Science.gov

Sample records for absolute velocity model

  1. A California statewide three-dimensional seismic velocity model from both absolute and differential times

    USGS Publications Warehouse

    Lin, G.; Thurber, C.H.; Zhang, H.; Hauksson, E.; Shearer, P.M.; Waldhauser, F.; Brocher, T.M.; Hardebeck, J.

    2010-01-01

    We obtain a seismic velocity model of the California crust and uppermost mantle using a regional-scale double-difference tomography algorithm. We begin by using absolute arrival-time picks to solve for a coarse three-dimensional (3D) P velocity (VP) model with a uniform 30 km horizontal node spacing, which we then use as the starting model for a finer-scale inversion using double-difference tomography applied to absolute and differential pick times. For computational reasons, we split the state into 5 subregions with a grid spacing of 10 to 20 km and assemble our final statewide VP model by stitching together these local models. We also solve for a statewide S-wave model using S picks from both the Southern California Seismic Network and USArray, assuming a starting model based on the VP results and a VP=VS ratio of 1.732. Our new model has improved areal coverage compared with previous models, extending 570 km in the SW-NE directionand 1320 km in the NW-SE direction. It also extends to greater depth due to the inclusion of substantial data at large epicentral distances. Our VP model generally agrees with previous separate regional models for northern and southern California, but we also observe some new features, such as high-velocity anomalies at shallow depths in the Klamath Mountains and Mount Shasta area, somewhat slow velocities in the northern Coast Ranges, and slow anomalies beneath the Sierra Nevada at midcrustal and greater depths. This model can be applied to a variety of regional-scale studies in California, such as developing a unified statewide earthquake location catalog and performing regional waveform modeling.

  2. Dependency of slab geometry on absolute velocities and conditions for cyclicity: insights from numerical modelling

    NASA Astrophysics Data System (ADS)

    Gibert, G.; Gerbault, M.; Hassani, R.; Tric, E.

    2012-05-01

    The aim of this study is to quantify the relationship between the kinematics of subduction, deformation in the overriding plate and the evolution of slab geometry. A 2-D finite element numerical code is used, and a first objective consists in benchmarking previously published analogue models. Far-field plate velocities are applied, and once the subducting plate reaches the 660 km discontinuity, modelled as a rigid base, we obtain two different forms or styles of subduction that depend on the overriding plate velocity vop: if vop > 0, the slab lies forwards on the 660 km discontinuity (style 1), and if vop≤ 0, the slab lies backwards on the discontinuity (style 2). We also obtain a cyclic pattern with the slab folding on itself repeatedly when vsp > 0 and 2vop+vsp > 0 (where vsp is the subducting plate velocity). These conditions result from the analysis of several simulations in which the subduction velocities and plate viscosities are varied. When the slab periodically folds on the 660 km discontinuity, periods of shallow slab dip and compression in the overriding plate are followed by periods of slab steepening and relative extension in the overriding plate. Folding periodicity is controlled by the slab viscosity and subduction velocity. When a low-viscosity zone is included in the overriding plate, the trench motion is effectively decoupled from the overriding plate velocity, therefore allowing it to be directly controlled by the deep dynamics of the slab. For the cyclic style 2 corresponding to forward folding of the slab, the low-viscosity region in the overriding plate increases the stress amplitudes oscillations, the trench motion and the folding periodicity with time. Therefore the strength of the entire overriding plate is shown to directly control the dynamics of subduction. Using the Nazca and South American plate velocities we produce models of cyclic folding with a period of ca. 22 Ma and a minimal dip angle of ca. 10°. Episodic folding of the slab

  3. Standardization of the cumulative absolute velocity

    SciTech Connect

    O'Hara, T.F.; Jacobson, J.P. )

    1991-12-01

    EPRI NP-5930, A Criterion for Determining Exceedance of the Operating Basis Earthquake,'' was published in July 1988. As defined in that report, the Operating Basis Earthquake (OBE) is exceeded when both a response spectrum parameter and a second damage parameter, referred to as the Cumulative Absolute Velocity (CAV), are exceeded. In the review process of the above report, it was noted that the calculation of CAV could be confounded by time history records of long duration containing low (nondamaging) acceleration. Therefore, it is necessary to standardize the method of calculating CAV to account for record length. This standardized methodology allows consistent comparisons between future CAV calculations and the adjusted CAV threshold value based upon applying the standardized methodology to the data set presented in EPRI NP-5930. The recommended method to standardize the CAV calculation is to window its calculation on a second-by-second basis for a given time history. If the absolute acceleration exceeds 0.025g at any time during each one second interval, the earthquake records used in EPRI NP-5930 have been reanalyzed and the adjusted threshold of damage for CAV was found to be 0.16g-set.

  4. Absolute blood velocity measured with a modified fundus camera

    NASA Astrophysics Data System (ADS)

    Duncan, Donald D.; Lemaillet, Paul; Ibrahim, Mohamed; Nguyen, Quan Dong; Hiller, Matthias; Ramella-Roman, Jessica

    2010-09-01

    We present a new method for the quantitative estimation of blood flow velocity, based on the use of the Radon transform. The specific application is for measurement of blood flow velocity in the retina. Our modified fundus camera uses illumination from a green LED and captures imagery with a high-speed CCD camera. The basic theory is presented, and typical results are shown for an in vitro flow model using blood in a capillary tube. Subsequently, representative results are shown for representative fundus imagery. This approach provides absolute velocity and flow direction along the vessel centerline or any lateral displacement therefrom. We also provide an error analysis allowing estimation of confidence intervals for the estimated velocity.

  5. Standardization of the cumulative absolute velocity. Final report

    SciTech Connect

    O`Hara, T.F.; Jacobson, J.P.

    1991-12-01

    EPRI NP-5930, ``A Criterion for Determining Exceedance of the Operating Basis Earthquake,`` was published in July 1988. As defined in that report, the Operating Basis Earthquake (OBE) is exceeded when both a response spectrum parameter and a second damage parameter, referred to as the Cumulative Absolute Velocity (CAV), are exceeded. In the review process of the above report, it was noted that the calculation of CAV could be confounded by time history records of long duration containing low (nondamaging) acceleration. Therefore, it is necessary to standardize the method of calculating CAV to account for record length. This standardized methodology allows consistent comparisons between future CAV calculations and the adjusted CAV threshold value based upon applying the standardized methodology to the data set presented in EPRI NP-5930. The recommended method to standardize the CAV calculation is to window its calculation on a second-by-second basis for a given time history. If the absolute acceleration exceeds 0.025g at any time during each one second interval, the earthquake records used in EPRI NP-5930 have been reanalyzed and the adjusted threshold of damage for CAV was found to be 0.16g-set.

  6. Radial velocity studies and absolute parameters of contact binaries. I - AB Andromedae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    1988-01-01

    New radial velocity curves have been obtained for the contact binary AB And, using the cross-correlation technique. A mass ratio of 0.479 is determined, which is revised to 0.491 when the velocities are corrected for proximity effects using a light curve model. These values differ by less than ten percent from the photometric mass ratio. An analysis of the symmetric B and V light curves reported by Rigterink in 1973 using the spectroscopic mass ratio yields a consistent set of light and velocity curve elements. These also produce a reasonably good fit to the infrared J and K light curves reported by Jameson and Akinci in 1979. Absolute elements are determined, and these indicate that both components have a main-sequence internal structure. These absolute parameters, together with the Galactic kinematics, suggest an age for the system similar to or greater than that of the Sun.

  7. Absolute plate velocities from seismic anisotropy: Importance of correlated errors

    NASA Astrophysics Data System (ADS)

    Zheng, Lin; Gordon, Richard G.; Kreemer, Corné

    2014-09-01

    The errors in plate motion azimuths inferred from shear wave splitting beneath any one tectonic plate are shown to be correlated with the errors of other azimuths from the same plate. To account for these correlations, we adopt a two-tier analysis: First, find the pole of rotation and confidence limits for each plate individually. Second, solve for the best fit to these poles while constraining relative plate angular velocities to consistency with the MORVEL relative plate angular velocities. Our preferred set of angular velocities, SKS-MORVEL, is determined from the poles from eight plates weighted proportionally to the root-mean-square velocity of each plate. SKS-MORVEL indicates that eight plates (Amur, Antarctica, Caribbean, Eurasia, Lwandle, Somalia, Sundaland, and Yangtze) have angular velocities that differ insignificantly from zero. The net rotation of the lithosphere is 0.25 ± 0.11° Ma-1 (95% confidence limits) right handed about 57.1°S, 68.6°E. The within-plate dispersion of seismic anisotropy for oceanic lithosphere (σ = 19.2°) differs insignificantly from that for continental lithosphere (σ = 21.6°). The between-plate dispersion, however, is significantly smaller for oceanic lithosphere (σ = 7.4°) than for continental lithosphere (σ = 14.7°). Two of the slowest-moving plates, Antarctica (vRMS = 4 mm a-1, σ = 29°) and Eurasia (vRMS = 3 mm a-1, σ = 33°), have two of the largest within-plate dispersions, which may indicate that a plate must move faster than ≈ 5 mm a-1 to result in seismic anisotropy useful for estimating plate motion. The tendency of observed azimuths on the Arabia plate to be counterclockwise of plate motion may provide information about the direction and amplitude of superposed asthenospheric flow or about anisotropy in the lithospheric mantle.

  8. Modeling Terminal Velocity

    ERIC Educational Resources Information Center

    Brand, Neal; Quintanilla, John A.

    2013-01-01

    Using a simultaneously falling softball as a stopwatch, the terminal velocity of a whiffle ball can be obtained to surprisingly high accuracy with only common household equipment. This classroom activity engages students in an apparently daunting task that nevertheless is tractable, using a simple model and mathematical techniques at their…

  9. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography.

    PubMed

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D; Chen, Zhongping

    2016-02-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing the vessel geometry, is derived analytically by localizing the artery from pure DOCT images through vessel segmentation and skeletonization. Our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches. Experiments on rodents using swept-source optical coherence tomography showed that our approach was able to reveal the consequences of permanent MCA occlusion with absolute BFV measurement. PMID:26977365

  10. Fully distributed absolute blood flow velocity measurement for middle cerebral arteries using Doppler optical coherence tomography

    PubMed Central

    Qi, Li; Zhu, Jiang; Hancock, Aneeka M.; Dai, Cuixia; Zhang, Xuping; Frostig, Ron D.; Chen, Zhongping

    2016-01-01

    Doppler optical coherence tomography (DOCT) is considered one of the most promising functional imaging modalities for neuro biology research and has demonstrated the ability to quantify cerebral blood flow velocity at a high accuracy. However, the measurement of total absolute blood flow velocity (BFV) of major cerebral arteries is still a difficult problem since it is related to vessel geometry. In this paper, we present a volumetric vessel reconstruction approach that is capable of measuring the absolute BFV distributed along the entire middle cerebral artery (MCA) within a large field-of-view. The Doppler angle at each point of the MCA, representing the vessel geometry, is derived analytically by localizing the artery from pure DOCT images through vessel segmentation and skeletonization. Our approach could achieve automatic quantification of the fully distributed absolute BFV across different vessel branches. Experiments on rodents using swept-source optical coherence tomography showed that our approach was able to reveal the consequences of permanent MCA occlusion with absolute BFV measurement. PMID:26977365

  11. First Absolutely Calibrated Localized Measurements of Ion Velocity in the MST in Locked and Rotating Plasmas

    NASA Astrophysics Data System (ADS)

    Baltzer, M.; Craig, D.; den Hartog, D. J.; Nornberg, M. D.; Munaretto, S.

    2015-11-01

    An Ion Doppler Spectrometer (IDS) is used on MST for high time-resolution passive and active measurements of impurity ion emission. Absolutely calibrated measurements of flow are difficult because the spectrometer records data within 0.3 nm of the C+5 line of interest, and commercial calibration lamps do not produce lines in this narrow range . A novel optical system was designed to absolutely calibrate the IDS. The device uses an UV LED to produce a broad emission curve in the desired region. A Fabry-Perot etalon filters this light, cutting transmittance peaks into the pattern of the LED emission. An optical train of fused silica lenses focuses the light into the IDS with f/4. A holographic diffuser blurs the light cone to increase homogeneity. Using this light source, the absolute Doppler shift of ion emissions can be measured in MST plasmas. In combination with charge exchange recombination spectroscopy, localized ion velocities can now be measured. Previously, a time-averaged measurement along the chord bisecting the poloidal plane was used to calibrate the IDS; the quality of these central chord calibrations can be characterized with our absolute calibration. Calibration errors may also be quantified and minimized by optimizing the curve-fitting process. Preliminary measurements of toroidal velocity in locked and rotating plasmas will be shown. This work has been supported by the US DOE.

  12. Absolute velocity measurement using three-beam spectral-domain Doppler optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Sharma, P.; Verma, Y.; Kumar, S.; Gupta, P. K.

    2015-09-01

    We report the development of a three-beam spectral-domain Doppler optical coherence tomography setup that allows single interferometer-based measurement of absolute flow velocity. The setup makes use of galvo-based phase shifting to remove complex conjugate mirror artifact and a beam displacer in the sample arm to avoid cross talk image. The results show that the developed approach allows efficient utilization of the imaging range of the spectral-domain optical coherence tomography setup for three-beam-based velocity measurement.

  13. Absolute total and partial dissociative cross sections of pyrimidine at electron and proton intermediate impact velocities

    SciTech Connect

    Wolff, Wania Luna, Hugo; Sigaud, Lucas; Montenegro, Eduardo C.; Tavares, Andre C.

    2014-02-14

    Absolute total non-dissociative and partial dissociative cross sections of pyrimidine were measured for electron impact energies ranging from 70 to 400 eV and for proton impact energies from 125 up to 2500 keV. MOs ionization induced by coulomb interaction were studied by measuring both ionization and partial dissociative cross sections through time of flight mass spectrometry and by obtaining the branching ratios for fragment formation via a model calculation based on the Born approximation. The partial yields and the absolute cross sections measured as a function of the energy combined with the model calculation proved to be a useful tool to determine the vacancy population of the valence MOs from which several sets of fragment ions are produced. It was also a key point to distinguish the dissociation regimes induced by both particles. A comparison with previous experimental results is also presented.

  14. SAR image registration in absolute coordinates using GPS carrier phase position and velocity information

    SciTech Connect

    Burgett, S.; Meindl, M.

    1994-09-01

    It is useful in a variety of military and commercial application to accurately register the position of synthetic aperture radar (SAR) imagery in absolute coordinates. The two basic SAR measurements, range and doppler, can be used to solve for the position of the SAR image. Imprecise knowledge of the SAR collection platform`s position and velocity vectors introduce errors in the range and doppler measurements and can cause the apparent location of the SAR image on the ground to be in error by tens of meters. Recent advances in carrier phase GPS techniques can provide an accurate description of the collection vehicle`s trajectory during the image formation process. In this paper, highly accurate carrier phase GPS trajectory information is used in conjunction with SAR imagery to demonstrate a technique for accurate registration of SAR images in WGS-84 coordinates. Flight test data will be presented that demonstrates SAR image registration errors of less than 4 meters.

  15. Long-Period Ground Motion Prediction Equations for Relative, Pseudo-Relative and Absolute Velocity Response Spectra in Japan

    NASA Astrophysics Data System (ADS)

    Dhakal, Y. P.; Kunugi, T.; Suzuki, W.; Aoi, S.

    2014-12-01

    Many of the empirical ground motion prediction equations (GMPE) also known as attenuation relations have been developed for absolute acceleration or pseudo relative velocity response spectra. For a small damping, pseudo and absolute acceleration response spectra are nearly identical and hence interchangeable. It is generally known that the relative and pseudo relative velocity response spectra differ considerably at very short or very long periods, and the two are often considered similar at intermediate periods. However, observations show that the period range at which the two spectra become comparable is different from site to site. Also, the relationship of the above two types of velocity response spectra with absolute velocity response spectra are not discussed well in literature. The absolute velocity response spectra are the peak values of time histories obtained by adding the ground velocities to relative velocity response time histories at individual natural periods. There exists many tall buildings on huge and deep sedimentary basins such as the Kanto basin, and the number of such buildings is growing. Recently, Japan Meteorological Agency (JMA) has proposed four classes of long-period ground motion intensity (http://www.data.jma.go.jp/svd/eew/data/ltpgm/) based on absolute velocity response spectra, which correlate to the difficulty of movement of people in tall buildings. As the researchers are using various types of response spectra for long-period ground motions, it is important to understand the relationships between them to take appropriate measures for disaster prevention applications. In this paper, we, therefore, obtain and discuss the empirical attenuation relationships using the same functional forms for the three types of velocity response spectra computed from observed strong motion records from moderate to large earthquakes in relation to JMA magnitude, hypocentral distance, sediment depths, and AVS30 as predictor variables at periods between

  16. Geostatistical Modeling of Pore Velocity

    SciTech Connect

    Devary, J.L.; Doctor, P.G.

    1981-06-01

    A significant part of evaluating a geologic formation as a nuclear waste repository involves the modeling of contaminant transport in the surrounding media in the event the repository is breached. The commonly used contaminant transport models are deterministic. However, the spatial variability of hydrologic field parameters introduces uncertainties into contaminant transport predictions. This paper discusses the application of geostatistical techniques to the modeling of spatially varying hydrologic field parameters required as input to contaminant transport analyses. Kriging estimation techniques were applied to Hanford Reservation field data to calculate hydraulic conductivity and the ground-water potential gradients. These quantities were statistically combined to estimate the groundwater pore velocity and to characterize the pore velocity estimation error. Combining geostatistical modeling techniques with product error propagation techniques results in an effective stochastic characterization of groundwater pore velocity, a hydrologic parameter required for contaminant transport analyses.

  17. Radial velocity studies and absolute parameters of contact binaries. II - OO Aquilae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    1989-01-01

    New high-precision radial velocities of the contact binary OO Aql have been obtained using the cross-correlation technique. The orbital elements have been corrected for proximity effects, using an analysis of published light curves of the system. The spectroscopically determined mass ratio of 0.843 is in excellent agreement with the photometrically determined value. OO Aql thus has one of the largest mass ratios observed for a contact binary. In contrast to almost all other contact binaries of G spectral type, the primary minimum is due to a transit by the less massive component, and thus the system is classified as an A-type contact binary. Absolute parameters are determined for OO Aql, which indicate that the primary component, although similar to the Sun in mass, is significantly more evolved. An age of about 8 Gyr and a metal abundance of one-half that of the Sun are determined. It seems that the system may have only recently evolved into contact, as suggested by Mochnacki, and that it is an important object for studies of the structure and evolution of contact binaries.

  18. Study on Cumulative Absolute Velocity as Operating Basis Earthquake Criteria to Nuclear Power Plants in Korea

    NASA Astrophysics Data System (ADS)

    Park, D.; Yun, K.; Chang, C.; Cho, S.; Choi, W.

    2013-12-01

    In recognition of the need to develop a new criteria for determining when the operating basis earthquake(OBE) has been exceeded at nuclear power plants in Korea, cumulative absolute velocity(CAV) is introduced in this paper. CAV OBE was determined as the minimum CAV value for the modified Mercalli intensity(MMI) VII based on the relation between the CAV and the seismic intensity. The MMI VII intensity can be defined as the ground-motion level that could cause a minor damage to a well-designed structure. Therefore, no damage to the more rugged NPP structure, which is reinforced against earthquakes, will be guaranteed if the minimum CAV value is used as a threshold of OBE exceedance criteria. In deriving the CAV OBE exceedance criteria, it is necessary to generate a suite of simulated ground-motions for a range of earthquake magnitudes and calibrated distances to the site. It is also necessary to use an instrumental MMI intensity of Fourier acceleration spectra(FAS) MMI because there have been no strong ground-motion records or experienced intensity data from damaging earthquakes in Korea. The empirical Green's function method and stochastic ground motion simulation method is used to simulate ground motion. Based on the relation between the CAV values given for a specific NPP site and the values for the instrumental MMI intensity (FAS MMI), the CAV OBE value was calculated as 0.16g.sec. However, since this result is totally based on the simulation, there still remains a margin of the CAV threshold value that must consider characteristics of the real strong ground-motion records. For the future work, data on the limited earthquake damage reported in Korea will be used to validate the simulated CAV values.

  19. ELLIPSOIDAL VARIABLE V1197 ORIONIS: ABSOLUTE LIGHT-VELOCITY ANALYSIS FOR KNOWN DISTANCE

    SciTech Connect

    Wilson, R. E.; Chochol, D.; KomzIk, R.; Van Hamme, W.; Pribulla, T.; Volkov, I.

    2009-09-01

    V1197 Orionis light curves from a long-term observing program for red giant binaries show ellipsoidal variation of small amplitude in the V and R{sub C} bands, although not clearly in U and B. Eclipses are not detected. All four bands show large irregular intrinsic variations, including fleeting quasi-periodicities identified by power spectra, that degrade analysis and may be caused by dynamical tides generated by orbital eccentricity. To deal with the absence of eclipses and consequent lack of astrophysical and geometrical information, direct use is made of the Hipparcos parallax distance while the V and R{sub C} light curves and (older) radial velocity curves are analyzed simultaneously in terms of absolute flux. The red giant's temperature is estimated from new spectra. This type of analysis, called Inverse Distance Estimation for brevity, is new and can also be applied to other ellipsoidal variables. Advantages gained by utilization of definite distance and temperature are discussed in regard to how radius, fractional lobe filling, and mass ratio information are expressed in the observations. The advantages were tested in solutions of noisy synthetic data. Also discussed and tested by simulations are ideas on the optimal number of light curves to be solved simultaneously under various conditions. The dim companion has not been observed or discussed in the literature but most solutions find its mass to be well below that of the red giant. Solutions show red giant masses that are too low for evolution to the red giant stage within the age of the Galaxy, although that result is probably an artifact of the intrinsic brightness fluctuations.

  20. Two-stage model of African absolute motion during the last 30 million years

    NASA Astrophysics Data System (ADS)

    Pollitz, Fred F.

    1991-07-01

    The absolute motion of Africa (relative to the hotspots) for the past 30 My is modeled with two Euler vectors, with a change occurring at 6 Ma. Because of the high sensitivity of African absolute motions to errors in the absolute motions of the North America and Pacific plates, both the pre-6 Ma and post-6 Ma African absolute motions are determined simultaneously with North America and Pacific absolute motions for various epochs. Geologic data from the northern Atlantic and hotspot tracks from the African plate are used to augment previous data sets for the North America and Pacific plates. The difference between the pre-6 Ma and post-6 Ma absolute plate motions may be represented as a counterclockwise rotation about a pole at 48 °S, 84 °E, with angular velocity 0.085 °/My. This change is supported by geologic evidence along a large portion of the African plate boundary, including the Red Sea and Gulf of Aden spreading systems, the Alpine deformation zone, and the central and southern mid-Atlantic Ridge. Although the change is modeled as one abrupt transition at 6 Ma, it was most likely a gradual change spanning the period 8-4 Ma. As a likely mechanism for the change, we favor strong asthenospheric return flow from the Afar hotspot towards the southwest; this could produce the uniform southwesterly shift in absolute motion which we have inferred as well as provide a mechanism for the opening of the East African Rift. Comparing the absolute motions of the North America and Pacific plates with earlier estimates, the pole positions are revised by up to 5° and the angular velocities are decreased by 10-20%.

  1. Revisiting absolute and relative judgments in the WITNESS model.

    PubMed

    Fife, Dustin; Perry, Colton; Gronlund, Scott D

    2014-04-01

    The WITNESS model (Clark in Applied Cognitive Psychology 17:629-654, 2003) provides a theoretical framework with which to investigate the factors that contribute to eyewitness identification decisions. One key factor involves the contributions of absolute versus relative judgments. An absolute contribution is determined by the degree of match between an individual lineup member and memory for the perpetrator; a relative contribution involves the degree to which the best-matching lineup member is a better match to memory than the remaining lineup members. In WITNESS, the proportional contributions of relative versus absolute judgments are governed by the values of the decision weight parameters. We conducted an exploration of the WITNESS model's parameter space to determine the identifiability of these relative/absolute decision weight parameters, and compared the results to a restricted version of the model that does not vary the decision weight parameters. This exploration revealed that the decision weights in WITNESS are difficult to identify: Data often can be fit equally well by setting the decision weights to nearly any value and compensating with a criterion adjustment. Clark, Erickson, and Breneman (Law and Human Behavior 35:364-380, 2011) claimed to demonstrate a theoretical basis for the superiority of lineup decisions that are based on absolute contributions, but the relationship between the decision weights and the criterion weakens this claim. These findings necessitate reconsidering the role of the relative/absolute judgment distinction in eyewitness decision making. PMID:23943556

  2. Detecting absolute human knee angle and angular velocity using accelerometers and rate gyroscopes.

    PubMed

    Williamson, R; Andrews, B J

    2001-05-01

    Knee joint angle and angular velocity were calculated in real time during standing up and sitting down. Two small modules comprising rate gyroscopes and accelerometers were attached to the thigh and shank of two able-bodied volunteers and one T5 ASIA(A) paraplegic assisted by functional electrical stimulation (FES). The offset and drift of the rate gyroscopes was compensated for by auto-resetting and auto-nulling algorithms. The tilt of the limb segments was calculated by combining the signals of the accelerometer and the rate gyroscope. The joint angle was calculated as the difference in tilt of the segments. The modules were also tested on a two-dimensional model. The mean differences between the rate gyroscope-accelerometer system and the reference goniometer for the model, able-bodied and paraplegic standing trials were 2.1 degrees, 2.4 degrees and 2.3 degrees respectively for knee angle and 2.3 degrees s(-1), 5.0 degrees s(-1) and 11.8 degrees s(-1) respectively for knee velocity. The rate gyroscope-accelerometer system was more accurate than using the accelerometer as a tilt meter, possibly due to the greater bandwidth of the rate gyroscope-accelerometer system. PMID:11465883

  3. A general relativistic model for free-fall absolute gravimeters

    NASA Astrophysics Data System (ADS)

    Tan, Yu-Jie; Shao, Cheng-Gang; Li, Jia; Hu, Zhong-Kun

    2016-04-01

    Although the relativistic manifestations of gravitational fields in gravimetry were first studied 40 years ago, the relativistic effects combined with free-fall absolute gravimeters have rarely been considered. In light of this, we present a general relativistic model for free-fall absolute gravimeters in a local-Fermi coordinates system, where we focus on effects related to the measuring devices: relativistic transverse Doppler effects, gravitational redshift effects and Earth’s rotation effects. Based on this model, a general relativistic expression of the measured gravity acceleration is obtained.

  4. New GNSS velocity field and preliminary velocity model for Ecuador

    NASA Astrophysics Data System (ADS)

    Luna-Ludeña, Marco P.; Staller, Alejandra; Gaspar-Escribano, Jorge M.; Belén Benito, M.

    2016-04-01

    In this work, we present a new preliminary velocity model of Ecuador based on the GNSS data of the REGME network (continuous monitoring GNSS network). To date, there is no velocity model available for the country. The only existing model in the zone is the regional model VEMOS2009 for South America and Caribbean (Drewes and Heidbach, 2012). This model was developed from the SIRGAS station positions, the velocities of the SIRGAS-CON stations, and several geodynamics projects performed in the region. Just two continuous GNSS (cGNSS) stations of Ecuador were taking into account in the VEMOS2009 model. The first continuous station of the REGME network was established in 2008. At present, it is composed by 32 continuous GNSS stations, covering the country. All the stations provided data during at least two years. We processed the data of the 32 GNSS stations of REGME for the 2008-2014 period, as well as 20 IGS stations in order to link to the global reference frame IGb08 (ITRF2008). GPS data were processed using Bernese 5.0 software (Dach et al., 2007). We obtained and analyzed the GNSS coordinate time series of the 32 REGME stations and we calculated the GPS-derived horizontal velocity field of the country. Velocities in ITRF2008 were transformed into a South American fixed reference frame, using the Euler pole calculated from 8 cGNSS stations throughout this plate. Our velocity field is consistent with the tectonics of the country and contributes to a better understanding of it. From the horizontal velocity field, we determined a preliminary model using the kriging geostatistical technique. To check the results we use the cross-validation method. The differences between the observed and estimated values range from ± 5 mm. This is a new velocity model obtained from GNSS data for Ecuador.

  5. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Lee, Chung-Uk; Kim, Chun-Hwey; Kang, Young-Beom; Koo, Jae-Rim

    2004-12-01

    We completed the light curves of the contact binary CK Boo for 13 nights from June to July in 2004 using the 1-m reflector and BVR filters at Mt. Lemmon Optical Astronomy Observatory, and determined four new times of minimum light (three timings for primary eclipse, one for secondary). With contact mode of the 1998-version Wilson-Devinney binary model, we analyzed our BVR light curves and Rucinski & Lu (1999)'s radial-velocity ones. As a result, we found CK boo to be A-type overcontact binary (f=84%) with the low mass ratio (q=0.11) and orbital inclination (i=65°). Absolute dimensions of the system are determined from our new solution; M1=1.42M⊙, M2=0.15M⊙, R1=1.47R⊙, R2=0.59M⊙, and the distance to it is derived as about 129pc. Our distance is well consistent with that (157±33pc) from the Hipparcos trigonometric parallax within the limit of the error yielded by the latter.

  6. Electroweak absolute, meta-, and thermal stability in neutrino mass models

    NASA Astrophysics Data System (ADS)

    Lindner, Manfred; Patel, Hiren H.; Radovčić, Branimir

    2016-04-01

    We analyze the stability of the electroweak vacuum in neutrino mass models containing right-handed neutrinos or fermionic isotriplets. In addition to considering absolute stability, we place limits on the Yukawa couplings of new fermions based on metastability and thermal stability in the early Universe. Our results reveal that the upper limits on the neutrino Yukawa couplings can change significantly when the top quark mass is allowed to vary within the experimental range of uncertainty in its determination.

  7. Newberry EGS Seismic Velocity Model

    DOE Data Explorer

    Templeton, Dennise

    2013-10-01

    We use ambient noise correlation (ANC) to create a detailed image of the subsurface seismic velocity at the Newberry EGS site down to 5 km. We collected continuous data for the 22 stations in the Newberry network, together with 12 additional stations from the nearby CC, UO and UW networks. The data were instrument corrected, whitened and converted to single bit traces before cross correlation according to the methodology in Benson (2007). There are 231 unique paths connecting the 22 stations of the Newberry network. The additional networks extended that to 402 unique paths crossing beneath the Newberry site.

  8. Measured and modelled absolute gravity changes in Greenland

    NASA Astrophysics Data System (ADS)

    Nielsen, J. Emil; Forsberg, Rene; Strykowski, Gabriel

    2014-01-01

    In glaciated areas, the Earth is responding to the ongoing changes of the ice sheets, a response known as glacial isostatic adjustment (GIA). GIA can be investigated through observations of gravity change. For the ongoing assessment of the ice sheets mass balance, where satellite data are used, the study of GIA is important since it acts as an error source. GIA consists of three signals as seen by a gravimeter on the surface of the Earth. These signals are investigated in this study. The ICE-5G ice history and recently developed ice models of present day changes are used to model the gravity change in Greenland. The result is compared with the initial measurements of absolute gravity (AG) change at selected Greenland Network (GNET) sites.

  9. Gravitational constant is likely dependent on the absolute velocity of galaxy

    NASA Astrophysics Data System (ADS)

    Chen, Shao-Guang

    In my paper ‘Quanta turn-advance ism, China Science && Technology Overview 131 192-210 (2011)’, QFT four-dimensional uncertainty principle and momentum-energy conservation law had been generalized as a five-dimensional equations: de Broglie wavelength as a position vector \\underline{q}= (i c t, r, s), momentum \\underline{P} = (i E/c, P, U c), \\underline{q} = i h / \\underline{P}, \\underline{q} \\underline{q} = 0, \\underline{P} \\underline{P} = 0, Sigma∑\\underline{P} = \\underline{P} (0) . The five-dimensional time-space-spin had been quantized as a non-dot model basic cell, the lowest energy state vertical polarized left spin 1/2 neutrino and right spin 1/2 antineutrino are just the left, right advance unit quanta _{0}nuυ, nuυ _{0} and left, right back unit quanta (0) nuυ, nuυ (0) , it again compose into spin 1 unit advance photon _{0}nuυnuυ _{0} and back (0) nuυnuυ (0) , spin 0 unit rest mass nuυ _{0}nuυ (0) and anti-mass _{0}nuυ (0) nuυ, spin 0 unit positive charge _{0}nuυnuυ (0) and negative charge nuυ _{0} (0) nuυ. It accord to the high energy physics experiment results of the transformation among the photons, masses quanta and charges quanta. The physical vacuum is the even collocation of non-combinational nuυ _{0} or _{0}nuυ. It is mathematically easy that from five-dimensional equations deduce out the Dirac, Klein-Gordan, Maxwell equations and Lorentz force formula, but appear some new results. The interactions between _{0}nuυ, nuυ _{0}, (0) nuυ, nuυ (0) , i.e., force f = ± ( h c / 2 r (3) ) r cos thetaθ for r not equal to 0 and f = 0 for r = 0, f as the magnetic force makes the photons, rest mass and charge quanta automatically come into being and stabilize. QFT no longer with divergence difficulty by the non-dot model. The explanation of abnormal magnetic moment and Lamb shift is more natural and simple only with the spin — the conjunction between turn and advance. Many testable results had been obtained. In the

  10. Lunar eclipse photometry: absolute luminance measurements and modeling.

    PubMed

    Hernitschek, Nina; Schmidt, Elmar; Vollmer, Michael

    2008-12-01

    The Moon's time-dependent luminance was determined during the 9 February 1990 and 3 March 2007 total lunar eclipses by using calibrated, industry standard photometers. After the results were corrected to unit air mass and to standard distances for both Moon and Sun, an absolute calibration was accomplished by using the Sun's known luminance and a pre-eclipse lunar albedo of approximately 13.5%. The measured minimum level of brightness in the total phase of both eclipses was relatively high, namely -3.32 m(vis) and -1.7 m(vis), which hints at the absence of pronounced stratospheric aerosol. The light curves were modeled in such a way as to let the Moon move through an artificial Earth shadow composed of a multitude of disk and ring zones, containing a relative luminance data set from an atmospheric radiative transfer calculation. PMID:19037352

  11. Velocity-jump models with crowding effects

    NASA Astrophysics Data System (ADS)

    Treloar, Katrina K.; Simpson, Matthew J.; McCue, Scott W.

    2011-12-01

    Velocity-jump processes are discrete random-walk models that have many applications including the study of biological and ecological collective motion. In particular, velocity-jump models are often used to represent a type of persistent motion, known as a run and tumble, that is exhibited by some isolated bacteria cells. All previous velocity-jump processes are noninteracting, which means that crowding effects and agent-to-agent interactions are neglected. By neglecting these agent-to-agent interactions, traditional velocity-jump models are only applicable to very dilute systems. Our work is motivated by the fact that many applications in cell biology, such as wound healing, cancer invasion, and development, often involve tissues that are densely packed with cells where cell-to-cell contact and crowding effects can be important. To describe these kinds of high-cell-density problems using a velocity-jump process we introduce three different classes of crowding interactions into a one-dimensional model. Simulation data and averaging arguments lead to a suite of continuum descriptions of the interacting velocity-jump processes. We show that the resulting systems of hyperbolic partial differential equations predict the mean behavior of the stochastic simulations very well.

  12. Absolute masses and radii determination in multiplanetary systems without stellar models

    NASA Astrophysics Data System (ADS)

    Almenara, J. M.; Díaz, R. F.; Mardling, R.; Barros, S. C. C.; Damiani, C.; Bruno, G.; Bonfils, X.; Deleuil, M.

    2015-11-01

    The masses and radii of extrasolar planets are key observables for understanding their interior, formation and evolution. While transit photometry and Doppler spectroscopy are used to measure the radii and masses respectively of planets relative to those of their host star, estimates for the true values of these quantities rely on theoretical models of the host star which are known to suffer from systematic differences with observations. When a system is composed of more than two bodies, extra information is contained in the transit photometry and radial velocity data. Velocity information (finite speed-of-light, Doppler) is needed to break the Newtonian MR-3 degeneracy. We performed a photodynamical modelling of the two-planet transiting system Kepler-117 using all photometric and spectroscopic data available. We demonstrate how absolute masses and radii of single-star planetary systems can be obtained without resorting to stellar models. Limited by the precision of available radial velocities (38 m s-1), we achieve accuracies of 20 per cent in the radii and 70 per cent in the masses, while simulated 1 m s-1 precision radial velocities lower these to 1 per cent for the radii and 2 per cent for the masses. Since transiting multiplanet systems are common, this technique can be used to measure precisely the mass and radius of a large sample of stars and planets. We anticipate these measurements will become common when the TESS and PLATO mission provide high-precision light curves of a large sample of bright stars. These determinations will improve our knowledge about stars and planets, and provide strong constraints on theoretical models.

  13. Age Dependent Absolute Plate and Plume Motion Modeling

    NASA Astrophysics Data System (ADS)

    Heaton, D. E.; Koppers, A. A. P.

    2015-12-01

    Current absolute plate motion (APM) models from 80 - 0 Ma are constrained by the location of mantle plume related hotspot seamounts, in particular those of the Hawaiian-Emperor and Louisville seamount trails. Originally the 'fixed' hotspot hypothesis was developed to explain past plate motion based on linear age progressive intra-plate volcanism. However, now that 'moving' hotspots are accepted, it is becoming clear that APM models need to be corrected for individual plume motion vectors. For older seamount trails that were active between roughly 50 and 80 Ma the APM models that use 'fixed' hotspots overestimate the measured age progression in those trails, while APM models corrected for 'moving' hotspots underestimate those age progressions. These mismatches are due to both a lack of reliable ages in the older portions of both the Hawaii and Louisville seamount trails and insufficient APM modeling constraints from other seamount trails in the Pacific Basin. Seamounts are difficult to sample and analyze because many are hydrothermally altered and have low potassium concentrations. New 40Ar/39Ar Age results from International Ocean Drilling Project (IODP) Expedition 330 Sites U1372 (n=18), U1375 (n=3), U1376 (n=15) and U1377 (n=7) aid in constraining the oldest end of the Louisville Seamount trail. A significant observation in this study is that the age range recovered in the drill cores match the range of ages that were acquired on dredging cruises at the same seamounts (e.g. Koppers et al., 2011). This is important for determining the inception age of a seamount. The sections recovered from IODP EXP 330 are in-situ volcanoclastic breccia and lava flows. Comparing the seismic interpretations of Louisville guyots (Contreras-Reyes et al., 2010), Holes U1372, U1373 and U1374 penetrated the extrusive and volcanoclastic sections of the seamount. The ages obtained are consistent over stratigraphic intervals >100-450 m thick, providing evidence that these seamounts

  14. Velocity model of the shallow lunar crust

    NASA Technical Reports Server (NTRS)

    Gangi, A. F.

    1980-01-01

    The travel times of the seismic waves obtained for the Apollo-14 and -16 active seismic experiments and the Apollo-16 grenade launches are shown to be consistent with a powder-layer model of the shallow lunar crust. The velocity variation with depth determined from these data is: V(z) = approximately 110 z to the 1/6 power m/sec for z less than 10 meters and V(z) is nearly = to 250 m/sec for z greater than 10 meters. The velocity values found for the 10 meter depth are similar to those found by Kovach, et al. (1972). The z to the 1/6 power depth dependence for the velocity of the topmost layer is that predicted on the basis of a powder layer (Gangi, 1972). The Amplitude variation of the direct waves as a function of source-to-receiver separation, x, is A(x) = A(o)x to the -n power exp(-ax) where 1.5 n 2.2 and a is nearly = to 0.047 neper/m. Velocity-spectra analyses of the direct, surface-reflected, bottom-reflected and refracted waves give results that are consistent with the velocity model inferred from the traveltime data.

  15. Mathematical Model for Absolute Magnetic Measuring Systems in Industrial Applications

    NASA Astrophysics Data System (ADS)

    Fügenschuh, Armin; Fügenschuh, Marzena; Ludszuweit, Marina; Mojsic, Aleksandar; Sokół, Joanna

    2015-09-01

    Scales for measuring systems are either based on incremental or absolute measuring methods. Incremental scales need to initialize a measurement cycle at a reference point. From there, the position is computed by counting increments of a periodic graduation. Absolute methods do not need reference points, since the position can be read directly from the scale. The positions on the complete scales are encoded using two incremental tracks with different graduation. We present a new method for absolute measuring using only one track for position encoding up to micrometre range. Instead of the common perpendicular magnetic areas, we use a pattern of trapezoidal magnetic areas, to store more complex information. For positioning, we use the magnetic field where every position is characterized by a set of values measured by a hall sensor array. We implement a method for reconstruction of absolute positions from the set of unique measured values. We compare two patterns with respect to uniqueness, accuracy, stability and robustness of positioning. We discuss how stability and robustness are influenced by different errors during the measurement in real applications and how those errors can be compensated.

  16. Determinations of its Absolute Dimensions and Distance by the Analyses of Light and Radial-Velocity Curves of the Contact Binary -I. V417 Aquilae

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Kim, Chun-Hwey; Lee, Chung-Uk; Oh, Kyu-Dong

    2004-06-01

    New photometric and spectroscopic solutions of W-type overcontact binary V417 Aql were obtained by solving the UBV light curves of Samec et al. (1997) and radial-velocity ones of Lu & Rucinski (1999) with the 2003 version of the Wilson-Devinney binary code. In the light curve synthesis the light of a third-body, which Qian (2003) proposed, was considered and obtained about 2.7%, 2.2%, and 0.4% for U, B, and V bandpasses, respectively. The model with third-light is better fitted to eclipse parts than that with no third-light. Absolute dimensions of V417 Aql are determined from our solution as M1=0.53 M⊙, M2=1.45 M⊙, R1=0.84 R⊙ and R2=1.31 M⊙, and the distance to it is deduced as about 216pc. Our distance is well consistent with that (204pc) derived from Rucinski & Duerbeck's (1997) relation, MV=MV(log P, B-V), but is more distant than that (131±40pc) determined by the Hipparcos trigonometric parallax. The difference may result from the relatively large error of Hipparcos parallax for V417 Aql.

  17. Relative and Absolute Fit Evaluation in Cognitive Diagnosis Modeling

    ERIC Educational Resources Information Center

    Chen, Jinsong; de la Torre, Jimmy; Zhang, Zao

    2013-01-01

    As with any psychometric models, the validity of inferences from cognitive diagnosis models (CDMs) determines the extent to which these models can be useful. For inferences from CDMs to be valid, it is crucial that the fit of the model to the data is ascertained. Based on a simulation study, this study investigated the sensitivity of various fit…

  18. Mapping Faults from 3-D Tomographic Velocity Model using Image Processing / Computer Vision Algorithms: Application to Northern Cascadia

    NASA Astrophysics Data System (ADS)

    Ramachandran, K.

    2011-12-01

    Three dimensional velocity models constructed through seismic tomography are seldom digitally processed further for imaging structural features. A study conducted to evaluate the potential for imaging subsurface discontinuities in horizontal and vertical direction from three dimensional velocity models using image processing/computer vision techniques has provided significant results. Three-dimensional velocity models constructed through tomographic inversion of active source and/or earthquake traveltime data are generally built from an initial 1-D velocity model that varies only with depth. Regularized tomographic inversion algorithms impose constraints on the roughness of the model that help to stabilize the inversion process. Final velocity models obtained from regularized tomographic inversions have smooth three-dimensional structures that are required by the data. Final velocity models are usually analyzed and interpreted either as a perturbation velocity model or as an absolute velocity model. Compared to perturbation velocity model, absolute velocity model has an advantage of providing constraints on lithology. Both velocity models lack the ability to provide sharp constraints on subsurface faults. However, results from the analysis of the 3-D velocity model from northern Cascadia using Roberts, Prewitt, Sobel, and Canny operators show that subsurface faults that are not clearly interpretable from velocity model plots can be identified through this approach. This analysis resulted in inferring the locations of Tacoma Fault, Seattle Fault, Southern Whidbey Island Fault, and Darrington Devils Mountain fault much clearly. The Coast Range Boundary Fault, previously hypothesized on the basis of sedimentological and tectonic observations is inferred clearly from processed images. Many of the fault locations so imaged correlate with earthquake hypocenters indicating their seismogenic nature.

  19. Absolute Entropy and Energy of Carbon Dioxide Using the Two-Phase Thermodynamic Model.

    PubMed

    Huang, Shao-Nung; Pascal, Tod A; Goddard, William A; Maiti, Prabal K; Lin, Shiang-Tai

    2011-06-14

    The two-phase thermodynamic (2PT) model is used to determine the absolute entropy and energy of carbon dioxide over a wide range of conditions from molecular dynamics trajectories. The 2PT method determines the thermodynamic properties by applying the proper statistical mechanical partition function to the normal modes of a fluid. The vibrational density of state (DoS), obtained from the Fourier transform of the velocity autocorrelation function, converges quickly, allowing the free energy, entropy, and other thermodynamic properties to be determined from short 20-ps MD trajectories. The anharmonic effects in the vibrations are accounted for by the broadening of the normal modes into bands from sampling the velocities over the trajectory. The low frequency diffusive modes, which lead to finite DoS at zero frequency, are accounted for by considering the DoS as a superposition of gas-phase and solid-phase components (two phases). The analytical decomposition of the DoS allows for an evaluation of properties contributed by different types of molecular motions. We show that this 2PT analysis leads to accurate predictions of entropy and energy of CO2 over a wide range of conditions (from the triple point to the critical point of both the vapor and the liquid phases along the saturation line). This allows the equation of state of CO2 to be determined, which is limited only by the accuracy of the force field. We also validated that the 2PT entropy agrees with that determined from thermodynamic integration, but 2PT requires only a fraction of the time. A complication for CO2 is that its equilibrium configuration is linear, which would have only two rotational modes, but during the dynamics it is never exactly linear, so that there is a third mode from rotational about the axis. In this work, we show how to treat such linear molecules in the 2PT framework. PMID:26596450

  20. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Marinke Hoppe, Charlotte; Ploeger, Felix; Konopka, Paul; Müller, Rolf

    2016-05-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer-Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the

  1. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Hoppe, C. M.; Ploeger, F.; Konopka, P.; Müller, R.

    2015-11-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large scale Brewer-Dobson-Circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Messy Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10 year simulation are provided for both, kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows younger mean age of air in the inner tropical upwelling branch and older mean age in the extratopical tropopause region.

  2. Crosswell born inversion for heterogeneous velocity models

    SciTech Connect

    Hegge, R.F.; Herman, G.C.; Sevink, A.G.J.

    1994-12-31

    The application of high-frequency asymptotic Born inverse scattering methods to cross-well imaging is discussed and illustrated with a number of model studies for synthetic data. In particular, attention is given to imaging problems that are associated with typical cross-well geometries. A severe problem is the existence of multiple travel paths between sources and receivers that are particularly apparent if low-velocity layers are present. When this occurs, the high-frequency asymptotic imaging method is no longer valid and large artifacts in the images can result. However, it is concluded that, even in the case of multiple travel paths, good images can be obtained by omitting the singularities in the imaging formula and by combining the results for different source locations.

  3. Ridge-spotting: A new test for Pacific absolute plate motion models

    NASA Astrophysics Data System (ADS)

    Wessel, Paul; Müller, R. Dietmar

    2016-06-01

    Relative plate motions provide high-resolution descriptions of motions of plates relative to other plates. Yet geodynamically, motions of plates relative to the mantle are required since such motions can be attributed to forces (e.g., slab pull and ridge push) acting upon the plates. Various reference frames have been proposed, such as the hot spot reference frame, to link plate motions to a mantle framework. Unfortunately, both accuracy and precision of absolute plate motion models lag behind those of relative plate motion models. Consequently, it is paramount to use relative plate motions in improving our understanding of absolute plate motions. A new technique called "ridge-spotting" combines absolute and relative plate motions and examines the viability of proposed absolute plate motion models. We test the method on six published Pacific absolute plate motions models, including fixed and moving hot spot models as well as a geodynamically derived model. Ridge-spotting reconstructs the Pacific-Farallon and Pacific-Antarctica ridge systems over the last 80 Myr. All six absolute plate motion models predict large amounts of northward migration and monotonic clockwise rotation for the Pacific-Farallon ridge. A geodynamic implication of our ridge migration predictions is that the suggestion that the Pacific-Farallon ridge may have been pinned by a large mantle upwelling is not supported. Unexpected or erratic ridge behaviors may be tied to limitations in the models themselves or (for Indo-Atlantic models) discrepancies in the plate circuits used to project models into the Pacific realm. Ridge-spotting is promising and will be extended to include more plates and other ocean basins.

  4. Phanerozoic within-plate magmatism of North Asia: Absolute paleogeographic reconstructions of the African large low-shear-velocity province

    NASA Astrophysics Data System (ADS)

    Kuz'min, M. I.; Yarmolyuk, V. V.; Kravchinsky, V. A.

    2011-11-01

    The phanerozoic within-plate magmatism of Siberia is reviewed. The large igneous provinces (LIPs) consecutively arising in the Siberian Craton are outlined: the Altai-Sayan LIP, which operated most actively 400-375 Ma ago, the Vilyui LIP, which was formed from the Middle Devonian to the Early Carboniferous, included; the Barguzin-Vitim LIP (305-275 Ma); the Late Paleozoic Rift System of Central Asia (318-250 Ma); the Siberian flood basalt (trap) province and the West Siberian rift system (250-247 Ma); and the East Mongolian-West Transbaikal LIP (230-195 Ma), as well as a number of Late-Mesozoic and Cenozoic rift zones and autonomous volcanic fields formed over the last 160 Ma. The trace-element and isotopic characteristics of the igneous rocks of the above provinces are reviewed; their mantle origin is substantiated and the prevalence of PREMA, EM2, and EM1 mantle magma sources are shown. The paleogeographic reconstructions based on paleomagnetic data assume that the Iceland hot spot was situated beneath the Siberian flood basalts 250 Ma ago and that the mantle plumes retained a relatively stable position irrespective of the movements of the lithospheric plates. At present, the Iceland hot spot occurs near the northern boundary of the African large low shear velocity province (LLSVP). It is suggested that the within-plate Phanerozoic magmatism of Siberia was related to the drift of the continent above the hot spots of the African LLSVP.

  5. Direct detection of neutral metal atoms in electron-stimulated desorption: Al from CH{sub 3}O/Al(111) - velocity distribution and absolute yield

    SciTech Connect

    Whitten, J.E.; Young, C.E.; Pellin, M.J.; Gruen, D.M.; Jones, P.L.

    1994-06-01

    Electron-stimulated desorption of neutral aluminum from the system CH{sub 3}O/Al(111) has been directly monitored via quasiresonant photoionization with 193 nm excimer laser light and confirmed by two-step resonant ionization, utilizing the Al 3d {sup 2}D manifold. Velocity distribution measurements for the neutral Al peak at {approximately} 800 m/s for 1 keV incident electron energy. An absolute yield of 3.2 x 10{sup {minus}6} Al atoms/electron was determined by comparison with sputtering measurements in the same apparatus. This is the first observation of electron-stimulated metal desorption from adsorbate-covered metallic surfaces.

  6. Influence of overriding plate velocity changes on slab dip and deformation: insights from laboratory models

    NASA Astrophysics Data System (ADS)

    Guillaume, Benjamin; Hertgen, Solenn; Martinod, Joseph

    2016-04-01

    Over geological times, plate reorganization associated with mantle convection led to changes in absolute plate velocities, which may in turn have impacted the geometry of the subducting plate as well as the overriding plate regime of deformation. Indeed, previous studies have shown a very good correlation between the absolute motion of the overriding plate on one hand and slab dip and overriding plate deformation on the other hand: extension and steep slab are associated with an overriding plate moving away from the trench while shortening and shallow slab occur if the upper plate goes the other way. However, these correlations are established when subduction has reached a steady-state regime and for a constant motion of the overriding plate over the subducting plate, which may not always be the case on Earth. The response of the subduction system to changes in absolute overriding plate velocity still remain an open question. In this study, we conducted a set of 3-D mantle-scale laboratory models of subduction in which we incrementally changed the velocity of the overriding plate to reproduce changes of velocities that may arise from variations of far-field boundary conditions in Nature. We first show that strain rates in the overriding plate are correlated with overriding plate absolute velocity but also that the regime of deformation adjusts rapidly to changes of velocity. This may explain for instance why despite the subduction has been continuous beneath South America since at least the middle Jurassic, shortening along its active margin is only recorded episodically, the main phases of Andean orogeny roughly corresponding to periods of South American plate westward acceleration. We also show that slab dip adjusts to changes of overriding plate velocity but it requires several Myr before it stabilizes. It may explain why the correlation between absolute overriding plate motion and slab dip from the analysis of present-day subduction zones is only moderate, part

  7. Constraint on Absolute Accuracy of Metacomprehension Assessments: The Anchoring and Adjustment Model vs. the Standards Model

    ERIC Educational Resources Information Center

    Kwon, Heekyung

    2011-01-01

    The objective of this study is to provide a systematic account of three typical phenomena surrounding absolute accuracy of metacomprehension assessments: (1) the absolute accuracy of predictions is typically quite low; (2) there exist individual differences in absolute accuracy of predictions as a function of reading skill; and (3) postdictions…

  8. Velocity statistics of the Nagel-Schreckenberg model.

    PubMed

    Bain, Nicolas; Emig, Thorsten; Ulm, Franz-Josef; Schreckenberg, Michael

    2016-02-01

    The statistics of velocities in the cellular automaton model of Nagel and Schreckenberg for traffic are studied. From numerical simulations, we obtain the probability distribution function (PDF) for vehicle velocities and the velocity-velocity (vv) covariance function. We identify the probability to find a standing vehicle as a potential order parameter that signals nicely the transition between free congested flow for a sufficiently large number of velocity states. Our results for the vv covariance function resemble features of a second-order phase transition. We develop a 3-body approximation that allows us to relate the PDFs for velocities and headways. Using this relation, an approximation to the velocity PDF is obtained from the headway PDF observed in simulations. We find a remarkable agreement between this approximation and the velocity PDF obtained from simulations. PMID:26986350

  9. Velocity statistics of the Nagel-Schreckenberg model

    NASA Astrophysics Data System (ADS)

    Bain, Nicolas; Emig, Thorsten; Ulm, Franz-Josef; Schreckenberg, Michael

    2016-02-01

    The statistics of velocities in the cellular automaton model of Nagel and Schreckenberg for traffic are studied. From numerical simulations, we obtain the probability distribution function (PDF) for vehicle velocities and the velocity-velocity (vv) covariance function. We identify the probability to find a standing vehicle as a potential order parameter that signals nicely the transition between free congested flow for a sufficiently large number of velocity states. Our results for the vv covariance function resemble features of a second-order phase transition. We develop a 3-body approximation that allows us to relate the PDFs for velocities and headways. Using this relation, an approximation to the velocity PDF is obtained from the headway PDF observed in simulations. We find a remarkable agreement between this approximation and the velocity PDF obtained from simulations.

  10. Elastic wave velocities of peridotite KLB-1 at mantle pressures and implications for mantle velocity modeling

    NASA Astrophysics Data System (ADS)

    Wang, Xuebing; Chen, Ting; Zou, Yongtao; Liebermann, Robert C.; Li, Baosheng

    2015-05-01

    Compressional (VP) and shear (VS) wave velocities of a synthetic KLB-1 peridotite were measured for the first time up to 10 GPa using ultrasonic interferometry. Analysis of the P and S wave velocities yielded K0 = 123(1) GPa, K0' = 5.1(2), G0 = 75(1) GPa, and G0'= 1.3(1) for the bulk and shear moduli and their pressure derivatives. Comparison with Voigt-Reuss-Hill (VRH) calculations based on literature elasticity data for its constituent minerals indicates that the experimentally measured P and S wave velocities, densities, bulk sound velocities, and VP/VS ratios fall close to the lower limit of VRH averages associated with the uncertainties of the mineral elasticity data. A comparison with previous modeling of mantle compositions implies that the velocities for an aggregate with the pyrolitic composition of KLB-1 are in close agreement with seismic data at the depths of the Earth's upper mantle.

  11. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  12. A modified full velocity difference model with the consideration of velocity deviation

    NASA Astrophysics Data System (ADS)

    Zhou, Jie; Shi, Zhong-Ke

    2016-01-01

    In this paper, a modified full velocity difference model (FVDM) based on car-following theory is proposed with the consideration of velocity deviation which represents the inexact judgement of velocity. The stability condition is obtained by the use of linear stability analysis. It is shown that the stability of traffic flow varies with the deviation extent of velocity. The Burgers, Korteweg-de Vries (KdV) and modified K-dV (MKdV) equations are derived to describe the triangular shock waves, soliton waves and kink-antikink waves in the stable, metastable and unstable region, respectively. The numerical simulations show a good agreement with the analytical results, such as density wave, hysteresis loop, acceleration, deceleration and so on. The results show that traffic congestion can be suppressed by taking the positive effect of velocity deviation into account. By taking the positive effect of high estimate of velocity into account, the unrealistic high deceleration and negative velocity which occur in FVDM will be eliminated in the proposed model.

  13. New identification method for Hammerstein models based on approximate least absolute deviation

    NASA Astrophysics Data System (ADS)

    Xu, Bao-Chang; Zhang, Ying-Dan

    2016-07-01

    Disorder and peak noises or large disturbances can deteriorate the identification effects of Hammerstein non-linear models when using the least-square (LS) method. The least absolute deviation technique can be used to resolve this problem; however, its absolute value cannot meet the need of differentiability required by most algorithms. To improve robustness and resolve the non-differentiable problem, an approximate least absolute deviation (ALAD) objective function is established by introducing a deterministic function that exhibits the characteristics of absolute value under certain situations. A new identification method for Hammerstein models based on ALAD is thus developed in this paper. The basic idea of this method is to apply the stochastic approximation theory in the process of deriving the recursive equations. After identifying the parameter matrix of the Hammerstein model via the new algorithm, the product terms in the matrix are separated by calculating the average values. Finally, algorithm convergence is proven by applying the ordinary differential equation method. The proposed algorithm has a better robustness as compared to other LS methods, particularly when abnormal points exist in the measured data. Furthermore, the proposed algorithm is easier to apply and converges faster. The simulation results demonstrate the efficacy of the proposed algorithm.

  14. Sampling artifact in volume weighted velocity measurement. I. Theoretical modeling

    NASA Astrophysics Data System (ADS)

    Zhang, Pengjie; Zheng, Yi; Jing, Yipeng

    2015-02-01

    Cosmology based on large scale peculiar velocity prefers volume weighted velocity statistics. However, measuring the volume weighted velocity statistics from inhomogeneously distributed galaxies (simulation particles/halos) suffers from an inevitable and significant sampling artifact. We study this sampling artifact in the velocity power spectrum measured by the nearest particle velocity assignment method by Zheng et al., [Phys. Rev. D 88, 103510 (2013).]. We derive the analytical expression of leading and higher order terms. We find that the sampling artifact suppresses the z =0 E -mode velocity power spectrum by ˜10 % at k =0.1 h /Mpc , for samples with number density 10-3 (Mpc /h )-3 . This suppression becomes larger for larger k and for sparser samples. We argue that this source of systematic errors in peculiar velocity cosmology, albeit severe, can be self-calibrated in the framework of our theoretical modelling. We also work out the sampling artifact in the density-velocity cross power spectrum measurement. A more robust evaluation of related statistics through simulations will be presented in a companion paper by Zheng et al., [Sampling artifact in volume weighted velocity measurement. II. Detection in simulations and comparison with theoretical modelling, arXiv:1409.6809.]. We also argue that similar sampling artifact exists in other velocity assignment methods and hence must be carefully corrected to avoid systematic bias in peculiar velocity cosmology.

  15. An improved car-following model considering relative velocity fluctuation

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Shi, Zhongke

    2016-07-01

    To explore and evaluate the impacts of relative velocity fluctuation on the dynamic characteristics and fuel consumptions of traffic flow, we present an improved car-following model considering relative velocity fluctuation based on the full velocity difference model, then we carry out several numerical simulations to determine the optimal time window length and to explore how relative velocity fluctuation affects cars' velocity and its fluctuation as well as fuel consumptions. It can be found that the improved car-following model can describe the phase transition of traffic flow and estimate the evolution of traffic congestion, and that taking relative velocity fluctuation into account in designing the advanced adaptive cruise control strategy can improve the traffic flow stability and reduce fuel consumptions.

  16. A simple model explaining super-resolution in absolute optical instruments

    NASA Astrophysics Data System (ADS)

    Leonhardt, Ulf; Sahebdivan, Sahar; Kogan, Alex; Tyc, Tomáš

    2015-05-01

    We develop a simple, one-dimensional model for super-resolution in absolute optical instruments that is able to describe the interplay between sources and detectors. Our model explains the subwavelength sensitivity of a point detector to a point source reported in previous computer simulations and experiments (Miñano 2011 New J. Phys.13 125009; Miñano 2014 New J. Phys.16 033015).

  17. Uncertainty assessment of 3D instantaneous velocity model from stack velocities

    NASA Astrophysics Data System (ADS)

    Emanuele Maesano, Francesco; D'Ambrogi, Chiara

    2015-04-01

    3D modelling is a powerful tool that is experiencing increasing applications in data analysis and dissemination. At the same time the need of quantitative uncertainty evaluation is strongly requested in many aspects of the geological sciences and by the stakeholders. In many cases the starting point for 3D model building is the interpretation of seismic profiles that provide indirect information about the geology of the subsurface in the domain of time. The most problematic step in the 3D modelling construction is the conversion of the horizons and faults interpreted in time domain to the depth domain. In this step the dominant variable that could lead to significantly different results is the velocity. The knowledge of the subsurface velocities is related mainly to punctual data (sonic logs) that are often sparsely distributed in the areas covered by the seismic interpretation. The extrapolation of velocity information to wide extended horizons is thus a critical step to obtain a 3D model in depth that can be used for predictive purpose. In the EU-funded GeoMol Project, the availability of a dense network of seismic lines (confidentially provided by ENI S.p.A.) in the Central Po Plain, is paired with the presence of 136 well logs, but few of them have sonic logs and in some portion of the area the wells are very widely spaced. The depth conversion of the 3D model in time domain has been performed testing different strategies for the use and the interpolation of velocity data. The final model has been obtained using a 4 layer cake 3D instantaneous velocity model that considers both the initial velocity (v0) in every reference horizon and the gradient of velocity variation with depth (k). Using this method it is possible to consider the geological constraint given by the geometries of the horizons and the geo-statistical approach to the interpolation of velocities and gradient. Here we present an experiment based on the use of set of pseudo-wells obtained from the

  18. Cluster statistics and quasisoliton dynamics in microscopic optimal-velocity models

    NASA Astrophysics Data System (ADS)

    Yang, Bo; Xu, Xihua; Pang, John Z. F.; Monterola, Christopher

    2016-04-01

    Using the non-linear optimal velocity models as an example, we show that there exists an emergent intrinsic scale that characterizes the interaction strength between multiple clusters appearing in the solutions of such models. The interaction characterizes the dynamics of the localized quasisoliton structures given by the time derivative of the headways, and the intrinsic scale is analogous to the "charge" of the quasisolitons, leading to non-trivial cluster statistics from the random perturbations to the initial steady states of uniform headways. The cluster statistics depend both on the quasisoliton charge and the density of the traffic. The intrinsic scale is also related to an emergent quantity that gives the extremum headways in the cluster formation, as well as the coexistence curve separating the absolute stable phase from the metastable phase. The relationship is qualitatively universal for general optimal velocity models.

  19. Modelling and measurement of the absolute level of power radiated by antenna integrated THz UTC photodiodes.

    PubMed

    Natrella, Michele; Liu, Chin-Pang; Graham, Chris; van Dijk, Frederic; Liu, Huiyun; Renaud, Cyril C; Seeds, Alwyn J

    2016-05-30

    We determine the output impedance of uni-travelling carrier (UTC) photodiodes at frequencies up to 400 GHz by performing, for the first time, 3D full-wave modelling of detailed UTC photodiode structures. In addition, we demonstrate the importance of the UTC impedance evaluation, by using it in the prediction of the absolute power radiated by an antenna integrated UTC, over a broad frequency range and confirming the predictions by experimental measurements up to 185 GHz. This is done by means of 3D full-wave modelling and is only possible since the source (UTC) to antenna impedance match is properly taken into account. We also show that, when the UTC-to-antenna coupling efficiency is modelled using the classical junction-capacitance/series-resistance concept, calculated and measured levels of absolute radiated power are in substantial disagreement, and the maximum radiated power is overestimated by a factor of almost 7 dB. The ability to calculate the absolute emitted power correctly enables the radiated power to be maximised through optimisation of the UTC-to-antenna impedance match. PMID:27410104

  20. Modeling Low Velocity Impacts: Predicting Crater Depth on Pluto

    NASA Astrophysics Data System (ADS)

    Bray, V. J.; Schenk, P.

    2014-12-01

    The New Horizons mission is due to fly-by the Pluto system in Summer 2015 and provides the first opportunity to image the Pluto surface in detail, allowing both the appearance and number of its crater population to be studied for the first time. Bray and Schenk (2014) combined previous cratering studies and numerical modeling of the impact process to predict crater morphology on Pluto based on current understanding of Pluto's composition, structure and surrounding impactor population. Predictions of how the low mean impact velocity (~2km/s) of the Pluto system will influence crater formation is a complex issue. Observations of secondary cratering (low velocity, high angle) and laboratory experiments of impact at low velocity are at odds regarding how velocity controls depth-diameter ratios: Observations of secondary craters show that these low velocity craters are shallower than would be expected for a hyper-velocity primary. Conversely, gas gun work has shown that relative crater depth increases as impact velocity decreases. We have investigated the influence of impact velocity further with iSALE hydrocode modeling of comet impact into Pluto. With increasing impact velocity, a projectile will produce wider and deeper craters. The depth-diameter ratio (d/D) however has a more complex progression with increasing impact velocity: impacts faster than 2km/s lead to smaller d/D ratios as impact velocity increases, in agreement with gas-gun studies. However, decreasing impact velocity from 2km/s to 300 m/s produced smaller d/D as impact velocity was decreased. This suggests that on Pluto the deepest craters would be produced by ~ 2km/s impacts, with shallower craters produced by velocities either side of this critical point. Further simulations to investigate whether this effect is connected to the sound speed of the target material are ongoing. The complex relationship between impact velocity and crater depth for impacts occurring between 300m/s and 10 km/s suggests

  1. Brady 1D seismic velocity model ambient noise prelim

    DOE Data Explorer

    Mellors, Robert J.

    2013-10-25

    Preliminary 1D seismic velocity model derived from ambient noise correlation. 28 Green's functions filtered between 4-10 Hz for Vp, Vs, and Qs were calculated. 1D model estimated for each path. The final model is a median of the individual models. Resolution is best for the top 1 km. Poorly constrained with increasing depth.

  2. Time-series modeling and prediction of global monthly absolute temperature for environmental decision making

    NASA Astrophysics Data System (ADS)

    Ye, Liming; Yang, Guixia; Van Ranst, Eric; Tang, Huajun

    2013-03-01

    A generalized, structural, time series modeling framework was developed to analyze the monthly records of absolute surface temperature, one of the most important environmental parameters, using a deterministicstochastic combined (DSC) approach. Although the development of the framework was based on the characterization of the variation patterns of a global dataset, the methodology could be applied to any monthly absolute temperature record. Deterministic processes were used to characterize the variation patterns of the global trend and the cyclic oscillations of the temperature signal, involving polynomial functions and the Fourier method, respectively, while stochastic processes were employed to account for any remaining patterns in the temperature signal, involving seasonal autoregressive integrated moving average (SARIMA) models. A prediction of the monthly global surface temperature during the second decade of the 21st century using the DSC model shows that the global temperature will likely continue to rise at twice the average rate of the past 150 years. The evaluation of prediction accuracy shows that DSC models perform systematically well against selected models of other authors, suggesting that DSC models, when coupled with other ecoenvironmental models, can be used as a supplemental tool for short-term (˜10-year) environmental planning and decision making.

  3. The Impact of Different Absolute Solar Irradiance Values on Current Climate Model Simulations

    NASA Technical Reports Server (NTRS)

    Rind, David H.; Lean, Judith L.; Jonas, Jeffrey

    2014-01-01

    Simulations of the preindustrial and doubled CO2 climates are made with the GISS Global Climate Middle Atmosphere Model 3 using two different estimates of the absolute solar irradiance value: a higher value measured by solar radiometers in the 1990s and a lower value measured recently by the Solar Radiation and Climate Experiment. Each of the model simulations is adjusted to achieve global energy balance; without this adjustment the difference in irradiance produces a global temperature change of 0.48C, comparable to the cooling estimated for the Maunder Minimum. The results indicate that by altering cloud cover the model properly compensates for the different absolute solar irradiance values on a global level when simulating both preindustrial and doubled CO2 climates. On a regional level, the preindustrial climate simulations and the patterns of change with doubled CO2 concentrations are again remarkably similar, but there are some differences. Using a higher absolute solar irradiance value and the requisite cloud cover affects the model's depictions of high-latitude surface air temperature, sea level pressure, and stratospheric ozone, as well as tropical precipitation. In the climate change experiments it leads to an underestimation of North Atlantic warming, reduced precipitation in the tropical western Pacific, and smaller total ozone growth at high northern latitudes. Although significant, these differences are typically modest compared with the magnitude of the regional changes expected for doubled greenhouse gas concentrations. Nevertheless, the model simulations demonstrate that achieving the highest possible fidelity when simulating regional climate change requires that climate models use as input the most accurate (lower) solar irradiance value.

  4. Absolute stability and synchronization in neural field models with transmission delays

    NASA Astrophysics Data System (ADS)

    Kao, Chiu-Yen; Shih, Chih-Wen; Wu, Chang-Hong

    2016-08-01

    Neural fields model macroscopic parts of the cortex which involve several populations of neurons. We consider a class of neural field models which are represented by integro-differential equations with transmission time delays which are space-dependent. The considered domains underlying the systems can be bounded or unbounded. A new approach, called sequential contracting, instead of the conventional Lyapunov functional technique, is employed to investigate the global dynamics of such systems. Sufficient conditions for the absolute stability and synchronization of the systems are established. Several numerical examples are presented to demonstrate the theoretical results.

  5. Absolute IGS antenna phase center model igs08.atx: status and potential improvements

    NASA Astrophysics Data System (ADS)

    Schmid, R.; Dach, R.; Collilieux, X.; Jäggi, A.; Schmitz, M.; Dilssner, F.

    2016-04-01

    On 17 April 2011, all analysis centers (ACs) of the International GNSS Service (IGS) adopted the reference frame realization IGS08 and the corresponding absolute antenna phase center model igs08.atx for their routine analyses. The latter consists of an updated set of receiver and satellite antenna phase center offsets and variations (PCOs and PCVs). An update of the model was necessary due to the difference of about 1 ppb in the terrestrial scale between two consecutive realizations of the International Terrestrial Reference Frame (ITRF2008 vs. ITRF2005), as that parameter is highly correlated with the GNSS satellite antenna PCO components in the radial direction.

  6. A turbulent inflow model based on velocity modulation

    NASA Astrophysics Data System (ADS)

    Huyer, Stephen A.; Beal, David

    2007-11-01

    This article presents a novel turbulent inflow model based on modulation of the velocity field for use with time-domain propulsor calculations. Given an experimental mean and rms turbulent inflow, a model can be constructed by modulating the velocity field over a range of frequencies. Assuming the turbulence is homogeneous, the inflow can be constructed as a Fourier series where the frequencies can also be modulated to smooth the broadband output. To demonstrate the effectiveness of the model, experimental inflow velocity data were acquired for an upstream stator, downstream rotor configuration mounted on an undersea vehicle afterbody. Two main sources of turbulence originated from the vorticity shed from the stator wakes and the boundary layer vorticity produced on the hull body. Three-dimensional, unsteady velocity data were acquired using hot-wire anemometry and reduced to provide mean and rms velocity values. Time-series data were processed to provide velocity power spectra used to calibrate the model. Simulations were performed using a modified version of the propulsor unsteady flow code capable of computing fully turbulent inflows. This solver models the propulsor blade as a vortex lattice and sheds the vorticity into the wake to solve the unsteady potential flow. The no-flux boundary conditions are satisfied at the lattice control points and the resulting unsteady circulation is a function of the instantaneous inflow velocity field over the blade. Vorticity is shed into the wake to account for the full time history of the inflow velocity field. To demonstrate the full effectiveness of the model, computed surface pressure data were exported to a code to compute the far-field radiated noise (both tonal and broadband). Simulated data were compared with experimentally obtained noise data with favorable results. Applications of this methodology in the incompressible flow domain include broadband analysis of propulsor-radiated noise on undersea vehicles and

  7. The galaxy velocity field and CDM models

    NASA Technical Reports Server (NTRS)

    Tormen, Giuseppe; Moscardini, Lauro; Lucchin, Francesco; Matarrese, Sabino

    1993-01-01

    It is generally accepted that some kind of non-baryonic dark matter accounts for most of the mass density of the universe. Considering such a component has become, in the last decade, a key ingredient in current theories of structure formation. In particular, the Cold Dark Matter (CDM) scenario has proven to be quite successful in explaining most of the observed properties of galaxies and of their large-scale distribution. The standard CDM model is characterized by a primordial Zel'dovich spectrum, of random-phase adiabatic perturbations in a universe with density parameter omega sub 0 = 1 and vanishing cosmological constant. This poster paper presents an analysis of observational data on peculiar motion of optical galaxies in comparison to the predictions of CDM models where the assumptions of the standard scenario: omega sub 0 = 1, n = 1, and bias parameter b = 1 are relaxed. In particular, CDM models with 0 less than n less than 1 and 0.4 less than omega sub 0 less than 1 are considered.

  8. Asymmetric optimal-velocity car-following model

    NASA Astrophysics Data System (ADS)

    Xu, Xihua; Pang, John; Monterola, Christopher

    2015-10-01

    Taking the asymmetric characteristic of the velocity differences of vehicles into account, we present an asymmetric optimal velocity model for a car-following theory. The asymmetry between the acceleration and the deceleration is represented by the exponential function with an asymmetrical factor, which agrees with the published experiment. This model avoids the disadvantage of the unrealistically high acceleration appearing in previous models when the velocity difference becomes large. This model is simple and only has two independent parameters. The linear stability condition is derived and the phase transition of the traffic flow appears beyond the critical density. The strength of interaction between clusters is shown to increase with the asymmetry factor in our model.

  9. Velocity-density twin transforms in the thin disc model

    NASA Astrophysics Data System (ADS)

    Bratek, Łukasz; Sikora, Szymon; Jałocha, Joanna; Kutschera, Marek

    2015-08-01

    Ring mass density and the corresponding circular velocity in thin disc model are known to be integral transforms of one another. But it may be less familiar that the transforms can be reduced to one-fold integrals with identical weight functions. It may be of practical value that the integral for the surface density does not involve the velocity derivative, unlike the equivalent and widely known Toomre's formula.

  10. Evaluation of Generalized Born Model Accuracy for Absolute Binding Free Energy Calculations.

    PubMed

    Zeller, Fabian; Zacharias, Martin

    2014-06-27

    Generalized Born (GB) implicit solvent models are widely used in molecular dynamics simulations to evaluate the interactions of biomolecular complexes. The continuum treatment of the solvent results in significant computational savings in comparison to an explicit solvent representation. It is, however, not clear how accurately the GB approach reproduces the absolute free energies of biomolecular binding. On the basis of induced dissociation by means of umbrella sampling simulations, the absolute binding free energies of small proline-rich peptide ligands and a protein receptor were calculated. Comparative simulations according to the same protocol were performed by employing an explicit solvent model and various GB-type implicit solvent models in combination with a nonpolar surface tension term. The peptide ligands differed in a key residue at the peptide-protein interface, including either a nonpolar, a neutral polar, a positively charged, or a negatively charged group. For the peptides with a neutral polar or nonpolar interface residue, very good agreement between the explicit solvent and GB implicit solvent results was found. Deviations in the main separation free energy contributions are smaller than 1 kcal/mol. In contrast, for peptides with a charged interface residue, significant deviations of 2-4 kcal/mol were observed. The results indicate that recent GB models can compete with explicit solvent representations in total binding free energy calculations as long as no charged residues are present at the binding interface. PMID:24941018

  11. Velocity Structure in the West Bohemia Seismic Zone: Velocity Models Retrieved from different Earthquake Swarms

    NASA Astrophysics Data System (ADS)

    Alexandrakis, C.; Löberich, E.; Kieslich, A.; Calo, M.; Vavrycuk, V.; Buske, S.

    2015-12-01

    Earthquake swarms, fluid migration and gas springs are indications of the ongoing geodynamic processes within the West Bohemia seismic zone located at the Czech-German border. The possible relationship between the fluids, gas and seismicity is of particular interest and has motivated numerous past, ongoing and future studies, including a multidisciplinary monitoring proposal through the International Continental Scientific Drilling Program (ICDP). The most seismically active area within the West Bohemia seismic zone is located at the Czech town Nový Kostel. The Nový Kostel zone experiences frequent swarms of several hundreds to thousands of earthquakes over a period of weeks to several months. The seismicity is always located in the same area and depth range (~5-15 km), however the activated fault segments and planes differ. For example, the 2008 swarm activated faults along the southern end of the seismic zone, the 2011 swarm activated the northern segment, and the recent 2014 swarm activated the middle of the seismic zone. This indicates changes to the local stress field, and may relate to fluid migration and/or the complicated tectonic situation. The West Bohemia Seismic Network (WEBNET) is ideally located for studying the Nový Kostel swarm area and provides good azimuthal coverage. Here, we use the high quality P- and S-wave arrival picks recorded by WEBNET to calculate swarm-dependent velocity models for the 2008 and 2011 swarms, and an averaged (swarm independent) model using earthquakes recorded between 1991 and 2011. To this end, we use double-difference tomography to calculate P- and S-wave velocity models. The models are compared and examined in terms of swarm-dependent velocities and structures. Since the P-to-S velocity ratio is particularly sensitive to the presence of pore fluids, we derive ratio models directly from the inverted P- and S-wave models in order to investigate the potential influence of fluids on the seismicity. Finally, clustering

  12. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  13. Behaviour of ion velocity distributions for a simple collision model

    NASA Technical Reports Server (NTRS)

    St-Maurice, J.-P.; Schunk, R. W.

    1974-01-01

    Calculation of the ion velocity distributions for a weakly ionized plasma subjected to crossed electric and magnetic fields. An exact solution to Boltzmann's equation has been obtained by replacing the Boltzmann collision integral with a simple relaxation model. At altitudes above about 150 km, where the ion collision frequency is much less than the ion cyclotron frequency, the ion distribution takes the shape of a torus in velocity space for electric fields greater than 40 mV/m. This shape persists for one to two hours after application of the electric field. At altitudes where the ion collision and cyclotron frequencies are approximately equal (about 120 km), the ion velocity distribution is shaped like a bean for large electric field strengths. This bean-shaped distribution persists throughout the lifetime of ionospheric electric fields. These highly non-Maxwellian ion velocity distributions may have an appreciable affect on the interpretation of ion temperature measurements.

  14. Improved Strategies and Optimization of Calibration Models for Real-time PCR Absolute Quantification

    EPA Science Inventory

    Real-time PCR absolute quantification applications rely on the use of standard curves to make estimates of DNA target concentrations in unknown samples. Traditional absolute quantification approaches dictate that a standard curve must accompany each experimental run. However, t...

  15. Recovering slant and angular velocity from a linear velocity field: modeling and psychophysics.

    PubMed

    Domini, Fulvio; Caudek, Corrado

    2003-07-01

    The data from two experiments, both using stimuli simulating orthographically rotating surfaces, are presented, with the primary variable of interest being whether the magnitude of the simulated gradient was from expanding vs. contracting motion. One experiment asked observers to report the apparent slant of the rotating surface, using a gauge figure. The other experiment asked observers to report the angular velocity, using a comparison rotating sphere. The results from both experiments clearly show that observers are less sensitive to expanding than to contracting optic-flow fields. These results are well predicted by a probabilistic model which derives the orientation and angular velocity of the projected surface from the properties of the optic flow computed within an extended time window. PMID:12818345

  16. Computations of absolute solvation free energies of small molecules using explicit and implicit solvent model.

    SciTech Connect

    Shivakumar, D.; Deng, Y.; Roux, B.; Biosciences Division; Univ. of Chicago

    2009-01-01

    Accurate determination of absolute solvation free energy plays a critical role in numerous areas of biomolecular modeling and drug discovery. A quantitative representation of ligand and receptor desolvation, in particular, is an essential component of current docking and scoring methods. Furthermore, the partitioning of a drug between aqueous and nonpolar solvents is one of the important factors considered in pharmacokinetics. In this study, the absolute hydration free energy for a set of 239 neutral ligands spanning diverse chemical functional groups commonly found in drugs and drug-like candidates is calculated using the molecular dynamics free energy perturbation method (FEP/MD) with explicit water molecules, and compared to experimental data as well as its counterparts obtained using implicit solvent models. The hydration free energies are calculated from explicit solvent simulations using a staged FEP procedure permitting a separation of the total free energy into polar and nonpolar contributions. The nonpolar component is further decomposed into attractive (dispersive) and repulsive (cavity) components using the Weeks-Chandler-Anderson (WCA) separation scheme. To increase the computational efficiency, all of the FEP/MD simulations are generated using a mixed explicit/implicit solvent scheme with a relatively small number of explicit TIP3P water molecules, in which the influence of the remaining bulk is incorporated via the spherical solvent boundary potential (SSBP). The performances of two fixed-charge force fields designed for small organic molecules, the General Amber force field (GAFF), and the all-atom CHARMm-MSI, are compared. Because of the crucial role of electrostatics in solvation free energy, the results from various commonly used charge generation models based on the semiempirical (AM1-BCC) and QM calculations [charge fitting using ChelpG and RESP] are compared. In addition, the solvation free energies of the test set are also calculated using

  17. Wave-induced velocities inside a model seagrass bed

    NASA Astrophysics Data System (ADS)

    Luhar, Mitul; Coutu, Sylvain; Infantes, Eduardo; Fox, Samantha; Nepf, Heidi

    2010-12-01

    Laboratory measurements reveal the flow structure within and above a model seagrass meadow (dynamically similar to Zostera marina) forced by progressive waves. Despite being driven by purely oscillatory flow, a mean current in the direction of wave propagation is generated within the meadow. This mean current is forced by a nonzero wave stress, similar to the streaming observed in wave boundary layers. The measured mean current is roughly four times that predicted by laminar boundary layer theory, with magnitudes as high as 38% of the near-bed orbital velocity. A simple theoretical model is developed to predict the magnitude of this mean current based on the energy dissipated within the meadow. Unlike unidirectional flow, which can be significantly damped within a meadow, the in-canopy orbital velocity is not significantly damped. Consistent with previous studies, the reduction of in-canopy velocity is a function of the ratio of orbital excursion and blade spacing.

  18. Ray tracing in discontinuous velocity model with implicit Interface

    NASA Astrophysics Data System (ADS)

    Zhang, Jianxing; Yang, Qin; Meng, Xianhai; Li, Jigang

    2016-07-01

    Ray tracing in the velocity model containing complex discontinuities is still facing many challenges. The main difficulty arises from the detection of the spatial relationship between the rays and the interfaces that are usually described in non-linear parametric forms. We propose a novel model representation method that can facilitate the implementation of classical shooting-ray methods. In the representation scheme, each interface is expressed as the zero contour of a signed distance field. A multi-copy strategy is adopted to describe the volumetric properties within blocks. The implicit description of the interface makes it easier to detect the ray-interface intersection. The direct calculation of the intersection point is converted into the problem of judging the signs of a ray segment's endpoints. More importantly, the normal to the interface at the intersection point can be easily acquired according to the signed distance field of the interface. The multiple storage of the velocity property in the proximity of the interface can provide accurate and unambiguous velocity information of the intersection point. Thus, the departing ray path can be determined easily and robustly. In addition, the new representation method can describe velocity models containing very complex geological structures, such as faults, salt domes, intrusions, and pinches, without any simplification. The examples on synthetic and real models validate the robustness and accuracy of the ray tracing based on the proposed model representation scheme.

  19. Photochirogenesis: Photochemical models on the absolute asymmetric formation of amino acids in interstellar space

    NASA Astrophysics Data System (ADS)

    Meinert, Cornelia; de Marcellus, Pierre; Le Sergeant D'Hendecourt, Louis; Nahon, Laurent; Jones, Nykola C.; Hoffmann, Søren V.; Bredehöft, Jan Hendrik; Meierhenrich, Uwe J.

    2011-10-01

    Proteins of all living organisms including plants, animals, and humans are made up of amino acid monomers that show identical stereochemical L-configuration. Hypotheses for the origin of this symmetry breaking in biomolecules include the absolute asymmetric photochemistry model by which interstellar ultraviolet (UV) circularly polarized light (CPL) induces an enantiomeric excess in chiral organic molecules in the interstellar/circumstellar media. This scenario is supported by a) the detection of amino acids in the organic residues of UV-photo-processed interstellar ice analogues, b) the occurrence of L-enantiomer-enriched amino acids in carbonaceous meteorites, and c) the observation of CPL of the same helicity over large distance scales in the massive star-forming region of Orion. These topics are of high importance in topical biophysical research and will be discussed in this review. Further evidence that amino acids and other molecules of prebiotic interest are asymmetrically formed in space comes from studies on the enantioselective photolysis of amino acids by UV-CPL. Also, experiments have been performed on the absolute asymmetric photochemical synthesis of enantiomer-enriched amino acids from mixtures of astrophysically relevant achiral precursor molecules using UV-circularly polarized photons. Both approaches are based on circular dichroic transitions of amino acids that will be highlighted here as well. These results have strong implications on our current understanding of how life's precursor molecules were possibly built and how life selected the left-handed form of proteinogenic amino acids.

  20. Modeling absolute differences in life expectancy with a censored skew-normal regression approach

    PubMed Central

    Clough-Gorr, Kerri; Zwahlen, Marcel

    2015-01-01

    Parameter estimates from commonly used multivariable parametric survival regression models do not directly quantify differences in years of life expectancy. Gaussian linear regression models give results in terms of absolute mean differences, but are not appropriate in modeling life expectancy, because in many situations time to death has a negative skewed distribution. A regression approach using a skew-normal distribution would be an alternative to parametric survival models in the modeling of life expectancy, because parameter estimates can be interpreted in terms of survival time differences while allowing for skewness of the distribution. In this paper we show how to use the skew-normal regression so that censored and left-truncated observations are accounted for. With this we model differences in life expectancy using data from the Swiss National Cohort Study and from official life expectancy estimates and compare the results with those derived from commonly used survival regression models. We conclude that a censored skew-normal survival regression approach for left-truncated observations can be used to model differences in life expectancy across covariates of interest. PMID:26339544

  1. A model to interpret the intensity-velocity and velocity-velocity phase differences from solar observations obtained with magneto-optical filters

    NASA Astrophysics Data System (ADS)

    Moretti, P. F.; Severino, G.

    2004-07-01

    The intensity (I) and velocity (V) signals obtained using magneto-optical filters (MOF), are not independent of each other. The induced spurious signals affect the intensity-velocity phase difference measurements and the effect is referred to as a I-V crosstalk (Moretti & Severino \\cite{Moretti02}). We show a new model to interpret the I-V phase measurements and, in particular, its application to the interpretation of the data obtained with sodium MOF systems. The model can also be applied to correct the velocity-velocity phase from multi layer observations.

  2. Surveying implicit solvent models for estimating small molecule absolute hydration free energies

    PubMed Central

    Knight, Jennifer L.

    2011-01-01

    Implicit solvent models are powerful tools in accounting for the aqueous environment at a fraction of the computational expense of explicit solvent representations. Here, we compare the ability of common implicit solvent models (TC, OBC, OBC2, GBMV, GBMV2, GBSW, GBSW/MS, GBSW/MS2 and FACTS) to reproduce experimental absolute hydration free energies for a series of 499 small neutral molecules that are modeled using AMBER/GAFF parameters and AM1-BCC charges. Given optimized surface tension coefficients for scaling the surface area term in the nonpolar contribution, most implicit solvent models demonstrate reasonable agreement with extensive explicit solvent simulations (average difference 1.0-1.7 kcal/mol and R2=0.81-0.91) and with experimental hydration free energies (average unsigned errors=1.1-1.4 kcal/mol and R2=0.66-0.81). Chemical classes of compounds are identified that need further optimization of their ligand force field parameters and others that require improvement in the physical parameters of the implicit solvent models themselves. More sophisticated nonpolar models are also likely necessary to more effectively represent the underlying physics of solvation and take the quality of hydration free energies estimated from implicit solvent models to the next level. PMID:21735452

  3. A new settling velocity model to describe secondary sedimentation.

    PubMed

    Ramin, Elham; Wágner, Dorottya S; Yde, Lars; Binning, Philip J; Rasmussen, Michael R; Mikkelsen, Peter Steen; Plósz, Benedek Gy

    2014-12-01

    Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions. PMID:25243657

  4. Enhanced Cortical Connectivity in Absolute Pitch Musicians: A Model for Local Hyperconnectivity

    PubMed Central

    Loui, Psyche; Charles Li, Hui C.; Hohmann, Anja; Schlaug, Gottfried

    2010-01-01

    Connectivity in the human brain has received increased scientific interest in recent years. Although connection disorders can affect perception, production, learning, and memory, few studies have associated brain connectivity with graded variations in human behavior, especially among normal individuals. One group of normal individuals who possess unique characteristics in both behavior and brain structure is absolute pitch (AP) musicians, who can name the appropriate pitch class of any given tone without a reference. Using diffusion tensor imaging and tractography, we observed hyperconnectivity in bilateral superior temporal lobe structures linked to AP possession. Furthermore, volume of tracts connecting left superior temporal gyrus to left middle temporal gyrus predicted AP performance. These findings extend previous reports of exaggerated temporal lobe asymmetry, may explain the higher incidence of AP in developmental disorders, and may provide a model for understanding the heightened connectivity that is thought to underlie savant skills and cases of exceptional creativity. PMID:20515408

  5. A New Mixed Model Based on the Velocity Structure Function

    NASA Astrophysics Data System (ADS)

    Brun, Christophe; Friedrich, Rainer; Da Silva, Carlos B.; Métais, Olivier

    We propose a new mixed model for Large Eddy-Simulation based on the 3D spatial velocity increment. This approach blends the non-linear properties of the Increment model (Brun & Friedrich (2001)) with the eddy viscosity characteristics of the Structure Function model (Métais & Lesieur (1992)). The behaviour of this subgrid scale model is studied both via a priori tests of a plane jet at ReH=3000 and Large Eddy-Simulation of a round jet at ReD=25000. This approach allows to describe both forward and backward energy transfer encountered in transitional shear flows.

  6. Intraglottal velocity and pressure measurements in a hemilarynx model

    PubMed Central

    Oren, Liran; Gutmark, Ephraim; Khosla, Sid

    2015-01-01

    Determining the mechanisms of self-sustained oscillation of the vocal folds requires characterization of the pressures produced by intraglottal aerodynamics. Because most of the intraglottal aerodynamic forces cannot be measured in a tissue model of the larynx, current understanding of vocal fold vibration mechanism is derived from mechanical, analytical, and computational models. Previous studies have computed intraglottal pressures from measured intraglottal velocity fields and intraglottal geometry; however, this technique for determining pressures is not yet validated. In this study, intraglottal pressure measurements taken in a hemilarynx model are compared with pressure values that are computed from simultaneous velocity measurements. The results showed that significant negative pressure formed near the superior aspect of the folds during closing, which agrees with previous measurements in other hemilarynx models. Intraglottal velocity measurements show that the flow near the superior aspect separates from the glottal wall during closing and may develop into a vortex, which further augments the magnitude of negative pressure. Intraglottal pressure distributions, computed by solving the pressure Poisson equation, showed good agreement with pressure measurements. The match between the pressure computations and its measurements validates the current technique, which was previously used to estimate intraglottal pressure distribution in a full larynx model. PMID:25698025

  7. Intraglottal velocity and pressure measurements in a hemilarynx model.

    PubMed

    Oren, Liran; Gutmark, Ephraim; Khosla, Sid

    2015-02-01

    Determining the mechanisms of self-sustained oscillation of the vocal folds requires characterization of the pressures produced by intraglottal aerodynamics. Because most of the intraglottal aerodynamic forces cannot be measured in a tissue model of the larynx, current understanding of vocal fold vibration mechanism is derived from mechanical, analytical, and computational models. Previous studies have computed intraglottal pressures from measured intraglottal velocity fields and intraglottal geometry; however, this technique for determining pressures is not yet validated. In this study, intraglottal pressure measurements taken in a hemilarynx model are compared with pressure values that are computed from simultaneous velocity measurements. The results showed that significant negative pressure formed near the superior aspect of the folds during closing, which agrees with previous measurements in other hemilarynx models. Intraglottal velocity measurements show that the flow near the superior aspect separates from the glottal wall during closing and may develop into a vortex, which further augments the magnitude of negative pressure. Intraglottal pressure distributions, computed by solving the pressure Poisson equation, showed good agreement with pressure measurements. The match between the pressure computations and its measurements validates the current technique, which was previously used to estimate intraglottal pressure distribution in a full larynx model. PMID:25698025

  8. Nilpotent and absolutely anticommuting symmetries in the Freedman-Townsend model: Augmented superfield formalism

    NASA Astrophysics Data System (ADS)

    Shukla, A.; Krishna, S.; Malik, R. P.

    2014-12-01

    We derive the off-shell nilpotent and absolutely anticommuting Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetry transformations, corresponding to the (1-form) Yang-Mills (YM) and (2-form) tensorial gauge symmetries of the four (3+1)-dimensional (4D) Freedman-Townsend (FT) model, by exploiting the augmented version of Bonora-Tonin's (BT) superfield approach to BRST formalism where the 4D flat Minkowskian theory is generalized onto the (4, 2)-dimensional supermanifold. One of the novel observations is the fact that we are theoretically compelled to go beyond the horizontality condition (HC) to invoke an additional set of gauge-invariant restrictions (GIRs) for the derivation of the full set of proper (anti-)BRST symmetries. To obtain the (anti-)BRST symmetry transformations, corresponding to the tensorial (2-form) gauge symmetries within the framework of augmented version of BT-superfield approach, we are logically forced to modify the FT-model to incorporate an auxiliary 1-form field and the kinetic term for the antisymmetric (2-form) gauge field. This is also a new observation in our present investigation. We point out some of the key differences between the modified FT-model and Lahiri-model (LM) of the dynamical non-Abelian 2-form gauge theories. We also briefly mention a few similarities.

  9. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  10. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  11. An Integrated Model of Choices and Response Times in Absolute Identification

    ERIC Educational Resources Information Center

    Brown, Scott D.; Marley, A. A. J.; Donkin, Christopher; Heathcote, Andrew

    2008-01-01

    Recent theoretical developments in the field of absolute identification have stressed differences between relative and absolute processes, that is, whether stimulus magnitudes are judged relative to a shorter term context provided by recently presented stimuli or a longer term context provided by the entire set of stimuli. The authors developed a…

  12. A Goldilocks principle for modelling radial velocity noise

    NASA Astrophysics Data System (ADS)

    Feng, F.; Tuomi, M.; Jones, H. R. A.; Butler, R. P.; Vogt, S.

    2016-09-01

    The Doppler measurements of stars are diluted and distorted by stellar activity noise. Different choices of noise models and statistical methods have led to much controversy in the confirmation of exoplanet candidates obtained through analysing radial velocity data. To quantify the limitation of various models and methods, we compare different noise models and signal detection criteria for various simulated and real data sets in the Bayesian framework. According to our analyses, the white noise model tend to interpret noise as signal, leading to false positives. On the other hand, the red noise models are likely to interpret signal as noise, resulting in false negatives. We find that the Bayesian information criterion combined with a Bayes factor threshold of 150 can efficiently rule out false positives and confirm true detections. We further propose a Goldilocks principle aimed at modelling radial velocity noise to avoid too many false positives and too many false negatives. We propose that the noise model with RHK-dependent jitter is used in combination with the moving average model to detect planetary signals for M dwarfs. Our work may also shed light on the noise modelling for hotter stars, and provide a valid approach for finding similar principles in other disciplines.

  13. Modelling the Velocity Field in a Regular Grid in the Area of Poland on the Basis of the Velocities of European Permanent Stations

    NASA Astrophysics Data System (ADS)

    Bogusz, Janusz; Kłos, Anna; Grzempowski, Piotr; Kontny, Bernard

    2014-06-01

    The paper presents the results of testing the various methods of permanent stations' velocity residua interpolation in a regular grid, which constitutes a continuous model of the velocity field in the territory of Poland. Three packages of software were used in the research from the point of view of interpolation: GMT ( The Generic Mapping Tools), Surfer and ArcGIS. The following methods were tested in the softwares: the Nearest Neighbor, Triangulation (TIN), Spline Interpolation, Surface, Inverse Distance to a Power, Minimum Curvature and Kriging. The presented research used the absolute velocities' values expressed in the ITRF2005 reference frame and the intraplate velocities related to the NUVEL model of over 300 permanent reference stations of the EPN and ASG-EUPOS networks covering the area of Europe. Interpolation for the area of Poland was done using data from the whole area of Europe to make the results at the borders of the interpolation area reliable. As a result of this research, an optimum method of such data interpolation was developed. All the mentioned methods were tested for being local or global, for the possibility to compute errors of the interpolated values, for explicitness and fidelity of the interpolation functions or the smoothing mode. In the authors' opinion, the best data interpolation method is Kriging with the linear semivariogram model run in the Surfer programme because it allows for the computation of errors in the interpolated values and it is a global method (it distorts the results in the least way). Alternately, it is acceptable to use the Minimum Curvature method. Empirical analysis of the interpolation results obtained by means of the two methods showed that the results are identical. The tests were conducted using the intraplate velocities of the European sites. Statistics in the form of computing the minimum, maximum and mean values of the interpolated North and East components of the velocity residuum were prepared for all

  14. Joint analysis of the seismic data and velocity gravity model

    NASA Astrophysics Data System (ADS)

    Belyakov, A. S.; Lavrov, V. S.; Muchamedov, V. A.; Nikolaev, A. V.

    2016-03-01

    We performed joint analysis of the seismic noises recorded at the Japanese Ogasawara station located on Titijima Island in the Philippine Sea using the STS-2 seismograph at the OSW station in the winter period of January 1-15, 2015, over the background of a velocity gravity model. The graphs prove the existence of a cause-and-effect relation between the seismic noise and gravity and allow us to consider it as a desired signal.

  15. A model for predicting individuals' absolute risk of esophageal adenocarcinoma: Moving toward tailored screening and prevention.

    PubMed

    Xie, Shao-Hua; Lagergren, Jesper

    2016-06-15

    Esophageal adenocarcinoma (EAC) is characterized by rapidly increasing incidence and poor prognosis, stressing the need for preventive and early detection strategies. We used data from a nationwide population-based case-control study, which included 189 incident cases of EAC and 820 age- and sex-matched control participants, from 1995 through 1997 in Sweden. We developed risk prediction models based on unconditional logistic regression. Candidate predictors included established and readily identifiable risk factors for EAC. The performance of model was assessed by the area under receiver operating characteristic curve (AUC) with cross-validation. The final model could explain 94% of all case patients with EAC (94% population attributable risk) and included terms for gastro-esophageal reflux symptoms or use of antireflux medication, body mass index (BMI), tobacco smoking, duration of living with a partner, previous diagnoses of esophagitis and diaphragmatic hernia and previous surgery for esophagitis, diaphragmatic hernia or severe reflux or gastric or duodenal ulcer. The AUC was 0.84 (95% confidence interval [CI] 0.81-0.87) and slightly lower after cross-validation. A simpler model, based only on reflux symptoms or use of antireflux medication, BMI and tobacco smoking could explain 91% of the case patients with EAC and had an AUC of 0.82 (95% CI 0.78-0.85). These EAC prediction models showed good discriminative accuracy, but need to be validated in other populations. These models have the potential for future use in identifying individuals with high absolute risk of EAC in the population, who may be considered for endoscopic screening and targeted prevention. PMID:26756848

  16. Modelling of the pressure-velocity correlation in turbulence diffusion

    NASA Astrophysics Data System (ADS)

    Fu, Song

    1993-05-01

    In the context of second-moment closure, the mechanism of turbulence diffusion consists of mainly two parts: a triple velocity correlation and a pressure-velocity correlation. The first correlation is measurable and can be analyzed theoretically through its transport equation. The second correlation cannot, however, be obtained directly from experiments and knowledge about it is comparatively limited. Most current computations of turbulent flows adopt diffusion models which neglect the effect of the pressure-velocity correlation in the diffusion process. The importance of this correlation effect is elucidated; the neglect of this effect constitutes some of the major defects in the application of the second-moment closures. Through the relation between the two correlations, established by Lumley (1978), we propose a new type of turbulence diffusion model which takes into account the pressure effect. Application of this new model in the computation of the turbulence shearless mixing layer and plane- and round-jet flows shows that the spreading rates of these flows can be captured satisfactorily.

  17. Estimation of macro velocity models by wave field extrapolation

    NASA Astrophysics Data System (ADS)

    Cox, Hendricus Lambertus Hubertus

    A method to estimate accurate macro velocity models for prediction of traveltimes of seismic waves in the earth's subsurface is developed. The sensitivity of prestack migration is used to estimate the model and since model errors are expressed in the quality of the migration result, the migration process itself can be used to determine these errors. Using an initial model, shot records are downward extrapolated to grid points (depth points) in the subsurface. The extrapolated data can be reordered into so called common depth point (CDP) gathers, image gathers and focus panels. The deviation from horizontal alignment is used to quantify the errors in the model and to apply update corrections accordingly. The analysis can be done before or after stacking over all shot records (CDP stacking). the previously mentioned focus panels are generated by CDP stacking. The alignment analysis reduces then to a simple focusing analysis. The examples discussed show that horizontal alignment gives accurate macro velocity models for prestack depth migration. Focus panels can be difficult to interpret in complicated situations, where it is impossible to converge to the correct solution with focus panels only. The process should be guided by macrogeologic models of the area. In complicated situations, a layer stripping strategy is preferred.

  18. The USGS 3D Seismic Velocity Model for Northern California

    NASA Astrophysics Data System (ADS)

    Brocher, T. M.; Aagaard, B.; Simpson, R. W.; Jachens, R. C.

    2006-12-01

    We present a new regional 3D seismic velocity model for Northern California for use in strong motion simulations of the 1906 San Francisco and other earthquakes. The model includes compressional-wave velocity (Vp), shear-wave velocity (Vs), density, and intrinsic attenuation (Qp, Qs). These properties were assigned for each rock type in a 3D geologic model derived from surface outcrops, boreholes, gravity and magnetic data, and seismic reflection, refraction, and tomography studies. A detailed description of the model, USGS Bay Area Velocity Model 05.1.0, is available online [http://www.sf06simulation.org/geology/velocitymodel]. For ground motion simulations Vs and Qs are more important parameters than Vp and Qp because the strongest ground motions are generated chiefly by shear and surface wave arrivals. Because Vp data are more common than Vs data, however, we first developed Vp versus depth relations for each rock type and then converted these to Vs versus depth relations. For the most important rock types in Northern California we compiled measurements of Vp versus depth using borehole logs, laboratory measurements on hand samples, seismic refraction profiles, and tomography models. These rock types include Salinian and Sierran granitic rocks, metagraywackes and greenstones of the Franciscan Complex, Tertiary and Mesozoic sedimentary and volcanic rocks, and Quaternary and Holocene deposits (Brocher, USGS OFR 05-1317, 2005). Vp versus depth curves were converted to Vs versus depth curves using new empirical nonlinear relations between Vs and Vp (Brocher, BSSA, 2005). These relations, showing that Poisson's ratio is a nonlinear function of Vp, were similarly based on compilations of diverse Vs and Vp measurements on a large suite of rock types, mainly from California and the Pacific Northwest. The model is distributed in a discretized form with routines to query the model using C++, C, and Fortran 77 programming languages. The geologic model was discretized at

  19. Model based period analysis of absolute and relative survival with R: data preparation, model fitting and derivation of survival estimates.

    PubMed

    Holleczek, Bernd; Brenner, Hermann

    2013-05-01

    Period analysis is increasingly employed in analyses of long-term survival of patients with chronic diseases such as cancer, as it derives more up-to-date survival estimates than traditional cohort based approaches. It has recently been extended with regression modelling using generalized linear models, which increases the precision of the survival estimates and enables to assess and account for effects of additional covariates. This paper provides a detailed presentation how model based period analysis may be used to derive population-based absolute and relative survival estimates using the freely available R language and statistical environment and already available R programs for period analysis. After an introduction of the underlying regression model and a description of the software tools we provide a step-by-step implementation of two regression models in R and illustrate how estimates and a test for trend over time in relative survival may be derived using data from a population based cancer registry. PMID:23116692

  20. Sleipner CCS site: velocity and attenuation model from seismic tomography

    NASA Astrophysics Data System (ADS)

    Rossi, G.; Chadwick, R. A.; Williams, G. A.

    2012-04-01

    The results of the travel-time and frequency shift tomographic inversion of the seismic data from one of the high-resolution lines acquired in 2006 on the Sleipner CO2 geological storage site are here presented. The work has been performed within the European project CO2ReMoVe, to produce an accurate model in-depth, of both seismic velocities and attenuation, to constrain better the quantification studies of the project's partners. Tomographic techniques have the advantage of not assuming horizontal layering or uniform lateral velocities, and of enabling an easy comparison of models, even if resulting from seismic data acquired with different geometries, unavoidable in a time-lapse data set. Through an iterative process, the differences in travel-times between observed direct, reflected or refracted arrivals and the same, calculated on a discrete model, with a ray-tracing based on the Fermat's principle, are minimized. Other minimization procedures provide the reflector/refractor geometries in -depth. Analogously, in attenuation tomography, the minimization process takes into account the observed and calculated spectral-centroid frequency-shift, due to the loss of the highest frequency of the seismic wave, while crossing an attenuating medium. The result is a seismic quality factor (Q) model in-depth, and hence of the attenuation that is known to be more sensitive to subtle changes in physical properties than seismic velocity. The model is across the center of the CO2 plume, on the in-line 1838, and is constituted by nine layers, four resulting by a preliminary analysis of the pre-injection 1994 data set, i.e. seabed, a strong reflection in the overburden and the top and bottom of the Utsira Sand, plus additional five horizons, four of which within Utsira Sands, and one just above the top of it. The layers within the reservoir are very close to each other and in some cases they merge together laterally. The accumulation of CO2 in the uppermost layer of the

  1. A new velocity-pressure-compaction model for uncemented sediments

    NASA Astrophysics Data System (ADS)

    Saul, M. J.; Lumley, D. E.

    2013-05-01

    Knowledge of the pressure dependence of rock properties is useful for a wide range of earth science problems, especially related to pore pressure changes caused by fluid injection or withdrawal, as often occurs in groundwater, hydrocarbon and CO2 sequestration reservoirs. A long-standing problem is that theoretical models of velocity-pressure response often do not match laboratory measurements, and alternately, empirical regressions fit to such data do not extrapolate accurately to wider pressure ranges since they have little or no physical basis. Accurate determination of the dry rock frame properties at low effective pressure is a key aspect of the problem, particularly when ultrasonic laboratory measurements are not available in this pressure range. We present a new model to describe the pressure sensitivity of the bulk and shear moduli for uncemented sedimentary rocks. Our model incorporates effects of sedimentary compaction and critical porosity, including a relationship to account for porosity and density change with pressure. The model is tested on laboratory measurements for various rock samples and fits well over a wide range of pressures. The new velocity-pressure model should be useful for improved prediction and interpretation of pressure-dependent rock properties and seismic data.

  2. Absolute Proper Motions to B~22.5. IV. Faint, Low-Velocity White Dwarfs and the White Dwarf Population Density Law

    NASA Astrophysics Data System (ADS)

    Majewski, S. R.; Siegel, M. H.

    2002-04-01

    The reduced proper-motion diagram (RPMD) for a complete sample of 819 faint (B<=22.5) stars with high-accuracy proper motions (σμ~1 mas yr-1) in an area of 0.3 deg2 in the north Galactic pole field SA 57 is investigated. Eight stars with very large reduced proper motions are identified as faint white dwarf candidates. On the basis of larger than 6 σ measured proper motions and the lack of photometric variability over a 20 yr baseline, we discriminate these white dwarf candidates from the several times more numerous quasi-stellar objects (QSOs), which can potentially occupy a similar location in the RPMD. For comparison, less than 4 σ proper motions and photometric variability are found in all but one of 35 spectroscopically confirmed QSOs in the same field. While spectroscopic confirmation of their status as white dwarfs is a necessary, but difficult, outstanding task, we discuss the implausibility that these stars could be any kind of survey contaminant. High-quality proper motions lend confidence in our ability to separate white dwarfs from subdwarfs in the RPMD. If bona fide white dwarfs, the eight candidates found here represent a portion of the white dwarf population that hitherto has remained uninvestigated by previous surveys by virtue of the faint magnitudes and low proper motions of the stars. This faint, low-velocity sample represents an increase in the white dwarf sky surface density to B=22.5 by an order of magnitude than that found in the previously most complete surveys to this depth. However, because the majority of the stars discovered here are at projected distances of more than a disk scale height above the Galactic midplane, their existence does not affect significantly the typical estimates of the local white dwarf density. On the other hand, as distant white dwarf candidates with low, typically thin-disk-like transverse velocities (<40 km s-1), the newly discovered stars suggest a disk white dwarf scale height larger than the values of 250

  3. Central United States Velocity Model Version 1: Description and Validation

    NASA Astrophysics Data System (ADS)

    Ramirez Guzman, L.; Williams, R. A.; Boyd, O. S.; Hartzell, S.

    2009-12-01

    We describe and test via numerical simulations a velocity model of the Central United States (CUSVM Version 1). Our model covers an area of 650,000 km2 and includes parts of Arkansas, Mississippi, Alabama, Illinois, Missouri, Kentucky and Tennessee. The model represents the compilation of research carried out for decades consisting of seismic refraction and reflection lines, geophysical logs, and inversions of the regional seismic properties. The CUSVM has a higher resolution description around Memphis and St. Louis, two of the largest urban areas in the Central United States. The density, p- and s-wave velocities are synthesized in a stand-alone spatial data base that can be queried to generate the required input for numerical simulations. We calibrate the CUSVM using three earthquakes located N, SW and SE of the zone encompassed by the model to sample different paths of propagation. The selected stations in the comparisons reflect different geological site conditions and cover distances ranging from 50 to 450 km away from the epicenters. The results indicate that both within and outside the Mississippi embayment, the CUSVM satisfactorily reproduces: a) the body wave arrival times and b) the observed regional variations in ground motion amplitude and duration in the frequency range 0-0.75Hz.

  4. Lattice Models for Granular-Like Velocity Fields: Hydrodynamic Description

    NASA Astrophysics Data System (ADS)

    Manacorda, Alessandro; Plata, Carlos A.; Lasanta, Antonio; Puglisi, Andrea; Prados, Antonio

    2016-07-01

    A recently introduced model describing—on a 1d lattice—the velocity field of a granular fluid is discussed in detail. The dynamics of the velocity field occurs through next-neighbours inelastic collisions which conserve momentum but dissipate energy. The dynamics is described through the corresponding Master Equation for the time evolution of the probability distribution. In the continuum limit, equations for the average velocity and temperature fields with fluctuating currents are derived, which are analogous to hydrodynamic equations of granular fluids when restricted to the shear modes. Therefore, the homogeneous cooling state, with its linear instability, and other relevant regimes such as the uniform shear flow and the Couette flow states are described. The evolution in time and space of the single particle probability distribution, in all those regimes, is also discussed, showing that the local equilibrium is not valid in general. The noise for the momentum and energy currents, which are correlated, are white and Gaussian. The same is true for the noise of the energy sink, which is usually negligible.

  5. Lattice Models for Granular-Like Velocity Fields: Hydrodynamic Description

    NASA Astrophysics Data System (ADS)

    Manacorda, Alessandro; Plata, Carlos A.; Lasanta, Antonio; Puglisi, Andrea; Prados, Antonio

    2016-08-01

    A recently introduced model describing—on a 1d lattice—the velocity field of a granular fluid is discussed in detail. The dynamics of the velocity field occurs through next-neighbours inelastic collisions which conserve momentum but dissipate energy. The dynamics is described through the corresponding Master Equation for the time evolution of the probability distribution. In the continuum limit, equations for the average velocity and temperature fields with fluctuating currents are derived, which are analogous to hydrodynamic equations of granular fluids when restricted to the shear modes. Therefore, the homogeneous cooling state, with its linear instability, and other relevant regimes such as the uniform shear flow and the Couette flow states are described. The evolution in time and space of the single particle probability distribution, in all those regimes, is also discussed, showing that the local equilibrium is not valid in general. The noise for the momentum and energy currents, which are correlated, are white and Gaussian. The same is true for the noise of the energy sink, which is usually negligible.

  6. College Students' Role Models, Learning Style Preferences, and Academic Achievement in Collaborative Teaching: Absolute versus Relativistic Thinking

    ERIC Educational Resources Information Center

    Chiou, Wen-Bin

    2008-01-01

    Based on the perspective of postformal operations, this study investigated whether college students' role models (technical teachers vs. lecturing teachers) and preferred learning styles (experience-driven mode vs. theory-driven mode) in collaborative teaching courses would be moderated by their cognitive development (absolute thinking vs.…

  7. Congruence of 3-D Whole Mantle Models of Shear Velocity

    NASA Astrophysics Data System (ADS)

    Dziewonski, A. M.; Lekic, V.; Romanowicz, B. A.

    2012-12-01

    The range of shear velocity anomalies in published whole mantle models is considerable. This impedes drawing conclusions of importance for geodynamic modeling and for interpretation of mineral physics results. However, if one considers only the models that were built using data that are sensitive to mantle structure at all depths, these models show robust features in their power spectra as a function of depth. On this basis we propose that there are five depth intervals with distinct spectral characteristics. 1. Heterosphere (Moho - 300 km) is characterized by strong power spectrum relatively flat up to degree 6. With lateral shear wavespeed variations as large as 15%, this zone accounts for more than 50% of the entire heterogeneity in the mantle. Differences among models for different tectonic regions decrease rapidly below 300 km depth. 2. Upper mantle buffer zone (300- 500 km) has a flat spectrum and the overall power of heterogeneity drops by an order of magnitude compared to the region above. There may be still weak difference between continents and oceans, but the oceanic regions lose their age dependence. The spectral characteristics do not change across the 410 km discontinuity. 3. Transition zone (500 - 650 km) The degree 2 anomaly becomes dominant. There are long wavelength anomalies in regions of the fastest plate subduction during the last 15-20 Ma, suggesting slab ponding above the 650 km discontinuity. Several slower-than-average anomalies of unknown origin are present in this depth range. 4. Lower mantle buffer zone (650 - 2300 km) has a weak, flat spectrum without long wavelength velocity anomalies that could be interpreted as unfragmented subducted slabs. However, there are three relatively narrow and short high velocity anomalies under Peru, Tonga and Indonesia that may indicate limited slab penetration. 5 Abyssal layer (2300 - CMB) Strong spectrum dominated by degrees 2 and 3. The amplitude is the largest at the CMB and decreases rapidly up to

  8. Modeling the exit velocity of a compressed air cannon

    NASA Astrophysics Data System (ADS)

    Rohrbach, Z. J.; Buresh, T. R.; Madsen, M. J.

    2012-01-01

    The use of compressed air cannons in an undergraduate laboratory provides a way to illustrate the connection between diverse physics concepts, such as conservation of momentum, the work-kinetic energy theorem, gas expansion, air drag, and elementary Newtonian mechanics. However, it is not clear whether the expansion of the gas in the cannon is an adiabatic or an isothermal process. We built an air cannon that utilizes a diaphragm valve to release the pressurized gas and found that neither process accurately predicts the exit velocity of our projectile. We discuss a model based on the flow of air through the valve, which is in much better agreement with our data.

  9. A model for ductile metal friction at high velocities

    NASA Astrophysics Data System (ADS)

    Hammerberg, J. E.; Ravelo, R. J.; Germann, T. C.

    We describe a meso-macro scale model for the frictional force at ductile metal interfaces for high velocities and large compressions. The model incorporates the micro-mesoscopic growth and refinement of material microstructure in a highly strained region at the sliding interface and incorporates both rate dependent plasticity and thermal conduction. The model compares favorably with recent large scale (1.8 billion atom) simulations to 50 ns of 3-dimensional polycrystalline 13-50 nm grain size Al-Al interfaces at pressures of 15 GPa using the SPaSM NonEquilibrium Molecular Dynamics (NEMD) simulation code. This work was performed under the auspices of the U.S. Dept. of Energy under Contract DE-AC52-06NA25396. The support of the LANL ASC-PEM program is gratefully acknowledged.

  10. Mean velocity and moments of turbulent velocity fluctuations in the wake of a model ship propulsor

    NASA Astrophysics Data System (ADS)

    Pêgo, J. P.; Lienhart, H.; Durst, F.

    2007-08-01

    Pod drives are modern outboard ship propulsion systems with a motor encapsulated in a watertight pod, whose shaft is connected directly to one or two propellers. The whole unit hangs from the stern of the ship and rotates azimuthally, thus providing thrust and steering without the need of a rudder. Force/momentum and phase-resolved laser Doppler anemometry (LDA) measurements were performed for in line co-rotating and contra-rotating propellers pod drive models. The measurements permitted to characterize these ship propulsion systems in terms of their hydrodynamic characteristics. The torque delivered to the propellers and the thrust of the system were measured for different operation conditions of the propellers. These measurements lead to the hydrodynamic optimization of the ship propulsion system. The parameters under focus revealed the influence of distance between propeller planes, propeller frequency of rotation ratio and type of propellers (co- or contra-rotating) on the overall efficiency of the system. Two of the ship propulsion systems under consideration were chosen, based on their hydrodynamic characteristics, for a detailed study of the swirling wake flow by means of laser Doppler anemometry. A two-component laser Doppler system was employed for the velocity measurements. A light barrier mounted on the axle of the rear propeller motor supplied a TTL signal to mark the beginning of each period, thus providing angle information for the LDA measurements. Measurements were conducted for four axial positions in the slipstream of the pod drive models. The results show that the wake of contra-rotating propeller is more homogeneous than when they co-rotate. In agreement with the results of the force/momentum measurements and with hypotheses put forward in the literature (see e.g. Poehls in Entwurfsgrundlagen für Schraubenpropeller, 1984; Schneekluth in Hydromechanik zum Schiffsentwurf, 1988; Breslin and Andersen in Hydrodynamics of ship propellers, 1996

  11. 3D geomechanical-numerical modelling of the absolute stress state for geothermal reservoir exploration

    NASA Astrophysics Data System (ADS)

    Reiter, Karsten; Heidbach, Oliver; Moeck, Inga

    2013-04-01

    For the assessment and exploration of a potential geothermal reservoir, the contemporary in-situ stress is of key importance in terms of well stability and orientation of possible fluid pathways. However, available data, e.g. Heidbach et al. (2009) or Zang et al. (2012), deliver only point wise information of parts of the six independent components of the stress tensor. Moreover most measurements of the stress orientation and magnitude are done for hydrocarbon industry obvious in shallow depth. Interpolation across long distances or extrapolation into depth is unfavourable, because this would ignore structural features, inhomogeneity's in the crust or other local effects like topography. For this reasons geomechanical numerical modelling is the favourable method to quantify orientations and magnitudes of the 3D stress field for a geothermal reservoir. A geomechanical-numerical modelling, estimating the 3D absolute stress state, requires the initial stress state as model constraints. But in-situ stress measurements within or close by a potential reservoir are rare. For that reason a larger regional geomechanical-numerical model is necessary, which derive boundary conditions for the wanted local reservoir model. Such a large scale model has to be tested against in-situ stress measurements, orientations and magnitudes. Other suitable and available data, like GPS measurements or fault slip rates are useful to constrain kinematic boundary conditions. This stepwise approach from regional to local scale takes all stress field factors into account, from first over second up to third order. As an example we present a large scale crustal and upper mantle 3D-geomechanical-numerical model of the Alberta Basin and the surroundings, which is constructed to describe continuously the full stress tensor. In-situ stress measurements are the most likely data, because they deliver the most direct information's of the stress field and they provide insights into different depths, a

  12. The Case for Absolute Ligand Discrimination: Modeling Information Processing and Decision by Immune T Cells

    NASA Astrophysics Data System (ADS)

    François, Paul; Altan-Bonnet, Grégoire

    2016-03-01

    Some cells have to take decision based on the quality of surroundings ligands, almost irrespective of their quantity, a problem we name "absolute discrimination". An example of absolute discrimination is recognition of not-self by immune T Cells. We show how the problem of absolute discrimination can be solved by a process called "adaptive sorting". We review several implementations of adaptive sorting, as well as its generic properties such as antagonism. We show how kinetic proofreading with negative feedback implement an approximate version of adaptive sorting in the immune context. Finally, we revisit the decision problem at the cell population level, showing how phenotypic variability and feedbacks between population and single cells are crucial for proper decision.

  13. Velocity Structure Determination Through Seismic Waveform Modeling and Time Deviations

    NASA Astrophysics Data System (ADS)

    Savage, B.; Zhu, L.; Tan, Y.; Helmberger, D. V.

    2001-12-01

    Through the use of seismic waveforms recorded by TriNet, a dataset of earthquake focal mechanisms and deviations (time shifts) relative to a standard model facilitates the investigation of the crust and uppermost mantle of southern California. The CAP method of focal mechanism determination, in use by TriNet on a routine basis, provides time shifts for surface waves and Pnl arrivals independently relative to the reference model. These shifts serve as initial data for calibration of local and regional seismic paths. Time shifts from the CAP method are derived by splitting the Pnl section of the waveform, the first arriving Pn to just before the arrival of the S wave, from the much slower surface waves then cross-correlating the data with synthetic waveforms computed from a standard model. Surface waves interact with the entire crust, but the upper crust causes the greatest effect. Whereas, Pnl arrivals sample the deeper crust, upper mantle, and source region. This natural division separates the upper from lower crust for regional calibration and structural modeling and allows 3-D velocity maps to be created using the resulting time shifts. Further examination of Pnl and other arrivals which interact with the Moho illuminate the complex nature of this boundary. Initial attempts at using the first 10 seconds of the Pnl section to determine upper most mantle structure have proven insightful. Two large earthquakes north of southern California in Nevada and Mammoth Lakes, CA allow the creation of record sections from 200 to 600 km. As the paths swing from east to west across southern California, simple 1-D models turn into complex structure, dramatically changing the waveform character. Using finite difference models to explain the structure, we determine that a low velocity zone is present at the base of the crust and extends to 100 km in depth. Velocity variations of 5 percent of the mantle in combination with steeply sloping edges produces complex waveform variations

  14. Traveling waves in an optimal velocity model of freeway traffic.

    PubMed

    Berg, P; Woods, A

    2001-03-01

    Car-following models provide both a tool to describe traffic flow and algorithms for autonomous cruise control systems. Recently developed optimal velocity models contain a relaxation term that assigns a desirable speed to each headway and a response time over which drivers adjust to optimal velocity conditions. These models predict traffic breakdown phenomena analogous to real traffic instabilities. In order to deepen our understanding of these models, in this paper, we examine the transition from a linear stable stream of cars of one headway into a linear stable stream of a second headway. Numerical results of the governing equations identify a range of transition phenomena, including monotonic and oscillating travelling waves and a time- dependent dispersive adjustment wave. However, for certain conditions, we find that the adjustment takes the form of a nonlinear traveling wave from the upstream headway to a third, intermediate headway, followed by either another traveling wave or a dispersive wave further downstream matching the downstream headway. This intermediate value of the headway is selected such that the nonlinear traveling wave is the fastest stable traveling wave which is observed to develop in the numerical calculations. The development of these nonlinear waves, connecting linear stable flows of two different headways, is somewhat reminiscent of stop-start waves in congested flow on freeways. The different types of adjustments are classified in a phase diagram depending on the upstream and downstream headway and the response time of the model. The results have profound consequences for autonomous cruise control systems. For an autocade of both identical and different vehicles, the control system itself may trigger formations of nonlinear, steep wave transitions. Further information is available [Y. Sugiyama, Traffic and Granular Flow (World Scientific, Singapore, 1995), p. 137]. PMID:11308709

  15. Traveling waves in an optimal velocity model of freeway traffic

    NASA Astrophysics Data System (ADS)

    Berg, Peter; Woods, Andrew

    2001-03-01

    Car-following models provide both a tool to describe traffic flow and algorithms for autonomous cruise control systems. Recently developed optimal velocity models contain a relaxation term that assigns a desirable speed to each headway and a response time over which drivers adjust to optimal velocity conditions. These models predict traffic breakdown phenomena analogous to real traffic instabilities. In order to deepen our understanding of these models, in this paper, we examine the transition from a linear stable stream of cars of one headway into a linear stable stream of a second headway. Numerical results of the governing equations identify a range of transition phenomena, including monotonic and oscillating travelling waves and a time- dependent dispersive adjustment wave. However, for certain conditions, we find that the adjustment takes the form of a nonlinear traveling wave from the upstream headway to a third, intermediate headway, followed by either another traveling wave or a dispersive wave further downstream matching the downstream headway. This intermediate value of the headway is selected such that the nonlinear traveling wave is the fastest stable traveling wave which is observed to develop in the numerical calculations. The development of these nonlinear waves, connecting linear stable flows of two different headways, is somewhat reminiscent of stop-start waves in congested flow on freeways. The different types of adjustments are classified in a phase diagram depending on the upstream and downstream headway and the response time of the model. The results have profound consequences for autonomous cruise control systems. For an autocade of both identical and different vehicles, the control system itself may trigger formations of nonlinear, steep wave transitions. Further information is available [Y. Sugiyama, Traffic and Granular Flow (World Scientific, Singapore, 1995), p. 137].

  16. A priori testing of subgrid-scale models for the velocity-pressure and vorticity-velocity formulations

    NASA Technical Reports Server (NTRS)

    Winckelmans, G. S.; Lund, T. S.; Carati, D.; Wray, A. A.

    1996-01-01

    Subgrid-scale models for Large Eddy Simulation (LES) in both the velocity-pressure and the vorticity-velocity formulations were evaluated and compared in a priori tests using spectral Direct Numerical Simulation (DNS) databases of isotropic turbulence: 128(exp 3) DNS of forced turbulence (Re(sub(lambda))=95.8) filtered, using the sharp cutoff filter, to both 32(exp 3) and 16(exp 3) synthetic LES fields; 512(exp 3) DNS of decaying turbulence (Re(sub(Lambda))=63.5) filtered to both 64(exp 3) and 32(exp 3) LES fields. Gaussian and top-hat filters were also used with the 128(exp 3) database. Different LES models were evaluated for each formulation: eddy-viscosity models, hyper eddy-viscosity models, mixed models, and scale-similarity models. Correlations between exact versus modeled subgrid-scale quantities were measured at three levels: tensor (traceless), vector (solenoidal 'force'), and scalar (dissipation) levels, and for both cases of uniform and variable coefficient(s). Different choices for the 1/T scaling appearing in the eddy-viscosity were also evaluated. It was found that the models for the vorticity-velocity formulation produce higher correlations with the filtered DNS data than their counterpart in the velocity-pressure formulation. It was also found that the hyper eddy-viscosity model performs better than the eddy viscosity model, in both formulations.

  17. Absolute Zero

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.; Sheibley, D.; Belloni, M.; Stamper-Kurn, D.; Vinen, W. F.

    2006-12-01

    Absolute Zero is a two hour PBS special attempting to bring to the general public some of the advances made in 400 years of thermodynamics. It is based on the book “Absolute Zero and the Conquest of Cold” by Tom Shachtman. Absolute Zero will call long-overdue attention to the remarkable strides that have been made in low-temperature physics, a field that has produced 27 Nobel Prizes. It will explore the ongoing interplay between science and technology through historical examples including refrigerators, ice machines, frozen foods, liquid oxygen and nitrogen as well as much colder fluids such as liquid hydrogen and liquid helium. A website has been established to promote the series: www.absolutezerocampaign.org. It contains information on the series, aimed primarily at students at the middle school level. There is a wealth of material here and we hope interested teachers will draw their student’s attention to this website and its substantial contents, which have been carefully vetted for accuracy.

  18. Velocity response curves demonstrate the complexity of modeling entrainable clocks.

    PubMed

    Taylor, Stephanie R; Cheever, Allyson; Harmon, Sarah M

    2014-12-21

    Circadian clocks are biological oscillators that regulate daily behaviors in organisms across the kingdoms of life. Their rhythms are generated by complex systems, generally involving interlocked regulatory feedback loops. These rhythms are entrained by the daily light/dark cycle, ensuring that the internal clock time is coordinated with the environment. Mathematical models play an important role in understanding how the components work together to function as a clock which can be entrained by light. For a clock to entrain, it must be possible for it to be sped up or slowed down at appropriate times. To understand how biophysical processes affect the speed of the clock, one can compute velocity response curves (VRCs). Here, in a case study involving the fruit fly clock, we demonstrate that VRC analysis provides insight into a clock׳s response to light. We also show that biochemical mechanisms and parameters together determine a model׳s ability to respond realistically to light. The implication is that, if one is developing a model and its current form has an unrealistic response to light, then one must reexamine one׳s model structure, because searching for better parameter values is unlikely to lead to a realistic response to light. PMID:25193284

  19. Unsteady velocity measurements in a realistic intracranial aneurysm model

    NASA Astrophysics Data System (ADS)

    Ugron, Ádám; Farinas, Marie-Isabelle; Kiss, László; Paál, György

    2012-01-01

    The initiation, growth and rupture of intracranial aneurysms are intensively studied by computational fluid dynamics. To gain confidence in the results of numerical simulations, validation of the results is necessary. To this end the unsteady flow was measured in a silicone phantom of a realistic intracranial aneurysm. A flow circuit was built with a novel unsteady flow rate generating method, used to model the idealised shape of the heartbeat. This allowed the measurement of the complex three-dimensional velocity distribution by means of laser-optical methods such as laser doppler anemometry (LDA) and particle image velocimetry (PIV). The PIV measurements, available with high temporal and spatial distribution, were found to have good agreement with the control LDA measurements. Furthermore, excellent agreement was found with the numerical results.

  20. Gender equality and women's absolute status: a test of the feminist models of rape.

    PubMed

    Martin, Kimberly; Vieraitis, Lynne M; Britto, Sarah

    2006-04-01

    Feminist theory predicts both a positive and negative relationship between gender equality and rape rates. Although liberal and radical feminist theory predicts that gender equality should ameliorate rape victimization, radical feminist theorists have argued that gender equality may increase rape in the form of male backlash. Alternatively, Marxist criminologists focus on women's absolute socioeconomic status rather than gender equality as a predictor of rape rates, whereas socialist feminists combine both radical and Marxist perspectives. This study uses factor analysis to overcome multicollinearity limitations of past studies while exploring the relationship between women's absolute and relative socioeconomic status on rape rates in major U.S. cities using 2000 census data. The findings indicate support for both the Marxist and radical feminist explanations of rape but no support for the ameliorative hypothesis. These findings support a more inclusive socialist feminist theory that takes both Marxist and radical feminist hypotheses into account. PMID:16567334

  1. Modeling Normal Shock Velocity Curvature Relation for Heterogeneous Explosives

    NASA Astrophysics Data System (ADS)

    Yoo, Sunhee; Crochet, Michael; Pemberton, Steve

    2015-06-01

    The normal shock velocity and curvature, Dn(κ) , relation on a detonation shock surface has been an important functional quantity to measure to understand the shock strength exerted against the material interface between a main explosive charge and the case of an explosive munition. The Dn(κ) relation is considered an intrinsic property of an explosive, and can be experimentally deduced by rate stick tests at various charge diameters. However, experimental measurements of the Dn(κ) relation for heterogeneous explosives such as PBXN-111 are challenging due to the non-smoothness and asymmetry usually observed in the experimental streak records of explosion fronts. Out of the many possibilities, the asymmetric character may be attributed to the heterogeneity of the explosives, a hypothesis which begs two questions: (1) is there any simple hydrodynamic model that can explain such an asymmetric shock evolution, and (2) what statistics can be derived for the asymmetry using simulations with defined structural heterogeneity in the unreacted explosive? Saenz, Taylor and Stewart studied constitutive models for derivation of the Dn(κ) relation on porous `homogeneous' explosives and carried out simulations in a spherical coordinate frame. In this paper, we extend their model to account for `heterogeneity' and present shock evolutions in heterogeneous explosives using 2-D hydrodynamic simulations with some statistical examination. (96TW-2015-0004)

  2. Modelling nonstationary Doppler noise in exoplanetary radial velocity data

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2015-08-01

    We construct a new class of analytic nonstationary noise models for exoplanetary Doppler data. The observable correlated noise is represented as a convolution of a parent activity process with a given memory function. The model honours the casuality principle, meaning that only past values of the activity may affect the observable value. This model does not approximate detailedly any real stellar activity phenomena, but it becomes mathematically simple, simultaneously satisfying the basic natural principles of physical sensibility and self-consistency.Additionally, we develop a new type of periodograms that can be used to detect periodic modulations in the Doppler noise characteristics, rather than in the observed radial velocity curve itself. We present first results of applying this technique to public Doppler time series available for a set of planet-hosting stars.This work was supported by the Russian Foundation for Basic Research (project No. 14-02-92615 KO_a), the UK Royal Society International Exchange grant IE140055, by the President of Russia grant for young scientists (No. MK-733.2014.2), by the programme of the Presidium of Russian Academy of Sciences P21, and by the Saint Petersburg State University research grant 6.37.341.2015.

  3. Authentication Based on Pole-zero Models of Signature Velocity.

    PubMed

    Rashidi, Saeid; Fallah, Ali; Towhidkhah, Farzad

    2013-10-01

    With the increase of communication and financial transaction through internet, on-line signature verification is an accepted biometric technology for access control and plays a significant role in authenticity and authorization in modernized society. Therefore, fast and precise algorithms for the signature verification are very attractive. The goal of this paper is modeling of velocity signal that pattern and properties is stable for persons. With using pole-zero models based on discrete cosine transform, precise method is proposed for modeling and then features is founded from strokes. With using linear, parzen window and support vector machine classifiers, the signature verification technique was tested with a large number of authentic and forgery signatures and has demonstrated the good potential of this technique. The signatures are collected from three different database include a proprietary database, the SVC2004 and the Sabanci University signature database benchmark databases. Experimental results based on Persian, SVC2004 and SUSIG databases show that our method achieves an equal error rate of 5.91%, 5.62% and 3.91% in the skilled forgeries, respectively. PMID:24696797

  4. Authentication Based on Pole-zero Models of Signature Velocity

    PubMed Central

    Rashidi, Saeid; Fallah, Ali; Towhidkhah, Farzad

    2013-01-01

    With the increase of communication and financial transaction through internet, on-line signature verification is an accepted biometric technology for access control and plays a significant role in authenticity and authorization in modernized society. Therefore, fast and precise algorithms for the signature verification are very attractive. The goal of this paper is modeling of velocity signal that pattern and properties is stable for persons. With using pole-zero models based on discrete cosine transform, precise method is proposed for modeling and then features is founded from strokes. With using linear, parzen window and support vector machine classifiers, the signature verification technique was tested with a large number of authentic and forgery signatures and has demonstrated the good potential of this technique. The signatures are collected from three different database include a proprietary database, the SVC2004 and the Sabanci University signature database benchmark databases. Experimental results based on Persian, SVC2004 and SUSIG databases show that our method achieves an equal error rate of 5.91%, 5.62% and 3.91% in the skilled forgeries, respectively. PMID:24696797

  5. Determining the importance of model calibration for forecasting absolute/relative changes in streamflow from LULC and climate changes

    USGS Publications Warehouse

    Niraula, Rewati; Meixner, Thomas; Norman, Laura M.

    2015-01-01

    Land use/land cover (LULC) and climate changes are important drivers of change in streamflow. Assessing the impact of LULC and climate changes on streamflow is typically done with a calibrated and validated watershed model. However, there is a debate on the degree of calibration required. The objective of this study was to quantify the variation in estimated relative and absolute changes in streamflow associated with LULC and climate changes with different calibration approaches. The Soil and Water Assessment Tool (SWAT) was applied in an uncalibrated (UC), single outlet calibrated (OC), and spatially-calibrated (SC) mode to compare the relative and absolute changes in streamflow at 14 gaging stations within the Santa Cruz River Watershed in southern Arizona, USA. For this purpose, the effect of 3 LULC, 3 precipitation (P), and 3 temperature (T) scenarios were tested individually. For the validation period, Percent Bias (PBIAS) values were >100% with the UC model for all gages, the values were between 0% and 100% with the OC model and within 20% with the SC model. Changes in streamflow predicted with the UC and OC models were compared with those of the SC model. This approach implicitly assumes that the SC model is “ideal”. Results indicated that the magnitude of both absolute and relative changes in streamflow due to LULC predicted with the UC and OC results were different than those of the SC model. The magnitude of absolute changes predicted with the UC and SC models due to climate change (both P and T) were also significantly different, but were not different for OC and SC models. Results clearly indicated that relative changes due to climate change predicted with the UC and OC were not significantly different than that predicted with the SC models. This result suggests that it is important to calibrate the model spatially to analyze the effect of LULC change but not as important for analyzing the relative change in streamflow due to climate change. This

  6. Absolute model ages of mantled surfaces in Malea Planum and Utopia Planitia, Mars.

    NASA Astrophysics Data System (ADS)

    Willmes, M.; Hiesinger, H.; Reiss, D.; Zanetti, M.

    2009-04-01

    The surface of Mars is partially covered by a latitude-dependent ice-rich smooth mantle in the middle and high latitudes (±30-60°) [1, 2]. These deposits relate to changes in the obliquity of Mars which have led to major shifts in the Martian climate and repeated global episodes of deposition [3]. The deposits vary in thickness and are usually independent of local geology, topography and elevation. In this study we have determined absolute model ages for the mantled surface units in Utopia Planitia (northern hemisphere) and Malea Planum (southern hemisphere) using crater statistics [4]. These regions show a specific type of mantle degradation called scalloped terrain, and modelled crater retention ages of the easily eroded mantle in these regions reveal the time since the last resurfacing. Images from the High Resolution Imaging Science Experiment (HiRISE) (25-50 cm/pixel spatial resolution) on board the Mars Reconnaissance Orbiter (MRO) were analyzed, continuous areas of smooth mantle were mapped, and small, fresh, unmodified craters were counted. Both regions show degradation features of the mantle in varying degrees. The mantle in Utopia Planitia appears heavily modified by polygonal fractures and scalloped depressions [5]. Scalloped depressions are also found in Malea Planum, but the mantle appears much smoother and less modified by periglacial processes [5, 6]. The study areas totalled 722 km² in Utopia Planitia, and 296 km² in Malea Planum. Model ages for these regions were determined using the chronology function of Hartmann and Neukum [4] and the production function Ivanov [7]. The model ages show that the mantle unit for the area mapped in Utopia Planitia is 0.65 (+0.35/-0.41) to 2.9 (+0.69/-0.75) Myr old and Malea Planum is 3.0 (+1.5/-1.7) to 4.5 (+1.3/-1.4) Myr old, and that both regions represent very recent Amazonian terrain. This is also in agreement with the observed young degradation features described by [6, 8]. We acknowledge that the

  7. Comparison of CME radial velocities from a flux rope model and an ice cream cone model

    NASA Astrophysics Data System (ADS)

    Kim, T.; Moon, Y.; Na, H.

    2011-12-01

    Coronal Mass Ejections (CMEs) on the Sun are the largest energy release process in the solar system and act as the primary driver of geomagnetic storms and other space weather phenomena on the Earth. So it is very important to infer their directions, velocities and three-dimensional structures. In this study, we choose two different models to infer radial velocities of halo CMEs since 2008 : (1) an ice cream cone model by Xue et al (2005) using SOHO/LASCO data, (2) a flux rope model by Thernisien et al. (2009) using the STEREO/SECCHI data. In addition, we use another flux rope model in which the separation angle of flux rope is zero, which is morphologically similar to the ice cream cone model. The comparison shows that the CME radial velocities from among each model have very good correlations (R>0.9). We will extending this comparison to other partial CMEs observed by STEREO and SOHO.

  8. Ultralow-velocity zone geometries resolved by multidimensional waveform modelling

    NASA Astrophysics Data System (ADS)

    Vanacore, E. A.; Rost, S.; Thorne, M. S.

    2016-07-01

    Ultralow-velocity zones (ULVZs) are thin patches of material with strongly reduced seismic wave speeds situated on top of the core-mantle boundary (CMB). A common phase used to detect ULVZs is SPdKS (SKPdS), an SKS wave with a short diffracted P leg along the CMB. Most previous efforts have examined ULVZ properties using 1-D waveform modelling approaches. We present waveform modelling results using the 2.5-D finite-difference algorithm PSVaxi allowing us better insight into ULVZ structure and location. We characterize ULVZ waveforms based on ULVZ elastic properties, shape and position along the SPdKS ray path. In particular, we vary the ULVZ location (e.g. source or receiver side), ULVZ topographical profiles (e.g. boxcar, trapezoidal or Gaussian) and ULVZ lateral scale along great circle path (2.5°, 5°, 10°). We observe several waveform effects absent in 1-D ULVZ models and show evidence for waveform effects allowing the differentiation between source and receiver side ULVZs. Early inception of the SPdKS/SKPdS phase is difficult to detect for receiver-side ULVZs with maximum shifts in SKPdS initiation of ˜3° in epicentral distance, whereas source-side ULVZs produce maximum shifts of SPdKS initiation of ˜5°, allowing clear separation of source- versus receiver-side structure. We present a case study using data from up to 300 broad-band stations in Turkey recorded between 2005 and 2010. We observe a previously undetected ULVZ in the southern Atlantic Ocean region centred near 45°S, 12.5°W, with a lateral scale of ˜3°, VP reduction of 10 per cent, VS reduction of 30 per cent and density increase of 10 per cent relative to PREM.

  9. The Candy Wrapper Velocity Model for the Earth's Inner Core

    NASA Astrophysics Data System (ADS)

    Mattesini, M.

    2014-12-01

    Recent global expansion of seismic data motivated a number of seismological studies of the Earth's inner core that proposed the existence of increasingly complex structure and anisotropy. In the meantime, new hypotheses of dynamic mechanisms have been put forward to interpret seismological results. Here, the nature of hemispherical dichotomy and anisotropy is re-investigated by bridging the observations of PKP(bc-df) differential travel-times with the iron bcc/hcp elastic properties computed from first-principles methods.The Candy Wrapper velocity model introduced here accounts for a dynamic picture of the inner core (i.e., the eastward drift of material), where different iron crystal shapes can be stabilized at the two hemispheres. We show that seismological data are best explained by a rather complicated, mosaic-like, structure of the inner core, where well-separated patches of different iron crystals compose the anisotropic western hemispherical region, and a conglomerate of almost indistinguishable iron phases builds-up the weakly anisotropic eastern side.

  10. An absolute chronology for early Egypt using radiocarbon dating and Bayesian statistical modelling

    PubMed Central

    Dee, Michael; Wengrow, David; Shortland, Andrew; Stevenson, Alice; Brock, Fiona; Girdland Flink, Linus; Bronk Ramsey, Christopher

    2013-01-01

    The Egyptian state was formed prior to the existence of verifiable historical records. Conventional dates for its formation are based on the relative ordering of artefacts. This approach is no longer considered sufficient for cogent historical analysis. Here, we produce an absolute chronology for Early Egypt by combining radiocarbon and archaeological evidence within a Bayesian paradigm. Our data cover the full trajectory of Egyptian state formation and indicate that the process occurred more rapidly than previously thought. We provide a timeline for the First Dynasty of Egypt of generational-scale resolution that concurs with prevailing archaeological analysis and produce a chronometric date for the foundation of Egypt that distinguishes between historical estimates. PMID:24204188

  11. Towards an Anisotropic Whole Mantle 3D Elastic Velocity Model

    NASA Astrophysics Data System (ADS)

    Panning, M. P.; Romanowicz, B.; Gung, Y.

    2001-12-01

    Many studies have documented the existence of anisotropy in the earth's upper mantle, concentrated in the top 200 km. This evidence comes from the study of surface waves as well as shear wave splitting. There is also evidence for shear wave splitting in D", at least in well sampled regions. There are some hints of anisotropy at the base of the transition zone. Tomographic models of the upper mantle have been developed with simplifying assumptions about the nature of the anisotropy, in order to minimize the number of free parameters in the inversions. Some assume transverse isotropy (e.g Ekström and Dziewonski, 1997), others include additional degrees of freedom with some realistic constraints on mineralogy (e.g. Montagner and Tanimoto, 1991). Our goal is to investigate anisotropy in the whole mantle, using the framework of waveform inversion, and the nonlinear asymptotic mode coupling theory (NACT), previously developed and applied to the construction of whole-mantle SH velocity models (Li and Romanowicz, 1996; Mégnin and Romanowicz, 2000). For this we require a 3 component dataset, and we have extended our automatic transverse (T) component wavepicking procedures to the vertical (Z) and longitudinal (L) component - a non-trivial task given the large number of phases present in the coupled P-SV system. A useful initial assumption, for which the theory has been readily adapted, is that of transverse isotropy. As a first step towards this, we have been investigating inversions using T component and Z,L component data separately. In particular, this allows us to explore the sampling that can be achieved with Z,L component data alone in the deepest part of the mantle. Indeed, D" is in general much better sampled in SH than in SV, owing to the availability of SHdiff at large distances, while SVdiff decays more rapidly due to mantle-core coupling. We present the results of our resolution experiments and discuss the differences between the 3D SV model obtained in well

  12. College students' role models, learning style preferences, and academic achievement in collaborative teaching: absolute versus relativistic thinking.

    PubMed

    Chiou, Wen-Bin

    2008-01-01

    Based on the perspective of postformal operations, this study investigated whether college students' role models (technical teachers vs. lecturing teachers) and preferred learning styles (experience-driven mode vs. theory-driven mode) in collaborative teaching courses would be moderated by their cognitive development (absolute thinking vs. relativistic thinking) and examine whether academic achievement of students would be contingent upon their preferred learning styles. Two hundred forty-four college students who have taken the technical courses with collaborative teaching participated in this study. The results showed that those participants with absolute thinking perceived the modeling advantage of technical teachers was greater than that of lecturing teachers, preferred the experience-driven mode over the theory-driven mode, and displayed differential academic achievement between technical courses and general courses. On the other hand, the students with relativistic thinking revealed no difference in perceived modeling advantage of role models, learning styles preferences, and academic achievement between two categories of courses. In addition, this research indicates that college students' preferred learning styles would interact with course category (technical courses vs. general courses) to display differential academic achievement. Implications and future directions are discussed. PMID:18447085

  13. A mathematical model of turbulence in flows with uniform stationary velocity gradients

    NASA Technical Reports Server (NTRS)

    Zak, M. A.

    1982-01-01

    Certain cases of turbulence as a postinstability state of a fluid in motion modeled by the introduction of multivalued velocity fields are examined. The turbulence is regarded as occurring in the form of random pulsations which grow until the external energy input in the average flow is balanced by the dissipated energy of pulsations by means of turbulent friction. Closed form analytic solutions are shown to be possible when the considered velocity fields, the pulsation velocity and the fluid velocity, are decoupled.

  14. An empirical model to forecast solar wind velocity through statistical modeling

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Ridley, A. J.

    2013-12-01

    The accurate prediction of the solar wind velocity has been a major challenge in the space weather community. Previous studies proposed many empirical and semi-empirical models to forecast the solar wind velocity based on either the historical observations, e.g. the persistence model, or the instantaneous observations of the sun, e.g. the Wang-Sheeley-Arge model. In this study, we use the one-minute WIND data from January 1995 to August 2012 to investigate and compare the performances of 4 models often used in literature, here referred to as the null model, the persistence model, the one-solar-rotation-ago model, and the Wang-Sheeley-Arge model. It is found that, measured by root mean square error, the persistence model gives the most accurate predictions within two days. Beyond two days, the Wang-Sheeley-Arge model serves as the best model, though it only slightly outperforms the null model and the one-solar-rotation-ago model. Finally, we apply the least-square regression to linearly combine the null model, the persistence model, and the one-solar-rotation-ago model to propose a 'general persistence model'. By comparing its performance against the 4 aforementioned models, it is found that the accuracy of the general persistence model outperforms the other 4 models within five days. Due to its great simplicity and superb performance, we believe that the general persistence model can serve as a benchmark in the forecast of solar wind velocity and has the potential to be modified to arrive at better models.

  15. Key elements of regional seismic velocity models for long period ground motion simulations

    USGS Publications Warehouse

    Brocher, T.M.

    2008-01-01

    Regional 3-D seismic velocity models used for broadband strong motion simulations must include compressional-wave velocity (Vp), shear-wave velocity (Vs), intrinsic attenuation (Qp, Qs), and density. Vs and Qs are the most important of these parameters because the strongest ground motions are generated chiefly by shear- and surface-wave arrivals. Because Vp data are more common than Vs data, many researchers first develop a Vp model and convert it to a Vs model. I describe recent empirical relations between Vs, Vp, Qs, Qp, and density that allow velocity models to be rapidly and accurately calculated. ?? Springer Science+Business Media B.V. 2007.

  16. Stochastic and empirical models of the absolute asymmetric synthesis by the Soai-autocatalysis.

    PubMed

    Barabás, Béla; Zucchi, Claudia; Maioli, Marco; Micskei, Károly; Pályi, Gyula

    2015-02-01

    Absolute asymmetric synthesis (AAS) is the preparation of pure (or excess of one) enantiomer of a chiral compound from achiral precursor(s) by a chemical reaction, without enantiopure chiral additive and/or without applied asymmetric physical field. Only one well-characterized example of AAS is known today: the Soai-autocatalysis. In an attempt at clarification of the mechanism of this particular reaction we have undertaken empirical and stochastic analysis of several parallel AAS experiments. Our results show that the initial steps of the reaction might be controlled by simple normal distribution ("coin tossing") formalism. Advanced stages of the reaction, however, appear to be of a more complicated nature. Symmetric beta distribution formalism could not be brought into correspondence with the experimental observations. A bimodal beta distribution algorithm provided suitable agreement with the experimental data. The parameters of this bimodal beta function were determined by a Pólya-urn experiment (simulated by computer). Interestingly, parameters of the resulting bimodal beta function give a golden section ratio. These results show, that in this highly interesting autocatalysis two or even perhaps three catalytic cycles are cooperating. An attempt at constructing a "designed" Soai-type reaction system has also been made. PMID:25644371

  17. Shuttle data book: SRM fragment velocity model. Presented to the SRB Fragment Model Review Panel

    NASA Technical Reports Server (NTRS)

    1989-01-01

    This study was undertaken to determine the velocity of fragments generated by the range safety destruction (RSD) or random failure of a Space Transportation System (STS) Solid Rocket Motor (SRM). The specific requirement was to provide a fragment model for use in those Galileo and Ulysses RTG safety analyses concerned with possible fragment impact on the spacecraft radioisotope thermoelectric generators (RTGS). Good agreement was obtained between predictions and observations for fragment velocity, velocity distributions, azimuths, and rotation rates. Based on this agreement with the entire data base, the model was used to predict the probable fragment environments which would occur in the event of an STS-SRM RSD or randon failure at 10, 74, 84 and 110 seconds. The results of these predictions are the basis of the fragment environments presented in the Shuttle Data Book (NSTS-08116). The information presented here is in viewgraph form.

  18. A strict test of stellar evolution models: The absolute dimensions of the massive benchmark eclipsing binary V578 Mon

    SciTech Connect

    Garcia, E. V.; Stassun, Keivan G.; Pavlovski, K.; Hensberge, H.; Chew, Y. Gómez Maqueo; Claret, A.

    2014-09-01

    We determine the absolute dimensions of the eclipsing binary V578 Mon, a detached system of two early B-type stars (B0V + B1V, P = 2.40848 days) in the star-forming region NGC 2244 of the Rosette Nebula. From the light curve analysis of 40 yr of photometry and the analysis of HERMES spectra, we find radii of 5.41 ± 0.04 R{sub ☉} and 4.29 ± 0.05 R{sub ☉}, and temperatures of 30,000 ± 500 K and 25,750 ± 435 K, respectively. We find that our disentangled component spectra for V578 Mon agree well with previous spectral disentangling from the literature. We also reconfirm the previous spectroscopic orbit of V578 Mon finding that masses of 14.54 ± 0.08 M{sub ☉} and 10.29 ± 0.06 M{sub ☉} are fully compatible with the new analysis. We compare the absolute dimensions to the rotating models of the Geneva and Utrecht groups and the models of the Granada group. We find that all three sets of models marginally reproduce the absolute dimensions of both stars with a common age within the uncertainty for gravity-effective temperature isochrones. However, there are some apparent age discrepancies for the corresponding mass-radius isochrones. Models with larger convective overshoot, >0.35, worked best. Combined with our previously determined apsidal motion of 0.07089{sub −0.00013}{sup +0.00021} deg cycle{sup –1}, we compute the internal structure constants (tidal Love number) for the Newtonian and general relativistic contribution to the apsidal motion as log k {sub 2} = –1.975 ± 0.017 and log k {sub 2} = –3.412 ± 0.018, respectively. We find the relativistic contribution to the apsidal motion to be small, <4%. We find that the prediction of log k {sub 2,theo} = –2.005 ± 0.025 of the Granada models fully agrees with our observed log k {sub 2}.

  19. A Velocity Distribution Model for Steady State Heat Transfer

    NASA Technical Reports Server (NTRS)

    Hall, Eric B.

    1996-01-01

    Consider a box that is filled with an ideal gas and that is aligned along Cartesian coordinates (x, y, z) having until length in the 'y' direction and unspecified length in the 'x' and 'z' directions. Heat is applied uniformly over the 'hot' end of the box (y = 1) and is removed uniformly over the 'cold' end (y = O) at a constant rate such that the ends of the box are maintained at temperatures T(sub 0) at y = O and T(sub 1) at y = 1. Let U, V, and W denote the respective velocity components of a molecule inside the box selected at some random time and at some location (x, y, z). If T(sub 0) = T(sub 1), then U, Y, and W are mutually independent and Gaussian, each with mean zero and variance RT(sub 0), where R is the gas constant. When T(sub 0) does not equal T(sub 1) the velocity components are not independent and are not Gaussian. Our objective is to characterize the joint distribution of the velocity components U, Y, and W as a function of y, and, in particular, to characterize the distribution of V given y. It is hoped that this research will lead to an increased physical understanding of the nature of turbulence.

  20. Modelling the maximum voluntary joint torque/angular velocity relationship in human movement.

    PubMed

    Yeadon, Maurice R; King, Mark A; Wilson, Cassie

    2006-01-01

    The force exerted by a muscle is a function of the activation level and the maximum (tetanic) muscle force. In "maximum" voluntary knee extensions muscle activation is lower for eccentric muscle velocities than for concentric velocities. The aim of this study was to model this "differential activation" in order to calculate the maximum voluntary knee extensor torque as a function of knee angular velocity. Torque data were collected on two subjects during maximal eccentric-concentric knee extensions using an isovelocity dynamometer with crank angular velocities ranging from 50 to 450 degrees s(-1). The theoretical tetanic torque/angular velocity relationship was modelled using a four parameter function comprising two rectangular hyperbolas while the activation/angular velocity relationship was modelled using a three parameter function that rose from submaximal activation for eccentric velocities to full activation for high concentric velocities. The product of these two functions gave a seven parameter function which was fitted to the joint torque/angular velocity data, giving unbiased root mean square differences of 1.9% and 3.3% of the maximum torques achieved. Differential activation accounts for the non-hyperbolic behaviour of the torque/angular velocity data for low concentric velocities. The maximum voluntary knee extensor torque that can be exerted may be modelled accurately as the product of functions defining the maximum torque and the maximum voluntary activation level. Failure to include differential activation considerations when modelling maximal movements will lead to errors in the estimation of joint torque in the eccentric phase and low velocity concentric phase. PMID:16389087

  1. Velocity mapping and models of the elliptical galaxies NGC 720, NGC 1052, and NGC 4697

    SciTech Connect

    Binney, J.J.; Davies, R.L.; Illingworth, G.D. Oxford Univ. National Optical Astronomy Observatories, Tucson, AZ California Univ., Santa Cruz )

    1990-09-01

    CCD surface photometry and extensive long-slit spectroscopy are used to construct detailed models of the flattened ellipticals NGC 720, 1052, and 4697. The models are combined with the Jeans equations to yield predicted fields of line-of-sight velocity dispersion and streaming velocity. By comparing these fields with observed velocities, it is concluded that none of these systems can have isotropic velocity dispersion tensors, and diminishing the assumed inclination of any given galaxy tends to decrease the line-of-sight velocity dispersion and, counterintuitively, to increase the line-of-sight rotation speeds. The ratio of the line-of-sight velocity dispersion along the minor axis to that along the major axis is found to be a sensitive diagnostic of the importance of a third integral for the galaxy's structure. 48 refs.

  2. Velocity mapping and models of the elliptical galaxies NGC 720, NGC 1052, and NGC 4697

    NASA Technical Reports Server (NTRS)

    Binney, J. J.; Davies, Roger L.; Illingworth, Garth D.

    1990-01-01

    CCD surface photometry and extensive long-slit spectroscopy are used to construct detailed models of the flattened ellipticals NGC 720, 1052, and 4697. The models are combined with the Jeans equations to yield predicted fields of line-of-sight velocity dispersion and streaming velocity. By comparing these fields with observed velocities, it is concluded that none of these systems can have isotropic velocity dispersion tensors, and diminishing the assumed inclination of any given galaxy tends to decrease the line-of-sight velocity dispersion and, counterintuitively, to increase the line-of-sight rotation speeds. The ratio of the line-of-sight velocity dispersion along the minor axis to that along the major axis is found to be a sensitive diagnostic of the importance of a third integral for the galaxy's structure.

  3. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  4. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  5. Revised Absolute Configuration of Sibiricumin A: Substituent Effects in Simplified Model Structures Used for Quantum Mechanical Predictions of Chiroptical Properties.

    PubMed

    Zhao, Dan; Li, Zheng-Qiu; Cao, Fei; Liang, Miao-Miao; Pittman, Charles U; Zhu, Hua-Jie; Li, Li; Yu, Shi-Shan

    2016-08-01

    This study discusses the choice of different simplified models used in computations of electronic circular dichroism (ECD) spectra and other chiroptical characteristics used to determine the absolute configuration (AC) of the complex natural product sibiricumin A. Sections of molecules containing one chiral center with one near an aromatic group have large effects on the ECD spectra. Conversely, when the phenyl group is present on a substituent without a nonstereogenic center, removal of this section will have little effect on ECD spectra. However, these nonstereogenic-center-containing sections have large effects on calculated optical rotations (OR) values since the OR value is more sensitive to the geometries of sections in a molecule. In this study, the wrong AC of sibiricumin A was reassigned as (7R,8S,1'R,7'R,8'S)-. Chirality 28:612-617, 2016. © 2016 Wiley Periodicals, Inc. PMID:27428019

  6. A 2015 International Geomagnetic Reference Field (IGRF) candidate model based on Swarm's experimental absolute magnetometer vector mode data

    NASA Astrophysics Data System (ADS)

    Vigneron, Pierre; Hulot, Gauthier; Olsen, Nils; Léger, Jean-Michel; Jager, Thomas; Brocco, Laura; Sirol, Olivier; Coïsson, Pierdavide; Lalanne, Xavier; Chulliat, Arnaud; Bertrand, François; Boness, Axel; Fratter, Isabelle

    2015-06-01

    Each of the three satellites of the European Space Agency Swarm mission carries an absolute scalar magnetometer (ASM) that provides the nominal 1-Hz scalar data of the mission for both science and calibration purposes. These ASM instruments, however, also deliver autonomous 1-Hz experimental vector data. Here, we report on how ASM-only scalar and vector data from the Alpha and Bravo satellites between November 29, 2013 (a week after launch) and September 25, 2014 (for on-time delivery of the model on October 1, 2014) could be used to build a very valuable candidate model for the 2015.0 International Geomagnetic Reference Field (IGRF). A parent model was first computed, describing the geomagnetic field of internal origin up to degree and order 40 in a spherical harmonic representation and including a constant secular variation up to degree and order 8. This model was next simply forwarded to epoch 2015.0 and truncated at degree and order 13. The resulting ASM-only 2015.0 IGRF candidate model is compared to analogous models derived from the mission's nominal data and to the now-published final 2015.0 IGRF model. Differences among models mainly highlight uncertainties enhanced by the limited geographical distribution of the selected data set (essentially due to a lack of availability of data at high northern latitude satisfying nighttime conditions at the end of the time period considered). These appear to be comparable to differences classically observed among IGRF candidate models. These positive results led the ASM-only 2015.0 IGRF candidate model to contribute to the construction of the final 2015.0 IGRF model.

  7. Full velocity difference and acceleration model for a car-following theory

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Liu, Qingling; Li, Xiuhai

    2013-05-01

    In order to describe the car-following behavior more actually in real traffic, a full velocity difference and acceleration model (for short, FVDAM) is proposed by synthetically taking into account headway, velocity difference and acceleration of the leading car on the basis of full velocity difference model. The analytical method and numerical simulation results show that the proposed model can describe the phase transition of traffic flow and estimate the evolution of traffic congestion, that incorporating the acceleration of the leading car into car-following model can stabilize traffic flow, suppress the traffic jam and increase capacity, and that the following car in FVDAM can accelerate more quickly than in FVDM.

  8. The Dynamics of Scaling: A Memory-Based Anchor Model of Category Rating and Absolute Identification

    ERIC Educational Resources Information Center

    Petrov, Alexander A.; Anderson, John R.

    2005-01-01

    A memory-based scaling model--ANCHOR--is proposed and tested. The perceived magnitude of the target stimulus is compared with a set of anchors in memory. Anchor selection is probabilistic and sensitive to similarity, base-level strength, and recency. The winning anchor provides a reference point near the target and thereby converts the global…

  9. Absolute/convective instability of planar viscoelastic jets

    NASA Astrophysics Data System (ADS)

    Ray, Prasun K.; Zaki, Tamer A.

    2015-01-01

    Spatiotemporal linear stability analysis is used to investigate the onset of local absolute instability in planar viscoelastic jets. The influence of viscoelasticity in dilute polymer solutions is modeled with the FENE-P constitutive equation which requires the specification of a non-dimensional polymer relaxation time (the Weissenberg number, We), the maximum polymer extensibility, L, and the ratio of solvent and solution viscosities, β. A two-parameter family of velocity profiles is used as the base state with the parameter, S, controlling the amount of co- or counter-flow while N-1 sets the thickness of the jet shear layer. We examine how the variation of these fluid and flow parameters affects the minimum value of S at which the flow becomes locally absolutely unstable. Initially setting the Reynolds number to Re = 500, we find that the first varicose jet-column mode dictates the presence of absolute instability, and increasing the Weissenberg number produces important changes in the nature of the instability. The region of absolute instability shifts towards thin shear layers, and the amount of back-flow needed for absolute instability decreases (i.e., the influence of viscoelasticity is destabilizing). Additionally, when We is sufficiently large and N-1 is sufficiently small, single-stream jets become absolutely unstable. Numerical experiments with approximate equations show that both the polymer and solvent contributions to the stress become destabilizing when the scaled shear rate, η = /W e dU¯1/dx 2L ( /d U ¯ 1 d x 2 is the base-state velocity gradient), is sufficiently large. These qualitative trends are largely unchanged when the Reynolds number is reduced; however, the relative importance of the destabilizing stresses increases tangibly. Consequently, absolute instability is substantially enhanced, and single-stream jets become absolutely unstable over a sizable portion of the parameter space.

  10. A probabilistic model of absolute auditory thresholds and its possible physiological basis.

    PubMed

    Heil, Peter; Neubauer, Heinrich; Tetschke, Manuel; Irvine, Dexter R F

    2013-01-01

    Detection thresholds for auditory stimuli, specified in terms of their -amplitude or level, depend on the stimulus temporal envelope and decrease with increasing stimulus duration. The neural mechanisms underlying these fundamental across-species observations are not fully understood. Here, we present a "continuous look" model, according to which the stimulus gives rise to stochastic neural detection events whose probability of occurrence is proportional to the 3rd power of the low-pass filtered, time-varying stimulus amplitude. Threshold is reached when a criterion number of events have occurred (probability summation). No long-term integration is required. We apply the model to an extensive set of thresholds measured in humans for tones of different envelopes and durations and find it to fit well. Subtle differences at long durations may be due to limited attention resources. We confirm the probabilistic nature of the detection events by analyses of simple reaction times and verify the exponent of 3 by validating model predictions for binaural thresholds from monaural thresholds. The exponent originates in the auditory periphery, possibly in the intrinsic Ca(2+) cooperativity of the Ca(2+) sensor involved in exocytosis from inner hair cells. It results in growth of the spike rate of auditory-nerve fibers (ANFs) with the 3rd power of the stimulus amplitude before saturating (Heil et al., J Neurosci 31:15424-15437, 2011), rather than with its square (i.e., with stimulus intensity), as is commonly assumed. Our work therefore suggests a link between detection thresholds and a key biochemical reaction in the receptor cells. PMID:23716205

  11. Inherently mass-conservative version of the semi-Lagrangian Absolute Vorticity (SL-AV) atmospheric model dynamical core

    NASA Astrophysics Data System (ADS)

    Shashkin, V. V.; Tolstykh, M. A.

    2013-09-01

    The semi-Lagrangian Absolute Vorticity (SL-AV) atmospheric model is the global semi-Lagrangian hydrostatic model used for operational medium-range and seasonal forecasts at Hydrometeorological centre of Russia. The distinct feature of SL-AV dynamical core is the semi-implicit semi-Lagrangian vorticity-divergence formulation on the unstaggered grid. Semi-implicit semi-Lagrangian approach allows for long time steps while violates the global and local mass-conservation. In particular, the total mass in simulations with semi-Lagrangian models can drift significantly if no aposteriori mass-fixing algorithms are applied. However, the global mass-fixing algorithms degrade the local mass conservation. The inherently mass-conservative version of SL-AV model dynamical core presented in the article ensures global and local mass conservation without mass-fixing algorithms. The mass conservation is achieved with the introduction of the finite-volume semi-Lagrangian discretization for continuity equation based on the 3-D extension of the conservative cascade semi-Lagrangian transport scheme (CCS). The numerical experiments show that the presented new version of SL-AV dynamical core combines the accuracy and stability of the standard SL-AV dynamical core with the mass-conservation properties. The results of the mountain induced Rossby wave test and baroclinic instability test for mass-conservative dynamical core are found to be in agreement with the results available in literature.

  12. Inherently mass-conservative version of the semi-Lagrangian absolute vorticity (SL-AV) atmospheric model dynamical core

    NASA Astrophysics Data System (ADS)

    Shashkin, V. V.; Tolstykh, M. A.

    2014-02-01

    The semi-Lagrangian absolute vorticity (SL-AV) atmospheric model is the global semi-Lagrangian hydrostatic model used for operational medium-range and seasonal forecasts at the Hydrometeorological Centre of Russia. The distinct feature of the SL-AV dynamical core is the semi-implicit, semi-Lagrangian vorticity-divergence formulation on the unstaggered grid. A semi-implicit, semi-Lagrangian approach allows for long time steps but violates the global and local mass conservation. In particular, the total mass in simulations with semi-Lagrangian models can drift significantly if no a posteriori mass-fixing algorithm is applied. However, the global mass-fixing algorithms degrade the local mass conservation. The new inherently mass-conservative version of the SL-AV model dynamical core presented here ensures global and local mass conservation without mass-fixing algorithms. The mass conservation is achieved with the introduction of the finite-volume, semi-Lagrangian discretization for a continuity equation based on the 3-D extension of the conservative cascade semi-Lagrangian transport scheme (CCS). Numerical experiments show that the new version of the SL-AV dynamical core presented combines the accuracy and stability of the standard SL-AV dynamical core with the mass-conservation properties. The results of the mountain-induced Rossby-wave test and baroclinic instability test for the mass-conservative dynamical core are found to be in agreement with the results available in the literature.

  13. A model equation for the joint distribution of the length and velocity difference of streamline segments in turbulent flows

    NASA Astrophysics Data System (ADS)

    Schaefer, P.; Gampert, M.; Peters, N.

    2013-11-01

    Streamlines recently received attention as natural geometries of turbulent flow fields. Similar to dissipation elements in scalar fields, streamlines are segmented into smaller subunits based on local extreme points of the absolute value of the velocity field u along the streamline coordinate s, i.e., points where the projected gradient in streamline direction us = 0. Then, streamline segments are parameterized using their arclength l between two neighboring extrema and the velocity difference Δ at the extrema. Both parameters are statistical variables and streamline segments are characterized by the joint probability density function (jpdf) P(l, Δ). Based on a previously formulated model for the marginal pdf of the arclength, P(l), which contains terms that account for slow changes as well as fast changes of streamline segments, a model for the jpdf is formulated. The jpdf's, when normalized with the mean length, lm, and the standard deviation of the velocity difference σ, obtained from two different direct numerical simulations (DNS) cases of homogeneous isotropic decaying and forced turbulence at Taylor based Reynolds number of Reλ = 116 and Reλ = 206, respectively, turn out to be almost Reynolds number independent. The steady model solution is compared with the normalized jpdf's obtained from DNS and it is found to be in good agreement. Special attention is paid to the intrinsic asymmetry of the jpdf with respect to the mean length of positive and negative streamline segments, where due to the kinematic stretching of positive segments and compression of negative ones, the mean length of positive segments turns out to be larger than the mean length of negative ones. This feature is reproduced by the model and the ratio of the two length scales, which turns out to be an almost Reynolds number independent, dimensionless quantity, is well reproduced. Finally, a relation between the kinetic asymmetry of streamline segments and the dynamic asymmetry of the pdf

  14. Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength

    USGS Publications Warehouse

    Beeler, N.M.; Tullis, T.E.

    1996-01-01

    Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The

  15. Impact of velocity correlation and distribution on transport in fractured media: Field evidence and theoretical model

    NASA Astrophysics Data System (ADS)

    Kang, Peter K.; Le Borgne, Tanguy; Dentz, Marco; Bour, Olivier; Juanes, Ruben

    2015-02-01

    Flow and transport through fractured geologic media often leads to anomalous (non-Fickian) transport behavior, the origin of which remains a matter of debate: whether it arises from variability in fracture permeability (velocity distribution), connectedness in the flow paths through fractures (velocity correlation), or interaction between fractures and matrix. Here we show that this uncertainty of distribution- versus correlation-controlled transport can be resolved by combining convergent and push-pull tracer tests because flow reversibility is strongly dependent on velocity correlation, whereas late-time scaling of breakthrough curves is mainly controlled by velocity distribution. We build on this insight, and propose a Lagrangian statistical model that takes the form of a continuous time random walk (CTRW) with correlated particle velocities. In this framework, velocity distribution and velocity correlation are quantified by a Markov process of particle transition times that is characterized by a distribution function and a transition probability. Our transport model accurately captures the anomalous behavior in the breakthrough curves for both push-pull and convergent flow geometries, with the same set of parameters. Thus, the proposed correlated CTRW modeling approach provides a simple yet powerful framework for characterizing the impact of velocity distribution and correlation on transport in fractured media.

  16. A crustal seismic velocity model for the UK, Ireland and surrounding seas

    USGS Publications Warehouse

    Kelly, A.; England, R.W.; Maguire, Peter K.H.

    2007-01-01

    A regional model of the 3-D variation in seismic P-wave velocity structure in the crust of NW Europe has been compiled from wide-angle reflection/refraction profiles. Along each 2-D profile a velocity-depth function has been digitised at 5 km intervals. These 1-D velocity functions were mapped into three dimensions using ordinary kriging with weights determined to minimise the difference between digitised and interpolated values. An analysis of variograms of the digitised data suggested a radial isotropic weighting scheme was most appropriate. Horizontal dimensions of the model cells are optimised at 40 ?? 40 km and the vertical dimension at 1 km. The resulting model provides a higher resolution image of the 3-D variation in seismic velocity structure of the UK, Ireland and surrounding areas than existing models. The construction of the model through kriging allows the uncertainty in the velocity structure to be assessed. This uncertainty indicates the high density of data required to confidently interpolate the crustal velocity structure, and shows that for this region the velocity is poorly constrained for large areas away from the input data. ?? 2007 The Authors Journal compilation ?? 2007 RAS.

  17. A dual-phantom system for validation of velocity measurements in stenosis models under steady flow.

    PubMed

    Blake, James R; Easson, William J; Hoskins, Peter R

    2009-09-01

    A dual-phantom system is developed for validation of velocity measurements in stenosis models. Pairs of phantoms with identical geometry and flow conditions are manufactured, one for ultrasound and one for particle image velocimetry (PIV). The PIV model is made from silicone rubber, and a new PIV fluid is made that matches the refractive index of 1.41 of silicone. Dynamic scaling was performed to correct for the increased viscosity of the PIV fluid compared with that of the ultrasound blood mimic. The degree of stenosis in the models pairs agreed to less than 1%. The velocities in the laminar flow region up to the peak velocity location agreed to within 15%, and the difference could be explained by errors in ultrasound velocity estimation. At low flow rates and in mild stenoses, good agreement was observed in the distal flow fields, excepting the maximum velocities. At high flow rates, there was considerable difference in velocities in the poststenosis flow field (maximum centreline differences of 30%), which would seem to represent real differences in hydrodynamic behavior between the two models. Sources of error included: variation of viscosity because of temperature (random error, which could account for differences of up to 7%); ultrasound velocity estimation errors (systematic errors); and geometry effects in each model, particularly because of imperfect connectors and corners (systematic errors, potentially affecting the inlet length and flow stability). The current system is best placed to investigate measurement errors in the laminar flow region rather than the poststenosis turbulent flow region. PMID:19540655

  18. Error propagation for velocity and shear stress prediction using 2D models for environmental management

    NASA Astrophysics Data System (ADS)

    Pasternack, Gregory B.; Gilbert, Andrew T.; Wheaton, Joseph M.; Buckland, Evan M.

    2006-08-01

    SummaryResource managers, scientists, government regulators, and stakeholders are considering sophisticated numerical models for managing complex environmental problems. In this study, observations from a river-rehabilitation experiment involving gravel augmentation and spawning habitat enhancement were used to assess sources and magnitudes of error in depth, velocity, and shear velocity predictions made at the 1-m scale with a commercial two-dimensional (depth-averaged) model. Error in 2D model depth prediction averaged 21%. This error was attributable to topographic survey resolution, which at 1 pt per 1.14 m 2, was inadequate to resolve small humps and depressions influencing point measurements. Error in 2D model velocity prediction averaged 29%. More than half of this error was attributable to depth prediction error. Despite depth and velocity error, 56% of tested 2D model predictions of shear velocity were within the 95% confidence limit of the best field-based estimation method. Ninety percent of the error in shear velocity prediction was explained by velocity prediction error. Multiple field-based estimates of shear velocity differed by up to 160%, so the lower error for the 2D model's predictions suggests such models are at least as accurate as field measurement. 2D models enable detailed, spatially distributed estimates compared to the small number measurable in a field campaign of comparable cost. They also can be used for design evaluation. Although such numerical models are limited to channel types adhering to model assumptions and yield predictions only accurate to ˜20-30%, they can provide a useful tool for river-rehabilitation design and assessment, including spatially diverse habitat heterogeneity as well as for pre- and post-project appraisal.

  19. Velocity dispersion and attenuation in granular marine sediments: comparison of measurements with predictions using acoustic models.

    PubMed

    Kimura, Masao

    2011-06-01

    The large velocity dispersion recently reported could be explained by a gap stiffness model incorporated into the Biot model (the BIMGS model) proposed by the author. However, at high frequencies, some measured results have been reported for negative velocity dispersion and attenuation proportional to the first to fourth power of frequency. In this study, first, it is shown that the results of velocity dispersion and attenuation calculated using the BIMGS model are consistent with the results measured in two kinds of water-saturated sands with different grain sizes, except in the high-frequency range. Then, the velocity dispersion and attenuation in six kinds of water-saturated glass beads and four kinds of water-saturated silica sands with different grain sizes are measured in the frequency ranges of 80-140 and 300-700 kHz. The measured results are compared with those calculated using the BIMGS model plus some acoustic models. It is shown that the velocity dispersion and attenuation are well predicted by using the BIMGS model in the range of kd ≤ 0.5 (k: wavenumber in water, d: grain diameter) and by using the BIMGS model plus multiple scattering effects in the range of kd ≥ 0.5 in which negative velocity dispersion appears. PMID:21682381

  20. Decent wage is more important than absolution of debts: A smallholder socio-hydrological modelling framework

    NASA Astrophysics Data System (ADS)

    Pande, Saket; Savenije, Hubert

    2015-04-01

    We present a framework to understand the socio-hydrological system dynamics of a small holder. Small holders are farmers who own less than 2 ha of farmland. It couples the dynamics of 6 main variables that are most relevant at the scale of a small holder: local storage (soil moisture and other water storage), capital, knowledge, livestock production, soil fertility and grass biomass production. The hydroclimatic variability is at sub-annual scale and influences the socio-hydrology at annual scale. The model incorporates rule-based adaptation mechanisms (for example: adjusting expenditures on food and fertilizers, selling livestocks etc.) of small holders when they face adverse socio-hydrological conditions, such as low annual rainfall, higher intra-annual variability in rainfall or variability in agricultural prices. We apply the framework to understand the socio-hydrology of a sugarcane small holder in Aurangabad, Maharashtra. This district has witnessed suicides of many sugarcane farmers who could not extricate themselves out of the debt trap. These farmers lack irrigation and are susceptible to fluctuating sugar prices and intra-annual hydro-climatic variability. We study the sensitivity of annual total capital averaged over 30 years, an indicator of small holder wellbeing, to initial capital that a small holder starts with and the prevalent wage rates. We find that a smallholder well being is low (below Rs 30000 per annum, a threshold above which a smallholder can afford a basic standard of living) and is rather insensitive to initial capital at low wage rates. Initial capital perhaps matters to small holder livelihoods at higher wage rates. Further, the small holder system appears to be resilient at around Rs 115/mandays in the sense that small perturbations in wage rates around this rate still sustains the smallholder above the basic standard of living. Our results thus indicate that government intervention to absolve the debt of farmers is not enough. It

  1. Velocity model construction, uncertainty evaluation, and two-way travel time to sediment thickness conversion

    NASA Astrophysics Data System (ADS)

    Li, Q.; Shimeld, J.; Dickie, K.; Dehler, S. A.; Desroches, K.

    2013-12-01

    Sediment thickness determinations play a key role in positioning the most seaward fixed points of the outer limits of continental shelves for coastal states. Seismic reflection surveying is an invaluable technique for estimating the sediment thickness required for the positioning. However, such seismic reflection surveying records the two way travel time (twtt) of vertically incident seismic waves. An accurate seismic velocity model is required for the conversion between twtt and sediment thickness. In this approach, a velocity model is constructed, its uncertainty is evaluated, and twtt is converted to sediment thickness. All of these procedures are programmed for batch and script processing. First, a slowness (the inverse of velocity) function, which is based on the solid sediment compaction theory, is selected and it is fitted using all available velocity observations using the reduced major axis (RMA) method, which can minimize errors from both velocity and depth observations. Second, the velocity uncertainty is estimated using a bootstrapping method by simulating a non-replace re-sampling procedure; thus it is also used in the estimation of sediment thickness uncertainty that is caused by velocity model errors. Moreover, with the constructed velocity model, conversion from sediment depth to twtt is resolved analytically and the conversion from twtt to depth is completed by solving a nonlinear equation with Newton iteration method, having approved convergence efficiency and a predefined accuracy (0.1 m). Finally, all these processes have been implemented in C# and JavaScript for integration with GeoFrame file format (seismic horizon interpretation) or embedded in any document with power batch processing and flexible verification facilities. As an example, publicly available velocity observations in the Labrador Sea region are used in the construction of a velocity model and the evaluation of velocity and sediment thickness uncertainty. The conversion between

  2. Quantifying Uncertainty in Velocity Models using Bayesian Methods

    NASA Astrophysics Data System (ADS)

    Hobbs, R.; Caiado, C.; Majdański, M.

    2008-12-01

    Quanitifying uncertainty in models derived from observed data is a major issue. Public and political understanding of uncertainty is poor and for industry inadequate assessment of risk costs money. In this talk we will examine the geological structure of the subsurface, however our principal exploration tool, controlled source seismology, gives its data in time. Inversion tools exist to map these data into a depth model but a full exploration of the uncertainty of the model is rarely done because robust strategies do not exist for large non-linear complex systems. There are two principal sources of uncertainty: the first comes from the input data which is noisy and bandlimited; the second, and more sinister, is from the model parameterisation and forward algorithms themselves, which approximate to the physics to make the problem tractable. To address these issues we propose a Bayesian approach. One philosophy is to estimate the uncertainty in a possible model derived using standard inversion tools. During the inversion stage we can use our geological prejudice to derive an acceptable model. Then we use a local random walk using the Metropolis- Hastings algorithm to explore the model space immediately around a possible solution. For models with a limited number of parameters we can use the forward modeling step from the inversion code. However as the number of parameters increase and/or the cost of the forward modeling step becomes significant, we need to use fast emulators to act as proxies so a sufficient number of iterations can be performed on which to base our statistical measures of uncertainty. In this presentation we show examples of uncertainty estimation using both pre- and post-critical seismic data. In particular, we will demonstrate uncertainty introduced by the approximation of the physics by using a tomographic inversion of bandlimited data and show that uncertainty increases as the central frequency of the data decreases. This is consistent with the

  3. UCVM: Open Source Software for Understanding and Delivering 3D Velocity Models

    NASA Astrophysics Data System (ADS)

    Gill, D.; Small, P.; Maechling, P. J.; Jordan, T. H.; Shaw, J. H.; Plesch, A.; Chen, P.; Lee, E. J.; Taborda, R.; Olsen, K. B.; Callaghan, S.

    2014-12-01

    Physics-based ground motion simulations can calculate the propagation of earthquake waves through 3D velocity models of the Earth. The Southern California Earthquake Center (SCEC) has developed the Unified Community Velocity Model (UCVM) framework to help researchers build structured or unstructured velocity meshes from 3D velocity models for use in wave propagation simulations. The UCVM software framework makes it easy to extract P and S wave propagation speeds and other material properties from 3D velocity models by providing a common interface through which researchers can query earth models for a given location and depth. Currently, the platform supports multiple California models, including SCEC CVM-S4 and CVM-H 11.9.1, and has been designed to support models from any region on earth. UCVM is currently being use to generate velocity meshes for many SCEC wave propagation codes, including AWP-ODC-SGT and Hercules. In this presentation, we describe improvements to the UCVM software. The current version, UCVM 14.3.0, released in March of 2014, supports the newest Southern California velocity model, CVM-S4.26, which was derived from 26 full-3D tomographic iterations using CVM-S4 as the starting model (Lee et al., this meeting), and the Broadband 1D velocity model used in the CyberShake 14.2 study. We have ported UCVM to multiple Linux distributions and OS X. Also included in this release is the ability to add small-scale stochastic heterogeneities to extract Cartesian meshes for use in high-frequency ground motion simulations. This tool was built using the C language open-source FFT library, FFTW. The stochastic parameters (Hurst exponent, correlation length, and the horizontal/vertical aspect ratio) can be customized by the user. UCVM v14.3.0 also provides visualization scripts for constructing cross-sections, horizontal slices, basin depths, and Vs30 maps. The interface allows researchers to visually review velocity models . Also, UCVM v14.3.0 can extract

  4. Comparing Absolute Error with Squared Error for Evaluating Empirical Models of Continuous Variables: Compositions, Implications, and Consequences

    NASA Astrophysics Data System (ADS)

    Gao, J.

    2014-12-01

    Reducing modeling error is often a major concern of empirical geophysical models. However, modeling errors can be defined in different ways: When the response variable is continuous, the most commonly used metrics are squared (SQ) and absolute (ABS) errors. For most applications, ABS error is the more natural, but SQ error is mathematically more tractable, so is often used as a substitute with little scientific justification. Existing literature has not thoroughly investigated the implications of using SQ error in place of ABS error, especially not geospatially. This study compares the two metrics through the lens of bias-variance decomposition (BVD). BVD breaks down the expected modeling error of each model evaluation point into bias (systematic error), variance (model sensitivity), and noise (observation instability). It offers a way to probe the composition of various error metrics. I analytically derived the BVD of ABS error and compared it with the well-known SQ error BVD, and found that not only the two metrics measure the characteristics of the probability distributions of modeling errors differently, but also the effects of these characteristics on the overall expected error are different. Most notably, under SQ error all bias, variance, and noise increase expected error, while under ABS error certain parts of the error components reduce expected error. Since manipulating these subtractive terms is a legitimate way to reduce expected modeling error, SQ error can never capture the complete story embedded in ABS error. I then empirically compared the two metrics with a supervised remote sensing model for mapping surface imperviousness. Pair-wise spatially-explicit comparison for each error component showed that SQ error overstates all error components in comparison to ABS error, especially variance-related terms. Hence, substituting ABS error with SQ error makes model performance appear worse than it actually is, and the analyst would more likely accept a

  5. Estimating V̄s(30) (or NEHRP site classes) from shallow velocity models (depths < 30 m)

    USGS Publications Warehouse

    Boore, David M.

    2004-01-01

    The average velocity to 30 m [V??s(30)] is a widely used parameter for classifying sites to predict their potential to amplify seismic shaking. In many cases, however, models of shallow shear-wave velocities, from which V??s(30) can be computed, do not extend to 30 m. If the data for these cases are to be used, some method of extrapolating the velocities must be devised. Four methods for doing this are described here and are illustrated using data from 135 boreholes in California for which the velocity model extends to at least 30 m. Methods using correlations between shallow velocity and V??s(30) result in significantly less bias for shallow models than the simplest method of assuming that the lowermost velocity extends to 30 m. In addition, for all methods the percent of sites misclassified is generally less than 10% and falls to negligible values for velocity models extending to at least 25 m. Although the methods using correlations do a better job on average of estimating V??s(30), the simplest method will generally result in a lower value of V??s(30) and thus yield a more conservative estimate of ground motion [which generally increases as V??s(30) decreases].

  6. Current plate velocities relative to the hotspots incorporating the NUVEL-1 global plate motion model

    SciTech Connect

    Gripp, A.E.; Gordon, R.G. )

    1990-07-01

    NUVEL-1 is a new global model of current relative plate velocities which differ significantly from those of prior models. Here the authors incorporate NUVEL-1 into HS2-NUVEL1, a new global model of plate velocities relative to the hotspots. HS2-NUVEL1 was determined from the hotspot data and errors used by Minster and Jordan (1978) to determine AM1-2, which is their model of plate velocities relative to the hotspots. AM1-2 is consistent with Minster and Jordan's relative plate velocity model RM2. Here the authors compare HS2-NUVEL1 with AM1-2 and examine how their differences relate to differences between NUVEL-1 and RM2. HS2-NUVEL1 plate velocities relative to the hotspots are mainly similar to those of AM1-2. Minor differences between the two models include the following: (1) in HS2-NUVEL1 the speed of the partly continental, apparently non-subducting Indian plate is greater than that of the purely oceanic, subducting Nazca plate; (2) in places the direction of motion of the African, Antarctic, Arabian, Australian, Caribbean, Cocos, Eurasian, North American, and South American plates differs between models by more than 10{degree}; (3) in places the speed of the Australian, Caribbean, Cocos, Indian, and Nazca plates differs between models by more than 8 mm/yr. Although 27 of the 30 RM2 Euler vectors differ with 95% confidence from those of NUVEL-1, only the AM1-2 Arabia-hotspot and India-hotspot Euler vectors differ with 95% confidence from those of HS2-NUVEL1. Thus, substituting NUVEL-1 for RM2 in the inversion for plate velocities relative to the hotspots changes few Euler vectors significantly, presumably because the uncertainty in the velocity of a plate relative to the hotspots is much greater than the uncertainty in its velocity relative to other plates.

  7. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  8. Meteor velocity distribution and an optimum monitoring mathematical model

    NASA Technical Reports Server (NTRS)

    Volkov, N. G.; Salimov, O. N.

    1987-01-01

    At present, there are a great number of radio meteor, ionosphere and rocket observation data for the altitude range of 80 to 100 km which indicate the existence of large scale circulation systems in the mesopause to low thermosphere range which change regularly with season and latitude. But the existing observation network and observation programs are not optimal for revealing the main factors forming the circulation mode at these altitudes. A generalized optimum monitoring mathematical model is offered for consideration. The model input data are distribution density, response function, individual measurement root mean square uncertainty and detection effectiveness function. The model makes it possible to obtain the observation distribution density, the minimal possible dispersion and optimized system effectiveness.

  9. Modeling coiled-tubing velocity strings for gas wells

    SciTech Connect

    Martinez, J.; Martinez, A.

    1998-02-01

    Because of its ability to prolong well life, its relatively low expense, and the relative ease with which it is installed, coiled tubing has become a preferred remedial method of tubular completion for gas wells. Of course, the difficulty in procuring wireline-test data is a drawback to verifying the accuracy of the assumptions and predictions used for coiled-tubing selection. This increases the importance of the prediction-making process, and, as a result, places great emphasis on the modeling methods that are used. This paper focuses on the processes and methods for achieving sound multiphase-flow predictions by looking at the steps necessary to arrive at coiled-tubing selection. Furthermore, this paper examines the variables that serve as indicators of the viability of each tubing size, especially liquid holdup. This means that in addition to methodology, emphasis is placed on the use of a good wellbore model. The computer model discussed is in use industry wide.

  10. Revisiting the capture velocity of a cesium magneto-optical trap: model, simulation and experiment

    NASA Astrophysics Data System (ADS)

    Anwar, Muhammad; Magalhães, Daniel V.; Müller, Stella T.; Faisal, Muhammad; Nawaz, Muhammad; Ahmed, Mushtaq

    2014-12-01

    In this work, we have explored ab initio the capture process in a magneto-optical trap by theory, simulation and experiment. We measured the capture velocity vc of a cesium vapor cell magneto-optical trap (VCMOT) from its capture rate R and developed an exact model for the capture rate of a VCMOT in terms of its capture velocity, background density and trap laser beam diameter. We measured the capture velocity of a cesium VCMOT for various trap laser intensities and magnetic field gradients. We observed that the capture velocity is a damping force as well as a restoring force phenomenon. We supported our findings by performing simulations for single atom trajectories in a 1D cesium MOT. Finally, we concluded that two MOTs can have the same capture velocities but very different capture rates, thereby revealing that these are two fundamentally different characteristics of the MOT.

  11. A comprehensive dispersion model of surface wave phase and group velocity for the globe

    NASA Astrophysics Data System (ADS)

    Ma, Zhitu; Masters, Guy; Laske, Gabi; Pasyanos, Michael

    2014-10-01

    A new method is developed to measure Rayleigh- and Love-wave phase velocities globally using a cluster analysis technique. This method clusters similar waveforms recorded at different stations from a single event and allows users to make measurements on hundreds of waveforms, which are filtered at a series of frequency ranges, at the same time. It also requires minimal amount of user interaction and allows easy assessment of the data quality. This method produces a large amount of phase delay measurements in a manageable time frame. Because there is a strong trade-off between the isotropic part of the Rayleigh-wave phase velocity and azimuthal anisotropy, we include the effect of azimuthal anisotropy in our inversions in order to obtain reliable isotropic phase velocity. We use b-splines to combine these isotropic phase velocity maps with our previous group velocity maps to produce an internally consistent global surface wave dispersion model.

  12. Measurements and a model for convective velocities in the turbulent boundary layer

    NASA Technical Reports Server (NTRS)

    Cliff, W. C.; Sandborn, V. A.

    1973-01-01

    A physical model is presented which describes convective velocities within a flat plate turbulent boundary layer. A production zone concept is used as a basis for the physical model. The production zone concept employs the idea that packets of turbulent fluid are generated near the viscous sublayer. These packets are found to be discernible from the mean motion and may move either outward from the production zone or inward depending on their circulation relative to the fluid surrounding the packet. The packets are predicted to travel with a convective velocity different from the local mean velocity throughout most of the boundary layer. The model also predicts that the convective velocities will be functions of wave number outside the production zone.

  13. Modeling non-Fickian dispersion by use of the velocity PDF on the pore scale

    NASA Astrophysics Data System (ADS)

    Kooshapur, Sheema; Manhart, Michael

    2015-04-01

    For obtaining a description of reactive flows in porous media, apart from the geometrical complications of resolving the velocities and scalar values, one has to deal with the additional reactive term in the transport equation. An accurate description of the interface of the reacting fluids - which is strongly influenced by dispersion- is essential for resolving this term. In REV-based simulations the reactive term needs to be modeled taking sub-REV fluctuations and possibly non-Fickian dispersion into account. Non-Fickian dispersion has been observed in strongly heterogeneous domains and in early phases of transport. A fully resolved solution of the Navier-Stokes and transport equations which yields a detailed description of the flow properties, dispersion, interfaces of fluids, etc. however, is not practical for domains containing more than a few thousand grains, due to the huge computational effort required. Through Probability Density Function (PDF) based methods, the velocity distribution in the pore space can facilitate the understanding and modelling of non-Fickian dispersion [1,2]. Our aim is to model the transition between non-Fickian and Fickian dispersion in a random sphere pack within the framework of a PDF based transport model proposed by Meyer and Tchelepi [1,3]. They proposed a stochastic transport model where velocity components of tracer particles are represented by a continuous Markovian stochastic process. In addition to [3], we consider the effects of pore scale diffusion and formulate a different stochastic equation for the increments in velocity space from first principles. To assess the terms in this equation, we performed Direct Numerical Simulations (DNS) for solving the Navier-Stokes equation on a random sphere pack. We extracted the PDFs and statistical moments (up to the 4th moment) of the stream-wise velocity, u, and first and second order velocity derivatives both independent and conditioned on velocity. By using this data and

  14. A support vector regression-firefly algorithm-based model for limiting velocity prediction in sewer pipes.

    PubMed

    Ebtehaj, Isa; Bonakdari, Hossein

    2016-01-01

    Sediment transport without deposition is an essential consideration in the optimum design of sewer pipes. In this study, a novel method based on a combination of support vector regression (SVR) and the firefly algorithm (FFA) is proposed to predict the minimum velocity required to avoid sediment settling in pipe channels, which is expressed as the densimetric Froude number (Fr). The efficiency of support vector machine (SVM) models depends on the suitable selection of SVM parameters. In this particular study, FFA is used by determining these SVM parameters. The actual effective parameters on Fr calculation are generally identified by employing dimensional analysis. The different dimensionless variables along with the models are introduced. The best performance is attributed to the model that employs the sediment volumetric concentration (C(V)), ratio of relative median diameter of particles to hydraulic radius (d/R), dimensionless particle number (D(gr)) and overall sediment friction factor (λ(s)) parameters to estimate Fr. The performance of the SVR-FFA model is compared with genetic programming, artificial neural network and existing regression-based equations. The results indicate the superior performance of SVR-FFA (mean absolute percentage error = 2.123%; root mean square error =0.116) compared with other methods. PMID:27148727

  15. Shallow Seismic Velocity Structure of the Betic Cordillera (Southern Spain) from Modelling of Rayleigh Wave Dispersion

    NASA Astrophysics Data System (ADS)

    Chourak, M.; Corchete, V.; Badal, J.; Gómez, F.; Serón, J.

    2005-07-01

    A detailed dispersion analysis of Rayleigh waves generated by local earthquakes and occasionally by blasts that occurred in southern Spain, was undertaken to obtain the shear-wave velocity structure of the region at shallow depth. Our database includes seismograms generated by 35 seismic events that were recorded by 15 single-component short-period stations from 1990 to 1995. All these events have focal depths less than 10 km and body-wave magnitudes between 3.0 and 4.0, and they were all recorded at distances between 40 and 300 km from the epicentre. We analysed a total of 90 source-station Rayleigh-wave paths. The collected data were processed by standard digital filtering techniques to obtain Rayleigh-wave group-velocity dispersion measurements. The path-averaged group velocities vary from 1.12 to 2.25 km/s within the 1.0-6.0 s period interval. Then, using a stochastic inversion approach we obtained 1-D shear-wave velocity depth models across the study area, which were resolved to a depth of circa 5 km. The inverted shear-wave velocities range approximately between 1.0 and 3.8 km/s with a standard deviation range of 0.05 0.16 km/s, and show significant variations from region to region. These results were combined to produce 3-D images via volumetric modelling and data visualization. We present images that show different shear velocity patterns for the Betic Cordillera. Looking at the velocity distribution at various depths and at vertical sections, we discuss of the study area in terms of subsurface structure and S-wave velocity distribution (low velocity channels, basement depth, etc.) at very shallow depths (0 5 km). Our results characterize the region sufficiently and lead to a correlation of shear-wave velocity with the different geological units features.

  16. Delayed detonation models for normal and subluminous type Ia sueprnovae: Absolute brightness, light curves, and molecule formation

    NASA Technical Reports Server (NTRS)

    Hoflich, P.; Khokhlov, A. M.; Wheeler, J. C.

    1995-01-01

    We compute optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SN Ia's) using an elaborate treatment of the Local Thermodynamic Equilbrium (LTE) radiation transport, equation of state and ionization balance, expansion opacity including the cooling by CO, Co(+), and SiO, and a Monte Carlo gamma-ray deposition scheme. The models have an amount of Ni-56 in the range from approximately or equal to 0.1 solar mass up to 0.7 solar mass depending on the density at which the transition from a deflagration to a detonation occurs. Models with a large nickel production give light curves comparable to those of typical Type Ia supernovae. Subluminous supernovae can be explained by models with a low nickel production. Multiband light curves are presented in comparison with the normally bright event SN 1992bc and the subluminous events Sn 1991bg and SN 1992bo to establish the principle that the delayed detonation paradigm in Chandrasekhar mass models may give a common explosion mechanism accounting for both normal and subluminous SN Ia's. Secondary IR-maxima are formed in the models of normal SN Ia's as a photospheric effect if the photospheric radius continues to increase well after maximum light. Secondary maxima appear later and stronger in models with moderate expansion velocities and with radioactive material closer to the surface. Model light curves for subluminous SN Ia's tend to show only one 'late' IR-maximum. In some delayed detonation models shell-like envelopes form, which consist of unburned carbon and oxygen. The formation of molecules in these envelopes is addressed. If the model retains a C/O-envelope and is subluminous, strong vibration bands of CO may appear, typically several weeks past maximum light. CO should be very weak or absent in normal Sn Ia's.

  17. The reaction H + C4H2 - Absolute rate constant measurement and implication for atmospheric modeling of Titan

    NASA Astrophysics Data System (ADS)

    Nava, D. F.; Mitchell, M. B.; Stief, L. J.

    1986-04-01

    The absolute rate constant for the reaction H + C4H2 has been measured over the temperature (T) interval 210-423 K, using the technique of flash photolysis-resonance fluorescence. At each of the five temperatures employed, the results were independent of variations in C4H2 concentration, total pressure of Ar or N2, and flash intensity (i.e., the initial H concentration). The rate constant, k, was found to be equal to 1.39 x 10 to the -10th exp (-1184/T) cu cm/s, with an error of one standard deviation. The Arrhenius parameters at the high pressure limit determined here for the H + C4H2 reaction are consistent with those for the corresponding reactions of H with C2H2 and C3H4. Implications of the kinetic carbon chemistry results, particularly those at low temperature, are considered for models of the atmospheric carbon chemistry of Titan. The rate of this reaction, relative to that of the analogous, but slower, reaction of H + C2H2, appears to make H + C4H2 a very feasible reaction pathway for effective conversion of H atoms to molecular hydrogen in the stratosphere of Titan.

  18. Constraining the Absolute Orientation of eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission

    NASA Technical Reports Server (NTRS)

    Madura, T. I.; Gull, T. R.; Owocki, S. P.; Groh, J. H.; Okazaki, A. T.; Russell, C. M. P.

    2011-01-01

    We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA(theta) that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38deg, and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i approx. = 130deg to 145deg, Theta approx. = -15deg to +30deg, and an orbital axis projected on the sky at a P A approx. = 302deg to 327deg east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3-D. The companion star, Eta(sub B), thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modeling to determine the stellar masses.

  19. ABSOLUTE DIMENSIONS OF THE G7+K7 ECLIPSING BINARY STAR IM VIRGINIS: DISCREPANCIES WITH STELLAR EVOLUTION MODELS

    SciTech Connect

    Morales, Juan Carlos; Marschall, Laurence A.; Brehm, William

    2009-12-10

    We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations, we derive accurate absolute masses and radii of M {sub 1} = 0.981 +- 0.012 M {sub sun}, M {sub 2} = 0.6644 +- 0.0048 M {sub sun}, R {sub 1} = 1.061 +- 0.016 R {sub sun}, and R {sub 2} = 0.681 +- 0.013 R {sub sun} for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 +- 100 K and 4250 +- 130 K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100 K and 150 K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4 Gyr for the system, and a metallicity of [Fe/H] approx-0.3 that is consistent with other indications, but requires confirmation.

  20. Detailed p- and s-wave velocity models along the LARSE II transect, Southern California

    USGS Publications Warehouse

    Murphy, J.M.; Fuis, G.S.; Ryberg, T.; Lutter, W.J.; Catchings, R.D.; Goldman, M.R.

    2010-01-01

    Structural details of the crust determined from P-wave velocity models can be improved with S-wave velocity models, and S-wave velocities are needed for model-based predictions of strong ground motion in southern California. We picked P- and S-wave travel times for refracted phases from explosive-source shots of the Los Angeles Region Seismic Experiment, Phase II (LARSE II); we developed refraction velocity models from these picks using two different inversion algorithms. For each inversion technique, we calculated ratios of P- to S-wave velocities (VP/VS) where there is coincident P- and S-wave ray coverage.We compare the two VP inverse velocity models to each other and to results from forward modeling, and we compare the VS inverse models. The VS and VP/VS models differ in structural details from the VP models. In particular, dipping, tabular zones of low VS, or high VP/VS, appear to define two fault zones in the central Transverse Ranges that could be parts of a positive flower structure to the San Andreas fault. These two zones are marginally resolved, but their presence in two independent models lends them some credibility. A plot of VS versus VP differs from recently published plots that are based on direct laboratory or down-hole sonic measurements. The difference in plots is most prominent in the range of VP = 3 to 5 km=s (or VS ~ 1:25 to 2:9 km/s), where our refraction VS is lower by a few tenths of a kilometer per second from VS based on direct measurements. Our new VS - VP curve may be useful for modeling the lower limit of VS from a VP model in calculating strong motions from scenario earthquakes.

  1. Architecture-based force-velocity models of load-moving skeletal muscles.

    PubMed

    Baratta, R V; Solomonow, M; Best, R; Zembo, M; D'Ambrosia, R

    1995-04-01

    A predictive model of muscle force-velocity relationships is presented based on functional architectural variables. The parameters of Hill's equation describing muscle force-velocity relationship of nine muscles were estimated by their relationships with variables extracted from the whole-muscle length-force relationship and the percentage of slow-twitch fibres. Specifically, the maximal unloaded velocity (Vo) was estimated through multiple linear regression, from each muscle's fibre composition and the shortening range through which each muscle could produce active force. The maximal isometric force (Po) was also extracted from each muscle's length-force relationship. The ratio of Hill's dynamic constanta to Po and b to Vo, which determines the degree of curvature of the relation, was determined solely by the percent of slow-twitch fibres. This model was verified by fitting it to experimental force-velocity curves of nine different muscles in the cat's hindlimb. It was found that reasonable fits of force-velocity curves would be obtained with correlation coefficient in the range of 0.61 to 0.92, with an average of 0.82. The model predicted that muscles with relatively long shortening ranges would achieve higher maximal velocity, and that muscles with higher percentage of slow-twitch fibres had less pronounced curvature and lower maximal velocity in their force-velocity relationships. RELEVANCE: The results have direct implications in the design of neuroprosthetic limb control systems, which use electrical stimulation to restore function to muscles paralysed from spinal cord injury. The designer is enabled to optimally calibrate the controller according to the predicted individual force-velocity curves of different muscles by using the length-tension curves and fibre composition data available in the literature. PMID:11415546

  2. Constraining fault interpretation through tomographic velocity gradients: application to northern Cascadia

    NASA Astrophysics Data System (ADS)

    Ramachandran, K.

    2012-02-01

    Spatial gradients of tomographic velocities are seldom used in interpretation of subsurface fault structures. This study shows that spatial velocity gradients can be used effectively in identifying subsurface discontinuities in the horizontal and vertical directions. Three-dimensional velocity models constructed through tomographic inversion of active source and/or earthquake traveltime data are generally built from an initial 1-D velocity model that varies only with depth. Regularized tomographic inversion algorithms impose constraints on the roughness of the model that help to stabilize the inversion process. Final velocity models obtained from regularized tomographic inversions have smooth three-dimensional structures that are required by the data. Final velocity models are usually analyzed and interpreted either as a perturbation velocity model or as an absolute velocity model. Compared to perturbation velocity model, absolute velocity models have an advantage of providing constraints on lithology. Both velocity models lack the ability to provide sharp constraints on subsurface faults. An interpretational approach utilizing spatial velocity gradients applied to northern Cascadia shows that subsurface faults that are not clearly interpretable from velocity model plots can be identified by sharp contrasts in velocity gradient plots. This interpretation resulted in inferring the locations of the Tacoma, Seattle, Southern Whidbey Island, and Darrington Devil's Mountain faults much more clearly. The Coast Range Boundary fault, previously hypothesized on the basis of sedimentological and tectonic observations, is inferred clearly from the gradient plots. Many of the fault locations imaged from gradient data correlate with earthquake hypocenters, indicating their seismogenic nature.

  3. Constraining fault interpretation through tomographic velocity gradients: application to Northern Cascadia

    NASA Astrophysics Data System (ADS)

    Ramachandran, K.

    2011-09-01

    Spatial gradients of tomographic velocities are seldom used in interpretation of subsurface fault structures. This study shows that spatial velocity gradients can be used effectively in identifying subsurface discontinuities in the horizontal and vertical directions. Three-dimensional velocity models constructed through tomographic inversion of active source and/or earthquake traveltime data are generally built from an initial 1-D velocity model that varies only with depth. Regularized tomographic inversion algorithms impose constraints on the roughness of the model that help to stabilize the inversion process. Final velocity models obtained from regularized tomographic inversions have smooth three-dimensional structures that are required by the data. Final velocity models are usually analyzed and interpreted either as a perturbation velocity model or as an absolute velocity model. Compared to perturbation velocity model, absolute velocity model has an advantage of providing constraints on lithology. Both velocity models lack the ability to provide sharp constraints on subsurface faults. An interpretational approach utilizing spatial velocity gradients applied to northern Cascadia shows that subsurface faults that are not clearly interpretable from velocity model plots can be identified by sharp contrasts in velocity gradient plots. This interpretation resulted in inferring the locations of Tacoma Fault, Seattle Fault, Southern Whidbey Island Fault, and Darrington Devils Mountain fault much clearly. The Coast Range Boundary Fault, previously hypothesized on the basis of sedimentological and tectonic observations, is inferred clearly from the gradient plots. Many of the fault locations imaged from gradient data correlate with earthquake hypocenters indicating their seismogenic nature.

  4. Three Dimensional P Wave Velocity Model for the Crust Containing Aftershocks of the Bhuj, India Earthquake

    NASA Astrophysics Data System (ADS)

    Powell, C. A.; Vlahovic, G.; Bodin, P.; Horton, S.

    2001-12-01

    A three-dimensional P wave velocity model has been constructed for the crust in the vicinity of the Mw=7.7 January 26th Bhuj, India earthquake using aftershock data obtained by CERI away teams. Aftershocks were recorded by 8 portable, digital K2 seismographs (the MAEC/ISTAR network) and by a continuously recording Guralp CMG40TD broad-band seismometer. Station spacing is roughly 30 km. The network was in place for 18 days and recorded ground motions from about 2000 aftershocks located within about 100 km of all stations. The 3-D velocity model is based upon an initial subset of 461 earthquakes with 2848 P wave arrivals. The initial 1-D velocity model was determined using VELEST and the 3-D model was determined using the nonlinear travel time tomography method of Benz et al. [1996]. Block size was set at 2 by 2 by 2 km. A 45% reduction in RMS travel time residuals was obtained after 10 iterations holding hypocenters fixed. We imaged velocity anomalies in the range -2 to 4%. Low velocities were found in the upper 6 km and the anomalies follow surface features such as the Rann of Kutch. High velocity features were imaged at depth and are associated with the aftershock hypocenters. High crustal velocities are present at depths exceeding 20 km with the exception of the crust below the Rann of Kutch. The imaged velocity anomaly pattern does not change when different starting models are used and when hypocenters are relocated using P wave arrivals only. The analysis will be extended to an expanded data set of 941 aftershocks.

  5. An improved car-following model considering velocity fluctuation of the immediately ahead car

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Huang, Mengxing; Ren, Jia; Shi, Zhongke

    2016-05-01

    To better describe car-following behaviors in the adaptive cruise control strategy and further increase roadway traffic mobility and reduce fuel consumptions, the linkage between velocity fluctuation of the immediately ahead car and the following car's acceleration or deceleration is explored with respect to the measured car-following data by employing the gray correlation analysis theory and then an improved car-following model considering velocity fluctuation of the immediately ahead car on basis of the full velocity difference model is proposed. Numerical simulations are carried out and the effects of velocity fluctuation of the immediately ahead car on each car's velocity, acceleration, vehicular gap, fuel consumptions and the total fuel consumptions of the whole car-following system with different time window lengths are investigated in detail. The results show that velocity fluctuation of the immediately ahead car has significant effects on car-following behaviors and fuel consumptions, and that considering velocity fluctuation of the immediately ahead car in designing the adaptive cruise control system can improve traffic flow stability and reduce fuel consumptions.

  6. Velocity field measurements in oblique static divergent vocal fold models

    NASA Astrophysics Data System (ADS)

    Erath, Byron

    2005-11-01

    During normal phonation, the vocal fold cycle is characterized by the glottal opening transitioning from a convergent to a divergent passage and then closing before the cycle is repeated. Under ordinary phonatory conditions, both vocal folds, which form the glottal passage, move in phase with each other, creating a time-varying symmetric opening. However, abnormal pathological conditions, such as unilateral paralysis, and polyps, can result in geometrical asymmetries between the vocal folds throughout the phonatory cycle. This study investigates pulsatile flow fields through 7.5 times life-size vocal fold models with included divergence angles of 5 to 30 degrees, and obliquities between the vocal folds of up to 15 degrees. Flow conditions were scaled to match physiological parameters. Data were taken at the anterior posterior mid-plane using phase-averaged Particle Image Velocimetry (PIV). Viscous flow phenomena including the Coanda effect, flow separation points, and jet "flapping" were investigated. The results are compared to previously reported work of flow through symmetric divergent vocal fold models.

  7. Absolute and Convective Instability in Fluid-Conveying Flexible Pipes

    NASA Astrophysics Data System (ADS)

    de Langre, E.; Ouvrard, A. E.

    1998-11-01

    The effect of internal plug flow on the lateral stability of fluid conveying flexible pipes is investigated by determining the absolute/convective nature of the instability from the analytically derived linear dispersion relation. The fluid-structure interaction is modeled following the work of Gregory and Paidoussis (1966). The different domains of stability, convective instability, and absolute instability are explicitly derived in parameter space. The effect of flow velocity, mass ratio between the fluid and the structure, stiffness of the elastic foundation and axial tension is considered. Absolute instability prevails over a wide range of parameters. Convective instability only takes place at very high mass ratio, small stiffness and small axial tension. Relation is made with previous work of Brazier-Smith & Scott (1984) and Crighton (1991), considered here as a short wave approximation.

  8. A model for the spatial integration and differentiation of velocity signals.

    PubMed

    Gurney, K N; Wright, M J

    1996-09-01

    We present a model of optic flow processing which is able to reconcile the integrative, cooperative phenomena of motion capture and coherence with the differentiation of velocity signals in motion segmentation and transparency. The model uses a Markov random field to compute the behaviour of coextensive topographic neural maps of retinotopy and velocity. We have used the model to simulate the psychophysics of motion coherence, motion capture and transparency. Further, it exhibits motion segmentation without extra postulates. The model is robust and able to display all types of motion percept with the same parameter set. PMID:8917795

  9. Measurement of velocity deficit at the downstream of a 1:10 axial hydrokinetic turbine model

    SciTech Connect

    Gunawan, Budi; Neary, Vincent S; Hill, Craig; Chamorro, Leonardo

    2012-01-01

    Wake recovery constrains the downstream spacing and density of turbines that can be deployed in turbine farms and limits the amount of energy that can be produced at a hydrokinetic energy site. This study investigates the wake recovery at the downstream of a 1:10 axial flow turbine model using a pulse-to-pulse coherent Acoustic Doppler Profiler (ADP). In addition, turbine inflow and outflow velocities were measured for calculating the thrust on the turbine. The result shows that the depth-averaged longitudinal velocity recovers to 97% of the inflow velocity at 35 turbine diameter (D) downstream of the turbine.

  10. Modeling the effect of varying swim speeds on fish passage through velocity barriers

    USGS Publications Warehouse

    Castro-Santos, T.

    2006-01-01

    The distance fish can swim through zones of high-velocity flow is an important factor limiting the distribution and conservation of riverine and diadromous fishes. Often, these barriers are characterized by nonuniform flow conditions, and it is likely that fish will swim at varying speeds to traverse them. Existing models used to predict passage success, however, typically include the unrealistic assumption that fish swim at a constant speed regardless of the speed of flow. This paper demonstrates how the maximum distance of ascent through velocity barriers can be estimated from the swim speed-fatigue time relationship, allowing for variation in both swim speed and water velocity.

  11. Direct Measurement of Internal Flow Velocities in a Star-Slot Model

    NASA Technical Reports Server (NTRS)

    Foster, Winfred A., Jr.; Jenkins, Rhonald M.; Hengel, John E.; Smith, Andrew W.

    1997-01-01

    This paper presents the results of a cold flow experiment to make direct measurements of the velocity distribution in a model of a solid rocket motor star grain propellant slot. The experimental procedure utilizes a multi-component laser Doppler velocimeter (LDV) and an apparatus for seeding the flow with aluminum particles to determine the velocity components at various discrete locations within the star slot. The test article used in this investigation was a one-tenth scale, cold flow model based on the geometry of the Space Shuttle solid rocket motor head-end section. The results obtained for the direct measurements of velocity are compared to velocities calculated from measured pressure distributions to data obtained from oil smear experiments and flow visualization videos, and to heat transfer calorimeter data.

  12. Lane-changing behavior and its effect on energy dissipation using full velocity difference model

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Ding, Jian-Xun; Shi, Qin; Kühne, Reinhart D.

    2016-07-01

    In real urban traffic, roadways are usually multilane with lane-specific velocity limits. Most previous researches are derived from single-lane car-following theory which in the past years has been extensively investigated and applied. In this paper, we extend the continuous single-lane car-following model (full velocity difference model) to simulate the three-lane-changing behavior on an urban roadway which consists of three lanes. To meet incentive and security requirements, a comprehensive lane-changing rule set is constructed, taking safety distance and velocity difference into consideration and setting lane-specific speed restriction for each lane. We also investigate the effect of lane-changing behavior on distribution of cars, velocity, headway, fundamental diagram of traffic and energy dissipation. Simulation results have demonstrated asymmetric lane-changing “attraction” on changeable lane-specific speed-limited roadway, which leads to dramatically increasing energy dissipation.

  13. Site-Specific Velocity and Density Model for the Waste Treatment Plant, Hanford, Washington.

    SciTech Connect

    Rohay, Alan C.; Brouns, Thomas M.

    2007-06-27

    This report documents the work conducted under the SBP to develop a shear wave and compressional wave velocity and density model specific to the WTP site. Section 2 provides detailed background information on the WTP site and its underlying geology as well as on the Seismic Boreholes Project activities leading up to the Vs and Vp measurements. In Section 3, methods employed and results obtained are documented for measurements of Vs and Vp velocities in basalts and interbeds. Section 4 provides details on velocity measurements in the sediments underlying the WTP. Borehole gravity measurements of density of the subsurface basalt and sediments are described in Section 5. Section 6 describes the analysis of data presented in section 3-5, and presents the overall velocity and density model for the WTP site.

  14. Computational Modeling of Seismic Wave Propagation Velocity-Saturation Effects in Porous Rocks

    NASA Astrophysics Data System (ADS)

    Deeks, J.; Lumley, D. E.

    2011-12-01

    Compressional and shear velocities of seismic waves propagating in porous rocks vary as a function of the fluid mixture and its distribution in pore space. Although it has been possible to place theoretical upper and lower bounds on the velocity variation with fluid saturation, predicting the actual velocity response of a given rock with fluid type and saturation remains an unsolved problem. In particular, we are interested in predicting the velocity-saturation response to various mixtures of fluids with pressure and temperature, as a function of the spatial distribution of the fluid mixture and the seismic wavelength. This effect is often termed "patchy saturation' in the rock physics community. The ability to accurately predict seismic velocities for various fluid mixtures and spatial distributions in the pore space of a rock is useful for fluid detection, hydrocarbon exploration and recovery, CO2 sequestration and monitoring of many subsurface fluid-flow processes. We create digital rock models with various fluid mixtures, saturations and spatial distributions. We use finite difference modeling to propagate elastic waves of varying frequency content through these digital rock and fluid models to simulate a given lab or field experiment. The resulting waveforms can be analyzed to determine seismic traveltimes, velocities, amplitudes, attenuation and other wave phenomena for variable rock models of fluid saturation and spatial fluid distribution, and variable wavefield spectral content. We show that we can reproduce most of the published effects of velocity-saturation variation, including validating the Voigt and Reuss theoretical bounds, as well as the Hill "patchy saturation" curve. We also reproduce what has been previously identified as Biot dispersion, but in fact in our models is often seen to be wave multi-pathing and broadband spectral effects. Furthermore, we find that in addition to the dominant seismic wavelength and average fluid patch size, the

  15. No-net-rotation model of current plate velocities incorporating plate motion model NUVEL-1

    NASA Technical Reports Server (NTRS)

    Argus, Donald F.; Gordon, Richard G.

    1991-01-01

    NNR-NUVEL1 is presented which is a model of plate velocities relative to the unique reference frame defined by requiring no-net-rotation of the lithosphere while constraining relative plate velocities to equal those in global plate motion model NUVEL-1 (DeMets et al., 1990). In NNR-NUVEL1, the Pacific plate rotates in a right-handed sense relative to the no-net-rotation reference frame at 0.67 deg/m.y. about 63 deg S, 107 deg E. At Hawaii the Pacific plate moves relative to the no-net-rotation reference frame at 70 mm/yr, which is 25 mm/yr slower than the Pacific plate moves relative to the hotspots. Differences between NNR-NUVEL1 and HS2-NUVEL1 are described. The no-net-rotation reference frame differs significantly from the hotspot reference frame. If the difference between reference frames is caused by motion of the hotspots relative to a mean-mantle reference frame, then hotspots beneath the Pacific plate move with coherent motion towards the east-southeast. Alternatively, the difference between reference frames can show that the uniform drag, no-net-torque reference frame, which is kinematically equivalent to the no-net-rotation reference frame, is based on a dynamically incorrect premise.

  16. A distributed, dynamic, parallel computational model: the role of noise in velocity storage

    PubMed Central

    Merfeld, Daniel M.

    2012-01-01

    Networks of neurons perform complex calculations using distributed, parallel computation, including dynamic “real-time” calculations required for motion control. The brain must combine sensory signals to estimate the motion of body parts using imperfect information from noisy neurons. Models and experiments suggest that the brain sometimes optimally minimizes the influence of noise, although it remains unclear when and precisely how neurons perform such optimal computations. To investigate, we created a model of velocity storage based on a relatively new technique–“particle filtering”–that is both distributed and parallel. It extends existing observer and Kalman filter models of vestibular processing by simulating the observer model many times in parallel with noise added. During simulation, the variance of the particles defining the estimator state is used to compute the particle filter gain. We applied our model to estimate one-dimensional angular velocity during yaw rotation, which yielded estimates for the velocity storage time constant, afferent noise, and perceptual noise that matched experimental data. We also found that the velocity storage time constant was Bayesian optimal by comparing the estimate of our particle filter with the estimate of the Kalman filter, which is optimal. The particle filter demonstrated a reduced velocity storage time constant when afferent noise increased, which mimics what is known about aminoglycoside ablation of semicircular canal hair cells. This model helps bridge the gap between parallel distributed neural computation and systems-level behavioral responses like the vestibuloocular response and perception. PMID:22514288

  17. Variable aspect ratio method in the Xu-White model for shear-wave velocity estimation

    NASA Astrophysics Data System (ADS)

    Bai, Jun-Yu; Yue, Cheng-Qi; Liang, Yi-Qiang; Song, Zhi-Xiang; Ling, Su; Zhang, Yang; Wu, Wei

    2013-06-01

    Shear-wave velocity logs are useful for various seismic interpretation applications, including bright spot analyses, amplitude-versus-offset analyses and multicomponent seismic interpretations. This paper presents a method for predicting the shear-wave velocity of argillaceous sandstone from conventional log data and experimental data, based on Gassmann's equations and the Xu-White model. This variable aspect ratio method takes into account all the influences of the matrix nature, shale content, porosity size and pore geometry, and the properties of pore fluid of argillaceous sandstone, replacing the fixed aspect ratio assumption in the conventional Xu-White model. To achieve this, we first use the Xu-White model to derive the bulk and shear modulus of dry rock in a sand-clay mixture. Secondly, we use Gassmann's equations to calculate the fluid-saturated elastic properties, including compressional and shear-wave velocities. Finally, we use the variable aspect ratio method to estimate the shear-wave velocity. The numerical results indicate that the variable aspect ratio method provides an important improvement in the application of the Xu-White model for sand-clay mixtures and allows for a variable aspect ratio log to be introduced into the Xu-White model instead of the constant aspect ratio assumption. This method shows a significant improvement in predicting velocities over the conventional Xu-White model.

  18. Viscous linear stability of axisymmetric low-density jets: Parameters influencing absolute instability

    NASA Astrophysics Data System (ADS)

    Srinivasan, V.; Hallberg, M. P.; Strykowski, P. J.

    2010-02-01

    Viscous linear stability calculations are presented for model low-density axisymmetric jet flows. Absolute growth transitions for the jet column mode are mapped out in a parametric space including velocity ratio, density ratio, Reynolds number, momentum thickness, and subtle differences between velocity and density profiles. Strictly speaking, the profiles used in most jet stability studies to date are only applicable to unity Prandtl numbers and zero pressure gradient flows—the present work relaxes this requirement. Results reveal how subtle differences between the velocity and density profiles generally used in jet stability theory can dramatically alter the absolute growth rate of the jet column mode in these low-density flows. The results suggest heating/cooling or mass diffusion at the outer nozzle surface can suppress absolute instability and potentially global instability in low-density jets.

  19. A math model for high velocity sensoring with a focal plane shuttered camera.

    NASA Technical Reports Server (NTRS)

    Morgan, P.

    1971-01-01

    A new mathematical model is presented which describes the image produced by a focal plane shutter-equipped camera. The model is based upon the well-known collinearity condition equations and incorporates both the translational and rotational motion of the camera during the exposure interval. The first differentials of the model with respect to exposure interval, delta t, yield the general matrix expressions for image velocities which may be simplified to known cases. The exposure interval, delta t, may be replaced under certain circumstances with a function incorporating blind velocity and image position if desired. The model is tested using simulated Lunar Orbiter data and found to be computationally stable as well as providing excellent results, provided that some external information is available on the velocity parameters.

  20. High Resolution Interseismic Velocity Model of the San Andreas Fault From GPS and InSAR

    NASA Astrophysics Data System (ADS)

    Tong, X.; Sandwell, D. T.; Smith-Konter, B. R.

    2011-12-01

    We recover the interseismic deformation along the entire San Andreas Fault System (SAFS) at a spatial resolution of 200 meters by combining InSAR and GPS observations using a dislocation model. Previous efforts to compare 17 different GPS-derived strain rate models of the SAFS shows that GPS data alone cannot uniquely resolve the rapid velocity gradients near faults, which are critical for understanding the along-strike variations in stress accumulation rate and associated earthquake hazard. To improve the near-fault velocity resolution, we integrate new GPS observations with InSAR observations, initially from ALOS (Advanced Land Observation Satellite launched by Japan Aerospace Exploration Agency) ascending data (spanning 2006.5-2010), using a remove/restore approach. More than 1100 interferograms were processed with the newly developed InSAR processing software GMTSAR. The integration uses a dislocation-based velocity model to interpolate the Line-Of-Sight (LOS) velocity at the full resolution of the InSAR data in radar coordinates. The residual between the model and InSAR LOS velocity are stacked and high-pass filtered, then added back to the model. This LOS velocity map covers almost entire San Andreas Fault System (see Figure 1) from Maacama Fault to the north to the Superstition Hills Fault to the south. The average standard deviation of the LOS velocity model ranges from 2 to 4 mm/yr. Our initial results show previously unknown details in along-strike variations in surface fault creep. Moreover, the high resolution velocity field can resolve asperities in these "creeping" sections that are important for understanding moment accumulation rates and seismic hazards. We find that much of the high resolution velocity signal is related to non-tectonic processes (e.g., ground subsidence and uplift) sometimes very close to the fault zone. The near-fault deformation signal extracted from this velocity map can provide tighter constraints on fault slip rates and

  1. One-dimensional velocity model of the Middle Kura Depresion from local earthquakes data of Azerbaijan

    NASA Astrophysics Data System (ADS)

    Yetirmishli, G. C.; Kazimova, S. E.; Kazimov, I. E.

    2011-09-01

    We present the method for determining the velocity model of the Earth's crust and the parameters of earthquakes in the Middle Kura Depression from the data of network telemetry in Azerbaijan. Application of this method allowed us to recalculate the main parameters of the hypocenters of the earthquake, to compute the corrections to the arrival times of P and S waves at the observation station, and to significantly improve the accuracy in determining the coordinates of the earthquakes. The model was constructed using the VELEST program, which calculates one-dimensional minimal velocity models from the travel times of seismic waves.

  2. A new global plate velocity model using space geodetic data, REVEL

    NASA Astrophysics Data System (ADS)

    Sella, G. F.; Dixon, T. H.; Mao, A.; Stein, S.

    2001-12-01

    Our model describes the relative velocities of 19 plates and continental blocks, and is derived from publicly available space geodetic (primarily GPS) data for the period 1993-2000. We include an independent and rigorous estimate for GPS velocity uncertainties in order to assess plate rigidity, and propagate these uncertainties to the velocity predictions. By excluding sites that may be influenced by seismic cycle effects within the plate boundary zone as well sites affected by glacial isostatic adjustment, we believe the plate velocity model is representative of geologically Recent motions (last ~10,000 years) and have termed it REVEL, for Recent velocity. Departures from short term rigid plate behaviour due to glacial isostatic adjustment are clearly observed for North America and Eurasia. Australia shows possible differences from rigid plate behavior in a manner consistent with its mapped intraplate stress field. We see statistically significant differences between the velocity predictions of REVEL-2000 and those of the NUVEL-1A geologic model for about one third of tested plate pairs. Pacific-North America motion and motion of the Caribbean plate with respect to North and South America are significantly faster than NUVEL-1A, presumably reflecting systematic errors in the geological model because the relevant rate data do not reflect the full plate rate. Many other differences between the geodetic and geological models appear to reflect real velocity changes over the last few million years. Nubia-Arabia and Arabia-Eurasia appear to be slowing, perhaps related to the collision of Arabia with Eurasia and consequent increased resistance to Arabia's northward motion Several other plate pairs, including Nazca-Pacific, Nazca-South America and Nubia-South America, are experiencing gradual slowing that dates back to about 25 Ma. This is the time of the initiation of the modern Andes mountains, and we speculate that associated crustal thickening on the leading edge of

  3. Developing a Crustal and Upper Mantle Velocity Model for the Brazilian Northeast

    NASA Astrophysics Data System (ADS)

    Julia, J.; Nascimento, R.

    2013-05-01

    Development of 3D models for the earth's crust and upper mantle is important for accurately predicting travel times for regional phases and to improve seismic event location. The Brazilian Northeast is a tectonically active area within stable South America and displays one of the highest levels of seismicity in Brazil, with earthquake swarms containing events up to mb 5.2. Since 2011, seismic activity is routinely monitored through the Rede Sismográfica do Nordeste (RSisNE), a permanent network supported by the national oil company PETROBRAS and consisting of 15 broadband stations with an average spacing of ~200 km. Accurate event locations are required to correctly characterize and identify seismogenic areas in the region and assess seismic hazard. Yet, no 3D model of crustal thickness and crustal and upper mantle velocity variation exists. The first step in developing such models is to refine crustal thickness and depths to major seismic velocity boundaries in the crust and improve on seismic velocity estimates for the upper mantle and crustal layers. We present recent results in crustal and uppermost mantle structure in NE Brazil that will contribute to the development of a 3D model of velocity variation. Our approach has consisted of: (i) computing receiver functions to obtain point estimates of crustal thickness and Vp/Vs ratio and (ii) jointly inverting receiver functions and surface-wave dispersion velocities from an independent tomography study to obtain S-velocity profiles at each station. This approach has been used at all the broadband stations of the monitoring network plus 15 temporary, short-period stations that reduced the inter-station spacing to ~100 km. We expect our contributions will provide the basis to produce full 3D velocity models for the Brazilian Northeast and help determine accurate locations for seismic events in the region.

  4. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  5. A simple way to model the pressure dependency of rock velocity

    NASA Astrophysics Data System (ADS)

    Han, Tongcheng

    2016-04-01

    Modeling the pressure dependency of rock velocity is important for interpreting and comparing the seismic and earthquake data from different depths. This study develops a multicomponent differential effective medium model for the elastic properties of porous rocks with two types of pores in the grain background without mixing order. The developed model is applied to modeling the pressure dependent elastic velocity of porous rocks by incorporating the variation of stiff and compliant porosity as a function of pressure. The pressure dependent stiff and compliant porosity were inverted from the measured total porosity under pressure using a dual porosity model, and the unknown constant stiff and compliant pore aspect ratios were inverted by best fitting the modeled velocity to the measured data. Application of the approach to a low porosity granite and a medium porosity sandstone sample showed that the pressure dependency of rock velocity can be satisfactorily modeled by the developed model using the pressure dependent stiff and compliant porosity and carefully estimated stiff and compliant pore aspect ratio values.

  6. HIGH-RESOLUTION SEISMIC VELOCITY AND ATTENUATION MODELS OF THE CAUCASUS-CASPIAN REGION

    SciTech Connect

    Mellors, R; Gok, R; Sandvol, E

    2007-07-10

    The southwest edge of Eurasia is a tectonically and structurally complex region that includes the Caspian and Black Sea basins, the Caucasus Mountains, and the high plateaus south of the Caucasus. Crustal and upper mantle velocities show great heterogeneity in this region and regional phases display variations in both amplitudes and travel time. Furthermore, due to a lack of quality data, the region has largely been unexplored in terms of the detailed lithospheric seismic structure. A unified high-resolution 3D velocity and attenuation model of the crust and upper mantle will be developed and calibrated. This model will use new data from 23 new broadband stations in the region analyzed with a comprehensive set of techniques. Velocity models of the crust and upper mantle will be developed using a joint inversion of receiver functions and surface waves. The surface wave modeling will use both event-based methods and ambient noise tomography. Regional phase (Pg, Pn, Sn, and Lg) Q model(s) will be constructed using the new data in combination with existing data sets. The results of the analysis (both attenuation and velocity modeling) will be validated using modeling of regional phases, calibration with selected events, and comparison with previous work. Preliminary analyses of receiver functions show considerable variability across the region. All results will be integrated into the KnowledgeBase.

  7. Low velocity impact experiments on the explosive LX-10 with modeling of reaction violence

    NASA Astrophysics Data System (ADS)

    Chidester, Steven; Garcia, Frank; Vandersall, Kevin S.; Tarver, Craig M.; Ferranti, Louis

    2012-03-01

    A new gas gun capability designed for the velocity range of ~20-400 m/s was used to study the mechanisms of low-velocity impact ignition and reaction violence of explosive targets in safety studies. Hemispherical charges of the HMX-based explosive LX-10 (95% HMX, 5% Viton binder) assembled in a polycarbonate target ring were impacted by a 6.35 mm diameter hardened steel rod protruding from a projectile at velocities ranging from 36 to 374 m/s. Digital high-speed (Phantom v12) cameras were utilized to capture the times of first ignition and a Photonic Doppler Velocimetry (PDV) probe placed at the rear of the target was used to measure the free surface velocity histories of an aluminum foil on the LX-10 surface to quantify the resulting reaction violence. The Ignition and Growth reactive flow model for LX-10 was used to compare the relative violence of these reactions to the intentional detonation of an equivalent LX-10 charge. It was found that comparing the model results to that of the experiment using this impactor geometry within the tested velocity range, the reaction violence increased with velocity from 45-374 m/s and only a small fraction of material appears to react during the impact.

  8. Fabry-Perot interferometer measurement of static temperature and velocity for ASTOVL model tests

    NASA Technical Reports Server (NTRS)

    Kourous, Helen E.; Seacholtz, Richard G.

    1995-01-01

    A spectrally resolved Rayleigh/Mie scattering diagnostic was developed to measure temperature and wing-spanwise velocity in the vicinity of an ASTOVL aircraft model in the Lewis 9 x 15 Low Speed Wind Tunnel. The spectrum of argon-ion laser light scattered by the air molecules and particles in the flow was resolved with a Fabry-Perot interferometer. Temperature was extracted from the spectral width of the Rayleigh scattering component, and spanwise gas velocity from the gross spectral shift. Nozzle temperature approached 800 K, and the velocity component approached 30 m/s. The measurement uncertainty was about 5 percent for the gas temperature, and about 10 m/s for the velocity. The large difference in the spectral width of the Mie scattering from particles and the Rayleigh scattering from gas molecules allowed the gas temperature to be measured in flow containing both naturally occurring dust and LDV seed (both were present).

  9. Traffic stability of a car-following model considering driver’s desired velocity

    NASA Astrophysics Data System (ADS)

    Zhang, Geng; Sun, Di-Hua; Liu, Wei-Ning; Liu, Hui

    2015-07-01

    In this paper, a new car-following model is proposed by considering driver’s desired velocity according to Transportation Cyber Physical Systems. The effect of driver’s desired velocity on traffic flow has been investigated through linear stability theory and nonlinear reductive perturbation method. The linear stability condition shows that driver’s desired velocity effect can enlarge the stable region of traffic flow. From nonlinear analysis, the Burgers equation and mKdV equation are derived to describe the evolution properties of traffic density waves in the stable and unstable regions respectively. Numerical simulation is carried out to verify the analytical results, which reveals that traffic congestion can be suppressed efficiently by taking driver’s desired velocity effect into account.

  10. Constraining the absolute orientation of η Carinae's binary orbit: a 3D dynamical model for the broad [Fe III] emission

    NASA Astrophysics Data System (ADS)

    Madura, T. I.; Gull, T. R.; Owocki, S. P.; Groh, J. H.; Okazaki, A. T.; Russell, C. M. P.

    2012-03-01

    We present a three-dimensional (3D) dynamical model for the broad [Fe III] emission observed in η Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS). This model is based on full 3D smoothed particle hydrodynamics simulations of η Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectroimages of [Fe III] emission-line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA θ that the orbital plane projection of the line of sight makes with the apastron side of the semimajor axis and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3D orientation of the binary orbit. To simultaneously reproduce the blueshifted emission arcs observed at orbital phase 0.976, STIS slit PA =+38° and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i≈ 130° to 145°, θ≈-15° to +30° and an orbital axis projected on the sky at a PA ≈ 302° to 327° east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3D. The companion star, ηB, thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modelling to determine the stellar masses. Footnotes<label>1</label>Low- and high-ionization refer here to atomic species with ionizations potentials (IPs) below and above the IP of hydrogen, 13.6 eV.<label>2</label>Measured in degrees from north to east.<label>3</label>θ is the same as the angle φ defined in fig. 3 of O08.<label>4</label>The outer edge looks circular only because this marks the edge of the spherical computational domain of the SPH simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1028098','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1028098"><span id="translatedtitle">Atmospheric Longwave Irradiance Uncertainty: Pyrgeometers Compared to an <span class="hlt">Absolute</span> Sky-Scanning Radiometer, Atmospheric Emitted Radiance Interferometer, and Radiative Transfer <span class="hlt">Model</span> Calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Philipona, J. R.; Dutton, Ellsworth G.; Stoffel, T.; Michalsky, Joseph J.; Reda, I.; Stifter, Armin; Wendling, Peter; Wood, Norm; Clough, Shepard A.; Mlawer, Eli J.; Anderson, Gail; Revercomb, Henry E.; Shippert, Timothy R.</p> <p>2001-06-04</p> <p>Because atmospheric longwave radiation is one of the most fundamental elements of an expected climate change, there has been a strong interest in improving measurements and <span class="hlt">model</span> calculations in recent years. Important questions are how reliable and consistent are atmospheric longwave radiation measurements and calculations and what are the uncertainties? The First International Pyrgeometer and <span class="hlt">Absolute</span> Sky-scanning Radiometer Comparison, which was held at the Atmospheric Radiation Measurement program's Souther Great Plains site in Oklahoma, answers these questions at least for midlatitude summer conditions and reflects the state of the art for atmospheric longwave radiation measurements and calculations. The 15 participating pyrgeometers were all calibration-traced standard instruments chosen from a broad international community. Two new chopped pyrgeometers also took part in the comparison. And <span class="hlt">absolute</span> sky-scanning radiometer (ASR), which includes a pyroelectric detector and a reference blackbody source, was used for the first time as a reference standard instrument to field calibrate pyrgeometers during clear-sky nighttime measurements. Owner-provided and uniformly determined blackbody calibration factors were compared. Remarkable improvements and higher pyrgeometer precision were achieved with field calibration factors. Results of nighttime and daytime pyrgeometer precision and <span class="hlt">absolute</span> uncertainty are presented for eight consecutive days of measurements, during which period downward longwave irradiance varied between 260 and 420 W m-2. Comparisons between pyrgeometers and the <span class="hlt">absolute</span> ASR, the atmospheric emitted radiance interferometer, and radiative transfer <span class="hlt">models</span> LBLRTM and MODTRAN show a surprisingly good agreement of <2 W m-2 for nighttime atmospheric longwave irradiance measurements and calculations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22130451','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22130451"><span id="translatedtitle">Quasilinear <span class="hlt">model</span> for energetic particle diffusion in radial and <span class="hlt">velocity</span> space</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Waltz, R. E.; Staebler, G. M.; Bass, E. M.</p> <p>2013-04-15</p> <p>A quasilinear <span class="hlt">model</span> for passive energetic particle (EP) turbulent diffusion in radial and <span class="hlt">velocity</span> space is fitted and tested against nonlinear gyrokinetic tokamak simulations with the GYRO code [J. Candy and R. E. Waltz, Phys. Rev. Lett. 91, 045001 (2003)]. Off diagonal elements of a symmetric positive definite 2 Multiplication-Sign 2 EP diffusion matrix account for fluxes up radial (energy) gradients driven by energy (radial) gradients of the EP <span class="hlt">velocity</span> space distribution function. The quasilinear ratio kernel of the <span class="hlt">model</span> is provided by a simple analytic formula for the EP radial and <span class="hlt">velocity</span> space EP diffusivity relative to radial thermal ion energy diffusivity at each linear mode of the turbulence driven by the thermal plasma. The TGLF [G. M. Staebler, J. E. Kinsey, and R. E. Waltz, Phys. Plasmas 14, 0055909 (2007); ibid. 15, 0055908 (2008)] tokamak transport <span class="hlt">model</span> provides the linear mode frequency and growth rates to the kernel as well as the nonlinear spectral weight for each mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhPl...20d2510W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhPl...20d2510W"><span id="translatedtitle">Quasilinear <span class="hlt">model</span> for energetic particle diffusion in radial and <span class="hlt">velocity</span> space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Waltz, R. E.; Bass, E. M.; Staebler, G. M.</p> <p>2013-04-01</p> <p>A quasilinear <span class="hlt">model</span> for passive energetic particle (EP) turbulent diffusion in radial and <span class="hlt">velocity</span> space is fitted and tested against nonlinear gyrokinetic tokamak simulations with the GYRO code [J. Candy and R. E. Waltz, Phys. Rev. Lett. 91, 045001 (2003)]. Off diagonal elements of a symmetric positive definite 2×2 EP diffusion matrix account for fluxes up radial (energy) gradients driven by energy (radial) gradients of the EP <span class="hlt">velocity</span> space distribution function. The quasilinear ratio kernel of the <span class="hlt">model</span> is provided by a simple analytic formula for the EP radial and <span class="hlt">velocity</span> space EP diffusivity relative to radial thermal ion energy diffusivity at each linear mode of the turbulence driven by the thermal plasma. The TGLF [G. M. Staebler, J. E. Kinsey, and R. E. Waltz, Phys. Plasmas 14, 0055909 (2007); ibid. 15, 0055908 (2008)] tokamak transport <span class="hlt">model</span> provides the linear mode frequency and growth rates to the kernel as well as the nonlinear spectral weight for each mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987KosIs..25..133B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987KosIs..25..133B"><span id="translatedtitle">Investigation of the radiation brightness of gases around a burning <span class="hlt">model</span> moving at supersonic <span class="hlt">velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baulin, N. N.; Kuvalkin, D. G.; Piliugin, N. N.; Taganov, O. K.; Tikhomirov, S. G.</p> <p>1987-01-01</p> <p>Experimental results are presented on the ablation and shape change of burning <span class="hlt">models</span> made of a pyrotechnic composition moving in air at supersonic <span class="hlt">velocity</span>. A radiometer was used to measure the radiation brightness at a wavelength of 0.63 micron in the shock layer and wake of the burning <span class="hlt">models</span>. The glow characteristics are determined as a function of the initial air pressure in the path of motion; and a theoretical <span class="hlt">model</span> for the motion and ablation of burning bodies flying at supersonic <span class="hlt">velocity</span> is developed which satisfactorily describes the experimental results. The present study is of interest in connection with the aerodynamic heating of vehicles flying at hypersonic <span class="hlt">velocity</span> in planetary atmospheres.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JPhCS.333a2014P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JPhCS.333a2014P"><span id="translatedtitle">Effects of subfilter <span class="hlt">velocity</span> <span class="hlt">modelling</span> on dispersed phase in LES of heated channel flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pozorski, Jacek; Knorps, Maria; Łuniewski, Mirosław</p> <p>2011-12-01</p> <p>A non-isothermal turbulent flow with the dispersed phase is <span class="hlt">modelled</span> using the Large Eddy Simulation (LES) approach for fluid, one-way coupled with the equations of point-particle evolution. The channel is heated at both walls and isoflux boundary conditions are applied for fluid. Particle <span class="hlt">velocity</span> and thermal statistics are computed. Of particular interest are the r.m.s. profiles and the probability density function of particle temperature in the near-wall region. We compare our findings with available reference data for particle-laden, heated channel flow. Moreover, an open issue in LES is the influence of non-resolved (residual) scales of fluid <span class="hlt">velocity</span> and temperature fields on particles. In the present contribution, we apply a stochastic <span class="hlt">model</span> for subfilter fluid <span class="hlt">velocity</span> at the particle positions that aims at reconstructing the effects of the smallest scales of turbulence on particle dynamics. We analyse the impact of this <span class="hlt">model</span> on particle thermal statistics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000038172&hterms=mass+balance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bbalance','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000038172&hterms=mass+balance&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmass%2Bbalance"><span id="translatedtitle">Balance <span class="hlt">Velocities</span> of the Greenland Ice Sheet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Joughin, Ian; Fahnestock, Mark; Ekholm, Simon; Kwok, Ron</p> <p>1997-01-01</p> <p>We present a map of balance <span class="hlt">velocities</span> for the Greenland ice sheet. The resolution of the underlying DEM, which was derived primarily from radar altimetry data, yields far greater detail than earlier balance <span class="hlt">velocity</span> estimates for Greenland. The <span class="hlt">velocity</span> contours reveal in striking detail the location of an ice stream in northeastern Greenland, which was only recently discovered using satellite imagery. Enhanced flow associated with all of the major outlets is clearly visible, although small errors in the source data result in less accurate estimates of the <span class="hlt">absolute</span> flow speeds. Nevertheless, the balance map is useful for ice-sheet <span class="hlt">modelling</span>, mass balance studies, and field planning.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AtmEn..56..154Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AtmEn..56..154Z"><span id="translatedtitle"><span class="hlt">Modeling</span> the effect of humidity on the threshold friction <span class="hlt">velocity</span> of coal particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Xiaochun; Chen, Weiping; Ma, Chun; Zhan, Shuifen</p> <p>2012-09-01</p> <p>Coal particles emission could cause serious air pollution in coal production region and transport region. In coal mining industry, large amounts of water are regularly spayed to coal piles to prevent dust emission from the coal particles. The mechanism behind this measure is to manage the threshold friction <span class="hlt">velocity</span>, which is an important parameter in controlling wind erosion and dust emission. Bagnold has developed a threshold friction <span class="hlt">velocity</span> <span class="hlt">model</span> for soil particles. However, the Bagnold <span class="hlt">model</span> cannot be applied directly to coal particles as coal particles are quite different from soils in physical and chemical properties. We studied and <span class="hlt">modeled</span> threshold friction <span class="hlt">velocity</span> of coal particles under different humidities by using a wind tunnel. Results showed that the effects of humidity on coal particles' threshold friction <span class="hlt">velocity</span> are related to the hydrophilic effect and adhesive effect. Bagnold <span class="hlt">model</span> can be corrected by two new parameter items which explained the two effects. The new <span class="hlt">model</span>, agreed well with wind tunnel measurements for coal particles with different size categories. Despite the fact the new <span class="hlt">model</span> was developed for coal particles, its physical basis may allow the <span class="hlt">model</span> application to other wind susceptible particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.S22D..06L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.S22D..06L"><span id="translatedtitle">Probabilistic earthquake location and 3-D <span class="hlt">velocity</span> <span class="hlt">models</span> in routine earthquake location</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lomax, A.; Husen, S.</p> <p>2003-12-01</p> <p>Earthquake monitoring agencies, such as local networks or CTBTO, are faced with the dilemma of providing routine earthquake locations in near real-time with high precision and meaningful uncertainty information. Traditionally, routine earthquake locations are obtained from linearized inversion using layered seismic <span class="hlt">velocity</span> <span class="hlt">models</span>. This approach is fast and simple. However, uncertainties derived from a linear approximation to a set of non-linear equations can be imprecise, unreliable, or even misleading. In addition, 1-D <span class="hlt">velocity</span> <span class="hlt">models</span> are a poor approximation to real Earth structure in tectonically complex regions. In this paper, we discuss the routine location of earthquakes in near real-time with high precision using non-linear, probabilistic location methods and 3-D <span class="hlt">velocity</span> <span class="hlt">models</span>. The combination of non-linear, global search algorithms with probabilistic earthquake location provides a fast and reliable tool for earthquake location that can be used with any kind of <span class="hlt">velocity</span> <span class="hlt">model</span>. The probabilistic solution to the earthquake location includes a complete description of location uncertainties, which may be irregular and multimodal. We present applications of this approach to determine seismicity in Switzerland and in Yellowstone National Park, WY. Comparing our earthquake locations to earthquake locations obtained using linearized inversion and 1-D <span class="hlt">velocity</span> <span class="hlt">models</span> clearly demonstrates the advantages of probabilistic earthquake location and 3-D <span class="hlt">velocity</span> <span class="hlt">models</span>. For example, the more complete and reliable uncertainty information of non-linear, probabilistic earthquake location greatly facilitates the identification of poorly constrained hypocenters. Such events are often not identified in linearized earthquake location, since the location uncertainties are determined with a simplified, localized and approximate Gaussian statistic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MNRAS.tmp.1353B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016MNRAS.tmp.1353B&link_type=ABSTRACT"><span id="translatedtitle">Improving the <span class="hlt">modelling</span> of redshift-space distortions - II. A pairwise <span class="hlt">velocity</span> <span class="hlt">model</span> covering large and small scales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bianchi, Davide; Percival, Will J.; Bel, Julien</p> <p>2016-09-01</p> <p>We develop a <span class="hlt">model</span> for the redshift-space correlation function, valid for both dark matter particles and halos on scales >5 h-1Mpc. In its simplest formulation, the <span class="hlt">model</span> requires the knowledge of the first three moments of the line-of-sight pairwise <span class="hlt">velocity</span> distribution plus two well-defined dimensionless parameters. The <span class="hlt">model</span> is obtained by extending the Gaussian-Gaussianity prescription for the <span class="hlt">velocity</span> distribution, developed in a previous paper, to a more general concept allowing for local skewness, which is required to match simulations. We compare the <span class="hlt">model</span> with the well known Gaussian streaming <span class="hlt">model</span> and the more recent Edgeworth streaming <span class="hlt">model</span>. Using N-body simulations as a reference, we show that our <span class="hlt">model</span> gives a precise description of the redshift-space clustering over a wider range of scales. We do not discuss the theoretical prescription for the evaluation of the <span class="hlt">velocity</span> moments, leaving this topic to further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.A11E0099L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.A11E0099L"><span id="translatedtitle">Estimating hurricane vertical <span class="hlt">velocity</span> from Doppler radar for high-resolution hurricane <span class="hlt">model</span> initialization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, J.</p> <p>2013-12-01</p> <p>A mesoscale vorticity method derives the hurricane inner-core vertical <span class="hlt">velocity</span> from the vorticity variations in space and in time estimated from a deep layer of wind measurements obtained from Doppler radar. The vorticity method derives the hurricane inner core vertical <span class="hlt">velocity</span> and thus, the divergent wind based on the mesoscale vorticity equation. The inner-core divergent wind inferred dynamically and rotational wind estimated from radar data form the total horizontal wind which is dynamically balanced with the derived vertical <span class="hlt">velocity</span>. The derived high-resolution balance wind field is suitable for high resolution hurricane <span class="hlt">models</span> initialization. The vorticity method is tested using a high-resolution non-hydrostatic hurricane <span class="hlt">model</span> with radar data from Hurricane Danny which made landfall along the Alabama coast in 1997. Numerical experiments with a high resolution non-hydrostatic hurricane <span class="hlt">model</span> show positive radar data impacts on track and intensity forecasts, in particular, substantial improvements on the hurricane inner core <span class="hlt">velocity</span> field, can be obtained with the vertical <span class="hlt">velocity</span> and thus inner-core divergent wind inferred from the mesoscale vorticity method.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010OcMod..31...28J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010OcMod..31...28J"><span id="translatedtitle">Tuning a physically-based <span class="hlt">model</span> of the air-sea gas transfer <span class="hlt">velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jeffery, C. D.; Robinson, I. S.; Woolf, D. K.</p> <p></p> <p>Air-sea gas transfer <span class="hlt">velocities</span> are estimated for one year using a 1-D upper-ocean <span class="hlt">model</span> (GOTM) and a modified version of the NOAA-COARE transfer <span class="hlt">velocity</span> parameterization. Tuning parameters are evaluated with the aim of bringing the physically based NOAA-COARE parameterization in line with current estimates, based on simple wind-speed dependent <span class="hlt">models</span> derived from bomb-radiocarbon inventories and deliberate tracer release experiments. We suggest that A = 1.3 and B = 1.0, for the sub-layer scaling parameter and the bubble mediated exchange, respectively, are consistent with the global average CO 2 transfer <span class="hlt">velocity</span> k. Using these parameters and a simple 2nd order polynomial approximation, with respect to wind speed, we estimate a global annual average k for CO 2 of 16.4 ± 5.6 cm h -1 when using global mean winds of 6.89 m s -1 from the NCEP/NCAR Reanalysis 1 1954-2000. The tuned <span class="hlt">model</span> can be used to predict the transfer <span class="hlt">velocity</span> of any gas, with appropriate treatment of the dependence on molecular properties including the strong solubility dependence of bubble-mediated transfer. For example, an initial estimate of the global average transfer <span class="hlt">velocity</span> of DMS (a relatively soluble gas) is only 11.9 cm h -1 whilst for less soluble methane the estimate is 18.0 cm h -1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvD..91d3523Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvD..91d3523Z"><span id="translatedtitle">Sampling artifact in volume weighted <span class="hlt">velocity</span> measurement. II. Detection in simulations and comparison with theoretical <span class="hlt">modeling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, Yi; Zhang, Pengjie; Jing, Yipeng</p> <p>2015-02-01</p> <p>Measuring the volume weighted <span class="hlt">velocity</span> power spectrum suffers from a severe systematic error due to imperfect sampling of the <span class="hlt">velocity</span> field from the inhomogeneous distribution of dark matter particles/halos in simulations or galaxies with <span class="hlt">velocity</span> measurement. This "sampling artifact" depends on both the mean particle number density n¯P and the intrinsic large scale structure (LSS) fluctuation in the particle distribution. (1) We report robust detection of this sampling artifact in N -body simulations. It causes ˜12 % underestimation of the <span class="hlt">velocity</span> power spectrum at k =0.1 h /Mpc for samples with n¯ P=6 ×10-3 (Mpc /h )-3 . This systematic underestimation increases with decreasing n¯P and increasing k . Its dependence on the intrinsic LSS fluctuations is also robustly detected. (2) All of these findings are expected based upon our theoretical <span class="hlt">modeling</span> in paper I [P. Zhang, Y. Zheng, and Y. Jing, Sampling artifact in volume weighted <span class="hlt">velocity</span> measurement. I. Theoretical <span class="hlt">modeling</span>, arXiv:1405.7125.]. In particular, the leading order theoretical approximation agrees quantitatively well with the simulation result for n¯ P≳6 ×10-4 (Mpc /h )-3 . Furthermore, we provide an ansatz to take high order terms into account. It improves the <span class="hlt">model</span> accuracy to ≲1 % at k ≲0.1 h /Mpc over 3 orders of magnitude in n¯P and over typical LSS clustering from z =0 to z =2 . (3) The sampling artifact is determined by the deflection D field, which is straightforwardly available in both simulations and data of galaxy <span class="hlt">velocity</span>. Hence the sampling artifact in the <span class="hlt">velocity</span> power spectrum measurement can be self-calibrated within our framework. By applying such self-calibration in simulations, it is promising to determine the real large scale <span class="hlt">velocity</span> bias of 1013M⊙ halos with ˜1 % accuracy, and that of lower mass halos with better accuracy. (4) In contrast to suppressing the <span class="hlt">velocity</span> power spectrum at large scale, the sampling artifact causes an overestimation of the <span class="hlt">velocity</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.T51B1516B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.T51B1516B"><span id="translatedtitle">3-D crustal <span class="hlt">velocity</span> <span class="hlt">model</span> for Lithuania and its application to local event studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Budraitis, M.; Kozlovskaya, E.; Janutyte, I.; Motuza, G.</p> <p>2009-12-01</p> <p>PASSEQ 2006-2008 project (PASsive Seismic Experiment in TESZ) aimed at studying the lithosphere-asthenosphere system around the TransEuropean Suture Zone (TESZ)- the transition between old Proterozoic platform of north and east Europe and younger Phanerozoic platform in central and western Europe. The experiment was a seismic array research aiming to retrieve the structure of the crust and Earth's mantle down to the mantle transition zone, including mapping of upper mantle seismic <span class="hlt">velocity</span> variations and discontinuities (Moho, lithosphere-asthenosphere boundary, mantle transition zone) using all available techniques. During the experiment 26 seismic stations (including four broadband stations) were installed in Lithuania and operated since June, 2006 till January, 2008. One of the main reasons of PASSEQ deployment in Lithuania is identification and characterisation of the local seismic activity. During the data acquisition period a number of local seismic events was identified and preliminary event location was made using LocSat and VELEST algorithms and 1-D <span class="hlt">velocity</span> <span class="hlt">models</span>. These standard procedures is not enough precise for Lithuania, however, because the thickness of the crust varies significantly in the region (from 45 to 55 km). Another problem was low quality of S-wave arrivals due to thick (up to 2 km) sediments in most part of Lithuania. In order to improve event location, we compiled a 3-D seismic <span class="hlt">velocity</span> <span class="hlt">model</span> of the crust down to a depth of 60 km. The <span class="hlt">model</span>, consisting of four major layers (sediments, upper crust, middle crust, lower crust and uppermost mantle) was interpolated from 2-D <span class="hlt">velocity</span> <span class="hlt">models</span> along previous wide-angle reflection and refraction profiles into a regular grid. The quality of the approximation was analysed using comparison of travel times of P-waves recorded by controlled source experiments and calculated travel times through the 3-D <span class="hlt">velocity</span> <span class="hlt">model</span>. The <span class="hlt">model</span> was converted into a density <span class="hlt">model</span> using a special procedure, in which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008JGRB..113.6306K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008JGRB..113.6306K"><span id="translatedtitle">Anisotropic shear-wave <span class="hlt">velocity</span> structure of the Earth's mantle: A global <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kustowski, B.; EkströM, G.; DziewońSki, A. M.</p> <p>2008-06-01</p> <p>We combine a new, large data set of surface wave phase anomalies, long-period waveforms, and body wave travel times to construct a three-dimensional <span class="hlt">model</span> of the anisotropic shear wave <span class="hlt">velocity</span> in the Earth's mantle. Our <span class="hlt">modeling</span> approach is improved and more comprehensive compared to our earlier studies and involves the development and implementation of a new spherically symmetric reference <span class="hlt">model</span>, simultaneous inversion for <span class="hlt">velocity</span> and anisotropy, as well as discontinuity topographies, and implementation of nonlinear crustal corrections for waveforms. A comparison of our new three-dimensional <span class="hlt">model</span>, S362ANI, with two other <span class="hlt">models</span> derived from comparable data sets but using different techniques reveals persistent features: (1) strong, ˜200-km-thick, high-<span class="hlt">velocity</span> anomalies beneath cratons, likely representing the continental lithosphere, underlain by weaker, fast anomalies extending below 250 km, which may represent continental roots, (2) weak <span class="hlt">velocity</span> heterogeneity between 250 and 400 km depths, (3) fast anomalies extending horizontally up to 2000-3000 km in the mantle transition zone beneath subduction zones, (4) lack of strong long-wavelength heterogeneity below 650 km suggesting inhibiting character of the upper mantle-lower mantle boundary, and (5) slow-<span class="hlt">velocity</span> superplumes beneath the Pacific and Africa. The shear wave radial anisotropy is strongest at 120 km depth, in particular beneath the central Pacific. Lateral anisotropic variations appreciably improve the fit to data that are predominantly sensitive to the uppermost and lowermost mantle but not to the waveforms that control the transition zone and midmantle depths. Tradeoffs between lateral variations in <span class="hlt">velocity</span> and anisotropy are negligible in the uppermost mantle but noticeable at the bottom of the mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70026174','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70026174"><span id="translatedtitle">Seismic <span class="hlt">velocity</span> <span class="hlt">models</span> for the Denali fault zone along the Richardson Highway, Alaska</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Brocher, T.M.; Fuis, G.S.; Lutter, W.J.; Christensen, N.I.; Ratchkovski, N.A.</p> <p>2004-01-01</p> <p>Crustal-scale seismic-<span class="hlt">velocity</span> <span class="hlt">models</span> across the Denali fault zone along the Richardson Highway show a 50-km-thick crust, a near vertical fault trace, and a 5-km-wide damage zone associated with the fault near Trans-Alaska Pipeline Pump Station 10, which provided the closest strong ground motion recordings of the 2002 Denali fault earthquake. We compare <span class="hlt">models</span>, derived from seismic reflection and refraction surveys acquired in 1986 and 1987, to laboratory measurements of seismic <span class="hlt">velocities</span> for typical metamorphic rocks exposed along the profiles. Our <span class="hlt">model</span> for the 1986 seismic reflection profile indicates a 5-km-wide low-<span class="hlt">velocity</span> zone in the upper 1 km of the Denali fault zone, which we interpret as fault gouge. Deeper refractions from our 1987 line image a 40-km wide, 5-km-deep low-<span class="hlt">velocity</span> zone along the Denali fault and nearby associated fault strands, which we attribute to a composite damage zone along several strands of the Denali fault zone and to the obliquity of the seismic line to the fault zone. Our <span class="hlt">velocity</span> <span class="hlt">model</span> and other geophysical data indicate a nearly vertical Denali fault zone to a depth of 30 km. After-shocks of the 2002 Denali fault earthquake and our <span class="hlt">velocity</span> <span class="hlt">model</span> provide evidence for a flower structure along the fault zone consisting of faults dipping toward and truncated by the Denali fault. Wide-angle reflections indicate that the crustal thickness beneath the Denali fault is transitional between the 60-km-thick crust beneath the Alaska Range to the south, and the extended, 30-km-thick crust of the Yukon-Tanana terrane to the north.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044834&hterms=spheroid+models&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dspheroid%2Bmodels','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044834&hterms=spheroid+models&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dspheroid%2Bmodels"><span id="translatedtitle">A <span class="hlt">model</span> of the planetary nebula NGC 2392 determined from <span class="hlt">velocity</span> observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Odell, C. R.; Ball, M. E.</p> <p>1985-01-01</p> <p>High-resolution slit spectra are combined with published photometric and <span class="hlt">velocity</span> data to develop a <span class="hlt">model</span> of the double-ring planetary nebula NGC 2392. The inner ring is due to an incomplete, prolate spheroid shell with most of the material concentrated near the minor axis circumference. The spheroid is seen almost pole-on, open at the sharp ends, and the formal <span class="hlt">velocity</span> of expansion (93 km/s) at the ends is a record high for planetary nebulae. The outer ring is a nearly round spheroid of approximately 16 km/s expansion <span class="hlt">velocity</span> and a different tilt angle than the inner shell. It is surrounded by rapidly expanding material with <span class="hlt">velocities</span> of at least 75 km/s. A high-<span class="hlt">velocity</span> stream of material is formed at the open ends of the inner shell and is accelerated by the central star's stellar wind to <span class="hlt">velocities</span> of at least + or - 190 km/s, providing the first direct evidence for the kinematic role of a strong stellar wind. The inner shell age is approximately 800 yr, arguing that the shell material was preferentially ejected from the equator of the parent star, in contradiction with the usual predictions of theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730024449','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730024449"><span id="translatedtitle">Pilot <span class="hlt">model</span> expansion tunnel test flow properties obtained from <span class="hlt">velocity</span>, pressure, and probe measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Friesen, W. J.; Moore, J. A.</p> <p>1973-01-01</p> <p><span class="hlt">Velocity</span>-profile, pitot-pressure, and supplemental probe measurements were made at the nozzle exist of an expansion tunnel (a modification to the Langley pilot <span class="hlt">model</span> expansion tube) for a nozzle net condition of a nitrogen test sample with a <span class="hlt">velocity</span> of 4.5 km/sec and a density 0.005 times the density of nitrogen at standard conditions, both with the nozzle initially immersed in a helium atmosphere and with the nozzle initially evacuated. The purpose of the report is to present the results of these measurements and some of the physical properties of the nitrogen test sample which can be inferred from the measured results. The main conclusions reached are that: the <span class="hlt">velocity</span> profiles differ for two nozzle conditions; regions of the flow field can be found where the <span class="hlt">velocity</span> is uniform to within 5 percent and constant for several hundred microseconds; the <span class="hlt">velocity</span> of the nitrogen test sample is reduced due to passage through the nozzle; and the <span class="hlt">velocity</span> profiles do not significantly reflect the large variations which occur in the inferred density profiles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70025878','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70025878"><span id="translatedtitle">Shallow-<span class="hlt">velocity</span> <span class="hlt">models</span> at the Kilauea Volcano, Hawaii, determined from array analyses of tremor wavefields</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Saccorotti, G.; Chouet, B.; Dawson, P.</p> <p>2003-01-01</p> <p>The properties of the surface wavefield at Kilauea Volcano are analysed using data from small-aperture arrays of short-period seismometers deployed in and around the Kilauea caldera. Tremor recordings were obtained during two Japan-US cooperative experiments conducted in 1996 and 1997. The seismometers were deployed in three semi-circular arrays with apertures of 300, 300 and 400 m, and a linear array with length of 1680 m. Data are analysed using a spatio-temporal correlation technique well suited for the study of the stationary stochastic wavefields of Rayleigh and Love waves associated with volcanic activity and scattering sources distributed in and around the summit caldera. Spatial autocorrelation coefficients are obtained as a function of frequency and are inverted for the dispersion characteristics of Rayleigh and Love waves using a grid search that seeks phase <span class="hlt">velocities</span> for which the L-2 norm between data and forward <span class="hlt">modelling</span> operators is minimized. Within the caldera, the phase <span class="hlt">velocities</span> of Rayleigh waves range from 1400 to 1800 m s-1 at 1 Hz down to 300-400 m s-1 at 10 Hz, and the phase <span class="hlt">velocities</span> of Love waves range from 2600 to 400 m s-1 within the same frequency band. Outside the caldera, Rayleigh wave <span class="hlt">velocities</span> range from 1800 to 1600 m s-1 at 1 Hz down to 260-360 m s-1 at 10 Hz, and Love wave <span class="hlt">velocities</span> range from 600 to 150 m s-1 within the same frequency band. The dispersion curves are inverted for <span class="hlt">velocity</span> structure beneath each array, assuming these dispersions represent the fundamental modes of Rayleigh and Love waves. The <span class="hlt">velocity</span> structures observed at different array sites are consistent with results from a recent 3-D traveltime tomography of the caldera region, and point to a marked <span class="hlt">velocity</span> discontinuity associated with the southern caldera boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11736257','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11736257"><span id="translatedtitle">Cellular automaton <span class="hlt">model</span> considering the <span class="hlt">velocity</span> effect of a car on the successive car.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, X; Wu, Q; Jiang, R</p> <p>2001-12-01</p> <p>In this paper we present a cellular automata <span class="hlt">model</span> for one-lane traffic flow. The update rules of <span class="hlt">velocity</span> of a car depend not only on the positions of this car and the car ahead of it, but also on the <span class="hlt">velocities</span> of the two cars. Using computer simulations we obtain some basic qualitative results and the fundamental diagram of the proposed <span class="hlt">model</span>. In comparison with those of the existing <span class="hlt">models</span> in the literature, we find that the fundamental diagram of the proposed <span class="hlt">model</span> is more consistent with the results measured in the real traffic, and the <span class="hlt">model</span> is able to reproduce some relevant macroscopic states that are found in the real traffic flow but cannot be predicted by the existing <span class="hlt">models</span>. PMID:11736257</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013aero.confE.327L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013aero.confE.327L"><span id="translatedtitle">Polar versus Cartesian <span class="hlt">velocity</span> <span class="hlt">models</span> for maneuvering target tracking with IMM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laneuville, Dann</p> <p></p> <p>This paper compares various <span class="hlt">model</span> sets in different IMM filters for the maneuvering target tracking problem. The aim is to see whether we can improve the tracking performance of what is certainly the most widely used <span class="hlt">model</span> set in the literature for the maneuvering target tracking problem: a Nearly Constant <span class="hlt">Velocity</span> <span class="hlt">model</span> and a Nearly Coordinated Turn <span class="hlt">model</span>. Our new challenger set consists of a mixed Cartesian position and polar <span class="hlt">velocity</span> state vector to describe the uniform motion segments and is augmented with the turn rate to obtain the second <span class="hlt">model</span> for the maneuvering segments. This paper also gives a general procedure to discretize up to second order any non-linear continuous time <span class="hlt">model</span> with linear diffusion. Comparative simulations on an air defence scenario with a 2D radar, show that this new approach improves significantly the tracking performance in this case.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9771G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9771G"><span id="translatedtitle"><span class="hlt">Modeling</span> continuous seismic <span class="hlt">velocity</span> changes due to ground shaking in Chile</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gassenmeier, Martina; Richter, Tom; Sens-Schönfelder, Christoph; Korn, Michael; Tilmann, Frederik</p> <p>2015-04-01</p> <p>In order to investigate temporal seismic <span class="hlt">velocity</span> changes due to earthquake related processes and environmental forcing, we analyze 8 years of ambient seismic noise recorded by the Integrated Plate Boundary Observatory Chile (IPOC) network in northern Chile between 18° and 25° S. The Mw 7.7 Tocopilla earthquake in 2007 and the Mw 8.1 Iquique earthquake in 2014 as well as numerous smaller events occurred in this area. By autocorrelation of the ambient seismic noise field, approximations of the Green's functions are retrieved. The recovered function represents backscattered or multiply scattered energy from the immediate neighborhood of the station. To detect relative changes of the seismic <span class="hlt">velocities</span> we apply the stretching method, which compares individual autocorrelation functions to stretched or compressed versions of a long term averaged reference autocorrelation function. We use time windows in the coda of the autocorrelations, that contain scattered waves which are highly sensitive to minute changes in the <span class="hlt">velocity</span>. At station PATCX we observe seasonal changes in seismic <span class="hlt">velocity</span> as well as temporary <span class="hlt">velocity</span> reductions in the frequency range of 4-6 Hz. The seasonal changes can be attributed to thermal stress changes in the subsurface related to variations of the atmospheric temperature. This effect can be <span class="hlt">modeled</span> well by a sine curve and is subtracted for further analysis of short term variations. Temporary <span class="hlt">velocity</span> reductions occur at the time of ground shaking usually caused by earthquakes and are followed by a recovery. We present an empirical <span class="hlt">model</span> that describes the seismic <span class="hlt">velocity</span> variations based on continuous observations of the local ground acceleration. Our hypothesis is that not only the shaking of earthquakes provokes <span class="hlt">velocity</span> drops, but any small vibrations continuously induce minor <span class="hlt">velocity</span> variations that are immediately compensated by healing in the steady state. We show that the shaking effect is accumulated over time and best described by</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhyA..392.3563P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhyA..392.3563P"><span id="translatedtitle">A new car-following <span class="hlt">model</span> with the consideration of anticipation optimal <span class="hlt">velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Guang-han; Cheng, Rong-jun</p> <p>2013-09-01</p> <p>In this paper, a new anticipation optimal <span class="hlt">velocity</span> <span class="hlt">model</span> (AOVM) is proposed by considering anticipation effect on the basis of the full <span class="hlt">velocity</span> difference <span class="hlt">model</span> (FVDM) for car-following theory on single lane. The linear stability condition is derived from linear stability analysis. Starting and braking process is investigated for the car motion under a traffic signal, which shows that the results accord with empirical traffic values. Especially AOVM can avoid the disadvantage of the unrealistically high deceleration appearing in FVDM. Furthermore, numerical simulation shows that AOVM might avoid the disadvantage of negative <span class="hlt">velocity</span> and headway that occur at small sensitivity coefficients in the FVDM since the anticipation effect is taken into account in AOVM, which means that collision disappears with the consideration of an appropriate anticipation parameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CNSNS..18.1027J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CNSNS..18.1027J"><span id="translatedtitle">Stabilization of traffic flow in optimal <span class="hlt">velocity</span> <span class="hlt">model</span> via delayed-feedback control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Yanfei; Hu, Haiyan</p> <p>2013-04-01</p> <p>Traffic jams may occur due to various reasons, such as traffic accidents, lane reductions and on-ramps. In order to suppress the traffic congestion in an optimal <span class="hlt">velocity</span> traffic <span class="hlt">model</span> without any driver's delay taken into account, a delayed-feedback control of both displacement and <span class="hlt">velocity</span> differences is proposed in this study. By using the delay-independent stability criteria and the H∞-norm, the delayed-feedback control can be determined to stabilize the unstable traffic flow and suppress the traffic jam. The numerical case studies are given to demonstrate and verify the new control method. Furthermore, a comparison is made between the new control method and the method proposed by Konishi et al. [K. Konishi, M. Hirai, H. Kokame, Decentralized delayed-feedback control of an optimal <span class="hlt">velocity</span> traffic <span class="hlt">model</span>, Eur. Phys. J. B 15 (2000) 715-722]. The results show that the new control method makes the traffic flow more stable and improves the control performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeoRL..30.1153B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeoRL..30.1153B"><span id="translatedtitle">Upper mantle P <span class="hlt">velocity</span> structure beneath the Baikal Rift from <span class="hlt">modeling</span> regional seismic data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brazier, Richard A.; Nyblade, Andrew A.</p> <p>2003-02-01</p> <p>Uppermost mantle P wave <span class="hlt">velocity</span> structure beneath the Baikal rift and southern margin of the Siberian Platform has been investigated by using a grid search method to <span class="hlt">model</span> Pnl waveforms from two moderate earthquakes recorded by station TLY at the southwestern end of Lake Baikal. The results yielded a limited number of successful <span class="hlt">models</span> which indicate the presence of upper mantle P wave <span class="hlt">velocities</span> beneath the rift axis and the margin of the platform that are 2-5% lower than expected. The magnitude of the <span class="hlt">velocity</span> anomalies and their location support the presence of a thermal anomaly that extends laterally beyond the rift proper, possibly created by small-scale convection or a plume-like, thermal upwelling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.T41E..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.T41E..06B"><span id="translatedtitle"><span class="hlt">Models</span> of Seismic <span class="hlt">Velocity</span> and Anisotropy For the Great Basin, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beghein, C.</p> <p>2010-12-01</p> <p>The Great Basin, which lies in the northern Basin and Range Province in the western United States, has a complex deformation history and is currently characterized by significant crustal extension. The region is marked by a semi-circular shear-wave splitting pattern around a weak azimuthal anisotropy zone in central Nevada. This observation led to various interpretations, including the presence of an upwelling, toroidal mantle flow around a slab, and lithospheric drip. Recent research, however, showed that a similar signal of anisotropy can be found in Rayleigh wave phase <span class="hlt">velocity</span> maps at periods of 16 s and 18 s around a region of locally reduced phase <span class="hlt">velocities</span> (Beghein, et al., EPSL, 2010). Since surface waves at these periods mostly sample the crust, this suggests that at least part of the observed shear-wave splitting pattern has a crustal origin. In the present study, we employ a forward <span class="hlt">modeling</span> approach to <span class="hlt">model</span> the three-dimensional (3-D) variations in shear-wave <span class="hlt">velocities</span> and azimuthal anisotropy in this area. We first use a fully non-linear forward <span class="hlt">modeling</span> approach based on the Neighbourhood Algorithm (Sambridge, 1999) to <span class="hlt">model</span> the isotropic <span class="hlt">velocity</span> variations. This method enables us to quantitatively assess parameter trade-offs and uncertainties. We use prior constraints for the Moho depth based on receiver function results (Miller and Levander, 2009), but we allow it vary by up to 3%. Our results display uniform S-wave <span class="hlt">velocities</span> of 3.6 km/s in the crust with a standard deviation of ~0.3 km/s. We also find the presence of a mantle lid of ~45 km thickness, with S-wave <span class="hlt">velocities</span> up to 4.9 km/s (+/- 0.2 km/s). The posterior Moho depth roughly follows the prior <span class="hlt">model</span>, and we find that the locally thicker crust located in the southwestern part of the region is sufficient to explain the reduction in phase <span class="hlt">velocities</span> seen at short periods at the center of the circular anisotropy pattern. <span class="hlt">Velocities</span> are lower down to at least 100 km depth with Vs=3.9 km</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S21A2380L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S21A2380L"><span id="translatedtitle">Isotropic and anisotropic shear <span class="hlt">velocity</span> <span class="hlt">model</span> of the NA upper mantle using EarthScope data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leiva, J.; Clouzet, P.; French, S. W.; Yuan, H.; Romanowicz, B. A.</p> <p>2013-12-01</p> <p>The EarthScope TA deployment has provided dense array coverage across the continental US and with it, the opportunity for high resolution 3D seismic <span class="hlt">velocity</span> imaging of both lithosphere and asthenosphere in the continent. Building upon our previous work, we present a new 3D isotropic, radially and azimuthally anisotropic shear wave <span class="hlt">model</span> of the North American (NA) lithospheric mantle, using full waveform tomography and shorter-period (40 s) waveform data. Our isotropic <span class="hlt">velocity</span> <span class="hlt">model</span> exhibits pronounced spatial correlation between major tectonic localities of the eastern NA continent, as evidenced in the geology, and seismic anomalies, suggesting recurring episodes of tectonic events not only are well exposed at the surface, but also leave persistent scars in the continental lithosphere mantle, marked by isotropic and radially anisotropic <span class="hlt">velocity</span> anomalies that reach as deep as 100-150 km. In eastern North America, our Vs images distinguish the fast <span class="hlt">velocity</span> cratonic NA from the deep rooted large volume high <span class="hlt">velocity</span> blocks which are east of the continent rift margin and extend 200-300 km offshore into Atlantic. In between is a prominent narrow band of low <span class="hlt">velocities</span> that roughly follows the south and eastern Laurentia rift margin and extends into New England. The lithosphere associated with this low <span class="hlt">velocity</span> band is thinned likely due to combined effects of repeated rifting processes along the rift margin and northward extension of the Bermuda low-<span class="hlt">velocity</span> channel across the New England region. Deep rooted high <span class="hlt">velocity</span> blocks east of the Laurentia margin are proposed to represent the Proterozoic Gondwanian terranes of pan-African affinity, which were captured during the Rodinia formation but left behind during the opening of the Atlantic Ocean. The anisotropy <span class="hlt">model</span> takes advantage of the up-to-date SKS compilation in the continent and new splitting results from Greenland. The new joint waveform and SKS splitting data inversion is carried out with a 2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22340019','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22340019"><span id="translatedtitle"><span class="hlt">Absolute</span> properties of the eclipsing binary system AQ Serpentis: A stringent test of convective core overshooting in stellar evolution <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Torres, Guillermo; Vaz, Luiz Paulo R.; Sandberg Lacy, Claud H.; Claret, Antonio E-mail: lpv@fisica.ufmg.br E-mail: claret@iaa.es</p> <p>2014-02-01</p> <p>We report differential photometric observations and radial-<span class="hlt">velocity</span> measurements of the detached, 1.69 day period, double-lined eclipsing binary AQ Ser. Accurate masses and radii for the components are determined to better than 1.8% and 1.1%, respectively, and are M {sub 1} = 1.417 ± 0.021 M {sub ☉}, M {sub 2} = 1.346 ± 0.024 M {sub ☉}, R {sub 1} = 2.451 ± 0.027 R {sub ☉}, and R {sub 2} = 2.281 ± 0.014 R {sub ☉}. The temperatures are 6340 ± 100 K (spectral type F6) and 6430 ± 100 K (F5), respectively. Both stars are considerably evolved, such that predictions from stellar evolution theory are particularly sensitive to the degree of extra mixing above the convective core (overshoot). The component masses are different enough to exclude a location in the H-R diagram past the point of central hydrogen exhaustion, which implies the need for extra mixing. Moreover, we find that current main-sequence <span class="hlt">models</span> are unable to match the observed properties at a single age even when allowing the unknown metallicity, mixing length parameter, and convective overshooting parameter to vary freely and independently for the two components. The age of the more massive star appears systematically younger. AQ Ser and other similarly evolved eclipsing binaries showing the same discrepancy highlight an outstanding and largely overlooked problem with the description of overshooting in current stellar theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S53A2401K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S53A2401K"><span id="translatedtitle">Comparison of P-, SV- and SH-wave <span class="hlt">velocity</span> <span class="hlt">models</span> below Japan and northeast China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kawakatsu, H.; Schardong, L.; Takeuchi, N.; Tanaka, S.; Obayashi, M.; Chen, Y. J.; Ning, J.; Niu, F.; Grand, S. P.; Ni, J.</p> <p>2013-12-01</p> <p>The recent deployment of the NECESSArray seismic network in northeast China has allowed new insights on the <span class="hlt">velocity</span> structure of this formerly poorly resolved area. This experiment has brought new data to debate about the geodynamical context in this region (stagnant slab, origin of intraplate volcanism, etc...). We use an efficient method for the measurement of travel time residuals by cross-correlating observed and synthetic waveforms. Synthetic seismograms are convolved with high-frequency source-time functions inverted along with focal depths, following a simulated annealing approach. Thus, resulting <span class="hlt">modeled</span> waveforms take more accurately account for the source effects. The method is used to perform measurements on direct P, SV and SH phases extracted from, respectively, vertical, radial and transverse band-pass-filtered records from NECESSArray and F-NET seismological networks. We finally invert the resulting datasets in order to obtain P-, SV- and SH-wave <span class="hlt">velocity</span> <span class="hlt">models</span>. To do so, we use a fast and efficient inversion method using ray theory. Observed structures in the three tomographic <span class="hlt">models</span> show a very good geographical coherency. Nevertheless, some differences are observed below Songliao basin and Changbaishan volcano between P and SV <span class="hlt">models</span> and SH <span class="hlt">model</span>. By measuring <span class="hlt">velocity</span> ratios, we discuss anisotropy and thermal/compositional origin of these <span class="hlt">velocity</span> anomalies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4753566','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4753566"><span id="translatedtitle">An Empirical <span class="hlt">Model</span> of Human Aspiration in Low-<span class="hlt">Velocity</span> Air Using CFD Investigations</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Anthony, T. Renée; Anderson, Kimberly R.</p> <p>2016-01-01</p> <p>Computational fluid dynamics (CFD) <span class="hlt">modeling</span> was performed to investigate the aspiration efficiency of the human head in low <span class="hlt">velocities</span> to examine whether the current inhaled particulate mass (IPM) sampling criterion matches the aspiration efficiency of an inhaling human in airflows common to worker exposures. Data from both mouth and nose inhalation, averaged to assess omnidirectional aspiration efficiencies, were compiled and used to generate a unifying <span class="hlt">model</span> to relate particle size to aspiration efficiency of the human head. Multiple linear regression was used to generate an empirical <span class="hlt">model</span> to estimate human aspiration efficiency and included particle size as well as breathing and freestream <span class="hlt">velocities</span> as dependent variables. A new set of simulated mouth and nose breathing aspiration efficiencies was generated and used to test the fit of empirical <span class="hlt">models</span>. Further, empirical relationships between test conditions and CFD estimates of aspiration were compared to experimental data from mannequin studies, including both calm-air and ultra-low <span class="hlt">velocity</span> experiments. While a linear relationship between particle size and aspiration is reported in calm air studies, the CFD simulations identified a more reasonable fit using the square of particle aerodynamic diameter, which better addressed the shape of the efficiency curve’s decline toward zero for large particles. The ultimate goal of this work was to develop an empirical <span class="hlt">model</span> that incorporates real-world variations in critical factors associated with particle aspiration to inform low-<span class="hlt">velocity</span> modifications to the inhalable particle sampling criterion. PMID:25438035</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70014159','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70014159"><span id="translatedtitle">Crustal <span class="hlt">velocities</span> near Coalinga, California, <span class="hlt">modeled</span> from a combined earthquake/explosion refraction profile</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Macgregor-Scott, N.; Walter, A.</p> <p>1988-01-01</p> <p>Crustal <span class="hlt">velocity</span> structure for the region near Coalinga, California, has been derived from both earthquake and explosion seismic phase data recorded along a NW-SE seismic-refraction profile on the western flank of the Great Valley east of the Diablo Range. Comparison of the two data sets reveals P-wave phases in common which can be correlated with changes in the <span class="hlt">velocity</span> structure below the earthquake hypocenters. In addition, the earthquake records reveal secondary phases at station ranges of less than 20 km that could be the result of S- to P-wave conversions at <span class="hlt">velocity</span> interfaces above the earthquake hypocenters. Two-dimensional ray-trace <span class="hlt">modeling</span> of the P-wave travel times resulted in a P-wave <span class="hlt">velocity</span> <span class="hlt">model</span> for the western flank of the Great Valley comprised of: 1) a 7- to 9-km thick section of sedimentary strata with <span class="hlt">velocities</span> similar to those found elsewhere in the Great Valley (1.6 to 5.2 km s-1); 2) a middle crust extending to about 14 km depth with <span class="hlt">velocities</span> comparable to those reported for the Franciscan assemblage in the Diablo Range (5.6 to 5.9 km s-1); and 3) a 13- to 14-km thick lower crust with <span class="hlt">velocities</span> similar to those reported beneath the Diablo Range and the Great Valley (6.5 to 7.30 km s-1). This lower crust may have been derived from subducted oceanic crust that was thickened by accretionary underplating or crustal shortening. -Authors</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70029117','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70029117"><span id="translatedtitle">Forearc structure beneath southwestern British Columbia: A three-dimensional tomographic <span class="hlt">velocity</span> <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ramachandran, K.; Dosso, S.E.; Spence, G.D.; Hyndman, R.D.; Brocher, T.M.</p> <p>2005-01-01</p> <p>This paper presents a three-dimensional compressional wave <span class="hlt">velocity</span> <span class="hlt">model</span> of the forearc crust and upper mantle and the subducting Juan de Fuca plate beneath southwestern British Columbia and the adjoining straits of Georgia and Juan de Fuca. The <span class="hlt">velocity</span> <span class="hlt">model</span> was constructed through joint tomographic inversion of 50,000 first-arrival times from earthquakes and active seismic sources. Wrangellia rocks of the accreted Paleozoic and Mesozoic island arc assemblage underlying southern Vancouver Island in the Cascadia forearc are imaged at some locations with higher than average lower crustal <span class="hlt">velocities</span> of 6.5-7.2 km/s, similar to observations at other island arc terranes. The mafic Eocene Crescent terrane, thrust landward beneath southern Vancouver Island, exhibits crustal <span class="hlt">velocities</span> in the range of 6.0-6.7 km/s and is inferred to extend to a depth of more than 20 km. The Cenozoic Olympic Subduction Complex, an accretionary prism thrust beneath the Crescent terrane in the Olympic Peninsula, is imaged as a low-<span class="hlt">velocity</span> wedge to depths of at least 20 km. Three zones with <span class="hlt">velocities</span> of 7.0-7.5 km/s, inferred to be mafic and/or ultramafic units, lie above the subducting Juan de Fuca plate at depths of 25-35 km. The forearc upper mantle wedge beneath southeastern Vancouver Island and the Strait of Georgia exhibits low <span class="hlt">velocities</span> of 7.2-7.5 km/s, inferred to correspond to ???20% serpentinization of mantle peridotites, and consistent with similar observations in other warm subduction zones. Estimated dip of the Juan de Fuca plate beneath southern Vancouver Island is ???11??, 16??, and 27?? at depths of 30, 40, and 50 km, respectively. Copyright 2005 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvA..94a3808D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvA..94a3808D&link_type=ABSTRACT"><span id="translatedtitle">Optomechanics for <span class="hlt">absolute</span> rotation detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Davuluri, Sankar</p> <p>2016-07-01</p> <p>In this article, we present an application of optomechanical cavity for the <span class="hlt">absolute</span> rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular <span class="hlt">velocity</span> of <span class="hlt">absolute</span> rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25935367','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25935367"><span id="translatedtitle">Microthrix parvicella abundance associates with activated sludge settling <span class="hlt">velocity</span> and rheology - Quantifying and <span class="hlt">modelling</span> filamentous bulking.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wágner, Dorottya S; Ramin, Elham; Szabo, Peter; Dechesne, Arnaud; Plósz, Benedek Gy</p> <p>2015-07-01</p> <p>The objective of this work is to identify relevant settling <span class="hlt">velocity</span> and rheology <span class="hlt">model</span> parameters and to assess the underlying filamentous microbial community characteristics that can influence the solids mixing and transport in secondary settling tanks. Parameter values for hindered, transient and compression settling <span class="hlt">velocity</span> functions were estimated by carrying out biweekly batch settling tests using a novel column setup through a four-month long measurement campaign. To estimate viscosity <span class="hlt">model</span> parameters, rheological experiments were carried out on the same sludge sample using a rotational viscometer. Quantitative fluorescence in-situ hybridisation (qFISH) analysis, targeting Microthrix parvicella and phylum Chloroflexi, was used. This study finds that M. parvicella - predominantly residing inside the microbial flocs in our samples - can significantly influence secondary settling through altering the hindered settling <span class="hlt">velocity</span> and yield stress parameter. Strikingly, this is not the case for Chloroflexi, occurring in more than double the abundance of M. parvicella, and forming filaments primarily protruding from the flocs. The transient and compression settling parameters show a comparably high variability, and no significant association with filamentous abundance. A two-dimensional, axi-symmetrical computational fluid dynamics (CFD) <span class="hlt">model</span> was used to assess calibration scenarios to <span class="hlt">model</span> filamentous bulking. Our results suggest that <span class="hlt">model</span> predictions can significantly benefit from explicitly accounting for filamentous bulking by calibrating the hindered settling <span class="hlt">velocity</span> function. Furthermore, accounting for the transient and compression settling <span class="hlt">velocity</span> in the computational domain is crucial to improve <span class="hlt">model</span> accuracy when <span class="hlt">modelling</span> filamentous bulking. However, the case-specific calibration of transient and compression settling parameters as well as yield stress is not necessary, and an average parameter set - obtained under bulking and good settling</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.6492V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.6492V"><span id="translatedtitle">Minimum 1D P- and S- <span class="hlt">Velocity</span> <span class="hlt">Models</span> for Montenegro and Vicinity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vucic, Ljiljana; Kissling, Edi; Spakman, Wim; Glavatovic, Branislav</p> <p>2015-04-01</p> <p>The territory of Montenegro and its vicinity are characterized by high-seismicity rate and very complex tectonics. Namely, southern Adria microplate subducts beneath Eurasia, forming the Dinarides fold-and-thrust belt which spreads through whole Montenegro and the western Balkans. Present-day lithosphere structure of the Adria-Dinarides collision zone in general is not constrained very well and, consequently, there is a lack of three-dimensional (3D) <span class="hlt">velocity</span> <span class="hlt">models</span> in this region. For these reasons, high resolution 3D tomography <span class="hlt">modeling</span> of this area is considered to be of great importance. As part of preparatory phase for conducting a 3D local earthquake tomography study, a substantial amount of waveform data was collected, from all surroundings national seismic networks including 130 seismic stations from 11 countries. The data set comprises waveforms from 1452 earthquakes in the region recorded during time period 1990 - 2014. The collected data were obtained in different formats and the data base was harmonized by converting and integrating all data to miniseed format. The potential resolution of collected data for seismic tomography purpose was analyzed by ray density testing, using specially developed software for this specific purpose. The result is expressed as the number of rays between selected group of earthquake hypocenters and seismic stations, penetrating through the 3D <span class="hlt">model</span> of the Earth crust and it documents the great potential of the data set for 3D seismic tomography. As a prerequisite to 3D tomography and for consistent high-precision earthquake locations, a minimum 1D <span class="hlt">velocity</span> <span class="hlt">model</span> has been calculated. The data set of around 400 earthquakes was selected from the main database and consistent wave onsets picking was performed, including seismic phase interpretation and its quality assessment. This highly consistent travel time data set is used for calculation of 1D <span class="hlt">velocity</span> <span class="hlt">models</span> for the region under study. The minimum 1D <span class="hlt">models</span> were derived</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008APS..DPPUP6124B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008APS..DPPUP6124B&link_type=ABSTRACT"><span id="translatedtitle">A <span class="hlt">velocity</span>-dependent anomalous radial transport <span class="hlt">model</span> for (2-D, 2-V) kinetic transport codes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bodi, Kowsik; Krasheninnikov, Sergei; Cohen, Ron; Rognlien, Tom</p> <p>2008-11-01</p> <p>Plasma turbulence constitutes a significant part of radial plasma transport in magnetically confined plasmas. This turbulent transport is <span class="hlt">modeled</span> in the form of anomalous convection and diffusion coefficients in fluid transport codes. There is a need to <span class="hlt">model</span> the same in continuum kinetic edge codes [such as the (2-D, 2-V) transport version of TEMPEST, NEO, and the code being developed by the Edge Simulation Laboratory] with non-Maxwellian distributions. We present an anomalous transport <span class="hlt">model</span> with <span class="hlt">velocity</span>-dependent convection and diffusion coefficients leading to a diagonal transport matrix similar to that used in contemporary fluid transport <span class="hlt">models</span> (e.g., UEDGE). Also presented are results of simulations corresponding to radial transport due to long-wavelength ExB turbulence using a <span class="hlt">velocity</span>-independent diffusion coefficient. A BGK collision <span class="hlt">model</span> is used to enable comparison with fluid transport codes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=henry+AND+constants&pg=2&id=EJ834115','ERIC'); return false;" href="http://eric.ed.gov/?q=henry+AND+constants&pg=2&id=EJ834115"><span id="translatedtitle">Evaluation of an Imputed Pitch <span class="hlt">Velocity</span> <span class="hlt">Model</span> of the Auditory Kappa Effect</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Henry, Molly J.; McAuley, J. Devin</p> <p>2009-01-01</p> <p>Three experiments evaluated an imputed pitch <span class="hlt">velocity</span> <span class="hlt">model</span> of the auditory kappa effect. Listeners heard 3-tone sequences and judged the timing of the middle (target) tone relative to the timing of the 1st and 3rd (bounding) tones. Experiment 1 held pitch constant but varied the time (T) interval between bounding tones (T = 728, 1,000, or 1,600…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226130','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226130"><span id="translatedtitle"><span class="hlt">Modeling</span> the Coupled Effects of Pore Space Geometry and <span class="hlt">Velocity</span> on Colloid Transport and Retention</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Recent experimental and theoretical work has demonstrated that pore space geometry and hydrodynamics can play an important role in colloid retention under unfavorable attachment conditions. Computer <span class="hlt">models</span> that only consider the average pore-water <span class="hlt">velocity</span> and a single attachment rate coefficient a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=63596&keyword=aermod&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=64097486&CFTOKEN=28794751','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=63596&keyword=aermod&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50&CFID=64097486&CFTOKEN=28794751"><span id="translatedtitle">USING METEOROLOGICAL <span class="hlt">MODEL</span> OUTPUT AS A SURROGATE FOR ON-SITE OBSERVATIONS TO PREDICT DEPOSITION <span class="hlt">VELOCITY</span></span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The National Oceanic and Atmospheric Administration's Multi-Layer <span class="hlt">Model</span> (NOAA-MLM) is used by several operational dry deposition networks for estimating the deposition <span class="hlt">velocity</span> of O , SO , HNO , and particles. The NOAA-MLM requires hourly values of meteorological variables and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/sir/2008/5219/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/sir/2008/5219/"><span id="translatedtitle"><span class="hlt">Models</span> for Gas Hydrate-Bearing Sediments Inferred from Hydraulic Permeability and Elastic <span class="hlt">Velocities</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lee, Myung W.</p> <p>2008-01-01</p> <p>Elastic <span class="hlt">velocities</span> and hydraulic permeability of gas hydrate-bearing sediments strongly depend on how gas hydrate accumulates in pore spaces and various gas hydrate accumulation <span class="hlt">models</span> are proposed to predict physical property changes due to gas hydrate concentrations. Elastic <span class="hlt">velocities</span> and permeability predicted from a cementation <span class="hlt">model</span> differ noticeably from those from a pore-filling <span class="hlt">model</span>. A nuclear magnetic resonance (NMR) log provides in-situ water-filled porosity and hydraulic permeability of gas hydrate-bearing sediments. To test the two competing <span class="hlt">models</span>, the NMR log along with conventional logs such as <span class="hlt">velocity</span> and resistivity logs acquired at the Mallik 5L-38 well, Mackenzie Delta, Canada, were analyzed. When the clay content is less than about 12 percent, the NMR porosity is 'accurate' and the gas hydrate concentrations from the NMR log are comparable to those estimated from an electrical resistivity log. The variation of elastic <span class="hlt">velocities</span> and relative permeability with respect to the gas hydrate concentration indicates that the dominant effect of gas hydrate in the pore space is the pore-filling characteristic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050000840&hterms=spatiotemporal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dspatiotemporal','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050000840&hterms=spatiotemporal&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dspatiotemporal"><span id="translatedtitle"><span class="hlt">Modeling</span> the spatiotemporal organization of <span class="hlt">velocity</span> storage in the vestibuloocular reflex by optokinetic studies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raphan, T.; Sturm, D.; Cohen, B. (Principal Investigator)</p> <p>1991-01-01</p> <p>1. A generalized three-dimensional state space <span class="hlt">model</span> of visual vestibular interaction was developed. Matrix and dynamical system operators associated with inputs from the semicircular canals, otolith <span class="hlt">velocity</span> estimator, and the visual system have been incorporated into the <span class="hlt">model</span>, which focus on their relationship to the <span class="hlt">velocity</span> storage integrator. 2. A relationship was postulated between the eigenvalues and the direction of the eigenvectors of the system matrix and the orientation of the spatial vertical. It was assumed that the system matrix for a tilted position was a composition of two linear transformations of the system matrix for the upright position. One transformation modifies the eigenvalues of the system matrix, whereas another rotates the eigenvectors of the system matrix. The pitch and roll eigenvectors rotate with the head, whereas the yaw axis eigenvector remains approximately spatially invariant. 3. Based on the three-dimensional <span class="hlt">model</span>, a computational procedure was formulated to identify the eigenvalues and eigenvectors of the system matrix with the use of a modification of the marquardt algorithm. With the use of data obtained from a monkey, it was shown that the three-dimensional behavior of <span class="hlt">velocity</span> storage cannot be predicted solely in terms of its time constants, i.e., the inverse of its eigenvalues. With the use of the same eigenvalues the data could either be fit or not fit, depending on the eigenvector directions. Therefore, it is necessary to specify eigenvector directions when characterizing <span class="hlt">velocity</span> storage in three dimensions. 4. Parameters found with the use of the Marquardt algorithm were incorporated into the <span class="hlt">model</span>. Diagonal matrices in a head coordinate frame were introduced for coupling the visual system to the integrator and to the direct optokinetic pathway. Simulations of optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) were run. The <span class="hlt">model</span> predicted the behavior of yaw and pitch OKN and OKAN when the animal is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27.4285F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27.4285F"><span id="translatedtitle">Rayleigh Wave Dispersion and A 1d S-<span class="hlt">velocity</span> <span class="hlt">Model</span> of The Fennoscandian Mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Funke, S.; Friederich, W.; Sstwg, The</p> <p></p> <p>We derive a Rayleigh wave dispersion curve from surface wave data recorded at the SVEKALAPKO tomographic array deployed in Southern Finland from September 1998 to March 1999. After a suite of processing steps, complex spectral amplitudes of the Rayleigh wave train are determined for each available seismogram. The process- ing includes low-pass filtering, instrument correction, deconvolution using a standard earth <span class="hlt">model</span> to compress the Rayleigh wave train, computation of Gabor matrices (sonograms) to pick group travel times, and finally estimation of complex spectral amplitudes in a Gaussian time window of frequency-dependent width centered on the group travel time. Spectral amplitude values are only accepted if the signal-to-noise ratio in the considered frequency interval is above a pre-chosen threshold and if the picked group travel time does not deviate too strongly from that predicted by a stan- dard earth <span class="hlt">model</span>. The final dataset contains spectral amplitude values at 34 selected periods from 52 earthquakes observed at on average 25 stations. For each selected frequency, we determine a phase <span class="hlt">velocity</span> by fitting plane waves propagating across the array with this <span class="hlt">velocity</span> to the complex spectral amplitudes of all earthquakes and stations. Errors are estimated with a bootstrap method. We obtain reliable phase <span class="hlt">velocities</span> in the frequency band from 8 mHz to 50 mHz. Phase veloci- ties for lower frequencies exhibit large errors due to the lack of big earthquakes during the time of deployment. The phase <span class="hlt">velocities</span> are substantially higher than predicted by standard earth <span class="hlt">model</span> ak135 below 20 mHz and slightly lower above 25 mHz. We have inverted the dispersion curve for a 1D shear wave <span class="hlt">velocity</span> <span class="hlt">model</span> down to about 400 km depth and obtain a 50 km thick crust and a fast upper mantle with a sub- Moho <span class="hlt">velocity</span> of 4.7 km/s. Our data do not require a low-<span class="hlt">velocity</span> zone in the upper mantle. Indeed, the dispersion curve can be explained by a nearly straight <span class="hlt">velocity</span> profile from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhRvE..75b7301G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhRvE..75b7301G"><span id="translatedtitle"><span class="hlt">Absolute</span> instability of a viscous hollow jet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gañán-Calvo, Alfonso M.</p> <p>2007-02-01</p> <p>An investigation of the spatiotemporal stability of hollow jets in unbounded coflowing liquids, using a general dispersion relation previously derived, shows them to be <span class="hlt">absolutely</span> unstable for all physical values of the Reynolds and Weber numbers. The roots of the symmetry breakdown with respect to the liquid jet case, and the validity of asymptotic <span class="hlt">models</span> are here studied in detail. Asymptotic analyses for low and high Reynolds numbers are provided, showing that old and well-established limiting dispersion relations [J. W. S. Rayleigh, The Theory of Sound (Dover, New York, 1945); S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability (Dover, New York, 1961)] should be used with caution. In the creeping flow limit, the analysis shows that, if the hollow jet is filled with any finite density and viscosity fluid, a steady jet could be made arbitrarily small (compatible with the continuum hypothesis) if the coflowing liquid moves faster than a critical <span class="hlt">velocity</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S33C2800G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S33C2800G"><span id="translatedtitle">UCVM: An Open Source Software Package for Querying and Visualizing 3D <span class="hlt">Velocity</span> <span class="hlt">Models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gill, D.; Small, P.; Maechling, P. J.; Jordan, T. H.; Shaw, J. H.; Plesch, A.; Chen, P.; Lee, E. J.; Taborda, R.; Olsen, K. B.; Callaghan, S.</p> <p>2015-12-01</p> <p>Three-dimensional (3D) seismic <span class="hlt">velocity</span> <span class="hlt">models</span> provide foundational data for ground motion simulations that calculate the propagation of earthquake waves through the Earth. The Southern California Earthquake Center (SCEC) has developed the Unified Community <span class="hlt">Velocity</span> <span class="hlt">Model</span> (UCVM) package for both Linux and OS X. This unique framework provides a cohesive way for querying and visualizing 3D <span class="hlt">models</span>. UCVM v14.3.0, supports many Southern California <span class="hlt">velocity</span> <span class="hlt">models</span> including CVM-S4, CVM-H 11.9.1, and CVM-S4.26. The last <span class="hlt">model</span> was derived from 26 full-3D tomographic iterations on CVM-S4. Recently, UCVM has been used to deliver a prototype of a new 3D <span class="hlt">model</span> of central California (CCA) also based on full-3D tomographic inversions. UCVM was used to provide initial plots of this <span class="hlt">model</span> and will be used to deliver CCA to users when the <span class="hlt">model</span> is publicly released. Visualizing <span class="hlt">models</span> is also possible with UCVM. Integrated within the platform are plotting utilities that can generate 2D cross-sections, horizontal slices, and basin depth maps. UCVM can also export <span class="hlt">models</span> in NetCDF format for easy import into IDV and ParaView. UCVM has also been prototyped to export <span class="hlt">models</span> that are compatible with IRIS' new Earth <span class="hlt">Model</span> Collaboration (EMC) visualization utility. This capability allows for user-specified horizontal slices and cross-sections to be plotted in the same 3D Earth space. UCVM was designed to help a wide variety of researchers. It is currently being use to generate <span class="hlt">velocity</span> meshes for many SCEC wave propagation codes, including AWP-ODC-SGT and Hercules. It is also used to provide the initial input to SCEC's CyberShake platform. For those interested in specific data points, the software framework makes it easy to extract P and S wave propagation speeds and other material properties from 3D <span class="hlt">velocity</span> <span class="hlt">models</span> by providing a common interface through which researchers can query earth <span class="hlt">models</span> for a given location and depth. Also included in the last release was the ability to add small</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70021432','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70021432"><span id="translatedtitle">Elastic-wave <span class="hlt">velocity</span> in marine sediments with gas hydrates: Effective medium <span class="hlt">modeling</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Helgerud, M.B.; Dvorkin, J.; Nur, A.; Sakai, A.; Collett, T.</p> <p>1999-01-01</p> <p>We offer a first-principle-based effective medium <span class="hlt">model</span> for elastic-wave <span class="hlt">velocity</span> in unconsolidated, high porosity, ocean bottom sediments containing gas hydrate. The dry sediment frame elastic constants depend on porosity, elastic moduli of the solid phase, and effective pressure. Elastic moduli of saturated sediment are calculated from those of the dry frame using Gassmann's equation. To <span class="hlt">model</span> the effect of gas hydrate on sediment elastic moduli we use two separate assumptions: (a) hydrate modifies the pore fluid elastic properties without affecting the frame; (b) hydrate becomes a component of the solid phase, modifying the elasticity of the frame. The goal of the <span class="hlt">modeling</span> is to predict the amount of hydrate in sediments from sonic or seismic <span class="hlt">velocity</span> data. We apply the <span class="hlt">model</span> to sonic and VSP data from ODP Hole 995 and obtain hydrate concentration estimates from assumption (b) consistent with estimates obtained from resistivity, chlorinity and evolved gas data. Copyright 1999 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..SHK.T1004C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..SHK.T1004C"><span id="translatedtitle">Low <span class="hlt">Velocity</span> Impact Experiments plus <span class="hlt">Modeling</span> of the Resulting Reaction Violence in LX-10 Charges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chidester, Steven; Garcia, Frank; Vandersall, Kevin; Tarver, Craig</p> <p>2011-06-01</p> <p>A new gas gun facility and improved instrumentation were used to study the mechanisms of low <span class="hlt">velocity</span> impact ignition and growth of violent reaction. Cylindrical charges of the HMX based explosive LX-10 (95% HMX, 5% Viton binder) encased by lexan were impacted by 6.35 mm diameter hardened steel projectiles at <span class="hlt">velocities</span> ranging from 47 to 500 m/s. Fast Phantom v12 cameras were employed to capture the times of first ignition. The degrees of resulting reaction violence were determined using Photonic Doppler Velocimetry (PDV) probes to measure the free surface <span class="hlt">velocity</span> histories of attached aluminum foils. Analytical and hydrodynamic reactive flow <span class="hlt">models</span> were used to estimate the relative violence of these LX-10 reactions compared to the intentional detonation of an equivalent LX-10 charge. This work was performed under the auspices of the U. S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770013923','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770013923"><span id="translatedtitle">Effects of geometry and jet <span class="hlt">velocity</span> on noise associated with an upper-surface-blowing <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Clark, L. R.; Yu, J. C.</p> <p>1977-01-01</p> <p>The noise characteristics associated with various upper surface blowing configurations were investigated using a small <span class="hlt">model</span> consisting of a plate and flap assembly (simulated wing with flap) attached to a rectangular nozzle. Nozzle aspect ratio, flow-run length, and flap-deflection angle were the experimental parameters studied. Three nozzle-exit <span class="hlt">velocities</span> were used. The normalized noise spectra obtained for different nozzle aspect ratios proved to be similar in terms of Strouhal number based on jet <span class="hlt">velocity</span> and flow-run length. Consequently, the need for knowing local flow <span class="hlt">velocity</span> and length scales (for example, at the flap trailing edge) as required in some of the existing noise prediction schemes is eliminated. Data are compared with results computed from three different noise prediction schemes, and the validity of each scheme is assessed. A simple method is proposed to evaluate the frequency dependence of acoustic shielding obtained with the simulated wing flap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040110412','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040110412"><span id="translatedtitle"><span class="hlt">Velocity</span> Measurements Near the Empennage of a SmallScale Helicopter <span class="hlt">Model</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gorton, Susan Althoff; Meyers, James F.; Berry, John D.</p> <p>1996-01-01</p> <p>A test program was conducted in the NASA Langley 14- by 22-Foot Subsonic Tunnel to measure the flow near the empennage of a small-scale powered helicopter <span class="hlt">model</span> with an operating tail fan. Three-component <span class="hlt">velocity</span> profiles were measured with Laser Velocimetry (LV) one chord forward of the horizontal tail for four advance ratios to evaluate the effect of the rotor wake impingement on the horizontal tail angle of attack. These <span class="hlt">velocity</span> data indicate the horizontal tail can experience unsteady downwash angle variations of over 30 degrees due to the rotor wake influence. The horizontal tail is most affected by the rotor wake above advance ratios of 0.10. <span class="hlt">Velocity</span> measurements of the flow on the inlet side of the fan were made for a low-speed flight condition using both conventional LV techniques and a promising, non-intrusive, global, three-component <span class="hlt">velocity</span> measurement technique called Doppler Global Velocimetry (DGV). The <span class="hlt">velocity</span> data show an accelerated flow near the fan duct, and vorticity calculations track the passage of main rotor wake vortices through the measurement plane. DGV shows promise as an evolving tool for rotor flowfield diagnostics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhFl...10.2012M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhFl...10.2012M"><span id="translatedtitle">Dynamics of <span class="hlt">velocity</span> gradient invariants in turbulence: Restricted Euler and linear diffusion <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martín, Jesús; Dopazo, César; Valiño, Luis</p> <p>1998-08-01</p> <p>A complete system of dynamical equations for the invariants of the <span class="hlt">velocity</span> gradient, the strain rate, and the rate-of-rotation tensors is deduced for an incompressible flow. The equations for the <span class="hlt">velocity</span> gradient invariants R and Q were first deduced by Cantwell [Phys. Fluids A 4, 782 (1992)] in terms of Hij, the tensor containing the anisotropic part of the pressure Hessian and the viscous diffusion term in the <span class="hlt">velocity</span> gradient equation. These equations are extended here for the strain rate tensor invariants, RS and QS, and for the rate-of-rotation tensor invariant, QW, using HijS and HijW, the symmetric and the skew-symmetric parts of Hij, respectively. In order to obtain a complete system, an equation for the square of the vortex stretching vector, Vi≡Sijωj, is required. The resulting dynamical system of invariants is closed using a simple <span class="hlt">model</span> for the <span class="hlt">velocity</span> gradient evolution: an isotropic approximation for the pressure term and a linear <span class="hlt">model</span> for the viscous diffusion term. The local topology and the resulting statistics implied by this <span class="hlt">model</span> reproduce a number of trends similar to known results from numerical experiments for the small scales of turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/401098','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/401098"><span id="translatedtitle">A <span class="hlt">model</span> for the two-point <span class="hlt">velocity</span> correlation function in turbulent channel flow</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sahay, A.; Sreenivasan, K.R.</p> <p>1996-06-01</p> <p>A relatively simple analytical expression is presented to approximate the equal-time, two-point, double-<span class="hlt">velocity</span> correlation function in turbulent channel flow. To assess the accuracy of the <span class="hlt">model</span>, we perform the spectral decomposition of the integral operator having the <span class="hlt">model</span> correlation function as its kernel. Comparisons of the empirical eigenvalues and eigenfunctions with those constructed from direct numerical simulations data show good agreement. {copyright} {ital 1996 American Institute of Physics.}</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005A%26A...444..615H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005A%26A...444..615H"><span id="translatedtitle">High geocentric <span class="hlt">velocity</span> meteor ablation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hill, K. A.; Rogers, L. A.; Hawkes, R. L.</p> <p>2005-12-01</p> <p>Interstellar origin meteoroids have now been detected using radar, image intensified video, large aperture radar and space dust impact techniques. Dynamical and radiation production mechanisms will eject some meteoroids from other planetary systems into orbits which will impact Earth with high geocentric <span class="hlt">velocities</span>. In this paper we numerically <span class="hlt">model</span> the ablation of high geocentric <span class="hlt">velocity</span> (71 to 500~km s-1) meteors in order to predict the heights, light curves and trail lengths to be expected. We <span class="hlt">modeled</span> three compositions and structures: asteroidal, cometary and porous cometary. Meteoroid masses ranging from 10-6 to 10-13~kg were used in the <span class="hlt">model</span>. As expected, these high geocentric <span class="hlt">velocity</span> meteors, when compared to other meteors, ablate higher in the atmosphere. For example a 300~km s-1 cometary structure meteor of mass 10-9~kg will have a peak luminosity at about 190 km. They will also have significantly longer trail lengths. The same 300~km s-1, 10-9~kg cometary meteor would be within 2 mag of its peak brightness for a vertical displacement of 60 km if incident at a zenith angle of 45°. The peak light intensity of these high geocentric <span class="hlt">velocity</span> meteors changes only slowly with <span class="hlt">velocity</span>. Although the incident kinetic energy per unit time increases dramatically, this is largely offset by a decrease in the optical luminous efficiency in this <span class="hlt">velocity</span> regime according to our luminous efficiency <span class="hlt">model</span>. The 300~km s-1, 10-9~kg cometary meteor would have an <span class="hlt">absolute</span> meteor magnitude at peak luminosity of about +8.5 mag. Our results suggest that at least those high geocentric <span class="hlt">velocity</span> meteors larger than about 10-8~kg should be observable with current meteor electro-optical technology although there may be observational biases against their detection. The results of this paper can be used to help optimize a search strategy for these very high geocentric <span class="hlt">velocity</span> meteors.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007JGRB..112.7313T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007JGRB..112.7313T"><span id="translatedtitle">Three-dimensional P wave <span class="hlt">velocity</span> <span class="hlt">model</span> for the San Francisco Bay region, California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thurber, Clifford H.; Brocher, Thomas M.; Zhang, Haijiang; Langenheim, Victoria E.</p> <p>2007-07-01</p> <p>A new three-dimensional P wave <span class="hlt">velocity</span> <span class="hlt">model</span> for the greater San Francisco Bay region has been derived using the double-difference seismic tomography method, using data from about 5,500 chemical explosions or air gun blasts and approximately 6,000 earthquakes. The <span class="hlt">model</span> region covers 140 km NE-SW by 240 km NW-SE, extending from 20 km south of Monterey to Santa Rosa and reaching from the Pacific coast to the edge of the Great Valley. Our <span class="hlt">model</span> provides the first regional view of a number of basement highs that are imaged in the uppermost few kilometers of the <span class="hlt">model</span>, and images a number of <span class="hlt">velocity</span> anomaly lows associated with known Mesozoic and Cenozoic basins in the study area. High <span class="hlt">velocity</span> (Vp > 6.5 km/s) features at ˜15-km depth beneath part of the edge of the Great Valley and along the San Francisco peninsula are interpreted as ophiolite bodies. The relocated earthquakes provide a clear picture of the geometry of the major faults in the region, illuminating fault dips that are generally consistent with previous studies. Ninety-five percent of the earthquakes have depths between 2.3 and 15.2 km, and the corresponding seismic <span class="hlt">velocities</span> at the hypocenters range from 4.8 km/s (presumably corresponding to Franciscan basement or Mesozoic sedimentary rocks of the Great Valley Sequence) to 6.8 km/s. The top of the seismogenic zone is thus largely controlled by basement depth, but the base of the seismogenic zone is not restricted to seismic <span class="hlt">velocities</span> of ≤6.3 km/s in this region, as had been previously proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFM.S23B1388T&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007AGUFM.S23B1388T&link_type=ABSTRACT"><span id="translatedtitle">Development of a State-Wide 3-D Seismic Tomography <span class="hlt">Velocity</span> <span class="hlt">Model</span> for California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thurber, C. H.; Lin, G.; Zhang, H.; Hauksson, E.; Shearer, P.; Waldhauser, F.; Hardebeck, J.; Brocher, T.</p> <p>2007-12-01</p> <p>We report on progress towards the development of a state-wide tomographic <span class="hlt">model</span> of the P-wave <span class="hlt">velocity</span> for the crust and uppermost mantle of California. The dataset combines first arrival times from earthquakes and quarry blasts recorded on regional network stations and travel times of first arrivals from explosions and airguns recorded on profile receivers and network stations. The principal active-source datasets are Geysers-San Pablo Bay, Imperial Valley, Livermore, W. Mojave, Gilroy-Coyote Lake, Shasta region, Great Valley, Morro Bay, Mono Craters-Long Valley, PACE, S. Sierras, LARSE 1 and 2, Loma Prieta, BASIX, San Francisco Peninsula and Parkfield. Our beta-version <span class="hlt">model</span> is coarse (uniform 30 km horizontal and variable vertical gridding) but is able to image the principal features in previous separate regional <span class="hlt">models</span> for northern and southern California, such as the high-<span class="hlt">velocity</span> subducting Gorda Plate, upper to middle crustal <span class="hlt">velocity</span> highs beneath the Sierra Nevada and much of the Coast Ranges, the deep low-<span class="hlt">velocity</span> basins of the Great Valley, Ventura, and Los Angeles, and a high- <span class="hlt">velocity</span> body in the lower crust underlying the Great Valley. The new state-wide <span class="hlt">model</span> has improved areal coverage compared to the previous <span class="hlt">models</span>, and extends to greater depth due to the data at large epicentral distances. We plan a series of steps to improve the <span class="hlt">model</span>. We are enlarging and calibrating the active-source dataset as we obtain additional picks from investigators and perform quality control analyses on the existing and new picks. We will also be adding data from more quarry blasts, mainly in northern California, following an identification and calibration procedure similar to Lin et al. (2006). Composite event construction (Lin et al., in press) will be carried out for northern California for use in conventional tomography. A major contribution of the state-wide <span class="hlt">model</span> is the identification of earthquakes yielding arrival times at both the Northern California Seismic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004AGUFM.S34A..06Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004AGUFM.S34A..06Z&link_type=ABSTRACT"><span id="translatedtitle">Crustal <span class="hlt">Velocity</span> <span class="hlt">Model</span> of Watusi Data Integrated With Legacy Data, Clark County, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaragoza, S. A.; Snelson, C. M.</p> <p>2004-12-01</p> <p>The Las Vegas Valley, Nevada is located in the central Basin and Range Province, about 100 km southeast of the Nevada Test Site (NTS). Las Vegas sits atop a basin up to 5 km deep (Langenheim et al., 2001) that has been shown to amplify energy from strong ground motion (Su et al., 1998). Rapid population growth has led to concerns that future nuclear testing at NTS may pose a hazard from strong ground motion. Studies performed when nuclear testing was ongoing were limited to the central basin and were insufficient to adequately assess ground motion hazard for the entire Valley. In September 2002, 400 single-channel seismic recorders were deployed to record a chemical blast (Watusi) at NTS. Forward <span class="hlt">modeling</span> of these data as well as Legacy data from the 1960s (Prodehl, 1979) produced a 268 km two-dimensional crustal <span class="hlt">velocity</span> <span class="hlt">model</span> from Kingman, Arizona to NTS with higher resolution than the previous <span class="hlt">model</span>. Crustal <span class="hlt">velocities</span> range from 3.5 to 6.2 km/s. <span class="hlt">Velocities</span> at the Moho range from 7.9-8.0 km/s. Crustal depth ranges from 28-29 km near Kingman to 33-34 km near NTS. A structural feature in <span class="hlt">model</span> space at 12-15 km underneath Indian Springs, Nevada appears to focus seismic energy into the Las Vegas basin, and may pose a significant seismic hazard. The feature has a dip in <span class="hlt">model</span> space of 45º toward the southeast. A density <span class="hlt">model</span> was also produced and tied to the <span class="hlt">velocity</span> <span class="hlt">model</span>. The density <span class="hlt">model</span> is consistent with the <span class="hlt">velocity</span> <span class="hlt">model</span>, confirming crustal depth ranges from 28-29 km near Kingman to 33-34 km near NTS. The density <span class="hlt">model</span> also confirms the 45º southeast-dipping structural feature and indicates the location of a mafic body in <span class="hlt">model</span> space at a depth of 5-12 km beneath the Las Vegas Basin. Possible interpretations of the dipping structure include a relict thrust or metamorphic core complex. However, these interpretations are difficult due to the steep dip angle of the feature, and more evidence would be needed to verify one of these conclusions. A more likely</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11798109','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11798109"><span id="translatedtitle">Source apportionment of gaseous atmospheric pollutants by means of an <span class="hlt">absolute</span> principal component scores (APCS) receptor <span class="hlt">model</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bruno, P; Caselli, M; de Gennaro, G; Traini, A</p> <p>2001-12-01</p> <p>A multivariate statistical method has been applied to apportion the atmospheric pollutant concentrations measured by automatic gas analyzers placed on a mobile laboratory for air quality monitoring in Taranto (Italy). In particular, Principal Component Analysis (PCA) followed by <span class="hlt">Absolute</span> Principal Component Scores (APCS) technique was performed to identify the number of emission sources and their contribution to measured concentrations of CO, NOx, benzene toluene m+p-Xylene (BTX). This procedure singled out two different sources that explain about 85% of collected data variance. PMID:11798109</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhLA..375.2377L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhLA..375.2377L"><span id="translatedtitle">Modification of Spalart-Allmaras <span class="hlt">model</span> with consideration of turbulence energy backscatter using <span class="hlt">velocity</span> helicity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Yangwei; Lu, Lipeng; Fang, Le; Gao, Feng</p> <p>2011-06-01</p> <p>The correlation between the <span class="hlt">velocity</span> helicity and the energy backscatter is proved in a DNS case of 256 3-grid homogeneous isotropic decaying turbulence. The helicity is then proposed to be employed to improve turbulence <span class="hlt">models</span> and SGS <span class="hlt">models</span>. Then Spalart-Allmaras turbulence <span class="hlt">model</span> (SA) is modified with the helicity to take account of the energy backscatter, which is significant in the region of corner separation in compressors. By comparing the numerical results with experiments, it can be concluded that the modification for SA <span class="hlt">model</span> with helicity can appropriately represent the energy backscatter, and greatly improves the predictive accuracy for simulating the corner separation flow in compressors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.H24A..08H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFM.H24A..08H&link_type=ABSTRACT"><span id="translatedtitle">Comparative Experimental and <span class="hlt">Modeling</span> Study of Fluid <span class="hlt">Velocities</span> in Heterogeneous Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hingerl, F.; Romanenko, K.; Pini, R.; Balcom, B.; Benson, S. M.</p> <p>2013-12-01</p> <p>Understanding the spatial distribution of fluid <span class="hlt">velocities</span> and effective porosities in rocks is crucial for predicting kinetic reaction rates and fluid-rock interactions in a plethora of geo-engineering applications, ranging from geothermal systems, Enhanced Oil Recovery to Carbon Capture and Storage. Magnetic Resonance Imaging can be used to measure spatially resolved porosities and fluid <span class="hlt">velocities</span> in porous media. Large internal field gradients and short spin relaxation times, however, constrain the usability of the conventional MRI technique in natural rock samples. The combination of three-dimensional Single Point Ramped Imaging with T1 Enhancement (SPRITE) and the 13-interval Alternating-Pulsed-Gradient Stimulated-Echo (APGSTE) scheme - a method developed at the UNB MRI Center - is able to compensate for those challenges and quantitative 3 dimensional maps of porosities and fluid <span class="hlt">velocities</span> can be obtained. In this study we measured <span class="hlt">velocities</span> and porosities using MRI in a sandstone rock sample showing meso-scale heterogeneities. Then we generated permeabilities using three independent approaches, employed them to <span class="hlt">model</span> single-phase fluid flow in the measured rock sample and compared the generated <span class="hlt">velocity</span> maps with the respective MRI measurements. For the first <span class="hlt">modeling</span> approach, we applied the Kozeny-Carman relationship to create a permeability map based on porosities measured using MRI. For the second approach we used permeabilities derived from CO2-H2O multi-phase experiments performed in the same rock sample assuming the validity of the J-Leverett function. The permeabilities in the third approach were generated by applying a new inverse iterative-updating technique. The resulting three permeability maps were then used as input for a CFD simulation - using the Stanford CFD code AD-GPRS - to create a respective <span class="hlt">velocity</span> map, which in turn was then compared to the measured <span class="hlt">velocity</span> map. The results of the different independent methods for generating</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15908257','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15908257"><span id="translatedtitle">A neuromusculoskeletal <span class="hlt">model</span> to simulate the constant angular <span class="hlt">velocity</span> elbow extension test of spasticity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Koo, Terry K K; Mak, Arthur F T</p> <p>2006-01-01</p> <p>We developed a neuromusculoskeletal <span class="hlt">model</span> to simulate the stretch reflex torque induced during a constant angular <span class="hlt">velocity</span> elbow extension by tuning a set of physiologically-based parameters. Our <span class="hlt">model</span> extended past <span class="hlt">modeling</span> efforts in the investigation of elbow spasticity by incorporating explicit musculotendon, muscle spindle, and motoneuron pool <span class="hlt">models</span> in each prime elbow flexor. We analyzed the effects of changes in motoneuron pool and muscle spindle properties as well as muscle mechanical properties on the biomechanical behavior of the elbow joint observed during a constant angular <span class="hlt">velocity</span> elbow extension. Results indicated that both motoneuron pool thresholds and gains could be substantially different among muscles. In addition, sensitivity analysis revealed that spindle static gain and motoneuron pool threshold were the most sensitive parameters that could affect the stretch reflex responses of the elbow flexors during a constant angular <span class="hlt">velocity</span> elbow extension, followed by motoneuron pool gain, and spindle dynamic gain. It is hoped that the <span class="hlt">model</span> will contribute to the understanding of the underlying mechanisms of spasticity after validation by more elaborate experiments, and will facilitate the future development of more specific treatment of spasticity. PMID:15908257</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S43B2079M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S43B2079M"><span id="translatedtitle">Validating 3D Seismic <span class="hlt">Velocity</span> <span class="hlt">Models</span> Using the Spectral Element Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maceira, M.; Rowe, C. A.; Allen, R. M.; Obrebski, M. J.</p> <p>2010-12-01</p> <p>As seismic instrumentation, data storage and dissemination and computational power improve, seismic <span class="hlt">velocity</span> <span class="hlt">models</span> attempt to resolve smaller structures and cover larger areas. However, it is unclear how accurate these <span class="hlt">velocity</span> <span class="hlt">models</span> are and, while the best <span class="hlt">models</span> available are used for event determination, it is difficult to put uncertainties on seismic event parameters. <span class="hlt">Model</span> validation is typically done using resolution tests that assume the imaging theory used is accurate and thus only considers the impact of the data coverage on resolution. We present the results of a more rigorous approach to <span class="hlt">model</span> validation via full three-dimensional waveform propagation using Spectral Element Methods (SEM). This approach makes no assumptions about the theory used to generate the <span class="hlt">models</span> but require substantial computational resources. We first validate 3D tomographic <span class="hlt">models</span> for the Western USA generated using both ray-theoretical and finite-frequency methods. The Dynamic North America (DNA) <span class="hlt">Models</span> of P- and S- <span class="hlt">velocity</span> structure (DNA09-P and DNA09-S) use teleseismic body-wave traveltime residuals recorded at over 800 seismic stations provided by the Earthscope USArray and regional seismic networks. We performed systematic computations of synthetics for the dataset used to generate the DNA <span class="hlt">models</span>. Direct comparison of these synthetic seismograms to the actual observations allows us to accurately assess and validate the <span class="hlt">models</span>. Implementation of the method for a densely instrumented region such as that covered by the DNA <span class="hlt">model</span> provides a useful testbed for the validation methods that we will subsequently apply to other, more challenging study areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AdWR...85...45W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AdWR...85...45W&link_type=ABSTRACT"><span id="translatedtitle">A comparison of measured and <span class="hlt">modeled</span> <span class="hlt">velocity</span> fields for a laminar flow in a porous medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wood, B. D.; Apte, S. V.; Liburdy, J. A.; Ziazi, R. M.; He, X.; Finn, J. R.; Patil, V. A.</p> <p>2015-11-01</p> <p>Obtaining highly-resolved <span class="hlt">velocity</span> data from experimental measurements in porous media is a significant challenge. The goal of this work is to compare the <span class="hlt">velocity</span> fields measured in a randomly-packed porous medium obtained from particle image velocimetry (PIV) with corresponding fields predicted from direct numerical simulation (DNS). Experimentally, the porous medium was comprised of 15 mm diameter spherical beads made of optical glass placed in a glass flow cell to create the packed bed. A solution of ammonium thiocyanate was refractive-index matched to the glass creating a medium that could be illuminated with a laser sheet without distortion. The bead center locations were quantified using the imaging system so that the geometry of the porous medium was known very accurately. Two-dimensional PIV data were collected and processed to provide high-resolution <span class="hlt">velocity</span> fields at a single plane within the porous medium. A Cartesian-grid-based fictitious domain approach was adopted for the direct numerical simulation of flow through the same geometry as the experimental measurements and without any adjustable parameters. The uncertainties associated with characterization of the pore geometry, PIV measurements, and DNS predictions were all systematically quantified. Although uncertainties in bead position measurements led to minor discrepancies in the comparison of the <span class="hlt">velocity</span> fields, the axial and normal <span class="hlt">velocity</span> deviations exhibited normalized root mean squared deviations (NRMSD) of only 11.32% and 4.74%, respectively. The high fidelity of both the experimental and numerical methods have significant implications for understanding and even for engineering the micro-macro relationship in porous materials. The ability to measure and <span class="hlt">model</span> sub-pore-scale flow features also has relevance to the development of upscaled <span class="hlt">models</span> for flow in porous media, where physically reasonable closure <span class="hlt">models</span> must be developed at the sub-pore scale. These results provide valuable data</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JSeis..17..683M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSeis..17..683M"><span id="translatedtitle">Shear wave <span class="hlt">velocity</span> <span class="hlt">models</span> retrieved using Rg wave dispersion data in shallow crust in some regions of southern Ontario, Canada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Shutian; Motazedian, Dariush; Corchete, Victor</p> <p>2013-04-01</p> <p>Many crucial tasks in seismology, such as locating seismic events and estimating focal mechanisms, need crustal <span class="hlt">velocity</span> <span class="hlt">models</span>. The <span class="hlt">velocity</span> <span class="hlt">models</span> of shallow structures are particularly important in the simulation of ground motions. In southern Ontario, Canada, many small shallow earthquakes occur, generating high-frequency Rayleigh ( Rg) waves that are sensitive to shallow structures. In this research, the dispersion of Rg waves was used to obtain shear-wave <span class="hlt">velocities</span> in the top few kilometers of the crust in the Georgian Bay, Sudbury, and Thunder Bay areas of southern Ontario. Several shallow <span class="hlt">velocity</span> <span class="hlt">models</span> were obtained based on the dispersion of recorded Rg waves. The Rg waves generated by an m N 3.0 natural earthquake on the northern shore of Georgian Bay were used to obtain <span class="hlt">velocity</span> <span class="hlt">models</span> for the area of an earthquake swarm in 2007. The Rg waves generated by a mining induced event in the Sudbury area in 2005 were used to retrieve <span class="hlt">velocity</span> <span class="hlt">models</span> between Georgian Bay and the Ottawa River. The Rg waves generated by the largest event in a natural earthquake swarm near Thunder Bay in 2008 were used to obtain a <span class="hlt">velocity</span> <span class="hlt">model</span> in that swarm area. The basic feature of all the investigated <span class="hlt">models</span> is that there is a top low-<span class="hlt">velocity</span> layer with a thickness of about 0.5 km. The seismic <span class="hlt">velocities</span> changed mainly within the top 2 km, where small earthquakes often occur.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/7860829','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/7860829"><span id="translatedtitle"><span class="hlt">Modeling</span> the glottal volume-<span class="hlt">velocity</span> waveform for three voice types.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Childers, D G; Ahn, C</p> <p>1995-01-01</p> <p>The purpose of this study was to <span class="hlt">model</span> features of the glottal volume-<span class="hlt">velocity</span> waveform for three voice types: modal voice, vocal fry, and breathy voice. The study analyzed data measured from two sustained vowels and one sentence uttered by nine adult, male subjects who represented examples of the three voice types. The primary analysis procedure was glottal inverse filtering, which estimated the glottal volume-<span class="hlt">velocity</span> waveform. The estimated glottal volume-<span class="hlt">velocity</span> waveform was then fit to an LF <span class="hlt">model</span> waveform. Four parameters of the LF <span class="hlt">model</span> were adjusted to minimize the mean-squared error between the estimated glottal waveform and the LF <span class="hlt">model</span> waveform. Statistical averages and standard deviations of the four parameters of the LF glottal waveform <span class="hlt">model</span> were calculated using the data for each voice type. The four LF <span class="hlt">model</span> parameters characterize important low-frequency features of the glottal waveform, namely, the glottal pulse width, pulse skewness, abruptness of closure of the glottal pulse, and the spectral tilt of the glottal pulse. Statistical analysis included ANOVA and multiple linear regression analysis. The ANOVA results demonstrated that there was a difference in three of the four LF <span class="hlt">model</span> parameters for the three voice types. The linear regression analysis between the four LF <span class="hlt">model</span> parameters and a formal rating by a listening test of the quality of the three voice types was used to determine the most significant LF <span class="hlt">model</span> parameters for each voice type. A simple rule was devised for synthesizing the three voice types with a formant synthesizer using the LF glottal waveform <span class="hlt">model</span>. Listener evaluations of the synthesized speech tended to confirm the results determined by the analysis procedures. PMID:7860829</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210625K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210625K"><span id="translatedtitle">3-D crustal <span class="hlt">velocity</span> <span class="hlt">model</span> for Lithuania and its application to local event studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kozlovskaya, Elena; Budraitis, Mantas; Janutyte, Ilma; Motuza, Gediminas; Lazauskiene, Jurga; Passeq-Working Group</p> <p>2010-05-01</p> <p>PASSEQ 2006-2008 project (PASsive Seismic Experiment in TESZ) aimed at studying the lithosphere-asthenosphere system around the TransEuropean Suture Zone (TESZ)- the transition between old Proterozoic platform of north and east Europe and younger Phanerozoic platform in central and western Europe. The experiment was a seismic array research aiming to retrieve the structure of the crust and Earth's mantle down to the mantle transition zone, including mapping of upper mantle seismic <span class="hlt">velocity</span> variations and discontinuities (Moho, lithosphere-asthenosphere boundary, mantle transition zone) using all available techniques. During the experiment 26 seismic stations (including four broadband stations) were installed in Lithuania. One of the main targets of PASSEQ deployment in Lithuania was identification and characterization of the local seismic activity. The PASSEQ stations in Lithuania were in operation since June, 2006 till January, 2008. During this period a number of local seismic events was recorded and preliminary event location was made using the LocSat algorithm and 1-D <span class="hlt">velocity</span> <span class="hlt">model</span>. This standard procedure is not enough precise for Lithuania, however, because the thickness of the crust varies significantly in the region (from 45 to 55 km). In order to improve event location, we separated the events into several groups and located each group separately using a VELEST algorithms and own 1-D <span class="hlt">velocity</span> <span class="hlt">model</span> for each group. We also compiled a 3-D seismic <span class="hlt">velocity</span> of the crust down to a depth of 60 km. The <span class="hlt">model</span>, consisting of four major layers (sediments, upper crust, middle crust, lower crust and uppermost mantle) was interpolated from 2-D <span class="hlt">velocity</span> <span class="hlt">models</span> along previous wide-angle reflection and refraction profiles into a regular grid. The quality of the approximation was analysed using comparison of travel times of P-waves recorded along previous controlled source profiles and synthetic travel times calculated using the 3-D <span class="hlt">velocity</span> <span class="hlt">model</span>. The <span class="hlt">model</span> was converted</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S43B2082S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S43B2082S"><span id="translatedtitle">SCEC CVM-Toolkit (CVM-T) -- High Performance Meshing Tools for SCEC Community <span class="hlt">Velocity</span> <span class="hlt">Models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Small, P.; Maechling, P. J.; Ely, G. P.; Olsen, K. B.; Withers, K.; Graves, R. W.; Jordan, T. H.; Plesch, A.; Shaw, J. H.</p> <p>2010-12-01</p> <p>The SCEC Community <span class="hlt">Velocity</span> <span class="hlt">Model</span> Toolkit (CVM-T) enables earthquake <span class="hlt">modelers</span> to quickly build, visualize, and validate large-scale 3D <span class="hlt">velocity</span> meshes using SCEC CVM-H or CVM-4. CVM-T is comprised of three main components: (1) a current SCEC community <span class="hlt">velocity</span> <span class="hlt">model</span> for Southern California, (2) tools for extracting meshes from this <span class="hlt">model</span> and visualizing them, and (3) an automated test framework for evaluating new releases of CVMs using SCEC’s AWP-ODC forward wave propagation software and one, or more, ground motion goodness of fit (GoF) algorithms. CVM-T is designed to help SCEC <span class="hlt">modelers</span> build large-scale <span class="hlt">velocity</span> meshes by extracting material properties from the most current version of Community <span class="hlt">Velocity</span> <span class="hlt">Model</span> H (CVM-H) and to provide a consistent interface as new CVM-H versions are developed. The CVM-T software provides a highly-scalable interface to CVM-H 6.2 (and later) voxets. Along with an improved interface to CVM-H material properties, the CVM-T software adds a geotechnical layer (GTL) to CVM-H 6.2+ based on Ely’s Vs30-derived GTL. The initial release of CVM-T also extends the coverage region for CVM-H 6.2 with a Hadley-Kanamori 1D background. Smoothing is performed within the transition boundary between the core <span class="hlt">model</span> and the 1D background. The user interface now includes a C API that allows applications to query the <span class="hlt">model</span> either by elevation or depth. The Extraction and Visualization Tools (EVT) include a parallelized 3D mesh generator which can quickly generate meshes (consisting of Vp, Vs, and density) from either CVM-H or CVM-4 with over 100 billion points. Python plotting scripts can be employed to plot horizontal or profile slices from existing meshes or directly from either CVM. The Automated Test Framework (ATF) is a system for quantitatively evaluating new versions of CVM-H and ensuring that the <span class="hlt">model</span> improves against prior versions. The ATF employs the CruiseControl build and test framework to run an AWP-ODC simulation for the 2008 Chino</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.T51A4590F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.T51A4590F"><span id="translatedtitle">Detailed <span class="hlt">Velocity</span> and Density <span class="hlt">models</span> of the Cascadia Subduction Zone from Prestack Full-Waveform Inversion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fortin, W.; Holbrook, W. S.; Mallick, S.; Everson, E. D.; Tobin, H. J.; Keranen, K. M.</p> <p>2014-12-01</p> <p>Understanding the geologic composition of the Cascadia Subduction Zone (CSZ) is critically important in assessing seismic hazards in the Pacific Northwest. Despite being a potential earthquake and tsunami threat to millions of people, key details of the structure and fault mechanisms remain poorly understood in the CSZ. In particular, the position and character of the subduction interface remains elusive due to its relative aseismicity and low seismic reflectivity, making imaging difficult for both passive and active source methods. Modern active-source reflection seismic data acquired as part of the COAST project in 2012 provide an opportunity to study the transition from the Cascadia basin, across the deformation front, and into the accretionary prism. Coupled with advances in seismic inversion methods, this new data allow us to produce detailed <span class="hlt">velocity</span> <span class="hlt">models</span> of the CSZ and accurate pre-stack depth migrations for studying geologic structure. While still computationally expensive, current computing clusters can perform seismic inversions at resolutions that match that of the seismic image itself. Here we present pre-stack full waveform inversions of the central seismic line of the COAST survey offshore Washington state. The resultant <span class="hlt">velocity</span> <span class="hlt">model</span> is produced by inversion at every CMP location, 6.25 m laterally, with vertical resolution of 0.2 times the dominant seismic frequency. We report a good average correlation value above 0.8 across the entire seismic line, determined by comparing synthetic gathers to the real pre-stack gathers. These detailed <span class="hlt">velocity</span> <span class="hlt">models</span>, both Vp and Vs, along with the density <span class="hlt">model</span>, are a necessary step toward a detailed porosity cross section to be used to determine the role of fluids in the CSZ. Additionally, the P-<span class="hlt">velocity</span> <span class="hlt">model</span> is used to produce a pre-stack depth migration image of the CSZ.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990040215','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990040215"><span id="translatedtitle">Towards a Rational <span class="hlt">Model</span> for the Triple <span class="hlt">Velocity</span> Correlations of Turbulence</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Younis, B. A.; Gatski, T. B.; Speziale, C. G.</p> <p>1999-01-01</p> <p>This paper presents a rational approach to <span class="hlt">modelling</span> the triple <span class="hlt">velocity</span> correlations that appear in the transport equations for the Reynolds stresses. All existing <span class="hlt">models</span> of these correlations have largely been formulated on phenomenological grounds and are defective in one important aspect: they all neglect to allow for the dependence of these correlations on the local gradients of mean <span class="hlt">velocity</span>. The mathematical necessity for this dependence will be demonstrated in the paper. The present contribution lies in the novel use of Group Representation Theory to determine the most general tensorial form of these correlations in terms of all the second- and third-order tensor quantities that appear in the exact equations that govern their evolution. The requisite representation did not exist in the literature and therefore had to be developed specifically for this purpose by Professor G. F. Smith. The outcome of this work is a mathematical framework for the construction of algebraic, explicit, and rational <span class="hlt">models</span> for the triple <span class="hlt">velocity</span> correlations that are theoretically consistent and include all the correct dependencies. Previous <span class="hlt">models</span> are reviewed, and all are shown to be an incomplete subset of this new representation, even to lowest order.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..DFD.QB009M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DFD.QB009M"><span id="translatedtitle">Bayesian Assessment of Mean <span class="hlt">Velocity</span> Profile <span class="hlt">Models</span> in Wall-Bounded Turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moser, Robert; Oliver, Todd</p> <p>2010-11-01</p> <p>The form of the mean <span class="hlt">velocity</span> profile in high-Reynolds-number wall-bounded turbulent shear flows has been the subject of renewed interest in recent years. A number of questions have been raised regarding the universality of the von Karman constant, the dependence of the over-lap layer on Reynolds number and even the appropriateness of a logarithmic description of the overlap layer. The questions have been difficult to resolve because the <span class="hlt">models</span> predict subtle differences in the mean <span class="hlt">velocity</span> profiles at finite Reynolds number. However, these subtle differences are important for scaling to very high Reynolds number and for inferring wall shear stress when direct measurements are not available. In this work, Bayesian inference is used to infer parameters (e.g. the Karman constant) and their uncertainty in a variety of turbulent mean <span class="hlt">velocity</span> representations using experimental data over a wide range of Reynolds number. Moreover, an information theory-based multi-<span class="hlt">model</span> formalism is used to rank competing <span class="hlt">models</span> (e.g., the standard log and power laws and finite Reynolds number refinements of these profiles) by a metric that naturally balances data fit versus <span class="hlt">model</span> complexity. This work is supported by the Department of Energy [National Nuclear Security Administration] under Award Number [DE-FC52-08NA28615].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/14654','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/14654"><span id="translatedtitle">Complete regional waveform <span class="hlt">modeling</span> to estimate seismic <span class="hlt">velocity</span> structure and source parameters for CTBT monitoring</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bredbeck, T; Rodgers, A; Walter, W</p> <p>1999-07-23</p> <p>The <span class="hlt">velocity</span> structures and source parameters estimated by waveform <span class="hlt">modeling</span> provide valuable information for CTBT monitoring. The inferred crustal and uppermost mantle structures advance understanding of tectonics and guides regionalization for event location and identification efforts. Estimation of source parameters such as seismic moment, depth and mechanism (whether earthquake, explosion or collapse) is crucial to event identification. In this paper we briefly outline some of the waveform <span class="hlt">modeling</span> research for CTBT monitoring performed in the last year. In the future we will estimate structure for new regions by <span class="hlt">modeling</span> waveforms of large well-observed events along additional paths. Of particular interest will be the estimation of <span class="hlt">velocity</span> structure in aseismic regions such as most of Africa and the Former Soviet Union. Our previous work on aseismic regions in the Middle East, north Africa and south Asia give us confidence to proceed with our current methods. Using the inferred <span class="hlt">velocity</span> <span class="hlt">models</span> we plan to estimate source parameters for smaller events. It is especially important to obtain seismic moments of earthquakes for use in applying the Magnitude-Distance Amplitude Correction (MDAC; Taylor et al., 1999) to regional body-wave amplitudes for discrimination and calibrating the coda-based magnitude scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JGR...10420237G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JGR...10420237G"><span id="translatedtitle">Three-dimensional <span class="hlt">models</span> of P wave <span class="hlt">velocity</span> and P-to-S <span class="hlt">velocity</span> ratio in the southern central Andes by simultaneous inversion of local earthquake data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graeber, Frank M.; Asch, Günter</p> <p>1999-09-01</p> <p>The PISCO'94 (Proyecto de Investigatión Sismológica de la Cordillera Occidental, 1994) seismological network of 31 digital broad band and short-period three-component seismometers was deployed in northern Chile between the Coastal Cordillera and the Western Cordillera. More than 5300 local seismic events were observed in a 100 day period. A subset of high-quality P and S arrival time data was used to invert simultaneously for hypocenters and <span class="hlt">velocity</span> structure. Additional data from two other networks in the region could be included. The <span class="hlt">velocity</span> <span class="hlt">models</span> show a number of prominent anomalies, outlining an extremely thickened crust (about 70 km) beneath the forearc region, an anomalous crustal structure beneath the recent magmatic arc (Western Cordillera) characterized by very low <span class="hlt">velocities</span>, and a high-<span class="hlt">velocity</span> slab. A region of an increased Vp/Vs ratio has been found directly above the Wadati-Benioff zone, which might be caused by hydration processes. A zone of lower than average <span class="hlt">velocities</span> and a high Vp/Vs ratio might correspond to the asthenospheric wedge. The upper edge of the Wadati-Benioff zone is sharply defined by intermediate depth hypocenters, while evidence for a double seismic zone can hardly be seen. Crustal events between the Precordillera and the Western Cordillera have been observed for the first time and are mainly located in the vicinity of the Salar de Atacama down to depths of about 40 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JGRB..121.2521B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016JGRB..121.2521B&link_type=ABSTRACT"><span id="translatedtitle">Assessing waveform predictions of recent three-dimensional <span class="hlt">velocity</span> <span class="hlt">models</span> of the Tibetan Plateau</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bao, Xueyang; Shen, Yang</p> <p>2016-04-01</p> <p>Accurate <span class="hlt">velocity</span> <span class="hlt">models</span> are essential for both the determination of earthquake locations and source moments and the interpretation of Earth structures. With the increasing number of three-dimensional <span class="hlt">velocity</span> <span class="hlt">models</span>, it has become necessary to assess the <span class="hlt">models</span> for accuracy in predicting seismic observations. Six <span class="hlt">models</span> of the crustal and uppermost mantle structures in Tibet and surrounding regions are investigated in this study. Regional Rayleigh and Pn (or Pnl) waveforms from two ground truth events, including one nuclear explosion and one natural earthquake located in the study area, are simulated by using a three-dimensional finite-difference method. Synthetics are compared to observed waveforms in multiple period bands of 20-75 s for Rayleigh waves and 1-20 s for Pn/Pnl waves. The <span class="hlt">models</span> are evaluated based on the phase delays and cross-correlation coefficients between synthetic and observed waveforms. A <span class="hlt">model</span> generated from full-wave ambient noise tomography best predicts Rayleigh waves throughout the data set, as well as Pn/Pnl waves traveling from the Tarim Basin to the stations located in central Tibet. In general, the <span class="hlt">models</span> constructed from P wave tomography are not well suited to predict Rayleigh waves, and vice versa. Possible causes of the differences between observed and synthetic waveforms, and frequency-dependent variations of the "best matching" <span class="hlt">models</span> with the smallest prediction errors are discussed. This study suggests that simultaneous prediction for body and surface waves requires an integrated <span class="hlt">velocity</span> <span class="hlt">model</span> constructed with multiple seismic waveforms and consideration of other important properties, such as anisotropy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21452679','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21452679"><span id="translatedtitle"><span class="hlt">MODELING</span> HIGH-<span class="hlt">VELOCITY</span> QSO ABSORBERS WITH PHOTOIONIZED MAGNETOHYDRODYNAMIC DISK WINDS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fukumura, Keigo; Kazanas, Demosthenes; Behar, Ehud</p> <p>2010-11-10</p> <p>We extend our <span class="hlt">modeling</span> of the ionization structure of magnetohydrodynamic (MHD) accretion-disk winds, previously applied to Seyfert galaxies, to a population of quasi-stellar objects (QSOs) of much lower X-ray-to-UV flux ratios, i.e., smaller {alpha}{sub ox} index, motivated by UV/X-ray ionized absorbers with extremely high outflow <span class="hlt">velocities</span> in UV-luminous QSOs. We demonstrate that magnetically driven winds ionized by a spectrum with {alpha}{sub ox} {approx_equal} -2 can produce the charge states responsible for C IV and Fe XXV/Fe XXVI absorption in wind regions with corresponding maximum <span class="hlt">velocities</span> of v(C IV) {approx_lt}0.1c and v(Fe XXV) {approx_lt} 0.6c (where c is the speed of light) and column densities N {sub H} {approx} 10{sup 23}-10{sup 24} cm{sup -2}, in general agreement with observations. In contrast to the conventional radiation-driven wind <span class="hlt">models</span>, high-<span class="hlt">velocity</span> flows are always present in our MHD-driven winds but manifest in the absorption spectra only for {alpha}{sub ox} {approx_lt} -2, as larger {alpha}{sub ox} values ionize the wind completely out to radii too large to demonstrate the presence of these high <span class="hlt">velocities</span>. We thus predict increasing <span class="hlt">velocities</span> of these ionized absorbers with decreasing (steeper) {alpha}{sub ox}, a quantity that emerges as the defining parameter in the kinematics of the active galactic nucleus UV/X-ray absorbers.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3515595','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3515595"><span id="translatedtitle">A Microscopic “Social Norm” <span class="hlt">Model</span> to Obtain Realistic Macroscopic <span class="hlt">Velocity</span> and Density Pedestrian Distributions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zanlungo, Francesco; Ikeda, Tetsushi; Kanda, Takayuki</p> <p>2012-01-01</p> <p>We propose a way to introduce in microscopic pedestrian <span class="hlt">models</span> a “social norm” in collision avoiding and overtaking, i.e. the tendency, shared by pedestrians belonging to the same culture, to avoid collisions and perform overtaking in a preferred direction. The “social norm” is implemented, regardless of the specific collision avoiding <span class="hlt">model</span>, as a rotation in the perceived <span class="hlt">velocity</span> vector of the opponent at the moment of computation of the collision avoiding strategy, and justified as an expectation that the opponent will follow the same “social norm” (for example a tendency to avoid on the left and overtake on the right, as proposed in this work for Japanese pedestrians). By comparing with real world data, we show that the introduction of this norm allows for a better reproduction of macroscopic pedestrian density and <span class="hlt">velocity</span> patterns. PMID:23227202</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AIPC.1233..656F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010AIPC.1233..656F&link_type=ABSTRACT"><span id="translatedtitle">Numerical <span class="hlt">Modelling</span> of Glass Fibre Reinforced Laminates Subjected to a Low <span class="hlt">Velocity</span> Impact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fan, J. Y.; Guana, Z. W.; Cantwell, W. J.</p> <p>2010-05-01</p> <p>This paper presents a series of numerical predictions of the perforation behaviour of glass fibre laminates subjected to quasi-static and low-<span class="hlt">velocity</span> impact loading. Both shear and tensile failure criteria were used in the finite element <span class="hlt">models</span> to simulate the post-failure processes via an automatic element removal procedure. The appropriate material properties, obtained through a series of uniaxial tension and bending tests on the composites, were used in the numerical <span class="hlt">models</span>. Four, eight and sixteen ply glass fibre laminates panels were perforated at quasi-static rates and under low-<span class="hlt">velocity</span> impact loading. Reasonably good correlation was obtained between the numerical simulations and the experimental results, both in terms of the failure modes and the load-deflection relationships before and during the penetration phase. The predicted impact energies of the GFRP panels were compared with the experimental data and reasonable agreement was observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3048061','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3048061"><span id="translatedtitle"><span class="hlt">Model</span>-Based Inference of Cognitive Processes from Unobtrusive Gait <span class="hlt">Velocity</span> Measurements</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Austin, Daniel.; Leen, Todd; Hayes, Tamara L.; Kaye, Jeff; Jimison, Holly; Pavel, Misha</p> <p>2011-01-01</p> <p>In this paper we describe a preliminary <span class="hlt">modeling</span> and analysis of a unique data set comprising unobtrusive and continuous measurements of gait <span class="hlt">velocity</span> in the elder participants' residences. The data have been collected as a part of a longitudinal study aimed at early detection of cognitive decline. We motivate these analyses by first presenting evidence that suggests significant relationship between gait parameters and cognitive functions. We then describe a simple, <span class="hlt">model</span>-based approach to the analysis of gait <span class="hlt">velocity</span> using a weighted correlation function estimates. One of the main challenges is due to the fact that the daily estimates of the gait parameters vary with the number of walks. We illustrate the importance of using weighted as opposed to unweighted estimates on a sample of different houses. The correlation functions appear to capture behavioral differences that can be related to the cognitive functioning of the participants. PMID:21096044</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991A%26A...245...57M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991A%26A...245...57M"><span id="translatedtitle">The age-metallicity-<span class="hlt">velocity</span> dispersion relation in the solar neighborhood and a simple evolution <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meusinger, H.; Stecklum, B.; Reimann, H.-G.</p> <p>1991-05-01</p> <p>An analysis of the age-metallicity relation (AMR) based on previous data is conducted again and the age-<span class="hlt">velocity</span> relation (AVR) is estimated for some nearby stars to examine connections between the relations. In the period of evolution of the galactic disk, an important relationship with age is determined for both AMR and AVR. The observed metallicity-<span class="hlt">velocity</span> relation is compared to the predicted relation to verify the AVR and AMR derivations. A <span class="hlt">model</span> is presented in which the star formation rate, the infall rate of gas, and the initial mass function are constant. The <span class="hlt">model</span> is found to agree with observed constraints on star counts in the solar neighborhood and constraints on the chemical and kinematical evolution of the local disk. A theory regarding the primary heating mechanism of the galactic disk is developed in terms of the AVR, and possible explanations - massive gas clouds and transient spiral waves - are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NJPh...18d3040N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NJPh...18d3040N"><span id="translatedtitle">Quantitative explanation of circuit experiments and real traffic using the optimal <span class="hlt">velocity</span> <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakayama, Akihiro; Kikuchi, Macoto; Shibata, Akihiro; Sugiyama, Yuki; Tadaki, Shin-ichi; Yukawa, Satoshi</p> <p>2016-04-01</p> <p>We have experimentally confirmed that the occurrence of a traffic jam is a dynamical phase transition (Tadaki et al 2013 New J. Phys. 15 103034, Sugiyama et al 2008 New J. Phys. 10 033001). In this study, we investigate whether the optimal <span class="hlt">velocity</span> (OV) <span class="hlt">model</span> can quantitatively explain the results of experiments. The occurrence and non-occurrence of jammed flow in our experiments agree with the predictions of the OV <span class="hlt">model</span>. We also propose a scaling rule for the parameters of the <span class="hlt">model</span>. Using this rule, we obtain critical density as a function of a single parameter. The obtained critical density is consistent with the observed values for highway traffic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920003055','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920003055"><span id="translatedtitle"><span class="hlt">Velocity</span> and pressure characteristics of a <span class="hlt">model</span> SSME high pressure fuel turbopump</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tse, D. G-N.; Sabnis, J. S.; Mcdonald, H.</p> <p>1991-01-01</p> <p>Under the present effort an experiment rig has been constructed, an instrumentation package developed and a series of mean and rms <span class="hlt">velocity</span> and pressure measurements made in a turbopump which <span class="hlt">modelled</span> the first stage of the Space Shuttle Main Engine (SSME) High Pressure Fuel Turbopump. The rig was designed so as to allow initial experiments with a single configuration consisting of a bell-mouth inlet, a flight impeller, a vaneless diffuser and a volute. Allowance was made for components such as inlet guide vanes, exit guide vanes, downstream pumps, etc. to be added in future experiments. This flexibility will provide a clear baseline set of experiments and allow evaluation in later experiments of the effect of adding specific components upon the pump performance properties. The rotational speed of the impeller was varied between 4260 and 7680 rpm which covered the range of scaled SSME rotation speeds when due allowance is made for the differing stagnation temperature, <span class="hlt">model</span> to full scale. The results at the inlet obtained with rotational speeds of 4260, 6084 and 7680 rpm showed that the axial <span class="hlt">velocity</span> at the bell-mouth inlet remained roughly constant at 2.2 of the bulk <span class="hlt">velocity</span> at the exit of the turbopump near the center of the inlet, but it decreased rapidly with increasing radius at all three speeds. Reverse flow occurred at a radius greater than 0.9 R for all three speeds and the maximum negative <span class="hlt">velocity</span> reduced from 1.3 of the bulk <span class="hlt">velocity</span> at the exit of the turbopump at 4260 rpm to 0.35 at 7680 rpm, suggesting that operating at a speed closer to the design condition of 8700 rpm improved the inlet characteristics. The reverse flow caused positive prerotation at the impeller inlet which was negligibly small near the center but reached 0.7 of the impeller speed at the outer annulus. The results in the diffuser and the volute obtained at 7680 rpm show that the hub and shroud walls of the diffuser were characterized by regions of transient reverse flow with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAESc..79..173P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAESc..79..173P"><span id="translatedtitle">Crustal <span class="hlt">velocity</span> structure beneath Saurashtra, NW India, through waveform <span class="hlt">modeling</span>: Implications for magmatic underplating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Praveen Kumar, K. A.; Mohan, G.</p> <p>2014-01-01</p> <p>The Saurashtra peninsula in the northwestern segment of the Deccan volcanic province of India, is characterized by several high gravity and magnetic anomalies, which correspond to mafic crustal intrusions. This study attempts to quantify the alterations to the crust caused by the Deccan volcanism, by estimating the crustal Poisson's ratio, shear wave <span class="hlt">velocity</span> (Vs) structure and the shear <span class="hlt">velocity</span> contrast across the Moho, through teleseismic waveform <span class="hlt">modeling</span>. The P receiver functions (RFs) for six broadband seismic stations were constructed using about 575 high quality (S/N ≥ 2.5) teleseismic waveforms of earthquakes (M ≥ 5.5) recorded during the period 2004-2010. The moveout corrected RF summation stacks were inverted using the Neighborhood algorithm (NA) to estimate the shear <span class="hlt">velocity</span> structure beneath each station. The crustal thickness is estimated to range from 38 km in western Saurashtra to 33 km close to the southern extension of the Cambay rift. A low <span class="hlt">velocity</span> zone possibly corresponding to sub-basaltic sediments is detected beneath all the stations. The average crustal Vs and Poisson's ratio are estimated to be 3.68 km/s and 0.276 respectively. The crustal Poisson's ratio indicates an intermediate to mafic composition for the crust. <span class="hlt">Modeling</span> reveals a relatively high <span class="hlt">velocity</span> lower crust with an average Vs ≈ 3.88 ± 0.1 km/s which is consistent with the high Vp ≈ 7.1 km/s reported for this region through seismic refraction and wide angle reflection studies, overlying a relatively low <span class="hlt">velocity</span> (Vs ≈ 4.4 ± 0.1 km/s) upper mantle. The shear <span class="hlt">velocity</span> contrasts across the Moho, derived from the amplitudes of the P-to-s (Pms) conversions from the Moho range from 0.08 to 0.17 which are much smaller than those (>0.20) observed across the Indian shield, implying a gradational Moho due to underplating. This study reveals that the crust beneath Saurashtra is distinctly different from that of the Archean Indian shield largely due to significant alterations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21116079','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21116079"><span id="translatedtitle">A dynamic <span class="hlt">model</span> for the turbulent burning <span class="hlt">velocity</span> for large eddy simulation of premixed combustion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Knudsen, E.; Pitsch, H.</p> <p>2008-09-15</p> <p>Turbulent premixed combustion is particularly difficult to describe using large eddy simulation (LES). In LES, premixed flame structures typically exist on subfilter length scales. Consequently, premixed LES <span class="hlt">models</span> must be capable of describing how completely unresolved flame structures propagate under the influence of completely unresolved eddies. This description is usually accomplished through the implementation of a <span class="hlt">model</span> for the turbulent burning <span class="hlt">velocity</span>. Here, a dynamic <span class="hlt">model</span> for describing the turbulent burning <span class="hlt">velocity</span> in the context of LES is presented. This <span class="hlt">model</span> uses a new surface filtering procedure that is consistent with standard LES filtering. Additionally, it only uses information that comes directly from the flame front. This latter attribute is important for two reasons. First, it guarantees that the <span class="hlt">model</span> can be consistently applied when level set methods, where arbitrary constraints can be imposed on field variables away from fronts, are used to track the flame. Second, it forces the <span class="hlt">model</span> to recognize that the physics governing flame front propagation are only valid locally at the front. Results showing <span class="hlt">model</span> validation in the context of direct numerical simulation (DNS), and <span class="hlt">model</span> application in the context of LES, are presented. (author)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121..818G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121..818G"><span id="translatedtitle">A reconciliation of empirical and mechanistic <span class="hlt">models</span> of the air-sea gas transfer <span class="hlt">velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goddijn-Murphy, Lonneke; Woolf, David K.; Callaghan, Adrian H.; Nightingale, Philip D.; Shutler, Jamie D.</p> <p>2016-01-01</p> <p><span class="hlt">Models</span> of the air-sea transfer <span class="hlt">velocity</span> of gases may be either empirical or mechanistic. Extrapolations of empirical <span class="hlt">models</span> to an unmeasured gas or to another water temperature can be erroneous if the basis of that extrapolation is flawed. This issue is readily demonstrated for the most well-known empirical gas transfer <span class="hlt">velocity</span> <span class="hlt">models</span> where the influence of bubble-mediated transfer, which can vary between gases, is not explicitly accounted for. Mechanistic <span class="hlt">models</span> are hindered by an incomplete knowledge of the mechanisms of air-sea gas transfer. We describe a hybrid <span class="hlt">model</span> that incorporates a simple mechanistic view—strictly enforcing a distinction between direct and bubble-mediated transfer—but also uses parameterizations based on data from eddy flux measurements of dimethyl sulphide (DMS) to calibrate the <span class="hlt">model</span> together with dual tracer results to evaluate the <span class="hlt">model</span>. This <span class="hlt">model</span> underpins simple algorithms that can be easily applied within schemes to calculate local, regional, or global air-sea fluxes of gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H13C0962M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H13C0962M"><span id="translatedtitle">A Stochastic Non-Gaussian <span class="hlt">Velocity</span> <span class="hlt">Model</span> for Tracer Dispersion in Heterogeneous Porous Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meyer, D. W.; Tchelepi, H. A.</p> <p>2009-12-01</p> <p>To <span class="hlt">model</span> tracer transport in porous media, computationally expensive Monte Carlo (MC) techniques or low-order approximation methods (LOAM) are applicable [1]. The latter are inexpensive but limited to relatively homogeneous media with low conductivity or transmissivity variations, and approximately Gaussian one-point <span class="hlt">velocity</span> statistics. MC studies have shown that heterogeneous media lead to distinctly skewed non-Gaussian <span class="hlt">velocity</span> distributions [2]. In addition to MC and LOAM, continuous time random walk (CTRW) or Lévy motion (LM) approaches were proposed for the <span class="hlt">modeling</span> of dispersion in highly heterogeneous media, e.g, fractured rock [3,4]. Both <span class="hlt">models</span> involve discontinuous stochastic processes for the displacement of tracer particles. The parameters that determine these processes, however, are not always easy to identify. In this work, a new particle-based <span class="hlt">model</span> for the simulation of tracer dispersion in homogeneous and heterogeneous porous media is presented. Other than in CTRW or LM <span class="hlt">models</span>, a continuous stochastic process for the Lagrangian <span class="hlt">velocity</span> of a tracer particle is formulated. The suggested formulation encompasses Gaussian and skewed <span class="hlt">velocity</span> statistics, and the <span class="hlt">model</span> parameters can be related more easily to medium characteristics. Numerical simulations of the tracer plume evolution in the Borden tracer experiment and of breakthrough curves in homogeneous and uniformly heterogeneous sand packs are successfully validated with experimental data [5,6]. Non-Fickian dispersion behavior resulting from the scale effect (plume-size dependent dispersivities) and skewed <span class="hlt">velocity</span> statistics is demonstrated and analyzed. [1] Zhang, Y. K. and D. Zhang (2004). "Forum: The state of stochastic hydrology." Stochastic Environmental Research and Risk Assessment 18(4): 265-265. [2] Salandin, P. and V. Fiorotto (1998). "Solute transport in highly heterogeneous aquifers." Water Resources Research 34(5): 949-961. [3] Benson, D. A., R. Schumer, et al. (2001). "Fractional</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1004383','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1004383"><span id="translatedtitle">Analytic solutions for seismic travel time and ray path geometry through simple <span class="hlt">velocity</span> <span class="hlt">models</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ballard, Sanford</p> <p>2007-12-01</p> <p>The geometry of ray paths through realistic Earth <span class="hlt">models</span> can be extremely complex due to the vertical and lateral heterogeneity of the <span class="hlt">velocity</span> distribution within the <span class="hlt">models</span>. Calculation of high fidelity ray paths and travel times through these <span class="hlt">models</span> generally involves sophisticated algorithms that require significant assumptions and approximations. To test such algorithms it is desirable to have available analytic solutions for the geometry and travel time of rays through simpler <span class="hlt">velocity</span> distributions against which the more complex algorithms can be compared. Also, in situations where computational performance requirements prohibit implementation of full 3D algorithms, it may be necessary to accept the accuracy limitations of analytic solutions in order to compute solutions that satisfy those requirements. Analytic solutions are described for the geometry and travel time of infinite frequency rays through radially symmetric 1D Earth <span class="hlt">models</span> characterized by an inner sphere where the <span class="hlt">velocity</span> distribution is given by the function V (r) = A-Br{sup 2}, optionally surrounded by some number of spherical shells of constant <span class="hlt">velocity</span>. The mathematical basis of the calculations is described, sample calculations are presented, and results are compared to the Taup Toolkit of Crotwell et al. (1999). These solutions are useful for evaluating the fidelity of sophisticated 3D travel time calculators and in situations where performance requirements preclude the use of more computationally intensive calculators. It should be noted that most of the solutions presented are only quasi-analytic. Exact, closed form equations are derived but computation of solutions to specific problems generally require application of numerical integration or root finding techniques, which, while approximations, can be calculated to very high accuracy. Tolerances are set in the numerical algorithms such that computed travel time accuracies are better than 1 microsecond.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/945756','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/945756"><span id="translatedtitle">HIGH-RESOLUTION SEISMIC <span class="hlt">VELOCITY</span> AND ATTENUATION <span class="hlt">MODELS</span> OF THE CAUCASUS-CASPIAN REGION</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mellors, R; Gok, R; Pasyanos, M; Skobeltsyn, G; Teoman, U; Godoladze, T; Sandvol, E</p> <p>2008-07-01</p> <p>The southwest edge of Eurasia is a tectonically and structurally complex region that includes the Caspian and Black Sea basins, the Caucasus Mountains, and the high plateaus south of the Caucasus. Using data from 25 broadband stations located in the region, new estimates of crustal and upper mantle thickness, <span class="hlt">velocity</span> structure, and attenuation are being developed. Receiver functions have been determined for all stations. Depth to Moho is estimated using slant stacking of the receiver functions, forward <span class="hlt">modeling</span>, and inversion. Moho depths along the Caspian and in the Kura Depression are in general poorly constrained using only receiver functions due to thick sedimentary basin sediments. The best fitting <span class="hlt">models</span> suggest a low <span class="hlt">velocity</span> upper crust with Moho depths ranging from 30 to 40 km. Crustal thicknesses increase in the Greater Caucasus with Moho depths of 40 to 50 km. Pronounced variations with azimuth of source are observed indicating 3D structural complexity and upper crustal <span class="hlt">velocities</span> are higher than in the Kura Depression to the south. In the Lesser Caucasus, south and west of the Kura Depression, the crust is thicker (40 to 50 km) and upper crustal <span class="hlt">velocities</span> are higher. Work is underway to refine these <span class="hlt">models</span> with the event based surface wave dispersion and ambient noise correlation measurements from continuous data. Regional phase (Lg and Pg) attenuation <span class="hlt">models</span> as well as blockage maps for Pn and Sn are being developed. Two methods are used to estimate Q: the two-station method to estimate inter-station Q and the reversed, two-station, two event method. The results are then inverted to create Lg and Pg Q maps. Initial results suggest substantial variations in both Pg and Lg Q in the region. A zone of higher Pg Q extends west from the Caspian between the Lesser and Greater Caucasus and a narrow area of higher Lg Q is observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950041534&hterms=sunlight&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsunlight','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950041534&hterms=sunlight&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dsunlight"><span id="translatedtitle"><span class="hlt">Modeling</span> of integrated sunlight <span class="hlt">velocity</span> measurements: The effect of surface darkening by magnetic fields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ulrich, R. K.; Henney, C. J.; Schimpf, S.; Fossat, E.; Gelly, B.; Grec, G.; Loudagh, S.; Schmider, F.-X; Palle, P.; Regulo, C.</p> <p>1993-01-01</p> <p>It has been known since the work by Claverie et al. (1982) that integrated-sunlight <span class="hlt">velocities</span> measured with the resonance scattering technique show variations with time scales of weeks to months. The cause can be understood in terms of the effects of solar activity as was pointed out by Edmunds & Gough (1983) and Andersen & Maltby (1983). The latter authors included a <span class="hlt">model</span> calculation based on sunspot areas which showed good promise of being able to quantitatively reproduce the observed <span class="hlt">velocity</span> shifts. We discuss in this paper a new <span class="hlt">modeling</span> effort based on daily magnetograms obtained at the 150-ft tower on Mt. Wilson. This type of database is more quantitative than sunspot area. Similar maps of magnetically sensitive quantities will be measured on a continuous time base as part of several planned helioseismology experiments (from space with the Solar Oscillations Imagery/Michelson Doppler Imager (SOI/MDI) experiment on the Solar and Heliospheric Observatory (SOHO), see Scherrer et al. (1991) or with ground-based networks, see Hill & Leibacher (1991)). We discuss the correlations between various magnetically sensitive quantities and develop a new <span class="hlt">model</span> for the effects of magnetic field on line profiles and surface brightness. From these correlations we integrate the line profile changes over the solar surface using observed magnetic field strengths measured at lambda 5250.2. The final output is a new <span class="hlt">model</span> for the effects of magnetic fields on integrated sunlight <span class="hlt">velocities</span> which we compare with daily offset <span class="hlt">velocities</span> derived from the International Research on the Interior of the Sun (IRIS)-T instrument at the Observatorio del Teide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V43B3149F&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V43B3149F&link_type=ABSTRACT"><span id="translatedtitle">Hindrance <span class="hlt">Velocity</span> <span class="hlt">Model</span> for Phase Segregation in Suspensions of Poly-dispersed Randomly Oriented Spheroids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Faroughi, S. A.; Huber, C.</p> <p>2015-12-01</p> <p>Crystal settling and bubbles migration in magmas have significant effects on the physical and chemical evolution of magmas. The rate of phase segregation is controlled by the force balance that governs the migration of particles suspended in the melt. The relative <span class="hlt">velocity</span> of a single particle or bubble in a quiescent infinite fluid (melt) is well characterized; however, the interplay between particles or bubbles in suspensions and emulsions and its effect on their settling/rising <span class="hlt">velocity</span> remains poorly quantified. We propose a theoretical <span class="hlt">model</span> for the hindered <span class="hlt">velocity</span> of non-Brownian emulsions of nondeformable droplets, and suspensions of spherical solid particles in the creeping flow regime. The <span class="hlt">model</span> is based on three sets of hydrodynamic corrections: two on the drag coefficient experienced by each particle to account for both return flow and Smoluchowski effects and a correction on the mixture rheology to account for nonlocal interactions between particles. The <span class="hlt">model</span> is then extended for mono-disperse non-spherical solid particles that are randomly oriented. The non-spherical particles are idealized as spheroids and characterized by their aspect ratio. The poly-disperse nature of natural suspensions is then taken into consideration by introducing an effective volume fraction of particles for each class of mono-disperse particles sizes. Our <span class="hlt">model</span> is tested against new and published experimental data over a wide range of particle volume fraction and viscosity ratios between the constituents of dispersions. We find an excellent agreement between our <span class="hlt">model</span> and experiments. We also show two significant applications for our <span class="hlt">model</span>: (1) We demonstrate that hindered settling can increase mineral residence time by up to an order of magnitude in convecting magma chambers. (2) We provide a <span class="hlt">model</span> to correct for particle interactions in the conventional hydrometer test to estimate the particle size distribution in soils. Our <span class="hlt">model</span> offers a greatly improved agreement with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoJI.202.1535Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoJI.202.1535Z"><span id="translatedtitle">Full waveform inversion of diving & reflected waves for <span class="hlt">velocity</span> <span class="hlt">model</span> building with impedance inversion based on scale separation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Wei; Brossier, Romain; Operto, Stéphane; Virieux, Jean</p> <p>2015-09-01</p> <p>Full waveform inversion (FWI) aims to reconstruct high-resolution subsurface <span class="hlt">models</span> from the full wavefield, which includes diving waves, post-critical reflections and short-spread reflections. Most successful applications of FWI are driven by the information carried by diving waves and post-critical reflections to build the long-to-intermediate wavelengths of the <span class="hlt">velocity</span> structure. Alternative approaches, referred to as reflection waveform inversion (RWI), have been recently revisited to retrieve these long-to-intermediate wavelengths from short-spread reflections by using some prior knowledge of the reflectivity and a scale separation between the <span class="hlt">velocity</span> macromodel and the reflectivity. This study presents a unified formalism of FWI, named as Joint FWI, whose aim is to efficiently combine the diving and reflected waves for <span class="hlt">velocity</span> <span class="hlt">model</span> building. The two key ingredients of Joint FWI are, on the data side, the explicit separation between the short-spread reflections and the wide-angle arrivals and, on the <span class="hlt">model</span> side, the scale separation between the <span class="hlt">velocity</span> macromodel and the short-scale impedance <span class="hlt">model</span>. The <span class="hlt">velocity</span> <span class="hlt">model</span> and the impedance <span class="hlt">model</span> are updated in an alternate way by Joint FWI and waveform inversion of the reflection data (least-squares migration), respectively. Starting from a crude <span class="hlt">velocity</span> <span class="hlt">model</span>, Joint FWI is applied to the streamer seismic data computed in the synthetic Valhall <span class="hlt">model</span>. While the conventional FWI is stuck into a local minimum due to cycle skipping, Joint FWI succeeds in building a reliable <span class="hlt">velocity</span> macromodel. Compared with RWI, the use of diving waves in Joint FWI improves the reconstruction of shallow <span class="hlt">velocities</span>, which translates into an improved imaging at deeper depths. The smooth <span class="hlt">velocity</span> <span class="hlt">model</span> built by Joint FWI can be subsequently used as a reliable initial <span class="hlt">model</span> for conventional FWI to increase the high-wavenumber content of the <span class="hlt">velocity</span> <span class="hlt">model</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.S11D0321Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.S11D0321Z"><span id="translatedtitle">Crustal <span class="hlt">Velocity</span> <span class="hlt">Model</span> of Watusi and Legacy Seismic Refraction Data, Clark County, Nevada</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaragoza, S. A.; Snelson, C. M.; McEwan, D.; Sandru, J.; Hirsch, A. C.</p> <p>2003-12-01</p> <p>Clark County, Nevada is located in the southern portion of the Basin and Range Province. As such, it has undergone tremendous extensional forces that produced numerous north-trending ridges and basins. Little is known regarding the crustal structure of the southern Basin and Range. Extension along the Las Vegas Valley Shear Zone (LVVSZ) has produced a northwest-trending corridor of particular interest that may channel seismic energy into the Las Vegas basin. Potential sources include energy produced by earthquakes as well as nuclear testing, should the Nevada Test Site (NTS) become active in the future. Previous studies include a crustal <span class="hlt">velocity</span> <span class="hlt">model</span> in the form of a fence diagram by Prodehl (1979) based on Legacy data, seismic refraction experiments performed when the NTS was active. Legacy data were collected on seismometers placed at intervals greater than or equal to 500 m. Seismic sources included chemical blasts and nuclear test shots. To examine whether structures along the corridor would cause seismic energy to dissipate or to transmit into the basin, in September 2002 we utilized 400 seismic instruments to record the Watusi chemical blast at the Nevada Test Site. The profile extended from Ann Road and I-95 northwest to the town of Indian Springs, where the station spacing was 125 m. The blast was located 65 km away from the first station and was expected to have the energy equivalent to 40,000 tons of TNT. However, most of the energy was lost into the air. In addition, falling debris produced diffractions in the data. We picked first arrivals and analyzed these data with forward <span class="hlt">modeling</span> utilizing MacRay ray-tracing software, integrating these with Prodehl's <span class="hlt">model</span> to produce an updated, higher resolution crustal <span class="hlt">velocity</span> <span class="hlt">model</span>. The <span class="hlt">model</span> indicates <span class="hlt">velocities</span> of the upper to lower crust, into the Moho, with average <span class="hlt">velocities</span> of approximately 6 km/s. Further studies will include integrating data from the Seismic Investigation of the Las Vegas Valley</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015Tectp.651...58M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015Tectp.651...58M&link_type=ABSTRACT"><span id="translatedtitle">Block <span class="hlt">modeling</span> of crustal deformation in Tierra del Fuego from GNSS <span class="hlt">velocities</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mendoza, L.; Richter, A.; Fritsche, M.; Hormaechea, J. L.; Perdomo, R.; Dietrich, R.</p> <p>2015-05-01</p> <p>The Tierra del Fuego (TDF) main island is divided by a major transform boundary between the South America and Scotia tectonic plates. Using a block <span class="hlt">model</span>, we infer slip rates, locking depths and inclinations of active faults in TDF from inversion of site <span class="hlt">velocities</span> derived from Global Navigation Satellite System observations. We use interseismic <span class="hlt">velocities</span> from 48 sites, obtained from field measurements spanning 20 years. Euler vectors consistent with a simple seismic cycle are estimated for each block. In addition, we introduce far-field information into the <span class="hlt">modeling</span> by applying constraints on Euler vectors of major tectonic plates. The difference between <span class="hlt">model</span> and observed surface deformation near the Magallanes Fagnano Fault System (MFS) is reduced by considering finite dip in the forward <span class="hlt">model</span>. For this tectonic boundary global plate circuits <span class="hlt">models</span> predict relative movements between 7 and 9 mm yr- 1, while our regional <span class="hlt">model</span> indicates that a strike-slip rate of 5.9 ± 0.2 mm yr- 1 is accommodated across the MFS. Our results indicate faults dipping 66- 4+ 6° southward, locked to a depth of 11- 5+ 5 km, which are consistent with geological <span class="hlt">models</span> for the MFS. However, normal slip also dominates the fault perpendicular motion throughout the eastern MFS, with a maximum rate along the Fagnano Lake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012PhFl...24g5108O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012PhFl...24g5108O"><span id="translatedtitle">Accounting for uncertainty in the analysis of overlap layer mean <span class="hlt">velocity</span> <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oliver, Todd A.; Moser, Robert D.</p> <p>2012-07-01</p> <p>When assessing the veracity of mathematical <span class="hlt">models</span>, it is important to consider the uncertainties in the data used for the assessment. In this paper, we study the impact of data uncertainties on the analysis of overlap layer <span class="hlt">models</span> for the mean <span class="hlt">velocity</span> in wall-bounded turbulent flows. Specifically, the tools of Bayesian statistics are used to calibrate and compare six competing <span class="hlt">models</span> of the mean <span class="hlt">velocity</span> profile, including multiple logarithmic and power law forms, using <span class="hlt">velocity</span> profile measurements from a zero-pressure-gradient turbulent boundary layer and fully developed turbulent pipe flow. The calibration problem is formulated as a Bayesian update of the joint probability density function for the calibration parameters, which are treated as random variables to characterize incomplete knowledge about their values. This probabilistic formulation provides a natural treatment of uncertainty and gives insight into the quality of the fit, features that are not easily obtained in deterministic calibration procedures. The <span class="hlt">model</span> comparison also relies on a Bayesian update. In particular, the relative probabilities of the competing <span class="hlt">models</span> are updated using the calibration data. The resulting posterior probabilities quantify the relative plausibility of the competing <span class="hlt">models</span> given the data. For the boundary layer, results are shown for five subsets of the turbulent boundary layer data due to Österlund, including different Reynolds number and wall distance ranges, and multiple assumptions regarding the magnitude of the uncertainty in the <span class="hlt">velocity</span> measurements. For most choices, multiple <span class="hlt">models</span> have relatively high posterior probability, indicating that it is difficult to distinguish between the <span class="hlt">models</span>. For the most inclusive data sets—i.e., the largest ranges of Reynolds number and wall distance—the first-order logarithmic law due to Buschmann and Gad-el-Hak is significantly more probable, given the data, than the other <span class="hlt">models</span> evaluated. For the pipe flow, data from</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120..344G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120..344G"><span id="translatedtitle">Validation of recent shear wave <span class="hlt">velocity</span> <span class="hlt">models</span> in the United States with full-wave simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gao, Haiying; Shen, Yang</p> <p>2015-01-01</p> <p>Interpretations of dynamic processes and the thermal and chemical structure of the Earth depend on the accuracy of Earth <span class="hlt">models</span>. With the growing number of <span class="hlt">velocity</span> <span class="hlt">models</span> constructed with different tomographic methods and seismic data sets, there is an increasing need for a systematic way to validate <span class="hlt">model</span> accuracy and resolution. This study selects five shear wave <span class="hlt">velocity</span> <span class="hlt">models</span> in the U.S. and simulates full-wave propagation within the 3-D structures. Surface-wave signals extracted from ambient seismic noise and regional earthquakes are compared with synthetic waveforms at multiple-frequency bands. Phase delays and cross-correlation coefficients between observed and synthetic waveforms allow us to compare and validate these <span class="hlt">models</span> quantitatively. In general, measurements from regional earthquakes are consistent with ambient noise results, but appear more scattered, which may result from uncertainty of the earthquake source location, origin time, and moment tensor. Our results show the improvement of <span class="hlt">model</span> prediction with the increase of seismic data sets and implement of advanced methods. There exists a positive linear trend between phase delay and interstation distance for three <span class="hlt">models</span>, indicating that on average, these <span class="hlt">models</span> are faster than the real Earth structure. The phase delays from the jointly inverted <span class="hlt">model</span> of ambient noise and receiver function have negative means at all periods while without obvious dependence on the interstation distance. The full-wave ambient noise tomographic <span class="hlt">model</span> predicts more accurate phase arrivals compared to other <span class="hlt">models</span>. This study suggests a need for an integrated <span class="hlt">model</span> constructed with multiple seismic waveforms and consideration of anisotropy and attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22167522','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22167522"><span id="translatedtitle">STANDARDIZING TYPE Ia SUPERNOVA <span class="hlt">ABSOLUTE</span> MAGNITUDES USING GAUSSIAN PROCESS DATA REGRESSION</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, A. G.; Aldering, G.; Aragon, C.; Bailey, S.; Childress, M.; Fakhouri, H. K.; Nordin, J.; Thomas, R. C.; Antilogus, P.; Bongard, S.; Canto, A.; Cellier-Holzem, F.; Guy, J.; Baltay, C.; Buton, C.; Kerschhaggl, M.; Kowalski, M.; Chotard, N.; Copin, Y.; Gangler, E.; and others</p> <p>2013-04-01</p> <p>We present a novel class of <span class="hlt">models</span> for Type Ia supernova time-evolving spectral energy distributions (SEDs) and <span class="hlt">absolute</span> magnitudes: they are each <span class="hlt">modeled</span> as stochastic functions described by Gaussian processes. The values of the SED and <span class="hlt">absolute</span> magnitudes are defined through well-defined regression prescriptions, so that data directly inform the <span class="hlt">models</span>. As a proof of concept, we implement a <span class="hlt">model</span> for synthetic photometry built from the spectrophotometric time series from the Nearby Supernova Factory. <span class="hlt">Absolute</span> magnitudes at peak B brightness are calibrated to 0.13 mag in the g band and to as low as 0.09 mag in the z = 0.25 blueshifted i band, where the dispersion includes contributions from measurement uncertainties and peculiar <span class="hlt">velocities</span>. The methodology can be applied to spectrophotometric time series of supernovae that span a range of redshifts to simultaneously standardize supernovae together with fitting cosmological parameters.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.205.1342T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.205.1342T"><span id="translatedtitle">Evaluation of the southern California seismic <span class="hlt">velocity</span> <span class="hlt">models</span> through simulation of recorded events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taborda, Ricardo; Azizzadeh-Roodpish, Shima; Khoshnevis, Naeem; Cheng, Keli</p> <p>2016-06-01</p> <p>Significant effort has been devoted over the last two decades to the development of various seismic <span class="hlt">velocity</span> <span class="hlt">models</span> for the region of southern California, United States. These <span class="hlt">models</span> are mostly used in forward wave propagation simulation studies, but also as base <span class="hlt">models</span> for tomographic and source inversions. Two of these <span class="hlt">models</span>, the community <span class="hlt">velocity</span> <span class="hlt">models</span> CVM-S and CVM-H, are among the most commonly used for this region. This includes two alternative variations to the original <span class="hlt">models</span>, the recently released CVM-S4.26 which incorporates results from a sequence of tomographic inversions into CVM-S, and the user-controlled option of CVM-H to replace the near-surface profiles with a VS30-based geotechnical <span class="hlt">model</span>. Although either one of these <span class="hlt">models</span> is regarded as acceptable by the <span class="hlt">modeling</span> community, it is known that they have differences in their representation of the crustal structure and sedimentary deposits in the region, and thus can lead to different results in forward and inverse problems. In this paper, we evaluate the accuracy of these <span class="hlt">models</span> when used to predict the ground motion in the greater Los Angeles region by means of an assessment of a collection of simulations of recent events. In total, we consider 30 moderate-magnitude earthquakes (3.5 < Mw < 5.5) between 1998 and 2014, and compare synthetics with data recorded by seismic networks during these events. The simulations are done using a finite-element parallel code, with numerical <span class="hlt">models</span> that satisfy a maximum frequency of 1 Hz and a minimum shear wave <span class="hlt">velocity</span> of 200 m s-1. The comparisons between data and synthetics are ranked quantitatively by means of a goodness-of-fit (GOF) criteria. We analyse the regional distribution of the GOF results for all events and all <span class="hlt">models</span>, and draw conclusions from the results and how these correlate to the <span class="hlt">models</span>. We find that, in light of our comparisons, the <span class="hlt">model</span> CVM-S4.26 consistently yields better results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.tmp...47T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.tmp...47T"><span id="translatedtitle">Evaluation of the Southern California Seismic <span class="hlt">Velocity</span> <span class="hlt">Models</span> through Simulation of Recorded Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taborda, Ricardo; Azizzadeh-Roodpish, Shima; Khoshnevis, Naeem; Cheng, Keli</p> <p>2016-03-01</p> <p>Significant effort has been devoted over the last two decades to the development of various seismic <span class="hlt">velocity</span> <span class="hlt">models</span> for the region of southern California, United States. These <span class="hlt">models</span> are mostly used in forward wave propagation simulation studies, but also as base <span class="hlt">models</span> for tomographic and source inversions. Two of these <span class="hlt">models</span>, the community <span class="hlt">velocity</span> <span class="hlt">models</span> CVM-S and CVM-H, are among the most commonly used for this region. This includes two alternative variations to the original <span class="hlt">models</span>, the recently released CVM-S4.26 which incorporates results from a sequence of tomographic inversions into CVM-S, and the user-controlled option of CVM-H to replace the near-surface profiles with a VS30-based geotechnical (GTL) <span class="hlt">model</span>. Although either one of these <span class="hlt">models</span> is regarded as acceptable by the <span class="hlt">modeling</span> community, it is known that they have differences in their representation of the crustal structure and sedimentary deposits in the region, and thus can lead to different results in forward and inverse problems. In this article we evaluate the accuracy of these <span class="hlt">models</span> when used to predict the ground motion in the greater Los Angeles region by means of an assessment of a collection of simulations of recent events. In total, we consider 30 moderate-magnitude earthquakes (3.5 < Mw < 5.5) between 1998 and 2014, and compare synthetics with data recorded by seismic networks during these events. The simulations are done using a finite element parallel code, with numerical <span class="hlt">models</span> that satisfy a maximum frequency of 1 Hz and a minimum shear wave <span class="hlt">velocity</span> of 200 m/s. The comparisons between data and synthetics are ranked quantitatively by means of a goodness-of-fit (GOF) criteria. We analyze the regional distribution of the GOF results for all events and all <span class="hlt">models</span>, and draw conclusions from the results and how these correlate to the <span class="hlt">models</span>. We find that, in light of our comparisons, the <span class="hlt">model</span> CVM-S4.26 consistently yields better results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGE....12..527G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGE....12..527G"><span id="translatedtitle">Rock physics <span class="hlt">model</span>-based prediction of shear wave <span class="hlt">velocity</span> in the Barnett Shale formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Zhiqi; Li, Xiang-Yang</p> <p>2015-06-01</p> <p>Predicting S-wave <span class="hlt">velocity</span> is important for reservoir characterization and fluid identification in unconventional resources. A rock physics <span class="hlt">model</span>-based method is developed for estimating pore aspect ratio and predicting shear wave <span class="hlt">velocity</span> Vs from the information of P-wave <span class="hlt">velocity</span>, porosity and mineralogy in a borehole. Statistical distribution of pore geometry is considered in the rock physics <span class="hlt">models</span>. In the application to the Barnett formation, we compare the high frequency self-consistent approximation (SCA) method that corresponds to isolated pore spaces, and the low frequency SCA-Gassmann method that describes well-connected pore spaces. Inversion results indicate that compared to the surroundings, the Barnett Shale shows less fluctuation in the pore aspect ratio in spite of complex constituents in the shale. The high frequency method provides a more robust and accurate prediction of Vs for all the three intervals in the Barnett formation, while the low frequency method collapses for the Barnett Shale interval. Possible causes for this discrepancy can be explained by the fact that poor in situ pore connectivity and low permeability make well-log sonic frequencies act as high frequencies and thus invalidate the low frequency assumption of the Gassmann theory. In comparison, for the overlying Marble Falls and underlying Ellenburger carbonates, both the high and low frequency methods predict Vs with reasonable accuracy, which may reveal that sonic frequencies are within the transition frequencies zone due to higher pore connectivity in the surroundings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S31A2030P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S31A2030P"><span id="translatedtitle">Three dimensional Rayleigh wave <span class="hlt">velocity</span> <span class="hlt">model</span> using multimode surface wave tomography of Eastern Asia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pandey, S.; Yuan, X.; Debayle, E.; Priestley, K. F.; Kind, R.; Li, X.</p> <p>2010-12-01</p> <p>The collision of the Eurasian plate, Indian plate and Philippine sea plate resulted in the tectonic feature of todays; like mountain ranges, fold belts, sedimentary basins and high plateaus in China and the surrounding region. In the Northern part this region is supposed to get some resistance from the Siberian shield. But the collision of Indian plate has left its major imprints and the consequence of this was the uplift of Himalayan Mountain and Tibetan Plateau. This triple junction scenario is the main cause for many inter and intra-plate earthquake in this region. It is generally agreed that the lithosphere is thick in west China while much of the lithospheric root was lost beneath some cratons in east China. Still it's an open debate whether the lithosphere beneath the Tibetan plateau has doubled its thickness as did the crust above or much of the thickened lithosphere was removed by mantle convection and delamination. In our study we try to determine the three dimensional Sv wave speed and azimuthal anisotropy <span class="hlt">model</span> by analyzing the vertical component multimode Rayleigh wave seismogram. The data which we used are from broadband stations from in and around China. We construct the three dimensional <span class="hlt">model</span> in two step procedure. In the first step we use the automated version of the Cara and Leveque [1987] waveform inversion technique in terms of secondary observables for <span class="hlt">modeling</span> each multimode Rayleigh waveform to determine the path-average mantle Sv wave speed structure. In the second stage we combine the 1-D <span class="hlt">velocity</span> <span class="hlt">models</span> in a tomographic inversion to obtain the three dimensional Sv wave speed structure and the azimuthal anisotropy as a function of depth. We have taken a source region specific <span class="hlt">velocity</span> structure from the three dimensional <span class="hlt">model</span> 3SMAC to improve the source excitation computation. We analyzed the seismograms using a modified (smoothed) version of PREM for the upper mantle <span class="hlt">velocity</span> structure both for the reference <span class="hlt">model</span> used in extracting the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26161661','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26161661"><span id="translatedtitle">An Analytical <span class="hlt">Model</span> for the Distributions of <span class="hlt">Velocity</span> and Discharge in Compound Channels with Submerged Vegetation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Beihan; Yang, Kejun; Cao, Shuyou</p> <p>2015-01-01</p> <p>Based on the momentum transfer theory, an analytical <span class="hlt">model</span> is proposed for the <span class="hlt">velocity</span> and discharge distributions in compound channels with submerged vegetation on the floodplain. The partially vegetated channel was divided into three sub-regions, i.e. the main channel region, the floodplain region with submerged vegetation and the floodplain region without vegetation. For each region, the force balance relationship was established, and the momentum transfer between different regions was presented. Verification by the experimental data and comparison with the traditional method shows that the proposed method is capable of predicting for the <span class="hlt">velocity</span> and discharge distributions in compound channels with submerged vegetation and is superior to the conventional method. The results also show that when the momentum transfer between different regions is ignored, the computed discharge will be much lager than the measured data, and the error increases with the discharge, especially in the floodplain region. PMID:26161661</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/12445609','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/12445609"><span id="translatedtitle">In vivo force-<span class="hlt">velocity</span> relation of human muscle: a <span class="hlt">modelling</span> from sinusoidal oscillation behaviour.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Desplantez, A; Goubel, F</p> <p>2002-12-01</p> <p>Isokinetic tests performed on human muscle in vivo during plantar flexion contractions lead to torque-angular <span class="hlt">velocity</span> relationships usually fitted by Hill's equation expressed in angular terms. However, such tests can lead to discrepant results since they require maximal voluntary contractions performed in dynamic conditions. In the present study, another way to approach mechanical behaviour of a musculo-articular structure was used, i.e. sinusoidal oscillations during sub-maximal contractions. This led to the expression of (i). Bode diagrams allowing the determination of a damping coefficient (B(bode)); and (ii). a viscous parameter (B(sin)) using an adaptation of Hill's equation to sinusoidal oscillations. Then torque-angular <span class="hlt">velocity</span> relationships were predicted from a <span class="hlt">model</span> based on the interrelation between B(bode) and B(sin) and on the determination of optimal conditions of contraction. This offers the possibility of characterizing muscle dynamic properties by avoiding the use of isokinetic maximal contractions. PMID:12445609</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4498773','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4498773"><span id="translatedtitle">An Analytical <span class="hlt">Model</span> for the Distributions of <span class="hlt">Velocity</span> and Discharge in Compound Channels with Submerged Vegetation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jiang, Beihan; Yang, Kejun; Cao, Shuyou</p> <p>2015-01-01</p> <p>Based on the momentum transfer theory, an analytical <span class="hlt">model</span> is proposed for the <span class="hlt">velocity</span> and discharge distributions in compound channels with submerged vegetation on the floodplain. The partially vegetated channel was divided into three sub-regions, i.e. the main channel region, the floodplain region with submerged vegetation and the floodplain region without vegetation. For each region, the force balance relationship was established, and the momentum transfer between different regions was presented. Verification by the experimental data and comparison with the traditional method shows that the proposed method is capable of predicting for the <span class="hlt">velocity</span> and discharge distributions in compound channels with submerged vegetation and is superior to the conventional method. The results also show that when the momentum transfer between different regions is ignored, the computed discharge will be much lager than the measured data, and the error increases with the discharge, especially in the floodplain region. PMID:26161661</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997ApJ...481..267D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997ApJ...481..267D"><span id="translatedtitle">The Dynamics of M15: Observations of the <span class="hlt">Velocity</span> Dispersion Profile and Fokker-Planck <span class="hlt">Models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dull, J. D.; Cohn, H. N.; Lugger, P. M.; Murphy, B. W.; Seitzer, P. O.; Callanan, P. J.; Rutten, R. G. M.; Charles, P. A.</p> <p>1997-05-01</p> <p>We report a new measurement of the <span class="hlt">velocity</span> dispersion profile within 1' (3 pc) of the center of the globular cluster M15 (NGC 7078), using long-slit spectra from the 4.2 m William Herschel Telescope at La Palma Observatory. We obtained spatially resolved spectra for a total of 23 slit positions during two observing runs. During each run, a set of parallel slit positions was used to map out the central region of the cluster; the position angle used during the second run was orthogonal to that used for the first. The spectra are centered in wavelength near the Ca II infrared triplet at 8650 Å, with a spectral range of about 450 Å. We determined radial <span class="hlt">velocities</span> by cross-correlation techniques for 131 cluster members. A total of 32 stars were observed more than once. Internal and external comparisons indicate a <span class="hlt">velocity</span> accuracy of about 4 km s-1. The <span class="hlt">velocity</span> dispersion profile rises from about σ = 7.2 +/- 1.4 km s-1 near 1' from the center of the cluster to σ = 13.9 +/- 1.8 km s-1 at 20". Inside of 20", the dispersion remains approximately constant at about 10.2 +/- 1.4 km s-1 with no evidence for a sharp rise near the center. This last result stands in contrast with that of Peterson, Seitzer, & Cudworth who found a central <span class="hlt">velocity</span> dispersion of 25 +/- 7 km s-1, based on a line-broadening measurement. Our <span class="hlt">velocity</span> dispersion profile is in good agreement with those determined in the recent studies of Gebhardt et al. and Dubath & Meylan. We have developed a new set of Fokker-Planck <span class="hlt">models</span> and have fitted these to the surface brightness and <span class="hlt">velocity</span> dispersion profiles of M15. We also use the two measured millisecond pulsar accelerations as constraints. The best-fitting <span class="hlt">model</span> has a mass function slope of x = 0.9 (where 1.35 is the slope of the Salpeter mass function) and a total mass of 4.9 × 105 M⊙. This <span class="hlt">model</span> contains approximately 104 neutron stars (3% of the total mass), the majority of which lie within 6" (0.2 pc) of the cluster center. Since the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.usgs.gov/of/2007/1348/','USGSPUBS'); return false;" href="http://pubs.usgs.gov/of/2007/1348/"><span id="translatedtitle"><span class="hlt">Velocity</span> and Density <span class="hlt">Models</span> Incorporating the Cascadia Subduction Zone for 3D Earthquake Ground Motion Simulations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Stephenson, William J.</p> <p>2007-01-01</p> <p>INTRODUCTION In support of earthquake hazards and ground motion studies in the Pacific Northwest, three-dimensional P- and S-wave <span class="hlt">velocity</span> (3D Vp and Vs) and density (3D rho) <span class="hlt">models</span> incorporating the Cascadia subduction zone have been developed for the region encompassed from about 40.2?N to 50?N latitude, and from about -122?W to -129?W longitude. The <span class="hlt">model</span> volume includes elevations from 0 km to 60 km (elevation is opposite of depth in <span class="hlt">model</span> coordinates). Stephenson and Frankel (2003) presented preliminary ground motion simulations valid up to 0.1 Hz using an earlier version of these <span class="hlt">models</span>. The version of the <span class="hlt">model</span> volume described here includes more structural and geophysical detail, particularly in the Puget Lowland as required for scenario earthquake simulations in the development of the Seattle Urban Hazards Maps (Frankel and others, 2007). Olsen and others (in press) used the <span class="hlt">model</span> volume discussed here to perform a Cascadia simulation up to 0.5 Hz using a Sumatra-Andaman Islands rupture history. As research from the EarthScope Program (http://www.earthscope.org) is published, a wealth of important detail can be added to these <span class="hlt">model</span> volumes, particularly to depths of the upper-mantle. However, at the time of development for this <span class="hlt">model</span> version, no EarthScope-specific results were incorporated. This report is intended to be a reference for colleagues and associates who have used or are planning to use this preliminary <span class="hlt">model</span> in their research. To this end, it is intended that these <span class="hlt">models</span> will be considered a beginning template for a community <span class="hlt">velocity</span> <span class="hlt">model</span> of the Cascadia region as more data and results become available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/8176431','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/8176431"><span id="translatedtitle"><span class="hlt">Modeling</span> three-dimensional <span class="hlt">velocity</span>-to-position transformation in oculomotor control.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schnabolk, C; Raphan, T</p> <p>1994-02-01</p> <p>1. A considerable amount of attention has been devoted to understanding the <span class="hlt">velocity</span>-position transformation that takes place in the control of eye movements in three dimensions. Much of the work has focused on the idea that rotations in three dimensions do not commute and that a "multiplicative quaternion <span class="hlt">model</span>" of <span class="hlt">velocity</span>-position integration is necessary to explain eye movements in three dimensions. Our study has indicated that this approach is not consistent with the physiology of the types of signals necessary to rotate the eyes. 2. We developed a three-dimensional dynamical system <span class="hlt">model</span> for movement of the eye within its surrounding orbital tissue. The main point of the <span class="hlt">model</span> is that the eye muscles generate torque to rotate the eye. When the eye reaches an orientation such that the restoring torque of the orbital tissue counterbalances the torque applied by the muscles, a unique equilibrium point is reached. The trajectory of the eye to reach equilibrium may follow any path, depending on the starting eye orientation and eye <span class="hlt">velocity</span>. However, according to Euler's theorem, the equilibrium reached is equivalent to a rotation about a fixed axis through some angle from a primary orientation. This represents the shortest path that the eye could take from the primary orientation in reaching equilibrium. Consequently, it is also the shortest path for returning the eye to the primary orientation. Thus the restoring torque developed by the tissue surrounding the eye was approximated as proportional to the product of this angle and a unit vector along this axis. The relationship between orientation and restoring torque gives a unique torque-orientation relationship. 3. Once the appropriate torque-orientation relationship for eye rotation is established the <span class="hlt">velocity</span>-position integrator can be <span class="hlt">modeled</span> as a dynamical system that is a direct extension of the one-dimensional <span class="hlt">velocity</span>-position integrator. The linear combination of the integrator state and a direct pathway</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.T61A1220N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.T61A1220N"><span id="translatedtitle">Tomographic <span class="hlt">velocity</span> <span class="hlt">model</span> for the aftershock region of the 2001 Gujarat, India earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Negishi, H.; Kumar, S.; Mori, J. J.; Sato, T.; Bodin, P.; Rastogi, B.</p> <p>2002-12-01</p> <p>A tomographic inversion was applied to the aftershock data collected after the January 26, 2001 Bhuj earthquake (Ms 7.9, Mw 7.7), which occurred on a south dipping (~50 degrees) reverse fault in the state of Gujarat in western India. We used high quality arrivals from 8,374 P and 7,994 S waves of 1404 aftershocks recorded on 27 digital stations from temporary seismic arrays setup by the India-Japan team; NGRI, India; and CERI, Memphis Univ., USA, following the Bhuj main shock. First, we used the Joint Hypocenters Determination Method for obtaining relocated hypocenters and a one-dimensional Vp and Vs <span class="hlt">velocity</span> <span class="hlt">model</span>, and then the resultant hypocenters and 1-D <span class="hlt">velocity</span> <span class="hlt">model</span> were used as the initial parameters for a 3-D tomographic inversion. The tomography technique is based on a grid-<span class="hlt">modeling</span> method by Zhao et al. . Vp, Vs and hypocenters are determined simultaneously. We tried to use the Cross-Validation Technique for determining an optimum <span class="hlt">model</span> in the seismic tomography. This approach has been applied to other tomographic studies to investigate the quantitative fluctuation range of <span class="hlt">velocity</span> perturbations . Significant variations in the <span class="hlt">velocity</span> (up to 6%) and Poisson's ratio (up to 8%) are revealed in the aftershock area. It seems that the aftershock distribution corresponds to the boundary between high and low <span class="hlt">velocity</span> heterogeneities. Small values of Vp/Vs are generally found at depths of 10 to 35 km, i.e. the depth range of aftershock distribution. However, the deeper region below the hypocenter of the mainshock, at depths of 35 to 45 km, is characterized by relatively high values of Vp/Vs and low values of Vs. This anomaly may be due to a weak fractured and fluid filled rock matrix, which might have contributed to triggering this earthquake. This earthquake occurred on a relatively deep and steeply dipping fault with a large stress drop . Theoretically it is difficult to slip steep faults, especially in the lower crust. Our tomographic investigation provides</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23586876','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23586876"><span id="translatedtitle"><span class="hlt">Absolute</span> biological needs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McLeod, Stephen</p> <p>2014-07-01</p> <p><span class="hlt">Absolute</span> needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended <span class="hlt">absolute</span> needs on the grounds that the verb 'need' has instrumental and <span class="hlt">absolute</span> senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are <span class="hlt">absolute</span> biological needs. The <span class="hlt">absolute</span> nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of <span class="hlt">absolute</span> need is not inherently normative in either of the first two senses. PMID:23586876</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1382...49W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1382...49W"><span id="translatedtitle"><span class="hlt">Absolute</span> neutrino mass measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wolf, Joachim</p> <p>2011-10-01</p> <p>The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2β) searches, single β-decay experiments provide a direct, <span class="hlt">model</span>-independent way to determine the <span class="hlt">absolute</span> neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy. Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium β-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope (137Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R&D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2β decay and single β-decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21611867','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21611867"><span id="translatedtitle"><span class="hlt">Absolute</span> neutrino mass measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wolf, Joachim</p> <p>2011-10-06</p> <p>The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, <span class="hlt">model</span>-independent way to determine the <span class="hlt">absolute</span> neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22089793','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22089793"><span id="translatedtitle"><span class="hlt">ABSOLUTE</span> PROPERTIES OF THE TRIPLE STAR CF TAURI</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lacy, Claud H. Sandberg; Torres, Guillermo; Claret, Antonio E-mail: gtorres@cfa.harvard.edu</p> <p>2012-12-01</p> <p>CF Tau is now known to be an eclipsing triple star with relatively deep total and annular eclipses. New light and radial <span class="hlt">velocity</span> curves as well as new times of minima were obtained and used for further <span class="hlt">modeling</span> of the system. Very accurate (better than 0.9%) masses and radii of the eclipsing pair are determined from analysis of the two new light curves, the radial <span class="hlt">velocity</span> curve, and the times of minimum light. The mass and luminosity of the distant third component is accurately determined as well. Theoretical <span class="hlt">models</span> of the detached, evolved eclipsing pair match the observed <span class="hlt">absolute</span> properties of the stars at an age of about 4.3 Gyr and [Fe/H] = -0.14.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.8181L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.8181L"><span id="translatedtitle">Development of the EUREF <span class="hlt">Velocity</span> <span class="hlt">Model</span> - Status and Roadmap for Future Work</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lidberg, Martin; Steffen, Holger; Altamimi, Zuheir; Bruyninx, Carine; Caporali, Alessandro; Dousa, Jan; Habrich, Heinz; Kenyeres, Ambrus; da Silva Fernandes, Rui Manuel; Stangl, Günter</p> <p>2013-04-01</p> <p>Interplate and intraplate deformations are present all over Europe. They can be subdivided by their spatial or temporal nature as well as their magnitude. For example, different, partly overlapping processes are related to several geodynamic zones such as plate boundaries, micro-plates, volcanoes, (formerly) glaciated areas, hydrological basins etc. On the other side, there are long-term processes such as the Fennoscandian post-glacial rebound, episodic events such as earthquakes and many temporarily intermediate deformations from e.g. volcanic swelling or anthropogenic influences due to oil or gas extraction or CO2 sequestration. The corresponding deformations of different scales are measured as three-dimensional crustal <span class="hlt">velocities</span> by Global Navigation Satellite System (GNSS) reference stations with meanwhile sufficient detail and accuracy. The IAG Reference Frame Sub-Commission for Europe (EUREF) working group on "Deformation <span class="hlt">models</span>" aims at obtaining <span class="hlt">velocity</span> <span class="hlt">models</span> for Europe and adjacent areas and significantly improving the prediction of the time evolution of coordinates, thus overcoming the limitations in the use of the European Terrestrial Reference System 1989 (ETRS89). A general understanding of the physics behind such a <span class="hlt">velocity</span> field is also a major goal. In particular, the working group will <span class="hlt">model</span> and correct for interplate and intraplate deformations, while using the reference frame, and thus extend the useful lifetime of a realisation of the ETRS89. Hence, the purpose of this working group are twofold; first, pure scientific interests in improved knowledge of the surface deformations of Eurasia and adjacent areas, and second, providing a valuable tool in the management and use of the national realisations of the ETRS89. The work will strongly benefit from sophisticated infrastructures such as the European Plate Observing System (EPOS). Key information for improved knowledge of crustal deformations is observed motions at stations. This includes</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.U34A..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.U34A..03P"><span id="translatedtitle">A Whole-Mantle Three Dimensional Radially Anisotropic S <span class="hlt">Velocity</span> <span class="hlt">Model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panning, M. P.; Romanowicz, B. A.</p> <p>2004-12-01</p> <p>We present a 3D radially anisotropic <span class="hlt">model</span> of the whole mantle obtained using a large three component surface and body waveform dataset and an iterative inversion for structure and source parameters based on Nonlinear Asymptotic Coupling Theory (NACT) (Li and Romanowicz, 1995). The <span class="hlt">model</span> is parameterized by isotropic VS up to spherical harmonic degree 24 and ξ (ξ = VSH2 / VSV2), a measurement of radial anisotropy in shear <span class="hlt">velocity</span>, up to degree 16. While the isotropic portion of the <span class="hlt">model</span> is consistent with previous shear <span class="hlt">velocity</span> tomographic <span class="hlt">models</span>, the anisotropic portion suggests relationships between flow and anisotropy in a vairety of depth ranges. In the uppermost mantle, we confirm observations of regions with VSH}>V{SV starting at ˜80 km under oceanic regions and ˜250 km under old continental lithosphere, suggesting horizontal flow beneath the lithosphere (Gung et al., 2003). We also observe a VSV}>V{SH signature at ˜200-300 km depth beneath major ridge systems with amplitude significantly correlated with spreading rate for fast-spreading segments. In the transition zone (400-700 km depth), regions of subducted slab material are associated with VSV}>V{SH. We also confirm the observation of strong radially symmetric VSH}>V{SV in the lowermost 300 km (Panning and Romanowicz, 2004). The 3D deviations from this degree 0 signature are associated with the transition to the large-scale low-<span class="hlt">velocity</span> superplumes under the central Pacific and Africa, suggesting that VSH}>V{SV is generated in the predominant horizontal flow of a mechanical boundary layer, with a change in signature related to transition to upwelling at the superplumes. We also solve for source perturbations in an interative procedure. Source perturbations are generally small compared to published Harvard CMT solutions, but significantly improve the fit to the data. The sources in the circum-Pacific subduction zones show small but clearly systematic shifts in location due to an improved structural</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1617..152W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1617..152W"><span id="translatedtitle">The thin section rock physics: <span class="hlt">Modeling</span> and measurement of seismic wave <span class="hlt">velocity</span> on the slice of carbonates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wardaya, P. D.; Noh, K. A. B. M.; Yusoff, W. I. B. W.; Ridha, S.; Nurhandoko, B. E. B.</p> <p>2014-09-01</p> <p>This paper discusses a new approach for investigating the seismic wave <span class="hlt">velocity</span> of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic <span class="hlt">velocity</span> measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave <span class="hlt">velocity</span> when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the <span class="hlt">modeling</span>, an advanced technique based on artificial neural network was employed for building the <span class="hlt">velocity</span> and density profile, replacing image's RGB pixel value with the seismic <span class="hlt">velocity</span> and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective <span class="hlt">velocities</span> were drawn from the recorded signal and being compared to the <span class="hlt">velocity</span> <span class="hlt">modeling</span> from Wyllie time average <span class="hlt">model</span> and Kuster-Toksoz rock physics <span class="hlt">model</span>. To perform the <span class="hlt">modeling</span>, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for <span class="hlt">velocity</span> <span class="hlt">modeling</span> were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured <span class="hlt">velocity</span> as compared to the Wyllie time average <span class="hlt">model</span>. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics <span class="hlt">model</span> for estimating the effective seismic wave</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22307902','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22307902"><span id="translatedtitle">The thin section rock physics: <span class="hlt">Modeling</span> and measurement of seismic wave <span class="hlt">velocity</span> on the slice of carbonates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wardaya, P. D. Noh, K. A. B. M. Yusoff, W. I. B. W.; Ridha, S.; Nurhandoko, B. E. B.</p> <p>2014-09-25</p> <p>This paper discusses a new approach for investigating the seismic wave <span class="hlt">velocity</span> of rock, specifically carbonates, as affected by their pore structures. While the conventional routine of seismic <span class="hlt">velocity</span> measurement highly depends on the extensive laboratory experiment, the proposed approach utilizes the digital rock physics view which lies on the numerical experiment. Thus, instead of using core sample, we use the thin section image of carbonate rock to measure the effective seismic wave <span class="hlt">velocity</span> when travelling on it. In the numerical experiment, thin section images act as the medium on which wave propagation will be simulated. For the <span class="hlt">modeling</span>, an advanced technique based on artificial neural network was employed for building the <span class="hlt">velocity</span> and density profile, replacing image's RGB pixel value with the seismic <span class="hlt">velocity</span> and density of each rock constituent. Then, ultrasonic wave was simulated to propagate in the thin section image by using finite difference time domain method, based on assumption of an acoustic-isotropic medium. Effective <span class="hlt">velocities</span> were drawn from the recorded signal and being compared to the <span class="hlt">velocity</span> <span class="hlt">modeling</span> from Wyllie time average <span class="hlt">model</span> and Kuster-Toksoz rock physics <span class="hlt">model</span>. To perform the <span class="hlt">modeling</span>, image analysis routines were undertaken for quantifying the pore aspect ratio that is assumed to represent the rocks pore structure. In addition, porosity and mineral fraction required for <span class="hlt">velocity</span> <span class="hlt">modeling</span> were also quantified by using integrated neural network and image analysis technique. It was found that the Kuster-Toksoz gives the closer prediction to the measured <span class="hlt">velocity</span> as compared to the Wyllie time average <span class="hlt">model</span>. We also conclude that Wyllie time average that does not incorporate the pore structure parameter deviates significantly for samples having more than 40% porosity. Utilizing this approach we found a good agreement between numerical experiment and theoretically derived rock physics <span class="hlt">model</span> for estimating the effective seismic wave</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=origin+AND+algebra&pg=3&id=EJ458199','ERIC'); return false;" href="http://eric.ed.gov/?q=origin+AND+algebra&pg=3&id=EJ458199"><span id="translatedtitle">Inequalities, <span class="hlt">Absolute</span> Value, and Logical Connectives.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Parish, Charles R.</p> <p>1992-01-01</p> <p>Presents an approach to the concept of <span class="hlt">absolute</span> value that alleviates students' problems with the traditional definition and the use of logical connectives in solving related problems. Uses a <span class="hlt">model</span> that maps numbers from a horizontal number line to a vertical ray originating from the origin. Provides examples solving <span class="hlt">absolute</span> value equations and…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19964671','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19964671"><span id="translatedtitle"><span class="hlt">Modeling</span> of friction force based on relative <span class="hlt">velocity</span> between liver tissue and needle for needle insertion simulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kobayashi, Yo; Sato, Takahiro; Fujie, Masakatsu G</p> <p>2009-01-01</p> <p>Needle insertion treatments require accurate placement of the needle tip into the target cancer. However, it is difficult to insert the needle into the cancer because of cancer displacement due to the organ deformation. Then, a path planning using needle insertion simulation to analyze the deformation of the organ is important for the accurate needle insertion. A frictional <span class="hlt">model</span> for needle insertion simulation is presented in this report. In particular, we focus on a <span class="hlt">model</span> of frictional force based on the relative <span class="hlt">velocity</span> between the needle and liver tissue ranging from hyper slow <span class="hlt">velocity</span>. First, in vitro experiments using hog liver were performed at several relative <span class="hlt">velocities</span> in order to measure the <span class="hlt">velocity</span> dependence of the frictional force. Several needle insertion experiments were performed under identical conditions in order to deal with the variance of experimental data. The 60 frictional force data were used to obtain average data at each relative <span class="hlt">velocity</span>. Second, the <span class="hlt">model</span> of frictional force was developed using the averages of the experimental results. This <span class="hlt">model</span> is defined according to the relative <span class="hlt">velocity</span> ranging from hyper slow <span class="hlt">velocity</span>. Finally, an evaluation experiment was carried out. The data obtained by the evaluation experiment reveals that the frictional force changes according to the relative <span class="hlt">velocity</span> between the needle and liver tissue. The experimental results support the validity of proposed <span class="hlt">model</span> of frictional force. PMID:19964671</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AAS...22734119W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AAS...22734119W"><span id="translatedtitle">Using A New <span class="hlt">Model</span> for Main Sequence Turnoff <span class="hlt">Absolute</span> Magnitudes to Measure Stellar Streams in the Milky Way Halo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weiss, Jake; Newberg, Heidi Jo; Arsenault, Matthew; Bechtel, Torrin; Desell, Travis; Newby, Matthew; Thompson, Jeffery M.</p> <p>2016-01-01</p> <p>Statistical photometric parallax is a method for using the distribution of <span class="hlt">absolute</span> magnitudes of stellar tracers to statistically recover the underlying density distribution of these tracers. In previous work, statistical photometric parallax was used to trace the Sagittarius Dwarf tidal stream, the so-called bifurcated piece of the Sagittaritus stream, and the Virgo Overdensity through the Milky Way. We use an improved knowledge of this distribution in a new algorithm that accounts for the changes in the stellar population of color-selected stars near the photometric limit of the Sloan Digital Sky Survey (SDSS). Although we select bluer main sequence turnoff stars (MSTO) as tracers, large color errors near the survey limit cause many stars to be scattered out of our selection box and many fainter, redder stars to be scattered into our selection box. We show that we are able to recover parameters for analogues of these streams in simulated data using a maximum likelihood optimization on MilkyWay@home. We also present the preliminary results of fitting the density distribution of major Milky Way tidal streams in SDSS data. This research is supported by generous gifts from the Marvin Clan, Babette Josephs, Manit Limlamai, and the MilkyWay@home volunteers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.S23C2724B&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.S23C2724B&link_type=ABSTRACT"><span id="translatedtitle">Assessing waveform predictions of recent three-dimensional <span class="hlt">velocity</span> <span class="hlt">models</span> of Tibet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bao, X.; Shen, Y.</p> <p>2015-12-01</p> <p>High-resolution tomographic <span class="hlt">models</span> are essential for understanding the physical and compositional properties in the lithosphere and obtaining accurate earthquake source locations and moment tensors. Yet, there are significant disagreements in recent three-dimensional <span class="hlt">velocity</span> <span class="hlt">models</span> of the crust and uppermost mantle in Tibet. Question also remains as to whether <span class="hlt">models</span> constructed from one type of seismic waves (body or surface waves) can be used to predict travel times and waveforms of another. In this study, six global or regional <span class="hlt">models</span> are selected for Tibet, most of which became publically available in the past five years. A three-dimensional finite-difference method in the spherical coordinates is applied to simulate full-wave propagation of regional Pn (with periods longer than 1 second) and Rayleigh waves (20-75 s period) for ground-truth events located at regional distances. The <span class="hlt">models</span> are evaluated based on the phase delays and cross-correlation coefficients between synthetic and observed waveforms. A <span class="hlt">model</span> generated from full-wave ambient noise tomography by Shen and Zhang (2012) consistently produces the best predictions for Rayleigh waves throughout the dataset and the Pn waves for the paths from the Tarim Basin to central Tibet. LITHO1.0, inverted from surface wave dispersions, shows a relatively stable but intermediate performance in predicting Pn and Rayleigh waves. None of the <span class="hlt">models</span> provide the best matches to both waves throughout the region. Furthermore, the <span class="hlt">models</span> constructed from surface waves are not well suited to predict Pn, and vice versa. We attribute this mainly to lack of accurate constraints on radial anisotropy and Vp/Vs ratios in the upper mantle, and Moho topography. We conclude that simultaneous prediction for P, S, and surface waves requires an integrated <span class="hlt">velocity</span> <span class="hlt">model</span> constructed with multiple seismic waveforms and consideration of other important properties, such as anisotropy and attenuation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...799..215P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...799..215P"><span id="translatedtitle">A Global <span class="hlt">Model</span> of The Light Curves and Expansion <span class="hlt">Velocities</span> of Type II-plateau Supernovae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pejcha, Ondřej; Prieto, Jose L.</p> <p>2015-02-01</p> <p>We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of Type II-Plateau supernovae based on their expansion <span class="hlt">velocities</span> and photometric measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and <span class="hlt">velocities</span>. We simultaneously fit ~230 <span class="hlt">velocity</span> and ~6800 mag measurements distributed over 21 photometric passbands spanning wavelengths from 0.19 to 2.2 μm. The light-curve differences among the Type II-Plateau supernovae are well <span class="hlt">modeled</span> by assuming different rates of photospheric radius expansion, which we explain as different density profiles of the ejecta, and we argue that steeper density profiles result in flatter plateaus, if everything else remains unchanged. The steep luminosity decline of Type II-Linear supernovae is due to fast evolution of the photospheric temperature, which we verify with a successful fit of SN 1980K. Eliminating the need for theoretical supernova atmosphere <span class="hlt">models</span>, we obtain self-consistent relative distances, reddenings, and nickel masses fully accounting for all internal <span class="hlt">model</span> uncertainties and covariances. We use our global fit to estimate the time evolution of any missing band tailored specifically for each supernova, and we construct spectral energy distributions and bolometric light curves. We produce bolometric corrections for all filter combinations in our sample. We compare our <span class="hlt">model</span> to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard \\mathscr{R}_V˜ 3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22364301','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22364301"><span id="translatedtitle">A GLOBAL <span class="hlt">MODEL</span> OF THE LIGHT CURVES AND EXPANSION <span class="hlt">VELOCITIES</span> OF TYPE II-PLATEAU SUPERNOVAE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pejcha, Ondřej; Prieto, Jose L.</p> <p>2015-02-01</p> <p>We present a new self-consistent and versatile method that derives photospheric radius and temperature variations of Type II-Plateau supernovae based on their expansion <span class="hlt">velocities</span> and photometric measurements. We apply the method to a sample of 26 well-observed, nearby supernovae with published light curves and <span class="hlt">velocities</span>. We simultaneously fit ∼230 <span class="hlt">velocity</span> and ∼6800 mag measurements distributed over 21 photometric passbands spanning wavelengths from 0.19 to 2.2 μm. The light-curve differences among the Type II-Plateau supernovae are well <span class="hlt">modeled</span> by assuming different rates of photospheric radius expansion, which we explain as different density profiles of the ejecta, and we argue that steeper density profiles result in flatter plateaus, if everything else remains unchanged. The steep luminosity decline of Type II-Linear supernovae is due to fast evolution of the photospheric temperature, which we verify with a successful fit of SN 1980K. Eliminating the need for theoretical supernova atmosphere <span class="hlt">models</span>, we obtain self-consistent relative distances, reddenings, and nickel masses fully accounting for all internal <span class="hlt">model</span> uncertainties and covariances. We use our global fit to estimate the time evolution of any missing band tailored specifically for each supernova, and we construct spectral energy distributions and bolometric light curves. We produce bolometric corrections for all filter combinations in our sample. We compare our <span class="hlt">model</span> to the theoretical dilution factors and find good agreement for the B and V filters. Our results differ from the theory when the I, J, H, or K bands are included. We investigate the reddening law toward our supernovae and find reasonable agreement with standard R{sub V}∼3.1 reddening law in UBVRI bands. Results for other bands are inconclusive. We make our fitting code publicly available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RAA....16g...1T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RAA....16g...1T"><span id="translatedtitle">Systematic comparison of initial <span class="hlt">velocities</span> for neutron stars in different <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taani, Ali</p> <p>2016-07-01</p> <p>I have studied the initial <span class="hlt">velocity</span> (Maxwellian and exponential distributions) and the scale height of isolated old (aged ≥ 109 yr) neutron stars (NSs) at different Galactocentric distances R in three population <span class="hlt">models</span>. The smooth time-independent 3-D axisymmetric gravitational potentials (Miyamoto-Nagai and Paczyński <span class="hlt">models</span>) were also used. The correlation between these quantities significantly affects the shapes of the profiles and distributions of the simulated sample, because the differences in the initial kick can arise from differences in the formation and evolution of NSs with other physical parameters. The scale height of the density distribution increases systematically with R. I have also shown that the distribution of old NSs in these population <span class="hlt">models</span> agrees with the observed structure of the Galaxy in terms of initial <span class="hlt">velocities</span> (1-D and 3-D), as well as the scale height distributions. These distributions tend to have an asymptotic behavior at the point R = 2.75 kpc. This means that the quality of the <span class="hlt">models</span> can be described in terms of a mean of the fitted Gaussian, and this could also give an overall perspective of the phase space properties of nearby old NSs on a given gravitational potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvA..91f3607N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvA..91f3607N"><span id="translatedtitle">Maximum group <span class="hlt">velocity</span> in a one-dimensional <span class="hlt">model</span> with a sinusoidally varying staggered potential</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nag, Tanay; Sen, Diptiman; Dutta, Amit</p> <p>2015-06-01</p> <p>We use Floquet theory to study the maximum value of the stroboscopic group <span class="hlt">velocity</span> in a one-dimensional tight-binding <span class="hlt">model</span> subjected to an on-site staggered potential varying sinusoidally in time. The results obtained by numerically diagonalizing the Floquet operator are analyzed using a variety of analytical schemes. In the low-frequency limit we use adiabatic theory, while in the high-frequency limit the Magnus expansion of the Floquet Hamiltonian turns out to be appropriate. When the magnitude of the staggered potential is much greater or much less than the hopping, we use degenerate Floquet perturbation theory; we find that dynamical localization occurs in the former case when the maximum group <span class="hlt">velocity</span> vanishes. Finally, starting from an "engineered" initial state where the particles (taken to be hard-core bosons) are localized in one part of the chain, we demonstrate that the existence of a maximum stroboscopic group <span class="hlt">velocity</span> manifests in a light-cone-like spreading of the particles in real space.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JDE...260.7093F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JDE...260.7093F"><span id="translatedtitle">Periodic solutions for a 1D-<span class="hlt">model</span> with nonlocal <span class="hlt">velocity</span> via mass transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferreira, Lucas C. F.; Valencia-Guevara, Julio C.</p> <p>2016-05-01</p> <p>This paper concerns periodic solutions for a 1D-<span class="hlt">model</span> with nonlocal <span class="hlt">velocity</span> given by the periodic Hilbert transform. There is a rich literature showing, via numerics and rigorous analysis, that this <span class="hlt">model</span> presents singular behavior of solutions. For instance, they can blow up by forming mass-concentration. We develop a global well-posedness theory for periodic measure initial data that allows, in particular, to analyze how the <span class="hlt">model</span> evolves from those singularities. Our results are based on periodic mass transport theory and the abstract gradient flow theory in metric spaces developed by Ambrosio et al. (2005). A viscous version of the <span class="hlt">model</span> is also analyzed and inviscid limit properties are obtained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApCM...23..857S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApCM...23..857S&link_type=ABSTRACT"><span id="translatedtitle">Simulation of High <span class="hlt">Velocity</span> Impact on Composite Structures - <span class="hlt">Model</span> Implementation and Validation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schueler, Dominik; Toso-Pentecôte, Nathalie; Voggenreiter, Heinz</p> <p>2016-08-01</p> <p>High <span class="hlt">velocity</span> impact on composite aircraft structures leads to the formation of flexural waves that can cause severe damage to the structure. Damage and failure can occur within the plies and/or in the resin rich interface layers between adjacent plies. In the present paper a <span class="hlt">modelling</span> methodology is documented that captures intra- and inter-laminar damage and their interrelations by use of shell element layers representing sub-laminates that are connected with cohesive interface layers to simulate delamination. This approach allows the simulation of large structures while still capturing the governing damage mechanisms and their interactions. The paper describes numerical algorithms for the implementation of a Ladevèze continuum damage <span class="hlt">model</span> for the ply and methods to derive input parameters for the cohesive zone <span class="hlt">model</span>. By comparison with experimental results from gas gun impact tests the potential and limitations of the <span class="hlt">modelling</span> approach are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApCM..tmp...25S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApCM..tmp...25S"><span id="translatedtitle">Simulation of High <span class="hlt">Velocity</span> Impact on Composite Structures - <span class="hlt">Model</span> Implementation and Validation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schueler, Dominik; Toso-Pentecôte, Nathalie; Voggenreiter, Heinz</p> <p>2016-05-01</p> <p>High <span class="hlt">velocity</span> impact on composite aircraft structures leads to the formation of flexural waves that can cause severe damage to the structure. Damage and failure can occur within the plies and/or in the resin rich interface layers between adjacent plies. In the present paper a <span class="hlt">modelling</span> methodology is documented that captures intra- and inter-laminar damage and their interrelations by use of shell element layers representing sub-laminates that are connected with cohesive interface layers to simulate delamination. This approach allows the simulation of large structures while still capturing the governing damage mechanisms and their interactions. The paper describes numerical algorithms for the implementation of a Ladevèze continuum damage <span class="hlt">model</span> for the ply and methods to derive input parameters for the cohesive zone <span class="hlt">model</span>. By comparison with experimental results from gas gun impact tests the potential and limitations of the <span class="hlt">modelling</span> approach are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoJI.202..224A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoJI.202..224A"><span id="translatedtitle">A lithospheric <span class="hlt">velocity</span> <span class="hlt">model</span> for the flat slab region of Argentina from joint inversion of Rayleigh wave phase <span class="hlt">velocity</span> dispersion and teleseismic receiver functions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ammirati, Jean-Baptiste; Alvarado, Patricia; Beck, Susan</p> <p>2015-07-01</p> <p>In the central Andes, the Nazca plate displays large along strike variations in dip with a near horizontal subduction angle between 28 and 32°S referred to the Pampean flat slab segment. The upper plate above the Pampean flat slab has high rates of crustal seismicity and active basement cored uplifts. The SIEMBRA experiment, a 43-broad-band-seismic-station array was deployed to better characterize the Pampean flat slab region around 31°S. In this study, we explore the lithospheric structure above the flat slab as a whole and its relation to seismicity. We use the SIEMBRA data to perform a joint inversion of teleseismic receiver functions and Rayleigh wave phase <span class="hlt">velocity</span> dispersion to constrain the shear wave <span class="hlt">velocity</span> variations in the lithosphere. Our joint inversion results show: (1) the presence of several upper-plate mid-crustal discontinuities and their lateral extent that are probably related to the terrane accretion history; (2) zones of high shear wave <span class="hlt">velocity</span> in the upper-plate lower crust associated with a weak Moho signal consistent with the hypothesis of partial eclogitization in the lower crust; (3) the presence of low shear-wave <span class="hlt">velocities</span> at ˜100 km depth interpreted as the subducting oceanic crust. Finally, in order to investigate the relation of the lithospheric structure to seismicity, we determine an optimal <span class="hlt">velocity</span>-depth <span class="hlt">model</span> based on the joint inversion results and use it to perform regional moment tensor inversions (SMTI) of crustal and slab earthquakes. The SMTI for 18 earthquakes that occurred between 2007 and 2009 in the flat slab region below Argentina, indicates systematically shallower focal depths for slab earthquakes (compared with inversions using previous <span class="hlt">velocity</span> <span class="hlt">models</span>). This suggests that the slab seismicity is concentrated mostly between 90 and 110 km depths within the subducting Nazca plate's oceanic crust and likely related to dehydration. In addition, the slab earthquakes exhibit extensional focal mechanisms suggesting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92f2830I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92f2830I"><span id="translatedtitle">Flow instability originating from particle configurations using the two-dimensional optimal <span class="hlt">velocity</span> <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ishiwata, Ryosuke; Sugiyama, Yuki</p> <p>2015-12-01</p> <p>The two-dimensional optimal <span class="hlt">velocity</span> <span class="hlt">model</span> has potential applications to pedestrian dynamics and the collective motion of animals. In this paper, we extend the linear stability analysis presented in a previous paper [A Nakayama et al., Phys. Rev. E. 77, 016105 (2008), 10.1103/PhysRevE.77.016105] and investigate the effects of particle configuration on the stability of several wave modes of collective oscillations of moving particles. We find that, when a particle moves without interacting with particles that are positioned in a diagonally forward or backward direction, the stable region of the particle flow is completely removed by the elliptically polarized mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...516572M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...516572M"><span id="translatedtitle">Two-dimensional airflow <span class="hlt">modeling</span> underpredicts the wind <span class="hlt">velocity</span> over dunes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michelsen, Britt; Strobl, Severin; Parteli, Eric J. R.; Pöschel, Thorsten</p> <p>2015-11-01</p> <p>We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind <span class="hlt">velocity</span> over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune’s symmetry axis — that is, over the equivalent transverse dune of same size. This finding suggests that the <span class="hlt">modeling</span> of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4647835','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4647835"><span id="translatedtitle">Two-dimensional airflow <span class="hlt">modeling</span> underpredicts the wind <span class="hlt">velocity</span> over dunes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Michelsen, Britt; Strobl, Severin; Parteli, Eric J. R.; Pöschel, Thorsten</p> <p>2015-01-01</p> <p>We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind <span class="hlt">velocity</span> over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune’s symmetry axis — that is, over the equivalent transverse dune of same size. This finding suggests that the <span class="hlt">modeling</span> of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected. PMID:26572966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26572966','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26572966"><span id="translatedtitle">Two-dimensional airflow <span class="hlt">modeling</span> underpredicts the wind <span class="hlt">velocity</span> over dunes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Michelsen, Britt; Strobl, Severin; Parteli, Eric J R; Pöschel, Thorsten</p> <p>2015-01-01</p> <p>We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind <span class="hlt">velocity</span> over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune's symmetry axis - that is, over the equivalent transverse dune of same size. This finding suggests that the <span class="hlt">modeling</span> of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected. PMID:26572966</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..118.2025E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..118.2025E"><span id="translatedtitle">An experimental investigation of <span class="hlt">velocity</span> fields in divergent glottal <span class="hlt">models</span> of the human vocal tract</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Erath, Byron D.; Plesniak, Michael W.</p> <p>2005-09-01</p> <p>In speech, sound production arises from fluid-structure interactions within the larynx as well as viscous flow phenomena that is most likely to occur during the divergent orientation of the vocal folds. Of particular interest are the flow mechanisms that influence the location of flow separation points on the vocal folds walls. Physiologically scaled pulsatile flow fields in 7.5 times real size static divergent glottal <span class="hlt">models</span> were investigated. Three divergence angles were investigated using phase-averaged particle image velocimetry (PIV). The pulsatile glottal jet exhibited a bi-modal stability toward both glottal walls, although there was a significant amount of variance in the angle the jet deflected from the midline. The attachment of the Coanda effect to the glottal <span class="hlt">model</span> walls occurred when the pulsatile <span class="hlt">velocity</span> was a maximum, and the acceleration of the waveform was zero. The location of the separation and reattachment points of the flow from the glottal <span class="hlt">models</span> was a function of the <span class="hlt">velocity</span> waveform and divergence angle. Acoustic analogies show that a dipole sound source contribution arising from the fluid interaction (Coanda jet) with the vocal fold walls is expected. [Work funded by NIH Grant RO1 DC03577.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvD..93d3534M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016PhRvD..93d3534M&link_type=ABSTRACT"><span id="translatedtitle">Extending the <span class="hlt">velocity</span>-dependent one-scale <span class="hlt">model</span> for domain walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martins, C. J. A. P.; Rybak, I. Yu.; Avgoustidis, A.; Shellard, E. P. S.</p> <p>2016-02-01</p> <p>We report on an extensive study of the evolution of domain wall networks in Friedmann-Lemaître-Robertson-Walker universes by means of the largest currently available field-theory simulations. These simulations were done in 40963 boxes and for a range of different fixed expansion rates, as well as for the transition between the radiation and matter eras. A detailed comparison with the <span class="hlt">velocity</span>-dependent one-scale <span class="hlt">model</span> shows that this cannot accurately reproduce the results of the entire range of simulated regimes if one assumes that the phenomenological energy loss and momentum parameters are constants. We therefore discuss how a more accurate <span class="hlt">modeling</span> of these parameters can be done, specifically by introducing an additional mechanism of energy loss (scalar radiation, which is particularly relevant for regimes with relatively little damping) and a modified momentum parameter which is a function of <span class="hlt">velocity</span> (in analogy to what was previously done for cosmic strings). We finally show that this extended <span class="hlt">model</span>, appropriately calibrated, provides an accurate fit to our simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.S33A1754S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.S33A1754S"><span id="translatedtitle">Improved Near-surface <span class="hlt">Velocity</span> <span class="hlt">Models</span> from Waveform Tomography Applied to Vibroseis MCS Reflection Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smithyman, B.; Clowes, R. M.</p> <p>2009-12-01</p> <p>Multichannel vibroseis reflection surveys are prevalent in the land exploration seismic industry because of benefits in speed and cost, along with reduced environmental impact when compared to explosive sources. Since the downgoing energy must travel through the shallow subsurface, an improved <span class="hlt">model</span> of near-surface <span class="hlt">velocity</span> can in theory substantially improve the resolution of deeper reflections. We describe techniques aimed at allowing the use of vibroseis data for long-offset refraction processing of first-arrival traveltimes and waveforms. Refraction processing of surface vibroseis data is typically limited to near-offset refraction statics. <span class="hlt">Velocity</span> <span class="hlt">models</span> of the shallow subsurface can be built to facilitate CDP stacking and migration, but these <span class="hlt">models</span> are typically coarse and of limited use for interpretation. Waveform tomography combines inversion of first-arrival traveltime data with full waveform inversion of densely-sampled refracted arrivals. Since inversion of the waveform amplitude and phase is not limited by the ray-theory approximation, identification of low-<span class="hlt">velocity</span> zones and small scattering targets is possible. Incorporating a wide range of offsets is critical for a more complete characterization of the near-surface. Because of the use of a non-linear frequency-domain approach to the solution of this inverse problem, low data frequencies are important in comparison with conventional reflection processing. Through the use of waveform tomography, we plan to build useful, detailed near-surface <span class="hlt">velocity</span> <span class="hlt">models</span> for both the reflection work flow and direct interpretation. Several difficulties exist in first-arrival analysis and waveform inversion of vibroseis data. The mixed-phase vibroseis source signature exhibits variations in phase with offset that are difficult to quantify without detailed a priori knowledge of the near-surface. This causes difficulties with picking and initial <span class="hlt">model</span> building, which is critical for non-linear waveform inversion. A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.4496O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.4496O"><span id="translatedtitle">Possibilities of <span class="hlt">modelling</span> of local and global hydrological changes from high-resolution Global Hydrological <span class="hlt">Model</span> in the <span class="hlt">absolute</span> gravity observations - the case of Józefosław Observatory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olszak, Tomasz; Barlik, Marcin; Pachuta, Andrzej; Próchniewicz, Dominik</p> <p>2014-05-01</p> <p>Geodynamical use of epoch gravimetric relative and <span class="hlt">absolute</span> observations requires the elimination of one from the most significant effect related to local and global changes of hydrological conditions. It is understood that hydrological effect is associated with changes in groundwater levels and soil moisture around the gravimetric station. In Poland, the quasi - permanent observations of gravity changes by <span class="hlt">absolute</span> method carried out since 2005 on gravity station located in the Astronomical - Geodetic Observatory in Józefosław. In the poster will be shortly described measurement strategy of <span class="hlt">absolute</span> observations and different approaches to the elimination of the local and global effects associated with changes in hydrology. This paper will discuss the results of the analysis of tidal observations relevant to the development of <span class="hlt">absolute</span> observations - seasonal changes in barometric correction factor and differences in the locally designated tidal corrections <span class="hlt">model</span>. Analysis of the possibility of elimination the impact of global hydrological influence is based on the <span class="hlt">model</span> GLDAS a spatial resolution of 0.25 degree independently on a local scale and global. Józefosław Observatory is equipped with additional sensors linked to the monitoring of local hydrological conditions. It gives a possibility to verify the quality of <span class="hlt">modeling</span> of hydrological changes using global <span class="hlt">models</span> in local and global scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......220H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......220H"><span id="translatedtitle">Vibrationally-Fluidized Granular Flows: Impact and Bulk <span class="hlt">Velocity</span> Measurements Compared with Discrete Element and Continuum <span class="hlt">Models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hashemnia, Kamyar</p> <p></p> <p>A new laser displacement probe was developed to measure the impact <span class="hlt">velocities</span> of particles within vibrationally-fluidized beds. The sensor output was also used to measure bulk flow <span class="hlt">velocity</span> along the probe window and to provide a measure of the media packing. The displacement signals from the laser sensors were analyzed to obtain the probability distribution functions of the impact <span class="hlt">velocity</span> of the particles. The impact <span class="hlt">velocity</span> was affected by the orientation of the laser probe relative to the bulk flow <span class="hlt">velocity</span>, and the density and elastic properties of the granular media. The impact <span class="hlt">velocities</span> of the particles were largely independent of their bulk flow speed and packing density. Both the local impact and bulk flow <span class="hlt">velocities</span> within a tub vibratory finisher were predicted using discrete element <span class="hlt">modelling</span> (DEM) and compared to the measured values for spherical steel media. It was observed that the impact and bulk flow <span class="hlt">velocities</span> were relatively insensitive to uncertainties in the contact coefficients of friction and restitution. It was concluded that the predicted impact and bulk flow <span class="hlt">velocities</span> were dependent on the number of layers in the <span class="hlt">model</span>. Consequently, the final DE <span class="hlt">model</span> mimicked the key aspects of the experimental setup, including the submerged laser sensor. The DE method predictions of both impact <span class="hlt">velocity</span> and bulk flow <span class="hlt">velocity</span> were in reasonable agreement with the experimental measurements, with maximum differences of 20% and 30%, respectively. Discrete element <span class="hlt">modeling</span> of granular flows is effective, but requires large numerical <span class="hlt">models</span>. In an effort to reduce computational effort, this work presents a finite element (FE) continuum <span class="hlt">model</span> of a vibrationally-fluidized granular flow. The constitutive equations governing the continuum <span class="hlt">model</span> were calibrated using the discrete element method (DEM). The bulk flow behavior of the equivalent continuum media was then studied using both Lagrangian and Eulerian FE formulations. The bulk flow <span class="hlt">velocities</span> predicted</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/37138','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/37138"><span id="translatedtitle">Determination of a shallow <span class="hlt">velocity</span>-depth <span class="hlt">model</span> from seismic refraction data by coherence inversion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Landa, E.; Keydar, S.; Kravtsov, A.</p> <p>1995-02-01</p> <p>Seismic refractions have different applications in seismic prospecting. The travel-times of refracted waves can be observed as first breaks on shot records and used for field static calculation. A new method for constructing a near-surface <span class="hlt">model</span> from refraction events is described. It does not require event picking on prestack records and is not based on any approximation of arrival times. It consists of the maximization of the semblance coherence measure computed using shot gathers in a time window along refraction traveltimes. Time curves are generated by ray tracing through the <span class="hlt">model</span>. The initial <span class="hlt">model</span> for the inversion was constructed by the intercept-time method. Apparent <span class="hlt">velocities</span> and intercept times were taken from a refraction stacked section. Such a section can be obtained by applying linear moveout corrections to common-shot records. The technique is tested successfully on synthetic and real data. An important application of the proposed method for solving the statics problem is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015VSD....53.1555S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015VSD....53.1555S"><span id="translatedtitle">Rear wheel torque vectoring <span class="hlt">model</span> predictive control with <span class="hlt">velocity</span> regulation for electric vehicles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Siampis, Efstathios; Velenis, Efstathios; Longo, Stefano</p> <p>2015-11-01</p> <p>In this paper we propose a constrained optimal control architecture for combined <span class="hlt">velocity</span>, yaw and sideslip regulation for stabilisation of the vehicle near the limit of lateral acceleration using the rear axle electric torque vectoring configuration of an electric vehicle. A nonlinear vehicle and tyre <span class="hlt">model</span> are used to find reference steady-state cornering conditions and design two <span class="hlt">model</span> predictive control (MPC) strategies of different levels of fidelity: one that uses a linearised version of the full vehicle <span class="hlt">model</span> with the rear wheels' torques as the input, and another one that neglects the wheel dynamics and uses the rear wheels' slips as the input instead. After analysing the relative trade-offs between performance and computational effort, we compare the two MPC strategies against each other and against an unconstrained optimal control strategy in Simulink and Carsim environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AAS...22541904S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AAS...22541904S"><span id="translatedtitle">Comparing the 2MTF and 6dFGS Peculiar <span class="hlt">Velocity</span> Surveys to <span class="hlt">models</span> from redshift surveys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Springob, Christopher M.; Hong, Tao; Magoulas, Christina; Colless, Matthew; Staveley-Smith, Lister; Erdogdu, Pirin; Jones, D. Heath; Lucey, John R.; Masters, Karen; Mould, Jeremy R.; Jarrett, Tom; Koribalski, Baerbel; Macri, Lucas M.; Scrimgeour, Morag</p> <p>2015-01-01</p> <p>The 6dF Galaxy Survey (6dFGS) and 2MASS Tully-Fisher Survey (2MTF) are large galaxy peculiar <span class="hlt">velocity</span> surveys of the local universe, providing distances and peculiar <span class="hlt">velocities</span> for thousands of galaxies, derived via the Fundamental Plane and Tully-Fisher relations respectively. We compare these observed <span class="hlt">velocity</span> fields to reconstructed peculiar <span class="hlt">velocity</span> field <span class="hlt">models</span> derived from redshift surveys such as the 2MASS Redshift Survey (2MRS) and the IRAS Point Source Redshift Survey (PSCz), addressing the question of whether the galaxy distribution traces the matter distribution, and whether the observed <span class="hlt">velocity</span> fields include a "residual bulk flow" not predicted by the <span class="hlt">models</span>. This research was conducted by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.S52D..06F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.S52D..06F"><span id="translatedtitle">Obtaining high-quality Love wave phase-<span class="hlt">velocity</span> <span class="hlt">models</span> from USArray data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foster, A. E.; Ekstrom, G.; Nettles, M.; Hjorleifsdottir, V.</p> <p>2012-12-01</p> <p>High-quality Love and Rayleigh wave <span class="hlt">models</span> are desirable for the constraints they provide on Earth structure, particularly radially anisotropic structure. Many Rayleigh wave <span class="hlt">models</span> have been constructed, but Love wave <span class="hlt">models</span> are more limited in number. Working with Love waves involves additional challenges that make it difficult to acquire and interpret high-quality measurements. Compared with Rayleigh waves, these include higher noise levels on the horizontal components, stronger sensitivity to the heterogeneous crustal structure, and greater interference from higher modes. This typically results in smaller data sets and larger uncertainties in single-station phase measurements for Love waves. We have constructed a data set of two-station phase measurements, based on differencing single-station phase measurements following Ekström et al. (1997). We inverted the two-station measurements to obtain phase-<span class="hlt">velocity</span> maps for both Love and Rayleigh waves at discrete periods from 25-100 s. Comparing equivalent estimates of the uncertainty for two-station measurements and single-station measurements, we find a marked reduction in uncertainty for two-station Rayleigh wave measurements, but a smaller improvement for Love waves. Here, we investigate some of the causes of the higher uncertainty in the Love wave <span class="hlt">models</span>, using both the two-station method and a mini-array method of estimating the local phase <span class="hlt">velocity</span>. We compare observed data from the USArray Transportable Array and synthetic data from numerical <span class="hlt">modeling</span>. The synthetic data is calculated using both SPECFEM3D_GLOBE, a finite-element method that should reproduce many wavefield effects, and normal mode summation, which allows us to isolate fundamental-mode signals. With these tools, we identify approaches that are likely to produce the highest-quality measurements and <span class="hlt">models</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1231575-absolute-path-command','SCIGOV-ESTSC'); return false;" href="http://www.osti.gov/scitech/biblio/1231575-absolute-path-command"><span id="translatedtitle">The <span class="hlt">absolute</span> path command</span></a></p> <p><a target="_blank" href=""></a></p> <p></p> <p>2012-05-11</p> <p>The ap command traveres all symlinks in a given file, directory, or executable name to identify the final <span class="hlt">absolute</span> path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the <span class="hlt">absolute</span> path to a relative directory from the current working directory.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1231575','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1231575"><span id="translatedtitle">The <span class="hlt">absolute</span> path command</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Moody, A.</p> <p>2012-05-11</p> <p>The ap command traveres all symlinks in a given file, directory, or executable name to identify the final <span class="hlt">absolute</span> path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the <span class="hlt">absolute</span> path to a relative directory from the current working directory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.204.1620R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.204.1620R"><span id="translatedtitle">Shear wave <span class="hlt">velocity</span> and Poisson's ratio <span class="hlt">models</span> across the southern Chile convergent margin at 38°15'S</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramos, C.; Mechie, J.; Feng, M.</p> <p>2016-03-01</p> <p>Using active and passive seismology data we derive a shear (S) wave <span class="hlt">velocity</span> <span class="hlt">model</span> and a Poisson's ratio (σ) <span class="hlt">model</span> across the Chilean convergent margin along a profile at 38°15'S, where the Mw 9.5 Valdivia earthquake occurred in 1960. The derived S-wave <span class="hlt">velocity</span> <span class="hlt">model</span> was constructed using three independently obtained <span class="hlt">velocity</span> <span class="hlt">models</span> that were merged together. In the upper part of the profile (0-2 km depth), controlled source data from explosions were used to obtain an S-wave traveltime tomogram. For the middle part (2-20 km depth), data from a temporary seismology array were used to carry out a dispersion analysis. The resulting dispersion curves were used to obtain a 3-D S-wave <span class="hlt">velocity</span> <span class="hlt">model</span>. In the lower part (20-75 km depth, depending on the longitude), an already existent local earthquake tomographic image was merged with the other two sections. This final S-wave <span class="hlt">velocity</span> <span class="hlt">model</span> and already existent compressional (P) wave <span class="hlt">velocity</span> <span class="hlt">models</span> along the same transect allowed us to obtain a Poisson's ratio <span class="hlt">model</span>. The results of this study show that the <span class="hlt">velocities</span> and Poisson's ratios in the continental crust of this part of the Chilean convergent margin are in agreement with geological features inferred from other studies and can be explained in terms of normal rock types. There is no requirement to call on the existence of measurable amounts of present-day fluids, in terms of seismic <span class="hlt">velocities</span>, above the plate interface in the continental crust of the Coastal Cordillera and the Central Valley in this part of the Chilean convergent margin. This is in agreement with a recent <span class="hlt">model</span> of water being transported down and released from the subduction zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26651690','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26651690"><span id="translatedtitle"><span class="hlt">Velocity</span> and displacement statistics in a stochastic <span class="hlt">model</span> of nonlinear friction showing bounded particle speed.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menzel, Andreas M</p> <p>2015-11-01</p> <p>Diffusion of colloidal particles in a complex environment such as polymer networks or biological cells is a topic of high complexity with significant biological and medical relevance. In such situations, the interaction between the surroundings and the particle motion has to be taken into account. We analyze a simplified diffusion <span class="hlt">model</span> that includes some aspects of a complex environment in the framework of a nonlinear friction process: at low particle speeds, friction grows linearly with the particle <span class="hlt">velocity</span> as for regular viscous friction; it grows more than linearly at higher particle speeds; finally, at a maximum of the possible particle speed, the friction diverges. In addition to bare diffusion, we study the influence of a constant drift force acting on the diffusing particle. While the corresponding stationary <span class="hlt">velocity</span> distributions can be derived analytically, the displacement statistics generally must be determined numerically. However, as a benefit of our <span class="hlt">model</span>, analytical progress can be made in one case of a special maximum particle speed. The effect of a drift force in this case is analytically determined by perturbation theory. It will be interesting in the future to compare our results to real experimental systems. One realization could be magnetic colloidal particles diffusing through a shear-thickening environment such as starch suspensions, possibly exposed to an external magnetic field gradient. PMID:26651690</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826..204Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826..204Y"><span id="translatedtitle">Revised <span class="hlt">Model</span> of the Steady-state Solar Wind Halo Electron <span class="hlt">Velocity</span> Distribution Function</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoon, Peter H.; Kim, Sunjung; Choe, G. S.; moon, Y.-J.</p> <p>2016-08-01</p> <p>A recent study discussed the steady-state <span class="hlt">model</span> for solar wind electrons during quiet time conditions. The electrons emanating from the Sun are treated in a composite three-population model—the low-energy Maxwellian core with an energy range of tens of eV, the intermediate ∼102–103 eV energy-range (“halo”) electrons, and the high ∼103–105 eV energy-range (“super-halo”) electrons. In the <span class="hlt">model</span>, the intermediate energy halo electrons are assumed to be in resonance with transverse EM fluctuations in the whistler frequency range (∼102 Hz), while the high-energy super-halo electrons are presumed to be in steady-state wave–particle resonance with higher-frequency electrostatic fluctuations in the Langmuir frequency range (∼105 Hz). A comparison with STEREO and WIND spacecraft data was also made. However, ignoring the influence of Langmuir fluctuations on the halo population turns out to be an unjustifiable assumption. The present paper rectifies the previous approach by including both Langmuir and whistler fluctuations in the construction of the steady-state <span class="hlt">velocity</span> distribution function for the halo population, and demonstrates that the role of whistler-range fluctuation is minimal unless the fluctuation intensity is arbitrarily raised. This implies that the Langmuir-range fluctuations, known as the quasi thermal noise, are important for both halo and super-halo electron <span class="hlt">velocity</span> distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MNRAS.452.2269R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MNRAS.452.2269R"><span id="translatedtitle">A Gaussian process framework for <span class="hlt">modelling</span> stellar activity signals in radial <span class="hlt">velocity</span> data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rajpaul, V.; Aigrain, S.; Osborne, M. A.; Reece, S.; Roberts, S.</p> <p>2015-09-01</p> <p>To date, the radial <span class="hlt">velocity</span> (RV) method has been one of the most productive techniques for detecting and confirming extrasolar planetary candidates. Unfortunately, stellar activity can induce RV variations which can drown out or even mimic planetary signals - and it is notoriously difficult to <span class="hlt">model</span> and thus mitigate the effects of these activity-induced nuisance signals. This is expected to be a major obstacle to using next-generation spectrographs to detect lower mass planets, planets with longer periods, and planets around more active stars. Enter Gaussian processes (GPs) which, we note, have a number of attractive features that make them very well suited to disentangling stellar activity signals from planetary signals. We present here a GP framework we developed to <span class="hlt">model</span> RV time series jointly with ancillary activity indicators (e.g. bisector <span class="hlt">velocity</span> spans, line widths, chromospheric activity indices), allowing the activity component of RV time series to be constrained and disentangled from e.g. planetary components. We discuss the mathematical details of our GP framework, and present results illustrating its encouraging performance on both synthetic and real RV data sets, including the publicly available Alpha Centauri B data set.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSM51B4258P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSM51B4258P"><span id="translatedtitle">Solar wind acceleration obtained from kinetic <span class="hlt">models</span> based on electron <span class="hlt">velocity</span> distribution functions with suprathermal particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pierrard, V.; Pieters, M.; Lazar, M.; Voitenko, Y.; Lamy, H.; Echim, M.</p> <p>2014-12-01</p> <p>Astrophysical and space plasmas are commonly found to be out ofthermal equilibrium, i.e., the <span class="hlt">velocity</span> distribution functions (VDF)of plasma particles cannot be described well enough by Maxwelliandistribution functions. The suprathermal populations are ubiquitousenhancing the high-energy tail of the distribution. A kinetic <span class="hlt">model</span> has been developed to successfullydescribe such plasmas with tails decreasing as a power law of thevelocity. In the present work, we show that a natural heating ofsolar and stellar coronas automatically appears when an enhancedpopulation of suprathermal particles is present at low altitude inthe solar (or stellar) atmosphere. This is true not only forelectrons and protons, but also for the minor ions which exhibit atemperature increase proportional to their mass. Moreover,suprathermal electrons contribute to the acceleration of stellarwinds to high bulk <span class="hlt">velocities</span> when Coulomb collisions are neglected.These results are illustrated by using a global <span class="hlt">model</span> of the solarcorona and solar wind based on VDF with suprathermal tails for thedifferent particle species. The energetic particles are non-collisional (without Coulomb collisions) even when thermalparticles are submitted to collisions. In the presence of long-rangecorrelations supplied by the fields and plasma instabilities,turbulence can play a role in the generation of such suprathermaltails. Solar wind observations are used as boundary conditions to determine the VDF in the other regions of the heliosphere. Consequences of suprathermal particles are also illustratedfor other space plasmas like the plasmasphere and the polar wind ofthe Earth and other planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...826..204Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ApJ...826..204Y&link_type=ABSTRACT"><span id="translatedtitle">Revised <span class="hlt">Model</span> of the Steady-state Solar Wind Halo Electron <span class="hlt">Velocity</span> Distribution Function</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoon, Peter H.; Kim, Sunjung; Choe, G. S.; moon, Y.-J.</p> <p>2016-08-01</p> <p>A recent study discussed the steady-state <span class="hlt">model</span> for solar wind electrons during quiet time conditions. The electrons emanating from the Sun are treated in a composite three-population model—the low-energy Maxwellian core with an energy range of tens of eV, the intermediate ˜102–103 eV energy-range (“halo”) electrons, and the high ˜103–105 eV energy-range (“super-halo”) electrons. In the <span class="hlt">model</span>, the intermediate energy halo electrons are assumed to be in resonance with transverse EM fluctuations in the whistler frequency range (˜102 Hz), while the high-energy super-halo electrons are presumed to be in steady-state wave–particle resonance with higher-frequency electrostatic fluctuations in the Langmuir frequency range (˜105 Hz). A comparison with STEREO and WIND spacecraft data was also made. However, ignoring the influence of Langmuir fluctuations on the halo population turns out to be an unjustifiable assumption. The present paper rectifies the previous approach by including both Langmuir and whistler fluctuations in the construction of the steady-state <span class="hlt">velocity</span> distribution function for the halo population, and demonstrates that the role of whistler-range fluctuation is minimal unless the fluctuation intensity is arbitrarily raised. This implies that the Langmuir-range fluctuations, known as the quasi thermal noise, are important for both halo and super-halo electron <span class="hlt">velocity</span> distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998EOSTr..79..278S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998EOSTr..79..278S"><span id="translatedtitle">Coronal Outflow <span class="hlt">Velocities</span> in a 3D Coronal <span class="hlt">Model</span> Determined from UVCS Doppler Dimming Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strachan, L.; Panasyuk, A. V.; Dobrzycka, D.; Gibson, S.; Biesecker, D. A.; Ko, Y.-K.; Galvin, A. B.; Romoli, M.; Kohn, J. L.</p> <p>1998-04-01</p> <p>We constrain coronal outflow <span class="hlt">velocity</span> solutions, resolved along the line-of-sight, by using Doppler dimming <span class="hlt">models</span> of H I Lyman alpha and O VI 1032/1037 Angstrom emissivities obtained with data from the Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO. The local emissivities, from heliocentric heights of 1.5 to 3.0 radii, were determined from 3-D reconstructions of line-of-sight intensities obtained during the Whole Sun Month Campaign (10 Aug. -- 8 Sep. 1996). The <span class="hlt">models</span> use electron densities derived from polarized brightness measurements made with the visible light coronagraphs on UVCS and LASCO, supplemented with data from Mark III at NCAR/MLSO. Electron temperature profiles are derived from `freezing-in' temperatures obtained from an analysis of charge state data from SWICS/Ulysses. The work concentrates on O5+ outflow <span class="hlt">velocities</span> which are determined from an analysis of the the O VI line ratios. This analysis is less sensitive to the uncertainties in the electron density and independent of the ionization balance and elemental abundance than the analyses which use individual spectral lines. This work is supported in part by NASA under grant NAG-3192 to the Smithsonian Astrophysical Observatory, by the Italian Space Agency and by Swiss funding agencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRB..120..359A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRB..120..359A"><span id="translatedtitle">S-<span class="hlt">velocity</span> <span class="hlt">model</span> and inferred Moho topography beneath the Antarctic Plate from Rayleigh waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>An, Meijian; Wiens, Douglas A.; Zhao, Yue; Feng, Mei; Nyblade, Andrew A.; Kanao, Masaki; Li, Yuansheng; Maggi, Alessia; Lévêque, Jean-Jacques</p> <p>2015-01-01</p> <p>Since 2007/2008, seismographs were deployed in many new locations across much of Antarctica. Using the records from 122 broadband seismic stations, over 10,000 Rayleigh wave fundamental-mode dispersion curves have been retrieved from earthquake waveforms and from ambient noise. Using the processed data set, a 3-D S-<span class="hlt">velocity</span> <span class="hlt">model</span> for the Antarctic lithosphere was constructed using a single-step surface wave tomographic method, and a Moho depth map was estimated from the <span class="hlt">model</span>. Using the derived crustal thicknesses, the average ratio of lithospheric mantle and crustal densities of Antarctica was calculated. The calculated density ratio indicates that the average crustal density for Antarctica is much higher than the average values for continental crust or the average density of lithospheric mantle is so low as to be equal to low-density bound of Archean lithosphere. The latter implies that the lithospheric mantle in much of Antarctica should be old and of Archean age. The East Antarctic Mountain Ranges (EAMOR) represent a thick crustal belt, with the thickest crust (~60 km) located close to Dome A. Very high <span class="hlt">velocities</span> can be found at depths greater than 200 km beneath parts of East Antarctica, demonstrating that the continental lithosphere extends deeper than 200 km. The very thick crust beneath the EAMOR may represent the collision suture of East Gondwana with Indo-Antarctica and West Gondwana during the Pan-African orogeny.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..92e2302M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..92e2302M"><span id="translatedtitle"><span class="hlt">Velocity</span> and displacement statistics in a stochastic <span class="hlt">model</span> of nonlinear friction showing bounded particle speed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menzel, Andreas M.</p> <p>2015-11-01</p> <p>Diffusion of colloidal particles in a complex environment such as polymer networks or biological cells is a topic of high complexity with significant biological and medical relevance. In such situations, the interaction between the surroundings and the particle motion has to be taken into account. We analyze a simplified diffusion <span class="hlt">model</span> that includes some aspects of a complex environment in the framework of a nonlinear friction process: at low particle speeds, friction grows linearly with the particle <span class="hlt">velocity</span> as for regular viscous friction; it grows more than linearly at higher particle speeds; finally, at a maximum of the possible particle speed, the friction diverges. In addition to bare diffusion, we study the influence of a constant drift force acting on the diffusing particle. While the corresponding stationary <span class="hlt">velocity</span> distributions can be derived analytically, the displacement statistics generally must be determined numerically. However, as a benefit of our <span class="hlt">model</span>, analytical progress can be made in one case of a special maximum particle speed. The effect of a drift force in this case is analytically determined by perturbation theory. It will be interesting in the future to compare our results to real experimental systems. One realization could be magnetic colloidal particles diffusing through a shear-thickening environment such as starch suspensions, possibly exposed to an external magnetic field gradient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.S42A..08B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.S42A..08B"><span id="translatedtitle">Community <span class="hlt">Velocity</span> <span class="hlt">Model</span> for the New Madrid Region, Central U.S.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boyd, O. S.</p> <p>2008-12-01</p> <p>In 1811-1812, a series of three major earthquakes struck the Central United States in the New Madrid Seismic Zone. Having magnitudes near 7.5 and being located within the relatively stable interior of the North American Continent, these events produced widespread strong shaking. If these events were to occur today, there would be substantial devastation to people, buildings and transportation and communication infrastructure. To better understand this threat and in preparation for the upcoming bicentennial, the US Geological Survey is planning to produce and support sophisticated numerical simulations of earthquake rupture and seismic wave propagation due to a repeat of these events. To kick off this effort, the USGS began the development and construction of a community seismic <span class="hlt">velocity</span> <span class="hlt">model</span> for use in these numerical simulations. We have collected existing research regarding the p- and s-wave <span class="hlt">velocities</span>, impedance contrasts and densities of the lithosphere in the New Madrid region and synthesized these results into a single <span class="hlt">model</span> that can be used in earthquake simulations. We have identified areas of missing or incomplete information for further study. The region covers an area of approximately 600,000 km2 from Little Rock, Arkansas across to Nashville Tennessee, up to St Louis, Missouri. The <span class="hlt">model</span> has currently been gridded at 3 km lateral resolution and from 5-m resolution near the surface to 10-km resolution at 100 km depth. Less but still substantial uncertainty exists for the Mississippi Embayment where a majority of the research has been done. Newer regional <span class="hlt">models</span> such as those by van der Lee and others and Liang and Langston have improved regional resolution beyond a 1-dimensional <span class="hlt">model</span>, but for ground motion simulations, greater resolution outside the Embayment is desired.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27547370','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27547370"><span id="translatedtitle">A comparison of <span class="hlt">absolute</span> performance of different correlative and mechanistic species distribution <span class="hlt">models</span> in an independent area.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shabani, Farzin; Kumar, Lalit; Ahmadi, Mohsen</p> <p>2016-08-01</p> <p>To investigate the comparative abilities of six different bioclimatic <span class="hlt">models</span> in an independent area, utilizing the distribution of eight different species available at a global scale and in Australia. Global scale and Australia. We tested a variety of bioclimatic <span class="hlt">models</span> for eight different plant species employing five discriminatory correlative species distribution <span class="hlt">models</span> (SDMs) including Generalized Linear <span class="hlt">Model</span> (GLM), MaxEnt, Random Forest (RF), Boosted Regression Tree (BRT), Bioclim, together with CLIMEX (CL) as a mechanistic niche <span class="hlt">model</span>. These <span class="hlt">models</span> were fitted using a training dataset of available global data, but with the exclusion of Australian locations. The capabilities of these techniques in projecting suitable climate, based on independent records for these species in Australia, were compared. Thus, Australia is not used to calibrate the <span class="hlt">models</span> and therefore it is as an independent area regarding geographic locations. To assess and compare performance, we utilized the area under the receiver operating characteristic (ROC) curves (AUC), true skill statistic (TSS), and fractional predicted areas for all SDMs. In addition, we assessed satisfactory agreements between the outputs of the six different bioclimatic <span class="hlt">models</span>, for all eight species in Australia. The <span class="hlt">modeling</span> method impacted on potential distribution predictions under current climate. However, the utilization of sensitivity and the fractional predicted areas showed that GLM, MaxEnt, Bioclim, and CL had the highest sensitivity for Australian climate conditions. Bioclim calculated the highest fractional predicted area of an independent area, while RF and BRT were poor. For many applications, it is difficult to decide which bioclimatic <span class="hlt">model</span> to use. This research shows that variable results are obtained using different SDMs in an independent area. This research also shows that the SDMs produce different results for different species; for example, Bioclim may not be good for one species but works better</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdWR...74...26L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdWR...74...26L"><span id="translatedtitle">An analytical <span class="hlt">model</span> for lateral depth-averaged <span class="hlt">velocity</span> distributions along a meander in curved compound channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Chao; Wright, Nigel; Liu, Xingnian; Yang, Kejun</p> <p>2014-12-01</p> <p>This paper presents an analytical method for <span class="hlt">modeling</span> the lateral depth-averaged <span class="hlt">velocity</span> distribution along a half-meander in a curved compound channel. An equation is derived from the momentum equation and the flow continuity equation which contains a <span class="hlt">velocity</span> term with both streamwise <span class="hlt">velocity</span> variation and lateral secondary flow variation. A <span class="hlt">velocity</span> variation parameter is proposed in the main channel and on the floodplain for a series of test sections. To study the validity of these equations experiments were conducted in a large scale meandering compound channel at Sichuan University, China. Based on the experimental data, the generation mechanism of secondary flow in the main channel along half a meander is analyzed. It is shown that the secondary current is enhanced by the centrifugal force and the floodplain flow. Due to the discontinuity of the flow depth and the effect of meandering in the main channel flow, a region divided method is adopted. A new boundary condition is proposed by introducing the angle between the main channel flow and the floodplain flow, and it is shown that this gives better <span class="hlt">modeling</span> results in cross-over sections. The <span class="hlt">modeling</span> results indicate that the proposed method, which uses the new boundary condition and includes both the streamwise <span class="hlt">velocity</span> variation and the lateral secondary flow variation, can <span class="hlt">model</span> the lateral depth-averaged <span class="hlt">velocity</span> distributions more accurately. Finally, variations in the <span class="hlt">velocity</span> term between the main channel and floodplain are discussed and analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JVGR..310..172S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JVGR..310..172S"><span id="translatedtitle">The oscillation <span class="hlt">model</span> of hydrothermal dynamics beneath Aso volcano, southwest Japan after small eruption on May 2011: A new understanding <span class="hlt">model</span> using repeated <span class="hlt">absolute</span> and relative gravity measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sofyan, Yayan; Nishijima, Jun; Fujimitsu, Yasuhiro; Yoshikawa, Shin; Kagiyama, Tsuneomi; Ohkura, Takahiro</p> <p>2016-01-01</p> <p>At the end of 2010, the seismic activity in Aso volcano intensely increased and water level in the Nakadake crater decreased until early in 2011, then was followed by a small eruption in May 2011. After the eruption and heavy rain, the volcanic activity subsided to calm period, crater bottom was refilled with water, and water level increased in the Nakadake crater. The next tremor reappeared in 2014 and tracked to eruption in November 2014. This eruptive pattern and water level variation in the crater repeatedly appeared on the surface, and it should be related to the hydrothermal dynamics beneath Aso volcano. We initiated the gravity measurements in relation to hydrothermal dynamics in the subsurface of Aso volcano using Scintrex CG-5 (549) and LaCoste Romberg type G-1016 relative gravimeter at 28 benchmarks in April 2011, one month before the eruption. The repeated gravity measurements continue to monitor Aso volcano with a series of the measurement after the eruption in every three months to a half year. We analyze the gravity variation from 2011 to 2014 between the time of the phreatic and strombolian eruption. The measurements covered the area more than 60 km2 in the west side of Aso caldera. A new gravity network was also installed in May 2010 at seven benchmarks using A10-017 <span class="hlt">absolute</span> gravimeter, which re-occupied in October 2010, June 2011 and two benchmarks in June 2014. As a result, the gravity changes distinguish hydrothermal dynamic in the subsurface, which has a direct correlation to water level fluctuation in the crater, after the first eruption and before the second discharge. The monitoring data notice large gravity changes between the surveys at benchmarks around Nakadake crater and Kusasenri area. The simple 3D inversion <span class="hlt">models</span> of the 4-D gravity data deduce the density contrast distribution beneath Aso volcano. The inversion and mass change result generate the oscillation typical as a new understanding <span class="hlt">model</span>. The variation of the mass shows a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435201','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4435201"><span id="translatedtitle">A New Open-Loop Fiber Optic Gyro Error Compensation Method Based on Angular <span class="hlt">Velocity</span> Error <span class="hlt">Modeling</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing</p> <p>2015-01-01</p> <p>With the open-loop fiber optic gyro (OFOG) <span class="hlt">model</span>, output voltage and angular <span class="hlt">velocity</span> can effectively compensate OFOG errors. However, the <span class="hlt">model</span> cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular <span class="hlt">velocities</span>. This paper puts forward a <span class="hlt">modeling</span> scheme with OFOG output voltage u and temperature T as the input variables and angular <span class="hlt">velocity</span> error Δω as the output variable. Firstly, the angular <span class="hlt">velocity</span> error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular <span class="hlt">velocity</span> error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network <span class="hlt">model</span>. Then the nonlinear mapping <span class="hlt">model</span> over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established <span class="hlt">model</span> can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular <span class="hlt">velocity</span> are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct <span class="hlt">modeling</span> of gyro angular <span class="hlt">velocity</span>, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.2%, respectively, so the performance of this method is better than that of the direct <span class="hlt">modeling</span> for gyro angular <span class="hlt">velocity</span>. PMID:25734642</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25734642','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25734642"><span id="translatedtitle">A new open-loop fiber optic gyro error compensation method based on angular <span class="hlt">velocity</span> error <span class="hlt">modeling</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Yanshun; Guo, Yajing; Li, Chunyu; Wang, Yixin; Wang, Zhanqing</p> <p>2015-01-01</p> <p>With the open-loop fiber optic gyro (OFOG) <span class="hlt">model</span>, output voltage and angular <span class="hlt">velocity</span> can effectively compensate OFOG errors. However, the <span class="hlt">model</span> cannot reflect the characteristics of OFOG errors well when it comes to pretty large dynamic angular <span class="hlt">velocities</span>. This paper puts forward a <span class="hlt">modeling</span> scheme with OFOG output voltage u and temperature T as the input variables and angular <span class="hlt">velocity</span> error Δω as the output variable. Firstly, the angular <span class="hlt">velocity</span> error Δω is extracted from OFOG output signals, and then the output voltage u, temperature T and angular <span class="hlt">velocity</span> error Δω are used as the learning samples to train a Radial-Basis-Function (RBF) neural network <span class="hlt">model</span>. Then the nonlinear mapping <span class="hlt">model</span> over T, u and Δω is established and thus Δω can be calculated automatically to compensate OFOG errors according to T and u. The results of the experiments show that the established <span class="hlt">model</span> can be used to compensate the nonlinear OFOG errors. The maximum, the minimum and the mean square error of OFOG angular <span class="hlt">velocity</span> are decreased by 97.0%, 97.1% and 96.5% relative to their initial values, respectively. Compared with the direct <span class="hlt">modeling</span> of gyro angular <span class="hlt">velocity</span>, which we researched before, the experimental results of the compensating method proposed in this paper are further reduced by 1.6%, 1.4% and 1.42%, respectively, so the performance of this method is better than that of the direct <span class="hlt">modeling</span> for gyro angular <span class="hlt">velocity</span>. PMID:25734642</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..SHK.C4004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..SHK.C4004B"><span id="translatedtitle">Validating Material <span class="hlt">Modelling</span> of OFHC Copper Using Dynamic Tensile Extrusion (DTE) Test at Different Impact <span class="hlt">Velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bonora, Nicola; Testa, Gabriel; Ruggiero, Andrew; Iannitti, Gianluca; Hörnqvist, Magnus; Mortazavi, Nooshin</p> <p>2015-06-01</p> <p>In the Dynamic Tensile Extrusion (DTE) test, the material is subjected to very large strain, high strain rate and elevated temperature. Numerical simulation, validated comparing with measurements obtained on soft-recovered extruded fragments, can be used to probe material response under such extreme conditions and to assess constitutive <span class="hlt">models</span>. In this work, the results of a parametric investigation on the simulation of DTE test of annealed OFHC copper - at impact <span class="hlt">velocity</span> ranging from 350 up to 420 m/s - using phenomenological and physically based <span class="hlt">models</span> (Johnson-Cook, Zerilli-Armstrong and Rusinek-Klepaczko), are presented. Preliminary simulation of microstructure evolution was performed using crystal plasticity package CPFEM, providing, as input, the strain history obtained with FEM at selected locations along the extruded fragments. Results were compared with EBSD investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21269162','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21269162"><span id="translatedtitle">EFFICIENT FITTING OF MULTIPLANET KEPLERIAN <span class="hlt">MODELS</span> TO RADIAL <span class="hlt">VELOCITY</span> AND ASTROMETRY DATA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wright, J. T.; Howard, A. W.</p> <p>2009-05-15</p> <p>We describe a technique for solving for the orbital elements of multiple planets from radial <span class="hlt">velocity</span> (RV) and/or astrometric data taken with 1 m s{sup -1} and {mu}as precision, appropriate for efforts to detect Earth-massed planets in their stars' habitable zones, such as NASA's proposed Space Interferometry Mission. We include details of calculating analytic derivatives for use in the Levenberg-Marquardt (LM) algorithm for the problems of fitting RV and astrometric data separately and jointly. We also explicate the general method of separating the linear and nonlinear components of a <span class="hlt">model</span> fit in the context of an LM fit, show how explicit derivatives can be calculated in such a <span class="hlt">model</span>, and demonstrate the speed up and convergence improvements of such a scheme in the case of a five-planet fit to published RV data for 55 Cnc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IJMPC..2650054C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IJMPC..2650054C"><span id="translatedtitle">An extended optimal <span class="hlt">velocity</span> difference <span class="hlt">model</span> in a cooperative driving system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Jinliang; Shi, Zhongke; Zhou, Jie</p> <p>2015-10-01</p> <p>An extended optimal <span class="hlt">velocity</span> (OV) difference <span class="hlt">model</span> is proposed in a cooperative driving system by considering multiple OV differences. The stability condition of the proposed <span class="hlt">model</span> is obtained by applying the linear stability theory. The results show that the increase in number of cars that precede and their OV differences lead to the more stable traffic flow. The Burgers, Korteweg-de Vries (KdV) and modified Korteweg-de Vries (mKdV) equations are derived to describe the density waves in the stable, metastable and unstable regions, respectively. To verify these theoretical results, the numerical simulation is carried out. The theoretical and numerical results show that the stabilization of traffic flow is enhanced by considering multiple OV differences. The traffic jams can be suppressed by taking more information of cars ahead.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21516780','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21516780"><span id="translatedtitle"><span class="hlt">Modelling</span> Viscoelastic Behaviour of Polymer by A Mixed <span class="hlt">Velocity</span>, Displacement Formulation - Numerical and Experimental Results</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pham, VT.; Silva, L.; Digonnet, H.; Combeaud, C.; Billon, N.; Coupez, T.</p> <p>2011-05-04</p> <p>The objective of this work is to <span class="hlt">model</span> the viscoelastic behaviour of polymer from the solid state to the liquid state. With this objective, we perform experimental tensile tests and compare with simulation results. The chosen polymer is a PMMA whose behaviour depends on its temperature. The computation simulation is based on Navier-Stokes equations where we propose a mixed finite element method with an interpolation P1+/P1 using displacement (or <span class="hlt">velocity</span>) and pressure as principal variables. The implemented technique uses a mesh composed of triangles (2D) or tetrahedra (3D). The goal of this approach is to <span class="hlt">model</span> the viscoelastic behaviour of polymers through a fluid-structure coupling technique with a multiphase approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARF50015M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARF50015M"><span id="translatedtitle">Prediction of the expansion <span class="hlt">velocity</span> of ultracold 1D quantum gases for integrable <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mei, Zhongtao; Vidmar, Lev; Heidrich-Meisner, Fabian; Bolech, Carlos</p> <p></p> <p>In the theory of Bethe-ansatz integrable quantum systems, rapidities play an important role as they are used to specify many-body states. The physical interpretation of rapidities going back to Sutherland is that they are the asymptotic momenta after letting a quantum gas expand into a larger volume rendering it dilute and noninteracting. We exploit this picture to calculate the expansion <span class="hlt">velocity</span> of a one-dimensional Fermi-Hubbard <span class="hlt">model</span> by using the distribution of rapidities defined by the initial state. Our results are consistent with the ones from time-dependent density-matrix renormalization. We show in addition that an approximate Bethe-ansatz solution works well also for the Bose-Hubbard <span class="hlt">model</span>. Our results are of interests for future sudden-expansion experiments with ultracold quantum gases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020079431','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020079431"><span id="translatedtitle">The <span class="hlt">Velocity</span> Distribution of Isolated Radio Pulsars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Arzoumanian, Z.; Chernoff, D. F.; Cordes, J. M.; White, Nicholas E. (Technical Monitor)</p> <p>2002-01-01</p> <p>We infer the <span class="hlt">velocity</span> distribution of radio pulsars based on large-scale 0.4 GHz pulsar surveys. We do so by <span class="hlt">modelling</span> evolution of the locations, <span class="hlt">velocities</span>, spins, and radio luminosities of pulsars; calculating pulsed flux according to a beaming <span class="hlt">model</span> and random orientation angles of spin and beam; applying selection effects of pulsar surveys; and comparing <span class="hlt">model</span> distributions of measurable pulsar properties with survey data using a likelihood function. The surveys analyzed have well-defined characteristics and cover approx. 95% of the sky. We maximize the likelihood in a 6-dimensional space of observables P, dot-P, DM, <span class="hlt">absolute</span> value of b, mu, F (period, period derivative, dispersion measure, Galactic latitude, proper motion, and flux density). The <span class="hlt">models</span> we test are described by 12 parameters that characterize a population's birth rate, luminosity, shutoff of radio emission, birth locations, and birth <span class="hlt">velocities</span>. We infer that the radio beam luminosity (i) is comparable to the energy flux of relativistic particles in <span class="hlt">models</span> for spin-driven magnetospheres, signifying that radio emission losses reach nearly 100% for the oldest pulsars; and (ii) scales approximately as E(exp 1/2) which, in magnetosphere <span class="hlt">models</span>, is proportional to the voltage drop available for acceleration of particles. We find that a two-component <span class="hlt">velocity</span> distribution with characteristic <span class="hlt">velocities</span> of 90 km/ s and 500 km/ s is greatly preferred to any one-component distribution; this preference is largely immune to variations in other population parameters, such as the luminosity or distance scale, or the assumed spin-down law. We explore some consequences of the preferred birth <span class="hlt">velocity</span> distribution: (1) roughly 50% of pulsars in the solar neighborhood will escape the Galaxy, while approx. 15% have <span class="hlt">velocities</span> greater than 1000 km/ s (2) observational bias against high <span class="hlt">velocity</span> pulsars is relatively unimportant for surveys that reach high Galactic <span class="hlt">absolute</span> value of z distances, but is severe for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012MarGR..33...17S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012MarGR..33...17S&link_type=ABSTRACT"><span id="translatedtitle">Using overlapping sonobuoy data from the Ross Sea to construct a 2D deep crustal <span class="hlt">velocity</span> <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Selvans, M. M.; Clayton, R. W.; Stock, J. M.; Granot, R.</p> <p>2012-03-01</p> <p>Sonobuoys provide an alternative to using long streamers while conducting multi-channel seismic (MCS) studies, in order to provide deeper <span class="hlt">velocity</span> control. We present analysis and <span class="hlt">modeling</span> techniques for interpreting the sonobuoy data and illustrate the method with ten overlapping sonobuoys collected in the Ross Sea, offshore from Antarctica. We demonstrate the importance of using the MCS data to correct for ocean currents and changes in ship navigation, which is required before using standard methods for obtaining a 1D <span class="hlt">velocity</span> profile from each sonobuoy. We verify our 1D <span class="hlt">velocity</span> <span class="hlt">models</span> using acoustic finite-difference (FD) <span class="hlt">modeling</span> and by performing depth migration on the data, and demonstrate the usefulness of FD <span class="hlt">modeling</span> for tying interval <span class="hlt">velocities</span> to the shallow crust imaged using MCS data. Finally, we show how overlapping sonobuoys along an MCS line can be used to construct a 2D <span class="hlt">velocity</span> <span class="hlt">model</span> of the crust. The <span class="hlt">velocity</span> <span class="hlt">model</span> reveals a thin crust (5.5 ± 0.4 km) at the boundary between the Adare and Northern Basins, and implies that the crustal structure of the Northern Basin may be more similar to that of the oceanic crust in the Adare Basin than to the stretched continental crust further south in the Ross Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1710976T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1710976T"><span id="translatedtitle">Petrophysical <span class="hlt">models</span> of high <span class="hlt">velocity</span> lower crust on the South Atlantic rifted margins: whence the asymmetry?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trumbull, Robert B.; Franke, Dieter; Bauer, Klaus; Sobolev, Stephan V.</p> <p>2015-04-01</p> <p>Lower crustal bodies with high seismic <span class="hlt">velocity</span> (Vp > 7km/s) underlie seaward-dipping reflector wedges on both margins of the South Atlantic, as on many other volcanic rifted margins worldwide. A comprehensive geophysical study of the South Atlantic margins by Becker et al. (Solid Earth, 5: 1011-1026, 2014) showed a strong asymmetry in the development of high-<span class="hlt">velocity</span> lower crust (HVLC), with about 4 times larger volumes of HVLC on the African margin. That study also found interesting variations in the vertical position of HVLC relative to seaward-dipping reflectors which question a simple intrusive vs. extrusive relationship between these lower- and upper crustal features. The asymmetry of HVLC volumes on the conjugate margins is paradoxically exactly the opposite to that of surface lavas in the Paraná-Etendeka flood basalt province, which are much more voluminous on the South American margin. This contribution highlights the asymmetric features of magma distribution on the South Atlantic margins and explores their geodynamic significance. Petrophysical <span class="hlt">models</span> of the HVLC are presented in the context of mantle melt generation, based on thickness-<span class="hlt">velocity</span> (H-Vp) relations. These suggest that the greater volumes and average Vp values of HVLC on the African margin are due to active upwelling and high temperature, whereas passive upwelling under a thick lithospheric lid suppressed magma generation on the South American margin. The contrast in mantle upwelling rate and lithospheric thickness on the two margins predictably causes differential uplift, and this may help explain the greater accomodation space for surface lavas on the South American side although melt generation was strongest under the African margin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IAUGA..2257286F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IAUGA..2257286F"><span id="translatedtitle">Stellar <span class="hlt">velocity</span> dispersions to z=2 and tests of stellar population <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franx, Marijn</p> <p>2015-08-01</p> <p>We have measured stellar <span class="hlt">velocity</span> dispersions of non-starforming galaxies to a redshift of 2, and we augment our sample with values from literature. We find that the galaxies lie on a well-defined mass Fundamental Plane. We establish a simple relation between restframe colors and mass-to-light ratio, and we show that the M/L can be estimated to 0.25 dex from a single restframe color. In addition, we compare the relation between color with predictions from stellar population <span class="hlt">models</span>. The galaxies span a wide range in restframe colors, and produce a stringest test of the <span class="hlt">models</span>. Whereas this test is a classic test of the shape of the IMF, we find thatpopulation <span class="hlt">models</span> from different authors show substantial differences, comparable to the variations between the predictions due to a different IMF. No single <span class="hlt">model</span> reproduces the mass-to-light variations in the visual and near-infrared satisfactorily, and a broken IMF <span class="hlt">models</span> produces the best results. Either the stellar populations are complex, or the <span class="hlt">models</span> need modification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdWR...92..271D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdWR...92..271D"><span id="translatedtitle">Predicting field-scale dispersion under realistic conditions with the polar Markovian <span class="hlt">velocity</span> process <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dünser, Simon; Meyer, Daniel W.</p> <p>2016-06-01</p> <p>In most groundwater aquifers, dispersion of tracers is dominated by flow-field inhomogeneities resulting from the underlying heterogeneous conductivity or transmissivity field. This effect is referred to as macrodispersion. Since in practice, besides a few point measurements the complete conductivity field is virtually never available, a probabilistic treatment is needed. To quantify the uncertainty in tracer concentrations from a given geostatistical <span class="hlt">model</span> for the conductivity, Monte Carlo (MC) simulation is typically used. To avoid the excessive computational costs of MC, the polar Markovian <span class="hlt">velocity</span> process (PMVP) <span class="hlt">model</span> was recently introduced delivering predictions at about three orders of magnitude smaller computing times. In artificial test cases, the PMVP <span class="hlt">model</span> has provided good results in comparison with MC. In this study, we further validate the <span class="hlt">model</span> in a more challenging and realistic setup. The setup considered is derived from the well-known benchmark macrodispersion experiment (MADE), which is highly heterogeneous and non-stationary with a large number of unevenly scattered conductivity measurements. Validations were done against reference MC and good overall agreement was found. Moreover, simulations of a simplified setup with a single measurement were conducted in order to reassess the <span class="hlt">model</span>'s most fundamental assumptions and to provide guidance for <span class="hlt">model</span> improvements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.S53C..06L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.S53C..06L"><span id="translatedtitle">Using Adjoint Methods to Improve 3-D <span class="hlt">Velocity</span> <span class="hlt">Models</span> of Southern California</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Q.; Tape, C.; Maggi, A.; Tromp, J.</p> <p>2006-12-01</p> <p>We use adjoint methods popular in climate and ocean dynamics to calculate Fréchet derivatives for tomographic inversions in southern California. The Fréchet derivative of an objective function χ(m), where m denotes the Earth <span class="hlt">model</span>, may be written in the generic form δχ=int Km(x) δln m(x) d3x, where δln m=δ m/m denotes the relative <span class="hlt">model</span> perturbation. For illustrative purposes, we construct the 3-D finite-frequency banana-doughnut kernel Km, corresponding to the misfit of a single traveltime measurement, by simultaneously computing the 'adjoint' wave field s† forward in time and reconstructing the regular wave field s backward in time. The adjoint wave field is produced by using the time-reversed <span class="hlt">velocity</span> at the receiver as a fictitious source, while the regular wave field is reconstructed on the fly by propagating the last frame of the wave field saved by a previous forward simulation backward in time. The approach is based upon the spectral-element method, and only two simulations are needed to produce density, shear-wave, and compressional-wave sensitivity kernels. This method is applied to the SCEC southern California <span class="hlt">velocity</span> <span class="hlt">model</span>. Various density, shear-wave, and compressional-wave sensitivity kernels are presented for different phases in the seismograms. We also generate 'event' kernels for Pnl, S and surface waves, which are the Fréchet kernels of misfit functions that measure the P, S or surface wave traveltime residuals at all the receivers simultaneously for one particular event. Effectively, an event kernel is a sum of weighted Fréchet kernels, with weights determined by the associated traveltime anomalies. By the nature of the 3-D simulation, every event kernel is also computed based upon just two simulations, i.e., its construction costs the same amount of computation time as an individual banana-doughnut kernel. One can think of the sum of the event kernels for all available earthquakes, called the 'misfit' kernel, as a graphical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JKPS...62...48L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JKPS...62...48L"><span id="translatedtitle">Influence of the pore fluid on the phase <span class="hlt">velocity</span> in bovine trabecular bone In Vitro: Prediction of the biot <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Kang Il</p> <p>2013-01-01</p> <p>The present study aims to investigate the influence of the pore fluid on the phase <span class="hlt">velocity</span> in bovine trabecular bone in vitro. The frequency-dependent phase <span class="hlt">velocity</span> was measured in 20 marrow-filled and water-filled bovine femoral trabecular bone samples. The mean phase <span class="hlt">velocities</span> at frequencies between 0.6 and 1.2 MHz exhibited significant negative dispersions for both the marrow-filled and the water-filled samples. The magnitudes of the dispersions showed no significant differences between the marrow-filled and the water-filled samples. In contrast, replacement of marrow by water led to a mean increase in the phase <span class="hlt">velocity</span> of 27 m/s at frequencies from 0.6 to 1.2 MHz. The theoretical phase <span class="hlt">velocities</span> of the fast wave predicted by using the Biot <span class="hlt">model</span> for elastic wave propagation in fluid-saturated porous media showed good agreements with the measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1009256','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1009256"><span id="translatedtitle">Role of <span class="hlt">Modeling</span> When Designing for <span class="hlt">Absolute</span> Energy Use Intensity Requirements in a Design-Build Framework: Preprint</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hirsch, A.; Pless, S.; Guglielmetti, R.; Torcellini, P. A.; Okada, D.; Antia, P.</p> <p>2011-03-01</p> <p>The Research Support Facility was designed to use half the energy of an equivalent minimally code-compliant building, and to produce as much renewable energy as it consumes on an annual basis. These energy goals and their substantiation through simulation were explicitly included in the project's fixed firm price design-build contract. The energy <span class="hlt">model</span> had to be continuously updated during the design process and to match the final building as-built to the greatest degree possible. Computer <span class="hlt">modeling</span> played a key role throughout the design process and in verifying that the contractual energy goals would be met within the specified budget. The main tool was a whole building energy simulation program. Other <span class="hlt">models</span> were used to provide more detail or to complement the whole building simulation tool. Results from these specialized <span class="hlt">models</span> were fed back into the main whole building simulation tool to provide the most accurate possible inputs for annual simulations. This paper will detail the <span class="hlt">models</span> used in the design process and how they informed important program and design decisions on the path from preliminary design to the completed building.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.S51A0994P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.S51A0994P"><span id="translatedtitle">Development of a Regional <span class="hlt">Velocity</span> <span class="hlt">Model</span> Using 3D Broadband Waveform Sensitivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panning, M. P.; Romanowicz, B. A.; Kim, A.</p> <p>2005-12-01</p> <p>We are developing a new approach which relies on a cascade of increasingly accurate theoretical approximations for computation of the seismic wavefield to develop a <span class="hlt">model</span> of regional seismic <span class="hlt">velocity</span> structure for eastern Eurasia using full seismic waveforms. The selected area is particularly suitable for the purpose of this experiment, as it is highly heterogeneous, presenting a challenge for standard <span class="hlt">modeling</span> techniques, but it is well surrounded by earthquake sources and a significant number of high quality broadband digital stations exist, for which data are readily accessible through IRIS (Incorporated Research Institutions for Seismology) and the FDSN (Federation of Digital Seismic Networks). The initial <span class="hlt">model</span> is derived from a large database of teleseismic long period waveforms (surface waves and overtone wavepackets) using well-developed theoretical approximations, the Path Average Approximation (PAVA) and Nonlinear Asymptotic Coupling Theory (NACT). These approaches assume waveforms are only sensitive to the 1D (PAVA) and 2D (NACT) structure in the vertical plane between source and receiver, which is adequate for the development of a smooth initial 3D <span class="hlt">velocity</span> <span class="hlt">model</span>. We refine this <span class="hlt">model</span> using a more accurate theoretical approach. We utilize an implementation of a 3D Born approximation, which takes into account the contribution to the waveform from single scattering throughout the <span class="hlt">model</span>, giving full 3D waveform sensitivity kernels. We perform verification tests of this approach for synthetic <span class="hlt">models</span>, and show that it can accurately represent the wavefield as predicted by numerical approaches in several situations where approximations such as PAVA and NACT are insufficient. The Born 3D waveform sensitivity kernels are used to perform a higher resolution inversion of regional waveforms for a smaller subregion between longitudes 90 and 150 degrees E, and latitudes 15 and 40 degrees N. To further increase the accuracy of this <span class="hlt">model</span>, we intend to utilize a very</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GeoJI.195..460M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GeoJI.195..460M"><span id="translatedtitle">An improved 1-D seismic <span class="hlt">velocity</span> <span class="hlt">model</span> for seismological studies in the Campania-Lucania region (Southern Italy)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matrullo, Emanuela; De Matteis, Raffaella; Satriano, Claudio; Amoroso, Ortensia; Zollo, Aldo</p> <p>2013-10-01</p> <p>We present a 1-D <span class="hlt">velocity</span> <span class="hlt">model</span> of the Earth's crust in Campania-Lucania region obtained by solving the coupled hypocentre-<span class="hlt">velocity</span> inverse problem for 1312 local earthquakes recorded at a dense regional network. The <span class="hlt">model</span> is constructed using the VELEST program, which calculates 1-D `minimum' <span class="hlt">velocity</span> <span class="hlt">model</span> from body wave traveltimes, together with station corrections, which account for deviations from the simple 1-D structure. The spatial distribution of station corrections correlates with the P-wave <span class="hlt">velocity</span> variations of a preliminary 3-D crustal <span class="hlt">velocity</span> <span class="hlt">model</span> that has been obtained from the tomographic inversion of the same data set of P traveltimes. We found that station corrections reflect not only inhomogeneous near-surface structures, but also larger-scale geological features associated to the transition between carbonate platform outcrops at Southwest and Miocene sedimentary basins at Northeast. We observe a significant trade-off between epicentral locations and station corrections, related to the existence of a thick low-<span class="hlt">velocity</span> layer to the NE. This effect is taken into account and minimized by re-computing station corrections, fixing the position of a subset of well-determined hypocentres, located in the 3-D tomographic <span class="hlt">model</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GeoJI.183..421Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010GeoJI.183..421Y&link_type=ABSTRACT"><span id="translatedtitle">Shallow low-<span class="hlt">velocity</span> zone of the San Jacinto fault from local earthquake waveform <span class="hlt">modelling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Hongfeng; Zhu, Lupei</p> <p>2010-10-01</p> <p>We developed a method to determine the depth extent of low-<span class="hlt">velocity</span> zone (LVZ) associated with a fault zone (FZ) using S-wave precursors from local earthquakes. The precursors are diffracted S waves around the edges of LVZ and their relative amplitudes to the direct S waves are sensitive to the LVZ depth. We applied the method to data recorded by three temporary arrays across three branches of the San Jacinto FZ. The FZ dip was constrained by differential traveltimes of P waves between stations at two side of the FZ. Other FZ parameters (width and <span class="hlt">velocity</span> contrast) were determined by <span class="hlt">modelling</span> waveforms of direct and FZ-reflected P and S waves. We found that the LVZ of the Buck Ridge fault branch has a width of ~150 m with a 30-40 per cent reduction in Vp and a 50-60 per cent reduction in Vs. The fault dips 70 +/- 5° to southwest and its LVZ extends only to 2 +/- 1 km in depth. The LVZ of the Clark Valley fault branch has a width of ~200 m with 40 per cent reduction in Vp and 50 per cent reduction in Vs. The Coyote Creek branch is nearly vertical and has a LVZ of ~150 m in width and of 25 per cent reduction in Vp and 50 per cent reduction in Vs. The LVZs of these three branches are not centred at the surface fault trace but are located to their northeast, indicating asymmetric damage during earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJWC..6702083N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJWC..6702083N"><span id="translatedtitle">Investigation of the <span class="hlt">velocity</span> distribution in the flow of a journal bearing <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nobis, Matthias; Reinke, Peter; Schmidt, Marcus; Riedel, Marco; Redlich, Marcel</p> <p>2014-03-01</p> <p>In many previous studies the main focus was put on the pressure distribution in the lubricating gap. Due to the limited space in the gap an investigation of the <span class="hlt">velocity</span> distribution is very difficult or rather impossible. Based on the geometrical shapes of a real journal bearing, a bearing <span class="hlt">model</span> test rig with an increased relative gap width has been developed. Thus, it is possible to detect the distribution of the flow speed within the gap by using a Laser Doppler Velocimeter (LDV). The comparability of the flow to the flow in a real journal bearing is ensured by observing the Reynolds similarity. Due to a targeted eccentricity in the system and the circumferential groove over 180°, there is in connection with the outlet hole in the rotating shaft a permanent change in the outflow conditions. The consequence is a periodically varying system pressure with effects to the pressure and volumetric flow rate at the inlet and outlet. The <span class="hlt">velocity</span> measurements with a triggered LDV are done by considering these transient boundary conditions at the system boundaries. In this paper the experimental setup, the expiration of the investigations and some exemplary results are presented. Attendant to the experiment, numerical simulations are carried out and the results are compared with the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SMaS...25e5026S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SMaS...25e5026S"><span id="translatedtitle">SMA actuators for vibration control and experimental determination of <span class="hlt">model</span> parameters dependent on ambient airflow <span class="hlt">velocity</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suzuki, Y.</p> <p>2016-05-01</p> <p>This article demonstrates the practical applicability of a method of <span class="hlt">modelling</span> shape memory alloys (SMAs) as actuators. For this study, a pair of SMA wires was installed in an antagonistic manner to form an actuator, and a linear differential equation that describes the behaviour of the actuator’s generated force relative to its input voltage was derived for the limited range below the austenite onset temperature. In this range, hysteresis need not be considered, and the proposed SMA actuator can therefore be practically applied in linear control systems, which is significant because large deformations accompanied by hysteresis do not necessarily occur in most vibration control cases. When specific values of the parameters used in the differential equation were identified experimentally, it became clear that one of the parameters was dependent on ambient airflow <span class="hlt">velocity</span>. The values of this dependent parameter were obtained using an additional SMA wire as a sensor. In these experiments, while the airflow distribution around the SMA wires was varied by changing the rotational speed of the fans in the wind tunnels, an input voltage was conveyed to the SMA actuator circuit, and the generated force was measured. In this way, the parameter dependent on airflow <span class="hlt">velocity</span> was estimated in real time, and it was validated that the calculated force was consistent with the measured one.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014TMP...178..347P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014TMP...178..347P"><span id="translatedtitle">Differential-geometric aspects of a nonholonomic Dirac mechanics: Lessons of a <span class="hlt">model</span> quadratic in <span class="hlt">velocities</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pavlov, V. P.</p> <p>2014-03-01</p> <p>Faddeev and Vershik proposed the Hamiltonian and Lagrangian formulations of constrained mechanical systems that are invariant from the differential geometry standpoint. In both formulations, the description is based on a nondegenerate symplectic 2-form defined on a cotangent bundle T*Q (in the Hamiltonian formulation) or on a tangent bundle TQ (in the Lagrangian formulation), and constraints are sets of functions in involution on these manifolds. We demonstrate that this technique does not allow "invariantization" of the Dirac procedure of constraint "proliferation." We show this in an example of a typical quantum field <span class="hlt">model</span> in which the original Lagrange function is a quadratic form in <span class="hlt">velocities</span> with a degenerate coefficient matrix. We postulate that the initial phase space is a manifold where all arguments of the action functional including the Lagrange multipliers are defined. The Lagrange multipliers can then be naturally interpreted physically as <span class="hlt">velocities</span> (in the Hamiltonian formulation) or momenta (in the Lagrangian formulation) related to "nonphysical" degrees of freedom. A quasisymplectic 2-form invariantly defined on such a manifold is degenerate. We propose new differential-geometric structures that allow formulating the Dirac procedure invariantly.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRB..119.4747R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRB..119.4747R"><span id="translatedtitle">Comprehensive observation and <span class="hlt">modeling</span> of earthquake and temperature-related seismic <span class="hlt">velocity</span> changes in northern Chile with passive image interferometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Richter, Tom; Sens-Schönfelder, Christoph; Kind, Rainer; Asch, Günter</p> <p>2014-06-01</p> <p>We report on earthquake and temperature-related <span class="hlt">velocity</span> changes in high-frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short-term <span class="hlt">velocity</span> drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long-term <span class="hlt">velocity</span> decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface-induced changes. Due to this high sensitivity, we observe a <span class="hlt">velocity</span> response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of <span class="hlt">velocity</span> drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual <span class="hlt">velocity</span> changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic <span class="hlt">velocity</span> with annual and daily periods indicate an atmospheric origin of the <span class="hlt">velocity</span> changes that we confirm with a <span class="hlt">model</span> based on thermally induced stress. This comprehensive <span class="hlt">model</span> explains the lag time dependence of the temperature-related seismic <span class="hlt">velocity</span> changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and <span class="hlt">velocity</span> change, plus autocorrelation sensitivity kernels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006GeoJI.167..361P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006GeoJI.167..361P"><span id="translatedtitle">A three-dimensional radially anisotropic <span class="hlt">model</span> of shear <span class="hlt">velocity</span> in the whole mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panning, Mark; Romanowicz, Barbara</p> <p>2006-10-01</p> <p>We present a 3-D radially anisotropic S <span class="hlt">velocity</span> <span class="hlt">model</span> of the whole mantle (SAW642AN), obtained using a large three component surface and body waveform data set and an iterative inversion for structure and source parameters based on Non-linear Asymptotic Coupling Theory (NACT). The <span class="hlt">model</span> is parametrized in level 4 spherical splines, which have a spacing of ~ 8°. The <span class="hlt">model</span> shows a link between mantle flow and anisotropy in a variety of depth ranges. In the uppermost mantle, we confirm observations of regions with VSH > VSV starting at ~80 km under oceanic regions and ~200 km under stable continental lithosphere, suggesting horizontal flow beneath the lithosphere. We also observe a VSV > VSH signature at ~150-300 km depth beneath major ridge systems with amplitude correlated with spreading rate for fast-spreading segments. In the transition zone (400-700 km depth), regions of subducted slab material are associated with VSV > VSH, while the ridge signal decreases. While the mid-mantle has lower amplitude anisotropy (<1 per cent), we also confirm the observation of radially symmetric VSH > VSV in the lowermost 300 km, which appears to be a robust conclusion, despite an error in our previous paper which has been corrected here. The 3-D deviations from this signature are associated with the large-scale low-<span class="hlt">velocity</span> superplumes under the central Pacific and Africa, suggesting that VSH > VSV is generated in the predominant horizontal flow of a mechanical boundary layer, with a change in signature related to transition to upwelling at the superplumes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15796343','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15796343"><span id="translatedtitle">Stabilizing PID controllers for a single-link biomechanical <span class="hlt">model</span> with position, <span class="hlt">velocity</span>, and force feedback.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Iqbal, Kamran; Roy, Anindo</p> <p>2004-12-01</p> <p>In this paper we address the problem of PID stabilization of a single-link inverted pendulum-based biomechanical <span class="hlt">model</span> with force feedback, two levels of position and <span class="hlt">velocity</span> feedback, and with delays in all the feedback loops. The novelty of the proposed <span class="hlt">model</span> lies in its physiological relevance, whereby both small and medium latency sensory feedbacks from muscle spindle (MS), and force feedback from Golgi tendon organ (GTO) are included in the formulation. The biomechanical <span class="hlt">model</span> also includes active and passive viscoelastic feedback from Hill-type muscle <span class="hlt">model</span> and a second-order low-pass function for muscle activation. The central nervous system (CNS) regulation of postural movement is represented by a proportional-integral-derivative (PID) controller. Padé approximation of delay terms is employed to arrive at an overall rational transfer function of the biomechanical <span class="hlt">model</span>. The Hermite-Biehler theorem is then used to derive stability results, leading to the existence of stabilizing PID controllers. An algorithm for selection of stabilizing feedback gains is developed using the linear matrix inequality (LMI) approach. PMID:15796343</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT........16V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT........16V"><span id="translatedtitle"><span class="hlt">Velocity</span> Resolved---Scalar <span class="hlt">Modeled</span> Simulations of High Schmidt Number Turbulent Transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verma, Siddhartha</p> <p></p> <p>The objective of this thesis is to develop a framework to conduct <span class="hlt">velocity</span> resolved - scalar <span class="hlt">modeled</span> (VR-SM) simulations, which will enable accurate simulations at higher Reynolds and Schmidt (Sc) numbers than are currently feasible. The framework established will serve as a first step to enable future simulation studies for practical applications. To achieve this goal, in-depth analyses of the physical, numerical, and <span class="hlt">modeling</span> aspects related to Sc " 1 are presented, specifically when <span class="hlt">modeling</span> in the viscous-convective subrange. Transport characteristics are scrutinized by examining scalar-<span class="hlt">velocity</span> Fourier mode interactions in Direct Numerical Simulation (DNS) datasets and suggest that scalar modes in the viscous-convective subrange do not directly affect large-scale transport for high Sc . Further observations confirm that discretization errors inherent in numerical schemes can be sufficiently large to wipe out any meaningful contribution from subfilter <span class="hlt">models</span>. This provides strong incentive to develop more effective numerical schemes to support high Sc simulations. To lower numerical dissipation while maintaining physically and mathematically appropriate scalar bounds during the convection step, a novel method of enforcing bounds is formulated, specifically for use with cubic Hermite polynomials. Boundedness of the scalar being transported is effected by applying derivative limiting techniques, and physically plausible single sub-cell extrema are allowed to exist to help minimize numerical dissipation. The proposed bounding algorithm results in significant performance gain in DNS of turbulent mixing layers and of homogeneous isotropic turbulence. Next, the combined physical/mathematical behavior of the subfilter scalar-flux vector is analyzed in homogeneous isotropic turbulence, by examining vector orientation in the strain-rate eigenframe. The results indicate no discernible dependence on the <span class="hlt">modeled</span> scalar field, and lead to the identification of the tensor</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980010520','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980010520"><span id="translatedtitle">Global Plate <span class="hlt">Velocities</span> from the Global Positioning System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Larson, Kristine M.; Freymueller, Jeffrey T.; Philipsen, Steven</p> <p>1997-01-01</p> <p>We have analyzed 204 days of Global Positioning System (GPS) data from the global GPS network spanning January 1991 through March 1996. On the basis of these GPS coordinate solutions, we have estimated <span class="hlt">velocities</span> for 38 sites, mostly located on the interiors of the Africa, Antarctica, Australia, Eurasia, Nazca, North America, Pacific, and South America plates. The uncertainties of the horizontal <span class="hlt">velocity</span> components range from 1.2 to 5.0 mm/yr. With the exception of sites on the Pacific and Nazca plates, the GPS <span class="hlt">velocities</span> agree with <span class="hlt">absolute</span> plate <span class="hlt">model</span> predictions within 95% confidence. For most of the sites in North America, Antarctica, and Eurasia, the agreement is better than 2 mm/yr. We find no persuasive evidence for significant vertical motions (less than 3 standard deviations), except at four sites. Three of these four were sites constrained to geodetic reference frame <span class="hlt">velocities</span>. The GPS <span class="hlt">velocities</span> were then used to estimate angular <span class="hlt">velocities</span> for eight tectonic plates. <span class="hlt">Absolute</span> angular <span class="hlt">velocities</span> derived from the GPS data agree with the no net rotation (NNR) NUVEL-1A <span class="hlt">model</span> within 95% confidence except for the Pacific plate. Our pole of rotation for the Pacific plate lies 11.5 deg west of the NNR NUVEL-1A pole, with an angular speed 10% faster. Our relative angular <span class="hlt">velocities</span> agree with NUVEL-1A except for some involving the Pacific plate. While our Pacific-North America angular <span class="hlt">velocity</span> differs significantly from NUVEL-1A, our <span class="hlt">model</span> and NUVEL-1A predict very small differences in relative motion along the Pacific-North America plate boundary itself. Our Pacific-Australia and Pacific- Eurasia angular <span class="hlt">velocities</span> are significantly faster than NUVEL-1A, predicting more rapid convergence at these two plate boundaries. Along the East Pacific Pise, our Pacific-Nazca angular <span class="hlt">velocity</span> agrees in both rate and azimuth with NUVFL-1A.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1637.1416H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1637.1416H"><span id="translatedtitle">Eddy current <span class="hlt">modeling</span> by finite element method for evaluation of mechanical properties of the structure cracked in <span class="hlt">absolute</span> probe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harzallah, Salaheddine; Chabaat, Mohamed; Belgacem, Fethi Bin Muhammad</p> <p>2014-12-01</p> <p>In this paper, a nondestructive evaluation by sensor Eddy current is used as a tool to control cracks and micro-cracks in materials. A simulation by a numerical approach based on the finite element method is employed to detect cracks in materials and eventually to study their propagation using a crucial parameter such as a Stress Intensity Factor (SIF). This method has emerged as one of the most efficient techniques for prospecting cracks in materials, evaluating SIFs and analyzing crack's growth in the context of linear elastic fracture mechanics (LEFM). This technique uses extrapolation of displacements from results compared with those obtained by the integral interaction. On the other hand, crack's growth is analyzed as a <span class="hlt">model</span> by combining the maximum circumferential stress criteria with the critical plane for predicting the direction of crack growth. Moreover, a constant crack growth increment is determined using the modified Paris's <span class="hlt">model</span>. Furthermore, stress intensity factors needed for these <span class="hlt">models</span> are calculated using the domain form of the J-integral interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoJI.tmp..222M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoJI.tmp..222M&link_type=ABSTRACT"><span id="translatedtitle">Horizontal and vertical <span class="hlt">velocities</span> derived from the IDS contribution to ITRF2014, and comparisons with geophysical <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreaux, G.; Lemoine, F. G.; Argus, D. F.; Santamaría-Gómez, A.; Willis, P.; Soudarin, L.; Gravelle, M.; Ferrage, P.</p> <p>2016-07-01</p> <p>In the context of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the IDS Combination Center estimated a cumulative DORIS position and <span class="hlt">velocity</span> solution to obtain mean horizontal and vertical motion of 160 stations at 71 DORIS sites. The main objective of this study is to validate the <span class="hlt">velocities</span> of the DORIS sites by comparison with external <span class="hlt">models</span> or time series. Horizontal <span class="hlt">velocities</span> are compared with two recent global plate <span class="hlt">models</span> (GEODVEL 2010 and NNR-MORVEL56). Prior to the comparisons, DORIS horizontal <span class="hlt">velocities</span> were corrected for Global Isostatic Adjustment (GIA) from the ICE-6G (VM5a) <span class="hlt">model</span>. For more than half of the sites, the DORIS horizontal <span class="hlt">velocities</span> differ from the global plate <span class="hlt">models</span> by less than 2-3 mm/yr. For five of the sites (Arequipa, Dionysos/Gavdos, Manila, Santiago) with horizontal <span class="hlt">velocity</span> differences wrt these <span class="hlt">models</span> larger than 10 mm/yr, comparisons with GNSS estimates show the veracity of the DORIS motions. Vertical motions from the DORIS cumulative solution are compared with the vertical <span class="hlt">velocities</span> derived from the latest GPS cumulative solution over the time span 1995.0-2014.0 from the University of La Rochelle (ULR6) solution at 31 co-located DORIS-GPS sites. These two sets of vertical <span class="hlt">velocities</span> show a correlation coefficient of 0.83. Vertical differences are larger than 2 mm/yr at 23 percent of the sites. At Thule the disagreement is explained by fine-tuned DORIS discontinuities in line with the mass variations of outlet glaciers. Furthermore, the time evolution of the vertical time series from the DORIS station in Thule show similar trends to the GRACE equivalent water height.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SolE....6..271G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SolE....6..271G"><span id="translatedtitle">A 3-D shear <span class="hlt">velocity</span> <span class="hlt">model</span> of the southern North American and Caribbean plates from ambient noise and earthquake tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaite, B.; Villaseñor, A.; Iglesias, A.; Herraiz, M.; Jiménez-Munt, I.</p> <p>2015-02-01</p> <p>We use group <span class="hlt">velocities</span> from earthquake tomography together with group and phase <span class="hlt">velocities</span> from ambient noise tomography (ANT) of Rayleigh waves to invert for the 3-D shear-wave <span class="hlt">velocity</span> structure (5-70 km) of the Caribbean (CAR) and southern North American (NAM) plates. The lithospheric <span class="hlt">model</span> proposed offers a complete image of the crust and uppermost-mantle with imprints of the tectonic evolution. One of the most striking features inferred is the main role of the Ouachita-Marathon-Sonora orogeny front on the crustal seismic structure of the NAM plate. A new imaged feature is the low crustal <span class="hlt">velocities</span> along the USA-Mexico border. The <span class="hlt">model</span> also shows a break of the east-west mantle <span class="hlt">velocity</span> dichotomy of the NAM and CAR plates beneath the Isthmus of the Tehuantepec and the Yucatan Block. High upper-mantle <span class="hlt">velocities</span> along the Mesoamerican Subduction Zone coincide with inactive volcanic areas while the lowest <span class="hlt">velocities</span> correspond to active volcanic arcs and thin lithospheric mantle regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.V11F..06V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.V11F..06V"><span id="translatedtitle">Measurement of <span class="hlt">Absolute</span> Carbon Isotope Ratios: Mechanisms and Implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vogel, J. S.; Giacomo, J. A.; Dueker, S. R.</p> <p>2012-12-01</p> <p>An accelerator mass spectrometer (AMS) produced <span class="hlt">absolute</span> isotope ratio measurements for 14C/13C as tested against >500 samples of NIST SRM-4990-C (OxII 14C standard) to an accuracy of 2.2±0.6‰ over a period of one year with measurements made to 1% counting statistics. The spectrometer is not maximized for 13C/12C, but measured ∂13C to 0.4±0.1‰ accuracy, with known methods for improvement. An AMS produces elemental anions from a sputter ion source and includes a charge-changing collision in a gas cell to isolate the rare 14C from the common isotopes and molecular isobars. Both these physical processes have been <span class="hlt">modeled</span> to determine the parameters providing such <span class="hlt">absolute</span> measures. Neutral resonant ionization in a cesium plasma produces mass-independent ionization, while <span class="hlt">velocity</span> dependent charge-state distributions in gas collisions produce relative ion beam intensities that are linear in mass at specific collision energies. The mechanisms are not specific to carbon isotopes, but stand alone <span class="hlt">absolute</span> IRMS (AIR-MS) instruments have not yet been made. Aside from the obvious applications in metrology, AIR-MS is particularly valuable in coupled separatory MS because no internal or external standards are required. Sample definition processes can be compared, even if no exact standard reference sample exists. Isotope dilution measurements do not require standards matching the dilution end-points and can be made over an extended, even extrapolated, range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70015901','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70015901"><span id="translatedtitle">Particle <span class="hlt">velocity</span> interpolation in block-centered finite difference groundwater flow <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Goode, D.J.</p> <p>1990-01-01</p> <p>Reviews linear and bilinear interpolation of <span class="hlt">velocity</span> and introduces a new interpolation scheme. Linear interpolation of <span class="hlt">velocity</span> is consistent with the numerical solution of the flow equation and preserves discontinuities in <span class="hlt">velocity</span> caused by abrupt (blocky) changes in transmissivity or hydraulic conductivity. However, linear interpolation yields discontinuous and somewhat unrealistic <span class="hlt">velocities</span> in homogeneous aquifers. Bilinear interpolation of <span class="hlt">velocity</span> yields continuous and realistic <span class="hlt">velocities</span> in homogeneous and smoothly heterogeneous aquifers but does not preserve discontinuities in <span class="hlt">velocity</span> at abrupt transmissivity boundaries. The new scheme uses potentiometric head gradients and offers improved accuracy for nonuniform flow in heterogeneous aquifers with abrupt changes in transmissivity. It is equivalent to bilinear interpolation in homogeneous media and is equivalent to linear interpolation where gradients are uniform. -from Author</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvE..91c3302H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvE..91c3302H"><span id="translatedtitle">Lattice Boltzmann <span class="hlt">model</span> for the correct convection-diffusion equation with divergence-free <span class="hlt">velocity</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Rongzong; Wu, Huiying</p> <p>2015-03-01</p> <p>A lattice Boltzmann (LB) <span class="hlt">model</span> for the convection-diffusion equation (CDE) with divergence-free <span class="hlt">velocity</span> field is proposed, and the Chapman-Enskog analysis shows that the CDE can be recovered correctly. In the present <span class="hlt">model</span>, the convection term is treated as a source term in the lattice Boltzmann equation (LBE) rather than being directly recovered by LBE; thus the CDE is intrinsically solved as a pure diffusion equation with a corresponding source term. To avoid the adoption of a nonlocal finite-difference scheme for computing the convection term, a local scheme is developed based on the Chapman-Enskog analysis. Most importantly, by properly specifying the discrete source term in the moment space, the local scheme can reach the same order (ɛ2) at which the CDE is recovered by a LB <span class="hlt">model</span>. Numerical tests, including a one-dimensional periodic problem, diffusion of a Gaussian hill, diffusion of a rectangular pulse, and natural convection in a square cavity, are carried out to verify the present <span class="hlt">model</span>. Numerical results are satisfactorily consistent with analytical solutions or previous numerical results, and show higher accuracy due to the correct recovery of CDE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3404643','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3404643"><span id="translatedtitle">Increasing pulse wave <span class="hlt">velocity</span> in a realistic cardiovascular <span class="hlt">model</span> does not increase pulse pressure with age</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Mohiuddin, Mohammad W.; Rihani, Ryan J.; Laine, Glen A.</p> <p>2012-01-01</p> <p>The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel <span class="hlt">model</span> believe that increases in PP arise from decreases in total arterial compliance (Ctot) and increases in total peripheral resistance (Rtot) with age. Investigators assuming a more sophisticated pulse transmission <span class="hlt">model</span> believe PP rises because increases in pulse wave <span class="hlt">velocity</span> (cph) make the reflected pressure wave arrive earlier, augmenting systolic pressure. It has recently been shown, however, that increases in cph do not have a commensurate effect on the timing of the reflected wave. We therefore used a validated, large-scale, human arterial system <span class="hlt">model</span> that includes realistic pulse wave transmission to determine whether increases in cph cause increased PP with age. First, we made the realistic arterial system <span class="hlt">model</span> age dependent by altering cardiac output (CO), Rtot, Ctot, and cph to mimic the reported changes in these parameters from age 30 to 70. Then, cph was theoretically maintained constant, while Ctot, Rtot, and CO were altered. The predicted increase in PP with age was similar to the observed increase in PP. In a complementary approach, Ctot, Rtot, and CO were theoretically maintained constant, and cph was increased. The predicted increase in PP was negligible. We found that increases in cph have a limited effect on the timing of the reflected wave but cause the system to degenerate into a windkessel. Changes in PP can therefore be attributed to a decrease in Ctot. PMID:22561301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AAS...22513816M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AAS...22513816M"><span id="translatedtitle">Testing Stellar Evolution <span class="hlt">Models</span>: <span class="hlt">Absolute</span> Dimensions of the Low-Mass Eclipsing Binary Star V651 Cassiopeiae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Matthews, Allison; Torres, Guillermo</p> <p>2015-01-01</p> <p>We report accurate values of several key quantities for the low-mass, 0.9968096 day period, double-lined eclipsing binary V651 Cas. We determine accurate values for the masses, radii and temperatures of the primary and secondary as follows: M = 0.8553(81) solar masses, R = 0.957(17) solar radii, and effective temperature = 5733(100) K for the primary component, and M = 0.7564(48) solar masses, R = 0.771(15) solar radii, and effective temperature = 5113(105) for the secondary component, with formal uncertainties shown in parentheses. A comparison with the stellar evolution <span class="hlt">models</span> from the Dartmouth Stellar Evolution Program suggests an age of 11(1) Gyr for a best-fit metallicity of [Fe/H] = -0.2. While the isochrone mentioned correctly reproduces the measured radii and temperatures of the stars within the current uncertainties, we note that the secondary radius appears marginally larger and the temperature marginally cooler than <span class="hlt">models</span> would predict. This is consistent with similar discrepancies found for other low-mass stars, generally accredited to surface activity. With further improvement in the measurement errors, and a spectroscopic measure of the metallicity, V651 Cas should be a valuable system for understanding the effects of magnetic activity on the global structure of low-mass stars and for providing guidance to improve stellar evolution <span class="hlt">models</span>.This work was supported in part by the NSF REU and DoD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NewA...34..234O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NewA...34..234O"><span id="translatedtitle">Galactic <span class="hlt">model</span> parameters of cataclysmic variables: Results from a new <span class="hlt">absolute</span> magnitude calibration with 2MASS and WISE</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Özdönmez, A.; Ak, T.; Bilir, S.</p> <p>2015-01-01</p> <p>In order to determine the spatial distribution, Galactic <span class="hlt">model</span> parameters and luminosity function of cataclysmic variables (CVs), a J-band magnitude limited sample of 263 CVs has been established using a newly constructed period-luminosity-colours (PLCs) relation which includes J,Ks and W1-band magnitudes in 2MASS and WISE photometries, and the orbital periods of the systems. This CV sample is assumed to be homogeneous regarding to distances as the new PLCs relation is calibrated with new or re-measured trigonometric parallaxes. Our analysis shows that the scaleheight of CVs is increasing towards shorter periods, although selection effects for the periods shorter than 2.25 h dramatically decrease the scaleheight: the scaleheight of the systems increases from 192 pc to 326 pc as the orbital period decreases from 12 to 2.25 h. The z-distribution of all CVs in the sample is well fitted by an exponential function with a scaleheight of 213-10+11 pc. However, we suggest that the scaleheight of CVs in the Solar vicinity should be ∼300 pc and that the scaleheights derived using the sech2 function should be also considered in the population synthesis <span class="hlt">models</span>. The space density of CVs in the Solar vicinity is found 5.58(1.35)×10-6 pc-3 which is in the range of previously derived space densities and not in agreement with the predictions of the population <span class="hlt">models</span>. The analysis based on the comparisons of the luminosity function of white dwarfs with the luminosity function of CVs in this study show that the best fits are obtained by dividing the luminosity functions of white dwarfs by a factor of 350-450.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982WRR....18.1157D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982WRR....18.1157D"><span id="translatedtitle">Pore <span class="hlt">Velocity</span> Estimation Uncertainties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Devary, J. L.; Doctor, P. G.</p> <p>1982-08-01</p> <p>Geostatistical data analysis techniques were used to stochastically <span class="hlt">model</span> the spatial variability of groundwater pore <span class="hlt">velocity</span> in a potential waste repository site. Kriging algorithms were applied to Hanford Reservation data to estimate hydraulic conductivities, hydraulic head gradients, and pore <span class="hlt">velocities</span>. A first-order Taylor series expansion for pore <span class="hlt">velocity</span> was used to statistically combine hydraulic conductivity, hydraulic head gradient, and effective porosity surfaces and uncertainties to characterize the pore <span class="hlt">velocity</span> uncertainty. Use of these techniques permits the estimation of pore <span class="hlt">velocity</span> uncertainties when pore <span class="hlt">velocity</span> measurements do not exist. Large pore <span class="hlt">velocity</span> estimation uncertainties were found to be located in the region where the hydraulic head gradient relative uncertainty was maximal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950040484&hterms=dark+matter+galaxy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddark%2Bmatter%2Bgalaxy','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950040484&hterms=dark+matter+galaxy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Ddark%2Bmatter%2Bgalaxy"><span id="translatedtitle">Internal <span class="hlt">velocity</span> and mass distributions in simulated clusters of galaxies for a variety of cosmogonic <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cen, Renyue</p> <p>1994-01-01</p> <p>The mass and <span class="hlt">velocity</span> distributions in the outskirts (0.5-3.0/h Mpc) of simulated clusters of galaxies are examined for a suite of cosmogonic <span class="hlt">models</span> (two Omega(sub 0) = 1 and two Omega(sub 0) = 0.2 <span class="hlt">models</span>) utilizing large-scale particle-mesh (PM) simulations. Through a series of <span class="hlt">model</span> computations, designed to isolate the different effects, we find that both Omega(sub 0) and P(sub k) (lambda less than or = 16/h Mpc) are important to the mass distributions in clusters of galaxies. There is a correlation between power, P(sub k), and density profiles of massive clusters; more power tends to point to the direction of a stronger correlation between alpha and M(r less than 1.5/h Mpc); i.e., massive clusters being relatively extended and small mass clusters being relatively concentrated. A lower Omega(sub 0) universe tends to produce relatively concentrated massive clusters and relatively extended small mass clusters compared to their counterparts in a higher Omega(sub 0) <span class="hlt">model</span> with the same power. <span class="hlt">Models</span> with little (initial) small-scale power, such as the hot dark matter (HDM) <span class="hlt">model</span>, produce more extended mass distributions than the isothermal distribution for most of the mass clusters. But the cold dark matter (CDM) <span class="hlt">models</span> show mass distributions of most of the clusters more concentrated than the isothermal distribution. X-ray and gravitational lensing observations are beginning providing useful information on the mass distribution in and around clusters; some interesting constraints on Omega(sub 0) and/or the (initial) power of the density fluctuations on scales lambda less than or = 16/h Mpc (where linear extrapolation is invalid) can be obtained when larger observational data sets, such as the Sloan Digital Sky Survey, become available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004M%26PS...39.1019V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004M%26PS...39.1019V"><span id="translatedtitle">Chicxulub central crater structure: Initial results from physical property measurements and combined <span class="hlt">velocity</span> and gravity <span class="hlt">modeling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vermeesch, P. M.; Morgan, J. V.</p> <p>2004-07-01</p> <p>The Chicxulub crater in Mexico is a nearly pristine example of a large impact crater. Its slow burial has left the central impact basin intact, within which there is an apparently uneroded topographic peak ring. Its burial, however, means that we must rely on drill holes and geophysical data to interpret the crater form. Interpretations of crater structures using geophysical data are often guided by numerical <span class="hlt">modeling</span> and observations at other large terrestrial craters. However, such endeavors are hindered by uncertainties in current numerical <span class="hlt">models</span> and the lack of any obvious progressive change in structure with increasing crater size. For this reason, proposed structural <span class="hlt">models</span> across Chicxulub remain divergent, particularly within the central crater region, where the deepest well is only ~1.6 km deep. The shape and precise location of the stratigraphic uplift are disputed. The spatial extent and distribution of the allogenic impact breccias and melt rocks remain unknown, as do the lithological nature of the peak ring and the mechanism for its formation. The objective of our research is to provide a well-constrained 3D structural and lithological <span class="hlt">model</span> across the central region of the Chicxulub crater that is consistent with combined geophysical data sets and drill core samples. With this in mind, we present initial physical property measurements made on 18 core samples from the Yaxcopoil-1 (Yax-1) drill hole between 400 and 1500 m deep and present a new density <span class="hlt">model</span> that is in agreement with both the 3D <span class="hlt">velocity</span> and gravity data. Future collation of petrophysical and geochemical data from Yax-1 core, as well as further seismic surveys and drilling, will allow us to calibrate our geophysical <span class="hlt">models</span>-assigning a suite of physical properties to each lithology. An accurate 3D <span class="hlt">model</span> of Chicxulub is critical to our understanding of large craters and to the constraining of the environmental effects of this impact.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015E%26PSL.418..115R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015E%26PSL.418..115R"><span id="translatedtitle">Nature and <span class="hlt">velocity</span> of pyroclastic density currents inferred from <span class="hlt">models</span> of entrainment of substrate lithic clasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roche, Olivier</p> <p>2015-05-01</p> <p>Deposits of pyroclastic density currents (PDCs) often contain accidental lithic clasts of typical size of 0.1-1 m captured from an underlying substrate by the parent flows at distances up to several tens of kilometers from the eruptive vent. In order to gain insights into the nature of PDCs, this study investigates the conditions required for entrainment of particles from a granular substrate by a gas-particle density current, with special emphasis to ignimbrite-forming currents whose dynamics are controversial. The two types of physics of emplacement of PDCs proposed in literature are considered. The first <span class="hlt">model</span> deals with a hydraulically rough, dilute turbulent PDC of bulk density of ∼1-10 kg/m3 and considers that entrainment through both traction and saltation is controlled by a Shield criterion at high (>104) particle Reynolds number. The second <span class="hlt">model</span> considers entrainment by a PDC consisting of a dense basal flow of bulk density of the order of 103 kg /m3 and with high interstitial gas pore pressure. This <span class="hlt">model</span> involves uplift of substrate particles, caused by an upward pressure gradient at the flow-substrate interface, and then transport and deposition on the aggrading basal deposit of the flow as demonstrated by recent laboratory experiments. Results show that a dilute PDC can entrain blocks of maximum size of ∼10-15 cm (for a block density of 2000-3000 kg/m3) if maximum current <span class="hlt">velocities</span> up to ∼100 m/s are taken into account. This, in turn, suggests that larger (heavier) blocks found in deposits were captured by PDCs if these had a dense basal flow. The dense flow <span class="hlt">model</span> predicts that PDCs have the potential to entrain metric blocks, whose maximum size (up to ∼2-5 m) decreases with decreasing atmospheric pressure (i.e. increasing altitude). Application of the <span class="hlt">model</span> considering published data on the characteristics of accidental blocks in several well-studied ignimbrites indicates that the <span class="hlt">velocity</span> of the parent dense PDCs was up to ∼25-30 m/s.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AGUFM.S62D..08S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AGUFM.S62D..08S"><span id="translatedtitle">"DOBREfraction'99" - <span class="hlt">Velocity</span> <span class="hlt">models</span> of the crust and upper mantle beneath the Donbas Foldbelt (SE Ukraine)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stephenson, R. A.; Dobrefraction'00 Working Group,.</p> <p>2002-12-01</p> <p>The Pripyat-Dniepr-Donets basin (PDD) is a Late Devonian rift basin located on the southwestern part of the East-European Craton (EEC). This rift basin strikes in a southeasterly direction and extends from Belarus through Ukraine, where it connects with the Donbas foldbelt and its continuation as the deformed southern margin of the craton (Karpinsky Swell) in southern Russia. The Pripyat and Dniepr-Donets basins are important hydrocarbon provinces. The Donbas foldbelt (DF) is the uplifted and deformed part of the 20-km thick Dniepr-Donets basin. In 1999, an international cooperative deep seismic sounding (DSS) experiment (DOBREfraction'99) was undertaken. This effort involved 11 in-line shotpoints and deployment of some 245 recording stations along a northeast-trending, 360 km long profile extending from the shores of the Azov Sea in the south, across the Azov Massif (Ukrainian Shield), the DF, ending at the Ukraine-Russia border in the Voronezh Massif of the EEC. Particular scientific targets included the nature of the crust-mantle transition and the geometry of crustal/upper mantle structures related to rifting and subsequent basin inversion. Tomographic inversion, as well as, ray-trace based <span class="hlt">velocity</span> <span class="hlt">modelling</span> has been carried out. The <span class="hlt">velocity</span> signature of the sedimentary basin itself is well resolved, indicating an asymmetric form (basement surface dipping more gently towards the center of the basin from the north than from the south) and a total thickness of about 20-km, comparable to estimates derived from previous seismic studies and geological interpretations. A thick (>10-km), high-<span class="hlt">velocity</span> (>6.9 km/s), lower crustal body lies beneath the rift basin itself. This layer forms a domal structure that is offset slightly to the north compared to the main basin depocenter. A thinner (~5-km) high <span class="hlt">velocity</span> layer is inferred beneath the southern margin of the Donbas foldbelt and Azov Massif. The former could be related to Permian uplift with the latter being due to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MNRAS.450..145B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MNRAS.450..145B"><span id="translatedtitle">Probing dark energy <span class="hlt">models</span> with extreme pairwise <span class="hlt">velocities</span> of galaxy clusters from the DEUS-FUR simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bouillot, Vincent R.; Alimi, Jean-Michel; Corasaniti, Pier-Stefano; Rasera, Yann</p> <p>2015-06-01</p> <p>Observations of colliding galaxy clusters with high relative <span class="hlt">velocity</span> probe the tail of the halo pairwise <span class="hlt">velocity</span> distribution with the potential of providing a powerful test of cosmology. As an example it has been argued that the discovery of the Bullet Cluster challenges standard Λ cold dark matter (ΛCDM) <span class="hlt">model</span> predictions. Halo catalogues from N-body simulations have been used to estimate the probability of Bullet-like clusters. However, due to simulation volume effects previous studies had to rely on a Gaussian extrapolation of the pairwise <span class="hlt">velocity</span> distribution to high <span class="hlt">velocities</span>. Here, we perform a detail analysis using the halo catalogues from the Dark Energy Universe Simulation Full Universe Runs (DEUS-FUR), which enables us to resolve the high-<span class="hlt">velocity</span> tail of the distribution and study its dependence on the halo mass definition, redshift and cosmology. Building upon these results, we estimate the probability of Bullet-like systems in the framework of Extreme Value Statistics. We show that the tail of extreme pairwise <span class="hlt">velocities</span> significantly deviates from that of a Gaussian, moreover it carries an imprint of the underlying cosmology. We find the Bullet Cluster probability to be two orders of magnitude larger than previous estimates, thus easing the tension with the ΛCDM <span class="hlt">model</span>. Finally, the comparison of the inferred probabilities for the different DEUS-FUR cosmologies suggests that observations of extreme interacting clusters can provide constraints on dark energy <span class="hlt">models</span> complementary to standard cosmological tests.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711991M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711991M"><span id="translatedtitle">Quantifying uncertainty in <span class="hlt">velocity</span> <span class="hlt">models</span> for seismic imaging using a Bayesian approach with application to the Mentelle Basin - Australia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michelioudakis, Dimitrios; Hobbs, Richard; Caiado, Camila</p> <p>2015-04-01</p> <p>Determining the depths of key horizons from seismic reflection data is one of the most important aspects of exploration geophysics. Here, we present Bayesian methods based on an elicitation tool and Gaussian processes to build a detailed and robust <span class="hlt">velocity</span> <span class="hlt">model</span> of the Mentelle Basin, located south west of Australia, with the ultimate goal to identify possible drilling targets for the Integrated Ocean Drilling Program (IODP). The Mentelle Basin is a deep water sedimentary basin located between the Naturaliste Plateau and the southern part of the Western Australian Shelf. It is among the few regions of the world where we can investigate the effects of the Cretaceous hot-house and its collapse at high latitude. The Mentelle Basin hosts a continuous shale sequence for this period that it is over a kilometer thick, the study of which, is crucial for the correlation between the paleoclimate conditions and the tectonic history of the region. By reprocessing 2D multichannel seismic reflection profiles around the proposed drill - sites, we create a detailed subsurface <span class="hlt">velocity</span> <span class="hlt">model</span> which is used as a priori input to the Bayesian approach. The final goal is to build a multi-layered <span class="hlt">model</span> to estimate the depth and the root mean square <span class="hlt">velocity</span> of each layer, both for the isotropic and anisotropic cases in terms of a multivariate posterior distribution. Having determined the RMS <span class="hlt">velocities</span> for each layer, we can calculate, by inference, their interval <span class="hlt">velocities</span> and finally estimate the depth of each sequence of interest with improved accuracy. The key advantage of the Bayesian approach and the major difference compared to the traditional semblance spectrum <span class="hlt">velocity</span> analysis procedure is the calculation of uncertainty of the output <span class="hlt">model</span>. As a result, our statistical approach can construct a robust <span class="hlt">velocity</span> <span class="hlt">model</span> which encompasses the noise and the band-limited nature of the data as an error function. We use this <span class="hlt">model</span> to control the depth migration of the seismic data and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011GeoJI.185..453K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011GeoJI.185..453K&link_type=ABSTRACT"><span id="translatedtitle">Forward waveform <span class="hlt">modelling</span> procedure for 1-D crustal <span class="hlt">velocity</span> structure and its application to the southern Korean Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Seongryong; Rhie, Junkee; Kim, Geunyoung</p> <p>2011-04-01</p> <p>We propose a full-grid search procedure for broad-band waveform <span class="hlt">modelling</span> to determine a 1-D crustal <span class="hlt">velocity</span> <span class="hlt">model</span>. The <span class="hlt">velocity</span> <span class="hlt">model</span> can be more constrained because of the use of broad-band waveforms instead of traveltimes for the crustal phases, although only a small number of event-station pairs were employed. Despite the time-consuming nature of the full-grid search method to search the whole <span class="hlt">model</span> parameter space, the use of an empirical relationship between the P- and S-wave <span class="hlt">velocities</span> can significantly reduce computation time. The proposed method was applied to a case in the southern Korean Peninsula. Broad-band waveforms obtained from two inland earthquakes that occurred on 2007 January 20 (Mw 4.6) and 2004 April 26 (Mw 3.6) were used to test the method. The three-layers over half-space crustal <span class="hlt">velocity</span> <span class="hlt">model</span> of the P- and S-wave <span class="hlt">velocities</span> was estimated. Comparisons of waveform fitness between the final <span class="hlt">model</span> and previously published <span class="hlt">models</span> demonstrate advancements in the average value of waveform fitness for the inland earthquakes. In addition, 1-D <span class="hlt">velocity</span> <span class="hlt">models</span> were determined for three distinct tectonic regions, namely, the Gyonggi Massif, the Okcheon Belt and the Gyeongsang Basin, which are all located inside the study area. A comparison between the three <span class="hlt">models</span> demonstrates that the crustal thickness of the southern Korean Peninsula increases from NW to SE and that the lower crustal composition of the Okcheon belt differs from that of the other tectonic regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.tmp..130J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.tmp..130J"><span id="translatedtitle">Renormalized scattering series for frequency domain waveform <span class="hlt">modelling</span> of strong <span class="hlt">velocity</span> contrasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jakobsen, M.; Wu, R. S.</p> <p>2016-04-01</p> <p>An improved description of scattering and inverse scattering processes in reflection seismology may be obtained on the basis of a scattering series solution to the Helmoltz equation, which allows one to separately <span class="hlt">model</span> primary and multiple reflections. However, the popular scattering series of Born is of limited seismic <span class="hlt">modelling</span> value, since it is only garantied to converge if the global contrast is relatively small. For frequency domain waveform <span class="hlt">modelling</span> of realistic contrasts, some kind of renormalization may be reguired. The concept of renormalization is normally associated with quantum field theory, where it is <span class="hlt">absolutely</span> essential for the treatment of infinities in connection with observable quantities. However, the renormalization program is also highly relevant for classical systems, especially when there are interaction effects that acts across different length scales. In the scattering series of De Wolf, a renormalization of the Green functions is achieved by a split of the scattering potential operator into fore- and back-scattering parts; which leads to an effective reorganization and partially re-summation of the different terms in the Born series, so that their order better reflects the physics of reflection seismology. It has been demonstrated that the leading (single return) term in the De Wolf series (DWS) gives much more accurate results than the corresponding Born approximation, especially for <span class="hlt">models</span> with high contrasts that lead to a large accumulation of phase changes in the forward direction. However, the higher-order terms in the DWS that are associated with internal multiples have not been studied numerically before. In this paper, we report from a systematic numerical investigation of the convergence properties of the DWS which is based on two new operator representations of the DWS. The first operator representation is relatively similar to the original scattering potential formulation, but more global and explicit in nature. The second</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoJI.206..880J&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoJI.206..880J&link_type=ABSTRACT"><span id="translatedtitle">Renormalized scattering series for frequency-domain waveform <span class="hlt">modelling</span> of strong <span class="hlt">velocity</span> contrasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jakobsen, M.; Wu, R. S.</p> <p>2016-08-01</p> <p>An improved description of scattering and inverse scattering processes in reflection seismology may be obtained on the basis of a scattering series solution to the Helmoltz equation, which allows one to separately <span class="hlt">model</span> primary and multiple reflections. However, the popular scattering series of Born is of limited seismic <span class="hlt">modelling</span> value, since it is only guaranteed to converge if the global contrast is relatively small. For frequency-domain waveform <span class="hlt">modelling</span> of realistic contrasts, some kind of renormalization may be required. The concept of renormalization is normally associated with quantum field theory, where it is <span class="hlt">absolutely</span> essential for the treatment of infinities in connection with observable quantities. However, the renormalization program is also highly relevant for classical systems, especially when there are interaction effects that act across different length scales. In the scattering series of De Wolf, a renormalization of the Green's functions is achieved by a split of the scattering potential operator into fore- and backscattering parts; which leads to an effective reorganization and partially re-summation of the different terms in the Born series, so that their order better reflects the physics of reflection seismology. It has been demonstrated that the leading (single return) term in the De Wolf series (DWS) gives much more accurate results than the corresponding Born approximation, especially for <span class="hlt">models</span> with high contrasts that lead to a large accumulation of phase changes in the forward direction. However, the higher order terms in the DWS that are associated with internal multiples have not been studied numerically before. In this paper, we report from a systematic numerical investigation of the convergence properties of the DWS which is based on two new operator representations of the DWS. The first operator representation is relatively similar to the original scattering potential formulation, but more global and explicit in nature. The second</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22034529','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22034529"><span id="translatedtitle"><span class="hlt">MODELING</span> MULTI-WAVELENGTH STELLAR ASTROMETRY. III. DETERMINATION OF THE <span class="hlt">ABSOLUTE</span> MASSES OF EXOPLANETS AND THEIR HOST STARS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Coughlin, J. L.; Lopez-Morales, Mercedes</p> <p>2012-05-10</p> <p>Astrometric measurements of stellar systems are becoming significantly more precise and common, with many ground- and space-based instruments and missions approaching 1 {mu}as precision. We examine the multi-wavelength astrometric orbits of exoplanetary systems via both analytical formulae and numerical <span class="hlt">modeling</span>. Exoplanets have a combination of reflected and thermally emitted light that causes the photocenter of the system to shift increasingly farther away from the host star with increasing wavelength. We find that, if observed at long enough wavelengths, the planet can dominate the astrometric motion of the system, and thus it is possible to directly measure the orbits of both the planet and star, and thus directly determine the physical masses of the star and planet, using multi-wavelength astrometry. In general, this technique works best for, though is certainly not limited to, systems that have large, high-mass stars and large, low-mass planets, which is a unique parameter space not covered by other exoplanet characterization techniques. Exoplanets that happen to transit their host star present unique cases where the physical radii of the planet and star can be directly determined via astrometry alone. Planetary albedos and day-night contrast ratios may also be probed via this technique due to the unique signature they impart on the observed astrometric orbits. We develop a tool to examine the prospects for near-term detection of this effect, and give examples of some exoplanets that appear to be good targets for detection in the K to N infrared observing bands, if the required precision can be achieved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1616006T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1616006T"><span id="translatedtitle">Measuring and <span class="hlt">modelling</span> the frictional <span class="hlt">velocity</span> u*, turbulence and heat fluxes above the North Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tambke, Jens; Bye, John A. T.; Schmidt, Michael; Wolff, Jörg-Olaf</p> <p>2014-05-01</p> <p>In this study, we analyse the frictional <span class="hlt">velocity</span> u*, drag coefficient, vertical wind speed and turbulence profiles observed at different met-masts in the German North and Baltic Sea. We present an analysis of different <span class="hlt">models</span> for the frictional <span class="hlt">velocity</span> u* in convective, neutral and stable thermal stratification of the atmosphere. Atmospheric turbulent momentum and heat flux measurements performed with ultra-sonic anemometers are compared to profile-derived values and a bulk Richardson number formulation of the atmospheric thermal stability. <span class="hlt">Modelling</span>: An improved approach to <span class="hlt">model</span> the vertical wind speed profile is presented and compared against meso-scale <span class="hlt">model</span> results (WRF, COSMO): Bye-Ekman-Coupling (BEC) describes the flux of momentum from the Ekman layer of the atmosphere through the Prandtl layer down to the air-sea interface by a modified wave boundary layer with enhanced Charnock dynamics (Bye et al. 2010). The BEC <span class="hlt">model</span> is based on the coupled pair of similarity relations for "aerodynamically rough flow" in both fluids (air and sea). The derived drag law is of Charnock form, almost independent of the wave age and consistent with the transfer of momentum to the wave spectrum - which takes place in the smaller rather than the dominant wavelengths. Measurements: It was found that the frictional <span class="hlt">velocity</span> u* is considerably smaller than predicted by conventional approaches using the Charnock relation: For wind speeds between 10 m/s and 15 m/s at 40 m height above the sea surface, u*(observed) is 14% smaller than u*(Charnock). Most important, we found unexpected, strong and obviously artificial distortions concerning the three wind speed components in the 10Hz data of the three ultra-sonic anemometers at the offshore met-mast FINO1 at 40 m, 60 m and 80 m height. The pattern of these distortions is independent from different post-processing procedures (planar-fit etc.). We anticipate that these artefacts imply severe problems for the eddy covariance technique</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.7634G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.7634G"><span id="translatedtitle">Shear-wave <span class="hlt">velocity</span> structure of young Atlantic Lithosphere from dispersion analysis and waveform <span class="hlt">modelling</span> of Rayleigh waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grevemeyer, Ingo; Lange, Dietrich; Schippkus, Sven</p> <p>2016-04-01</p> <p>The lithosphere is the outermost solid layer of the Earth and includes the brittle curst and brittle uppermost mantle. It is underlain by the asthenosphere, the weaker and hotter portion of the mantle. The boundary between the brittle lithosphere and the asthenosphere is call the lithosphere-asthenosphere boundary, or LAB. The oceanic lithosphere is created at spreading ridges and cools and thickens with age. Seismologists define the LAB by the presence of a low shear wave <span class="hlt">velocity</span> zone beneath a high <span class="hlt">velocity</span> lid. Surface waves from earthquakes occurring in young oceanic lithosphere should sample lithospheric structure when being recorded in the vicinity of a mid-ocean ridge. Here, we study group <span class="hlt">velocity</span> and dispersion of Rayleigh waves caused by earthquakes occurring at transform faults in the Central Atlantic Ocean. Earthquakes were recorded either by a network of wide-band (up to 60 s) ocean-bottom seismometers (OBS) deployed at the Mid-Atlantic Ridge near 15°N or at the Global Seismic Network (GSN) Station ASCN on Ascension Island. Surface waves sampling young Atlantic lithosphere indicate systematic age-dependent changes of group <span class="hlt">velocities</span> and dispersion of Rayleigh waves. With increasing plate age maximum group <span class="hlt">velocity</span> increases (as a function of period), indicating cooling and thickening of the lithosphere. Shear wave <span class="hlt">velocity</span> is derived inverting the observed dispersion of Rayleigh waves. Further, <span class="hlt">models</span> derived from the OBS records were refined using waveform <span class="hlt">modelling</span> of vertical component broadband data at periods of 15 to 40 seconds, constraining the <span class="hlt">velocity</span> structure of the uppermost 100 km and hence in the depth interval of the mantle where lithospheric cooling is most evident. Waveform <span class="hlt">modelling</span> supports that the thickness of lithosphere increases with age and that <span class="hlt">velocities</span> in the lithosphere increase, too.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715641T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715641T"><span id="translatedtitle">Using Global Plate <span class="hlt">Velocity</span> Boundary Conditions for Embedded Regional Geodynamic <span class="hlt">Models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taramon Gomez, Jorge; Morgan, Jason; Perez-Gussinye, Marta</p> <p>2015-04-01</p> <p>The treatment of far-field boundary conditions is one of the most poorly resolved issues for regional <span class="hlt">modeling</span> of geodynamic processes. In viscous flow, the choice of far-field boundary conditions often strongly shapes the large-scale structure of a geosimulation. The mantle <span class="hlt">velocity</span> field along the sidewalls and base of a <span class="hlt">modeling</span> region is typically much more poorly known than the geometry of past global motions of the surface plates as constrained by global plate motion reconstructions. For regional rifting <span class="hlt">models</span> it has become routine to apply highly simplified 'plate spreading' or 'uniform rifting' boundary conditions to a 3-D <span class="hlt">model</span> that limits its ability to simulate the geodynamic evolution of a specific rifted margin. One way researchers are exploring the sensitivity of regional <span class="hlt">models</span> to uncertain boundary conditions is to use a nested <span class="hlt">modeling</span> approach in which a global <span class="hlt">model</span> is used to determine a large-scale flow pattern that is imposed as a constraint along the boundaries of the region to be <span class="hlt">modeled</span>. Here we explore the utility of a different approach that takes advantage of the ability of finite element <span class="hlt">models</span> to use unstructured meshes than can embed much higher resolution sub-regions within a spherical global mesh. In our initial project to validate this approach, we create a global spherical mesh in which a higher resolution sub-region is created around the nascent South Atlantic Rifting Margin. Global Plate motion BCs and plate boundaries are applied for the time of the onset of rifting, continuing through several 10s of Ma of rifting. Thermal, compositional, and melt-related buoyancy forces are only non-zero within the high-resolution subregion, elsewhere, motions are constrained by surface plate-motion constraints. The total number of unknowns needed to solve an embedded regional <span class="hlt">model</span> with this approach is less than 1/3 larger than that needed for a structured-mesh solution on a Cartesian or spherical cap sub-regional mesh. Here we illustrate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21057337','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21057337"><span id="translatedtitle"><span class="hlt">Modelling</span> and Simulation of Tensile Fracture in High <span class="hlt">Velocity</span> Compacted Metal Powder</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jonsen, P.; Haeggblad, H.-A.</p> <p>2007-05-17</p> <p>In cold uniaxial powder compaction, powder is formed into a desired shape with rigid tools and a die. After pressing, but before sintering, the compacted powder is called green body. A critical property in the metal powder pressing process is the mechanical properties of the green body. Beyond a green body free from defects, desired properties are high strength and uniform density. High <span class="hlt">velocity</span> compaction (HVC) using a hydraulic operated hammer is a production method to form powder utilizing a shock wave. Pre-alloyed water atomised iron powder has been HVC-formed into circular discs with high densities. The diametral compression test also called the Brazilian disc test is an established method to measure tensile strength in low strength material like e.g. rock, concrete, polymers and ceramics. During the test a thin disc is compressed across the diameter to failure. The compression induces a tensile stress perpendicular to the compressed diameter. In this study the test have been used to study crack initiation and the tensile fracture process of HVC-formed metal powder discs with a relative density of 99%. A fictitious crack <span class="hlt">model</span> controlled by a stress versus crack-width relationship is utilized to <span class="hlt">model</span> green body cracking. Tensile strength is used as a failure condition and limits the stress in the fracture interface. The softening rate of the <span class="hlt">model</span> is obtained from the corresponding rate of the dissipated energy. The deformation of the powder material is <span class="hlt">modelled</span> with an elastic-plastic Cap <span class="hlt">model</span>. The characteristics of the tensile fracture development of the central crack in a diametrically loaded specimen is numerically studied with a three dimensional finite element simulation. Results from the finite element simulation of the diametral compression test shows that it is possible to simulate fracturing of HVC-formed powder. Results from the simulation agree reasonably with experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AIPC..908.1117J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AIPC..908.1117J"><span id="translatedtitle"><span class="hlt">Modelling</span> and Simulation of Tensile Fracture in High <span class="hlt">Velocity</span> Compacted Metal Powder</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonsén, P.; Häggblad, H.-A.˚.</p> <p>2007-05-01</p> <p>In cold uniaxial powder compaction, powder is formed into a desired shape with rigid tools and a die. After pressing, but before sintering, the compacted powder is called green body. A critical property in the metal powder pressing process is the mechanical properties of the green body. Beyond a green body free from defects, desired properties are high strength and uniform density. High <span class="hlt">velocity</span> compaction (HVC) using a hydraulic operated hammer is a production method to form powder utilizing a shock wave. Pre-alloyed water atomised iron powder has been HVC-formed into circular discs with high densities. The diametral compression test also called the Brazilian disc test is an established method to measure tensile strength in low strength material like e.g. rock, concrete, polymers and ceramics. During the test a thin disc is compressed across the diameter to failure. The compression induces a tensile stress perpendicular to the compressed diameter. In this study the test have been used to study crack initiation and the tensile fracture process of HVC-formed metal powder discs with a relative density of 99%. A fictitious crack <span class="hlt">model</span> controlled by a stress versus crack-width relationship is utilized to <span class="hlt">model</span> green body cracking. Tensile strength is used as a failure condition and limits the stress in the fracture interface. The softening rate of the <span class="hlt">model</span> is obtained from the corresponding rate of the dissipated energy. The deformation of the powder material is <span class="hlt">modelled</span> with an elastic-plastic Cap <span class="hlt">model</span>. The characteristics of the tensile fracture development of the central crack in a diametrically loaded specimen is numerically studied with a three dimensional finite element simulation. Results from the finite element simulation of the diametral compression test shows that it is possible to simulate fracturing of HVC-formed powder. Results from the simulation agree reasonably with experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010OcSci...6..361P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010OcSci...6..361P"><span id="translatedtitle">A <span class="hlt">model</span> for predicting changes in the electrical conductivity, practical salinity, and <span class="hlt">absolute</span> salinity of seawater due to variations in relative chemical composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pawlowicz, R.</p> <p>2010-03-01</p> <p>Salinity determination in seawater has been carried out for almost 30 years using the Practical Salinity Scale 1978. However, the numerical value of so-called practical salinity, computed from electrical conductivity, differs slightly from the true or <span class="hlt">absolute</span> salinity, defined as the mass of dissolved solids per unit mass of seawater. The difference arises because more recent knowledge about the composition of seawater is not reflected in the definition of practical salinity, which was chosen to maintain historical continuity with previous measures, and because of spatial and temporal variations in the relative composition of seawater. Accounting for these spatial variations in density calculations requires the calculation of a correction factor δSA, which is known to range from 0 to 0.03 g kg-1 in the world oceans. Here a mathematical <span class="hlt">model</span> relating compositional perturbations to δSA is developed, by combining a chemical <span class="hlt">model</span> for the composition of seawater with a mathematical <span class="hlt">model</span> for predicting the conductivity of multi-component aqueous solutions. <span class="hlt">Model</span> calculations for this estimate of δSA, denoted δSRsoln, generally agree with estimates of δSA based on fits to direct density measurements, denoted δSRdens, and show that biogeochemical perturbations affect conductivity only weakly. However, small systematic differences between <span class="hlt">model</span> and density-based estimates remain. These may arise for several reasons, including uncertainty about the biogeochemical processes involved in the increase in Total Alkalinity in the North Pacific, uncertainty in the carbon content of IAPSO standard seawater, and uncertainty about the haline contraction coefficient for the constituents involved in biogeochemical processes. This <span class="hlt">model</span> may then be important in constraining these processes, as well as in future efforts to improve parameterizations for δSA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009OcScD...6.2861P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009OcScD...6.2861P"><span id="translatedtitle">A <span class="hlt">model</span> for predicting changes in the electrical conductivity, practical salinity, and <span class="hlt">absolute</span> salinity of seawater due to variations in relative chemical composition</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pawlowicz, R.</p> <p>2009-11-01</p> <p>Salinity determination in seawater has been carried out for almost 30 years using the 1978 Practical Salinity Standard. However, the numerical value of so-called practical salinity, computed from electrical conductivity, differs slightly from the true or <span class="hlt">absolute</span> salinity, defined as the mass of dissolved solids per unit mass of seawater. The difference arises because more recent knowledge about the composition of seawater is not reflected in the definition of practical salinity, which was chosen to maintain historical continuity with previous measures, and because of spatial and temporal variations in the relative composition of seawater. Accounting for these variations in density calculations requires the calculation of a correction factor δSA, which is known to range from 0 to 0.03 g kg-1 in the world oceans. Here a mathematical <span class="hlt">model</span> relating compositional perturbations to δSA is developed, by combining a chemical <span class="hlt">model</span> for the composition of seawater with a mathematical <span class="hlt">model</span> for predicting the conductivity of multi-component aqueous solutions. <span class="hlt">Model</span> calculations generally agree with estimates of δSA based on fits to direct density measurements, and show that biogeochemical perturbations affect conductivity only weakly. However, small systematic differences between <span class="hlt">model</span> and density-based estimates remain. These may arise for several reasons, including uncertainty about the biogeochemical processes involved in the increase in Total Alkalinity in the North Pacific, uncertainty in the carbon content of IAPSO standard seawater, and uncertainty about the haline contraction coefficient for the constituents involved in biogeochemical processes. This <span class="hlt">model</span> may then be important in constraining these processes, as well as in future efforts to improve parameterizations for δSA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AcGeo..61..194K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcGeo..61..194K"><span id="translatedtitle">Application of one-dimensional <span class="hlt">model</span> to calculate water <span class="hlt">velocity</span> distributions over elastic elements simulating Canadian waterweed plants (Elodea Canadensis)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kubrak, Elżbieta; Kubrak, Janusz; Rowiński, Paweł</p> <p>2013-02-01</p> <p>One-dimensional <span class="hlt">model</span> for vertical profiles of longitudinal <span class="hlt">velocities</span> in open-channel flows is verified against laboratory data obtained in an open channel with artificial plants. Those plants simulate Canadian waterweed which in nature usually forms dense stands that reach all the way to the water surface. The <span class="hlt">model</span> works particularly well for densely spaced plants.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110013051','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110013051"><span id="translatedtitle">Electronic <span class="hlt">Absolute</span> Cartesian Autocollimator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Leviton, Douglas B.</p> <p>2006-01-01</p> <p>An electronic <span class="hlt">absolute</span> Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term <span class="hlt">absolute</span> in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based <span class="hlt">absolutely</span> on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic <span class="hlt">absolute</span> Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.204.1024K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.204.1024K"><span id="translatedtitle">SP12RTS: a degree-12 <span class="hlt">model</span> of shear- and compressional-wave <span class="hlt">velocity</span> for Earth's mantle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koelemeijer, P.; Ritsema, J.; Deuss, A.; van Heijst, H.-J.</p> <p>2016-02-01</p> <p>We present the new <span class="hlt">model</span> SP12RTS of isotropic shear-wave (VS) and compressional-wave (VP) <span class="hlt">velocity</span> variations in the Earth's mantle. SP12RTS is derived using the same methods as employed in the construction of the shear-wave <span class="hlt">velocity</span> <span class="hlt">models</span> S20RTS and S40RTS, and the same data types. SP12RTS includes additional traveltime measurements of P-waves and new splitting measurements: 33 normal modes with sensitivity to the compressional-wave <span class="hlt">velocity</span> and 9 Stoneley modes with sensitivity primarily to the lowermost mantle. Contrary to S20RTS and S40RTS, variations in VS and VP are determined without invoking scaling relationships. Lateral <span class="hlt">velocity</span> variations in SP12RTS are parametrised using spherical harmonics up to degree 12, to focus on long-wavelength features of VS and VP and their ratio R. Large-low-<span class="hlt">velocity</span> provinces (LLVPs) are observed for both VS and VP. SP12RTS also features an increase of R up to 2500 km depth, followed by a decrease towards the core-mantle boundary. A negative correlation between the shear-wave and bulk-sound <span class="hlt">velocity</span> variations is observed for both the LLVPs and the surrounding mantle. These characteristics can be explained by the presence of post-perovskite or large-scale chemical heterogeneity in the lower mantle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4180247','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4180247"><span id="translatedtitle">A COMPARISON OF <span class="hlt">MODEL</span> BASED AND DIRECT OPTIMIZATION BASED FILTERING ALGORITHMS FOR SHEARWAVE <span class="hlt">VELOCITY</span> RECONSTRUCTION FOR ELECTRODE VIBRATION ELASTOGRAPHY</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ingle, Atul; Varghese, Tomy</p> <p>2014-01-01</p> <p>Tissue stiffness estimation plays an important role in cancer detection and treatment. The presence of stiffer regions in healthy tissue can be used as an indicator for the possibility of pathological changes. Electrode vibration elastography involves tracking of a mechanical shear wave in tissue using radio-frequency ultrasound echoes. Based on appropriate assumptions on tissue elasticity, this approach provides a direct way of measuring tissue stiffness from shear wave <span class="hlt">velocity</span>, and enabling visualization in the form of tissue stiffness maps. In this study, two algorithms for shear wave <span class="hlt">velocity</span> reconstruction in an electrode vibration setup are presented. The first method <span class="hlt">models</span> the wave arrival time data using a hidden Markov <span class="hlt">model</span> whose hidden states are local wave <span class="hlt">velocities</span> that are estimated using a particle filter implementation. This is compared to a direct optimization-based function fitting approach that uses sequential quadratic programming to estimate the unknown <span class="hlt">velocities</span> and locations of interfaces. The mean shear wave <span class="hlt">velocities</span> obtained using the two algorithms are within 10%of each other. Moreover, the Young’s modulus estimates obtained from an incompressibility assumption are within 15 kPa of those obtained from the true stiffness data obtained from mechanical testing. Based on visual inspection of the two filtering algorithms, the particle filtering method produces smoother <span class="hlt">velocity</span> maps. PMID:25285187</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A43A3236D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A43A3236D"><span id="translatedtitle">A <span class="hlt">velocity</span>-dissipation stochastic trajectory <span class="hlt">model</span> for dispersal of heavy particles inside canopies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duman, T.; Trakhtenbrot, A.; Poggi, D.; Cassiani, M.; Katul, G. G.</p> <p>2014-12-01</p> <p>While the importance of dispersal of windborne heavy particles such as seeds or pollen inside canopies is rarely disputed, the details needed to describe turbulent fluctuations in such applications continue to draw significant research attention. Turbulence and heavy-particle dispersal within canopies are sensitive to interactions between meteorological conditions and canopy structure as well as on particle shape and mass. In many applications, dispersal of heavy particles is required over a broad range of time scales ranging from hours to several decades thereby frustrating any attempt to resolve all aspects of turbulence. In recent years, Lagrangian stochastic trajectory <span class="hlt">models</span> have been favored for predicting seed dispersal and are viewed as an acceptable compromise between empirical <span class="hlt">models</span> with their ad-hoc parameterizations and computationally intensive Large Eddy Simulations. Here, an important feature of turbulence, namely the intermittency in dissipation rate, is incorporated into such trajectory <span class="hlt">models</span>. Adding this effect has been recently shown to alter scalar dispersion patterns, especially in the far field. This method is applied here to heavy particles, where the long distance dispersal is deemed significant for many applications. This <span class="hlt">modeling</span> approach was first evaluated using controlled laboratory experiments, where uniform-sized spheres were released within a canopy comprised of uniform cylinders inside a flume (see figure). The extended <span class="hlt">model</span> that includes intermittency effects, as well as inertial drag forces on the particles, was shown to provide superior fit with the measured dispersal kernel than simpler <span class="hlt">models</span> that add a constant settling <span class="hlt">velocity</span> for each particle and/or do not include intermittency. The extended <span class="hlt">model</span> results captured short distance dispersal and the heavy tails. Next the extended <span class="hlt">model</span> was evaluated against a field experiment, where plant seeds were manually released inside a hardwood forest canopy (see figure). This</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PEPS....2....3A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015PEPS....2....3A&link_type=ABSTRACT"><span id="translatedtitle">Sound <span class="hlt">velocity</span> of hcp-Fe at high pressure: experimental constraints, extrapolations and comparison with seismic <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Antonangeli, Daniele; Ohtani, Eiji</p> <p>2015-12-01</p> <p>Determining the sound <span class="hlt">velocity</span> of iron under extreme thermodynamic conditions is essential for a proper interpretation of seismic observations of the Earth's core but is experimentally challenging. Here, we review techniques and methodologies used to measure sound <span class="hlt">velocities</span> in metals at megabar pressures, with specific focus on the compressional sound <span class="hlt">velocity</span> of hexagonal close-packed iron. A critical comparison of literature results, coherently analyzed using consistent metrology (pressure scale, equation of state), allows us to propose reference relations for the pressure and density dependence of the compressional <span class="hlt">velocity</span> of hexagonal close-packed iron at ambient temperature. This provides a key base line upon which to add complexity, including high-temperature effects, pre-melting effects, effects of nickel and/or light element incorporation, necessary for an accurate comparison with seismic <span class="hlt">models</span>, and ultimately to constrain Earth's inner core composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4306772','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4306772"><span id="translatedtitle">Critical <span class="hlt">Velocity</span> and Anaerobic Paddling Capacity Determined by Different Mathematical <span class="hlt">Models</span> and Number of Predictive Trials in Canoe Slalom</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Messias, Leonardo H. D.; Ferrari, Homero G.; Reis, Ivan G. M.; Scariot, Pedro P. M.; Manchado-Gobatto, Fúlvia B.</p> <p>2015-01-01</p> <p>The purpose of this study was to analyze if different combinations of trials as well as mathematical <span class="hlt">models</span> can modify the aerobic and anaerobic estimates from critical <span class="hlt">velocity</span> protocol applied in canoe slalom. Fourteen male elite slalom kayakers from Brazilian canoe slalom team (K1) were evaluated. Athletes were submitted to four predictive trials of 150, 300, 450 and 600 meters in a lake and the time to complete each trial was recorded. Critical <span class="hlt">velocity</span> (CV-aerobic parameter) and anaerobic paddling capacity (APC-anaerobic parameter) were obtained by three mathematical <span class="hlt">models</span> (Linear1=distance-time; Linear 2=<span class="hlt">velocity</span>-1/time and Non-Linear = time-<span class="hlt">velocity</span>). Linear 1 was chosen for comparison of predictive trials combinations. Standard combination (SC) was considered as the four trials (150, 300, 450 and 600 m). High fits of regression were obtained from all mathematical <span class="hlt">models</span> (range - R² = 0.96-1.00). Repeated measures ANOVA pointed out differences of all mathematical <span class="hlt">models</span> for CV (p = 0.006) and APC (p = 0.016) as well as R² (p = 0.033). Estimates obtained from the first (1) and the fourth (4) predictive trials (150 m = lowest; and 600 m = highest, respectively) were similar and highly correlated (r=0.98 for CV and r = 0.96 for APC) with the SC. In summary, methodological aspects must be considered in critical <span class="hlt">velocity</span> application in canoe slalom, since different combinations of trials as well as mathematical <span class="hlt">models</span> resulted in different aerobic and anaerobic estimates. Key points Great attention must be given for methodological concerns regarding critical <span class="hlt">velocity</span> protocol applied on canoe slalom, since different estimates were obtained depending on the mathematical <span class="hlt">model</span> and the predictive trials used. Linear 1 showed the best fits of regression. Furthermore, to the best of our knowledge and considering practical applications, this <span class="hlt">model</span> is the easiest one to calculate the estimates from critical <span class="hlt">velocity</span> protocol. Considering this, the abyss between</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21250885','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21250885"><span id="translatedtitle"><span class="hlt">Velocity</span>-dependent <span class="hlt">models</span> for non-Abelian/entangled string networks</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Avgoustidis, A.; Shellard, E. P. S.</p> <p>2008-11-15</p> <p>We develop <span class="hlt">velocity</span>-dependent <span class="hlt">models</span> describing the evolution of string networks that involve several types of interacting strings, each with a different tension. These incorporate the formation of Y-type junctions with links stretching between colliding strings, while always ensuring energy conservation. These <span class="hlt">models</span> can be used to describe network evolution for non-Abelian strings as well as cosmic superstrings. The application to Z{sub N} strings in which interactions are topologically constrained, demonstrates that a scaling regime is generally reached which involves a hierarchy of string densities with the lightest most abundant. We also study hybrid networks of cosmic superstrings, where energetic considerations are more important in determining interaction outcomes. We again find that networks tend towards scaling, with the three lightest network components being dominant and having comparable number densities, while the heavier string states are suppressed. A more quantitative analysis depends on the precise calculation of the string interaction matrix using the underlying string or field theory. Nevertheless, these results provide further evidence that the presence of junctions in a string network does not obstruct scaling.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20723030','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20723030"><span id="translatedtitle"><span class="hlt">Absolute</span> solvation free energy of Li{sup +} and Na{sup +} ions in dimethyl sulfoxide solution: A theoretical ab initio and cluster-continuum <span class="hlt">model</span> study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Westphal, Eduard; Pliego, Josefredo R. Jr.</p> <p>2005-08-15</p> <p>The solvation of the lithium and sodium ions in dimethyl sulfoxide solution was theoretically investigated using ab initio calculations coupled with the hybrid cluster-continuum <span class="hlt">model</span>, a quasichemical theory of solvation. We have investigated clusters of ions with up to five dimethyl sulfoxide (DMSO) molecules, and the bulk solvent was described by a dielectric continuum <span class="hlt">model</span>. Our results show that the lithium and sodium ions have four and five DMSO molecules into the first coordination shell, and the calculated solvation free energies are -135.5 and -108.6 kcal mol{sup -1}, respectively. These data suggest a solvation free energy value of -273.2 kcal mol{sup -1} for the proton in dimethyl sulfoxide solution, a value that is more negative than the present uncertain experimental value. This and previous studies on the solvation of ions in water solution indicate that the tetraphenylarsonium tetraphenylborate assumption is flawed and the <span class="hlt">absolute</span> value of the free energy of transfer of ions from water to DMSO solution is higher than the present experimental values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/22561301','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22561301"><span id="translatedtitle">Increasing pulse wave <span class="hlt">velocity</span> in a realistic cardiovascular <span class="hlt">model</span> does not increase pulse pressure with age.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mohiuddin, Mohammad W; Rihani, Ryan J; Laine, Glen A; Quick, Christopher M</p> <p>2012-07-01</p> <p>The mechanism of the well-documented increase in aortic pulse pressure (PP) with age is disputed. Investigators assuming a classical windkessel <span class="hlt">model</span> believe that increases in PP arise from decreases in total arterial compliance (C(tot)) and increases in total peripheral resistance (R(tot)) with age. Investigators assuming a more sophisticated pulse transmission <span class="hlt">model</span> believe PP rises because increases in pulse wave <span class="hlt">velocity</span> (c(ph)) make the reflected pressure wave arrive earlier, augmenting systolic pressure. It has recently been shown, however, that increases in c(ph) do not have a commensurate effect on the timing of the reflected wave. We therefore used a validated, large-scale, human arterial system <span class="hlt">model</span> that includes realistic pulse wave transmission to determine whether increases in c(ph) cause increased PP with age. First, we made the realistic arterial system <span class="hlt">model</span> age dependent by altering cardiac output (CO), R(tot), C(tot), and c(ph) to mimic the reported changes in these parameters from age 30 to 70. Then, c(ph) was theoretically maintained constant, while C(tot), R(tot), and CO were altered. The predicted increase in PP with age was similar to the observed increase in PP. In a complementary approach, C(tot), R(tot), and CO were theoretically maintained constant, and c(ph) was increased. The predicted increase in PP was negligible. We found that increases in c(ph) have a limited effect on the timing of the reflected wave but cause the system to degenerate into a windkessel. Changes in PP can therefore be attributed to a decrease in C(tot). PMID:22561301</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PMB....47.3893M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PMB....47.3893M"><span id="translatedtitle">Methodology to predict long-term cancer survival from short-term data using Tobacco Cancer Risk and <span class="hlt">Absolute</span> Cancer Cure <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mould, R. F.; Lederman, M.; Tai, P.; Wong, J. K. M.</p> <p>2002-11-01</p> <p>Three parametric statistical <span class="hlt">models</span> have been fully validated for cancer of the larynx for the prediction of long-term 15, 20 and 25 year cancer-specific survival fractions when short-term follow-up data was available for just 1-2 years after the end of treatment of the last patient. In all groups of cases the treatment period was only 5 years. Three disease stage groups were studied, T1N0, T2N0 and T3N0. The <span class="hlt">models</span> are the Standard Lognormal (SLN) first proposed by Boag (1949 J. R. Stat. Soc. Series B 11 15-53) but only ever fully validated for cancer of the cervix, Mould and Boag (1975 Br. J. Cancer 32 529-50), and two new <span class="hlt">models</span> which have been termed Tobacco Cancer Risk (TCR) and <span class="hlt">Absolute</span> Cancer Cure (ACC). In each, the frequency distribution of survival times of defined groups of cancer deaths is lognormally distributed: larynx only (SLN), larynx and lung (TCR) and all cancers (ACC). All <span class="hlt">models</span> each have three unknown parameters but it was possible to estimate a value for the lognormal parameter S a priori. By reduction to two unknown parameters the <span class="hlt">model</span> stability has been improved. The material used to validate the methodology consisted of case histories of 965 patients, all treated during the period 1944-1968 by Dr Manuel Lederman of the Royal Marsden Hospital, London, with follow-up to 1988. This provided a follow-up range of 20- 44 years and enabled predicted long-term survival fractions to be compared with the actual survival fractions, calculated by the Kaplan and Meier (1958 J. Am. Stat. Assoc. 53 457-82) method. The TCR and ACC <span class="hlt">models</span> are better than the SLN <span class="hlt">model</span> and for a maximum short-term follow-up of 6 years, the 20 and 25 year survival fractions could be predicted. Therefore the numbers of follow-up years saved are respectively 14 years and 19 years. Clinical trial results using the TCR and ACC <span class="hlt">models</span> can thus be analysed much earlier than currently possible. <span class="hlt">Absolute</span> cure from cancer was also studied, using not only the prediction <span class="hlt">models</span> which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPSC...10..717D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPSC...10..717D"><span id="translatedtitle"><span class="hlt">Absolute</span> magnitudes of trans-neptunian objects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.</p> <p>2015-10-01</p> <p>Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise <span class="hlt">absolute</span> magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate <span class="hlt">absolute</span> magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and <span class="hlt">modelled</span>, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure <span class="hlt">absolute</span> magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 <span class="hlt">absolute</span> magnitudes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/921934','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/921934"><span id="translatedtitle"><span class="hlt">ABSOLUTE</span> POLARIMETRY AT RHIC.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.</p> <p>2007-09-10</p> <p>Precise and <span class="hlt">absolute</span> beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The <span class="hlt">absolute</span> polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFMED41B1162M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFMED41B1162M"><span id="translatedtitle"><span class="hlt">Modeling</span> of Geodetic Crustal Motion <span class="hlt">Velocities</span> in Southern California: Undergraduate Research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McGill, S. F.; Barley, M. E.; Hams, J. E.; Hobart, K.; Ramirez, J.; Fryxell, J. E.; Lyzenga, G. A.; McGill, J. D.</p> <p>2003-12-01</p> <p>With funding from the National Science Foundation's Opportunities for Enhancing Diversity in the Geosciences, we have undertaken a project with two primary goals: (1) to introduce undergraduate students and K-14 educators to research in geology/geophysics, and (2) to use GPS to monitor deformation across the boundary between the Pacific and North American plates in southern California, and to <span class="hlt">model</span> the slip on specific faults that could be responsible for that deformation. Starting in July 2002, we collected campaign-style GPS data twice a year from 13 sites along a line across the San Andreas and San Jacinto faults from Norco through San Bernardino to Lucerne Valley. We are also <span class="hlt">modeling</span> data from the SCEC Crustal Deformation <span class="hlt">Velocity</span> Map 2.0 [http://www.scecdc.scec.org/group_e/release.v2/]. Our initial approach has been to use a one-dimensional <span class="hlt">model</span> of dislocations in an elastic half-space. We are studying the portion of the plate boundary from San Bernardino southward to the U.S.-Mexico border. We have divided this region into seven transects that are perpendicular to the plate boundary. We used a spreadsheet macro to systematically <span class="hlt">model</span> a range of slip rates and locking depths for each fault. Out of hundreds or thousands of possible combinations for each transect, we sorted the <span class="hlt">models</span> according to their goodness of fit, using the sum of the squares of the residuals as a criterion. We are also beginning to use the program Simplex (G. Lyzenga. J. Parker) to <span class="hlt">model</span> the <span class="hlt">velocity</span> data from all transects simultaneously. This will allow us to take into account the complex fault geometry of the region. Our preliminary results from the one-dimensional <span class="hlt">modeling</span> suggest that the best-fitting slip rate of the San Andreas fault is 26 mm/yr for the section from Indio to Durmid. However, slip rates in the range of 20-30 mm/yr also fit the geodetic data relatively well. Slip rates of 15 or 35 mm/yr do not fit well. For the San Jacinto fault, the best-fitting slip rate is 13</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27036483','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27036483"><span id="translatedtitle">Note: Sound <span class="hlt">velocity</span> of a soft sphere <span class="hlt">model</span> near the fluid-solid phase transition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khrapak, Sergey A</p> <p>2016-03-28</p> <p>The quasilocalized charge approximation is applied to estimate the sound <span class="hlt">velocity</span> of simple soft sphere fluid with the repulsive inverse-power-law interaction. The obtained results are discussed in the context of the sound <span class="hlt">velocity</span> of the hard-sphere system and of liquid metals at the melting temperature. PMID:27036483</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711136G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711136G"><span id="translatedtitle">A consistent geodynamic <span class="hlt">model</span> for predicting the <span class="hlt">velocity</span> and plate-internal deformation of Eurasia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Govers, Rob; Garcia-Sancho, Candela; Warners-Ruckstuhl, Karin; van der Burgt, Janneke; Wortel, Rinus</p> <p>2015-04-01</p> <p>The motion and deformation of tectonic plates is driven by gravity and resisted by frictional forces. In principle it should thus be possible to build mechanical <span class="hlt">models</span> that reproduce plate <span class="hlt">velocities</span> and surface deformation. Here we present a new approach that overcomes many of the previous obstacles to achieving this goal. Our approach to quantify the forces is based on mechanical equilibrium of the whole Eurasian plate, meaning that an increase in, for instance collision, forces must be matched by other plate tectonic forces. We first focus on present-day Eurasia. We include basal tractions from a global convection <span class="hlt">model</span>, lithospheric body forces, and edge forces resulting from the interaction of the Eurasian plate with neighboring plates. The resulting force distribution is constrained by observed plate motion and by stress observations. Eurasia's stress field turns out to be most sensitive to the distribution of collision forces on the plate's southern margin and, to a lesser extent, to lithospheric density structure and normal pressure from mantle flow. Stress observations require collision forces on the India-Eurasia boundary of 7.0 - 10.5 TN/m. A similar analysis is performed for Eurasia at 20 Ma and 40 Ma. Plate geometry is taken from the global Lausanne (Stampfli) reconstruction, as are plate <span class="hlt">velocities</span> and oceanic ages. Lithospheric body forces are accounted for in a simplified way because we lack detailed enough information on the plate scale topography. For the Miocene, we find ˜1.2 TN/m for the collision force on the India-Eurasia boundary. In the Eocene, the collision force we find is ˜0.4 TN/m. We conclude that the magnitude of the collision force on Tibet increased significantly after 20 Ma: from 40-20 Ma, the plate contact force on the India/Tibet plate boundary segment was of the same order of magnitude as resistive forces on subduction plate boundaries elsewhere. Our timing of the collision force on Eurasia, is substantially younger than the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S23C4512P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S23C4512P"><span id="translatedtitle">3-D <span class="hlt">Velocity</span> <span class="hlt">Model</span> of the Coachella Valley, Southern California Based on Explosive Shots from the Salton Seismic Imaging Project</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Persaud, P.; Stock, J. M.; Fuis, G. S.; Hole, J. A.; Goldman, M.; Scheirer, D. S.</p> <p>2014-12-01</p> <p>We have analyzed explosive shot data from the 2011 Salton Seismic Imaging Project (SSIP) across a 2-D seismic array and 5 profiles in the Coachella Valley to produce a 3-D P-wave <span class="hlt">velocity</span> <span class="hlt">model</span> that will be used in calculations of strong ground shaking. Accurate maps of seismicity and active faults rely both on detailed geological field mapping and a suitable <span class="hlt">velocity</span> <span class="hlt">model</span> to accurately locate earthquakes. Adjoint tomography of an older version of the SCEC 3-D <span class="hlt">velocity</span> <span class="hlt">model</span> shows that crustal heterogeneities strongly influence seismic wave propagation from moderate earthquakes (Tape et al., 2010). These authors improve the crustal <span class="hlt">model</span> and subsequently simulate the details of ground motion at periods of 2 s and longer for hundreds of ray paths. Even with improvements such as the above, the current SCEC <span class="hlt">velocity</span> <span class="hlt">model</span> for the Salton Trough does not provide a match of the timing or waveforms of the horizontal S-wave motions, which Wei et al. (2013) interpret as caused by inaccuracies in the shallow <span class="hlt">velocity</span> structure. They effectively demonstrate that the inclusion of shallow basin structure improves the fit in both travel times and waveforms. Our <span class="hlt">velocity</span> <span class="hlt">model</span> benefits from the inclusion of known location and times of a subset of 126 shots detonated over a 3-week period during the SSIP. This results in an improved <span class="hlt">velocity</span> <span class="hlt">model</span> particularly in the shallow crust. In addition, one of the main challenges in developing 3-D <span class="hlt">velocity</span> <span class="hlt">models</span> is an uneven stations-source distribution. To better overcome this challenge, we also include the first arrival times of the SSIP shots at the more widely spaced Southern California Seismic Network (SCSN) in our inversion, since the layout of the SSIP is complementary to the SCSN. References: Tape, C., et al., 2010, Seismic tomography of the Southern California crust based on spectral-element and adjoint methods: Geophysical Journal International, v. 180, no. 1, p. 433-462. Wei, S., et al., 2013, Complementary slip distributions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoJI.tmp...75V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoJI.tmp...75V"><span id="translatedtitle">Ultralow-<span class="hlt">velocity</span> zone geometries resolved by multi-dimensional waveform <span class="hlt">modeling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vanacore, E. A.; Rost, S.; Thorne, M. S.</p> <p>2016-03-01</p> <p>Ultra-low <span class="hlt">velocity</span> zones (ULVZs) are thin patches of material with strongly reduced seismic wave speeds situated on top of the core-mantle boundary (CMB). A common phase used to detect ULVZs is SPdKS (SKPdS), an SKS wave with a short diffracted P leg along the CMB. Most previous efforts have examined ULVZ properties using 1D waveform <span class="hlt">modeling</span> approaches. We present waveform <span class="hlt">modeling</span> results using the 2.5D finite difference algorithm PSVaxi allowing us better insight into ULVZ structure and location. We characterize ULVZ waveforms based on ULVZ elastic properties, shape, and position along the SPdKS raypath. In particular, we vary the ULVZ location (e.g. source or receiver side), ULVZ topographical profiles (e.g. boxcar, trapezoidal, or Gaussian) and ULVZ lateral scale along great circle path (2.5º, 5º, 10º). We observe several waveform effects absent in 1D ULVZ <span class="hlt">models</span> and show evidence for waveform effects allowing the differentiation between source and receiver side ULVZs. Early inception of the SPdKS/SKPdS phase is difficult to detect for receiver-side ULVZs with maximum shifts in SKPdS initiation of ˜3º in epicentral distance, whereas source-side ULVZs produce maximum shifts of SPdKS initiation of ˜5º, allowing clear separation of source- versus receiver-side structure. We present a case study using data from up to 300 broadband stations in Turkey recorded between 2005 and 2010. We observe a previously undetected ULVZ in the southern Atlantic Ocean region centered near 45º S, 12.5ºW, with a lateral scale of ˜3°, VP reduction of 10%, VS reduction of 30%, and density increase of 10% relative to PREM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70028272','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70028272"><span id="translatedtitle"><span class="hlt">Modeling</span> and validation of a 3D <span class="hlt">velocity</span> structure for the Santa Clara Valley, California, for seismic-wave simulations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hartzell, S.; Harmsen, S.; Williams, R.A.; Carver, D.; Frankel, A.; Choy, G.; Liu, P.-C.; Jachens, R.C.; Brocher, T.M.; Wentworth, C.M.</p> <p>2006-01-01</p> <p>A 3D seismic <span class="hlt">velocity</span> and attenuation <span class="hlt">model</span> is developed for Santa Clara Valley, California, and its surrounding uplands to predict ground motions from scenario earthquakes. The <span class="hlt">model</span> is developed using a variety of geologic and geophysical data. Our starting point is a 3D geologic <span class="hlt">model</span> developed primarily from geologic mapping and gravity and magnetic surveys. An initial <span class="hlt">velocity</span> <span class="hlt">model</span> is constructed by using seismic <span class="hlt">velocities</span> from boreholes, reflection/refraction lines, and spatial autocorrelation microtremor surveys. This <span class="hlt">model</span> is further refined and the seismic attenuation is estimated through waveform <span class="hlt">modeling</span> of weak motions from small local events and strong-ground motion from the 1989 Loma Prieta earthquake. Waveforms are calculated to an upper frequency of 1 Hz using a parallelized finite-difference code that utilizes two regions with a factor of 3 difference in grid spacing to reduce memory requirements. Cenozoic basins trap and strongly amplify ground motions. This effect is particularly strong in the Evergreen Basin on the northeastern side of the Santa Clara Valley, where the steeply dipping Silver Creek fault forms the southwestern boundary of the basin. In comparison, the Cupertino Basin on the southwestern side of the valley has a more moderate response, which is attributed to a greater age and <span class="hlt">velocity</span> of the Cenozoic fill. Surface waves play a major role in the ground motion of sedimentary basins, and they are seen to strongly develop along the western margins of the Santa Clara Valley for our simulation of the Loma Prieta earthquake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8936F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8936F"><span id="translatedtitle"><span class="hlt">Velocity</span> profiles and plug zones in a free surface viscoplastic flow : experimental study and comparison to shallow flow <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freydier, Perrine; Chambon, Guillaume; Naaim, Mohamed</p> <p>2016-04-01</p> <p>Rheological studies concerning natural muddy debris flows have shown that these materials can be <span class="hlt">modelled</span> as non-Newtonian viscoplastic fluids. These complex flows are generally represented using <span class="hlt">models</span> based on a depth-integrated approach (Shallow Water) that take into account closure terms depending on the shape of the <span class="hlt">velocity</span> profile. But to date, there is poor knowledge about the shape of <span class="hlt">velocity</span> profiles and the position of the interface between sheared and unsheared regions (plug) in these flows, especially in the vicinity of the front. In this research, the internal dynamics of a free-surface viscoplastic flow down an inclined channel is investigated and compared to the predictions of a Shallow Water <span class="hlt">model</span> based on the lubrication approximation. Experiments are conducted in an inclined channel whose bottom is constituted by an upward-moving conveyor belt with controlled <span class="hlt">velocity</span>, which allows generating and observing gravity-driven stationary surges in the laboratory frame. Carbopol microgel has been used as a homogeneous and transparent viscoplastic fluid. High-resolution measurements of <span class="hlt">velocity</span> field is performed through optical velocimetry techniques both in the uniform zone and within the front zone where flow thickness is variable and where recirculation takes place. Specific analyses have been developed to determine the position of the plug within the surge. Flow height is accessible through image processing and ultrasonic sensors. Sufficiently far from the front, experimental results are shown to be in good agreement with theoretical predictions regarding the <span class="hlt">velocity</span> profiles and the flow height evolution. In the vicinity of the front, however, analysis of measured <span class="hlt">velocity</span> profiles shows an evolution of the plug different from that predicted by lubrication approximation. Accordingly, the free surface shape also deviates from the predictions of the classical Shallow Water <span class="hlt">model</span>. These results highlight the necessity to take into account higher</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015IzPSE..51..250Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015IzPSE..51..250Y"><span id="translatedtitle"><span class="hlt">Velocity</span>-density <span class="hlt">models</span> of the Earth's crust and upper mantle from the quartz, Craton, and Kimberlite superlong seismic profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yegorova, T. P.; Pavlenkova, G. A.</p> <p>2015-03-01</p> <p>The unique deep seismic studies carried out in Russia with the use of nuclear explosions provided the possibility to identify the detailed structure of the Earth's crust, upper mantle, and transition zone to the lower mantle to a depth of 700 km in a huge territory of North Eurasia. It is shown that seismic <span class="hlt">velocities</span> in the upper mantle mainly reflect its temperature regime. The gravity <span class="hlt">modeling</span> along these profiles showed the absence of a direct relationship between seismic <span class="hlt">velocity</span> and density. The Siberian Craton, which is marked with a low heat flow and high-<span class="hlt">velocity</span> mantle, has lower density. The upper mantle of the East European Platform, with almost the same heat flow, is characterized by the highest densities and seismic <span class="hlt">velocities</span>. Within the West Siberian Plate, high heat flow, lower seismic <span class="hlt">velocities</span>, and increased density in the upper mantle are revealed. This combination of seismic <span class="hlt">velocities</span> and densities suggests different composition of the upper mantle beneath the studied structures with the depleted upper mantle beneath the Siberian Craton.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21739409','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21739409"><span id="translatedtitle">Closed traumatic brain injury <span class="hlt">model</span> in sheep mimicking high-<span class="hlt">velocity</span>, closed head trauma in humans.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grimmelt, A-C; Eitzen, S; Balakhadze, I; Fischer, B; Wölfer, J; Schiffbauer, H; Gorji, A; Greiner, C</p> <p>2011-08-01</p> <p>To date, there are only a few, non-evidence based, cerebroprotective therapeutic strategies for treatment and, accordingly, for prevention of secondary brain injuries following severe closed head trauma. In order to develop new therapy strategies, existing realistic animal <span class="hlt">models</span> need to be advanced. The objective is to bridge standardized small animal <span class="hlt">models</span> and actual patient medical care, since the results of experimental small animal studies often cannot be transferred to brain-injured humans. For improved standardization of high-<span class="hlt">velocity</span> trauma, new trauma devices for initiating closed traumatic brain injury in sheep were developed. The following new devices were tested: 1. An anatomically shaped rubber bolt with an integrated oscillation absorber for prevention of skull fractures; 2. Stationary mounting of the bolt to guarantee stable experimental conditions; 3. Varying degrees of trauma severity, i. e., mild and severe closed traumatic brain injury, using different cartridges; and 4. Trauma analysis via high-speed video recording. Peritraumatic measurements of intracranial pressure, brain tissue pH, brain tissue oxygen, and carbon dioxide pressure, as well as neurotransmitter concentrations were performed. Cerebral injuries were documented with magnetic resonance imaging and compared to neuropathological results. Due to the new trauma devices, skull fractures were prevented. The high-speed video recording documented a realistic trauma mechanism for a car accident. Enhancement of extracellular glutamate, aspartate, and gamma amino butyric acid concentrations began 60 min after the trauma. Magnetic resonance imaging and neuropathological results showed characteristic injury patterns of mild, and severe, closed traumatic brain injury. The severe, closed traumatic brain injury group showed diffuse axonal injuries, traumatic subarachnoid hemorrhage, and hemorrhagic contusions with inconsistent distribution among the animals. The <span class="hlt">model</span> presented here achieves</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSMTE..05.3201P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSMTE..05.3201P"><span id="translatedtitle">Persistent search in single and multiple confined domains: a <span class="hlt">velocity</span>-jump process <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poll, Daniel B.; Kilpatrick, Zachary P.</p> <p>2016-05-01</p> <p>We analyze <span class="hlt">velocity</span>-jump process <span class="hlt">models</span> of persistent search for a single target on a bounded domain. The searcher proceeds along ballistic trajectories and is absorbed upon collision with the target boundary. When reaching the domain boundary, the searcher chooses a random direction for its new trajectory. For circular domains and targets, we can approximate the mean first passage time (MFPT) using a Markov chain approximation of the search process. Our analysis and numerical simulations reveal that the time to find the target decreases for targets closer to the domain boundary. When there is a small probability of direction-switching within the domain, we find the time to find the target decreases slightly with the turning probability. We also extend our exit time analysis to the case of partitioned domains, where there is a single target within one of multiple disjoint subdomains. Given an average time of transition between domains < T> , we find that the optimal rate of transition that minimizes the time to find the target obeys {β\\text{min}}\\propto 1/\\sqrt< T> .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014GeoJI.197..233B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014GeoJI.197..233B"><span id="translatedtitle">Physical <span class="hlt">modelling</span> of a surface-wave survey over a laterally varying granular medium with property contrasts and <span class="hlt">velocity</span> gradients</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bergamo, Paolo; Bodet, Ludovic; Socco, Laura Valentina; Mourgues, Régis; Tournat, Vincent</p> <p>2014-04-01</p> <p>Laboratory experiments using laser-based ultrasonic techniques can be used to simulate seismic surveys on highly controlled small-scale physical <span class="hlt">models</span> of the subsurface. Most of the time, such <span class="hlt">models</span> consist in assemblies of homogeneous and consolidated materials. To enable the physical <span class="hlt">modelling</span> of unconsolidated, heterogeneous and porous media, the use of granular materials is suggested here. We describe a simple technique to build a two-layer physical <span class="hlt">model</span> characterized by lateral variations, strong property contrasts and <span class="hlt">velocity</span> gradients. We use this <span class="hlt">model</span> to address the efficiency of an innovative surface-wave processing technique developed to retrieve 2-D structures from a limited number of receivers. A step by step inversion procedure of the extracted dispersion curves yields accurate results so that the 2-D structure of the physical <span class="hlt">model</span> is satisfactorily reconstructed. The <span class="hlt">velocity</span> gradients within each layer are accurately retrieved as well, confirming current theoretical and experimental studies regarding guided surface acoustic modes in unconsolidated granular media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27364351','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27364351"><span id="translatedtitle">A full-dimensional <span class="hlt">model</span> of ozone forming reaction: the <span class="hlt">absolute</span> value of the recombination rate coefficient, its pressure and temperature dependencies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teplukhin, Alexander; Babikov, Dmitri</p> <p>2016-07-28</p> <p>Rigorous calculations of scattering resonances in ozone are carried out for a broad range of rotational excitations. The accurate potential energy surface of Dawes is adopted, and a new efficient method for calculations of ro-vibrational energies, wave functions and resonance lifetimes is employed (which uses hyper-spherical coordinates, the sequential diagonalization/truncation approach, grid optimization and complex absorbing potential). A detailed analysis is carried out to characterize distributions of resonance energies and lifetimes, their rotational/vibrational content and their positions with respect to the centrifugal barrier. Emphasis is on the contribution of these resonances to the recombination process that forms ozone. It is found that major contributions come from localized resonances at energies near the top of the barrier. Delocalized resonances at higher energies should also be taken into account, while very narrow resonances at low energies (trapped far behind the centrifugal barrier) should be treated as bound states. The <span class="hlt">absolute</span> value of the recombination rate coefficient, its pressure and temperature dependencies are obtained using the energy-transfer <span class="hlt">model</span> developed in the earlier work. Good agreement with experimental data is obtained if one follows the suggestion of Troe, who argued that the energy transfer mechanism of recombination is responsible only for 55% of the recombination rate (with the remaining 45% coming from the competing chaperon mechanism). PMID:27364351</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21471260','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21471260"><span id="translatedtitle"><span class="hlt">MODELING</span> MULTI-WAVELENGTH STELLAR ASTROMETRY. II. DETERMINING <span class="hlt">ABSOLUTE</span> INCLINATIONS, GRAVITY-DARKENING COEFFICIENTS, AND SPOT PARAMETERS OF SINGLE STARS WITH SIM LITE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Coughlin, Jeffrey L.; Harrison, Thomas E.; Gelino, Dawn M.</p> <p>2010-11-10</p> <p>We present a novel technique to determine the <span class="hlt">absolute</span> inclination of single stars using multi-wavelength submilliarcsecond astrometry. The technique exploits the effect of gravity darkening, which causes a wavelength-dependent astrometric displacement parallel to a star's projected rotation axis. We find that this effect is clearly detectable using SIM Lite for various giant stars and rapid rotators, and present detailed <span class="hlt">models</span> for multiple systems using the REFLUX code. We also explore the multi-wavelength astrometric reflex motion induced by spots on single stars. We find that it should be possible to determine spot size, relative temperature, and some positional information for both giant and nearby main-sequence stars utilizing multi-wavelength SIM Lite data. These data will be extremely useful in stellar and exoplanet astrophysics, as well as supporting the primary SIM Lite mission through proper multi-wavelength calibration of the giant star astrometric reference frame, and reduction of noise introduced by starspots when searching for extrasolar planets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001GeoJI.145...19N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001GeoJI.145...19N"><span id="translatedtitle">Seismic <span class="hlt">velocity</span> anisotropy in mica-rich rocks: an inclusion <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishizawa, O.; Yoshino, T.</p> <p>2001-04-01</p> <p>We calculated seismic wave <span class="hlt">velocity</span> anisotropy caused by the preferred orientation of mica minerals by using the differential effective medium method (DEM). Spheroidal biotite crystals with their c-axes coinciding with the symmetry axis of the spheroid are embedded in an isotropic matrix up to a volume ratio of 30 per cent. All crystals are aligned with their c-axes parallel to the symmetry axis of the effective homogeneous medium, which shows transverse isotropy. The effect of crystal shape on anisotropy was studied by changing the aspect ratio (the ratio between the minor axis and the major axis of the spheroid) from 0.01 (flat spheroid) to 1 (sphere). The S-<span class="hlt">velocity</span> anisotropy becomes large as the crystal shape becomes flat, whereas the P-<span class="hlt">velocity</span> anisotropy shows only small changes with changes of the crystal shape. In particular, biotite generates large S-wave anisotropy, and the anisotropy becomes stronger as the aspect ratio of the biotite crystal becomes smaller. When the volume ratio of the mica mineral is large, the P-wave phase <span class="hlt">velocity</span> surface shows considerable deviation from the ellipse, and the SV-wave phase <span class="hlt">velocity</span> surface forms a large bulge and crosses the SH-wave phase <span class="hlt">velocity</span> surface (singularity) in the plane including the symmetry axis. These results show an interesting contrast when compared with the effect of crack or pore shape on seismic <span class="hlt">velocity</span> anisotropy: crack (or pore) shape affects the P <span class="hlt">velocity</span> more than the S <span class="hlt">velocity</span>. We also calculated Thomsen's anisotropic parameters, ɛ, γ and δ as functions of the crystal aspect ratio and the mica volume ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26022836','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26022836"><span id="translatedtitle"><span class="hlt">Absolutely</span> relative or relatively <span class="hlt">absolute</span>: violations of value invariance in human decision making.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Teodorescu, Andrei R; Moran, Rani; Usher, Marius</p> <p>2016-02-01</p> <p>Making decisions based on relative rather than <span class="hlt">absolute</span> information processing is tied to choice optimality via the accumulation of evidence differences and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to <span class="hlt">absolute</span> intensities that maintain differences and ratios, respectively. While information about the <span class="hlt">absolute</span> values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision. To test the sensitivity of human decision making to <span class="hlt">absolute</span> values, we manipulated the intensities of brightness stimuli pairs while preserving either their differences or their ratios. Although asked to choose the brighter alternative relative to the other, participants responded faster to higher <span class="hlt">absolute</span> values. Thus, our results provide empirical evidence for human sensitivity to task irrelevant <span class="hlt">absolute</span> values indicating a hard-wired mechanism that precedes executive control. Computational investigations of several <span class="hlt">modelling</span> architectures reveal two alternative accounts for this phenomenon, which combine <span class="hlt">absolute</span> and relative processing. One account involves accumulation of differences with activation dependent processing noise and the other emerges from accumulation of <span class="hlt">absolute</span> values subject to the temporal dynamics of lateral inhibition. The potential adaptive role of such choice mechanisms is discussed. PMID:26022836</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.S43B2808S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.S43B2808S&link_type=ABSTRACT"><span id="translatedtitle">Near Surface Shear Wave <span class="hlt">Velocity</span> <span class="hlt">Model</span> of the Sacramento-San Joaquin Delta</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shuler, S.; Craig, M. S.; Hayashi, K.; Galvin, J. L.; Deqiang, C.; Jones, M. G.</p> <p>2015-12-01</p> <p>Multichannel analysis of surface wave measurements (MASW) and microtremor array measurements (MAM) were performed at twelve sites across the Sacramento-San Joaquin Delta to obtain high resolution shear wave <span class="hlt">velocity</span> (VS) <span class="hlt">models</span>. Deeper surveys were performed at four of the sites using the two station spatial autocorrelation (SPAC) method. For the MASW and MAM surveys, a 48-channel seismic system with 4.5 Hz geophones was used with a 10-lb sledgehammer and a metal plate as a source. Surveys were conducted at various locations on the crest of levees, the toe of the levees, and off of the levees. For MASW surveys, we used a record length of 2.048 s, a sample interval of 1 ms, and 1 m geophone spacing. For MAM, ambient noise was recorded for 65.536 s with a sampling interval of 4 ms and 1 m geophone spacing. VS was determined to depths of ~ 20 m using the MASW method and ~ 40 m using the MAM method. Maximum separation between stations in the two-station SPAC surveys was typically 1600 m to 1800 m, providing coherent signal with wavelengths in excess of 5 km and depth penetration of as much as 2000 m. Measured values of VS30 in the study area ranged from 97 m/s to 257 m/s, corresponding to NEHRP site classifications D and E. Comparison of our measured <span class="hlt">velocity</span> profiles with available geotechnical logs, including soil type, SPT, and CPT, reveals the existence of a small number of characteristic horizons within the upper 40m in the Delta: levee fill material, peat, transitional silty sand, and eolian sand at depth. Sites with a peat layer at the surface exhibited extremely low values of VS. Based on soil borings, the thickness of peat layers were approximately 0 m to 8 m. The VS for the peat layers ranged from 42 m/s to 150 m/s while the eolian sand layer exhibited VS ranging from of 220 m/s to 370 m/s. Soft near surface soils present in the region pose an increased earthquake hazard risk due to the potential for high ground accelerations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/16463910','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/16463910"><span id="translatedtitle">Implants as <span class="hlt">absolute</span> anchorage.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rungcharassaeng, Kitichai; Kan, Joseph Y K; Caruso, Joseph M</p> <p>2005-11-01</p> <p>Anchorage control is essential for successful orthodontic treatment. Each tooth has its own anchorage potential as well as propensity to move when force is applied. When teeth are used as anchorage, the untoward movements of the anchoring units may result in the prolonged treatment time, and unpredictable or less-than-ideal outcome. To maximize tooth-related anchorage, techniques such as differential torque, placing roots into the cortex of the bone, the use of various intraoral devices and/or extraoral appliances have been implemented. Implants, as they are in direct contact with bone, do not possess a periodontal ligament. As a result, they do not move when orthodontic/orthopedic force is applied, and therefore can be used as "<span class="hlt">absolute</span> anchorage." This article describes different types of implants that have been used as orthodontic anchorage. Their clinical applications and limitations are also discussed. PMID:16463910</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040110742','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040110742"><span id="translatedtitle"><span class="hlt">Absolute</span> Equilibrium Entropy</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shebalin, John V.</p> <p>1997-01-01</p> <p>The entropy associated with <span class="hlt">absolute</span> equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/966531','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/966531"><span id="translatedtitle">Developing regionalized <span class="hlt">models</span> of lithospheric thickness and <span class="hlt">velocity</span> structure across Eurasia and the Middle East from jointly inverting P-wave and S-wave receiver functions with Rayleigh wave group and phase <span class="hlt">velocities</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Julia, J; Nyblade, A; Hansen, S; Rodgers, A; Matzel, E</p> <p>2009-07-06</p> <p>In this project, we are developing <span class="hlt">models</span> of lithospheric structure for a wide variety of tectonic regions throughout Eurasia and the Middle East by regionalizing 1D <span class="hlt">velocity</span> <span class="hlt">models</span> obtained by jointly inverting P-wave and S-wave receiver functions with Rayleigh wave group and phase <span class="hlt">velocities</span>. We expect the regionalized <span class="hlt">velocity</span> <span class="hlt">models</span> will improve our ability to predict travel-times for local and regional phases, such as Pg, Pn, Sn and Lg, as well as travel-times for body-waves at upper mantle triplication distances in both seismic and aseismic regions of Eurasia and the Middle East. We anticipate the <span class="hlt">models</span> will help inform and strengthen ongoing and future efforts within the NNSA labs to develop 3D <span class="hlt">velocity</span> <span class="hlt">models</span> for Eurasia and the Middle East, and will assist in obtaining <span class="hlt">model</span>-based predictions where no empirical data are available and for improving locations from sparse networks using kriging. The codes needed to conduct the joint inversion of P-wave receiver functions (PRFs), S-wave receiver functions (SRFs), and dispersion <span class="hlt">velocities</span> have already been assembled as part of ongoing research on lithospheric structure in Africa. The methodology has been tested with synthetic 'data' and case studies have been investigated with data collected at an open broadband stations in South Africa. PRFs constrain the size and S-P travel-time of seismic discontinuities in the crust and uppermost mantle, SRFs constrain the size and P-S travel-time of the lithosphere-asthenosphere boundary, and dispersion <span class="hlt">velocities</span> constrain average S-wave <span class="hlt">velocity</span> within frequency-dependent depth-ranges. Preliminary results show that the combination yields integrated 1D <span class="hlt">velocity</span> <span class="hlt">models</span> local to the recording station, where the discontinuities constrained by the receiver functions are superimposed to a background <span class="hlt">velocity</span> <span class="hlt">model</span> constrained by the dispersion <span class="hlt">velocities</span>. In our first year of this project we will (i) generate 1D <span class="hlt">velocity</span> <span class="hlt">models</span> for open broadband seismic stations in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V51E3077D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015AGUFM.V51E3077D&link_type=ABSTRACT"><span id="translatedtitle">Effect of particle volume fraction on the settling <span class="hlt">velocity</span> of volcanic ash particles: implications for ash dispersion <span class="hlt">models</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Del Bello, E.; Taddeucci, J.; De'Michieli Vitturi, M.; Scarlato, P.; Andronico, D.; Scollo, S.; Kueppers, U.</p> <p>2015-12-01</p> <p>We present the first report of experimental measurements of the enhanced settling <span class="hlt">velocity</span> of volcanic particles as function of particle volume fraction. In order to investigate the differences in the aerodynamic behavior of ash particles when settling individually or in mass, we performed systematic large-scale ash settling experiments using natural basaltic and phonolitic ash. By releasing ash particles at different, controlled volumetric flow rates, in an unconstrained open space and at minimal air movement, we measured their terminal <span class="hlt">velocity</span>, size, and particle volume fraction with a high-speed camera at 2000 fps. Enhanced settling <span class="hlt">velocities</span> of individual particles increase with increasing particle volume fraction. This suggests that particle clustering during fallout may be one reason explaining larger than theoretical depletion rates of fine particles from volcanic ash clouds. We provide a quantitative empirical <span class="hlt">model</span> that allows to calculate, from a given particle size and density, the enhanced <span class="hlt">velocity</span> resulting from a given particle volume fraction. The proposed <span class="hlt">model</span> has the potential to serve as a simple tool for the prediction of the terminal <span class="hlt">velocity</span> of ash of an hypothetical distribution of ash of known particle size and volume fraction. This is of particular importance for advection-diffusion transport <span class="hlt">model</span> of ash where generally a one-way coupling is adopted, considering only the flow effects on particles. To better quantify the importance of the enhanced settling <span class="hlt">velocity</span> in ash dispersal, we finally introduced the new formulation in a Lagrangian <span class="hlt">model</span> calculating for realistic eruptive conditions the resulting ash concentration in the atmosphere and on the ground.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhRvE..78e1912K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhRvE..78e1912K"><span id="translatedtitle">Active transport on disordered microtubule networks: The generalized random <span class="hlt">velocity</span> <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kahana, Aviv; Kenan, Gilad; Feingold, Mario; Elbaum, Michael; Granek, Rony</p> <p>2008-11-01</p> <p>The motion of small cargo particles on microtubules by means of motor proteins in disordered microtubule networks is investigated theoretically using both analytical tools and computer simulations. Different network topologies in two and three dimensions are considered, one of which has been recently studied experimentally by Salman [Biophys. J. 89, 2134 (2005)]. A generalization of the random <span class="hlt">velocity</span> <span class="hlt">model</span> is used to derive the mean-square displacement of the cargo particle. We find that all cases belong to the class of anomalous superdiffusion, which is sensitive mainly to the dimensionality of the network and only marginally to its topology. Yet in three dimensions the motion is very close to simple diffusion, with sublogarithmic corrections that depend on the network topology. When details of the thermal diffusion in the bulk solution are included, no significant change to the asymptotic time behavior is found. However, a small asymmetry in the mean microtubule polarity affects the corresponding long-time behavior. We also study a three-dimensional <span class="hlt">model</span> of the microtubule network in living animal cells. Three first-passage-time problems of intracellular transport are simulated and analyzed for different motor processivities: (i) cargo that originates near the nucleus and has to reach the membrane, (ii) cargo that originates from the membrane and has to reach the nucleus, and (iii) cargo that leaves the nucleus and has to reach a specific target in the cytoplasm. We conclude that while a higher motor processivity increases the transport efficiency in cases (i) and (ii), in case (iii) it has the opposite effect. We conjecture that the balance between the different network tasks, as manifested in cases (i) and (ii) versus case (iii), may be the reason for the evolutionary choice of a finite motor processivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.2015W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.2015W"><span id="translatedtitle">Advantages of a conservative <span class="hlt">velocity</span> interpolation (CVI) scheme for particle-in-cell methods with application in geodynamic <span class="hlt">modeling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Hongliang; Agrusta, Roberto; Hunen, Jeroen</p> <p>2015-06-01</p> <p>The particle-in-cell method is generally considered a flexible and robust method to <span class="hlt">model</span> the geodynamic problems with chemical heterogeneity. However, <span class="hlt">velocity</span> interpolation from grid points to particle locations is often performed without considering the divergence of the <span class="hlt">velocity</span> field, which can lead to significant particle dispersion or clustering if those particles move through regions of strong <span class="hlt">velocity</span> gradients. This may ultimately result in cells void of particles, which, if left untreated, may, in turn, lead to numerical inaccuracies. Here we apply a two-dimensional conservative <span class="hlt">velocity</span> interpolation (CVI) scheme to steady state and time-dependent flow fields with strong <span class="hlt">velocity</span> gradients (e.g., due to large local viscosity variation) and derive and apply the three-dimensional equivalent. We show that the introduction of CVI significantly reduces the dispersion and clustering of particles in both steady state and time-dependent flow problems and maintains a locally steady number of particles, without the need for ad hoc remedies such as very high initial particle densities or reseeding during the calculation. We illustrate that this method provides a significant improvement to particle distributions in common geodynamic <span class="hlt">modeling</span> problems such as subduction zones or lithosphere-asthenosphere boundary dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JKPS...61..371L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JKPS...61..371L"><span id="translatedtitle">Relationships of the phase <span class="hlt">velocity</span> with the microarchitectural parameters in bovine trabecular bone in vitro: Application of a stratified <span class="hlt">model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Kang Il</p> <p>2012-08-01</p> <p>The present study aims to provide insight into the relationships of the phase <span class="hlt">velocity</span> with the microarchitectural parameters in bovine trabecular bone in vitro. The frequency-dependent phase <span class="hlt">velocity</span> was measured in 22 bovine femoral trabecular bone samples by using a pair of transducers with a diameter of 25.4 mm and a center frequency of 0.5 MHz. The phase <span class="hlt">velocity</span> exhibited positive correlation coefficients of 0.48 and 0.32 with the ratio of bone volume to total volume and the trabecular thickness, respectively, but a negative correlation coefficient of -0.62 with the trabecular separation. The best univariate predictor of the phase <span class="hlt">velocity</span> was the trabecular separation, yielding an adjusted squared correlation coefficient of 0.36. The multivariate regression <span class="hlt">models</span> yielded adjusted squared correlation coefficients of 0.21-0.36. The theoretical phase <span class="hlt">velocity</span> predicted by using a stratified <span class="hlt">model</span> for wave propagation in periodically stratified media consisting of alternating parallel solid-fluid layers showed reasonable agreements with the experimental measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3938504','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3938504"><span id="translatedtitle">Using Multivariate Regression <span class="hlt">Model</span> with Least <span class="hlt">Absolute</span> Shrinkage and Selection Operator (LASSO) to Predict the Incidence of Xerostomia after Intensity-Modulated Radiotherapy for Head and Neck Cancer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ting, Hui-Min; Chang, Liyun; Huang, Yu-Jie; Wu, Jia-Ming; Wang, Hung-Yu; Horng, Mong-Fong; Chang, Chun-Ming; Lan, Jen-Hong; Huang, Ya-Yu; Fang, Fu-Min; Leung, Stephen Wan</p> <p>2014-01-01</p> <p>Purpose The aim of this study was to develop a multivariate logistic regression <span class="hlt">model</span> with least <span class="hlt">absolute</span> shrinkage and selection operator (LASSO) to make valid predictions about the incidence of moderate-to-severe patient-rated xerostomia among head and neck cancer (HNC) patients treated with IMRT. Methods and Materials Quality of life questionnaire datasets from 206 patients with HNC were analyzed. The European Organization for Research and Treatment of Cancer QLQ-H&N35 and QLQ-C30 questionnaires were used as the endpoint evaluation. The primary endpoint (grade 3+ xerostomia) was defined as moderate-to-severe xerostomia at 3 (XER3m) and 12 months (XER12m) after the completion of IMRT. Normal tissue complication probability (NTCP) <span class="hlt">models</span> were developed. The optimal and suboptimal numbers of prognostic factors for a multivariate logistic regression <span class="hlt">model</span> were determined using the LASSO with bootstrapping technique. Statistical analysis was performed using the scaled Brier score, Nagelkerke R2, chi-squared test, Omnibus, Hosmer-Lemeshow test, and the AUC. Results Eight prognostic factors were selected by LASSO for the 3-month time point: Dmean-c, Dmean-i, age, financial status, T stage, AJCC stage, smoking, and education. Nine prognostic factors were selected for the 12-month time point: Dmean-i, education, Dmean-c, smoking, T stage, baseline xerostomia, alcohol abuse, family history, and node classification. In the selection of the suboptimal number of prognostic factors by LASSO, three suboptimal prognostic factors were fine-tuned by Hosmer-Lemeshow test and AUC, i.e., Dmean-c, Dmean-i, and age for the 3-month time point. Five suboptimal prognostic factors were also selected for the 12-month time point, i.e., Dmean-i, education, Dmean-c, smoking, and T stage. The overall performance for both time points of the NTCP <span class="hlt">model</span> in terms of scaled Brier score, Omnibus, and Nagelkerke R2 was satisfactory and corresponded well with the expected values. Conclusions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S51B4461P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S51B4461P"><span id="translatedtitle">Shear <span class="hlt">velocity</span> <span class="hlt">model</span> for the westernmost Mediterranean from ambient noise and ballistic finite-frequency Rayleigh wave tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Palomeras, I.; Villasenor, A.; Thurner, S.; Levander, A.; Gallart, J.; Harnafi, M.</p> <p>2014-12-01</p> <p>The westernmost Mediterranean comprises the Iberian Peninsula and Morocco, separated by the Alboran Sea and the Algerian Basin. From north to south this region consists of the Pyrenees, resulting from Iberia-Eurasia collision; the Iberian Massif, which has been undeformed since the end of the Paleozoic; the Central System and Iberian Chain, regions with intracontinental Oligocene-Miocene deformation; the Gibraltar Arc (Betics, Rif and Alboran terranes), resulting from post-Oligocene subduction roll-back; and the Atlas Mountains. We analyzed data from recent broad-band array deployments and permanent stations in the area (IberArray and Siberia arrays, the PICASSO array, the University of Munster array, and the Spanish, Portuguese and Moroccan National Networks) to characterize its lithospheric structure. The combined array of 350 stations has an average interstation spacing of ~60 km. We calculated the Rayleigh waves phase <span class="hlt">velocities</span> from ambient noise (periods 4 to 40 s) and teleseismic events (periods 20 to 167 s). We inverted the phase <span class="hlt">velocities</span> to obtain a shear <span class="hlt">velocity</span> <span class="hlt">model</span> for the lithosphere to ~200 km depth. Our results correlate well with the surface expression of the main structural units with higher crustal <span class="hlt">velocity</span> for the Iberian Massif than for the Alpine Iberia and Atlas Mountains. The Gibraltar Arc has lower crustal shear <span class="hlt">velocities</span> than the regional average at all crustal depths. It also shows an arc shaped anomaly with high upper mantle <span class="hlt">velocities</span> (>4.6 km/s) at shallow depths (<65 km) interpreted as the subducting Alboran slab. The hanging slab is depressing the crust of the Gibraltar arc to ~55 km depth, as seen in receiver function data and active source seismic profiles. Low upper mantle <span class="hlt">velocities</span> (<4.2 km/s) are observed beneath the Atlas, the northeastern end of the Betic Mountains and the Late Cenozoic volcanic fields in Iberia and Morocco, indicative of high temperatures at relatively shallow depths, and suggesting that the lithosphere</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5276K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5276K"><span id="translatedtitle">Long-period GPS waveforms. What can GPS bring to Earth seismic <span class="hlt">velocity</span> <span class="hlt">models</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kelevitz, Krisztina; Houlié, Nicolas; Boschi, Lapo; Nissen-Meyer, Tarje; Giardini, Domenico</p> <p>2014-05-01</p> <p>It is now commonly admitted that high rate GPS observations can provide reliable surface displacement waveforms (Cervelli, et al., 2001; Langbein, et al., 2006; Houlié, et al., 2006; Houlié et al., 2011). For long-period (T>5s) transients, it was shown that GPS and seismometer (STS-1) displacements are in agreement at least for vertical component (Houlié, et al., Sci. Rep. 2011). We propose here to supplement existing long-period seismic networks with high rate (>= 1Hz) GPS data in order to improve the resolution of global seismic <span class="hlt">velocity</span> <span class="hlt">models</span>. GPS measurements are providing a wide range of frequencies, going beyond the range of STS-1 in the low frequency end. Nowadays, almost 10.000 GPS receivers would be able to record data at 1 Hz with 3000+ stations already streaming data in Real-Time (RT). The reasons for this quick expansion are the price of receivers, their low maintenance, and the wide range of activities they can be used for (transport, science, public apps, navigation, etc.). We are presenting work completed on the 1Hz GPS records of the Hokkaido earthquake (25th of September, 2003, Mw=8.3). 3D Waveforms have been computed with an improved, stabilised inversion algorithm in order to constrain the ground motion history. Through the better resolution of inversion of the GPS phase observations, we determine displacement waveforms of frequencies ranging from 0.77 mHz to 330 mHz for a selection of sites. We compare inverted GPS waveforms with STS-1 waveforms and synthetic waveforms computed using 3D global wave propagation with SPECFEM. At co-located sites (STS-1 and GPS located within 10km) the agreement is good for the vertical component between seismic (both real and synthetic) and GPS waveforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4111W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4111W"><span id="translatedtitle">2.5D S-wave <span class="hlt">velocity</span> <span class="hlt">model</span> of the TESZ area in northern Poland from receiver function analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilde-Piorko, Monika; Polkowski, Marcin; Grad, Marek</p> <p>2016-04-01</p> <p>Receiver function (RF) locally provides the signature of sharp seismic discontinuities and information about the shear wave (S-wave) <span class="hlt">velocity</span> distribution beneath the seismic station. The data recorded by "13 BB Star" broadband seismic stations (Grad et al., 2015) and by few PASSEQ broadband seismic stations (Wilde-Piórko et al., 2008) are analysed to investigate the crustal and upper mantle structure in the Trans-European Suture Zone (TESZ) in northern Poland. The TESZ is one of the most prominent suture zones in Europe separating the young Palaeozoic platform from the much older Precambrian East European craton. Compilation of over thirty deep seismic refraction and wide angle reflection profiles, vertical seismic profiling in over one hundred thousand boreholes and magnetic, gravity, magnetotelluric and thermal methods allowed for creation a high-resolution 3D P-wave <span class="hlt">velocity</span> <span class="hlt">model</span> down to 60 km depth in the area of Poland (Grad et al. 2016). On the other hand the receiver function methods give an opportunity for creation the S-wave <span class="hlt">velocity</span> <span class="hlt">model</span>. Modified ray-tracing method (Langston, 1977) are used to calculate the response of the structure with dipping interfaces to the incoming plane wave with fixed slowness and back-azimuth. 3D P-wave <span class="hlt">velocity</span> <span class="hlt">model</span> are interpolated to 2.5D P-wave <span class="hlt">velocity</span> <span class="hlt">model</span> beneath each seismic station and synthetic back-azimuthal sections of receiver function are calculated for different Vp/Vs ratio. Densities are calculated with combined formulas of Berteussen (1977) and Gardner et al. (1974). Next, the synthetic back-azimuthal sections of RF are compared with observed back-azimuthal sections of RF for "13 BB Star" and PASSEQ seismic stations to find the best 2.5D S-wave <span class="hlt">models</span> down to 60 km depth. National Science Centre Poland provided financial support for this work by NCN grant DEC-2011/02/A/ST10/00284.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70093890','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70093890"><span id="translatedtitle">Blind test of methods for obtaining 2-D near-surface seismic <span class="hlt">velocity</span> <span class="hlt">models</span> from first-arrival traveltimes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zelt, Colin A.; Haines, Seth; Powers, Michael H.; Sheehan, Jacob; Rohdewald, Siegfried; Link, Curtis; Hayashi, Koichi; Zhao, Don; Zhou, Hua-wei; Burton, Bethany L.; Petersen, Uni K.; Bonal, Nedra D.; Doll, William E.</p> <p>2013-01-01</p> <p>Seismic refraction methods are used in environmental and engineering studies to image the shallow subsurface. We present a blind test of inversion and tomographic refraction analysis methods using a synthetic first-arrival-time dataset that was made available to the community in 2010. The data are realistic in terms of the near-surface <span class="hlt">velocity</span> <span class="hlt">model</span>, shot-receiver geometry and the data's frequency and added noise. Fourteen estimated <span class="hlt">models</span> were determined by ten participants using eight different inversion algorithms, with the true <span class="hlt">model</span> unknown to the participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated <span class="hlt">models</span> are generally consistent in terms of their large-scale features, demonstrating the robustness of refraction data inversion in general, and the eight inversion algorithms in particular. When compared to the true <span class="hlt">model</span>, all of the estimated <span class="hlt">models</span> contain a smooth expression of its two main features: a large offset in the bedrock and the top of a steeply dipping low-<span class="hlt">velocity</span> fault zone. The estimated <span class="hlt">models</span> do not contain a subtle low-<span class="hlt">velocity</span> zone and other fine-scale features, in accord with conventional wisdom. Together, the results support confidence in the reliability and robustness of modern refraction inversion and tomographic methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.7430F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.7430F"><span id="translatedtitle">Microseismic monitoring of soft-rock landslide: contribution of a 3D <span class="hlt">velocity</span> <span class="hlt">model</span> for the location of seismic sources.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Floriane, Provost; Jean-Philippe, Malet; Cécile, Doubre; Julien, Gance; Alessia, Maggi; Agnès, Helmstetter</p> <p>2015-04-01</p> <p>Characterizing the micro-seismic activity of landslides is an important parameter for a better understanding of the physical processes controlling landslide behaviour. However, the location of the seismic sources on landslides is a challenging task mostly because of (a) the recording system geometry, (b) the lack of clear P-wave arrivals and clear wave differentiation, (c) the heterogeneous <span class="hlt">velocities</span> of the ground. The objective of this work is therefore to test whether the integration of a 3D <span class="hlt">velocity</span> <span class="hlt">model</span> in probabilistic seismic source location codes improves the quality of the determination especially in depth. We studied the clay-rich landslide of Super-Sauze (French Alps). Most of the seismic events (rockfalls, slidequakes, tremors...) are generated in the upper part of the landslide near the main scarp. The seismic recording system is composed of two antennas with four vertical seismometers each located on the east and west sides of the seismically active part of the landslide. A refraction seismic campaign was conducted in August 2014 and a 3D P-wave <span class="hlt">model</span> has been estimated using the Quasi-Newton tomography inversion algorithm. The shots of the seismic campaign are used as calibration shots to test the performance of the different location methods and to further update the 3D <span class="hlt">velocity</span> <span class="hlt">model</span>. Natural seismic events are detected with a semi-automatic technique using a frequency threshold. The first arrivals are picked using a kurtosis-based method and compared to the manual picking. Several location methods were finally tested. We compared a non-linear probabilistic method coupled with the 3D P-wave <span class="hlt">model</span> and a beam-forming method inverted for an apparent <span class="hlt">velocity</span>. We found that the Quasi-Newton tomography inversion algorithm provides results coherent with the original underlaying topography. The <span class="hlt">velocity</span> ranges from 500 m.s-1 at the surface to 3000 m.s-1 in the bedrock. For the majority of the calibration shots, the use of a 3D <span class="hlt">velocity</span> <span class="hlt">model</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..DMP.T1082K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DMP.T1082K"><span id="translatedtitle">Laboratory and <span class="hlt">Modeling</span> Studies of <span class="hlt">Velocity</span>-Changing Collisions, Spin-Changing Collisions, and Magnetic Fields on Sodium Guidestars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kostinski, Natalie; Dimitrova, Ivana; Happer, William</p> <p>2010-03-01</p> <p>Lasers used to produce sodium guidestars can cause optical pumping of Na atoms, but only interact with atoms that possess resonant Doppler shift. The number density of atmospheric constituents (e.g., Na, N2, O, O2) is so low, that there is minimal collision broadening of the optical absorption lines and distinct <span class="hlt">velocity</span> groups can be excited. A goal of our work is <span class="hlt">modeling</span> and laboratory studies of the correlations between the atomic spin polarization and the atomic <span class="hlt">velocity</span> along the pumping beam. We believe this will aid in understanding the various mechanisms (collision processes, geomagnetic field) that can influence guidestar signal strength. This work should lead to a better understanding of the relative importance of strong and weak <span class="hlt">velocity</span>-changing collisions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.A12F..07P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.A12F..07P"><span id="translatedtitle">Sensitivity Study of the Vertical <span class="hlt">Velocity</span> Variation on Cloud Droplet Nucleation Process Using an Adiabatic Parcel <span class="hlt">Model</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peng, Y.; Lohmann, U.; Leaitch, R. W.</p> <p>2003-12-01</p> <p>Eleven profiles through liquid water cloud obtained during RACE (Radiation, Aerosol and Cloud Experiment) and NARE (North Atlantic Regional Experiment) are used to study the sensitivity of cloud droplet nucleation to the vertical gust <span class="hlt">velocity</span>. Selected cloud microphysical data, size-distributed aerosol properties and particle chemistry are applied in an adiabatic parcel <span class="hlt">model</span> to predict the activated cloud droplet number concentrations (N) using the frequency distribution of the measured in-cloud vertical <span class="hlt">velocities</span> and again using a vertical <span class="hlt">velocity</span> characteristic of observations. The simulated adiabatic value of N obtained using the standard deviation of the vertical <span class="hlt">velocity</span> distribution agrees with the observed maximum N (the cloud droplet number in an adiabetic core) to within 5%. If the parameterization derived by Lin et al. [1997] is applied to obtain the cloud-average N from the maximum N, the average N agrees with the observed cloud-average N to within 20%. The simulated N obtained using the full probability density function of the vertical gust <span class="hlt">velocities</span> is one approach that has been used to represent the cloud average N. This is based on the assumption that the average N is controlled by all variations in the updraft and not by the mixing process [Leaitch et al. 1996]. The value of N obtained in this manner is found to be higher than the observed average N by a factor of two. We believe that this result is because low vertical <span class="hlt">velocities</span> do not contribute effectively to the cloud droplet nucleation. If we neglect the lowest 45% of all vertical <span class="hlt">velocities</span>, then the difference between the simulated average N and the observed mean N is reduced to within 13%. These results suggest that it is appropriate to use a characteristic vertical <span class="hlt">velocity</span> to predict the cloud droplet number concentration in climate <span class="hlt">models</span> as done by Lohmann et al. [1999], where the subgrid variation of vertical <span class="hlt">velocity</span> is diagnosed from the turbulent kinetic energy. The frequency</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.S43B4572K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.S43B4572K&link_type=ABSTRACT"><span id="translatedtitle">High Resolution <span class="hlt">Models</span> of Regional Phase Attenuation and <span class="hlt">Velocity</span> Structure of the Turkish-Iranian Plateau and Zagros</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaviani, A.; Sandvol, E. A.; Bao, X.; Gok, R.; Rumpker, G.</p> <p>2014-12-01</p> <p>We present an approach for understanding the origin and nature of seismic anomalies in the continental crust of the Northern Middle East. We have constructed detailed <span class="hlt">models</span> of crustal attenuation and <span class="hlt">velocity</span> structure for the Northern Middle East based on the analysis of waveforms of the regional seismic phases Lg and Pg from regional earthquakes recorded at more than 550 stations in Turkish and Iranian Plateaus and the surrounding regions. The attenuation and <span class="hlt">velocity</span> <span class="hlt">models</span> are assumed to serve as proxies for the bulk average effective crustal P-wave and S-wave attenuation (Qa and Qb) and <span class="hlt">velocities</span> (Vp and Vs). About 30000 reliable spectra were collected for both Lg and Pg phases and used to measure the Two-Station Method (TSM) and Reverse Two-station/event Method (RTM) Lg and Pg Q at 1 Hz (QLg0 and QPg0) and their frequency dependence factor (η). The QLg0 and QPg0 and η values measured over the individual TSM and RTM paths are then used to perform an LSQR tomographic inversion for lateral variations in Q0 and η. We observe a strong correlation between the effective Q and <span class="hlt">velocity</span> <span class="hlt">models</span>. Our <span class="hlt">models</span> show lateral variations that coincide with the major tectonic boundaries in the region. The tomographic <span class="hlt">models</span> as well as the individual TSM and RTM measurements show lower values of QLg0 and QPg0 over the Turkish-Anatolian Plateau (QLg0<150 and QPg0<200) than those observed over the Iranian Plateau (150< QLg0<300 and 150< QPg0<400). Furthermore, we obtain