Science.gov

Sample records for accurate source parameters

  1. Accurate Stellar Parameters for Exoplanet Host Stars

    NASA Astrophysics Data System (ADS)

    Brewer, John Michael; Fischer, Debra; Basu, Sarbani; Valenti, Jeff A.

    2015-01-01

    A large impedement to our understanding of planet formation is obtaining a clear picture of planet radii and densities. Although determining precise ratios between planet and stellar host are relatively easy, determining accurate stellar parameters is still a difficult and costly undertaking. High resolution spectral analysis has traditionally yielded precise values for some stellar parameters but stars in common between catalogs from different authors or analyzed using different techniques often show offsets far in excess of their uncertainties. Most analyses now use some external constraint, when available, to break observed degeneracies between surface gravity, effective temperature, and metallicity which can otherwise lead to correlated errors in results. However, these external constraints are impossible to obtain for all stars and can require more costly observations than the initial high resolution spectra. We demonstrate that these discrepencies can be mitigated by use of a larger line list that has carefully tuned atomic line data. We use an iterative modeling technique that does not require external constraints. We compare the surface gravity obtained with our spectral synthesis modeling to asteroseismically determined values for 42 Kepler stars. Our analysis agrees well with only a 0.048 dex offset and an rms scatter of 0.05 dex. Such accurate stellar gravities can reduce the primary source of uncertainty in radii by almost an order of magnitude over unconstrained spectral analysis.

  2. Accurate shear measurement with faint sources

    SciTech Connect

    Zhang, Jun; Foucaud, Sebastien; Luo, Wentao E-mail: walt@shao.ac.cn

    2015-01-01

    For cosmic shear to become an accurate cosmological probe, systematic errors in the shear measurement method must be unambiguously identified and corrected for. Previous work of this series has demonstrated that cosmic shears can be measured accurately in Fourier space in the presence of background noise and finite pixel size, without assumptions on the morphologies of galaxy and PSF. The remaining major source of error is source Poisson noise, due to the finiteness of source photon number. This problem is particularly important for faint galaxies in space-based weak lensing measurements, and for ground-based images of short exposure times. In this work, we propose a simple and rigorous way of removing the shear bias from the source Poisson noise. Our noise treatment can be generalized for images made of multiple exposures through MultiDrizzle. This is demonstrated with the SDSS and COSMOS/ACS data. With a large ensemble of mock galaxy images of unrestricted morphologies, we show that our shear measurement method can achieve sub-percent level accuracy even for images of signal-to-noise ratio less than 5 in general, making it the most promising technique for cosmic shear measurement in the ongoing and upcoming large scale galaxy surveys.

  3. Accurate Parameter Estimation for Unbalanced Three-Phase System

    PubMed Central

    Chen, Yuan

    2014-01-01

    Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS. PMID:25162056

  4. Accurate parameter estimation for unbalanced three-phase system.

    PubMed

    Chen, Yuan; So, Hing Cheung

    2014-01-01

    Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS.

  5. Machine learning of parameters for accurate semiempirical quantum chemical calculations

    SciTech Connect

    Dral, Pavlo O.; von Lilienfeld, O. Anatole; Thiel, Walter

    2015-04-14

    We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempirical OM2 method using a set of 6095 constitutional isomers C7H10O2, for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules.

  6. Machine learning of parameters for accurate semiempirical quantum chemical calculations

    DOE PAGES

    Dral, Pavlo O.; von Lilienfeld, O. Anatole; Thiel, Walter

    2015-04-14

    We investigate possible improvements in the accuracy of semiempirical quantum chemistry (SQC) methods through the use of machine learning (ML) models for the parameters. For a given class of compounds, ML techniques require sufficiently large training sets to develop ML models that can be used for adapting SQC parameters to reflect changes in molecular composition and geometry. The ML-SQC approach allows the automatic tuning of SQC parameters for individual molecules, thereby improving the accuracy without deteriorating transferability to molecules with molecular descriptors very different from those in the training set. The performance of this approach is demonstrated for the semiempiricalmore » OM2 method using a set of 6095 constitutional isomers C7H10O2, for which accurate ab initio atomization enthalpies are available. The ML-OM2 results show improved average accuracy and a much reduced error range compared with those of standard OM2 results, with mean absolute errors in atomization enthalpies dropping from 6.3 to 1.7 kcal/mol. They are also found to be superior to the results from specific OM2 reparameterizations (rOM2) for the same set of isomers. The ML-SQC approach thus holds promise for fast and reasonably accurate high-throughput screening of materials and molecules.« less

  7. Importance of including small body spin effects in the modelling of intermediate mass-ratio inspirals. II. Accurate parameter extraction of strong sources using higher-order spin effects

    NASA Astrophysics Data System (ADS)

    Huerta, E. A.; Gair, Jonathan R.; Brown, Duncan A.

    2012-03-01

    -4, and 10-1, respectively. LISA should also be able to determine the location of the source in the sky and the SMBH spin orientation to within ˜10-4 steradians. Furthermore, we show that by including conservative corrections up to 2.5PN order, systematic errors no longer dominate over statistical errors. This shows that search templates that include small body spin effects in the equations of motion up to 2.5PN order should allow us to perform accurate parameter extraction for IMRIs with typical signal-to-noise ratio ˜1000.

  8. Direct computation of parameters for accurate polarizable force fields

    SciTech Connect

    Verstraelen, Toon Vandenbrande, Steven; Ayers, Paul W.

    2014-11-21

    We present an improved electronic linear response model to incorporate polarization and charge-transfer effects in polarizable force fields. This model is a generalization of the Atom-Condensed Kohn-Sham Density Functional Theory (DFT), approximated to second order (ACKS2): it can now be defined with any underlying variational theory (next to KS-DFT) and it can include atomic multipoles and off-center basis functions. Parameters in this model are computed efficiently as expectation values of an electronic wavefunction, obviating the need for their calibration, regularization, and manual tuning. In the limit of a complete density and potential basis set in the ACKS2 model, the linear response properties of the underlying theory for a given molecular geometry are reproduced exactly. A numerical validation with a test set of 110 molecules shows that very accurate models can already be obtained with fluctuating charges and dipoles. These features greatly facilitate the development of polarizable force fields.

  9. Accurate radio and optical positions for southern radio sources

    NASA Technical Reports Server (NTRS)

    Harvey, Bruce R.; Jauncey, David L.; White, Graeme L.; Nothnagel, Axel; Nicolson, George D.; Reynolds, John E.; Morabito, David D.; Bartel, Norbert

    1992-01-01

    Accurate radio positions with a precision of about 0.01 arcsec are reported for eight compact extragalactic radio sources south of -45-deg declination. The radio positions were determined using VLBI at 8.4 GHz on the 9589 km Tidbinbilla (Australia) to Hartebeesthoek (South Africa) baseline. The sources were selected from the Parkes Catalogue to be strong, flat-spectrum radio sources with bright optical QSO counterparts. Optical positions of the QSOs were also measured from the ESO B Sky Survey plates with respect to stars from the Perth 70 Catalogue, to an accuracy of about 0.19 arcsec rms. These radio and optical positions are as precise as any presently available in the far southern sky. A comparison of the radio and optical positions confirms the estimated optical position errors and shows that there is overall agreement at the 0.1-arcsec level between the radio and Perth 70 optical reference frames in the far south.

  10. Clinically accurate fetal ECG parameters acquired from maternal abdominal sensors

    PubMed Central

    CLIFFORD, Gari; SAMENI, Reza; WARD, Mr. Jay; ROBINSON, Julian; WOLFBERG, Adam J.

    2011-01-01

    OBJECTIVE To evaluate the accuracy of a novel system for measuring fetal heart rate and ST-segment changes using non-invasive electrodes on the maternal abdomen. STUDY DESIGN Fetal ECGs were recorded using abdominal sensors from 32 term laboring women who had a fetal scalp electrode (FSE) placed for a clinical indication. RESULTS Good quality data for FHR estimation was available in 91.2% of the FSE segments, and 89.9% of the abdominal electrode segments. The root mean square (RMS) error between the FHR data calculated by both methods over all processed segments was 0.36 beats per minute. ST deviation from the isoelectric point ranged from 0 to 14.2% of R-wave amplitude. The RMS error between the ST change calculated by both methods averaged over all processed segments was 3.2%. CONCLUSION FHR and ST change acquired from the maternal abdomen is highly accurate and on average is clinically indistinguishable from FHR and ST change calculated using FSE data. PMID:21514560

  11. Fast, accurate, robust and Open Source Brain Extraction Tool (OSBET)

    NASA Astrophysics Data System (ADS)

    Namias, R.; Donnelly Kehoe, P.; D'Amato, J. P.; Nagel, J.

    2015-12-01

    The removal of non-brain regions in neuroimaging is a critical task to perform a favorable preprocessing. The skull-stripping depends on different factors including the noise level in the image, the anatomy of the subject being scanned and the acquisition sequence. For these and other reasons, an ideal brain extraction method should be fast, accurate, user friendly, open-source and knowledge based (to allow for the interaction with the algorithm in case the expected outcome is not being obtained), producing stable results and making it possible to automate the process for large datasets. There are already a large number of validated tools to perform this task but none of them meets the desired characteristics. In this paper we introduced an open source brain extraction tool (OSBET), composed of four steps using simple well-known operations such as: optimal thresholding, binary morphology, labeling and geometrical analysis that aims to assemble all the desired features. We present an experiment comparing OSBET with other six state-of-the-art techniques against a publicly available dataset consisting of 40 T1-weighted 3D scans and their corresponding manually segmented images. OSBET gave both: a short duration with an excellent accuracy, getting the best Dice Coefficient metric. Further validation should be performed, for instance, in unhealthy population, to generalize its usage for clinical purposes.

  12. Accurate source location from waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, Nian; Shen, Yang; Flinders, Ashton; Zhang, Wei

    2016-06-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (>100 m). In this study, we explore the use of P coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example to provide realistic topography. A grid search algorithm is combined with the 3-D strain Green's tensor database to improve search efficiency as well as the quality of hypocenter solutions. The strain Green's tensor is calculated using a 3-D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are obtained based on the least squares misfit between the "observed" and predicted P and P coda waves. The 95% confidence interval of the solution is provided as an a posteriori error estimation. For shallow events tested in the study, scattering is mainly due to topography in comparison with stochastic lateral velocity heterogeneity. The incorporation of P coda significantly improves solution accuracy and reduces solution uncertainty. The solution remains robust with wide ranges of random noises in data, unmodeled random velocity heterogeneities, and uncertainties in moment tensors. The method can be extended to locate pairs of sources in close proximity by differential waveforms using source-receiver reciprocity, further reducing errors caused by unmodeled velocity structures.

  13. Accurate source location from P waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, N.; Shen, Y.

    2015-12-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (> 100 m). In this study, we explore the use of P-coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example. The grid search method is combined with the 3D strain Green's tensor database type method to improve the search efficiency as well as the quality of hypocenter solution. The strain Green's tensor is calculated by the 3D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are then obtained based on the least-square misfit between the 'observed' and predicted P and P-coda waves. A 95% confidence interval of the solution is also provided as a posterior error estimation. We find that the scattered waves are mainly due to topography in comparison with random velocity heterogeneity characterized by the von Kάrmάn-type power spectral density function. When only P wave data is used, the 'best' solution is offset from the real source location mostly in the vertical direction. The incorporation of P coda significantly improves solution accuracy and reduces its uncertainty. The solution remains robust with a range of random noises in data, un-modeled random velocity heterogeneities, and uncertainties in moment tensors that we tested.

  14. A simple and accurate resist parameter extraction method for sub-80-nm DRAM patterns

    NASA Astrophysics Data System (ADS)

    Lee, Sook; Hwang, Chan; Park, Dong-Woon; Kim, In-Sung; Kim, Ho-Chul; Woo, Sang-Gyun; Cho, Han-Ku; Moon, Joo-Tae

    2004-05-01

    Due to the polarization effect of high NA lithography, the consideration of resist effect in lithography simulation becomes increasingly important. In spite of the importance of resist simulation, many process engineers are reluctant to consider resist effect in lithography simulation due to time-consuming procedure to extract required resist parameters and the uncertainty of measurement of some parameters. Weiss suggested simplified development model, and this model does not require the complex kinetic parameters. For the device fabrication engineers, there is a simple and accurate parameter extraction and optimizing method using Weiss model. This method needs refractive index, Dill"s parameters and development rate monitoring (DRM) data in parameter extraction. The parameters extracted using referred sequence is not accurate, so that we have to optimize the parameters to fit the critical dimension scanning electron microscopy (CD SEM) data of line and space patterns. Hence, the FiRM of Sigma-C is utilized as a resist parameter-optimizing program. According to our study, the illumination shape, the aberration and the pupil mesh point have a large effect on the accuracy of resist parameter in optimization. To obtain the optimum parameters, we need to find the saturated mesh points in terms of normalized intensity log slope (NILS) prior to an optimization. The simulation results using the optimized parameters by this method shows good agreement with experiments for iso-dense bias, Focus-Exposure Matrix data and sub 80nm device pattern simulation.

  15. Local tsunamis and earthquake source parameters

    USGS Publications Warehouse

    Geist, Eric L.; Dmowska, Renata; Saltzman, Barry

    1999-01-01

    This chapter establishes the relationship among earthquake source parameters and the generation, propagation, and run-up of local tsunamis. In general terms, displacement of the seafloor during the earthquake rupture is modeled using the elastic dislocation theory for which the displacement field is dependent on the slip distribution, fault geometry, and the elastic response and properties of the medium. Specifically, nonlinear long-wave theory governs the propagation and run-up of tsunamis. A parametric study is devised to examine the relative importance of individual earthquake source parameters on local tsunamis, because the physics that describes tsunamis from generation through run-up is complex. Analysis of the source parameters of various tsunamigenic earthquakes have indicated that the details of the earthquake source, namely, nonuniform distribution of slip along the fault plane, have a significant effect on the local tsunami run-up. Numerical methods have been developed to address the realistic bathymetric and shoreline conditions. The accuracy of determining the run-up on shore is directly dependent on the source parameters of the earthquake, which provide the initial conditions used for the hydrodynamic models.

  16. Design parameters and source terms: Volume 3, Source terms

    SciTech Connect

    Not Available

    1987-10-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report by Stearns Catalytic Corporation (SCC), entitled ''Design Parameters and Source Terms for a Two-Phase Repository in Salt,'' 1985, to the level of the Site Characterization Plan - Conceptual Design Report. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible Salt Repository sites. 11 refs., 9 tabs.

  17. Bayesian parameter estimation of a k-ε model for accurate jet-in-crossflow simulations

    DOE PAGES

    Ray, Jaideep; Lefantzi, Sophia; Arunajatesan, Srinivasan; Dechant, Lawrence

    2016-05-31

    Reynolds-averaged Navier–Stokes models are not very accurate for high-Reynolds-number compressible jet-in-crossflow interactions. The inaccuracy arises from the use of inappropriate model parameters and model-form errors in the Reynolds-averaged Navier–Stokes model. In this study, the hypothesis is pursued that Reynolds-averaged Navier–Stokes predictions can be significantly improved by using parameters inferred from experimental measurements of a supersonic jet interacting with a transonic crossflow.

  18. The Advanced Photon Source list of parameters

    SciTech Connect

    Bizek, H.M.

    1996-07-01

    The Advanced Photon Source (APS) is a third-generation synchrotron radiation source that stores positrons in a storage ring. The choice of positrons as accelerating particles was motivated by the usual reason: to eliminate the degradation of the beam caused by trapping of positively charged dust particles or ions. The third-generation synchrotron radiation sources are designed to have low beam emittance and many straight sections for insertion devices. The parameter list is comprised of three basic systems: the injection system, the storage ring system, and the experimental facilities system. The components of the injection system are listed according to the causal flow of positrons. Below we briefly list the individual components of the injection system, with the names of people responsible for managing these machines in parentheses: the linac system; electron linac-target-positron linac (Marion White); low energy transport line from linac to the PAR (Michael Borland); positron accumulator ring or PAR (Michael Borland); low energy transport line from PAR to injector synchrotron (Michael Borland); injector synchrotron (Stephen Milton); high energy transport line from injector synchrotron to storage ring (Stephen Milton). The storage ring system, managed by Glenn Decker, uses the Chasman-Green lattice. The APS storage ring, 1104 m in circumference, has 40 periodic sectors. Six are used to house hardware and 34 serve as insertion devices. Another 34 beamlines emit radiation from bending magnets. The experimental facilities system`s parameters include parameters for both an undulator and a wiggler.

  19. Source Parameters of European Intraplate Earthquakes

    NASA Astrophysics Data System (ADS)

    Braunmiller, J.

    2002-12-01

    Seismicity in the European-Mediterranean region follows mainly the plate boundary zones. However, a significant number of earthquakes is located inside the Eurasian plate in Europe. These intraplate events pose a serious hazard; for example, a repeat of the 1356 Basel earthquake, the largest historic earthquake in central Europe, could cause billions of US\\ in damage. The cause for intraplate seismicity is still poorly understood. Systematic fault parameter retrieval may improve our understanding of their origin in relation to the acting stresses and existing geologic structures. Here, I present robust, waveform modeling derived earthquake source parameters that provide the seismic moment tensor (principal stress axes), seismic moment and centroid depth. One data source is the global Harvard CMT catalog covering larger events (moment magnitude M_{w} \\geq 5) for a 26 year period. Such larger intraplate events, that can be analyzed with teleseismic data, occur infrequently. I thus used regional data from the evolving European broadband station network to analyze the more frequent moderate size events of the last three years. The magnitude threshold for regional analysis is M_{w}=4.5. In some areas with dense station coverage events as small as M_{w}$=3.5 can be analyzed. Regional analysis expands the spatial coverage and number of events significantly. The combined source parameter data set contains more than 60 intraplate events in Europe. Most intraplate activity is associated with known weak zones (palaeo-collision zones, former continental rifts and subduction zones, and passive continental margins) and other, slowly moving faults. Distributed seismicity in southeastern Europe may be related to the near-by active subduction and collision zones. Several events are probably mining induced and have large non double-couple source components. Thrust type source mechanisms are restricted to continental margins (offshore Norway) and former subduction zones (Romania

  20. Parameter Estimation of Ion Current Formulations Requires Hybrid Optimization Approach to Be Both Accurate and Reliable

    PubMed Central

    Loewe, Axel; Wilhelms, Mathias; Schmid, Jochen; Krause, Mathias J.; Fischer, Fathima; Thomas, Dierk; Scholz, Eberhard P.; Dössel, Olaf; Seemann, Gunnar

    2016-01-01

    Computational models of cardiac electrophysiology provided insights into arrhythmogenesis and paved the way toward tailored therapies in the last years. To fully leverage in silico models in future research, these models need to be adapted to reflect pathologies, genetic alterations, or pharmacological effects, however. A common approach is to leave the structure of established models unaltered and estimate the values of a set of parameters. Today’s high-throughput patch clamp data acquisition methods require robust, unsupervised algorithms that estimate parameters both accurately and reliably. In this work, two classes of optimization approaches are evaluated: gradient-based trust-region-reflective and derivative-free particle swarm algorithms. Using synthetic input data and different ion current formulations from the Courtemanche et al. electrophysiological model of human atrial myocytes, we show that neither of the two schemes alone succeeds to meet all requirements. Sequential combination of the two algorithms did improve the performance to some extent but not satisfactorily. Thus, we propose a novel hybrid approach coupling the two algorithms in each iteration. This hybrid approach yielded very accurate estimates with minimal dependency on the initial guess using synthetic input data for which a ground truth parameter set exists. When applied to measured data, the hybrid approach yielded the best fit, again with minimal variation. Using the proposed algorithm, a single run is sufficient to estimate the parameters. The degree of superiority over the other investigated algorithms in terms of accuracy and robustness depended on the type of current. In contrast to the non-hybrid approaches, the proposed method proved to be optimal for data of arbitrary signal to noise ratio. The hybrid algorithm proposed in this work provides an important tool to integrate experimental data into computational models both accurately and robustly allowing to assess the often non

  1. An accurate Fortran code for computing hydrogenic continuum wave functions at a wide range of parameters

    NASA Astrophysics Data System (ADS)

    Peng, Liang-You; Gong, Qihuang

    2010-12-01

    The accurate computations of hydrogenic continuum wave functions are very important in many branches of physics such as electron-atom collisions, cold atom physics, and atomic ionization in strong laser fields, etc. Although there already exist various algorithms and codes, most of them are only reliable in a certain ranges of parameters. In some practical applications, accurate continuum wave functions need to be calculated at extremely low energies, large radial distances and/or large angular momentum number. Here we provide such a code, which can generate accurate hydrogenic continuum wave functions and corresponding Coulomb phase shifts at a wide range of parameters. Without any essential restrict to angular momentum number, the present code is able to give reliable results at the electron energy range [10,10] eV for radial distances of [10,10] a.u. We also find the present code is very efficient, which should find numerous applications in many fields such as strong field physics. Program summaryProgram title: HContinuumGautchi Catalogue identifier: AEHD_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEHD_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1233 No. of bytes in distributed program, including test data, etc.: 7405 Distribution format: tar.gz Programming language: Fortran90 in fixed format Computer: AMD Processors Operating system: Linux RAM: 20 MBytes Classification: 2.7, 4.5 Nature of problem: The accurate computation of atomic continuum wave functions is very important in many research fields such as strong field physics and cold atom physics. Although there have already existed various algorithms and codes, most of them can only be applicable and reliable in a certain range of parameters. We present here an accurate FORTRAN program for

  2. How Good are our Source Parameter Estimates for Small Earthquakes?

    NASA Astrophysics Data System (ADS)

    Abercrombie, R. E.

    2002-12-01

    Measuring reliable and accurate source parameters for small earthquakes (M<3) is a long term goal for seismologists. Small earthquakes are important as they bridge the gap between laboratory measurements of stick-slip sliding and large damaging earthquakes. They also provide insights into the nucleation process of unstable slip. Unfortunately, uncertainties in such parameters as the stress drop and radiated energy of small earthquakes are as large as an order of magnitude. This is a consequence of the high frequency radiation (> 100 Hz) needed to resolve the source process. High frequency energy is severely attenuated and distorted along the ray path. The best records of small earthquakes are from deep (> 1km) boreholes and mines, where the waves are recorded before passing through the near-surface rocks. Abercrombie (1995) and Prejean & Ellsworth (2001) used such deep recordings to investigate source scaling and discovered that the radiated energy is a significantly smaller fraction of the total energy than for larger earthquakes. Richardson and Jordan (2002) obtained a similar result from seismograms recorded in deep mines. Ide and Beroza (2001) investigated the effect of limited recording bandwidth in such studies and found that there was evidence of selection bias. Recalculating the source parameters of earthquakes recorded in the Cajon Pass borehole, correcting for the limited bandwidth, does not remove the scale dependence. Ide et al. (2002) used empirical Green's function methods to improve source parameter estimates, and found that even deep borehole recording is not a guarantee of negligible site effects. Another problem is that the lack of multiple recordings of small earthquakes means that very simple source models have to be used to calculate source parameters. The rupture velocity must also be assumed. There are still significant differences (nearly a factor of 10 in stress drop) between the predictions of even the simple models commonly in use. Here I

  3. Time resolved diffuse optical spectroscopy with geometrically accurate models for bulk parameter recovery

    PubMed Central

    Guggenheim, James A.; Bargigia, Ilaria; Farina, Andrea; Pifferi, Antonio; Dehghani, Hamid

    2016-01-01

    A novel straightforward, accessible and efficient approach is presented for performing hyperspectral time-domain diffuse optical spectroscopy to determine the optical properties of samples accurately using geometry specific models. To allow bulk parameter recovery from measured spectra, a set of libraries based on a numerical model of the domain being investigated is developed as opposed to the conventional approach of using an analytical semi-infinite slab approximation, which is known and shown to introduce boundary effects. Results demonstrate that the method improves the accuracy of derived spectrally varying optical properties over the use of the semi-infinite approximation. PMID:27699137

  4. Time resolved diffuse optical spectroscopy with geometrically accurate models for bulk parameter recovery

    PubMed Central

    Guggenheim, James A.; Bargigia, Ilaria; Farina, Andrea; Pifferi, Antonio; Dehghani, Hamid

    2016-01-01

    A novel straightforward, accessible and efficient approach is presented for performing hyperspectral time-domain diffuse optical spectroscopy to determine the optical properties of samples accurately using geometry specific models. To allow bulk parameter recovery from measured spectra, a set of libraries based on a numerical model of the domain being investigated is developed as opposed to the conventional approach of using an analytical semi-infinite slab approximation, which is known and shown to introduce boundary effects. Results demonstrate that the method improves the accuracy of derived spectrally varying optical properties over the use of the semi-infinite approximation.

  5. Accurate estimation of motion blur parameters in noisy remote sensing image

    NASA Astrophysics Data System (ADS)

    Shi, Xueyan; Wang, Lin; Shao, Xiaopeng; Wang, Huilin; Tao, Zhong

    2015-05-01

    The relative motion between remote sensing satellite sensor and objects is one of the most common reasons for remote sensing image degradation. It seriously weakens image data interpretation and information extraction. In practice, point spread function (PSF) should be estimated firstly for image restoration. Identifying motion blur direction and length accurately is very crucial for PSF and restoring image with precision. In general, the regular light-and-dark stripes in the spectrum can be employed to obtain the parameters by using Radon transform. However, serious noise existing in actual remote sensing images often causes the stripes unobvious. The parameters would be difficult to calculate and the error of the result relatively big. In this paper, an improved motion blur parameter identification method to noisy remote sensing image is proposed to solve this problem. The spectrum characteristic of noisy remote sensing image is analyzed firstly. An interactive image segmentation method based on graph theory called GrabCut is adopted to effectively extract the edge of the light center in the spectrum. Motion blur direction is estimated by applying Radon transform on the segmentation result. In order to reduce random error, a method based on whole column statistics is used during calculating blur length. Finally, Lucy-Richardson algorithm is applied to restore the remote sensing images of the moon after estimating blur parameters. The experimental results verify the effectiveness and robustness of our algorithm.

  6. Precise and accurate assessment of uncertainties in model parameters from stellar interferometry. Application to stellar diameters

    NASA Astrophysics Data System (ADS)

    Lachaume, Regis; Rabus, Markus; Jordan, Andres

    2015-08-01

    In stellar interferometry, the assumption that the observables can be seen as Gaussian, independent variables is the norm. In particular, neither the optical interferometry FITS (OIFITS) format nor the most popular fitting software in the field, LITpro, offer means to specify a covariance matrix or non-Gaussian uncertainties. Interferometric observables are correlated by construct, though. Also, the calibration by an instrumental transfer function ensures that the resulting observables are not Gaussian, even if uncalibrated ones happened to be so.While analytic frameworks have been published in the past, they are cumbersome and there is no generic implementation available. We propose here a relatively simple way of dealing with correlated errors without the need to extend the OIFITS specification or making some Gaussian assumptions. By repeatedly picking at random which interferograms, which calibrator stars, and which are the errors on their diameters, and performing the data processing on the bootstrapped data, we derive a sampling of p(O), the multivariate probability density function (PDF) of the observables O. The results can be stored in a normal OIFITS file. Then, given a model m with parameters P predicting observables O = m(P), we can estimate the PDF of the model parameters f(P) = p(m(P)) by using a density estimation of the observables' PDF p.With observations repeated over different baselines, on nights several days apart, and with a significant set of calibrators systematic errors are de facto taken into account. We apply the technique to a precise and accurate assessment of stellar diameters obtained at the Very Large Telescope Interferometer with PIONIER.

  7. Significance of accurate diffraction corrections for the second harmonic wave in determining the acoustic nonlinearity parameter

    SciTech Connect

    Jeong, Hyunjo; Zhang, Shuzeng; Li, Xiongbing; Barnard, Dan

    2015-09-15

    The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α{sub 2} ≃ 2α{sub 1}.

  8. Accurate parameters for HD 209458 and its planet from HST spectrophotometry

    NASA Astrophysics Data System (ADS)

    del Burgo, C.; Allende Prieto, C.

    2016-08-01

    We present updated parameters for the star HD 209458 and its transiting giant planet. The stellar angular diameter θ=0.2254±0.0017 mas is obtained from the average ratio between the absolute flux observed with the Hubble Space Telescope and that of the best-fitting Kurucz model atmosphere. This angular diameter represents an improvement in precision of more than four times compared to available interferometric determinations. The stellar radius R⋆=1.20±0.05 R⊙ is ascertained by combining the angular diameter with the Hipparcos trigonometric parallax, which is the main contributor to its uncertainty, and therefore the radius accuracy should be significantly improved with Gaia's measurements. The radius of the exoplanet Rp=1.41±0.06 RJ is derived from the corresponding transit depth in the light curve and our stellar radius. From the model fitting, we accurately determine the effective temperature, Teff=6071±20 K, which is in perfect agreement with the value of 6070±24 K calculated from the angular diameter and the integrated spectral energy distribution. We also find precise values from recent Padova Isochrones, such as R⋆=1.20±0.06 R⊙ and Teff=6099±41 K. We arrive at a consistent picture from these methods and compare the results with those from the literature.

  9. Accuracy in determining voice source parameters

    NASA Astrophysics Data System (ADS)

    Leonov, A. S.; Sorokin, V. N.

    2014-11-01

    The paper addresses the accuracy of an approximate solution to the inverse problem of retrieving the shape of a voice source from a speech signal for a known signal-to-noise ratio (SNR). It is shown that if the source is found as a function of time with the A.N. Tikhonov regularization method, the accuracy of the found approximation is worse than the accuracy of speech signal recording by an order of magnitude. In contrast, adequate parameterization of the source ensures approximate solution accuracy comparable with the accuracy of the problem data. A corresponding algorithm is considered. On the basis of linear (in terms of data errors) estimates of approximate parametric solution accuracy, parametric models with the best accuracy can be chosen. This comparison has been carried out for the known voice source models, i.e., model [17] and the LF model [18]. The advantages of the latter are shown. Thus, for SNR = 40 dB, the relative accuracy of an approximate solution found with this algorithm is about 1% for the LF model and about 2% for model [17] as compared to an accuracy of 7-8% in the regularization method. The role of accuracy estimates found in speaker identification problems is discussed.

  10. Accurate fundamental parameters and detailed abundance patterns from spectroscopy of 93 solar-type Kepler targets

    NASA Astrophysics Data System (ADS)

    Bruntt, H.; Basu, S.; Smalley, B.; Chaplin, W. J.; Verner, G. A.; Bedding, T. R.; Catala, C.; Gazzano, J.-C.; Molenda-Żakowicz, J.; Thygesen, A. O.; Uytterhoeven, K.; Hekker, S.; Huber, D.; Karoff, C.; Mathur, S.; Mosser, B.; Appourchaux, T.; Campante, T. L.; Elsworth, Y.; García, R. A.; Handberg, R.; Metcalfe, T. S.; Quirion, P.-O.; Régulo, C.; Roxburgh, I. W.; Stello, D.; Christensen-Dalsgaard, J.; Kawaler, S. D.; Kjeldsen, H.; Morris, R. L.; Quintana, E. V.; Sanderfer, D. T.

    2012-06-01

    We present a detailed spectroscopic study of 93 solar-type stars that are targets of the NASA/Kepler mission and provide detailed chemical composition of each target. We find that the overall metallicity is well represented by Fe lines. Relative abundances of light elements (CNO) and α elements are generally higher for low-metallicity stars. Our spectroscopic analysis benefits from the accurately measured surface gravity from the asteroseismic analysis of the Kepler light curves. The accuracy on the log g parameter is better than 0.03 dex and is held fixed in the analysis. We compare our Teff determination with a recent colour calibration of VT-KS [TYCHO V magnitude minus Two Micron All Sky Survey (2MASS) KS magnitude] and find very good agreement and a scatter of only 80 K, showing that for other nearby Kepler targets, this index can be used. The asteroseismic log g values agree very well with the classical determination using Fe I-Fe II balance, although we find a small systematic offset of 0.08 dex (asteroseismic log g values are lower). The abundance patterns of metals, α elements and the light elements (CNO) show that a simple scaling by [Fe/H] is adequate to represent the metallicity of the stars, except for the stars with metallicity below -0.3, where α-enhancement becomes important. However, this is only important for a very small fraction of the Kepler sample. We therefore recommend that a simple scaling with [Fe/H] be employed in the asteroseismic analyses of large ensembles of solar-type stars.

  11. Consistency of VDJ Rearrangement and Substitution Parameters Enables Accurate B Cell Receptor Sequence Annotation

    PubMed Central

    Ralph, Duncan K.; Matsen, Frederick A.

    2016-01-01

    VDJ rearrangement and somatic hypermutation work together to produce antibody-coding B cell receptor (BCR) sequences for a remarkable diversity of antigens. It is now possible to sequence these BCRs in high throughput; analysis of these sequences is bringing new insight into how antibodies develop, in particular for broadly-neutralizing antibodies against HIV and influenza. A fundamental step in such sequence analysis is to annotate each base as coming from a specific one of the V, D, or J genes, or from an N-addition (a.k.a. non-templated insertion). Previous work has used simple parametric distributions to model transitions from state to state in a hidden Markov model (HMM) of VDJ recombination, and assumed that mutations occur via the same process across sites. However, codon frame and other effects have been observed to violate these parametric assumptions for such coding sequences, suggesting that a non-parametric approach to modeling the recombination process could be useful. In our paper, we find that indeed large modern data sets suggest a model using parameter-rich per-allele categorical distributions for HMM transition probabilities and per-allele-per-position mutation probabilities, and that using such a model for inference leads to significantly improved results. We present an accurate and efficient BCR sequence annotation software package using a novel HMM “factorization” strategy. This package, called partis (https://github.com/psathyrella/partis/), is built on a new general-purpose HMM compiler that can perform efficient inference given a simple text description of an HMM. PMID:26751373

  12. Consistency of VDJ Rearrangement and Substitution Parameters Enables Accurate B Cell Receptor Sequence Annotation.

    PubMed

    Ralph, Duncan K; Matsen, Frederick A

    2016-01-01

    VDJ rearrangement and somatic hypermutation work together to produce antibody-coding B cell receptor (BCR) sequences for a remarkable diversity of antigens. It is now possible to sequence these BCRs in high throughput; analysis of these sequences is bringing new insight into how antibodies develop, in particular for broadly-neutralizing antibodies against HIV and influenza. A fundamental step in such sequence analysis is to annotate each base as coming from a specific one of the V, D, or J genes, or from an N-addition (a.k.a. non-templated insertion). Previous work has used simple parametric distributions to model transitions from state to state in a hidden Markov model (HMM) of VDJ recombination, and assumed that mutations occur via the same process across sites. However, codon frame and other effects have been observed to violate these parametric assumptions for such coding sequences, suggesting that a non-parametric approach to modeling the recombination process could be useful. In our paper, we find that indeed large modern data sets suggest a model using parameter-rich per-allele categorical distributions for HMM transition probabilities and per-allele-per-position mutation probabilities, and that using such a model for inference leads to significantly improved results. We present an accurate and efficient BCR sequence annotation software package using a novel HMM "factorization" strategy. This package, called partis (https://github.com/psathyrella/partis/), is built on a new general-purpose HMM compiler that can perform efficient inference given a simple text description of an HMM. PMID:26751373

  13. Effective Temperatures of Selected Main-Sequence Stars with the Most Accurate Parameters

    NASA Astrophysics Data System (ADS)

    Soydugan, F.; Eker, Z.; Soydugan, E.; Bilir, S.; Gökçe, E. Y.; Steer, I.; Tüysüz, M.; Šenyüz, T.; Demircan, O.

    2015-07-01

    In this study we investigate the distributions of the properties of detached double-lined binaries (DBs) in the mass-luminosity, mass-radius, and mass-effective temperature diagrams. We have improved the classical mass-luminosity relation based on the database of DBs by Eker et al. (2014a). Based on the accurate observational data available to us we propose a method for improving the effective temperatures of eclipsing binaries with accurate mass and radius determinations.

  14. Rapid Bayesian point source inversion using pattern recognition --- bridging the gap between regional scaling relations and accurate physical modelling

    NASA Astrophysics Data System (ADS)

    Valentine, A. P.; Kaeufl, P.; De Wit, R. W. L.; Trampert, J.

    2014-12-01

    Obtaining knowledge about source parameters in (near) real-time during or shortly after an earthquake is essential for mitigating damage and directing resources in the aftermath of the event. Therefore, a variety of real-time source-inversion algorithms have been developed over recent decades. This has been driven by the ever-growing availability of dense seismograph networks in many seismogenic areas of the world and the significant advances in real-time telemetry. By definition, these algorithms rely on short time-windows of sparse, local and regional observations, resulting in source estimates that are highly sensitive to observational errors, noise and missing data. In order to obtain estimates more rapidly, many algorithms are either entirely based on empirical scaling relations or make simplifying assumptions about the Earth's structure, which can in turn lead to biased results. It is therefore essential that realistic uncertainty bounds are estimated along with the parameters. A natural means of propagating probabilistic information on source parameters through the entire processing chain from first observations to potential end users and decision makers is provided by the Bayesian formalism.We present a novel method based on pattern recognition allowing us to incorporate highly accurate physical modelling into an uncertainty-aware real-time inversion algorithm. The algorithm is based on a pre-computed Green's functions database, containing a large set of source-receiver paths in a highly heterogeneous crustal model. Unlike similar methods, which often employ a grid search, we use a supervised learning algorithm to relate synthetic waveforms to point source parameters. This training procedure has to be performed only once and leads to a representation of the posterior probability density function p(m|d) --- the distribution of source parameters m given observations d --- which can be evaluated quickly for new data.Owing to the flexibility of the pattern

  15. Disambiguating past events: Accurate source memory for time and context depends on different retrieval processes.

    PubMed

    Persson, Bjorn M; Ainge, James A; O'Connor, Akira R

    2016-07-01

    Current animal models of episodic memory are usually based on demonstrating integrated memory for what happened, where it happened, and when an event took place. These models aim to capture the testable features of the definition of human episodic memory which stresses the temporal component of the memory as a unique piece of source information that allows us to disambiguate one memory from another. Recently though, it has been suggested that a more accurate model of human episodic memory would include contextual rather than temporal source information, as humans' memory for time is relatively poor. Here, two experiments were carried out investigating human memory for temporal and contextual source information, along with the underlying dual process retrieval processes, using an immersive virtual environment paired with a 'Remember-Know' memory task. Experiment 1 (n=28) showed that contextual information could only be retrieved accurately using recollection, while temporal information could be retrieved using either recollection or familiarity. Experiment 2 (n=24), which used a more difficult task, resulting in reduced item recognition rates and therefore less potential for contamination by ceiling effects, replicated the pattern of results from Experiment 1. Dual process theory predicts that it should only be possible to retrieve source context from an event using recollection, and our results are consistent with this prediction. That temporal information can be retrieved using familiarity alone suggests that it may be incorrect to view temporal context as analogous to other typically used source contexts. This latter finding supports the alternative proposal that time since presentation may simply be reflected in the strength of memory trace at retrieval - a measure ideally suited to trace strength interrogation using familiarity, as is typically conceptualised within the dual process framework. PMID:27174312

  16. Accurate Atmospheric Parameters at Moderate Resolution Using Spectral Indices: Preliminary Application to the MARVELS Survey

    NASA Astrophysics Data System (ADS)

    Ghezzi, Luan; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Porto de Mello, Gustavo F.; Santiago, Basílio X.; De Lee, Nathan; Lee, Brian L.; da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; Wisniewski, John P.; González Hernández, Jonay I.; Stassun, Keivan G.; Fleming, Scott W.; Schneider, Donald P.; Mahadevan, Suvrath; Cargile, Phillip; Ge, Jian; Pepper, Joshua; Wang, Ji; Paegert, Martin

    2014-12-01

    Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature T eff, metallicity [Fe/H], and surface gravity log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. Therefore, most surveys employ spectral synthesis, which is a powerful technique, but relies heavily on the completeness and accuracy of atomic line databases and can yield possibly correlated atmospheric parameters. In this work, we use an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R ~ 12,000). To avoid a time-consuming manual analysis, we have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices, and, through a comparison of those with values calculated with predetermined calibrations, estimate the atmospheric parameters of the stars. The calibrations were derived using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra, permitting the low-resolution equivalent widths to be directly related to the stellar parameters. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters derived from the high-resolution spectra and spectroscopic analysis based on the excitation and ionization equilibria method. Our approach was able to recover the parameters within 80 K for T eff, 0.05 dex for [Fe/H], and 0.15 dex for log g, values that are lower than or equal to the typical external uncertainties found between different high-resolution analyses. An additional test was

  17. Accurate atmospheric parameters at moderate resolution using spectral indices: Preliminary application to the marvels survey

    SciTech Connect

    Ghezzi, Luan; Da Costa, Luiz N.; Maia, Marcio A. G.; Ogando, Ricardo L. C.; Dutra-Ferreira, Letícia; Lorenzo-Oliveira, Diego; Porto de Mello, Gustavo F.; Santiago, Basílio X.; De Lee, Nathan; Lee, Brian L.; Ge, Jian; Wisniewski, John P.; González Hernández, Jonay I.; Stassun, Keivan G.; Cargile, Phillip; Pepper, Joshua; Fleming, Scott W.; Schneider, Donald P.; Mahadevan, Suvrath; Wang, Ji; and others

    2014-12-01

    Studies of Galactic chemical, and dynamical evolution in the solar neighborhood depend on the availability of precise atmospheric parameters (effective temperature T {sub eff}, metallicity [Fe/H], and surface gravity log g) for solar-type stars. Many large-scale spectroscopic surveys operate at low to moderate spectral resolution for efficiency in observing large samples, which makes the stellar characterization difficult due to the high degree of blending of spectral features. Therefore, most surveys employ spectral synthesis, which is a powerful technique, but relies heavily on the completeness and accuracy of atomic line databases and can yield possibly correlated atmospheric parameters. In this work, we use an alternative method based on spectral indices to determine the atmospheric parameters of a sample of nearby FGK dwarfs and subgiants observed by the MARVELS survey at moderate resolving power (R ∼ 12,000). To avoid a time-consuming manual analysis, we have developed three codes to automatically normalize the observed spectra, measure the equivalent widths of the indices, and, through a comparison of those with values calculated with predetermined calibrations, estimate the atmospheric parameters of the stars. The calibrations were derived using a sample of 309 stars with precise stellar parameters obtained from the analysis of high-resolution FEROS spectra, permitting the low-resolution equivalent widths to be directly related to the stellar parameters. A validation test of the method was conducted with a sample of 30 MARVELS targets that also have reliable atmospheric parameters derived from the high-resolution spectra and spectroscopic analysis based on the excitation and ionization equilibria method. Our approach was able to recover the parameters within 80 K for T {sub eff}, 0.05 dex for [Fe/H], and 0.15 dex for log g, values that are lower than or equal to the typical external uncertainties found between different high-resolution analyses. An

  18. Polynomial fitting of DT-MRI fiber tracts allows accurate estimation of muscle architectural parameters.

    PubMed

    Damon, Bruce M; Heemskerk, Anneriet M; Ding, Zhaohua

    2012-06-01

    Fiber curvature is a functionally significant muscle structural property, but its estimation from diffusion-tensor magnetic resonance imaging fiber tracking data may be confounded by noise. The purpose of this study was to investigate the use of polynomial fitting of fiber tracts for improving the accuracy and precision of fiber curvature (κ) measurements. Simulated image data sets were created in order to provide data with known values for κ and pennation angle (θ). Simulations were designed to test the effects of increasing inherent fiber curvature (3.8, 7.9, 11.8 and 15.3 m(-1)), signal-to-noise ratio (50, 75, 100 and 150) and voxel geometry (13.8- and 27.0-mm(3) voxel volume with isotropic resolution; 13.5-mm(3) volume with an aspect ratio of 4.0) on κ and θ measurements. In the originally reconstructed tracts, θ was estimated accurately under most curvature and all imaging conditions studied; however, the estimates of κ were imprecise and inaccurate. Fitting the tracts to second-order polynomial functions provided accurate and precise estimates of κ for all conditions except very high curvature (κ=15.3 m(-1)), while preserving the accuracy of the θ estimates. Similarly, polynomial fitting of in vivo fiber tracking data reduced the κ values of fitted tracts from those of unfitted tracts and did not change the θ values. Polynomial fitting of fiber tracts allows accurate estimation of physiologically reasonable values of κ, while preserving the accuracy of θ estimation.

  19. FAST TRACK COMMUNICATION Accurate estimate of α variation and isotope shift parameters in Na and Mg+

    NASA Astrophysics Data System (ADS)

    Sahoo, B. K.

    2010-12-01

    We present accurate calculations of fine-structure constant variation coefficients and isotope shifts in Na and Mg+ using the relativistic coupled-cluster method. In our approach, we are able to discover the roles of various correlation effects explicitly to all orders in these calculations. Most of the results, especially for the excited states, are reported for the first time. It is possible to ascertain suitable anchor and probe lines for the studies of possible variation in the fine-structure constant by using the above results in the considered systems.

  20. Accurate nuclear masses from a three parameter Kohn-Sham DFT approach (BCPM)

    SciTech Connect

    Baldo, M.; Robledo, L. M.; Schuck, P.; Vinas, X.

    2012-10-20

    Given the promising features of the recently proposed Barcelona-Catania-Paris (BCP) functional [1], it is the purpose of this work to still improve on it. It is, for instance, shown that the number of open parameters can be reduced from 4-5 to 2-3, i.e. by practically a factor of two without deteriorating the results.

  1. Accurate parameters of the oldest known rocky-exoplanet hosting system: Kepler-10 revisited

    SciTech Connect

    Fogtmann-Schulz, Alexandra; Hinrup, Brian; Van Eylen, Vincent; Christensen-Dalsgaard, Jørgen; Kjeldsen, Hans; Silva Aguirre, Víctor; Tingley, Brandon

    2014-02-01

    Since the discovery of Kepler-10, the system has received considerable interest because it contains a small, rocky planet which orbits the star in less than a day. The system's parameters, announced by the Kepler team and subsequently used in further research, were based on only five months of data. We have reanalyzed this system using the full span of 29 months of Kepler photometric data, and obtained improved information about its star and the planets. A detailed asteroseismic analysis of the extended time series provides a significant improvement on the stellar parameters: not only can we state that Kepler-10 is the oldest known rocky-planet-harboring system at 10.41 ± 1.36 Gyr, but these parameters combined with improved planetary parameters from new transit fits gives us the radius of Kepler-10b to within just 125 km. A new analysis of the full planetary phase curve leads to new estimates on the planetary temperature and albedo, which remain degenerate in the Kepler band. Our modeling suggests that the flux level during the occultation is slightly lower than at the transit wings, which would imply that the nightside of this planet has a non-negligible temperature.

  2. Earthquake source parameters determined by the SAFOD Pilot Hole seismic array

    USGS Publications Warehouse

    Imanishi, K.; Ellsworth, W.L.; Prejean, S.G.

    2004-01-01

    We estimate the source parameters of #3 microearthquakes by jointly analyzing seismograms recorded by the 32-level, 3-component seismic array installed in the SAFOD Pilot Hole. We applied an inversion procedure to estimate spectral parameters for the omega-square model (spectral level and corner frequency) and Q to displacement amplitude spectra. Because we expect spectral parameters and Q to vary slowly with depth in the well, we impose a smoothness constraint on those parameters as a function of depth using a linear first-differenfee operator. This method correctly resolves corner frequency and Q, which leads to a more accurate estimation of source parameters than can be obtained from single sensors. The stress drop of one example of the SAFOD target repeating earthquake falls in the range of typical tectonic earthquakes. Copyright 2004 by the American Geophysical Union.

  3. Is fluorescence under an alternate light source sufficient to accurately diagnose subclinical bruising?

    PubMed

    Lombardi, Maria; Canter, Jennifer; Patrick, Patricia A; Altman, Robin

    2015-03-01

    This single-blinded, randomized validation study was conducted to evaluate whether fluorescence under alternate light sources (ALS) is sufficient to diagnose subclinical bruising (bruising not visible under white light). Standardized trauma was induced on randomly selected ventral forearms. On days 1, 7, and 14 investigators independently examined case forearms under white light for perceived bruising and under ALS for fluorescence and compared body maps. 56 case and 62 control forearms (n = 118) were examined. Sensitivity of ALS on days 1, 7, and 14 was 76.8%, 69.6%, and 60.7%, respectively, compared to 69.6%, 60.0%, and 32.1% for white light. The specificity of ALS on days 1, 7, and 14 was 51.6%, 59.7%, and 53.2%, respectively, compared to 71.0%, 81.4%, and 86.9% for white light. ALS has increased sensitivity yet low specificity compared to white light in accurately detecting bruises. Fluorescence under ALS is not sufficient to accurately or responsibly diagnose subclinical bruising. PMID:25677469

  4. Is fluorescence under an alternate light source sufficient to accurately diagnose subclinical bruising?

    PubMed

    Lombardi, Maria; Canter, Jennifer; Patrick, Patricia A; Altman, Robin

    2015-03-01

    This single-blinded, randomized validation study was conducted to evaluate whether fluorescence under alternate light sources (ALS) is sufficient to diagnose subclinical bruising (bruising not visible under white light). Standardized trauma was induced on randomly selected ventral forearms. On days 1, 7, and 14 investigators independently examined case forearms under white light for perceived bruising and under ALS for fluorescence and compared body maps. 56 case and 62 control forearms (n = 118) were examined. Sensitivity of ALS on days 1, 7, and 14 was 76.8%, 69.6%, and 60.7%, respectively, compared to 69.6%, 60.0%, and 32.1% for white light. The specificity of ALS on days 1, 7, and 14 was 51.6%, 59.7%, and 53.2%, respectively, compared to 71.0%, 81.4%, and 86.9% for white light. ALS has increased sensitivity yet low specificity compared to white light in accurately detecting bruises. Fluorescence under ALS is not sufficient to accurately or responsibly diagnose subclinical bruising.

  5. PyVCI: A flexible open-source code for calculating accurate molecular infrared spectra

    NASA Astrophysics Data System (ADS)

    Sibaev, Marat; Crittenden, Deborah L.

    2016-06-01

    The PyVCI program package is a general purpose open-source code for simulating accurate molecular spectra, based upon force field expansions of the potential energy surface in normal mode coordinates. It includes harmonic normal coordinate analysis and vibrational configuration interaction (VCI) algorithms, implemented primarily in Python for accessibility but with time-consuming routines written in C. Coriolis coupling terms may be optionally included in the vibrational Hamiltonian. Non-negligible VCI matrix elements are stored in sparse matrix format to alleviate the diagonalization problem. CPU and memory requirements may be further controlled by algorithmic choices and/or numerical screening procedures, and recommended values are established by benchmarking using a test set of 44 molecules for which accurate analytical potential energy surfaces are available. Force fields in normal mode coordinates are obtained from the PyPES library of high quality analytical potential energy surfaces (to 6th order) or by numerical differentiation of analytic second derivatives generated using the GAMESS quantum chemical program package (to 4th order).

  6. Volcanic eruption source parameters from active and passive microwave sensors

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Marzano, Frank S.; Cimini, Domenico; Mereu, Luigi

    2016-04-01

    It is well known, in the volcanology community, that precise information of the source parameters characterising an eruption are of predominant interest for the initialization of the Volcanic Transport and Dispersion Models (VTDM). Source parameters of main interest would be the top altitude of the volcanic plume, the flux of the mass ejected at the emission source, which is strictly related to the cloud top altitude, the distribution of volcanic mass concentration along the vertical column as well as the duration of the eruption and the erupted volume. Usually, the combination of a-posteriori field and numerical studies allow constraining the eruption source parameters for a given volcanic event thus making possible the forecast of ash dispersion and deposition from future volcanic eruptions. So far, remote sensors working at visible and infrared channels (cameras and radiometers) have been mainly used to detect, track and provide estimates of the concentration content and the prevailing size of the particles propagating within the ash clouds up to several thousand of kilometres far from the source as well as track back, a-posteriori, the accuracy of the VATDM outputs thus testing the initial choice made for the source parameters. Acoustic wave (infrasound) and microwave fixed scan radar (voldorad) were also used to infer source parameters. In this work we want to put our attention on the role of sensors operating at microwave wavelengths as complementary tools for the real time estimations of source parameters. Microwaves can benefit of the operability during night and day and a relatively negligible sensitivity to the presence of clouds (non precipitating weather clouds) at the cost of a limited coverage and larger spatial resolution when compared with infrared sensors. Thanks to the aforementioned advantages, the products from microwaves sensors are expected to be sensible mostly to the whole path traversed along the tephra cloud making microwaves particularly

  7. Accurate Prediction of Severe Allergic Reactions by a Small Set of Environmental Parameters (NDVI, Temperature)

    PubMed Central

    Andrianaki, Maria; Azariadis, Kalliopi; Kampouri, Errika; Theodoropoulou, Katerina; Lavrentaki, Katerina; Kastrinakis, Stelios; Kampa, Marilena; Agouridakis, Panagiotis; Pirintsos, Stergios; Castanas, Elias

    2015-01-01

    Severe allergic reactions of unknown etiology,necessitating a hospital visit, have an important impact in the life of affected individuals and impose a major economic burden to societies. The prediction of clinically severe allergic reactions would be of great importance, but current attempts have been limited by the lack of a well-founded applicable methodology and the wide spatiotemporal distribution of allergic reactions. The valid prediction of severe allergies (and especially those needing hospital treatment) in a region, could alert health authorities and implicated individuals to take appropriate preemptive measures. In the present report we have collecterd visits for serious allergic reactions of unknown etiology from two major hospitals in the island of Crete, for two distinct time periods (validation and test sets). We have used the Normalized Difference Vegetation Index (NDVI), a satellite-based, freely available measurement, which is an indicator of live green vegetation at a given geographic area, and a set of meteorological data to develop a model capable of describing and predicting severe allergic reaction frequency. Our analysis has retained NDVI and temperature as accurate identifiers and predictors of increased hospital severe allergic reactions visits. Our approach may contribute towards the development of satellite-based modules, for the prediction of severe allergic reactions in specific, well-defined geographical areas. It could also probably be used for the prediction of other environment related diseases and conditions. PMID:25794106

  8. An Accurate and Generic Testing Approach to Vehicle Stability Parameters Based on GPS and INS

    PubMed Central

    Miao, Zhibin; Zhang, Hongtian; Zhang, Jinzhu

    2015-01-01

    With the development of the vehicle industry, controlling stability has become more and more important. Techniques of evaluating vehicle stability are in high demand. As a common method, usually GPS sensors and INS sensors are applied to measure vehicle stability parameters by fusing data from the two system sensors. Although prior model parameters should be recognized in a Kalman filter, it is usually used to fuse data from multi-sensors. In this paper, a robust, intelligent and precise method to the measurement of vehicle stability is proposed. First, a fuzzy interpolation method is proposed, along with a four-wheel vehicle dynamic model. Second, a two-stage Kalman filter, which fuses the data from GPS and INS, is established. Next, this approach is applied to a case study vehicle to measure yaw rate and sideslip angle. The results show the advantages of the approach. Finally, a simulation and real experiment is made to verify the advantages of this approach. The experimental results showed the merits of this method for measuring vehicle stability, and the approach can meet the design requirements of a vehicle stability controller. PMID:26690154

  9. Can a combination of ultrasonographic parameters accurately evaluate concussion and guide return-to-play decisions?

    PubMed

    Cartwright, Michael S; Dupuis, Janae E; Bargoil, Jessica M; Foster, Dana C

    2015-09-01

    Mild traumatic brain injury, often referred to as concussion, is a common, potentially debilitating, and costly condition. One of the main challenges in diagnosing and managing concussion is that there is not currently an objective test to determine the presence of a concussion and to guide return-to-play decisions for athletes. Traditional neuroimaging tests, such as brain magnetic resonance imaging, are normal in concussion, and therefore diagnosis and management are guided by reported symptoms. Some athletes will under-report symptoms to accelerate their return-to-play and others will over-report symptoms out of fear of further injury or misinterpretation of underlying conditions, such as migraine headache. Therefore, an objective measure is needed to assist in several facets of concussion management. Limited data in animal and human testing indicates that intracranial pressure increases slightly and cerebrovascular reactivity (the ability of the cerebral arteries to auto-regulate in response to changes in carbon dioxide) decreases slightly following mild traumatic brain injury. We hypothesize that a combination of ultrasonographic measurements (optic nerve sheath diameter and transcranial Doppler assessment of cerebrovascular reactivity) into a single index will allow for an accurate and non-invasive measurement of intracranial pressure and cerebrovascular reactivity, and this index will be clinically relevant and useful for guiding concussion diagnosis and management. Ultrasound is an ideal modality for the evaluation of concussion because it is portable (allowing for evaluation in many settings, such as on the playing field or in a combat zone), radiation-free (making repeat scans safe), and relatively inexpensive (resulting in nearly universal availability). This paper reviews the literature supporting our hypothesis that an ultrasonographic index can assist in the diagnosis and management of concussion, and it also presents limited data regarding the

  10. Can a combination of ultrasonographic parameters accurately evaluate concussion and guide return-to-play decisions?

    PubMed

    Cartwright, Michael S; Dupuis, Janae E; Bargoil, Jessica M; Foster, Dana C

    2015-09-01

    Mild traumatic brain injury, often referred to as concussion, is a common, potentially debilitating, and costly condition. One of the main challenges in diagnosing and managing concussion is that there is not currently an objective test to determine the presence of a concussion and to guide return-to-play decisions for athletes. Traditional neuroimaging tests, such as brain magnetic resonance imaging, are normal in concussion, and therefore diagnosis and management are guided by reported symptoms. Some athletes will under-report symptoms to accelerate their return-to-play and others will over-report symptoms out of fear of further injury or misinterpretation of underlying conditions, such as migraine headache. Therefore, an objective measure is needed to assist in several facets of concussion management. Limited data in animal and human testing indicates that intracranial pressure increases slightly and cerebrovascular reactivity (the ability of the cerebral arteries to auto-regulate in response to changes in carbon dioxide) decreases slightly following mild traumatic brain injury. We hypothesize that a combination of ultrasonographic measurements (optic nerve sheath diameter and transcranial Doppler assessment of cerebrovascular reactivity) into a single index will allow for an accurate and non-invasive measurement of intracranial pressure and cerebrovascular reactivity, and this index will be clinically relevant and useful for guiding concussion diagnosis and management. Ultrasound is an ideal modality for the evaluation of concussion because it is portable (allowing for evaluation in many settings, such as on the playing field or in a combat zone), radiation-free (making repeat scans safe), and relatively inexpensive (resulting in nearly universal availability). This paper reviews the literature supporting our hypothesis that an ultrasonographic index can assist in the diagnosis and management of concussion, and it also presents limited data regarding the

  11. Can a Combination of Ultrasonographic Parameters Accurately Evaluate Concussion and Guide Return-to-Play Decisions?

    PubMed Central

    Cartwright, Michael S.; Dupuis, Janae E.; Bargoil, Jessica M.; Foster, Dana C.

    2015-01-01

    Mild traumatic brain injury, often referred to as concussion, is a common, potentially debilitating, and costly condition. One of the main challenges in diagnosing and managing concussion is that there is not currently an objective test to determine the presence of a concussion and to guide return-to-play decisions for athletes. Traditional neuroimaging tests, such as brain magnetic resonance imaging, are normal in concussion, and therefore diagnosis and management are guided by reported symptoms. Some athletes will under-report symptoms to accelerate their return-to-play and others will over-report symptoms out of fear of further injury or misinterpretation of underlying conditions, such as migraine headache. Therefore, an objective measure is needed to assist in several facets of concussion management. Limited data in animal and human testing indicates that intracranial pressure increases slightly and cerebrovascular reactivity (the ability of the cerebral arteries to auto-regulate in response to changes in carbon dioxide) decreases slightly following mild traumatic brain injury. We hypothesize that a combination of ultrasonographic measurements (optic nerve sheath diameter and transcranial Doppler assessment of cerebrovascular reactivity) into a single index will allow for an accurate and non-invasive measurement of intracranial pressure and cerebrovascular reactivity, and this index will be clinically relevant and useful for guiding concussion diagnosis and management. Ultrasound is an ideal modality for the evaluation of concussion because it is portable (allowing for evaluation in many settings, such as on the playing field or in a combat zone), radiation-free (making repeat scans safe), and relatively inexpensive (resulting in nearly universal availability). This paper reviews the literature supporting our hypothesis that an ultrasonographic index can assist in the diagnosis and management of concussion, and it also presents limited data regarding the

  12. Point source solutions and coupling parameters in cratering mechanics

    NASA Technical Reports Server (NTRS)

    Holsapple, K. A.; Schmidt, R. M.

    1987-01-01

    The use of a point source of an impactor energy and momentum to replace the effects of the impactor is examined. The general framework and notation of the impact cratering problems are described; it is determined that the cratering phenomena are governed by Froude, Cauchy, and Reynolds numbers. The coupling parameter concept is defined mathematically as the measure that governs limit point source solutions. Examples of cases where coupling parameters are used are presented. The relationships of the coupling parameter concept with steady flow and the Z-model of cratering of Maxwell (1973, 1977) are studied. Crater size, ejecta distributions, growth histories, time of formation, melt volume, and shock decay for various scale factors for impact cratering mechanics are calculated, and the applicability of the coupling parameter to the study of cratering mechanics is revealed.

  13. Accurate structure and dynamics of the metal-site of paramagnetic metalloproteins from NMR parameters using natural bond orbitals.

    PubMed

    Hansen, D Flemming; Westler, William M; Kunze, Micha B A; Markley, John L; Weinhold, Frank; Led, Jens J

    2012-03-14

    A natural bond orbital (NBO) analysis of unpaired electron spin density in metalloproteins is presented, which allows a fast and robust calculation of paramagnetic NMR parameters. Approximately 90% of the unpaired electron spin density occupies metal-ligand NBOs, allowing the majority of the density to be modeled by only a few NBOs that reflect the chemical bonding environment. We show that the paramagnetic relaxation rate of protons can be calculated accurately using only the metal-ligand NBOs and that these rates are in good agreement with corresponding rates measured experimentally. This holds, in particular, for protons of ligand residues where the point-dipole approximation breaks down. To describe the paramagnetic relaxation of heavy nuclei, also the electron spin density in the local orbitals must be taken into account. Geometric distance restraints for (15)N can be derived from the paramagnetic relaxation enhancement and the Fermi contact shift when local NBOs are included in the analysis. Thus, the NBO approach allows us to include experimental paramagnetic NMR parameters of (15)N nuclei as restraints in a structure optimization protocol. We performed a molecular dynamics simulation and structure determination of oxidized rubredoxin using the experimentally obtained paramagnetic NMR parameters of (15)N. The corresponding structures obtained are in good agreement with the crystal structure of rubredoxin. Thus, the NBO approach allows an accurate description of the geometric structure and the dynamics of metalloproteins, when NMR parameters are available of nuclei in the immediate vicinity of the metal-site.

  14. Accurate Structure and Dynamics of the Metal-Site of Paramagnetic Metalloproteins from NMR Parameters Using Natural Bond Orbitals

    PubMed Central

    2012-01-01

    A natural bond orbital (NBO) analysis of unpaired electron spin density in metalloproteins is presented, which allows a fast and robust calculation of paramagnetic NMR parameters. Approximately 90% of the unpaired electron spin density occupies metal–ligand NBOs, allowing the majority of the density to be modeled by only a few NBOs that reflect the chemical bonding environment. We show that the paramagnetic relaxation rate of protons can be calculated accurately using only the metal–ligand NBOs and that these rates are in good agreement with corresponding rates measured experimentally. This holds, in particular, for protons of ligand residues where the point-dipole approximation breaks down. To describe the paramagnetic relaxation of heavy nuclei, also the electron spin density in the local orbitals must be taken into account. Geometric distance restraints for 15N can be derived from the paramagnetic relaxation enhancement and the Fermi contact shift when local NBOs are included in the analysis. Thus, the NBO approach allows us to include experimental paramagnetic NMR parameters of 15N nuclei as restraints in a structure optimization protocol. We performed a molecular dynamics simulation and structure determination of oxidized rubredoxin using the experimentally obtained paramagnetic NMR parameters of 15N. The corresponding structures obtained are in good agreement with the crystal structure of rubredoxin. Thus, the NBO approach allows an accurate description of the geometric structure and the dynamics of metalloproteins, when NMR parameters are available of nuclei in the immediate vicinity of the metal-site. PMID:22329704

  15. GUIDANCE2: accurate detection of unreliable alignment regions accounting for the uncertainty of multiple parameters

    PubMed Central

    Sela, Itamar; Ashkenazy, Haim; Katoh, Kazutaka; Pupko, Tal

    2015-01-01

    Inference of multiple sequence alignments (MSAs) is a critical part of phylogenetic and comparative genomics studies. However, from the same set of sequences different MSAs are often inferred, depending on the methodologies used and the assumed parameters. Much effort has recently been devoted to improving the ability to identify unreliable alignment regions. Detecting such unreliable regions was previously shown to be important for downstream analyses relying on MSAs, such as the detection of positive selection. Here we developed GUIDANCE2, a new integrative methodology that accounts for: (i) uncertainty in the process of indel formation, (ii) uncertainty in the assumed guide tree and (iii) co-optimal solutions in the pairwise alignments, used as building blocks in progressive alignment algorithms. We compared GUIDANCE2 with seven methodologies to detect unreliable MSA regions using extensive simulations and empirical benchmarks. We show that GUIDANCE2 outperforms all previously developed methodologies. Furthermore, GUIDANCE2 also provides a set of alternative MSAs which can be useful for downstream analyses. The novel algorithm is implemented as a web-server, available at: http://guidance.tau.ac.il. PMID:25883146

  16. Line Shape Parameters for CO_2 Transitions: Accurate Predictions from Complex Robert-Bonamy Calculations

    NASA Astrophysics Data System (ADS)

    Lamouroux, Julien; Gamache, Robert R.

    2013-06-01

    A model for the prediction of the vibrational dependence of CO_2 half-widths and line shifts for several broadeners, based on a modification of the model proposed by Gamache and Hartmann, is presented. This model allows the half-widths and line shifts for a ro-vibrational transition to be expressed in terms of the number of vibrational quanta exchanged in the transition raised to a power p and a reference ro-vibrational transition. Complex Robert-Bonamy calculations were made for 24 bands for lower rotational quantum numbers J'' from 0 to 160 for N_2-, O_2-, air-, and self-collisions with CO_2. In the model a Quantum Coordinate is defined by (c_1 Δν_1 + c_2 Δν_2 + c_3 Δν_3)^p where a linear least-squares fit to the data by the model expression is made. The model allows the determination of the slope and intercept as a function of rotational transition, broadening gas, and temperature. From these fit data, the half-width, line shift, and the temperature dependence of the half-width can be estimated for any ro-vibrational transition, allowing spectroscopic CO_2 databases to have complete information for the line shape parameters. R. R. Gamache, J.-M. Hartmann, J. Quant. Spectrosc. Radiat. Transfer. {{83}} (2004), 119. R. R. Gamache, J. Lamouroux, J. Quant. Spectrosc. Radiat. Transfer. {{117}} (2013), 93.

  17. GUIDANCE2: accurate detection of unreliable alignment regions accounting for the uncertainty of multiple parameters.

    PubMed

    Sela, Itamar; Ashkenazy, Haim; Katoh, Kazutaka; Pupko, Tal

    2015-07-01

    Inference of multiple sequence alignments (MSAs) is a critical part of phylogenetic and comparative genomics studies. However, from the same set of sequences different MSAs are often inferred, depending on the methodologies used and the assumed parameters. Much effort has recently been devoted to improving the ability to identify unreliable alignment regions. Detecting such unreliable regions was previously shown to be important for downstream analyses relying on MSAs, such as the detection of positive selection. Here we developed GUIDANCE2, a new integrative methodology that accounts for: (i) uncertainty in the process of indel formation, (ii) uncertainty in the assumed guide tree and (iii) co-optimal solutions in the pairwise alignments, used as building blocks in progressive alignment algorithms. We compared GUIDANCE2 with seven methodologies to detect unreliable MSA regions using extensive simulations and empirical benchmarks. We show that GUIDANCE2 outperforms all previously developed methodologies. Furthermore, GUIDANCE2 also provides a set of alternative MSAs which can be useful for downstream analyses. The novel algorithm is implemented as a web-server, available at: http://guidance.tau.ac.il.

  18. Accurate Analytical and Statistical Approaches to Reduce O-C Discrepancies in the Precessional Parameters

    NASA Astrophysics Data System (ADS)

    Martínez, M. J.; Marco, F. J.; López, J. A.

    2009-02-01

    The Hipparcos catalog provides a reference frame at optical wavelengths for the new International Celestial Reference System (ICRS). This new reference system was adopted following the resolution agreed at the 23rd IAU General Assembly held in Kyoto in 1997. Differences in the Hipparcos system of proper motions and the previous materialization of the reference frame, the FK5, are expected to be caused only by the combined effects of the motion of the equinox of the FK5 and the precession of the equator and the ecliptic. Several authors have pointed out an inconsistency between the differences in proper motion of the Hipparcos-FK5 and the correction of the precessional values derived from VLBI and lunar laser ranging (LLR) observations. Most of them have claimed that these discrepancies are due to slightly biased proper motions in the FK5 catalog. The different mathematical models that have been employed to explain these errors have not fully accounted for the discrepancies in the correction of the precessional parameters. Our goal here is to offer an explanation for this fact. We propose the use of independent parametric and nonparametric models. The introduction of a nonparametric model, combined with the inner product in the square integrable functions over the unitary sphere, would give us values which do not depend on the possible interdependencies existing in the data set. The evidence shows that zonal studies are needed. This would lead us to introduce a local nonparametric model. All these models will provide independent corrections to the precessional values, which could then be compared in order to study the reliability in each case. Finally, we obtain values for the precession corrections that are very consistent with those that are currently adopted.

  19. Design parameters and source terms: Volume 1, Design parameters: Revision 0

    SciTech Connect

    Not Available

    1987-10-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report by Stearns Catalytic Corporation (SCC), entitled ''Design Parameters and Source Terms for a Two-Phase Repository in Salt,'' 1985, to the level of the Site Characterization Plan - Conceptual Design Report. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible Salt Repository sites.

  20. Measurement of parameters in Indus-2 synchrotron radiation source.

    PubMed

    Ghodke, A D; Husain, Riyasat; Kumar, Pradeep; Yadav, Surendra; Puntambekar, T A

    2012-10-01

    The paper presents the measurement of optics parameters in Indus-2 synchrotron radiation source, which include betatron tune, beta function, dispersion function, natural chromaticity, corrected chromaticity, central RF frequency, momentum compaction factor, and linear betatron coupling. Two methods were used for beta function measurement; a conventional quadrupole scan method and a method using the fitting of the orbit response matrix. A robust Levenberg-Marquardt algorithm was used for nonlinear least square fitting of the orbit response matrix. In this paper, detailed methods for the parameter measurements are described. The measured results are discussed and compared with the theoretical values obtained using accelerator simulation code Accelerator Toolbox in MATLAB.

  1. A Weibull statistics-based lignocellulose saccharification model and a built-in parameter accurately predict lignocellulose hydrolysis performance.

    PubMed

    Wang, Mingyu; Han, Lijuan; Liu, Shasha; Zhao, Xuebing; Yang, Jinghua; Loh, Soh Kheang; Sun, Xiaomin; Zhang, Chenxi; Fang, Xu

    2015-09-01

    Renewable energy from lignocellulosic biomass has been deemed an alternative to depleting fossil fuels. In order to improve this technology, we aim to develop robust mathematical models for the enzymatic lignocellulose degradation process. By analyzing 96 groups of previously published and newly obtained lignocellulose saccharification results and fitting them to Weibull distribution, we discovered Weibull statistics can accurately predict lignocellulose saccharification data, regardless of the type of substrates, enzymes and saccharification conditions. A mathematical model for enzymatic lignocellulose degradation was subsequently constructed based on Weibull statistics. Further analysis of the mathematical structure of the model and experimental saccharification data showed the significance of the two parameters in this model. In particular, the λ value, defined the characteristic time, represents the overall performance of the saccharification system. This suggestion was further supported by statistical analysis of experimental saccharification data and analysis of the glucose production levels when λ and n values change. In conclusion, the constructed Weibull statistics-based model can accurately predict lignocellulose hydrolysis behavior and we can use the λ parameter to assess the overall performance of enzymatic lignocellulose degradation. Advantages and potential applications of the model and the λ value in saccharification performance assessment were discussed.

  2. A Weibull statistics-based lignocellulose saccharification model and a built-in parameter accurately predict lignocellulose hydrolysis performance.

    PubMed

    Wang, Mingyu; Han, Lijuan; Liu, Shasha; Zhao, Xuebing; Yang, Jinghua; Loh, Soh Kheang; Sun, Xiaomin; Zhang, Chenxi; Fang, Xu

    2015-09-01

    Renewable energy from lignocellulosic biomass has been deemed an alternative to depleting fossil fuels. In order to improve this technology, we aim to develop robust mathematical models for the enzymatic lignocellulose degradation process. By analyzing 96 groups of previously published and newly obtained lignocellulose saccharification results and fitting them to Weibull distribution, we discovered Weibull statistics can accurately predict lignocellulose saccharification data, regardless of the type of substrates, enzymes and saccharification conditions. A mathematical model for enzymatic lignocellulose degradation was subsequently constructed based on Weibull statistics. Further analysis of the mathematical structure of the model and experimental saccharification data showed the significance of the two parameters in this model. In particular, the λ value, defined the characteristic time, represents the overall performance of the saccharification system. This suggestion was further supported by statistical analysis of experimental saccharification data and analysis of the glucose production levels when λ and n values change. In conclusion, the constructed Weibull statistics-based model can accurately predict lignocellulose hydrolysis behavior and we can use the λ parameter to assess the overall performance of enzymatic lignocellulose degradation. Advantages and potential applications of the model and the λ value in saccharification performance assessment were discussed. PMID:26121186

  3. Optical identifications of radio sources with accurate positions using the United Kingdom Schmidt Telescope (UKST) IIIa-J plates

    NASA Technical Reports Server (NTRS)

    Savage, A.

    1986-01-01

    Several programs are making use of UKST Sky Survey plates to identify southern radio sources. The fine-grain modern plates and accurate radio positions give a much improved identification rate. It seems that it will very soon be possible to determine whether or not there is a quasar redshift cut-off at z of about 4. There is an urgent need for more accurate fundamental reference star positions in the South.

  4. Automated source term and wind parameter estimation for atmospheric transport and dispersion applications

    NASA Astrophysics Data System (ADS)

    Bieringer, Paul E.; Rodriguez, Luna M.; Vandenberghe, Francois; Hurst, Jonathan G.; Bieberbach, George; Sykes, Ian; Hannan, John R.; Zaragoza, Jake; Fry, Richard N.

    2015-12-01

    Accurate simulations of the atmospheric transport and dispersion (AT&D) of hazardous airborne materials rely heavily on the source term parameters necessary to characterize the initial release and meteorological conditions that drive the downwind dispersion. In many cases the source parameters are not known and consequently based on rudimentary assumptions. This is particularly true of accidental releases and the intentional releases associated with terrorist incidents. When available, meteorological observations are often not representative of the conditions at the location of the release and the use of these non-representative meteorological conditions can result in significant errors in the hazard assessments downwind of the sensors, even when the other source parameters are accurately characterized. Here, we describe a computationally efficient methodology to characterize both the release source parameters and the low-level winds (eg. winds near the surface) required to produce a refined downwind hazard. This methodology, known as the Variational Iterative Refinement Source Term Estimation (STE) Algorithm (VIRSA), consists of a combination of modeling systems. These systems include a back-trajectory based source inversion method, a forward Gaussian puff dispersion model, a variational refinement algorithm that uses both a simple forward AT&D model that is a surrogate for the more complex Gaussian puff model and a formal adjoint of this surrogate model. The back-trajectory based method is used to calculate a "first guess" source estimate based on the available observations of the airborne contaminant plume and atmospheric conditions. The variational refinement algorithm is then used to iteratively refine the first guess STE parameters and meteorological variables. The algorithm has been evaluated across a wide range of scenarios of varying complexity. It has been shown to improve the source parameters for location by several hundred percent (normalized by the

  5. Optimization of tissue physical parameters for accurate temperature estimation from finite-element simulation of radiofrequency ablation

    NASA Astrophysics Data System (ADS)

    Subramanian, Swetha; Mast, T. Douglas

    2015-09-01

    Computational finite element models are commonly used for the simulation of radiofrequency ablation (RFA) treatments. However, the accuracy of these simulations is limited by the lack of precise knowledge of tissue parameters. In this technical note, an inverse solver based on the unscented Kalman filter (UKF) is proposed to optimize values for specific heat, thermal conductivity, and electrical conductivity resulting in accurately simulated temperature elevations. A total of 15 RFA treatments were performed on ex vivo bovine liver tissue. For each RFA treatment, 15 finite-element simulations were performed using a set of deterministically chosen tissue parameters to estimate the mean and variance of the resulting tissue ablation. The UKF was implemented as an inverse solver to recover the specific heat, thermal conductivity, and electrical conductivity corresponding to the measured area of the ablated tissue region, as determined from gross tissue histology. These tissue parameters were then employed in the finite element model to simulate the position- and time-dependent tissue temperature. Results show good agreement between simulated and measured temperature.

  6. Optimization of tissue physical parameters for accurate temperature estimation from finite-element simulation of radiofrequency ablation.

    PubMed

    Subramanian, Swetha; Mast, T Douglas

    2015-10-01

    Computational finite element models are commonly used for the simulation of radiofrequency ablation (RFA) treatments. However, the accuracy of these simulations is limited by the lack of precise knowledge of tissue parameters. In this technical note, an inverse solver based on the unscented Kalman filter (UKF) is proposed to optimize values for specific heat, thermal conductivity, and electrical conductivity resulting in accurately simulated temperature elevations. A total of 15 RFA treatments were performed on ex vivo bovine liver tissue. For each RFA treatment, 15 finite-element simulations were performed using a set of deterministically chosen tissue parameters to estimate the mean and variance of the resulting tissue ablation. The UKF was implemented as an inverse solver to recover the specific heat, thermal conductivity, and electrical conductivity corresponding to the measured area of the ablated tissue region, as determined from gross tissue histology. These tissue parameters were then employed in the finite element model to simulate the position- and time-dependent tissue temperature. Results show good agreement between simulated and measured temperature. PMID:26352462

  7. Towards an accurate specific reaction parameter density functional for water dissociation on Ni(111): RPBE versus PW91.

    PubMed

    Jiang, Bin; Guo, Hua

    2016-08-01

    In search for an accurate description of the dissociative chemisorption of water on the Ni(111) surface, we report a new nine-dimensional potential energy surface (PES) based on a large number of density functional theory points using the RPBE functional. Seven-dimensional quantum dynamical calculations have been carried out on the RPBE PES, followed by site averaging and lattice effect corrections, yielding sticking probabilities that are compared with both the previous theoretical results based on a PW91 PES and experiment. It is shown that the RPBE functional increases the reaction barrier, but has otherwise a minor impact on the PES topography. Better agreement with experimental results is obtained with the new PES, but the agreement is still not quantitative. Possible sources of the remaining discrepancies are discussed.

  8. Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

    SciTech Connect

    Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

    2015-04-08

    A numerical model, based on the fluid plasma theory, has been used for description of the spatial distribution of the plasma parameters (electron density and temperature, plasma potential as well as densities of the three types of positive hydrogen ions) in the IPP prototype RF negative hydrogen ion source. The model covers the driver and the expansion plasma region of the source with their actual size and accounts for the presence of the magnetic filter field with its actual value and location as well as for the bias potential applied to the plasma grid. The obtained results show that without a magnetic filter the two 2D geometries considered, respectively, with an axial symmetry and a planar one, represent accurately the complex 3D structure of the source. The 2D model with a planar symmetry (where the E×B and diamagnetic drifts could be involved in the description) has been used for analysis of the influence, via the charged-particle and electron-energy fluxes, of the magnetic filter and of the bias potential on the spatial structure of the plasma parameters in the source. Benchmarking of results from the code to experimental data shows that the model reproduces the general trend in the axial behavior of the plasma parameters in the source.

  9. Spatial distribution of the plasma parameters in the RF negative ion source prototype for fusion

    NASA Astrophysics Data System (ADS)

    Lishev, S.; Schiesko, L.; Wünderlich, D.; Fantz, U.

    2015-04-01

    A numerical model, based on the fluid plasma theory, has been used for description of the spatial distribution of the plasma parameters (electron density and temperature, plasma potential as well as densities of the three types of positive hydrogen ions) in the IPP prototype RF negative hydrogen ion source. The model covers the driver and the expansion plasma region of the source with their actual size and accounts for the presence of the magnetic filter field with its actual value and location as well as for the bias potential applied to the plasma grid. The obtained results show that without a magnetic filter the two 2D geometries considered, respectively, with an axial symmetry and a planar one, represent accurately the complex 3D structure of the source. The 2D model with a planar symmetry (where the E×B and diamagnetic drifts could be involved in the description) has been used for analysis of the influence, via the charged-particle and electron-energy fluxes, of the magnetic filter and of the bias potential on the spatial structure of the plasma parameters in the source. Benchmarking of results from the code to experimental data shows that the model reproduces the general trend in the axial behavior of the plasma parameters in the source.

  10. SENSITIVITY OF STRUCTURAL RESPONSE TO GROUND MOTION SOURCE AND SITE PARAMETERS.

    USGS Publications Warehouse

    Safak, Erdal; Brebbia, C.A.; Cakmak, A.S.; Abdel Ghaffar, A.M.

    1985-01-01

    Designing structures to withstand earthquakes requires an accurate estimation of the expected ground motion. While engineers use the peak ground acceleration (PGA) to model the strong ground motion, seismologists use physical characteristics of the source and the rupture mechanism, such as fault length, stress drop, shear wave velocity, seismic moment, distance, and attenuation. This study presents a method for calculating response spectra from seismological models using random vibration theory. It then investigates the effect of various source and site parameters on peak response. Calculations are based on a nonstationary stochastic ground motion model, which can incorporate all the parameters both in frequency and time domains. The estimation of the peak response accounts for the effects of the non-stationarity, bandwidth and peak correlations of the response.

  11. Design parameters and source terms: Volume 2, Source terms: Revision 0

    SciTech Connect

    Not Available

    1987-10-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report by Stearns Catalytic Corporation (SCC), entitled ''Design Parameters and Source Terms for a Two-Phase Repository Salt,'' 1985, to the level of the Site Characterization Plan - Conceptual Design Report. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible Salt Repository sites. 2 tabs.

  12. Public directory data sources do not accurately characterize the food environment in two predominantly rural states.

    PubMed

    Longacre, Meghan R; Primack, Brian A; Owens, Peter M; Gibson, Lucinda; Beauregard, Sandy; Mackenzie, Todd A; Dalton, Madeline A

    2011-04-01

    Communities are being encouraged to develop locally based interventions to address environmental risk factors for obesity. Online public directories represent an affordable and easily accessible mechanism for mapping community food environments, but may have limited utility in rural areas. The primary aim of this study was to evaluate the efficacy of public directories vs rigorous onsite field verification to characterize the community food environment in 32 geographically dispersed towns from two rural states covering 1,237.6 square miles. Eight types of food outlets were assessed in 2007, including food markets and eating establishments, first using two publically available online directories followed by onsite field verification by trained coders. χ(2) and univariate binomial regression were used to determine whether the proportion of outlets accurately listed varied by food outlet type or town population. Among 1,340 identified outlets, only 36.9% were accurately listed through public directories; 29.6% were not listed but were located during field observation. Accuracy varied by outlet type, being most accurate for big box stores and least accurate for farm/produce stands. Overall, public directories accurately identified fewer than half of the food outlets. Accuracy was significantly lower for rural and small towns compared to mid-size and urban towns (P<0.001). In this geographic sample, public directories seriously misrepresented the actual distribution of food outlets, particularly for rural and small towns. To inform local obesity-prevention efforts, communities should strongly consider using field verification to characterize the food environment in low-population areas.

  13. Source parameters derived from seismic spectrum in the Jalisco block

    NASA Astrophysics Data System (ADS)

    Gutierrez, Q. J.; Escudero, C. R.; Nunez-Cornu, F. J.

    2012-12-01

    The direct measure of the earthquake fault dimension represent a complicated task nevertheless a better approach is using the seismic waves spectrum. With this method we can estimate the dimensions of the fault, the stress drop and the seismic moment. The study area comprises the complex tectonic configuration of Jalisco block and the subduction of the Rivera plate beneath the North American plate; this causes that occur in Jalisco some of the most harmful earthquakes and other related natural disasters. Accordingly it is important to monitor and perform studies that helps to understand the physics of earthquake rupture mechanism in the area. The main proposue of this study is estimate earthquake seismic source parameters. The data was recorded by the MARS network (Mapping the Riviera Subduction Zone) and the RESAJ network. MARS had 51 stations and settled in the Jalisco block; that is delimited by the mesoamerican trench at the west, the Colima grabben to the south, and the Tepic-Zacoalco to the north; for a period of time, of January 1, 2006 until December 31, 2007 Of this network was taken 104 events, the magnitude range of these was between 3 to 6.5 MB. RESJAL has 10 stations and is within the state of Jalisco, began to record since October 2011 and continues to record. We firs remove the trend, the mean and the instrument response, then manually chosen the S wave, then the multitaper method was used to obtain the spectrum of this wave and so estimate the corner frequency and the spectra level. We substitude the obtained in the equations of the Brune model to calculate the source parameters. Doing this we obtained the following results; the source radius was between .1 to 2 km, the stress drop was between .1 to 2 MPa.

  14. Source Parameters for Repeating Earthquakes along the Middle America Trench

    NASA Astrophysics Data System (ADS)

    Bilek, S. L.; Phillips, W. S.; Walter, J. I.; Peng, Z.; Schwartz, S. Y.; Brudzinski, M. R.; Yao, D.

    2015-12-01

    Repeating earthquakes, with their similar locations and similar waveforms, are often thought to represent slip along the same patch of fault. Analysis of these earthquake clusters can provide useful information about the nature of the fault and earthquake interaction. Here we focus on sequences of repeating earthquakes along both the Nicoya Peninsula, Costa Rica and along the Oaxaca segment of Mexico, as both megathrust faults have been well instrumented in recent years with local seismic networks able to record the small magnitude earthquakes. These regions have also experienced large megathrust earthquakes as well as non-volcanic tremor and slow slip, suggesting a complex fault system that allows a wide spectrum of slip. We can use source characteristics of the repeating earthquakes to probe this fault complexity. Along the Nicoya Peninsula, there are over 370 repeating earthquakes (M 0.5-3.3) in the 3 months following the 2012 Mw 7.6 megathrust earthquake grouped into 55 distinct clusters. Along Oaxaca, the earthquake clusters or swarms (M 1.5-5.5) span a wider spatial and temporal range. For our source parameter calculations, we form narrow-frequency band envelopes for pairs of earthquakes within the earthquake clusters to compute spectral ratios for each pair. We determine seismic moment, corner frequency, and earthquake stress drop for each earthquake from these spectral ratios. We compare the source parameters for events within the clusters to examine temporal variations and compare between clusters to explore spatial variations that could be linked to other slip heterogeneity. Preliminary results for the Nicoya region suggest nearly identical stress drop for repeating events within clusters located near the 2012 mainshock, and more variability in stress drops for earthquakes in clusters located updip and to the northwest of the mainshock.

  15. Sensitivity of numerical dispersion modeling to explosive source parameters

    SciTech Connect

    Baskett, R.L. ); Cederwall, R.T. )

    1991-02-13

    The calculation of downwind concentrations from non-traditional sources, such as explosions, provides unique challenges to dispersion models. The US Department of Energy has assigned the Atmospheric Release Advisory Capability (ARAC) at the Lawrence Livermore National Laboratory (LLNL) the task of estimating the impact of accidental radiological releases to the atmosphere anywhere in the world. Our experience includes responses to over 25 incidents in the past 16 years, and about 150 exercises a year. Examples of responses to explosive accidents include the 1980 Titan 2 missile fuel explosion near Damascus, Arkansas and the hydrogen gas explosion in the 1986 Chernobyl nuclear power plant accident. Based on judgment and experience, we frequently estimate the source geometry and the amount of toxic material aerosolized as well as its particle size distribution. To expedite our real-time response, we developed some automated algorithms and default assumptions about several potential sources. It is useful to know how well these algorithms perform against real-world measurements and how sensitive our dispersion model is to the potential range of input values. In this paper we present the algorithms we use to simulate explosive events, compare these methods with limited field data measurements, and analyze their sensitivity to input parameters. 14 refs., 7 figs., 2 tabs.

  16. Determination of plasma parameters in solar zebra radio sources

    NASA Astrophysics Data System (ADS)

    Karlický, M.; Yasnov, L. V.

    2015-09-01

    Aims: We present a new method for determining the magnetic field strength and plasma density in the solar zebra radio sources. Methods: Using the double plasma resonance (DPR) model of the zebra emission, we analytically derived the equations for computing the gyroharmonic number s of selected zebra lines and then solved these equations numerically. Results: The method was successfully tested on artificially generated zebras and then applied to observed ones. The magnetic field strength and plasma density in the radio sources were determined. Simultaneously, we evaluated the parameter Lnb = 2Lb/ (2Ln - Lb), where Ln and Lb are the characteristic scale-heights of the plasma density and magnetic field strength in the zebra source, respectively. Computations show that the maximum frequency of the low-polarized zebras is about 8 GHz, in very good agreement with observations. For the high-polarized zebras, this limit is about four times lower. Microwave zebras are preferentially generated in the regions with steep gradients of the plasma density, such as in the transition region. In models with smaller density gradients, such as those with a barometric density profile, the microwave zebras cannot be produced owing to the strong bremsstrahlung and cyclotron absorptions. We also show that our DPR model is able to explain the zebras with frequency-equidistant zebra lines.

  17. Effect of photon energy spectrum on dosimetric parameters of brachytherapy sources

    PubMed Central

    Ghorbani, Mahdi; Davenport, David

    2016-01-01

    Abstract Aim The aim of this study is to quantify the influence of the photon energy spectrum of brachytherapy sources on task group No. 43 (TG-43) dosimetric parameters. Background Different photon spectra are used for a specific radionuclide in Monte Carlo simulations of brachytherapy sources. Materials and methods MCNPX code was used to simulate 125I, 103Pd, 169Yb, and 192Ir brachytherapy sources. Air kerma strength per activity, dose rate constant, radial dose function, and two dimensional (2D) anisotropy functions were calculated and isodose curves were plotted for three different photon energy spectra. The references for photon energy spectra were: published papers, Lawrence Berkeley National Laboratory (LBNL), and National Nuclear Data Center (NNDC). The data calculated by these photon energy spectra were compared. Results Dose rate constant values showed a maximum difference of 24.07% for 103Pd source with different photon energy spectra. Radial dose function values based on different spectra were relatively the same. 2D anisotropy function values showed minor differences in most of distances and angles. There was not any detectable difference between the isodose contours. Conclusions Dosimetric parameters obtained with different photon spectra were relatively the same, however it is suggested that more accurate and updated photon energy spectra be used in Monte Carlo simulations. This would allow for calculation of reliable dosimetric data for source modeling and calculation in brachytherapy treatment planning systems. PMID:27247558

  18. Design parameters and source terms: Volume 1, Design parameters: Revision 0

    SciTech Connect

    Not Available

    1987-09-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report to the level of the Site Characterization Plan - Conceptual Design Report, SCP-CDR. The previous unpublished SCC Study identified the data needs for the Environmental Assessment effort for seven possible salt repository sites.

  19. The Exponent of High-frequency Source Spectral Falloff and Contribution to Source Parameter Estimates

    NASA Astrophysics Data System (ADS)

    Kiuchi, R.; Mori, J. J.

    2015-12-01

    As a way to understand the characteristics of the earthquake source, studies of source parameters (such as radiated energy and stress drop) and their scaling are important. In order to estimate source parameters reliably, often we must use appropriate source spectrum models and the omega-square model is most frequently used. In this model, the spectrum is flat in lower frequencies and the falloff is proportional to the angular frequency squared. However, Some studies (e.g. Allmann and Shearer, 2009; Yagi et al., 2012) reported that the exponent of the high frequency falloff is other than -2. Therefore, in this study we estimate the source parameters using a spectral model for which the falloff exponent is not fixed. We analyze the mainshock and larger aftershocks of the 2008 Iwate-Miyagi Nairiku earthquake. Firstly, we calculate the P wave and SH wave spectra using empirical Green functions (EGF) to remove the path effect (such as attenuation) and site effect. For the EGF event, we select a smaller earthquake that is highly-correlated with the target event. In order to obtain the stable results, we calculate the spectral ratios using a multitaper spectrum analysis (Prieto et al., 2009). Then we take a geometric mean from multiple stations. Finally, using the obtained spectra ratios, we perform a grid search to determine the high frequency falloffs, as well as corner frequency of both of events. Our results indicate the high frequency falloff exponent is often less than 2.0. We do not observe any regional, focal mechanism, or depth dependencies for the falloff exponent. In addition, our estimated corner frequencies and falloff exponents are consistent between the P wave and SH wave analysis. In our presentation, we show differences in estimated source parameters using a fixed omega-square model and a model allowing variable high-frequency falloff.

  20. Reconstruction of the activity of point sources for the accurate characterization of nuclear waste drums by segmented gamma scanning.

    PubMed

    Krings, Thomas; Mauerhofer, Eric

    2011-06-01

    This work improves the reliability and accuracy in the reconstruction of the total isotope activity content in heterogeneous nuclear waste drums containing point sources. The method is based on χ(2)-fits of the angular dependent count rate distribution measured during a drum rotation in segmented gamma scanning. A new description of the analytical calculation of the angular count rate distribution is introduced based on a more precise model of the collimated detector. The new description is validated and compared to the old description using MCNP5 simulations of angular dependent count rate distributions of Co-60 and Cs-137 point sources. It is shown that the new model describes the angular dependent count rate distribution significantly more accurate compared to the old model. Hence, the reconstruction of the activity is more accurate and the errors are considerably reduced that lead to more reliable results. Furthermore, the results are compared to the conventional reconstruction method assuming a homogeneous matrix and activity distribution.

  1. Harmonic Generation from Solid Targets - Optmization of Source Parameters

    NASA Astrophysics Data System (ADS)

    Zepf, Matthew; Watts, I. F.; Dangor, A. E.; Norreys, P. A.; Chambers, D. M.; Machacek, A.; Wark, J. S.; Tsakiris, G. D.

    1998-11-01

    High harmonics from solid targets have received renewed interest over the last few years. Theoretical predictions using 1 1/2 D codes suggest that very high orders (>100 ) can be generated at conversion efficiencies in excess of 10-6 [1,2] at Iλ^2 > 10^19 W/cm^2. Experiments have since been performed with pulses varying from 100 fs to 2.5 ps in duration [3-6]. The steep density gradient necessary to generate the harmonics can be generated by either ponderomotive steepening or by using ultraclean pulses which preserve the initial solid vacuum boundary. The two regimes are compared in terms of their dependence on the laser parameters and the emitted harmonic radiation. Particular emphasis will be given to measurements of the holeboring velocity, the polarisation of the harmonics and the intensity scaling in the two regimes. This comparison enables us to find the ideal parameter range for the optimization of harmonic source. [1] R. Lichters et al., Physics of Plasmas 3, 3425, (1996). [2] P. Gibbon, IEEE J. of Q. Elec. 33, 1915 (1997). [3] S. Kohlweyer, et al., Optics Comm. 177, 431 (1995). [4] P. Norreys et al., Phys. Rev. Lett., 76, 1832 (1995). [5] D. von der Linde et al., Phys. Rev. A, 52, R25 (1995) [6] M. Zepf, et al., submitted for publication in Phys. Rev. Lett.

  2. A two-parameter kinetic model based on a time-dependent activity coefficient accurately describes enzymatic cellulose digestion

    PubMed Central

    Kostylev, Maxim; Wilson, David

    2014-01-01

    Lignocellulosic biomass is a potential source of renewable, low-carbon-footprint liquid fuels. Biomass recalcitrance and enzyme cost are key challenges associated with the large-scale production of cellulosic fuel. Kinetic modeling of enzymatic cellulose digestion has been complicated by the heterogeneous nature of the substrate and by the fact that a true steady state cannot be attained. We present a two-parameter kinetic model based on the Michaelis-Menten scheme (Michaelis L and Menten ML. (1913) Biochem Z 49:333–369), but with a time-dependent activity coefficient analogous to fractal-like kinetics formulated by Kopelman (Kopelman R. (1988) Science 241:1620–1626). We provide a mathematical derivation and experimental support to show that one of the parameters is a total activity coefficient and the other is an intrinsic constant that reflects the ability of the cellulases to overcome substrate recalcitrance. The model is applicable to individual cellulases and their mixtures at low-to-medium enzyme loads. Using biomass degrading enzymes from a cellulolytic bacterium Thermobifida fusca we show that the model can be used for mechanistic studies of enzymatic cellulose digestion. We also demonstrate that it applies to the crude supernatant of the widely studied cellulolytic fungus Trichoderma reesei and can thus be used to compare cellulases from different organisms. The two parameters may serve a similar role to Vmax, KM, and kcat in classical kinetics. A similar approach may be applicable to other enzymes with heterogeneous substrates and where a steady state is not achievable. PMID:23837567

  3. Variant of more accurate determination of the locations of shortwave radio emission sources

    NASA Astrophysics Data System (ADS)

    Ivanov, V. F.; Myslivtsev, T. O.; Troitskii, B. V.

    2013-04-01

    The paper discusses how the trajectory calculation method can be used to solve the problem of locality determination of shortwave (SW) emission sources. The dependence of the electron concentration on the coordinates is specified using the SPIM model; it is corrected using the ionospheric solar activity index, which is specified with the help of maps of total electron content. We suggested a variant of how a regional map of the total electron content can be plotted according to measurements of signals from GLONASS/GPS navigation systems. It is shown that the trajectory calculation method, coupled with an adjustable ionospheric model, allows for a more exact locality determination of SW radio emission sources.

  4. Initial tsunami source estimation by inversion with an intelligent selection of model parameters and time delays

    NASA Astrophysics Data System (ADS)

    Mulia, Iyan E.; Asano, Toshiyuki

    2016-01-01

    We propose a method for accurately estimating the initial tsunami source. Our technique is independent of the earthquake parameters, because we only use recorded tsunami waveforms and an auxiliary basis function, instead of a fault model. We first use the measured waveforms to roughly identify the source area using backward propagated travel times, and then infer the initial sea surface deformation through inversion analysis. A computational intelligence approach based on a genetic algorithm combined with a pattern search was used to select appropriate least squares model parameters and time delays. The proposed method significantly reduced the number of parameters and suppressed the negative effect of regularization schemes that decreased the plausibility of the model. Furthermore, the stochastic approach for deriving the time delays is a more flexible strategy for simulating actual phenomena that occur in nature. The selected parameters and time delays increased the accuracy, and the model's ability to reveal the underlying physics associated with the tsunami-generating processes. In this paper, we applied the method to the 2011 Tohoku-Oki tsunami event and examined its effectiveness by comparing the results to those using the conventional method.

  5. Design parameters and source terms: Volume 2, Source terms: Revision 0

    SciTech Connect

    Not Available

    1987-09-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report to the level of the Site Characterization Plan---Conceptual Design Report SCP-CDR. The previous study identifies the data needs for the Environmental Assessment effort for seven possible salt repository sites. Volume 2 contains tables of source terms.

  6. A Parameter Identification Method for Helicopter Noise Source Identification and Physics-Based Semi-Empirical Modeling

    NASA Technical Reports Server (NTRS)

    Greenwood, Eric, II; Schmitz, Fredric H.

    2010-01-01

    A new physics-based parameter identification method for rotor harmonic noise sources is developed using an acoustic inverse simulation technique. This new method allows for the identification of individual rotor harmonic noise sources and allows them to be characterized in terms of their individual non-dimensional governing parameters. This new method is applied to both wind tunnel measurements and ground noise measurements of two-bladed rotors. The method is shown to match the parametric trends of main rotor Blade-Vortex Interaction (BVI) noise, allowing accurate estimates of BVI noise to be made for operating conditions based on a small number of measurements taken at different operating conditions.

  7. Volcano deformation source parameters estimated from InSAR: Sensitivities to uncertainties in seismic tomography

    NASA Astrophysics Data System (ADS)

    Masterlark, Timothy; Donovan, Theodore; Feigl, Kurt L.; Haney, Matthew; Thurber, Clifford H.; Tung, Sui

    2016-04-01

    The eruption cycle of a volcano is controlled in part by the upward migration of magma. The characteristics of the magma flux produce a deformation signature at the Earth's surface. Inverse analyses use geodetic data to estimate strategic controlling parameters that describe the position and pressurization of a magma chamber at depth. The specific distribution of material properties controls how observed surface deformation translates to source parameter estimates. Seismic tomography models describe the spatial distributions of material properties that are necessary for accurate models of volcano deformation. This study investigates how uncertainties in seismic tomography models propagate into variations in the estimates of volcano deformation source parameters inverted from geodetic data. We conduct finite element model-based nonlinear inverse analyses of interferometric synthetic aperture radar (InSAR) data for Okmok volcano, Alaska, as an example. We then analyze the estimated parameters and their uncertainties to characterize the magma chamber. Analyses are performed separately for models simulating a pressurized chamber embedded in a homogeneous domain as well as for a domain having a heterogeneous distribution of material properties according to seismic tomography. The estimated depth of the source is sensitive to the distribution of material properties. The estimated depths for the homogeneous and heterogeneous domains are 2666 ± 42 and 3527 ± 56 m below mean sea level, respectively (99% confidence). A Monte Carlo analysis indicates that uncertainties of the seismic tomography cannot account for this discrepancy at the 99% confidence level. Accounting for the spatial distribution of elastic properties according to seismic tomography significantly improves the fit of the deformation model predictions and significantly influences estimates for parameters that describe the location of a pressurized magma chamber.

  8. Rapid, high-order accurate calculation of flows due to free source or vortex distributions

    NASA Technical Reports Server (NTRS)

    Halsey, D.

    1981-01-01

    Fast Fourier transform (FFT) techniques are applied to the problem of finding the flow due to source or vortex distributions in the field outside an airfoil or other two-dimensional body. Either the complex potential or the complex velocity may be obtained to a high order of accuracy, with computational effort similar to that required by second-order fast Poisson solvers. These techniques are applicable to general flow problems with compressibility and rotation. An example is given of their use for inviscid compressible flow.

  9. Earthquake Source Parameters Inferred from T-Wave Observations

    NASA Astrophysics Data System (ADS)

    Perrot, J.; Dziak, R.; Lau, T. A.; Matsumoto, H.; Goslin, J.

    2004-12-01

    The seismicity of the North Atlantic Ocean has been recorded by two networks of autonomous hydrophones moored within the SOFAR channel on the flanks of the Mid-Atlantic Ridge (MAR). In February 1999, a consortium of U.S. investigators (NSF and NOAA) deployed a 6-element hydrophone array for long-term monitoring of MAR seismicity between 15o-35oN south of the Azores. In May 2002, an international collaboration of French, Portuguese, and U.S. researchers deployed a 6-element hydrophone array north of the Azores Plateau from 40o-50oN. The northern network (referred to as SIRENA) was recovered in September 2003. The low attenuation properties of the SOFAR channel for earthquake T-wave propagation results in a detection threshold reduction from a magnitude completeness level (Mc) of ˜ 4.7 for MAR events recorded by the land-based seismic networks to Mc=3.0 using hydrophone arrays. Detailed focal depth and mechanism information, however, remain elusive due to the complexities of seismo-acoustic propagation paths. Nonetheless, recent analyses (Dziak, 2001; Park and Odom, 2001) indicate fault parameter information is contained within the T-wave signal packet. We investigate this relationship further by comparing an earthquake's T-wave duration and acoustic energy to seismic magnitude (NEIC) and radiation pattern (for events M>5) from the Harvard moment-tensor catalog. First results show earthquake energy is well represented by the acoustic energy of the T-waves, however T-wave codas are significantly influenced by acoustic propagation effects and do not allow a direct determination of the seismic magnitude of the earthquakes. Second, there appears to be a correlation between T-wave acoustic energy, azimuth from earthquake source to the hydrophone, and the radiation pattern of the earthquake's SH waves. These preliminary results indicate there is a relationship between the T-wave observations and earthquake source parameters, allowing for additional insights into T

  10. Investigating the value of passive microwave observations for monitoring volcanic eruption source parameters

    NASA Astrophysics Data System (ADS)

    Montopoli, Mario; Cimini, Domenico; Marzano, Frank

    2016-04-01

    Volcanic eruptions inject both gas and solid particles into the Atmosphere. Solid particles are made by mineral fragments of different sizes (from few microns to meters), generally referred as tephra. Tephra from volcanic eruptions has enormous impacts on social and economical activities through the effects on the environment, climate, public health, and air traffic. The size, density and shape of a particle determine its fall velocity and thus residence time in the Atmosphere. Larger particles tend to fall quickly in the proximity of the volcano, while smaller particles may remain suspended for several days and thus may be transported by winds for thousands of km. Thus, the impact of such hazards involves local as well as large scales effects. Local effects involve mostly the large sized particles, while large scale effects are caused by the transport of the finest ejected tephra (ash) through the atmosphere. Forecasts of ash paths in the atmosphere are routinely run after eruptions using dispersion models. These models make use of meteorological and volcanic source parameters. The former are usually available as output of numerical weather prediction models or large scale reanalysis. Source parameters characterize the volcanic eruption near the vent; these are mainly the ash mass concentration along the vertical column and the top altitude of the volcanic plume, which is strictly related to the flux of the mass ejected at the emission source. These parameters should be known accurately and continuously; otherwise, strong hypothesis are usually needed, leading to large uncertainty in the dispersion forecasts. However, direct observations during an eruption are typically dangerous and impractical. Thus, satellite remote sensing is often exploited to monitor volcanic emissions, using visible (VIS) and infrared (IR) channels available on both Low Earth Orbit (LEO) and Geostationary Earth Orbit (GEO) satellites. VIS and IR satellite imagery are very useful to monitor

  11. Brachytherapy dosimetry parameters calculated for a {sup 131}Cs source

    SciTech Connect

    Rivard, Mark J.

    2007-02-15

    A comprehensive analysis of the IsoRay Medical model CS-1 Rev2 {sup 131}Cs brachytherapy source was performed. Dose distributions were simulated using Monte Carlo methods (MCNP5) in liquid water, Solid{sup TM}, and Virtual Water{sup TM} spherical phantoms. From these results, the in-water brachytherapy dosimetry parameters have been determined, and were compared with those of Murphy et al. [Med. Phys. 31, 1529-1538 (2004)] using measurements and simulations. Our results suggest that calculations obtained using erroneous cross-section libraries should be discarded as recommended by the 2004 AAPM TG-43U1 report. Our {sub MC}{lambda} value of 1.046{+-}0.019 cGy h{sup -1} U{sup -1} is within 1.3% of that measured by Chen et al. [Med. Phys. 32, 3279-3285 (2005)] using TLDs and the calculated results of Wittman and Fisher [Med. Phys. 34, 49-54 (2007)] using MCNP5. Using the discretized energy approach of Rivard [Appl. Radiat. Isot. 55, 775-782 (2001)] to ascertain the impact of individual {sup 131}Cs photons on radial dose function and anisotropy functions, there was virtual equivalence of results for 29.461{<=}E{sub {gamma}}{<=}34.419 keV and for a mono-energetic 30.384 keV photon source. Comparisons of radial dose function and 2D anisotropy function data are also included, and an analysis of material composition and cross-section libraries was performed.

  12. Variation of seismic source parameters around the southern Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Rhee, H. M.; Sheen, D. H.; Kang, T. S.

    2014-12-01

    In this study, we determined seismic source parameters from 557 events with ML≥1.6 that occurred in the southern part of the Korean Peninsula from 2001 to 2013. A total of 7,267 S-wave trains on three-component seismograms recorded at broadband seismic stations were used for measuring the corner frequency, Brune stress drop and moment magnitude by using the iterative method of Jo and Baag (2001) based on the methods of Snoke (1987) and Andrews (1986). The SNR were calculated for each seismogram to exclude the possible contamination of the records by noise and/or instrumental malfunctioning. For the stable correction of attenuation, we tested several Q factors from the previous studies on those for the Korean Peninsula and found Kim (2007) gave the best result. In this study, as shown by Shi et al. (1998), the stress drop tended to decrease with decreasing seismic moment from the magnitude 3.5. Although there was large scatter in stress drop, however, the stress drops seemed to be constant for the larger events and the average stress drop was estimated to around 45.5 bar. It is interesting that there was a variation in stress drops depending on earthquake location: stress drops of the earthquakes occurred in the East Sea (Japan Sea) and the southwestern part of North Korea were relatively lower than those for the events occurred at other region in the southern Korean Peninsula.

  13. Accurate multi-source forest species mapping using the multiple spectral-spatial classification approach

    NASA Astrophysics Data System (ADS)

    Stavrakoudis, Dimitris; Gitas, Ioannis; Karydas, Christos; Kolokoussis, Polychronis; Karathanassi, Vassilia

    2015-10-01

    This paper proposes an efficient methodology for combining multiple remotely sensed imagery, in order to increase the classification accuracy in complex forest species mapping tasks. The proposed scheme follows a decision fusion approach, whereby each image is first classified separately by means of a pixel-wise Fuzzy-Output Support Vector Machine (FO-SVM) classifier. Subsequently, the multiple results are fused according to the so-called multiple spectral- spatial classifier using the minimum spanning forest (MSSC-MSF) approach, which constitutes an effective post-regularization procedure for enhancing the result of a single pixel-based classification. For this purpose, the original MSSC-MSF has been extended in order to handle multiple classifications. In particular, the fuzzy outputs of the pixel-based classifiers are stacked and used to grow the MSF, whereas the markers are also determined considering both classifications. The proposed methodology has been tested on a challenging forest species mapping task in northern Greece, considering a multispectral (GeoEye) and a hyper-spectral (CASI) image. The pixel-wise classifications resulted in overall accuracies (OA) of 68.71% for the GeoEye and 77.95% for the CASI images, respectively. Both of them are characterized by high levels of speckle noise. Applying the proposed multi-source MSSC-MSF fusion, the OA climbs to 90.86%, which is attributed both to the ability of MSSC-MSF to tackle the salt-and-pepper effect, as well as the fact that the fusion approach exploits the relative advantages of both information sources.

  14. Localizer: fast, accurate, open-source, and modular software package for superresolution microscopy.

    PubMed

    Dedecker, Peter; Duwé, Sam; Neely, Robert K; Zhang, Jin

    2012-12-01

    We present Localizer, a freely available and open source software package that implements the computational data processing inherent to several types of superresolution fluorescence imaging, such as localization (PALM/STORM/GSDIM) and fluctuation imaging (SOFI/pcSOFI). Localizer delivers high accuracy and performance and comes with a fully featured and easy-to-use graphical user interface but is also designed to be integrated in higher-level analysis environments. Due to its modular design, Localizer can be readily extended with new algorithms as they become available, while maintaining the same interface and performance. We provide front-ends for running Localizer from Igor Pro, Matlab, or as a stand-alone program. We show that Localizer performs favorably when compared with two existing superresolution packages, and to our knowledge is the only freely available implementation of SOFI/pcSOFI microscopy. By dramatically improving the analysis performance and ensuring the easy addition of current and future enhancements, Localizer strongly improves the usability of superresolution imaging in a variety of biomedical studies. PMID:23208219

  15. Estimation of Eruption Source Parameters from Plume Growth Rate

    NASA Astrophysics Data System (ADS)

    Pouget, Solene; Bursik, Marcus; Webley, Peter; Dehn, Jon; Pavalonis, Michael; Singh, Tarunraj; Singla, Puneet; Patra, Abani; Pitman, Bruce; Stefanescu, Ramona; Madankan, Reza; Morton, Donald; Jones, Matthew

    2013-04-01

    The eruption of Eyjafjallajokull, Iceland in April and May, 2010, brought to light the hazards of airborne volcanic ash and the importance of Volcanic Ash Transport and Dispersion models (VATD) to estimate the concentration of ash with time. These models require Eruption Source Parameters (ESP) as input, which typically include information about the plume height, the mass eruption rate, the duration of the eruption and the particle size distribution. However much of the time these ESP are unknown or poorly known a priori. We show that the mass eruption rate can be estimated from the downwind plume or umbrella cloud growth rate. A simple version of the continuity equation can be applied to the growth of either an umbrella cloud or the downwind plume. The continuity equation coupled with the momentum equation using only inertial and gravitational terms provides another model. Numerical modeling or scaling relationships can be used, as necessary, to provide values for unknown or unavailable parameters. Use of these models applied to data on plume geometry provided by satellite imagery allows for direct estimation of plume volumetric and mass growth with time. To test our methodology, we compared our results with five well-studied and well-characterized historical eruptions: Mount St. Helens, 1980; Pinatubo, 1991, Redoubt, 1990; Hekla, 2000 and Eyjafjallajokull, 2010. These tests show that the methodologies yield results comparable to or better than currently accepted methodologies of ESP estimation. We then applied the methodology to umbrella clouds produced by the eruptions of Okmok, 12 July 2008, and Sarychev Peak, 12 June 2009, and to the downwind plume produced by the eruptions of Hekla, 2000; Kliuchevsko'i, 1 October 1994; Kasatochi 7-8 August 2008 and Bezymianny, 1 September 2012. The new methods allow a fast, remote assessment of the mass eruption rate, even for remote volcanoes. They thus provide an additional path to estimation of the ESP and the forecasting

  16. Extracting source parameters from beam monitors on a chopper spectrometer

    SciTech Connect

    Abernathy, Douglas L; Niedziela, Jennifer L; Stone, Matthew B

    2015-01-01

    The intensity distributions of beam monitors in direct-geometry time-of-flight neutron spectrometers provide important information about the instrument resolution. For short-pulse spallation neutron sources in particular, the asymmetry of the source pulse may be extracted and compared to Monte Carlo source simulations. An explicit formula using a Gaussian-convolved Ikeda-Carpenter distribution is given and compared to data from the ARCS instrument at the Spallation Neutron Source.

  17. Design parameters and source terms: Volume 3, Source terms: Revision 0

    SciTech Connect

    Not Available

    1987-09-01

    The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report to the level of the Site Characterization Plan /endash/ Conceptual Design Report, SCP-CDR. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible salt repository sites.

  18. Tsunami hazard warning and risk prediction based on inaccurate earthquake source parameters

    NASA Astrophysics Data System (ADS)

    Goda, Katsuichiro; Abilova, Kamilla

    2016-02-01

    This study investigates the issues related to underestimation of the earthquake source parameters in the context of tsunami early warning and tsunami risk assessment. The magnitude of a very large event may be underestimated significantly during the early stage of the disaster, resulting in the issuance of incorrect tsunami warnings. Tsunamigenic events in the Tohoku region of Japan, where the 2011 tsunami occurred, are focused on as a case study to illustrate the significance of the problems. The effects of biases in the estimated earthquake magnitude on tsunami loss are investigated using a rigorous probabilistic tsunami loss calculation tool that can be applied to a range of earthquake magnitudes by accounting for uncertainties of earthquake source parameters (e.g., geometry, mean slip, and spatial slip distribution). The quantitative tsunami loss results provide valuable insights regarding the importance of deriving accurate seismic information as well as the potential biases of the anticipated tsunami consequences. Finally, the usefulness of rigorous tsunami risk assessment is discussed in defining critical hazard scenarios based on the potential consequences due to tsunami disasters.

  19. Tsunami hazard warning and risk prediction based on inaccurate earthquake source parameters

    NASA Astrophysics Data System (ADS)

    Goda, K.; Abilova, K.

    2015-12-01

    This study investigates the issues related to underestimation of the earthquake source parameters in the context of tsunami early warning and tsunami risk assessment. The magnitude of a very large event may be underestimated significantly during the early stage of the disaster, resulting in the issuance of incorrect tsunami warnings. Tsunamigenic events in the Tohoku region of Japan, where the 2011 tsunami occurred, are focused on as a case study to illustrate the significance of the problems. The effects of biases in the estimated earthquake magnitude on tsunami loss are investigated using a rigorous probabilistic tsunami loss calculation tool that can be applied to a range of earthquake magnitudes by accounting for uncertainties of earthquake source parameters (e.g. geometry, mean slip, and spatial slip distribution). The quantitative tsunami loss results provide with valuable insights regarding the importance of deriving accurate seismic information as well as the potential biases of the anticipated tsunami consequences. Finally, usefulness of rigorous tsunami risk assessment is discussed in defining critical hazard scenarios based on the potential consequences due to tsunami disasters.

  20. EVALUATING SOIL EROSION PARAMETER ESTIMATES FROM DIFFERENT DATA SOURCES

    EPA Science Inventory

    Topographic factors and soil loss estimates that were derived from thee data sources (STATSGO, 30-m DEM, and 3-arc second DEM) were compared. Slope magnitudes derived from the three data sources were consistently different. Slopes from the DEMs tended to provide a flattened sur...

  1. Numerical parameter constraints for accurate PIC-DSMC simulation of breakdown from arc initiation to stable arcs

    NASA Astrophysics Data System (ADS)

    Moore, Christopher; Hopkins, Matthew; Moore, Stan; Boerner, Jeremiah; Cartwright, Keith

    2015-09-01

    Simulation of breakdown is important for understanding and designing a variety of applications such as mitigating undesirable discharge events. Such simulations need to be accurate through early time arc initiation to late time stable arc behavior. Here we examine constraints on the timestep and mesh size required for arc simulations using the particle-in-cell (PIC) method with direct simulation Monte Carlo (DMSC) collisions. Accurate simulation of electron avalanche across a fixed voltage drop and constant neutral density (reduced field of 1000 Td) was found to require a timestep ~ 1/100 of the mean time between collisions and a mesh size ~ 1/25 the mean free path. These constraints are much smaller than the typical PIC-DSMC requirements for timestep and mesh size. Both constraints are related to the fact that charged particles are accelerated by the external field. Thus gradients in the electron energy distribution function can exist at scales smaller than the mean free path and these must be resolved by the mesh size for accurate collision rates. Additionally, the timestep must be small enough that the particle energy change due to the fields be small in order to capture gradients in the cross sections versus energy. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. DOE's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  2. Scaling Relationship Among Source Parameters of Microearthquake," From Near Source Observation in a Deep Mine

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Y.; Yoshimura, M.; Furumoto, M.

    2004-12-01

    Scaling relationships among various source parameters are important clues to understand the source process. In particular the relationship between the corner frequency, fC, and the seismic moment, MO, has been investigated by many researchers. Aki(1967) investigated fC and MO using the spectra of seismic waves and reported that these parameters obeyed a relationship of MO ∝ fC-3. For small earthquakes, the breakdown of this relationship was often reported. On the other hand, no breakdown of the relationship for microearthquakes has been reported from high quality observation at deep boreholes and in a deep gold mine. We report here these scaling relationships using waveform of microearthquakes observed at the distance range of 15m to 1km. We installed nine tri-axial borehole accelerometers within 200 m along a haulage tunnel 2650m deep in Mponeng mine in South Africa from February to December in 1996. More than 25 thousand seismic events were recorded with a sampling frequency of 15 kHz and a dynamic range of 120 dB. The recording system has flat response up to 2 KHz. Among those events, we select 378 events with high S/N. We locate hypocenters assuming infinite medium with the P-wave velocity 5.5 km/s and the S-wave velocity 3.2 km/s. We calculate the green function using the discrete wavenumber integral method into account the effect of anelasticity by Takeo (1985) and determine the seismic moment and the mechanism using moment tensor inversion. We apply the omega square model by Brune (1970) to determine the corner frequency and the stress drop. Minimizing L2 norm between the observed spectra of P and S waves and the synthetic ones give the optimum source parameters. The earthquakes analyzed in this study show the constant stress drop of 0.4 ˜8MPa in the ranges of 40

  3. A non-empirical, parameter-free, hybrid functional for accurate calculations of optoelectronic properties of finite systems

    NASA Astrophysics Data System (ADS)

    Brawand, Nicholas; Vörös, Márton; Govoni, Marco; Galli, Giulia

    The accurate prediction of optoelectronic properties of molecules and solids is a persisting challenge for current density functional theory (DFT) based methods. We propose a hybrid functional where the mixing fraction of exact and local exchange is determined by a non-empirical, system dependent function. This functional yields ionization potentials, fundamental and optical gaps of many, diverse systems in excellent agreement with experiments, including organic and inorganic molecules and nanocrystals. We further demonstrate that the newly defined hybrid functional gives the correct alignment between the energy level of the exemplary TTF-TCNQ donor-acceptor system. DOE-BES: DE-FG02-06ER46262.

  4. Low-frequency source parameters of twelve large earthquakes

    NASA Astrophysics Data System (ADS)

    Harabaglia, Paolo

    1993-06-01

    A global survey of the low-frequency (1-21 mHz) source characteristics of large events are studied. We are particularly interested in events unusually enriched in low-frequency and in events with a short-term precursor. We model the source time function of 12 large earthquakes using teleseismic data at low frequency. For each event we retrieve the source amplitude spectrum in the frequency range between 1 and 21 mHz with the Silver and Jordan method and the phase-shift spectrum in the frequency range between 1 and 11 mHz with the Riedesel and Jordan method. We then model the source time function by fitting the two spectra. Two of these events, the 1980 Irpinia, Italy, and the 1983 Akita-Oki, Japan, are shallow-depth complex events that took place on multiple faults. In both cases the source time function has a length of about 100 seconds. By comparison Westaway and Jackson find 45 seconds for the Irpinia event and Houston and Kanamori about 50 seconds for the Akita-Oki earthquake. The three deep events and four of the seven intermediate-depth events are fast rupturing earthquakes. A single pulse is sufficient to model the source spectra in the frequency range of our interest. Two other intermediate-depth events have slower rupturing processes, characterized by a continuous energy release lasting for about 40 seconds. The last event is the intermediate-depth 1983 Peru-Ecuador earthquake. It was first recognized as a precursive event by Jordan. We model it with a smooth rupturing process starting about 2 minutes before the high frequency origin time superimposed to an impulsive source.

  5. Accurate determination of interface trap state parameters by admittance spectroscopy in the presence of a Schottky barrier contact: Application to ZnO-based solar cells

    NASA Astrophysics Data System (ADS)

    Marin, Andrew T.; Musselman, Kevin P.; MacManus-Driscoll, Judith L.

    2013-04-01

    This work shows that when a Schottky barrier is present in a photovoltaic device, such as in a device with an ITO/ZnO contact, equivalent circuit analysis must be performed with admittance spectroscopy to accurately determine the pn junction interface recombination parameters (i.e., capture cross section and density of trap states). Without equivalent circuit analysis, a Schottky barrier can produce an error of ˜4-orders of magnitude in the capture cross section and ˜50% error in the measured density of trap states. Using a solution processed ZnO/Cu2O photovoltaic test system, we apply our analysis to clearly separate the contributions of interface states at the pn junction from the Schottky barrier at the ITO/ZnO contact so that the interface state recombination parameters can be accurately characterized. This work is widely applicable to the multitude of photovoltaic devices, which use ZnO adjacent to ITO.

  6. Blind Source Parameters for Performance Evaluation of Despeckling Filters.

    PubMed

    Biradar, Nagashettappa; Dewal, M L; Rohit, ManojKumar; Gowre, Sanjaykumar; Gundge, Yogesh

    2016-01-01

    The speckle noise is inherent to transthoracic echocardiographic images. A standard noise-free reference echocardiographic image does not exist. The evaluation of filters based on the traditional parameters such as peak signal-to-noise ratio, mean square error, and structural similarity index may not reflect the true filter performance on echocardiographic images. Therefore, the performance of despeckling can be evaluated using blind assessment metrics like the speckle suppression index, speckle suppression and mean preservation index (SMPI), and beta metric. The need for noise-free reference image is overcome using these three parameters. This paper presents a comprehensive analysis and evaluation of eleven types of despeckling filters for echocardiographic images in terms of blind and traditional performance parameters along with clinical validation. The noise is effectively suppressed using the logarithmic neighborhood shrinkage (NeighShrink) embedded with Stein's unbiased risk estimation (SURE). The SMPI is three times more effective compared to the wavelet based generalized likelihood estimation approach. The quantitative evaluation and clinical validation reveal that the filters such as the nonlocal mean, posterior sampling based Bayesian estimation, hybrid median, and probabilistic patch based filters are acceptable whereas median, anisotropic diffusion, fuzzy, and Ripplet nonlinear approximation filters have limited applications for echocardiographic images. PMID:27298618

  7. Blind Source Parameters for Performance Evaluation of Despeckling Filters

    PubMed Central

    Biradar, Nagashettappa; Dewal, M. L.; Rohit, ManojKumar; Gowre, Sanjaykumar; Gundge, Yogesh

    2016-01-01

    The speckle noise is inherent to transthoracic echocardiographic images. A standard noise-free reference echocardiographic image does not exist. The evaluation of filters based on the traditional parameters such as peak signal-to-noise ratio, mean square error, and structural similarity index may not reflect the true filter performance on echocardiographic images. Therefore, the performance of despeckling can be evaluated using blind assessment metrics like the speckle suppression index, speckle suppression and mean preservation index (SMPI), and beta metric. The need for noise-free reference image is overcome using these three parameters. This paper presents a comprehensive analysis and evaluation of eleven types of despeckling filters for echocardiographic images in terms of blind and traditional performance parameters along with clinical validation. The noise is effectively suppressed using the logarithmic neighborhood shrinkage (NeighShrink) embedded with Stein's unbiased risk estimation (SURE). The SMPI is three times more effective compared to the wavelet based generalized likelihood estimation approach. The quantitative evaluation and clinical validation reveal that the filters such as the nonlocal mean, posterior sampling based Bayesian estimation, hybrid median, and probabilistic patch based filters are acceptable whereas median, anisotropic diffusion, fuzzy, and Ripplet nonlinear approximation filters have limited applications for echocardiographic images. PMID:27298618

  8. The influence of Monte Carlo source parameters on detector design and dose perturbation in small field dosimetry

    NASA Astrophysics Data System (ADS)

    Charles, P. H.; Crowe, S. B.; Kairn, T.; Knight, R.; Hill, B.; Kenny, J.; Langton, C. M.; Trapp, J. V.

    2014-03-01

    To obtain accurate Monte Carlo simulations of small radiation fields, it is important model the initial source parameters (electron energy and spot size) accurately. However recent studies have shown that small field dosimetry correction factors are insensitive to these parameters. The aim of this work is to extend this concept to test if these parameters affect dose perturbations in general, which is important for detector design and calculating perturbation correction factors. The EGSnrc C++ user code cavity was used for all simulations. Varying amounts of air between 0 and 2 mm were deliberately introduced upstream to a diode and the dose perturbation caused by the air was quantified. These simulations were then repeated using a range of initial electron energies (5.5 to 7.0 MeV) and electron spot sizes (0.7 to 2.2 FWHM). The resultant dose perturbations were large. For example 2 mm of air caused a dose reduction of up to 31% when simulated with a 6 mm field size. However these values did not vary by more than 2 % when simulated across the full range of source parameters tested. If a detector is modified by the introduction of air, one can be confident that the response of the detector will be the same across all similar linear accelerators and the Monte Carlo modelling of each machine is not required.

  9. On the selection of loads in the multiload method for measuring the acoustic source parameters of duct systems.

    PubMed

    Jang, Seung-Ho; Ih, Jeong-Guon

    2002-03-01

    The in-duct source can be characterized by two acoustical parameters such as the source strength and the source impedance, which permit the prediction of radiated sound pressure or insertion loss of the whole duct system. One-port acoustic characteristics of an in-duct source can be measured by the multiload method using an overdetermined set of open pipes or side-branch pipes with different lengths as applied loads. The input data, viz. load pressure and load impedance, are usually contaminated by measurement error in the actual measurements, which result in errors in the calculated source parameters. In this paper, the effects of the errors in the input data on the results have been studied numerically, varying the number of loads and their impedances in order to determine what combination of the loads will yield the best result. It is noted that, frequently, only a set of open pipes is used when applying the multiload method to the internal combustion engine sources. A set of pipe lengths, which cause the calculated results to be least sensitive to the input data error, can be found when using open pipe loads. The present work is intended to produce guidelines for preparing an appropriate load set in order to obtain accurate source properties of fluid machines.

  10. SEMICONDUCTOR INTEGRATED CIRCUITS: Accurate metamodels of device parameters and their applications in performance modeling and optimization of analog integrated circuits

    NASA Astrophysics Data System (ADS)

    Tao, Liang; Xinzhang, Jia; Junfeng, Chen

    2009-11-01

    Techniques for constructing metamodels of device parameters at BSIM3v3 level accuracy are presented to improve knowledge-based circuit sizing optimization. Based on the analysis of the prediction error of analytical performance expressions, operating point driven (OPD) metamodels of MOSFETs are introduced to capture the circuit's characteristics precisely. In the algorithm of metamodel construction, radial basis functions are adopted to interpolate the scattered multivariate data obtained from a well tailored data sampling scheme designed for MOSFETs. The OPD metamodels can be used to automatically bias the circuit at a specific DC operating point. Analytical-based performance expressions composed by the OPD metamodels show obvious improvement for most small-signal performances compared with simulation-based models. Both operating-point variables and transistor dimensions can be optimized in our nesting-loop optimization formulation to maximize design flexibility. The method is successfully applied to a low-voltage low-power amplifier.

  11. Source mechanisms and source parameters of March 10 and September 13, 2007, United Arab Emirates Earthquakes

    SciTech Connect

    Marzooqi, Y A; Abou Elenean, K M; Megahed, A S; El-Hussain, I; Rodgers, A; Khatibi, E A

    2008-02-29

    On March 10 and September 13, 2007 two felt earthquakes with moment magnitudes 3.66 and 3.94 occurred in the eastern part of United Arab Emirates (UAE). The two events were accompanied by few smaller events. Being well recorded by the digital UAE and Oman digital broadband stations, they provide us an excellent opportunity to study the tectonic process and present day stress field acting on this area. In this study, we determined the focal mechanisms of the two main shocks by two methods (polarities of P and regional waveform inversion). Our results indicate a normal faulting mechanism with slight strike slip component for the two studied events along a fault plane trending NNE-SSW in consistent a suggested fault along the extension of the faults bounded Bani Hamid area. The Seismicity distribution between two earthquake sequences reveals a noticeable gap that may be a site of a future event. The source parameters (seismic moment, moment magnitude, fault radius, stress drop and displacement across the fault) were also estimated based on the far field displacement spectra and interpreted in the context of the tectonic setting.

  12. Petermann I and II spot size: Accurate semi analytical description involving Nelder-Mead method of nonlinear unconstrained optimization and three parameter fundamental modal field

    NASA Astrophysics Data System (ADS)

    Roy Choudhury, Raja; Roy Choudhury, Arundhati; Kanti Ghose, Mrinal

    2013-01-01

    A semi-analytical model with three optimizing parameters and a novel non-Gaussian function as the fundamental modal field solution has been proposed to arrive at an accurate solution to predict various propagation parameters of graded-index fibers with less computational burden than numerical methods. In our semi analytical formulation the optimization of core parameter U which is usually uncertain, noisy or even discontinuous, is being calculated by Nelder-Mead method of nonlinear unconstrained minimizations as it is an efficient and compact direct search method and does not need any derivative information. Three optimizing parameters are included in the formulation of fundamental modal field of an optical fiber to make it more flexible and accurate than other available approximations. Employing variational technique, Petermann I and II spot sizes have been evaluated for triangular and trapezoidal-index fibers with the proposed fundamental modal field. It has been demonstrated that, the results of the proposed solution identically match with the numerical results over a wide range of normalized frequencies. This approximation can also be used in the study of doped and nonlinear fiber amplifier.

  13. Simultaneous parameter estimation and contaminant source characterization for coupled groundwater flow and contaminant transport modelling

    USGS Publications Warehouse

    Wagner, B.J.

    1992-01-01

    Parameter estimation and contaminant source characterization are key steps in the development of a coupled groundwater flow and contaminant transport simulation model. Here a methodologyfor simultaneous model parameter estimation and source characterization is presented. The parameter estimation/source characterization inverse model combines groundwater flow and contaminant transport simulation with non-linear maximum likelihood estimation to determine optimal estimates of the unknown model parameters and source characteristics based on measurements of hydraulic head and contaminant concentration. First-order uncertainty analysis provides a means for assessing the reliability of the maximum likelihood estimates and evaluating the accuracy and reliability of the flow and transport model predictions. A series of hypothetical examples is presented to demonstrate the ability of the inverse model to solve the combined parameter estimation/source characterization inverse problem. Hydraulic conductivities, effective porosity, longitudinal and transverse dispersivities, boundary flux, and contaminant flux at the source are estimated for a two-dimensional groundwater system. In addition, characterization of the history of contaminant disposal or location of the contaminant source is demonstrated. Finally, the problem of estimating the statistical parameters that describe the errors associated with the head and concentration data is addressed. A stage-wise estimation procedure is used to jointly estimate these statistical parameters along with the unknown model parameters and source characteristics. ?? 1992.

  14. Coupling 1D Navier Stokes equation with autoregulation lumped parameter networks for accurate cerebral blood flow modeling

    NASA Astrophysics Data System (ADS)

    Ryu, Jaiyoung; Hu, Xiao; Shadden, Shawn C.

    2014-11-01

    The cerebral circulation is unique in its ability to maintain blood flow to the brain under widely varying physiologic conditions. Incorporating this autoregulatory response is critical to cerebral blood flow modeling, as well as investigations into pathological conditions. We discuss a one-dimensional nonlinear model of blood flow in the cerebral arteries that includes coupling of autoregulatory lumped parameter networks. The model is tested to reproduce a common clinical test to assess autoregulatory function - the carotid artery compression test. The change in the flow velocity at the middle cerebral artery (MCA) during carotid compression and release demonstrated strong agreement with published measurements. The model is then used to investigate vasospasm of the MCA, a common clinical concern following subarachnoid hemorrhage. Vasospasm was modeled by prescribing vessel area reduction in the middle portion of the MCA. Our model showed similar increases in velocity for moderate vasospasms, however, for serious vasospasm (~ 90% area reduction), the blood flow velocity demonstrated decrease due to blood flow rerouting. This demonstrates a potentially important phenomenon, which otherwise would lead to false-negative decisions on clinical vasospasm if not properly anticipated.

  15. Source parameters and crustal Q for four earthquakes in South Carolina

    USGS Publications Warehouse

    Fletcher, Joe B.

    1995-01-01

    Two three-component seismometers (one surface and one borehole) were re-installed on the Savannah River Site (SRS), South Carolina in July 1992 to determine attenuation in the Coastal Plain sediment wedge and source parameters of local earthquakes. Four earthquakes M ~1.8 to 3.6 were recorded during the next 6 months. The largest event was located near Summerville within the meizoseismal area for the 1886 Charleston earthquake. Although source parameters have been determined from strong motion data and short-period regional networks for east coast earthquakes, these are some of the first source parameters determined from broad-band digital recorders. This paper determines source parameters such as moment, stress drop, and the attenuation parameter t* using a non-linear least-squares algorithm. -from Author

  16. White LED compared with other light sources: age-dependent photobiological effects and parameters for evaluation.

    PubMed

    Rebec, Katja Malovrh; Klanjšek-Gunde, Marta; Bizjak, Grega; Kobav, Matej B

    2015-01-01

    Ergonomic science at work and living places should appraise human factors concerning the photobiological effects of lighting. Thorough knowledge on this subject has been gained in the past; however, few attempts have been made to propose suitable evaluation parameters. The blue light hazard and its influence on melatonin secretion in age-dependent observers is considered in this paper and parameters for its evaluation are proposed. New parameters were applied to analyse the effects of white light-emitting diode (LED) light sources and to compare them with the currently applied light sources. The photobiological effects of light sources with the same illuminance but different spectral power distribution were determined for healthy 4-76-year-old observers. The suitability of new parameters is discussed. Correlated colour temperature, the only parameter currently used to assess photobiological effects, is evaluated and compared to new parameters. PMID:26647954

  17. Extension of the AMBER force field for nitroxide radicals and combined QM/MM/PCM approach to the accurate determination of EPR parameters of DMPOH in solution

    PubMed Central

    Hermosilla, Laura; Prampolini, Giacomo; Calle, Paloma; García de la Vega, José Manuel; Brancato, Giuseppe; Barone, Vincenzo

    2015-01-01

    A computational strategy that combines both time-dependent and time-independent approaches is exploited to accurately model molecular dynamics and solvent effects on the isotropic hyperfine coupling constants of the DMPO-H nitroxide. Our recent general force field for nitroxides derived from AMBER ff99SB is further extended to systems involving hydrogen atoms in β-positions with respect to NO. The resulting force-field has been employed in a series of classical molecular dynamics simulations, comparing the computed EPR parameters from selected molecular configurations to the corresponding experimental data in different solvents. The effect of vibrational averaging on the spectroscopic parameters is also taken into account, by second order vibrational perturbation theory involving semi-diagonal third energy derivatives together first and second property derivatives. PMID:26584116

  18. A robust and accurate center-frequency estimation (RACE) algorithm for improving motion estimation performance of SinMod on tagged cardiac MR images without known tagging parameters.

    PubMed

    Liu, Hong; Wang, Jie; Xu, Xiangyang; Song, Enmin; Wang, Qian; Jin, Renchao; Hung, Chih-Cheng; Fei, Baowei

    2014-11-01

    A robust and accurate center-frequency (CF) estimation (RACE) algorithm for improving the performance of the local sine-wave modeling (SinMod) method, which is a good motion estimation method for tagged cardiac magnetic resonance (MR) images, is proposed in this study. The RACE algorithm can automatically, effectively and efficiently produce a very appropriate CF estimate for the SinMod method, under the circumstance that the specified tagging parameters are unknown, on account of the following two key techniques: (1) the well-known mean-shift algorithm, which can provide accurate and rapid CF estimation; and (2) an original two-direction-combination strategy, which can further enhance the accuracy and robustness of CF estimation. Some other available CF estimation algorithms are brought out for comparison. Several validation approaches that can work on the real data without ground truths are specially designed. Experimental results on human body in vivo cardiac data demonstrate the significance of accurate CF estimation for SinMod, and validate the effectiveness of RACE in facilitating the motion estimation performance of SinMod.

  19. High-frequency observations and source parameters of microearthquakes recorded at hard-rock sites

    USGS Publications Warehouse

    Cranswick, Edward; Wetmiller, Robert; Boatwright, John

    1985-01-01

    We have estimated the source parameters of 53 microearthquakes recorded in July 1983 which were aftershocks of the Miramichi, New Brunswick, earthquake that occurred on 9 January 1982. These events were recorded by local three-component digital seismographs at 400 sps/component from 2-Hz velocity transducers sited directly on glacially scoured crystalline basement outcrop. Hypocentral distances are typically less than 5 km, and the hypocenters and the seven digital seismograph stations established all lie essentially within the boundaries of a granitic pluton that encompasses the faults that ruptured during the main shock and major aftershocks. The P-wave velocity is typically 5 km/sec at the surface and at least 6 km/sec at depths greater than about 1 km.The events have S-wave corner frequencies in the band 10 to 40 Hz, and the calculated Brune model seismic moments range from 1015 to 1018 dyne-cm. The corresponding stress drops are generally less than 1.0 bars, but there is considerable evidence that the seismic-source signals have been modified by propagation and/or site-effects. The data indicate: (a) there is a velocity discontinuity at 0.5 km depth; (b) the top layer has strong scattering/attenuating properties; (c) some source-receiver paths differentiate the propagated signal; (d) there is a hard-rock-site P-wave “fmax” between 50 and 100 Hz; and (e) some hard-rock sites are characterized by P-wave resonance frequencies in the range 50 to 100 Hz. Comparison of this dataset with the January 1982 New Brunswick digital seismograms which were recorded at sites underlain by several meters of low-velocity surface sediments suggests that some of the hard-rock-site phenomena listed above can be explained in terms of a layer-over-a-half-space model. For microearthquakes, this result implies that spectrally determined source dimension scales with site dimension (thickness of the layer). More generally, it emphasizes that it is very difficult to accurately observe

  20. Calculated and measured brachytherapy dosimetry parameters in water for the Xoft Axxent X-Ray Source: An electronic brachytherapy source

    SciTech Connect

    Rivard, Mark J.; Davis, Stephen D.; DeWerd, Larry A.; Rusch, Thomas W.; Axelrod, Steve

    2006-11-15

    A new x-ray source, the model S700 Axxent trade mark sign X-Ray Source (Source), has been developed by Xoft Inc. for electronic brachytherapy. Unlike brachytherapy sources containing radionuclides, this Source may be turned on and off at will and may be operated at variable currents and voltages to change the dose rate and penetration properties. The in-water dosimetry parameters for this electronic brachytherapy source have been determined from measurements and calculations at 40, 45, and 50 kV settings. Monte Carlo simulations of radiation transport utilized the MCNP5 code and the EPDL97-based mcplib04 cross-section library. Inter-tube consistency was assessed for 20 different Sources, measured with a PTW 34013 ionization chamber. As the Source is intended to be used for a maximum of ten treatment fractions, tube stability was also assessed. Photon spectra were measured using a high-purity germanium (HPGe) detector, and calculated using MCNP. Parameters used in the two-dimensional (2D) brachytherapy dosimetry formalism were determined. While the Source was characterized as a point due to the small anode size, <1 mm, use of the one-dimensional (1D) brachytherapy dosimetry formalism is not recommended due to polar anisotropy. Consequently, 1D brachytherapy dosimetry parameters were not sought. Calculated point-source model radial dose functions at g{sub P}(5) were 0.20, 0.24, and 0.29 for the 40, 45, and 50 kV voltage settings, respectively. For 1source model radial dose functions were typically within 4% of calculated results. Calculated values for F(r,{theta}) for all operating voltages were within 15% of unity along the distal end ({theta}=0 deg. ), and ranged from F(1 cm,160 deg. )=0.2 to F(15 cm,175 deg. )=0.4 towards the catheter proximal end. For all three operating voltages using the PTW chamber, measured dependence of output as a function of azimuthal angle, {psi}, was typically on average {+-}3% for 0 deg. {<=}{psi}{<=}360 deg

  1. Calibration of the Regional Crustal Waveguide and the Retrieval of Source Parameters Using Waveform Modeling

    NASA Astrophysics Data System (ADS)

    Saikia, C. K.; Woods, B. B.; Thio, H. K.

    - Regional crustal waveguide calibration is essential to the retrieval of source parameters and the location of smaller (M<4.8) seismic events. This path calibration of regional seismic phases is strongly dependent on the accuracy of hypocentral locations of calibration (or master) events. This information can be difficult to obtain, especially for smaller events. Generally, explosion or quarry blast generated travel-time data with known locations and origin times are useful for developing the path calibration parameters, but in many regions such data sets are scanty or do not exist. We present a method which is useful for regional path calibration independent of such data, i.e. with earthquakes, which is applicable for events down to Mw = 4 and which has successfully been applied in India, central Asia, western Mediterranean, North Africa, Tibet and the former Soviet Union. These studies suggest that reliably determining depth is essential to establishing accurate epicentral location and origin time for events. We find that the error in source depth does not necessarily trade-off only with the origin time for events with poor azimuthal coverage, but with the horizontal location as well, thus resulting in poor epicentral locations. For example, hypocenters for some events in central Asia were found to move from their fixed-depth locations by about 20km. Such errors in location and depth will propagate into path calibration parameters, particularly with respect to travel times. The modeling of teleseismic depth phases (pP, sP) yields accurate depths for earthquakes down to magnitude Mw = 4.7. This Mwthreshold can be lowered to four if regional seismograms are used in conjunction with a calibrated velocity structure model to determine depth, with the relative amplitude of the Pnl waves to the surface waves and the interaction of regional sPmP and pPmP phases being good indicators of event depths. We also found that for deep events a seismic phase which follows an S

  2. Combining visible-based-color parameters and geochemical tracers to improve sediment source discrimination and apportionment.

    PubMed

    Tiecher, Tales; Caner, Laurent; Minella, Jean Paolo Gomes; dos Santos, Danilo Rheinheimer

    2015-09-15

    Parameter selection in fingerprinting studies are often time-consuming and costly because successful fingerprint properties are generally highly site-specific. Recently, spectroscopy has been applied to trace sediment origin as a rapid, less expensive, non-destructive and straightforward alternative. We show in this study the first attempt to combine both geochemical tracers and color parameters derived from the visible (VIS) spectrum in a single estimate of sediment source contribution. Moreover, we compared the discrimination power and source apportionment using VIS-based-color parameters and using the whole ultra-violet-visible (UV-VIS) spectrum in partial last square regression (PLSR) models. This study was carried out in a small (1.19 km(2)) rural catchment from southern Brazil. The sediment sources evaluated were crop fields, unpaved roads, and stream channels. Color parameters were only able to discriminate unpaved roads from the other sources, disabling its use to fingerprint sediment sources itself. Nonetheless, there was a great improvement in source discrimination combining geochemical tracers and color parameters. Unlike VIS-based-color parameters, the distances between sediment sources were always significantly different using the whole UV-VIS-spectrum. It indicates a loss of information and, consequently, loss of discriminating power when using VIS-based-color parameters instead of the whole UV-VIS spectrum. Overall, there was good agreement in source ascription obtained with geochemical tracers alone, geochemical tracers coupled with color parameters, and UV-VIS-PLSR models, and all of them indicate clearly that the main sediment source was the crop fields, corresponding to 57 ± 14, 48 ± 13, and 62 ± 18%, respectively. Prediction errors for UV-VIS-PLSR models (6.6 ± 1.1%) were very similar to those generated in a mixed linear model using geochemical tracers alone (6.4 ± 3.6%), but the combination of color parameters and geochemical tracers

  3. Sensitivities to source-term parameters of emergency planning zone boundaries for waste management facilities

    SciTech Connect

    Mueller, C.J.

    1995-07-01

    This paper reviews the key parameters comprising airborne radiological and chemical release source terms, discusses the ranges over which values of these parameters occur for plausible but severe waste management facility accidents, and relates the concomitant sensitivities of emergency planning zone boundaries predicted on calculated distances to early severe health effects.

  4. Numerical investigation and electro-acoustic modeling of measurement methods for the in-duct acoustical source parameters

    NASA Astrophysics Data System (ADS)

    Jang, Seung-Ho; Ih, Jeong-Guon

    2003-02-01

    It is known that the direct method yields different results from the indirect (or load) method in measuring the in-duct acoustic source parameters of fluid machines. The load method usually comes up with a negative source resistance, although a fairly accurate prediction of radiated noise can be obtained from any method. This study is focused on the effect of the time-varying nature of fluid machines on the output results of two typical measurement methods. For this purpose, a simplified fluid machine consisting of a reservoir, a valve, and an exhaust pipe is considered as representing a typical periodic, time-varying system and the measurement situations are simulated by using the method of characteristics. The equivalent circuits for such simulations are also analyzed by considering the system as having a linear time-varying source. It is found that the results from the load method are quite sensitive to the change of cylinder pressure or valve profile, in contrast to those from the direct method. In the load method, the source admittance turns out to be predominantly dependent on the valve admittance at the calculation frequency as well as the valve and load admittances at other frequencies. In the direct method, however, the source resistance is always positive and the source admittance depends mainly upon the zeroth order of valve admittance.

  5. An almost-parameter-free harmony search algorithm for groundwater pollution source identification.

    PubMed

    Jiang, Simin; Zhang, Yali; Wang, Pei; Zheng, Maohui

    2013-01-01

    The spatiotemporal characterization of unknown sources of groundwater pollution is frequently encountered in environmental problems. This study adopts a simulation-optimization approach that combines a contaminant transport simulation model with a heuristic harmony search algorithm to identify unknown pollution sources. In the proposed methodology, an almost-parameter-free harmony search algorithm is developed. The performance of this methodology is evaluated on an illustrative groundwater pollution source identification problem, and the identified results indicate that the proposed almost-parameter-free harmony search algorithm-based optimization model can give satisfactory estimations, even when the irregular geometry, erroneous monitoring data, and prior information shortage of potential locations are considered.

  6. The core dominance parameter and Fermi detection of extragalactic radio sources

    NASA Astrophysics Data System (ADS)

    Liu, Zhen-Kuo; Wu, Zhong-Zu; Gu, Min-Feng

    2016-08-01

    By cross-correlating an archive sample of 542 extragalactic radio sources with the Fermi-LAT Third Source Catalog (3FGL), we have compiled a sample of 80 γ-ray sources and 462 non-Fermi sources with available core dominance parameter (R CD), and core and extended radio luminosity; all the parameters are directly measured or derived from available data in the literature. We found that R CD has significant correlations with radio core luminosity, γ-ray luminosity and γ-ray flux; the Fermi sources have on average higher R CD than non-Fermi sources. These results indicate that the Fermi sources should be more compact, and the beaming effect should play a crucial role in the detection of γ-ray emission. Moreover, our results also show Fermi sources have systematically larger radio flux than non-Fermi sources at fixed R CD, indicating larger intrinsic radio flux in Fermi sources. These results show a strong connection between radio and γ-ray flux for the present sample and indicate that the non-Fermi sources are likely due to the low beaming effect, and/or the low intrinsic γ-ray flux. This supports a scenario that has been published in the literature: a co-spatial origin of the activity for the radio and γ-ray emission, suggesting that the origin of the seed photons for the high-energy γ-ray emission is within the jet.

  7. Impact of various operating modes on performance and emission parameters of small heat source

    NASA Astrophysics Data System (ADS)

    Vician, Peter; Holubčík, Michal; Palacka, Matej; Jandačka, Jozef

    2016-06-01

    Thesis deals with the measurement of performance and emission parameters of small heat source for combustion of biomass in each of its operating modes. As the heat source was used pellet boiler with an output of 18 kW. The work includes design of experimental device for measuring the impact of changes in air supply and method for controlling the power and emission parameters of heat sources for combustion of woody biomass. The work describes the main factors that affect the combustion process and analyze the measurements of emissions at the heat source. The results of experiment demonstrate the values of performance and emissions parameters for the different operating modes of the boiler, which serve as a decisive factor in choosing the appropriate mode.

  8. Estimation of seismic source parameters for earthquakes in the southern Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Rhee, H.; Sheen, D.

    2013-12-01

    Recent seismicity in the Korean Peninsula is shown to be low but there is the potential for more severe seismic activity. Historical records show that there were many damaging earthquakes around the Peninsula. Absence of instrumental records of damaging earthquakes hinders our efforts to understand seismotectonic characteristics in the Peninsula and predict seismic hazards. Therefore it is important to analyze instrumental records precisely to help improve our knowledge of seismicity in this region. Several studies on seismic source parameters in the Korean Peninsula were performed to find source parameters for a single event (Kim, 2001; Jo and Baag, 2007; Choi, 2009; Choi and Shim, 2009; Choi, 2010; Choi and Noh, 2010; Kim et al., 2010), to find relationships between source parameters (Kim and Kim, 2008; Shin and Kang, 2008) or to determine the input parameters for the stochastic strong ground motion simulation (Jo and Baag, 2001; Junn et al., 2002). In all previous studies, however, the source parameters were estimated only from small numbers of large earthquakes in this region. To understand the seismotectonic environment in low seismicity region, it will be better that a study on the source parameters is performed by using as many data as we can. In this study, therefore, we estimated seismic source parameters, such as the corner frequency, Brune stress drop and moment magnitude, from 503 events with ML≥1.6 that occurred in the southern part of the Korean Peninsula from 2001 to 2012. The data set consist of 2,834 S-wave trains on three-component seismograms recorded at broadband seismograph stations which have been operating by the Korea Meteorological Administration and the Korea Institute of Geoscience and Mineral Resources. To calculate the seismic source parameters, we used the iterative method of Jo and Baag (2001) based on the methods of Snoke (1987) and Andrews (1986). In this method, the source parameters are estimated by using the integration of

  9. Observations of earthquake source parameters at 2 km depth in the Long Valley Caldera, eastern California

    USGS Publications Warehouse

    Prejean, Stephanie G.; Ellsworth, William L.

    2001-01-01

    To investigate seismic source parameter scaling and seismic efficiency in the Long Valley caldera, California, we measured source parameters for 41 earthquakes (M 0.5 to M 5) recorded at 2 km depth in the Long Valley Exploratory Well. Borehole recordings provide a wide frequency bandwidth, typically 1 to 200–300 Hz, and greatly reduce seismic noise and path effects compared to surface recordings. We calculated source parameters in both the time and frequency domains for P and S waves. At frequencies above the corner frequency, spectra decay faster than ω3, indicating that attenuation plays an important role in shaping the spectra (path averaged Qp = 100–400, Qs = 200–800). Source parameters are corrected for attenuation and radiation pattern. Both static stress drops and apparent stresses range from approximately 0.01 to 30 MPa. Although static stress drops do not vary with seismic moment for these data, our analyses are consistent with apparent stress increasing with increasing moment. To estimate tectonic driving stress and seismic efficiencies in the region, we combined source parameter measurements with knowledge of the stress field and a Coulomb failure criterion to infer a driving stress of 40–70 MPa. Subsequent seismic efficiencies are consistent with McGarr's (1999) hypothesis of a maximum seismic efficiency of 6%.

  10. Impulse source versus dodecahedral loudspeaker for measuring parameters derived from the impulse response in room acoustics.

    PubMed

    San Martín, Ricardo; Arana, Miguel; Machín, Jorge; Arregui, Abel

    2013-07-01

    This study investigates the performance of dodecahedral and impulse sources when measuring acoustic parameters in enclosures according to ISO 3382-1 [Acoustics-Measurement of room acoustic parameters. Part 1: Performance spaces (International Organization for Standardization, Geneva, Switzerland, 2009)]. In general, methods using speakers as a sound source are limited by their frequency response and directivity. On the other hand, getting impulse responses from impulse sources typically involves a lack of repeatability, and it is usually necessary to average several measurements for each position. Through experiments in different auditoriums that recreate typical situations in which the measurement standard is applied, it is found that using impulse sources leads to greater variation in the results, especially at low frequencies. However, this prevents subsequent dispersions due to variables that this technique does not require, such as the orientation of the emitting source. These dispersions may be relevant at high frequencies exceeding the established tolerance criteria for certain parameters. Finally, a new descriptor for dodecahedral sources reflecting the influence their lack of omnidirectionality produces on measuring acoustic parameters is proposed.

  11. Source parameters controlling the generation and propagation of potential local tsunamis along the cascadia margin

    USGS Publications Warehouse

    Geist, E.; Yoshioka, S.

    1996-01-01

    The largest uncertainty in assessing hazards from local tsunamis along the Cascadia margin is estimating the possible earthquake source parameters. We investigate which source parameters exert the largest influence on tsunami generation and determine how each parameter affects the amplitude of the local tsunami. The following source parameters were analyzed: (1) type of faulting characteristic of the Cascadia subduction zone, (2) amount of slip during rupture, (3) slip orientation, (4) duration of rupture, (5) physical properties of the accretionary wedge, and (6) influence of secondary faulting. The effect of each of these source parameters on the quasi-static displacement of the ocean floor is determined by using elastic three-dimensional, finite-element models. The propagation of the resulting tsunami is modeled both near the coastline using the two-dimensional (x-t) Peregrine equations that includes the effects of dispersion and near the source using the three-dimensional (x-y-t) linear long-wave equations. The source parameters that have the largest influence on local tsunami excitation are the shallowness of rupture and the amount of slip. In addition, the orientation of slip has a large effect on the directivity of the tsunami, especially for shallow dipping faults, which consequently has a direct influence on the length of coastline inundated by the tsunami. Duration of rupture, physical properties of the accretionary wedge, and secondary faulting all affect the excitation of tsunamis but to a lesser extent than the shallowness of rupture and the amount and orientation of slip. Assessment of the severity of the local tsunami hazard should take into account that relatively large tsunamis can be generated from anomalous 'tsunami earthquakes' that rupture within the accretionary wedge in comparison to interplate thrust earthquakes of similar magnitude. ?? 1996 Kluwer Academic Publishers.

  12. Joint Inversion of Earthquake Source Parameters with local and teleseismic body waves

    NASA Astrophysics Data System (ADS)

    Chen, W.; Ni, S.; Wang, Z.

    2011-12-01

    In the classical source parameter inversion algorithm of CAP (Cut and Paste method, by Zhao and Helmberger), waveform data at near distances (typically less than 500km) are partitioned into Pnl and surface waves to account for uncertainties in the crustal models and different amplitude weight of body and surface waves. The classical CAP algorithms have proven effective for resolving source parameters (focal mechanisms, depth and moment) for earthquakes well recorded on relatively dense seismic network. However for regions covered with sparse stations, it is challenging to achieve precise source parameters . In this case, a moderate earthquake of ~M6 is usually recorded on only one or two local stations with epicentral distances less than 500 km. Fortunately, an earthquake of ~M6 can be well recorded on global seismic networks. Since the ray paths for teleseismic and local body waves sample different portions of the focal sphere, combination of teleseismic and local body wave data helps constrain source parameters better. Here we present a new CAP mothod (CAPjoint), which emploits both teleseismic body waveforms (P and SH waves) and local waveforms (Pnl, Rayleigh and Love waves) to determine source parameters. For an earthquake in Nevada that is well recorded with dense local network (USArray stations), we compare the results from CAPjoint with those from the traditional CAP method involving only of local waveforms , and explore the efficiency with bootstraping statistics to prove the results derived by CAPjoint are stable and reliable. Even with one local station included in joint inversion, accuracy of source parameters such as moment and strike can be much better improved.

  13. Multi-scale comparison of source parameter estimation using empirical Green's function approach

    NASA Astrophysics Data System (ADS)

    Chen, X.; Cheng, Y.

    2015-12-01

    Analysis of earthquake source parameters requires correction of path effect, site response, and instrument responses. Empirical Green's function (EGF) method is one of the most effective methods in removing path effects and station responses by taking the spectral ratio between a larger and smaller event. Traditional EGF method requires identifying suitable event pairs, and analyze each event individually. This allows high quality estimations for strictly selected events, however, the quantity of resolvable source parameters is limited, which challenges the interpretation of spatial-temporal coherency. On the other hand, methods that exploit the redundancy of event-station pairs are proposed, which utilize the stacking technique to obtain systematic source parameter estimations for a large quantity of events at the same time. This allows us to examine large quantity of events systematically, facilitating analysis of spatial-temporal patterns, and scaling relationship. However, it is unclear how much resolution is scarified during this process. In addition to the empirical Green's function calculation, choice of model parameters and fitting methods also lead to biases. Here, using two regional focused arrays, the OBS array in the Mendocino region, and the borehole array in the Salton Sea geothermal field, I compare the results from the large scale stacking analysis, small-scale cluster analysis, and single event-pair analysis with different fitting methods to systematically compare the results within completely different tectonic environment, in order to quantify the consistency and inconsistency in source parameter estimations, and the associated problems.

  14. Considering uncertainties in the determination of earthquake source parameters from seismic spectra

    NASA Astrophysics Data System (ADS)

    Garcia-Aristizabal, Alexander; Caciagli, Marco; Selva, Jacopo

    2016-11-01

    In this paper, we present a method for handling uncertainties in the determination of the source parameters of earthquakes from spectral data. We propose a robust framework for estimating earthquake source parameters and relative uncertainties, which are propagated down to the estimation of basic seismic parameters of interest such as the seismic moment, the moment magnitude, the source size and the static stress drop. In practice, we put together a Bayesian approach for model parameter estimation and a weighted statistical mixing of multiple solutions obtained from a network of instruments, providing a useful framework for extracting meaningful data from intrinsically uncertain data sets. The Bayesian approach used to estimate the source spectra parameters is a simple but powerful mechanism for non-linear model fitting, providing also the opportunity to naturally propagate uncertainties and to assess the quality and uniqueness of the solution. Another important added value of such an approach is the possibility of integrating information from the expertise of seismologists. Such data can be encoded in a prior state of information that is then updated with the information provided by seismological data. The performance of the proposed approach is demonstrated analysing data from the 1909 April 23 earthquake occurred near Benavente (Portugal).

  15. A study on the seismic source parameters for earthquakes occurring in the southern Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Rhee, H. M.; Sheen, D. H.

    2015-12-01

    We investigated the characteristics of the seismic source parameters of the southern part of the Korean Peninsula for the 599 events with ML≥1.7 from 2001 to 2014. A large number of data are carefully selected by visual inspection in the time and frequency domains. The data set consist of 5,093 S-wave trains on three-component seismograms recorded at broadband seismograph stations which have been operating by the Korea Meteorological Administration and the Korea Institute of Geoscience and Mineral Resources. The corner frequency, stress drop, and moment magnitude of each event were measured by using the modified method of Jo and Baag (2001), based on the methods of Snoke (1987) and Andrews (1986). We found that this method could improve the stability of the estimation of source parameters from S-wave displacement spectrum by an iterative process. Then, we compared the source parameters with those obtained from previous studies and investigated the source scaling relationship and the regional variations of source parameters in the southern Korean Peninsula.

  16. How sensitive is earthquake ground motion to source parameters? Insights from a numerical study in the Mygdonian basin

    NASA Astrophysics Data System (ADS)

    Chaljub, Emmanuel; Maufroy, Emeline; deMartin, Florent; Hollender, Fabrice; Guyonnet-Benaize, Cédric; Manakou, Maria; Savvaidis, Alexandros; Kiratzi, Anastasia; Roumelioti, Zaferia; Theodoulidis, Nikos

    2014-05-01

    Understanding the origin of the variability of earthquake ground motion is critical for seismic hazard assessment. Here we present the results of a numerical analysis of the sensitivity of earthquake ground motion to seismic source parameters, focusing on the Mygdonian basin near Thessaloniki (Greece). We use an extended model of the basin (65 km [EW] x 50 km [NS]) which has been elaborated during the Euroseistest Verification and Validation Project. The numerical simulations are performed with two independent codes, both implementing the Spectral Element Method. They rely on a robust, semi-automated, mesh design strategy together with a simple homogenization procedure to define a smooth velocity model of the basin. Our simulations are accurate up to 4 Hz, and include the effects of surface topography and of intrinsic attenuation. Two kinds of simulations are performed: (1) direct simulations of the surface ground motion for real regional events having various back azimuth with respect to the center of the basin; (2) reciprocity-based calculations where the ground motion due to 980 different seismic sources is computed at a few stations in the basin. In the reciprocity-based calculations, we consider epicentral distances varying from 2.5 km to 40 km, source depths from 1 km to 15 km and we span the range of possible back-azimuths with a 10 degree bin. We will present some results showing (1) the sensitivity of ground motion parameters to the location and focal mechanism of the seismic sources; and (2) the variability of the amplification caused by site effects, as measured by standard spectral ratios, to the source characteristics

  17. Extraction of accurate structure-factor amplitudes from Laue data: wavelength normalization with wiggler and undulator X-ray sources.

    PubMed

    Srajer, V; Crosson, S; Schmidt, M; Key, J; Schotte, F; Anderson, S; Perman, B; Ren, Z; Teng, T Y; Bourgeois, D; Wulff, M; Moffat, K

    2000-07-01

    Wavelength normalization is an essential part of processing of Laue X-ray diffraction data and is critically important for deriving accurate structure-factor amplitudes. The results of wavelength normalization for Laue data obtained in nanosecond time-resolved experiments at the ID09 beamline at the European Synchrotron Radiation Facility, Grenoble, France, are presented. Several wiggler and undulator insertion devices with complex spectra were used. The results show that even in the most challenging cases, such as wiggler/undulator tandems or single-line undulators, accurate wavelength normalization does not require unusually redundant Laue data and can be accomplished using typical Laue data sets. Single-line undulator spectra derived from Laue data compare well with the measured incident X-ray spectra. Successful wavelength normalization of the undulator data was also confirmed by the observed signal in nanosecond time-resolved experiments. Single-line undulators, which are attractive for time-resolved experiments due to their high peak intensity and low polychromatic background, are compared with wigglers, based on data obtained on the same crystal. PMID:16609201

  18. The role of cognitive switching in head-up displays. [to determine pilot ability to accurately extract information from either of two sources

    NASA Technical Reports Server (NTRS)

    Fischer, E.

    1979-01-01

    The pilot's ability to accurately extract information from either one or both of two superimposed sources of information was determined. Static, aerial, color 35 mm slides of external runway environments and slides of corresponding static head-up display (HUD) symbology were used as the sources. A three channel tachistoscope was utilized to show either the HUD alone, the scene alone, or the two slides superimposed. Cognitive performance of the pilots was assessed by determining the percentage of correct answers given to two HUD related questions, two scene related questions, or one HUD and one scene related question.

  19. Seismic Source Parameters of Normal-Faulting Inslab Earthquakes in Central Mexico

    NASA Astrophysics Data System (ADS)

    Rodríguez-Pérez, Quetzalcoatl; Singh, Shri Krishna

    2016-08-01

    We studied 62 normal-faulting inslab earthquakes in the Mexican subduction zone with magnitudes in the range of 3.6 ≤ M w ≤ 7.3 and hypocentral depths of 30 ≤ Z ≤ 108 km. We used different methods to estimate source parameters to observe differences in stress drop, corner frequencies, source dimensions, source duration, energy-to-moment ratio, radiated efficiency, and radiated seismic energy. The behavior of these parameters is derived. We found that normal-faulting inslab events have higher radiated seismic energy, energy-to-moment ratio, and stress drop than interplate earthquakes as expected. This may be explained by the mechanism dependence of radiated seismic energy and apparent stress reported in previous source parameter studies. The energy-to-moment ratio data showed large scatter and no trend with seismic moment. The stress drop showed no trend with seismic moment, but an increment with depth. The radiated seismic efficiencies showed similar values to those obtained from interplate events, but higher than near-trench events. We found that the source duration is independent of the depth. We also derived source scaling relationships for the mentioned parameters. The low level of uncertainties for the seismic source parameters and scaling relationships showed that the obtained parameters are robust. Therefore, reliable source parameter estimation can be carried out using the obtained scaling relationships. We also studied regional stress field of normal-faulting inslab events. Heterogeneity exists in the regional stress field, as indicated by individual stress tensor inversions conducted for two different depth intervals ( Z < 40 km and Z > 40 km, respectively). While the maximum stress axis ( σ 1) appears to be consistent and stable, the orientations of the intermediate and minimum stresses ( σ 2 and σ 3) vary over the depth intervals. The stress inversion results showed that the tensional axes are parallel to the dip direction of the subducted

  20. Dependence of the source performance on plasma parameters at the BATMAN test facility

    SciTech Connect

    Wimmer, C.; Fantz, U.

    2015-04-08

    The investigation of the dependence of the source performance (high j{sub H{sup −}}, low j{sub e}) for optimum Cs conditions on the plasma parameters at the BATMAN (Bavarian Test MAchine for Negative hydrogen ions) test facility is desirable in order to find key parameters for the operation of the source as well as to deepen the physical understanding. The most relevant source physics takes place in the extended boundary layer, which is the plasma layer with a thickness of several cm in front of the plasma grid: the production of H{sup −}, its transport through the plasma and its extraction, inevitably accompanied by the co-extraction of electrons. Hence, a link of the source performance with the plasma parameters in the extended boundary layer is expected. In order to characterize electron and negative hydrogen ion fluxes in the extended boundary layer, Cavity Ring-Down Spectroscopy and Langmuir probes have been applied for the measurement of the H{sup −} density and the determination of the plasma density, the plasma potential and the electron temperature, respectively. The plasma potential is of particular importance as it determines the sheath potential profile at the plasma grid: depending on the plasma grid bias relative to the plasma potential, a transition in the plasma sheath from an electron repelling to an electron attracting sheath takes place, influencing strongly the electron fraction of the bias current and thus the amount of co-extracted electrons. Dependencies of the source performance on the determined plasma parameters are presented for the comparison of two source pressures (0.6 Pa, 0.45 Pa) in hydrogen operation. The higher source pressure of 0.6 Pa is a standard point of operation at BATMAN with external magnets, whereas the lower pressure of 0.45 Pa is closer to the ITER requirements (p ≤ 0.3 Pa)

  1. Dependence of the source performance on plasma parameters at the BATMAN test facility

    NASA Astrophysics Data System (ADS)

    Wimmer, C.; Fantz, U.

    2015-04-01

    The investigation of the dependence of the source performance (high jH-, low je) for optimum Cs conditions on the plasma parameters at the BATMAN (Bavarian Test MAchine for Negative hydrogen ions) test facility is desirable in order to find key parameters for the operation of the source as well as to deepen the physical understanding. The most relevant source physics takes place in the extended boundary layer, which is the plasma layer with a thickness of several cm in front of the plasma grid: the production of H-, its transport through the plasma and its extraction, inevitably accompanied by the co-extraction of electrons. Hence, a link of the source performance with the plasma parameters in the extended boundary layer is expected. In order to characterize electron and negative hydrogen ion fluxes in the extended boundary layer, Cavity Ring-Down Spectroscopy and Langmuir probes have been applied for the measurement of the H- density and the determination of the plasma density, the plasma potential and the electron temperature, respectively. The plasma potential is of particular importance as it determines the sheath potential profile at the plasma grid: depending on the plasma grid bias relative to the plasma potential, a transition in the plasma sheath from an electron repelling to an electron attracting sheath takes place, influencing strongly the electron fraction of the bias current and thus the amount of co-extracted electrons. Dependencies of the source performance on the determined plasma parameters are presented for the comparison of two source pressures (0.6 Pa, 0.45 Pa) in hydrogen operation. The higher source pressure of 0.6 Pa is a standard point of operation at BATMAN with external magnets, whereas the lower pressure of 0.45 Pa is closer to the ITER requirements (p ≤ 0.3 Pa).

  2. Earthquake Source Parameters Relationships from 3D Rough Fault Dynamic Rupture

    NASA Astrophysics Data System (ADS)

    Yao, Q.; Day, S. M.; Shi, Z.

    2015-12-01

    Fault surface roughness has a strong influence on the distribution of stress around the fault, and affects the dynamics of the earthquake process. In particular, roughness influences the distribution of the parameters conventionally used to describe fault slip in, for example, kinematic modeling of strong ground motion. We explore the effect of the fault roughness on earthquake source parameters through the statistical analysis of a large suite of 3D rupture simulations. We have built a database of more than 1000 simulated dynamic ruptures based on different rough fault profiles and relative-strength (S) ratios, and have quantitatively analyzed the correlation between earthquake source parameter pairs.. In the subshear propagation-speed regime, we find the following relationships: (1) Rise time, total slip and peak slip rate each decrease with increasing roughness. (2) Rupture velocity is weakly positively related to slip, and the relationship is stronger with increasing roughness. We also explore how peak slip rate, rise time and different pairs of source parameters correlations are affected by fault roughness. This work may give useful guidance for use in kinematic rupture-source generators and help improve methods for ground strong motion prediction.

  3. Harmonic allocation of authorship credit: source-level correction of bibliometric bias assures accurate publication and citation analysis.

    PubMed

    Hagen, Nils T

    2008-01-01

    Authorship credit for multi-authored scientific publications is routinely allocated either by issuing full publication credit repeatedly to all coauthors, or by dividing one credit equally among all coauthors. The ensuing inflationary and equalizing biases distort derived bibliometric measures of merit by systematically benefiting secondary authors at the expense of primary authors. Here I show how harmonic counting, which allocates credit according to authorship rank and the number of coauthors, provides simultaneous source-level correction for both biases as well as accommodating further decoding of byline information. I also demonstrate large and erratic effects of counting bias on the original h-index, and show how the harmonic version of the h-index provides unbiased bibliometric ranking of scientific merit while retaining the original's essential simplicity, transparency and intended fairness. Harmonic decoding of byline information resolves the conundrum of authorship credit allocation by providing a simple recipe for source-level correction of inflationary and equalizing bias. Harmonic counting could also offer unrivalled accuracy in automated assessments of scientific productivity, impact and achievement.

  4. Determination of discharge parameters via OES at the Linac4 H- ion source

    NASA Astrophysics Data System (ADS)

    Briefi, S.; Fink, D.; Mattei, S.; Lettry, J.; Fantz, U.

    2016-02-01

    Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (Te ≈ 1.2 eV, ne ≈ 1 × 1019 m-3, and nH/nH2 ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal "hockey-stick" rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients.

  5. Determination of discharge parameters via OES at the Linac4 H⁻ ion source.

    PubMed

    Briefi, S; Fink, D; Mattei, S; Lettry, J; Fantz, U

    2016-02-01

    Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (T(e) ≈ 1.2 eV, n(e) ≈ 1 × 10(19) m(-3), and n(H/)n(H2) ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal "hockey-stick" rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients. PMID:26931986

  6. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information.

    PubMed

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan W; Jin, Ke; Du, Yingge; Neeway, James J; Ryan, Joseph V; Hu, Dehong; Zhang, Kelvin H L; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampilai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    The use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass (SON68) and layered hole-perovskite oxide thin films were selected as model systems because of their fundamental and practical significance. Our results show that high sputter rates and accurate interfacial information can be achieved simultaneously for argon cluster sputtering, whereas this is not the case for cesium and oxygen sputtering. Therefore, the implementation of an argon cluster sputtering source can significantly improve the analysis efficiency of insulating materials and, thus, can expand its applications to the study of glass corrosion, perovskite oxide thin film characterization, and many other systems of interest.

  7. Assessing the Uncertainties on Seismic Source Parameters: Towards Realistic Estimates of Moment Tensor Determinations

    NASA Astrophysics Data System (ADS)

    Magnoni, F.; Scognamiglio, L.; Tinti, E.; Casarotti, E.

    2014-12-01

    Seismic moment tensor is one of the most important source parameters defining the earthquake dimension and style of the activated fault. Moment tensor catalogues are ordinarily used by geoscientists, however, few attempts have been done to assess possible impacts of moment magnitude uncertainties upon their own analysis. The 2012 May 20 Emilia mainshock is a representative event since it is defined in literature with a moment magnitude value (Mw) spanning between 5.63 and 6.12. An uncertainty of ~0.5 units in magnitude leads to a controversial knowledge of the real size of the event. The possible uncertainty associated to this estimate could be critical for the inference of other seismological parameters, suggesting caution for seismic hazard assessment, coulomb stress transfer determination and other analyses where self-consistency is important. In this work, we focus on the variability of the moment tensor solution, highlighting the effect of four different velocity models, different types and ranges of filtering, and two different methodologies. Using a larger dataset, to better quantify the source parameter uncertainty, we also analyze the variability of the moment tensor solutions depending on the number, the epicentral distance and the azimuth of used stations. We endorse that the estimate of seismic moment from moment tensor solutions, as well as the estimate of the other kinematic source parameters, cannot be considered an absolute value and requires to come out with the related uncertainties and in a reproducible framework characterized by disclosed assumptions and explicit processing workflows.

  8. Prediction of broadband ground-motion time histories: Hybrid low/high-frequency method with correlated random source parameters

    USGS Publications Warehouse

    Liu, P.; Archuleta, R.J.; Hartzell, S.H.

    2006-01-01

    We present a new method for calculating broadband time histories of ground motion based on a hybrid low-frequency/high-frequency approach with correlated source parameters. Using a finite-difference method we calculate low- frequency synthetics (< ∼1 Hz) in a 3D velocity structure. We also compute broadband synthetics in a 1D velocity model using a frequency-wavenumber method. The low frequencies from the 3D calculation are combined with the high frequencies from the 1D calculation by using matched filtering at a crossover frequency of 1 Hz. The source description, common to both the 1D and 3D synthetics, is based on correlated random distributions for the slip amplitude, rupture velocity, and rise time on the fault. This source description allows for the specification of source parameters independent of any a priori inversion results. In our broadband modeling we include correlation between slip amplitude, rupture velocity, and rise time, as suggested by dynamic fault modeling. The method of using correlated random source parameters is flexible and can be easily modified to adjust to our changing understanding of earthquake ruptures. A realistic attenuation model is common to both the 3D and 1D calculations that form the low- and high-frequency components of the broadband synthetics. The value of Q is a function of the local shear-wave velocity. To produce more accurate high-frequency amplitudes and durations, the 1D synthetics are corrected with a randomized, frequency-dependent radiation pattern. The 1D synthetics are further corrected for local site and nonlinear soil effects by using a 1D nonlinear propagation code and generic velocity structure appropriate for the site’s National Earthquake Hazards Reduction Program (NEHRP) site classification. The entire procedure is validated by comparison with the 1994 Northridge, California, strong ground motion data set. The bias and error found here for response spectral acceleration are similar to the best results

  9. Accurate positions for the ultraluminous X-ray sources NGC 7319-X4 and NGC 5474-X1 and limiting magnitudes for their optical counterparts

    NASA Astrophysics Data System (ADS)

    Heida, M.; Jonker, P. G.; Torres, M. A. P.; Mineo, S.

    2012-08-01

    In this paper, we report accurate Chandra positions for two ultraluminous X-ray sources (ULXs): NGC 7319-X4 at Right Ascension (RA) = 339?029 17(2), Declination (Dec.) = 33?974 76(2) and NGC 5474-X1 at RA = 211?248 59(3), Dec. = 53?635 84(3). We perform bore-sight corrections on the Chandra X-ray satellite observations of these sources to get these accurate positions of the X-ray sources and match these positions with archival optical data from the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope. We do not find the optical counterparts; the limiting absolute magnitudes of the observations in the WFPC2 standard magnitude system are B=-7.9, V=-8.7 and I=-9.3 for NGC 7319-X4 and U=-6.4 for NGC 5474-X1. We report on the X-ray spectral properties and find evidence for X-ray variability in NGC 5474-X1. Finally, we briefly discuss several options for the nature of these ULXs.

  10. Preliminary result of rapid solenoid for controlling heavy-ion beam parameters of laser ion source

    DOE PAGES

    Okamura, M.; Sekine, M.; Ikeda, S.; Kanesue, T.; Kumaki, M.; Fuwa, Y.

    2015-03-13

    To realize a heavy ion inertial fusion driver, we have studied a possibility of laser ion source (LIS). A LIS can provide high current high brightness heavy ion beams, however it was difficult to manipulate the beam parameters. To overcome the issue, we employed a pulsed solenoid in the plasma drift section and investigated the effect of the solenoid field on singly charged iron beams. The rapid ramping magnetic field could enhance limited time slice of the current and simultaneously the beam emittance changed accordingly. This approach may also useful to realize an ion source for HIF power plant.

  11. Simulation of parameter scaling in electron cyclotron resonance ion source plasmas using the GEM code

    SciTech Connect

    Cluggish, B.; Zhao, L.; Kim, J. S.

    2010-02-15

    Although heating power and gas pressure are two of the two of primary experimental ''knobs'' available to users of electron cyclotron resonance ion sources, there is still no clear understanding of how they interact in order to provide optimal plasma conditions. FAR-TECH, Inc. has performed a series of simulations with its generalized electron cyclotron resonance ion source model in which the power and pressure were varied over a wide range. Analysis of the numerical data produces scaling laws that predict the plasma parameters as a function of the power and pressure. These scaling laws are in general agreement with experimental data.

  12. Accurate relative-phase and time-delay maps all over the emission cone of hyperentangled photon source

    NASA Astrophysics Data System (ADS)

    Hegazy, Salem F.; El-Azab, Jala; Badr, Yehia A.; Obayya, Salah S. A.

    2016-04-01

    High flux of hyperentangled photons entails collecting the two-photon emission over relatively wide extent in frequency and transverse space within which the photon pairs are simultaneously entangled in multiple degrees of freedom. In this paper, we present a numerical approach to determining the spatial-spectral relative-phase and time-delay maps of hyperentangled photons all over the spontaneous parametric down conversion (SPDC) emission cone. We consider the hyperentangled-photons produced by superimposing noncollinear SPDC emissions of two crossed and coherentlypumped nonlinear crystals. We adopt a vectorial representation for all parameters of concern. This enables us to study special settings such as the self-compensation via oblique pump incidence. While rigorous quantum treatment of SPDC emission requires Gaussian state representation, in low-gain regime (like the case of the study), it is well approximated to the first order to superposition of vacuum and two-photon states. The relative phase and time-delay maps are then calculated between the two-photon wavepackets created along symmetrical locations of the crystals. Assuming monochromatic plane-wave pump field, the mutual signal-idler relations like energy conservation and transversemomentum conservation define well one of the two-photon with reference to its conjugate. The weaker conservation of longitudinal momentum (due to relatively thin crystals) allows two-photon emission directions coplanar with the pump beam while spreading around the perfect phase-matching direction. While prior works often adopt first-order approximation, it is shown that the relative-phase map is a very well approximated to a quadratic function in the polar angle of the two-photon emission while negligibly varying with the azimuthal angle.

  13. Deep Wideband Single Pointings and Mosaics in Radio Interferometry: How Accurately Do We Reconstruct Intensities and Spectral Indices of Faint Sources?

    NASA Astrophysics Data System (ADS)

    Rau, U.; Bhatnagar, S.; Owen, F. N.

    2016-11-01

    Many deep wideband wide-field radio interferometric surveys are being designed to accurately measure intensities, spectral indices, and polarization properties of faint source populations. In this paper, we compare various wideband imaging methods to evaluate the accuracy to which intensities and spectral indices of sources close to the confusion limit can be reconstructed. We simulated a wideband single-pointing (C-array, L-Band (1–2 GHz)) and 46-pointing mosaic (D-array, C-Band (4–8 GHz)) JVLA observation using a realistic brightness distribution ranging from 1 μJy to 100 mJy and time-, frequency-, polarization-, and direction-dependent instrumental effects. The main results from these comparisons are (a) errors in the reconstructed intensities and spectral indices are larger for weaker sources even in the absence of simulated noise, (b) errors are systematically lower for joint reconstruction methods (such as Multi-Term Multi-Frequency-Synthesis (MT-MFS)) along with A-Projection for accurate primary beam correction, and (c) use of MT-MFS for image reconstruction eliminates Clean-bias (which is present otherwise). Auxiliary tests include solutions for deficiencies of data partitioning methods (e.g., the use of masks to remove clean bias and hybrid methods to remove sidelobes from sources left un-deconvolved), the effect of sources not at pixel centers, and the consequences of various other numerical approximations within software implementations. This paper also demonstrates the level of detail at which such simulations must be done in order to reflect reality, enable one to systematically identify specific reasons for every trend that is observed, and to estimate scientifically defensible imaging performance metrics and the associated computational complexity of the algorithms/analysis procedures. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

  14. A Study of Experimental Measurements of Dosimetric Parameters in HDR IR-192 Source

    SciTech Connect

    Zhang Menglong; Zhang Liangan; Yuan Shuyu; Dai Guangfu

    2010-01-01

    Thermoluminescent dosimeters have been used to perform dosimetry measurements for the widely used Ir-192 microSelectron-HDR source with an improved polystyrene phantom. Radial dose functions and anisotropy functions, main parameters of 2D dose-rate formalism from the TG-43U1 protocol, have been obtained experimentally. Measurement results are compared with that of the Monte Carlo calculations reported, and no difference has been found between them.

  15. Scaling Relations Between Mainshock Source Parameters and Aftershock Distributions for Use in Aftershock Forecasting

    NASA Astrophysics Data System (ADS)

    Donovan, J.; Jordan, T. H.

    2010-12-01

    Aftershocks are often used to delineate the mainshock rupture zone retrospectively. In aftershock forecasting on the other hand, the problem is to use mainshock rupture area to determine the aftershock zone prospectively. The procedures for this type of prediction are not as well developed and have been restricted to simple parameterizations such as the Utsu-Seki (1955) scaling relation between mainshock energy and aftershock area (Ogata and Zhueng, 2006). With a focus on improving current forecasting methods, we investigate the relationship between spatial source parameters that can be rapidly computed (spatial centroid and characteristic dimensions) and corresponding spatial measures of the aftershock distribution. For a set of about 30 large events, we either extracted source parameters from the McGuire et al (2002) finite moment tensor (FMT) catalog, or computed them from the online SRCMOD database (Mai, 2004). We identified aftershocks with windowing and scale-free methods, and computed both L1 and L2 measures of their distributions. Our comparisons produce scaling relations among the characteristic dimensions that can be used to initiate aftershock forecasts. By using rapidly-determined source parameters, we can decrease the forecasting latency and thus improve the probability gain of the forecasting methods.

  16. Complete regional waveform modeling to estimate seismic velocity structure and source parameters for CTBT monitoring

    SciTech Connect

    Bredbeck, T; Rodgers, A; Walter, W

    1999-07-23

    The velocity structures and source parameters estimated by waveform modeling 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 modeling research for CTBT monitoring performed in the last year. In the future we will estimate structure for new regions by modeling waveforms of large well-observed events along additional paths. Of particular interest will be the estimation of velocity 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 velocity models 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.

  17. Inversion of source parameters for moderate and small earthquakes in Beijing region

    NASA Astrophysics Data System (ADS)

    Lan, Cong-Xin; Liu, Jie; Zheng, Si-Hua; Ma, Shi-Zhen; Li, Ju-Zhen

    2005-09-01

    According to the geological structural features, Beijing and the adjacent areas can be divided into two regions of plain in the east and mountain in the west. Among the stations covered by the telemetered digital seismic station network of Earthquake Administration of Beijing Municipality, the stations in the plain area are all borehole ones and the stations in the western mountainous region are all located on the surface bedrock. In the paper, 511 waveform data recorded by the network from Oct. 2001 to Oct. 2004 are used in the researches for the entire Beijing region, the western mountainous region and the eastern plain area, respectively. The Q values are calculated for each area by Atkinson’s method and compared with the existed data. The reliability of the Q values and the reasons for the difference in the Q values are also discussed. Then, the source parameters and site response are inverted by the Moya’s method, in which two models are used. The first model uses the Q values, earthquakes and stations in the sub-areas and the second model uses the Q values, earthquakes and stations in the entire Beijing region. The results indicate that the source parameters and site responses obtained by two models are basically consistent with each other. It also indicates that the source parameters obtained by these methods are not affected by the size of station network.

  18. Kinetic parameters related to sources and sinks of vibrationally excited OH in the nightglow

    SciTech Connect

    McDade, I.C.; Llewellyn, E.J. )

    1987-07-01

    Kinetic parameters related to vibrational deactivation and chemical removal of vibrationally excited OH radicals in the mesosphere are deduced from ground-based measurements of the mean vibrational distribution of the OH Meinel bands in the nightglow. The derived parameters, which rely on a laboratory measured rate coefficient for the removal of OH(v = 9) by O{sub 2} and a set of relative Meinel band transition probabilities, have been obtained for two limiting Meinel band excitation models that differ in the extent to which single-quantum vibrational deactivation and sudden death' collisional removal processes determine the OH vibrational distribution. It is shown that the OH Meinel band emission can be adequately explained with the deduced parameters and the H + O{sub 3} {yields} OH + O{sub 2} reaction as the only chemical source of vibrationally excited OH. Evidence is presented which suggests that the reaction HO{sub 2} + O {leftrightarrow} HO + O{sub 2} may perhaps be involved as a sink of vibrationally excited OH rather than as a potential source. The deduced kinetic parameters should be particularly useful in future Meinel band studies as they have been obtained from an analysis for which there is no assumption about the very uncertain OH radiative lifetimes.

  19. Simultaneous estimation of model parameters and diffuse pollution sources for river water quality modeling.

    PubMed

    Jun, K S; Kang, J W; Lee, K S

    2007-01-01

    Diffuse pollution sources along a stream reach are very difficult to both monitor and estimate. In this paper, a systematic method using an optimal estimation algorithm is presented for simultaneous estimation of diffuse pollution and model parameters in a stream water quality model. It was applied with the QUAL2E model to the South Han River in South Korea for optimal estimation of kinetic constants and diffuse loads along the river. Initial calibration results for kinetic constants selected from a sensitivity analysis reveal that diffuse source inputs for nitrogen and phosphorus are essential to satisfy the system mass balance. Diffuse loads for total nitrogen and total phosphorus were estimated by solving the expanded inverse problem. Comparison of kinetic constants estimated simultaneously with diffuse sources to those estimated without diffuse loads, suggests that diffuse sources must be included in the optimization not only for its own estimation but also for adequate estimation of the model parameters. Application of the optimization method to river water quality modeling is discussed in terms of the sensitivity coefficient matrix structure.

  20. Rapid tsunami models and earthquake source parameters: Far-field and local applications

    USGS Publications Warehouse

    Geist, E.L.

    2005-01-01

    Rapid tsunami models have recently been developed to forecast far-field tsunami amplitudes from initial earthquake information (magnitude and hypocenter). Earthquake source parameters that directly affect tsunami generation as used in rapid tsunami models are examined, with particular attention to local versus far-field application of those models. First, validity of the assumption that the focal mechanism and type of faulting for tsunamigenic earthquakes is similar in a given region can be evaluated by measuring the seismic consistency of past events. Second, the assumption that slip occurs uniformly over an area of rupture will most often underestimate the amplitude and leading-wave steepness of the local tsunami. Third, sometimes large magnitude earthquakes will exhibit a high degree of spatial heterogeneity such that tsunami sources will be composed of distinct sub-events that can cause constructive and destructive interference in the wavefield away from the source. Using a stochastic source model, it is demonstrated that local tsunami amplitudes vary by as much as a factor of two or more, depending on the local bathymetry. If other earthquake source parameters such as focal depth or shear modulus are varied in addition to the slip distribution patterns, even greater uncertainty in local tsunami amplitude is expected for earthquakes of similar magnitude. Because of the short amount of time available to issue local warnings and because of the high degree of uncertainty associated with local, model-based forecasts as suggested by this study, direct wave height observations and a strong public education and preparedness program are critical for those regions near suspected tsunami sources.

  1. Reconciling Earthquake Source Parameters from InSAR and Long-period Seismic Waveform Data

    NASA Astrophysics Data System (ADS)

    Shakibay Senobari, N.; Funning, G.; Ferreira, A. M. G.; Weston, J. M.

    2015-12-01

    Comparisons between earthquake source parameters as determined by InSAR and the global centroid moment tensor (GCMT) catalogue show discrepancies between locations derived using these independent methods (Ferreira et al., 2011; Weston et al., 2011, 2012). Earthquake centroid location determination using InSAR data (named the 'InSAR Centroid Moment Tensor', or 'ICMT' location) is more robust, since it is independent of Earth velocity structure errors that impact on longperiod surface wave inversions used in the GCMT method. Ferreira et al (2011) showed that these discrepancies cannot be resolved at present by applying more detailed 3D Earth velocity structures from mantle tomography models. Earthquake location determination is dependent on the assumed velocity structure, not only in the GCMT method, but also in all of the seismic based earthquake source parameter inversions. Velocity structures are typically produced by seismic tomography, which itself depends on seismic phase travel times. These travel times are a function of source location and origin time, plus the path between the source and receivers. Errors in source location can therefore be compounded as errors in the velocity structure. In a preliminary study we analyze longperiod seismic data for four shallow continental earthquakes studied with InSAR - Zarand Mw 6.5 (Iran, 2005), Eureka Valley Mw 6.1 (California, 1993), Aiquile Mw 6.5 (Bolivia, 1998) and Wells Mw 6.0 (Nevada, 2008). We use the spectral element wave propagation package, SPECFEM3D GLOBE, and Earth model S40RTS (Ritsema et al., 2010) to calculate Green's functions and synthetic seismograms for these events using their ICMT source locations. Using a cross-correlation method we were able to estimate phase shifts for each source-receiver pair between synthetic and observed long period waveforms. We believe these phase shifts may correspond to unmodeled heterogeneity in the S40RTS model, and if systematically documented could provide additional

  2. Experimental and Monte Carlo determination of the TG-43 dosimetric parameters for the model 9011 THINSeed brachytherapy source

    SciTech Connect

    Kennedy, R. M.; Davis, S. D.; Micka, J. A.; DeWerd, L. A.

    2010-04-15

    Purpose: AAPM TG-43 brachytherapy dosimetry parameters for a new, smaller diameter {sup 125}I brachytherapy source (THINSeed, model 9011) were determined using LiF:Mg,Ti thermoluminescent dosimeter (TLD-100) microcubes and Monte Carlo simulations. Methods: Two polymethyl methacrylate phantoms were machined to hold TLD-100 microcubes at specific locations for the experimental determination of the radial dose function, dose-rate constant, and anisotropy functions of the new source. The TG-43 parameters were also calculated using Monte Carlo simulations. For comparison, the model 6711 source was also investigated. Results: Experimental results for both models 9011 and 6711 sources showed good agreement with Monte Carlo values, as well as with previously published values. Conclusions: The TG-43 parameters for the new source model are similar to those of model 6711; however, they represent two separate sources and TG-43 parameters used in treatment planning must be source specific.

  3. Coda Q Attenuation and Source Parameters Analysis in North East India Using Local Earthquakes

    NASA Astrophysics Data System (ADS)

    Mohapatra, A. K.; Mohanty, W. K.; Earthquake Seismology

    2010-12-01

    Alok Kumar Mohapatra1* and William Kumar Mohanty1 *Corresponding author: alokgpiitkgp@gmail.com 1Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur, West Bengal, India. Pin-721302 ABSTRACT In the present study, the quality factor of coda waves (Qc) and the source parameters has been estimated for the Northeastern India, using the digital data of ten local earthquakes from April 2001 to November 2002. Earthquakes with magnitude range from 3.8 to 4.9 have been taken into account. The time domain coda decay method of a single back scattering model is used to calculate frequency dependent values of Coda Q (Qc) where as, the source parameters like seismic moment(Mo), stress drop, source radius(r), radiant energy(Wo),and strain drop are estimated using displacement amplitude spectrum of body wave using Brune's model. The earthquakes with magnitude range 3.8 to 4.9 have been used for estimation Qc at six central frequencies 1.5 Hz, 3.0 Hz, 6.0 Hz, 9.0 Hz, 12.0 Hz, and 18.0 Hz. In the present work, the Qc value of local earthquakes are estimated to understand the attenuation characteristic, source parameters and tectonic activity of the region. Based on a criteria of homogeneity in the geological characteristics and the constrains imposed by the distribution of available events the study region has been classified into three zones such as the Tibetan Plateau Zone (TPZ), Bengal Alluvium and Arakan-Yuma Zone (BAZ), Shillong Plateau Zone (SPZ). It follows the power law Qc= Qo (f/fo)n where, Qo is the quality factor at the reference frequency (1Hz) fo and n is the frequency parameter which varies from region to region. The mean values of Qc reveals a dependence on frequency, varying from 292.9 at 1.5 Hz to 4880.1 at 18 Hz. Average frequency dependent relationship Qc values obtained of the Northeastern India is 198 f 1.035, while this relationship varies from the region to region such as, Tibetan Plateau Zone (TPZ): Qc= 226 f 1.11, Bengal Alluvium

  4. Relationship between Dietary Fat Intake, Its Major Food Sources and Assisted Reproduction Parameters

    PubMed Central

    Kazemi, Ashraf; Ramezanzadeh, Fatemeh; Nasr-Esfahani, Mohammad Hosein

    2014-01-01

    Background High dietary fat consumption may alter oocyte development and embryonic development. This prospective study was conducted to determine the relation between dietary fat consumption level, its food sources and the assisted reproduction parameters. Methods A prospective study was conducted on 240 infertile women. In assisted reproduction treatment cycle, fat consumption and major food sources over the previous three months were identified. The number of retrieved oocytes, metaphase ΙΙ stage oocytes numbers, fertilization rate, embryo quality and clinical pregnancy rate were also determined. The data were analyzed using multiple regression, binary logistic regression, chi-square and t-test. The p-value of less than 0.05 was considered significant. Results Total fat intake adjusted for age, body mass index, physical activity and etiology of infertility was positively associated with the number of retrieved oocytes and inversely associated with the high embryo quality rate. An inverse association was observed between sausage and turkey ham intake and the number of retrieved oocytes. Also, oil intake level had an inverse association with good cleavage rate. Conclusion The results revealed that higher levels of fat consumption tend to increase the number of retrieved oocytes and were adversely related to embryonic development. Among food sources of fat, vegetable oil, sausage and turkey ham intake may adversely affect assisted reproduction parameters. PMID:25473630

  5. Accurate collision-induced line-coupling parameters for the fundamental band of CO in He - Close coupling and coupled states scattering calculations

    NASA Technical Reports Server (NTRS)

    Green, Sheldon; Boissoles, J.; Boulet, C.

    1988-01-01

    The first accurate theoretical values for off-diagonal (i.e., line-coupling) pressure-broadening cross sections are presented. Calculations were done for CO perturbed by He at thermal collision energies using an accurate ab initio potential energy surface. Converged close coupling, i.e., numerically exact values, were obtained for coupling to the R(0) and R(2) lines. These were used to test the coupled states (CS) and infinite order sudden (IOS) approximate scattering methods. CS was found to be of quantitative accuracy (a few percent) and has been used to obtain coupling values for lines to R(10). IOS values are less accurate, but, owing to their simplicity, may nonetheless prove useful as has been recently demonstrated.

  6. Near real-time estimation of the seismic source parameters in a compressed domain

    NASA Astrophysics Data System (ADS)

    Rodriguez, Ismael A. Vera

    Seismic events can be characterized by its origin time, location and moment tensor. Fast estimations of these source parameters are important in areas of geophysics like earthquake seismology, and the monitoring of seismic activity produced by volcanoes, mining operations and hydraulic injections in geothermal and oil and gas reservoirs. Most available monitoring systems estimate the source parameters in a sequential procedure: first determining origin time and location (e.g., epicentre, hypocentre or centroid of the stress glut density), and then using this information to initialize the evaluation of the moment tensor. A more efficient estimation of the source parameters requires a concurrent evaluation of the three variables. The main objective of the present thesis is to address the simultaneous estimation of origin time, location and moment tensor of seismic events. The proposed method displays the benefits of being: 1) automatic, 2) continuous and, depending on the scale of application, 3) of providing results in real-time or near real-time. The inversion algorithm is based on theoretical results from sparse representation theory and compressive sensing. The feasibility of implementation is determined through the analysis of synthetic and real data examples. The numerical experiments focus on the microseismic monitoring of hydraulic fractures in oil and gas wells, however, an example using real earthquake data is also presented for validation. The thesis is complemented with a resolvability analysis of the moment tensor. The analysis targets common monitoring geometries employed in hydraulic fracturing in oil wells. Additionally, it is presented an application of sparse representation theory for the denoising of one-component and three-component microseismicity records, and an algorithm for improved automatic time-picking using non-linear inversion constraints.

  7. Impacts of input parameter spatial aggregation on an agricultural nonpoint source pollution model

    NASA Astrophysics Data System (ADS)

    FitzHugh, T. W.; Mackay, D. S.

    2000-09-01

    The accuracy of agricultural nonpoint source pollution models depends in part on how well model input parameters describe the relevant characteristics of the watershed. The spatial extent of input parameter aggregation has previously been shown to have a substantial impact on model output. This study investigates this problem using the Soil and Water Assessment Tool (SWAT), a distributed-parameter agricultural nonpoint source pollution model. The primary question addressed here is: how does the size or number of subwatersheds used to partition the watershed affect model output, and what are the processes responsible for model behavior? SWAT was run on the Pheasant Branch watershed in Dane County, WI, using eight watershed delineations, each with a different number of subwatersheds. Model runs were conducted for the period 1990-1996. Streamflow and outlet sediment predictions were not seriously affected by changes in subwatershed size. The lack of change in outlet sediment is due to the transport-limited nature of the Pheasant Branch watershed and the stable transport capacity of the lower part of the channel network. This research identifies the importance of channel parameters in determining the behavior of SWAT's outlet sediment predictions. Sediment generation estimates do change substantially, dropping by 44% between the coarsest and the finest watershed delineations. This change is primarily due to the sensitivity of the runoff term in the Modified Universal Soil Loss Equation to the area of hydrologic response units (HRUs). This sensitivity likely occurs because SWAT was implemented in this study with a very detailed set of HRUs. In order to provide some insight on the scaling behavior of the model two indexes were derived using the mathematics of the model. The indexes predicted SWAT scaling behavior from the data inputs without a need for running the model. Such indexes could be useful for model users by providing a direct way to evaluate alternative models

  8. Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source.

    PubMed

    Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

    2016-01-01

    Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors' precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO₄ laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed. PMID:27043567

  9. Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source.

    PubMed

    Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

    2016-03-30

    Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors' precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO₄ laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed.

  10. Optical Riblet Sensor: Beam Parameter Requirements for the Probing Laser Source

    PubMed Central

    Tschentscher, Juliane; Hochheim, Sven; Brüning, Hauke; Brune, Kai; Voit, Kay-Michael; Imlau, Mirco

    2016-01-01

    Beam parameters of a probing laser source in an optical riblet sensor are studied by considering the high demands on a sensors’ precision and reliability for the determination of deviations of the geometrical shape of a riblet. Mandatory requirements, such as minimum intensity and light polarization, are obtained by means of detailed inspection of the optical response of the riblet using ray and wave optics; the impact of wavelength is studied. Novel measures for analyzing the riblet shape without the necessity of a measurement with a reference sample are derived; reference values for an ideal riblet structure obtained with the optical riblet sensor are given. The application of a low-cost, frequency-doubled Nd:YVO4 laser pointer sufficient to serve as a reliable laser source in an appropriate optical riblet sensor is discussed. PMID:27043567

  11. Study on inelastic attenuation coefficient, site response and source parameters in Shanxi region

    NASA Astrophysics Data System (ADS)

    Chuo, Yong-Qing; Su, Yan; Jia, Jian-Xi; Huang, Jin-Gang

    2004-07-01

    Based on 310 horizontal-component digital seismograms recorded at 14 seismic stations in Shanxi Digital Seismograph Network, the inelastic attenuation coefficient in Shanxi region is studied. By the methods of Atkinson and Moya, the site response of each station and several source parameters are obtained and the inversion results from both methods are compared and analyzed. The frequency-dependent inelastic attenuation coefficient Q is estimated as Q(f)=323.2 f 0.506. The site responses of 14 seismic stations do not show significant amplification, which is consistent with their basement on rock. We also found the dependence of corner frequency on seismic moment, seismic moment on stress drop, source radius on stress drop.

  12. Relationship between strong-motion array parameters and the accuracy of source inversion and physical waves

    USGS Publications Warehouse

    Iida, M.; Miyatake, T.; Shimazaki, K.

    1990-01-01

    We develop general rules for a strong-motion array layout on the basis of our method of applying a prediction analysis to a source inversion scheme. A systematic analysis is done to obtain a relationship between fault-array parameters and the accuracy of a source inversion. Our study of the effects of various physical waves indicates that surface waves at distant stations contribute significantly to the inversion accuracy for the inclined fault plane, whereas only far-field body waves at both small and large distances contribute to the inversion accuracy for the vertical fault, which produces more phase interference. These observations imply the adequacy of the half-space approximation used throughout our present study and suggest rules for actual array designs. -from Authors

  13. Collinear Cluster Tripartition as a Neutron Source--Evaluation of the Setup Parameters

    SciTech Connect

    Kamanin, D. V.; Kuznetsova, E. A.; Aleksandrov, A. A.; Aleksandrova, I. A.; Borzakov, S. B.; Chelnokov, M. L.; Pham Minh, D.; Kondratyev, N. A.; Kopach, Yu. N.; Panteleev, Ts.; Penionzhkevich, Yu. E.; Svirikhin, A. I.; Sokol, E. A.; Testov, D. A.; Zhuchko, V. E.; Yeremin, A. V.; Pyatkov, Yu. V.; Jacobs, N.; Ryabov, Yu. V.

    2010-04-30

    Forthcoming experiments aimed at studying the mechanism of collinear cluster tripartition are planning to be performed with the new facility. Charged products will be registered with the double arm time-of-flight spectrometer composed of mosaics of PIN -diodes and MCP (micro channel plates) based timing detectors. Several tens of {sup 3}He-filled counters will be gathered round the {sup 252}Cf source. In order to choose an optimal configuration of the neutron detector and other parameters of the experiment special modeling has performed using both 'neutron barrel' and known MCNP code. The first test run of the new facility is in progress also its 'neutron skin' in under construction.

  14. Preliminary Spreadsheet of Eruption Source Parameters for Volcanoes of the World

    USGS Publications Warehouse

    Mastin, Larry G.; Guffanti, Marianne; Ewert, John W.; Spiegel, Jessica

    2009-01-01

    Volcanic eruptions that spew tephra into the atmosphere pose a hazard to jet aircraft. For this reason, the International Civil Aviation Organization (ICAO) has designated nine Volcanic Ash and Aviation Centers (VAACs) around the world whose purpose is to track ash clouds from eruptions and notify aircraft so that they may avoid these ash clouds. During eruptions, VAACs and their collaborators run volcanic-ashtransport- and-dispersion (VATD) models that forecast the location and movement of ash clouds. These models require as input parameters the plume height H, the mass-eruption rate , duration D, erupted volume V (in cubic kilometers of bubble-free or 'dense rock equivalent' [DRE] magma), and the mass fraction of erupted tephra with a particle size smaller than 63 um (m63). Some parameters, such as mass-eruption rate and mass fraction of fine debris, are not obtainable by direct observation; others, such as plume height or duration, are obtainable from observations but may be unavailable in the early hours of an eruption when VATD models are being initiated. For this reason, ash-cloud modelers need to have at their disposal source parameters for a particular volcano that are based on its recent eruptive history and represent the most likely anticipated eruption. They also need source parameters that encompass the range of uncertainty in eruption size or characteristics. In spring of 2007, a workshop was held at the U.S. Geological Survey (USGS) Cascades Volcano Observatory to derive a protocol for assigning eruption source parameters to ash-cloud models during eruptions. The protocol derived from this effort was published by Mastin and others (in press), along with a world map displaying the assigned eruption type for each of the world's volcanoes. Their report, however, did not include the assigned eruption types in tabular form. Therefore, this Open-File Report presents that table in the form of an Excel spreadsheet. These assignments are preliminary and will

  15. Cytokinin deficiency causes distinct changes of sink and source parameters in tobacco shoots and roots

    PubMed Central

    Werner, Tomáš; Holst, Kerstin; Pörs, Yvonne; Guivarc'h, Anne; Mustroph, Angelika; Chriqui, Dominique; Grimm, Bernhard; Schmülling, Thomas

    2008-01-01

    Cytokinin deficiency causes pleiotropic developmental changes such as reduced shoot and increased root growth. It was investigated whether cytokinin-deficient tobacco plants, which overproduce different cytokinin oxidase/dehydrogenase enzymes, show changes in different sink and source parameters, which could be causally related to the establishment of the cytokinin deficiency syndrome. Ultrastructural analysis revealed distinct changes in differentiating shoot tissues, including an increased vacuolation and an earlier differentiation of plastids, which showed partially disorganized thylakoid structures later in development. A comparison of the ploidy levels revealed an increased population of cells with a 4C DNA content during early stages of leaf development, indicating an inhibited progression from G2 to mitosis. To compare physiological characteristics of sink leaves, source leaves and roots of wild-type and cytokinin-deficient plants, several photosynthetic parameters, content of soluble sugars, starch and adenylates, as well as activities of enzymes of carbon assimilation and dissimilation were determined. Leaves of cytokinin-deficient plants contained less chlorophyll and non-photochemical quenching of young leaves was increased. However, absorption rate, photosynthetic capacity (Fv/Fm and JCO2max) and efficiency (ΦCO2app), as well as the content of soluble sugars, were not strongly altered in source leaves, indicating that chlorophyll is not limiting for photoassimilation and suggesting that source strength did not restrict shoot growth. By contrast, shoot sink tissues showed drastically reduced contents of soluble sugars, decreased activities of vacuolar invertases, and a reduced ATP content. These results strongly support a function of cytokinin in regulating shoot sink strength and its reduction may be a cause of the altered shoot phenotype. Roots of cytokinin-deficient plants contained less sugar compared with wild-type. However, this did not negatively

  16. Characterization of plasma parameters, first beam results, and status of electron cyclotron resonance source

    SciTech Connect

    Jain, S. K.; Jain, Akhilesh; Hannurkar, P. R.; Kotaiah, S.

    2007-05-15

    Electron cyclotron resonance (ECR) plasma source at 50 keV, 30 mA proton current has been designed, fabricated, and assembled. Its plasma study has been done. Plasma chamber was excited with 350 W of microwave power at 2450 MHz, along with nitrogen and hydrogen gases. Microwave power was fed to the plasma chamber through waveguide. Plasma density and electron temperature were studied under various operating conditions, such as magnetic field, gas pressure, and transversal distance. Langmuir probe was used for plasma characterization using current-voltage variation. The nitrogen plasma density calculated was approximately 4.5x10{sup 11} cm{sup -3}, and electron temperatures of 3-10 eV (cold) and 45-85 eV (hot) were obtained. The total ion beam current of 2.5 mA was extracted, with two-electrode extraction geometry, at 15 keV beam energy. The optimization of the source is under progress to extract 30 mA proton beam current at 50 keV beam energy, using three-electrode extraction geometry. This source will be used as an injector to continuous wave radio frequency quadrupole, a part of 100 MeV proton linac. The required root-mean-square normalized beam emittance is less than 0.2{pi} mm mrad. This article presents the study of plasma parameters, first beam results, and status of ECR proton source.

  17. Characterization of plasma parameters, first beam results, and status of electron cyclotron resonance source.

    PubMed

    Jain, S K; Jain, Akhilesh; Hannurkar, P R; Kotaiah, S

    2007-05-01

    Electron cyclotron resonance (ECR) plasma source at 50 keV, 30 mA proton current has been designed, fabricated, and assembled. Its plasma study has been done. Plasma chamber was excited with 350 W of microwave power at 2450 MHz, along with nitrogen and hydrogen gases. Microwave power was fed to the plasma chamber through waveguide. Plasma density and electron temperature were studied under various operating conditions, such as magnetic field, gas pressure, and transversal distance. Langmuir probe was used for plasma characterization using current-voltage variation. The nitrogen plasma density calculated was approximately 4.5 x 10(11) cm(-3), and electron temperatures of 3-10 eV (cold) and 45-85 eV (hot) were obtained. The total ion beam current of 2.5 mA was extracted, with two-electrode extraction geometry, at 15 keV beam energy. The optimization of the source is under progress to extract 30 mA proton beam current at 50 keV beam energy, using three-electrode extraction geometry. This source will be used as an injector to continuous wave radio frequency quadrupole, a part of 100 MeV proton linac. The required root-mean-square normalized beam emittance is less than 0.2pi mm mrad. This article presents the study of plasma parameters, first beam results, and status of ECR proton source.

  18. Volcano deformation source parameters estimated from InSAR and FEM-based nonlinear inverse methods: Sensitivities to uncertainties in seismic tomography

    NASA Astrophysics Data System (ADS)

    Masterlark, T.; Donovan, T. C.; Feigl, K. L.; Haney, M. M.; Thurber, C. H.

    2013-12-01

    Forward models of volcano deformation, due to a pressurized magma chamber embedded in an elastic domain, can predict observed surface deformation. Inverse models of surface deformation allow us to estimate characteristic parameters that describe the deformation source, such as the position and strength of a pressurized magma chamber embedded in an elastic domain. However, the specific distribution of material properties controls how the pressurization translates to surface deformation in a forward model, or alternatively, how observed surface deformation translates to source parameters in an inverse model. Seismic tomography models can describe the specific distributions of material properties that are necessary for accurate forward and inverse models of volcano deformation. The aim of this project is to investigate how uncertainties in seismic tomography models propagate into variations in the estimates of volcano deformation source parameters inverted from geodetic data. To do so, we combine FEM-based nonlinear inverse analyses of InSAR data for Okmok volcano, Alaska, as an example to estimate sensitivities of source parameters to uncertainties in seismic tomography. More specifically, we use Monte Carlo methods to construct an assembly of FEMs that simulate a pressurized magma chamber in the domain of Okmok. Each FEM simulates a realization of source parameters (three-component magma chamber position), a material property distribution that samples the seismic tomography model with a normal velocity perturbation of +/-10%, and a corresponding linear pressure estimate calculated using the Pinned Mesh Perturbation method. We then analyze the posteriori results to quantify sensitivities of source parameter estimates to the seismic tomography uncertainties. Preliminary results suggest that uncertainties in the seismic tomography do not significantly influence the estimated source parameters at a 95% confidence level. The presence of heterogeneous material properties

  19. Calibrating nonlinear volcano deformation source parameters in FEMs: The pinned mesh perturbation method. (Invited)

    NASA Astrophysics Data System (ADS)

    Masterlark, T.; Stone, J.; Feigl, K.

    2010-12-01

    The internal structure, loading processes, and effective boundary conditions of a volcano control the deformation that we observe at the Earth’s surface. Forward models of these internal structures and processes allow us to predict the surface deformation. In practice, we are faced with the inverse situation of using surface observations (e.g., InSAR and GPS) to characterize the inaccessible internal structures and processes. Distortions of these characteristics are tied to our ability to: 1) identify and resolve the internal structure; 2) simulate the internal processes over a problem domain having this internal structure; and 3) calibrate parameters that describe these internal processes to the observed deformation. Relatively simple analytical solutions for deformation sources (such as a pressurized magma chamber) embedded in a homogeneous, elastic half-space are commonly used to simulate observed volcano deformation, because they are computationally inexpensive, and thus easily integrated into inverse analyses that seek to characterize the source position and magnitude. However, the half-space models generally do not adequately represent internal distributions of material properties and complex geometric configurations, such as topography, of volcano deformational systems. These incompatibilities are known to severely bias both source parameter estimations and forward model calculations of deformation and stress. Alternatively, a Finite Element Model (FEM) can simulate the elastic response to a pressurized magma chamber over a domain having arbitrary geometry and distribution of material properties. However, the ability to impose perturbations of the source position parameters and automatically reconstruct an acceptable mesh has been an obstacle to implementing FEM-based nonlinear inverse methods to estimate the position of a deformation source. Using InSAR-observed deflation of Okmok volcano, Alaska, during its 1997 eruption as an example, we present the

  20. Estimation of hyper-parameters for a hierarchical model of combined cortical and extra-brain current sources in the MEG inverse problem.

    PubMed

    Morishige, Ken-ichi; Yoshioka, Taku; Kawawaki, Dai; Hiroe, Nobuo; Sato, Masa-aki; Kawato, Mitsuo

    2014-11-01

    One of the major obstacles in estimating cortical currents from MEG signals is the disturbance caused by magnetic artifacts derived from extra-cortical current sources such as heartbeats and eye movements. To remove the effect of such extra-brain sources, we improved the hybrid hierarchical variational Bayesian method (hyVBED) proposed by Fujiwara et al. (NeuroImage, 2009). hyVBED simultaneously estimates cortical and extra-brain source currents by placing dipoles on cortical surfaces as well as extra-brain sources. This method requires EOG data for an EOG forward model that describes the relationship between eye dipoles and electric potentials. In contrast, our improved approach requires no EOG and less a priori knowledge about the current variance of extra-brain sources. We propose a new method, "extra-dipole," that optimally selects hyper-parameter values regarding current variances of the cortical surface and extra-brain source dipoles. With the selected parameter values, the cortical and extra-brain dipole currents were accurately estimated from the simulated MEG data. The performance of this method was demonstrated to be better than conventional approaches, such as principal component analysis and independent component analysis, which use only statistical properties of MEG signals. Furthermore, we applied our proposed method to measured MEG data during covert pursuit of a smoothly moving target and confirmed its effectiveness. PMID:25034620

  1. Different sperm sources and parameters can influence intracytoplasmic sperm injection outcomes before embryo implantation*

    PubMed Central

    Lu, Yue-hong; Gao, Hui-juan; Li, Bai-jia; Zheng, Ying-ming; Ye, Ying-hui; Qian, Yu-li; Xu, Chen-ming; Huang, He-feng; Jin, Fan

    2012-01-01

    To evaluate the effects of sperm with different parameters and sources on the outcomes of intracytoplasmic sperm injection (ICSI), 1972 ICSI cycles were analyzed retrospectively. Groups 1 to 5 were composed of cycles using ejaculated sperm and were grouped according to sperm quantity, quality, and morphology into normal (288 cycles), or mild (329 cycles), moderate (522 cycles), severe (332 cycles), and extremely severe (171 cycles) oligozoospermia and/or asthenozoospermia and/or teratozoospermia (OAT) groups. Group 6 was composed of 250 cycles using testicular or epididymal sperm, and Group 7 consisted of 80 cycles using frozen-thawed sperm. We found that fertilization rates were gradually reduced from Groups 1 to 6, and reached statistical difference in Groups 5 and 6 (P<0.05). The high-quality embryo rate was higher in Group 1 than in Groups 2, 3, 5, 6, and 7 (P<0.05). No statistical differences were observed in the rates of embryo cleavage, clinical pregnancy, miscarriage, live-birth, premature birth, low birth weight, weeks of premature birth, average birth weight, or sex ratio for all seven groups (P>0.05). A total of nine cases of malformation were observed, with a malformation rate of 1.25% (9/719). In conclusion, different sperm sources and parameters can affect ICSI outcomes before embryo implantation. A full assessment of offspring malformation will require further study using a larger sample size. PMID:22205614

  2. Solving seismological problems using SGRAPH program: I-source parameters and hypocentral location

    SciTech Connect

    Abdelwahed, Mohamed F.

    2012-09-26

    SGRAPH program is considered one of the seismological programs that maintain seismic data. SGRAPH is considered unique for being able to read a wide range of data formats and manipulate complementary tools in different seismological subjects in a stand-alone Windows-based application. SGRAPH efficiently performs the basic waveform analysis and solves advanced seismological problems. The graphical user interface (GUI) utilities and the Windows facilities such as, dialog boxes, menus, and toolbars simplified the user interaction with data. SGRAPH supported the common data formats like, SAC, SEED, GSE, ASCII, and Nanometrics Y-format, and others. It provides the facilities to solve many seismological problems with the built-in inversion and modeling tools. In this paper, I discuss some of the inversion tools built-in SGRAPH related to source parameters and hypocentral location estimation. Firstly, a description of the SGRAPH program is given discussing some of its features. Secondly, the inversion tools are applied to some selected events of the Dahshour earthquakes as an example of estimating the spectral and source parameters of local earthquakes. In addition, the hypocentral location of these events are estimated using the Hypoinverse 2000 program operated by SGRAPH.

  3. The role of remediation, natural alkalinity sources and physical stream parameters in stream recovery.

    PubMed

    Kruse, Natalie A; DeRose, Lisa; Korenowsky, Rebekah; Bowman, Jennifer R; Lopez, Dina; Johnson, Kelly; Rankin, Edward

    2013-10-15

    Acid mine drainage (AMD) negatively impacts not only stream chemistry, but also aquatic biology. The ultimate goal of AMD treatment is restoration of the biological community, but that goal is rarely explicit in treatment system design. Hewett Fork in Raccoon Creek Watershed, Ohio, has been impacted by historic coal mining and has been treated with a calcium oxide doser in the headwaters of the watershed since 2004. All of the acidic inputs are isolated to a 1.5 km stretch of stream in the headwaters of the Hewett Fork watershed. The macroinvertebrate and fish communities have begun to recover and it is possible to distinguish three zones downstream of the doser: an impaired zone, a transition zone and a recovered zone. Alkalinity from both the doser and natural sources and physical stream parameters play a role in stream restoration. In Hewett Fork, natural alkaline additions downstream are higher than those from the doser. Both, alkaline additions and stream velocity drive sediment and metal deposition. Metal deposition occurs in several patterns; aluminum tends to deposit in regions of low stream velocity, while iron tends to deposit once sufficient alkalinity is added to the system downstream of mining inputs. The majority of metal deposition occurs upstream of the recovered zone. Both the physical stream parameters and natural alkalinity sources influence biological recovery in treated AMD streams and should be considered in remediation plans.

  4. Source parameters of intermediate-depth Vrancea (Romania) earthquakes from empirical Green's functions modeling

    NASA Astrophysics Data System (ADS)

    Oth, Adrien; Wenzel, Friedemann; Radulian, Mircea

    2007-06-01

    Several source parameters (source dimensions, slip, particle velocity, static and dynamic stress drop) are determined for the moderate-size October 27th, 2004 ( MW = 5.8), and the large August 30th, 1986 ( MW = 7.1) and March 4th, 1977 ( MW = 7.4) Vrancea (Romania) intermediate-depth earthquakes. For this purpose, the empirical Green's functions method of Irikura [e.g. Irikura, K. (1983). Semi-Empirical Estimation of Strong Ground Motions during Large Earthquakes. Bull. Dis. Prev. Res. Inst., Kyoto Univ., 33, Part 2, No. 298, 63-104., Irikura, K. (1986). Prediction of strong acceleration motions using empirical Green's function, in Proceedings of the 7th Japan earthquake engineering symposium, 151-156., Irikura, K. (1999). Techniques for the simulation of strong ground motion and deterministic seismic hazard analysis, in Proceedings of the advanced study course seismotectonic and microzonation techniques in earthquake engineering: integrated training in earthquake risk reduction practices, Kefallinia, 453-554.] is used to generate synthetic time series from recordings of smaller events (with 4 ≤ MW ≤ 5) in order to estimate several parameters characterizing the so-called strong motion generation area, which is defined as an extended area with homogeneous slip and rise time and, for crustal earthquakes, corresponds to an asperity of about 100 bar stress release [Miyake, H., T. Iwata and K. Irikura (2003). Source characterization for broadband ground-motion simulation: Kinematic heterogeneous source model and strong motion generation area. Bull. Seism. Soc. Am., 93, 2531-2545.] The parameters are obtained by acceleration envelope and displacement waveform inversion for the 2004 and 1986 events and MSK intensity pattern inversion for the 1977 event using a genetic algorithm. The strong motion recordings of the analyzed Vrancea earthquakes as well as the MSK intensity pattern of the 1977 earthquake can be well reproduced using relatively small strong motion

  5. Source Parameters of the 2009 L'Aquila Fault Earthquakes (Italy)

    NASA Astrophysics Data System (ADS)

    Tinti, E.; Scognamiglio, L.; Piccinini, D.; Chiaraluce, L.; Valoroso, L.; Cocco, M.

    2014-12-01

    The 2009 L'Aquila main shock (6th of April, Mw6.1) is one of the best-recorded normal faulting earthquakes with a distinctive foreshock-aftershock sequence. The seismic sequence activated an ~50-km-long, N133°E-trending fault system composed of two major right-stepping en echelon segments: the L'Aquila fault (AF) and the Campotosto fault. We focus our analysis only on the volume containing the high-angle AF segment where the whole foreshock sequence clustered around the nucleation patch together with numerous repeating earthquakes. Analyzing the seismograms of the events that occurred within 6 km (±3) from the AF plane we discuss the complex nucleation and rupture process characterizing the 2009 L'Aquila earthquake together with the inferred heterogeneous distribution of the material/mechanical rock properties, seismicity pattern and coseismic slip, showing how different competing mechanisms control the initial stage of rupture and the dynamic rupture propagation. We compute source parameters (i.e., stress drop, moment magnitude and corner frequency) of foreshocks and aftershocks to investigate the spatial-temporal pattern of fault zone heterogeneities. Source spectra at each station are inferred by using the multi-taper technique and corrected for attenuation; therefore corner frequency is inferred by using the Snoke's relation. Outputs were compared to those we obtained by a multi-window-spectral-ratio technique (MWSR) computing the fit of stacked spectral ratios. Further, we discuss the results with those found in the literature. Ml versus Mw relation is inferred for this dataset. Foreshocks and aftershocks nucleated in the same fault portion do not show any difference in source parameters.

  6. Source parameters of microearthquakes on an interplate asperity off Kamaishi, NE Japan over two earthquake cycles

    USGS Publications Warehouse

    Uchida, Naoki; Matsuzawa, Toru; Ellsworth, William L.; Imanishi, Kazutoshi; Shimamura, Kouhei; Hasegawa, Akira

    2012-01-01

    We have estimated the source parameters of interplate earthquakes in an earthquake cluster off Kamaishi, NE Japan over two cycles of M~ 4.9 repeating earthquakes. The M~ 4.9 earthquake sequence is composed of nine events that occurred since 1957 which have a strong periodicity (5.5 ± 0.7 yr) and constant size (M4.9 ± 0.2), probably due to stable sliding around the source area (asperity). Using P- and S-wave traveltime differentials estimated from waveform cross-spectra, three M~ 4.9 main shocks and 50 accompanying microearthquakes (M1.5–3.6) from 1995 to 2008 were precisely relocated. The source sizes, stress drops and slip amounts for earthquakes of M2.4 or larger were also estimated from corner frequencies and seismic moments using simultaneous inversion of stacked spectral ratios. Relocation using the double-difference method shows that the slip area of the 2008 M~ 4.9 main shock is co-located with those of the 1995 and 2001 M~ 4.9 main shocks. Four groups of microearthquake clusters are located in and around the mainshock slip areas. Of these, two clusters are located at the deeper and shallower edge of the slip areas and most of these microearthquakes occurred repeatedly in the interseismic period. Two other clusters located near the centre of the mainshock source areas are not as active as the clusters near the edge. The occurrence of these earthquakes is limited to the latter half of the earthquake cycles of the M~ 4.9 main shock. Similar spatial and temporal features of microearthquake occurrence were seen for two other cycles before the 1995 M5.0 and 1990 M5.0 main shocks based on group identification by waveform similarities. Stress drops of microearthquakes are 3–11 MPa and are relatively constant within each group during the two earthquake cycles. The 2001 and 2008 M~ 4.9 earthquakes have larger stress drops of 41 and 27 MPa, respectively. These results show that the stress drop is probably determined by the fault properties and does not change

  7. Determination of source parameters for local and regional earthquakes in Israel

    NASA Astrophysics Data System (ADS)

    Ataeva, G.; Shapira, A.; Hofstetter, A.

    2015-04-01

    We have investigated earthquake source parameters and seismic moment-magnitude relations from 103 regional and local earthquakes with moment magnitude 2.6 to 7.2, which occurred in a distance range from 4.5 to 550 km during 1995-2012 by applying Brune's seismic source model (J Geophys Res 75:4997-5009, 1970, J Geophys Res 76:5002, 1971) for P- and S/Lg-wave displacement spectra. Considering P- and S-wave data separately, we first studied the empirical dependence of the Fourier spectral amplitudes Ω due to the geometrical spreading and the inelastic attenuation and of the corner frequency, f 0, with the epicentral distances, R. We found the distance correction parameters, Re 0.0042 R and R 0.8333 e 0.00365 R for the low-frequency spectral amplitudes and f 0 = f {0/'} e 0.00043 R and f 0 = f {0/'} e 0.00044 R for the corner frequency at the source, f 0, and observed at the station, f {0/'}, from P-wave and S-wave spectra, respectively. Applying the distance correction procedure, we determined the source displacement spectrum of P and S waves for each earthquake to estimate the seismic moment, M 0; the moment magnitude, M W; the source radius, r; and the stress drop, Δσ. The seismic moments range from 1.06 × 1013 to 7.67 × 1019 N m, and their corresponding moment magnitudes are in the range of 2.6-7.2. Values of stress drop Δσ vary from 0.1 to 44 MPa. It was found that the stress drop increases with the increasing seismic moment in the range of 1013-1016 N m and possibly becomes constant at higher magnitudes, reaching a maximum value of about 40-45 MPa. We demonstrate that the values of the M 0 and M W estimated from P-wave and S-wave analysis are consistent and confirmed by the results of waveform inversions, i.e., centroid moment tensor (CMT) solution.

  8. Tsunami hazard assessment in Nice, France, and influence of uncertainties in source parameters

    NASA Astrophysics Data System (ADS)

    Fontaine, Agathe; Loevenbruck, Anne; Heinrich, Philippe; Gailler, Audrey; Hébert, Hélène

    2015-04-01

    Although the tsunami hazard on the French Mediterranean coast is still poorly known, potential tsunamigenic sources exist in the Western Mediterranean basin. Even though the water heights are moderate, generated waves and currents could reach busy beaches, harbors and other coastal structures. The European project ASTARTE aims at reaching a higher level of tsunami resilience in the North-East Atlantic and Mediterranean region (called NEAM by IOC-UNESCO). In this context, ASTARTE proposes to improve the knowledge of tsunami generation, develop methods for hazard, vulnerability and risk assessment, better understand local coastal effects and enhance tools for early warning system. 9 test sites, including Nice for the French coasts, have been selected all over the NEAM area. Nice is the largest city of the French Riviera and welcomes a very large number of tourists every year, notably for seaside activities. Moreover its waterfront hosts the second French airport and many other facilities. Our work focuses on the tsunami hazard assessment related to seismic sources. This study, based on a worst-case scenarios approach, is carried out using multigrid numerical simulations. Seismic sources are computed through the Okada elastic dislocation model and constrained with the seismological parameters of the rupture. The coseismic deformation provides the initial condition to solve the shallow water equations on which the tsunami propagation simulation is based. Nested computational grids allow taking into account the shoaling effect for the Nice area as well as the potential inundation. The French Litto3D project, led by SHOM (Service Hydrographique et Oceanographique de la Marine) and IGN (Institut National de l'Information Geographique et Forestiere) provides high resolution bathymetric and topographic data (1 to 5 meters of resolution) along the coastline. Our modeling thus gives detailed estimation of the wave impacts on Nice with a particular focus on three critical

  9. Parameter-specific electronic measurement and analysis of sources of variation using ring oscillators

    NASA Astrophysics Data System (ADS)

    Wang, Lynn T.-N.; Pang, Liang-Teck; Neureuther, Andrew R.; Nikolić, Borivoje

    2009-03-01

    Parameter-specific and simulation-calibrated ring oscillator (RO) inverter layouts are described for identifying and quantitatively modeling sources of circuit performance variation from source/drain stress, shallow trench isolation (STI) stress, lithography, etch, and misalignment. This paper extends the RO approach by adding physical modeling/simulation of the sources of variability to tune the layouts of monitors for enhanced sensitivity and selectivity. Poly and diffusion layout choices have been guided by fast-CAD pattern matching. The accuracy of the fast-CAD estimate from the Pattern Matcher for these lithography issues is corroborated by simulations in Mentor Graphics Calibre. Generic conceptual results are given based on the experience from preparing of proprietary layouts that pass DRC check for a 45 nm test chip with ST Micro. Typical improvements in sensitivity of 2 fold are possible with layouts for lithography focus. A layout monitor for poly to diffusion misalignment based on programmable off-sets shows a 0.8% change in RO frequency per 1nm poly to diffusion off-set. Layouts are also described for characterizing stress effects associated with diffusion area size, asymmetry, vertical spacing, and multiple gate lengths.

  10. Source Parameters of Reservoir-Induced Small Earthquakes: Can We Resolve Rupture Velocity?

    NASA Astrophysics Data System (ADS)

    Tomic, J.; Abercrombie, R. E.; Do Nascimento, A. F.

    2003-12-01

    Abercrombie and Leary (1993) noted that the average stress drops of induced earthquakes appear to be lower than those of tectonic earthquakes. This difference may result from different tectonic setting or the shallow depth of induced earthquakes. Alternatively, it may reflect uncertainties resulting from single station recording, and assumption of rupture velocity and source model. We analyze earthquakes induced by the Açu reservoir, NE Brazil for comparison with tectonic and mining earthquakes. Do Nascimento (2002) located 286 earthquakes (M<=2.8) recorded between 1994 and 1997 on a closely spaced network of 8 3-component seismometers. The locations and focal mechanisms are consistent with activity on NE trending right-lateral faults. The short source-to-receiver distances (<5km) and shallow hypocentral depths (<3km) of the earthquakes, and the low attenuation of the Precambrian basement rock allowed energy at frequencies up to the Nyquist (100 and 250 Hz) to be well recorded at the surface. Starting with the largest earthquakes we search for groups of collocated events. We use 3 different approaches to calculate the source parameters of the largest 2 earthquakes in the first cluster (M2.2 and M1.8), at 4 stations with good azimuthal distribution. We fit the individual spectra using an ω -2 source model to find corner frequency (fc), frequency-independent Q, and long period amplitude. We use the small earthquakes as empirical Green's functions (EGF) and calculate the spectral ratios of the largest earthquake to the smaller events in the cluster. Using the ω -2 model we fit the ratios solving for the fc of the largest earthquake. We then determine the relative source time functions using the EGF method. We will also measure radiated energy. The various estimates of source duration and fc imply stress drops in the range of 1 to 10 MPa. These are similar to tectonic earthquakes suggesting hypocentral depth and strain rate do not affect stress drop. The source

  11. Laser-plasma SXR/EUV sources: adjustment of radiation parameters for specific applications

    NASA Astrophysics Data System (ADS)

    Bartnik, A.; Fiedorowicz, H.; Fok, T.; Jarocki, R.; Kostecki, J.; Szczurek, A.; Szczurek, M.; Wachulak, P.; Wegrzyński, Ł.

    2014-12-01

    In this work soft X-ray (SXR) and extreme ultraviolet (EUV) laser-produced plasma (LPP) sources employing Nd:YAG laser systems of different parameters are presented. First of them is a 10-Hz EUV source, based on a double-stream gaspuff target, irradiated with the 3-ns/0.8J laser pulse. In the second one a 10 ns/10 J/10 Hz laser system is employed and the third one utilizes the laser system with the pulse shorten to approximately 1 ns. Using various gases in the gas puff targets it is possible to obtain intense radiation in different wavelength ranges. This way intense continuous radiation in a wide spectral range as well as quasi-monochromatic radiation was produced. To obtain high EUV or SXR fluence the radiation was focused using three types of grazing incidence collectors and a multilayer Mo/Si collector. First of them is a multfoil gold plated collector consisted of two orthogonal stacks of ellipsoidal mirrors forming a double-focusing device. The second one is the ellipsoidal collector being part of the axisymmetrical ellipsoidal surface. Third of the collectors is composed of two aligned axisymmetrical paraboloidal mirrors optimized for focusing of SXR radiation. The last collector is an off-axis ellipsoidal multilayer Mo/Si mirror allowing for efficient focusing of the radiation in the spectral region centered at λ = 13.5 ± 0.5 nm. In this paper spectra of unaltered EUV or SXR radiation produced in different LPP source configurations together with spectra and fluence values of focused radiation are presented. Specific configurations of the sources were assigned to various applications.

  12. Fullwaveform inversion for structure and source parameters using regional data recorded in eastern Kazakhstan. Final report, 1 September 1990-1 September 1992

    SciTech Connect

    Harvey, D.J.

    1993-04-01

    We have completed a study which was aimed at obtaining fundamental understanding of regional wave propagation by attempting to match synthetic seismograms with real data. The first part of this study involved the identification and analysis of a set of local and regional seismic events recorded near the former Soviet test site at Semipalatinsk. We then applied full waveform inversion in the 0.5 to 1 Hertz frequency band to selected events to extract source and structure parameters. We found that for certain source-receiver paths we could do an excellent job of matching complete seismograms on radial and vertical components up to a frequency of one Hertz including P, S and Rg phases using shallow explosion sources. For other source-receiver paths the fits were not so good using shallow explosion sources, however we obtained good fits on all three components by assuming a 5 km deep earth source. These results indicate that waveform inversion can be used to discriminate small shallow explosions from small relatively shallow earthquakes and that structural effects can be accurately modeled in this region up to a frequency of 1 Hertz.... Regional events, Source discrimination, Waveform inversion, Waveform modeling.

  13. Constraints on Source Parameters on Deep Moonquakes and Lunar Interior Structure

    NASA Astrophysics Data System (ADS)

    Yamada, R.; Araki, H.; Noda, H.; Matsumoto, K.

    2014-12-01

    The NASA Apollo mission realized the first and only seismic network on the Moon consisting of 4 seismic stations (Apollo 12, 14, 15 and 16). The seismic recording obtained by the network revealed that the most active lunar seismic events occurred in the lunar deep region at about 700 to 1200 km depth, which are called as deep moonquakes (e.g., Nakamura, 2005). The deep moonquakes repeatedly occur at the identical source with lunar tidal period depending on the relative positions of the Moon, the Earth and the Sun (e.g., Lammlein, 1977). On the other hand, the occurrence mechanism of the deep moonquakes is still unclear because we do not yet understand the source parameters such as focal mechanism, seismic moment and source spectrum. Yamada et al. (2013) analyzed the seismic data from Apollo 12 station to derive seismic moment distribution for active 15 deep moonquakes and showed that the seismic moments were different source by source. However, we found that the amplitudes of deep moonquakes observed at Apollo 15 and 16 stations cannot be well explained by our seismic moment distribution derived from the Apollo 12 data (Yamada et al., 2014). The higher seismic quality factors of S-wave are required to explain attenuation of amplitude of the deep moonquakes. This discrepancy may be also due to assumption of constant radiation pattern (strike dip, slip) in our previous studies. The amplitude of seismic event is determined from seismic moment, radiation pattern and lunar interior structure through which the seismic rays pass. Nakamura (1978) indicated that the radiation pattern varies with time by analyzing of the ratio of amplitudes of the same deep event observed at two stations. In this study, we investigate possible radiation pattern and seismic quality factor and seismic moments so as to explain the amplitude ratios of the same deep event observed at three stations (Apollo12, 15 and 16) and absolute amplitude of the deep events at each station using Markov

  14. Effect of Zinc Source on Hematological, Metabolic Parameters and Mineral Balance in Lambs.

    PubMed

    Aliarabi, Hassan; Fadayifar, Amir; Tabatabaei, Mohammad Mehdi; Zamani, Pouya; Bahari, Aliasghar; Farahavar, Abbas; Dezfoulian, Amir Hossein

    2015-11-01

    This experiment was conducted to study the effects of different sources of zinc (Zn) on blood metabolites and balances of some minerals in lambs. In the first part, 20 6-7-month-old lambs were randomly allotted to four treatments including (1) basal diet containing 22.47 mg Zn/kg DM without supplementary Zn (control), (2) basal diet + 40 mg Zn/kg DM as ZnSO4 (ZnSO4 40), (3) basal diet + 20 mg Zn/kg DM as Zn-proteinate (Zn-Pro 20), and (4) basal diet + 40 mg Zn/kg DM as Zn-proteinate (Zn-Pro 40). Blood samples were taken on days 0, 28, and 65 before morning feeding. In the second part, four lambs from each treatment were randomly transferred to metabolic cages to evaluate the effects of different sources of Zn on N, Zn, Fe, and Cu retentions. This trial consisted of 18 days, with the first 12 days as the adaptation period followed by 6 days of sample collection. The results of this study showed that the source of Zinc had no significant effect on the analyzed parameters. Average daily gain and feed efficiency were improved by Zn supplementation (P < 0.05). Daily feed intake, plasma glucose, Fe and Cu concentrations, serum total antioxidant capacity, red blood cell count, packed cell volume, and hemoglobin concentration did not differ significantly between treatments (P > 0.05). Plasma Zn concentration, alkaline phosphatase (ALP) and bone-specific alkaline phosphatase (BALP) activity, and white blood cell and lymphocyte count differed significantly between control and Zn-supplemented groups (P < 0.05) as Zn supplementation improved these parameters. Nitrogen, Fe, and Cu retentions did not differ between treatments (P > 0.05). Zinc retention showed a significant difference between control and Zn-supplemented groups (P < 0.05), but there were no significant differences among the Zn-supplemented groups. The results of this study show that Zn supplementation improved performance and zinc retention in lambs. However, there were no significant

  15. Effect of Zinc Source on Hematological, Metabolic Parameters and Mineral Balance in Lambs.

    PubMed

    Aliarabi, Hassan; Fadayifar, Amir; Tabatabaei, Mohammad Mehdi; Zamani, Pouya; Bahari, Aliasghar; Farahavar, Abbas; Dezfoulian, Amir Hossein

    2015-11-01

    This experiment was conducted to study the effects of different sources of zinc (Zn) on blood metabolites and balances of some minerals in lambs. In the first part, 20 6-7-month-old lambs were randomly allotted to four treatments including (1) basal diet containing 22.47 mg Zn/kg DM without supplementary Zn (control), (2) basal diet + 40 mg Zn/kg DM as ZnSO4 (ZnSO4 40), (3) basal diet + 20 mg Zn/kg DM as Zn-proteinate (Zn-Pro 20), and (4) basal diet + 40 mg Zn/kg DM as Zn-proteinate (Zn-Pro 40). Blood samples were taken on days 0, 28, and 65 before morning feeding. In the second part, four lambs from each treatment were randomly transferred to metabolic cages to evaluate the effects of different sources of Zn on N, Zn, Fe, and Cu retentions. This trial consisted of 18 days, with the first 12 days as the adaptation period followed by 6 days of sample collection. The results of this study showed that the source of Zinc had no significant effect on the analyzed parameters. Average daily gain and feed efficiency were improved by Zn supplementation (P < 0.05). Daily feed intake, plasma glucose, Fe and Cu concentrations, serum total antioxidant capacity, red blood cell count, packed cell volume, and hemoglobin concentration did not differ significantly between treatments (P > 0.05). Plasma Zn concentration, alkaline phosphatase (ALP) and bone-specific alkaline phosphatase (BALP) activity, and white blood cell and lymphocyte count differed significantly between control and Zn-supplemented groups (P < 0.05) as Zn supplementation improved these parameters. Nitrogen, Fe, and Cu retentions did not differ between treatments (P > 0.05). Zinc retention showed a significant difference between control and Zn-supplemented groups (P < 0.05), but there were no significant differences among the Zn-supplemented groups. The results of this study show that Zn supplementation improved performance and zinc retention in lambs. However, there were no significant

  16. SIMPEG: An open source framework for simulation and gradient based parameter estimation in geophysical applications

    NASA Astrophysics Data System (ADS)

    Cockett, Rowan; Kang, Seogi; Heagy, Lindsey J.; Pidlisecky, Adam; Oldenburg, Douglas W.

    2015-12-01

    Inverse modeling is a powerful tool for extracting information about the subsurface from geophysical data. Geophysical inverse problems are inherently multidisciplinary, requiring elements from the relevant physics, numerical simulation, and optimization, as well as knowledge of the geologic setting, and a comprehension of the interplay between all of these elements. The development and advancement of inversion methodologies can be enabled by a framework that supports experimentation, is flexible and extensible, and allows the knowledge generated to be captured and shared. The goal of this paper is to propose a framework that supports many different types of geophysical forward simulations and deterministic inverse problems. Additionally, we provide an open source implementation of this framework in Python called SIMPEG (Simulation and Parameter Estimation in Geophysics,

  17. Static Source Parameters of the West Bohemia/Vogtland Earthquake Swarms

    NASA Astrophysics Data System (ADS)

    Michalek, J.; Cermakova, H.; Horalek, J.; Fischer, T.

    2011-12-01

    The static source parameters like seismic moment, stress drop and size of the fault plane are important quantities in assessing the earthquake effects. The static stress drop is commonly accepted to be almost constant but recent studies show that this is not valid in many cases. Thus the confirmation of the validity of scaling laws in the case of small earthquakes can significantly contribute to the assessment of the seismic potential of a particular fault zone. One of the areas with such small intraplate earthquakes is the West Bohemia/Vogtland region in the Central Europe where earthquake swarms occur. The area is continuously monitored since 1990 by WEBNET seismic network which nowadays consists of 13 permanent stations and similar amount of temporary stations. The main instrumentally recorded swarms occurred in 1997 (ML<=3.0), 2000 (ML<=3.2) and 2008 (ML<=3.8). In our study we focused on the swarms 2000 and 2008 for which the similarity analysis using the cross-correlation method was done and earthquakes were classified into multiplets. We applied the spectral ratios method to event pairs inside multiplets to evaluate corner frequencies of inividual earthquakes. Using the absolute moment tensors of specific earthquakes which are known from previous studies and assumption of reasonable rupture propagation velocity (3 km/s) we can figure out the stress drop distribution over the range 1e13 to 2e15 Nm of seismic moment (0.0<=ML<=3.5). To get reliable source parameters the propagation and attenuation effects should be eliminated what can not be sufficiently done using the single event spectral analysis. Comparison of results using both techniques - spectral ratios and single event spectral analysis - shows the advantages and drawbacks.

  18. Efficient moment-based inference of admixture parameters and sources of gene flow.

    PubMed

    Lipson, Mark; Loh, Po-Ru; Levin, Alex; Reich, David; Patterson, Nick; Berger, Bonnie

    2013-08-01

    The recent explosion in available genetic data has led to significant advances in understanding the demographic histories of and relationships among human populations. It is still a challenge, however, to infer reliable parameter values for complicated models involving many populations. Here, we present MixMapper, an efficient, interactive method for constructing phylogenetic trees including admixture events using single nucleotide polymorphism (SNP) genotype data. MixMapper implements a novel two-phase approach to admixture inference using moment statistics, first building an unadmixed scaffold tree and then adding admixed populations by solving systems of equations that express allele frequency divergences in terms of mixture parameters. Importantly, all features of the model, including topology, sources of gene flow, branch lengths, and mixture proportions, are optimized automatically from the data and include estimates of statistical uncertainty. MixMapper also uses a new method to express branch lengths in easily interpretable drift units. We apply MixMapper to recently published data for Human Genome Diversity Cell Line Panel individuals genotyped on a SNP array designed especially for use in population genetics studies, obtaining confident results for 30 populations, 20 of them admixed. Notably, we confirm a signal of ancient admixture in European populations-including previously undetected admixture in Sardinians and Basques-involving a proportion of 20-40% ancient northern Eurasian ancestry. PMID:23709261

  19. Efficient moment-based inference of admixture parameters and sources of gene flow.

    PubMed

    Lipson, Mark; Loh, Po-Ru; Levin, Alex; Reich, David; Patterson, Nick; Berger, Bonnie

    2013-08-01

    The recent explosion in available genetic data has led to significant advances in understanding the demographic histories of and relationships among human populations. It is still a challenge, however, to infer reliable parameter values for complicated models involving many populations. Here, we present MixMapper, an efficient, interactive method for constructing phylogenetic trees including admixture events using single nucleotide polymorphism (SNP) genotype data. MixMapper implements a novel two-phase approach to admixture inference using moment statistics, first building an unadmixed scaffold tree and then adding admixed populations by solving systems of equations that express allele frequency divergences in terms of mixture parameters. Importantly, all features of the model, including topology, sources of gene flow, branch lengths, and mixture proportions, are optimized automatically from the data and include estimates of statistical uncertainty. MixMapper also uses a new method to express branch lengths in easily interpretable drift units. We apply MixMapper to recently published data for Human Genome Diversity Cell Line Panel individuals genotyped on a SNP array designed especially for use in population genetics studies, obtaining confident results for 30 populations, 20 of them admixed. Notably, we confirm a signal of ancient admixture in European populations-including previously undetected admixture in Sardinians and Basques-involving a proportion of 20-40% ancient northern Eurasian ancestry.

  20. Computation of probabilistic hazard maps and source parameter estimation for volcanic ash transport and dispersion

    SciTech Connect

    Madankan, R.; Pouget, S.; Singla, P.; Bursik, M.; Dehn, J.; Jones, M.; Patra, A.; Pavolonis, M.; Pitman, E.B.; Singh, T.; Webley, P.

    2014-08-15

    Volcanic ash advisory centers are charged with forecasting the movement of volcanic ash plumes, for aviation, health and safety preparation. Deterministic mathematical equations model the advection and dispersion of these plumes. However initial plume conditions – height, profile of particle location, volcanic vent parameters – are known only approximately at best, and other features of the governing system such as the windfield are stochastic. These uncertainties make forecasting plume motion difficult. As a result of these uncertainties, ash advisories based on a deterministic approach tend to be conservative, and many times over/under estimate the extent of a plume. This paper presents an end-to-end framework for generating a probabilistic approach to ash plume forecasting. This framework uses an ensemble of solutions, guided by Conjugate Unscented Transform (CUT) method for evaluating expectation integrals. This ensemble is used to construct a polynomial chaos expansion that can be sampled cheaply, to provide a probabilistic model forecast. The CUT method is then combined with a minimum variance condition, to provide a full posterior pdf of the uncertain source parameters, based on observed satellite imagery. The April 2010 eruption of the Eyjafjallajökull volcano in Iceland is employed as a test example. The puff advection/dispersion model is used to hindcast the motion of the ash plume through time, concentrating on the period 14–16 April 2010. Variability in the height and particle loading of that eruption is introduced through a volcano column model called bent. Output uncertainty due to the assumed uncertain input parameter probability distributions, and a probabilistic spatial-temporal estimate of ash presence are computed.

  1. Disentangling the eruption source parameters that control the climate effects of volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Marshall, Lauren; Schmidt, Anja; Mann, Graham; Carslaw, Kenneth; Dhomse, Sandip; Haywood, Jim; Jones, Andy

    2016-04-01

    Climatic cooling in the 1-2 years following a major volcanic eruption does not scale linearly with the mass of SO2 injected into the atmosphere. The injection height of the emissions, the latitude of the volcano, the season and large scale atmospheric circulations, also influence the climatic response. Complex couplings exist between stratospheric chemistry and circulations, and aerosol induced heating and aerosol microphysical processes such as condensation and evaporation. As yet, there has been no systematic assessment of these relationships when considering different eruption source parameters. A series of simulations with a global composition-climate model with interactive stratospheric chemistry and aerosol microphysics are conducted, in which the eruption latitude and injection height are varied. Parameter combinations are chosen such that injections sample areas in the atmosphere where different chemical and dynamical influences are important (e.g. tropical vs. high latitude eruptions, injections near the tropopause vs. injections in the upper stratosphere). Each experiment is repeated for varying SO2 injection magnitudes. We focus on the analysis of aerosol properties such as the stratospheric aerosol optical depth, effective radius and heating rates, and resultant perturbations to radiative fluxes. Initial results demonstrate the non-linearity in the climatic response as the injection magnitude is increased. Future work will focus on disentangling the contribution of each parameter to the climatic response with additional simulations to investigate the effect of season and the Quasi Biennial Oscillation. Results will aid in the understanding of the impact of past, present and future volcanic eruptions. By analysing sulfate deposition to the polar ice caps, we will assess the uncertainty in, and validity of, the historic volcanic radiative forcing deduced from ice cores.

  2. Inversion of Source Parameters for Moderate Earthquakes Using Short-Period Teleseismic P Waves

    NASA Astrophysics Data System (ADS)

    Chu, Risheng; Ni, Sidao; Pitarka, Arben; Helmberger, Don V.

    2014-07-01

    In this paper, we introduce a new method for estimating the source parameters of moderate earthquakes ( M w ~5.0) by modeling short-period teleseismic waveforms. This method uses a grid-search algorithm to minimize misfits between observed data and synthetic seismograms in depth, magnitude, and mechanism domain in a relative high-frequency range of 0.8-2.0 Hz, similar to the traditional cut-and-paste method used in regional modeling ( Zhu and Helmberger, Bull Sesimol Soc Am 86:1634-1641, 1996). In this frequency range, a significant challenge is determining the initial P-wave polarity because of a low signal-to-noise ratio (SNR). Therefore we first determine source properties for a master earthquake with a relative strong SNR. Both the travel time and amplitude corrections are developed relative to the reference 1D model along each path used in inverting the master event. We then applied these corrections to other earthquakes clustered in the same area to constrain the initial P polarities. Thus the focal mechanisms can be determined reasonably well. We inverted focal mechanisms for a small set of events beneath Qeshm Island in southern Iran and demonstrate the importance of radiation pattern at short periods.

  3. Attenuation, source parameters and site effects of SH waves in Taiwan

    NASA Astrophysics Data System (ADS)

    Chang, Shun-Chiang; Wen, Kuo-Liang

    2016-04-01

    Generalized inversion technique (GIT) (Castro et al., 1990) was used to derive SH-wave in the frequency range 0.2-25 Hz (interval 0.1 Hz). The inversion results can find attenuation characteristics, earthquake source parameters and site amplification functions. The characteristics of the site amplification are referred to horizontal-to-vertical (H/V) Fourier spectral ratios of microtremor for a referent rock site. The SH-wave from 28 earthquakes with magnitude ranging from ML 5 to 7, of 1319 earthquake records at 146 TSMIP strong motion stations in Jianan Plain, southwestern Taiwan are used in this analysis. The SH-wave quality factor Q(f) is estimated as 52.83f0.77 for 0.2<= f < =25 Hz. The stress drops can be found from source spectra by using the omega-square model. The results of site amplification are similar to horizontal-to-vertical spectral ratio of the microtremor which have clearly and similar predominant peaks.

  4. Robust contrast source inversion method with automatic choice rule of regularization parameters for ultrasound waveform tomography

    NASA Astrophysics Data System (ADS)

    Lin, Hongxiang; Azuma, Takashi; Qu, Xiaolei; Takagi, Shu

    2016-07-01

    We consider ultrasound waveform tomography using an ultrasound prototype equipped with the ring-array transducers. For this purpose, we use robust contrast source inversion (robust CSI), viz extended contrast source inversion, to reconstruct the sound-speed image from the wave-field data. The robust CSI method is implemented by the alternating minimization method. An automatic choice rule is employed into the alternating minimization method in order to heuristically determine a suitable regularization parameter while iterating. We prove the convergence of this algorithm. The numerical examples show that the robust CSI method with the automatic choice rule improves the spatial resolution of medical images and enhances the robustness, even when the wave-field data of a wavelength of 6.16 mm contaminated by 5% noise are used. The numerical results also show that the images reconstructed by the proposed method yield a spatial resolution of approximately half the wavelength that may be adequate for imaging a breast tumor at Stage I.

  5. Source parameters of the Sarez-Pamir earthquake of 1911 February 18

    NASA Astrophysics Data System (ADS)

    Kulikova, Galina; Schurr, Bernd; Krüger, Frank; Brzoska, Elisabeth; Heimann, Sebastian

    2016-05-01

    The Ms ˜ 7.7 Sarez-Pamir earthquake of 1911 February 18 is the largest instrumentally recorded earthquake in the Pamir region. It triggered one of the largest landslides of the past century, building a giant natural dam and forming Lake Sarez. As for many strong earthquakes from that time, information about source parameters of the Sarez-Pamir earthquake is limited due to the sparse observations. Here, we present the analysis of analogue seismic records of the Sarez-Pamir earthquake. We have collected, scanned and digitized 26 seismic records from 13 stations worldwide to relocate the epicentre and determine the event's depth (˜26 km) and magnitude (mB7.3 and Ms7.7). The unusually good quality of the digitized waveforms allowed their modelling, revealing an NE-striking sinistral strike-slip focal mechanism in accordance with regional tectonics. The shallow depth and magnitude (Mw7.3) of the earthquake were confirmed. Additionally, we investigated the possible contribution of the landslide to the waveforms and present an alternative source model assuming the landslide and earthquake occurred in close sequence.

  6. Estimation of source parameters and scaling relations for moderate size earthquakes in North-West Himalaya

    NASA Astrophysics Data System (ADS)

    Kumar, Vikas; Kumar, Dinesh; Chopra, Sumer

    2016-10-01

    The scaling relation and self similarity of earthquake process have been investigated by estimating the source parameters of 34 moderate size earthquakes (mb 3.4-5.8) occurred in the NW Himalaya. The spectral analysis of body waves of 217 accelerograms recorded at 48 sites have been carried out using in the present analysis. The Brune's ω-2 model has been adopted for this purpose. The average ratio of the P-wave corner frequency, fc(P), to the S-wave corner frequency, fc(S), has been found to be 1.39 with fc(P) > fc(S) for 90% of the events analyzed here. This implies the shift in the corner frequency in agreement with many other similar studies done for different regions. The static stress drop values for all the events analyzed here lie in the range 10-100 bars average stress drop value of the order of 43 ± 19 bars for the region. This suggests the likely estimate of the dynamic stress drop, which is 2-3 times the static stress drop, is in the range of about 80-120 bars. This suggests the relatively high seismic hazard in the NW Himalaya as high frequency strong ground motions are governed by the stress drop. The estimated values of stress drop do not show significant variation with seismic moment for the range 5 × 1014-2 × 1017 N m. This observation along with the cube root scaling of corner frequencies suggests the self similarity of the moderate size earthquakes in the region. The scaling relation between seismic moment and corner frequency Mo fc3 = 3.47 ×1016Nm /s3 estimated in the present study can be utilized to estimate the source dimension given the seismic moment of the earthquake for the hazard assessment. The present study puts the constrains on the important parameters stress drop and source dimension required for the synthesis of strong ground motion from the future expected earthquakes in the region. Therefore, the present study is useful for the seismic hazard and risk related studies for NW Himalaya.

  7. Source parameters and rupture velocities of microearthquakes in western Nagano, Japan, determined using stopping phases

    USGS Publications Warehouse

    Imanishi, K.; Takeo, M.; Ellsworth, W.L.; Ito, H.; Matsuzawa, T.; Kuwahara, Y.; Iio, Y.; Horiuchi, S.; Ohmi, S.

    2004-01-01

    We use an inversion method based on stopping phases (Imanishi and Takeo, 2002) to estimate the source dimension, ellipticity, and rupture velocity of microearthquakes and investigate the scaling relationships between source parameters. We studied 25 earthquakes, ranging in size from M 1.3 to M 2.7, that occurred between May and August 1999 at the western Nagano prefecture, Japan, which is characterized by a high rate of shallow earthquakes. The data consist of seismograms recorded in an 800-m borehole and at 46 surface and 2 shallow borehole seismic stations whose spacing is a few kilometers. These data were recorded with a sampling frequency of 10 kHz. In particular, the 800-m-borehole data provide a wide frequency bandwidth with greatly reduced ground noise and coda wave amplitudes compared with surface recordings. High-frequency stopping phases appear in the body waves in Hilbert transform pairs and are readily detected on seismograms recorded in the 800-m borehole. After correcting both borehole and surface data for attenuation, we also measure the rise time, which is defined as the interval from the arrival time of the direct wave to the timing of the maximum amplitude in the displacement pulse. The differential time of the stopping phases and the rise times were used to obtain source parameters. We found that several microearthquakes propagated unilaterally, suggesting that all microearthquakes cannot be modeled as a simple circular crack model. Static stress drops range from approximately 0.1 to 2 MPa and do not vary with seismic moment. It seems that the breakdown in stress drop scaling seen in previous studies using surface data is simply an artifact of attenuation in the crust. The average value of rupture velocity does not depend on earthquake size and is similar to those reported for moderate and large earthquakes. It is likely that earthquakes are self-similar over a wide range of earthquake size and that the dynamics of small and large earthquakes are

  8. Determination of earthquake source parameters from waveform data for studies of global and regional seismicity

    NASA Astrophysics Data System (ADS)

    Dziewonski, A. M.; Chou, T.-A.; Woodhouse, J. H.

    1981-04-01

    It is possible to use the waveform data not only to derive the source mechanism of an earthquake but also to establish the hypocentral coordinates of the `best point source' (the centroid of the stress glut density) at a given frequency. Thus two classical problems of seismology are combined into a single procedure. Given an estimate of the origin time, epicentral coordinates and depth, an initial moment tensor is derived using one of the variations of the method described in detail by Gilbert and Dziewonski (1975). This set of parameters represents the starting values for an iterative procedure in which perturbations to the elements of the moment tensor are found simultaneously with changes in the hypocentral parameters. In general, the method is stable, and convergence rapid. Although the approach is a general one, we present it here in the context of the analysis of long-period body wave data recorded by the instruments of the SRO and ASRO digital network. It appears that the upper magnitude limit of earthquakes that can be processed using this particular approach is between 7.5 and 8.0; the lower limit is, at this time, approximately 5.5, but it could be extended by broadening the passband of the analysis to include energy with periods shorter that 45 s. As there are hundreds of earthquakes each year with magnitudes exceeding 5.5, the seismic source mechanism can now be studied in detail not only for major events but also, for example, for aftershock series. We have investigated the foreshock and several aftershocks of the Sumba earthquake of August 19, 1977; the results show temporal variation of the stress regime in the fault area of the main shock. An area some 150 km to the northwest of the epicenter of the main event became seismically active 49 days later. The sense of the strike-slip mechanism of these events is consistent with the relaxation of the compressive stress in the plate north of the Java trench. Another geophysically interesting result of our

  9. Determination of earthquake source parameters from waveform data for studies of global and regional seismicity

    SciTech Connect

    Dziewonski, A.M.; Chou, T.A.; Woodhouse, J.H.

    1981-04-10

    It is possible to use the waveform data not only to derive the source mechanism of an earthquake but also to establish the hypocentral coordinates of the 'best point source' (the centroid of the stress glut density) at a given frequency. Thus two classical problems of seismology are combined into a single procedure. Given as estimate of the origin time, epicentral coordinates and depth, an initial moment tensor is derived using one of the variations of the method described in detail by Gibert and Dziewonski (1975). This set of parameters represents the starting values for an iterative procedure in which perturbations to the elements of the moment tensor are found simultaneously with changes in the hypocentral parameters. In general, the method is stable, and convergence rapid. Although the approach is a general one, we present it here in the context of the analysis of long-period body wave data recorded by the instruments of the sro and asro digital network. It appears that the upper magnitude limit of earthquakes that can be processed using this particular approach is between 7.5 and 8.0; the lower limit is, at this time, approximately 5.5, but it could be extended by broadening the passband of the analysis to include energy with periods shorter than 45 s. As there are hundreds of earthquakes each year with magnitudes exceeding 5.5, the seismic source mechanism can now be studied in detail not only for major events but also, for example, for aftershock series. We have investigated the foreshock and several aftershocks of the Sumba earthquake of August 19, 1977; the results show temporal variation of the stress regime in the fault area of the main shock. An area some 150 km to the northwest of the epicenter of the main event became seismically active 49 days later. The sense of the strike-slip mechanism of these events is consistent with the relaxation of the compressive stress in the plate north of the Java trench.

  10. Massively parallel sequencing of the mouse exome to accurately identify rare, induced mutations: an immediate source for thousands of new mouse models.

    PubMed

    Andrews, T D; Whittle, B; Field, M A; Balakishnan, B; Zhang, Y; Shao, Y; Cho, V; Kirk, M; Singh, M; Xia, Y; Hager, J; Winslade, S; Sjollema, G; Beutler, B; Enders, A; Goodnow, C C

    2012-05-01

    Accurate identification of sparse heterozygous single-nucleotide variants (SNVs) is a critical challenge for identifying the causative mutations in mouse genetic screens, human genetic diseases and cancer. When seeking to identify causal DNA variants that occur at such low rates, they are overwhelmed by false-positive calls that arise from a range of technical and biological sources. We describe a strategy using whole-exome capture, massively parallel DNA sequencing and computational analysis, which identifies with a low false-positive rate the majority of heterozygous and homozygous SNVs arising de novo with a frequency of one nucleotide substitution per megabase in progeny of N-ethyl-N-nitrosourea (ENU)-mutated C57BL/6j mice. We found that by applying a strategy of filtering raw SNV calls against known and platform-specific variants we could call true SNVs with a false-positive rate of 19.4 per cent and an estimated false-negative rate of 21.3 per cent. These error rates are small enough to enable calling a causative mutation from both homozygous and heterozygous candidate mutation lists with little or no further experimental validation. The efficacy of this approach is demonstrated by identifying the causative mutation in the Ptprc gene in a lymphocyte-deficient strain and in 11 other strains with immune disorders or obesity, without the need for meiotic mapping. Exome sequencing of first-generation mutant mice revealed hundreds of unphenotyped protein-changing mutations, 52 per cent of which are predicted to be deleterious, which now become available for breeding and experimental analysis. We show that exome sequencing data alone are sufficient to identify induced mutations. This approach transforms genetic screens in mice, establishes a general strategy for analysing rare DNA variants and opens up a large new source for experimental models of human disease.

  11. Statistical variations of source parameters in inter- and intraplate earthquakes in Chile and their correlations with the slab properties.

    NASA Astrophysics Data System (ADS)

    Derode, B.

    2015-12-01

    Understanding the rupture processes of intermediate-depth earthquakes in active subduction zones and their dependence to inherited geophysical parameters, such as the maturity and orientation of pre-existing faults, is still of prime interest. Unfortunately, quantitative values describing the nucleation and propagation processes at depths are rare, and the earthquake source parameters determined from global databases or far-field measurements are often very heterogeneous, especially for the smallest and deepest earthquakes. In order to leveling this problem and discriminate specific characteristics of the intermediate-depth earthquakes in Chile (IDEQ-Chile), we conducted high precision measurements using local and regional waveforms data obtained from broadband and strong-motions stations of IPOC network in northern Chile. A strict and rigorous methodology was used to reduce the scattering of the source parameter estimation usually observed. With this high-quality database, we examined the source characteristics of a few hundreds of intra-slab intermediate depth-earthquakes, with depth varying from 40 km to 300 km. For the effective comparison of the source parameters, we studied with the same approach a hundred of interplate earthquakes located along the same latitude-dependent zone of the subducted slab. Based on static and cinematic considerations, we compared these source parameters with macroscopic geophysical parameters such as the stress regime, the coupling degree or the style of faulting, in order to show the possible correlations between them. Interestingly, we observed three major depth-dependent zones corresponding to three different sets of static and dynamic source parameters. We show that there are some evident differences between these distinct Chilean zones, although the apparent quasi-constant velocity and age of the subducted Nazca plate along Chile. We discuss how some of the various proposed sources mechanisms, explaining the earthquakes

  12. Estimation Source Parameters of Large-Scale Chemical Surface Explosions and Recent Underground Nuclear Tests

    NASA Astrophysics Data System (ADS)

    Gitterman, Y.; Kim, S.; Hofstetter, R.

    2013-12-01

    Large-scale surface explosions were conducted by the Geophysical Institute of Israel at Sayarim Military Range (SMR), Negev desert: 82 tons of strong HE explosives in August 2009, and 10&100 tons of ANFO explosives in January 2011. The main goal was to provide strong controlled sources in different wind conditions, for calibration of IMS infrasound stations. Numerous dense observations of blast waves were provided by high-pressure, acoustic and seismic sensors at near-source (< 1 km) and close local (1-40 km) distances. The rarely reported Secondary Shock (SS) phenomenon was clearly observed at the all sensors. A novel empirical relationship for the new air-blast parameter - SS time delay - versus distance (both scaled by the cubic root of estimated TNT equivalent charge) was developed and analyzed. The scaled SS delays were found clearly separated for 2009 and 2011 shots, thus demonstrating dependence on the type of explosives with different detonation velocity. Additional acoustic and seismic records from very large (> 2000 tons) ANFO surface shots at White Sands Military Range (WSMR) were analyzed for SS time delay. The Secondary Shocks were revealed on the records in the range 1.5-60 km and showed consistency with the SMR data, thus extending the charge and distance range for the developed SS delay relationship. Obtained results suggest that measured SS delays can provide important information about an explosion source character, and can be used as a new simple cost-effective yield estimator for explosions with known type of explosives. The new results are compared with analogous available data of surface nuclear explosions. Special distinctions in air-blast waves are revealed and analyzed, resulting from the different source phenomenology (energy release). Two underground nuclear explosions conducted by North Korea in 2009 and 2013 were recorded by several stations of Israel Seismic Network. Pronounced minima (spectral nulls) at 1.2-1.3 Hz were revealed in the

  13. Source parameters of the 2008 Bukavu-Cyangugu earthquake estimated from InSAR and teleseismic data

    NASA Astrophysics Data System (ADS)

    D'Oreye, Nicolas; González, Pablo J.; Shuler, Ashley; Oth, Adrien; Bagalwa, Louis; Ekström, Göran; Kavotha, Déogratias; Kervyn, François; Lucas, Celia; Lukaya, François; Osodundu, Etoy; Wauthier, Christelle; Fernández, José

    2011-02-01

    Earthquake source parameter determination is of great importance for hazard assessment, as well as for a variety of scientific studies concerning regional stress and strain release and volcano-tectonic interaction. This is especially true for poorly instrumented, densely populated regions such as encountered in Africa, where even the distribution of seismicity remains poorly documented. In this paper, we combine data from satellite radar interferometry (InSAR) and teleseismic waveforms to determine the source parameters of the Mw 5.9 earthquake that occurred on 2008 February 3 near the cities of Bukavu (DR Congo) and Cyangugu (Rwanda). This was the second largest earthquake ever to be recorded in the Kivu basin, a section of the western branch of the East African Rift (EAR). This earthquake is of particular interest due to its shallow depth and proximity to active volcanoes and Lake Kivu, which contains high concentrations of dissolved carbon dioxide and methane. The shallow depth and possible similarity with dyking events recognized in other parts of EAR suggested the potential association of the earthquake with a magmatic intrusion, emphasizing the necessity of accurate source parameter determination. In general, we find that estimates of fault plane geometry, depth and scalar moment are highly consistent between teleseismic and InSAR studies. Centroid-moment-tensor (CMT) solutions locate the earthquake near the southern part of Lake Kivu, while InSAR studies place it under the lake itself. CMT solutions characterize the event as a nearly pure double-couple, normal faulting earthquake occurring on a fault plane striking 350° and dipping 52° east, with a rake of -101°. This is consistent with locally mapped faults, as well as InSAR data, which place the earthquake on a fault striking 355° and dipping 55° east, with a rake of -98°. The depth of the earthquake was constrained by a joint analysis of teleseismic P and SH waves and the CMT data set, showing that

  14. The Araucaria Project: accurate stellar parameters and distance to evolved eclipsing binary ASAS J180057-2333.8 in Sagittarius Arm

    NASA Astrophysics Data System (ADS)

    Suchomska, K.; Graczyk, D.; Smolec, R.; Pietrzyński, G.; Gieren, W.; Stȩpień, K.; Konorski, P.; Pilecki, B.; Villanova, S.; Thompson, I. B.; Górski, M.; Karczmarek, P.; Wielgórski, P.; Anderson, R. I.

    2015-07-01

    We have analyzed the double-lined eclipsing binary system ASAS J180057-2333.8 from the All Sky Automated Survey (ASAS) catalogue. We measure absolute physical and orbital parameters for this system based on archival V-band and I-band ASAS photometry, as well as on high-resolution spectroscopic data obtained with ESO 3.6 m/HARPS and CORALIE spectrographs. The physical and orbital parameters of the system were derived with an accuracy of about 0.5-3 per cent. The system is a very rare configuration of two bright well-detached giants of spectral types K1 and K4 and luminosity class II. The radii of the stars are R1 = 52.12 ± 1.38 and R2 = 67.63 ± 1.40 R⊙ and their masses are M1 = 4.914 ± 0.021 and M2 = 4.875 ± 0.021 M⊙. The exquisite accuracy of 0.5 per cent obtained for the masses of the components is one of the best mass determinations for giants. We derived a precise distance to the system of 2.14 ± 0.06 kpc (stat.) ± 0.05 (syst.) which places the star in the Sagittarius-Carina arm. The Galactic rotational velocity of the star is Θs = 258 ± 26 km s-1 assuming Θ0 = 238 km s-1. A comparison with PARSEC isochrones places the system at the early phase of core helium burning with an age of slightly larger than 100 million years. The effect of overshooting on stellar evolutionary tracks was explored using the MESA star code.

  15. Is scoring system of computed tomography based metric parameters can accurately predicts shock wave lithotripsy stone-free rates and aid in the development of treatment strategies?

    PubMed Central

    Badran, Yasser Ali; Abdelaziz, Alsayed Saad; Shehab, Mohamed Ahmed; Mohamed, Hazem Abdelsabour Dief; Emara, Absel-Aziz Ali; Elnabtity, Ali Mohamed Ali; Ghanem, Maged Mohammed; ELHelaly, Hesham Abdel Azim

    2016-01-01

    Objective: The objective was to determine the predicting success of shock wave lithotripsy (SWL) using a combination of computed tomography based metric parameters to improve the treatment plan. Patients and Methods: Consecutive 180 patients with symptomatic upper urinary tract calculi 20 mm or less were enrolled in our study underwent extracorporeal SWL were divided into two main groups, according to the stone size, Group A (92 patients with stone ≤10 mm) and Group B (88 patients with stone >10 mm). Both groups were evaluated, according to the skin to stone distance (SSD) and Hounsfield units (≤500, 500–1000 and >1000 HU). Results: Both groups were comparable in baseline data and stone characteristics. About 92.3% of Group A rendered stone-free, whereas 77.2% were stone-free in Group B (P = 0.001). Furthermore, in both group SWL success rates was a significantly higher for stones with lower attenuation <830 HU than with stones >830 HU (P < 0.034). SSD were statistically differences in SWL outcome (P < 0.02). Simultaneous consideration of three parameters stone size, stone attenuation value, and SSD; we found that stone-free rate (SFR) was 100% for stone attenuation value <830 HU for stone <10 mm or >10 mm but total number SWL sessions and shock waves required for the larger stone group were higher than in the smaller group (P < 0.01). Furthermore, SFR was 83.3% and 37.5% for stone <10 mm, mean HU >830, SSD 90 mm and SSD >120 mm, respectively. On the other hand, SFR was 52.6% and 28.57% for stone >10 mm, mean HU >830, SSD <90 mm and SSD >120 mm, respectively. Conclusion: Stone size, stone density (HU), and SSD is simple to calculate and can be reported by radiologists to applying combined score help to augment predictive power of SWL, reduce cost, and improving of treatment strategies. PMID:27141192

  16. Source Parameters of the Upper-Mantle September 21, 2013 Mw4.8 Wyoming Earthquake

    NASA Astrophysics Data System (ADS)

    Froment, B.; Prieto, G. A.; Abercrombie, R. E.

    2014-12-01

    On September 21, 2013, a Mw4.8 earthquake occurred at more than 70 km deep in the Wind River Range (western Wyoming). Moment tensor inversions show dominant strike-slip faulting with a small reverse component, with nodal planes striking nearly ENE and NW. While intermediate-depth earthquakes are common in a subduction context, there have been very few upper-mantle intraplate events. The 2012 Mw8.6 off-shore Sumatra event is an example of a « deep » intraplate strike-slip earthquake which occurred in the low ocean crust or mantle. The Wyoming event is thus a very unique example of deep intracontinental earthquake. The physical mechanism responsible of intermediate-depth earthquakes remains under debate. This work aims at determining robust source parameters to investigate any distinct characteristic from that for shallow earthquakes or subduction zone intermediate-depth events.We adopt the empirical Green's function (EGF) approach to empirically correct for path and site effects. The nearby Ml3.0 aftershock which occurred 2 hours after the mainshock and at similar depth, is considered as EGF earthquake. This only aftershock is located at ~5 km from the mainshock and turns out to be a good EGF since both earthquakes generate high-correlated waveforms. Using the multitaper approach we are able to deconvolve the EGF from the mainshock with robust spectral and temporal representations. We use both the spectral (spectral ratio) and the temporal (source time function) information to obtain a more robust estimate of the source duration and the corresponding corner frequency, but require an adaptive window in order to have good signal to noise ratios in as wide a frequency band as possible. We propose a semi-automatic, adaptive time window approach, that allows for a robust measurement at each single station, thereby enhancing the analysis of the azimuthal distribution of corner frequencies.We additionally investigate the radiated seismic energy of the Mw4.8 earthquake

  17. Source parameters of March 10 and September 13, 2007, United Arab Emirates earthquakes

    NASA Astrophysics Data System (ADS)

    Al Marzooqi, Y.; Abou Elenean, K. M.; Megahed, A. S.; El-Hussain, I.; Rodgers, A. J.; Al Khatibi, E.

    2008-11-01

    On March 10 and September 13, 2007 two earthquakes with moment magnitudes 3.66 and 3.94, respectively, occurred in the eastern part of the United Arab Emirates (UAE). The two events were widely felt in the northern Emirates and Oman and were accompanied by a few aftershocks. Ground motions from these events were well recorded by the broadband stations of Dubai (UAE) and Oman seismological networks and provide an excellent opportunity to study the tectonic process and present day stress field acting in this area. In this study, we report the focal mechanisms of the two main shocks by two methods: first motion polarities and regional waveform moment tensor inversion. Our results indicate nearly pure normal faulting mechanisms with a slight strike slip component. We associated the fault plane trending NNE-SSW with a suggested fault along the extension of the faults bounded Bani Hamid area. The seismicity distribution between two earthquake sequences reveals a noticeable gap that may be a site of a future event. The source parameters (seismic moment, moment magnitude, fault radius, stress drop and displacement across the fault) were also estimated from displacement spectra. The moment magnitudes were very consistent with waveform inversion. The recent deployment of seismic networks in Dubai and Oman reveals tectonic activity in the northern Oman Mountains that was previously unknown. Continued observation and analysis will allow for characterization of seismicity and assessment of seismic hazard in the region.

  18. Effect of light source parameters on the polarization properties of the beam

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Liu, Yan; Jiang, Hui-lin; Liu, Zhi; Zhou, Xin; Fang, Hanhan

    2013-08-01

    Polarized laser has been widely used in free space optical communication, laser radar, and laser ranging system because of its advantages of good performance in recent years. The changes of laser polarization properties in the process of transmission in atmospheric turbulence have a certain impact on the system performance. The paper research on the rule of polarization properties changes of Gauss Schell model beam in turbulent conditions. And analysis the main factors to affect the polarization properties by numerical simulation using MATLAB software tools. The factors mainly including: initial polarization, coherence coefficient, spot size and the intensity of the atmospheric turbulent. The simulation results show that, the degree of polarization will converge to the initial polarization when the beam propagation in turbulent conditions. The degrees of polarization change to different value when initial polarization of beam is different in a short distance. And, the degrees of polarization converge to the initial polarization after long distance. Beam coherence coefficient bigger, the degree of polarization and change range increases bigger. The change of polarization more slowly for spot size is bigger. The change of polarization change is faster for longer wavelength. The conclusion of the study indicated that the light source parameters effect the changes of polarization properties under turbulent conditions. The research provides theory basis for the polarization properties of the laser propagation, and it will plays a significant role in optical communication and target recognition.

  19. Estimation of eruption source parameters from umbrella cloud or downwind plume growth rate

    NASA Astrophysics Data System (ADS)

    Pouget, Solène; Bursik, Marcus; Webley, Peter; Dehn, Jon; Pavolonis, Michael

    2013-05-01

    We introduce a new method to estimate mass eruption rate (MER) and mass loading from the growth of a volcanic umbrella cloud or downwind plume using satellite images, or photographs where ground-based observations are available. This new method is compared with pre-existing models and documented mass eruption rate given in the research literature. We applied the method to five well-studied eruptions (Mount St. Helens, 1980; Redoubt, 1990; Pinatubo, 1991; Hekla, 2000 and Eyjafjallajökull, 2010) and to five less well-documented eruptions (Kliuchevsko'i, 1994; Okmok, 2008; Kasatochi, 2008; Sarychev Peak, 2009 and Bezymianny, 2012). The mass eruption rate is obtained by estimation of the radius of the umbrella cloud with time or by estimation of the width of the downwind plume with distance from the volcano. The results given by the new method show a more fully characterized MER as a function of time than do the results given by pre-existing methods, and allow a faster, remote assessment of the mass eruption rate, even for volcanoes that are difficult to study. The method thus may provide an additional important path to the estimation of source parameters and the forecasting of ash cloud propagation. In addition, in cases where numerous methods are available, use of the method yields new, independent measures of mass eruption rate, hence an ability to estimate uncertainty in mass eruption rate, which could be used in probabilistic estimations of ash cloud propagation.

  20. Effect of dietary alternative lipid sources on haematological parameters and serum constituents of Heterobranchus longifilis fingerlings.

    PubMed

    Babalola, T O O; Adebayo, M A; Apata, D F; Omotosho, J S

    2009-03-01

    The worldwide increase in aquaculture production and the decrease of wild fish stocks has made the replacement of fish oil (FO) in aquafeed industry a priority. Therefore, the use of terrestrial animal fats and vegetable oils, which has lower cost and larger supplies, may be good as substitute for FO. This study investigate the effects of total replacement of FO by two terrestrial animal fats (pork lard and poultry fat) and three vegetable oils (palm kernel oil, sheabutter oil and sunflower oil) on haematological and serum biochemical profile of Heterobranchus longifilis over 70 days. FO-diet was used as the control. The haematological parameters were significantly affected by dietary lipid sources. Serum total protein was not influenced by the dietary lipids. However, serum cholesterol was significantly higher in fish fed diet containing sunflower oil. Glucose and activities of liver enzymes in blood serum were significantly reduced in fish fed alternative lipids when compared with the control. These results indicate that FO can be replaced completely with alternative lipids without any serious negative health impacts.

  1. Source Parameters of the Deadly Mw 7.6 Kashmir Earthquake of 8 October, 2005

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik; Chadha, R. K.; Kumar, N.; Raju, I. P.; Satyamurty, C.

    2007-10-01

    During the last six years, National Geophysical Research Institute, Hyderabad has established a semi-permanent seismological network of 5 8 broadband seismographs and 10 20 accelerographs in the Kachchh seismic zone, Gujarat with a prime objective to monitor the continued aftershock activity of the 2001 Mw 7.7 Bhuj mainshock. The reliable and accurate broadband data for the 8 October Mw 7.6 2005 Kashmir earthquake and its aftershocks from this network as well as Hyderabad Geoscope station enabled us to estimate the group velocity dispersion characteristics and one-dimensional regional shear velocity structure of the Peninsular India. Firstly, we measure Rayleigh-and Love-wave group velocity dispersion curves in the period range of 8 to 35 sec and invert these curves to estimate the crustal and upper mantle structure below the western part of Peninsular India. Our best model suggests a two-layered crust: The upper crust is 13.8 km thick with a shear velocity (Vs) of 3.2 km/s; the corresponding values for the lower crust are 24.9 km and 3.7 km/sec. The shear velocity for the upper mantle is found to be 4.65 km/sec. Based on this structure, we perform a moment tensor (MT) inversion of the bandpass (0.05 0.02 Hz) filtered seismograms of the Kashmir earthquake. The best fit is obtained for a source located at a depth of 30 km, with a seismic moment, Mo, of 1.6 × 1027 dyne-cm, and a focal mechanism with strike 19.5°, dip 42°, and rake 167°. The long-period magnitude (MA ~ Mw) of this earthquake is estimated to be 7.31. An analysis of well-developed sPn and sSn regional crustal phases from the bandpassed (0.02 0.25 Hz) seismograms of this earthquake at four stations in Kachchh suggests a focal depth of 30.8 km.

  2. Source Parameters of the 8 October, 2005 Mw7.6 Kashmir Earthquake

    NASA Astrophysics Data System (ADS)

    Mandal, Prantik; Chadha, R. K.; Kumar, N.; Raju, I. P.; Satyamurty, C.

    2007-12-01

    During the last six years, the National Geophysical Research Institute, Hyderabad has established a semi-permanent seismological network of 5 broadband seismographs and 10 accelerographs in the Kachchh seismic zone, Gujarat, with the prime objective to monitor the continued aftershock activity of the 2001 Mw7.7 Bhuj mainshock. The reliable and accurate broadband data for the Mw 7.6 (8 Oct., 2005) Kashmir earthquake and its aftershocks from this network, as well as from the Hyderabad Geoscope station, enabled us to estimate the group velocity dispersion characteristics and the one-dimensional regional shear-velocity structure of peninsular India. Firstly, we measure Rayleigh- and Love-wave group velocity dispersion curves in the range of 8 to 35 sec and invert these curves to estimate the crustal and upper mantle structure below the western part of peninsular India. Our best model suggests a two-layered crust: The upper crust is 13.8-km thick with a shear velocity (Vs) of 3.2 km/s; the corresponding values for the lower crust are 24.9 km and 3.7 km/sec. The shear velocity for the upper mantle is found to be 4.65 km/sec. Based on this structure, we perform a moment tensor (MT) inversion of the bandpass (0.05 0.02 Hz) filtered seismograms of the Kashmir earthquake. The best fit is obtained for a source located at a depth of 30 km, with a seismic moment, Mo, of 1.6 × 1027 dyne-cm, and a focal mechanism with strike 19.5°, dip 42°, and rake 167°. The long-period magnitude (MA ~ Mw) of this earthquake is estimated to be 7.31. An analysis of well-developed sPn and sSn regional crustal phases from the bandpassed (0.02 0.25 Hz) seismograms of this earthquake at four stations in Kachchh suggests a focal depth of 30.8 km.

  3. Eruption Source Parameters for Recent Icelandic Eruptions and Their Implications for Duration and Termination of Events

    NASA Astrophysics Data System (ADS)

    Thordarson, T.

    2015-12-01

    Since 1947, Iceland has featured 26 volcanic eruptions (2.5 eruptions/year). These include events at the central volcanoes Hekla, Eyjafjallajökull, Grímsvötn and Askja and the fissure eruptions of Surtsey 1963-67 and Nornahraun 2014-15. Of these, 11 are effusive, 8 are mixed (explosive to effusive) and 6 are within-glacier events. Surtsey is the only emergent submarine event (1309 days; 1 km3). Duration of effusive eruptions spans 0.3 to 181 days, with volume, average and peak magma discharge ranging from 10-5-1.6 km3, 0.5-123 m3/s and 1-370 m3/s. Similarly, the mixed events have durations spanning 2.8 to 393 days with volume, average and peak magma discharge ranging from 0.03-0.87 km3, 14-617 m3/s and 50-35600 m3/s. Duration of within-glacier events spans 4.4 to 14 days with volume, average and peak magma discharge ranging from 0.05-0.27 km3, 9-440 m3/s and 400-14000 m3/s. The discharge profiles for these eruptions are highly variable. Mixed eruptions often feature intense discharge (1500 to 40000 m3/s) at the onset of eruption (lasting hours), but some start in a much more subdued manner (500-1000 m3/s). This initial phase is followed by low (3-20 m3/s) magma discharge lasting for weeks to months that normally terminates abruptly. The onset of effusive eruptions is typified by modest discharge (10's to 100's m3/s). They can be very abrupt (<1 day), or drawn out for weeks to months with discharge dropping steadily throughout. The within-glacier events are short-lived explosive events, although with highly varied intensity (see above), and appear to terminate rather abruptly. Plots of eruption duration against size or discharge exhibits no systematic correlation suggesting that none of the eruption source parameters exert principal control on eruption duration or termination. However, these parameters may play a role in conjunction with other factors such as the nature of the lithostratigraphic succession and the local stress field at the eruption site.

  4. Evaluating the effect of various intracavitary applicators on dosimetric parameters of (192)Ir, (137)Cs, and (60)Co sources.

    PubMed

    Ghorbani, Mahdi; Hashempour, Marjan; Azizi, Mona; Meigooni, Ali S

    2016-06-01

    The purpose of this research is to study the effect of various applicator compositions on dosimetric parameters and dose distribution of (192)Ir, (137)Cs, and (60)Co sources, using Monte Carlo simulation techniques. To study the effect of applicators on source dosimetry, the dose rate constant, and radial dose function and isodose curves for the above noted sources were calculated in the presence and absence of plastic, titanium, and a stainless steel applicators. The effects of the applicators on the dosimetric parameters and isodose curves of these sources were dependent of the source type and materials of the applicator. The (192)Ir source with the stainless steel applicator has the maximum difference of dose rate (4.2 %) relative to the without applicator case. The (60)Co source with plastic applicator has the minimum dose variation. Moreover, this effect is higher for lower energy sources. Ignoring the effect of applicator composition and geometry on dose distribution may cause discrepancies in treatment planning. Plastic applicators have the least radiation attenuation compared to the other applicators, therefore, they are recommended for use in brachytherapy. A table of correction factors has been introduced for different sources and applicators with different materials for the clinical applications.

  5. The Beni Haoua, Algeria, Mw 4.9 earthquake: source parameters, engineering, and seismotectonic implications

    NASA Astrophysics Data System (ADS)

    Abbes, Khadidja; Dorbath, Louis; Dorbath, Catherine; Djeddi, Mohamed; Ousadou, Farida; Maouche, Said; Benkaci, Nassima; Slimani, Abdennasser; Larbes, Said; Bouziane, Djillali

    2016-04-01

    A moderate Mw 4.9 earthquake struck the Beni Haoua (Algeria) coastal area on April 25, 2012. The mainshock was largely recorded by the accelerograph network of the Centre National de Recherche Appliquée en Génie Parasismique (CGS). The same day the earthquake occurred, eight mobile short period stations were deployed through the epicentral area. In this study, we use accelerogram and seismogram data recorded by these two networks. We combined the focal mechanism built from the first motion of P waves and from waveform inversion, and the distribution of aftershocks to well constrain the source parameters. The mainshock is located with a shallow focal depth, ˜9 km, and the focal mechanism shows a nearly pure left lateral strike slip motion, with total seismic moment of 2.8 × 1016 N.m (Mw = 4.9). The aftershocks mainly cluster on a narrow NS strip, starting at the coast up to 3-4 km inland. This cluster, almost vertical, is concentrated between 6 and 10 km depth. The second part of this work concerns the damage distribution and estimated intensity in the epicentral area. The damage distribution is discussed in connection with the observed maximum strong motion. The acceleration response spectrum with 5 % damping of the mainshock and aftershocks give the maximum amplitude in high frequency which directly affects the performance of the high-frequency structures. Finally, we tie this earthquake with the seismotectonic of the region, leading to conclude that it occurred on a N-S transform zone between two major compressional fault zones oriented NE-SW.

  6. Constraints on recent earthquake source parameters, fault geometry and aftershock characteristics in Oklahoma

    NASA Astrophysics Data System (ADS)

    McNamara, D. E.; Benz, H.; Herrmann, R. B.; Bergman, E. A.; McMahon, N. D.; Aster, R. C.

    2014-12-01

    In late 2009, the seismicity of Oklahoma increased dramatically. The largest of these earthquakes was a series of three damaging events (Mw 4.8, 5.6, 4.8) that occurred over a span of four days in November 2011 near the town of Prague in central Oklahoma. Studies suggest that these earthquakes were induced by reactivation of the Wilzetta fault due to the disposal of waste water from hydraulic fracturing ("fracking") and other oil and gas activities. The Wilzetta fault is a northeast trending vertical strike-slip fault that is a well known structural trap for oil and gas. Since the November 2011 Prague sequence, thousands of small to moderate (M2-M4) earthquakes have occurred throughout central Oklahoma. The most active regions are located near the towns of Stillwater and Medford in north-central Oklahoma, and Guthrie, Langston and Jones near Oklahoma City. The USGS, in collaboration with the Oklahoma Geological Survey and the University of Oklahoma, has responded by deploying numerous temporary seismic stations in the region in order to record the vigorous aftershock sequences. In this study we use data from the temporary seismic stations to re-locate all Oklahoma earthquakes in the USGS National Earthquake Information Center catalog using a multiple-event approach known as hypo-centroidal decomposition that locates earthquakes with decreased uncertainty relative to one another. Modeling from this study allows us to constrain the detailed geometry of the reactivated faults, as well as source parameters (focal mechanisms, stress drop, rupture length) for the larger earthquakes. Preliminary results from the November 2011 Prague sequence suggest that subsurface rupture lengths of the largest earthquakes are anomalously long with very low stress drop. We also observe very high Q (~1000 at 1 Hz) that explains the large felt areas and we find relatively low b-value and a rapid decay of aftershocks.

  7. The Source and Impact of Specific Parameters that Enhance Well-Being in Daily Life.

    PubMed

    Stewart, William C; Reynolds, Kelly E; Jones, Lydia J; Stewart, Jeanette A; Nelson, Lindsay A

    2016-08-01

    The purpose of this study was to review four parameters (forgiveness, gratitude, hope and empathy) frequently noted when evaluating well-being. We reviewed clinical studies from 1966 to present. We included 63 articles. All four of the parameters were shown to generally improve an individual's well-being. These parameters demonstrated a positive influence within more specific societal issues including improvement in social relationships, delinquent behavior and physical health. These parameters were generally derived from training and religion. This study suggests that these parameters may improve either one of general well-being, pro-social and positive relational behavior and demonstrate positive health effects. PMID:26087913

  8. High frequency 3-component waveform inversion for source and structural parameters. Final report, 31 December 1993--30 June 1998

    SciTech Connect

    Harvey, D.J.; Lavehio, A.L.

    1998-09-01

    The authors present the results of three studies to develop and verify techniques to classify weak seismic events. (1) The method and results of full waveform inversion for both detailed source parameters and structure parameters are described. Input data were seismograms from industrial explosions in Eastern Kazakhstan recorded by the NRDC seismic network in 1987. Very good fits were produced between the synthetic seismograms and the observed data on all three components simultaneously and for P-wave, Rayleigh wave, and Love wave. They interpreted some of the inverted source parameters as characteristic of several different types of industrial surface mining operations. (2) The same technique was used to determine detailed source and structure parameters using an event that is highly relevant to nuclear monitoring. They determined that a salt mine collapse near Solikamsk, the Ural Mountains on 5 January 1995 was most likely a mine collapse instead of an underground explosions. (3) This study was carried out jointly by the Seismology Group of the University of Colorado and the Russian team from the Int`l Institute of Earthquake Prediction Theory and Math. Geophysics. They developed a new technique to identify a seismic event based on simultaneous inversion of surface wave amplitude spectra and signs of first motions of body wave. They applied this technique to several events near the Chinese test site at Lop Nor and demonstrated significant differences in source parameters characterizing explosions and natural earthquakes in this region.

  9. 40 CFR Table F-2 to Subpart F of... - Default Data Sources for Parameters Used for CO2 Emissions

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Default Data Sources for Parameters Used for CO2 Emissions F Table F-2 to Subpart F of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Aluminum...

  10. 40 CFR Table F-2 to Subpart F of... - Default Data Sources for Parameters Used for CO2 Emissions

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Default Data Sources for Parameters Used for CO2 Emissions F Table F-2 to Subpart F of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Aluminum...

  11. 40 CFR Table F-2 to Subpart F of... - Default Data Sources for Parameters Used for CO2 Emissions

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Default Data Sources for Parameters Used for CO2 Emissions F Table F-2 to Subpart F of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Aluminum...

  12. 40 CFR Table F-2 to Subpart F of... - Default Data Sources for Parameters Used for CO2 Emissions

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Default Data Sources for Parameters Used for CO2 Emissions F Table F-2 to Subpart F of Part 98 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Aluminum...

  13. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T.-C.; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators.

  14. Parasitic analysis and π-type Butterworth-Van Dyke model for complementary-metal-oxide-semiconductor Lamb wave resonator with accurate two-port Y-parameter characterizations.

    PubMed

    Wang, Yong; Goh, Wang Ling; Chai, Kevin T-C; Mu, Xiaojing; Hong, Yan; Kropelnicki, Piotr; Je, Minkyu

    2016-04-01

    The parasitic effects from electromechanical resonance, coupling, and substrate losses were collected to derive a new two-port equivalent-circuit model for Lamb wave resonators, especially for those fabricated on silicon technology. The proposed model is a hybrid π-type Butterworth-Van Dyke (PiBVD) model that accounts for the above mentioned parasitic effects which are commonly observed in Lamb-wave resonators. It is a combination of interdigital capacitor of both plate capacitance and fringe capacitance, interdigital resistance, Ohmic losses in substrate, and the acoustic motional behavior of typical Modified Butterworth-Van Dyke (MBVD) model. In the case studies presented in this paper using two-port Y-parameters, the PiBVD model fitted significantly better than the typical MBVD model, strengthening the capability on characterizing both magnitude and phase of either Y11 or Y21. The accurate modelling on two-port Y-parameters makes the PiBVD model beneficial in the characterization of Lamb-wave resonators, providing accurate simulation to Lamb-wave resonators and oscillators. PMID:27131699

  15. Mesh parameterization opens the door to FEM-based inverse methods for estimating nonlinear source parameters of volcano deformation

    NASA Astrophysics Data System (ADS)

    Stone, J.; Masterlark, T.; Feigl, K.

    2010-12-01

    Migration of magma within an active volcano produces a deformation signature at the Earth’s surface. The internal structure of a volcano and specific movements of the magma control the actual deformation that we observe. Relatively simple models that simulate magma injection as a pressurized body embedded in a half-space with uniform elastic properties (e.g., Mogi) describe the characteristic radially-symmetric deformation patterns that are commonly observed for episodes of volcano inflation or deflation. Inverse methods based on Mogi-type models can precisely and efficiently estimate the non-linear parameters that describe the geometry (position and shape) of the deformation source, as well as the linear parameter that describes the strength (pressure) of the deformation source. Although such models mimic the observed deformation, they assume a rheologic structure that drastically oversimplifies the plumbing beneath a volcano. This incompatibility can lead to biases in estimating the parameters of the model. Alternatively, Finite Element Models (FEMs) can simulate a pressurized body embedded in a problem domain having an arbitrary distribution of material properties that better corresponds to the internal structure of an active volcano. FEMs have been used in inverse methods for estimating linear deformation source parameters, such as the source pressure. However, perturbations of the non-linear parameters that describe the geometry of the source require automated re-meshing of the problem domain -a significant obstacle to implementing FEM-based nonlinear inverse methods in volcano deformation studies. We present a parametric executable (C++ source code), which automatically generates Abaqus FEMs that simulate a pressurized ellipsoid embedded in an axisymmetric problem domain, having an a priori distribution of material properties. We demonstrate this executable by analyzing InSAR-observed deformation of the 1997 eruption of Okmok Volcano, Alaska as an example

  16. Application of the Approximate Bayesian Computation methods in the stochastic estimation of atmospheric contamination parameters for mobile sources

    NASA Astrophysics Data System (ADS)

    Kopka, Piotr; Wawrzynczak, Anna; Borysiewicz, Mieczyslaw

    2016-11-01

    In this paper the Bayesian methodology, known as Approximate Bayesian Computation (ABC), is applied to the problem of the atmospheric contamination source identification. The algorithm input data are on-line arriving concentrations of the released substance registered by the distributed sensors network. This paper presents the Sequential ABC algorithm in detail and tests its efficiency in estimation of probabilistic distributions of atmospheric release parameters of a mobile contamination source. The developed algorithms are tested using the data from Over-Land Atmospheric Diffusion (OLAD) field tracer experiment. The paper demonstrates estimation of seven parameters characterizing the contamination source, i.e.: contamination source starting position (x,y), the direction of the motion of the source (d), its velocity (v), release rate (q), start time of release (ts) and its duration (td). The online-arriving new concentrations dynamically update the probability distributions of search parameters. The atmospheric dispersion Second-order Closure Integrated PUFF (SCIPUFF) Model is used as the forward model to predict the concentrations at the sensors locations.

  17. Surface brightness, standard candles and q/0/. [universe deceleration parameter determination by redshift-magnitude relation of extragalactic sources

    NASA Technical Reports Server (NTRS)

    Petrosian, V.

    1977-01-01

    The most direct way to determine the deceleration parameter, q(0), of the universe is through the study of the redshift-magnitude relation of extragalactic sources. Progress has been slow because the necessary sources for this study must be standard candles, which have identical absolute total luminosity (balometric or monochromatic). The present paper shows, first of all, that, although necessary, this is not a sufficient condition for nonpoint-like (or resolved) sources. A modification of the redshift-magnitude relation is then described for a certain class of nonstandard candles using measurements of isophotal surface brightness. It is noted that such measurements can be used to standardize the central surface brightness of galaxies, but the standardization of the scale parameter remains beyond observations.

  18. Modeling the Global Distribution of Plasma Parameters on Coronal Source Surface for Different Solar Phases Using 1AU Observations

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Shen, F.; Feng, X.

    2015-10-01

    In this paper, we have developed an empirical model of the global distribution of plasma parameters on the coronal source surface (at 2.5 solar radii (Rs) in our study) by analyzing observations from Ulysses and OMNI data. We use this model to construct the global map of source surface plasma for four typical Carrington Rotations (CRs) during different phases of solar activity, and analyze the basic characteristics of the distribution. A simple validation of the model is made by comparing the density and velocity distribution with the pB-inversed density and Wang-Sheeley-Arge (WSA) model velocity. The preliminary results show that our model gives reasonable large scale distribution of source surface plasma parameters at different phases of solar activity.

  19. Impact of assay parameters on the accuracy of free PSA test: source and stability of calibrator, calibration curve fitting, and level of total PSA in the serum.

    PubMed

    Liu, G H; Wu, J T

    1998-01-01

    The measurement of PSA is recommended for men over 50 years of age for screening of prostate cancer. However, proper differentiation of prostate cancer from benign prostate hyperplasia (BPH) relies on an accurate measurement of free PSA (fPSA) and a correct calculation of percent fPSA. Because of the extremely low concentration of fPSA in the serum, any slight deviation from its true value may produce large errors in percent fPSA calculated. Therefore, we undertook a study examining carefully those parameters of the fPSA assay which might affect the fPSA determination. We found that the integrity of the calibrator, the computer curve-fitting program selected, the source of the calibrator, and the total PSA or fPSA + PSA complexes (tPSA) concentration of the specimen all had an impact on the accuracy of the fPSA value assayed. We found that an examination of the slope of the calibration curve was important to reveal whether the calibrator had or had not been denatured during storage. We also found that the 4-parameter cure fitting program was best suited for plotting the fPSA calibration curve. The calibrator we isolated from LNCaP cells was acceptable for our assay because it had an affinity for the assay antibody very similar to that of serum fPSA. We also determined the effect of tPSA concentration on the fPSA determinations and found that within the concentration range of 4-10 ng/mL the impact on the percent fPSA calculated was not significant. We believe that our assay produces accurate fPSA values when all these assay parameters are well controlled.

  20. Optimization of deterministic transport parameters for the calculation of the dose distribution around a high dose-rate {sup 192}Ir brachytherapy source

    SciTech Connect

    Gifford, Kent A.; Price, Michael J.; Horton, John L. Jr.; Wareing, Todd A.; Mourtada, Firas

    2008-06-15

    The goal of this work was to calculate the dose distribution around a high dose-rate {sup 192}Ir brachytherapy source using a multi-group discrete ordinates code and then to compare the results with a Monte Carlo calculated dose distribution. The unstructured tetrahedral mesh discrete ordinates code Attila version 6.1.1 was used to calculate the photon kerma rate distribution in water around the Nucletron microSelectron mHDRv2 source. MCNPX 2.5.c was used to compute the Monte Carlo water photon kerma rate distribution. Two hundred million histories were simulated, resulting in standard errors of the mean of less than 3% overall. The number of energy groups, S{sub n} (angular order), P{sub n} (scattering order), and mesh elements were varied in addition to the method of analytic ray tracing to assess their effects on the deterministic solution. Water photon kerma rate matrices were exported from both codes into an in-house data analysis software. This software quantified the percent dose difference distribution, the number of points within {+-}3% and {+-}5%, and the mean percent difference between the two codes. The data demonstrated that a 5 energy-group cross-section set calculated results to within 0.5% of a 15 group cross-section set. S{sub 12} was sufficient to resolve the solution in angle. P{sub 2} expansion of the scattering cross-section was necessary to compute accurate distributions. A computational mesh with 55 064 tetrahedral elements in a 30 cm diameter phantom resolved the solution spatially. An efficiency factor of 110 with the above parameters was realized in comparison to MC methods. The Attila code provided an accurate and efficient solution of the Boltzmann transport equation for the mHDRv2 source.

  1. Monte Carlo calculated TG-60 dosimetry parameters for the {beta}{sup -} emitter {sup 153}Sm brachytherapy source

    SciTech Connect

    Sadeghi, Mahdi; Taghdiri, Fatemeh; Hamed Hosseini, S.; Tenreiro, Claudio

    2010-10-15

    Purpose: The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable for {beta} sources. Radioactive biocompatible and biodegradable {sup 153}Sm glass seed without encapsulation is a {beta}{sup -} emitter radionuclide with a short half-life and delivers a high dose rate to the tumor in the millimeter range. This study presents the results of Monte Carlo calculations of the dosimetric parameters for the {sup 153}Sm brachytherapy source. Methods: Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate two-dimensional dose distributions around the source. The dosimetric parameters of AAPM TG-60 recommendations including the reference dose rate, the radial dose function, the anisotropy function, and the one-dimensional anisotropy function were obtained. Results: The dose rate value at the reference point was estimated to be 9.21{+-}0.6 cGy h{sup -1} {mu}Ci{sup -1}. Due to the low energy beta emitted from {sup 153}Sm sources, the dose fall-off profile is sharper than the other beta emitter sources. The calculated dosimetric parameters in this study are compared to several beta and photon emitting seeds. Conclusions: The results show the advantage of the {sup 153}Sm source in comparison with the other sources because of the rapid dose fall-off of beta ray and high dose rate at the short distances of the seed. The results would be helpful in the development of the radioactive implants using {sup 153}Sm seeds for the brachytherapy treatment.

  2. Comparison of TG-43 dosimetric parameters of brachytherapy sources obtained by three different versions of MCNP codes.

    PubMed

    Zaker, Neda; Zehtabian, Mehdi; Sina, Sedigheh; Koontz, Craig; Meigooni, Ali S

    2016-01-01

    Monte Carlo simulations are widely used for calculation of the dosimetric parameters of brachytherapy sources. MCNP4C2, MCNP5, MCNPX, EGS4, EGSnrc, PTRAN, and GEANT4 are among the most commonly used codes in this field. Each of these codes utilizes a cross-sectional library for the purpose of simulating different elements and materials with complex chemical compositions. The accuracies of the final outcomes of these simulations are very sensitive to the accuracies of the cross-sectional libraries. Several investigators have shown that inaccuracies of some of the cross section files have led to errors in 125I and 103Pd parameters. The purpose of this study is to compare the dosimetric parameters of sample brachytherapy sources, calculated with three different versions of the MCNP code - MCNP4C, MCNP5, and MCNPX. In these simulations for each source type, the source and phantom geometries, as well as the number of the photons, were kept identical, thus eliminating the possible uncertainties. The results of these investigations indicate that for low-energy sources such as 125I and 103Pd there are discrepancies in gL(r) values. Discrepancies up to 21.7% and 28% are observed between MCNP4C and other codes at a distance of 6 cm for 103Pd and 10 cm for 125I from the source, respectively. However, for higher energy sources, the discrepancies in gL(r) values are less than 1.1% for 192Ir and less than 1.2% for 137Cs between the three codes. PMID:27074460

  3. Identification of copper sources in urban surface waters using the principal component analysis based on aquatic parameters.

    PubMed

    Sodre, Fernando Fabriz; dos Anjos, Vanessa Egea; Prestes, Ellen Christine; Grassi, Marco Tadeu

    2005-06-01

    The goal of this work was to identify the sources of copper loads in surface urban waters using principal component analysis under the aquatic parameters data evaluation approach. Water samples from the Irai and Iguacu rivers were collected monthly during a 12-month period at two points located upstream and downstream of a metropolitan region. pH, total alkalinity, dissolved chloride, total suspended solids, dissolved organic matter, total recoverable copper, temperature, and precipitation data provided some reliable information concerning the characteristics and water quality of both rivers. Principal component analysis indicated seasonal and spatial effects on copper concentration and loads in both environments. During the rainy season, non-point sources such as urban run-off are believed to be the major source of copper in both cases. In contrast, during the lower precipitation period, the discharge of raw sewage seems to be the primary source of copper to the Iguacu River, which also exhibited higher total metal concentrations.

  4. A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

    NASA Astrophysics Data System (ADS)

    Mastin, L. G.; Guffanti, M.; Servranckx, R.; Webley, P.; Barsotti, S.; Dean, K.; Durant, A.; Ewert, J. W.; Neri, A.; Rose, W. I.; Schneider, D.; Siebert, L.; Stunder, B.; Swanson, G.; Tupper, A.; Volentik, A.; Waythomas, C. F.

    2009-09-01

    During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called "eruption source parameters", such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m63 of erupted debris finer than about 4ϕ or 63 μm, which can remain in the cloud for many hours or days. Observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected. Moreover, observed plume height may change during an eruption, requiring rapid assignment of new parameters. This paper reports on a group effort to improve the accuracy of source parameters used by VATDs in the early hours of an eruption. We do so by first compiling a list of eruptions for which these parameters are well constrained, and then using these data to review and update previously studied parameter relationships. We find that the existing scatter in plots of H versus Ṁ yields an uncertainty within the 50% confidence interval of plus or minus a factor of four in eruption rate for a given plume height. This scatter is not clearly attributable to biases in measurement techniques or to well-recognized processes such as elutriation from pyroclastic flows. Sparse data on total grain-size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions (˜ 0.01) and large silicic ones (> 0.5). We classify eleven eruption types; four types each for different sizes of silicic and mafic eruptions; submarine eruptions; "brief" or Vulcanian eruptions; and eruptions that generate co-ignimbrite or co-pyroclastic flow plumes. For each eruption type we assign source parameters. We then assign a characteristic eruption type to each of the world's ˜ 1500 Holocene

  5. A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

    USGS Publications Warehouse

    Mastin, L.G.; Guffanti, M.; Servranckx, R.; Webley, P.; Barsotti, S.; Dean, K.; Durant, A.; Ewert, J.W.; Neri, A.; Rose, William I.; Schneider, D.; Siebert, L.; Stunder, B.; Swanson, G.; Tupper, A.; Volentik, A.; Waythomas, C.F.

    2009-01-01

    During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called "eruption source parameters", such as plume height H, mass eruption rate ???, duration D, and the mass fraction m63 of erupted debris finer than about 4??{symbol} or 63????m, which can remain in the cloud for many hours or days. Observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected. Moreover, observed plume height may change during an eruption, requiring rapid assignment of new parameters. This paper reports on a group effort to improve the accuracy of source parameters used by VATDs in the early hours of an eruption. We do so by first compiling a list of eruptions for which these parameters are well constrained, and then using these data to review and update previously studied parameter relationships. We find that the existing scatter in plots of H versus ??? yields an uncertainty within the 50% confidence interval of plus or minus a factor of four in eruption rate for a given plume height. This scatter is not clearly attributable to biases in measurement techniques or to well-recognized processes such as elutriation from pyroclastic flows. Sparse data on total grain-size distribution suggest that the mass fraction of fine debris m63 could vary by nearly two orders of magnitude between small basaltic eruptions (??? 0.01) and large silicic ones (> 0.5). We classify eleven eruption types; four types each for different sizes of silicic and mafic eruptions; submarine eruptions; "brief" or Vulcanian eruptions; and eruptions that generate co-ignimbrite or co-pyroclastic flow plumes. For each eruption type we assign source parameters. We then assign a characteristic eruption type to each of the world's ??? 1500

  6. A linear gradient line source facilitates the use of diffusion models with high order approximation for efficient, accurate turbid sample optical properties recovery.

    PubMed

    Lee, Ming-Wei; Hung, Cheng-Hung; Liao, Jung-Li; Cheng, Nan-Yu; Hou, Ming-Feng; Tseng, Sheng-Hao

    2014-10-01

    In this paper, we demonstrate that a scanning MEMS mirror can be employed to create a linear gradient line source that is equivalent to a planar source. This light source setup facilitates the use of diffusion models of increased orders of approximation having closed form solution, and thus enhance the efficiency and accuracy in sample optical properties recovery. In addition, compared with a regular planar light source, the linear gradient line source occupies much less source area and has an elevated measurement efficiency. We employed a δ-P1 diffusion equation with a closed form solution and carried out a phantom study to understand the performance of this new method in determining the absorption and scattering properties of turbid samples. Moreover, our Monte Carlo simulation results indicated that this geometry had probing depths comparable to those of the conventional diffuse reflectance measurement geometry with a source-detector separation of 3 mm. We expect that this new source setup would facilitate the investigating of superficial volumes of turbid samples in the wavelength regions where tissue absorption coefficients are comparable to scattering coefficients.

  7. Low-frequency source parameters of twelve large earthquakes. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Harabaglia, Paolo

    1993-01-01

    A global survey of the low-frequency (1-21 mHz) source characteristics of large events are studied. We are particularly interested in events unusually enriched in low-frequency and in events with a short-term precursor. We model the source time function of 12 large earthquakes using teleseismic data at low frequency. For each event we retrieve the source amplitude spectrum in the frequency range between 1 and 21 mHz with the Silver and Jordan method and the phase-shift spectrum in the frequency range between 1 and 11 mHz with the Riedesel and Jordan method. We then model the source time function by fitting the two spectra. Two of these events, the 1980 Irpinia, Italy, and the 1983 Akita-Oki, Japan, are shallow-depth complex events that took place on multiple faults. In both cases the source time function has a length of about 100 seconds. By comparison Westaway and Jackson find 45 seconds for the Irpinia event and Houston and Kanamori about 50 seconds for the Akita-Oki earthquake. The three deep events and four of the seven intermediate-depth events are fast rupturing earthquakes. A single pulse is sufficient to model the source spectra in the frequency range of our interest. Two other intermediate-depth events have slower rupturing processes, characterized by a continuous energy release lasting for about 40 seconds. The last event is the intermediate-depth 1983 Peru-Ecuador earthquake. It was first recognized as a precursive event by Jordan. We model it with a smooth rupturing process starting about 2 minutes before the high frequency origin time superimposed to an impulsive source.

  8. A summary of the sources of input parameter values for the Waste Isolation Pilot Plant final porosity surface calculations

    SciTech Connect

    Butcher, B.M.

    1997-08-01

    A summary of the input parameter values used in final predictions of closure and waste densification in the Waste Isolation Pilot Plant disposal room is presented, along with supporting references. These predictions are referred to as the final porosity surface data and will be used for WIPP performance calculations supporting the Compliance Certification Application to be submitted to the U.S. Environmental Protection Agency. The report includes tables and list all of the input parameter values, references citing their source, and in some cases references to more complete descriptions of considerations leading to the selection of values.

  9. Simultaneous Joint Inversion of Seismic AVO and Controlled Source Electromagnetic Data by Direct Estimation of Common Parameter Structure

    NASA Astrophysics Data System (ADS)

    Lien, M.

    2012-12-01

    We are concerned with the inverse problem of identifying changes in saturation for monitoring of underground reservoirs with application to CO2 sequestration and oil production monitoring. The inverse problem is at the outset ill-posed, where non-uniqueness and instability issues can lead to large uncertainties in the resulting parameter estimates. Constraining the inversion with a higher degree of information by combining information from different data sets will be important to improve the quality of the model calibration and thereby the reliability of the resulting reservoir predictions. For this, the simultaneous joint inversion of seismic AVO and controlled source electromagnetic (CSEM) data is considered. With simultaneous joint inversion, one secures that the final result from the inversion honors all available data. AVO and CSEM represent different sources of information. The seismic signals provide information about the elastic properties of the reservoir with relatively high spatial resolution, whereas CSEM data probe the electric properties of the subsediments at the extreme low frequency limit. Hence, the coupling of the two data types is not trivial. An increasingly popular approach for simultaneous joint inversion of disparate data sets is structure-coupled joint inversion. Here the coupling of the data sets is obtained by imposing structural dependency between the different geophysical model parameters (i.e. the elastic and electric properties of the reservoir). The idea is that some of the main property changes in the different model parameters are likely to occur over the same interfaces/structures representing e.g. changes in lithology or fluid saturation. We propose a novel approach for structure-coupled joint inversion, where the coupling of the different data sets is obtained by facilitating for estimation of parameter structure directly. The approach is based on a generic method for parameter representation providing a joint relation to a

  10. Estimation of earthquake source parameters by the inversion of waveform data: synthetic waveforms

    USGS Publications Warehouse

    Sipkin, S.A.

    1982-01-01

    Two methods are presented for the recovery of a time-dependent moment-tensor source from waveform data. One procedure utilizes multichannel signal-enhancement theory; in the other a multichannel vector-deconvolution approach, developed by Oldenburg (1982) and based on Backus-Gilbert inverse theory, is used. These methods have the advantage of being extremely flexible; both may be used either routinely or as research tools for studying particular earthquakes in detail. Both methods are also robust with respect to small errors in the Green's functions and may be used to refine estimates of source depth by minimizing the misfits to the data. The multichannel vector-deconvolution approach, although it requires more interaction, also allows a trade-off between resolution and accuracy, and complete statistics for the solution are obtained. The procedures have been tested using a number of synthetic body-wave data sets, including point and complex sources, with satisfactory results. ?? 1982.

  11. Assessing FPAR Source and Parameter Optimization Scheme in Application of a Diagnostic Carbon Flux Model

    SciTech Connect

    Turner, D P; Ritts, W D; Wharton, S; Thomas, C; Monson, R; Black, T A

    2009-02-26

    The combination of satellite remote sensing and carbon cycle models provides an opportunity for regional to global scale monitoring of terrestrial gross primary production, ecosystem respiration, and net ecosystem production. FPAR (the fraction of photosynthetically active radiation absorbed by the plant canopy) is a critical input to diagnostic models, however little is known about the relative effectiveness of FPAR products from different satellite sensors nor about the sensitivity of flux estimates to different parameterization approaches. In this study, we used multiyear observations of carbon flux at four eddy covariance flux tower sites within the conifer biome to evaluate these factors. FPAR products from the MODIS and SeaWiFS sensors, and the effects of single site vs. cross-site parameter optimization were tested with the CFLUX model. The SeaWiFs FPAR product showed greater dynamic range across sites and resulted in slightly reduced flux estimation errors relative to the MODIS product when using cross-site optimization. With site-specific parameter optimization, the flux model was effective in capturing seasonal and interannual variation in the carbon fluxes at these sites. The cross-site prediction errors were lower when using parameters from a cross-site optimization compared to parameter sets from optimization at single sites. These results support the practice of multisite optimization within a biome for parameterization of diagnostic carbon flux models.

  12. Effects of laser source parameters on the generation of narrow band and directed laser ultrasound

    NASA Technical Reports Server (NTRS)

    Spicer, James B.; Deaton, John B., Jr.; Wagner, James W.

    1992-01-01

    Predictive and prescriptive modeling of laser arrays is performed to demonstrate the effects of the extension of array elements on laser array performance. For a repetitively pulsed laser source (the temporal laser array), efficient frequency compression is best achieved by detecting longitudinal waves off-epicenter in plates where the source size and shape directly influence the longitudinal wave shape and duration; the longitudinal array may be tailored for a given repetition frequency to yield efficient overtone energy compression into the fundamental frequency band. For phased arrays, apparent array directivity is heavily influenced by array element size.

  13. Estimation of source parameters according to microseismic monitoring of the central part of the East-European platform

    NASA Astrophysics Data System (ADS)

    Besedina, Alina

    2016-04-01

    Microseismic monitoring of active fault allows one to quickly assess the seismicity of the study area. In platform conditions it requires more time to accumulate of representative data of occurrence of seismic endogenous events. The graphics repeatability, based on data from microseismic monitoring, correlate well with the dependence obtained during long-term regional observations. The focal parameters are assessed for sources of weak seismicity of the central part of East-European platform with the help of small-aperture array. Sensor bandwidth limitations can lead to underestimation of radiated seismic energy due to losses in high-frequency part of signal. Seismometers with enhance amplitude-frequency response in high-frequency part of the spectrum allow avoiding this instrumental problem. This provides records seismic oscillations from events with Mw ~ -2 - 1 and more correct estimation of seismic source parameters. This work was supported by the Russian Foundation for Basic Research (project no. 16-35-00508).

  14. Comparison of the Cut-and-Paste and Full Moment Tensor Methods for Estimating Earthquake Source Parameters

    NASA Astrophysics Data System (ADS)

    Templeton, D.; Rodgers, A.; Helmberger, D.; Dreger, D.

    2008-12-01

    Earthquake source parameters (seismic moment, focal mechanism and depth) are now routinely reported by various institutions and network operators. These parameters are important for seismotectonic and earthquake ground motion studies as well as calibration of moment magnitude scales and model-based earthquake-explosion discrimination. Source parameters are often estimated from long-period three- component waveforms at regional distances using waveform modeling techniques with Green's functions computed for an average plane-layered models. One widely used method is waveform inversion for the full moment tensor (Dreger and Helmberger, 1993). This method (TDMT) solves for the moment tensor elements by performing a linearized inversion in the time-domain that minimizes the difference between the observed and synthetic waveforms. Errors in the seismic velocity structure inevitably arise due to either differences in the true average plane-layered structure or laterally varying structure. The TDMT method can account for errors in the velocity model by applying a single time shift at each station to the observed waveforms to best match the synthetics. Another method for estimating source parameters is the Cut-and-Paste (CAP) method. This method breaks the three-component regional waveforms into five windows: vertical and radial component Pnl; vertical and radial component Rayleigh wave; and transverse component Love waves. The CAP method performs a grid search over double-couple mechanisms and allows the synthetic waveforms for each phase (Pnl, Rayleigh and Love) to shift in time to account for errors in the Green's functions. Different filtering and weighting of the Pnl segment relative to surface wave segments enhances sensitivity to source parameters, however, some bias may be introduced. This study will compare the TDMT and CAP methods in two different regions in order to better understand the advantages and limitations of each method. Firstly, we will consider the

  15. Identification of Transport Parameters and Pollution Sources for a Physically Based Groundwater Contaminant Transport Model: A Comparison of Algorithms

    NASA Astrophysics Data System (ADS)

    Yin, Y.; Sykes, J. F.

    2006-12-01

    Transport parameter estimation and contaminant source identification are critical steps in the development of a physically based groundwater contaminant transport model. For most transient field scale problems, the high computational burden required by parameter identification algorithms combined with sparse data sets often limits calibration. However, when data are available, a high performance computing system and parallel computing may make the calibration process feasible. The selection of the optimization algorithm is also critical. In this paper, the contaminant transport and source parameters were estimated and compared using optimization with two heuristic search algorithms (a dynamically dimensioned search and a parallelized micro genetic algorithm) and a gradient based multi-start PEST algorithm which were implemented on the Shared Hierarchical Academic Research Computing Network (Sharcnet). The case study is located in New Jersey where improper waste disposal resulted in the contamination of down gradient public water supply wells. Using FRAC3DVS, a physically based transient three-dimensional groundwater flow model with spatially and temporally varying recharge was developed and calibrated using both approximately 9 years of head data from continuous well records and data over a period of approximately 30 years from traditional monitoring wells. For the contaminant system, the parameters that were estimated include source leaching rate, source concentration, dispersivities, and retardation coefficient. The groundwater domain was discretized using 214,520 elements. With highly changing pump rates at the 7 municipal wells, time increments over the approximately 30 year simulation period varied dynamically between several days and 3 months. On Sharcnet, one forward simulation on a single processor of both transient flow and contaminant transport takes approximately 3 to 4 hours. The contaminant transport model calibration results indicate that overall

  16. A review of the nutritional content and technological parameters of indigenous sources of meat in South America.

    PubMed

    Saadoun, A; Cabrera, M C

    2008-11-01

    Meat yields, proximate compositions, fatty acids compositions and technological parameters are reviewed for species which might be further developed as indigenous sources of meat in South America. These include the alpaca (Lama pacos), capybara (Hydrochoerus hydrochaeris), guanaco (Lama guanicoe), llama (Lama glama), nutria (Myocastor coypus), collared peccary (Tayassu tajacu), greater rhea (Rhea americana), lesser rhea (Rhea pennata), yacare (Caiman crocodilus yacare), tegu lizard (Tupinambis merianae) and green iguana (Iguana iguana).

  17. Effect of source parameters on forward-directivity velocity pulse for vertical strike slip fault in half space

    NASA Astrophysics Data System (ADS)

    Liu, Qifang; Yuan, Yifan; Jin, Xing

    2006-06-01

    It has been found that the large velocity pulse is one of the most important characteristics of near-fault strong ground motions. Some statistical relationships between pulse period and the moment magnitude for near-fault strong ground motions have been established by Somerville (1998); Alavi and Krawinkler (2000); and Mavroeidis and Papageorgiou (2003), where no variety of rupture velocity, fault depth, and fault distance, etc. were considered. Since near-fault ground motions are significantly influenced by the rupture process and source parameters, the effects of some source parameters on the amplitude and the period of a forward-directivity velocity pulse in a half space are analyzed by the finite difference method combined with the kinematic source model in this paper. The study shows that the rupture velocity, fault depth, position of the initial rupture point and distribution of asperities are the most important parameters to the velocity pulse. Generally, the pulse period decreases and the pulse amplitude increases as the rupture velocity increases for shallow crustal earthquakes. In a definite region besides the fault trace, the pulse period increases as the fault depth increases. For a uniform strike slip fault, rupture initiating from one end of a fault and propagating to the other always generates a higher pulse amplitude and longer pulse period than in other cases.

  18. Inexpensive, Open-Source, Internet of Things-Enabled Sensing Stations for Environmental Parameter Measurements

    NASA Astrophysics Data System (ADS)

    Marchetto, P. M.; Hofmeister, K.; Walter, M. T.

    2015-12-01

    In the age of the Internet, data is inherently portable. Given the shrinking numbers of stream gauges in the US under the banner of the USGS and the lack of collocation of sensors for environmental parameters, it is clear the only way to collect these data is with near real-time, multi-parameters sensing stations. We are designing a system that can be built and deployed for under $300 by community groups interested in learning more about the land that they are protecting, such as conservation groups, or groups interested in the basic science behind sensing and ecology, such as makerspaces. Sensing stations like these will enable a greater diversity of data collection while increasing public awareness of environmental issues and the research process.

  19. Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident

    NASA Astrophysics Data System (ADS)

    Miyazawa, Y.; Masumoto, Y.; Varlamov, S. M.; Miyama, T.; Takigawa, M.; Honda, M.; Saino, T.

    2012-10-01

    With combined use of the ocean-atmosphere simulation models and field observation data, we evaluate the parameters associated with the total caesium-137 amounts of the direct release into the ocean and atmospheric deposition over the Western North Pacific caused by the accident of Fukushima Daiichi nuclear power plant (FNPP) that occurred in March 2011. The Green's function approach is adopted for the estimation of two parameters determining the total emission amounts for the period from 12 March to 6 May 2011. It is confirmed that the validity of the estimation depends on the simulation skill near FNPP. The total amount of the direct release is estimated as 5.5-5.9 × 1015 Bq, while that of the atmospheric deposition is estimated as 5.5-9.7 × 1015 Bq, which indicates broader range of the estimate than that of the direct release owing to uncertainty of the dispersion widely spread over the Western North Pacific.

  20. Inverse estimation of source parameters of oceanic radioactivity dispersion models associated with the Fukushima accident

    NASA Astrophysics Data System (ADS)

    Miyazawa, Y.; Masumoto, Y.; Varlamov, S. M.; Miyama, T.; Takigawa, M.; Honda, M.; Saino, T.

    2013-04-01

    With combined use of the ocean-atmosphere simulation models and field observation data, we evaluate the parameters associated with the total caesium-137 amounts of the direct release into the ocean and atmospheric deposition over the western North Pacific caused by the accident of Fukushima Daiichi nuclear power plant (FNPP) that occurred in March 2011. The Green's function approach is adopted for the estimation of two parameters determining the total emission amounts for the period from 12 March to 6 May 2011. It is confirmed that the validity of the estimation depends on the simulation skill near FNPP. The total amount of the direct release is estimated as 5.5-5.9 × 1015 Bq, while that of the atmospheric deposition is estimated as 5.5-9.7 × 1015 Bq, which indicates broader range of the estimate than that of the direct release owing to uncertainty of the dispersion widely spread over the western North Pacific.

  1. Recommended Parameter Values for INEEL Subsurface Disposal Area Source Release Modeling

    SciTech Connect

    Riley, Robert G.; Lopresti, Charles A.

    2004-06-23

    The purpose of this report is to summarize 1) associated information and values for key release model parameters (i.e., best estimate, minimum and maximum) obtained where possible from published experimental data, 2) a structure for selection of sensitivity tests cases that can be used to identify test cases, and 3) recommended test cases for selected contaminants of potential concern to assess remedy effectiveness against a no-treatment base case.

  2. Model parameter estimations from residual gravity anomalies due to simple-shaped sources using Differential Evolution Algorithm

    NASA Astrophysics Data System (ADS)

    Ekinci, Yunus Levent; Balkaya, Çağlayan; Göktürkler, Gökhan; Turan, Seçil

    2016-06-01

    An efficient approach to estimate model parameters from residual gravity data based on differential evolution (DE), a stochastic vector-based metaheuristic algorithm, has been presented. We have showed the applicability and effectiveness of this algorithm on both synthetic and field anomalies. According to our knowledge, this is a first attempt of applying DE for the parameter estimations of residual gravity anomalies due to isolated causative sources embedded in the subsurface. The model parameters dealt with here are the amplitude coefficient (A), the depth and exact origin of causative source (zo and xo, respectively) and the shape factors (q and ƞ). The error energy maps generated for some parameter pairs have successfully revealed the nature of the parameter estimation problem under consideration. Noise-free and noisy synthetic single gravity anomalies have been evaluated with success via DE/best/1/bin, which is a widely used strategy in DE. Additionally some complicated gravity anomalies caused by multiple source bodies have been considered, and the results obtained have showed the efficiency of the algorithm. Then using the strategy applied in synthetic examples some field anomalies observed for various mineral explorations such as a chromite deposit (Camaguey district, Cuba), a manganese deposit (Nagpur, India) and a base metal sulphide deposit (Quebec, Canada) have been considered to estimate the model parameters of the ore bodies. Applications have exhibited that the obtained results such as the depths and shapes of the ore bodies are quite consistent with those published in the literature. Uncertainty in the solutions obtained from DE algorithm has been also investigated by Metropolis-Hastings (M-H) sampling algorithm based on simulated annealing without cooling schedule. Based on the resulting histogram reconstructions of both synthetic and field data examples the algorithm has provided reliable parameter estimations being within the sampling limits of

  3. Tephra fallout hazard assessment at Vesuvius: the effect of uncertainties on the wind and the eruption source parameters

    NASA Astrophysics Data System (ADS)

    Macedonio, Giovanni; Costa, Antonio; Scollo, Simona; Neri, Augusto

    2016-04-01

    In this study we investigate the effect of using different meteorological datasets and eruption source parameters on tephra fallout hazard assessment for a sub-Plinian eruption of Vesuvius, which is considered as a reference case for hazard assessment analysis of Vesuvius. We analyze the effect of using different meteorological data, from: i) radio-sounding carried out at the meteorological station of Brindisi (Italy) between 1962 and 1976 and between 1996 and 2012 and at Pratica di Mare (Rome, Italy) between 1995 and 2013; ii) meteorological models of the National Oceanic and Atmospheric Administration (NOAA) and of the European Centre for Medium-Range Weather Forecasts (ECMWF). Furthermore, we consider the effects of perturbing reference eruptive source parameters. In particular, we vary the total mass, the total grain-size distribution, the column height, and the effective atmospheric diffusion coefficient to evaluate how these parameters affect the hazard probability maps. Moreover, the effect of the seasonal variation of the wind field and the effect of the rain on the deposit loading are considered. Results show that the parameter that mostly affects hazard maps is, as expected, the total erupted mass; furthermore, keeping constant the erupted mass, the most important control on hazard is due to the particle terminal settling velocity distribution which is a function of the total grain-size distribution, particle density and shape. Within the considered range variations, the hazard depends less on the use of different meteorological datasets, column height and effective diffusion coefficient.

  4. The Dosimetric Parameters Investigation of the Pulsed X-ray and Gamma Radiation Sources

    NASA Astrophysics Data System (ADS)

    Stuchebrov, S. G.; Miloichikova, I. A.; Shilova, X. O.

    2016-01-01

    The most common type of radiation used for diagnostic purposes are X-rays. However, X-rays methods have limitations related to the radiation dose for the biological objects. It is known that the use of the pulsed emitting source synchronized with the detection equipment for internal density visualization of objects significant reduces the radiation dose to the object. In the article the analysis of the suitability of the different dosimetric equipment for the radiation dose estimation of the pulsed emitting sources is carried out. The approbation results on the pulsed X-ray generator RAP-160-5 of the dosimetry systems workability with the pulse radiation and its operation range are presented. The results of the dose field investigation of the portable betatron OB-4 are demonstrated. The depth dose distribution in the air, lead and water of the pulsed bremsstrahlung generated by betatron are shown.

  5. Source Parameters for Moderate Earthquakes in the Zagros Mountains with Implications for the Depth Extent of Seismicity

    SciTech Connect

    Adams, A; Brazier, R; Nyblade, A; Rodgers, A; Al-Amri, A

    2009-02-23

    Six earthquakes within the Zagros Mountains with magnitudes between 4.9 and 5.7 have been studied to determine their source parameters. These events were selected for study because they were reported in open catalogs to have lower crustal or upper mantle source depths and because they occurred within an area of the Zagros Mountains where crustal velocity structure has been constrained by previous studies. Moment tensor inversion of regional broadband waveforms have been combined with forward modeling of depth phases on short period teleseismic waveforms to constrain source depths and moment tensors. Our results show that all six events nucleated within the upper crust (<11 km depth) and have thrust mechanisms. This finding supports other studies that call into question the existence of lower crustal or mantle events beneath the Zagros Mountains.

  6. 3D models of slow motions in the Earth's crust and upper mantle in the source zones of seismically active regions and their comparison with highly accurate observational data: II. Results of numerical calculations

    NASA Astrophysics Data System (ADS)

    Molodenskii, S. M.; Molodenskii, M. S.; Begitova, T. A.

    2016-09-01

    In the first part of the paper, a new method was developed for solving the inverse problem of coseismic and postseismic deformations in the real (imperfectly elastic, radially and horizontally heterogeneous, self-gravitating) Earth with hydrostatic initial stresses from highly accurate modern satellite data. The method is based on the decomposition of the sought parameters in the orthogonalized basis. The method was suggested for estimating the ambiguity of the solution of the inverse problem for coseismic and postseismic deformations. For obtaining this estimate, the orthogonal complement is constructed to the n-dimensional space spanned by the system of functional derivatives of the residuals in the system of n observed and model data on the coseismic and postseismic displacements at a variety of sites on the ground surface with small variations in the models. Below, we present the results of the numerical modeling of the elastic displacements of the ground surface, which were based on calculating Green's functions of the real Earth for the plane dislocation surface and different orientations of the displacement vector as described in part I of the paper. The calculations were conducted for the model of a horizontally homogeneous but radially heterogeneous selfgravitating Earth with hydrostatic initial stresses and the mantle rheology described by the Lomnitz logarithmic creep function according to (M. Molodenskii, 2014). We compare our results with the previous numerical calculations (Okado, 1985; 1992) for the simplest model of a perfectly elastic nongravitating homogeneous Earth. It is shown that with the source depths starting from the first hundreds of kilometers and with magnitudes of about 8.0 and higher, the discrepancies significantly exceed the errors of the observations and should therefore be taken into account. We present the examples of the numerical calculations of the creep function of the crust and upper mantle for the coseismic deformations. We

  7. Faulting processes and earthquake source parameters at Mount Etna: State of the art and perspectives

    NASA Astrophysics Data System (ADS)

    Patanè, Domenico; Giampiccolo, Elisabetta

    Seismicity at Mt. Etna, as in other volcanic areas, is usually defined as seismo-volcanic activity. However, a large class of earthquakes, named volcano-tectonic (VT), shares similar characteristics to those of seismic events acquired in tectonic environments. In the past, most of the ambiguities engendering a general mistrust in using simple source models originated from poor constraints on foci or unsatisfactory coverage of the focal sphere. Recently, after the Mt. Etna seismic network was boosted, more detailed analyses have been performed, allowing to verify that most of the earthquakes can be interpreted in terms of shear failure and their mechanisms can be considered to derive from the classical double-couple system of forces. This is supported by structural and geological evidences, as well as by the space-time features of seismicity and focal mechanism results, which confirm the important role played by regional tectonics at Mt. Etna. In this work we will present the state of the art of the source mechanism studies performed on Etnean VT earthquakes and discuss the role of attenuation effects and site response which strongly contribute to determine the "appearance" of seismograms. The results of the evaluation of the seismic moments and fault dimensions will be also discussed in order to compare Mt. Etna source scaling with those of other volcanic and non-volcanic areas in the world. Finally, some considerations on faulting processes, on the directivity effects and on the presence in the first P-pulse of a nucleation phase preceding a phase of high-speed rupture propagation will be provided.

  8. Information on Hydrologic Conceptual Models, Parameters, Uncertainty Analysis, and Data Sources for Dose Assessments at Decommissioning Sites

    SciTech Connect

    Meyer, Philip D.; Gee, Glendon W.; Nicholson, Thomas J.

    2000-02-28

    This report addresses issues related to the analysis of uncertainty in dose assessments conducted as part of decommissioning analyses. The analysis is limited to the hydrologic aspects of the exposure pathway involving infiltration of water at the ground surface, leaching of contaminants, and transport of contaminants through the groundwater to a point of exposure. The basic conceptual models and mathematical implementations of three dose assessment codes are outlined along with the site-specific conditions under which the codes may provide inaccurate, potentially nonconservative results. In addition, the hydrologic parameters of the codes are identified and compared. A methodology for parameter uncertainty assessment is outlined that considers the potential data limitations and modeling needs of decommissioning analyses. This methodology uses generic parameter distributions based on national or regional databases, sensitivity analysis, probabilistic modeling, and Bayesian updating to incorporate site-specific information. Data sources for best-estimate parameter values and parameter uncertainty information are also reviewed. A follow-on report will illustrate the uncertainty assessment methodology using decommissioning test cases.

  9. Evolution of plasma parameters in a He - N2/Ar magnetic pole enhanced inductive plasma source

    NASA Astrophysics Data System (ADS)

    Younus, Maria; Rehman, N. U.; Shafiq, M.; Zakaullah, M.; Abrar, M.

    2016-02-01

    A magnetic pole enhanced inductively coupled H e - N2/A r plasma is studied at low pressure, to monitor the effects of helium mixing on plasma parameters like electron number density (ne) , electron temperature (Te) , plasma potential (Vp ) , and electron energy probability functions (EEPFs). An RF compensated Langmuir probe is employed to measure these plasma parameters. It is noted that electron number density increases with increasing RF power and helium concentration in the mixture, while it decreases with increase in filling gas pressure. On the other hand, electron temperature shows an increasing trend with helium concentration in the mixture. At low RF powers and low helium concentration in the mixture, EEPFs show a "bi-Maxwellian" distribution with pressure. While at RF powers greater than 50 W and higher helium concentration in the mixture, EEPFs evolve into "Maxwellian" distribution. The variation of skin depth with RF power and helium concentration in the mixture, and its relation with EEPF are also studied. The effect of helium concentrations on the temperatures of two electron groups ( Tb u l k and Tt a i l ) in the "bi-Maxwellian" EEPFs is also observed. The temperature of low energy electron group ( Tb u l k) shows significant increase with helium addition, while the temperature of tail electrons ( Tt a i l) increases smoothly as compared to ( Tb u l k).

  10. DNAPL Mobility in Heterogeneous Porous Media: Sensitivity of Migration Times to Source Characteristics and Release Location Parameters

    NASA Astrophysics Data System (ADS)

    Pang, T.; Gerhard, J. I.; Kueper, B. H.

    2004-12-01

    This study examined the factors the influence the time required for a release of dense nonaqueous phase liquid (DNAPL) to cease migrating through heterogeneous porous media below the watertable. Using numerical simulation, the temporal and spatial sensitivity of DNAPL migration was evaluated for four DNAPL source characteristics - nonwetting fluid type (i.e., density and viscosity), interfacial tension (IFT), source strength, and volume released - and for three release location parameters - mean permeability, porosity, and hydraulic gradient. The study was conducted using the multiphase code DNAPL3D whose constitutive relationships were developed, and validated, for DNAPL migration in both space and time. All numerical simulations employed a single correlated random permeability field and identical boundary and source conditions to the base case, except for systematic variation of the parameter under investigation. It was found that all of the parameters examined had a significant spatial effect on the final DNAPL migration pattern, either on the overall volume of subsurface invaded (e.g., direct correlation to volume released) or on the amount of lateral spreading (e.g., direct correlation to IFT). However, only two of the parameters were found to have a significant effect on the time required to achieve the final, stable distribution of DNAPL pools and residual. Migration rates were very sensitive to DNAPL type, with predicted cessation times ranging from 30 days for the high mobility fluid tetrachloroethylene (PCE) to over 1000 years for the low mobility fluid coal tar. These simulations reveal that while density primarily influences the spatial extent of penetration and viscosity primarily influences penetration rate, the two effects are not independent due to interactions with site-specific heterogeneity. In addition, the mean permeability of the heterogeneous domain was found to be significant, with increases in mean k corresponding to decreases in both

  11. Investigation of fringe plasma parameters on a high power rf driven ion source

    SciTech Connect

    McNeely, P.; Schiesko, L.

    2010-02-15

    It has been observed that there are differences between the uncompensated Langmuir probes installed in the upper and lower areas of the rf driven H{sup -} sources at IPP Garching. The two probes often had substantially different floating potentials or ion saturation currents. In an effort to understand the reasons for these differences a Langmuir probe analysis system was used on the probes to collect the full current voltage characteristic. The results show what is likely the formation of an ion-ion plasma. The paper shows the effect of beam extraction and the presence of caesium on the probe characteristics.

  12. Near Real-Time Determination of Earthquake Source Parameters for Tsunami Early Warning from Geodetic Observations

    NASA Astrophysics Data System (ADS)

    Manneela, Sunanda; Srinivasa Kumar, T.; Nayak, Shailesh R.

    2016-06-01

    Exemplifying the tsunami source immediately after an earthquake is the most critical component of tsunami early warning, as not every earthquake generates a tsunami. After a major under sea earthquake, it is very important to determine whether or not it has actually triggered the deadly wave. The near real-time observations from near field networks such as strong motion and Global Positioning System (GPS) allows rapid determination of fault geometry. Here we present a complete processing chain of Indian Tsunami Early Warning System (ITEWS), starting from acquisition of geodetic raw data, processing, inversion and simulating the situation as it would be at warning center during any major earthquake. We determine the earthquake moment magnitude and generate the centroid moment tensor solution using a novel approach which are the key elements for tsunami early warning. Though the well established seismic monitoring network, numerical modeling and dissemination system are currently capable to provide tsunami warnings to most of the countries in and around the Indian Ocean, the study highlights the critical role of geodetic observations in determination of tsunami source for high-quality forecasting.

  13. Argon Cluster Sputtering Source for ToF-SIMS Depth Profiling of Insulating Materials: High Sputter Rate and Accurate Interfacial Information

    SciTech Connect

    Wang, Zhaoying; Liu, Bingwen; Zhao, Evan; Jin, Ke; Du, Yingge; Neeway, James J.; Ryan, Joseph V.; Hu, Dehong; Zhang, Hongliang; Hong, Mina; Le Guernic, Solenne; Thevuthasan, Suntharampillai; Wang, Fuyi; Zhu, Zihua

    2015-08-01

    For the first time, the use of an argon cluster ion sputtering source has been demonstrated to perform superiorly relative to traditional oxygen and cesium ion sputtering sources for ToF-SIMS depth profiling of insulating materials. The superior performance has been attributed to effective alleviation of surface charging. A simulated nuclear waste glass, SON68, and layered hole-perovskite oxide thin films were selected as model systems due to their fundamental and practical significance. Our study shows that if the size of analysis areas is same, the highest sputter rate of argon cluster sputtering can be 2-3 times faster than the highest sputter rates of oxygen or cesium sputtering. More importantly, high quality data and high sputter rates can be achieved simultaneously for argon cluster sputtering while this is not the case for cesium and oxygen sputtering. Therefore, for deep depth profiling of insulating samples, the measurement efficiency of argon cluster sputtering can be about 6-15 times better than traditional cesium and oxygen sputtering. Moreover, for a SrTiO3/SrCrO3 bi-layer thin film on a SrTiO3 substrate, the true 18O/16O isotopic distribution at the interface is better revealed when using the argon cluster sputtering source. Therefore, the implementation of an argon cluster sputtering source can significantly improve the measurement efficiency of insulating materials, and thus can expand the application of ToF-SIMS to the study of glass corrosion, perovskite oxide thin films, and many other potential systems.

  14. ZAP AND ITS APPLICATION TO THE OPTIMIZATION OF SYNCHROTRON LIGHT SOURCE PARAMETERS

    SciTech Connect

    Zisman, M.S.

    1987-10-01

    A new computer code, ZAP, has been written to study the influence of various collective effects on the performance of electron storage rings. In particular, the code can evaluate the equilibrium emittance of a ring including the effects of intrabeam scattering. Examples are presented of utilizing the code to optimize the design of storage rings for the purposes of a third-generation synchrotron radiation source and a high-gain free-electron laser. In addition, the importance of the intrabeam scattering emittance blowup to the issue of low energy injection is discussed. Such considerations will be necessary to optimize the design of compact synchrotrons now being studied for use in x-ray lithography. To verify predictions of the code, comparisons are made with experimental measurements of low energy beam emittance taken from the Aladdin storage ring; reasonable agreement is obtained.

  15. Laser-plasma source parameters for Kr, Gd, and Tb ions at 6.6 nm

    SciTech Connect

    Masnavi, Majid; Szilagyi, John; Parchamy, Homaira; Richardson, Martin C.

    2013-04-22

    There is increasing interest in extreme-ultraviolet (EUV) laser-based lamps for sub-10-nm lithography operating in the region of 6.6 nm. A collisional-radiative model is developed as a post-processor of a hydrodynamic code to investigate emission from resonance lines in Kr, Gd, and Tb ions under conditions typical for mass-limited EUV sources. The analysis reveals that maximum conversion efficiencies of Kr occur at 5 Multiplication-Sign 10{sup 10}W/cm{sup 2}, while for Gd and Tb it was Asymptotically-Equal-To 0.9%/2{pi}sr for laser intensities of (2-5) Multiplication-Sign 10{sup 12}W/cm{sup 2}.

  16. Source parameter estimates of echolocation clicks from wild pygmy killer whales (Feresa attenuata) (L)

    NASA Astrophysics Data System (ADS)

    Madsen, P. T.; Kerr, I.; Payne, R.

    2004-10-01

    Pods of the little known pygmy killer whale (Feresa attenuata) in the northern Indian Ocean were recorded with a vertical hydrophone array connected to a digital recorder sampling at 320 kHz. Recorded clicks were directional, short (25 μs) transients with estimated source levels between 197 and 223 dB re. 1 μPa (pp). Spectra of clicks recorded close to or on the acoustic axis were bimodal with peak frequencies between 45 and 117 kHz, and with centroid frequencies between 70 and 85 kHz. The clicks share characteristics of echolocation clicks from similar sized, whistling delphinids, and have properties suited for the detection and classification of prey targeted by this odontocete. .

  17. Source Parameters from Full Moment Tensor Inversions of Potentially Induced Earthquakes in Western Canada

    NASA Astrophysics Data System (ADS)

    Wang, R.; Gu, Y. J.; Schultz, R.; Kim, A.; Chen, Y.

    2015-12-01

    During the past four years, the number of earthquakes with magnitudes greater than three has substantially increased in the southern section of Western Canada Sedimentary Basin (WCSB). While some of these events are likely associated with tectonic forces, especially along the foothills of the Canadian Rockies, a significant fraction occurred in previously quiescent regions and has been linked to waste water disposal or hydraulic fracturing. A proper assessment of the origin and source properties of these 'induced earthquakes' requires careful analyses and modeling of regional broadband data, which steadily improved during the past 8 years due to recent establishments of regional broadband seismic networks such as CRANE, RAVEN and TD. Several earthquakes, especially those close to fracking activities (e.g. Fox creek town, Alberta) are analyzed. Our preliminary full moment tensor inversion results show maximum horizontal compressional orientations (P-axis) along the northeast-southwest orientation, which agree with the regional stress directions from borehole breakout data and the P-axis of historical events. The decomposition of those moment tensors shows evidence of strike-slip mechanism with near vertical fault plane solutions, which are comparable to the focal mechanisms of injection induced earthquakes in Oklahoma. Minimal isotropic components have been observed, while a modest percentage of compensated-linear-vector-dipole (CLVD) components, which have been linked to fluid migraition, may be required to match the waveforms. To further evaluate the non-double-couple components, we compare the outcomes of full, deviatoric and pure double couple (DC) inversions using multiple frequency ranges and phases. Improved location and depth information from a novel grid search greatly assists the identification and classification of earthquakes in potential connection with fluid injection or extraction. Overall, a systematic comparison of the source attributes of

  18. Investigating uncertainties in empirical Green's function analysis of earthquake source parameters

    NASA Astrophysics Data System (ADS)

    Abercrombie, Rachel E.

    2015-06-01

    I use a well-recorded earthquake sequence to investigate the uncertainties of earthquake stress drops calculated using an empirical Green's function (EGF) approach. The earthquakes in the largest (M ~ 2.1) repeating sequence targeted by the San Andreas Observatory at Depth (SAFOD), Parkfield, California, are recorded by multiple borehole stations and have simple sources, well-constrained stress drops, and abundant smaller earthquakes to use as EGFs. I perform three tests to estimate quantitatively the likely uncertainties to arise in less optimal settings. I use EGF earthquakes with a range of cross-correlation values and separation distances from the main earthquakes. The stress drop measurements decrease by a factor of 3 as the quality of the EGF assumption decreases; a good EGF must be located within approximately one source dimension of the large earthquake, with high cross correlation. I subsample the large number of measurements for the main earthquakes to investigate the expected stress drop uncertainties in studies where fewer stations or EGFs are available. If only one measurement is available, the uncertainties are likely to be at least 50%. The uncertainties decrease to <20% with five or more measurements; using multiple EGFs is a good alternative to multiple stations. To investigate the effects of limited frequency bandwidth, I recalculate the corner frequencies after progressively decimating the sample rate. Decreasing the high-frequency limit of the bandwidth decreases the estimate of the corner frequency (and stress drop). The corner frequency may be underestimated if it is within a factor of 3 of the maximum frequency of the signal.

  19. Dual electrospray ionization source for confident generation of accurate mass tags using liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Nepomuceno, Angelito I; Muddiman, David C; Bergen, H Robert; Craighead, James R; Burke, Michael J; Caskey, Patrick E; Allan, Jonathan A

    2003-07-15

    Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) has rapidly established a prominent role in proteomics because of its unparalleled resolving power, sensitivity and ability to achieve high mass measurement accuracy (MMA) simultaneously. However, space-charge effects must be quantitatively, routinely, and confidently corrected because they are known to profoundly influence MMA. We argue that the most effective way to account for space-charge effects is to introduce an internal mass calibrant (IMC) using a dual electrospray ionization (ESI) source where the IMC is added from a separate ESI emitter. The major disadvantage of our initial dual ESI source to achieve high MMA, and arguably the only one, was the time required to switch between the analyte emitter and IMC emitter (i.e., >300 ms). While this "switching time" was acceptable for direct infusion experiments, it did not lend itself to high-throughput applications or when conducting on-line liquid separations. In this report, we completely redesigned the dual ESI source and demonstrate several key attributes. First, the new design allows for facile alignment of ESI emitters, undetectable vibration, and the ability to extend to multiple emitters. Second, the switching time was reduced to <50 ms, which allowed the analyte and IMC to be accumulated "simultaneously" in the external ion reservoir and injected as a single ion packet into the ion cyclotron resonance cell, eliminating the need for a separate accumulation and ion injection event for the IMC. Third, by using a high concentration of the IMC, the residence time on this emitter could be reduced to approximately 80 ms, allowing for more time spent accumulating analyte ions of significantly lower concentration. Fourth, multiplexed on-line separations can be carried out providing increased throughput. Specifically, the new dual ESI source has demonstrated its ability to produce a stable ion current over a 45-min time period at 7 T

  20. Fast and accurate Monte Carlo modeling of a kilovoltage X-ray therapy unit using a photon-source approximation for treatment planning in complex media

    PubMed Central

    Zeinali-Rafsanjani, B.; Mosleh-Shirazi, M. A.; Faghihi, R.; Karbasi, S.; Mosalaei, A.

    2015-01-01

    To accurately recompute dose distributions in chest-wall radiotherapy with 120 kVp kilovoltage X-rays, an MCNP4C Monte Carlo model is presented using a fast method that obviates the need to fully model the tube components. To validate the model, half-value layer (HVL), percentage depth doses (PDDs) and beam profiles were measured. Dose measurements were performed for a more complex situation using thermoluminescence dosimeters (TLDs) placed within a Rando phantom. The measured and computed first and second HVLs were 3.8, 10.3 mm Al and 3.8, 10.6 mm Al, respectively. The differences between measured and calculated PDDs and beam profiles in water were within 2 mm/2% for all data points. In the Rando phantom, differences for majority of data points were within 2%. The proposed model offered an approximately 9500-fold reduced run time compared to the conventional full simulation. The acceptable agreement, based on international criteria, between the simulations and the measurements validates the accuracy of the model for its use in treatment planning and radiobiological modeling studies of superficial therapies including chest-wall irradiation using kilovoltage beam. PMID:26170553

  1. Seismotectonics of Western Turkey: A Synthesis of Source Parameters and Rupture Histories of Recent Earthquakes

    NASA Astrophysics Data System (ADS)

    Taymaz, T.; Tan, O.; Yolsal, S.

    2004-12-01

    The Aegean region, including western Turkey and Greece, is indeed one of the most seismically active and rapidly deforming continental domains in the Earth. The wide range of deformational processes occurring in this region means that the eastern Mediterranean provides a unique opportunity to improve our understanding of the complex kinematics of continental collision, including strike-slip faulting and crustal extension, as well as associated seismicity and volcanism. The tectonic evolution of the Eastern Mediterranean region is dominated by effects of subduction along the Hellenic (Aegean) arc and of continental collision in eastern Anatolia and the Caucasus. Northward subduction of the African plate beneath western Anatolia and the Aegean region is causing crustal extension in the overlying Aegean province. The interplay between dynamic effects of the relative motions of adjoining plates thus controls large-scale crustal deformation and the associated earthquake activity in Turkey. The Aegean region has been subject to extension since Miocene time, and this extension has left a pronounced expression in the present-day topography. It is further widely accepted that the rapid extension observed in western Turkey is mainly accommodated by large active normal faults that control the geomorphology which is dominated by a series of E-W trending normal-fault-bounded horst and graben structures; the N-S extension inferred from these structures is consistent with regional earthquake focal mechanisms. The E-W trending Menderes graben, the NE-SW trending Burdur, Acigol and Baklan, and NW-SE trending Dinar and Sultandag-Aksehir basins all bounded by large faults form a system of half-graben whose orientation is evident in both the topography and the tilting of Neogene sediments adjacent to them. We have studied source mechanisms and rupture histories of ˜20 earthquakes using body-waveform modelling, and have compared the shapes and amplitudes of teleseismic long-period P

  2. Inversion of Source and Transport Parameters of Relativistic SEPs from Neutron Monitor Data

    NASA Astrophysics Data System (ADS)

    Agueda, Neus; Bütikofer, Rolf; Vainio, Rami; Heber, Bernd; Afanasiev, Alexander; Malandraki, Olga E.

    2016-04-01

    We present a new methodology to study the release processes of relativistic solar energetic particles (SEPs) based on the direct inversion of Ground Level Enhancements (GLEs) observed by the worldwide network of neutron monitors (NMs). The new approach makes use of several models, including: the propagation of relativistic SEPs from the Sun to the Earth, their transport in the Earth's magnetosphere and atmosphere, as well as the detection of the nucleon component of the secondary cosmic rays by ground based NMs. The combination of these models allows us to compute the expected ground-level NM counting rates for a series of instantaneous releases from the Sun. The amplitudes of the source components are then inferred by fitting the NM observations with the modeled NM counting rate increases. Within the HESPERIA project, we will develop the first software package for the direct inversion of GLEs and we will make it freely available for the solar and heliospheric communities. Acknowledgement: This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 637324.

  3. Constraints on the source parameters of low-frequency earthquakes on the San Andreas Fault

    NASA Astrophysics Data System (ADS)

    Thomas, Amanda M.; Beroza, Gregory C.; Shelly, David R.

    2016-02-01

    Low-frequency earthquakes (LFEs) are small repeating earthquakes that occur in conjunction with deep slow slip. Like typical earthquakes, LFEs are thought to represent shear slip on crustal faults, but when compared to earthquakes of the same magnitude, LFEs are depleted in high-frequency content and have lower corner frequencies, implying longer duration. Here we exploit this difference to estimate the duration of LFEs on the deep San Andreas Fault (SAF). We find that the M ~ 1 LFEs have typical durations of ~0.2 s. Using the annual slip rate of the deep SAF and the average number of LFEs per year, we estimate average LFE slip rates of ~0.24 mm/s. When combined with the LFE magnitude, this number implies a stress drop of ~104 Pa, 2 to 3 orders of magnitude lower than ordinary earthquakes, and a rupture velocity of 0.7 km/s, 20% of the shear wave speed. Typical earthquakes are thought to have rupture velocities of ~80-90% of the shear wave speed. Together, the slow rupture velocity, low stress drops, and slow slip velocity explain why LFEs are depleted in high-frequency content relative to ordinary earthquakes and suggest that LFE sources represent areas capable of relatively higher slip speed in deep fault zones. Additionally, changes in rheology may not be required to explain both LFEs and slow slip; the same process that governs the slip speed during slow earthquakes may also limit the rupture velocity of LFEs.

  4. Underground Test Area Subproject Phase I Data Analysis Task. Volume V - Transport Parameter and Source Term Data Documentation Package

    SciTech Connect

    1996-12-01

    Volume V of the documentation for the Phase I Data Analysis Task performed in support of the current Regional Flow Model, Transport Model, and Risk Assessment for the Nevada Test Site Underground Test Area Subproject contains the transport parameter and source term data. Because of the size and complexity of the model area, a considerable quantity of data was collected and analyzed in support of the modeling efforts. The data analysis task was consequently broken into eight subtasks, and descriptions of each subtask's activities are contained in one of the eight volumes that comprise the Phase I Data Analysis Documentation.

  5. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, Natalia G.; Prejean, Stephanie G.; Hansen, Roger A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field.

  6. Seismic swarm associated with the 2008 eruption of Kasatochi Volcano, Alaska: Earthquake locations and source parameters

    USGS Publications Warehouse

    Ruppert, N.A.; Prejean, S.; Hansen, R.A.

    2011-01-01

    An energetic seismic swarm accompanied an eruption of Kasatochi Volcano in the central Aleutian volcanic arc in August of 2008. In retrospect, the first earthquakes in the swarm were detected about 1 month prior to the eruption onset. Activity in the swarm quickly intensified less than 48 h prior to the first large explosion and subsequently subsided with decline of eruptive activity. The largest earthquake measured as moment magnitude 5.8, and a dozen additional earthquakes were larger than magnitude 4. The swarm exhibited both tectonic and volcanic characteristics. Its shear failure earthquake features were b value = 0.9, most earthquakes with impulsive P and S arrivals and higher-frequency content, and earthquake faulting parameters consistent with regional tectonic stresses. Its volcanic or fluid-influenced seismicity features were volcanic tremor, large CLVD components in moment tensor solutions, and increasing magnitudes with time. Earthquake location tests suggest that the earthquakes occurred in a distributed volume elongated in the NS direction either directly under the volcano or within 5-10 km south of it. Following the MW 5.8 event, earthquakes occurred in a new crustal volume slightly east and north of the previous earthquakes. The central Aleutian Arc is a tectonically active region with seismicity occurring in the crusts of the Pacific and North American plates in addition to interplate events. We postulate that the Kasatochi seismic swarm was a manifestation of the complex interaction of tectonic and magmatic processes in the Earth's crust. Although magmatic intrusion triggered the earthquakes in the swarm, the earthquakes failed in context of the regional stress field. Copyright ?? 2011 by the American Geophysical Union.

  7. Improved source parameter constraints for five undersea earthquakes from north component of GRACE gravity and gravity gradient change measurements

    NASA Astrophysics Data System (ADS)

    Dai, Chunli; Shum, C. K.; Guo, Junyi; Shang, Kun; Tapley, Byron; Wang, Rongjiang

    2016-06-01

    The innovative processing of Gravity Recovery And Climate Experiment (GRACE) data using only the north component of gravity change and its corresponding gravity gradient changes allows the enhancement of the spatial resolution for coseismic deformation signals. Here, we report the study of five undersea earthquakes using this technique: the 2004 Sumatra-Andaman earthquake, the 2007 Bengkulu earthquake, the 2010 Maule, Chile earthquake, the 2011 Tohoku earthquake, and the 2012 Indian Ocean earthquakes. By using the high spherical harmonic degree (up to degree 96) data products and the associated GRACE data processing techniques, the retrieved north component of gravity change is up to - 34 ± 1.4 μGal for the 2004 Sumatra-Andaman earthquake, which illustrates by far the highest amplitude of the coseismic signal retrieved from satellite gravimetry among previous studies. We creatively apply the localized spectral analysis as an efficient method to empirically determine the practical spherical harmonic truncation degree. By combining least squares adjustment with the simulated annealing algorithm, point source parameters are estimated, which demonstrates the unique constraint on source model from GRACE data compared to other data sources. For the 2004 Sumatra-Andaman earthquake, GRACE data produce a shallower centroid depth (9.1 km), as compared to the depth (28.3 km) from GPS data. For the 2011 Tohoku earthquake, the GRACE-estimated centroid location is southwest of the GPS/seismic solutions, and the slip orientation is about 10° clockwise from the published GPS/seismic slip models. We concluded that these differences demonstrate the additional and critical offshore constraint by GRACE on source parameters, as compared to GPS/seismic data.

  8. Uncertainty in local and regional tsunami earthquake source parameters: Implications for scenario based hazard assessment and forecasting

    NASA Astrophysics Data System (ADS)

    Müller, Christof; Power, William; Burbidge, David; Wang, Xiaoming

    2016-04-01

    Over the last decade tsunami propagation models have been used extensively for both tsunami forecasting, hazard and risk assessment. However, the effect of uncertainty in the earthquake source parameters, such as location and distribution of slip in the earthquake source on the results of the tsunami model has not always been examined in great detail. We have developed a preliminary combined and continuous Hikurangi-Kermadec subduction zone interface model. The model is defined by a spline surface and is based on a previously published spline model for Hikurangi interface and a more traditional unit source model for the Kermadec interface. The model allows to freely position and vary the earthquake epicenter and to consider non-uniform slip. Using this model we have investigated the effects of variability in non-uniform slip and epicenter location on the distribution of offshore maximum wave heights for local New Zealand targets. Which scenario out of an ensemble is responsible for the maximum wave height locally is a spatially highly variable function of earthquake location and/or the distribution of slip. We use the Coefficient of Variation (CoV) to quantify the variability of offshore wave heights as a function of source location and distribution of slip. CoV increases significantly with closer proximity to the shore, in bays and in shallow water. The study has implication for tsunami hazard assessment and forecasting. As an example, our results challenge the concept of hazard assessment using a single worst case scenario in particular for local tsunami.

  9. Site response for seattle and source parameters of earthquakes in the puget sound region

    USGS Publications Warehouse

    Frankel, A.; Carver, D.; Cranswick, E.; Meremonte, M.; Bice, T.; Overturf, D.

    1999-01-01

    We analyzed seismograms from 21 earthquakes (M(L) 2.0-4.9) recorded by digital seismographs we deployed in urban Seatte to determine site response and earthquake stress drops. The seismometers were situated on a wide variety of geologic units, including artificial fill (e.g., Kingdome, Harbor Island), Pleistocene age soils (glacial till and outwash deposits of Seattle's hills), modified land (downtown Seattle, Space Needle), and Tertiary sedimentary rock. Two mainshock-aftershock sequences were recorded: the June 1997 Bremerton sequence (mainshock M(L) 4.9) and the February 1997 South Seattle sequence (mainshock M(L) 3.5), along with other events in the Puget Sound region. We developed a new inversion procedure to estimate site response, source corner frequencies, and seismic moments from the S-wave spectra. This inversion uses corner frequencies determined from spectral ratios of mainshock-aftershock pairs as constraints. The site responses found from the inversion are not relative to the rock site but are relative to an idealized site with a flat frequency response. The response of the rock site is also found from the inversion. The inversion results show high response for the sites on artificial fill, more moderate amplication for most sites on stiff Pleistocene soils or modified land, and low response for the rock site. Some sites display resonances, such as a strong 2-Hz resonance at our site near the Kingdome, which is caused by the surficial layers of fill and younger alluvium. The sites in West Seattle exhibit high amplification, even though they are on relatively stiff soils of glacial outwash. This may be partly caused by basin surface waves produced by conversion of incident S waves. This high response in West Seattle is consistent with damage reports from the 1949 (m(b) 7.1) and 1965 (m(b) 6.5) earthquakes. Stress-drop estimates for the events we recorded were generally low, between 0.4 and 25 bars, although some of the events may have had higher stress

  10. Persistent inflation at Aira caldera accompanying explosive activity at Sakurajima volcano: Constraining deformation source parameters from Finite Element inversions

    NASA Astrophysics Data System (ADS)

    Hickey, James; Gottsmann, Jo; Iguchi, Masato; Nakamichi, Haruhisa

    2015-04-01

    Aira caldera is located within Kagoshima Bay at the southern end of Kyushu, Japan. Sakurajima is an active post-caldera andesitic stratovolcano that sits on the caldera's southern rim. Despite frequent Vulcanian-type explosive activity, the area is experiencing continued uplift at a maximum rate of approximately 1.5 cm/yr with a footprint of 40 km, indicating that magma is being supplied faster than it is erupted. This is of particular concern as the amplitude of deformation is approaching the level inferred prior to the 1914 VEI 4 eruption. Using GPS data from 1996 - 2007 we explore causes for the uplift. To solve for the optimum deformation source parameters we use an inverse Finite Element method accounting for three-dimensional material heterogeneity (inferred from seismic tomography) and the surrounding topography of the region. The same inversions are also carried out using Finite Element models that incorporate simplified homogeneous or one-dimensional subsurface material properties, with and without topography. Results from the comparison of the six different models show statistically significant differences in the inferred deformation sources. This indicates that both subsurface heterogeneity and surface topography are essential in geodetic modelling to extract the most realistic deformation source parameters. The current best-fit source sits within a seismic low-velocity zone in the north-east of the caldera at a depth of approximately 14 km with a volume increase of 1.2 x 108 m3. The source location underlies a region of active underwater fumaroles within the Wakamiko crater and differs significantly from previous analytical modelling results. Seismic data further highlights areas of high seismic attenuation as well as large aseismic zones, both of which could allude to inelastic behaviour and a significant heat source at depth. To integrate these observations, subsequent forward Finite Element models will quantify the importance of rheology and

  11. Characterization of the Virginia earthquake effects and source parameters from website traffic analysis

    NASA Astrophysics Data System (ADS)

    Bossu, R.; Lefebvre, S.; Mazet-Roux, G.; Roussel, F.

    2012-12-01

    of inhabitants than localities having experienced weak ground motion. In other words, we observe higher proportion of visitors from localities where the earthquake was widely felt when compared to localities where it was scarcely felt. This opens the way to automatically map the relative level of shaking within minutes of an earthquake's occurrence. In conclusion, the study of the Virginia earthquake shows that eyewitnesses' visits to our website follow the arrival of the P waves at their location. This further demonstrates the real time public desire of information after felt earthquakes, a parameter which should be integrated in the definition of earthquake information services. It also reveals additional capabilities of the flashsourcing method. Earthquakes felt at large distances i.e. where the propagation time to the most distant eyewitnesses exceeds a couple of minutes, can be located and their magnitude estimated in a time frame comparable to the one of automatic seismic locations by real time seismic networks. It also provides very rapid indication on the effects of the earthquakes, by mapping the felt area, detecting the localities affected by network disruption and mapping the relative level of shaking. Such information are essential to improve situation awareness, constrain real time scenario and in in turn, contribute to improved earthquake response.

  12. Effect of discharge parameters on emission yields in a radio-frequency glow-discharge atomic-emission source

    NASA Astrophysics Data System (ADS)

    Parker, Mark; Hartenstein, Matthew L.; Marcus, R. Kenneth

    1997-05-01

    A study is performed on a radio-frequency glow-discharge atomic-emission (rf-GD-AES) source to determine the factors effecting the emission yields for both metallic and nonconductive sample types. Specifically, these studies focus on determining how the operating parameters (power and pressure) influence emission yields. The results follow predicted patterns as determined by Langmuir probe diagnostic studies of a similar source. In particular, discharge gas pressure is the key operating parameter as slight changes in pressure may significantly affect the emission yield of the analyte species. RF power is less important and is shown to produce only relatively small changes in the emission yield over the ranges typically used in rf-GD analyses. These studies indicate that the quantitative analysis of layered materials, depth-profiling, may be adversely affected if the data collection scheme, i.e. the quantitative algorithm, requires changing the pressure during an analysis to keep the operating current and voltage constant. A direct relationship is shown to exist between the Ar (discharge gas) emission intensity and that of sputtered species for nonconductors. This observance is used to compensate for differences in emission intensities observed in the analysis of various thickness nonconductive samples. The sputtered element emission signals are corrected based on the emission intensity of an Ar (1) transition, implying that quantitative analysis of nonconductive samples is not severely limited by the availability of matrix matched standards.

  13. Effect of basic physical parameters to control plasma meniscus and beam halo formation in negative ion sources

    SciTech Connect

    Miyamoto, K.; Okuda, S.; Nishioka, S.; Hatayama, A.

    2013-09-14

    Our previous study shows that the curvature of the plasma meniscus causes the beam halo in the negative ion sources: the negative ions extracted from the periphery of the meniscus are over-focused in the extractor due to the electrostatic lens effect, and consequently become the beam halo. In this article, the detail physics of the plasma meniscus and beam halo formation is investigated with two-dimensional particle-in-cell simulation. It is shown that the basic physical parameters such as the H{sup −} extraction voltage and the effective electron confinement time significantly affect the formation of the plasma meniscus and the resultant beam halo since the penetration of electric field for negative ion extraction depends on these physical parameters. Especially, the electron confinement time depends on the characteristic time of electron escape along the magnetic field as well as the characteristic time of electron diffusion across the magnetic field. The plasma meniscus penetrates deeply into the source plasma region when the effective electron confinement time is short. In this case, the curvature of the plasma meniscus becomes large, and consequently the fraction of the beam halo increases.

  14. The effect of wind and eruption source parameter variations on tephra fallout hazard assessment: an example from Vesuvio (Italy)

    NASA Astrophysics Data System (ADS)

    Macedonio, Giovanni; Costa, Antonio; Scollo, Simona; Neri, Augusto

    2015-04-01

    Uncertainty in the tephra fallout hazard assessment may depend on different meteorological datasets and eruptive source parameters used in the modelling. We present a statistical study to analyze this uncertainty in the case of a sub-Plinian eruption of Vesuvius of VEI = 4, column height of 18 km and total erupted mass of 5 × 1011 kg. The hazard assessment for tephra fallout is performed using the advection-diffusion model Hazmap. Firstly, we analyze statistically different meteorological datasets: i) from the daily atmospheric soundings of the stations located in Brindisi (Italy) between 1962 and 1976 and between 1996 and 2012, and in Pratica di Mare (Rome, Italy) between 1996 and 2012; ii) from numerical weather prediction models of the National Oceanic and Atmospheric Administration and of the European Centre for Medium-Range Weather Forecasts. Furthermore, we modify the total mass, the total grain-size distribution, the eruption column height, and the diffusion coefficient. Then, we quantify the impact that different datasets and model input parameters have on the probability maps. Results shows that the parameter that mostly affects the tephra fallout probability maps, keeping constant the total mass, is the particle terminal settling velocity, which is a function of the total grain-size distribution, particle density and shape. Differently, the evaluation of the hazard assessment weakly depends on the use of different meteorological datasets, column height and diffusion coefficient.

  15. Analysis of Micro-Seismic Signals and Source Parameters of Eruptions Generated by Rapid Decompression of Volcanic Rocks

    NASA Astrophysics Data System (ADS)

    Arciniega-Ceballos, A.; Alatorre-Ibarguengoitia, M. A.; Scheu, B.; Dingwell, D. B.; Delgado Granados, H.

    2010-12-01

    Seismic evaluation of well-controlled experimental volcanic simulations offers the hope of a better understanding of source mechanisms in natural volcanic seismicity. Here, we have performed the first investigation of the dynamics of explosive volcanic eruption of magma under controlled laboratory conditions. Specifically, we analyzed the micro-seismicity generated by the rapid depressurization of volcanic rocks in a shock tube apparatus, which represents the seismic mechanism. The source parameters and the force system have been analyzed considering the relationship F=πr2 Po. Our well-constrained physical mechanism consists of the slow pressurization of the system (using Argon gas) followed by rapid depressurization of natural volcanic samples (ash, pumice and fragmented particles of pumice) contained in a steel pipe-like conduit of radius r and height ~2r. Several experiments with samples with different porosities were performed under controlled pressure conditions (ranging from 4 to 20 MPa), at room temperature. We calculated the magnitude of the vertical and downward forces and forces at the walls of the reservoir, and the kinetic energy involved during decompression and fragmentation processes from the micro-seismic signals detected at several points in the apparatus using highly dynamic piezo-film transducers. We first characterized the frequencies of the apparatus in order to distinguish in the signals between the waves produced by the natural resonance of the system due to the pressure shock and the waves generated by the rapid depressurization of the samples. In the micro-seismic records the inflation-deflation states of the pipe-like conduit and the fragmentation process after the rapid removal of the diaphragm can be recognized clearly. The decompression time is directly measured from the pressure drop curves of the system recorded by dynamic pressure transducers and correlates well with the duration of maximum amplitudes of micro-seismic waves

  16. Shot noise effect on noise source and noise parameter of 10-nm-scale quasi-ballistic n-/p-type MOS devices

    NASA Astrophysics Data System (ADS)

    Jeon, Jongwook; Kang, Myounggon

    2016-05-01

    In this work, we investigated the noise source and noise parameters of a quasi-ballistic MOSFET at the high-frequency regime. We presented the shot noise properties in the measured drain current noise and its impact on the induced gate noise and the noise parameters of 10-nm-scale n-/p-type MOS (N/PMOS) devices for the first time. The measured noise sources and noise parameters were carefully analyzed with the shot and thermal noise models in all operation regions. On the basis of the results, new noise parameter models are proposed and the noise performance improvement in the quasi-ballistic regime is shown.

  17. Multi-parameter high-resolution lithospheric imaging by source-independent full-waveform inversion of teleseismic data

    NASA Astrophysics Data System (ADS)

    Beller, S.; Monteiller, V.; Operto, S.; Nolet, G.

    2015-12-01

    Building broadband multi-parameter lithospheric models is one of the quest of earthquake seismology. Nowadays, deployment of dense arrays of broadband stations and advances in high-performance computing open new perspectives to achieve this goal by full waveform inversion (FWI) of teleseismic data. Compared to traveltime tomography, broadband images can be obtained by FWI when wavefields that are forward-scattered (i.e., transmission regime) and backward-scattered (reflection regime) by lithospheric heterogeneties to be imaged are involved in the inversion. In teleseismic setting, incident wavefields impinge the boundaries of the lithospheric target and propagate up to the surface where they are recorded by the stations, giving rise to the transmitted part of the recorded wavefield. The incident wavefield is also reflected back into the lithospheric target by the free surface acting as P- and S-waves secondary sources. The resulting wavefield is reflected by the lithospheric reflectors before being recorded by the stations, giving rise to the second-order reflection part of the recorded wavefield. While the transmitted part of the wavefield allows one to achieve a resolution close to that obtained by traveltime tomography, involving the reflected part of the wavefield in the FWI is amenable to the short-wavelength updates, hence broadaning the wavenumber spectrum of the lithospheric models toward high wavenumbers. Another benefit to involve the reflection regime in FWI is to increase the sensitivity of the FWI to the density parameter. In this study, we first discuss the feasibility of the density reconstruction in addition to that of the P- and S-waves velocities by FWI of teleseismic wavefields with a realistic synthetic study representative of the western Alps. The density reconstruction implies the extraction of information given by small amplitude secondary wavefields from the data that may be drastically affected by noise and trade-off between model parameter

  18. Plasma diagnosis as a tool for the determination of the parameters of electron beam evaporation and sources of ionization

    NASA Astrophysics Data System (ADS)

    Mukherjee, Jaya; Dileep Kumar, V.; Yadav, S. P.; Barnwal, Tripti A.; Dikshit, Biswaranjan

    2016-07-01

    The atomic vapor generated by electron beam heating is partially ionized due to atom–atom collisions (Saha ionization) and electron impact ionization, which depend upon the source temperature and area of evaporation as compared to the area of electron beam bombardment on the target. When electron beam evaporation is carried out by inserting the target inside an insulating liner to reduce conductive heat loss, it is expected that the area of evaporation becomes significantly more than the area of electron beam bombardment on the target, resulting in reduced electron impact ionization. To assess this effect and to quantify the parameters of evaporation, such as temperature and area of evaporation, we have carried out experiments using zirconium, tin and aluminum as a target. By measuring the ion content using a Langmuir probe, in addition to measuring the atomic vapor flux at a specific height, and by combining the experimental data with theoretical expressions, we have established a method for simultaneously inferring the source temperature, evaporation area and ion fraction. This assumes significance because the temperature cannot be reliably measured by an optical pyrometer due to the wavelength dependent source emissivity and reflectivity of thin film mirrors. In addition, it also cannot be inferred from only the atomic flux data at a certain height as the area of evaporation is unknown (it can be much more than the area of electron bombardment, especially when the target is placed in a liner). Finally, the reason for the lower observed electron temperatures of the plasma for all the three cases is found to be the energy loss due to electron impact excitation of the atomic vapor during its expansion from the source.

  19. Plasma diagnosis as a tool for the determination of the parameters of electron beam evaporation and sources of ionization

    NASA Astrophysics Data System (ADS)

    Mukherjee, Jaya; Dileep Kumar, V.; Yadav, S. P.; Barnwal, Tripti A.; Dikshit, Biswaranjan

    2016-07-01

    The atomic vapor generated by electron beam heating is partially ionized due to atom-atom collisions (Saha ionization) and electron impact ionization, which depend upon the source temperature and area of evaporation as compared to the area of electron beam bombardment on the target. When electron beam evaporation is carried out by inserting the target inside an insulating liner to reduce conductive heat loss, it is expected that the area of evaporation becomes significantly more than the area of electron beam bombardment on the target, resulting in reduced electron impact ionization. To assess this effect and to quantify the parameters of evaporation, such as temperature and area of evaporation, we have carried out experiments using zirconium, tin and aluminum as a target. By measuring the ion content using a Langmuir probe, in addition to measuring the atomic vapor flux at a specific height, and by combining the experimental data with theoretical expressions, we have established a method for simultaneously inferring the source temperature, evaporation area and ion fraction. This assumes significance because the temperature cannot be reliably measured by an optical pyrometer due to the wavelength dependent source emissivity and reflectivity of thin film mirrors. In addition, it also cannot be inferred from only the atomic flux data at a certain height as the area of evaporation is unknown (it can be much more than the area of electron bombardment, especially when the target is placed in a liner). Finally, the reason for the lower observed electron temperatures of the plasma for all the three cases is found to be the energy loss due to electron impact excitation of the atomic vapor during its expansion from the source.

  20. Reducing fluxes of faecal indicator compliance parameters to bathing waters from diffuse agricultural sources: the Brighouse Bay study, Scotland.

    PubMed

    Kay, D; Aitken, M; Crowther, J; Dickson, I; Edwards, A C; Francis, C; Hopkins, M; Jeffrey, W; Kay, C; McDonald, A T; McDonald, D; Stapleton, C M; Watkins, J; Wilkinson, J; Wyer, M D

    2007-05-01

    The European Water Framework Directive requires the integrated management of point and diffuse pollution to achieve 'good' water quality in 'protected areas'. These include bathing waters, which are regulated using faecal indicator organisms as compliance parameters. Thus, for the first time, European regulators are faced with the control of faecal indicator fluxes from agricultural sources where these impact on bathing water compliance locations. Concurrently, reforms to the European Union (EU) Common Agricultural Policy offer scope for supporting on-farm measures producing environmental benefits through the new 'single farm payments' and the concept of 'cross-compliance'. This paper reports the first UK study involving remedial measures, principally stream bank fencing, designed to reduce faecal indicator fluxes at the catchment scale. Considerable reduction in faecal indicator flux was observed, but this was insufficient to ensure bathing water compliance with either Directive 76/160/EEC standards or new health-evidence-based criteria proposed by WHO and the European Commission.

  1. BluePyOpt: Leveraging Open Source Software and Cloud Infrastructure to Optimise Model Parameters in Neuroscience

    PubMed Central

    Van Geit, Werner; Gevaert, Michael; Chindemi, Giuseppe; Rössert, Christian; Courcol, Jean-Denis; Muller, Eilif B.; Schürmann, Felix; Segev, Idan; Markram, Henry

    2016-01-01

    At many scales in neuroscience, appropriate mathematical models take the form of complex dynamical systems. Parameterizing such models to conform to the multitude of available experimental constraints is a global non-linear optimisation problem with a complex fitness landscape, requiring numerical techniques to find suitable approximate solutions. Stochastic optimisation approaches, such as evolutionary algorithms, have been shown to be effective, but often the setting up of such optimisations and the choice of a specific search algorithm and its parameters is non-trivial, requiring domain-specific expertise. Here we describe BluePyOpt, a Python package targeted at the broad neuroscience community to simplify this task. BluePyOpt is an extensible framework for data-driven model parameter optimisation that wraps and standardizes several existing open-source tools. It simplifies the task of creating and sharing these optimisations, and the associated techniques and knowledge. This is achieved by abstracting the optimisation and evaluation tasks into various reusable and flexible discrete elements according to established best-practices. Further, BluePyOpt provides methods for setting up both small- and large-scale optimisations on a variety of platforms, ranging from laptops to Linux clusters and cloud-based compute infrastructures. The versatility of the BluePyOpt framework is demonstrated by working through three representative neuroscience specific use cases. PMID:27375471

  2. BluePyOpt: Leveraging Open Source Software and Cloud Infrastructure to Optimise Model Parameters in Neuroscience.

    PubMed

    Van Geit, Werner; Gevaert, Michael; Chindemi, Giuseppe; Rössert, Christian; Courcol, Jean-Denis; Muller, Eilif B; Schürmann, Felix; Segev, Idan; Markram, Henry

    2016-01-01

    At many scales in neuroscience, appropriate mathematical models take the form of complex dynamical systems. Parameterizing such models to conform to the multitude of available experimental constraints is a global non-linear optimisation problem with a complex fitness landscape, requiring numerical techniques to find suitable approximate solutions. Stochastic optimisation approaches, such as evolutionary algorithms, have been shown to be effective, but often the setting up of such optimisations and the choice of a specific search algorithm and its parameters is non-trivial, requiring domain-specific expertise. Here we describe BluePyOpt, a Python package targeted at the broad neuroscience community to simplify this task. BluePyOpt is an extensible framework for data-driven model parameter optimisation that wraps and standardizes several existing open-source tools. It simplifies the task of creating and sharing these optimisations, and the associated techniques and knowledge. This is achieved by abstracting the optimisation and evaluation tasks into various reusable and flexible discrete elements according to established best-practices. Further, BluePyOpt provides methods for setting up both small- and large-scale optimisations on a variety of platforms, ranging from laptops to Linux clusters and cloud-based compute infrastructures. The versatility of the BluePyOpt framework is demonstrated by working through three representative neuroscience specific use cases. PMID:27375471

  3. The Source Parameters of Echolocation Clicks from Captive and Free-Ranging Yangtze Finless Porpoises (Neophocaena asiaeorientalis asiaeorientalis)

    PubMed Central

    Fang, Liang; Wang, Ding; Li, Yongtao; Cheng, Zhaolong; Pine, Matthew K.; Wang, Kexiong; Li, Songhai

    2015-01-01

    The clicks of Yangtze finless porpoises (Neophocaena asiaeorientalis asiaeorientalis) from 7 individuals in the tank of Baiji aquarium, 2 individuals in a netted pen at Shishou Tian-e-zhou Reserve and 4 free-ranging individuals at Tianxingzhou were recorded using a broadband digital recording system with four element hydrophones. The peak-to-peak apparent source level (ASL_pp) of clicks from individuals at the Baiji aquarium was 167 dB re 1 μPa with mean center frequency of 133 kHz, -3dB bandwidth of 18 kHz and -10 dB duration of 58 μs. The ASL_pp of clicks from individuals at the Shishou Tian-e-zhou Reserve was 180 dB re 1 μPa with mean center frequency of 128 kHz, -3dB bandwidth of 20 kHz and -10 dB duration of 39 μs. The ASL_pp of clicks from individuals at Tianxingzhou was 176 dB re 1 μPa with mean center frequency of 129 kHz, -3dB bandwidth of 15 kHz and -10 dB duration of 48 μs. Differences between the source parameters of clicks among the three groups of finless porpoises suggest these animals adapt to their echolocation signals depending on their surroundings. PMID:26053758

  4. Parameter uncertainty analysis of the non-point source pollution in the Daning River watershed of the Three Gorges Reservoir Region, China.

    PubMed

    Shen, Zhenyao; Hong, Qian; Yu, Hong; Liu, Ruimin

    2008-11-01

    The generation and formation of non-point source pollution involves great uncertainty, and this uncertainty makes monitoring and controlling pollution very difficult. Understanding the main parameters that affect non-point source pollution uncertainty is necessary to provide the basis for the planning and design of control measures. In this study, three methods were adopted to do the parameter uncertainty analysis with the Soil and Water Assessment Tool (SWAT). Based on the results of parameter sensitivity analysis by the Morris screening method, the ten parameters that most affect runoff, sediment, organic N, nitrate, and total phosphorous (TP) were chosen for further uncertainty analysis. First-order error analysis (FOEA) and the Monte Carlo method (MC) were used to analyze the effect of parameter uncertainty on model outputs. FOEA results showed that only a few parameters had significantly affected the uncertainty of the final simulation results, and many parameters had little or no effect. The SCS curve number was the parameter with significant uncertainty impact on runoff, sediment, organic N, nitrate and TP, and it showed that the runoff process was mainly responsible for the uncertainty of non-point source pollution load. The uncertainty of sediment was the biggest among the five model output results described above. MC results indicated that neglecting the parameter uncertainty of the model would underestimate the non-point source pollution load, and that the relationship between model input and output was non-linear. The uncertainty of non-point source pollution exhibited a temporal pattern: It was greater in summer than in winter. The uncertainty of runoff was smaller compared to that of sediment, organic N, nitrate, and TP, and the source of uncertainty was mainly affected by parameters associated with runoff. PMID:18639918

  5. Meat quality, oxidative stability and blood parameters from Graylag geese offered alternative fiber sources in growing period.

    PubMed

    He, L W; Meng, Q X; Li, D Y; Zhang, Y W; Ren, L P

    2015-04-01

    The effects of dietary fiber sources on the meat quality, oxidative stability, and blood parameters of growing Graylag geese (28-112d) were investigated. The birds were randomly allocated into 4 treatments, of which dietary fiber was mainly from corn straw silage (CSS), steam-exploded corn straw (SECS), steam-exploded wheat straw (SEWS), and steam-exploded rice straw (SERS). No influence (P>0.05) on the basic chemical components, oxidative stability, or organoleptic traits of muscle were observed, except that birds fed SECS had a higher (P<0.05) protein proportion than those fed CSS or SERS, and CSS increased (P<0.01) the cholesterol content when compared to SEWS or SERS. Regarding fatty acid profile in meat, CSS and SECS increased (P<0.01) the proportion of C18:2n6t and decreased that of C21:0 and C22:0 when compared to the others. The birds fed SERS had a higher (P<0.05) proportion of C20:0 and C22:0 than the others, a higher proportion of C20:5n3, n-3 fatty acids, Δ-9 desaturase (18) index compared to those fed CSS or SECS, and a lower (P<0.01) proportion of C20:1n9 than those fed SECS or SEWS. Additionally, SEWS resulted in a higher (P<0.01) proportion of C20:2 when compared to the others. In conclusion, these fibers affect just the protein proportion, cholesterol content, and fatty acid profile of breast muscle, along with the concentration of TG and MDA in blood, but not the other characteristics. No superior fiber source exists with respect to meat quality, suggesting that Graylag geese feeding should make the most economically of the convenient fiber source with appropriate pretreatment. PMID:25717090

  6. Source Parameter Inversion for Recent Great Earthquakes from a Decade-long Observation of Global Gravity Fields

    NASA Technical Reports Server (NTRS)

    Han, Shin-Chan; Riva, Ricccardo; Sauber, Jeanne; Okal, Emile

    2013-01-01

    We quantify gravity changes after great earthquakes present within the 10 year long time series of monthly Gravity Recovery and Climate Experiment (GRACE) gravity fields. Using spherical harmonic normal-mode formulation, the respective source parameters of moment tensor and double-couple were estimated. For the 2004 Sumatra-Andaman earthquake, the gravity data indicate a composite moment of 1.2x10(exp 23)Nm with a dip of 10deg, in agreement with the estimate obtained at ultralong seismic periods. For the 2010 Maule earthquake, the GRACE solutions range from 2.0 to 2.7x10(exp 22)Nm for dips of 12deg-24deg and centroid depths within the lower crust. For the 2011 Tohoku-Oki earthquake, the estimated scalar moments range from 4.1 to 6.1x10(exp 22)Nm, with dips of 9deg-19deg and centroid depths within the lower crust. For the 2012 Indian Ocean strike-slip earthquakes, the gravity data delineate a composite moment of 1.9x10(exp 22)Nm regardless of the centroid depth, comparing favorably with the total moment of the main ruptures and aftershocks. The smallest event we successfully analyzed with GRACE was the 2007 Bengkulu earthquake with M(sub 0) approx. 5.0x10(exp 21)Nm. We found that the gravity data constrain the focal mechanism with the centroid only within the upper and lower crustal layers for thrust events. Deeper sources (i.e., in the upper mantle) could not reproduce the gravity observation as the larger rigidity and bulk modulus at mantle depths inhibit the interior from changing its volume, thus reducing the negative gravity component. Focal mechanisms and seismic moments obtained in this study represent the behavior of the sources on temporal and spatial scales exceeding the seismic and geodetic spectrum.

  7. Meat quality, oxidative stability and blood parameters from Graylag geese offered alternative fiber sources in growing period.

    PubMed

    He, L W; Meng, Q X; Li, D Y; Zhang, Y W; Ren, L P

    2015-04-01

    The effects of dietary fiber sources on the meat quality, oxidative stability, and blood parameters of growing Graylag geese (28-112d) were investigated. The birds were randomly allocated into 4 treatments, of which dietary fiber was mainly from corn straw silage (CSS), steam-exploded corn straw (SECS), steam-exploded wheat straw (SEWS), and steam-exploded rice straw (SERS). No influence (P>0.05) on the basic chemical components, oxidative stability, or organoleptic traits of muscle were observed, except that birds fed SECS had a higher (P<0.05) protein proportion than those fed CSS or SERS, and CSS increased (P<0.01) the cholesterol content when compared to SEWS or SERS. Regarding fatty acid profile in meat, CSS and SECS increased (P<0.01) the proportion of C18:2n6t and decreased that of C21:0 and C22:0 when compared to the others. The birds fed SERS had a higher (P<0.05) proportion of C20:0 and C22:0 than the others, a higher proportion of C20:5n3, n-3 fatty acids, Δ-9 desaturase (18) index compared to those fed CSS or SECS, and a lower (P<0.01) proportion of C20:1n9 than those fed SECS or SEWS. Additionally, SEWS resulted in a higher (P<0.01) proportion of C20:2 when compared to the others. In conclusion, these fibers affect just the protein proportion, cholesterol content, and fatty acid profile of breast muscle, along with the concentration of TG and MDA in blood, but not the other characteristics. No superior fiber source exists with respect to meat quality, suggesting that Graylag geese feeding should make the most economically of the convenient fiber source with appropriate pretreatment.

  8. Investigating earthquake self-similarity using a 20 year catalog of source parameters derived from InSAR data

    NASA Astrophysics Data System (ADS)

    Funning, G.; Ferreira, A. M.; Weston, J. M.; Bloomfield, H.

    2013-12-01

    The question of how moment release in earthquakes scales to other earthquake source parameters, such as fault length and average slip, is a long-standing controversy (e.g. Scholz, 1982, 1994; Romanowicz, 1992). It is a problem that speaks to issues of earthquake source mechanics, specifically the self-similarity of earthquakes - is stress drop constant across all magnitudes? Theoretically, two end-member scaling models have been proposed - the so-called ';W-model', whereby seismic moment scales linearly with fault length, and the alternative ';L-model', where moment scales with the square of fault length. Existing data on earthquake rupture dimensions, typically from field observations or aftershock locations, do not conclusively favor one over the other. A W-model implies a constant stress drop for all earthquakes in the same tectonic setting, and therefore that earthquakes are self-similar. The L-model does not imply self-similarity, but is consistent with the idea that ';large earthquakes' (i.e. earthquakes that rupture the full thickness of the brittle upper crust) grow by increasing their rupture length, with average slip being proportional to fault length. To address this problem, we use a compilation of source parameter information from over 130 published studies of 101 individual earthquakes (Mw 4.7-9.0) studied using InSAR. There are several reasons to suggest that this information will be highly suitable for the study of earthquake scaling. The high spatial resolution and centimetric precision of InSAR data provide strong constraints on estimates of fault length and slip. In addition, in a previous study, we found good agreement between moment estimates from InSAR studies and the Global CMT catalog, derived from long-period seismic data (Weston et al., 2011). Considering events of all mechanisms together, we find a scaling relationship between moment (M0) and fault length (L), such that M0 ∝ L1.8. We find differences in this power law exponent with

  9. simpegEM: An open-source resource for simulation and parameter estimation problems in electromagnetic geophysics

    NASA Astrophysics Data System (ADS)

    Heagy, L. J.; Cockett, R.; Kang, S.; Rosenkjaer, G. K.; Oldenburg, D.

    2015-12-01

    A large suite of problems in applied geophysics can be tackled by simulating and inverting electromagnetic (EM) data. Problems can be treated in the time- or frequency-domain, sources can be magnetic or electric and either natural or controlled, techniques such as primary-secondary may be employed and different problem dimensionalities, including 1D, 2D and 3D, may be considered. To address the inverse problem, derivatives of each of these element must be readily accessible so they may be composed to form the sensitivity for the approach taken. For many applications, efficient algorithms have been designed and implemented. However, inconsistencies between implementations of different problem-types and modeling techniques often limits extensibility and interoperability, particularly when addressing the inverse problem. Building on top of the open-source simulation and gradient based parameter estimation framework, SimPEG (http://simpeg.xyz), we have developed simpegEM to be a modular framework for geophysical problems in electromagnetics. The SimPEG implementation in Python provides finite-volume discretizations for both structured and semi-structured meshes, along with machinery for the inversion, including optimization and regularization routines. The elements of the EM simulation, including the formulation of Maxwell's equations and definitions of the sources and receivers as well as their derivatives are implemented in a modular, object-oriented manner. This structure and organization of the code allow elements to be readily interchanged and extensions made. In this presentation, we discuss an example with steel-cased wells. Steel is highly conductive, has a significant magnetic permeability and is very thin compared to its length, making it a challenging structure to model. Using the open-source frameworks of SimPEG and simpegEM, we solve this using a primary-secondary approach that employs multiple formulations of Maxwell's equations and both a 2D

  10. HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source

    NASA Astrophysics Data System (ADS)

    Melnikov, S. Yu; Eislöffel, J.; Bacciotti, F.; Woitas, J.; Ray, T. P.

    2009-11-01

    Context: We present the results of new spectral diagnostic investigations applied to high-resolution long-slit spectra obtained with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) of the jet from the T Tauri star RW Aur. Aims: Our primary goal is to determine basic physical parameters (electron density ne and electron temperature Te, hydrogen ionisation fraction xe, total hydrogen density nH, radial velocity vr and the mass outflow rate dot Mj) along both the red- and blueshifted lobes of the RW Aur jet. Methods: The input dataset consists of seven long-slit spectra, of 0.1 arcsec spatial resolution, taken with the STIS slit parallel to the jet, and stepped across it. We use the Bacciotti & Eislöffel (1999, A&A, 342, 717) method to analyse the forbidden doublets [O I]λλ6300,6363, [S II]λλ 6716,6731, and [N II]λλ 6548,6583 Å to extract n_e, T_e, x_e, and n_H. Results: We were able to extract the parameters as far as 3.9 arcsec in the red- and 2.1 arcsec in the blueshifted beam. The electron density at the base of both lobes is close to the critical density for [S II] emission but then it decreases gradually with distance from the source. The range of electron temperatures derived for this jet (Te = 10^4-2×104 K) is similar to those generally found in other outflows from young stars. The ionisation fraction xe varies between 0.04 and 0.4, increasing within the first few arcseconds and then decreasing in both lobes. The total hydrogen density, derived as nH = ne / x_e, is on average 3.2×104 cm-3 and shows a gradual decrease along the beam. Variations of the above quantities along the jet lobes appear to be correlated with the position of knots. Combining the derived parameters with vr measured from the HST spectra and other characteristics available for this jet, we estimate dot Mj following two different procedures. The mass-outflow rate dot Mj is moderate and similar in the two lobes, despite the fact that the well-known asymmetry in the radial

  11. Source Parameters of the 2013 May 1, mb 5.7 Kashmir Earthquake: Implications for Seismic Hazard

    NASA Astrophysics Data System (ADS)

    Mitra, S.; Wanchoo, S.; Priestley, K. F.

    2013-12-01

    We study the source mechanism and depth of the recent moderately-large earthquake (mb 5.7), which occurred on 1st May 2013 in the Kashmir seismic gap. The epicenter of the earthquake lie southeast of the Kashmir Valley and falls at the edge of the meisoseismal zone of the 1555 Kashmir earthquake (magnitude>8). This event provides an excellent opportunity to study the seismotectonics of the Kashmir Himalaya using global digital seismic data. We modelled the source parameters of the earthquake by least-squares fitting of the teleseismic P- and SH-waveform data. The minimum-misfit solution reveal that the earthquake occurred on an oblique thrust fault with strike, dip and rake of 346°, 26° and 121°, respectively, and originated at a depth of 16×3 km. The strike of the fault plane matches that of the mapped Himalayan thrust faults in the region and its depth puts it within the Himalayan wedge, close to the basal decollement (Main Himalayan Thrust). However, the dip of the causal fault plane is larger than the inferred dip of the Main Himalayan Thrust and therefore requires the earthquake to have occurred on a ramp or a splay thrust. The most likely candidate is the Main Boundary Thrust whose downdip end matches with the geometry of the fault plane and coincides with the observed hypocentral distribution of small-to-moderate earthquakes in the region. The hypocentral zone of this event therefore marks a region of strain accumulation and release beneath the Kashmir seismic gap and could possibly be the point of initiation of a future great earthquake.

  12. Physical properties of outflows. Comparing CO- and H2O-based parameters in Class 0 sources

    NASA Astrophysics Data System (ADS)

    Bjerkeli, P.; Liseau, R.; Nisini, B.; Tafalla, M.; Bergman, P.; Melnick, G.; Rydbeck, G.

    2013-04-01

    Context. The observed physical properties of outflows from low-mass sources put constraints on possible ejection mechanisms. Historically, these quantities have been derived from CO using ground-based observations. It is, therefore, important to investigate whether parameters such as momentum rate (thrust) and mechanical luminosity (power) are the same when different molecular tracers are used. Aims: Our objective is to determine the outflow momentum, dynamical time-scale, thrust, energy, and power using CO and H2O as tracers of outflow activity. Methods: Within the framework of the Water In Star-forming regions with Herschel (WISH) key program, three molecular outflows from Class 0 sources have been mapped using the Heterodyne Instrument for the Far Infrared (HIFI) instrument aboard Herschel. We used these observations together with previously published H2 data to infer the physical properties of the outflows. We compared the physical properties derived here with previous estimates based on CO observations. Results: Inspection of the spatial distribution of H2O and H2 confirms that these molecules are co-spatial. The most prominent emission peaks in H2 coincide with strong H2O emission peaks and the estimated widths of the flows when using the two tracers are comparable. Conclusions: For the momentum rate and the mechanical luminosity, inferred values are not dependent on which tracer is used, i.e. the values agree to within a factor of 4 and 3, respectively. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  13. Numerical modeling on the source parameter scaling relations and synthetic surface deformation of episodic slow slip events in subduction zones

    NASA Astrophysics Data System (ADS)

    Liu, Y.

    2013-12-01

    A spectrum of slow slip phenomena in subduction zones, ranging from low-frequency earthquakes to long-term slow slip events (SSE), demonstrates a linear relation between event moment M0 and duration T spanning 7 to 8 orders of magnitude in each dimension [Ide et al., Nature, 2007; Gao et al., BSSA, 2012]. However, such a linear relation is not clearly established for each type of slow phenomena. For example, slow earthquakes beneath the Kii Peninsula in western Japan show M0 ~ T1.5 [Ide et al., GRL, 2008]. Except for the episodic SSEs in Cascadia, SSEs in other subduction zones have more scattered M0 -T relation. Understanding this scaling relation is thus key to the study of the physical mechanism of SSEs and why they are different from regular earthquakes. Here we set up a 3D planar Cascadia subduction fault model using gabbro rate-state friction parameters and incorporating near-lithostatic pore pressure around the velocity-weakening to strengthening friction stability transition at depths between 30 and 40 km. SSEs appear at the transitional depths and repeat roughly every year. Complex along-strike migration patterns are also modeled by introducing small (<5%) along-strike perturbations in frictional parameters. By identifying individual episodes of SSEs using a slip velocity threshold, we quantify the following SSE source properties, along-strike propagation length, total duration, equivalent moment, stress drop, migration speed, derive their scaling relations and compare to the observations summarized by Gao et al. [2012]. Our modeled SSEs have nearly constant stress drops between 0.001 and 0.01 MPa, due to the small effective normal stress on the order of 1 MPa in the SSE region. They have moment M0 between 1017.5 to 1019.5 Nm and duration T between 0.1 to 1 year, and the relation is best described by M0 ~ T1.8 for about 70 episodes recorded in 20 years along the 1000 km long margin. More simulation cases are conducted to systematically investigate how the

  14. In situ measurement of ions parameters of laser produced ion source using high resolution Thomson Parabola Spectrometer

    NASA Astrophysics Data System (ADS)

    Chaurasia, S.; Kaur, C.; Rastogi, V.; Poswal, A. K.; Munda, D. S.; Bhatia, R. K.; Nataraju, V.

    2016-08-01

    The laser produced plasma based heavy ion source has become an outstanding front end for heavy ion accelerators. Before being implemented in the heavy ion accelerators its detailed characterization is required. For this purpose, a high resolution and high dispersion Thomson parabola spectrometer comprising of Time-of-Flight diagnostics has been developed for the characterization of ions with energy in the range from 1 keV to 1 MeV/nucleon and incorporated in the Laser plasma experimental chamber. The ion spectrometer is optimized with graphite target. The carbon ions of charge states C1+ to C6+ are observed in the energy range from 3 keV to 300 keV, which has also been verified by Time-of-Flight measurement. Experimental results were matched with simulation done by SIMION 7.0 code which is used for the design of the spectrometer. We also developed data analysis software using Python language to measure in situ ion's parameters and the results are in better agreement to the experimental results than the commercially available software SIMION 7.0. The resolution of the spectrometer is ΔE/E = 0.026 @ 31 keV for charge state (C4+) of carbon.

  15. Comparison of Schlemm's canal's biological parameters in primary open-angle glaucoma and normal human eyes with swept source optical

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Shi, Guohua; Li, Xiqi; Lu, Jing; Ding, Zhihua; Sun, Xinghuai; Jiang, Chunhui; Zhang, Yudong

    2012-11-01

    Thirty-seven normal and primary open angle glaucoma (POAG) subjects were noninvasively imaged by a tailor-made real-time anterior segment swept source optical coherence tomography (SS-OCT) to demonstrate the differences of the Schlemm's canal (SC) between POAG and normal eyes. After the cross-section images of the anterior chamber angle were acquired by SS-OCT, SC was confirmed by two independent masked observers and the average area, long diameter, and perimeter of the SC were measured. In normal subjects the circumference, area, and long diameter is 580.34±87.81 μm, 8023.89±1486.10 μ, and 272.83±49.39 μm, respectively, and these parameters were 393.25±98.04 μm, 3941.50±1210.69 μ, and 190.91±46.47 μm in the POAG subjects. The area of SC in the normal ones was significantly larger than that in POAG eyes (p<0.001), so as the long diameter and the perimeter (p<0.001 p<0.001).

  16. Investigations on caesium-free alternatives for H{sup −} formation at ion source relevant parameters

    SciTech Connect

    Kurutz, U.; Fantz, U.

    2015-04-08

    Negative hydrogen ions are efficiently produced in ion sources by the application of caesium. Due to a thereby induced lowering of the work function of a converter surface a direct conversion of impinging hydrogen atoms and positive ions into negative ions is maintained. However, due to the complex caesium chemistry and dynamics a long-term behaviour is inherent for the application of caesium that affects the stability and reliability of negative ion sources. To overcome these drawbacks caesium-free alternatives for efficient negative ion formation are investigated at the flexible laboratory setup HOMER (HOMogenous Electron cyclotron Resonance plasma). By the usage of a meshed grid the tandem principle is applied allowing for investigations on material induced negative ion formation under plasma parameters relevant for ion source operation. The effect of different sample materials on the ratio of the negative ion density to the electron density n{sub H{sup −}} /n{sub e} is compared to the effect of a stainless steel reference sample and investigated by means of laser photodetachment in a pressure range from 0.3 to 3 Pa. For the stainless steel sample no surface induced effect on the negative ion density is present and the measured negative ion densities are resulting from pure volume formation and destruction processes. In a first step the dependency of n{sub H{sup −}} /n{sub e} on the sample distance has been investigated for a caesiated stainless steel sample. At a distance of 0.5 cm at 0.3 Pa the density ratio is 3 times enhanced compared to the reference sample confirming the surface production of negative ions. In contrast for the caesium-free material samples, tantalum and tungsten, the same dependency on pressure and distance n{sub H{sup −}} /n{sub e} like for the stainless steel reference sample were obtained within the error margins: A density ratio of around 14.5% is measured at 4.5 cm sample distance and 0.3 Pa, linearly decreasing with

  17. Determination of Source Parameters for Earthquakes in the Northeastern United States and Quebec, Canada by Using Regional Broadband Seismograms

    NASA Astrophysics Data System (ADS)

    Du, W.; Kim, W.; Sykes, L. R.

    2001-05-01

    We studied approximately 20 earthquakes which have occurred in the Northeastern United States and Quebec, southern Canada since 1990. These earthquakes have local magnitude (ML) ranging from 3.5 to 5.2 and are well recorded by broadband seismographic stations in the region. Focal depth and moment tensor of these earthquakes are determined by using waveform inversion technique in which the best fit double-couple mechanism is obtained through a grid search over strike, dip and rake angles. Complete synthetics for three-component displacement signals in the period range 1 to 30 seconds are calculated. In most cases, long period Pnl and surface waves are used to constrain the source parameters. Our results indicate that most of the events show the horizontal compression with near horizontal P axis striking NE-SW. However, three events along the lower St. Lawrence River shows the P axes striking ESE-SE (100-130 degrees) with plunge angles of about 20 degrees. Focal depths of these events range from 2 to 28 km. Four events along the Appalachian Mts. have occurred with 2 to 5 km depths -- Jan. 16, 1994 Reading, Pa sequence, Sep. 25, 1998 Pymatuning, Pa event, Jan. 26, 2001 Ashutabula, Oh earthquake and an event in the Charlevoix seismic zone, Canada (Oct. 28, 1997). Two events have occurred at depth greater than 20 km. These are Quebec City earthquake on Nov. 6, 1997 and Christieville, Quebec event on May 4, 1997. We also observed the apparent discrepancy between the moment magnitude (Mw) and local magnitude (ML). Preliminary results show that for the events studied, Mw tends to be about 0.3 magnitude units smaller than the corresponding ML. However, some events show comparable Mw and ML values, for instance, the 1994 Reading, Pa sequence and Oct. 28, 1997 Charlevoix earthquake. These events have occurred at shallow depths and show low stress drops (less than 100 bars). We believe that this magnitude discrepancy reflects the source characteristics of intraplate events in

  18. A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays. I. Method and results for the Leaky-Box model

    NASA Astrophysics Data System (ADS)

    Putze, A.; Derome, L.; Maurin, D.; Perotto, L.; Taillet, R.

    2009-04-01

    Context: Propagation of charged cosmic-rays in the Galaxy depends on the transport parameters, whose number can be large depending on the propagation model under scrutiny. A standard approach for determining these parameters is a manual scan, leading to an inefficient and incomplete coverage of the parameter space. Aims: In analyzing the data from forthcoming experiments, a more sophisticated strategy is required. An automated statistical tool is used, which enables a full coverage of the parameter space and provides a sound determination of the transport and source parameters. The uncertainties in these parameters are also derived. Methods: We implement a Markov Chain Monte Carlo (MCMC), which is well suited to multi-parameter determination. Its specificities (burn-in length, acceptance, and correlation length) are discussed in the context of cosmic-ray physics. Its capabilities and performances are explored in the phenomenologically well-understood Leaky-Box Model. Results: From a technical point of view, a trial function based on binary-space partitioning is found to be extremely efficient, allowing a simultaneous determination of up to nine parameters, including transport and source parameters, such as slope and abundances. Our best-fit model includes both a low energy cut-off and reacceleration, whose values are consistent with those found in diffusion models. A Kolmogorov spectrum for the diffusion slope (δ = 1/3) is excluded. The marginalised probability-density function for δ and α (the slope of the source spectra) are δ ≈ 0.55-0.60 and α ≈ 2.14-2.17, depending on the dataset used and the number of free parameters in the fit. All source-spectrum parameters (slope and abundances) are positively correlated among themselves and with the reacceleration strength, but are negatively correlated with the other propagation parameters. Conclusions: The MCMC is a practical and powerful tool for cosmic-ray physic analyses. It can be used to confirm hypotheses

  19. Inferring fault mechanical conditions from the source parameters of a complex microseismic multiplet in the Corinth rift, Greece

    NASA Astrophysics Data System (ADS)

    Dublanchet, P.; Godano, M.; Bernard, P.

    2015-11-01

    We develop a mechanical model of tight clusters of coplanar seismic asperities, to investigate a particular microearthquake swarm located at 8 km depth in the Corinth rift in Greece, which was active between 2001 and 2007. Although it is classified as a multiplet based on waveform similarity, this seismic sequence is much more complex than a repeating earthquake sequence and cannot be interpreted as the regular failure of a single asperity forced by surrounding aseismic creep. Here we suggest that such complex sequences could be generated by the failure of a set of coplanar asperities interacting in a small region of a fault segment. We show that in order to reproduce the dynamics of the observed sequence and the characteristics of the events, the cluster of asperities has to be located very close to an aseismically slipping fault segment, which could be an updip extension of the deep detachment zone in the rift, creeping at 1.5 cm/yr. For more general cases of coplanar clustered asperities, we show that the shape of the cumulative coseismic displacement pattern associated with the repeated failures of the asperities is strongly controlled by the behavior of the fault area surrounding the asperity cluster. In particular, if the cluster is part of a locked fault area, the resulting long-term cumulative displacement is maximum at the center of the cluster. In contrast, an asperity cluster surrounded by aseismic creep leads to a uniform cumulative coseismic slip pattern. The ratio between cumulative slip at the center of the seismogenic patch and cumulative slip at its periphery could therefore be an indicator of the mechanical conditions prevailing on the fault. A systematic study of the source parameters of complex microseismic sequences could therefore provide insights into the mechanical state of active faults continuously generating microseismicity.

  20. Relation between sources of particulate air pollution and biological effect parameters in samples from four European cities: An exploratory study

    SciTech Connect

    Steerenberg, P.A.; van Amelsvoort, L.; Lovik, M.; Hetland, R.B.; Alberg, T.; Halatek, T.; Bloemen, H.J.T.; Rydzynski, K.; Swaen, G.; Schwarze, P.; Dybing, E.; Cassee, F.R.

    2006-05-15

    Given that there are widely different prevalence rates of respiratory allergies and asthma between the countries of Europe and that exposure to ambient particulate matter (PM) is substantial in urban environments throughout Europe, an EU project entitled 'Respiratory Allergy and Inflammation Due to Ambient Particles' (RAIAP) was set up. The project focused on the role of physical and chemical composition of PM on release of cytokines of cells in vitro, on respiratory inflammation in vivo, and on adjuvant potency in allergy animal models. Coarse (2.5 - 10 {mu}m) and fine (0.15 - 2.5 {mu}m) particles were collected during the spring, summer and winter in Rome ( I), Oslo (N), Lodz (PL), and Amsterdam (NL). Markers within the same model were often well correlated. Markers of inflammation in the in vitro and in vivo models also showed a high degree of correlation. In contrast, correlation between parameters in the different allergy models and between allergy and inflammation markers was generally poor. This suggests that various bioassays are needed to assess the potential hazard of PM. The present study also showed that by clustering chemical constituents of PM based on the overall response pattern in the bioassays, five distinct groups could be identified. The clusters of traffic, industrial combustion and/or incinerators, and combustion of black and brown coal/wood smoke were associated primarily with adjuvant activity for respiratory allergy, whereas clusters of crustal of material and sea spray are predominantly associated with measures for inflammation and acute toxicity. The present study has shown that biological effect of PM can be linked to one or more PM emission sources and that this linkage requires a wide range of bioassays.

  1. A new tool for rapid and automatic estimation of earthquake source parameters and generation of seismic bulletins

    NASA Astrophysics Data System (ADS)

    Zollo, Aldo

    2016-04-01

    RISS S.r.l. is a Spin-off company recently born from the initiative of the research group constituting the Seismology Laboratory of the Department of Physics of the University of Naples Federico II. RISS is an innovative start-up, based on the decade-long experience in earthquake monitoring systems and seismic data analysis of its members and has the major goal to transform the most recent innovations of the scientific research into technological products and prototypes. With this aim, RISS has recently started the development of a new software, which is an elegant solution to manage and analyse seismic data and to create automatic earthquake bulletins. The software has been initially developed to manage data recorded at the ISNet network (Irpinia Seismic Network), which is a network of seismic stations deployed in Southern Apennines along the active fault system responsible for the 1980, November 23, MS 6.9 Irpinia earthquake. The software, however, is fully exportable and can be used to manage data from different networks, with any kind of station geometry or network configuration and is able to provide reliable estimates of earthquake source parameters, whichever is the background seismicity level of the area of interest. Here we present the real-time automated procedures and the analyses performed by the software package, which is essentially a chain of different modules, each of them aimed at the automatic computation of a specific source parameter. The P-wave arrival times are first detected on the real-time streaming of data and then the software performs the phase association and earthquake binding. As soon as an event is automatically detected by the binder, the earthquake location coordinates and the origin time are rapidly estimated, using a probabilistic, non-linear, exploration algorithm. Then, the software is able to automatically provide three different magnitude estimates. First, the local magnitude (Ml) is computed, using the peak-to-peak amplitude

  2. A new tool for rapid and automatic estimation of earthquake source parameters and generation of seismic bulletins

    NASA Astrophysics Data System (ADS)

    Zollo, Aldo

    2016-04-01

    RISS S.r.l. is a Spin-off company recently born from the initiative of the research group constituting the Seismology Laboratory of the Department of Physics of the University of Naples Federico II. RISS is an innovative start-up, based on the decade-long experience in earthquake monitoring systems and seismic data analysis of its members and has the major goal to transform the most recent innovations of the scientific research into technological products and prototypes. With this aim, RISS has recently started the development of a new software, which is an elegant solution to manage and analyse seismic data and to create automatic earthquake bulletins. The software has been initially developed to manage data recorded at the ISNet network (Irpinia Seismic Network), which is a network of seismic stations deployed in Southern Apennines along the active fault system responsible for the 1980, November 23, MS 6.9 Irpinia earthquake. The software, however, is fully exportable and can be used to manage data from different networks, with any kind of station geometry or network configuration and is able to provide reliable estimates of earthquake source parameters, whichever is the background seismicity level of the area of interest. Here we present the real-time automated procedures and the analyses performed by the software package, which is essentially a chain of different modules, each of them aimed at the automatic computation of a specific source parameter. The P-wave arrival times are first detected on the real-time streaming of data and then the software performs the phase association and earthquake binding. As soon as an event is automatically detected by the binder, the earthquake location coordinates and the origin time are rapidly estimated, using a probabilistic, non-linear, exploration algorithm. Then, the software is able to automatically provide three different magnitude estimates. First, the local magnitude (Ml) is computed, using the peak-to-peak amplitude

  3. 3D models of slow motions in the Earth's crust and upper mantle in the source zones of seismically active regions and their comparison with highly accurate observational data: I. Main relationships

    NASA Astrophysics Data System (ADS)

    Molodenskii, S. M.; Molodenskii, M. S.; Begitova, T. A.

    2016-09-01

    Constructing detailed models for postseismic and coseismic deformations of the Earth's surface has become particularly important because of the recently established possibility to continuously monitor the tectonic stresses in the source zones based on the data on the time variations in the tidal tilt amplitudes. Below, a new method is suggested for solving the inverse problem about the coseismic and postseismic deformations in the real non-ideally elastic, radially and horizontally heterogeneous, self-gravitating Earth with a hydrostatic distribution of the initial stresses from the satellite data on the ground surface displacements. The solution of this problem is based on decomposing the parameters determining the geometry of the fault surface and the distribution of the dislocation vector on this surface and elastic modules in the source in the orthogonal bases. The suggested approach includes four steps: 1. Calculating (by the perturbation method) the variations in Green's function for the radial and tangential ground surface displacements with small 3D variations in the mechanical parameters and geometry of the source area (i.e., calculating the functional derivatives of the three components of Green's function on the surface from the distributions of the elastic moduli and creep function within the volume of the source area and Burgers' vector on the surface of the dislocations); 2. Successive orthogonalization of the functional derivatives; 3. Passing from the decompositions of the residuals between the observed and modeled surface displacements in the system of nonorthogonalized functional derivatives to their decomposition in the system of orthogonalized derivatives; finding the corrections to the distributions of the sought parameters from the coefficients of their decompositions in the orthogonalized basis; and 4. Analyzing the ambiguity of the inverse problem solution by constructing the orthogonal complement to the obtained basis. The described

  4. Comparison of Orbital Parameters for GEO Debris Predicted by LEGEND and Observed by MODEST: Can Sources of Orbital Debris be Identified?

    NASA Technical Reports Server (NTRS)

    Barker, Edwin S.; Matney, M. J.; Liou, J.-C.; Abercromby, K. J.; Rodriquez, H. M.; Seitzer, P.

    2006-01-01

    Since 2002 the National Aeronautics and Space Administration (NASA) has carried out an optical survey of the debris environment in the geosynchronous Earth-orbit (GEO) region with the Michigan Orbital Debris Survey Telescope (MODEST) in Chile. The survey coverage has been similar for 4 of the 5 years allowing us to follow the orbital evolution of Correlated Targets (CTs), both controlled and un-controlled objects, and Un-Correlated Targets (UCTs). Under gravitational perturbations the distributions of uncontrolled objects, both CTs and UCTs, in GEO orbits will evolve in predictable patterns, particularly evident in the inclination and right ascension of the ascending node (RAAN) distributions. There are several clusters (others have used a "cloud" nomenclature) in observed distributions that show evolution from year to year in their inclination and ascending node elements. However, when MODEST is in survey mode (field-of-view approx.1.3deg) it provides only short 5-8 minute orbital arcs which can only be fit under the assumption of a circular orbit approximation (ACO) to determine the orbital parameters. These ACO elements are useful only in a statistical sense as dedicated observing runs would be required to obtain sufficient orbital coverage to determine a set of accurate orbital elements and then to follow their evolution. Identification of the source(s) for these "clusters of UCTs" would be advantageous to the overall definition of the GEO orbital debris environment. This paper will set out to determine if the ACO elements can be used to in a statistical sense to identify the source of the "clustering of UCTs" roughly centered on an inclination of 12deg and a RAAN of 345deg. The breakup of the Titan 3C-4 transtage on February 21, 1992 has been modeled using NASA s LEGEND (LEO-to-GEO Environment Debris) code to generate a GEO debris cloud. Breakup fragments are created based on the NASA Standard Breakup Model (including fragment size, area-to-mass (A/M), and

  5. Comparison of Orbital Parameters for GEO Debris Predicted by LEGEND and Observed by MODEST: Can Sources of Orbital Debris be Identified?

    NASA Astrophysics Data System (ADS)

    Barker, E.; Matney, M. J.; Liou, J.-C.; Abercromby, K.; Rodriguez, H.; Seitzer, P.

    Since 2002 the National Aeronautics and Space Administration (NASA) has carried out an optical survey of the debris environment in the geosynchronous Earth-orbit (GEO) region with the Michigan Orbital Debris Survey Telescope (MODEST) in Chile. The survey coverage has been similar for 4 of the 5 years allowing us to follow the orbital evolution of Correlated Targets (CTs), both controlled and un-controlled objects, and Un-Correlated Targets (UCTs). Under gravitational perturbations the distributions of uncontrolled objects, both CTs and UCTs, in GEO orbits will evolve in predictable patterns, particularly evident in the inclination and right ascension of the ascending node (RAAN) distributions. There are several clusters (others have used a "cloud" nomenclature) in observed distributions that show evolution from year to year in their inclination and ascending node elements. However, when MODEST is in survey mode (field-of-view ~1.3°) it provides only short 5-8 minute orbital arcs which can only be fit under the assumption of a circular orbit approximation (ACO) to determine the orbital parameters. These ACO elements are useful only in a statistical sense as dedicated observing runs would be required to obtain sufficient orbital coverage to determine a set of accurate orbital elements and then to follow their evolution. Identification of the source(s) for these "clusters of UCTs" would be advantageous to the overall definition of the GEO orbital debris environment. This paper will set out to determine if the ACO elements can be used to in a statistical sense to identify the source of the "clustering of UCTs" roughly centered on an inclination of 12° and a RAAN of 345°. The breakup of the Titan 3C-4 transtage on February 21, 1992 has been modeled using NASA's LEGEND (LEO-to-GEO Environment Debris) code to generate a GEO debris cloud. Breakup fragments are created based on the NASA Standard Breakup Model (including fragment size, area-to-mass (A/M), and delta

  6. Feeding at a high pitch: source parameters of narrow band, high-frequency clicks from echolocating off-shore hourglass dolphins and coastal Hector's dolphins.

    PubMed

    Kyhn, Line A; Tougaard, J; Jensen, F; Wahlberg, M; Stone, G; Yoshinaga, A; Beedholm, K; Madsen, P T

    2009-03-01

    Toothed whales depend on echolocation for orientation and prey localization, and source parameters of echolocation clicks from free-ranging animals therefore convey valuable information about the acoustic physiology and behavioral ecology of the recorded species. Recordings of wild hourglass (Lagenorhynchus cruciger) and Hector's dolphins (Cephalorhynchus hectori) were made in the Drake Passage (between Tierra del Fuego and the Antarctic Peninsular) and Banks Peninsular (Akaroa Harbour, New Zealand) with a four element hydrophone array. Analysis of source parameters shows that both species produce narrow band high-frequency (NBHF) echolocation clicks. Coastal Hector's dolphins produce clicks with a mean peak frequency of 129 kHz, 3 dB bandwidth of 20 kHz, 57 micros, 10 dB duration, and mean apparent source level (ASL) of 177 dB re 1 microPa(p.-p.). The oceanic hourglass dolphins produce clicks with mean peak frequency of 126 kHz, 3 dB bandwidth of 8 kHz, 116 micros, 10 dB duration, and a mean estimated ASL of 197 dB re 1 microPa(p.-p.). Thus, hourglass dolphins apparently produce clicks of higher source level, which should allow them to detect prey at more than twice the distance compared to Hector's dolphins. The observed source parameter differences within these two NBHF species may be an adaptation to a coastal cluttered environment versus a deep water, pelagic habitat. PMID:19275335

  7. Finite Source Parameters Using Strong Motion Waveforms of Taiwan TSMIP Data: A Case Study of 22 October 1999 Chiayi, Taiwan, Earthquake

    NASA Astrophysics Data System (ADS)

    Chang, K.; Chi, W. C.; Dreger, D. S.; Gung, Y.

    2014-12-01

    Inverting seismic waveforms for the finite fault source parameters of earthquakes is important for reconstruction of faulting processes including both the properties of the fault and transient stress field. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for more than 100 Mw>4 earthquakes were first obtained by complete waveform moment tensor inversions. Then we use part of this catalog to study the 22 October 1999 (Mw 5.6) earthquake sequence near the city of Chiayi, Taiwan, where a damaging earthquake occurred a century ago. We have derived the change in the duration of the apparent source time functions (ASTFs) using a new Empirical Green Function Deconvolution method to estimate the mainshock rupture propagation processes. Preliminary results show the mainshock ruptured on the NNE-SSW trending right-lateral strike-slip fault and propagated toward SSW direction. To further characterize the faulting, we are using a finite fault inversion code developed by Dreger and Kaverina (2000) to derive a slip distribution model of this mainshock. The procedure developed from this study can be applied to other strong motion events to better understand their kinematic source parameters.

  8. Source parameters of the 2007 Noto Hanto earthquake sequence derived from strong motion records at temporary and permanent stations

    NASA Astrophysics Data System (ADS)

    Maeda, Takahiro; Ichiyanagi, Masayoshi; Takahashi, Hiroaki; Honda, Ryo; Yamaguchi, Teruhiro; Kasahara, Minoru; Sasatani, Tsutomu

    2008-10-01

    A large crustal earthquake, the 2007 Noto Hanto earthquake, occurred west off the Noto peninsula in Ishikawa prefecture, Japan, on March 25, 2007. We started temporary strong motion observation at five sites within the aftershock area from about 13 h after the main shock occurrence. We first applied the spectral inversion method to S-wave strong ground motion records at the temporary and permanent stations. We obtained source specta of the main shock and aftershocks, Q s (quality factor for S-wave) values ( Q s = 34.5 f 0.95) and site responses at 22 sites. We then estimated a source model of the main shock using the empirical Green's function method. The source model consists of three strong motion generation areas and well explains the observed records. Finally, we examined the consistency of the main-shock source models estimated from the above two analyses. The high-frequency level of the acceleration source spectrum based on the main-shock source model is consistent with the source spectrum estimated from the spectral inversion. The combined area of strong motion generation areas is approximately half of the value expected by the empirical relationship, and the high-frequency level of acceleration source spectrum is approximately 2.5 times larger than the empirical relationship for shallow inland and inter-plate earthquakes.

  9. Accurate monotone cubic interpolation

    NASA Technical Reports Server (NTRS)

    Huynh, Hung T.

    1991-01-01

    Monotone piecewise cubic interpolants are simple and effective. They are generally third-order accurate, except near strict local extrema where accuracy degenerates to second-order due to the monotonicity constraint. Algorithms for piecewise cubic interpolants, which preserve monotonicity as well as uniform third and fourth-order accuracy are presented. The gain of accuracy is obtained by relaxing the monotonicity constraint in a geometric framework in which the median function plays a crucial role.

  10. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  11. Seismotectonics of the Caucasus and surrounding regions: source parameters and rupture histories of the recent destructive earthquakes

    NASA Astrophysics Data System (ADS)

    Tan, O.; Taymaz, T.

    2004-12-01

    The complexity of plate interactions and associated crustal deformation in the eastern Mediterranean region is marked by the occurence of many destructive earthquakes throughout the recorded history. The wide range of deformational processes occuring in this region means that eastern Mediterranean provides a unique opportunity to improve our understanding of the complex kinematics of continental collision, including strike-slip faulting and crustal extension, as well as associated seismicity and volcanism. This presentation is concerned with the seismotectonics of Caucasus and surrounding regions that are prominent features in the collision zone between the African and Eurasian plates, and provides us with a complex pattern of continental deformation of the region. We have studied the tectonic characteristics of a comprehensive seismicity occurred in the region during the last 20 years, based on newly retrieved and obtained source mechanisms and rupture histories of ˜40 earthquakes, Mw>5.3, by using waveform inversion of teleseismic long-period P-, SH-, and broad-band P-waveforms recorded in the distance range of 30-90° . They all exhibit the characteristics and structural complexities associated with strike-slip, thrust and normal faulting as a result of ongoing crustal deformation. Earthquakes in the greater Caucasus mainly exhibit NW-SE thrust faulting mechanisms in general. The western part of the mountain belt has only one moderate size event and verifies that northward dipping shallow thrust fault is active beneath the southern border of the western greater Caucasus. In contrary, the Racha earthquake, and its four moderate size aftershocks, and earthquake of Barisakho indicate that most of the stress accumulation occurs within the central part of the Caucasus mountain belt. A series of earthquakes shows that northern boundary thrust faults of the eastern greater Caucasus dips southwards with a very shallow angle ( ˜5-10° ). Furthermore, the Lesser

  12. Monte Carlo calculations and experimental measurements of dosimetric parameters of the IRA-{sup 103}Pd brachytherapy source

    SciTech Connect

    Sadeghi, Mahdi; Raisali, Gholamreza; Hosseini, S. Hamed; Shavar, Arzhang

    2008-04-15

    This article presents a brachytherapy source having {sup 103}Pd adsorbed onto a cylindrical silver rod that has been developed by the Agricultural, Medical, and Industrial Research School for permanent implant applications. Dosimetric characteristics (radial dose function, anisotropy function, and anisotropy factor) of this source were experimentally and theoretically determined in terms of the updated AAPM Task group 43 (TG-43U1) recommendations. Monte Carlo simulations were used to calculate the dose rate constant. Measurements were performed using TLD-GR200A circular chip dosimeters using standard methods employing thermoluminescent dosimeters in a Perspex phantom. Precision machined bores in the phantom located the dosimeters and the source in a reproducible fixed geometry, providing for transverse-axis and angular dose profiles over a range of distances from 0.5 to 5 cm. The Monte Carlo N-particle (MCNP) code, version 4C simulation techniques have been used to evaluate the dose-rate distributions around this model {sup 103}Pd source in water and Perspex phantoms. The Monte Carlo calculated dose rate constant of the IRA-{sup 103}Pd source in water was found to be 0.678 cGy h{sup -1} U{sup -1} with an approximate uncertainty of {+-}0.1%. The anisotropy function, F(r,{theta}), and the radial dose function, g(r), of the IRA-{sup 103}Pd source were also measured in a Perspex phantom and calculated in both Perspex and liquid water phantoms.

  13. Estimating winter wheat phenological parameters: Implications for crop modeling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Crop parameters, such as the timing of developmental events, are critical for accurate simulation results in crop simulation models, yet uncertainty often exists in determining the parameters. Factors contributing to the uncertainty include: a) sources of variation within a plant (i.e., within diffe...

  14. Predicting hydration Gibbs energies of alkyl-aromatics using molecular simulation: a comparison of current force fields and the development of a new parameter set for accurate solvation data.

    PubMed

    Garrido, Nuno M; Jorge, Miguel; Queimada, António J; Gomes, José R B; Economou, Ioannis G; Macedo, Eugénia A

    2011-10-14

    The Gibbs energy of hydration is an important quantity to understand the molecular behavior in aqueous systems at constant temperature and pressure. In this work we review the performance of some popular force fields, namely TraPPE, OPLS-AA and Gromos, in reproducing the experimental Gibbs energies of hydration of several alkyl-aromatic compounds--benzene, mono-, di- and tri-substituted alkylbenzenes--using molecular simulation techniques. In the second part of the paper, we report a new model that is able to improve such hydration energy predictions, based on Lennard Jones parameters from the recent TraPPE-EH force field and atomic partial charges obtained from natural population analysis of density functional theory calculations. We apply a scaling factor determined by fitting the experimental hydration energy of only two solutes, and then present a simple rule to generate atomic partial charges for different substituted alkyl-aromatics. This rule has the added advantages of eliminating the unnecessary assumption of fixed charge on every substituted carbon atom and providing a simple guideline for extrapolating the charge assignment to any multi-substituted alkyl-aromatic molecule. The point charges derived here yield excellent predictions of experimental Gibbs energies of hydration, with an overall absolute average deviation of less than 0.6 kJ mol(-1). This new parameter set can also give good predictive performance for other thermodynamic properties and liquid structural information.

  15. Accurate determination of optical bandgap and lattice parameters of Zn{sub 1-x}Mg{sub x}O epitaxial films (0{<=}x{<=}0.3) grown by plasma-assisted molecular beam epitaxy on a-plane sapphire

    SciTech Connect

    Laumer, Bernhard; Schuster, Fabian; Stutzmann, Martin; Bergmaier, Andreas; Dollinger, Guenther; Eickhoff, Martin

    2013-06-21

    Zn{sub 1-x}Mg{sub x}O epitaxial films with Mg concentrations 0{<=}x{<=}0.3 were grown by plasma-assisted molecular beam epitaxy on a-plane sapphire substrates. Precise determination of the Mg concentration x was performed by elastic recoil detection analysis. The bandgap energy was extracted from absorption measurements with high accuracy taking electron-hole interaction and exciton-phonon complexes into account. From these results a linear relationship between bandgap energy and Mg concentration is established for x{<=}0.3. Due to alloy disorder, the increase of the photoluminescence emission energy with Mg concentration is less pronounced. An analysis of the lattice parameters reveals that the epitaxial films grow biaxially strained on a-plane sapphire.

  16. Multi-year evaluation of ambient volatile organic compounds: temporal variation, ozone formation, meteorological parameters, and sources.

    PubMed

    Kim, Ku H; Chun, Ho-Hwan; Jo, Wan K

    2015-02-01

    The multi-year characteristics of ambient volatile organic compounds (VOCs) and their source contribution in a selected metropolitan (Seoul) and rural (Seokmolee) areas in Korea were investigated to provide the framework for development and implementation of ambient VOC control strategies. For Seoul, none of the three VOC groups exhibited any significant trend in their ambient concentrations, whereas for Seokmolee, they all showed a generally decreasing trend between 2005 and 2008 and an increasing trend after 2008. Two paraffinic (ethane and propane) and two olefin (ethylene and propylene) hydrocarbons displayed higher concentrations during the cold season than warm season, while the other target VOCs did not exhibit any significant trends. Ethylene and toluene were the first and second largest contributors to ozone formation, respectively, whereas several other VOCs displayed photochemical ozone formation potential values less than 0.01 ppb. For both areas, there was a significant negative correlation between ambient temperature and the selected VOC group concentrations. In contrast, a significant positive correlation was observed between relative humidity and the three VOC group concentrations, while no significant correlation was observed between wind speed and VOC group concentrations. For Seoul, the combination of vehicle exhaust and gasoline/solvent evaporation was the greatest source of VOCs, followed by liquid natural gas (LNG) and liquid petroleum gas (LPG). However, combination of LNG and LPG was the greatest source of VOCs at Seokmolee, followed by the combination of vehicle exhaust and gasoline evaporation, and then biogenic sources. PMID:25632908

  17. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  18. Source parameters and moment tensor of the ML 4.6 earthquake of November 19, 2011, southwest Sharm El-Sheikh, Egypt

    NASA Astrophysics Data System (ADS)

    Mohamed, Gad-Elkareem Abdrabou; Omar, Khaled

    2014-06-01

    The southern part of the Gulf of Suez is one of the most seismically active areas in Egypt. On Saturday November 19, 2011 at 07:12:15 (GMT) an earthquake of ML 4.6 occurred in southwest Sharm El-Sheikh, Egypt. The quake has been felt at Sharm El-Sheikh city while no casualties were reported. The instrumental epicenter is located at 27.69°N and 34.06°E. Seismic moment is 1.47 E+22 dyne cm, corresponding to a moment magnitude Mw 4.1. Following a Brune model, the source radius is 101.36 m with an average dislocation of 0.015 cm and a 0.06 MPa stress drop. The source mechanism from a fault plane solution shows a normal fault, the actual fault plane is strike 358, dip 34 and rake -60, the computer code ISOLA is used. Twenty seven small and micro earthquakes (1.5 ⩽ ML ⩽ 4.2) were also recorded by the Egyptian National Seismological Network (ENSN) from the same region. We estimate the source parameters for these earthquakes using displacement spectra. The obtained source parameters include seismic moments of 2.77E+16-1.47E+22 dyne cm, stress drops of 0.0005-0.0617 MPa and relative displacement of 0.0001-0.0152 cm.

  19. Sensitivity of two dispersion models (AERMOD and ISCST3) to input parameters for a rural ground-level area source.

    PubMed

    Faulkner, William B; Shaw, Bryan W; Grosch, Tom

    2008-10-01

    As of December 2006, the American Meteorological Society/U.S. Environmental Protection Agency (EPA) Regulatory Model with Plume Rise Model Enhancements (AERMOD-PRIME; hereafter AERMOD) replaced the Industrial Source Complex Short Term Version 3 (ISCST3) as the EPA-preferred regulatory model. The change from ISCST3 to AERMOD will affect Prevention of Significant Deterioration (PSD) increment consumption as well as permit compliance in states where regulatory agencies limit property line concentrations using modeling analysis. Because of differences in model formulation and the treatment of terrain features, one cannot predict a priori whether ISCST3 or AERMOD will predict higher or lower pollutant concentrations downwind of a source. The objectives of this paper were to determine the sensitivity of AERMOD to various inputs and compare the highest downwind concentrations from a ground-level area source (GLAS) predicted by AERMOD to those predicted by ISCST3. Concentrations predicted using ISCST3 were sensitive to changes in wind speed, temperature, solar radiation (as it affects stability class), and mixing heights below 160 m. Surface roughness also affected downwind concentrations predicted by ISCST3. AERMOD was sensitive to changes in albedo, surface roughness, wind speed, temperature, and cloud cover. Bowen ratio did not affect the results from AERMOD. These results demonstrate AERMOD's sensitivity to small changes in wind speed and surface roughness. When AERMOD is used to determine property line concentrations, small changes in these variables may affect the distance within which concentration limits are exceeded by several hundred meters. PMID:18939775

  20. Measuring earthquake source parameters in the Mendocino triple junction region using a dense OBS array: Implications for fault strength variations

    NASA Astrophysics Data System (ADS)

    Chen, Xiaowei; McGuire, Jeffrey J.

    2016-11-01

    Subduction zones produce earthquakes on a set of faults that operate under a wide variety of conditions resulting from considerable variations in depth, temperature, rock type, and fluid pressure. These variations likely lead to variation in the stress levels that drives particular earthquakes and that in turn effects the magnitude of seismic shaking they produce. In the Mendocino Triple Junction (MTJ) region, intraplate faults within the mantle of the subducting plate fail regularly in energetic earthquakes while the adjacent thrust interface of the Cascadia subduction zone remains seismically quiet despite the likelihood that it operates at much lower levels of stress and strength. In 2012, as part of the Cascadia Initiative community experiment, an ocean bottom seismometer (OBS) array was deployed in the MTJ area, providing unusually dense data covering both the inter- and intra-plate earthquakes. Combining these data with onshore networks, we detect and relocate 1137 earthquakes with a three dimensional velocity model. We perform detailed spectral and time domain analysis to study variations in earthquake source properties between the different types of faults. We observe a wide variability of stress drops and systematic lateral and depth variations in the earthquake source spectra resulting from the different types of tectonic fault systems in this region: intraplate faults within the subducted oceanic mantle, the Mendocino transform plate boundary fault, and the thrust interface of the Cascadia subduction zone. Some of the depth variability of source spectra can be explained by the expected increase in rupture velocity with depth. However, the overall variation in stress drop estimates is consistent with the highest stress drop earthquakes occurring in the depth range predicted by strength envelopes. Moreover, the earthquakes in the vicinity of the thrust interface, likely including some within the subducted oceanic crust, show clearly lower stress drops and

  1. The use of carbon and sulfur isotopes as correlation parameters for the source identification of beach tar in the southern California borderland

    NASA Astrophysics Data System (ADS)

    Hartman, Blayne; Hammond, Douglas E.

    1981-03-01

    Carbon and sulfur isotope ratios and total sulfur content are used to correlate beach tars depositing near Los Angeles with their probable sources. Analysis is confined strictly to the asphaltene fraction of petroleum owing to the insensitivity of this fraction to weathering processes. The δ 13C, δ 34S and % S of the asphaltene fraction of natural offshore seep oils range from -22.51 to -23.20%., +7.75 to + 15.01%. and 4.45 to 8.27%, respectively. Values for local offshore production wells overlapped those for the natural seepage, ranging from -22.10 to -22.85%., -2.96 to 13.90%., and 0.81 to 8.00%. Analytical values for these parameters show that tanker crudes imported into the area are not similar to the California oils. Analysis of the same parameters in beach tars collected during 1976-1977 indicates a close match with the potential source oils, thus it is concluded that these parameters are useful for identifying petroleum sources, even after 2-4 weeks of weathering. Results indicate that 55% of the tars in Santa Monica Bay are derived from natural oil seepage 150km to the northwest at Coal Oil Point, 26% are derived from natural oil seepage in Santa Monica Bay, and 19% are derived from unknown sources. Models of tar transport are inferred which are consistent with the seasonal deposition pattern. Tar from Coal Oil Point natural oil seeps is transported southward in the southern California gyre during the spring, summer and fall seasons, but probably undergoes northward transport during the winter season due to the surfacing of the Davidson Current. Tar from the Santa Monica Bay natural oil seeps moves onshore, but deposition rate seems to depend on seepage flow rate.

  2. Urban stream syndrome in a small, lightly developed watershed: a statistical analysis of water chemistry parameters, land use patterns, and natural sources.

    PubMed

    Halstead, Judith A; Kliman, Sabrina; Berheide, Catherine White; Chaucer, Alexander; Cock-Esteb, Alicea

    2014-06-01

    The relationships among land use patterns, geology, soil, and major solute concentrations in stream water for eight tributaries of the Kayaderosseras Creek watershed in Saratoga County, NY, were investigated using Pearson correlation coefficients and multivariate regression analysis. Sub-watersheds corresponding to each sampling site were delineated, and land use patterns were determined for each of the eight sub-watersheds using GIS. Four land use categories (urban development, agriculture, forests, and wetlands) constituted more than 99 % of the land in the sub-watersheds. Eleven water chemistry parameters were highly and positively correlated with each other and urban development. Multivariate regression models indicated urban development was the most powerful predictor for the same eleven parameters (conductivity, TN, TP, NO[Formula: see text], Cl(-), HCO(-)3, SO9(2-)4, Na(+), K(+), Ca(2+), and Mg(2+)). Adjusted R(2) values, ranging from 19 to 91 %, indicated that these models explained an average of 64 % of the variance in these 11 parameters across the samples and 70 % when Mg(2+) was omitted. The more common R (2), ranging from 29 to 92 %, averaged 68 % for these 11 parameters and 72 % when Mg(2+) was omitted. Water quality improved most with forest coverage in stream watersheds. The strong associations between water quality variables and urban development indicated an urban source for these 11 water quality parameters at all eight sampling sites was likely, suggesting that urban stream syndrome can be detected even on a relatively small scale in a lightly developed area. Possible urban sources of Ca(2+) and HCO(-)3 are suggested.

  3. Accurate Optical Reference Catalogs

    NASA Astrophysics Data System (ADS)

    Zacharias, N.

    2006-08-01

    Current and near future all-sky astrometric catalogs on the ICRF are reviewed with the emphasis on reference star data at optical wavelengths for user applications. The standard error of a Hipparcos Catalogue star position is now about 15 mas per coordinate. For the Tycho-2 data it is typically 20 to 100 mas, depending on magnitude. The USNO CCD Astrograph Catalog (UCAC) observing program was completed in 2004 and reductions toward the final UCAC3 release are in progress. This all-sky reference catalogue will have positional errors of 15 to 70 mas for stars in the 10 to 16 mag range, with a high degree of completeness. Proper motions for the about 60 million UCAC stars will be derived by combining UCAC astrometry with available early epoch data, including yet unpublished scans of the complete set of AGK2, Hamburg Zone astrograph and USNO Black Birch programs. Accurate positional and proper motion data are combined in the Naval Observatory Merged Astrometric Dataset (NOMAD) which includes Hipparcos, Tycho-2, UCAC2, USNO-B1, NPM+SPM plate scan data for astrometry, and is supplemented by multi-band optical photometry as well as 2MASS near infrared photometry. The Milli-Arcsecond Pathfinder Survey (MAPS) mission is currently being planned at USNO. This is a micro-satellite to obtain 1 mas positions, parallaxes, and 1 mas/yr proper motions for all bright stars down to about 15th magnitude. This program will be supplemented by a ground-based program to reach 18th magnitude on the 5 mas level.

  4. Estimation of parameters of finite seismic source model for selected event of West Bohemia year 2008 seismic swarm—methodology improvement and data extension

    NASA Astrophysics Data System (ADS)

    Kolář, Petr

    2015-10-01

    In addition to the previously processed set of 91 events from year 2008 seismic swarm from West Bohemian region (Czech Rep.), we investigated another 368 events, i.e. 454 events in total ( M L 0.1-3.8). We determined parameters of a finite source model by stopping-phases method, namely, source radius and rupture velocity. Newly, the methodology was amended by applying a correction for the effect of attenuation; this effect was found to have an ineligible influence on the results, especially for weaker events ( M L < 1.2). The results are presented both in numerical and in graphical form. From the determined source parameters, we again estimated stress drops of processed events—the results confirm a hypothesis about constant stress drop (with the mean value being 2.9 ± 1.3 MPa). Even if a newly implemented correction for the effect of attenuation decreases the stress drop variation (especially for weaker events), the possibility of partial saturation still remains open. We also present an attempt of a 3D structure model of foci volume and speculate about possible sub-vertical structure in the foci area.

  5. Reconstructing eruptive source parameters from tephra deposit: a numerical study of medium-sized explosive eruptions at Etna volcano

    NASA Astrophysics Data System (ADS)

    Spanu, Antonio; Michieli Vitturi, Mattia de'; Barsotti, Sara

    2016-09-01

    Since the 1970s, multiple reconstruction techniques have been proposed and are currently used, to extrapolate and quantify eruptive parameters from sampled tephra fall deposit datasets. Atmospheric transport and deposition processes strongly control the spatial distribution of tephra deposit; therefore, a large uncertainty affects mass derived estimations especially for fall layer that are not well exposed. This paper has two main aims: the first is to analyse the sensitivity to the deposit sampling strategy of reconstruction techniques. The second is to assess whether there are differences between the modelled values for emitted mass and grainsize, versus values estimated from the deposits. We find significant differences and propose a new correction strategy. A numerical approach is demonstrated by simulating with a dispersal code a mild explosive event occurring at Mt. Etna on 24 November 2006. Eruptive parameters are reconstructed by an inversion information collected after the eruption. A full synthetic deposit is created by integrating the deposited mass computed by the model over the computational domain (i.e., an area of 7.5 × 104 km 2). A statistical analysis based on 2000 sampling tests of 50 sampling points shows a large variability, up to 50 % for all the reconstruction techniques. Moreover, for some test examples Power Law errors are larger than estimated uncertainty. A similar analysis, on simulated grain-size classes, shows how spatial sampling limitations strongly reduce the utility of available information on the total grain size distribution. For example, information on particles coarser than ϕ(-4) is completely lost when sampling at 1.5 km from the vent for all columns with heights less than 2000 m above the vent. To correct for this effect an optimal sampling strategy and a new reconstruction method are presented. A sensitivity study shows that our method can be extended to a wide range of eruptive scenarios including those in which

  6. Evaluating DEM conditioning techniques, elevation source data, and grid resolution for field-scale hydrological parameter extraction

    NASA Astrophysics Data System (ADS)

    Woodrow, Kathryn; Lindsay, John B.; Berg, Aaron A.

    2016-09-01

    Although digital elevation models (DEMs) prove useful for a number of hydrological applications, they are often the end result of numerous processing steps that each contains uncertainty. These uncertainties have the potential to greatly influence DEM quality and to further propagate to DEM-derived attributes including derived surface and near-surface drainage patterns. This research examines the impacts of DEM grid resolution, elevation source data, and conditioning techniques on the spatial and statistical distribution of field-scale hydrological attributes for a 12,000 ha watershed of an agricultural area within southwestern Ontario, Canada. Three conditioning techniques, including depression filling (DF), depression breaching (DB), and stream burning (SB), were examined. The catchments draining to each boundary of 7933 agricultural fields were delineated using the surface drainage patterns modeled from LiDAR data, interpolated to a 1 m, 5 m, and 10 m resolution DEMs, and from a 10 m resolution photogrammetric DEM. The results showed that variation in DEM grid resolution resulted in significant differences in the spatial and statistical distributions of contributing areas and the distributions of downslope flowpath length. Degrading the grid resolution of the LiDAR data from 1 m to 10 m resulted in a disagreement in mapped contributing areas of between 29.4% and 37.3% of the study area, depending on the DEM conditioning technique. The disagreements among the field-scale contributing areas mapped from the 10 m LiDAR DEM and photogrammetric DEM were large, with nearly half of the study area draining to alternate field boundaries. Differences in derived contributing areas and flowpaths among various conditioning techniques increased substantially at finer grid resolutions, with the largest disagreement among mapped contributing areas occurring between the 1 m resolution DB DEM and the SB DEM (37% disagreement) and the DB-DF comparison (36.5% disagreement in mapped

  7. Electrostatic energy analyzer measurements of low energy zirconium beam parameters in a plasma sputter-type negative ion source.

    PubMed

    Malapit, Giovanni M; Mahinay, Christian Lorenz S; Poral, Matthew D; Ramos, Henry J

    2012-02-01

    A plasma sputter-type negative ion source is utilized to produce and detect negative Zr ions with energies between 150 and 450 eV via a retarding potential-type electrostatic energy analyzer. Traditional and modified semi-cylindrical Faraday cups (FC) inside the analyzer are employed to sample negative Zr ions and measure corresponding ion currents. The traditional FC registered indistinct ion current readings which are attributed to backscattering of ions and secondary electron emissions. The modified Faraday cup with biased repeller guard ring, cut out these signal distortions leaving only ringings as issues which are theoretically compensated by fitting a sigmoidal function into the data. The mean energy and energy spread are calculated using the ion current versus retarding potential data while the beam width values are determined from the data of the transverse measurement of ion current. The most energetic negative Zr ions yield tighter energy spread at 4.11 eV compared to the least energetic negative Zr ions at 4.79 eV. The smallest calculated beam width is 1.04 cm for the negative Zr ions with the highest mean energy indicating a more focused beam in contrast to the less energetic negative Zr ions due to space charge forces.

  8. Electrostatic energy analyzer measurements of low energy zirconium beam parameters in a plasma sputter-type negative ion source

    SciTech Connect

    Malapit, Giovanni M.; Mahinay, Christian Lorenz S.; Poral, Matthew D.; Ramos, Henry J.

    2012-02-15

    A plasma sputter-type negative ion source is utilized to produce and detect negative Zr ions with energies between 150 and 450 eV via a retarding potential-type electrostatic energy analyzer. Traditional and modified semi-cylindrical Faraday cups (FC) inside the analyzer are employed to sample negative Zr ions and measure corresponding ion currents. The traditional FC registered indistinct ion current readings which are attributed to backscattering of ions and secondary electron emissions. The modified Faraday cup with biased repeller guard ring, cut out these signal distortions leaving only ringings as issues which are theoretically compensated by fitting a sigmoidal function into the data. The mean energy and energy spread are calculated using the ion current versus retarding potential data while the beam width values are determined from the data of the transverse measurement of ion current. The most energetic negative Zr ions yield tighter energy spread at 4.11 eV compared to the least energetic negative Zr ions at 4.79 eV. The smallest calculated beam width is 1.04 cm for the negative Zr ions with the highest mean energy indicating a more focused beam in contrast to the less energetic negative Zr ions due to space charge forces.

  9. Source parameters for the 1952 Kern County earthquake, California: A joint inversion of leveling and triangulation observations

    USGS Publications Warehouse

    Bawden, G.W.

    2001-01-01

    Coseismic leveling and triangulation observations are used to determine the faulting geometry and slip distribution of the July 21, 1952, Mw 7.3 Kem County earthquake on the White Wolf fault. A singular value decomposition inversion is used to assess the ability of the geodetic network to resolve slip along a multisegment fault and shows that the network is sufficient to resolve slip along the surface rupture to a depth of 10 km. Below 10 km, the network can only resolve dip slip near the fault ends. The preferred source model is a two-segment right-stepping fault with a strike of 51?? and a dip of 75?? SW. The epicentral patch has deep (6-27 km) leftlateral oblique slip, while the northeastern patch has shallow (1-12.5 km) reverse slip. There is nearly uniform reverse slip (epicentral, 1.6 m; northeast, 1.9 m), with 3.6 m of left-lateral strike slip limited to the epicentral patch. The seismic moment is M0= 9.2 ?? 0.5 ?? 1019 N m (Mw= 7.2). The signal-to-noise ratio of the leveling and triangulation data is reduced by 96% and 49%, respectively. The slip distribution from the preferred model matches regional geomorphic features and may provide a driving mechanism for regional shortening across the Comanche thrust and structural continuity with the Scodie seismic lineament to the northeast.

  10. Quartz size/shape relationships: variable size/shape relationships of detrital quartz reflect differences in source/transport parameters

    SciTech Connect

    Ehrlich, R.; Eggers, M.R.; Goodman, E.D.

    1985-01-01

    A common misconception is that as size decreases, quartz grains become progressively more angular. All possible size/shape relationships can and do occur including: 1) no relationship, 2) fine sizes, more rounded, 3) finer sized more angular, and 4) size/shape discontinuities where shape is constant over a wide range and then changes and stays constant over the remaining range. Detritus from large, long established flood plains (Mississippi, Ganges, Amazon) display a continuous change in shape with size. Detritus from primary sources generally display no size/shape effect. Small rivers commonly exhibit size/shape discontinuities. The origin of a particular size/shape relationship arises from two opposing tendencies. Finer detritus travel much faster than coarser sands. Thus silts from one provenance can overtake coarser material of different provenance. If flood plains are large and long-lived, the contribution of individual tributaries is diluted almost to indetectibility and all sizes have time enough to reach the sea. In such situations the size/shape relationship reflects a steady state of equilibrium. In smaller rivers individual tributaries can provide significant proportions of grains to flood plains with characteristic sizes and shapes leading to discrete shifts in the size/shape curve.

  11. Influence of particle size and calcium source on production performance, egg quality, and bone parameters in laying ducks.

    PubMed

    Wang, S; Chen, W; Zhang, H X; Ruan, D; Lin, Y C

    2014-10-01

    The influence of calcium source (limestone and oyster shell) and particle size (<0.1 mm; 0.85 to 2 mm) on laying performance, egg quality, and bone properties were examined in laying ducks by a 2 × 2 factorial arrangement of treatments. Longyan females (288) with similar BW at 24 wk of age were randomly allotted into 4 treatments, each with 6 replicates of 12 individually caged birds and studied over the following 12 wk. Particle size affected egg weight and feed conversion (P < 0.05). Large particle size increased shell breaking strength, albumen height, Haugh unit, and shell content of phosphorus and magnesium (P < 0.05), but had no effect on egg shape, yolk color, shell thickness, or the weight proportion of shell. There were no effects of particle size on tibial properties: dry defatted weight, calcium content, or breaking strength. Limestone increased albumen height, shell content of calcium and phosphorus, and the breaking strength of tibia (P < 0.05). It is concluded that limestone with a large particle size provided for superior productive performance, egg quality, and bone characteristics and is more suitable than oyster shell for practical applications.

  12. Estimation and propagation of volcanic source parameter uncertainty in an ash transport and dispersal model: application to the Eyjafjallajokull plume of 14-16 April 2010

    NASA Astrophysics Data System (ADS)

    Bursik, Marcus; Jones, Matthew; Carn, Simon; Dean, Ken; Patra, Abani; Pavolonis, Michael; Pitman, E. Bruce; Singh, Tarunraj; Singla, Puneet; Webley, Peter; Bjornsson, Halldor; Ripepe, Maurizio

    2012-12-01

    Data on source conditions for the 14 April 2010 paroxysmal phase of the Eyjafjallajökull eruption, Iceland, have been used as inputs to a trajectory-based eruption column model, bent. This model has in turn been adapted to generate output suitable as input to the volcanic ash transport and dispersal model, puff, which was used to propagate the paroxysmal ash cloud toward and over Europe over the following days. Some of the source parameters, specifically vent radius, vent source velocity, mean grain size of ejecta, and standard deviation of ejecta grain size have been assigned probability distributions based on our lack of knowledge of exact conditions at the source. These probability distributions for the input variables have been sampled in a Monte Carlo fashion using a technique that yields what we herein call the polynomial chaos quadrature weighted estimate (PCQWE) of output parameters from the ash transport and dispersal model. The advantage of PCQWE over Monte Carlo is that since it intelligently samples the input parameter space, fewer model runs are needed to yield estimates of moments and probabilities for the output variables. At each of these sample points for the input variables, a model run is performed. Output moments and probabilities are then computed by properly summing the weighted values of the output parameters of interest. Use of a computational eruption column model coupled with known weather conditions as given by radiosonde data gathered near the vent allows us to estimate that initial mass eruption rate on 14 April 2010 may have been as high as 108 kg/s and was almost certainly above 107 kg/s. This estimate is consistent with the probabilistic envelope computed by PCQWE for the downwind plume. The results furthermore show that statistical moments and probabilities can be computed in a reasonable time by using 94 = 6,561 PCQWE model runs as opposed to millions of model runs that might be required by standard Monte Carlo techniques. The

  13. Effect of different fat sources on in vitro degradation of nutrients and certain blood parameters in sheep.

    PubMed

    Fébel, Hedvig; Husvéth, F; Veresegyházy, T; Andrásofszky, Emese; Várhegyi, Ildikó; Huszár, Szilvia

    2002-01-01

    This study was designed to determine the effects of calcium salt of palm oil fatty acids (CS), hydroxyethylsoyamide (HESA), butylsoyamide (BSA) and soybean oil (SO) on degradation of crude protein and fibre in vitro, and on the blood plasma lipid parameters in vivo. Five mature wethers (body weight 75 kg) were fed five diets in a 5 x 5 Latin square experiment. The control diet consisted of 50% meadow hay and 50% concentrate with no added fat. The control diet was supplemented with CS, HESA, BSA, or SO. Fat was added at 3.5% of dietary dry matter (DM). The final ether extract content of the ration was near 6%. Each period lasted 20 days. Fat supplements, except HESA, consistently decreased the in vitro DM disappearance of soybean meal as compared to control. In contrast to the effect of other treatments, crude protein degradation was greatest in the test tubes with inocula obtained from sheep fed diet with HESA. Fat supplements equally inhibited the DM and fibre breakdown of alfalfa pellet. CS and HESA seemed to be less detrimental to in vitro fermentation of neutral detergent fibre (NDF) than BSA and SO. All fat supplements increased blood plasma triglyceride, cholesterol and total lipid content. Plasma concentration of cholesterol and total lipid was highest with SO. The inclusion of CS in the diet increased 16:0, while all fat supplements increased plasma 18:0 and decreased 16:1 and 18:1 fatty acid content. Plasma 18:2n-6 was not changed by feeding CS and SO. However, compared to the control diet, 18:2n-6 increased with 12 and 41% in plasma fatty acids when sheep were fed HESA and BSA, respectively. The results showed that plasma concentration of linoleic acid was enhanced more when the amide was synthesised from butylamine than when from ethanolamine. PMID:12113177

  14. Growth performance and physiological parameters of conventional and specified pathogen-free rats fed autoclaved diets with different protein sources.

    PubMed

    Barszcz, M; Paradziej-Łukowicz, J; Taciak, M; Tuśnio, A; Staśkiewicz, Ł; Muszyńska-Furas, B; Lewandowska, A; Pastuszewska, B; Skomiał, J

    2015-12-01

    The effects of feeding autoclaved commercial SSNIFF (SN) diet and diets containing soya bean (S) and casein (C) to growing conventional (CON) and specified pathogen-free (SPF) rats were determined. Diets S, C and SN, autoclaved at 121 °C during 20 min (T1), at 134 °C during 10 min (T2) and non-autoclaved (T0), were fed during four weeks, each to 8 CON males and 8 females of mean initial body weight 56 g, kept individually. Diets S, C and SN, autoclaved at T1, were fed during two months, each to 20 SPF males and 20 females of mean initial body weight 58 g, kept in group of 5 animals per cage. In CON rats, autoclaving did not affect feed intake and weight gain, decreased thyroid and stomach weight, increased caecal tissue and digesta weight, and concentrations of isobutyric, isovaleric and valeric acid in caecal digesta. Among biochemical blood parameters, autoclaving decreased only total protein concentration and aspartate aminotransferase activity. Feeding C diet resulted in lower feed intake and weight gain in CON and SPF males. Diet affected organ weights and the greatest differences were found in rats on SN diet for weights of stomach, caecum and female reproductive organs. Diet affected concentration of all short-chain fatty acids, pH and weight of caecal digesta, the most important being the greatest butyric acid concentration on SN diet and isoacids on C diet. It is concluded that autoclaving of both soya-containing and soya-free diets does not affect negatively animal performance and physiology.

  15. Spectral P-wave magnitudes, magnitude spectra and other source parameters for the 1990 southern Sudan and the 2005 Lake Tanganyika earthquakes

    NASA Astrophysics Data System (ADS)

    Moussa, Hesham Hussein Mohamed

    2008-10-01

    Teleseismic Broadband seismograms of P-waves from the May 1990 southern Sudan and the December, 2005 Lake Tanganyika earthquakes; the western branch of the East African Rift System at different azimuths have been investigated on the basis of magnitude spectra. The two earthquakes are the largest shocks in the East African Rift System and its extension in southern Sudan. Focal mechanism solutions along with geological evidences suggest that the first event represents a complex style of the deformation at the intersection of the northern branch of the western branch of the East African Rift and Aswa Shear Zone while the second one represents the current tensional stress on the East African Rift. The maximum average spectral magnitude for the first event is determined to be 6.79 at 4 s period compared to 6.33 at 4 s period for the second event. The other source parameters for the two earthquakes were also estimated. The first event had a seismic moment over fourth that of the second one. The two events are radiated from patches of faults having radii of 13.05 and 7.85 km, respectively. The average displacement and stress drop are estimated to be 0.56 m and 1.65 MPa for the first event and 0.43 m and 2.20 MPa for the second one. The source parameters that describe inhomogeneity of the fault are also determined from the magnitude spectra. These additional parameters are complexity, asperity radius, displacements across the asperity and ambient stress drop. Both events produce moderate rupture complexity. Compared to the second event, the first event is characterized by relatively higher complexity, a low average stress drop and a high ambient stress. A reasonable explanation for the variations in these parameters may suggest variation in the strength of the seismogenic fault which provides the relations between the different source parameters. The values of stress drops and the ambient stresses estimated for both events indicate that these earthquakes are of interplate

  16. Diurnal variation of particle-bound PAHs in an urban area of Spain using TD-GC/MS: Influence of meteorological parameters and emission sources

    NASA Astrophysics Data System (ADS)

    Elorduy, I.; Elcoroaristizabal, S.; Durana, N.; García, J. A.; Alonso, L.

    2016-08-01

    Short -term particulate concentrations of 13 polycyclic aromatic hydrocarbons (PAHs) in PM10 were determined in the urban area of Bilbao (Spain). The analysis was performed by thermal desorption coupled with gas chromatography-mass spectrometry (TD-GC/MS), which enabled to use three diurnal periods of 8 h sampling basis time resolution. A total of 105 PM10 samples were collected during 5 months in 2013. Diurnal average concentration of total PAHs (∑13 PAHs) ranged from 1.18 to 9.78 ng m-3; and from 0.06 to 0.70 ng m-3 for benzo[a]pyrene. The presence of high concentrations of benzo[b]fluoranthene, pyrene, fluoranthene and chrysene, and the significant PAHs diurnal variations due to the sampling period, pointed out the influence of mixing anthropogenic sources and meteorological conditions. The diurnal pattern of source contributions was assessed by binary diagnostic ratios and principal component analysis (PCA). These results showed the prevalence of pyrogenic sources coming from traffic and coal/coke combustion sources. Moreover, the PCA differentiated a diurnal pattern of source contributions. The influence of meteorological factors was studied by Pearson correlation analysis and multiple linear regression. Three factors, temperature, wind speed and atmospheric pressure, were identified as the most significant ones affecting diurnal PAHs concentrations. Finally, PCA of the PAHs levels, regulated atmospheric pollutants and meteorological parameters showed that diurnal PAHs concentrations were mainly influenced by variations in the emission sources, atmospheric oxidants such as ozone, and temperature conditions. These results provide further insight into the PAHs diurnal patterns in urban areas by using higher temporal resolutions.

  17. Air pollution of Moscow by the carbon monoxide and aerosols, boundary layer parameters and estimation of the CO sources intensity.

    NASA Astrophysics Data System (ADS)

    Rakitin, V.; Fokeeva, E.; Kuznetsov, R.; Emilenko, A.; Kopeikin, V.

    2009-04-01

    The results of measurements of the carbon monoxide total content, the soot and submicron aerosols content are given for the period 2005-2008 over Moscow. Two identical grating spectrometers of medium resolution (0,2sm-1) are used with appropriate solar tracking systems, one of which is located outside the city at Zvenigorod Scientific Station (ZSS 56oN, 38oE, 60km West from Moscow in the rural zone) and the other one is inside a city center. This method makes possible to determine the characteristics of anthropogenic pollution, urban part of the CO content. Some simultaneously measurements of aerosols content, the CO column and CO background concentrations in Moscow, autumn 2007 are presented. Nephelometer and quartz filters for soot sampling were used for aerosols measurements. Correlations coefficients between aerosols, CO background concentration and urban part of the CO content were obtained. Permanent sounding of boundary layer was carried out using acoustic locator (SODAR) LATAN-3. Applications of SODAR data (profile of wind speed and inversion height) makes possible to forecast of air pollution situations in megacities area. We obtained the correlation coefficients for the urban part of the CO content with the wind speed for cold and warm seasons. Analysis results of measurements demonstrated preeminent influence of the wind in certain boundary layer (up to 500m) upon the CO extension. The intensity of CO sources in Moscow was estimated. The systematization of CO diurnal variations for different meteorological conditions was performed. Comparing our results with the results of the earlier measurements period (1993-2005), we found out that the urban part of the CO content in the surface air layer over the city did not increase in spite of more than tripled number of motor-vehicles in Moscow. So using the applications of this spectroscopic method we can obtain the air pollution trend from the averaged air pollution measured values.

  18. Developing Accurate Spatial Maps of Cotton Fiber Quality Parameters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Awareness of the importance of cotton fiber quality (Gossypium, L. sps.) has increased as advances in spinning technology require better quality cotton fiber. Recent advances in geospatial information sciences allow an improved ability to study the extent and causes of spatial variability in fiber p...

  19. Steering Landsat-oriented, open-source risk-mapping tools towards Copernicus: tuning parameters on Sentinel-2 data

    NASA Astrophysics Data System (ADS)

    De Vecchi, Daniele; Dell'Acqua, Fabio

    2016-04-01

    consortium guarantees support and improvements to the proposed set of tools. Keywords: Vulnerability monitoring, exposure monitoring, remote sensing, optical imagery, Copernicus, Sentinel-2, open-source software tools

  20. Monte Carlo calculations and experimental measurements of the TG-43U1-recommended dosimetric parameters of 125I (Model IR-Seed2) brachytherapy source.

    PubMed

    Sheikholeslami, Sahar; Nedaie, Hasan Ali; Sadeghi, Mahdi; Pourbeigi, Hossein; Shahzadi, Sohrab; Zehtabian, Mehdi; Hasani, Mohsen; Meigooni, Ali S

    2016-01-01

    A new design of 125I (Model IR-Seed2) brachytherapy source has been manufactured recently at the Applied Radiation Research School, Nuclear Science and Technology Research Institute in Iran. The source consists of six resin beads (0.5 mm diameter) that are sealed in a cylindrical titanium capsule of 0.7 mm internal and 0.8 mm external diameters. This work aims to evaluate the dosimetric parameters of the newly designed 125I source using experimental measurements and Monte Carlo (MC) simulations. Dosimetric characteristics (dose rate constant, radial dose function, and 2D and 1D anisotropy functions) of the IR-Seed2 were determined using experimental measurements and MC simulations following the recommendations by the Task Group 43 (TG-43U1) report of the American Association of Physicists in Medicine (AAPM). MC simulations were performed using the MCNP5 code in water and Plexiglas, and experimental measurements were carried out using thermoluminescent dosimeters (TLD-GR207A) in Plexiglas phantoms. The measured dose to water in Plexiglas data were used for verification of the accuracy of the source and phantom geometry in the Monte Carlo simulations. The final MC simulated data to water in water were recommended for clinical applications. The MC calculated dose rate constant (Λ) of the IR-Seed2 125I seed in water was found to be 0.992 ± 0.025 cGy h-1U-1. Additionally, its radial dose function by line and point source approximations, gL(r) and gp(r), calculated for distances from 0.1 cm to 7 cm. The values of gL(r) at radial distances from 0.5 cm to 5 cm were measured in a Plexiglas phantom to be between 1.212 and 0.413. The calculated and measured of values for 2D anisotropy function, F(r, θ), were obtained for the radial distances ranging from 1.5 cm to 5 cm and angular range of 0°-90° in a Plexiglas phantom. Also, the 2D anisotropy function was calculated in water for the clinical application. The results of these investigations show that the uncertainty of

  1. Optimization of plasma parameters with magnetic filter field and pressure to maximize H- ion density in a negative hydrogen ion source

    NASA Astrophysics Data System (ADS)

    Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young; Chung, Kyoung-Jae; Hwang, Y. S.

    2016-02-01

    Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuir probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H- populations for various filter field strengths and pressures. Enhanced H- population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H- sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region.

  2. Estimation of earthquake source parameters of the June 22, 2002 Changoureh-Avaj event, NW Iran, using aftershocks distribution and far-field data

    NASA Astrophysics Data System (ADS)

    Sadeghi, H.; Suzuki, S.; Hosseini, S. K.; Fujii, Y.; Fatemi Aghda, S. M.

    2003-04-01

    The Changoureh-Avaj Earthquake occurred on the 22 June 2002 in about 225 km west of the capital of Iran-Tehran. Many houses in about 50 villages with adobe constructions collapsed, causing the death of 230 people and injuries to more than 1400. This earthquake is of great importance not only for seismological interests, but also for knowing fault activity around Tehran with about 7 million populations. The present work is to estimate the earthquake source parameters by far-field body waves of main shock and the fault geometry inferred from the aftershocks distribution. The aftershocks distribution images a thrust fault surface with 26 degrees dip to the south from 0 to 15 km depth and the dip direction is S10W. Beside of the main fault, a conjugate sub-fault could be also imaged that suggests the main shock hypocenter at about 8 km. Based on this fault geometry and using the data of Khorasan Earthquake Network (Ferdowsi University of Mashhad) broadband stations, about 750 to 1000 km epicentral distances, we study the source parameters. The far-field body waves and displacement spectral analysis, assuming a rectangular fault, yield a fault length of 28 km, stress drop of 0.4 MPa (4 bars), average dislocation of 12 cm and the seismic moment of 3.1E18 Nm. The rake is determined between 90 and 105 degrees.

  3. Optimization of plasma parameters with magnetic filter field and pressure to maximize H⁻ ion density in a negative hydrogen ion source.

    PubMed

    Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young; Chung, Kyoung-Jae; Hwang, Y S

    2016-02-01

    Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuir probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H(-) populations for various filter field strengths and pressures. Enhanced H(-) population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H(-) sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region. PMID:26932018

  4. Magnetic Flux of EUV Arcade and Dimming Regions as a Relevant Parameter for Early Diagnostics of Solar Eruptions - Sources of Non-recurrent Geomagnetic Storms and Forbush Decreases

    NASA Astrophysics Data System (ADS)

    Chertok, I. M.; Grechnev, V. V.; Belov, A. V.; Abunin, A. A.

    2013-01-01

    This study aims at the early diagnostics of the geoeffectiveness of coronal mass ejections (CMEs) from quantitative parameters of the accompanying EUV dimming and arcade events. We study events of the 23th solar cycle, in which major non-recurrent geomagnetic storms (GMS) with Dst<-100 nT are sufficiently reliably identified with their solar sources in the central part of the disk. Using the SOHO/EIT 195 Å images and MDI magnetograms, we select significant dimming and arcade areas and calculate summarized unsigned magnetic fluxes in these regions at the photospheric level. The high relevance of this eruption parameter is displayed by its pronounced correlation with the Forbush decrease (FD) magnitude, which, unlike GMSs, does not depend on the sign of the B z component but is determined by global characteristics of ICMEs. Correlations with the same magnetic flux in the solar source region are found for the GMS intensity (at the first step, without taking into account factors determining the B z component near the Earth), as well as for the temporal intervals between the solar eruptions and the GMS onset and peak times. The larger the magnetic flux, the stronger the FD and GMS intensities are and the shorter the ICME transit time is. The revealed correlations indicate that the main quantitative characteristics of major non-recurrent space weather disturbances are largely determined by measurable parameters of solar eruptions, in particular, by the magnetic flux in dimming areas and arcades, and can be tentatively estimated in advance with a lead time from 1 to 4 days. For GMS intensity, the revealed dependencies allow one to estimate a possible value, which can be expected if the B z component is negative.

  5. Modeling of Morelia Fault Earthquake (Mw=5.4) source fault parameters using the coseismic ground deformation and groundwater level changes data

    NASA Astrophysics Data System (ADS)

    Sarychikhina, O.; Glowacka, E.; Mellors, R. J.; Vázquez, R.

    2009-12-01

    On 24 May 2006 at 04:20 (UTC) a moderate-size (Mw=5.4) earthquake struck the Mexicali Valley, Baja California, México, roughly 30 km to the southeast of the city of Mexicali, in the vicinity of the Cerro Prieto Geothermal Field (CPGF). The earthquake occurred on the Morelia fault, one of the east-dipping normal faults in the Mexicali Valley. Locally, this earthquake was strongly felt and caused minor damage. The event created 5 km of surface rupture and down-dip displacements of up to 25-30 cm were measured at some places along this surface rupture. Associated deformation was measured by vertical crackmeter, leveling profile, and Differential Synthetic Aperture Radar Interferometry (D-InSAR). A coseismic step-like groundwater level change was detected at 7 wells. The Mw=5.4 Morelia Fault earthquake had significant scientific interest, first, because of surprisingly strong effects for an earthquake of such size; second, the variability of coseismic effects data from different ground-based and space-based techniques which allows to the better constrain of the source fault parameters. Source parameters for the earthquake were estimated using forward modeling of both surface deformation data and static volume strain change (inferred from coseismic changes in groundwater level). All ground deformation data was corrected by anthropogenic component caused by the geothermal fluid exploitation in the CPGF. Modeling was based on finite rectangular fault embedded in an elastic media. The preferred fault model has a strike, rake, and dip of (48°, -89°, 45°) and has a length of 5.2 km, width of 6.7 km, and 34 cm of uniform slip. The geodetic moment, based on the modeled fault parameters, is 1.18E+17 Nm. The model matches the observed surface deformation, expected groundwater level changes, and teleseismic moment reasonably well and explains in part why the earthquake was so strongly felt in the area.

  6. Seasonal and diurnal variations of atmospheric PAHs and OCPs in a suburban paddy field, South China: Impacts of meteorological parameters and sources

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Qilu; Wang, Shaorui; Wang, Yujie; Luo, Chunling; Li, Jun; Zhang, Gan

    2015-07-01

    The atmospheric contaminations of polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs), and DDTs have been extensively monitored for decades, but contaminations in agricultural paddy fields have rarely been reported. We measured the atmospheric PAH, HCH, and DDT constituents during different rice growth stages in a suburban paddy field in South China. Diurnal variations were found in the atmospheric concentrations of PAHs and HCHs, but not for DDTs. Additional nocturnal emissions and meteorological conditions, such as low nocturnal stable atmospheric boundary layers, may be mainly responsible for the higher PAH and HCH levels at night, respectively. Atmospheric concentrations of PAH, HCH, and DDT constituents varied with rice growth stage, but no regular seasonal variation was found, suggesting that rice growth has no significant influence on the atmospheric concentrations of these chemicals. A correlation analysis suggested that meteorological parameters, such as temperature, precipitation, mixing layer height, or wind speed, may directly or indirectly affect the air concentrations of PAHs, HCHs, and DDTs. Source apportionment showed that atmospheric PAHs, HCHs, and DDTs in the paddy field originated from mixed sources, and the contribution of each source varied with time. The isomer ratio of fluoranthene/(fluoranthene + pyrene) may result in an invalid diagnosis of PAHs.

  7. Novel maturity parameters for mature to over-mature source rocks and oils based on the distribution of phenanthrene series compounds.

    PubMed

    Wang, Zixiang; Wang, Yongli; Wu, Baoxiang; Wang, Gen; Sun, Zepeng; Xu, Liang; Zhu, Shenzhen; Sun, Lina; Wei, Zhifu

    2016-03-01

    Pyrolysis experiments of a low-mature bitumen sample originated from Cambrian was conducted in gold capsules. Abundance and distribution of phenanthrene series compounds in pyrolysis products were measured by GC-MS to investigate their changes with thermal maturity. Several maturity parameters based on the distribution of phenanthrene series compounds have been discussed. The results indicate that the distribution changes of phenanthrene series compounds are complex, and cannot be explained by individual reaction process during thermal evolution. The dealkylation cannot explain the increase of phenanthrene within the EasyRo range of 0.9% ∼ 2.1%. Adding of phenanthrene into maturity parameters based on the methylphenanthrene isomerization is unreasonable, even though MPI 1 and MPI 2 could be used to some extent. Two additional novel and an optimized maturation parameters based on the distribution of phenanthrene series compounds are proposed and their relationships to EasyRo% (x) are established: log(MPs/P) = 0.19x + 0.08 (0.9% < EasyRo% < 2.1%); log(MPs/P) = 0.64x - 0.86 (2.1% < EasyRo% < 3.4%); log(DMPs/TMPs) = 0.71x - 0.55 (0.9% < EasyRo% < 3.4%); log(MTR) = 0.84x - 0.75 (0.9% < EasyRo% < 3.4%). These significant positive correlations are strong argument for using log(MPs/P), log(DMPs/TMPs) and log(MTR) as maturity parameters, especially for mature to over-mature source rocks. PMID:27441263

  8. Constraining Earthquake Source Parameters in Rupture Patches and Rupture Barriers on Gofar Transform Fault, East Pacific Rise from Ocean Bottom Seismic Data

    NASA Astrophysics Data System (ADS)

    Moyer, P. A.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.

    2015-12-01

    On Gofar transform fault on the East Pacific Rise (EPR), Mw ~6.0 earthquakes occur every ~5 years and repeatedly rupture the same asperity (rupture patch), while the intervening fault segments (rupture barriers to the largest events) only produce small earthquakes. In 2008, an ocean bottom seismometer (OBS) deployment successfully captured the end of a seismic cycle, including an extensive foreshock sequence localized within a 10 km rupture barrier, the Mw 6.0 mainshock and its aftershocks that occurred in a ~10 km rupture patch, and an earthquake swarm located in a second rupture barrier. Here we investigate whether the inferred variations in frictional behavior along strike affect the rupture processes of 3.0 < M < 4.5 earthquakes by determining source parameters for 100 earthquakes recorded during the OBS deployment.Using waveforms with a 50 Hz sample rate from OBS accelerometers, we calculate stress drop using an omega-squared source model, where the weighted average corner frequency is derived from an empirical Green's function (EGF) method. We obtain seismic moment by fitting the omega-squared source model to the low frequency amplitude of individual spectra and account for attenuation using Q obtained from a velocity model through the foreshock zone. To ensure well-constrained corner frequencies, we require that the Brune [1970] model provides a statistically better fit to each spectral ratio than a linear model and that the variance is low between the data and model. To further ensure that the fit to the corner frequency is not influenced by resonance of the OBSs, we require a low variance close to the modeled corner frequency. Error bars on corner frequency were obtained through a grid search method where variance is within 10% of the best-fit value. Without imposing restrictive selection criteria, slight variations in corner frequencies from rupture patches and rupture barriers are not discernable. Using well-constrained source parameters, we find an

  9. High Frequency QRS ECG Accurately Detects Cardiomyopathy

    NASA Technical Reports Server (NTRS)

    Schlegel, Todd T.; Arenare, Brian; Poulin, Gregory; Moser, Daniel R.; Delgado, Reynolds

    2005-01-01

    High frequency (HF, 150-250 Hz) analysis over the entire QRS interval of the ECG is more sensitive than conventional ECG for detecting myocardial ischemia. However, the accuracy of HF QRS ECG for detecting cardiomyopathy is unknown. We obtained simultaneous resting conventional and HF QRS 12-lead ECGs in 66 patients with cardiomyopathy (EF = 23.2 plus or minus 6.l%, mean plus or minus SD) and in 66 age- and gender-matched healthy controls using PC-based ECG software recently developed at NASA. The single most accurate ECG parameter for detecting cardiomyopathy was an HF QRS morphological score that takes into consideration the total number and severity of reduced amplitude zones (RAZs) present plus the clustering of RAZs together in contiguous leads. This RAZ score had an area under the receiver operator curve (ROC) of 0.91, and was 88% sensitive, 82% specific and 85% accurate for identifying cardiomyopathy at optimum score cut-off of 140 points. Although conventional ECG parameters such as the QRS and QTc intervals were also significantly longer in patients than controls (P less than 0.001, BBBs excluded), these conventional parameters were less accurate (area under the ROC = 0.77 and 0.77, respectively) than HF QRS morphological parameters for identifying underlying cardiomyopathy. The total amplitude of the HF QRS complexes, as measured by summed root mean square voltages (RMSVs), also differed between patients and controls (33.8 plus or minus 11.5 vs. 41.5 plus or minus 13.6 mV, respectively, P less than 0.003), but this parameter was even less accurate in distinguishing the two groups (area under ROC = 0.67) than the HF QRS morphologic and conventional ECG parameters. Diagnostic accuracy was optimal (86%) when the RAZ score from the HF QRS ECG and the QTc interval from the conventional ECG were used simultaneously with cut-offs of greater than or equal to 40 points and greater than or equal to 445 ms, respectively. In conclusion 12-lead HF QRS ECG employing

  10. A simplified analytical approach to estimate the parameters required for strength determination of HDR 192Ir brachytherapy sources using a Farmer-type ionization chamber.

    PubMed

    Kumar, Sudhir; Srinivasan, P; Sharma, S D; Mayya, Y S

    2012-01-01

    Measuring the strength of high dose rate (HDR) (192)Ir brachytherapy sources on receipt from the vendor is an important component of a quality assurance program. Owing to their ready availability in radiotherapy departments, the Farmer-type ionization chambers are also used to determine the strength of HDR (192)Ir brachytherapy sources. The use of a Farmer-type ionization chamber requires the estimation of the scatter correction factor along with positioning error (c) and the constant of proportionality (f) to determine the strength of HDR (192)Ir brachytherapy sources. A simplified approach based on a least squares method was developed for estimating the values of f and M(s). The seven distance method was followed to record the ionization chamber readings for parameterization of f and M(s). Analytically calculated values of M(s) were used to determine the room scatter correction factor (K(sc)). The Monte Carlo simulations were also carried out to calculate f and K(sc) to verify the magnitude of the parameters determined by the proposed analytical approach. The value of f determined using the simplified analytical approach was found to be in excellent agreement with the Monte Carlo simulated value (within 0.7%). Analytically derived values of K(sc) were also found to be in good agreement with the Monte Carlo calculated values (within 1.47%). Being far simpler than the presently available methods of evaluating f, the proposed analytical approach can be adopted for routine use by clinical medical physicists to estimate f by hand calculations.

  11. Evaluation of maize grain and polyunsaturated fatty acid (PUFA) as energy sources for breeding rams based on hormonal, sperm functional parameters and fertility.

    PubMed

    Selvaraju, Sellappan; Raju, Priyadarshini; Rao, Somu Bala Nageswara; Raghavendra, Subbarao; Nandi, Sumantha; Dineshkumar, Dhanasekaran; Thayakumar, Allen; Parthipan, Shivashanmugam; Ravindra, Janivara Parameswaraiah

    2012-01-01

    The objective of the present study was to elucidate the effect of different sources of dietary energy (maize vs polyunsaturated fatty acid (PUFA) on semen functional parameters and fertility of adult rams. Eighteen adult rams were divided into two groups (maize and PUFA, n=9). The main energy source for the rams in the maize group was coarsely ground maize grain, whereas in the PUFA group it was sunflower oil (rich in 18:2 linoleic acid, an omega-6 acid). The ration was fed for a minimum period of 60 days and thereafter semen was collected for evaluation. The proportion of progressive forward motility was significantly (P<0.05) higher in the PUFA group compared with the maize group. Sperm lipid peroxidation as measured by malondialdehyde formation (µM per 1×10(9) spermatozoa) was significantly (P<0.05) higher in the PUFA group compared with the maize group. When the semen was diluted with Tris-egg yolk-citrate buffer and incubated for 24h at 4°C, the proportions of plasmalemma integrity, the sperm subpopulation positive for functional membrane and acrosomal integrities, and mitochondrial membrane potential were significantly (P<0.05) higher in PUFA-fed than in maize-fed animals. The different sources of energy did not influence the serum and seminal plasma IGF-I levels. The cleavage rate (percentage) did not differ significantly between PUFA- (45.4±4.91) and maize- (44.63±6.8) fed animals. In conclusion, PUFA feeding influenced sperm quality by altering or stabilising membrane integrity. The present study indicates that PUFA may improve semen quality but did not improve in vitro fertilisation. PMID:22697117

  12. Evaluation of maize grain and polyunsaturated fatty acid (PUFA) as energy sources for breeding rams based on hormonal, sperm functional parameters and fertility.

    PubMed

    Selvaraju, Sellappan; Raju, Priyadarshini; Rao, Somu Bala Nageswara; Raghavendra, Subbarao; Nandi, Sumantha; Dineshkumar, Dhanasekaran; Thayakumar, Allen; Parthipan, Shivashanmugam; Ravindra, Janivara Parameswaraiah

    2012-01-01

    The objective of the present study was to elucidate the effect of different sources of dietary energy (maize vs polyunsaturated fatty acid (PUFA) on semen functional parameters and fertility of adult rams. Eighteen adult rams were divided into two groups (maize and PUFA, n=9). The main energy source for the rams in the maize group was coarsely ground maize grain, whereas in the PUFA group it was sunflower oil (rich in 18:2 linoleic acid, an omega-6 acid). The ration was fed for a minimum period of 60 days and thereafter semen was collected for evaluation. The proportion of progressive forward motility was significantly (P<0.05) higher in the PUFA group compared with the maize group. Sperm lipid peroxidation as measured by malondialdehyde formation (µM per 1×10(9) spermatozoa) was significantly (P<0.05) higher in the PUFA group compared with the maize group. When the semen was diluted with Tris-egg yolk-citrate buffer and incubated for 24h at 4°C, the proportions of plasmalemma integrity, the sperm subpopulation positive for functional membrane and acrosomal integrities, and mitochondrial membrane potential were significantly (P<0.05) higher in PUFA-fed than in maize-fed animals. The different sources of energy did not influence the serum and seminal plasma IGF-I levels. The cleavage rate (percentage) did not differ significantly between PUFA- (45.4±4.91) and maize- (44.63±6.8) fed animals. In conclusion, PUFA feeding influenced sperm quality by altering or stabilising membrane integrity. The present study indicates that PUFA may improve semen quality but did not improve in vitro fertilisation.

  13. Source Parameters and Crustal Attenuation in Interior Alaska: Estimates Using Broadband Lg-Wave Spectra Derived from the BEAAR Experiment Data.

    NASA Astrophysics Data System (ADS)

    Marriott, D. A.; Hansen, R. A.

    2002-12-01

    Source parameters, site effects, and regional crustal attenuation in interior Alaska were estimated using displacement amplitude spectra of Lg phase arrivals derived from the Broadband Experiment Across the Alaska Range (BEAAR) seismic data. The BEAAR project consisted of 36 three component broadband seismometers temporarily installed across the Alaska Range. This array stretched across a large portion of interior Alaska, providing excellent recordings of regional events. The model parameters were estimated using a simultaneous nonlinear least squares inversion including all the spectral data. The source parameters estimated were the seismic moment, Mo, and the corner frequency, fo, for each event. The values of Mo were well constrained and yielded an empirical relationship between ML and Mo for interior Alaska. Estimates of the corner frequency for each event, along with the Mo values, yielded an estimate of stress drop for each event. For events larger then ML = 3 in Alaska, stress drop showed no significant dependence on magnitude. A frequency dependent local site amplification term was estimated for each station in the inversion as an average of the residuals for each station over many events. The inclusion of this site term reduced the total residuals of the regional attenuation model calculations. A preliminary model for regional attenuation of the Lg seismic phase averaged over all tectonic regions across continental Alaska from BEAAR data was derived to be: QLg(f) = 166f0.58. This model was estimated from 123 shallow earthquakes larger than M =3 located in continental Alaska, and more than 1,000 spectra. Because the Lg phase was trapped in the crustal wave-guide, QLg gave a good representation of attenuation in the crust, and appears to correlate with crustal structure. Estimates of attenuation for each ray path show local variation in QLg. This variation may be caused by changes in crustal structure such as faulting, deformation, or differences in

  14. NNLOPS accurate associated HW production

    NASA Astrophysics Data System (ADS)

    Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

    2016-06-01

    We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

  15. Search for along-strike variations in earthquake source parameters for seismicity within the February 27, 2010 Mw=8.8 Maule, Chile earthquake rupture zone

    NASA Astrophysics Data System (ADS)

    Anderson, K. E.; Bilek, S. L.

    2011-12-01

    The February 27, 2010 Maule earthquake (Mw 8.8) ruptured a ~600 km segment of the Chilean subduction zone just north of the 1960 rupture zone. Results from back-projection analysis of the mainshock suggest along-strike variation in the energy release, with low frequency, slow velocity slip along the southern end of the rupture. Thus, if these variations are driven by variations in the fault zone, we would expect to see similar variations in pre- and/or post-mainshock seismicity along the margin. Here we examine other earthquakes within this region to determine if the along-strike variation is observed in either previous events or aftershocks. For other large magnitude (Mw ≥ 5.5) earthquakes from 1990-2011, we compute source time functions to assess rupture characteristics, specifically rupture duration and complexity, that may vary both along strike and with time. Preliminary results for the large magnitude events suggest no clear along-strike pattern in these rupture characteristics, thus not mimicking the mainshock results. We are also determining source parameters for the smaller magnitude aftershocks recorded by the regional Chile RAPID seismic network (CHAMP), which was placed along the rupture zone to record roughly 7 months of aftershocks. First results are a catalog of focal mechanisms for these smaller magnitude earthquakes (Mw < 5.5), with a current catalog of over 100 solutions from March 20, 2010 through mid September, 2010. This catalog contains a mix of interplate thrust and normal faulting focal mechanisms. Cross sections reveal that a majority of the earthquakes occur along the shallow dip of the subduction zone interface. As these events span the entire rupture zone, we will also examine these events for possible along-strike variations in source characteristics, such as stress drop, seismic moment and corner frequency. We model the P-wave spectra using a multitaper technique, then stack, and average the spectra as a function of event size

  16. Accurate Molecular Polarizabilities Based on Continuum Electrostatics

    PubMed Central

    Truchon, Jean-François; Nicholls, Anthony; Iftimie, Radu I.; Roux, Benoît; Bayly, Christopher I.

    2013-01-01

    A novel approach for representing the intramolecular polarizability as a continuum dielectric is introduced to account for molecular electronic polarization. It is shown, using a finite-difference solution to the Poisson equation, that the Electronic Polarization from Internal Continuum (EPIC) model yields accurate gas-phase molecular polarizability tensors for a test set of 98 challenging molecules composed of heteroaromatics, alkanes and diatomics. The electronic polarization originates from a high intramolecular dielectric that produces polarizabilities consistent with B3LYP/aug-cc-pVTZ and experimental values when surrounded by vacuum dielectric. In contrast to other approaches to model electronic polarization, this simple model avoids the polarizability catastrophe and accurately calculates molecular anisotropy with the use of very few fitted parameters and without resorting to auxiliary sites or anisotropic atomic centers. On average, the unsigned error in the average polarizability and anisotropy compared to B3LYP are 2% and 5%, respectively. The correlation between the polarizability components from B3LYP and this approach lead to a R2 of 0.990 and a slope of 0.999. Even the F2 anisotropy, shown to be a difficult case for existing polarizability models, can be reproduced within 2% error. In addition to providing new parameters for a rapid method directly applicable to the calculation of polarizabilities, this work extends the widely used Poisson equation to areas where accurate molecular polarizabilities matter. PMID:23646034

  17. Kinematic source parameter estimation for the 1995 Mw 7.2 Gulf of Aqaba Earthquake by using InSAR and teleseismic data in a Bayesian framework

    NASA Astrophysics Data System (ADS)

    Bathke, Hannes; Feng, Guangcai; Heimann, Sebastian; Nikkhoo, Mehdi; Zielke, Olaf; Jónsson, Sigurjon; Mai, Martin

    2016-04-01

    The 1995 Mw 7.2 Gulf of Aqaba earthquake was primarily a left-lateral strike-slip earthquake, occurring on the Dead Sea transform fault at the western border of the Arabian plate. The tectonic setting within the trans-tensional Gulf of Aqaba is complex, consisting of several en echelon transform faults and pull-apart basins. Several studies have been published, focusing on this earthquake using either InSAR or teleseismic (P and SH waves) data. However, the published finite-fault rupture models of the earthquake differ significantly. For example, it still remains unclear whether the Aqaba fault, the Aragonese fault or the Arnona fault ruptured in the event. It is also possible that several segments were activated. The main problem with past studies is that either InSAR or teleseismic data were used, but not both. Teleseismic data alone are unable to locate the event well, while the InSAR data are limited in the near field due to the earthquake's offshore location. In addition, the source fault is roughly north-south oriented and InSAR has limited sensitivity to north-south displacements. Here we improve on previous studies by using InSAR and teleseismic data jointly to constrain the source model. In addition, we use InSAR data from two additional tracks that have not been used before, which provides a more complete displacement field of the earthquake. Furthermore, in addition to the fault model parameters themselves, we also estimate the parameter uncertainties, which were not reported in previous studies. Based on these uncertainties we estimate a model-prediction covariance matrix in addition to the data covariance matrix that we then use in Bayesian inference sampling to solve for the static slip-distribution on the fault. By doing so, we avoid using a Laplacian smoothing operator, which is often subjective and may pose an unphysical constraint to the problem. Our results show that fault slip on only the Aragonese fault can satisfactorily explain the InSAR data

  18. Evaluation of the operating parameters of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) ionization source for elemental mass spectrometry.

    PubMed

    Zhang, Lynn X; Manard, Benjamin T; Konegger-Kappel, Stefanie; Kappel, Stefanie Konegger; Marcus, R Kenneth

    2014-11-01

    The liquid sampling-atmospheric pressure glow discharge (LS-APGD) has been assessed as an ionization source for elemental analysis with an interdependent, parametric evaluation regarding sheath/cooling gas flow rate, discharge current, liquid flow rate, and the distance between the plasma and the sampling cone of the mass spectrometer. In order to better understand plasma processes (and different from previous reports), no form of collision/reaction processing was performed to remove molecular interferents. The evaluation was performed employing five test elements: cesium, silver, lead, lanthanum and nickel (10(-4) mol L(-1) in 1 mol L(-1) HNO3). The intensity of the atomic ions, levels of spectral background, the signal-to-background ratios, and the atomic-to-oxide/hydroxide adduct ratios were monitored in order to obtain fundamental understanding with regards to not only how each parameter effects the performance of this LS-APGD source, but also the inter-parametric effects. The results indicate that the discharge current and the liquid sampling flow rates are the key aspects that control the spectral composition. A compromise set of operating conditions was determined: sheath gas flow rate = 0.9 L min(-1), discharge current = 10 mA, solution flow rate = 10 μL min(-1), and sampling distance = 1 cm. Limits of detection (LODs) were calculated using the SBR-RSDB (signal-to-background ratio/relative standard deviation of the background) approach under the optimized condition. The LODs for the test elementals ranged from 15 to 400 ng mL(-1) for 10 μL injections, with absolute mass values from 0.2 to 4 ng.

  19. Accurate estimation of sigma(exp 0) using AIRSAR data

    NASA Technical Reports Server (NTRS)

    Holecz, Francesco; Rignot, Eric

    1995-01-01

    During recent years signature analysis, classification, and modeling of Synthetic Aperture Radar (SAR) data as well as estimation of geophysical parameters from SAR data have received a great deal of interest. An important requirement for the quantitative use of SAR data is the accurate estimation of the backscattering coefficient sigma(exp 0). In terrain with relief variations radar signals are distorted due to the projection of the scene topography into the slant range-Doppler plane. The effect of these variations is to change the physical size of the scattering area, leading to errors in the radar backscatter values and incidence angle. For this reason the local incidence angle, derived from sensor position and Digital Elevation Model (DEM) data must always be considered. Especially in the airborne case, the antenna gain pattern can be an additional source of radiometric error, because the radar look angle is not known precisely as a result of the the aircraft motions and the local surface topography. Consequently, radiometric distortions due to the antenna gain pattern must also be corrected for each resolution cell, by taking into account aircraft displacements (position and attitude) and position of the backscatter element, defined by the DEM data. In this paper, a method to derive an accurate estimation of the backscattering coefficient using NASA/JPL AIRSAR data is presented. The results are evaluated in terms of geometric accuracy, radiometric variations of sigma(exp 0), and precision of the estimated forest biomass.

  20. Two highly accurate methods for pitch calibration

    NASA Astrophysics Data System (ADS)

    Kniel, K.; Härtig, F.; Osawa, S.; Sato, O.

    2009-11-01

    Among profiles, helix and tooth thickness pitch is one of the most important parameters of an involute gear measurement evaluation. In principle, coordinate measuring machines (CMM) and CNC-controlled gear measuring machines as a variant of a CMM are suited for these kinds of gear measurements. Now the Japan National Institute of Advanced Industrial Science and Technology (NMIJ/AIST) and the German national metrology institute the Physikalisch-Technische Bundesanstalt (PTB) have each developed independently highly accurate pitch calibration methods applicable to CMM or gear measuring machines. Both calibration methods are based on the so-called closure technique which allows the separation of the systematic errors of the measurement device and the errors of the gear. For the verification of both calibration methods, NMIJ/AIST and PTB performed measurements on a specially designed pitch artifact. The comparison of the results shows that both methods can be used for highly accurate calibrations of pitch standards.

  1. Source parameters of a M4.8 and its accompanying repeating earthquakes off Kamaishi, NE Japan: Implications for the hierarchical structure of asperities and earthquake cycle

    USGS Publications Warehouse

    Uchida, N.; Matsuzawa, T.; Ellsworth, W.L.; Imanishi, K.; Okada, T.; Hasegawa, A.

    2007-01-01

    We determine the source parameters of a M4.9 ?? 0.1 'characteristic earthquake' sequence and its accompanying microearthquakes at ???50 km depth on the subduction plate boundary offshore of Kamaishi, NE Japan. The microearthquakes tend to occur more frequently in the latter half of the recurrence intervals of the M4.9 ?? 0.1 events. Our results show that the microearthquakes are repeating events and they are located not only around but also within the slip area for the 2001 M4.8 event. From the hierarchical structure of slip areas and smaller stress drops for the microearthquakes compared to the M4.8 event, we infer the small repeating earthquakes rupture relatively weak patches in and around the slip area for the M4.8 event and their activity reflects a stress concentration process and/or change in frictional property (healing) at the area. We also infer the patches for the M4.9 ?? 0.1 and other repeating earthquakes undergo aseismic slip during their interseismic period. Copyright 2007 by the American Geophysical Union.

  2. Eruption Source Parameters for forecasting ash dispersion and deposition from vulcanian eruptions at Tungurahua volcano: Insights from field data from the July 2013 eruption

    NASA Astrophysics Data System (ADS)

    Parra, René; Bernard, Benjamin; Narváez, Diego; Le Pennec, Jean-Luc; Hasselle, Nathalie; Folch, Arnau

    2016-01-01

    Tungurahua volcano, located in the central area of the Ecuadorian Sierra, is erupting intermittently since 1999 alternating between periods of quiescence and explosive activity. Volcanic ash has been the most frequent and widespread hazard provoking air contamination episodes and impacts on human health, animals and crops in the surrounding area. After two months of quiescence, Tungurahua erupted violently on 14th July 2013 generating short-lived eruptive columns rising up to 9 km above the vent characterized as a vulcanian eruption. The resulting fallout deposits were sampled daily during and after the eruptions to determine grain size distributions and perform morphological and componentry analyses. Dispersion and sedimentation of ash were simulated numerically coupling the meteorological Weather Research Forecasting (WRF) with the volcanic ash dispersion FALL3D models. The combination of field and numerical studies allowed constraining the Eruption Source Parameters (ESP) for this event, which could be used to forecast ash dispersion and deposition from future vulcanian eruptions at Tungurahua. This set of pre-defined ESP was further validated using two different eruptions, as blind test, occurring on 16th December 2012 and 1st February 2014.

  3. A novel modelling framework to prioritize estimation of non-point source pollution parameters for quantifying pollutant origin and discharge in urban catchments.

    PubMed

    Fraga, I; Charters, F J; O'Sullivan, A D; Cochrane, T A

    2016-02-01

    Stormwater runoff in urban catchments contains heavy metals (zinc, copper, lead) and suspended solids (TSS) which can substantially degrade urban waterways. To identify these pollutant sources and quantify their loads the MEDUSA (Modelled Estimates of Discharges for Urban Stormwater Assessments) modelling framework was developed. The model quantifies pollutant build-up and wash-off from individual impervious roof, road and car park surfaces for individual rain events, incorporating differences in pollutant dynamics between surface types and rainfall characteristics. This requires delineating all impervious surfaces and their material types, the drainage network, rainfall characteristics and coefficients for the pollutant dynamics equations. An example application of the model to a small urban catchment demonstrates how the model can be used to identify the magnitude of pollutant loads, their spatial origin and the response of the catchment to changes in specific rainfall characteristics. A sensitivity analysis then identifies the key parameters influencing each pollutant load within the stormwater given the catchment characteristics, which allows development of a targeted calibration process that will enhance the certainty of the model outputs, while minimizing the data collection required for effective calibration. A detailed explanation of the modelling framework and pre-calibration sensitivity analysis is presented. PMID:26613353

  4. Source Estimation by Full Wave Form Inversion

    SciTech Connect

    Sjögreen, Björn; Petersson, N. Anders

    2013-08-07

    Given time-dependent ground motion recordings at a number of receiver stations, we solve the inverse problem for estimating the parameters of the seismic source. The source is modeled as a point moment tensor source, characterized by its location, moment tensor components, the start time, and frequency parameter (rise time) of its source time function. In total, there are 11 unknown parameters. We use a non-linear conjugate gradient algorithm to minimize the full waveform misfit between observed and computed ground motions at the receiver stations. An important underlying assumption of the minimization problem is that the wave propagation is accurately described by the elastic wave equation in a heterogeneous isotropic material. We use a fourth order accurate finite difference method, developed in [12], to evolve the waves forwards in time. The adjoint wave equation corresponding to the discretized elastic wave equation is used to compute the gradient of the misfit, which is needed by the non-linear conjugated minimization algorithm. A new source point moment source discretization is derived that guarantees that the Hessian of the misfit is a continuous function of the source location. An efficient approach for calculating the Hessian is also presented. We show how the Hessian can be used to scale the problem to improve the convergence of the non-linear conjugated gradient algorithm. Numerical experiments are presented for estimating the source parameters from synthetic data in a layer over half-space problem (LOH.1), illustrating rapid convergence of the proposed approach.

  5. Geoacoustic and source tracking using particle filtering: experimental results.

    PubMed

    Yardim, Caglar; Gerstoft, Peter; Hodgkiss, William S

    2010-07-01

    A particle filtering (PF) approach is presented for performing sequential geoacoustic inversion of a complex ocean acoustic environment using a moving acoustic source. This approach treats both the environmental parameters [e.g., water column sound speed profile (SSP), water depth, sediment and bottom parameters] at the source location and the source parameters (e.g., source depth, range and speed) as unknown random variables that evolve as the source moves. This allows real-time updating of the environment and accurate tracking of the moving source. As a sequential Monte Carlo technique that operates on nonlinear systems with non-Gaussian probability densities, the PF is an ideal algorithm to perform tracking of environmental and source parameters, and their uncertainties via the evolving posterior probability densities. The approach is demonstrated on both simulated data in a shallow water environment with a sloping bottom and experimental data collected during the SWellEx-96 experiment.

  6. The Mw 5.8 Mineral, Virginia, earthquake of August 2011 and aftershock sequence: constraints on earthquake source parameters and fault geometry

    USGS Publications Warehouse

    McNamara, Daniel E.; Benz, H.M.; Herrmann, Robert B.; Bergman, Eric A.; Earle, Paul; Meltzer, Anne; Withers, Mitch; Chapman, Martin

    2014-01-01

    The Mw 5.8 earthquake of 23 August 2011 (17:51:04 UTC) (moment, M0 5.7×1017  N·m) occurred near Mineral, Virginia, within the central Virginia seismic zone and was felt by more people than any other earthquake in United States history. The U.S. Geological Survey (USGS) received 148,638 felt reports from 31 states and 4 Canadian provinces. The USGS PAGER system estimates as many as 120,000 people were exposed to shaking intensity levels of IV and greater, with approximately 10,000 exposed to shaking as high as intensity VIII. Both regional and teleseismic moment tensor solutions characterize the earthquake as a northeast‐striking reverse fault that nucleated at a depth of approximately 7±2  km. The distribution of reported macroseismic intensities is roughly ten times the area of a similarly sized earthquake in the western United States (Horton and Williams, 2012). Near‐source and far‐field damage reports, which extend as far away as Washington, D.C., (135 km away) and Baltimore, Maryland, (200 km away) are consistent with an earthquake of this size and depth in the eastern United States (EUS). Within the first few days following the earthquake, several government and academic institutions installed 36 portable seismograph stations in the epicentral region, making this among the best‐recorded aftershock sequences in the EUS. Based on modeling of these data, we provide a detailed description of the source parameters of the mainshock and analysis of the subsequent aftershock sequence for defining the fault geometry, area of rupture, and observations of the aftershock sequence magnitude–frequency and temporal distribution. The observed slope of the magnitude–frequency curve or b‐value for the aftershock sequence is consistent with previous EUS studies (b=0.75), suggesting that most of the accumulated strain was released by the mainshock. The aftershocks define a rupture that extends between approximately 2–8 km in depth and 8–10 km along

  7. Distance scaling method for accurate prediction of slowly varying magnetic fields in satellite missions

    NASA Astrophysics Data System (ADS)

    Zacharias, Panagiotis P.; Chatzineofytou, Elpida G.; Spantideas, Sotirios T.; Capsalis, Christos N.

    2016-07-01

    In the present work, the determination of the magnetic behavior of localized magnetic sources from near-field measurements is examined. The distance power law of the magnetic field fall-off is used in various cases to accurately predict the magnetic signature of an equipment under test (EUT) consisting of multiple alternating current (AC) magnetic sources. Therefore, parameters concerning the location of the observation points (magnetometers) are studied towards this scope. The results clearly show that these parameters are independent of the EUT's size and layout. Additionally, the techniques developed in the present study enable the placing of the magnetometers close to the EUT, thus achieving high signal-to-noise ratio (SNR). Finally, the proposed method is verified by real measurements, using a mobile phone as an EUT.

  8. SU-D-19A-05: The Dosimetric Impact of Using Xoft Axxent® Electronic Brachytherapy Source TG-43 Dosimetry Parameters for Treatment with the Xoft 30 Mm Diameter Vaginal Applicator

    SciTech Connect

    Simiele, S; Micka, J; Culberson, W; DeWerd, L

    2014-06-01

    Purpose: A full TG-43 dosimetric characterization has not been performed for the Xoft Axxent ® electronic brachytherapy source (Xoft, a subsidiary of iCAD, San Jose, CA) within the Xoft 30 mm diameter vaginal applicator. Currently, dose calculations are performed using the bare-source TG-43 parameters and do not account for the presence of the applicator. This work focuses on determining the difference between the bare-source and sourcein- applicator TG-43 parameters. Both the radial dose function (RDF) and polar anisotropy function (PAF) were computationally determined for the source-in-applicator and bare-source models to determine the impact of using the bare-source dosimetry data. Methods: MCNP5 was used to model the source and the Xoft 30 mm diameter vaginal applicator. All simulations were performed using 0.84p and 0.03e cross section libraries. All models were developed based on specifications provided by Xoft. The applicator is made of a proprietary polymer material and simulations were performed using the most conservative chemical composition. An F6 collision-kerma tally was used to determine the RDF and PAF values in water at various dwell positions. The RDF values were normalized to 2.0 cm from the source to accommodate the applicator radius. Source-in-applicator results were compared with bare-source results from this work as well as published baresource results. Results: For a 0 mm source pullback distance, the updated bare-source model and source-in-applicator RDF values differ by 2% at 3 cm and 4% at 5 cm. The largest PAF disagreements were observed at the distal end of the source and applicator with up to 17% disagreement at 2 cm and 8% at 8 cm. The bare-source model had RDF values within 2.6% of the published TG-43 data and PAF results within 7.2% at 2 cm. Conclusion: Results indicate that notable differences exist between the bare-source and source-in-applicator TG-43 simulated parameters. Xoft Inc. provided partial funding for this work.

  9. TRIPPy: Python-based Trailed Source Photometry

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  10. Assessment of upper tropospheric HOx sources over the tropical Pacific based on NASA GTE/PEM data: Net effect on HOx and other photochemical parameters

    NASA Astrophysics Data System (ADS)

    Crawford, J.; Davis, D.; Olson, J.; Chen, G.; Liu, S.; Gregory, G.; Barrick, J.; Sachse, G.; Sandholm, S.; Heikes, B.; Singh, H.; Blake, D.

    1999-07-01

    Data for the tropical upper troposphere (8-12 km, 20°N-20°S) collected during NASA's Pacific Exploratory Missions have been used to carry out a detailed examination of the photochemical processes controlling HOx (OH+HO2). Of particular significance is the availability of measurements of nonmethane hydrocarbons, oxygenated hydrocarbons (i.e., acetone, methanol, and ethanol) and peroxides (i.e., H2O2 and CH3OOH). These observations have provided constraints on model calculations permitting an assessment of the potential impact of these species on the levels of HOx, CH3O2, CH2O, as well as ozone budget parameters. Sensitivity calculations using a time-dependent photochemical box model show that when constrained by measured values of the above oxygenated species, model estimated HOx levels are elevated relative to unconstrained calculations. The impact of constraining these species was found to increase with altitude, reflecting the systematic roll-off in water vapor mixing ratios with altitude. At 11-12 km, overall increases in HOx approached a factor of 2 with somewhat larger increases being found for gross and net photochemical production of ozone. While significant, the impact on HOx due to peroxides appears to be less than previously estimated. In particular, observations of elevated H2O2 levels may be more influenced by local photochemistry than by convective transport. Issues related to the uncertainty in high-altitude water vapor levels and the possibility of other contributing sources of HOx are discussed. Finally, it is noted that the uncertainties in gas kinetic rate coefficients at the low temperatures of the upper troposphere and as well as OH sensor calibrations should be areas of continued investigation.

  11. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models. PMID:27111139

  12. Accurate phase-shift velocimetry in rock

    NASA Astrophysics Data System (ADS)

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R.; Holmes, William M.

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  13. Accurate phase-shift velocimetry in rock.

    PubMed

    Shukla, Matsyendra Nath; Vallatos, Antoine; Phoenix, Vernon R; Holmes, William M

    2016-06-01

    Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.

  14. Profitable capitation requires accurate costing.

    PubMed

    West, D A; Hicks, L L; Balas, E A; West, T D

    1996-01-01

    In the name of costing accuracy, nurses are asked to track inventory use on per treatment basis when more significant costs, such as general overhead and nursing salaries, are usually allocated to patients or treatments on an average cost basis. Accurate treatment costing and financial viability require analysis of all resources actually consumed in treatment delivery, including nursing services and inventory. More precise costing information enables more profitable decisions as is demonstrated by comparing the ratio-of-cost-to-treatment method (aggregate costing) with alternative activity-based costing methods (ABC). Nurses must participate in this costing process to assure that capitation bids are based upon accurate costs rather than simple averages. PMID:8788799

  15. Accurate identification and compensation of geometric errors of 5-axis CNC machine tools using double ball bar

    NASA Astrophysics Data System (ADS)

    Lasemi, Ali; Xue, Deyi; Gu, Peihua

    2016-05-01

    Five-axis CNC machine tools are widely used in manufacturing of parts with free-form surfaces. Geometric errors of machine tools have significant effects on the quality of manufactured parts. This research focuses on development of a new method to accurately identify geometric errors of 5-axis CNC machines, especially the errors due to rotary axes, using the magnetic double ball bar. A theoretical model for identification of geometric errors is provided. In this model, both position-independent errors and position-dependent errors are considered as the error sources. This model is simplified by identification and removal of the correlated and insignificant error sources of the machine. Insignificant error sources are identified using the sensitivity analysis technique. Simulation results reveal that the simplified error identification model can result in more accurate estimations of the error parameters. Experiments on a 5-axis CNC machine tool also demonstrate significant reduction in the volumetric error after error compensation.

  16. PERSONALISED BODY COUNTER CALIBRATION USING ANTHROPOMETRIC PARAMETERS.

    PubMed

    Pölz, S; Breustedt, B

    2016-09-01

    Current calibration methods for body counting offer personalisation for lung counting predominantly with respect to ratios of body mass and height. Chest wall thickness is used as an intermediate parameter. This work revises and extends these methods using a series of computational phantoms derived from medical imaging data in combination with radiation transport simulation and statistical analysis. As an example, the method is applied to the calibration of the In Vivo Measurement Laboratory (IVM) at Karlsruhe Institute of Technology (KIT) comprising four high-purity germanium detectors in two partial body measurement set-ups. The Monte Carlo N-Particle (MCNP) transport code and the Extended Cardiac-Torso (XCAT) phantom series have been used. Analysis of the computed sample data consisting of 18 anthropometric parameters and calibration factors generated from 26 photon sources for each of the 30 phantoms reveals the significance of those parameters required for producing an accurate estimate of the calibration function. Body circumferences related to the source location perform best in the example, while parameters related to body mass show comparable but lower performances, and those related to body height and other lengths exhibit low performances. In conclusion, it is possible to give more accurate estimates of calibration factors using this proposed approach including estimates of uncertainties related to interindividual anatomical variation of the target population. PMID:26396263

  17. Dose characterization in the near-source region for two high dose rate brachytherapy sources.

    PubMed

    Wang, Ruqing; Li, X Allen

    2002-08-01

    High dose rate (HDR) 192Ir sources are currently used in intravascular brachytherapy (IVB) for the peripheral arterial system. This poses a demand on evaluating accurate dose parameters in the near-source region for such sources. The purpose of this work is to calculate the dose parameters for the old VariSource HDR 192Ir source and the new microSelectron HDR 192Ir source, using Monte Carlo electron and photon transport simulation. The two-dimensional (2D) dose rate distributions and the air kerma strengths for the two HDR sources were calculated by EGSnrc and EGS4 Monte Carlo codes. Based on these data, the dose parameters proposed in the AAPM TG-60 protocol were derived. The dose rate constants obtained are 13.119+/-0.028 cGy h(-1) U(-1) for the old VariSource source, and 22.751+/-0.031 cGy h(-1) U(-1) for the new microSelectron source at the reference point (r0 = 2 mm, theta = pi/2). The 2D dose rate distributions, the radial dose functions, and the anisotropy functions presented for the two sources cover radial distances ranging from 0.5 to 10 mm. In the near-source region on the transverse plane, the dose effects of the charged particle nonequilibrium and the beta-particle dose contribution were studied. It is found that at radial distances ranging from 0.5 to 2 mm, these effects increase the calculated dose rates by up to 29% for the old VariSource source, and by up to 12% for the new microSelectron source, which, in turn, change values of the radial dose function and the anisotropy function. The present dose parameters, which account for the charged particle nonequilibrium and the beta particle contribution, may be used for accurate IVB dose calculation. PMID:12201413

  18. Accurately Mapping M31's Microlensing Population

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2004-07-01

    We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity

  19. Effects of Dietary Lipid Source and Level on Growth Performance, Blood Parameters and Flesh Quality of Sub-adult Olive Flounder (Paralichthys olivaceus)

    PubMed Central

    Kim, Dong-Kyu; Kim, Kyoung-Duck; Seo, Joo-Young; Lee, Sang-Min

    2012-01-01

    This study was conducted to investigate the effects of dietary lipid source and level on growth performance, blood parameters, fatty acid composition and flesh quality of sub-adult olive flounder Paralichthys olivaceus. Eight experimental diets were formulated to contain 5% squid liver oil (SLO), 5% linseed oil (LO), 5% soybean oil (SO), a mixture of 1% squid liver oil, 2% linseed oil and 2% soybean oil (MIX), no lipid supplementation with high protein level (LL-HP), 10% squid liver oil (HL-SLO), a mixture of 1% squid liver oil, 4.5% linseed oil and 4.5% soybean oil (HL-VO), and 1% squid liver oil with high starch level (LL-HC), respectively. Two replicate groups of fish (average initial weight of 296 g) were fed the diets for 17 wks. After 5 wks, 11 wks and the end of the feeding trial, five fish from each tank were randomly sampled for analysis of body composition. At the end of the feeding trial, final mean weight of fish fed the LL-HP diet was significantly (p<0.05) higher than that of fish fed the HL-VO diet, but did not differ significantly from those of fish fed the SLO, LO, SO, MIX, HL-SLO and LL-HC diets. Fish fed the LL-HP diet showed significantly higher feed efficiency than fish fed the LO, HL-SLO and HL-VO diets. Feed efficiency of fish fed the LO, SO and MIX diets were similar to those of fish fed the SLO and HL-SLO diets. Fish fed the HL-SLO diet showed significantly higher total cholesterol content in plasma compared with other diets. Fatty acid composition of tissues was reflected by dietary fatty acid composition. The highest linoleic (LA) and linolenic acid (LNA) contents in the dorsal muscle were observed in fish fed the SO and LO diets, respectively, regardless of feeding period. The highest eicosapentaenoic acid (EPA) content in the dorsal muscle was observed in fish fed the LL-HP and LL-HC diets after 11 and 17 weeks of feeding, respectively. Fish fed the SLO and HL-SLO diets showed higher docosahexaenoic acid (DHA) content than that of other

  20. Accurate documentation and wound measurement.

    PubMed

    Hampton, Sylvie

    This article, part 4 in a series on wound management, addresses the sometimes routine yet crucial task of documentation. Clear and accurate records of a wound enable its progress to be determined so the appropriate treatment can be applied. Thorough records mean any practitioner picking up a patient's notes will know when the wound was last checked, how it looked and what dressing and/or treatment was applied, ensuring continuity of care. Documenting every assessment also has legal implications, demonstrating due consideration and care of the patient and the rationale for any treatment carried out. Part 5 in the series discusses wound dressing characteristics and selection.

  1. SIMBA survey of southern high-mass star forming regions. I. Physical parameters of the 1.2 mm/IRAS sources

    NASA Astrophysics Data System (ADS)

    Faúndez, S.; Bronfman, L.; Garay, G.; Chini, R.; Nyman, L.-Å.; May, J.

    2004-10-01

    We report the results of a 1.2 mm continuum emission survey toward 146 IRAS sources thought to harbour high-mass star forming regions. The sources have FIR colors typical of UCHII regions and were detected in the CS(2->1) line survey of Bronfman et al. (\\cite{bnm}). Regions of 15 arcmin × 10 arcmin, centered on each IRAS source, were mapped with an angular resolution of ˜24 arcsec, using the SIMBA array on the SEST telescope. 1.2 mm emission was detected toward all IRAS sources. We find that the dust cores associated with these sources have typical sizes of 0.4 pc and masses of 5× 103 M⊙. Dust temperatures and luminosities, derived from the SED, are typically 32 K and 2.3 × 105 L⊙. Table 1 and Figs. 6 to 23 are only available in electronic form at http://www.edpsciences.org

  2. Monte Carlo modeling provides accurate calibration factors for radionuclide activity meters.

    PubMed

    Zagni, F; Cicoria, G; Lucconi, G; Infantino, A; Lodi, F; Marengo, M

    2014-12-01

    Accurate determination of calibration factors for radionuclide activity meters is crucial for quantitative studies and in the optimization step of radiation protection, as these detectors are widespread in radiopharmacy and nuclear medicine facilities. In this work we developed the Monte Carlo model of a widely used activity meter, using the Geant4 simulation toolkit. More precisely the "PENELOPE" EM physics models were employed. The model was validated by means of several certified sources, traceable to primary activity standards, and other sources locally standardized with spectrometry measurements, plus other experimental tests. Great care was taken in order to accurately reproduce the geometrical details of the gas chamber and the activity sources, each of which is different in shape and enclosed in a unique container. Both relative calibration factors and ionization current obtained with simulations were compared against experimental measurements; further tests were carried out, such as the comparison of the relative response of the chamber for a source placed at different positions. The results showed a satisfactory level of accuracy in the energy range of interest, with the discrepancies lower than 4% for all the tested parameters. This shows that an accurate Monte Carlo modeling of this type of detector is feasible using the low-energy physics models embedded in Geant4. The obtained Monte Carlo model establishes a powerful tool for first instance determination of new calibration factors for non-standard radionuclides, for custom containers, when a reference source is not available. Moreover, the model provides an experimental setup for further research and optimization with regards to materials and geometrical details of the measuring setup, such as the ionization chamber itself or the containers configuration.

  3. Real-time monitoring and massive inversion of source parameters of very long period seismic signals: An application to Stromboli Volcano, Italy

    USGS Publications Warehouse

    Auger, E.; D'Auria, L.; Martini, M.; Chouet, B.; Dawson, P.

    2006-01-01

    We present a comprehensive processing tool for the real-time analysis of the source mechanism of very long period (VLP) seismic data based on waveform inversions performed in the frequency domain for a point source. A search for the source providing the best-fitting solution is conducted over a three-dimensional grid of assumed source locations, in which the Green's functions associated with each point source are calculated by finite differences using the reciprocal relation between source and receiver. Tests performed on 62 nodes of a Linux cluster indicate that the waveform inversion and search for the best-fitting signal over 100,000 point sources require roughly 30 s of processing time for a 2-min-long record. The procedure is applied to post-processing of a data archive and to continuous automatic inversion of real-time data at Stromboli, providing insights into different modes of degassing at this volcano. Copyright 2006 by the American Geophysical Union.

  4. Toward Accurate and Quantitative Comparative Metagenomics.

    PubMed

    Nayfach, Stephen; Pollard, Katherine S

    2016-08-25

    Shotgun metagenomics and computational analysis are used to compare the taxonomic and functional profiles of microbial communities. Leveraging this approach to understand roles of microbes in human biology and other environments requires quantitative data summaries whose values are comparable across samples and studies. Comparability is currently hampered by the use of abundance statistics that do not estimate a meaningful parameter of the microbial community and biases introduced by experimental protocols and data-cleaning approaches. Addressing these challenges, along with improving study design, data access, metadata standardization, and analysis tools, will enable accurate comparative metagenomics. We envision a future in which microbiome studies are replicable and new metagenomes are easily and rapidly integrated with existing data. Only then can the potential of metagenomics for predictive ecological modeling, well-powered association studies, and effective microbiome medicine be fully realized. PMID:27565341

  5. Toward Accurate and Quantitative Comparative Metagenomics

    PubMed Central

    Nayfach, Stephen; Pollard, Katherine S.

    2016-01-01

    Shotgun metagenomics and computational analysis are used to compare the taxonomic and functional profiles of microbial communities. Leveraging this approach to understand roles of microbes in human biology and other environments requires quantitative data summaries whose values are comparable across samples and studies. Comparability is currently hampered by the use of abundance statistics that do not estimate a meaningful parameter of the microbial community and biases introduced by experimental protocols and data-cleaning approaches. Addressing these challenges, along with improving study design, data access, metadata standardization, and analysis tools, will enable accurate comparative metagenomics. We envision a future in which microbiome studies are replicable and new metagenomes are easily and rapidly integrated with existing data. Only then can the potential of metagenomics for predictive ecological modeling, well-powered association studies, and effective microbiome medicine be fully realized. PMID:27565341

  6. How Accurately can we Calculate Thermal Systems?

    SciTech Connect

    Cullen, D; Blomquist, R N; Dean, C; Heinrichs, D; Kalugin, M A; Lee, M; Lee, Y; MacFarlan, R; Nagaya, Y; Trkov, A

    2004-04-20

    I would like to determine how accurately a variety of neutron transport code packages (code and cross section libraries) can calculate simple integral parameters, such as K{sub eff}, for systems that are sensitive to thermal neutron scattering. Since we will only consider theoretical systems, we cannot really determine absolute accuracy compared to any real system. Therefore rather than accuracy, it would be more precise to say that I would like to determine the spread in answers that we obtain from a variety of code packages. This spread should serve as an excellent indicator of how accurately we can really model and calculate such systems today. Hopefully, eventually this will lead to improvements in both our codes and the thermal scattering models that they use in the future. In order to accomplish this I propose a number of extremely simple systems that involve thermal neutron scattering that can be easily modeled and calculated by a variety of neutron transport codes. These are theoretical systems designed to emphasize the effects of thermal scattering, since that is what we are interested in studying. I have attempted to keep these systems very simple, and yet at the same time they include most, if not all, of the important thermal scattering effects encountered in a large, water-moderated, uranium fueled thermal system, i.e., our typical thermal reactors.

  7. SPLASH: Accurate OH maser positions

    NASA Astrophysics Data System (ADS)

    Walsh, Andrew; Gomez, Jose F.; Jones, Paul; Cunningham, Maria; Green, James; Dawson, Joanne; Ellingsen, Simon; Breen, Shari; Imai, Hiroshi; Lowe, Vicki; Jones, Courtney

    2013-10-01

    The hydroxyl (OH) 18 cm lines are powerful and versatile probes of diffuse molecular gas, that may trace a largely unstudied component of the Galactic ISM. SPLASH (the Southern Parkes Large Area Survey in Hydroxyl) is a large, unbiased and fully-sampled survey of OH emission, absorption and masers in the Galactic Plane that will achieve sensitivities an order of magnitude better than previous work. In this proposal, we request ATCA time to follow up OH maser candidates. This will give us accurate (~10") positions of the masers, which can be compared to other maser positions from HOPS, MMB and MALT-45 and will provide full polarisation measurements towards a sample of OH masers that have not been observed in MAGMO.

  8. The source parameters, surface deformation and tectonic setting of three recent earthquakes: thessalonki (Greece), tabas-e-golshan (iran) and carlisle (u.k.).

    PubMed

    King, G; Soufleris, C; Berberian, M

    1981-03-01

    Abstract- Three earthquakes have been studied. These are the Thessaloniki earthquake of 20th June 1978 (Ms = 6.4, Normal faulting), the Tabase-Golshan earthquake of 16th September 1978 (Ms = 7.7 Thrust faulting) and the Carlisle earth-quake of 26th December 1979 (Mb = 5.0, Thrust faulting). The techniques employed to determine source parameters included field studies of SUP face deformation, fault breaks, locations of locally recorded aftershocks and teleseismic studies including joint hypocentral location, first motion methods and waveform modelling. It is clear that these techniques applied together provide more information than the same methods used separately. The moment of the Thessaloniki earthquake determined teleseismically (Force moment 5.2 times 10(25) dyne cm. Geometric moment 1.72 times 10(8) m(3) ) is an order of magnitude greater than that determined using field data (surface ruptures and aftershock depths) (Force moment 4.5 times 10(24) dyne cm. Geometric moment 0.16 times 10(8) m(3) ). It is concluded that for this earthquake the surface rupture only partly reflects the processes on the main rupture plane. This view i s supported by a distribution of aftershocks and damage which extends well outside the region of ground rupture. However, the surface breaks consistently have the same slip vector direction as the fault plane solutions suggesting that they are in this respect related to to the main faulting and are not superficial slumping. Both field studies and waveform studies suggest a low stress drop which may explain the relatively little damage and loss of life as a result of the Thessaloniki earthquake. In contrast, the teleseismic moment of the Tabas-e-Golshan earthquake (Force moment 4.4 times 10(26) dyne cm. Geometric moment 1.5 times 10(9) m(3) ) is similar t o that determined from field studies (Force moment 10.2 times 10(26) dyne cm. Geometric moment 3.4 times 10(9) m(3) ) and the damage and after-shock distributions clearly relate to the

  9. The source parameters, surface deformation and tectonic setting of three recent earthquakes: thessalonki (Greece), tabas-e-golshan (iran) and carlisle (u.k.).

    PubMed

    King, G; Soufleris, C; Berberian, M

    1981-03-01

    Abstract- Three earthquakes have been studied. These are the Thessaloniki earthquake of 20th June 1978 (Ms = 6.4, Normal faulting), the Tabase-Golshan earthquake of 16th September 1978 (Ms = 7.7 Thrust faulting) and the Carlisle earth-quake of 26th December 1979 (Mb = 5.0, Thrust faulting). The techniques employed to determine source parameters included field studies of SUP face deformation, fault breaks, locations of locally recorded aftershocks and teleseismic studies including joint hypocentral location, first motion methods and waveform modelling. It is clear that these techniques applied together provide more information than the same methods used separately. The moment of the Thessaloniki earthquake determined teleseismically (Force moment 5.2 times 10(25) dyne cm. Geometric moment 1.72 times 10(8) m(3) ) is an order of magnitude greater than that determined using field data (surface ruptures and aftershock depths) (Force moment 4.5 times 10(24) dyne cm. Geometric moment 0.16 times 10(8) m(3) ). It is concluded that for this earthquake the surface rupture only partly reflects the processes on the main rupture plane. This view i s supported by a distribution of aftershocks and damage which extends well outside the region of ground rupture. However, the surface breaks consistently have the same slip vector direction as the fault plane solutions suggesting that they are in this respect related to to the main faulting and are not superficial slumping. Both field studies and waveform studies suggest a low stress drop which may explain the relatively little damage and loss of life as a result of the Thessaloniki earthquake. In contrast, the teleseismic moment of the Tabas-e-Golshan earthquake (Force moment 4.4 times 10(26) dyne cm. Geometric moment 1.5 times 10(9) m(3) ) is similar t o that determined from field studies (Force moment 10.2 times 10(26) dyne cm. Geometric moment 3.4 times 10(9) m(3) ) and the damage and after-shock distributions clearly relate to the

  10. Accurate thickness measurement of graphene

    NASA Astrophysics Data System (ADS)

    Shearer, Cameron J.; Slattery, Ashley D.; Stapleton, Andrew J.; Shapter, Joseph G.; Gibson, Christopher T.

    2016-03-01

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  11. Accurate thickness measurement of graphene.

    PubMed

    Shearer, Cameron J; Slattery, Ashley D; Stapleton, Andrew J; Shapter, Joseph G; Gibson, Christopher T

    2016-03-29

    Graphene has emerged as a material with a vast variety of applications. The electronic, optical and mechanical properties of graphene are strongly influenced by the number of layers present in a sample. As a result, the dimensional characterization of graphene films is crucial, especially with the continued development of new synthesis methods and applications. A number of techniques exist to determine the thickness of graphene films including optical contrast, Raman scattering and scanning probe microscopy techniques. Atomic force microscopy (AFM), in particular, is used extensively since it provides three-dimensional images that enable the measurement of the lateral dimensions of graphene films as well as the thickness, and by extension the number of layers present. However, in the literature AFM has proven to be inaccurate with a wide range of measured values for single layer graphene thickness reported (between 0.4 and 1.7 nm). This discrepancy has been attributed to tip-surface interactions, image feedback settings and surface chemistry. In this work, we use standard and carbon nanotube modified AFM probes and a relatively new AFM imaging mode known as PeakForce tapping mode to establish a protocol that will allow users to accurately determine the thickness of graphene films. In particular, the error in measuring the first layer is reduced from 0.1-1.3 nm to 0.1-0.3 nm. Furthermore, in the process we establish that the graphene-substrate adsorbate layer and imaging force, in particular the pressure the tip exerts on the surface, are crucial components in the accurate measurement of graphene using AFM. These findings can be applied to other 2D materials.

  12. A Flexible Fringe Projection Vision System with Extended Mathematical Model for Accurate Three-Dimensional Measurement

    PubMed Central

    Xiao, Suzhi; Tao, Wei; Zhao, Hui

    2016-01-01

    In order to acquire an accurate three-dimensional (3D) measurement, the traditional fringe projection technique applies complex and laborious procedures to compensate for the errors that exist in the vision system. However, the error sources in the vision system are very complex, such as lens distortion, lens defocus, and fringe pattern nonsinusoidality. Some errors cannot even be explained or rendered with clear expressions and are difficult to compensate directly as a result. In this paper, an approach is proposed that avoids the complex and laborious compensation procedure for error sources but still promises accurate 3D measurement. It is realized by the mathematical model extension technique. The parameters of the extended mathematical model for the ’phase to 3D coordinates transformation’ are derived using the least-squares parameter estimation algorithm. In addition, a phase-coding method based on a frequency analysis is proposed for the absolute phase map retrieval to spatially isolated objects. The results demonstrate the validity and the accuracy of the proposed flexible fringe projection vision system on spatially continuous and discontinuous objects for 3D measurement. PMID:27136553

  13. A Flexible Fringe Projection Vision System with Extended Mathematical Model for Accurate Three-Dimensional Measurement.

    PubMed

    Xiao, Suzhi; Tao, Wei; Zhao, Hui

    2016-01-01

    In order to acquire an accurate three-dimensional (3D) measurement, the traditional fringe projection technique applies complex and laborious procedures to compensate for the errors that exist in the vision system. However, the error sources in the vision system are very complex, such as lens distortion, lens defocus, and fringe pattern nonsinusoidality. Some errors cannot even be explained or rendered with clear expressions and are difficult to compensate directly as a result. In this paper, an approach is proposed that avoids the complex and laborious compensation procedure for error sources but still promises accurate 3D measurement. It is realized by the mathematical model extension technique. The parameters of the extended mathematical model for the 'phase to 3D coordinates transformation' are derived using the least-squares parameter estimation algorithm. In addition, a phase-coding method based on a frequency analysis is proposed for the absolute phase map retrieval to spatially isolated objects. The results demonstrate the validity and the accuracy of the proposed flexible fringe projection vision system on spatially continuous and discontinuous objects for 3D measurement. PMID:27136553

  14. Calibrating X-ray Imaging Devices for Accurate Intensity Measurement

    SciTech Connect

    Haugh, M. J.

    2011-07-28

    The purpose of the project presented is to develop methods to accurately calibrate X-ray imaging devices. The approach was to develop X-ray source systems suitable for this endeavor and to develop methods to calibrate solid state detectors to measure source intensity. NSTec X-ray sources used for the absolute calibration of cameras are described, as well as the method of calibrating the source by calibrating the detectors. The work resulted in calibration measurements for several types of X-ray cameras. X-ray camera calibration measured efficiency and efficiency variation over the CCD. Camera types calibrated include: CCD, CID, back thinned (back illuminated), front illuminated.

  15. Quantitative Microbial Risk Assessment Tutorial – SDMProjectBuilder: Import Local Data Files to Identify and Modify Contamination Sources and Input Parameters

    EPA Science Inventory

    Twelve example local data support files are automatically downloaded when the SDMProjectBuilder is installed on a computer. They allow the user to modify values to parameters that impact the release, migration, fate, and transport of microbes within a watershed, and control delin...

  16. Combination of magnetic parameters and heavy metals to discriminate soil-contamination sources in Yinchuan--a typical oasis city of Northwestern China.

    PubMed

    Xia, Dunsheng; Wang, Bo; Yu, Ye; Jia, Jia; Nie, Yan; Wang, Xin; Xu, Shujing

    2014-07-01

    Various industrial processes and vehicular traffic result in harmful emissions containing both magnetic minerals and heavy metals. In this study, we investigated the levels of magnetic and heavy metal contamination of topsoils from Yinchuan city in northwestern China. The results demonstrate that magnetic mineral assemblages in the topsoil are dominated by pseudo-single domain (PSD) and multi-domain (MD) magnetite. The concentrations of anthropogenic heavy metals (Cr, Cu, Pb and Zn) and the magnetic properties of χlf, SIRM, χARM, and 'SOFT' and 'HARD' remanence are significantly correlated, suggesting that the magnetic minerals and heavy metals have common sources. Combined use of principal components and fuzzy cluster analysis of the magnetic and chemical data set indicates that the magnetic and geochemical properties of the particulates emitted from different sources vary significantly. Samples from university campus and residential areas are mainly affected by crustal material, with low concentrations of magnetic minerals and heavy metals, while industrial pollution sources are characterized by high concentrations of coarse magnetite and Cr, Cu, Pb and Zn. Traffic pollution is characterized by Pb and Zn, and magnetite. Magnetic measurements of soils are capable of differentiating sources of magnetic minerals and heavy metals from industrial processes, vehicle fleets and soil parent material.

  17. Source parameters of the 2013, Ms 7.0, Lushan earthquake and the characteristics of the near-fault strong ground motion

    NASA Astrophysics Data System (ADS)

    Zhao, Fengfan; Meng, Lingyuan

    2016-04-01

    The April 20, 2013 Ms 7.0, earthquake in Lushan city, Sichuan province of China occurred as the result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on the Southern part of Longmenshan fault at a depth of 13km. The maximum intensity is up to VIII to IX at Boxing and Lushan city, which are located in the meizoseismal area. In this study, we analyzed the dynamic source process with the source mechanism and empirical relationships, estimated the strong ground motion in the near-fault field based on the Brune's circle model. A dynamical composite source model (DCSM) has been developed to simulate the near-fault strong ground motion with associated fault rupture properties at Boxing and Lushan city, respectively. The results indicate that the frictional undershoot behavior in the dynamic source process of Lushan earthquake, which is actually different from the overshoot activity of the Wenchuan earthquake. Moreover, we discussed the characteristics of the strong ground motion in the near-fault field, that the broadband synthetic seismogram ground motion predictions for Boxing and Lushan city produced larger peak values, shorter durations and higher frequency contents. It indicates that the factors in near-fault strong ground motion was under the influence of higher effect stress drop and asperity slip distributions on the fault plane. This work is financially supported by the Natural Science Foundation of China (Grant No. 41404045) and by Science for Earthquake Resilience of CEA (XH14055Y).

  18. Design parameters for a 7.2 tesla bending magnet for a 1.5 GeV compact light source

    SciTech Connect

    Green, M.A.; Madura, D.

    1995-06-01

    This report describes the design for a 7.2 tesla superconducting dipole magnet for a compact synchrotron light source. The proposed magnet is a Vobly type modified picture frame dipole that has the flux returned through unsaturated iron. In this magnet, The iron in the pole pieces is highly saturated, Separately powered coils around the pole pieces are used to direct the flux lines until the flux can be returned through the unsaturated iron. The proposed dipole will develop a uniform field over a region that is 80 mm high by 130 mm wide over a range of central induction from 0.4 T to almost 8 T. Each dipole for the compact light source will have a magnetic length of about 0.38 meters.

  19. Design parameters for a 7.2 tesla bending magnet for a 1.5 GeV compact light source

    SciTech Connect

    Green, M.A.; Madura, D.

    1996-07-01

    This report describes the design for a 7.2 tesla superconducting dipole magnet for a compact synchrotron light source. The proposed magnet is a Vobly type modified picture frame dipole that has the flux returned through unsaturated iron. In this magnet, the iron in the pole pieces is highly saturated. Separately powered coils around the pole pieces are used to direct the flux lines until the flux can be returned through the unsaturated iron. The proposed dipole will develop a uniform field over a region that is 80 mm high by 130 mm wide over a range of central induction from 0.4 T to almost 8 T. Each dipole for the compact light source will have a magnetic length of about 0.38 meters.

  20. Profiles of ion beams and plasma parameters on a multi-frequencies microwaves large bore electron cyclotron resonance ion source with permanent magnets

    SciTech Connect

    Kato, Yushi; Sakamoto, Naoki; Kiriyama, Ryutaro; Takenaka, Tomoya; Kurisu, Yosuke; Nozaki, Dai; Sato, Fuminobu; Iida, Toshiyuki

    2012-02-15

    In order to contribute to various applications of plasma and beams based on an electron cyclotron resonance, a new concept on magnetic field with all magnets on plasma production and confinement has been proposed with enhanced efficiency for broad and dense ion beam. The magnetic field configuration consists of a pair of comb-shaped magnet surrounding plasma chamber cylindrically. Resonance zones corresponding for 2.45 GHz and 11-13 GHz frequencies are positioned at spatially different positions. We launch simultaneously multiplex frequencies microwaves operated individually, try to control profiles of the plasma parameters and the extracted ion beams, and to measure them in detail.

  1. Effects of dietary substitution of zinc-methionine for inorganic zinc sources on growth performance, tissue zinc accumulation and some blood parameters in broiler chicks.

    PubMed

    Jahanian, R; Rasouli, E

    2015-02-01

    This study was designed to evaluate the effects of dietary inclusion of zinc-methionine (ZnMet) as a replacement for conventional inorganic zinc sources on performance, tissue zinc accumulation and some plasma indices in broiler chicks. A total of 450-day-old Ross male broiler chicks were randomly assigned to five pen replicates of nine experimental diets. Dietary treatments consisted of two basal diets supplemented with 40 mg/kg added Zn as feed-grade Zn sulphate or Zn oxide in which, Zn was replaced with that supplied from ZnMet complex by 25, 50, 75 or 100%. At 42 days of age, three randomly selected birds from each pen were bled to measure plasma metabolites; then, the chicks were slaughtered to evaluate carcass characteristics. Results showed that dietary treatments affected (p < 0.05) feed intake during the starter period, and chicks on Zn oxide diets consumed more feed than sulphate counterparts. Furthermore, dietary substitution of inorganic Zn sources by ZnMet caused improvements (p < 0.01) in body weight gain during all experimental periods. Dietary supplementation of ZnMet improved feed conversion efficiency during 1-21 and 1-42, but not in 21-42 days of age. Complete replacement of inorganic Zn by that supplied from ZnMet caused an increase (p < 0.05) in relative liver weight. Similarly, dietary inclusion of ZnMet increased breast meat and carcass yields and reduced abdominal fat percentage (p < 0.05). Incremental levels of ZnMet increased (p < 0.05) zinc concentrations in liver and thymus, and the highest zinc accumulations were seen in 100% ZnMet-supplemented birds. Interestingly, introduction of ZnMet into the diets partially in place of inorganic sources resulted in decreases (p < 0.01) in plasma uric acid and triglycerides concentrations. The present findings indicated that dietary ZnMet inclusion in replacement of inorganic sources in addition to improving growth performance, reduced plasma uric acid and triglycerides concentrations, consequently

  2. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  3. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2013-07-01 2013-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  4. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2011-07-01 2011-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  5. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2014-07-01 2014-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  6. 38 CFR 4.46 - Accurate measurement.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2012-07-01 2012-07-01 false Accurate measurement. 4... RATING DISABILITIES Disability Ratings The Musculoskeletal System § 4.46 Accurate measurement. Accurate measurement of the length of stumps, excursion of joints, dimensions and location of scars with respect...

  7. Dynamic source parameters of the March-May 1969 Serdo Earthquake Sequence in central Afar, Ethiopia, deduced from teleseismic body waves

    NASA Astrophysics Data System (ADS)

    Kebede, Fekadu; Kim, Won-Young; KulháNek, Ota

    1989-05-01

    Long-period teleseismic P and S waveforms for the largest four earthquakes in the Serdo sequence are compared with synthetic seismograms to infer mechanisms, focal depths, source time functions, and dynamic energy release. For all four events studied, the mechanisms are predominantly strike slip. Depth estimates obtained for the four earthquakes by matching synthetic seismograms to the observations are found to lie between 5 and 8 km. The azimuthal variation of observed body wave duration for the main event indicates that the rupture propagated from NE to SW. Average seismic moments obtained from body wave synthetics vary from 4.6×1017 to 2.5×1018 N m. Average final displacements, stress drops, and lengths of the fault are found to lie between 0.16 and 0.56 m, 0.45 and 1.56 MPa, and 10 and 16 km, respectively. The low stress drop value obtained may indicate the presence of softer materials near the source. The energy release shows that the mode of energy release during the sequence took place in two steps, mainly by the two largest shocks.

  8. Comparison of the Effects of Environmental Parameters on the Growth Variability of Vibrio parahaemolyticus Coupled with Strain Sources and Genotypes Analyses

    PubMed Central

    Liu, Bingxuan; Liu, Haiquan; Pan, Yingjie; Xie, Jing; Zhao, Yong

    2016-01-01

    Microbial growth variability plays an important role on food safety risk assessment. In this study, the growth kinetic characteristics corresponding to maximum specific growth rate (μmax) of 50 V. parahaemolyticus isolates from different sources and genotypes were evaluated at different temperatures (10, 20, 30, and 37°C) and salinity (0.5, 3, 5, 7, and 9%) using the automated turbidimetric system Bioscreen C. The results demonstrated that strain growth variability increased as the growth conditions became more stressful both in terms of temperature and salinity. The coefficient of variation (CV) of μmax for temperature was larger than that for salinity, indicating that the impact of temperature on strain growth variability was greater than that of salinity. The strains isolated from freshwater aquatic products had more conspicuous growth variations than those from seawater. Moreover, the strains with tlh+/tdh+/trh− exhibited higher growth variability than tlh+/tdh−/trh− or tlh+/tdh−/trh+, revealing that gene heterogeneity might have possible relations with the growth variability. This research illustrates that the growth environments, strain sources as well as genotypes have impacts on strain growth variability of V. parahaemolyticus, which can be helpful for incorporating strain variability in predictive microbiology and microbial risk assessment. PMID:27446034

  9. Comparison of the Effects of Environmental Parameters on the Growth Variability of Vibrio parahaemolyticus Coupled with Strain Sources and Genotypes Analyses.

    PubMed

    Liu, Bingxuan; Liu, Haiquan; Pan, Yingjie; Xie, Jing; Zhao, Yong

    2016-01-01

    Microbial growth variability plays an important role on food safety risk assessment. In this study, the growth kinetic characteristics corresponding to maximum specific growth rate (μmax) of 50 V. parahaemolyticus isolates from different sources and genotypes were evaluated at different temperatures (10, 20, 30, and 37°C) and salinity (0.5, 3, 5, 7, and 9%) using the automated turbidimetric system Bioscreen C. The results demonstrated that strain growth variability increased as the growth conditions became more stressful both in terms of temperature and salinity. The coefficient of variation (CV) of μmax for temperature was larger than that for salinity, indicating that the impact of temperature on strain growth variability was greater than that of salinity. The strains isolated from freshwater aquatic products had more conspicuous growth variations than those from seawater. Moreover, the strains with tlh (+) /tdh (+) /trh (-) exhibited higher growth variability than tlh (+) /tdh (-) /trh (-) or tlh (+) /tdh (-) /trh (+), revealing that gene heterogeneity might have possible relations with the growth variability. This research illustrates that the growth environments, strain sources as well as genotypes have impacts on strain growth variability of V. parahaemolyticus, which can be helpful for incorporating strain variability in predictive microbiology and microbial risk assessment. PMID:27446034

  10. Calibration of low light/near infrared cameras with satellite remote sensing to measure incandescence and thermal signatures for source parameter estimation

    NASA Astrophysics Data System (ADS)

    Harrild, M.; Webley, P.; Dehn, J.

    2013-12-01

    Volcanic activity ranges from low level lava effusion to large explosive eruptions, easily capable of ejecting ash up to aircraft cruise altitudes. Knowledge and understanding of precursory activity and thermal signatures are vital for monitoring volcanogenic processes. For many years, satellite remote sensing has been used to determine effusion rates and expensive ground based thermal cameras can calibrate these measurements. However, this investigation explores the use of webcams to image volcanic activity in the visible to near-infrared (NIR) portion of the spectrum, by comparison of webcam pixel brightness to temperatures obtained from co-located FLIR cameras. By determining this relationship, webcam imagery can be used to approximate volcanic eruption temperatures, indicating changes in activity. A field campaign, presented here, to Stromboli, June 2013, demonstrates the use of co-located cameras to determine temperatures from pixel brightness resulting from various Type 1, 2a and 2b eruptions. This method is ideal for monitoring (particularly in remote locations) as the cameras are cheap, consume little power, are easily replaced, provide near real-time data and the images can be compared to satellite observations. A plethora of webcam imagery also exists for past eruptions, that will be analyzed and initial results are presented. Preliminary investigations were conducted in laboratory settings to determine saturation levels of each camera (wavelength dependent) and the required temporal resolution to accurately detect thermal signatures and calculate rise rates. Combined together and coupled with other observations such as seismic, infrasonic and space-borne, this data analysis will provide an increased understanding into volcanogenic processes. Two pairs of time co-incidental images showing the progression of an eruption from Stromboli's southwest crater on June 23rd 2013 at 20:52:15 and 20:52:19 UTC. a) and c) show thermal infrared images taken using a

  11. Effects of potential food sources on biological and demographic parameters of the predatory mites Kampimodromus aberrans, Typhlodromus pyri and Amblyseius andersoni.

    PubMed

    Lorenzon, Mauro; Pozzebon, Alberto; Duso, Carlo

    2012-11-01

    Kampimodromus aberrans, Typhlodromus pyri and Amblyseius andersoni are generalist predatory mites important in controlling tetranychid and eriophyoid mites in European vineyards. They can persist by exploiting various non-prey foods when their main prey is absent or scarce. A comparative analysis of the effects of various prey and non-prey foods on the life history of these predators is lacking. In the laboratory, predatory mites were reared on herbivorous mites (Panonychus ulmi, Eotetranychus carpini and Colomerus vitis), a potential alternative prey (Tydeus caudatus) and two non-prey foods, i.e. the pollen of Typha latifolia and the mycelium of Grape downy mildew (GDM) Plasmopara viticola. Developmental times, survival, sex ratio and fecundity as well as life table parameters were estimated. Kampimodromus aberrans developed faster on E. carpini, C. vitis or pollen than on P. ulmi and laid more eggs on pollen than on prey. Low numbers of this predator developed on GDM infected leaves. Tydeus caudatus was not suitable as prey for any of the three predatory mites. Kampimodromus aberrans showed the highest intrinsic rate of population increase when fed on pollen. Developmental times of T. pyri on prey or pollen were similar but fecundity was higher on pollen than on P. ulmi. Typhlodromus pyri had higher intrinsic rates of population increase on C. vitis and pollen than on P. ulmi; E. carpini showed intermediate values whereas GDM resulted in the lowest r ( m ) values. Development of A. andersoni females was faster on pollen and C. vitis than on P. ulmi and GDM. Fecundity was higher on pollen and mites compared to GDM. Life table parameters of A. andersoni did not differ when predators were fed with prey or pollen while GDM led to a lower r ( m ) value. On a specific diet A. andersoni exhibited faster development and higher fecundity than T. pyri and K. aberrans. These findings improve knowledge on factors affecting the potential of predatory mites in controlling

  12. Bismuth sulphides prepared by thermal and hydrothermal decomposition of a single source precursor: the effect of reaction parameters on morphology, microstructure and catalytic activity.

    PubMed

    Siqueira, Guilherme Oliveira; de Oliveira Porto, Arilza; Viana, Marcelo Machado; da Silva, Herculano Vieira; de Souza, Yara Gonçalves; da Silva, Hugo Wallison Alves; de Lima, Geraldo Magela; Matencio, Tulio

    2013-10-14

    Bismuth sulphides were prepared by thermal and hydrothermal decomposition of a precursor, bismuth tris-diethyldithiocarbamate, at different temperatures and times. The obtained results showed that the thermal decomposition of the precursor in a tube furnace was not very appropriate to control particle size and morphology. XRD results showed that at 310 °C the precursor was not fully decomposed but at 500 °C besides the orthorhombic bismuth sulphide, the metallic bismuth also started to be formed. At the highest temperature 1D crystals were formed with an apparent mean crystal size of 138 nm. However, hydrothermal decomposition was shown to be a very suitable method to control particle size and morphology just by varying some parameters such as temperature and time. For 6 hours reaction time, as temperature increased, the apparent mean crystal size decreased. The particle morphology was also very affected by this parameter, at 180 °C only 1D particles (nanorods) with lengths varying from 25 to 4700 nm were formed but at 200 °C not only 1D particles but also 2D particles were (nanosheets) obtained. Bismuth sulphide particles obtained at 180 °C and 24 hours reaction time were shown to be formed mostly by 2D particles compared to those obtained at 6 hours. It was clearly seen that the increase in reaction time and temperature led to the formation of bi-dimensional particles. The presence of 1D crystals in the samples obtained by hydrothermal decomposition at 180 °C/6 h and 180 °C/24 h is responsible for their high catalytic efficiency towards methylene blue dye degradation. PMID:23994884

  13. Accurate SHAPE-directed RNA structure determination

    PubMed Central

    Deigan, Katherine E.; Li, Tian W.; Mathews, David H.; Weeks, Kevin M.

    2009-01-01

    Almost all RNAs can fold to form extensive base-paired secondary structures. Many of these structures then modulate numerous fundamental elements of gene expression. Deducing these structure–function relationships requires that it be possible to predict RNA secondary structures accurately. However, RNA secondary structure prediction for large RNAs, such that a single predicted structure for a single sequence reliably represents the correct structure, has remained an unsolved problem. Here, we demonstrate that quantitative, nucleotide-resolution information from a SHAPE experiment can be interpreted as a pseudo-free energy change term and used to determine RNA secondary structure with high accuracy. Free energy minimization, by using SHAPE pseudo-free energies, in conjunction with nearest neighbor parameters, predicts the secondary structure of deproteinized Escherichia coli 16S rRNA (>1,300 nt) and a set of smaller RNAs (75–155 nt) with accuracies of up to 96–100%, which are comparable to the best accuracies achievable by comparative sequence analysis. PMID:19109441

  14. Characterization of a hybrid target multi-keV x-ray source by a multi-parameter statistical analysis of titanium K-shell emission

    SciTech Connect

    Primout, M.; Babonneau, D.; Jacquet, L.; Gilleron, F.; Peyrusse, O.; Fournier, K. B.; Marrs, R.; May, M. J.; Heeter, R. F.; Wallace, R. J.

    2015-11-10

    We studied the titanium K-shell emission spectra from multi-keV x-ray source experiments with hybrid targets on the OMEGA laser facility. Using the collisional-radiative TRANSPEC code, dedicated to K-shell spectroscopy, we reproduced the main features of the detailed spectra measured with the time-resolved MSPEC spectrometer. We developed a general method to infer the Ne, Te and Ti characteristics of the target plasma from the spectral analysis (ratio of integrated Lyman-α to Helium-α in-band emission and the peak amplitude of individual line ratios) of the multi-keV x-ray emission. Finally, these thermodynamic conditions are compared to those calculated independently by the radiation-hydrodynamics transport code FCI2.

  15. Characterization of a hybrid target multi-keV x-ray source by a multi-parameter statistical analysis of titanium K-shell emission

    DOE PAGES

    Primout, M.; Babonneau, D.; Jacquet, L.; Gilleron, F.; Peyrusse, O.; Fournier, K. B.; Marrs, R.; May, M. J.; Heeter, R. F.; Wallace, R. J.

    2015-11-10

    We studied the titanium K-shell emission spectra from multi-keV x-ray source experiments with hybrid targets on the OMEGA laser facility. Using the collisional-radiative TRANSPEC code, dedicated to K-shell spectroscopy, we reproduced the main features of the detailed spectra measured with the time-resolved MSPEC spectrometer. We developed a general method to infer the Ne, Te and Ti characteristics of the target plasma from the spectral analysis (ratio of integrated Lyman-α to Helium-α in-band emission and the peak amplitude of individual line ratios) of the multi-keV x-ray emission. Finally, these thermodynamic conditions are compared to those calculated independently by the radiation-hydrodynamics transportmore » code FCI2.« less

  16. Evaluation of severe accident risks: Quantification of major input parameters. Experts` determination of source term issues: Volume 2, Revision 1, Part 4

    SciTech Connect

    Harper, F.T.; Breeding, R.J.; Brown, T.D.; Gregory, J.J.; Jow, H.N.; Payne, A.C.; Gorham, E.D.; Amos, C.N.; Helton, J.; Boyd, G.

    1992-06-01

    In support of the Nuclear Regulatory Commission`s (NRC`s) assessment of the risk from severe accidents at commercial nuclear power plants in the US reported in NUREG-1150, the Severe Accident Risk Reduction Program (SAARP) has completed a revised calculation of the risk to the general public from severe accidents at five nuclear power plants: Surry, Sequoyah, Zion, Peach Bottom and Grand Gulf. The emphasis in this risk analysis was not on determining a point estimate of risk, but to determine the distribution of risk, and to assess the uncertainties that account for the breadth of this distribution. Off-site risk initiation by events, both internal to the power station and external to the power station. Much of this important input to the logic models was generated by expert panels. This document presents the distributions and the rationale supporting the distributions for the questions posed to the Source Term Panel.

  17. Pyromat II micropyrolysis of source rocks and oil shales: Effects of native content and sample size on T sub max values and kinetic parameters

    SciTech Connect

    Reynolds, J.G.; Murray, A.

    1991-01-01

    The Pyromat 2 micropyrolyzer can routinely measure kinetics on standard shales and source rocks. However, when examining samples which have high native bitumen contents, samples with high TOC and native bitumen contents, asphaltenes, tar sands, and other non-kerogen type materials, the pyrolysis profiles sometimes deviate from normal expected behavior. Some of the deviant features are: (1) evolution before the maximum assigned to kerogen breakdown, (2) broadening of the maximum assigned to kerogen breakdown and shifting in T{sub max} with increasing sample size, and (3) artifacts in activation energy distributions derived in kinetic analyses. This report examines these features in more detail and offers potential experimental solutions to circumvent problems created by these features. 9 refs., 9 figs., 5 tabs.

  18. Characterization of a hybrid target multi-keV x-ray source by a multi-parameter statistical analysis of titanium K-shell emission

    NASA Astrophysics Data System (ADS)

    Primout, M.; Babonneau, D.; Jacquet, L.; Gilleron, F.; Peyrusse, O.; Fournier, K. B.; Marrs, R.; May, M. J.; Heeter, R. F.; Wallace, R. J.

    2016-03-01

    We have studied the titanium K-shell emission spectra from multi-keV x-ray source experiments with hybrid targets on the OMEGA laser facility. Using the collisional-radiative TRANSPEC code, dedicated to K-shell spectroscopy, we reproduced the main features of the detailed spectra measured with the time-resolved MSPEC spectrometer. We have developed a general method to infer the Ne, Te and Ti characteristics of the target plasma from the spectral analysis (ratio of integrated Lyman-α to Helium-α in-band emission and the peak amplitude of individual line ratios) of the multi-keV x-ray emission. These thermodynamic conditions are compared to those calculated independently by the radiation-hydrodynamics transport code FCI2.

  19. Effects of diets differing in protein source and technical treatment on digestibility, performance and visceral and biochemical parameters of fattening pigs.

    PubMed

    Liermann, Wendy; Berk, Andreas; Böschen, Verena; Dänicke, Sven

    2016-01-01

    The aim of the experiment on 100 cross-bred barrows was to compare commercial diets for fattening pigs based on either soya bean meal (SBM) imported from non-European countries with diets based on a mixture of locally produced rape seed meal, distillers' dried grains with solubles and soya beans as main protein sources. In addition, these both types of diets were processed by two different technical feed treatments, i.e. coarse grinding without hydrothermal treatment or fine grinding and pelleting. With only few exceptions, nutrients of the diet without SBM were more digestible (p < 0.05) resulting in a higher metabolisable energy (ME) content. Fine grinding and pelleting increased also the ME content and the nutrient digestibility with the exception of crude fibre. Higher feed intake of animals that fed diets without SBM (p < 0.01) resulted in higher average daily gain (p < 0.01). However feeding this diet, the higher digestibility was not reflected in a decreased feed-to-gain ratio (FGR), but fine grinding and pelleting reduced FGR (p < 0.001). A higher pH value and a lower DM content of caecal chymus were detected in animals that received coarsely ground feed (p < 0.05). Animals that fed finely ground and pelleted feed had higher slaughter and relative liver weights and higher blood cholesterol concentrations (p = 0.040). The urea concentrations of blood were lower (p = 0.019) after feeding diets without SBM. In conclusion, SBM imported from non-European countries can be replaced by alternative local protein sources without compromising digestibility or performances of animals. Although fine grinding and thermal treatment particularly seemed to be advantageous for digestibility and performance, the possible risk of development of stomach lesions should be considered. PMID:27032030

  20. A quick accurate model of nozzle backflow

    NASA Technical Reports Server (NTRS)

    Kuharski, R. A.

    1991-01-01

    Backflow from nozzles is a major source of contamination on spacecraft. If the craft contains any exposed high voltages, the neutral density produced by the nozzles in the vicinity of the craft needs to be known in order to assess the possibility of Paschen breakdown or the probability of sheath ionization around a region of the craft that collects electrons for the plasma. A model for backflow has been developed for incorporation into the Environment-Power System Analysis Tool (EPSAT) which quickly estimates both the magnitude of the backflow and the species makeup of the flow. By combining the backflow model with the Simons (1972) model for continuum flow it is possible to quickly estimate the density of each species from a nozzle at any position in space. The model requires only a few physical parameters of the nozzle and the gas as inputs and is therefore ideal for engineering applications.

  1. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  2. PYFLOW_2.0. A new open-source software for quantifying impact parameters and deposition rates of dilute pyroclastic density currents

    NASA Astrophysics Data System (ADS)

    Dioguardi, Fabio; Dellino, Pierfrancesco; Mele, Daniela

    2016-04-01

    Dilute pyroclastic density currents (DPDCs) are one of the hazardous events that can happen during explosive eruptions. They are ground-hugging turbulent gas-particle flows that move down volcano slopes under the combined action of density contrast and gravity. DPDCs are dangerous for human lives and infrastructures both because they exert a dynamic pressure in their direction of motion and transport volcanic ash particles, which remain in the atmosphere during and after the passage of DPDC until they settle on the ground. Deposits formed by the passage of a DPDC show peculiar characteristics that can be linked to flow field variables. This has been the subject of extensive investigations in the past years leading to the formulation of a sedimentological model (Dellino et al. 2008), which has been used for evaluating the impact parameters of past eruptions on a statistical basis for hazard assessment purposes. The model has been recently translated in a Fortran code (PYFLOW, Dioguardi and Dellino, 2014). Here we present the latest release of this code (PYFLOW_2.0) which, besides significant improvements in the code structure, computation times and the introduction of a user friendly data input method, allows to calculate the deposition time and rate of the ash and lapilli layer formed by a DPDC by linking deposit (e.g. componentry, grainsize) to flow (e.g. flow average density and shear velocity) characteristics as calculated by the aforementioned sedimentological model. The deposition rate is calculated by summing the contributions of each grainsize class of all components constituting the deposit (e.g. juvenile particles, crystals, etc.), which are in turn computed as a function of particle density, terminal velocity, concentration and deposition probability. Here we apply the concept of deposition probability, previously introduced for estimating the deposition rates of turbidity currents (Stow and Bowen, 1980), to DPDCs, although with a different approach, i

  3. The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes. Review of sources and main parameters.

    PubMed

    Marcet, Ismael; Álvarez, Carlos; Paredes, Benjamín; Díaz, Mario

    2016-03-01

    Food industry processing wastes are produced in enormous amounts every year, such wastes are usually disposed with the corresponding economical cost it implies, in the best scenario they can be used for pet food or composting. However new promising technologies and tools have been developed in the last years aimed at recovering valuable compounds from this type of materials. In particular, sub-critical water hydrolysis (SWH) has been revealed as an interesting way for recovering high added-value molecules, and its applications have been broadly referred in the bibliography. Special interest has been focused on recovering protein hydrolysates in form of peptides or amino acids, from both animal and vegetable wastes, by means of SWH. These recovered biomolecules have a capital importance in fields such as biotechnology research, nutraceuticals, and above all in food industry, where such products can be applied with very different objectives. Present work reviews the current state of art of using sub-critical water hydrolysis for protein recovering from food industry wastes. Key parameters as reaction time, temperature, amino acid degradation and kinetic constants have been discussed. Besides, the characteristics of the raw material and the type of products that can be obtained depending on the substrate have been reviewed. Finally, the application of these hydrolysates based on their functional properties and antioxidant activity is described. PMID:26831563

  4. The use of sub-critical water hydrolysis for the recovery of peptides and free amino acids from food processing wastes. Review of sources and main parameters.

    PubMed

    Marcet, Ismael; Álvarez, Carlos; Paredes, Benjamín; Díaz, Mario

    2016-03-01

    Food industry processing wastes are produced in enormous amounts every year, such wastes are usually disposed with the corresponding economical cost it implies, in the best scenario they can be used for pet food or composting. However new promising technologies and tools have been developed in the last years aimed at recovering valuable compounds from this type of materials. In particular, sub-critical water hydrolysis (SWH) has been revealed as an interesting way for recovering high added-value molecules, and its applications have been broadly referred in the bibliography. Special interest has been focused on recovering protein hydrolysates in form of peptides or amino acids, from both animal and vegetable wastes, by means of SWH. These recovered biomolecules have a capital importance in fields such as biotechnology research, nutraceuticals, and above all in food industry, where such products can be applied with very different objectives. Present work reviews the current state of art of using sub-critical water hydrolysis for protein recovering from food industry wastes. Key parameters as reaction time, temperature, amino acid degradation and kinetic constants have been discussed. Besides, the characteristics of the raw material and the type of products that can be obtained depending on the substrate have been reviewed. Finally, the application of these hydrolysates based on their functional properties and antioxidant activity is described.

  5. Optimization of the Ion Source-Mass Spectrometry Parameters in Non-Steroidal Anti-Inflammatory and Analgesic Pharmaceuticals Analysis by a Design of Experiments Approach

    NASA Astrophysics Data System (ADS)

    Paíga, Paula; Silva, Luís M. S.; Delerue-Matos, Cristina

    2016-08-01

    The flow rates of drying and nebulizing gas, heat block and desolvation line temperatures and interface voltage are potential electrospray ionization parameters as they may enhance sensitivity of the mass spectrometer. The conditions that give higher sensitivity of 13 pharmaceuticals were explored. First, Plackett-Burman design was implemented to screen significant factors, and it was concluded that interface voltage and nebulizing gas flow were the only factors that influence the intensity signal for all pharmaceuticals. This fractionated factorial design was projected to set a full 22 factorial design with center points. The lack-of-fit test proved to be significant. Then, a central composite face-centered design was conducted. Finally, a stepwise multiple linear regression and subsequently an optimization problem solving were carried out. Two main drug clusters were found concerning the signal intensities of all runs of the augmented factorial design. p-Aminophenol, salicylic acid, and nimesulide constitute one cluster as a result of showing much higher sensitivity than the remaining drugs. The other cluster is more homogeneous with some sub-clusters comprising one pharmaceutical and its respective metabolite. It was observed that instrumental signal increased when both significant factors increased with maximum signal occurring when both codified factors are set at level +1. It was also found that, for most of the pharmaceuticals, interface voltage influences the intensity of the instrument more than the nebulizing gas flowrate. The only exceptions refer to nimesulide where the relative importance of the factors is reversed and still salicylic acid where both factors equally influence the instrumental signal.

  6. Optimization of the Ion Source-Mass Spectrometry Parameters in Non-Steroidal Anti-Inflammatory and Analgesic Pharmaceuticals Analysis by a Design of Experiments Approach.

    PubMed

    Paíga, Paula; Silva, Luís M S; Delerue-Matos, Cristina

    2016-10-01

    The flow rates of drying and nebulizing gas, heat block and desolvation line temperatures and interface voltage are potential electrospray ionization parameters as they may enhance sensitivity of the mass spectrometer. The conditions that give higher sensitivity of 13 pharmaceuticals were explored. First, Plackett-Burman design was implemented to screen significant factors, and it was concluded that interface voltage and nebulizing gas flow were the only factors that influence the intensity signal for all pharmaceuticals. This fractionated factorial design was projected to set a full 2(2) factorial design with center points. The lack-of-fit test proved to be significant. Then, a central composite face-centered design was conducted. Finally, a stepwise multiple linear regression and subsequently an optimization problem solving were carried out. Two main drug clusters were found concerning the signal intensities of all runs of the augmented factorial design. p-Aminophenol, salicylic acid, and nimesulide constitute one cluster as a result of showing much higher sensitivity than the remaining drugs. The other cluster is more homogeneous with some sub-clusters comprising one pharmaceutical and its respective metabolite. It was observed that instrumental signal increased when both significant factors increased with maximum signal occurring when both codified factors are set at level +1. It was also found that, for most of the pharmaceuticals, interface voltage influences the intensity of the instrument more than the nebulizing gas flowrate. The only exceptions refer to nimesulide where the relative importance of the factors is reversed and still salicylic acid where both factors equally influence the instrumental signal. Graphical Abstract ᅟ. PMID:27527098

  7. Optimization of the Ion Source-Mass Spectrometry Parameters in Non-Steroidal Anti-Inflammatory and Analgesic Pharmaceuticals Analysis by a Design of Experiments Approach.

    PubMed

    Paíga, Paula; Silva, Luís M S; Delerue-Matos, Cristina

    2016-10-01

    The flow rates of drying and nebulizing gas, heat block and desolvation line temperatures and interface voltage are potential electrospray ionization parameters as they may enhance sensitivity of the mass spectrometer. The conditions that give higher sensitivity of 13 pharmaceuticals were explored. First, Plackett-Burman design was implemented to screen significant factors, and it was concluded that interface voltage and nebulizing gas flow were the only factors that influence the intensity signal for all pharmaceuticals. This fractionated factorial design was projected to set a full 2(2) factorial design with center points. The lack-of-fit test proved to be significant. Then, a central composite face-centered design was conducted. Finally, a stepwise multiple linear regression and subsequently an optimization problem solving were carried out. Two main drug clusters were found concerning the signal intensities of all runs of the augmented factorial design. p-Aminophenol, salicylic acid, and nimesulide constitute one cluster as a result of showing much higher sensitivity than the remaining drugs. The other cluster is more homogeneous with some sub-clusters comprising one pharmaceutical and its respective metabolite. It was observed that instrumental signal increased when both significant factors increased with maximum signal occurring when both codified factors are set at level +1. It was also found that, for most of the pharmaceuticals, interface voltage influences the intensity of the instrument more than the nebulizing gas flowrate. The only exceptions refer to nimesulide where the relative importance of the factors is reversed and still salicylic acid where both factors equally influence the instrumental signal. Graphical Abstract ᅟ.

  8. Optimization of the Ion Source-Mass Spectrometry Parameters in Non-Steroidal Anti-Inflammatory and Analgesic Pharmaceuticals Analysis by a Design of Experiments Approach

    NASA Astrophysics Data System (ADS)

    Paíga, Paula; Silva, Luís M. S.; Delerue-Matos, Cristina

    2016-10-01

    The flow rates of drying and nebulizing gas, heat block and desolvation line temperatures and interface voltage are potential electrospray ionization parameters as they may enhance sensitivity of the mass spectrometer. The conditions that give higher sensitivity of 13 pharmaceuticals were explored. First, Plackett-Burman design was implemented to screen significant factors, and it was concluded that interface voltage and nebulizing gas flow were the only factors that influence the intensity signal for all pharmaceuticals. This fractionated factorial design was projected to set a full 22 factorial design with center points. The lack-of-fit test proved to be significant. Then, a central composite face-centered design was conducted. Finally, a stepwise multiple linear regression and subsequently an optimization problem solving were carried out. Two main drug clusters were found concerning the signal intensities of all runs of the augmented factorial design. p-Aminophenol, salicylic acid, and nimesulide constitute one cluster as a result of showing much higher sensitivity than the remaining drugs. The other cluster is more homogeneous with some sub-clusters comprising one pharmaceutical and its respective metabolite. It was observed that instrumental signal increased when both significant factors increased with maximum signal occurring when both codified factors are set at level +1. It was also found that, for most of the pharmaceuticals, interface voltage influences the intensity of the instrument more than the nebulizing gas flowrate. The only exceptions refer to nimesulide where the relative importance of the factors is reversed and still salicylic acid where both factors equally influence the instrumental signal.

  9. The 1911 M ~6.6 Calaveras earthquake: Source parameters and the role of static, viscoelastic, and dynamic coulomb stress changes imparted by the 1906 San Francisco earthquake

    USGS Publications Warehouse

    Doser, D.I.; Olsen, K.B.; Pollitz, F.F.; Stein, R.S.; Toda, S.

    2009-01-01

    The occurrence of a right-lateral strike-slip earthquake in 1911 is inconsistent with the calculated 0.2-2.5 bar static stress decrease imparted by the 1906 rupture at that location on the Calaveras fault, and 5 yr of calculated post-1906 viscoelastic rebound does little to reload the fault. We have used all available first-motion, body-wave, and surface-wave data to explore possible focal mechanisms for the 1911 earthquake. We find that the event was most likely a right-lateral strikeslip event on the Calaveras fault, larger than, but otherwise resembling, the 1984 Mw 6.1 Morgan Hill earthquake in roughly the same location. Unfortunately, we could recover no unambiguous surface fault offset or geodetic strain data to corroborate the seismic analysis despite an exhaustive archival search. We calculated the static and dynamic Coulomb stress changes for three 1906 source models to understand stress transfer to the 1911 site. In contrast to the static stress shadow, the peak dynamic Coulomb stress imparted by the 1906 rupture promoted failure at the site of the 1911 earthquake by 1.4-5.8 bar. Perhaps because the sample is small and the aftershocks are poorly located, we find no correlation of 1906 aftershock frequency or magnitude with the peak dynamic stress, although all aftershocks sustained a calculated dynamic stress of ???3 bar. Just 20 km to the south of the 1911 epicenter, we find that surface creep of the Calaveras fault at Hollister paused for ~17 yr after 1906, about the expected delay for the calculated static stress drop imparted by the 1906 earthquake when San Andreas fault postseismic creep and viscoelastic relaxation are included. Thus, the 1911 earthquake may have been promoted by the transient dynamic stresses, while Calaveras fault creep 20 km to the south appears to have been inhibited by the static stress changes.

  10. Source parameters of the 2014 Mw 6.1 South Napa earthquake estimated from the Sentinel 1A, COSMO-SkyMed and GPS data

    NASA Astrophysics Data System (ADS)

    Guangcai, Feng; Zhiwei, Li; Xinjian, Shan; Bing, Xu; Yanan, Du

    2015-08-01

    Using the combination of two InSAR and one GPS data sets, we present the detailed source model of the 2014 Mw 6.1 South Napa earthquake, the biggest tremor to hit the San Francisco Bay Area since the 1989 Mw 6.9 Loma Prieta earthquake. The InSAR data are from the Sentinel-1A (S1A) and COSMO-SkyMed (CS) satellites, and GPS data are provided by Nevada Geodetic Laboratory. We firstly obtain the complete coseismic deformation fields of this event and estimate the InSAR data errors, then using the S1A data to construct the fault geometry, one main and two short parallel sub-faults which haven't been identified by field investigation. As expected the geometry is in good agreement with the aftershock distribution. By inverting the InSAR and GPS data, we derive a three segment slip and rake models. Our model indicates that this event was a right-lateral strike-slip earthquake with a slight reverse component in the West Napa Fault as we estimated. The fault is ~ 30 km long and more than 80% of the seismic moment was released at the center of the fault segment, where the slip reached its maximum (up to 1 m). We also find that our geodetic moment magnitude is 2.07 × 1018 Nm, corresponding to Mw 6.18, larger than that of USGS (Mw 6.0) and GCMT (Mw 6.1). This difference may partly be explained by our InSAR data including about one week's postseismic deformation and aftershocks. The results also demonstrate high SNR and great ability of the newly launched Sentinel-1A in earthquake study. Furthermore, this study suggests that this earthquake has potential to trigger nearby faults, especially the Green Valley fault where the coulomb stress was imparted by the 2014 South Napa earthquake.

  11. Sensitivity Analysis of Hardwired Parameters in GALE Codes

    SciTech Connect

    Geelhood, Kenneth J.; Mitchell, Mark R.; Droppo, James G.

    2008-12-01

    The U.S. Nuclear Regulatory Commission asked Pacific Northwest National Laboratory to provide a data-gathering plan for updating the hardwired data tables and parameters of the Gaseous and Liquid Effluents (GALE) codes to reflect current nuclear reactor performance. This would enable the GALE codes to make more accurate predictions about the normal radioactive release source term applicable to currently operating reactors and to the cohort of reactors planned for construction in the next few years. A sensitivity analysis was conducted to define the importance of hardwired parameters in terms of each parameter’s effect on the emission rate of the nuclides that are most important in computing potential exposures. The results of this study were used to compile a list of parameters that should be updated based on the sensitivity of these parameters to outputs of interest.

  12. Accurate method of modeling cluster scaling relations in modified gravity

    NASA Astrophysics Data System (ADS)

    He, Jian-hua; Li, Baojiu

    2016-06-01

    We propose a new method to model cluster scaling relations in modified gravity. Using a suite of nonradiative hydrodynamical simulations, we show that the scaling relations of accumulated gas quantities, such as the Sunyaev-Zel'dovich effect (Compton-y parameter) and the x-ray Compton-y parameter, can be accurately predicted using the known results in the Λ CDM model with a precision of ˜3 % . This method provides a reliable way to analyze the gas physics in modified gravity using the less demanding and much more efficient pure cold dark matter simulations. Our results therefore have important theoretical and practical implications in constraining gravity using cluster surveys.

  13. Source components and intensive parameters of magma genesis in the CentAm and North IBM arcs: analyses using Arc Basalt Simulator model

    NASA Astrophysics Data System (ADS)

    Kimura, J.; Stern, R. J.; Yoshida, T.

    2007-12-01

    melting at 3%F/2.3GPa with a flux rate 0.05%. Costa Rica segment VF basalts (strongest HIMU signature) require NGD- AOC, SED, and DPM peridotite for Arenal and PM for Platanar basalts. Slab dehydration conditions are SED/AOC = 2/98 for Arenal and 0.7/99.3 for Platanar at 1000C/6GPa and 1100C/6GPa, respectively. Melting conditions are 2%F/2.3GPa with flux rate 0.2% for Arenal and 5%/2.3GPa with flux rate 2% for Platanar. The most rear arc OIB La Providencia basalt needs the strongest HIMU SGD-AOC with SED/AOC = 10/90 slab dehydrated at 1000/6GPa fluxed to melt PM at 1%F/2.3GPa with 0.01% flux rate. Slab dehydration temperature is generally higher beneath CentAm (950-1100C) than beneath N-Izu (880-980C), especially for Costa Rica (1000-1100), reflecting the much younger age of the CentAm slab. Mantle melting degree is high for N-Izu VF (24%F) but low for CentAm and N-Izu RA (2-5%F). Fluid flux rate is low beneath RAs of both arcs (0.01-0.05%) and larger beneath both volcanic fronts (0.2-2%). VF sub-alkaline basalts have relatively low fluid flux (0.05-0.5%) compared to larger flux for the alkali basalt (2%) in VF (Platanar) and behind VF (Yojoa). Intensive parameters derived from the calculations appear to be consistent with the two different tectonic settings between N-Izu and CentAm.

  14. Beyond Ellipse(s): Accurately Modelling the Isophotal Structure of Galaxies with ISOFIT and CMODEL

    NASA Astrophysics Data System (ADS)

    Ciambur, B. C.

    2015-09-01

    This work introduces a new fitting formalism for isophotes that enables more accurate modeling of galaxies with non-elliptical shapes, such as disk galaxies viewed edge-on or galaxies with X-shaped/peanut bulges. Within this scheme, the angular parameter that defines quasi-elliptical isophotes is transformed from the commonly used, but inappropriate, polar coordinate to the “eccentric anomaly.” This provides a superior description of deviations from ellipticity, better capturing the true isophotal shape. Furthermore, this makes it possible to accurately recover both the surface brightness profile, using the correct azimuthally averaged isophote, and the two-dimensional model of any galaxy: the hitherto ubiquitous, but artificial, cross-like features in residual images are completely removed. The formalism has been implemented into the Image Reduction and Analysis Facility tasks Ellipse and Bmodel to create the new tasks “Isofit,” and “Cmodel.” The new tools are demonstrated here with application to five galaxies, chosen to be representative case-studies for several areas where this technique makes it possible to gain new scientific insight. Specifically: properly quantifying boxy/disky isophotes via the fourth harmonic order in edge-on galaxies, quantifying X-shaped/peanut bulges, higher-order Fourier moments for modeling bars in disks, and complex isophote shapes. Higher order (n > 4) harmonics now become meaningful and may correlate with structural properties, as boxyness/diskyness is known to do. This work also illustrates how the accurate construction, and subtraction, of a model from a galaxy image facilitates the identification and recovery of over-lapping sources such as globular clusters and the optical counterparts of X-ray sources.

  15. Accurately measuring MPI broadcasts in a computational grid

    SciTech Connect

    Karonis N T; de Supinski, B R

    1999-05-06

    timing of events and, thus, eliminate concurrency between the collective communications that they measure. However, accurate event timing predictions are often impossible since network delays and local processing overheads are stochastic. Further, reasonable predictions are not possible if source code of the implementation is unavailable to the benchmark. We focus on measuring the performance of broadcast communication.

  16. An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography

    SciTech Connect

    Feng Jinchao; Qin Chenghu; Jia Kebin; Han Dong; Liu Kai; Zhu Shouping; Yang Xin; Tian Jie

    2011-11-15

    rather than monochromatic data. Furthermore, the study conducted using an adaptive regularization parameter demonstrated our ability to accurately localize the bioluminescent source. With the adaptively estimated regularization parameter, the reconstructed center position of the source was (20.37, 31.05, 12.95) mm, and the distance to the real source was 0.63 mm. The results of the dual-source experiments further showed that our algorithm could localize the bioluminescent sources accurately. The authors then presented experimental evidence that the proposed algorithm exhibited its calculated efficiency over the heuristic method. The effectiveness of the new algorithm was also confirmed by comparing it with the L-curve method. Furthermore, various initial speculations regarding the regularization parameter were used to illustrate the convergence of our algorithm. Finally, in vivo mouse experiment further illustrates the effectiveness of the proposed algorithm. Conclusions: Utilizing numerical, physical phantom and in vivo examples, we demonstrated that the bioluminescent sources could be reconstructed accurately with automatic regularization parameters. The proposed algorithm exhibited superior performance than both the heuristic regularization parameter choice method and L-curve method based on the computational speed and localization error.

  17. Mill profiler machines soft materials accurately

    NASA Technical Reports Server (NTRS)

    Rauschl, J. A.

    1966-01-01

    Mill profiler machines bevels, slots, and grooves in soft materials, such as styrofoam phenolic-filled cores, to any desired thickness. A single operator can accurately control cutting depths in contour or straight line work.

  18. An articulated statistical shape model for accurate hip joint segmentation.

    PubMed

    Kainmueller, Dagmar; Lamecker, Hans; Zachow, Stefan; Hege, Hans-Christian

    2009-01-01

    In this paper we propose a framework for fully automatic, robust and accurate segmentation of the human pelvis and proximal femur in CT data. We propose a composite statistical shape model of femur and pelvis with a flexible hip joint, for which we extend the common definition of statistical shape models as well as the common strategy for their adaptation. We do not analyze the joint flexibility statistically, but model it explicitly by rotational parameters describing the bent in a ball-and-socket joint. A leave-one-out evaluation on 50 CT volumes shows that image driven adaptation of our composite shape model robustly produces accurate segmentations of both proximal femur and pelvis. As a second contribution, we evaluate a fine grain multi-object segmentation method based on graph optimization. It relies on accurate initializations of femur and pelvis, which our composite shape model can generate. Simultaneous optimization of both femur and pelvis yields more accurate results than separate optimizations of each structure. Shape model adaptation and graph based optimization are embedded in a fully automatic framework. PMID:19964159

  19. Event reconstruction for line source releases

    SciTech Connect

    Zajic, Dragan; Brown, Michael J; Williams, Michael D

    2010-01-01

    The goal of source inversion, also called event reconstruction, is the calculation of source parameters from information obtained by network of concentration (or dosage) and meteorological sensors. Source parameters include source location and strength, but in certain cases there could be more than one source so the inversion procedure could deal with determination of number of sources, as well. In a case of limited time period pollutant emission events, as for example during accidents or intentional releases, it is of great use to estimate starting and ending times of the event. This kind of research is very useful for estimating the source parameters of industrial pollutants since it provides important information for regulation purposes. Also it provides information to fast responders in a case of accidental pollutant releases or for homeland security needs when chemical, biological or radiological agent is deliberately released. Development of faster and more accurate algorithms is very important since it could help reduce the populace's exposure to dangerous airborne contaminants, plan evacuation routes, and help assess the magnitude of clean up. During the last decade, the large number of research papers in area of source inversion was published where many different approaches were used. Most of the source inversion work publish to date apply to point source releases. The forward dispersion models used range from fast Gaussian plume and puff codes that enable almost instantaneous calculations of concentrations and dosages to Computational Fluid Dynamics (CFD) codes that provide more detailed and precise calculation but at the same time are expensive with respect to time and computer resources. The optimization methods were often used and examples are simulated annealing and genetic algorithms.

  20. LISA source confusion

    SciTech Connect

    Crowder, Jeff; Cornish, Neil J.

    2004-10-15

    The Laser Interferometer Space Antenna will detect thousands of gravitational wave sources. Many of these sources will be overlapping in the sense that their signals will have a nonzero cross correlation. Such overlaps lead to source confusion, which adversely affects how well we can extract information about the individual sources. Here we study how source confusion impacts parameter estimation for galactic compact binaries, with emphasis on the effects of the number of overlaping sources, the time of observation, the gravitational wave frequencies of the sources, and the degree of the signal correlations. Our main findings are that the parameter resolution decays exponentially with the number of overlapping sources and superexponentially with the degree of cross correlation. We also find that an extended mission lifetime is key to disentangling the source confusion as the parameter resolution for overlapping sources improves much faster than the usual square root of the observation time.

  1. More-Accurate Model of Flows in Rocket Injectors

    NASA Technical Reports Server (NTRS)

    Hosangadi, Ashvin; Chenoweth, James; Brinckman, Kevin; Dash, Sanford

    2011-01-01

    An improved computational model for simulating flows in liquid-propellant injectors in rocket engines has been developed. Models like this one are needed for predicting fluxes of heat in, and performances of, the engines. An important part of predicting performance is predicting fluctuations of temperature, fluctuations of concentrations of chemical species, and effects of turbulence on diffusion of heat and chemical species. Customarily, diffusion effects are represented by parameters known in the art as the Prandtl and Schmidt numbers. Prior formulations include ad hoc assumptions of constant values of these parameters, but these assumptions and, hence, the formulations, are inaccurate for complex flows. In the improved model, these parameters are neither constant nor specified in advance: instead, they are variables obtained as part of the solution. Consequently, this model represents the effects of turbulence on diffusion of heat and chemical species more accurately than prior formulations do, and may enable more-accurate prediction of mixing and flows of heat in rocket-engine combustion chambers. The model has been implemented within CRUNCH CFD, a proprietary computational fluid dynamics (CFD) computer program, and has been tested within that program. The model could also be implemented within other CFD programs.

  2. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    NASA Technical Reports Server (NTRS)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  3. Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Skaloud, J.

    2015-08-01

    In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.