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1

Seismic anisotropy estimated from P-wave arrival times in crosshole measurements  

NASA Astrophysics Data System (ADS)

Seismic anisotropy is evidenced in the inner core, upper mantle and the lower crust in large scale, and the evidence is generally provided by shear wave splitting analysis. Here this paper searches for the evidence of anisotropy in the uppermost crust, by using P-wave arrival times from crosshole seismic measurement to directly estimate velocity anisotropy associated with the fine-layering effect of multiple sedimentary beds. Conceptually fine layering causes the so-called VTI (vertical transverse isotropy) anisotropy with a vertical symmetry and the effect is parametrized by the horizontal and vertical velocity ratio. It is found however that the VTI anisotropic parameter does not have a simple vertical symmetry but is also azimuth dependent. This azimuthal anisotropy may reflect the fracture orientation due to large-scale tectonic movements, and is very important in the production of oil reservoirs, as the seismically fast directions can indicate preferred directions of fluid flow. This paper presents innovative methods for anisotropy analysis in both vertical and horizontal plane. Integrated seismic anisotropy interpretation clearly indicates distinguished strain orientations forming fractures in Oligocenic, Miocenic and Pliocenic sediment, in the edge of the extensional basin immediately next to Tan-Lu Fault, an active continental strike-slip fault zone.

Wang, Yanghua

2011-03-01

2

P-wave arrival times for the 1991 racha, Georgia earthquake sequence at stations of a test, sparse network  

SciTech Connect

The following arrival information is a supplement to Myers and Schultz (2000). Myers and Schultz (2000) demonstrate the improvement in sparse-network location that can be achieved by using travel-time corrections determined with a Bayesian Kriging algorithm (Schultz et al., 1998). Precise, benchmark locations are provided by a local aftershock study of the 1991 Racha, Georgia earthquake sequence in the Caucasus Mountains (Fuenzalida et al., 1997). A test network is used to relocate the aftershocks with and without travel-time corrections. The test network is meant to represent a typical International Monitoring System configuration, with 6 stations at regional to near teleseismic distances (less then 30{sup o} from the epicenter). The following arrival-time data help to facilitate the reproduction of Myers and Schultz (2000). The arrival picks were obtained from the International Seismic Center (ISC) (openly available) and a Lawrence Livermore National Laboratory (LLNL) analyst (Flori Ryan). Table 1 lists the arrivals in epic time (time since January 1, 1970). The author of the arrival pick is listed as either ''flori'' or ''-'', where ''-'' indicates ISC. Table 2 lists the hypocenter information determined in the local aftershock study of Fuenzalida et al. (1997), and Table 3 lists the station information for the Racha test network. Fields in all tables are described in the CSS3.O database schema.

Myers, S C; Schultz, C A; Ryall, F

2000-02-02

3

Shallow subduction beneath Italy: Three-dimensional images of the Adriatic-European-Tyrrhenian lithosphere system based on high-quality P wave arrival times  

Microsoft Academic Search

This paper presents a velocity model of the Italian (central Mediterranean) lithosphere in unprecedented detail. The model is derived by inverting a set of 166,000 Pg and Pn seismic wave arrival times, restricted to the highest-quality data available. The tomographic images reveal the geometry of the subduction-collision system between the European, Adriatic, and Tyrrhenian plates, over a larger volume and

R. Di Stefano; E. Kissling; C. Chiarabba; A. Amato; D. Giardini

2009-01-01

4

Resolving P-wave travel-time anomalies using seismic array observations of oceanic storms  

E-print Network

Resolving P-wave travel-time anomalies using seismic array observations of oceanic storms Jian California reveals P-wave arrivals from distant storms in open oceans. In this case, the noise can results suggest using oceanic storms as additional seismic sources for resolving P-wave travel

Gerstoft, Peter

5

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL  

E-print Network

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL REIMBURSEMENT obtain a Travel Advance for this trip? No Yes Was there any personal time during this trip? No Yes From.S. Citizen: Yes No City of Residence: Vendor I.D. # (if known): Purpose of Travel: Destination: Did you

Bigelow, Stephen

6

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL  

E-print Network

Final Arrival Location: Final Arrival Date: Final Arrival Time: FOREIGN TRAVEL REIMBURSEMENT: ______________________ Date:_____________________ Non-UC travelers - your SSN # is required:_______________ U.S. Citizen: Yes): _______________________ Purpose of Travel: Destination: Did you obtain a Travel Advance for this trip? No Yes Was there any

Ahlers, Guenter

7

Gaussian modeling of the P-wave morphology time course applied to anticipate paroxysmal atrial fibrillation.  

PubMed

This paper introduces a new algorithm to quantify the P-wave morphology time course with the aim of anticipating as much as possible the onset of paroxysmal atrial fibrillation (PAF). The method is based on modeling each P-wave with a single Gaussian function and analyzing the extracted parameters variability over time. The selected Gaussian approaches are associated with the amplitude, peak timing, and width of the P-wave. In order to validate the algorithm, electrocardiogram segments 2 h preceding the onset of PAF episodes from 46 different patients were assessed. According to the expected intermittently disturbed atrial conduction before the onset of PAF, all the analyzed Gaussian metrics showed an increasing variability trend as the PAF onset approximated. Moreover, the Gaussian P-wave width reported a diagnostic accuracy around 80% to discern between healthy subjects, patients far from PAF, and patients less than 1 h close to a PAF episode. This discriminant power was similar to those provided by the most classical time-domain approach, i.e., the P-wave duration. However, this newly proposed parameter presents the advantage of being less sensitive to a precise delineation of the P-wave boundaries. Furthermore, the linear combination of both metrics improved the diagnostic accuracy up to 86.69%. In conclusion, morphological P-wave characterization provides additional information to the metrics based on P-wave timing. PMID:25298113

Martínez, Arturo; Alcaraz, Raúl; Rieta, José Joaquín

2015-12-01

8

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume I P-Wave Measurements in Borehole C4993 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.  

SciTech Connect

In this volume (I), all P-wave measurements are presented that were performed in Borehole C4993 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 370 to 1400 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used, while below about 1200 ft, depth intervals of 20 ft were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 22 ft in Borehole C4993, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4993, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-07-06

9

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume II P-Wave Measurements in Borehole C4996 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.  

SciTech Connect

In this volume (II), all P-wave measurements are presented that were performed in Borehole C4996 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 360 to 1400 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used, while below about 1180 ft, depth intervals of 20 ft were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 22 ft in Borehole C4996, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4996, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-07-06

10

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume III P-Wave Measurements in Borehole C4997 Seismic Records, Wave-Arrival Identifications and Interpreted P-Wave Velocity Profile.  

SciTech Connect

In this volume (III), all P-wave measurements are presented that were performed in Borehole C4997 at the Waste Treatment Plant (WTP) with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver. P-wave measurements were performed over the depth range of 390 to 1220 ft, typically in 10-ft intervals. However, in some interbeds, 5-ft depth intervals were used. Compression (P) waves were generated by moving the base plate of T-Rex for a given number of cycles at a fixed frequency as discussed in Section 2. This process was repeated so that signal averaging in the time domain was performed using 3 to about 15 averages, with 5 averages typically used. In addition to the LBNL 3-D geophone, called the lower receiver herein, a 3-D geophone from Redpath Geophysics was fixed at a depth of 40 ft (later relocated to 27.5 ft due to visibility in borehole after rain) in Borehole C4997, and a 3-D geophone from the University of Texas was embedded near the borehole at about 1.5 ft below the ground surface. This volume is organized into 12 sections as follows: Section 1: Introduction, Section 2: Explanation of Terminology, Section 3: Vp Profile at Borehole C4997, Sections 4 to 6: Unfiltered P-wave records of lower vertical receiver, reaction mass, and reference receiver, Sections 7 to 9: Filtered P-wave signals of lower vertical receiver, reaction mass and reference receiver, Section 10: Expanded and filtered P-wave signals of lower vertical receiver, and Sections 11 and 12: Waterfall plots of unfiltered and filtered lower vertical receiver signals.

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

11

Walk -Run Activity --An S and P Wave Travel Time ("S minus P" Earthquake Location Method)  

E-print Network

Walk - Run Activity --An S and P Wave Travel Time Simulation ("S minus P" Earthquake Location between distance and time of travel of seismic waves (a travel time-curve). To use the constructed time-travel pencils) Procedure: Part One: Constructing the Travel-Time Graph To model how earthquake waves travel

Smith-Konter, Bridget

12

Target tracking and Estimated Time of Arrival (ETA) Prediction for Arrival Aircraft  

E-print Network

Target tracking and Estimated Time of Arrival (ETA) Prediction for Arrival Aircraft Kaushik Roy Benjamin Levy Claire J. Tomlin§ The problem of developing a unified algorithm for arrival aircraft target. One bottleneck in the flow of aircraft is traffic on the surface of and in the air surrounding

California at Irvine, University of

13

Earthquake Travel Times: Customized Listing of Recent Arrival Times  

NSDL National Science Digital Library

The US Geological Survey Earthquake Hazards Program Web site contains the Earthquake Travel Times Customized Listing of Recent Arrival Times online calculator. The tool allows visitors to generate a listing of the times that phases from recent earthquakes arrived at their particular seismic station. After inputting the latitude and longitude of their location, the distance and magnitude of earthquakes to consider, types of phases, and other parameters, the user gets a simple but informative readout. The data includes the date and time of the earthquake, phase codes, travel time in seconds, arrival time, direction of travel, and more. Any seismologist or other researchers in similar fields should thoroughly appreciate this simple and helpful resource.

14

Relativistic free-motion time-of-arrival  

E-print Network

Relativistic free-motion time-of-arrival theory for massive spin-1/2 particles is systematically developed. Contrary to the nonrelativistic time-of-arrival operator studied thoroughly in previous literatures, the relativistic time-of-arrival operator possesses self-adjoint extensions because of the particle-antiparticle symmetry. The nonrelativistic limit of our theory is in agreement with the nonrelativistic time-of-arrival theory. By comparing the time-of-arrival operator with the Hamiltonian operator of a free Dirac particle, one can show a duality between position space and momentum space.

Zhi-Yong Wang; Cai-Dong Xiong

2007-01-17

15

Fast method to calculate tsunami arrival times  

NASA Astrophysics Data System (ADS)

Exact arrival time of tsunami wave at coast or/and sensor is among important parameters for tsunami risk mitigation. Among the existing methods we mention: simulation of synthetic tsunami wave propagation from the given source; permanent data check at sensor system. Both approaches require extended CPU time or data transfer. Here we suggest alternative method based only on kinematics computation. The method is based on kinematic calculation of tsunami wave front line. Precise algorithms to move the points at the front line and, in case of necessity, to add new points, have been proposed. To start with, this method was successfully tested in an area with constant depth. Then the model bathymetry with parabolic and sloping bottom relief, in which cases exact analytical solutions are available, were studied. New algorithm was proved to be precise. The method gives possibility to compute not only tsunami travel times but also the wave rays. Tsunami amplitude can be estimated by wave-ray's divergence and depth change along wave route. The wave amplitude was estimated and then compared to results of numerical tests, obtained within the shallow-water numerical modeling of tsunami propagation using the MOST software package. For the model (slope-like) bathymetry the results differs by only a few percent. The advantage of proposed method is rapidness and low computer resources requirement.

Lavrentyev, Mikhail; Romanenko, Alexey; Marchuk, Andery; Vassilyev, George

2014-05-01

16

Acceleration of stable TTI P-wave reverse-time migration with GPUs  

NASA Astrophysics Data System (ADS)

When a pseudo-acoustic TTI (tilted transversely isotropic) coupled wave equation is used to implement reverse-time migration (RTM), shear wave energy is significantly included in the migration image. Because anisotropy has intrinsic elastic characteristics, coupling P-wave and S-wave modes in the pseudo-acoustic wave equation is inevitable. In RTM with only primary energy or the P-wave mode in seismic data, the S-wave energy is regarded as noise for the migration image. To solve this problem, we derive a pure P-wave equation for TTI media that excludes the S-wave energy. Additionally, we apply the rapid expansion method (REM) based on a Chebyshev expansion and a pseudo-spectral method (PSM) to calculate spatial derivatives in the wave equation. When REM is incorporated with the PSM for the spatial derivatives, wavefields with high numerical accuracy can be obtained without grid dispersion when performing numerical wave modeling. Another problem in the implementation of TTI RTM is that wavefields in an area with high gradients of dip or azimuth angles can be blown up in the progression of the forward and backward algorithms of the RTM. We stabilize the wavefields by applying a spatial-frequency domain high-cut filter when calculating the spatial derivatives using the PSM. In addition, to increase performance speed, the graphic processing unit (GPU) architecture is used instead of traditional CPU architecture. To confirm the degree of acceleration compared to the CPU version on our RTM, we then analyze the performance measurements according to the number of GPUs employed.

Kim, Youngseo; Cho, Yongchae; Jang, Ugeun; Shin, Changsoo

2013-03-01

17

Upper mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone - results from teleseismic P-wave travel time tomography  

NASA Astrophysics Data System (ADS)

Structure and dynamics of the upper mantle is important in understanding timing and mechanisms shaping prensent day topography and near surface geology. Debate persists regarding the geological age of the Scandes Mountains. We contribute by imaging upper mantle structure beneath southern Scandinavia using teleseismic P-wave travel time tomography (P-tomography). We include data from mobile stations deployed in projects CALAS, CENMOVE, MAGNUS, SCANLIPS and Tor. Permanent stations included are those available from the University of Uppsala, NORSAR and GEUS. P-wave arrival times generally show differences of up to 1 second across the study area. Upper mantle velocities are relatively high in southern Sweden and southern Norway east of the Oslo Graben. Lower velocities are observed in the Norwegian-Danish Basin southwest of the Sorgenfrei-Tornquist Zone(STZ) and in the southwestern part of Norway. We interpret the southwestern boundary of thick Baltic Shield lithosphere where we observe the highest horizontal P-wave velocity gradient. Thus, we find the boundary of thick lithosphere to more or less coinside with the STZ in the southeastern part of the study area, extending from southern Sweden into the northern part of Jutland. From here it turns north, passing through the Oslo Graben area to about 60°N then turning northwest, approaching the Norwegian west coast around 65°N. Thus, as compared to Baltic Shield, upper mantle velocity is significantly reduced beneath deep sedimentary basins of Denmark and northern Germany.

Medhus, Anna Bondo; Balling, Niels; Holm Jacobsen, Bo; England, Richard W.; Kind, Rainer; Shomali, Zaher Hossein; Weidle, Christian; Gregersen, Søren; Voss, Peter; Thybo, Hans

2010-05-01

18

Path Integral Analysis of Arrival Times with a Complex Potential  

E-print Network

A number of approaches to the arrival time problem employ a complex potential of a simple step function type and the arrival time distribution may then be calculated using the stationary scattering wave functions. Here, it is shown that in the Zeno limit (in which the potential becomes very large), the arrival time distribution may be obtained in a clear and simple way using a path integral representation of the propagator together with the path decomposition expansion (in which the propagator is factored across a surface of constant time). This method also shows that the same result is obtained for a wide class of complex potentials.

J. J. Halliwell

2008-01-28

19

Time-of-arrival probabilities for general particle detectors  

E-print Network

We develop a general framework for the construction of probabilities for the time of arrival in quantum systems. The time of arrival is identified with the time instant when a transition in the detector's degrees of freedom takes place. Thus, its definition is embedded within the larger issue of defining probabilities with respect to time for general quantum transitions. The key point in our analysis is that we manage to reduce the problem of defining a quantum time observable to a mathematical model where time is associated to a transition from a subspace of the Hilbert space of the total system to its complementary subspace. This property makes it possible to derive a general expression for the probability for the time of transition, valid for any quantum system, with the only requirement that the time of transition is correlated with a definite macroscopic record. The framework developed here allows for the consideration of any experimental configuration for the measurement of the time of arrival and it also applies to relativistic systems with interactions described by quantum field theory. We use the method in order to describe time-of-arrival measurements in high-energy particle reactions and for a rigorous derivation of the time-integrated probabilities in particle oscillations.

Charis Anastopoulos; Ntina Savvidou

2012-05-12

20

A new pulse arrival-time recording system  

SciTech Connect

We describe a new pulse arrival-time recording system that is being developed at Los Alamos. The new PATRM/PCI (Pulse Arrival-Time Recording Module/Peripheral Component Interconnect) has had several features added. These features enhance our time-correlation measurement capabilities. By applying the latest advances in electronics and computer technology we are able to increase capability over existing instrumentation while lowering the per channel cost. The modular design approach taken allows easy configuration of both small and large systems.

Arnone, G.J.

1996-12-31

21

Parameters for arrival time distribution of air shower particles  

NASA Astrophysics Data System (ADS)

Several parameters which could be used to describe the arrival time distribution of extensive air shower (EAS) particles have been discussed according to their relations with core distance and the fluctuations. Among these parameters, ? is considered to be better than the others when applied to Linsley Effect.

Dai, Hongyue; W, Hazen; E, Hazen

1988-09-01

22

Parameters for arrival time distribution of air shower particles  

Microsoft Academic Search

Several parameters which could be used to describe the arrival time distribution of extensive air shower (EAS) particles have been discussed according to their relations with core distance and the fluctuations. Among these parameters, tau is considered to be better than the others when applied to Linsley Effect. Bibtex entry for this abstract Preferred format for this abstract (see Preferences)

Hongyue Dai; Hazen W; Hazen E

1988-01-01

23

Quantum-classical comparison: arrival times and statistics  

NASA Astrophysics Data System (ADS)

Classical and quantum scattering of a non-Gaussian wave packet by a rectangular barrier is studied in terms of arrival times to a given detector location. A classical wave equation, proposed by N Rosen (1964 Am. J. Phys. 32 377), is used to study the corresponding classical dynamics. Mean arrival times are then computed and compared for different values of initial wave packet parameters and barrier width. The agreement is improved in the large mass limit as one expects. A short comment on the possibility of generalization of Rosen?s proposal to a two-body system is given. Differences in distributions of particles obeying different statistics are studied by considering a system composed of two free particles.

Mousavi, S. V.; Miret-Artés, S.

2015-02-01

24

Empirical estimation of the arrival time of ICME Shocks  

NASA Astrophysics Data System (ADS)

Empirical estimation of the arrival time of ICME Shocks Mosalam Shaltout1 ,M.Youssef 1and R.Mawad2 1 National Research Institute of Astronomy and Geophysics (NRIAG) ,Helwan -Cairo-Egypt Email: mosalamshaltout@hotmail.com 2 Faculty of Science-Monifiia University-Physics Department-Shiben Al-Koum -Monifiia-Egypt We are got the Data of the SSC events from Preliminary Reports of the ISGI (Institut de Physique du Globe, France) .Also we are selected the same CME interval 1996-2005 from SOHO/LASCO/C2.We have estimated the arrival time of ICME shocks during solar cycle 23rd (1996-2005), we take the Sudden storm commencement SSC as a indicator of the arrival of CMEs at the Earth's Magnetosphere (ICME).Under our model ,we selected 203 ICME shock-SSC associated events, we got an imperial relation between CME velocity and their travel time, from which we obtained high correlation between them, R=0.75.

Shaltout, Mosalam

25

Current status of CME/shock arrival time prediction  

NASA Astrophysics Data System (ADS)

of the major solar transients, coronal mass ejections (CMEs) and their related interplanetary shocks have severe space weather effects and become the focus of study for both solar and space scientists. Predicting their evolutions in the heliosphere and arrival times at Earth is an important component of the space weather predictions. Various kinds of models in this aspect have been developed during the past decades. In this paper, we will present a view of the present status (during Solar Cycle 24 in 2014) of the space weather's objective to predict the arrival of coronal mass ejections and their interplanetary shock waves at Earth. This status, by implication, is relevant to their arrival elsewhere in the solar system. Application of this prediction status is clearly appropriate for operational magnetospheric and ionospheric situations including A - > B - > C…solar system missions. We review current empirical models, expansion speed model, drag-based models, physics-based models (and their real-time prediction's statistical experience in Solar Cycle 23), and MHD models. New observations in Solar Cycle 24, including techniques/models, are introduced as they could be incorporated to form new prediction models. The limitations of the present models and the direction of further development are also suggested.

Zhao, Xinhua; Dryer, Murray

2014-07-01

26

Arrival timing and seasonal reproductive performance in a long-distance migratory landbird  

Microsoft Academic Search

The date when a landbird migrant arrives on its breeding grounds may have reproductive consequences. Generally, early arriving individuals begin breeding earlier and consequently experience greater seasonal reproductive performance. Here, we describe relationships between arrival timing and seasonal reproductive performance in the American redstart ( Setophaga ruticilla), a long-distance passerine migrant, arriving at northerly breeding grounds in Michigan’s eastern Upper

Robert J. Smith; Frank R. Moore

2005-01-01

27

Arrival timing and seasonal reproductive performance in a long- distance migratory landbird  

Microsoft Academic Search

The date when a landbird migrant arrives on its breeding grounds may have reproductive consequences. Generally, early arriving individuals begin breeding earlier and consequently experience greater seasonal reproductive performance. Here, we describe relationships between arrival timing and seasonal reproductive performance in the American redstart (Setophaga ruticilla), a long-distance passerine migrant, arriving at northerly breeding grounds in Michigan s eastern Upper

Robert J. Smith; Frank R. Moore

2004-01-01

28

Rounding of Arrival and Departure Times in Travel Surveys: An Interpretation in Terms of Scheduled Activities  

Microsoft Academic Search

In travel surveys most respondents apply rounding of departure and arrival times to multiples of 5, 15 and 30 minutes: in the annual Dutch travel survey about 85-95 percent of all reported times are 'round' ones. We estimate rounding models for departure and arrival times. The model allows one to compute the probability that a reported arrival time m (say

Piet Rietveld

2001-01-01

29

ConcepTest: P Wave Arrival  

NSDL National Science Digital Library

Examine the seismogram below that shows a 26-minute long record of the seismic waves from the 1906 San Francisco earthquake as it was received by a seismograph station in Germany, over 14,000 km away. Which letter ...

30

Arrival timing and hematological parameters in Gray Catbirds ( Dumetella carolinensis )  

Microsoft Academic Search

Early arrival at the breeding grounds for migratory birds is associated with greater reproductive success. According to the\\u000a condition-dependent arrival hypothesis, only those individuals in superior physiological condition are able to bear the costs\\u000a (e.g., poor environmental conditions, limited food availability) of early arrival. Condition has usually been measured in\\u000a terms of energy reserves or mass but other physiological measures

Margret I. HatchRobert; Robert J. Smith; Jennifer C. Owen

2010-01-01

31

Early magnitude estimation for the MW7.9 Wenchuan earthquake using progressively expanded P-wave time window  

NASA Astrophysics Data System (ADS)

More and more earthquake early warning systems (EEWS) are developed or currently being tested in many active seismic regions of the world. A well-known problem with real-time procedures is the parameter saturation, which may lead to magnitude underestimation for large earthquakes. In this paper, the method used to the MW9.0 Tohoku-Oki earthquake is explored with strong-motion records of the MW7.9, 2008 Wenchuan earthquake. We measure two early warning parameters by progressively expanding the P-wave time window (PTW) and distance range, to provide early magnitude estimates and a rapid prediction of the potential damage area. This information would have been available 40 s after the earthquake origin time and could have been refined in the successive 20 s using data from more distant stations. We show the suitability of the existing regression relationships between early warning parameters and magnitude, provided that an appropriate PTW is used for parameter estimation. The reason for the magnitude underestimation is in part a combined effect of high-pass filtering and frequency dependence of the main radiating source during the rupture process. Finally we suggest only using Pd alone for magnitude estimation because of its slight magnitude saturation compared to the ?c magnitude.

Peng, Chaoyong; Yang, Jiansi; Zheng, Yu; Xu, Zhiqiang; Jiang, Xudong

2014-10-01

32

Early magnitude estimation for the MW7.9 Wenchuan earthquake using progressively expanded P-wave time window.  

PubMed

More and more earthquake early warning systems (EEWS) are developed or currently being tested in many active seismic regions of the world. A well-known problem with real-time procedures is the parameter saturation, which may lead to magnitude underestimation for large earthquakes. In this paper, the method used to the MW9.0 Tohoku-Oki earthquake is explored with strong-motion records of the MW7.9, 2008 Wenchuan earthquake. We measure two early warning parameters by progressively expanding the P-wave time window (PTW) and distance range, to provide early magnitude estimates and a rapid prediction of the potential damage area. This information would have been available 40?s after the earthquake origin time and could have been refined in the successive 20?s using data from more distant stations. We show the suitability of the existing regression relationships between early warning parameters and magnitude, provided that an appropriate PTW is used for parameter estimation. The reason for the magnitude underestimation is in part a combined effect of high-pass filtering and frequency dependence of the main radiating source during the rupture process. Finally we suggest only using Pd alone for magnitude estimation because of its slight magnitude saturation compared to the ?c magnitude. PMID:25346344

Peng, Chaoyong; Yang, Jiansi; Zheng, Yu; Xu, Zhiqiang; Jiang, Xudong

2014-01-01

33

Early magnitude estimation for the MW7.9 Wenchuan earthquake using progressively expanded P-wave time window  

PubMed Central

More and more earthquake early warning systems (EEWS) are developed or currently being tested in many active seismic regions of the world. A well-known problem with real-time procedures is the parameter saturation, which may lead to magnitude underestimation for large earthquakes. In this paper, the method used to the MW9.0 Tohoku-Oki earthquake is explored with strong-motion records of the MW7.9, 2008 Wenchuan earthquake. We measure two early warning parameters by progressively expanding the P-wave time window (PTW) and distance range, to provide early magnitude estimates and a rapid prediction of the potential damage area. This information would have been available 40?s after the earthquake origin time and could have been refined in the successive 20?s using data from more distant stations. We show the suitability of the existing regression relationships between early warning parameters and magnitude, provided that an appropriate PTW is used for parameter estimation. The reason for the magnitude underestimation is in part a combined effect of high-pass filtering and frequency dependence of the main radiating source during the rupture process. Finally we suggest only using Pd alone for magnitude estimation because of its slight magnitude saturation compared to the ?c magnitude. PMID:25346344

Peng, Chaoyong; Yang, Jiansi; Zheng, Yu; Xu, Zhiqiang; Jiang, Xudong

2014-01-01

34

S-P wave travel time residuals and lateral inhomogeneity in the mantle beneath Tibet and the Himalaya  

NASA Technical Reports Server (NTRS)

S-P wave travel time residuals were measured in earthquakes in Tibet and the Himalaya in order to study lateral inhomogeneities in the earth's mantle. Average S-P residuals, measured with respect to Jeffrey-Bullen (J-B) tables for 11 earthquakes in the Himalaya are less than +1 second. Average J-B S-P from 10 of 11 earthquakes in Tibet, however, are greater than +1 second even when corrected for local crustal thickness. The largest values, ranging between 2.5 and 4.9 seconds are for five events in central and northern Tibet, and they imply that the average velocities in the crust and upper mantle in this part of Tibet are 4 to 10 percent lower than those beneath the Himalaya. On the basis of the data, it is concluded that it is unlikely that a shield structure lies beneath north central Tibet unless the S-P residuals are due to structural variations occurring deeper than 250 km.

Molnar, P.; Chen, W.-P.

1984-01-01

35

Theoretical P-Wave Travel Times, Magnitude 6.7 Island of Hawaii, Hawaii, Sunday, October 15, 2006 at 17:07:49 UTC  

NSDL National Science Digital Library

This page from the USGS displays the predicted travel times of the P-Waves originating from the 6.7 magnitude earthquake that struck near Puako, HI on October 15th, 2006. There is a table of data as well as the map visualization.

Program, Earthquake H.; Usgs

36

Semi-coherent time of arrival estimation using regression.  

PubMed

Time of arrival (ToA) estimation is essential for many types of remote sensing applications including radar, sonar, and underground exploration. The standard method for ToA estimation employs a matched filter for computing the maximum likelihood estimator (MLE) for ToA. The accuracy of the MLE decreases rapidly whenever the amount of noise in a received signal rises above a certain threshold. This well-known threshold effect is unavoidable in several important applications due to various limitations on the power and the spectrum of a narrowband source pulse. A measurement performed in the presence of the threshold effect employs a receiver which operates in the semi-coherent state. Therefore, the conventional methods assuming a coherent state receiver should be adapted to the semi-coherent case. In this paper, a biosonar-inspired method for the semi-coherent ToA estimation is described. The method abandons the exploration of an echo signal by a single matched filter in favor of the analysis by multiple phase-shifted unmatched filters. Each phase-shifted unmatched filter gives rise to a biased ToA estimator. The described method uses regression for combining these estimators into a single unbiased ToA estimator that outperform the MLE in the presence of the threshold effect. PMID:22894206

Apartsin, Alexander; Cooper, Leon N; Intrator, Nathan

2012-08-01

37

Improvement in estimation of time of arrival (TOA) from timing advance (TA)  

Microsoft Academic Search

Wireless systems reporting TOA (time of arrival), the propagation time from the mobile station (MS) to the base station (BS), may use this information to assist with automatic location identification (ALI). The TA (timing advance), used in TDMA systems, may be used as an approximation for TOA. The MS\\/BS system measures TOA with a certain raw measurement error. The TA

George P. Yost; Shankari Panchapakesan

1998-01-01

38

A Fast-Time Simulation Tool for Analysis of Airport Arrival Traffic  

NASA Technical Reports Server (NTRS)

The basic objective of arrival sequencing in air traffic control automation is to match traffic demand and airport capacity while minimizing delays. The performance of an automated arrival scheduling system, such as the Traffic Management Advisor developed by NASA for the FAA, can be studied by a fast-time simulation that does not involve running expensive and time-consuming real-time simulations. The fast-time simulation models runway configurations, the characteristics of arrival traffic, deviations from predicted arrival times, as well as the arrival sequencing and scheduling algorithm. This report reviews the development of the fast-time simulation method used originally by NASA in the design of the sequencing and scheduling algorithm for the Traffic Management Advisor. The utility of this method of simulation is demonstrated by examining the effect on delays of altering arrival schedules at a hub airport.

Erzberger, Heinz; Meyn, Larry A.; Neuman, Frank

2004-01-01

39

A COMPARISON OF COLLAPSING AND PRECISE ARRIVAL-TIME MAPPING OF MICROSEISMICITY  

SciTech Connect

In this paper they compare the improvements in microseismic location images obtained using precise arrival times with that obtained by the collapsing technique. They first collapse the initial locations for a hydraulic-fracture data set from the Carthage Cotton Valley gas field, they then use the precise-arrival-time locations as measure for the effectiveness of the collapsing. Finally, they examine the changes when applying collapsing to the precise-arrival-time locations.

RUTLEDGE, JAMES T. [Los Alamos National Laboratory; JONES, ROB H. [Los Alamos National Laboratory

2007-01-05

40

P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model  

NASA Astrophysics Data System (ADS)

P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, that constitute alpine rock walls, has been denied in prior studies. These explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill, i.e. water, air and ice. In existing models, no velocity increase is expected for low-porosity bedrock. We postulate, that mixing laws apply for high-porosity rocks, but freezing in confined space in low-porosity bedrock also alters physical rock matrix properties. In the laboratory, we measured p-wave velocities of 22 decimeter-large low-porosity (<6 %) metamorphic, magmatic and sedimentary permafrost rock samples with a natural texture (>100 micro-fissures) from 25 °C to -15 °C in 0.3 °C increments close to the freezing point. P-wave velocity increases by 7-78 % when freezing parallel to cleavage/bedding and matrix velocity increases from 5-59 % coincident to an anisotropy decrease in most samples. The expansion of rigid bedrock upon freezing is restricted and ice pressure will increase matrix velocity and decrease anisotropy while changing velocities of the pore infill are insignificant. Here, we present a modified Timur's 2-phase equation implementing changes in matrix velocity dependent on lithology and demonstrate the physical basis for refraction seismics in low-porosity bedrock.

Draebing, D.; Krautblatter, M.

2012-02-01

41

P-wave velocity changes in freezing hard low-porosity rocks: a laboratory-based time-average model  

NASA Astrophysics Data System (ADS)

P-wave refraction seismics is a key method in permafrost research but its applicability to low-porosity rocks, which constitute alpine rock walls, has been denied in prior studies. These studies explain p-wave velocity changes in freezing rocks exclusively due to changing velocities of pore infill, i.e. water, air and ice. In existing models, no significant velocity increase is expected for low-porosity bedrock. We postulate, that mixing laws apply for high-porosity rocks, but freezing in confined space in low-porosity bedrock also alters physical rock matrix properties. In the laboratory, we measured p-wave velocities of 22 decimetre-large low-porosity (< 10%) metamorphic, magmatic and sedimentary rock samples from permafrost sites with a natural texture (> 100 micro-fissures) from 25 °C to -15 °C in 0.3 °C increments close to the freezing point. When freezing, p-wave velocity increases by 11-166% perpendicular to cleavage/bedding and equivalent to a matrix velocity increase from 11-200% coincident to an anisotropy decrease in most samples. The expansion of rigid bedrock upon freezing is restricted and ice pressure will increase matrix velocity and decrease anisotropy while changing velocities of the pore infill are insignificant. Here, we present a modified Timur's two-phase-equation implementing changes in matrix velocity dependent on lithology and demonstrate the general applicability of refraction seismics to differentiate frozen and unfrozen low-porosity bedrock.

Draebing, D.; Krautblatter, M.

2012-10-01

42

Uppermost mantle P wave velocities beneath Turkey and Iran  

SciTech Connect

The uppermost mantle P wave velocities beneath Turkey and Iran were estimated by applying the conventional travel time-distance relation method to arrival times of well located earthquakes recorded at a few stations. The average uppermost mantle P wave velocity under Turkey is estimated from two stations of the World Wide Standardized Seismograph Network (WWSSN), Istanbul and Tabriz. The data are consistent with a crust of uniform, but poorly determined, thickness and an uppermost mantle P wave velocity of 7.73 +- 0.08 km/s. This velocity is very similar to that for the Aegean Sea and suggests that its structure could be closely related to that beneath Turkey. For Iran, the results calculated from travel times to three WWSSN stations, Meshed, Shiraz, and Tabriz, can be explained by a crust dipping toward the south-southeast at about 1/sup 0/ with an uppermost mantle P wave velocity of 8.0 +- 0.1 km/s. If the crustal thickness were 34 km in the north it would reach about 49 km in the south. Based on these uppermost mantle velocities, the temperature at Moho beneath Turkey is probably close to the melting temperature of peridotite but that beneath Iran is probably lower.

Chen, C.; Chen, W.; Molnar, P.

1980-01-01

43

Calibration of sonobuoy compass via arrival time inversion  

Microsoft Academic Search

Onboard magnetic compasses allow sonobuoys to measure their orientation and form beams along true headings. Compass failure means true array heading is unknown and the buoy's beams cannot be used for target localization and tracking. We describe a method for recovering buoy orientation by inverting the pattern of signal arrivals at the individual hydrophones, and present results using data recorded

K. J. Delaney; J. M. Alsup; P. Sullivan

2003-01-01

44

Grid travel{time tracing: second{order method for the rst arrivals in smooth media  

E-print Network

Grid travel{time tracing: second{order method for the #12;rst arrivals in smooth media Lud#20;ek{arrival travel times on a rectan- gular grid of points is proposed. The new proposed method is of second{order accuracy. This means that the error of the calculated travel time is proportional to the second power

Cerveny, Vlastislav

45

Grid travel{time tracing: second{order method for the rst arrivals in smooth media *  

E-print Network

Grid travel{time tracing: second{order method for the #12;rst arrivals in smooth media * Lud#20;ek the #12;rst{arrival travel times on a rectangular grid of points is proposed. Whereas the former "#12;nite is of the second{order accu- racy. It means that the relative propagation{velocity error of calculated travel time

Cerveny, Vlastislav

46

Arrival timing in subadult and adult Black Redstart males: competition-dependent behaviour?  

Microsoft Academic Search

The different arrival times of 1-year-old and older males is a widely recognised phenomenon in most migrating passerines. The converse pattern, i.e. the yearlings arriving at the breeding grounds at the same time as adults, has been reported only exceptionally. Two hypotheses have been formulated to explain the delayed arrival of yearling males: investment reduction, and energetic constraint hypotheses, respectively.

L. Schwarzová; P. Štros; D. Frynta; R. Fuchs

2010-01-01

47

Distortions of Experimental Muon Arrival Time Distributions of Extensive Air Showers by the Observation Conditions  

E-print Network

Event-by-event measured arrival time distributions of Extensive Air Shower (EAS) muons are affected and distorted by various interrelated effects which originate from the time resolution of the timing detectors, from fluctuations of the reference time and the number (multiplicity) of detected muons spanning the arrival time distribution of the individual EAS events. The origin of these effects is discussed, and different correction procedures, which involve detailed simulations, are proposed and illustrated. The discussed distortions are relevant for relatively small observation distances (R < 200 m) from the EAS core. Their significance decreases with increasing observation distance and increasing primary energies. Local arrival time distributions which refer to the observed arrival time of the first local muon prove to be less sensitive to the mass of the primary. This feature points to the necessity of arrival time measurements with additional information on the curvature of the EAS disk.

R. Haeusler; A. F. Badea; H. Rebel; I. M. Brancus; J. Oehlschlaeger

2001-10-17

48

Localization of a noisy broadband surface target using time differences of multipath arrivals.  

PubMed

Previous studies [Tiemann et al., J. Acoust. Soc. Am. 120, 2355-2365 (2006)] have reported the localization of marine mammals in 3-D from their clicks using multipath arrivals. Bathymetric variations were advantageously used to predict multipath arrival times with a raytracer. These arrivals are directly discernible from the time series for impulsive sources, such as whale clicks, but extension of the method to continuous broadband sources presents additional complications. By pulse compressing noise emitted from a small boat using two hydrophones, the hyperbolic direct-arrival ambiguity can be refined in both range and bearing. Acoustic-derived results are validated with target GPS measurements. PMID:23862911

Gebbie, John; Siderius, Martin; McCargar, Reid; Allen, John S; Pusey, Grant

2013-07-01

49

Primary energy spectrum of cosmic rays obtained by arrival time spread of particles in EAS  

Microsoft Academic Search

The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) by using compact arrays. According to J. Linsley, the primary energy of EAS can be estimated from the spread of the arrival times of EAS particles, even with a small array. A shift register system for clocking the arrival times was installed

M. Okita; T. Wada; Y. Yamashita; K. Okei; T. Morita; S. Liang; N. Takahashi; A. Iyono; H. Matsumoto; C. Noda; M. Masuda; I. Yamamoto; M. Kohata; N. Ochi; T. Nakatsuka; S. Tsuji

2008-01-01

50

Search for correlations in the arrival times of extensive air showers and Weber gravitational waves  

SciTech Connect

In an experimental search for correlations in the arrival times of extensive air showers and Weber gravitational waves the only evidence for correlations was found in the occurrence of double pairs of coincidences. The probability of observing such pairs in this experiment for random uncorrelated arrival times was calculated to be less than 1%. (LBS)

Kanofsky, A.; Tutin, M.; Kanofsky, P.

1974-01-26

51

Forecasting solar wind structures and shock arrival times using an ensemble of models  

Microsoft Academic Search

Forecasting the time of arrival at Earth of interplanetary shocks following solar metric type II activity is an important first step in the establishment of an operational space weather prediction system. The quality of the forecasts is of utmost importance. The performances of the shock time of arrival (STOA) and interplanetary shock propagation models (ISPM) were previously evaluated by Smith

C. D. Fry; M. Dryer; Z. Smith; W. Sun; C. S. Deehr; S.-I. Akasofu

2003-01-01

52

Impact of time-correlated arrivals on the performance of backpressure-based stochastic network control  

Microsoft Academic Search

In this paper, we consider the backpressure-based control for wireless multihop networks with time-correlated arrivals. The arrival process considered in this work is fairly general in the sense that it may exhibit long-range dependence depending on the asymptotic shape of the autocorrelation func- tion. We first show that the original backpressure policy is still throughput-optimal even with correlated arrivals if

Jeongho Jeon; Anthony Ephremides

2011-01-01

53

Measurement of X-ray photon energy and arrival time using a silicon drift detector  

NASA Astrophysics Data System (ADS)

Detecting the X-ray emission of pulsars and obtaining the photons' time of arrival are the foundational steps in autonomous navigation via X-ray pulsar measurement. The precision of a pulse's time of arrival is mainly determined by the precision of photon arrival time measurement. In this work, a silicon drift detector is used to measure photon energy and arrival time. The measurement system consists of a signal detector, a processing unit, a signal acquisition unit and a data receiving unit. This system acquires the energy resolution and arrival time information of photons. In particular, background noise with different energies disturbs pulse profile forming, the system can also achieve a high signal-to-noise ratio profile. Ground test results show that this system can be applied in autonomous navigation based on X-ray pulsar measurement.

Liu, Li; Yu, Hai; Zheng, Wei

2014-03-01

54

Arrival times for dissipative, nonlinear second-sound waves in solids  

NASA Astrophysics Data System (ADS)

We extend our original analysis begun in Tarkenton et al. [Phys. Rev. B 49, 11 794 (1994)] to include dissipative effects that are important in real cryogenic systems where nonlinear second sound exists. We present results concerning arrival times of thermal pulses propagated in cryogenic crystals, namely the behavior of the arrival times as a function of pulse amplitude. These arrival times show some surprising effects due to competing nonlinear terms: after decreasing with increasing amplitude, as one would expect, the arrival times start to lengthen due to nonlinear effects and finally saturate at a level slightly above the shortest arrival times. All these surprising effects arise from competing nonlinear terms in the expression for the wave speed. We finally relate these results to the experiment we proposed in our original paper.

Tarkenton, G. M.; Cramer, M. S.

1995-07-01

55

Travel-time residuals of teleseismic P-waves at the Rodriguez Triple Junction in the Indian Ocean using ocean-bottom seismometers  

Microsoft Academic Search

We conducted three weeks of seismic observations at the Rodriguez Triple Junction (RTJ) in the Indian Ocean using 18 ocean-bottom seismometers over an area of 90km × 90km. We identified six teleseismic events and obtained significant anomalies in the relative travel-time residuals of the teleseismic P-waves. The residuals are positive at the RTJ, the northern part of the Southeast Indian

Kei Katsumata; Junzo Kasahara; Naoshi Hirata; Ryota Hino; Narumi Takahashi; Mayumi Sekine; Seiichi Miura; Sadayuki Koresawa

1996-01-01

56

Timing of arrival from spring migration is associated with flight performance in the migratory barn swallow.  

PubMed

Timing of arrival at the breeding grounds by migratory birds affects their mating success and access to superior resources, thus being a major factor associated with fitness. Much empirical work has been devoted to investigate the condition dependence of arrival sequence of migrants and characteristics of individuals that influence arrival time from migration. Surprisingly, there are no studies examining the relationship between flight performance of individual birds and their arrival time. I investigated the relative importance of direct effects of short-term flight performance, age, body condition and the degree of sexual ornamentation (tail length) on timing of spring arrival in the barn swallow (Hirundo rustica), a long-distance trans-equatorial passerine migrant. I evaluated short-term flight performance (a composite variable comprising flight manoeuvrability, velocity and acceleration) in a standardised manner using flight tunnels. Short-term flight performance was a significant and important predictor of spring arrival date. Furthermore, locomotion predicted arrival date of individual birds independently of morphological variables-the degree of sexual ornamentation (the length of the tail) and wing aspect ratio and body condition. I discuss the possible role short-term flight performance may have in determining migratory performance. This is the first time flight performance has been shown to be associated with timing of arrival from migration in a migratory bird. PMID:23293424

Matyjasiak, Piotr

2013-01-01

57

Search for correlations in the arrival times of extensive air showers and Weber gravitational waves  

SciTech Connect

We have searched for correlations in the arrival times of extensive air showers and Weber gravitational waves. Extensive air showers with energies greater than 5 x 10/sup 14/ eV were detected at the Jadwin Physics Building, Princeton, New Jersey, from March to November 1971. The apparatus was not sensitive to cosmic rays coming directly from the galactic center. The shower- arrival times were compared to the arrival times of Weber' s gravitational waves occurring over the same period. Undelayed and delayed time coincidences were checked for in the analysis, as well as possible time-delay dispersion effects. (auth)

Kanofsky, A.; Tutin, M.; Kanofsky, P.

1973-12-15

58

Time-of-arrival estimation by UWB radios with low sampling rate and clock drift calibration$  

E-print Network

-of-arrival Clock drift Stroboscopic sampling a b s t r a c t In this paper, we propose a time-of-arrival (TOA and is robust against clock drift. Low-rate stroboscopic sampling, which can achieve an equivalent sampling rate error sources in TOA estimation with stroboscopic sampling IR-UWB systems. Taking the drift into account

Leus, Geert

59

Effect of time window length for maximum amplitude estimation on P wave magnitude: application for Earthquake Early Warning  

Microsoft Academic Search

Earthquake early warning, EEW, aims at issuing the warning of strong ground shaking before its arrival by analyzing seismic waveform data obtained near the hypocenter. Rapid estimation is important as well as precise anticipation of strong shaking. At present, Japan Meteorological Agency (JMA) anticipates the strong shaking using magnitude, attenuation relation and site amplification factors, and the anticipation is performed

M. Hoshiba; K. Iwakiri; K. Ohtake

2009-01-01

60

A review of the decoherent histories approach to the arrival time problem in quantum theory  

E-print Network

We review recent progress in understanding the arrival time problem in quantum mechanics, from the point of view of the decoherent histories approach to quantum theory. We begin by discussing the arrival time problem, focussing in particular on the role of the probability current in the expected classical solution. After a brief introduction to decoherent histories we review the use of complex potentials in the construction of appropriate class operators. We then discuss the arrival time problem for a particle coupled to an environment, and review how the arrival time probability can be expressed in terms of a POVM in this case. We turn finally to the question of decoherence of the corresponding histories, and we show that this can be achieved for simple states in the case of a free particle, and for general states for a particle coupled to an environment.

James M Yearsley

2010-12-12

61

The prediction of bus arrival time using Automatic Vehicle Location Systems data  

E-print Network

THE PREDICTION OF BUS ARRIVAL TIME USING AUTOMATIC VEHICLE LOCATION SYSTEMS DATA A Dissertation by RAN HEE JEONG Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of DOCTOR OF PHILOSOPHY December 2004 Major Subject: Civil Engineering THE PREDICTION OF BUS ARRIVAL TIME USING AUTOMATIC VEHICLE LOCATION SYSTEMS DATA A Dissertation by RAN HEE JEONG Submitted to Texas...

Jeong, Ran Hee

2005-02-17

62

Arrival-time fluctuations of coherent reflections from surface gravity water waves.  

PubMed

Arrival time fluctuations of coherent reflections from surface gravity waves are examined. A two-dimensional ray model with an evolving rough sea surface is used to explain the mechanism and formation of the deterministic striation patterns due to the surface reflection. Arrival time predictions from the ray model match qualitatively well with the measurements from bidirectional acoustic transmissions in a water depth of 100?m. PMID:24815293

Badiey, Mohsen; Eickmeier, Justin; Song, Aijun

2014-05-01

63

Spin-dependent observable effect for free particles using the arrival time distribution  

SciTech Connect

The mean arrival time of free particles is computed using the quantum-mechanical probability current. This is uniquely determined in the nonrelativistic limit of Dirac equation, although the Schroedinger probability current has an inherent nonuniqueness. Since the Dirac probability current contains a spin-dependent term, an arrival time distribution based on the probability current shows an observable spin-dependent effect, even for free particles. This arises essentially from relativistic quantum dynamics, but persists even in the nonrelativistic regime.

Ali, Md. Manirul; Majumdar, A.S. [S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Calcutta 700098 (India); Home, Dipankar [Department of Physics, Bose Institute, Calcutta 700009 (India); Sengupta, Shyamal [Jadavpur University, Calcutta 700032 (India)

2003-10-01

64

Velocity structure of the crust and upper mantle at the northern group of Kamchatka volcanoes (Based on the travel time of P-waves from volcanic earthquakes)  

NASA Astrophysics Data System (ADS)

The results of a calculation of the P-wave ( V P ) velocity fields are presented on the basis of the method of the reversible wave and the TAU parameter characterizing the V P / V S ratio of seismic waves from the local volcanic earthquakes that occurred at the northern group of Kamchatka volcanoes in 2005-2007. The 3D velocity cross sections were constructed along the SW-NE-trending volcanic group from the Ploskii Tolbachik volcano in the southwest up to the Shiveluch volcano in the northeast. The change of velocity field in time and depth is found. The problems of relating these changes to volcanic activity is reviewed.

Slavina, L. B.; Pivovarova, N. B.; Senyukov, S. L.

2012-12-01

65

A Fast-Time Study of Aircraft Reordering in Arrival Sequencing and Scheduling  

NASA Technical Reports Server (NTRS)

In order to ensure that the safe capacity of the terminal area is not exceeded, Air Traffic Management ATM often places restrictions on arriving flights transitioning from en route airspace to terminal airspace. This restriction of arrival traffic is commonly referred to as arrival flow management, and includes techniques such as metering, vectoring, fix-load balancing, and the imposition of miles-in-trail separations. These restrictions are enacted without regard for the relative priority which airlines may be placing on individual flights based on factors such as crew criticality, passenger connectivity, critical turn times, gate availability, on-time performance, fuel status, or runway preference. The development of new arrival flow management techniques which take into consideration priorities expressed by air carriers will likely reduce the economic impact of ATM restrictions on the airlines and lead to increased airline economic efficiency by allowing airlines to have greater control over their individual arrival banks of aircraft. NASA and the Federal Aviation Administration (FAA) have designed and developed a suite of software decision support tools (DSTs) collectively known as the Center TRACON Automation System (CTAS). One of these tools, the Traffic Management Advisor (TMA) is currently being used at the Fort Worth Air Route Traffic Control Center to perform arrival flow management of traffic into the Dallas/Fort Worth airport (DFW). The TMA is a time-based strategic planning tool that assists Traffic Management Coordinators (TMCs) and En Route Air Traffic Controllers in efficiently balancing arrival demand with airport capacity. The primary algorithm in the TMA is a real-time scheduler which generates efficient landing sequences and landing times for arrivals within about 200 no a. from touchdown. This scheduler will sequence aircraft so that they arrive in a first- come - first-served (FCFS) order. While FCFS sequencing establishes a fair order based on estimated times of arrival, it does not take into account individual airline priorities among incoming flights. NASA is exploring the possibility of allowing airlines to express relative arrival priorities to air traffic management through the development of new CTAS scheduling algorithms which take into consideration airline arrival preferences. The accommodation of airline priorities in arrival sequencing and scheduling would under most circumstances result in a deviation from a "natural" or FCFS arrival order. As a First step toward developing airline influenced sequencing algorithms, an investigation was conducted to determine the feasibility of reordering arrival traffic from a strict FCFS sequence. A fast-time simulation has been developed which allows statistical evaluation of sequencing and scheduling algorithms for arrival traffic at the Dallas/Fort Worth Airport. In contrast to real-time simulation or field tests, which would require on the order of ninety minutes to examine a single traffic rush period, the fast-time simulation allows examination of multiple rush periods in a matter of seconds.

Carr, Greg; Neuman, Frank; Tobias, Leonard (Technical Monitor)

1998-01-01

66

Different motion cues are used to estimate time-to-arrival for frontoparallel and looming trajectories  

PubMed Central

Estimation of time-to-arrival for moving objects is critical to obstacle interception and avoidance, as well as to timing actions such as reaching and grasping moving objects. The source of motion information that conveys arrival time varies with the trajectory of the object raising the question of whether multiple context-dependent mechanisms are involved in this computation. To address this question we conducted a series of psychophysical studies to measure observers’ performance on time-to-arrival estimation when object trajectory was specified by angular motion (“gap closure” trajectories in the frontoparallel plane), looming (colliding trajectories, TTC) or both (passage courses, TTP). We measured performance of time-to-arrival judgments in the presence of irrelevant motion, in which a perpendicular motion vector was added to the object trajectory. Data were compared to models of expected performance based on the use of different components of optical information. Our results demonstrate that for gap closure, performance depended only on the angular motion, whereas for TTC and TTP, both angular and looming motion affected performance. This dissociation of inputs suggests that gap closures are mediated by a separate mechanism than that used for the detection of time-to-collision and time-to-passage. We show that existing models of TTC and TTP estimation make systematic errors in predicting subject performance, and suggest that a model which weights motion cues by their relative time-to-arrival provides a better account of performance. PMID:22056519

Calabro, Finnegan J.; Beardsley, Scott A.; Vaina, Lucia M.

2012-01-01

67

NONNEGATIVE DECONVOLUTION FOR TIME OF ARRIVAL ESTIMATION Yuanqing Lin1  

E-print Network

-based algo- rithms such as MUSIC have proven successful in discrimi- nating the signal subspace from in the time domain as: xi(t) = s(t) hi(t) + i(t), i = 1, 2 (1) where hi(t) are the impulse responses between and temporally uncorre- lated with the source. In an ideal, free-space scenario, the impulse responses between

Saul, Lawrence K.

68

Inter-arrival Times of Goals in Ice Hockey  

Microsoft Academic Search

Previous studies have attempted to model goal scoring in sports such as ice hockey as simple Poisson processes. Others (Thomas, 2006) have shown that events within the game of ice hockey are better modelled as a Semi-Markov process determined by puck possession and location. I demonstrate that a similarly defined Semi-Markov process model is well-suited to describe the times between

Andrew C. Thomas

2007-01-01

69

Scaling Behavior of the First Arrival Time of a Random-Walking Magnetic Domain  

SciTech Connect

We report a universal scaling behavior of the first arrival time of a traveling magnetic domain wall into a finite space-time observation window of a magneto-optical microscope enabling direct visualization of a Barkhausen avalanche in real time. The first arrival time of the traveling magnetic domain wall exhibits a nontrivial fluctuation and its statistical distribution is described by universal power-law scaling with scaling exponents of 1.34 {+-} 0.07 for CoCr and CoCrPt films, despite their quite different domain evolution patterns. Numerical simulation of the first arrival time with an assumption that the magnetic domain wall traveled as a random walker well matches our experimentally observed scaling behavior, providing an experimental support for the random-walking model of traveling magnetic domain walls.

Im, M.-Y.; Lee, S.-H.; Kim, D.-H.; Fischer, P.; Shin, S.-C.

2008-02-04

70

Does winter region affect spring arrival time and body mass of king eiders in northern Alaska?  

USGS Publications Warehouse

Events during the non-breeding season may affect the body condition of migratory birds and influence performance during the following breeding season. Migratory birds nesting in the Arctic often rely on endogenous nutrients for reproductive efforts, and are thus potentially subject to such carry-over effects. We tested whether king eider (Somateria spectabilis) arrival time and body mass upon arrival at breeding grounds in northern Alaska were affected by their choice of a winter region in the Bering Sea. We captured birds shortly after arrival on breeding grounds in early June 2002-2006 at two sites in northern Alaska and determined the region in which individuals wintered using satellite telemetry or stable isotope ratios of head feathers. We used generalized linear models to assess whether winter region explained variation in arrival body mass among individuals by accounting for sex, site, annual variation, and the date a bird was captured. We found no support for our hypothesis that either arrival time or arrival body mass of king eiders differed among winter regions. We conclude that wintering in different regions in the Bering Sea is unlikely to have reproductive consequences for king eiders in our study areas. ?? US Government 2009.

Oppel, S.; Powell, A.N.

2009-01-01

71

Continuous measurement of the arrival times of x-ray photon sequence  

NASA Astrophysics Data System (ADS)

In order to record x-ray pulse profile for x-ray pulsar-based navigation and timing, this paper presents a continuous, high-precision method for measuring arrival times of photon sequence with a common starting point. In this method, a high stability atomic clock is counted to measure the coarse time of arrival photon. A high resolution time-to-digital converter is used to measure the fine time of arrival photon. The coarse times and the fine times are recorded continuously and then transferred to computer memory by way of memory switch. The pulse profile is obtained by a special data processing method. A special circuit was developed and a low-level x-ray pulse profile measurement experiment system was setup. The arrival times of x-ray photon sequence can be consecutively recorded with a time resolution of 500 ps and the profile of x-ray pulse was constructed. The data also can be used for analysis by many other methods, such as statistical distribution of photon events per time interval, statistical distribution of time interval between two photon events, photon counting histogram, autocorrelation and higher order autocorrelation.

Yan, Qiurong; Zhao, Baosheng; Sheng, Lizhi; Liu, Yong'an

2011-05-01

72

Continuous measurement of the arrival times of x-ray photon sequence.  

PubMed

In order to record x-ray pulse profile for x-ray pulsar-based navigation and timing, this paper presents a continuous, high-precision method for measuring arrival times of photon sequence with a common starting point. In this method, a high stability atomic clock is counted to measure the coarse time of arrival photon. A high resolution time-to-digital converter is used to measure the fine time of arrival photon. The coarse times and the fine times are recorded continuously and then transferred to computer memory by way of memory switch. The pulse profile is obtained by a special data processing method. A special circuit was developed and a low-level x-ray pulse profile measurement experiment system was setup. The arrival times of x-ray photon sequence can be consecutively recorded with a time resolution of 500 ps and the profile of x-ray pulse was constructed. The data also can be used for analysis by many other methods, such as statistical distribution of photon events per time interval, statistical distribution of time interval between two photon events, photon counting histogram, autocorrelation and higher order autocorrelation. PMID:21639490

Yan, Qiurong; Zhao, Baosheng; Sheng, Lizhi; Liu, Yong'an

2011-05-01

73

Multi-Mode Lamb Wave Arrival Time Extraction for Improved Tomographic Reconstruction  

SciTech Connect

An ultrasonic signal processing technique is applied to multi-mode arrival time estimation from Lamb waveforms. The basic tool is a simplified time-scale projection called a dynamic wavelet fingerprint (DWFP) which enables direct observation of the variation of features of interest in non-stationary ultrasonic signals. The DWFP technique was used to automatically detect and evaluate each candidate through-transmitted Lamb mode. The area of the dynamic wavelet fingerprint was then used as a feature to distinguish false modes caused by noise and other interference from the true modes of interest. The set of estimated arrival times were then used as inputs for tomographic reconstruction. The Lamb wave tomography images generated with these estimated arrival times were able to indicate different defects in aluminum plates.

Hinders, Mark K.; Hou Jidong; Leonard, Kevin R. [College of William and Mary in Virginia, Applied Science Dept., Williamsburg, VA 23187 (United States)

2005-04-09

74

EFFECTS OF REFRACTION ON ANGLES AND TIMES OF ARRIVAL OF SOLAR RADIO BURSTS  

SciTech Connect

Solar type III and type II radio bursts suffer severe bending and group delay due to refraction while escaping from the source where the refractive index {mu} can be as low as {approx}0 to the observer where {mu} {approx} 1. These propagation effects can manifest themselves as errors in the observed directions and times of arrival at the telescope. We describe a ray-tracing technique that can be used to estimate these errors. By applying this technique to the spherically symmetric density model derived using the data from the WIND/Waves experiment, we show that (1) the fundamental and harmonic emissions escape the solar atmosphere in narrow cones (at 625 kHz the widths of these escape cones are {approx}1.{sup 0}1 and {approx}8{sup 0}, respectively), (2) the errors in the angles as well as the times of arrival increase monotonically with the angle of arrival (at 625 kHz these errors are 0.{sup 0}26 and {approx}17.2 s for the fundamental and {approx}0.{sup 0}52 and {approx}7.6 s for the harmonic at the maximum possible angles of arrival of {approx}0.{sup 0}55 and {approx}4{sup 0}, respectively), and (3) the lower the frequencies are, the higher the errors in both the angles and times of arrival are. This implies that at 625 kHz the measured arrival angles and arrival times of the fundamental and harmonic are off by {approx}50% and {approx}13%, and {approx}3.4% and {approx}1.5%, respectively.

Thejappa, G. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); MacDowall, R. J.; Gopalswamy, N., E-mail: thejappa@astro.umd.edu, E-mail: Robert.MacDowall@nasa.gov [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2011-06-10

75

Lateral density and arrival time distributions of Cherenkov photons in extensive air showers: a simulation study  

E-print Network

We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using different high and low energy hadronic interaction models available in the CORSIKA simulation package. We have found that, for all primary particles, their energies and hadronic interaction model combinations, the density distribution patterns of Cherenkov photons follow the negative exponential function with different coefficients and slopes depending on the type of primary particle, its energy and the type of model combination. Whereas the arrival time distribution patterns of Cherenkov photons follow the function of the form $t (r) = t_{0}e^{\\Gamma/r^{\\lambda}}$, with different values of the function parameters. Flatness of the density distribution increases with decreasing energy and increasing mass of the primary particle. The shift from the spherical shape of the arrival time distribution near the shower core increases with increasing mass of the low energy primary particl...

Hazarika, P; Chitnis, V R; Acharya, B S; Das, G S; Singh, B B; Britto, R

2014-01-01

76

Improvements of the shock arrival times at the Earth model STOA  

E-print Network

Prediction of the shocks' arrival times (SATs) at the Earth is very important for space weather forecast. There is a well-known SAT model, STOA, which is widely used in the space weather forecast. However, the shock transit time from STOA model usually has a relative large error compared to the real measurements. In addition, STOA tends to yield too much `yes' prediction, which causes a large number of false alarms. Therefore, in this work, we work on the modification of STOA model. First, we give a new method to calculate the shock transit time by modifying the way to use the solar wind speed in STOA model. Second, we develop new criteria for deciding whether the shock will arrive at the Earth with the help of the sunspot numbers and the angle distances of the flare events. It is shown that our work can improve the SATs prediction significantly, especially the prediction of flare events without shocks arriving at the Earth.

Liu, H -L

2015-01-01

77

Arrival Times of Air Shower Particles at Large Distances from the Axis  

Microsoft Academic Search

A study has been made of the relative times of arrival of shower particles at large distances (200 to 1500 m) from the shower axis. Data were obtained at the MIT Volcano Ranch Station, using an array of 20 scintillation detectors, one of which was shielded part of the time. The shower size, direction, and core location were determined for

John Linsley; Livio Scarsi

1962-01-01

78

POSITIONING USING TIME-DIFFERENCE OF ARRIVAL MEASUREMENTS Fredrik Gustafsson and Fredrik Gunnarsson  

E-print Network

) measurements occurs in a range of ap- plications from wireless communication networks to elec- tronic warfare rather insensitive to fading is based on time of arrival (TOA). In future system, only the time's (0.4, 0.6 and 0.9 scale units, respectively). · Electronic warfare, where the problem

Gustafsson, Fredrik

79

Primary energy spectrum of cosmic rays obtained by arrival time spread of particles in EAS  

NASA Astrophysics Data System (ADS)

The Large Area Air Shower (LAAS) group has been performing a network observation of extensive air showers (EAS) by using compact arrays. According to J. Linsley, the primary energy of EAS can be estimated from the spread of the arrival times of EAS particles, even with a small array. A shift register system for clocking the arrival times was installed in an array (OUS1) which is located in Okayama University of Science. Analyzing the OUS1 data, we obtained the primary energies of large air showers.

Okita, M.; Wada, T.; Yamashita, Y.; Okei, K.; Morita, T.; Liang, S.; Takahashi, N.; Iyono, A.; Matsumoto, H.; Noda, C.; Masuda, M.; Yamamoto, I.; Kohata, M.; Ochi, N.; Nakatsuka, T.; Tsuji, S.

2008-01-01

80

Changes in the timing of departure and arrival of Irish migrant waterbirds  

PubMed Central

There have been many recent reports across Europe and North America of a change in the timing of arrival and departure of a range of migrant bird species to their breeding grounds. These studies have focused primarily on passerine birds and climate warming has been found to be one of the main drivers of earlier arrival and departure in spring. In Ireland, rising spring temperature has been shown to result in the earlier arrival of sub-Saharan passerine species and the early departure of the Whooper Swan. In order to investigate changes in spring arrival and departure dates of waterbirds to Ireland, we extracted latest dates as an indicator of the timing of departure of winter visitors (24 species) and earliest dates as an indicator of the timing of arrival of spring/summer migrants (2 species) from BirdWatch Ireland’s East Coast Bird reports (1980–2003). Three of the winter visitors showed evidence of later departure and one of earlier departure whereas one of the spring/summer visitors showed evidence of earlier arrival. In order to determine any influence of local temperature on these trends, we analysed data from two synoptic weather stations within the study area and found that spring (average February, March and April) air temperature significantly (P < 0.05) increased at a rate of 0.03 °C per year, which was strongly correlated with changes in latest and earliest records. We also tested the sensitivity of bird departure/arrival to temperature and found that Northern Pintail would leave 10 days earlier in response to a 1 °C increase in spring temperature. In addition, we investigated the impact of a large-scale circulation pattern, the North Atlantic Oscillation (NAO), on the timing of arrival and departure which correlated with both advances and delays in departure and arrival. We conclude that the impact of climate change on earliest and latest records of these birds is, as expected, species specific and that local temperature had less of an influence than large-scale circulation patterns. PMID:25653907

Geyer, Heather; Yu, Rong

2015-01-01

81

Lithospheric structure of the Illinois Basin from teleseismic P-wave tomography  

NASA Astrophysics Data System (ADS)

We examine heterogeneity of the crust and upper mantle associated with a major intracratonic basin, using arrival time data from a regional EarthScope experiment extending across the western margin of the Illinois Basin. We measured 24,062 P-wave residuals associated with 399 teleseismic events recorded from January 2012 to March 2013 by 122 stations in the Illinois Basin region. We used data from the Ozark Illinois INdiana Kentucky (OIINK) Flexible Array, the permanent New Madrid Seismic Network, and a portion of the Earthscope Transportable Array. Precise relative arrival times were determined using array cross-correlation methods. We plotted the measured arrivals as residual maps to identify first order patterns of velocity heterogeneity and to fix outliers. These data were then inverted for P-wave velocity using non-linear tomography code developed by Steven Roecker. Our preliminary results indicate the upper 200 km of the mantle can be characterized by two blocks with a transition zone centered roughly parallel to the Ohio River boundary of Illinois and Kentucky. Estimated P-wave velocities are higher in Kentucky, located southeast of the transition zone compared to Missouri and Illinois, located northwest. We caution that at this stage our tomography model may be biased as we have not accounted for variations in crustal structure or applied corrections associated with the Illinois Basin. Parallel work with receiver functions by our group and the known geometry of the Illinois Basin will be used to calculate these corrections and modify the tomographic model accordingly.

Wilson, B.; Gilbert, H. J.; Hamburger, M. W.; Merrell, T.; Pavlis, G. L.; Sherrill, E.

2013-12-01

82

Multichannel deconvolution of p waves at seismic arrays and three-component stations. Annual report, 1 October 1985-1 October 1986  

SciTech Connect

The results of a new multichannel method, applied to array recordings and three-component station networks for teleseismic P waves, are presented and interpreted in terms of possible surface reflections and other arrivals from the Nevada Test Site (NTS), Novaya Zemlya, and Eastern Kazakh Test Site (EKTS) nuclear explosions. The deconvolution method utilizes the well known fact that P-wave spectra can be decomposed into source and receiver spectral factors. The source functions obtained in the deconvolution process provide a better picture of the nature of explosion source time functions and, in particular, of the presence or lack of secondary arrivals following the P wave such as pP or spall. The presence of such secondary arrivals and their effects on the first cycle of the P wave are very important in yield estimation. For most events at the eastern part of EKTS the source time functions appear to contain a pP arrival but they also show later, unexplained arrivals and other complexities. At other test sites often there are no clearly identifiable pP phases in the deconvolved traces. Joint deconvolution of central EKTS data using all AWRE arrays indicated strong azimuthal asymmetries in the body-wave radiation. Deconvolutions of NTS events were considerably degraded by the limited signal bandwidth due to strong mantle attenuation under this test site. The site functions are also complex in most cases. Site and source effects contribute about equally to the energy observed in the P codas of the events analyzed.

Der, Z.A.; Lees, A.C.; Shumway, R.H.; McElfresh, T.W.; Marshall, M.E.

1986-10-30

83

Real-time Upstream Monitoring System: Using ACE Data to Predict the Arrival of Interplanetary Shocks  

NASA Astrophysics Data System (ADS)

We have developed an algorithm to predict Earth arrival times for interplanetary (IP) shock events originating at the Sun. Our predictions are generated from real-time data collected by the Electron, Proton, and Alpha Monitor (EPAM) instrument on NASA's Advanced Composition Explorer (ACE) spacecraft. The high intensities of energetic ions that occur prior to and during an IP shock pose a radiation hazard to astronauts as well as to electronics in Earth orbit. The potential to predict such events is based on characteristic signatures in the Energetic Storm Particle (ESP) event ion intensities which are often associated with IP shocks. We have previously reported on the development and implementation of an algorithm to forecast the arrival of ESP events. Historical ion data from ACE/EPAM was used to train an artificial neural network which uses the signature of an approaching event to predict the time remaining until the shock arrives. Tests on the trained network have been encouraging, with an average error of 9.4 hours for predictions made 24 hours in advance, and an reduced average error of 4.9 hours when the shock is 12 hours away. The prediction engine has been integrated into a web-based system that uses real-time ACE/EPAM data provided by the NOAA Space Environment Center (http://sd-www.jhuapl.edu/UPOS/RISP/ index.html.) This system continually processes the latest ACE data, reports whether or not there is an impending shock, and predicts the time remaining until the shock arrival. Our predictions are updated every five minutes and provide significant lead-time, thereby supplying critical information that can be used by mission planners, satellite operations controllers, and scientists. We have continued to refine the prediction capabilities of this system; in addition to forecasting arrival times for shocks, we now provide confidence estimates for those predictions.

Donegan, M. M.; Wagstaff, K. L.; Ho, G. C.; Vandegriff, J.

2003-12-01

84

Time-of-arrival estimation by UWB radios with low sampling rate and clock drift calibration$  

E-print Network

: Ultra-wideband Time-of-arrival Clock drift Stroboscopic sampling a b s t r a c t In this paper, we is featured by a low sampling rate and is robust against clock drift. Low-rate stroboscopic sampling, which samples, the clock drift is one of the main error sources in TOA estimation with stroboscopic sampling IR

Leus, Geert

85

Lateral density and arrival time distributions of Cherenkov photons in extensive air showers: a simulation study  

E-print Network

We have investigated some features of the density and arrival time distributions of Cherenkov photons in extensive air showers using the CORSIKA simulation package. The main thrust of this study is to see the effect of hadronic interaction models on the production pattern of Cherenkov photons with respect to distance from the shower core. Such studies are very important in ground based $\\gamma$-ray astronomy for an effective rejection of huge cosmic ray background, where the atmospheric Cherenkov technique is being used extensively within the energy range of some hundred GeV to few TeV. We have found that for all primary particles, the density distribution patterns of Cherenkov photons follow the negative exponential function with different coefficients and slopes depending on the type of primary particle, its energy and the type of interaction model combinations. Whereas the arrival time distribution patterns of Cherenkov photons follow the function of the form $t (r) = t_{0}e^{\\Gamma/r^{\\lambda}}$, with different values of the function parameters. There is no significant effect of hadronic interaction model combinations onthe density and arrival time distributions for the $\\gamma$-ray primaries. However, for the hadronic showers, the effects of the model combinations are significant under different conditions. There are some contributions from shower to shower fluctuations to the density and arrival time deviations of Cherenkov photons apart from the contribution due to inherent differences in hadronic interaction models.

P. Hazarika; U. D. Goswami; V. R. Chitnis; B. S. Acharya; G. S. Das; B. B. Singh; R. Britto

2014-04-08

86

Determination of arrival times for acoustic emission source location in composites  

Microsoft Academic Search

The determination of the arrival time of an AE event has been studied using simulated acoustic emission (AE) signals on a Kevlar\\/epoxy composite. Transient recorder records were used to study the AE waveforms as well as the background electronic noise. Parameters studied include the bandpass and the relative position of the sensor with respect to the source position. The rise

M. A. Hamstad

1986-01-01

87

A Comparison of Waterflood Management Using Arrival Time Optimization and NPV Optimization  

E-print Network

the gradients. The comparison is conducted on a 4- spot synthetic case. Then we introduce the accelerated arrival time optimization which has an acceleration term in the objective function to speed up the oil production in the field. The proposed new approach...

Tao, Qing

2011-02-22

88

OneBusAway: Results from Providing Real-Time Arrival Information for Public Transit  

E-print Network

OneBusAway: Results from Providing Real-Time Arrival Information for Public Transit Brian Ferris@cs.washington.edu ABSTRACT Public transit systems play an important role in combating traffic congestion, reducing carbon emissions, and promot- ing compact, sustainable urban communities. The usability of public transit can

Anderson, Richard

89

Effects of a Longer Detection Window in VHF Time-of-Arrival Lightning Detection Systems  

Microsoft Academic Search

Lightning detection systems that operate by measuring the times of arrival (TOA) of short bursts of radiation at VHF can produce huge volumes of data. The first automated system of this kind, the NASA Kennedy Space Center LDAR network, is capable of producing one detection every 100 usec from each of seven sensors (Lennon and Maier, 1991), where each detection

M. Murphy; R. Holle; N. Demetriades

2003-01-01

90

Instate Travel Are departure and arrival times included on the travel expense statement?  

E-print Network

Instate Travel Are departure and arrival times included on the travel expense statement? Is expense attached? For overnight travel, are per diem rates on the day of departure and day of return listed at 75 utilized a personal vehicle for travel and departed from or returned to his/her personal residence

Arnold, Jonathan

91

Maximum Likelihood Time-of-Arrival Estimation of Optical Pulses via Photon-Counting Photodetectors  

NASA Technical Reports Server (NTRS)

Many optical imaging, ranging, and communications systems rely on the estimation of the arrival time of an optical pulse. Recently, such systems have been increasingly employing photon-counting photodetector technology, which changes the statistics of the observed photocurrent. This requires time-of-arrival estimators to be developed and their performances characterized. The statistics of the output of an ideal photodetector, which are well modeled as a Poisson point process, were considered. An analytical model was developed for the mean-square error of the maximum likelihood (ML) estimator, demonstrating two phenomena that cause deviations from the minimum achievable error at low signal power. An approximation was derived to the threshold at which the ML estimator essentially fails to provide better than a random guess of the pulse arrival time. Comparing the analytic model performance predictions to those obtained via simulations, it was verified that the model accurately predicts the ML performance over all regimes considered. There is little prior art that attempts to understand the fundamental limitations to time-of-arrival estimation from Poisson statistics. This work establishes both a simple mathematical description of the error behavior, and the associated physical processes that yield this behavior. Previous work on mean-square error characterization for ML estimators has predominantly focused on additive Gaussian noise. This work demonstrates that the discrete nature of the Poisson noise process leads to a distinctly different error behavior.

Erkmen, Baris I.; Moision, Bruce E.

2010-01-01

92

Accurate seismic phase identification and arrival time picking of glacial icequakes  

NASA Astrophysics Data System (ADS)

A catastrophic lake drainage event was monitored continuously using an array of 6, 4.5 Hz 3 component geophones in the Russell Glacier catchment, Western Greenland. Many thousands of events and arrival time phases (e.g., P- or S-wave) were recorded, often with events occurring simultaneously but at different locations. In addition, different styles of seismic events were identified from 'classical' tectonic earthquakes to tremors usually observed in volcanic regions. The presence of such a diverse and large dataset provides insight into the complex system of lake drainage. One of the most fundamental steps in seismology is the accurate identification of a seismic event and its associated arrival times. However, the collection of such a large and complex dataset makes the manual identification of a seismic event and picking of the arrival time phases time consuming with variable results. To overcome the issues of consistency and manpower, a number of different methods have been developed including short-term and long-term averages, spectrograms, wavelets, polarisation analyses, higher order statistics and auto-regressive techniques. Here we propose an automated procedure which establishes the phase type and accurately determines the arrival times. The procedure combines a number of different automated methods to achieve this, and is applied to the recently acquired lake drainage data. Accurate identification of events and their arrival time phases are the first steps in gaining a greater understanding of the extent of the deformation and the mechanism of such drainage events. A good knowledge of the propagation pathway of lake drainage meltwater through a glacier will have significant consequences for interpretation of glacial and ice sheet dynamics.

Jones, G. A.; Doyle, S. H.; Dow, C.; Kulessa, B.; Hubbard, A.

2010-12-01

93

Techniques for measuring arrival times of pulsar signals 1: DSN observations from 1968 to 1980  

NASA Astrophysics Data System (ADS)

Techniques used in the ground based observations of pulsars are described, many of them applicable in a navigation scheme. The arrival times of the pulses intercepting Earth are measured at time intervals from a few days to a few months. Low noise, wide band receivers, amplify signals intercepted by 26 m, 34, and 64 m antennas. Digital recordings of total received signal power versus time are cross correlated with the appropriate pulse template.

Downs, G. S.; Reichley, P. E.

1980-08-01

94

Feasibility of water seepage monitoring in concrete with embedded smart aggregates by P-wave travel time measurement  

NASA Astrophysics Data System (ADS)

Water seepage in concrete threatens the safety of marine constructions and reduces the durability of concrete structures. This note presents a smart aggregate-based monitoring method to monitor the travel time evolution of a harmonic stress wave during the water infiltrating process in concrete structures. An experimental investigation, in which two plain concrete columns were examined under different water infiltration cases, verified the validity of the proposed monitoring method. The test results show that the travel time of the harmonic stress wave is sensitive to the development of water seepage in concrete and decreases with increasing water seepage depth. The proposed active monitoring method provides an innovative approach to monitor water seepage in concrete structures.

Zou, Dujian; Liu, Tiejun; Huang, Yongchao; Zhang, Fuyao; Du, Chengcheng; Li, Bo

2014-06-01

95

Holographic p -wave superfluid  

NASA Astrophysics Data System (ADS)

In the probe limit, we numerically construct a holographic p -wave superfluid model in the four-dimensional (4D) and five-dimensional (5D) anti-de Sitter black holes coupled to a Maxwell-complex vector field. We find that, for the condensate with the fixed superfluid velocity, the results are similar to the s -wave cases in both 4D and 5D spacetimes. In particular, the Cave of Winds and the phase transition, always being of second order, take place in the 5D case. Moreover, we find that the translating superfluid velocity from second order to first order S/y? increases with the mass squared. Furthermore, for the supercurrent with fixed temperature, the results agree with the Ginzburg-Landau prediction near the critical temperature. In addition, this complex vector superfluid model is still a generalization of the SU(2) superfluid model, and it also provides a holographic realization of the H e3 superfluid system.

Wu, Ya-Bo; Lu, Jun-Wang; Zhang, Wen-Xin; Zhang, Cheng-Yuan; Lu, Jian-Bo; Yu, Fang

2014-12-01

96

Monitoring molecular interactions using photon arrival-time interval distribution analysis  

DOEpatents

A method for analyzing/monitoring the properties of species that are labeled with fluorophores. A detector is used to detect photons emitted from species that are labeled with one or more fluorophores and located in a confocal detection volume. The arrival time of each of the photons is determined. The interval of time between various photon pairs is then determined to provide photon pair intervals. The number of photons that have arrival times within the photon pair intervals is also determined. The photon pair intervals are then used in combination with the corresponding counts of intervening photons to analyze properties and interactions of the molecules including brightness, concentration, coincidence and transit time. The method can be used for analyzing single photon streams and multiple photon streams.

Laurence, Ted A. (Livermore, CA); Weiss, Shimon (Los Angels, CA)

2009-10-06

97

Direct observation of temporal coherence by weak projective measurements of photon arrival time  

NASA Astrophysics Data System (ADS)

We show that a weak projective measurement of photon arrival time can be realized by controllable two-photon interferences with photons from short-time reference pulses at a polarization beam splitter. The weak value of the projector on the arrival time defined by the reference pulse can be obtained from the coincidence rates conditioned by a specific output measurement. If the weak measurement is followed by a measurement of frequency, the coincidence counts reveal the complete temporal coherence of the single-photon wave function. Significantly, the weak values of the input state can also be obtained at higher measurement strengths, so that correlations between weak measurements on separate photons can be observed and evaluated without difficulty. The method can thus be used to directly observe the nonclassical statistics of time-energy entangled photons.

Hofmann, Holger F.; Ren, Changliang

2013-06-01

98

Upper mantle P-wave velocity structure beneath southern Scandinavia  

NASA Astrophysics Data System (ADS)

This study images upper mantle structure beneath different tectonic and geomorphological provinces in southern Scandinavia by P-wave travel time tomography based on teleseismic events. We present integrated results using data from several projects (CALAS, MAGNUS, SCANLIPS, CENMOVE and Tor) with a total of 202 temporary seismological stations deployed in southern Norway, southern Sweden, Denmark and the northernmost part of Germany. These stations, together with 18 permanent stations, yield a high density data coverage enabling presentation of the first high resolution 3D seismic P-wave velocity model for the upper mantle for this region, which includes areas of Baltic Shield, Scandinavian Caledonides, the entire northern part of the prominent Tornquist Zone and the Southern Scandes Mountains. P-wave arrival time residuals of up to ±1 s are observed reflecting large seismic velocity contrasts at depths. Relative regional as well as absolute global tomographic inversion is carried out and consistently show upper mantle velocity variations relative to the ak135 reference model of up to ± 2-3 % corresponding to P-wave velocity differences of about 0.4 km/s from depths of about 100 km to more than 300 km. High upper mantle velocities are observed to great depth to the east in Baltic Shield areas of southwestern Sweden. Lower velocities are found to the west and southwest beneath the Danish and North German sedimentary basins and in most of southern Norway. A well-defined, generally narrow deep boundary is observed between areas of contrasting upper mantle seismic velocity. In basin areas, low upper mantle velocities are associated with thinned lithosphere and velocity contrasts are interpreted to represent differences between deep shield lithosphere and shallow basin asthenosphere with a deep lithospheric boundary running close to the Sorgenfrei-Tornquist Zone. Differences in P-wave velocity are here likely to arise mainly from temperature differences. To the north, the boundary crosses various tectonic and geomorphologic units including shield units, the Caledonides as well as areas of high topography, and a structural and geodynamic interpretation is more complex. Reduced upper mantle velocities below southern Norway also appear to be associated with a thinner lithosphere compared to shield areas to the east. Velocity contrasts may be explained to a higher degree by both compositional and temperature differences and a geodynamic origin including both Proterozoic and Phanerozoic events. Below southern Norway, a regional contribution to buoyancy from reduced density in the upper mantle is likely to exist, but we observe no clear correlation between reduced upper mantle seismic velocity and high topography of the southern Scandes Mountains.

Medhus, A. B.; Balling, N.; Jacobsen, B. H.; England, R. W.; Kind, R.; Weidle, C.; Voss, P.; Thybo, H.

2012-04-01

99

High resolution time of arrival estimation for a cooperative sensor system  

NASA Astrophysics Data System (ADS)

Distance resolution of cooperative sensors is limited by the signal bandwidth. For the transmission mainly lower frequency bands are used which are more narrowband than classical radar frequencies. To compensate this resolution problem the combination of a pseudo-noise coded pulse compression system with superresolution time of arrival estimation is proposed. Coded pulsecompression allows secure and fast distance measurement in multi-user scenarios which can easily be adapted for data transmission purposes (Morhart and Biebl, 2009). Due to the lack of available signal bandwidth the measurement accuracy degrades especially in multipath scenarios. Superresolution time of arrival algorithms can improve this behaviour by estimating the channel impulse response out of a band-limited channel view. For the given test system the implementation of a MUSIC algorithm permitted a two times better distance resolution as the standard pulse compression.

Morhart, C.; Biebl, E. M.

2010-09-01

100

A Comparison of Center/TRACON Automation System and Airline Time of Arrival Predictions  

NASA Technical Reports Server (NTRS)

Benefits from information sharing between an air traffic service provider and a major air carrier are evaluated. Aircraft arrival time schedules generated by the NASA/FAA Center/TRACON Automation System (CTAS) were provided to the American Airlines System Operations Control Center in Fort Worth, Texas, during a field trial of a specialized CTAS display. A statistical analysis indicates that the CTAS schedules, based on aircraft trajectories predicted from real-time radar and weather data, are substantially more accurate than the traditional airline arrival time estimates, constructed from flight plans and en route crew updates. The improvement offered by CTAS is especially advantageous during periods of heavy traffic and substantial terminal area delay, allowing the airline to avoid large predictive errors with serious impact on the efficiency and profitability of flight operations.

Heere, Karen R.; Zelenka, Richard E.

2000-01-01

101

Analyses of the Age of Genes and the First Arrival Times in a Finite Population  

PubMed Central

The age of a mutant gene is studied using the infinite allele model in which every mutant is new and selectively neutral. Based on a time reversal theory of Markov processes, we develop a method of mathematical analysis that is considerably simpler for calculating the various statistics of the age than previous methods. Formulas for the mean and variance and for the distribution of age are presented together with some examples of relevance to cases in natural populations.—Theoretical studies of the first arrival time of an allele to a specified frequency, given an initially monomorphic condition of the locus, are presented. It is shown that, beginning with an allele that has frequency p = 1 or an allele with frequency p = 1/2N, there is an initial lag phase in which there is virtually no chance of an allele with a specified intermediate frequency appearing in the population. The distribution of the first arrival time is also presented. The distribution shows several characteristics that are not immediately obvious from a consideration of only the mean and variance of first arrival time. Especially noteworthy is the existence of a very long tail to the distribution. We have also studied the distribution of the age of an allele in the population. Again, the distribution of this measure is shown to be more informative for several questions than are the mean and variance alone. PMID:17246178

Maruyama, Takeo; Fuerst, Paul A.

1983-01-01

102

Joint estimation of time delays and directions of arrival of multiple reflections of a known signal  

Microsoft Academic Search

We present an efficient algorithm for estimating the time delays and the directions-of-arrival (DOAs) of multiple reflections of a known signal. The algorithm is based on an iterative scheme that transforms the multidimensional maximum likelihood criterion into two sets of simple one-dimensional (1-D) maximization problems. Simulation results illustrating the performance of the algorithm in comparison with the Cramer-Rao bound are

Mati Wax; Amir Leshem

1997-01-01

103

Time-of-Arrival Estimation with FLOM-MUSIC Under Impulsive Noise  

Microsoft Academic Search

FLOM-MUSIC (fractional lower order moment- MUSIC), a high resolution spectral estimation algorithm, is proposed for TOA (time of arrival) estimation under non-Gaussian noise. While Gaussianity is the conventional model in statistical signal processing, it does not accurately represent noise with impulsive nature that do occur in some wireless environments. FLOM-MUSIC is, in particular, designed for the a-stable model of impulsive

I. Hacioglu; F. K. Harmanci; E. Anarim; H. Delic

2006-01-01

104

Inversion of qP wave travel times from the URL experiment 1 Ivan Psenc'ik \\Lambda , JingSong Liu \\Lambda\\Lambda , R. Paul Young \\Lambda\\Lambda\\Lambda  

E-print Network

Inversion of qP wave travel times from the URL experiment 1 Ivan PŸsenŸc'ik \\Lambda , JingSong Liu an experiment in the vicinity of the Underground Research Laboratory (URL) in Manitoba, Canada are inverted heterogeneity and anisotropy of rocks surrounding the tunnel of the URL is made except the variation of elastic

Cerveny, Vlastislav

105

Comparing seismic tomographic images from automatically- and manually-detected arrival times  

NASA Astrophysics Data System (ADS)

In this work we compare local earthquake tomographic images obtained using arrival times detected by an automatic picking procedure and by an expert seismologist. For this purpose we select a reference dataset composed of 476 earthquakes occurred in the Trentino region (north-eastern Italy) in the period 1994-2007. Local magnitudes are comprised between 0.8 and 5.3. Original recordings are mainly from the Provincia Autonoma di Trento (PAT), and from other networks operating in the surrounding areas (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - INOGS; Istituto Nazionale di Geofisica e Vulcanologia - INGV; others available via the European Integrated Data Archive). The automatic picking of P and S phases is performed through a picker engine based on the Akaike information criterion (AIC). In particular, the proposed automatic phase picker includes: (i) envelope calculation, (ii) band-pass filtering, (iii) Akaike information criterion (AIC) detector for both P- and S-arrivals, (iv) checking for impulsive arrivals, (v) evaluation of expected S onset on the basis of a preliminary location derived from the P-arrival times, and (vi) quality assessment. Simultaneously, careful manual inspection by expert seismologists is applied to the same waveform dataset, to obtain manually-repicked phase readings. Both automatic and manual procedures generate a comparable amount of readings (about 6000 P- and 5000 S-phases). These data are used for the determination of two similar 3-D propagation models for the Trentino region, applying the SIMULPS code. In order to quantitatively estimate the difference of these two models we measure their discrepancies in terms of velocity at all grid points. The small differences observed among tomographic results allow us to demonstrate that the automatic picking engine adopted in this test can be used for reprocessing large amount of seismic recordings with the aim of perform a local tomographic study with an accuracy comparable to the one obtainable with a complete manual data revision.

Spallarossa, Daniele; Scafidi, Davide; Turino, Chiara; Ferretti, Gabriele; Viganò, Alfio

2013-04-01

106

Evidence for the subducting lithosphere under Southern Vancouver Island and Western Oregon from teleseismic P wave conversions  

Microsoft Academic Search

Long-period teleseismic P waves recorded at VIC (Victoria, British Columbia) and COR (Corvallis, Orgeon) show anomalously large Ps conversions and later arriving P-to-S reverberations not observed from typical continental crustal sections or from previously proposed structures for these stations determined from refraction surveys. The timing and large amplitude of the Ps phase, relative to direct P, suggests a high velocity-contrast

Charles A. Langston

1981-01-01

107

Analysis of the Tsunami of December 26, 2004, on the Kerala Coast of India—Part II: Arrival Times  

Microsoft Academic Search

The Tsunami of December 26, 2004, in the Indian Ocean arrived on the coast of Kerala in southwest India some three hours after the tsunami was generated. The tsunami activity persisted throughout that day and, in some locations, even into the early morning of the next day. Based on interviews with eye witnesses, arrival times of tsunami waves are presented

M. Baba; N. P. Kurian; B. T. Murali Krishnan; N. Nirupama; T. S. Murty

2006-01-01

108

Highly efficient arrival timing diagnostics for femtosecond X-ray and optical laser pulses  

NASA Astrophysics Data System (ADS)

We developed a diagnostic system for measuring the arrival timing between femtosecond X-ray free-electron laser (XFEL) and near-infrared laser pulses with high efficiency. The ultrafast change in optical transmittance induced by intense XFEL light was probed by a spatial decoding technique. For enhancing detection efficiency, we utilized an X-ray elliptical mirror that increases X-ray intensity by forming a line-focused profile. We found that the system is applicable to the timing diagnostics for 12 keV X-ray pulses with a pulse energy as small as 12 µJ.

Sato, Takahiro; Togashi, Tadashi; Ogawa, Kanade; Katayama, Tetsuo; Inubushi, Yuichi; Tono, Kensuke; Yabashi, Makina

2015-01-01

109

The function of bilateral odor arrival time differences in olfactory orientation of sharks.  

PubMed

The direction of an odor signal source can be estimated from bilateral differences in signal intensity and/or arrival time. The best-known examples of the use of arrival time differences are in acoustic orientation. For chemoreception, animals are believed to orient by comparing bilateral odor concentration differences, turning toward higher concentrations. However, time differences should not be ignored, because odor plumes show chaotic intermittency, with the concentration variance several orders of magnitude greater than the concentration mean. We presented a small shark species, Mustelus canis, with carefully timed and measured odor pulses directly into their nares. They turned toward the side stimulated first, even with delayed pulses of higher concentration. This is the first conclusive evidence that under seminatural conditions and without training, bilateral time differences trump odor concentration differences. This response would steer the shark into an odor patch each time and thereby enhance its contact with the plume, i.e., a stream of patches. Animals with more widely spaced nares would be able to resolve smaller angles of attack at higher swimming speeds, a feature that may have contributed to the evolution of hammerhead sharks. This constitutes a novel steering algorithm for tracking odor plumes. PMID:20541411

Gardiner, Jayne M; Atema, Jelle

2010-07-13

110

Predicting Ambulance Time of Arrival to the Emergency Department Using Global Positioning System and Google Maps  

PubMed Central

Objective To derive and validate a model that accurately predicts ambulance arrival time that could be implemented as a Google Maps web application. Methods This was a retrospective study of all scene transports in Multnomah County, Oregon, from January 1 through December 31, 2008. Scene and destination hospital addresses were converted to coordinates. ArcGIS Network Analyst was used to estimate transport times based on street network speed limits. We then created a linear regression model to improve the accuracy of these street network estimates using weather, patient characteristics, use of lights and sirens, daylight, and rush-hour intervals. The model was derived from a 50% sample and validated on the remainder. Significance of the covariates was determined by p < 0.05 for a t-test of the model coefficients. Accuracy was quantified by the proportion of estimates that were within 5 minutes of the actual transport times recorded by computer-aided dispatch. We then built a Google Maps-based web application to demonstrate application in real-world EMS operations. Results There were 48,308 included transports. Street network estimates of transport time were accurate within 5 minutes of actual transport time less than 16% of the time. Actual transport times were longer during daylight and rush-hour intervals and shorter with use of lights and sirens. Age under 18 years, gender, wet weather, and trauma system entry were not significant predictors of transport time. Our model predicted arrival time within 5 minutes 73% of the time. For lights and sirens transports, accuracy was within 5 minutes 77% of the time. Accuracy was identical in the validation dataset. Lights and sirens saved an average of 3.1 minutes for transports under 8.8 minutes, and 5.3 minutes for longer transports. Conclusions An estimate of transport time based only on a street network significantly underestimated transport times. A simple model incorporating few variables can predict ambulance time of arrival to the emergency department with good accuracy. This model could be linked to global positioning system data and an automated Google Maps web application to optimize emergency department resource use. Use of lights and sirens had a significant effect on transport times. PMID:23865736

Fleischman, Ross J.; Lundquist, Mark; Jui, Jonathan; Newgard, Craig D.; Warden, Craig

2014-01-01

111

Processing advances for localization of beaked whales using time difference of arrival.  

PubMed

This paper is concerned with the localization of clicking Blainville's beaked whales (Mesoplodon densirostris) using an array of widely spaced bottom-mounted hydrophones. A set of signal and data processing advances are presented that together make reliable tracking a possibility. These advances include a species-specific detector, elimination of spurious time-difference-of-arrival (TDOA) estimates, improved tracking of TDOA estimates, positive association of TDOA estimates using different hydrophone pairs, and joint localization of multiple whales. A key innovation in three of these advances is the principle of click-matching. The methods are demonstrated using real data. PMID:23742359

Baggenstoss, Paul M

2013-06-01

112

Phase sensitive monitoring of electron bunch form and arrival time in superconducting linear accelerators  

SciTech Connect

In this Letter, we present a simple approach for monitoring electron bunch form and arrival time combining electro-optic sampling and phase and frequency sensitive signal detection. The sensitivity of the technique has the potential to allow online diagnostics to be performed down to bunch charges in the femto coulomb regime. The concept has high impact for the developments of the next generation of 4th generation x-ray light sources working with long pulse trains or continuous wave mode of operation.

Kaya, C.; Schneider, C.; Seidel, W.; Kuntzsch, M.; Bhattacharyya, J.; Mittendorff, M.; Winnerl, S.; Staats, G.; Helm, M.; Michel, P.; Gensch, M. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328, Dresden (Germany); Al-Shemmary, A.; Stojanovic, N. [DESY, Notkestr. 85, 22607 Hamburg (Germany); Evtushenko, P. [Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

2012-04-02

113

Measurement-induced spatial modulation of spontaneous decay and photon arrival times  

SciTech Connect

We report a way of manipulating the spontaneous emission process leading to a spatial modulation of spontaneous decay. The effect is observed in the case of coherently driven atoms separated by less than a transition wavelength. It is quantified by Glauber's photon-photon second-order correlation function. We show that the photon arrival time, usually regarded as an entirely random process, depends not only on where a photon is detected but also on where a former photon had been recorded previously. Our results shed light on the unexpected consequences of state reduction and entanglement for the fundamental process of spontaneous emission.

Zanthier, Joachim von [Institut fuer Optik, Information und Photonik, Universitaet Erlangen-Nuernberg, 91058 Erlangen (Germany); Bastin, Thierry [Institut de Physique Nucleaire, Atomique et de Spectroscopie, Universite de Liege au Sart Tilman, 4000 Liege (Belgium); Agarwal, Girish S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078-3072 (United States)

2006-12-15

114

VLF long-range lightning location using the arrival time difference technique (ATD)  

NASA Technical Reports Server (NTRS)

A new network of VLF receiving systems is currently being developed in the USA to support NASA's Tropical Rain Measuring Mission (TRMM). The new network will be deployed in the east coast of the US, including Puerto Rico, and will be operational in late 1995. The system should give affordable, near real-time, accurate lightning locating capabilities at long ranges and with extended coverage. It is based on the Arrival Time Difference (ATD) method of Lee (1986; 1990). The ATD technique is based on the estimation of the time of arrival of sferics detected over an 18 kHz bandwith. The ground system results will be compared and complemented with satellite optical measurements gathered with the already operational Optical Transient Detector (OTD) instrument and in due course with its successor the Lightning Imaging Sensor (LIS). Lightning observations are important to understand atmospheric electrification phenomena, discharge processes, associated phenomena on earth (e.g. whistlers, explosive Spread-F) and other planets. In addition, lightning is a conspicuous indicator of atmospheric activity whose potential is just beginning to be recognized and utilized. On more prosaic grounds, lightning observations are important for protection of life, property and services.

Ierkic, H. Mario

1996-01-01

115

Limits to PTA sensitivity: spin stability and arrival time precision of millisecond pulsars  

NASA Astrophysics Data System (ADS)

Sources of noise in pulsar timing measurements are discussed along with spin stability of neutron stars. Estimates and scaling laws are given for spin noise, timing errors from fluctuations in pulsar magnetospheres, dispersion and scattering in the interstellar plasma, and in the matched filtering technique used to estimate arrival times. The composite noise spectrum is presented and an assessment of the detectability of gravitational waves (GWs) is given in terms of the sources of error and their mitigation. The scaling laws indicate that substantial improvement in sensitivity to GWs can be expected from implementation of new, wideband spectrometers at radio observatories, by using new algorithms to further reduce the levels of plasma propagation effects, and by increasing the number of millisecond pulsars used in pulsar timing arrays.

Cordes, James M.

2013-11-01

116

Determination of differential arrival times by cross-correlating worldwide seismological data  

NASA Astrophysics Data System (ADS)

Cross-correlation delays are the preferred body wave observables in global tomography. Heterogeneity is the main factor influencing delay times found by cross-correlation. Not only the waveform, but also the arrival time itself is affected by differences in seismic velocity encountered along the way. An accurate method for estimating differential times of seismic arrivals across a regional array by cross-correlation was developed by VanDecar and Crosson [1990]. For the estimation of global travel time delays in different frequency bands, Sigloch and Nolet [2006] developed a method for the estimation of body wave delays using a matched filter, which requires the separate estimation of the source time function. Sigloch et al. [2008] found that waveforms often cluster in and opposite the direction of rupture propagation on the fault, confirming that the directivity effect is a major factor in shaping the waveform of large events. We propose a generalization of the VanDecar-Crosson method to which we add a correction for the directivity effect in the seismological data. The new method allows large events to be treated without the need to estimate the source time function for the computation of a matched synthetic waveform. The procedure consists in (1) the detection of the directivity effect in the data and the determination of a rupture model (unilateral or bilateral) explaining the differences in pulse duration among the stations, (2) the determination of an apparent fault rupture length explaining the pulse durations, (3) the removal of the delay due to the directivity effect in the pulse duration , by stretching or contracting the seismograms for directive and anti-directive stations respectively and (4) the application of a generalized VanDecar and Crosson method using only delays between pairs of stations that have an acceptable correlation coefficient. We validate our method by performing tests on synthetic data. Results show that the error between theoretical and measured differential arrival time are significantly reduced for the corrected data. We illustrate our method on data from several real earthquakes.

Godano, M.; Nolet, G.; Zaroli, C.

2012-12-01

117

Scattering of P Waves under the Montana Lasa  

Microsoft Academic Search

The variations of amplitude and time delay of teleseismic P waves across the Montana Lass (Large Aperture Seismic Array) were interpreted as being due to scattering by a random inhomogeneity in the earth's crust under the array. The prediction of the Chernov [1960] theory explains well the observed statistical properties of P waves with a frequency of 0.5 I-iz. The

Keiiti Aki

1973-01-01

118

Anxiety and P Wave Dispersion in a Healthy Young Population  

Microsoft Academic Search

Background: P wave dispersion (Pd), defined as the difference between the maximum (Pmax) and the minimum P wave duration (Pmin), and Pmax are electrocardiographic (ECG) markers that have been used to evaluate the discontinuous propagation of sinus impulses and the prolongation of atrial conduction time. Pd in normal subjects has been reported to be influenced by the autonomic tone, which

Hüseyin Uyarel; Sennur Unal Dayi; Zeynep Tartan; Ahmet Karabulut; Bülent Uzunlar; Hasan Samur; Ertan Okmen; Nese Cam

2005-01-01

119

The influence of ice-pressure on p-wave velocity in alpine low-porosity rocks: a modified time-average model  

NASA Astrophysics Data System (ADS)

Most polar and many mountainous regions are affected by permafrost. Seismic field and laboratory measurements represent a standard approach to investigate permafrost since the early 1970s. Laboratory research has focussed on arctic high-porosity sandstones, shales and carbonate rocks and results have been implemented in various seismic models (Carcione and Seriani, 1998). However, alpine rock walls consist of low-porosity bedrock and some authors deny the applicability of seismic approaches to these (McGinnis et al., 1973). Models developed in high-porosity rocks explain bulk p-wave velocity of bedrock due to changing velocities in the pore infill (ice/water/air) while the matrix velocity of bedrock remains constant. Here we show, that in low-porosity rocks matrix velocities change considerably while changes in pore velocities are insignificant. Hence, p-wave refraction seismics is applicable in low-porosity alpine rock walls. For this, we (1) present data of p-wave measurements of 23 different alpine rocks, (2) evaluate the influence of ice pressure on seismic velocities, (3) determine anisotropic decrease due to ice pressure and (4) extend Timur's (1968) 2-phase model for alpine rocks. The tested rocks derive from alpine locations in Switzerland, Germany, Austria, France and Svalbard, and German sub alpine locations. All samples possess effective porosities lower than 6 %. P-wave velocities were measured parallel and perpendicular to cleavage or bedding in a temperature range from +20° C to -15° C in a WEISS WK 180/40 high-accuracy climate chamber. Rock temperature was monitored continuously with two or three calibrated thermometers; p-waves were generated with a Geotron ultrasonic transducer and measured with a Fluke Scopemeter. (1) All rock samples show p-wave velocity increase dependent on lithology due to freezing. P-wave velocity increase is in the range of 7.33 (±3.73) % for Gneiss and 78.45 (±7.00) % for carbonate rocks parallel to cleavage/bedding; perpendicular measurements show an increase between 11.10 (±2.38) % for Gneiss and 166.01 (±56.93) % for carbonate rocks. The increase of p-wave velocity of carbonate rocks is independent of effective porosity. (2) Velocity increase due to freezing is not only derived through higher velocity of ice in relation to water; ice pressure induces an increase of the velocity of the rock matrix. Matrix velocity increases parallel to cleavage/bedding between 5.08 (±4.08) % for Gneiss and 59.44 (±9.33) % for carbonate rocks; perpendicular measurements indicate matrix velocity increase reaching from 8.95 (±4.51) % for mafic metamorphic rocks and 168.53 (±62.00) % for carbonate rocks. (3) Anisotropy decreases as a result of crack closure due to ice pressure in 15 of 23 rock samples. This effect is specially pronounced for schists. (4) We extend Timur's (1968) 2 phase equation with a lithology dependent variable to increase the matrix velocity responding to developing ice pressure while freezing. This study shows the general applicability of refraction seismics in low-porosity permafrost rocks. The expansion of rigid bedrock upon freezing is restricted and, thus, ice pressure will increase matrix velocity. Here, we present a modified "Timur (1968) 2 phase equation" implementing a 4-21 % change in matrix velocity dependent on lithology.

Dräbing, D.; Krautblatter, M.

2012-04-01

120

On the relationship between pedestrian gap acceptance and time to arrival estimates.  

PubMed

The identification of safe gaps between passing cars when crossing a street is a task most of us accomplish successfully on a daily basis. Objectively, how safe a specific gap is, is mainly dependent on how long it would take the approaching vehicle to arrive (time to arrival; TTA). Common sense might suggest that TTA is the basis for pedestrians' gap selection. However, it has been shown repeatedly that vehicle approach speed has a substantial influence on the size of chosen gaps. At higher speeds, pedestrians tend to accept smaller time gaps, i.e. they initiate riskier crossings. Some researchers have gone so far as to suggest that pedestrians rely more on physical distance of a vehicle in their crossing decisions than TTA. Yet, at the same time, there is evidence that TTA estimates themselves are influenced by object approach speed. It is suspected that pedestrians are more apt to base their decisions on systematically distorted TTA estimates, rather than physical distance. The goal of the two experiments described in this article was to explore the relationship between gap acceptance and TTA estimation. Participants were presented with video clips of approaching vehicles, and were either required to indicate a crossing decision, or to estimate TTA. Results show the typical effects of speed (smaller gaps at higher speed, lower TTA estimate at lower speed) and age (larger gaps for older participants). However, when using subjective time gap size (the TTA estimate) instead of objective time gap size to predict gap acceptance, the effect of speed either disappeared (Experiment I) or decreased substantially (Experiment II). The results indicate that systematic differences in TTA estimates can be a reasonable explanation for the effect of speed on gap acceptance. PMID:25035969

Petzoldt, Tibor

2014-11-01

121

Relaxing the closure assumption in single-season occupancy models: staggered arrival and departure times  

USGS Publications Warehouse

Occupancy statistical models that account for imperfect detection have proved very useful in several areas of ecology, including species distribution and spatial dynamics, disease ecology, and ecological responses to climate change. These models are based on the collection of multiple samples at each of a number of sites within a given season, during which it is assumed the species is either absent or present and available for detection while each sample is taken. However, for some species, individuals are only present or available for detection seasonally. We present a statistical model that relaxes the closure assumption within a season by permitting staggered entry and exit times for the species of interest at each site. Based on simulation, our open model eliminates bias in occupancy estimators and in some cases increases precision. The power to detect the violation of closure is high if detection probability is reasonably high. In addition to providing more robust estimation of occupancy, this model permits comparison of phenology across sites, species, or years, by modeling variation in arrival or departure probabilities. In a comparison of four species of amphibians in Maryland we found that two toad species arrived at breeding sites later in the season than a salamander and frog species, and departed from sites earlier.

Kendall, William L.; Hines, James E.; Nichols, James D.; Grant, Evan H. Campbell

2013-01-01

122

Airborne Evaluation and Demonstration of a Time-Based Airborne Inter-Arrival Spacing Tool  

NASA Technical Reports Server (NTRS)

An airborne tool has been developed that allows an aircraft to obtain a precise inter-arrival time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) data to compute speed commands for the ATAAS-equipped aircraft to obtain this inter-arrival spacing behind another aircraft. The tool was evaluated in an operational environment at the Chicago O'Hare International Airport and in the surrounding terminal area with three participating aircraft flying fixed route area navigation (RNAV) paths and vector scenarios. Both manual and autothrottle speed management were included in the scenarios to demonstrate the ability to use ATAAS with either method of speed management. The results on the overall delivery precision of the tool, based on a target spacing of 90 seconds, were a mean of 90.8 seconds with a standard deviation of 7.7 seconds. The results for the RNAV and vector cases were, respectively, M=89.3, SD=4.9 and M=91.7, SD=9.0.

Lohr, Gary W.; Oseguera-Lohr, Rosa M.; Abbott, Terence S.; Capron, William R.; Howell, Charles T.

2005-01-01

123

41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?  

Code of Federal Regulations, 2011 CFR

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2011-07-01

124

41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?  

Code of Federal Regulations, 2012 CFR

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2012-07-01

125

41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?  

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2014-07-01

126

41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?  

Code of Federal Regulations, 2013 CFR

...departure/arrival dates and times on my travel claim? 301-11.10...departure/arrival dates and times on my travel claim? You must record...record departure/arrival times, but you must annotate your travel claim when your travel...

2013-07-01

127

Seismicity and arrival-time residuals from the Victoria Earthquake of June 9, 1980  

SciTech Connect

Hypocenter distribution in space and time of the aftershock activity from the Victoria Earthquake of June 9, 1980 was studied. It was concluded that the main event excited aftershocks in several pre-existing nests at the northwest end of the Cerro Prieto Fault, but no significant activity occurred at the immediate neighborhood of the main event. The depth of the aftershocks increases with the distance from the northwest end of the fault and this feature might be related with the higher temperatures and the spreading center located between the ends of the Imperial and Cerro Prieto Faults. The significance of the arrival-times residuals for local and regional stations is discussed both for P and S-waves and the importance of obtaining station corrections is emphasized. The non-uniqueness in determining a structure which minimizes the residuals is illustrated. Two different structures which satisfy the local data are presented.

Wong, V.; Frez, J.

1981-01-01

128

Extracting Time-Lapsed Velocity Changes From The Direct Arrival Of Ambient Noise Correlation Functions  

NASA Astrophysics Data System (ADS)

This study investigates methods for observing temporal subsurface velocity variations from ambient seismic noise, which provides an exciting opportunity to generate 4D tomographic images. In geologically active regions, the time lag of the ambient Noise Correlation Function (NCF) can change or migrate, reflecting associated changes in the subsurface velocity structure. Unfortunately, this time lag also reflects apparent velocity changes due to seasonal variations in the ambient seismic field as well. Recently, studies have begun observing these temporal variations in volcanic regions by analyzing the changes in the coda of the NCF, and attempting to spatially locate these changes though the examination of the complex scattering regime. Here, we examine time-lagged differences of the main arrival, with the signal to noise ratio of these NCFs being drastically improved by the development of the adaptive covariance filter (ACF). By utilizing velocity variations in these main arrivals, it becomes more straightforward to spatially locate these changes and understand their temporal resolution. We examine two case studies that have different spatial and temporal scales. First, we use all available data near the Yellowstone caldera, including permanent and temporary networks such as the USArray and NOISY projects. We attempt to correct for, and remove, seasonal velocity variations in the NCFs to directly observe decreased velocities at surface wave periods consistent with depths of the magma chamber beneath Yellowstone. Second, we use data from 2009-2011 around Piton de la Fournaise shield volcano on Réunion Island to observe temporal velocity variations associated with eruptive phases. We compare our results of the magnitude and location of these velocity variations to studies observing time-lapsed velocity changes from NCF coda waves.

Seats, K.; Lawrence, J. F.

2013-12-01

129

Sex differences in accuracy and precision when judging time to arrival: data from two Internet studies.  

PubMed

We report two Internet studies that investigated sex differences in the accuracy and precision of judging time to arrival. We used accuracy to mean the ability to match the actual time to arrival and precision to mean the consistency with which each participant made their judgments. Our task was presented as a computer game in which a toy UFO moved obliquely towards the participant through a virtual three-dimensional space on route to a docking station. The UFO disappeared before docking and participants pressed their space bar at the precise moment they thought the UFO would have docked. Study 1 showed it was possible to conduct quantitative studies of spatiotemporal judgments in virtual reality via the Internet and confirmed reports that men are more accurate because women underestimate, but found no difference in precision measured as intra-participant variation. Study 2 repeated Study 1 with five additional presentations of one condition to provide a better measure of precision. Again, men were more accurate than women but there were no sex differences in precision. However, within the coincidence-anticipation timing (CAT) literature, of those studies that report sex differences, a majority found that males are both more accurate and more precise than females. Noting that many CAT studies report no sex differences, we discuss appropriate interpretations of such null findings. While acknowledging that CAT performance may be influenced by experience we suggest that the sex difference may have originated among our ancestors with the evolutionary selection of men for hunting and women for gathering. PMID:21125324

Sanders, Geoff; Sinclair, Kamila

2011-12-01

130

Spectral encoding method for measuring the relative arrival time between x-ray/optical pulses.  

PubMed

The advent of few femtosecond x-ray light sources brings promise of x-ray/optical pump-probe experiments that can measure chemical and structural changes in the 10-100 fs time regime. Widely distributed timing systems used at x-ray Free-Electron Laser facilities are typically limited to above 50 fs fwhm jitter in active x-ray/optical synchronization. The approach of single-shot timing measurements is used to sort results in the event processing stage. This has seen wide use to accommodate the insufficient precision of active stabilization schemes. In this article, we review the current technique for "measure-and-sort" at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The relative arrival time between an x-ray pulse and an optical pulse is measured near the experimental interaction region as a spectrally encoded cross-correlation signal. The cross-correlation provides a time-stamp for filter-and-sort algorithms used for real-time sorting. Sub-10 fs rms resolution is common in this technique, placing timing precision at the same scale as the duration of the shortest achievable x-ray pulses. PMID:25173255

Bionta, M R; Hartmann, N; Weaver, M; French, D; Nicholson, D J; Cryan, J P; Glownia, J M; Baker, K; Bostedt, C; Chollet, M; Ding, Y; Fritz, D M; Fry, A R; Kane, D J; Krzywinski, J; Lemke, H T; Messerschmidt, M; Schorb, S; Zhu, D; White, W E; Coffee, R N

2014-08-01

131

On the Retrieval of Lightning Radio Sources from Time-of-Arrival Data  

NASA Technical Reports Server (NTRS)

We examine the problem of retrieving three-dimensional lightning locations from radio frequency Time-Of-Arrival (TOA) measurements. Arbitrary antenna locations are considered. By judiciously differencing measurements that are related to the location of the antennas and their excitation times, the problem is converted from the initial spherical nonlinear form to a system of linear equations. In the linear formalism, the source location and time-of-occurrence is viewed geometrically as an intersection of hyperplanes in the four-dimensional Minkowski space (x,y,z,t). The linear equations are solved to obtain explicit analytic expressions for the location and time variables. Retrieval errors are not interpreted with conventional Geometrical Dilution of Precision (GDOP) arguments as discussed by Holmes and Reedy (1951), but with more recent inversion analyses considered by Twomey (1977). Measurement errors are propagated analytically so that the specific effect of these errors on the solution is clarified. The sensitivity of the solution on the number of antennas used, antenna network geometry, source position, and measurement differencing schemes are discussed in terms of the eigenvalues of the linear system.

Koshak, William J.; Solakiewicz, Richard J.

1996-01-01

132

Priority Effects of Time of Arrival of Plant Functional Groups Override Sowing Interval or Density Effects: A Grassland Experiment  

PubMed Central

Priority effects occur when species that arrive first in a habitat significantly affect the establishment, growth, or reproduction of species arriving later and thus affect functioning of communities. However, we know little about how the timing of arrival of functionally different species may alter structure and function during assembly. Even less is known about how plant density might interact with initial assembly. In a greenhouse experiment legumes, grasses or forbs were sown a number of weeks before the other two plant functional types were sown (PFT) in combination with a sowing density treatment. Legumes, grasses or non-legume forbs were sown first at three different density levels followed by sowing of the remaining PFTs after three or six-weeks. We found that the order of arrival of different plant functional types had a much stronger influence on aboveground productivity than sowing density or interval between the sowing events. The sowing of legumes before the other PFTs produced the highest aboveground biomass. The larger sowing interval led to higher asymmetric competition, with highest dominance of the PFT sown first. It seems that legumes were better able to get a head-start and be productive before the later groups arrived, but that their traits allowed for better subsequent establishment of non-legume PFTs. Our study indicates that the manipulation of the order of arrival can create priority effects which favour functional groups of plants differently and thus induce different assembly routes and affect community composition and functioning. PMID:24497995

von Gillhaussen, Philipp; Rascher, Uwe; Jablonowski, Nicolai D.; Plückers, Christine; Beierkuhnlein, Carl; Temperton, Vicky M.

2014-01-01

133

Measurement of arrival time of particles in extensive air showers using TDC32  

NASA Astrophysics Data System (ADS)

Arrival time of particles in an extensive air shower (EAS) is a key physical parameter to determine its direction. EAS direction is useful for studies of anisotropy and composition of cosmic rays, and search for multi-TeV ?-rays sources. Accurate timing may be used to search exotic phenomena such as production of new particles at extremely high energies available during early stages of development of EAS and also for detecting sub-relativistic hadrons in EAS. Time to digital converters (TDCs) are used to perform this task. Traditional TDCs operate in the START-STOP mode with limited dynamic range and single-hit capability. With the advent of high luminosity collider LHC, need for TDCs with large dynamic range, multi-hit capability and TRIGGERED mode of operation became necessary. A 32 channel TDC was designed for the GRAPES-3 experiment on a CAMAC platform around TDC32, an ASIC developed by micro-electronics group at CERN, Geneva. Four modules were operated in the GRAPES-3 experiment. Here, we present details of the circuit design and their performance over several years. The multi-hit feature of this device was used to study the time structure of particles in the EAS on time scale of ~1 ?s. The distribution of time intervals in the multi-hit data shows an exponential profile with a time constant of ~370 ns. These delayed particles are likely to be neutrons produced in the EAS core that were recorded in the scintillator detectors following the relativistic EAS front.

Gupta, S. K.; Christiansen, J.; Hayashi, Y.; Jain, A.; Mohanty, P. K.; Ravindran, K. C.; Satyanarayana, B.

2013-04-01

134

A three-dimensional P wave velocity model for the Charlevoix seismic zone, Quebec, Canada  

NASA Astrophysics Data System (ADS)

A three-dimensional P wave velocity model has been developed for the Charlevoix seismic zone (CSZ). The CSZ is located along the St. Lawrence River ˜100 km northeast of Quebec City, Canada, and is one of the most active seismic zones in eastern North America. Five earthquakes with magnitudes equal to or exceeding 6.0 have occurred in the CSZ in historic time, and around 200 earthquakes occur annually. Hypocenters are located in Precambrian basement rocks. Basement rocks have been affected by numerous tectonic events including Grenvillian collision, Iapetan rifting, and meteor impact. We performed a sequential, tomographic inversion for P wave velocity structure based upon 3093 P wave arrivals from 489 earthquakes recorded by 12 stations. High velocity is associated with the center of the impact crater. The region of high velocity is surrounded by low velocities interpreted to be highly disrupted rocks. An elongated, high-velocity region is present at midcrustal depths that trends parallel to the St. Lawrence River. Earthquakes avoid the high-velocity body and separate into two bands, one on either side of the feature. Larger earthquakes (magnitude ? 4) have occurred along the northern edges of the high-velocity region.

Vlahovic, Gordana; Powell, Christine; Lamontagne, Maurice

2003-09-01

135

Ultra-Wideband Time-Difference-of-Arrival High Resolution 3D Proximity Tracking System  

NASA Technical Reports Server (NTRS)

This paper describes a research and development effort for a prototype ultra-wideband (UWB) tracking system that is currently under development at NASA Johnson Space Center (JSC). The system is being studied for use in tracking of lunar./Mars rovers and astronauts during early exploration missions when satellite navigation systems are not available. U IATB impulse radio (UWB-IR) technology is exploited in the design and implementation of the prototype location and tracking system. A three-dimensional (3D) proximity tracking prototype design using commercially available UWB products is proposed to implement the Time-Difference- Of-Arrival (TDOA) tracking methodology in this research effort. The TDOA tracking algorithm is utilized for location estimation in the prototype system, not only to exploit the precise time resolution possible with UWB signals, but also to eliminate the need for synchronization between the transmitter and the receiver. Simulations show that the TDOA algorithm can achieve the fine tracking resolution with low noise TDOA estimates for close-in tracking. Field tests demonstrated that this prototype UWB TDOA High Resolution 3D Proximity Tracking System is feasible for providing positioning-awareness information in a 3D space to a robotic control system. This 3D tracking system is developed for a robotic control system in a facility called "Moonyard" at Honeywell Defense & System in Arizona under a Space Act Agreement.

Ni, Jianjun; Arndt, Dickey; Ngo, Phong; Phan, Chau; Dekome, Kent; Dusl, John

2010-01-01

136

Joint microseismic location and anisotropic tomography using differential arrival times and differential backazimuths  

NASA Astrophysics Data System (ADS)

We develop a new method to locate microseismic events induced by hydraulic fracturing with simultaneous anisotropic tomography, using differential arrival times and differential backazimuths. Compared to the existing double-difference method, our method incorporates backazimuth information to better constrain microseismic locations in the case of downhole linear seismic arrays used for monitoring induced seismicity. The tomography is constrained to a 1-D layered VTI (transversely isotropic structure with a vertical symmetry axis) structure to improve inversion stability given the limited passive seismic data. We derive analytical sensitivities for the elastic moduli (Cij) and layer thickness L, and verify the analytical results with numerical calculations. The forward modelled traveltimes and sensitivities are all calculated analytically without weak anisotropy assumption. By incorporating the relative information among events, the extended double-difference method can provide better relative locations for events and, therefore, can characterize the fractures with higher accuracy. In the two tests with synthetic data, our method provides more accurate relative locations than the traditional methods, which only use absolute information. With fast speed and high accuracy, our inversion scheme is suitable for real-time microseismic monitoring of hydraulic fracturing.

Li, Junlun; Zhang, Haijiang; Rodi, William L.; Toksoz, M. Nafi

2013-12-01

137

Estimating permeability from quasi-static deformation: Temporal variations and arrival time inversion  

SciTech Connect

Transient pressure variations within a reservoir can be treated as a propagating front and analyzed using an asymptotic formulation. From this perspective one can define a pressure 'arrival time' and formulate solutions along trajectories, in the manner of ray theory. We combine this methodology and a technique for mapping overburden deformation into reservoir volume change as a means to estimate reservoir flow properties, such as permeability. Given the entire 'travel time' or phase field, obtained from the deformation data, we can construct the trajectories directly, there-by linearizing the inverse problem. A numerical study indicates that, using this approach, we can infer large-scale variations in flow properties. In an application to Interferometric Synthetic Aperture (InSAR) observations associated with a CO{sub 2} injection at the Krechba field, Algeria, we image pressure propagation to the northwest. An inversion for flow properties indicates a linear trend of high permeability. The high permeability correlates with a northwest trending fault on the flank of the anticline which defines the field.

Vasco, D.W.; Ferretti, Alessandro; Novali, Fabrizio

2008-05-01

138

Evaluation of Operational Procedures for Using a Time-Based Airborne Inter-arrival Spacing Tool  

NASA Technical Reports Server (NTRS)

An airborne tool has been developed based on the concept of an aircraft maintaining a time-based spacing interval from the preceding aircraft. The Advanced Terminal Area Approach Spacing (ATAAS) tool uses Automatic Dependent Surveillance-Broadcast (ADS-B) aircraft state data to compute a speed command for the ATAAS-equipped aircraft to obtain a required time interval behind another aircraft. The tool and candidate operational procedures were tested in a high-fidelity, full mission simulator with active airline subject pilots flying an arrival scenario using three different modes for speed control. The objectives of this study were to validate the results of a prior Monte Carlo analysis of the ATAAS algorithm and to evaluate the concept from the standpoint of pilot acceptability and workload. Results showed that the aircraft was able to consistently achieve the target spacing interval within one second (the equivalent of approximately 220 ft at a final approach speed of 130 kt) when the ATAAS speed guidance was autothrottle-coupled, and a slightly greater (4-5 seconds), but consistent interval with the pilot-controlled speed modes. The subject pilots generally rated the workload level with the ATAAS procedure as similar to that with standard procedures, and also rated most aspects of the procedure high in terms of acceptability. Although pilots indicated that the head-down time was higher with ATAAS, the acceptability of head-down time was rated high. Oculometer data indicated slight changes in instrument scan patterns, but no significant change in the amount of time spent looking out the window between the ATAAS procedure versus standard procedures.

Oseguera-Lohr, Rosa M.; Lohr, Gary W.; Abbott, Terence S.; Eischeid, Todd M.

2002-01-01

139

Fault zone structure determined through the analysis of earthquake arrival times  

SciTech Connect

This thesis develops and applies a technique for the simultaneous determination of P and S wave velocity models and hypocenters from a set of arrival times. The velocity models are parameterized in terms of cubic B-splines basis functions which permit the retrieval of smooth models that can be used directly for generation of synthetic seismograms using the ray method. In addition, this type of smoothing limits the rise of instabilities related to the poor resolving power of the data. V{sub P}/V{sub S} ratios calculated from P and S models display generally instabilities related to the different ray-coverages of compressional and shear waves. However, V{sub P}/V{sub S} ratios are important for correct identification of rock types and this study introduces a new methodology based on adding some coupling (i.e., proportionality) between P and S models which stabilizes the V{sub P}/V{sub S} models around some average preset value determined from the data. Tests of the technique with synthetic data show that this additional coupling regularizes effectively the resulting models.

Michelini, A.

1991-10-01

140

Enhancing the estimation of blood pressure using pulse arrival time and two confounding factors.  

PubMed

A new method of blood pressure (BP) estimation using multiple regression with pulse arrival time (PAT) and two confounding factors was evaluated in clinical and unconstrained monitoring situations. For the first analysis with clinical data, electrocardiogram (ECG), photoplethysmogram (PPG) and invasive BP signals were obtained by a conventional patient monitoring device during surgery. In the second analysis, ECG, PPG and non-invasive BP were measured using systems developed to obtain data under conditions in which the subject was not constrained. To enhance the performance of BP estimation methods, heart rate (HR) and arterial stiffness were considered as confounding factors in regression analysis. The PAT and HR were easily extracted from ECG and PPG signals. For arterial stiffness, the duration from the maximum derivative point to the maximum of the dicrotic notch in the PPG signal, a parameter called TDB, was employed. In two experiments that normally cause BP variation, the correlation between measured BP and the estimated BP was investigated. Multiple-regression analysis with the two confounding factors improved correlation coefficients for diastolic blood pressure and systolic blood pressure to acceptable confidence levels, compared to existing methods that consider PAT only. In addition, reproducibility for the proposed method was determined using constructed test sets. Our results demonstrate that non-invasive, non-intrusive BP estimation can be obtained using methods that can be applied in both clinical and daily healthcare situations. PMID:20009186

Baek, Hyun Jae; Kim, Ko Keun; Kim, Jung Soo; Lee, Boreom; Park, Kwang Suk

2010-02-01

141

Annual variation in arrival and departure times of carrion insects at carcasses: implications for succession studies in forensic entomology  

Microsoft Academic Search

A succession of insect species associate with decaying bodies, and because of the relatively predictable arrival and departure times of many species, this process is routinely used to estimate minimum post-mortem interval. Corpse fauna are compared with baseline data on succession rates, which are usually taken from decomposing animal carcasses. Baseline data are traditionally collected over a single year only;

M. S. Archer

2003-01-01

142

The Development of a General Associative Learning Account of Skill Acquisition in a Relative Arrival-Time Judgment Task  

ERIC Educational Resources Information Center

Current theory assumes that individuals only use information from the immediate environment to perform relative arrival-time judgment tasks. This article presents a theoretical analysis of the memory requirements of this task. The authors present an analysis of the inputs to the memory system and the processes that map those inputs onto outputs.…

Loft, Shayne; Neal, Andrew; Humphreys, Michael S.

2007-01-01

143

Time-domain geometrical localization of point-like fluorescence inclusions in turbid media with early photon arrival times.  

PubMed

We introduce a novel approach for localizing a plurality of discrete point-like fluorescent inclusions embedded in a thick turbid medium using time-domain measurements. The approach uses early photon information contained in measured time-of-flight distributions originating from fluorescence emission. Fluorescence time point-spread functions (FTPSFs) are acquired with ultrafast time-correlated single photon counting after short pulse laser excitation. Early photon arrival times are extracted from the FTPSFs obtained from several source-detector positions. Each source-detector measurement allows defining a geometrical locus where an inclusion is to be found. These loci take the form of ovals in 2D or ovoids in 3D. From these loci a map can be built, with the maxima thereof corresponding to positions of inclusions. This geometrical approach is supported by Monte Carlo simulations performed for biological tissue-like media with embedded fluorescent inclusions. To validate the approach, several experiments are conducted with a homogeneous phantom mimicking tissue optical properties. In the experiments, inclusions filled with indocyanine green are embedded in the phantom and the fluorescence response to a short pulse of excitation laser is recorded. With our approach, several inclusions can be localized with low millimeter positional error. Our results support the approach as an accurate, efficient, and fast method for localizing fluorescent inclusions embedded in highly turbid media mimicking biological tissues. Further Monte Carlo simulations on a realistic mouse model show the feasibility of the technique for small animal imaging. PMID:24085003

Pichette, Julien; Domínguez, Jorge Bouza; Bérubé-Lauzière, Yves

2013-08-20

144

Effects of a Longer Detection Window in VHF Time-of-Arrival Lightning Detection Systems  

NASA Astrophysics Data System (ADS)

Lightning detection systems that operate by measuring the times of arrival (TOA) of short bursts of radiation at VHF can produce huge volumes of data. The first automated system of this kind, the NASA Kennedy Space Center LDAR network, is capable of producing one detection every 100 usec from each of seven sensors (Lennon and Maier, 1991), where each detection consists of the time and amplitude of the highest-amplitude peak observed within the 100 usec window. More modern systems have been shown to produce very detailed information with one detection every 10 usec (Rison et al., 2001). Operating such systems in real time, however, can become expensive because of the large data communications rates required. One solution to this problem is to use a longer detection window, say 500 usec. In principle, this has little or no effect on the flash detection efficiency because each flash typically produces a very large number of these VHF bursts (known as sources). By simply taking the largest-amplitude peak from every 500-usec interval instead of every 100-usec interval, we should detect the largest 20{%} of the sources that would have been detected using the 100-usec window. However, questions remain about the exact effect of a longer detection window on the source detection efficiency with distance from the network, its effects on how well flashes are represented in space, and how well the reduced information represents the parent thunderstorm. The latter issue is relevant for automated location and tracking of thunderstorm cells using data from VHF TOA lightning detection networks, as well as for understanding relationships between lightning and severe weather. References Lennon, C.L. and L.M. Maier, Lightning mapping system. Proceedings, Intl. Aerospace and Ground Conf. on Lightning and Static Elec., Cocoa Beach, Fla., NASA Conf. Pub. 3106, vol. II, pp. 89-1 - 89-10, 1991. Rison, W., P. Krehbiel, R. Thomas, T. Hamlin, J. Harlin, High time resolution lightning mapping observations of a small thunderstorm during STEPS. Eos Trans. AGU, 82 (47), Fall Meet. Suppl., Abstract AE12A-83, 2001.

Murphy, M.; Holle, R.; Demetriades, N.

2003-12-01

145

Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease.  

PubMed

Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD. PMID:25379411

Al-Bachari, Sarah; Parkes, Laura M; Vidyasagar, Rishma; Hanby, Martha F; Tharaken, Vivek; Leroi, Iracema; Emsley, Hedley C A

2014-01-01

146

Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease  

PubMed Central

Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD. PMID:25379411

Al-Bachari, Sarah; Parkes, Laura M.; Vidyasagar, Rishma; Hanby, Martha F.; Tharaken, Vivek; Leroi, Iracema; Emsley, Hedley C.A.

2014-01-01

147

`Inter-Arrival Time' Inspired Algorithm and its Application in Clustering and Molecular Phylogeny  

NASA Astrophysics Data System (ADS)

Bioinformatics, being multidisciplinary field, involves applications of various methods from allied areas of Science for data mining using computational approaches. Clustering and molecular phylogeny is one of the key areas in Bioinformatics, which help in study of classification and evolution of organisms. Molecular phylogeny algorithms can be divided into distance based and character based methods. But most of these methods are dependent on pre-alignment of sequences and become computationally intensive with increase in size of data and hence demand alternative efficient approaches. `Inter arrival time distribution' (IATD) is a popular concept in the theory of stochastic system modeling but its potential in molecular data analysis has not been fully explored. The present study reports application of IATD in Bioinformatics for clustering and molecular phylogeny. The proposed method provides IATDs of nucleotides in genomic sequences. The distance function based on statistical parameters of IATDs is proposed and distance matrix thus obtained is used for the purpose of clustering and molecular phylogeny. The method is applied on a dataset of 3' non-coding region sequences (NCR) of Dengue virus type 3 (DENV-3), subtype III, reported in 2008. The phylogram thus obtained revealed the geographical distribution of DENV-3 isolates. Sri Lankan DENV-3 isolates were further observed to be clustered in two sub-clades corresponding to pre and post Dengue hemorrhagic fever emergence groups. These results are consistent with those reported earlier, which are obtained using pre-aligned sequence data as an input. These findings encourage applications of the IATD based method in molecular phylogenetic analysis in particular and data mining in general.

Kolekar, Pandurang S.; Kale, Mohan M.; Kulkarni-Kale, Urmila

2010-10-01

148

Characterizing the nonlinear interaction of S- and P-waves in a rock sample  

NASA Astrophysics Data System (ADS)

The nonlinear elastic response of rocks is known to be caused by the rocks' microstructure, particularly cracks and fluids. This paper presents a method for characterizing the nonlinearity of rocks in a laboratory scale experiment with a unique configuration. This configuration has been designed to open up the possibility of using the nonlinear characterization of rocks as an imaging tool in the field. In our experiment, we study the nonlinear interaction of two traveling waves: a low-amplitude 500 kHz P-wave probe and a high-amplitude 50 kHz S-wave pump in a room-dry 15 × 15 × 3 cm slab of Berea sandstone. Changes in the arrival time of the P-wave probe as it passes through the perturbation created by the traveling S-wave pump were recorded. Waveforms were time gated to simulate a semi-infinite medium. The shear wave phase relative to the P-wave probe signal was varied with resultant changes in the P-wave probe arrival time of up to 100 ns, corresponding to a change in elastic properties of 0.2%. In order to estimate the strain in our sample, we also measured the particle velocity at the sample surface to scale a finite difference linear elastic simulation to estimate the complex strain field in the sample, on the order of 10-6, induced by the S-wave pump. We derived a fourth order elastic model to relate the changes in elasticity to the pump strain components. We recover quadratic and cubic nonlinear parameters: ? ˜ = - 872 and ? ˜ = - 1.1 × 10 10 , respectively, at room-temperature and when particle motions of the pump and probe waves are aligned. Temperature fluctuations are correlated to changes in the recovered values of ? ˜ and ? ˜ , and we find that the nonlinear parameter changes when the particle motions are orthogonal. No evidence of slow dynamics was seen in our measurements. The same experimental configuration, when applied to Lucite and aluminum, produced no measurable nonlinear effects. In summary, a method of selectively determining the local nonlinear characteristics of rock quantitatively has been demonstrated using traveling sound waves.

Gallot, Thomas; Malcolm, Alison; Szabo, Thomas L.; Brown, Stephen; Burns, Daniel; Fehler, Michael

2015-01-01

149

Operational warning of interplanetary shock arrivals using energetic particle data from ACE: Real-time Upstream Monitoring System  

NASA Astrophysics Data System (ADS)

We report on an operational system which provides advance warning and predictions of arrival times at Earth of interplanetary (IP) shocks that originate at the Sun. The data stream used in our prediction algorithm is real-time and comes from the Electron, Proton, and Alpha Monitor (EPAM) instrument on NASA's Advanced Composition Explorer (ACE) spacecraft. Since locally accelerated energetic storm particle (ESP) events accompany most IP shocks, their arrival can be predicted using ESP event signatures. We have previously reported on the development and implementation of an algorithm which recognizes the upstream particle signature of approaching IP shocks and provides estimated countdown predictions. A web-based system (see (http://sd-www.jhuapl.edu/UPOS/RISP/index.html) combines this prediction capability with real-time ACE/EPAM data provided by the NOAA Space Environment Center. The most recent ACE data is continually processed and predictions of shock arrival time are updated every five minutes when an event is impending. An operational display is provided to indicate advisories and countdowns for the event. Running the algorithm on a test set of historical events, we obtain a median error of about 10 hours for predictions made 24-36 hours before actual shock arrival and about 6 hours when the shock is 6-12 hours away. This system can provide critical information to mission planners, satellite operations controllers, and scientists by providing significant lead-time for approaching events. Recently, we have made improvements to the triggering mechanism as well as re-training the neural network, and here we report prediction results from the latest system.

Donegan, M.; Vandegriff, J.; Ho, G. C.; Julia, S. J.

2004-12-01

150

The two-dimensional source location problem for time differences of arrival at minimal element monitoring arrays.  

PubMed

The time difference of arrival (TDOA) source localization inverse problem is analyzed for two-dimensional signal propagation detected by a small number of sensor elements in a monitoring array. Nonlinear least-squares solutions are found based on the assumptions of geodesic rays propagating at constant speed. The two-dimensional (2D) TDOA source location problem is shown in the case of three sensors to have dual possible solutions for some combinations of arrival time differences. In the case of four non-collinear sensors, there are unique solutions for all physically possible combinations of time differences. Dual solutions to the three-sensor problem are associated with a small range of arrival time differences but large regions in physical space. The locations of the dual solutions are separated by a wide variety of distances, which in some cases prevent the use of alternative reasoning to remove the ambiguity. Three-sensor TDOA cannot be reliably used for 2D source location unless the source is a priori known to be within either the spatial region spanned by the sensor array or the external zones of unique solution. Determining the minimum number of sensors necessary to unambiguously solve the source location problem assists in cost-effective design of sensor arrays. PMID:17552709

Spencer, Steven J

2007-06-01

151

Experimental demonstration of a method to realize weak measurement of the arrival time of a single photon  

SciTech Connect

We present a realization of weak measurement for the arrival time of a single photon in virtue of the simultaneous characteristic of biphotons. Our experimental setup is based on a Hong-Ou-Mandel interferometer. A birefringent crystal is used to perform weak measurement between a preselected and a postselected measurement by two polarizers. The extreme weak values lie well outside of the eigenvalues of the observable.

Wang Qin; Sun Fangwen; Zhang Yongsheng; Jian Li; Huang Yunfeng; Guo Guangcan [Key Laboratory of Quantum Information, Department of Physics, University of Science and Technology of China, Hefei 230026 (China)

2006-02-15

152

A new analysis method of single molecule fluorescence using series of photon arrival times: theory and experiment  

NASA Astrophysics Data System (ADS)

Up to now, single molecule fluorescence experiments were performed by dividing the time into a set of intervals and to observe the number of fluorescence photons arriving in each interval. It is obvious that the detected photons carry less information than the arrival times of the photons themselves. From the arrival times, one can still calculate the number of photons in any user-defined interval; whereas, when only the number of photons in an interval are recorded, information about their positions in time is lost. Therefore, we present a new analysis method of single molecule fluorescence data based on the positions in time of the detected fluorescence photons. We derive mathematically different statistical characteristics describing the single molecule fluorescence experiment assuming an immobilized molecule. The theory of point processes using the generating functionals formalism is ideally suited for a consistent description, linking the statistical characteristics of the excitation and detected photons to the statistical characteristics of the single motionless molecule. We then use computer-generated data sets mimicking the single molecule fluorescence experiment to explore the parametric estimation of mono- and bi-exponential single molecule impulse response functions (SMIRFs) via the following statistical characteristics: the probability density distributions (pdd) of the single and first photocount time positions in a user-defined detection interval, the probability distribution of the number of photocounts per user-defined detection interval, the time correlation function and the pdd of the time interval between two consecutive photocounts. It is shown that all of the above characteristics ensure a satisfactory recovery of the decay time of mono-exponential SMIRFs for a broad range of excitation intensities and widths of user-defined detection intervals. For bi-exponential SMIRFs, the selection of the experimental conditions is more critical and dependent on the detection procedure. At lower excitation intensities it is advantageous to use the pdds of the single and first photocount time occurrences in the user-defined detection interval. To show the practical usefulness of the new analysis method, series of photon arrival times from immobilized single molecules of DiI and rhodamine 6G were analyzed to estimate triplet lifetimes and intersystem crossing yields.

Novikov, Eugene; Hofkens, Johan; Cotlet, Mircea; Maus, Michael; De Schryver, Frans C.; Boens, Noël

2001-09-01

153

Three-dimensional P-wave velocity structure of Mt. Etna, Italy  

USGS Publications Warehouse

The three-dimensional P-wave velocity structure of Mt. Etna is determined to depths of 15 km by tomographic inversion of first arrival times from local earthquakes recorded by a network of 29 permanent and temporary seismographs. Results show a near-vertical low-velocity zone that extends from beneath the central craters to a depth of 10 km. This low-velocity region is coincident with a band of steeply-dipping seismicity, suggesting a magmatic conduit that feeds the summit eruptions. The most prominent structure is an approximately 8-km-diameter high-velocity body located between 2 and 12 km depth below the southeast flank of the volcano. This high-velocity body is interpreted as a remnant mafic intrusion that is an important structural feature influencing both volcanism and east flank slope stability and faulting.

Villasenor, A.; Benz, H.M.; Filippi, L.; De Luca, G.; Scarpa, R.; Patane, G.; Vinciguerra, S.

1998-01-01

154

Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles  

DOEpatents

An apparatus for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously.

Benjamin, R.F.

1983-10-18

155

Optical pin apparatus for measuring the arrival time and velocity of shock waves and particles  

DOEpatents

An apparatus is disclosed for the detection of the arrival and for the determination of the velocity of disturbances such as shock-wave fronts and/or projectiles. Optical pins using fluid-filled microballoons as the light source and an optical fiber as a link to a photodetector have been used to investigate shock-waves and projectiles. A microballoon filled with a noble gas is affixed to one end of a fiber-optic cable, and the other end of the cable is attached to a high-speed streak camera. As the shock-front or projectile compresses the microballoon, the gas inside is heated and compressed producing a bright flash of light. The flash of light is transmitted via the optic cable to the streak camera where it is recorded. One image-converter streak camera is capable of recording information from more than 100 microballoon-cable combinations simultaneously. 3 figs.

Benjamin, R.F.

1987-03-10

156

P-Wave Wave in a Slinky  

NSDL National Science Digital Library

This animation shows how P-waves (primary, or compressional, waves) travel through a Slinky toy. It is accompanied by a brief written explanation that describes some of the properties of P-waves and how they are generated in a real Slinky.

John Lahr

157

Upper Mantle P-Wave Teleseismic Tomography Beneath the Jalisco Block, Mexico  

NASA Astrophysics Data System (ADS)

Two major seismological problems are tracking the true path the waves take through the earth and improve event location. Seismic tomography deals with both. The present project is intended to obtain a high quality estimate of the upper mantle P-wave velocity distribution of the Jalisco Block region. The results obtained allow a delimitation of lithospheres of different composition and the identification of subducted material. The study area is located in the Western's most central part of Mexico and is characterized by the fragmentation of the North American plate and the subduction of the Cocos and Rivera slabs. Using an iterative wavefront tracking method called the Fast Marching Teleseismic Tomography (FMTT) implemented by N. Rawlinson et al. (2006) we obtained a set of tomographic slices at depth and in the NS & EW direction which represent the internal P-wave velocity distribution at depths from ~50 km to 350 km. The inversión comprises 150 teleseismic events with good signal to noise ratio, magnitudes ? 5.3 and epicentral distances between 30° and 97°, recorded by the Mapping the Rivera Subduction Zone (MARS) temporary network and the RESAJ (Seismological and Accelerometrical Network of Jalisco). The set of relative arrival time residuals extracted from the seismograms were obtained using the Multi-Channel Cross-Correlation (MCCC) method of VanDecar and Crosson (1990), such residuals are presented as 3D P-wave anomalies, deviated from the unidimensional reference model ak135. Solution robustness is verified through the reconstruction of synthetic checkerboard tests, we also performed a trade-off analysis with the generation of L-curves which helped to determine the most appropiate damping and smoothing regularization terms, commonly applied to deal with solution non-uniqueness. Preliminary NS tomographic slices generated with a set of 58 events show high velocity anomalies with a geometry that resembles a subducting slab along longitudes -103.5 and -105.5

Perez, O. G.; Escudero, C. R.; Nunez-Cornu, F. J.

2012-12-01

158

Mapping of shallow three dimensional variations of P-wave velocity in Garhwal Himalaya  

NASA Astrophysics Data System (ADS)

A set of short aperture seismic arrays was operated in the Garhwal Himalaya close to the Main Central Thrust and recorded a large number of small local earthquakes. This study pertains to the inversion of the body wave arrival time data of these earthquakes to construct a seismic velocity model for the region. The analysis indicates a systematic variation in the P-wave velocities of the upper crustal rocks. We estimate (i) significantly lower seismic velocities within the Middle-Lesser Garhwal Himalaya, and (ii) higher seismic velocities in the interface zone between the Middle-Lesser and Higher Garhwal Himalaya. Seismic activity is mostly confined to a relatively narrow north-east dipping zone in the upper 4 km of the crust characterized by a relatively higher P-wave velocity. This active seismicity represents reverse thrusting along steep north-easterly dipping parallel slip surfaces within this zone forming a ramp in the crystalline formations of Higher Himalaya. The lower velocity zone exhibits a low level of seismicity but appears to be associated with an increased landslide hazard.

Sarkar, I.; Jain, R.; Khattri, K. N.

2001-02-01

159

Alignment of leading-edge and peak-picking time of arrival methods to obtain accurate source locations  

SciTech Connect

The location of a radiating source can be determined by time-tagging the arrival of the radiated signal at a network of spatially distributed sensors. The accuracy of this approach depends strongly on the particular time-tagging algorithm employed at each of the sensors. If different techniques are used across the network, then the time tags must be referenced to a common fiducial for maximum location accuracy. In this report we derive the time corrections needed to temporally align leading-edge, time-tagging techniques with peak-picking algorithms. We focus on broadband radio frequency (RF) sources, an ionospheric propagation channel, and narrowband receivers, but the final results can be generalized to apply to any source, propagation environment, and sensor. Our analytic results are checked against numerical simulations for a number of representative cases and agree with the specific leading-edge algorithm studied independently by Kim and Eng (1995) and Pongratz (2005 and 2007).

Roussel-Dupre, R.; Symbalisty, E.; Fox, C.; and Vanderlinde, O.

2009-08-01

160

The gravity dual of a p-wave superconductor  

E-print Network

We construct black hole solutions to the Yang-Mills equations in an AdS_4-Schwarzschild background which exhibit superconductivity. What makes these backgrounds p-wave superconductors is that the order parameter is a vector, and the conductivities are strongly anisotropic in a manner that is suggestive of a gap with nodes. The low-lying excitations of the normal state have a relaxation time which grows rapidly as the temperature decreases, consistent with the absence of impurity scattering. A numerical exploration of quasinormal modes close to the transition temperature suggests that p-wave backgrounds are stable against perturbations analogous to turning on a p+ip gap, whereas p+ip-wave configurations are unstable against turning into pure p-wave backgrounds.

Gubser, Steven S

2008-01-01

161

The gravity dual of a p-wave superconductor  

NASA Astrophysics Data System (ADS)

We construct black hole solutions to the Yang-Mills equations in an AdS4-Schwarzschild background which exhibit superconductivity. What makes these backgrounds p-wave superconductors is that the order parameter is a vector, and the conductivities are strongly anisotropic in a manner that is suggestive of a gap with nodes. The low-lying excitations of the normal state have a relaxation time which grows rapidly as the temperature decreases, consistent with the absence of impurity scattering. A numerical exploration of quasinormal modes close to the transition temperature suggests that p-wave backgrounds are stable against perturbations analogous to turning on a p+ip gap, whereas p+ip-wave configurations are unstable against turning into pure p-wave backgrounds.

Gubser, Steven S.; Pufu, Silviu S.

2008-11-01

162

41 CFR 301-11.10 - Am I required to record departure/arrival dates and times on my travel claim?  

Code of Federal Regulations, 2010 CFR

...arrival dates and times on my travel claim? 301-11.10 Section 301-11.10 Public Contracts and Property Management Federal...TDY) TRAVEL ALLOWANCES ALLOWABLE TRAVEL EXPENSES 11-PER DIEM EXPENSES General Rules §...

2010-07-01

163

On the possibility to discriminate the mass of the primary cosmic ray using the muon arrival times from extensive air showers: Application for Pierre Auger Observatory  

SciTech Connect

In this paper we study the possibility to discriminate the mass of the primary cosmic ray by observing the muon arrival times in ground detectors. We analyzed extensive air showers (EAS) induced by proton and iron nuclei with the same energy 8 Multiplication-Sign 10{sup 17} eV simulated with CORSIKA, and analyzed the muon arrival times at ground measured by the infill array detectors of the Pierre Auger Observatory (PAO). From the arrival times of the core and of the muons the atmospheric depth of muon generation locus is evaluated. The results suggest a potential mass discrimination on the basis of muon arrival times and of the reconstructed atmospheric depth of muon production. An analysis of a larger set of CORSIKA simulations carried out for primary energies above 10{sup 18} eV is in progress.

Arsene, N.; Rebel, H.; Sima, O. [Institute of Space Science (ISS), Bucharest-Magurele, P.O. Box MG-23 (Romania) and Physics Department, University of Bucharest, Bucharest-Magurele (Romania); Karlsruhe Institute of Technology, Karlsruhe (Germany); Physics Department, University of Bucharest, Bucharest-Magurele (Romania)

2012-11-20

164

First arrival time tomography for a near vertical reflection seismic profile in the Kaokoland region in Northern Namibia - first results  

NASA Astrophysics Data System (ADS)

Within the LISPWAL project (part of the SAMPLE SPP), in 2012 a Near Vertical Reflection (NVR) Seismic profile was generated in the Kaokoland region in Northern Namibia. 150 (25kg) controlled source shots at ~1350 m spacing were conducted along a 200 km North-South profile. A spread of 300 seismic stations, spaced 100 m apart, was moved in a roll-along style, to collect data suitable for standard reflection seismic processing and first arrival time tomography. Travel time data of seismic phases are used as input data to derive shallow velocity models of compressional waves (P), shear waves (S) and the Vp/Vs ratio. Using First Arrival Seismic Tomography (FAST) software, we derive shallow tomographic models for the upper 1 to 1.5 km. All three models are characterized by significant differences between the northern and the southern part. In the south P- and S-velocities are higher and Vp/Vs ratios lower while in the north the P- and S-velocities are lower while the Vp/Vs ratios show higher values.

Braeuer, Benjamin; Ryberg, Trond; Haberland, Christian; Bauer, Klaus; Weber, Michael

2014-05-01

165

Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory and Ulysses  

NASA Technical Reports Server (NTRS)

Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to approximately 2 deg accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at approximately 1 min x 4 min, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.

Laros, J. G.; Boynton, W. V.; Hurley, K.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.

1997-01-01

166

A Simulation Study of Linsley's Approach to infer Elongation Rate and Fluctuations of the EAS Maximum Depth from Muon Arrival Time Distributions  

NASA Astrophysics Data System (ADS)

An indirect approach to deduce the elongation rate De and the fluctuations of the atmospheric depth Xm of the EAS maximum from muon arrival time distributions has been scrutinized on basis of Monte Carlo simulations of the EAS development and of the longitudinal profile of various EAS parameters. Special attention is made to the behaviour of a scaling parameter relating the variations at the height of the shower maximum to the arrival time of muons at observation level.

Badea, Florin A.

167

A simulation based study of Linsley's approach to infer the elongation rate and fluctuations of the EAS maximum depth from muon arrival time distributions  

NASA Astrophysics Data System (ADS)

An indirect approach to deduce the elongation rate De and the fluctuations of the atmospheric depth Xm of the extensive air showers (EAS) maximum from muon arrival time distributions has been scrutinised on basis of Monte Carlo simulations of the EAS development and of the longitudinal profile of various EAS parameters. Special attention is given to the behaviour of a scaling parameter relating the variations of the muon arrival times registered at the observation level to the height of the shower maximum.

Badea, A. F.; Rebel, H.; Zazyan, M.; Brancus, I. M.; Haungs, A.; Oehlschläger, J.

2001-03-01

168

A one-particle time of arrival operator for a free relativistic spin- 0 charged particle in (1 + 1) dimensions  

NASA Astrophysics Data System (ADS)

We construct a one-particle TOA operator T ˆ canonically conjugate with the Hamiltonian describing a free, charged, spin- 0, relativistic particle in one spatial dimension and show that it is maximally symmetric. We solve for its eigenfunctions and show that they form a complete and non-orthogonal set. Plotting the time evolution of their corresponding probability densities, it implies that the eigenfunctions become more localized at the origin at the time equal to their eigenvalues. That is, a particle being described by an eigenfunction of T ˆ is in a state of definite arrival time at the origin and at the corresponding eigenvalue. We also calculate the TOA probability distribution of a particle in some initial state.

Bunao, Joseph; Galapon, Eric A.

2015-02-01

169

ESTIMATING THE ARRIVAL TIME OF EARTH-DIRECTED CORONAL MASS EJECTIONS AT IN SITU SPACECRAFT USING COR AND HI OBSERVATIONS FROM STEREO  

SciTech Connect

Predicting the arrival time and transit speed of coronal mass ejections (CMEs) near the Earth is critical to understanding the solar-terrestrial relationship. Even though STEREO observations now provide multiple views of CMEs in the heliosphere, the true speeds derived from stereoscopic reconstruction of SECCHI coronagraph data are not quite sufficient for accurate forecasting of the arrival time at Earth of a majority of CMEs. This uncertainty is due to many factors that change CME kinematics, such as the interaction of two or more CMEs or the interaction of CMEs with the pervading solar wind. In order to understand the propagation of CMEs, we have used the three-dimensional triangulation method on SECCHI coronagraph (COR2) images and geometric triangulation on the J-maps constructed from Heliospheric Imagers HI1 and HI2 data for eight Earth-directed CMEs observed during 2008-2010. Based on the reconstruction, and implementing the drag-based model for the distance where the CMEs could not be tracked unambiguously in the interplanetary (IP) medium, the arrival time of these CMEs have been estimated. These arrival times have also been compared with the actual arrival times as observed by in situ instruments. The analysis reveals the importance of heliospheric imaging for improved forecasting of the arrival time and direction of propagation of CMEs in the IP medium.

Mishra, Wageesh; Srivastava, Nandita, E-mail: wageesh@prl.res.in [Udaipur Solar Observatory, Physical Research Laboratory, P.O. Box 198, Badi Road, Udaipur 313 001 (India)

2013-07-20

170

Nie and Fan THE ARRIVING ON TIME PROBLEM: A DISCRETE ALGORITHM THAT ENSURES  

E-print Network

have been introduced, including expected travel time, reliability, value at risk, expectation adaptive optimal path algorithms focus on least expected travel time. Recently, we have proposed an adaptive path finding strategy, named as the SOTA algorithm, to maximize the travel time reliability

Fan, Yueyue

171

Polishing the Right Apple: Anytime Classification Also Benefits Data Streams with Constant Arrival Times  

Microsoft Academic Search

Classification of items taken from data streams requires algorithms that operate in time sensitive and computationally constrained environments. Often, the available time for classification is not known a priori and may change as a consequence of external circumstances. Many traditional algorithms are unable to provide satisfactory performance while supporting the highly variable response times that exemplify such applications. In such

Jin Shieh; Eamonn J. Keogh

2010-01-01

172

Lightning First Pulses Used in the "Last" (Time-of-Arrival) and "Atlas" (Single Station) Total Lightning Mapping Systems  

NASA Technical Reports Server (NTRS)

The first RF pulse from "total lightning' discharges (cloud and ground flashes) has been used in different ways to locate the origin of flashes in two new types of lightning detection systems. The multisensor LASI time-of-arrival (TOA) system uses GPS timing of the first pulse. The ATLAS single sensor system uses the amplitude of the first pulse, which is invariant in magnitude and polarization for all lightning discharges, to determine distance from the sensor. It is significantly more accurate than past single sensor lightning mapping systems. The polarity of the first pulse generally identifies lightning type (IC or CG). Both systems utilize only the first pulse which makes signal processing much simpler than with previous lightning locating systems. Knowing the position where lightning begins (maximum electric fields, mixed phase hydrometeors and updrafts) is valuable for identifying convective cells producing the hazardous meteorological conditions caused by thunderstorms. It is also important for research studying thunderstorm electrification and associated microphysical problems.

Markson, Ralph; Ruhnke, Lothar

1999-01-01

173

[Development of estimated time of arrival method and usefulness in pulmonary artery/vein separation 3D-CT].  

PubMed

We have developed an estimated time of arrival (ETA) method as a new single-phase scan for pulmonary artery/vein separation. This method enables differentiation of CT values between arteries and veins by means of two-step consecutive injection of contrast medium based on the pulmonary circulation time. This paper presents an overview of the ETA method and scan technique. Since the ETA method is a single-phase scan, it uses a low radiation dose compared with the conventional multi-phase scan. Moreover, this method eliminates gaps due to breath holding. The ETA method can detect irregularities and obtain high-quality pulmonary artery/vein separation 3D-CT images. PMID:25410332

Nakamori, Katsutoshi; Nagasawa, Naoki; Yamazaki, Akio; Kubooka, Naoya; Yamao, Yoshikazu; Murashima, Syuichi; Fujita, Makiko; Takao, Motoshi; Tenpaku, Hironori; Shimamoto, Akira; Maki, Hiroaki; Sakuma, Hajime

2014-11-01

174

Multifactor Poisson and Gamma-Poisson models for call center arrival times  

E-print Network

of the performance of the queuing system. The models can also be used to predict future call volumes or workloads quality (measured by the waiting time of calls). To achieve the balance, they use queueing

Brown, Lawrence D.

175

Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1987 Annual Report.  

SciTech Connect

This project monitored the daily passage of smolts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clearwater rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time. 10 figs, 15 tabs.

Buettner, Edwin W.; Nelson, V. Lance

1990-01-01

176

Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1988 Annual Report.  

SciTech Connect

This project monitored the daily passage of smelts during the 1988 spring outmigration at two migrant traps; one each on the Snake and Clear-water rivers. Due to the low runoff year, chinook salmon catch at the Snake River trap was very low. Steelhead trout catch was higher than normal, probably due to trap modifications and because the trap was moved to the east side of the river. Chinook salmon and steelhead trout catch at the Clearwater River trap was similar to 1987. Total cumulative recovery of PIT tagged fish at the three dams, with PIT tag detection systems was: 55% for chinook salmon, 73% for hatchery steelhead trout, and 75% for wild steelhead trout. Travel time through Lower Granite Reservoir for PIT tagged chinook salmon and steelhead trout, marked at the head of the reservoir, was affected by discharge. Statistical analysis showed that as discharge increased from 40 kcfs to 80 kcfs, chinook salmon travel time decreased three fold, and steelhead trout travel time decreased two fold. There was a statistical difference between estimates of travel time through Lower Granite Reservoir for PIT tagged and freeze branded steelhead trout, but not for chinook salmon. These differences may be related to the estimation techniques used for PIT tagged and freeze branded groups, rather than real differences in travel time.

Buettner, Edwin W.; Nelson, William R.

1989-10-01

177

Drinking Status of Heavy Drinkers Detected by Arrival Time Parametric Imaging Using Sonazoid-Enhanced Ultrasonography: Study of Two Cases  

PubMed Central

Chronic heavy consumption of alcohol is associated with increased risks of developing liver cirrhosis, hepatocellular carcinoma, and esophageal varices. Cessation of alcohol consumption is the most important requirement in treating these diseases. However, judging whether patients have actually maintained abstinence from alcohol requires reliance on their reports, which vary substantially across individuals using the test methods currently available. Arrival time parametric imaging (At-PI) using Sonazoid-enhanced ultrasonography is regarded as a useful approach for assessing the progression of lesions that have developed in liver parenchyma. In this study, we report two cases for whom this approach was successfully applied to indicate the drinking status of a heavy drinker. At-PI enables approximate and objective assessment of the drinking status of patients, independent of their reports; therefore, it is a promising method for providing information about drinking status. PMID:21503166

Wakui, Noritaka; Takayama, Ryuji; Mimura, Takahiko; Kamiyama, Naohisa; Maruyama, Kenichi; Sumino, Yasukiyo

2011-01-01

178

Practical and fast quantum random number generation based on photon arrival time relative to external reference  

SciTech Connect

We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

Nie, You-Qi; Zhang, Jun, E-mail: zhangjun@ustc.edu.cn; Pan, Jian-Wei [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Hong-Fei; Wang, Jian [Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhang, Zhen; Ma, Xiongfeng [Center for Quantum Information, Institute for Interdisciplinary Information Sciences, Tsinghua University, Beijing 100084 (China)

2014-02-03

179

Practical and fast quantum random number generation based on photon arrival time relative to external reference  

NASA Astrophysics Data System (ADS)

We present a practical high-speed quantum random number generator, where the timing of single-photon detection relative to an external time reference is measured as the raw data. The bias of the raw data can be substantially reduced compared with the previous realizations. The raw random bit rate of our generator can reach 109 Mbps. We develop a model for the generator and evaluate the min-entropy of the raw data. Toeplitz matrix hashing is applied for randomness extraction, after which the final random bits are able to pass the standard randomness tests.

Nie, You-Qi; Zhang, Hong-Fei; Zhang, Zhen; Wang, Jian; Ma, Xiongfeng; Zhang, Jun; Pan, Jian-Wei

2014-02-01

180

Does Seismometer Depth and Surrounding Materials Affect the Arrival Times of Seismic  

E-print Network

, and keyword files and create simple files. ---8.3.4 Explain that earthquakes often occur along the boundaries and surrounding materials differ." PROCEDURE: 1). Go to the USGS most recent earthquake site listing and record the dates and times of 5-7 major recent earthquakes of interest to you. 2).Retrieve and review the stored

Polly, David

181

Real-time shock arrival predictions during the ``Halloween 2003 epoch''  

Microsoft Academic Search

The ``Halloween'' epoch from 19 October to 20 November 2003 was marked by 19 major solar flares that were accompanied by metric type II radio bursts. Several of these flares were followed by major geomagnetic storms. The radio bursts were used in real time because they imply coronal and interplanetary transport. Most of these events were also associated with halo

M. Dryer; Z. Smith; C. D. Fry; W. Sun; C. S. Deehr; S.-I. Akasofu

2004-01-01

182

The energy radiated by the 26 December 2004 Sumatra-Andaman earthquake estimated from 10-minute P-wave windows  

USGS Publications Warehouse

The rupture process of the Mw 9.1 Sumatra-Andaman earthquake lasted for approximately 500 sec, nearly twice as long as the teleseismic time windows between the P and PP arrival times generally used to compute radiated energy. In order to measure the P waves radiated by the entire earthquake, we analyze records that extend from the P-wave to the S-wave arrival times from stations at distances ?? >60??. These 8- to 10-min windows contain the PP, PPP, and ScP arrivals, along with other multiply reflected phases. To gauge the effect of including these additional phases, we form the spectral ratio of the source spectrum estimated from extended windows (between TP and TS) to the source spectrum estimated from normal windows (between TP and TPP). The extended windows are analyzed as though they contained only the P-pP-sP wave group. We analyze four smaller earthquakes that occurred in the vicinity of the Mw 9.1 mainshock, with similar depths and focal mechanisms. These smaller events range in magnitude from an Mw 6.0 aftershock of 9 January 2005 to the Mw 8.6 Nias earthquake that occurred to the south of the Sumatra-Andaman earthquake on 28 March 2005. We average the spectral ratios for these four events to obtain a frequency-dependent operator for the extended windows. We then correct the source spectrum estimated from the extended records of the 26 December 2004 mainshock to obtain a complete or corrected source spectrum for the entire rupture process (???600 sec) of the great Sumatra-Andaman earthquake. Our estimate of the total seismic energy radiated by this earthquake is 1.4 ?? 1017 J. When we compare the corrected source spectrum for the entire earthquake to the source spectrum from the first ???250 sec of the rupture process (obtained from normal teleseismic windows), we find that the mainshock radiated much more seismic energy in the first half of the rupture process than in the second half, especially over the period range from 3 sec to 40 sec.

Choy, G.L.; Boatwright, J.

2007-01-01

183

Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1984 Annual Report.  

SciTech Connect

Hatcheries released 9.3 million chinook salmon and 6.3 million steelhead smolts and presmolts upriver from Lower Granite Reservoir for migration in spring, 1984. Peak passage of yearling chinook salmon occurred the third week in April at both Whitebird and Snake River traps. Passage of steelhead was still increasing when high water stopped trapping in mid-May. Average migration rate between release sites and Snake River (the head of Lower Granite Reservoir) was 13.2 miles/day and from that point on through the reservoir to the dam, 1.9 miles/day. Salmon River discharge, when considered along with other environmental factors, had the greatest effect on migration rate of smolts branded both at hatcheries and at the Whitebird trap and migrating to the head of Lower Granite Reservoir. Migration rate for steelhead released from Dworshak Hatchery and recaptured at the Clearwater trap was 34 miles/day. Survival rates to the Snake River trap of branded chinook salmon smolts released at Hells Canyon Dam, Rapid River, South Fork Salmon and Decker Flat were 52%, 65%, 68% and 35%, respectively. Classical descaling, where at least 40% of the scales are missing from at least two of five areas on the side of a smolt, ranged from 0 to 5.3% at hatcheries for chinook salmon and was less than 1% for steelhead. Scattered descaling, where at least 10% of scales are missing from at least one side of a fish, was always more extensive than was classical descaling, ranging from 2.5 times greater for Clearwater hatchery steelhead to 6.8 times greater for Clearwater wild steelhead. Mean total length of chinook salmon yearlings was the same at all the traps, i.e., 128 mm (117 mm fork length) +- 1 mm.

Scully, Richard J.; Buettner, Edwin W.

1986-02-01

184

Smolt Condition and Timing of Arrival at Lower Granite Reservoir, 1983-1984 Technical Report.  

SciTech Connect

Hatcheries released 9.3 million chinook salmon and 6.3 million steelhead smolts and presmolts upriver from Lower Granite Reservoir for migration In spring, 1984. We operated smolt monitoring traps at Whitebird from March 14 to May 12, Snake River from March 22 to May 15 and Clearwater from March 29 to May 13. Peak passage of yearling chinook salmon occurred the third week In April at both Whitebird and Snake River traps. Passage of steelhead was still increasing when high water stopped trapping in mid-May. Median migration rates for branded chinook salmon between release sites and Whitebird were 3, 17 and 15 miles/day for Rapid River, South Fork Salmon and Decker Flat smolts, respectively, an average of 11.6 miles/day. Average migration rate for these three groups between Whitebird and Snake River trap was 28 miles/day. Average migration rate between release sites and Snake River (the head of Lower Granite Reservoir) was 13.2 miles/day and from that point on through the reservoir to the dam, 1.9 miles/day. Salmon River discharge, when considered along with other environmental factors, had the greatest effect on migration rate of smolts branded both at hatcheries and at the Whitebird trap and migrating to the head of Lower Granite Reservoir. Migration rate for steelhead released from Dworshak Hatchery and recaptured at the Clearwater trap was 34 miles/day. Survival rates to the Snake River trap of branded chinook salmon smolts released at Hells Canyon Dam, Rapid River, South Fork Salmon and Decker Flat were 52%, 65%, 68% and 35%, respectively. Classical descaling, where at least 40% of the scales are missing from at least two of five areas on the side of a smolt, ranged from 0 to 5.3% at hatcheries for chinook salmon and was less than 1% for steelhead. Descaling rate often Increased about 1% at release sites. Classical descaling at Whitebird, Clearwater and Snake River traps averaged 4.5, 2.5 and 1.5% for chinook salmon, 2.1, 0.4 and 1.4% for wild steelhead and 8.7, 4.1 and 5.5% for hatchery steelhead, respectively. Scattered descaling, where at least 10% of scales are missing from at least one side of a fish, was always more extensive than was classical descaling, ranging from 2.5 times greater for Clearwater hatchery steelhead to 6.8 times greater for Clearwater wild steelhead. Mean total length of chinook salmon yearlings was the same at all the traps, i.e., 128 mm (117 mm fork length) + 1 mm. The largest chinook salmon smolts came from Dworshak National Fish Hatchery on the Clearwater River. Hatchery steelhead were smallest (2 = 203 mm) at the Clearwater trap and largest (2 = 239 mm) at the Whitebird trap. Wild steelhead were also smallest at Clearwater trap ({bar x} = 178 mm) and largest at Whitebird trap ({bar x} = 193 mm). Purse seining to evaluate rates of descaling before and after smolts passed Lower Granite Dam was largely ineffective since we were unable to catch sufficient numbers of smolts in the tailrace, and winds in the forebay area altered descaling rates in sampled smolts.

Scully, Richard J.; Buettner, Edwin W.

1985-12-01

185

P-wave and surface wave survey for permafrost analysis in alpine regions  

NASA Astrophysics Data System (ADS)

In various high mountain environments the estimate of mechanical properties of slope and sediments are relevant for the link of the geo-mechanical properties with the climate change effects. Two different locations were selected to perform seismic and georadar surveying, the Tsanteleina glacier (Gran Paradiso) and the Blue Lake in Val d'Ayas in the massif of Monterosa. The analysis of the seismic and GPR lines allowed to characterize the silty soil (top layer) and underlying bedrock. We applied seismic survey in time lapse mode to check the presence of "active" layer and estimate the mechanical properties of the moraines material and their sensitivity to the permafrost changes. Mechanical properties of sediments and moraines in glacial areas are related to the grain-size, the compaction of the material subjected to the past glacial activity, the presence of frozen materials and the reactivity of the permafrost to the climate changes. The test site of Tsanteleina has been equipped with sensors to monitor the temperature of soil and air and with time domain reflectometry to estimate the soil moisture and the frozen and thawing cycle of the uppermost material. Seismic reflections from the top of the permafrost layer are difficult to identify as they are embedded in the source-generated noise. Therefore we estimate seismic velocities from the analysis of traveltime refraction tomography and the analysis of surface wave. This approach provides information on compressional and shear waves using a single acquisition layout and a hammer acts as source. This reduces the acquisition time in complex logistical condition especially in winter period. The seismic survey was performed using 48 vertical geophones with 2 m spacing. The survey has been repeated in two different periods: summer 2011 and winter 2011. Common offset reflection lines with a 200 MHz GPR system (in summer) permitted to investigate the sediments and obtain information on the subsoil layering. The processing of seismic data involved the tomographic interpretation of traveltime P-wave first arrivals by considering the continuous refraction of the ray-paths. Several surface-wave dispersion curves were extracted in f-k domain along the seismic line and then inverted through a laterally constrained inversion algorithm to obtain a pseudo-2D section of S-wave velocity. Georadar investigation (about 2 km of georadar lines in the first site) confirmed the presence both of fine and coarse sediments in the uppermost layer; the seismic data allowed the moraines to be characterized down to 20-25 meters of depth. At the elevation of 2700 m asl, we observed a general decrease of the P-wave traveltimes collected in November, when the near surface layer was in frozen condition, respect to the data acquired in June. The frozen layer is responsible of the inversion of P-wave velocity with depth; the higher velocity layer (frozen) cannot be detected in the tomographic interpretation of refraction tomographic of the P-wave arrivals. Compressional wave velocity ranges from 700 m/s on the uppermost part, to 2000-2500 m/s in the internal part of the sediments reaching values higher than 5000 m/s at depth about 20 m. The analysis of surface wave permitted to estimate a slight increase from summer to winter of the S-wave velocity, in the depth range between 0 to 5 m.

Godio, A.; Socco, L. V.; Garofalo, F.; Arato, A.; Théodule, A.

2012-04-01

186

Joint inversion of gravity and arrival time data from Parkfield: New constraints on structure and hypocenter locations near the SAFOD drill site  

USGS Publications Warehouse

Taking advantage of large datasets of both gravity and elastic wave arrival time observations available for the Parkfield, California region, we generated an image consistent with both types of data. Among a variety of strategies, the best result was obtained from a simultaneous inversion with a stability requirement that encouraged the perturbed model to remain close to a starting model consisting of a best fit to the arrival time data. The preferred model looks essentially the same as the best-fit arrival time model in areas where ray coverage is dense, with differences being greatest at shallow depths and near the edges of the model where ray paths are few. Earthquake locations change by no more than about 100 m, the general effect being migration of the seismic zone to the northeast, closer to the surface trace of the San Andreas Fault. Copyright 2004 by the American Geophysical Union.

Roecker, S.; Thurber, C.; McPhee, D.

2004-01-01

187

Teleseismic P-wave tomogram of the Yellowstone plume  

Microsoft Academic Search

Inversion of a new data set of teleseismic P-wave travel-times from three PASSCAL seismic deployments around the Yellowstone hotspot reveals a 100 km diameter upper mantle plume that extends from the Yellowstone volcanic caldera to 500 km depth and dips 20° to the northwest. A monotonic decrease in the velocity perturbation of the plume from ?3.2% at 100 km to

Huaiyu Yuan; Ken Dueker

2005-01-01

188

Teleseismic P-wave tomogram of the Yellowstone plume  

Microsoft Academic Search

Inversion of a new data set of teleseismic P-wave travel-times from three PASSCAL seismic deployments around the Yellowstone hotspot reveals a 100 km diameter upper mantle plume that extends from the Yellowstone volcanic caldera to 500 km depth and dips 20° to the northwest. A monotonic decrease in the velocity perturbation of the plume from -3.2% at 100 km to

Huaiyu Yuan; Ken Dueker

2005-01-01

189

Simulation-based validation and arrival-time correction for Patlak analyses of Perfusion-CT scans  

NASA Astrophysics Data System (ADS)

Blood-brain-barrier (BBB) breakdown is a hypothesized mechanism for hemorrhagic transformation in acute stroke. The Patlak analysis of a Perfusion Computed Tomography (PCT) scan measures the BBB permeability, but the method yields higher estimates when applied to the first pass of the contrast bolus compared to a delayed phase. We present a numerical phantom that simulates vascular and parenchymal time-attenuation curves to determine the validity of permeability measurements obtained with different acquisition protocols. A network of tubes represents the major cerebral arteries ipsi- and contralateral to an ischemic event. These tubes branch off into smaller segments that represent capillary beds. Blood flow in the phantom is freely defined and simulated as non-Newtonian tubular flow. Diffusion of contrast in the vessels and permeation through vessel walls is part of the simulation. The phantom allows us to compare the results of a permeability measurement to the simulated vessel wall status. A Patlak analysis reliably detects areas with BBB breakdown for acquisitions of 240s duration, whereas results obtained from the first pass are biased in areas of reduced blood flow. Compensating for differences in contrast arrival times reduces this bias and gives good estimates of BBB permeability for PCT acquisitions of 90-150s duration.

Bredno, Jörg; Hom, Jason; Schneider, Thomas; Wintermark, Max

2009-02-01

190

High-precision x-ray FEL pulse arrival time measurements at SACLA by a THz streak camera with Xe clusters.  

PubMed

The accurate measurement of the arrival time of a hard X-ray free electron laser (FEL) pulse with respect to a laser is of utmost importance for pump-probe experiments proposed or carried out at FEL facilities around the world. This manuscript presents the latest device to meet this challenge, a THz streak camera using Xe gas clusters, capable of pulse arrival time measurements with an estimated accuracy of several femtoseconds. An experiment performed at SACLA demonstrates the performance of the device at photon energies between 5 and 10 keV with variable photon beam parameters. PMID:25606930

Jurani?, P N; Stepanov, A; Ischebeck, R; Schlott, V; Pradervand, C; Patthey, L; Radovi?, M; Gorgisyan, I; Rivkin, L; Hauri, C P; Monoszlai, B; Ivanov, R; Peier, P; Liu, J; Togashi, T; Owada, S; Ogawa, K; Katayama, T; Yabashi, M; Abela, R

2014-12-01

191

One dimensional P wave velocity structure of the crust beneath west Java and accurate hypocentre locations from local earthquake inversion  

SciTech Connect

A one-dimensional (1-D) velocity model and station corrections for the West Java zone were computed by inverting P-wave arrival times recorded on a local seismic network of 14 stations. A total of 61 local events with a minimum of 6 P-phases, rms 0.56 s and a maximum gap of 299 Degree-Sign were selected. Comparison with previous earthquake locations shows an improvement for the relocated earthquakes. Tests were carried out to verify the robustness of inversion results in order to corroborate the conclusions drawn out from our reasearch. The obtained minimum 1-D velocity model can be used to improve routine earthquake locations and represents a further step toward more detailed seismotectonic studies in this area of West Java.

Supardiyono; Santosa, Bagus Jaya [Physics Department, Faculty of Mathematics and Natural Sciences, State University of Surabaya, Surabaya (Indonesia) and Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia); Physics Department, Faculty of Mathematics and Natural Sciences, Sepuluh Nopember Institute of Technology, Surabaya (Indonesia)

2012-06-20

192

The estimation of subsample time delay of arrival in the discrete-time measurement of phase delay  

Microsoft Academic Search

Time delay estimation (TDE) techniques based upon the identification of the extremum of the cross-correlation function, or some other statistic of two signals, typically use some form of interpolation between points to obtain a resolution finer than the sample period. Often these techniques introduce some bias because of mismatch between the interpolating function and the actual discrete-time correlation function. We

Douglas L. Maskell; Graham S. Woods

1999-01-01

193

Seismic Imaging of a Bimaterial Interface along the Hayward Fault, CA, with Fault Zone Head Waves and Direct P Arrivals  

NASA Astrophysics Data System (ADS)

We show the existence and image properties of a seismic velocity contrast along the Hayward fault using moveout analysis and joint inversion of fault zone head waves (FZHW) and direct P arrivals. The analysis is based on FZHW and P arrival times for 5834 earthquakes recorded at up to 27 stations of the Berkeley Digital Seismic Network (BDSN) and the Northern California Seismic Network (NCSN). Robust identification of FZHW requires the combination of multiple techniques due to the diverse instrumentation of the BDSN and NCSN. For single-component short-period instruments, FZHW are identified by examining sets of waveforms from both sides of the fault, and finding on one (the slow) side emergent reversed-polarity arrivals before the direct P waves. For three-component broadband and strong-motion instruments, the FZHW are identified with polarization analysis that detects early arrivals from the fault direction before the regular body waves with polarizations in the source-receiver directions. The initial results indicate a velocity contrast of 5-12% along the central portion of the Hayward fault, with the southwest side having faster P wave velocity in agreement with tomography results. A systematic moveout between the FZHW and direct P waves for a roughly 70 km long fault section suggest a single continuous fault interface over that distance. We also find some complexities near the junction with the Calaveras fault in the southernmost portion and near the city of Oakland. Regions giving rise to variable FZHW arrival times can be correlated to first order with the presence of lithological complexity, including slivers of high-velocity metamorphic rocks and serpentinized rocks. The seismic velocity contrast and geological complexity have important implications for earthquake and rupture dynamics of the Hayward fault.

Allam, A. A.; Ben-Zion, Y.; Peng, Z.

2012-12-01

194

Observations of high-frequency P wave earthquake and explosion spectra compared with ?-3, ?-2, and sharpe source models  

NASA Astrophysics Data System (ADS)

Observations of 10-, 20-, and 30-Hz P wave spectral amplitudes from earthquakes and explosions are compared with the Archambeau [1968, 1972] earthquake model featuring a P wave falloff of ?-3 beyond the corner frequency, a modified Brune [1970, 1971] earthquake model with ?-2 falloff, and the Sharpe [1942] explosion model which has a ?-2 falloff. The Archambeau and Sharpe models have been, in part, the basis of a proposal by Evernden et al. [1986] that high-frequency (?30 Hz) seismic energy could provide an effective solution to the problem of detection and identification of low-yield coupled and fully decoupled underground nuclear explosions. The observations of earthquakes show an increase in spectral amplitude with moment approximately in agreement with the ?-2 falloff model and, for larger moments, in disagreement with the ?-3 model. Comparison of theoretical and actual seismograms narrow-band filtered at 30 Hz shows that in part the increase in spectral amplitude of earthquakes is due to the complex and long duration of the rupture process and not because of an increase in an impulsive first arrival like that characteristic of an explosion. The 30-Hz amplitudes for explosions show much scatter, and many events have a spectral falloff greater than the ?-2 predicted by the Sharpe model. Whether this is due entirely to attenuation or is the actual source spectrum is not determined. High stress drop earthquakes are predicted to have larger spectral amplitudes than the Sharpe model. Thus any discrimination technique using high-frequency P wave spectra should probably take into account differences in pulse shape and amplitude in the time domain.

Walter, William R.; Brune, James N.; Priestley, Keith F.; Fletcher, Jon

1988-06-01

195

A simulation based study of Linsley's approach to infer the elongation rate and fluctuations of the EAS maximum depth from muon arrival time distributions  

Microsoft Academic Search

An indirect approach to deduce the elongation rate De and the fluctuations of the atmospheric depth Xm of the extensive air showers (EAS) maximum from muon arrival time distributions has been scrutinised on basis of Monte Carlo simulations of the EAS development and of the longitudinal profile of various EAS parameters. Special attention is given to the behaviour of a

A. F. Badea; H. Rebel; M. Zazyan; I. M. Brancus; A. Haungs; J. Oehlschläger

2001-01-01

196

A Simulation Study of Linsley's Approach to infer Elongation Rate and Fluctuations of the EAS Maximum Depth from Muon Arrival Time Distributions  

Microsoft Academic Search

An indirect approach to deduce the elongation rate De and the fluctuations of the atmospheric depth Xm of the EAS maximum from muon arrival time distributions has been scrutinized on basis of Monte Carlo simulations of the EAS development and of the longitudinal profile of various EAS parameters. Special attention is made to the behaviour of a scaling parameter relating

Florin A. Badea

1999-01-01

197

Pre-Arrival GuideThis interactive PDF guide will help to prepare for your time at the International Summer School (ISS). To confirm your place, you must  

E-print Network

to the International Summer School 2014 JUNE 21 - AUGUST 1 #12;Registration Registration for all students takes place/o International Summer School University of Oslo P.O. Box 1082, Blindern NO-0317 Oslo NORWAY Visiting address ISSPre-Arrival GuideThis interactive PDF guide will help to prepare for your time at the International

Johansen, Tom Henning

198

A Microcontroller-Based Instrument for Measuring P-Wave Speed in Impact-Echo Testing of Concrete  

Microsoft Academic Search

The objective of this paper is to describe a microcontroller-based instrument for measuring P-wave speed in impact-echo test of concrete. This measurement is based on measuring the travel time of the P-wave (Deltat) between two transducers at known distance apart. The present study developed an instrument to record the Deltat using interrupt-on-change feature of microcontroller and calculate the P-wave speed.

Slamet Riyadi; K. A. M. Nayan; M. M. Mustafa

2006-01-01

199

Dynamic Allocation and Learning with Strategic Arrivals  

E-print Network

) about the timing of purchase: cus- tomers for a certain flight are advised whether to buy immediately advice about the timing of purchase for durable goods. The conventional wisdom is that consumer, and about their arrival time to the market. The designer learns about future arrivals from past arrivals

Franz, Sven Oliver

200

Comparison of P-Wave and S-Wave Reflection Surveying Effectiveness for Detection of Mine-Related Subsidence Activity Beneath a Heavily Traveled Roadway  

NASA Astrophysics Data System (ADS)

We acquired high-resolution multicomponent seismic reflection data along an undermined 2200 ft (671 m) section of Interstate highway 70 (I-70) in eastern Ohio, in order to identify areas of active subsidence or soil piping into subsurface collapse features. This paper presents results from research conducted: 1) to investigate potential advantages and disadvantages associated with near-surface P- and S-wave reflection surveys, and 2) to determine the subsidence detection potential of common-mode P- and S-wave data components acquired in the study area. P-wave data have traditionally been acquired during shallow reflection surveys, however, the number of reports concerning shallow S-wave surveys is relatively small, and very few reports concerning the concurrent acquisition and analysis of P- and S-wave reflection data exist. Although S-wave reflections from the top-of-bedrock (located above the coal mine and targeted for subsidence detection purposes) were consistently observed in both XX component (inline-inline, SV-SV) and YY component (crossline-crossline, SH-SH) data, surface wave noise resulted in the optimum reflection window of XX data being relatively narrow. Stacks produced using YY data had a higher signal-to-noise ratio and better imaged the target horizon than those produced using XX data. Whereas S-waves were relatively insensitive to changes in overburden moisture content, P-wave reflections from the top-of-saturated-overburden (located above bedrock) were recorded in ZZ component (vertical-vertical, P-P) data. The arrival times of P-wave reflections and the characteristics of the recorded noise modes made it difficult to process and use P-wave reflections from this interface. P-wave events from deeper impedance contrasts were not observed in field data due to several factors: surface wave and air wave noise, a high P-wave reflection coefficient at the top-of-saturated-overburden, low P-wave reflection coefficients at deeper interfaces, and interference effects/resolution issues. Calculations suggest that the resolution of S-waves in the study area dry overburden is more than 1.7 times that of P-waves, and that the resolution of S-waves in the study area saturated overburden is more than 4.5 times that of P-waves. Given the study area subsurface conditions and acquired data characteristics, areas of the subsurface where subsidence processes have been active could be most accurately delineated through the processing and interpretation of YY (relative to XX and ZZ) data. Processed YY data indicate that the bedrock horizon is significantly disrupted due to mine-related subsidence processes at numerous locations along the roadway in the study area. Hence, these locations are regarded as having a relatively high risk for future mine-related surface failure.

Guy, E. D.; Daniels, J. J.

2002-12-01

201

Reactivation and mantle dynamics of North China Craton: insight from P-wave anisotropy tomography  

NASA Astrophysics Data System (ADS)

We determined the first 3-D P-wave anisotropic tomography beneath the North China Craton (NCC) using a large number of high-quality arrival-time data from local earthquakes and teleseismic events, which reveals depth-dependent azimuthal anisotropy in the crust and upper mantle down to 600 km depth. In the NCC western block, the fast velocity direction (FVD) varies from east-west in the southern part to northeast-southwest in the northern part, which may reflect either the interaction between the Yangtze block and NCC or fossil lithospheric fabrics in the craton. Under the NCC eastern block, a uniform northwest-southeast FVD is revealed in the lower part of the upper mantle (300-410 km depths) and the mantle transition zone (410-660 km depths), which may reflect horizontal and upwelling flows in the big mantle wedge (BMW) above the stagnant Pacific slab in the mantle transition zone. The NCC central block exhibits a northeast-southwest FVD, consistent with the surface tectonic orientation there, suggesting that the cold and thick (>300 km) cratonic root of the NCC western block may obstruct the northwest-southeast trending mantle flow induced by the Pacific Plate subduction, resulting in a northeast-southwest trending mantle flow under the central block. Our present results indicate that the corner flow in the BMW associated with the deep subduction of the Pacific Plate is the main cause of NCC reactivation and mantle dynamics under East China.

Tian, You; Zhao, Dapeng

2013-12-01

202

Matter-wave interference in s-wave and p-wave Fermi condensates  

SciTech Connect

We discuss the time evolution and matter-wave interference of Fermi condensates on the Bose-Einstein condensate side of Feshbach resonances for s- and p-wave superfluids, upon release from harmonic traps. In s-wave systems, where the order parameter is a complex scalar, we find that the interference patterns depend on the relative phase of the order parameters of the condensates. In p-wave systems involving the mixture of two hyperfine states, we show that the interference pattern exhibits a polarization effect depending on the relative orientation of the two vector order parameters. Lastly, we also point out that p-wave Fermi condensates exhibit an anisotropic expansion, reflecting the spatial anisotropy of the underlying interaction between fermions and the orbital nature of the vector order parameter. Potential applications of our results include systems of ultracold atoms that exhibit p-wave Feshbach resonances, such as {sup 6}Li or {sup 40}K.

Zhang Wei; Sa de Melo, C. A. R. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2007-07-15

203

Quench-Induced Floquet Topological p-Wave Superfluids  

NASA Astrophysics Data System (ADS)

Ultracold atomic gases in two dimensions tuned close to a p-wave Feshbach resonance were expected to exhibit topological superfluidity, but these were found to be experimentally unstable. We show that one can induce a topological Floquet superfluid if weakly interacting atoms are brought suddenly close ("quenched") to such a resonance, in the time before the instability kicks in. The resulting superfluid possesses Majorana edge modes, yet differs from a conventional Floquet system as it is not driven externally. Instead, the periodic modulation is self-generated by the dynamics.

Foster, Matthew S.; Gurarie, Victor; Dzero, Maxim; Yuzbashyan, Emil A.

2014-08-01

204

Computer program modifications of Open-file report 82-1065; a comprehensive system for interpreting seismic-refraction and arrival-time data using interactive computer methods  

USGS Publications Warehouse

The computer programs published in Open-File Report 82-1065, A comprehensive system for interpreting seismic-refraction arrival-time data using interactive computer methods (Ackermann, Pankratz, and Dansereau, 1982), have been modified to run on a mini-computer. The new version uses approximately 1/10 of the memory of the initial version, is more efficient and gives the same results.

Ackermann, Hans D.; Pankratz, Leroy W.; Dansereau, Danny A.

1983-01-01

205

Robust Bayesian hypocentre and uncertainty region estimation: the effect of heavy-tailed distributions and prior information in cases with poor, inconsistent and insufficient arrival times  

NASA Astrophysics Data System (ADS)

We propose methods for robust Bayesian inference of the hypocentre in presence of poor, inconsistent and insufficient phase arrival times. The objectives are to increase the robustness, the accuracy and the precision by introducing heavy-tailed distributions and an informative prior distribution of the seismicity. The effects of the proposed distributions are studied under real measurement conditions in two underground mine networks and validated using 53 blasts with known hypocentres. To increase the robustness against poor, inconsistent or insufficient arrivals, a Gaussian Mixture Model is used as a hypocentre prior distribution to describe the seismically active areas, where the parameters are estimated based on previously located events in the region. The prior is truncated to constrain the solution to valid geometries, for example below the ground surface, excluding known cavities, voids and fractured zones. To reduce the sensitivity to outliers, different heavy-tailed distributions are evaluated to model the likelihood distribution of the arrivals given the hypocentre and the origin time. Among these distributions, the multivariate t-distribution is shown to produce the overall best performance, where the tail-mass adapts to the observed data. Hypocentre and uncertainty region estimates are based on simulations from the posterior distribution using Markov Chain Monte Carlo techniques. Velocity graphs (equivalent to traveltime graphs) are estimated using blasts from known locations, and applied to reduce the main uncertainties and thereby the final estimation error. To focus on the behaviour and the performance of the proposed distributions, a basic single-event Bayesian procedure is considered in this study for clarity. Estimation results are shown with different distributions, with and without prior distribution of seismicity, with wrong prior distribution, with and without error compensation, with and without error description, with insufficient arrival times and in presence of significant outliers. A particular focus is on visual results and comparisons to give a better understanding of the Bayesian advantage and to show the effects of heavy-tailed distributions and informative prior information on real data.

Martinsson, J.

2013-03-01

206

P Wave Dispersion and Maximum P Wave Duration Are Associated with Renal Outcomes in Chronic Kidney Disease  

PubMed Central

P wave parameters measured by 12-lead electrocardiogram (ECG) are commonly used as a noninvasive tool to evaluate left atrial enlargement. This study was designed to assess whether P wave parameters were associated with renal outcomes in chronic kidney disease (CKD) patients. This longitudinal study enrolled 439 patients with CKD stages 3–5. Renal end points were defined as the commencement of dialysis or death. Change in renal function was measured using the estimated glomerular filtration rate (eGFR) slope. We measured two ECG P wave parameters corrected for heart rate, i.e., corrected P wave dispersion and corrected maximum P wave duration. The values of P wave dispersion and maximum P wave duration were 88.8±21.7 ms and 153.3±21.7 ms, respectively. During the follow-up period (mean, 25.2 months), 95 patients (21.6%) started hemodialysis and 30 deaths (6.8%) were recorded. Multivariate Cox regression analysis identified that increased P wave dispersion [hazard ratio (HR), 1.020; 95% confidence interval (CI), 1.009–1.032; P<0.001] and maximum P wave duration (HR, 1.013; 95% CI, 1.003–1.024; P?=?0.012) were associated with progression to renal end points. Furthermore, increased P wave dispersion (unstandardized coefficient ??=?–0.016; P?=?0.037) and maximum P wave duration (unstandardized coefficient ??=?–0.014; P?=?0.040) were negatively associated with the eGFR slope. We demonstrated that increased P wave dispersion and maximum P wave duration were associated with progression to the renal end points of dialysis or death and faster renal function decline in CKD patients. Screening CKD patients on the basis of P wave dispersion and maximum P wave duration may help identify patients at high risk for worse renal outcomes. PMID:25006682

Huang, Jiun-Chi; Wei, Shu-Yi; Chen, Szu-Chia; Chang, Jer-Ming; Hung, Chi-Chih; Su, Ho-Ming; Hwang, Shang-Jyh; Chen, Hung-Chun

2014-01-01

207

A scheme for a shot-to-shot, femtosecond-resolved pulse length and arrival time measurement of free electron laser x-ray pulses that overcomes the time jitter problem between the FEL and the laser  

NASA Astrophysics Data System (ADS)

The recent entry of X-ray free electron lasers (FELs) to all fields of physics has created an enormous need, both from scientists and operators, for better characterization of the beam created by these facilities. Of particular interest is the measurement of the arrival time of the FEL pulse relative to a laser pump, for pump-probe experiments, and the measurement of the FEL pulse length. This article describes a scheme that corrects one of the major sources of uncertainty in these types of measurements, namely the jitter in the arrival time of the FEL relative to an experimental laser beam. The setup presented here uses a combination of THz streak cameras and a spectral encoding setup to reduce the effect of an FEL's jitter, leaving the pulse length as the only variable that can affect the accuracy of the pulse length and arrival time measurement. A discussion of underlying principles is also provided.

Jurani?, P. N.; Stepanov, A.; Peier, P.; Hauri, C. P.; Ischebeck, R.; Schlott, V.; Radovi?, M.; Erny, C.; Ardana-Lamas, F.; Monoszlai, B.; Gorgisyan, I.; Patthey, L.; Abela, R.

2014-03-01

208

Effect of immiscible liquid contaminants on P-wave transmission through natural aquifer samples  

SciTech Connect

We performed core-scale laboratory experiments to examine the effect of non-aqueous phase liquid (NAPL) contaminants on P-wave velocity and attenuation in heterogeneous media. This work is part of a larger project to develop crosswell seismic methods for minimally invasive NAPL detection. The test site is the former DOE Pinellas Plant in Florida, which has known NAPL contamination in the surficial aquifer. Field measurements revealed a zone of anomalously high seismic attenuation, which may be due to lithology and/or contaminants (NAPL or gas phase). Intact core was obtained from the field site, and P-wave transmission was measured by the pulse-transmission technique with a 500 kHz transducer. Two types of samples were tested: a clean fine sand from the upper portion of the surficial aquifer, and clayey-silty sand with shell fragments and phosphate nodules from the lower portion. Either NAPL trichloroethene or toluene was injected into the initially water-saturated sample. Maximum NAPL saturations ranged from 30 to 50% of the pore space. P-wave velocity varied by approximately 4% among the water-saturated samples, while velocities decreased by 5 to 9% in samples at maximum NAPL saturation compared to water-saturated conditions. The clay and silt fraction as well as the larger scatterers in the clayey-silty sands apparently caused greater P-wave attenuation compared to the clean sand. The presence of NAPLs caused a 34 to 54% decrease in amplitudes of the first arrival. The central frequency of the transmitted energy ranged from 85 to 200 kHz, and was sensitive to both grain texture and presence of NAPL. The results are consistent with previous trends observed in homogeneous sand packs. More data will be acquired to interpret P-wave tomograms from crosswell field measurements, determine the cause of high attenuation observed in the field data and evaluate the sensitivity of seismic methods for NAPL detection.

Geller, Jil T.; Ajo-Franklin, Jonathan B.; Majer, Ernest L.

2003-01-31

209

Environmental and lunar cues are predictive of the timing of river entry and spawning-site arrival in lake sturgeon Acipenser fulvescens.  

PubMed

The associations were quantified between daily and interannual variation in the timing of a closed population of lake sturgeon Acipenser fulvescens migration and arrival at spawning sites with stream environmental and lunar covariates. Spawning data were gathered from 1262 fish in Black Lake, Michigan 2001 to 2008 and by video monitoring 2000 to 2002. Sex-specific variation in responses to external cues was also tested. Results showed that a greater number of individuals initiated migration from lake to riverine habitats at dawn and dusk relative to other times of the day. Current and lagged effects of water temperature and river discharge, and periods in the lunar cycle were important variables in models quantifying movements into the river and timing of adult arrival at spawning sites. Different suites of covariates were predictive of A. fulverscens responses during different periods of the spawning season. The timing of initiation of migration and spawning, and the importance of covariates to the timing of these events, did not differ between sexes. Stream flow and temperature covaried with other variables including day length and the lunar cycle. Anthropogenic disruption of relationships among variables may mean that environmental cues may no longer reliably convey information for Acipenseriformes and other migratory fishes. PMID:22747803

Forsythe, P S; Scribner, K T; Crossman, J A; Ragavendran, A; Baker, E A; Davis, C; Smith, K K

2012-07-01

210

The effect of the Earth's oblate spheroid shape on the accuracy of a time-of-arrival lightning ground strike locating system  

NASA Technical Reports Server (NTRS)

The algorithm used in previous technology time-of-arrival lightning mapping systems was based on the assumption that the earth is a perfect spheroid. These systems yield highly-accurate lightning locations, which is their major strength. However, extensive analysis of tower strike data has revealed occasionally significant (one to two kilometer) systematic offset errors which are not explained by the usual error sources. It was determined that these systematic errors reduce dramatically (in some cases) when the oblate shape of the earth is taken into account. The oblate spheroid correction algorithm and a case example is presented.

Casper, Paul W.; Bent, Rodney B.

1991-01-01

211

A holographic p-wave superconductor model  

NASA Astrophysics Data System (ADS)

We study a holographic p-wave superconductor model in a four dimensional Einstein-Maxwell-complex vector field theory with a negative cosmological constant. The complex vector field is charged under the Maxwell field. We solve the full coupled equations of motion of the system and find black hole solutions with the vector hair. The vector hairy black hole solutions are dual to a thermal state with the U(1) symmetry as well as the spatial rotational symmetry broken spontaneously. Depending on two parameters, the mass and charge of the vector field, we find a rich phase structure: zeroth order, first order and second order phase transitions can happen in this model. We also find "retrograde condensation" in which the hairy black hole solution exists only for the temperatures above a critical value with the free energy much larger than the one of the black hole without the vector hair. We construct the phase diagram for this system in terms of the temperature and charge of the vector field.

Cai, Rong-Gen; Li, Li; Li, Li-Fang

2014-01-01

212

Wavelet-based automatic determination of the P- and S-wave arrivals  

NASA Astrophysics Data System (ADS)

The detection of P- and S-wave arrivals is important for a variety of seismological applications including earthquake detection and characterization, and seismic tomography problems such as imaging of hydrocarbon reservoirs. For many years, dedicated human-analysts manually selected the arrival times of P and S waves. However, with the rapid expansion of seismic instrumentation, automatic techniques that can process a large number of seismic traces are becoming essential in tomographic applications, and for earthquake early-warning systems. In this work, we present a pair of algorithms for efficient picking of P and S onset times. The algorithms are based on the continuous wavelet transform of the seismic waveform that allows examination of a signal in both time and frequency domains. Unlike Fourier transform, the basis functions are localized in time and frequency, therefore, wavelet decomposition is suitable for analysis of non-stationary signals. For detecting the P-wave arrival, the wavelet coefficients are calculated using the vertical component of the seismogram, and the onset time of the wave is identified. In the case of the S-wave arrival, we take advantage of the polarization of the shear waves, and cross-examine the wavelet coefficients from the two horizontal components. In addition to the onset times, the automatic picking program provides estimates of uncertainty, which are important for subsequent applications. The algorithms are tested with synthetic data that are generated to include sudden changes in amplitude, frequency, and phase. The performance of the wavelet approach is further evaluated using real data by comparing the automatic picks with manual picks. Our results suggest that the proposed algorithms provide robust measurements that are comparable to manual picks for both P- and S-wave arrivals.

Bogiatzis, P.; Ishii, M.

2013-12-01

213

Predicting interplanetary shock arrivals at Earth, Mars, and Venus: A real-time modeling experiment following the solar flares of 5-14 December 2006  

NASA Astrophysics Data System (ADS)

A 3-D, kinematic, solar wind model (Hakamada-Akasofu-Fry version 2 (HAFv.2)) is used to predict interplanetary shock arrivals at Venus, Earth, and Mars during a sequence of significant solar events that occurred in the interval 5-14 December 2006. Mars and Venus were on the opposite side of the Sun from Earth during this period. The shocks from the first two east limb events (5 and 6 December) were predicted to interact to form a single disturbance before reaching Earth and Venus. A single shock was indeed recorded at Earth only about 3 h earlier than had been predicted. The composite shock was predicted by HAFv.2 to arrive at Venus on 8 December at ˜0500 UT. Solar energetic particles (SEPs) were detected in Venus Express Analyzer of Space Plasmas and Energetic Atoms-4 data for some 3 d (from <0530 UT on 6 December), and an energetic storm particle (ESP) event signaled the arrival of a single shock wave at 0900 UT on 7 December. SEPs were correspondingly recorded at Mars. However, the eastern flank of the composite shock was predicted to decay to an MHD wave prior to reaching this location, and no shock signature was observed in the available data. The shocks generated in association with two flare events that occurred closer to the West Limb on 13 and 14 December were predicted by HAFv.2 to remain separate when they arrived at Earth but to combine thereafter before reaching Mars. Each was expected to decay to MHD waves before reaching Venus, which was at that time located behind the Sun. Separated shocks were observed to arrive at L1 (ACE) only 8 min earlier than and 5.3 h later than their predicted times. The western flank of the combined shocks was predicted to arrive at Mars early on 20 December 2006. An indication of the passage of this shock was provided by a signature of ion heating in Mars Express IMA (ion mass-resolving analyzer) data from <0424 UT on 20 December. The predictions of the HAFv.2 model for Earth were each well within the ±11 h. RMS error earlier found, on the basis of significant statistics, to apply at 1 AU during the rise and maximum phases of solar cycle 23. Overall, the model is demonstrated to be capable of predicting the effects produced by shocks and by the background solar wind at Venus, Earth, and Mars. It is suggested that the continuous presence of solar wind monitors (plasma and interplanetary magnetic field observations) at "benchmark planets" can constitute a necessary and valuable component of ongoing and future space weather programs for the validation of solar wind models such as HAFv.2.

McKenna-Lawlor, S. M. P.; Dryer, M.; Fry, C. D.; Smith, Z. K.; Intriligator, D. S.; Courtney, W. R.; Deehr, C. S.; Sun, W.; Kecskemety, K.; Kudela, K.; Balaz, J.; Barabash, S.; Futaana, Y.; Yamauchi, M.; Lundin, R.

2008-06-01

214

Comparison of the CME-associated shock arrival times at the earth using the WSA-ENLIL model with three cone models  

NASA Astrophysics Data System (ADS)

We have made a comparison of CME-associated shock arrival times at the earth based on the WSA-ENLIL model with three cone models using 29 halo CMEs from 2001 to 2002. These halo CMEs have cone model parameters from Michalek et al. (2007) as well as their associated interplanetary (IP) shocks. For this study we consider three different cone models (an asymmetric cone model, an ice-cream cone model and an elliptical cone model) to determine CME cone parameters (radial velocity, angular width and source location), which are used for input parameters of the WSA-ENLIL model. The mean absolute error (MAE) of the arrival times for the elliptical cone model is 10 hours, which is about 2 hours smaller than those of the other models. However, this value is still larger than that (8.7 hours) of an empirical model by Kim et al. (2007). We are investigating several possibilities on relatively large errors of the WSA-ENLIL cone model, which may be caused by CME-CME interaction, background solar wind speed, and/or CME density enhancement.

Jang, S.; Moon, Y.; Na, H.

2012-12-01

215

P wave velocity structure beneath Greenland using teleseismic events  

NASA Astrophysics Data System (ADS)

A three-dimensional P-wave velocity model was inverted with 3032 ray paths from 416 events observed on the GLISN network from 2009 to 2013. The relative travel times were computed with respect to the IASP91 global reference model using the multi-channel cross correlation method (MCCC) by VanDecar and Crosson {, 1990 #1}. Our model space was parameterized laterally with 1°×1° from 55°N to 85°N in latitude and from 20°W to 80°W in longitude. This high latitude model space causes spatial distortion in the model parameters on the spherical coordinate for the teleseismic body wave tomography. To minimize a distortion in the model parameters the spherical coordinate system was rotated as the referent stations SUMG and SCO, located on the middle of Greenland, to equator, and all stations and seismic events were converted to this new coordinate system. All ray paths were computed by a three dimensional ray tracing algorithm developed with pseudobending technique and Snell's law {Zhao, 1992 #1}, and travel times were corrected by ice and crustal thicknesses for each observed station as well. Our inverted model shows a broad low velocity anomaly ( -1.5%) in the mid-eastern parts of Greenland, which is connected to the low velocity anomaly beneath Iceland. Another low velocity anomaly was observed below 300km in the middle of Greenland where the Icelandic mantle plume was located in 60Ma. P wave velocity anomaly depth slices from 150 km to 400 km on the rotated coordinate from the center of Green land to the equator.

Park, Y.; Lee, W.; Yoo, H.

2013-12-01

216

Estimating the inter-arrival time density of Markov renewal processes under structural assumptions on the transition  

E-print Network

over time. An example is the size of a tectonic earthquake. Here the stress builds up over time because, the number of susceptibles will rise again after an epidemic, due to loss of immunity in the population, so

Wefelmeyer, Wolfgang

217

Estimating the value of containment strategies in delaying the arrival time of an influenza pandemic: A case study of travel restriction and patient isolation  

NASA Astrophysics Data System (ADS)

With a simple phenomenological metapopulation model, which characterizes the invasion process of an influenza pandemic from a source to a subpopulation at risk, we compare the efficiency of inter- and intrapopulation interventions in delaying the arrival of an influenza pandemic. We take travel restriction and patient isolation as examples, since in reality they are typical control measures implemented at the inter- and intrapopulation levels, respectively. We find that the intrapopulation interventions, e.g., patient isolation, perform better than the interpopulation strategies such as travel restriction if the response time is small. However, intrapopulation strategies are sensitive to the increase of the response time, which might be inevitable due to socioeconomic reasons in practice and will largely discount the efficiency.

Wang, Lin; Zhang, Yan; Huang, Tianyi; Li, Xiang

2012-09-01

218

Structure of the Northern Cascadia Subduction Zone: A 3-D Tomographic P-wave Velocity Model  

NASA Astrophysics Data System (ADS)

A large-scale 3D P-wave velocity model to ~60 km depth has been constructed for SW British Columbia and NW Washington through tomographic inversion of first-arrival times from controlled source experiments together with local and regional earthquake travel-time data recorded at permanent stations. 150000 first-arrival times recorded at 225 temporary stations from the 1998 Seismic Hazards Investigation in Puget Sound (SHIPS) experiment, and 60000 first-arrival times from 3000 earthquakes recorded at 91 permanent recording stations are inverted for a minimum structure velocity model. The RMS residuals for the initial and final models are 764 and 132 ms, respectively, which represents a 97% variance reduction. Checkerboard resolution tests indicate a horizontal resolution of 30 km down to 20 km depth, and 50 km down to 60 km depth. The velocity model images the structure of the forearc crust/upper mantle, and the subducting Juan de Fuca plate geometry beneath the region. The sedimentary basins in the Straits of Georgia and Juan de Fuca and Puget Sound are well defined by the velocity model. The mafic Eocene Crescent Terrane (Metchosin Igneous Complex in southern Vancouver Island) is shown to dip beneath the margin to at least 20 km depth. This terrane is regionally extensive beneath the Strait of Juan de Fuca and the Puget lowland, with higher than average velocities of ~7 km/s at approximately 15 km depth. Beneath the Olympic Peninsula, the Core rocks (accretionary sedimentary prism) are under-thrust beneath the Crescent Terrane to a depth of at least 30 km. At this location most seismicity lies within the overlying Crescent Terrane; the under-thrusting Core rocks are aseismic. The strong Crescent terrane seismicity may be due to deformation induced by the underthrusting. Beneath southern Vancouver Island, the subduction thrust zone above the Juan de Fuca plate is characterized by low velocities of 6.4-6.6 km/s at a depth of 25-35 km. Such low velocities may be due to trapped fluids, sheared lower crustal rocks, and possibly underthrust accretionary sedimentary or metamorphic rocks. This low velocity region coincides with the high conductivity region mapped in previous magneto-telluric studies and with a dipping band of seismic reflectors; it is devoid of seismicity. It probably represents a zone of aseismic slip. Low velocities of 7.2-7.6 km/s are observed in the forearc upper mantle beneath the Strait of Georgia and Puget Sound. Such low upper mantle velocities are interpreted to be due to regional serpentinization of cool forearc mantle peridotite by fluids rising from the dehydrating underlying Juan de Fuca crust. The Tertiary sedimentary basins in the Strait of Georgia and Puget lowland lie directly above the zone of forearc upper mantle serpentinization. In contrast, the sedimentary basins in the Strait of Juan de Fuca lie in a synclinal depression in the Crescent volcanic Terrane.

Ramachandran, K.; Hyndman, R. D.; Brocher, T. M.

2004-12-01

219

Assessment of performance of the inter-arrival time algorithm to identify ice shattering artifacts in cloud particle probes measurements  

NASA Astrophysics Data System (ADS)

Shattering presents a serious obstacle to current airborne in-situ methods of characterizing the microphysical properties of ice clouds. Small shattered fragments result from the impact of natural ice crystals with the forward parts of aircraft-mounted measurement probes. The presence of these shattered fragments may result in a significant overestimation of the measured concentration of small ice crystals, contaminating the measurement of the ice particle size distribution (PSD). One method of identifying shattered particles is to use an interarrival time algorithm. This method is based on the assumption that shattered fragments form spatial clusters that have short interarrival times between particles, relative to natural particles, when they pass through the sample volume of the probe. The interarrival time algorithm is a successful technique for the classification of shattering artifacts and natural particles. This study assesses the limitations and efficiency of the interarrival time algorithm. The analysis has been performed using simultaneous measurements of 2-D optical array probes with the standard and antishattering "K-tips" collected during the Airborne Icing Instrumentation Experiment (AIIE). It is shown that the efficiency of the algorithm depends on ice particle size, concentration and habit. Additional numerical simulations indicate that the effectiveness of the interarrival time algorithm to eliminate shattering artifacts can be significantly restricted in some cases. Improvements to the interarrival time algorithm are discussed.

Korolev, A.; Field, P. R.

2014-10-01

220

Embedded Fiber Optic Sensors for Measuring Transient Detonation/Shock Behavior;Time-of-Arrival Detection and Waveform Determination.  

SciTech Connect

The miniaturization of explosive components has driven the need for a corresponding miniaturization of the current diagnostic techniques available to measure the explosive phenomena. Laser interferometry and the use of spectrally coated optical windows have proven to be an essential interrogation technique to acquire particle velocity time history data in one- dimensional gas gun and relatively large-scale explosive experiments. A new diagnostic technique described herein allows for experimental measurement of apparent particle velocity time histories in microscale explosive configurations and can be applied to shocks/non-shocks in inert materials. The diagnostic, Embedded Fiber Optic Sensors (EFOS), has been tested in challenging microscopic experimental configurations that give confidence in the technique's ability to measure the apparent particle velocity time histories of an explosive with pressure outputs in the tenths of kilobars to several kilobars. Embedded Fiber Optic Sensors also allow for several measurements to be acquired in a single experiment because they are microscopic, thus reducing the number of experiments necessary. The future of EFOS technology will focus on further miniaturization, material selection appropriate for the operating pressure regime, and extensive hydrocode and optical analysis to transform apparent particle velocity time histories into true particle velocity time histories as well as the more meaningful pressure time histories.

Chavez, Marcus Alexander; Willis, Michael David; Covert, Timothy T.

2014-09-01

221

Determination of three-dimensional velocity anomalies under a seismic array using first P arrival times from local earthquakes 1. A homogeneous initial model  

Microsoft Academic Search

Geiger's method of locating local earthquakes has been extended to include the effect of P velocity variation along the ray paths in three dimensions. The crustal structure was modeled by rectangular blocks, and a parameter was assigned to each block describing the perturbation of P wave slowness in the block. On the basis of an initial model, a set of

Keiiti Aki; W. H. K. Lee

1976-01-01

222

The transient analysis of the queue-length distribution in the batch arrival system with N-policy, multiple vacations and setup times  

NASA Astrophysics Data System (ADS)

A batch arrival queueing system of the MX/G/1 type with unlimited queue is considered. After each busy period the server begins a multiple vacation period, consisting of independent single vacations, when the service process is blocked. The server begins successive single vacations as far as at the end of one of them the number of customers waiting in the queue equals at least N. The service of the first customer after the vacation period is preceded by a setup time. The analysis of the queue-size distribution on the first vacation cycle is directed to the analysis of the same characteristic in the corresponding "usual" system with unremovable server on its first busy period. The renewal-theory approach is used to obtain results in the general case. As main result the explicit representation for the LT of queue-size distribution is derived for the original system.

Kempa, Wojciech M.

2010-10-01

223

Estimating the arrival times of photon-limited laser pulses in the presence of shot and speckle noise  

NASA Technical Reports Server (NTRS)

Maximum-likelihood (ML) receivers are frequently used to optimize the timing performance of laser-ranging and laser-altimetry systems in the presence of shot and speckle noise. Monte Carlo method was used to examine ML-receiver performance with return signals in the 10-5000-photoelectron (pe) range. The simulations were performed for shot noise only and for shot and speckle noise. The results agree with previous theory for signal strengths greater than about 100 pe's but show that the theory can significantly underestimate timing errors for weaker received signals. Sharp high-bandwidth features in the detected signals are shown to improve timing performance only if their signal levels are greater than 4-5 pe's.

Abshire, James B.; Mcgarry, Jan F.

1987-01-01

224

Point process with last-arrival-time dependent intensity and 1-dimensional incompressible fluid system with evaporation.  

E-print Network

system with evaporation. Tetsuya Hattori Laboratory of Mathematics, Faculty of Economics, Keio by unbounded and space-time dependent evaporation rates. We prove unique existence of the solution occurs at y = 1. Each fluid component, say , evaporates with rate w which may vary among different

Hattori, Tetsuya

225

Analysis of near-source contributions to early P-wave coda for underground explosions. II. Frequency dependence  

SciTech Connect

Analysis of dispersion in more than 1600 teleseismic short-period P waves from 46 underground explosions has established that near-source effects are responsible for systematic frequency-dependent variations observed in the first 15 sec of the P signals. Explosions from the Nevada, Amchitka, and Novaya Zemlya test sites exhibit a common magnitude dependence of the dispersive behavior, with smaller events having relatively enriched low-frequency (0.4 to 0.8 Hz) energy in the coda. For the Nevada and Amchitka sites, the larger events have relatively enhanced high-frequency (0.8 to 1.1 hz) energy in the coda as well, which may be a consequence of diminished high-frequency content of the direct arrivals. The dispersive behavior also correlates well with known source depths for the Nevada Test Site and Amchitka events, and with estimated pP delay times for the Novaya Zemlya events, indicating that burial depth and/or explosion size are important factors. Pahute Mesa tests show a secondary dependence on position in the site, with centrally located events having stronger dispersion, as well as more pronounced slowly varying azimuthal patterns in frequency dependence. Stations at azimuths NNE from the Mesa have particularly strong dispersion for centrally located events. Spatial and azimuthal variations for Pahute Mesa events do not appear to be the result of aftershock radiation but instead are associated with frequency-dependent defocusing and scattering from a high-velocity structure beneath the test site.

Lay, T.

1987-08-01

226

Extension of Fuda's ?N P wave separable model  

NASA Astrophysics Data System (ADS)

Fuda's method to construct a ?N separable model for the P wave interaction is extended to further include the inelasticity effect for all partial waves and the sign changing property of the P11 phase shift. NUCLEAR REACTIONS ?N P wave separable model, inverse scattering problem with crossing symmetry; t matrix contains nucleon poles, right and left cuts, and inelasticity effect; P11 changes the sign.

Nakano, K.

1983-03-01

227

Vortex States of Chiral p-wave Superconductors  

NASA Astrophysics Data System (ADS)

In chiral p-wave superconductors a flux lattice of doubly quantized vortices is shown to be energetically stable for fields Hc1 < HFL < H < Hc2, while at low fields a lattice of singly quantized vortices is stable. Here we report self-consistent calculations by Eilenberger theory for spatial structures of the pair potential and current density for vortex states of single- and double-winding vortices in chiral p-wave superconductors with a cylindrical Fermi surface.

Ichioka, M.; Machida, K.; Sauls, J. A.

2012-12-01

228

Sub-femtosecond precision measurement of relative X-ray arrival time for free-electron lasers  

NASA Astrophysics Data System (ADS)

Today's brightest coherent X-ray sources, X-ray free-electron lasers, produce ultrafast X-ray pulses for which full-width at half-maximum durations as short as 3?fs have been measured. There has been a marked increase in the popularity of such short pulses now that optical timing techniques have begun to report an X-ray/optical delay below ?10?fs r.m.s. errors. As a result, sub-10?fs optical pulses have been implemented at the Linac Coherent Light Source (LCLS) X-ray beamlines, thus warranting a push to reduce the error in X-ray/optical delay measurements to the 1?fs level. Here, we report a unique two-dimensional spectrogram measurement of the relative X-ray/optical delay. This easily scalable relative delay measurement already surpasses previous techniques by an order of magnitude with its sub-1?fs temporal resolution and opens up the prospect of time-resolved X-ray measurements to the attosecond community.

Hartmann, N.; Helml, W.; Galler, A.; Bionta, M. R.; Grünert, J.; L. Molodtsov, S.; Ferguson, K. R.; Schorb, S.; Swiggers, M. L.; Carron, S.; Bostedt, C.; Castagna, J.-C.; Bozek, J.; Glownia, J. M.; Kane, D. J.; Fry, A. R.; White, W. E.; Hauri, C. P.; Feurer, T.; Coffee, R. N.

2014-09-01

229

Basement configuration of on-land Kutch basin from seismic refraction studies and modeling of first arrival travel time skips  

NASA Astrophysics Data System (ADS)

The Kutch basin is one of the three (Narmada, Cambay and Kutch) major marginal rift basins that are close to each other in mid-western part of the Indian subcontinent. The seismic refraction and wide-angle reflection data were acquired and a first order velocity structure of the Kutch sedimentary basin along Jakhau-Mandvi, Mandvi-Mundra, Mundra-Adesar and Hamirpur-Halvad profiles is derived. The travel time skip phenomenon has been noticed in the travel time plots and record sections indicating presence of low velocity sediments. Derived two-dimensional velocity-depth models revealed a Mesozoic sedimentary sequence sandwiched between Trap and Limestone layers, in some of the profiles. Two thick low velocity layers (that corresponds early to late Mesozoic era) have been identified. These are dipping towards Mandvi along Jakhau-Mandvi profile. The early Mesozoic layer that is thinning towards southeast is completely missing in Mandvi-Mundra profile. It is also noticed that the early Mesozoic Bhuj formation exists in the northern parts of the Mundra-Adesar and Hamirpur-Halvad profiles, where it directly overlies the granitic basement. The derived velocity-depth model suggests that the basement is about 3 km deep near Jakhau and reaches a depth of about 6 km near Mandvi. The layered structure may correspond to the Tertiary, Trap, Late Mesozoic sediments and Mesozoic limestone. The velocity-depth model obtained in Kutch is very similar to earlier derived model for Jamnagar and Dwarka sub-basins of northwestern Saurashtra peninsula suggesting probable continuity/linkage between southern on-land Kutch and, across the Gulf of Kutch to Saurashtra peninunsula. We also conclude that the evolution of Kutch basin, as a peri-cratonic rift basin, is essentially controlled by the four (F1-F4) faults inferred from obvious abrupt changes in layer thickness/velocity along the seismic refraction profiles.

Prasad, B. Rajendra; Venkateswarlu, N.; Prasad, A. S. S. S. R. S.; Murthy, A. S. N.; Sateesh, T.

2010-10-01

230

Denoising and harmonic artifacts rejection for ECG P-waves by quadratic variation reduction.  

PubMed

Atrial fibrillation (AF) is a common cardiac arrhythmia related to irregular atrial contractions. Several studies have shown that the analysis of P-waves extracted from ECG signals is helpful in understanding the predisposing factors to AF. However, P-waves are usually highly corrupted by noise and harmonic artifacts and this makes quite difficult their analysis. Recently we proposed a novel algorithm for denoising P-waves based on the notion of quadratic variation reduction. It is quite good in denoising P-waves affected by noise, but its effectiveness reduces when it is used in filtering out harmonic artifacts, like power-line interference. In this paper we propose an algorithm that overcomes this limitation and extends our previous method allowing it to both denoise and reject harmonic artifacts. Simulation results confirm the effectiveness of the approach and highlight its ability to remove both noise and artifacts. The algorithm has reduced computational complexity and this makes it suitable for real-time applications. PMID:22254476

Fasano, A; Villani, V; Vollero, L

2011-01-01

231

Detection of regular variations in the intensity and pulse time of arrival of the anomalous pulsar PSR B0943+10  

NASA Astrophysics Data System (ADS)

Timing of the anomalous pulsar PSR B0943+10 during 2007-2013 was carried out on the Large Phased Array radio telescope of the Pushchino Radio Astronomy Observatory at 112 MHz. The astrometric and rotational parameters for epoch MJD=56 500 have been determined. Considerable deviations of the pulse times of arrival from the precalculated values with a characteristic period of several years due to the presence of correlated low-frequency noise in the pulsar spin phase have been detected. These deviations can be explained in a planetary model by the presence of two companions of the pulsar, whose orbital parameters have been determined. A continuous increase in the longitude of the pulse maximum within the emission window, the pulse width, and the intensity have been detected after each switch to the burst mode. Together with the changes in pulse shape, degree of linear polarization of the pulse, and drift rate of individual pulses detected earlier, this indicates that all the main parameters of the radio emission in the B mode are unstable. This distinguishes PSR B0943+10 from all other modes-witching pulsars. The origin of the observed properties of this pulsar are probably associated with the interaction of its extended magnetosphere with the surrounding medium.

Suleymanova, S. A.; Rodin, A. E.

2014-11-01

232

Comparison of P-wave and S-wave data in a fractured reservoir  

E-print Network

(Member) Joel Watkins (Head of Department) August 1993 ABSTRACT Comparison of P-wave and S-wave Data in a Fractured Reservoir. (August 1993) Husam M. Al-Mustafa, B. S. , King Fahd University of Pettoleum and Minerals, Saudi Arabia; Chair... CORRECTIONS A suuic correcdon is a constant time shift of reflections on a seismic trace caused by laterally variable, near-surface irregularities that hinder the interpretation of deeper subsurface structures, The assumption made is that the residual...

Al-Mustafa, Husam Mustafa

1993-01-01

233

Laboratory monitoring of P-waves in partially saturated sand  

NASA Astrophysics Data System (ADS)

Seismic data depends on a variety of hydrogeological properties of the prospected porous media such as porosity, permeability and fluid saturation. We have performed a laboratory experiment in the kiloHertz range in order to analyze the role of partial saturation on direct propagating P-waves phase velocity and attenuation. The experiment consists of a sand-filled tank 107 cm x 34 cm x 35cm equipped with accelerometers and water capacitance probes. The P-waves seismic propagation is generated by hitting a steel ball on a granite plate on the one lateral side of the container. Several imbibition/drainage cycles are performed between the water residual saturation and the gas residual saturation. The laboratory seismic data are processed by two Continuous Wavelet Transforms using one real mother wavelet (Mexican hat) and one complex (Morlet) to recover velocity and attenuation as a function of frequency. Phase velocity of direct P-wave decreases with an increase of water content and is quite consistent with the low frequency limit of the Biot's theory both for imbibition and drainage. The interpretation of the P-waves attenuation needs to go beyond the macroscopic fluid flow of Biot's theory and to introduce a viscoelastic contribution linked to the grain to grain overall losses which are described by a constant Q-model. A strong hysteresis between imbibition and drainage is observed and explained by introducing an effective permeability depending on water and gas relative permeabilities (Van Genuchten model).

Barrière, J.; Bordes, C.; Brito, D.; Sénéchal, P.; Perroud, H.

2011-12-01

234

Arrival time parametric imaging using Sonazoid-enhanced ultrasonography is useful for the detection of spoke-wheel patterns of focal nodular hyperplasia smaller than 3 cm.  

PubMed

It is considered difficult to make a definitive diagnosis of focal nodular hyperplasia (FNH) of <3 cm when using conventional diagnostic imaging modalities. Typical FNH imaging findings are: i) central scar formation, ii) nutrient vessels extending radially from the center and iii) the presence of Kupffer cells. In a clinical setting, identification of a spoke-wheel pattern formed by nutrient vessels extending radially is a key feature in the diagnosis of FNH. In this study, we investigated the detection rate of spoke-wheel patterns of FNH <3 cm using arrival time parametric imaging (At-PI) technology with Sonazoid-enhanced ultrasonography (US). Five patients with FNH <3 cm who had undergone Sonazoid-enhanced US at the Toho University Omori Medical Center between February 2008 and March 2009 were included in the study. The mean tumor diameter was 20.2±7.2 mm. Lesions were enhanced with 0.5 ml Sonazoid US contrast agent and a video of the procedure was saved and used for At-PI analysis of contrast agent dynamics in FNH. Three ultrasonographic specialists examined the images and made a diagnosis of FNH based on the findings of spoke-wheel patterns. Similarly, micro-flow imaging (MFI) was performed to evaluate the contrast agent dynamics in FNH. Using MFI, FNH was diagnosed in 3 of the 5 cases by the three specialists, whereas At-PI enabled the identification of spoke-wheel patterns in all 5 cases. At-PI using Sonazoid-enhanced US is superior for detecting spoke-wheel patterns of FNH <3 cm. PMID:23837029

Wakui, Noritaka; Takayama, Ryuji; Kamiyama, Naohisa; Kobayashi, Kojiro; Matsui, Daigo; Matsukiyo, Yasushi; Kanekawa, Takenori; Ikehara, Takashi; Ishii, Koji; Sumino, Yasukiyo

2013-06-01

235

Revealing the architecture of the upper boundary of the Philippine Sea Plate beneath the northern tip of the Izu-Tanzawa Collision Zone, Central Japan, using later-phase of P waves  

NASA Astrophysics Data System (ADS)

In Izu-Tanzawa Collision Zone (ITCZ), Izu arc collides with Japan arc due to subduction of the Philippine Sea plate (PHP). Recent studies by Kikuchi (2008) and Arai et al. (2009) have revealed that the upper boundary of PHP has a complex geometry in this area. High seismicity near the top boundary of PHP is reported in the front (northern) edge of the ITCZ, which is the transition zone from collision to subduction of PHP, whereas an aseismic zone is located on the western part of the high seismicity region. This spatial variation of seismicity is probably related to the shape of PHP caused by the difference between collisional vs. subductive movements. To better correlate the spatial distribution of seismicity and the plate configuration, we attempt to find a discontinuous surface near the upper boundary of PHP using later phases of P waves. We used seismic-waveform data from the website of Hi-net seismic network. In the high seismicity region, clear later phases of P waves (X phases) are observed in vertical component seismograms recorded at the stations above the high seismicity region. The X phases arrive 0.5s to 2.0s after P arrivals. Time difference between P and X arrivals (X-P times) increases with distances between the plate boundary and the hypocenters. Similarly, X-P times increase as the distances from the northwestern edge of the high seismicity region to the hypocenters increase. These observations suggest two possibilities for the origin of the X phases: (1) a converted wave at the upper boundary of PHP or (2) a reflected wave from the edge of the high seismicity region. First we searched a suitable plane for which calculated X-P times can match the observed X-P times, by assuming the X phases are converted waves. We found that two converted planes located at different depths would best explain all observed X-P times simultaneously; the depth of the estimated plane in the western side of the high seismicity zone is deeper than that of the eastern side. Next, we determined reflection points for which the observed X-P times can fit: estimated reflection points were concentrated in the northwestern edge of the high seismicity region. In either case, generation points of X phases are located near the top boundary of PHP and it would be expected that the detailed structure near the top boundary of the PHP could be clarified using these later phases. Acknowledgement: We thank the National Research Institute for Earth Science and Disaster Prevention of Japan for providing the Hi-net data.

Shuri, Y.; Tsumura, N.

2010-12-01

236

Hepatic vein arrival time as assessed by contrast-enhanced ultrasonography is useful for the assessment of portal hypertension in compensated cirrhosis.  

PubMed

The measurement of the hepatic venous pressure gradient (HVPG) for the estimation of portal hypertension (PH) in cirrhosis has some limitations, including its invasiveness. Hepatic vein arrival time (HVAT), as assessed by microbubble contrast-enhanced ultrasonography (CEUS), is negatively correlated with the histological grade of liver fibrosis because of the associated hemodynamic abnormalities. Anatomical and pathophysiological changes in liver microcirculation are the initial events leading to PH. However, the direct relationship between HVAT and PH has not been evaluated. The present study measured both HVPG and HVAT in 71 consecutive patients with compensated cirrhosis and analyzed the relationship between the two parameters (i.e., the derivation set). Results were validated in 35 compensated patients with cirrhosis at another medical center (i.e., the validation set). The derivation set had HVPG and HVAT values of 11.4 ± 5.0 mmHg (mean ± standard deviation; range, 2-23) and 14.1 ± 3.4 seconds (range, 8.4-24.2), respectively; there was a statistically significant negative correlation between HVPG and HVAT (r(2) = 0.545; P < 0.001). The area under the receiver operating characteristic curve (AUROC) was 0.973 for clinically significant PH (CSPH; HVPG, ? 10 mmHg), and the sensitivity, specificity, positive predictive value, negative predictive value, and positive and negative likelihood ratios for CSPH for an HVAT cut-off value of 14 seconds were 92.7%, 86.7%, 90.5%, 89.7%, 6.95, and 0.08, respectively. In addition, a shorter HVAT was associated with worse Child-Pugh score (P < 0.001) and esophageal varices (P = 0.018). In the validation set, there was also a significant negative correlation between HVAT and HVPG (r(2) = 0.538; P < 0.001), and AUROC = 0.953 for CSPH. HVAT was significantly correlated with PH. These results indicate that measuring HVAT is useful for the noninvasive prediction of CSPH in patients with compensated cirrhosis. PMID:22473911

Kim, Moon Young; Suk, Ki Tae; Baik, Soon Koo; Kim, Hyoun A; Kim, Young Ju; Cha, Seung Hwan; Kwak, Hwa Ryun; Cho, Mee Yon; Park, Hong Jun; Jeon, Hyo Keun; Park, So Yeon; Kim, Bo Ra; Hong, Jin Heon; Jo, Ki Won; Kim, Jae Woo; Kim, Hyun Soo; Kwon, Sang Ok; Chang, Sei Jin; Baik, Gwang Ho; Kim, Dong Joon

2012-09-01

237

Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion Data for Three-Dimensional Seismic Velocity Structure Around SAFOD  

NASA Astrophysics Data System (ADS)

The crust around the San Andreas Fault Observatory at depth (SAFOD) has been the subject of many geophysical studies aimed at characterizing in detail the fault zone structure and elucidating the lithologies and physical properties of the surrounding rocks. Seismic methods in particular have revealed the complex two-dimensional (2D) and three-dimensional (3D) structure of the crustal volume around SAFOD and the strong velocity reduction in the fault damage zone. In this study we conduct a joint inversion using body-wave arrival times and surface-wave dispersion data to image the P-and S-wave velocity structure of the upper crust surrounding SAFOD. The two data types have complementary strengths - the body-wave data have good resolution at depth, albeit only where there are crossing rays between sources and receivers, whereas the surface waves have very good near-surface resolution and are not dependent on the earthquake source distribution because they are derived from ambient noise. The body-wave data are from local earthquakes and explosions, comprising the dataset analyzed by Zhang et al. (2009). The surface-wave data are for Love waves from ambient noise correlations, and are from Roux et al. (2011). The joint inversion code is based on the regional-scale version of the double-difference (DD) tomography algorithm tomoDD. The surface-wave inversion code that is integrated into the joint inversion algorithm is from Maceira and Ammon (2009). The propagator matrix solver in the algorithm DISPER80 (Saito, 1988) is used for the forward calculation of dispersion curves from layered velocity models. We examined how the structural models vary as we vary the relative weighting of the fit to the two data sets and in comparison to the previous separate inversion results. The joint inversion with the 'optimal' weighting shows more clearly the U-shaped local structure from the Buzzard Canyon Fault on the west side of SAF to the Gold Hill Fault on the east side.

Zhang, H.; Thurber, C. H.; Maceira, M.; Roux, P.

2013-12-01

238

Holographic p-wave superconductors from Gauss-Bonnet gravity  

SciTech Connect

We study the holographic p-wave superconductors in a five-dimensional Gauss-Bonnet gravity with an SU(2) Yang-Mills gauge field. In the probe approximation, we find that when the Gauss-Bonnet coefficient grows, the condensation of the vector field becomes harder, both the perpendicular and parallel components, with respect to the direction of the condensation, of the anisotropic conductivity decrease. We also study the mass of the quasiparticle excitations, the gap frequency and the DC conductivities of the p-wave superconductor. All of them depend on the Gauss-Bonnet coefficient. In addition, we observe a strange behavior for the condensation and the relation between the gap frequency and the mass of quasiparticles when the Gauss-Bonnet coefficient is larger than 9/100, which is the upper bound for the Gauss-Bonnet coefficient from the causality of the dual field theory.

Cai Ronggen; Nie Zhangyu; Zhang Haiqing [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China)

2010-09-15

239

P-wave baryons in the quark model  

Microsoft Academic Search

We discuss the spectrum and mixing angles of negative-parity baryons in a quark-model framework inspired by quantum chromodynamics. We take into account in zero order the removal of the degeneracy between the two P-wave states of the three-quark system in the S=-1 sector, as well as the hyperfine interaction between quarks, but neglect spin-orbit coupling. We find good agreement with

Nathan Isgur; Gabriel Karl

1978-01-01

240

Electrocardiographic P-wave characteristics in patients with psoriasis vulgaris  

PubMed Central

Purpose Psoriasis vulgaris is one of the most common skin disorders. Patients with psoriasis carry an excessive risk of atrial fibrillation (AF). The differences between the maximum (Pmax) and the minimum (Pmin) P-wave duration on ECG are defined as P-wave dispersion (PWD). Prolongation of PWD is an independent risk factor for the development of AF. The aim of this the study was to investigate P-wave duration and PWD in patients with psoriasis. Methods Sixty-one adult patients with psoriasis vulgaris (group 1) and 58 age and sex-matched healthy individuals (group 2) were included in this study. ECG recordings were obtained, and the P-wave variables were calculated. Results were reported as mean ± standard deviation and percentages. Continuous variables were analysed using Student's t test. A value of P < 0.05 was considered statistically signi?cant. Results Pmax and PWD were significantly higher in group 1 than in group 2 (108.8 ± 21.3 ms versus 93.3 ± 13.0 ms, P < 0.001; 67.4 ± 22.9 ms versus 45.0 ± 19.6 ms, P < 0.001, respectively). Also, Pmin was significantly lower in group 1 (41.3 ± 12.3 ms versus 48.3 ± 14.3 ms, P = 0.04). The psoriasis disease activity score and hsCRP correlated with PWD (P < 0.01). Conclusions Atrial conduction of sinus impulses was impaired in patients with psoriasis vulgaris. It was more prominent in patients with severe disease. Physicians caring for patients with psoriasis vulgaris should screen them for AF development. PMID:23153368

Erdogan, Ercan; Tasal, Abdurrrahman; Vatankulu, Mehmet Akif; Kul, Seref; Sevgili, Emrah; Ertas, Gokhan; Dizman, Didem; Onsun, Nahide; Uysal, Omer

2013-01-01

241

p-wave optical Feshbach resonances in {sup 171}Yb  

SciTech Connect

We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized {sup 171}Yb spin-1/2 fermions. A laser exciting two colliding atoms to the {sup 1}S{sub 0}+{sup 3}P{sub 1} channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schroedinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized {sup 171}Yb, where the three colors correspond to the three spatial orbitals of the first excited p band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.

Goyal, Krittika; Deutsch, Ivan [Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Reichenbach, Iris [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden (Germany)

2010-12-15

242

Kondo resonance from p-wave hybridization in graphene.  

PubMed

The p-wave hybridization in graphene present a distinct class of Kondo problem in pseudogap Fermi systems with bath density of states (DOS) ??(?) ? |?|. The peculiar geometry of substitutional and hollow-site ad-atoms, and effectively the vacancies allow for a p-wave form of momentum dependence in the hybridization of the associated local orbital with the Dirac fermions of the graphene host which results in a different picture than the s-wave momentum independent hybridization. For the p-wave hybridization function, away from the Dirac point we find closed-form formulae for the Kondo temperature TK which in contrast to the s-wave case is non-zero for any value of hybridization strength V of the single impurity Anderson model (SIAM). At the Dirac point where the DOS vanishes, we find a conceivably small value of Vmin above which the Kondo screening takes place even in the presence of particle-hole symmetry. We also show that the non-Lorentzian line shape of the local spectrum arising from anomalous hybridization function leads to much larger TK in vacant graphene compared to a metallic host with similar bandwidth and SIAM parameters. PMID:25237820

Jafari, S A; Tohyama, T

2014-10-15

243

p-wave optical Feshbach resonances in Yb171  

NASA Astrophysics Data System (ADS)

We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized Yb171 spin-1/2 fermions. A laser exciting two colliding atoms to the 1S0+3P1 channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region, and thus, three-body recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground-state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schrödinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply this control to propose a toy model for three-color superfluidity in an optical lattice for spin-polarized Yb171, where the three colors correspond to the three spatial orbitals of the first excited p band. We calculate the conditions under which tunneling and on-site interactions are comparable, at which point quantum critical behavior is possible.

Goyal, Krittika; Reichenbach, Iris; Deutsch, Ivan

2010-12-01

244

p-Wave Optical Feshbach Resonances in Yb-171  

E-print Network

We study the use of an optical Feshbach resonance to modify the p-wave interaction between ultracold polarized Yb-171 spin-1/2 fermions. A laser exciting two colliding atoms to the 1S_0 + 3P_1 channel can be detuned near a purely-long-range excited molecular bound state. Such an exotic molecule has an inner turning point far from the chemical binding region and thus three-body-recombination in the Feshbach resonance will be highly suppressed in contrast to that typically seen in a ground state p-wave magnetic Feshbach resonance. We calculate the excited molecular bound-state spectrum using a multichannel integration of the Schr\\"{o}dinger equation, including an external perturbation by a magnetic field. From the multichannel wave functions, we calculate the Feshbach resonance properties, including the modification of the elastic p-wave scattering volume and inelastic spontaneous scattering rate. The use of magnetic fields and selection rules for polarized light yields a highly controllable system. We apply th...

Goyal, Krittika; Deutsch, Ivan

2010-01-01

245

Laboratory monitoring of P waves in partially saturated sand  

NASA Astrophysics Data System (ADS)

Energy dissipation is observed on seismic data when a wave propagates through a porous medium, involving different frequency regimes depending on the nature of rock and fluid types. We focus here on the role of partial fluid saturation in unconsolidated porous media, looking in particular at P-wave phase velocity and attenuation. The study consists in running an experiment in a sand-filled tank partially saturated with water. Seismic propagation in the tank is generated in the kHz range by hitting a steel ball on a granite plate. Seismic data are recorded by buried accelerometers and injecting or extracting water controls the partial saturation. Several imbibition/drainage cycles were performed between the water and gas residual saturations. A Continuous Wavelet Transform applied on seismic records allowed us to extract the direct P wave at each receiver. We observe an hysteresis in phase velocities and inverse quality factors between imbibition and drainage. Phase velocities and inverse quality factors are then jointly inverted to get a final poro-viscoelastic model of the partially saturated sand that satisfactorily reproduces the data. The model formulation consists in generalizing the Biot theory to effective properties of the fluid and medium (permeability and bulk modulus) to properly explain the phase velocity variation as a function of the saturation. The strong level of attenuation measured experimentally is further explained by an anelastic effect due to grain to grain sliding, adding to Biot's losses. This study shows that fluid distribution at microscopic scale has strong influence on the attenuation of direct P waves at macroscopic scale and confirms that seismic prospection may be a powerful tool for the characterization of transport phenomena in porous media.

Barrière, Julien; Bordes, Clarisse; Brito, Daniel; Sénéchal, Pascale; Perroud, Hervé

2012-12-01

246

Hydrodynamic Modes of a holographic $p-$ wave superfluid  

E-print Network

In this work we analyze the hydrodynamics of a $p-$ wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.

Raul E. Arias; Ignacio Salazar Landea

2014-09-22

247

Hydrodynamic modes of a holographic p-wave superfluid  

NASA Astrophysics Data System (ADS)

In this work we analyze the hydrodynamics of a p- wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.

Arias, Raúl E.; Landea, Ignacio Salazar

2014-11-01

248

p-Wave Cold Collisions in an Optical Lattice Clock  

SciTech Connect

We study ultracold collisions in fermionic ytterbium by precisely measuring the energy shifts they impart on the atoms' internal clock states. Exploiting Fermi statistics, we uncover p-wave collisions, in both weakly and strongly interacting regimes. With the higher density afforded by two-dimensional lattice confinement, we demonstrate that strong interactions can lead to a novel suppression of this collision shift. In addition to reducing the systematic errors of lattice clocks, this work has application to quantum information and quantum simulation with alkaline-earth atoms.

Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Ludlow, A. D. [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Stecher, J. von; Rey, A. M. [JILA, NIST, and University of Colorado, Department of Physics, Boulder, Colorado 80309 (United States)

2011-09-02

249

p -Wave Superfluidity by Spin-Nematic Fermi Surface Deformation  

NASA Astrophysics Data System (ADS)

We study attractively interacting fermions on a square lattice with dispersion relations exhibiting strong spin-dependent anisotropy. The resulting Fermi surface mismatch suppresses the s -wave BCS-type instability, clearing the way for unconventional types of order. Unbiased sampling of the Feynman diagrammatic series using diagrammatic Monte Carlo methods reveals a rich phase diagram in the regime of intermediate coupling strength. Instead of a proposed Cooper-pair Bose metal phase [A. E. Feiguin and M. P. A. Fisher, Phys. Rev. Lett. 103, 025303 (2009)], we find an incommensurate density wave at strong anisotropy and two different p -wave superfluid states with unconventional symmetry at intermediate anisotropy.

Gukelberger, Jan; Kozik, Evgeny; Pollet, Lode; Prokof'ev, Nikolay; Sigrist, Manfred; Svistunov, Boris; Troyer, Matthias

2014-11-01

250

Hydrodynamic Modes of a holographic $p-$ wave superfluid  

E-print Network

In this work we analyze the hydrodynamics of a $p-$ wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.

Arias, Raul E

2014-01-01

251

Crustal P-wave velocity model for the central-western region of Mexico  

NASA Astrophysics Data System (ADS)

Several studies require a p-wave velocity model to obtain accurate results moreover such models could provide an insight of the tectonic structure of the study area. Accordingly, in this study we estimate the crustal 3D p-wave velocity model for the Jalisco Block located at the central-western region of Mexico. The Jalisco Block is limited on its eastern side by the Colima and Tepic-Zacoalcos Rifts, and the Trans-Mexican Volcanic Belt; while on its western side it is limited by the Mesoamerican Trench. Cocos and Rivera plates are subducting beneath the Jalisco Block conforming a tectonically complex region. We used earthquakes occurring within the limits of lithosphere volume from which we want to estimate the velocity model. Such events were registered by the Mapping the Rivera Subduction Zone experiment (MARS) and the Seismic and Acelerometric Network of Jalisco (RESAJ). During MARS experiment 51broadband stations active from January 2006 to June 2007 were deployed while RESAJ by July of 2012consists of nine active stations however more stations will be deployed until reach 30 stations. The velocity model is estimated using the Fast Marching Tomography (FMTOMO) software. FMTOMO uses the Fast Marching Method (FMM) in order to solve the forward problem; the FMM is a numerical algorithm that tracks the interfaces evolution along a nodes narrow band, and travel times are updated solving the eikonal equation. Finally , the inverse problem is about adjusting the model parameters (interface depth, velocity, hypocenter location) in order to try to satisfy the observed data (travel times). We perform a resolution test using several events that show good resolution results up to a 60 km depth. We present a 3D p-wave velocity model, we compare our results within the MARS data with previous results for greater depths, approximately the upper mantle, finally we also present studies towards the northern portion of the Jalisco Block using the RESAJ data.

Ochoa, J.; Escudero, C. R.; Perez, O. G.; Nunez-Cornu, F. J.

2012-12-01

252

Derivation of site-specific relationships between hydraulic parameters and p-wave velocities based on hydraulic and seismic tomography  

SciTech Connect

In this study, hydraulic and seismic tomographic measurements were used to derive a site-specific relationship between the geophysical parameter p-wave velocity and the hydraulic parameters, diffusivity and specific storage. Our field study includes diffusivity tomograms derived from hydraulic travel time tomography, specific storage tomograms, derived from hydraulic attenuation tomography, and p-wave velocity tomograms, derived from seismic tomography. The tomographic inversion was performed in all three cases with the SIRT (Simultaneous Iterative Reconstruction Technique) algorithm, using a ray tracing technique with curved trajectories. The experimental set-up was designed such that the p-wave velocity tomogram overlaps the hydraulic tomograms by half. The experiments were performed at a wellcharacterized sand and gravel aquifer, located in the Leine River valley near Göttingen, Germany. Access to the shallow subsurface was provided by direct-push technology. The high spatial resolution of hydraulic and seismic tomography was exploited to derive representative site-specific relationships between the hydraulic and geophysical parameters, based on the area where geophysical and hydraulic tests were performed. The transformation of the p-wave velocities into hydraulic properties was undertaken using a k-means cluster analysis. Results demonstrate that the combination of hydraulic and geophysical tomographic data is a promising approach to improve hydrogeophysical site characterization.

Brauchler, R.; Doetsch, J.; Dietrich, P.; Sauter, M.

2012-01-10

253

Rupture history of the 1997 Cariaco, Venezuela, earthquake from teleseismic P waves  

USGS Publications Warehouse

A two-step finite-fault waveform inversion scheme is applied to the broadband teleseismic P waves recorded for the strike-slip, Cariaco, Venezuela, earthquake of 9 July 1997 to recover the distribution of mainshock slip. The earthquake is first analyzed using a long narrow fault with a maximum rise time of 20 sec. This line-source analysis indicates that slip propagated to the west with a constant rupture velocity and a relatively short rise time. The results are then used to constrain a second inversion of the P waveforms using a 60-km by 20-km two-dimensional fault. The rupture shows a zone of large slip (1.3-m peak) near the hypocenter and a second, broader source extending updip and to the west at depths shallower than 5 km. The second source has a peak slip of 2.1 meters and accounts for most of the moment of 1.1 × 1026 dyne-cm (6.6 Mww) estimated from the P waves. The inferred rupture pattern is consistent with macroseismic effects observed in the epicentral area.

Mendoza, C.

2000-01-01

254

New insights on the structure of La Soufriere dome from joint inversion of P-wave velocity and density  

NASA Astrophysics Data System (ADS)

One objective of the french project Domoscan (2009-2013) was to obtain better constraints on the geological structure of La Soufriere hydrothermal system, that is the dome inner structure but also its basement that has not yet been imaged, while it may play an essential role in potential flank destabilization. In this framework, we performed a 3D gravity and P-wave travel time joint inversion to obtain density and P-wave velocity images of La Soufriere hydrothermal system (Coutant et al., 2012). The joint inversion approach was proposed to overcome the lack of resolution of the two methods taken separately. In this study, the coupling between P-wave velocity and density relies on a relationship derived from laboratory measurements on 58 samples from La Soufriere and Mt Pelee deposits. The laboratory data cover a large range of porosity (1-73%) with P wave velocity ranging from 2 to 5.4 km/s and density from 1.5 to 2.8 g/cm3 in water saturated samples. The joint inversion results show that P wave velocity model benefits from density resolution at the volcano summit, while density resolution improves at depth. The improved images allow new insights on La Soufriere structures. As an example the resistive zones that have been so far only seen by electromagnetic surveys may not be due only to argilization but may also be explained by the presence of dense massive zones, that we interpret as andesite spines resulting from 3100 B.P. or 1530 A.D eruptions. These dense bodies may have implication on the stability of the edifice and then the destabilization risks at La Soufriere of Guadeloupe. This work also shows that laboratory studies on physical properties of volcanic rocks and their relationships can be useful in the interpretation of geophysical observations on structurally complex areas such as volcano or geothermal system.

Bernard, Marie-Lise; Coutant, Olivier; Beauducel, Francois

2014-05-01

255

Mapping of shallow three dimensional variations of P-wave velocity in Garhwal Himalaya  

Microsoft Academic Search

A set of short aperture seismic arrays was operated in the Garhwal Himalaya close to the Main Central Thrust and recorded a large number of small local earthquakes. This study pertains to the inversion of the body wave arrival time data of these earthquakes to construct a seismic velocity model for the region. The analysis indicates a systematic variation in

I. Sarkar; R. Jain; K. N. Khattri

2001-01-01

256

Topological states in normal and superconducting p-wave chains  

NASA Astrophysics Data System (ADS)

We study a two-band model of fermions in a 1d chain with an antisymmetric hybridization that breaks inversion symmetry. We find that for certain values of its parameters, the sp-chain maps formally into a p-wave superconducting chain, the archetypical 1d system exhibiting Majorana fermions. The eigenspectra, including the existence of zero energy modes in the topological phase, agree for both models. The end states too share several similarities, such as the behavior of the localization length, the non-trivial topological index and robustness to disorder. However, we show that the excitations in the ends of a finite sp chain are conventional fermions though endowed with protected topological properties. Our results are obtained by a scattering approach in a semi-infinite chain with an edge defect treated within the T-matrix approximation. We present exact numerical diagonalization results that extend our analysis to arbitrary parameters and to disordered systems.

Continentino, Mucio A.; Caldas, Heron; Nozadze, David; Trivedi, Nandini

2014-10-01

257

Properties of the charmed P-wave mesons  

SciTech Connect

Two broad charmed mesons, the D{sub 0}* and D{sub 1}{sup '}, have recently been observed. We examine the quark model predictions for the D{sub 0}* and D{sub 1}{sup '} properties and discuss experimental measurements that can shed light on them. We find that these states are well described as the broad, j=1/2 nonstrange charmed P-wave mesons. Understanding the D{sub 0}* and D{sub 1}{sup '} states can provide important insights into the D{sub sJ}*(2317), D{sub sJ}(2460) states whose unexpected properties have led to renewed interest in hadron spectroscopy.

Godfrey, Stephen [Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, Ottawa, K1S 5B6 (Canada)

2005-09-01

258

A model of seismic coda arrivals to suppress spurious events.  

NASA Astrophysics Data System (ADS)

We describe a model of coda arrivals which has been added to NET-VISA (Network processing Vertically Integrated Seismic Analysis) our probabilistic generative model of seismic events, their transmission, and detection on a global seismic network. The scattered energy that follows a seismic phase arrival tends to deceive typical STA/LTA based arrival picking software into believing that a real seismic phase has been detected. These coda arrivals which tend to follow all seismic phases cause most network processing software including NET-VISA to believe that multiple events have taken place. It is not a simple matter of ignoring closely spaced arrivals since arrivals from multiple events can indeed overlap. The current practice in NET-VISA of pruning events within a small space-time neighborhood of a larger event works reasonably well, but it may mask real events produced in an after-shock sequence. Our new model allows any seismic arrival, even coda arrivals, to trigger a subsequent coda arrival. The probability of such a triggered arrival depends on the amplitude of the triggering arrival. Although real seismic phases are more likely to generate such coda arrivals. Real seismic phases also tend to generate coda arrivals with more strongly correlated parameters, for example azimuth and slowness. However, the SNR (Signal to Noise Ratio) of a coda arrival immediately following a phase arrival tends to be lower because of the nature of the SNR calculation. We have calibrated our model on historical statistics of such triggered arrivals and our inference accounts for them while searching for the best explanation of seismic events their association to the arrivals and the coda arrivals. We have tested our new model on one week of global seismic data spanning March 22, 2009 to March 29, 2009. Our model was trained on two and half months of data from April 5, 2009 to June 20, 2009. We use the LEB bulletin produced by the IDC (International Data Center) as the ground truth and computed the precision (percentage of reported events which are true) and recall (percentage of true events which are reported). The existing model has a precision of 32.2 and recall of 88.6 which changes to a precision of 50.7 and recall of 88.5 after pruning. The new model has a precision of 56.8 and recall of 86.9 without any pruning and the corresponding precision recall curve is dramatically improved. In contrast, the performance of the current automated bulletin at the IDC, SEL3, has a precision of 46.2 and recall of 69.7.

Arora, N.; Russell, S.

2012-04-01

259

Monitoring of the ultrasonic P-wave velocity in early-age concrete with embedded piezoelectric transducers  

NASA Astrophysics Data System (ADS)

This note deals with the use of embedded piezoelectric transducers to monitor the ultrasonic P-wave velocity evolution during the setting and hardening phases of concrete subsequent to casting time. The main advantage of the technique is the possibility of overcoming the limitations of traditional methods which prevent the application of specific mechanical boundary conditions during the measurement. The embedded transducers are based on the ‘smart aggregates’ concept previously developed at the University of Houston, Texas. Two piezoelectric transducers are embedded in a prismatic mold and the evolution of the P-wave velocity is recorded for the first 24 h in concrete after the casting time. The results are very promising and show a good agreement with classical ultrasonic tests using external transducers.

Dumoulin, Cédric; Karaiskos, Grigoris; Carette, Jérôme; Staquet, Stéphanie; Deraemaeker, Arnaud

2012-04-01

260

The P-wave boundary of the Large-Low Shear Velocity Province beneath the Pacific  

NASA Astrophysics Data System (ADS)

The Large Low Shear Velocity Provinces (LLSVPs) in the lower mantle represent volumetrically significant thermal or chemical or thermo-chemical heterogeneities. Their structure and boundaries have been widely studied, mainly using S-waves, but much less is known about their signature in the P-wavefield. We use an extensive dataset recorded at USArray to create, for the first time, a high-resolution map of the location, shape, sharpness, and extent of the boundary of the Pacific LLSVP using P(Pdiff)-waves. We find that the northern edge of the Pacific LLSVP is shallow dipping (26° relative to the horizontal) and diffuse (?120 km wide transition zone) whereas the eastern edge is steeper dipping (70°) and apparently sharp (?40 km wide). We trace the LLSVP boundary up to ?500 km above the CMB in most areas, and 700 km between 120° and 90°W at the eastern extent of the boundary. Apparent P-wave velocity drops are ?1-3% relative to PREM, indicating a strong influence of LLSVPs on P-wave velocity, at least in the high-frequency wavefield, in contrast to previous studies. A localised patch with a greater velocity drop of ?15-25% is detected, defined by large magnitude gradients of the travel-time residuals. We identify this as a likely location of an Ultra-Low Velocity Zone (ULVZ), matching the location of a previously detected ULVZ in this area. The boundary of a separate low velocity anomaly, of a similar height to the LLSVP, is detected in the north-west Pacific, matching tomographic images. This outlier appears to be connected to the main LLSVP through a narrow channel close to the CMB and may be in the process of joining or splitting from the main LLSVP. We also see strong velocity increases in the lower mantle to the east of the LLSVP, likely detecting subducted material beneath central America. The LLSVP P-wave boundary is similar to that determined in high-resolution S-wave studies and follows the -0.4% ?VS iso-velocity contour in the S40RTS tomography model. Additionally, the LLSVP boundary roughly matches the shape of the -0.4% ?VP iso-velocity contour of the P-wave model GyPSuM but defines an area more similar to that defined by the 0.0% VP iso-velocity contour. High resolution P-wave velocity determination allows for estimation of the ratio of P- and S-wave velocity anomalies (RS,P) which can be used to indicate dominantly thermal or chemical control of seismic velocities. Although the RS,P is found here to be approximately 2.4, which is indicative of a thermo-chemical anomaly. However, this result contains a large amount of uncertainty and the implications for the origin of LLSVPs likely remain inconclusive. Nonetheless, other observations of the Pacific LLSVP are consistent with a thermo-chemical anomaly whose shape and boundary sharpness are controlled by proximity to active and past subduction.

Frost, Daniel A.; Rost, Sebastian

2014-10-01

261

Signal processing and tracking of arrivals in ocean acoustic tomography.  

PubMed

The signal processing for ocean acoustic tomography experiments has been improved to account for the scattering of the individual arrivals. The scattering reduces signal coherence over time, bandwidth, and space. In the typical experiment, scattering is caused by the random internal-wave field and results in pulse spreading (over arrival-time and arrival-angle) and wander. The estimator-correlator is an effective procedure that improves the signal-to-noise ratio of travel-time estimates and also provides an estimate of signal coherence. The estimator-correlator smoothes the arrival pulse at the expense of resolution. After an arrival pulse has been measured, it must be associated with a model arrival, typically a ray arrival. For experiments with thousands of transmissions, this is a tedious task that is error-prone when done manually. An error metric that accounts for peak amplitude as well as travel-time and arrival-angle can be defined. The Viterbi algorithm can then be adapted to the task of automated peak tracking. Repeatable, consistent results are produced that are superior to a manual tracking procedure. The tracking can be adjusted by tuning the error metric in logical, quantifiable manner. PMID:25373953

Dzieciuch, Matthew A

2014-11-01

262

An efficient hybrid pseudospectral/finite-difference scheme for solving the TTI pure P-wave equation  

NASA Astrophysics Data System (ADS)

The pure P-wave equation for modelling and migration in tilted transversely isotropic (TTI) media has attracted more and more attention in imaging seismic data with anisotropy. The desirable feature is that it is absolutely free of shear-wave artefacts and the consequent alleviation of numerical instabilities generally suffered by some systems of coupled equations. However, due to several forward-backward Fourier transforms in wavefield updating at each time step, the computational cost is significant, and thereby hampers its prevalence. We propose to use a hybrid pseudospectral (PS) and finite-difference (FD) scheme to solve the pure P-wave equation. In the hybrid solution, most of the cost-consuming wavenumber terms in the equation are replaced by inexpensive FD operators, which in turn accelerates the computation and reduces the computational cost. To demonstrate the benefit in cost saving of the new scheme, 2D and 3D reverse-time migration (RTM) examples using the hybrid solution to the pure P-wave equation are carried out, and respective runtimes are listed and compared. Numerical results show that the hybrid strategy demands less computation time and is faster than using the PS method alone. Furthermore, this new TTI RTM algorithm with the hybrid method is computationally less expensive than that with the FD solution to conventional TTI coupled equations.

Zhan, Ge; Pestana, Reynam C.; Stoffa, Paul L.

2013-04-01

263

Joint Tomography of Body Wave and Surface Wave Phase Arrival Times for Lithospheric Structure beneath Central Tibet Using a Fully 3-D Multi-scale Finite-frequency Approach  

NASA Astrophysics Data System (ADS)

As body and surface wave phase arrivals provide complementary constraints on crust and mantle structures, we here introduce a self-consistent methodology to jointly invert body and surface wave data for shear velocity variations under regional arrays. The approach combines a fully 3-D finite-frequency theory and wavelet-based, multi-scale parameterization to deal with two major concerns in tomographic inverse problems that inevitably arise from the intrinsic wave diffraction and scattering and from uneven source-receiver distributions. To properly account for finite-frequency wave propagation, we use the computationally-efficient expressions of 3-D Born-Fréchet kernels, formulated in the framework of body-wave ray summation and surface-wave mode summation, respectively, to construct the partial derivatives of frequency-dependent arrival time data to 3-D elastic wavespeed perturbations. To achieve both spectral resolution for long-wavelength structure in regions of sparse data coverage and spatial resolution in densely-sampled regions, we employ a flexible, data-adaptive scheme of non-stationary parameterization and regularization by means of the hierarchical wavelet decomposition. We demonstrate this innovated method by applying it to tomographic imaging of shear wave velocity structure beneath central Tibet, where Project Hi-CLIMB deployed a dense seismic array of over 200 broadband stations across the Himalayan-Tibetan orogen during 2002-2005, used to illuminate the geodynamic nature responsible for the most prominent zone of active continental collision.

Hung, S.; Jheng, Y.; Zhou, Y.

2012-12-01

264

P-wave charmed baryons from QCD sum rules  

E-print Network

We study the P-wave charmed baryons using the method of QCD sum rule in the framework of heavy quark effective theory (HQET). We consider systematically all possible baryon currents with a derivative for internal rho- and lambda-mode excitations. We have found good working window for the currents corresponding to the rho-mode excitations for Lambda_c(2595), Lambda_c(2625), Xi_c(2790) and Xi_c(2815) which complete two SU(3) 3F_bar multiplets of J(P)=1/2(-) and 3/2(-), while the currents corresponding to the lambda-mode excitations seem also consistent with the data. Our results also suggest that there are two Sigma_c(2800) states of J(P)=1/2(-) and 3/2(-) whose mass splitting is 14 \\pm 7 MeV, and two Xi_c(2980) states whose mass splitting is 12 \\pm 7 MeV. They have two Omega_c partners of J(P) = 1/2(-) and 3/2(-), whose masses are around 3.25 \\pm 0.20 GeV with mass splitting 10 \\pm 6 MeV. All of them together complete two SU(3) 6F multiplets of J(P)=1/2(-) and 3/2(-). They may also have J(P)=5/2(-) partners. X...

Chen, Hua-Xing; Mao, Qiang; Hosaka, Atsushi; Liu, Xiang; Zhu, Shi-Lin

2015-01-01

265

Knowledge-based scheduling of arrival aircraft  

NASA Technical Reports Server (NTRS)

A knowledge-based method for scheduling arrival aircraft in the terminal area has been implemented and tested in real-time simulation. The scheduling system automatically sequences, assigns landing times, and assigns runways to arrival aircraft by utilizing continuous updates of aircraft radar data and controller inputs. The scheduling algorithms is driven by a knowledge base which was obtained in over two thousand hours of controller-in-the-loop real-time simulation. The knowledge base contains a series of hierarchical 'rules' and decision logic that examines both performance criteria, such as delay reduction, as well as workload reduction criteria, such as conflict avoidance. The objective of the algorithms is to devise an efficient plan to land the aircraft in a manner acceptable to the air traffic controllers. This paper will describe the scheduling algorithms, give examples of their use, and present data regarding their potential benefits to the air traffic system.

Krzeczowski, K.; Davis, T.; Erzberger, H.; Lev-Ram, I.; Bergh, C.

1995-01-01

266

Arrivals & Departures diplomas. If you  

E-print Network

Arrivals & Departures diplomas. If you think about it, all those people have diplomas signed by one of four different gov- ernors, but those diplomas are all signed by the same chancellor. Second, I saw

de Lijser, Peter

267

[A P-wave detection method based on multi-feature].  

PubMed

Generally, P-wave is the wave of low-frequency and low-amplitude, and it could be affected by baseline drift, electromyography (EMG) interference and other noises easily. Not every heart beat contains the P-wave, and it is also a major problem to determine the P-wave exist or not in a heart beat. In order to solve the limitation of suiting the diverse morphological P-wave using wavelet-amplitude-transform algorithm and the limitation of selecting the pseudo-P-wave sample using the wavelet transform and neural network, we presented new P-wave detecting method based on wave-amplitude threshold and using the multi-feature as the input of neural networks. Firstly, we removed the noise of ECG through the wavelet transform, then determined the position of the candidate P-wave by calculating modulus maxima of the wavelet transform, and then determine the P-wave exist or not by wave-amplitude threshold method initially. Finally we determined whether the P-wave existed or not by the neural networks. The method is validated based on the QT database which is supplied with manual labels made by physicians. We compared the detection effect of ECG P-waves, which was obtained with the method developed in the study, with the algorithm of wavelet threshold value and the method based on "wavelet-amplitude-slope", and verified the feasibility of the proposed algorithm. The detected ECG signal, which is recorded in the hospital ECG division, was consistent with the doctor's labels. Furthermore, after detecting the 13 sets of ECG which were 15 min long, the detection rate for the correct P-wave is 99.911%. PMID:25039128

Song, Lixin; Guan, Lili; Wang, Qian; Wang, Yuhong

2014-04-01

268

The correlations between the saturated and dry P-wave velocity of rocks.  

PubMed

Sometimes engineers need to estimate the wet-rock P-wave velocity from the dry-rock P-wave velocity. An estimation equation embracing all rock classes will be useful for the rock engineers. To investigate the predictability of wet-rock P-wave velocity from the dry-rock P-wave velocity, P-wave velocity measurements were performed on 41 different rock types, 11 of which were igneous, 15 of which were sedimentary and 15 of which was metamorphic. In addition to the dry- and wet-rock P-wave velocity measurements, the P-wave velocity changing as a function of saturation degree was studied. Moreover, dry-rock S-wave velocity measurements were conducted. The test results were modeled using Gassmann's and Wood's theory and it was seen that the measured data did not fit the theories. The unconformity is due to the fact that the theories are valid for high-porosity unconsolidated sediments at low frequencies. Gassmann's equation was modified for the rocks except high-porosity unconsolidated sediments. The dry- and wet-rock P-wave velocity values were evaluated using regression analysis. A strong linear correlation between the dry- and wet-rock P-wave velocities was found. Regression analyses were repeated for the rock classes and it was shown that correlation coefficients were increased. Concluding remark is that the derived equations can be used for the prediction of wet-rock P-wave velocity from the dry-rock P-wave velocity. PMID:17624388

Kahraman, S

2007-11-01

269

Eternal inflation with arrival terminals  

NASA Astrophysics Data System (ADS)

We analyze the cosmological role of terminal vacua in the string theory landscape, and point out that existing work on this topic makes very strong assumptions about the properties of the terminal vacua. We explore the implications of relaxing these assumptions (by including "arrival" as well as "departure" terminals) and demonstrate that the results in earlier work are highly sensitive to their assumption of no arrival terminals. We use our discussion to make some general points about tuning and initial conditions in cosmology.

Stoltenberg, Henry; Albrecht, Andreas

2015-01-01

270

A statistical study of the performance of the Hakamada-Akasofu-Fry version 2 numerical model in predicting solar shock arrival times at Earth during different phases of solar cycle 23  

NASA Astrophysics Data System (ADS)

The performance of the Hakamada Akasofu-Fry, version 2 (HAFv.2) numerical model, which provides predictions of solar shock arrival times at Earth, was subjected to a statistical study to investigate those solar/interplanetary circumstances under which the model performed well/poorly during key phases (rise/maximum/decay) of solar cycle 23. In addition to analyzing elements of the overall data set (584 selected events) associated with particular cycle phases, subsets were formed such that those events making up a particular sub-set showed common characteristics. The statistical significance of the results obtained using the various sets/subsets was generally very low and these results were not significant as compared with the hit by chance rate (50%). This implies a low level of confidence in the predictions of the model with no compelling result encouraging its use. However, the data suggested that the success rates of HAFv.2 were higher when the background solar wind speed at the time of shock initiation was relatively fast. Thus, in scenarios where the background solar wind speed is elevated and the calculated success rate significantly exceeds the rate by chance, the forecasts could provide potential value to the customer. With the composite statistics available for solar cycle 23, the calculated success rate at high solar wind speed, although clearly above 50%, was indicative rather than conclusive. The RMS error estimated for shock arrival times for every cycle phase and for the composite sample was in each case significantly better than would be expected for a random data set. Also, the parameter "Probability of Detection, yes" (PODy) which presents the Proportion of Yes observations that were correctly forecast (i.e. the ratio between the shocks correctly predicted and all the shocks observed), yielded values for the rise/maximum/decay phases of the cycle and using the composite sample of 0.85, 0.64, 0.79 and 0.77, respectively. The statistical results obtained through detailed analysis of the available data provided insights into how changing circumstances on the Sun and in interplanetary space can affect the performance of the model. Since shock arrival predictions are widely utilized in making commercially significant decisions re. protecting space assets, the present detailed archival studies can be useful in future operational decision making during solar cycle 24. It would be of added value in this context to use Briggs-Rupert methodology to estimate the cost to an operator of acting on an incorrect forecast.

McKenna-Lawlor, S. M. P.; Fry, C. D.; Dryer, M.; Heynderickx, D.; Kecskemety, K.; Kudela, K.; Balaz, J.

2012-02-01

271

High-frequency P-wave seismic noise driven by ocean winds Jian Zhang,1  

E-print Network

High-frequency P-wave seismic noise driven by ocean winds Jian Zhang,1 Peter Gerstoft,1 and Peter M] Earth's background vibrations at frequencies below about 0.5 Hz have been attributed to ocean-wave with the offshore wind speed, demonstrating that these high-frequency P- waves are excited by distant ocean winds

Shearer, Peter

272

Increases in P-Wave Dispersion Predict Postoperative Atrial Fibrillation After Coronary Artery Bypass Graft Surgery  

Microsoft Academic Search

Atrial fibrillation (AF) is a common complication after coronary artery bypass graft (CABG) surgery. In this study we examined the effect of surgery on atrial elec- trophysiology as measured by P-wave characteristics and to determine the potential predictive value of P-wave characteristics on the incidences of postopera- tive AF in patients undergoing CABG surgery. Patients undergoing elective CABG surgery were

Joby Chandy; Toshiko Nakai; Randall J. Lee; Wayne H. Bellows; Samir Dzankic; Jacqueline M. Leung

2004-01-01

273

Upper-mantle structure beneath the Southern Scandes Mountains and the Northern Tornquist Zone revealed by P-wave traveltime tomography  

NASA Astrophysics Data System (ADS)

This study images upper-mantle structure beneath different tectonic and geomorphological provinces in southern Scandinavia by P-wave traveltime tomography based on teleseismic events. We present results using integrated data from several individual projects (CALAS, MAGNUS, SCANLIPS, CENMOVE and Tor) with a total of 202 temporary seismological stations deployed in southern Norway, southern Sweden, Denmark and the northernmost part of Germany. These stations, together with 18 permanent stations, yield a high density data coverage and enable presentation of the first high resolution 3D seismic velocity model for the upper mantle for this region, which includes the entire northern part of the prominent Tornquist Zone and the Southern Scandes Mountains. P-wave arrival time residuals of up to ±1 s are observed indicating large seismic velocity contrasts at depths. Relative regional as well as absolute global tomographic inversion is carried out and consistently show upper-mantle velocity variations relative to the ak135 global reference model of up to ±2-3 per cent corresponding to P-wave velocity differences of 0.4-0.5 km s-1 from depths of about 100 km to more than 300 km. High upper-mantle velocities are observed to great depth to the east in Baltic Shield areas of southwestern Sweden suggesting the existence of a deep lithosphere keel. Lower velocities are found to the west and southwest beneath the Danish and North German sedimentary basins and in most of southern Norway. A well defined, generally narrow and deep boundary is observed between areas of contrasting upper-mantle seismic velocity. In the southern part of the study area, this boundary is localized along and east of the Sorgenfrei-Tornquist Zone. It seems to follow the eastern boundary of a zone of significant Late Carboniferous-Permian volcanic activity from southwestern Sweden to the Oslo Graben area. To the north, it crosses shield units, Caledonides as well as areas of high topography. Supported by independent results of surface wave studies, we interpret this velocity boundary as a first order lithosphere boundary representing the southwestern edge of thick shield lithosphere. In basin areas to the southwest, low upper-mantle velocities are associated with asthenosphere beneath thinned lithosphere and velocity contrasts are likely to arise mainly from temperature differences. To the north structural and geodynamic relations are more complex and both temperature and compositional differences may play a part. Reduced upper-mantle velocity beneath southern Norway also seems, despite relatively low heat flow, to be associated with areas of thinned lithosphere, pointing towards increased temperatures and reduced density in the upper mantle. This feature extends over large areas and seems not directly correlated to the shorter wavelength high topography of the Scandes Mountains, but may contribute with some isostatic buoyancy on a regional scale. For this northern area, there is no obvious geodynamic explanation to reduced upper-mantle velocity. A number of candidates are available including deep transient thermal influence from basin areas to the southwest.

Medhus, A. B.; Balling, N.; Jacobsen, B. H.; Weidle, C.; England, R. W.; Kind, R.; Thybo, H.; Voss, P.

2012-06-01

274

X(3915) and X(4350) as New Members in the P-Wave Charmonium Family  

SciTech Connect

The analysis of the mass spectrum and the calculation of the strong decay of P-wave charmonium states strongly purport to explain the newly observed X(3915) and X(4350) as new members in the P-wave charmonium family, i.e., chi{sub c0}{sup '} for X(3915) and chi{sub c2}{sup ''} for X(4350). Under the P-wave charmonium assignment to X(3915) and X(4350), the J{sup PC} quantum numbers of X(3915) and X(4350) must be 0{sup ++} and 2{sup ++} respectively, which provide important criteria to test the P-wave charmonium explanation for X(3915) and X(4350) proposed by this Letter. The decay behavior of the remaining two P-wave charmonium states with the second radial excitation is predicted, and an experimental search for them is suggested.

Liu Xiang; Sun Zhifeng [School of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Research Center for Hadron and CSR Physics, Lanzhou University and Institute of Modern Physics of CAS, Lanzhou 730000 (China); Luo Zhigang [School of Physics, Peking University, Beijing 100871 (China)

2010-03-26

275

Model input and output files for the simulation of time of arrival of landfill leachate at the water table, Municipal Solid Waste Landfill Facility, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso County, Texas  

USGS Publications Warehouse

This report contains listings of model input and output files for the simulation of the time of arrival of landfill leachate at the water table from the Municipal Solid Waste Landfill Facility (MSWLF), about 10 miles northeast of downtown El Paso, Texas. This simulation was done by the U.S. Geological Survey in cooperation with the U.S. Department of the Army, U.S. Army Air Defense Artillery Center and Fort Bliss, El Paso, Texas. The U.S. Environmental Protection Agency-developed Hydrologic Evaluation of Landfill Performance (HELP) and Multimedia Exposure Assessment (MULTIMED) computer models were used to simulate the production of leachate by a landfill and transport of landfill leachate to the water table. Model input data files used with and output files generated by the HELP and MULTIMED models are provided in ASCII format on a 3.5-inch 1.44-megabyte IBM-PC compatible floppy disk.

Abeyta, Cynthia G.; Frenzel, Peter F.

1999-01-01

276

Fluid pressure arrival time tomography: Estimation and assessment in the presence of inequality constraints, with an application to a producing gas field at Krechba, Algeria  

SciTech Connect

Deformation in the overburden proves useful in deducing spatial and temporal changes in the volume of a producing reservoir. Based upon these changes we estimate diffusive travel times associated with the transient flow due to production, and then, as the solution of a linear inverse problem, the effective permeability of the reservoir. An advantage an approach based upon travel times, as opposed to one based upon the amplitude of surface deformation, is that it is much less sensitive to the exact geomechanical properties of the reservoir and overburden. Inequalities constrain the inversion, under the assumption that the fluid production only results in pore volume decreases within the reservoir. We apply the formulation to satellite-based estimates of deformation in the material overlying a thin gas production zone at the Krechba field in Algeria. The peak displacement after three years of gas production is approximately 0.5 cm, overlying the eastern margin of the anticlinal structure defining the gas field. Using data from 15 irregularly-spaced images of range change, we calculate the diffusive travel times associated with the startup of a gas production well. The inequality constraints are incorporated into the estimates of model parameter resolution and covariance, improving the resolution by roughly 30 to 40%.

Rucci, A.; Vasco, D.W.; Novali, F.

2010-04-01

277

Comparison of interplanetary CME arrival times and solar wind parameters based on the WSA-ENLIL model with three cone types and observations  

NASA Astrophysics Data System (ADS)

We have made a comparison between coronal mass ejection (CME)-associated shock propagations based on the Wang-Sheeley-Arge (WSA)-ENLIL model using three cone types and in situ observations. For this we use 28 full-halo CMEs, whose cone parameters are determined and their corresponding interplanetary shocks were observed at the Earth, from 2001 to 2002. We consider three different cone types (an asymmetric cone model, an ice cream cone model, and an elliptical cone model) to determine 3-D CME cone parameters (radial velocity, angular width, and source location), which are the input values of the WSA-ENLIL model. The mean absolute error of the CME-associated shock travel times for the WSA-ENLIL model using the ice-cream cone model is 9.9 h, which is about 1 h smaller than those of the other models. We compare the peak values and profiles of solar wind parameters (speed and density) with in situ observations. We find that the root-mean-square errors of solar wind peak speed and density for the ice cream and asymmetric cone model are about 190 km/s and 24/cm3, respectively. We estimate the cross correlations between the models and observations within the time lag of ± 2 days from the shock travel time. The correlation coefficients between the solar wind speeds from the WSA-ENLIL model using three cone types and in situ observations are approximately 0.7, which is larger than those of solar wind density (cc ˜0.6). Our preliminary investigations show that the ice cream cone model seems to be better than the other cone models in terms of the input parameters of the WSA-ENLIL model.

Jang, Soojeong; Moon, Y.-J.; Lee, Jae-Ok; Na, Hyeonock

2014-09-01

278

19 CFR 122.118 - Exportation from port of arrival.  

...TREASURY AIR COMMERCE REGULATIONS Transit Air Cargo Manifest (TACM) Procedures...port of arrival. (a) Application. Transit air cargo may be transferred for exportation...other Federal agencies. (b) Time. Transit air cargo shall be exported from...

2014-04-01

279

STAFFING A CALL CENTER WITH UNCERTAIN ARRIVAL RATE AND ABSENTEEISM  

Microsoft Academic Search

This paper proposes simple methods for sta-ng a single-class call center with uncertain arrival rate and uncertain sta-ng due to employee absenteeism. The arrival rate and the proportion of servers present are treated as random variables. The basic model is a multi-server queue with customer abandonment, allowing non-exponential service-time and time-to-abandon dis- tributions. The goal is to maximize the expected

Ward Whitt

280

Acoustic Source Localization via Time Difference of Arrival Estimation for Distributed Sensor Networks using Tera-scale Optical-Core Devices  

SciTech Connect

For real-time acoustic source localization applications, one of the primary challenges is the considerable growth in computational complexity associated with the emergence of ever larger, active or passive, distributed sensor networks. These sensors rely heavily on battery-operated system components to achieve highly functional automation in signal and information processing. In order to keep communication requirements minimal, it is desirable to perform as much processing on the receiver platforms as possible. However, the complexity of the calculations needed to achieve accurate source localization increases dramatically with the size of sensor arrays, resulting in substantial growth of computational requirements that cannot be readily met with standard hardware. One option to meet this challenge builds upon the emergence of digital optical-core devices. The objective of this work was to explore the implementation of key building block algorithms used in underwater source localization on the optical-core digital processing platform recently introduced by Lenslet Inc. This demonstration of considerably faster signal processing capability should be of substantial significance to the design and innovation of future generations of distributed sensor networks.

Imam, Neena [ORNL; Barhen, Jacob [ORNL

2009-01-01

281

A Powerful Twin Arrives  

NASA Astrophysics Data System (ADS)

First Images from FORS2 at VLT KUEYEN on Paranal The first, major astronomical instrument to be installed at the ESO Very Large Telescope (VLT) was FORS1 ( FO cal R educer and S pectrograph) in September 1998. Immediately after being attached to the Cassegrain focus of the first 8.2-m Unit Telescope, ANTU , it produced a series of spectacular images, cf. ESO PR 14/98. Many important observations have since been made with this outstanding facility. Now FORS2 , its powerful twin, has been installed at the second VLT Unit Telescope, KUEYEN . It is the fourth major instrument at the VLT after FORS1 , ISAAC and UVES.. The FORS2 Commissioning Team that is busy installing and testing this large and complex instrument reports that "First Light" was successfully achieved already on October 29, 1999, only two days after FORS2 was first mounted at the Cassegrain focus. Since then, various observation modes have been carefully tested, including normal and high-resolution imaging, echelle and multi-object spectroscopy, as well as fast photometry with millisecond time resolution. A number of fine images were obtained during this work, some of which are made available with the present Press Release. The FORS instruments ESO PR Photo 40a/99 ESO PR Photo 40a/99 [Preview - JPEG: 400 x 345 pix - 203k] [Normal - JPEG: 800 x 689 pix - 563kb] [Full-Res - JPEG: 1280 x 1103 pix - 666kb] Caption to PR Photo 40a/99: This digital photo shows the twin instruments, FORS2 at KUEYEN (in the foreground) and FORS1 at ANTU, seen in the background through the open ventilation doors in the two telescope enclosures. Although they look alike, the two instruments have specific functions, as described in the text. FORS1 and FORS2 are the products of one of the most thorough and advanced technological studies ever made of a ground-based astronomical instrument. They have been specifically designed to investigate the faintest and most remote objects in the universe. They are "multi-mode instruments" that may be used in several different observation modes. FORS2 is largely identical to FORS1 , but there are a number of important differences. For example, it contains a Mask Exchange Unit (MXU) for laser-cut star-plates [1] that may be inserted at the focus, allowing a large number of spectra of different objects, in practice up to about 70, to be taken simultaneously. Highly sophisticated software assigns slits to individual objects in an optimal way, ensuring a great degree of observing efficiency. Instead of the polarimetry optics found in FORS1 , FORS2 has new grisms that allow the use of higher spectral resolutions. The FORS project was carried out under ESO contract by a consortium of three German astronomical institutes, the Heidelberg State Observatory and the University Observatories of Göttingen and Munich. The participating institutes have invested a total of about 180 man-years of work in this unique programme. The photos below demonstrate some of the impressive possibilities with this new instrument. They are based on observations with the FORS2 standard resolution collimator (field size 6.8 x 6.8 armin = 2048 x 2048 pixels; 1 pixel = 0.20 arcsec). In addition, observations of the Crab pulsar demonstrate a new observing mode, high-speed photometry. Protostar HH-34 in Orion ESO PR Photo 40b/99 ESO PR Photo 40b/99 [Preview - JPEG: 400 x 444 pix - 220kb] [Normal - JPEG: 800 x 887 pix - 806kb] [Full-Res - JPEG: 2000 x 2217 pix - 3.6Mb] The Area around HH-34 in Orion ESO PR Photo 40c/99 ESO PR Photo 40c/99 [Preview - JPEG: 400 x 494 pix - 262kb] [Full-Res - JPEG: 802 x 991 pix - 760 kb] The HH-34 Superjet in Orion (centre) PR Photo 40b/99 shows a three-colour composite of the young object Herbig-Haro 34 (HH-34) , now in the protostar stage of evolution. It is based on CCD frames obtained with the FORS2 instrument in imaging mode, on November 2 and 6, 1999. This object has a remarkable, very complicated appearance that includes two opposite jets that ram into the surrounding interstellar matter. This structure is produced by a machine-gu

1999-11-01

282

Coexistence and competition of ferromagnetism and p -wave superconductivity in holographic model  

NASA Astrophysics Data System (ADS)

By combining a holographic p -wave superconductor model and a holographic ferromagnetism model, we study the coexistence and competition of ferromagnetism and p -wave superconductivity. It is found that the results depend on the self-interaction of magnetic moment of the complex vector field and which phase appears first. In the case where the ferromagnetic phase appears first, if the interaction is attractive, the system shows the ferromagnetism and superconductivity can coexist at low temperatures. If the interaction is repulsive, the system will only be in a pure ferromagnetic state. In the case where the superconducting phase appears first, the attractive interaction will lead to a magnetic p -wave superconducting phase at low temperatures. If the interaction is repulsive, the system will be in a pure p -wave superconducting phase or a ferromagnetic phase when the temperature is lowered.

Cai, Rong-Gen; Yang, Run-Qiu

2015-01-01

283

Coexistence and competition of ferromagnetism and p-wave superconductivity in holographic model  

E-print Network

By combining a holographic p-wave superconductor model and a holographic ferromagnetism model, we study the coexistence and competition of ferromagnetism and p-wave superconductivity. It is found that the results depend on the self-interaction of magnetic moment of the complex vector field and which phase appears first. In the case that the ferromagnetic phase appears first, if the interaction is attractive, the system shows the ferromagnetism and superconductivity can coexist in low temperatures. If the interaction is repulsive, the system will only be in a pure ferromagnetic state. In the case that the superconducting phase appears first, the attractive interaction will leads to a magnetic p-wave superconducting phase in low temperatures. If the interaction is repulsive, the system will be in a pure p-wave superconducting phase or ferromagnetic phase when the temperature is lowered.

Rong-Gen Cai; Run-Qiu Yang

2014-10-19

284

Analysis of P-wave seismic response for fracture detection: modelling and case studies   

E-print Network

This thesis addresses a few specific issues in the use of wide azimuth P-wave seismic data for fracture detection based on numerical modelling and real data. These issues include the seismic response of discrete fractures, ...

Xu, Yungui

2012-06-25

285

Near-surface seismic attenuation of P-waves in West Texas  

E-print Network

(Member) Robert R. Berg (Member) el S. Watkins (Head of Department) August 1992 ABSTRACT Near-surface Seismic Attenuation of P-Waves in West Texas. (August 1992) Said Awdhah AI-Zahrani, B. S, University of Petroleum and Minerals, Dhahran, Saudi... Arabia Chair of Advisory Committee: Dr. Steven H. Harder Field experiments were conducted near Monahans, Texas, to measure the seismic P-wave attenuation of near-surface sediments. The field measurements consisted of recording two dynamite shots at a...

Al-Zahrani, Said Awdhah

1992-01-01

286

P Wave Area for Quantitative Electrocardiographic Assessment of Left Atrial Remodeling  

PubMed Central

Background Left atrial (LA) dilation provides a substrate for mitral regurgitation (MR) and atrial arrhythmias. ECG can screen for LA dilation but standard approaches do not assess LA geometry as a continuum, as does non-invasive imaging. This study tested ECG-quantified P wave area as an index of LA geometry. Methods and Results 342 patients with CAD underwent ECG and CMR within 7 (0.1±1.4) days. LA area on CMR correlated best with P wave area in ECG lead V1 (r?=?0.42, p<0.001), with lesser correlations for P wave amplitude and duration. P wave area increased stepwise in relation to CMR-evidenced MR severity (p<0.001), with similar results for MR on echocardiography (performed in 86% of patients). Pulmonary arterial (PA) pressure on echo was increased by 50% among patients in the highest (45±14 mmHg) vs. the lowest (31±9 mmHg) P wave area quartile of the population. In multivariate regression, CMR and echo-specific models demonstrated P wave area to be independently associated with LA size after controlling for MR, as well as echo-evidenced PA pressure. Clinical follow-up (mean 2.4±1.9 years) demonstrated ECG and CMR to yield similar results for stratification of arrhythmic risk, with a 2.6-fold increase in risk for atrial fibrillation/flutter among patients in the top P wave area quartile of the population (CI 1.1–5.9, p?=?0.02), and a 3.2-fold increase among patients in the top LA area quartile (CI 1.4–7.0, p?=?0.005). Conclusions ECG-quantified P wave area provides an index of LA remodeling that parallels CMR-evidenced LA chamber geometry, and provides similar predictive value for stratification of atrial arrhythmic risk. PMID:24901435

Weinsaft, Jonathan W.; Kochav, Jonathan D.; Kim, Jiwon; Gurevich, Sergey; Volo, Samuel C.; Afroz, Anika; Petashnick, Maya; Kim, Agnes; Devereux, Richard B.; Okin, Peter M.

2014-01-01

287

Geohydrology of the unsaturated zone and simulated time of arrival of landfill leachate at the water table, municipal solid waste landfill facility, US Army Air Defense Artillery Center and Fort Bliss, El Paso County, Texas  

USGS Publications Warehouse

The U.S. Air Defense Artillery Center and Fort Bliss Municipal Solid Waste Landfill Facility (MSWLF) is located about 10 miles northeast of downtown El Paso, Texas. The landfill is built on the Hueco Bolson, a deposit that yields water to five public-supply wells within 1.1 miles of the landfill boundary on all sides. The bolson deposits consist of lenses and mixtures of sand, clay, silt, gravel, and caliche. The unsaturated zone at the landfill is about 300 feet thick. The Hydrologic Evaluation of Landfill Performance (HELP) and the Multimedia Exposure Assessment Model for Evaluating the Land Disposal of Wastes (MULTIMED) computer models were used to simulate the time of first arrival of landfill leachate at the water table. Site-specific data were collected for model input. At five sites on the landfill cover, hydraulic conductivity was measured by an in situ method; in addition, laboratory values were obtained for porosity, moisture content at field capacity, and moisture content at wilting point. Twenty-seven sediment samples were collected from two adjacent boreholes drilled near the southwest corner of the landfill. Of these, 23 samples were assumed to represent the unsaturated zone beneath the landfill. The core samples were analyzed in the laboratory for various characteristics required for the HELP and MULTIMED models: initial moisture content, dry bulk density, porosity, saturated hydraulic conductivity, moisture retention percentages at various suction values, total organic carbon, and pH. Parameters were calculated for the van Genuchten and Brooks-Corey equations that relate hydraulic conductivity to saturation. A reported recharge value of 0.008 inch per year was estimated on the basis of soil- water chloride concentration. The HELP model was implemented using input values that were based mostly on site-specific data or assumed in a conservative manner. Exceptions were the default values used for waste characteristics. Flow through the landfill was assumed to be at steady state. The HELP-estimated landfill leakage rate was 101.6 millimeters per year, approximately 500 times the estimated recharge rate for the area near the landfill. The MULTIMED model was implemented using input values that were based mainly on site-specific data and some conservatively assumed values. Landfill leakage was assumed to begin when the landfill was established and to continue at a steady-state rate of 101.6 millimeters per year as estimated by the HELP model. By using an assumed solute concentration in the leachate of 1 milligram per liter and assuming no delay or decay of solute, the solute serves as a tracer to indicate the first arrival of landfill leachate. The simulated first arrival of leachate at the water table was 204 to 210 years after the establishment of the landfill.

Frenzel, Peter F.; Abeyta, Cynthia G.

1999-01-01

288

Direction of Arrival Estimation Using the Parameterized Spatial Correlation Matrix  

Microsoft Academic Search

The estimation of the direction-of-arrival (DOA) of one or more acoustic sources is an area that has generated much interest in recent years, with applications like automatic video camera steering and multiparty stereophonic teleconferencing entering the market. DOA estimation algorithms are hindered by the effects of background noise and reverberation. Methods based on the time-differences-of-arrival (TDOA) are commonly used to

Jacek Dmochowski; Jacob Benesty; Sofiène Affes

2007-01-01

289

Estimating Controller Intervention Probabilities for Optimized Profile Descent Arrivals  

NASA Technical Reports Server (NTRS)

Simulations of arrival traffic at Dallas/Fort-Worth and Denver airports were conducted to evaluate incorporating scheduling and separation constraints into advisories that define continuous descent approaches. The goal was to reduce the number of controller interventions required to ensure flights maintain minimum separation distances of 5 nmi horizontally and 1000 ft vertically. It was shown that simply incorporating arrival meter fix crossing-time constraints into the advisory generation could eliminate over half of the all predicted separation violations and more than 80% of the predicted violations between two arrival flights. Predicted separation violations between arrivals and non-arrivals were 32% of all predicted separation violations at Denver and 41% at Dallas/Fort-Worth. A probabilistic analysis of meter fix crossing-time errors is included which shows that some controller interventions will still be required even when the predicted crossing-times of the advisories are set to add a 1 or 2 nmi buffer above the minimum in-trail separation of 5 nmi. The 2 nmi buffer was shown to increase average flight delays by up to 30 sec when compared to the 1 nmi buffer, but it only resulted in a maximum decrease in average arrival throughput of one flight per hour.

Meyn, Larry A.; Erzberger, Heinz; Huynh, Phu V.

2011-01-01

290

On estimates of first solar proton arrival  

NASA Astrophysics Data System (ADS)

It is generally believed that an arrival of first solar protons to the Earth corresponds to the GLE onset registered by the NM network. Many transport models and model injection functions use the proton arrival time as a basic parameter. However its estimate definitely depends on a background level of particular detector and a time derivative of detector count rate. The Anti-Coincidence System (ACS) of Spectrometer on INTEGRAL (SPI) is sensitive to primary and secondary gamma-rays and effectively response to solar protons. The ACS SPI provides unprecedented statistics and time-resolution in comparison with NM's. Therefore the ACS SPI may response to solar protons sometimes earlier than do NM's. For example, on 2006 December 13 the ACS SPI onset to solar protons was about 10 min before the GLE onset (3 min after the main hard X-ray peak). This time difference was much less (or even negative) for giant hard X-ray flares of 2003 October 28 and 2005 January 20, when the ACS background was relatively high.

Struminsky, Alexei

291

Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by {ital Pioneer} {ital V}{ital enus} {ital Orbiter}, {ital Compton} {ital Gamma}-{ital Ray} {ital Observatory}, and {ital Ulysses}  

SciTech Connect

Between the {ital Compton} {ital Gamma} {ital Ray} {ital Observatory} ({ital CGRO}) launch in 1991 April and the {ital Pioneer} {ital V}{ital enus} {ital Orbiter} ({ital PVO}) demise in 1992 October, concurrent coverage by {ital CGRO}, {ital PVO}, and {ital Ulysses} was obtained for several hundred gamma-ray bursts (GRBs). Although most of these were below the {ital PVO} and {ital Ulysses} thresholds, 37 were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to {approximately}2{degree} accuracy by the {ital CGRO} Burst and Transient Source Experiment (BATSE), and three were also localized by COMPTEL. We computed arrival-time error boxes, whose larger dimensions range from about 2{prime} to several degrees and whose smaller dimensions are in the arcminute range. Twelve have areas less than 10 arcmin{sup 2}, and only four have areas greater than 1 deg{sup 2}. The area of the smallest box is 0.44 arcmin{sup 2}. We find that the overall BATSE localization accuracy for these events is consistent with the most recent stated uncertainties. This work indicates that the {ital ROSAT} soft X-ray source found within a preliminary IPN error box for GB920501 (Trig 1576) (Hurley et al.) is less likely to be the GRB counterpart than previously reported. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

Laros, J.G. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)] [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Hurley, K.C. [Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720-7450 (United States)] [Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720-7450 (United States); Fenimore, E.E.; Klebesadel, R.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Briggs, M.S. [University of Alabama in Huntsville, Huntsville, AL 35899 (United States)] [University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Kouveliotou, C.; McCollough, M.L. [USRA, at NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)] [USRA, at NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Fishman, G.J.; Meegan, C.A. [NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)] [NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Cline, T.L. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)] [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Boer, M.; Niel, M. [CESR, F-31029 Toulouse Cedex (France)] [CESR, F-31029 Toulouse Cedex (France)

1998-10-01

292

P-Wave ?N-?N Coupling and the Spin-Orbit Splitting of ? 9 {Be}  

NASA Astrophysics Data System (ADS)

We reexamine the spin-orbit splitting of ? 9 {Be} excited states in terms of the SU6 quark-model baryon-baryon interaction. The previous folding procedure to generate the ?? spin-orbit potential from the quark-model ?N LS resonating-group kernel predicted three to five times larger values for ?E?s = Ex(3/2+) - Ex(5/2+) in the model FSS and fss2. This time, we calculate ?? LS Born kernel, starting from the LS components of the nuclear-matter G-matrix for the ? hyperon. This framework makes it possible to take full account of an important P-wave ?N-?N coupling through the antisymmetric LS(-) force involved in the Fermi-Breit interaction. We find that the experimental value, ? E{l s}exp = 43 ± 5 {keV}, is reproduced by the quark-model G-matrix LS interaction with a Fermi-momentum around kF = 1.0 fm-1, when the model FSS is used in the energy-independent renormalized RGM formalism. On the other hand, the model fss2 gives too large splitting of almost 200 keV, owing to the uncanceled contribution of the scalar-meson exchange LS components.

Fujiwara, Y.; Kohno, M.; Suzuki, Y.

293

When Did the First Americans Arrive?  

NSDL National Science Digital Library

Who were the first Americans, when did they arrive, and from where did they come? With limited evidence, scientists have long proposed a hypothesis that linked the migration route and the timing of the migration of these ancient people to the end of the last ice age. This video segment, adapted from a NOVA television broadcast, describes how archaeologists have uncovered new evidence suggesting that the first Americans may have been able to migrate down the coast of North America, rather than waiting for an ice-free corridor to develop, implying that migration could have occurred earlier than previously thought. The segment is five minutes forty seconds in length.

2010-09-15

294

When Did the First Americans Arrive?  

NSDL National Science Digital Library

Who were the first Americans, when did they arrive, and from where did they come? With limited evidence, scientists have long proposed a hypothesis that linked the migration route and the timing of the migration of these ancient people to the end of the last ice age. This video segment, adapted from a NOVA television broadcast, describes how archaeologists have uncovered new evidence suggesting that the first Americans may have been able to migrate down the coast of North America, rather than waiting for an ice-free corridor to develop, implying that migration could have occurred earlier than previously thought. The segment is five minutes forty seconds in length.

295

Body waves separation in the time-frequency domain  

NASA Astrophysics Data System (ADS)

Arrival times of body waves generated by small magnitude microseismic events are usually very close and their limited bandwidth can cause even partial overlap in the time and frequency domains. The separation of P and S waves is then a challenging task that if solved could bring more insights about nature and location of the generating source. Differences in arrival times and frequency content of P and S waves can be seen by using time-frequency decomposition. The traditional time-frequency representation based on the Fourier Transform is limited by its trade-off between time and frequency resolutions, while other alternatives like the Wavelet Transform are still limited by the Heisenberg box. A new derivation of the Continuous Wavelet Transform, called Synchrosqueezing, stretches these boundaries using a mixture of the reassignment method with instantaneous frequency, giving a better frequency representation with improved time localization. Furthermore, all the individual components of the signal are separated in the time domain. This means that we are able to isolate the waveforms of a complex microseismic trace. Each spectral component can then be matched with a body wave plus its associated coda. Proper parameters have to be selected prior to the computation, such as the central frequency and bandwidth of the mother wavelet. We thus include a signal characterization first to find the best matching mother wavelet. In this paper we use the Synchrosqueezing transform to perform the time frequency representation of short brittle events recorded during microseismic experiments. Decomposition results for these examples show that the Synchrosqueezing transform outperforms the Short-Time Fourier Transform. The different components of each body waves (first arrival, coda, frequency components) can then be identified in the time-frequency plane. For some microseismic events, a first P-wave arrival is followed by another arrival at lower frequency that could be a P-wave converted to S-wave (P-S). This arrival is followed by a spectral component at the same frequency potentially corresponding to its coda. The main S-wave comprises a few spectral components of lower frequency. Each signal components can then be extracted by the inverse Synchrosqueezing transform, to be analyzed separately. The same approach could be extrapolated to the time-frequency representation of other seismic signals such as resonance frequencies and long-period events. Microseismic event from a hydraulic fracturing treatment. Zoom in the T-F representations of the STFT (left) and SST (right) of the microseismic event.

Herrera, R. H.; Tary, J.; Van der Baan, M.

2013-12-01

296

Scattering amplitude of ultracold atoms near the p-wave magnetic Feshbach resonance  

SciTech Connect

Most of the current theories on the p-wave superfluid in cold atomic gases are based on the effective-range theory for the two-body scattering, where the low-energy p-wave scattering amplitude f{sub 1}(k) is given by f{sub 1}(k)=-1/[ik+1/(Vk{sup 2})+1/R]. Here k is the incident momentum, V and R are the k-independent scattering volume and effective range, respectively. However, due to the long-range nature of the van der Waals interaction between two colliding ultracold atoms, the p-wave scattering amplitude of the two atoms is not described by the effective-range theory [J. Math. Phys. 4, 54 (1963); Phys. Rev. A 58, 4222 (1998)]. In this paper we provide an explicit calculation for the p-wave scattering of two ultracold atoms near the p-wave magnetic Feshbach resonance. We show that in this case the low-energy p-wave scattering amplitude f{sub 1}(k)=-1/[ik+1/(V{sup eff}k{sup 2})+1/(S{sup eff}k)+1/R{sup eff}] where V{sup eff}, S{sup eff}, and R{sup eff} are k-dependent parameters. Based on this result, we identify sufficient conditions for the effective-range theory to be a good approximation of the exact scattering amplitude. Using these conditions we show that the effective-range theory is a good approximation for the p-wave scattering in the ultracold gases of {sup 6}Li and {sup 40}K when the scattering volume is enhanced by the resonance.

Zhang Peng [Exploratory Research for Advanced Technology, Macroscopic Quantum Project, Japan Science and Technology, Tokyo 113-8656 (Japan); Department of Physics, Renmin University of China, Beijing 100872 (China); Naidon, Pascal [Exploratory Research for Advanced Technology, Macroscopic Quantum Project, Japan Science and Technology, Tokyo 113-8656 (Japan); Ueda, Masahito [Exploratory Research for Advanced Technology, Macroscopic Quantum Project, Japan Science and Technology, Tokyo 113-8656 (Japan); Department of Physics, University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033 (Japan)

2010-12-15

297

Fluorescence assay for polymerase arrival rates  

E-print Network

To engineer complex synthetic biological systems will require modular design, assembly, and characterization strategies. The RNA polymerase arrival rate (PAR) is defined to be the rate that RNA polymerases arrive at a ...

Che, Austin, 1979-

2004-01-01

298

Fluorescence Assay for Polymerase Arrival Rates  

E-print Network

To engineer complex synthetic biological systems will require modular design, assembly, and characterization strategies. The RNA polymerase arrival rate (PAR) is defined to be the rate that RNA polymerases arrive at a ...

Che, Austin

2003-08-31

299

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

300

Saskatoon | Saskatchewan | Canada Pre-Arrival  

E-print Network

Saskatoon | Saskatchewan | Canada Pre-Arrival Guidefor International Students Studious Ingenious to the University of Saskatchewan (U of S). We are very pleased that you have chosen our university as your place Outstanding Documentation | 21 University of Saskatchewan Pre-Arrival Guide 1 #12;BeforeYouArrive Apply

Peak, Derek

301

Multistatic Pulse-Wave Angle-of-arrival-assisted relative interferometric RADAR  

Microsoft Academic Search

In this work we propose a Pulse-Wave (PW) extension to the Angle-of-arrival-assisted Radio Interferometry (ARI) technique to dramatically reduce the scan-time and the number of vantage points necessary to obtain high-fidelity target position estimation. Accordingly, we call this enhanced process PW-ARI. PW-ARI is the fusion of data from three domains: time (time-of-flight), phase (relative phase-of-arrival), and angle (direction-of-arrival). It has

Jonathan Friedman; Thomas Schmid; Zainul Charbiwala; Mani B. Srivastava; Y. H. Cho

2009-01-01

302

Anisotropic P-wave velocity analysis and seismic imaging in onshore Kutch sedimentary basin of India  

NASA Astrophysics Data System (ADS)

The long-offset P-wave seismic reflection data has observable non-hyperbolic moveout, which depend on two parameters such as normal moveout velocity ( Vnmo) and the anisotropy parameter( ?). Anisotropy (e.g., directional dependence of velocity at a fixed spatial location in a medium) plays an important role in seismic imaging. It is difficult to know the presence of anisotropy in the subsurface geological formations only from P-wave seismic data and special analysis is required for this. The presence of anisotropy causes two major distortions of moveout in P-wave seismic reflection data. First, in contrast to isotropic media, normal-moveout (NMO) velocity differs from the vertical velocity; and the second is substantial increase of deviations in hyperbolic moveout in an anisotropic layer. Hence, with the help of conventional velocity analysis based on short-spread moveout (stacking) velocities do not provide enough information to determine the true vertical velocity in a transversely isotropic media with vertical symmetry axis (VTI media). Therefore, it is essential to estimate the single anisotropic parameter ( ?) from the long-offset P-wave seismic data. It has been demonstrated here as a case study with long-offset P-wave seismic data acquired in onshore Kutch sedimentary basin of western India that suitable velocity analysis using Vnmo and ? can improve the stacking image obtained from conventional velocity analysis.

Behera, Laxmidhar; Khare, Prakash; Sarkar, Dipankar

2011-08-01

303

What Do s- and p-Wave Neutron Average Radiative Widths Reveal  

SciTech Connect

A first observation of two resonance-like structures at mass numbers 92 and 112 in the average capture widths of the p-wave neutron resonances relative to the s-wave component is interpreted in terms of a spin-orbit splitting of the 3p single-particle state into P{sub 3/2} and P{sub 1/2} components at the neutron separation energy. A third structure at about A = 124, which is not correlated with the 3p-wave neutron strength function, is possibly due to the Pygmy Dipole Resonance. Five significant results emerge from this investigation: (i) The strength of the spin-orbit potential of the optical-model is determined as 5.7 {+-} 0.5 MeV, (ii) Non-statistical effects dominate the p-wave neutron-capture in the mass region A = 85 - 130, (iii) The background magnitude of the p-wave average capture-width relative to that of the s-wave is determined as 0.50 {+-} 0.05, which is accounted for quantitatively in tenns of the generalized Fermi liquid model of Mughabghab and Dunford, (iv) The p-wave resonances arc partially decoupled from the giant-dipole resonance (GDR), and (v) Gamma-ray transitions, enhanced over the predictions of the GDR, are observed in the {sup 90}Zr - {sup 98}Mo and Sn-Ba regions.

Mughabghab, S.F.

2010-04-30

304

P-wave-enhanced spin field effect transistor and recent patents.  

PubMed

P-wave-enhanced spin field-effect transistor made of AlGaN/GaN heterostructure was designed for the spintronic devices operated at high power and high temperature. The operation theory is based on the spin-polarized field-effect transistor designed by Datta and Das [Appl. Phys. Lett. 56, 665 (1990)]. The mechanism of the p-wave enhancement in AlGaN/GaN heterostructure was investigated. The recent development and related patents in the spin-polarized field-effect transistor were reviewed. In particular, we will focus on the recent patents which could enhance p-wave probability and control of spin precession of 2DEG in the AlGaN/GaN transistor structure. PMID:19076030

Gau, Ming-Hong; Lo, Ikai; Wang, Wan-Tsang; Chiang, Jih-Chen; Chou, Mitch Ming-Chi

2007-01-01

305

Vanishing edge currents in non-p -wave topological chiral superconductors  

NASA Astrophysics Data System (ADS)

The edge currents of two-dimensional topological chiral superconductors with nonzero Cooper pair angular momentum—e.g., chiral p -, d -, and f -wave superconductivity—are studied. Bogoliubov-de Gennes and Ginzburg-Landau calculations are used to show that in the continuum limit, only chiral p -wave states have a nonzero edge current. Outside this limit, when lattice effects become important, edge currents in non-p -wave superconductors are comparatively smaller, but can be nonzero. Using Ginzburg-Landau theory, a simple criterion is derived for when edge currents vanish for non-p -wave chiral superconductivity on a lattice. The implications of our results for putative chiral superconductors such as Sr2RuO4 and UPt3 are discussed.

Huang, Wen; Taylor, Edward; Kallin, Catherine

2014-12-01

306

First-order P-wave ray synthetic seismograms in inhomogeneous, weakly anisotropic, layered media  

NASA Astrophysics Data System (ADS)

The calculation of first-order P-wave ray synthetic seismograms based on first-order ray tracing (FORT) and dynamic ray tracing (FODRT) for P-waves propagating in inhomogeneous, weakly anisotropic media is extended from smooth to layered media. All the basic formulae necessary to calculate the P-wave FORT and FODRT quantities inside layers and to transform them at the points of reflection/transmission are given. The proposed formulae are applicable in subcritical as well as overcritical regions. The accuracy of the results is tested by comparing the approximate (FORT) results with the results obtained from a standard ray tracer for anisotropic media. The tests indicate that, except for critical regions, where the ray theory provides incorrect results anyway, the accuracy of FORT and FODRT in layered media is comparable with the accuracy in smooth media.

Pšen?ík, Ivan; Farra, Véronique

2014-07-01

307

Possible realization of a chiral p-wave paired state in a two-component system  

NASA Astrophysics Data System (ADS)

There is much interest in the realization of systems with p-wave pairing in one dimension or chiral p-wave pairing in two dimensions, because these are believed to support Majorana modes at the ends or inside vortices. We consider a two-component system of composite fermions and provide theoretical evidence that, under appropriate conditions, the screened interaction between the minority composite fermions is such as to produce an almost exact realization of a p-wave paired state described by the so-called anti-Pfaffian wave function. This state is predicted to occur at filling ? =3/8 or 13/8 in GaAs when the Zeeman energy is sufficiently small, and at ? =±3/8 or ±13/8 in single layer graphene when either the Zeeman or the valley splitting is sufficiently small.

Mukherjee, Sutirtha; Jain, J. K.; Mandal, Sudhansu S.

2014-09-01

308

Arrhythmia resulting from sensing malfunction in a P wave triggered pacemaker.  

PubMed

P wave triggered pacemakers can produce complicated arrhythmias during normal function. A ventricular, R wave inhibited pacemaker and an atrial sensing pacemaker were both present and functioning normally in the patient reported here. A premature paced beat was observed every 12th beat which resulted from discharge of the atrial sensing pacemaker. This arrhythmia appeared because a "P" wave occurred during the noise sampling period of the atrial sensing pacemaker, disabling the demand function and resulting in generator discharge on or near the T wave of a preceding unsensed beat while the pacemaker was in the asynchronous mode. PMID:7430871

Curtis, G P; Lief, L H

1980-10-01

309

New predictions for inclusive heavy-quarkonium P-wave decays.  

PubMed

We show that some nonrelativistic quantum chromodynamics color-octet matrix elements can be written in terms of (derivatives of) wave functions at the origin and of nonperturbative universal constants once the factorization between the soft and ultrasoft scales is achieved by using an effective field theory where only ultrasoft degrees of freedom are kept as dynamical entities. This allows us to derive a new set of relations between inclusive heavy-quarkonium P-wave decays into light hadrons with different principal quantum numbers and with different heavy flavors. In particular, we can estimate the ratios of the decay widths of bottomonium P-wave states from charmonium data. PMID:11800937

Brambilla, Nora; Eiras, Dolors; Pineda, Antonio; Soto, Joan; Vairo, Antonio

2002-01-01

310

At the beginning of April 1911 Albert Einstein arrived in Prague to become full professor of theoretical physics at the German part of Charles University. It was there, for the first time, that  

E-print Network

At the beginning of April 1911 Albert Einstein arrived in Prague to become full professor anticipated what a future theory of gravity should look like. At the occasion of the Einstein and sightseeing (e.g., places associated with Einstein, Mach, Doppler, Kepler, and Brahe). We are considering

Cerveny, Vlastislav

311

Subduction in the southern Caribbean: Images from finite-frequency P wave tomography  

NASA Astrophysics Data System (ADS)

The eastern boundary of the Caribbean plate is marked by subduction of the Atlantic under the Lesser Antilles. The southeastern plate boundary is characterized by a strike-slip margin, while different configurations of subduction of the southwest Caribbean under South America have been proposed. We investigate the slab geometry in the upper mantle using multiple-frequency, teleseismic P wave tomography. Waveforms from P and PKPdf phases from 285 (Mb > 5.0) events occurring at epicentral distances from 30° to 90° and greater than 150° were bandpass filtered and cross-correlated to obtain up to three sets of delay times for each event. The delay times were inverted using approximate first Fresnel zone sensitivity kernels. Our results show the subducting Atlantic slab, as well as a second slab in the west of the study area that we interpret as a subducting fragment of the Caribbean plate. Both slabs have steep dips where imaged and can be traced to depths greater than 600 km. These results are consistent with transition zone boundary topography as determined by receiver function analysis. The Atlantic slab extends continent-ward south of the plate bounding strike-slip margin. We interpret this extension as continental margin lithospheric mantle that is detaching from beneath South America and subducting along with the oceanic Atlantic slab. The steep subduction of the Caribbean occurs ˜500 km landward from the trench, implying an initial stage of shallow subduction as far to the east as the Lake Maracaibo-Mérida Andes region, as has been inferred from intermediate depth seismicity.

Bezada, M. J.; Levander, A.; Schmandt, B.

2010-12-01

312

ccsd00003592, Resonant scattering properties close to a p-wave Feshbach resonance  

E-print Network

ccsd­00003592, version 2 ­ 29 Mar 2005 Resonant scattering properties close to a p-wave Feshbach resonance F. Chevy 1 , E. G.M. van Kempen 2 , T.Bourdel 1 , J. Zhang 3 , L. Khaykovich 4 , M.Teichmann 1 , L-wave Feshbach resonance. Our model is based on a simple three channel system that reproduces more elaborate

313

Investigation of semileptonic B meson decays to p-wave charm mesons  

E-print Network

We have studied semileptonic B meson decays with a p-wave charm meson in the final state using 3.29 x 10(6) B (B) over bar events collected with the CLEO II detector at the Cornell Electron-Positron Storage Ring. We find a value for the exclusive...

Ammar, Raymond G.; Baringer, Philip S.; Bean, Alice; Besson, David Zeke; Coppage, Don; Darling, C.; Davis, Robin E. P.; Hancock, N.; Kotov, S.; Kravchenko, I.; Kwak, Nowhan

1998-05-01

314

Confinement-induced p-wave resonances from s-wave interactions  

SciTech Connect

We show that a purely s-wave interaction in three dimensions (3D) can induce higher partial-wave resonances in mixed dimensions. We develop two-body scattering theories in all three cases of 0D-3D, 1D-3D, and 2D-3D mixtures and determine the positions of higher partial-wave resonances in terms of the 3D s-wave scattering length assuming a harmonic confinement potential. We also compute the low-energy scattering parameters in the p-wave channel (scattering volume and effective momentum) that are necessary for the low-energy effective theory of the p-wave resonance. We point out that some of the resonances observed in the Florence group experiment [Phys. Rev. Lett. 104, 153202 (2010)] can be interpreted as the p-wave resonances in the 2D-3D mixed dimensions. Our study paves the way for a variety of physics, such as Anderson localization of matter waves under p-wave resonant scatterers.

Nishida, Yusuke [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Tan, Shina [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States); School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2010-12-15

315

Pelagic and coastal sources of P wave microseisms: Generation under tropical cyclones  

E-print Network

Pelagic and coastal sources of P wave microseisms: Generation under tropical cyclones Jian Zhang,1 wave wave interactions due to tropical cyclones and to image Earth structure using ambient seismic wave microseisms: Generation under tropical cyclones, Geophys. Res. Lett., 37, L15301, doi:10

Gerstoft, Peter

316

Upper mantle Q and thermal structure beneath Tanzania, East Africa from teleseismic P wave spectra  

E-print Network

Upper mantle Q and thermal structure beneath Tanzania, East Africa from teleseismic P wave spectra. Introduction [2] East Africa is a geologically unique region with Cenozoic volcanism and a developing., A. A. Nyblade, and J. Ritsema (2004), Upper mantle Q and thermal structure beneath Tanzania, East

Ritsema, Jeroen

317

Analysis of the Mantle Transition Zone beneath West Antarctica using P-wave receiver functions  

NASA Astrophysics Data System (ADS)

Several exposed, sub-glacial, and submarine volcanoes exist throughout West Antarctica in the vicinity of the West Antarctic Rift System; prior work has suggested that a mantle plume beneath the region influences the observed rifting and volcanism. However the existence of a mantle plume has not been verified, because models from recent seismic tomography results are not well resolved at mantle transition zone depths. We use P-wave receiver functions (PRFs) from all Antarctic seismic stations installed at sites above less than 1 km of ice, including recent 2007-2012 Antarctic POLENET, permanent GSN, and the 2000-2003 TAMSEIS seismographs to explore the depth to and the thickness of the mantle transition zone beneath West Antarctica. We calculate PRFs for all earthquakes occurring at 30-90° with Mb>5.5 using a time-domain iterative deconvolution method filtered using a Gaussian-width factor of 0.5, corresponding to frequencies less than ~0.24 Hz. Using this method, we check stability of the deconvolution by convolving the vertical component with the final radial receiver function, rejecting all receiver functions that did not recover at least 80% of the original trace. Maps showing Ps pierce-points cover most of West Antarctica and the Transantarctic Mountains, with particularly good coverage beneath Marie Byrd Land and the region around Ross Island. Preliminary results for P receiver functions stacked by station and migrated to depth using the ak135 1-d velocity model indicate a depressed 410' discontinuity beneath West Antarctica; beneath the Transantarctic and East Antarctic sites, the 410' is not depressed. However, no clear depth patterns are observed for the 660' discontinuity throughout West Antarctica; at several West Antarctic sites, the 660' may even be depressed slightly. Additional work using common conversion point (CCP) stacking will enable us to more clearly map the depth of the 410' and 660' and to identify spatial variations in mantle transition zone thickness.

Emry, E.; Nyblade, A.; Julia, J.; Anandakrishnan, S.; Aster, R. C.; Wiens, D. A.; Huerta, A. D.; Wilson, T. J.

2013-12-01

318

Design Considerations for a New Terminal Area Arrival Scheduler  

NASA Technical Reports Server (NTRS)

Design of a terminal area arrival scheduler depends on the interrelationship between throughput, delay and controller intervention. The main contribution of this paper is an analysis of the above interdependence for several stochastic behaviors of expected system performance distributions in the aircraft s time of arrival at the meter fix and runway. Results of this analysis serve to guide the scheduler design choices for key control variables. Two types of variables are analyzed, separation buffers and terminal delay margins. The choice for these decision variables was tested using sensitivity analysis. Analysis suggests that it is best to set the separation buffer at the meter fix to its minimum and adjust the runway buffer to attain the desired system performance. Delay margin was found to have the least effect. These results help characterize the variables most influential in the scheduling operations of terminal area arrivals.

Thipphavong, Jane; Mulfinger, Daniel

2010-01-01

319

Admission control with batch arrivals E. Lerzan Ormeci  

E-print Network

policies that maximize the total expected discounted reward with a continuous discount rate over, where each admitted class-i job demands an exponential service with rate µ, and brings a reward ri. We to the system, it brings a reward of ri > 0 upon its arrival, and requires an exponential service time with rate

Ã?rmeci, E. Lerzan

320

The rupture process and asperity distribution of three great earthquakes from long-period diffracted P-waves  

NASA Technical Reports Server (NTRS)

The variation of maximum earthquake size along the subduction zones has been interpreted as a variation in the seismic coupling ostensibly related to the mechanical conditions of the fault zone. Great differences are noted between the seismographs of the three great earthquakes whose rupture processes are presently considered: in the Kurile Islands (1963), The Rat Islands (1965) and Alaska (1964). On-scale long period P waves were recorded in all cases. Source time functions are deconvolved from the observed periods. It is concluded that maximum earthquake size is related to the asperity distribution on the fault. The subduction zones with the largest earthquakes have very large asperities, as in the Alaskan case, while the zones with the smaller great earthquakes, such as the Kurile Islands, have smaller scattered asperities.

Ruff, L.; Kanamori, H.

1983-01-01

321

Checklist 1 Before your arrival in Germany  

E-print Network

particularly at the beginning of your stay: official fees at local authorities, university fees, deposit.)? o Do I have all the documents required? o Do I have accommodation when arriving in Germany? If not, search for accommodation early in advance before arriving in Germany Documents you need to enrol

Kemper, Gregor

322

Evaluation of QT and P Wave Dispersion and Mean Platelet Volume among Inflammatory Bowel Disease Patients  

PubMed Central

Background: In inflammatory bowel disease (IBD) number of thromboembolic events are increased due to hypercoagulupathy and platelet activation. Increases in mean platelet volume (MPV) can lead to platelet activation, this leads to thromboembolic events and can cause acute coronary syndromes. In IBD patients, QT-dispersion and P-wave dispersion are predictors of ventricular arrhythmias and atrial fibrilation; MPV is accepted as a risk factor for acute coronary syndromes, we aimed at evaluating the correlations of these with the duration of disease, its localization and activity. Methods: The study group consisted of 69 IBD (Ulcerative colitis n: 54, Crohn's Disease n:15) patients and the control group included 38 healthy individuals. Disease activity was evaluated both endoscopically and clinically. Patients with existing cardiac conditions, those using QT prolonging medications and having systemic diseases, anemia and electrolyte imbalances were excluded from the study. QT-dispersion, P-wave dispersion and MPV values of both groups were compared with disease activity, its localization, duration of disease and the antibiotics used. Results: The P-wave dispersion values of the study group were significantly higher than those of the control group. Duration of the disease was not associated with QT-dispersion, and MPV levels. QT-dispersion, P-wave dispersion, MPV and platelet count levels were similar between the active and in mild ulcerative colitis patients. QT-dispersion levels were similar between IBD patients and the control group. No difference was observed between P-wave dispersion, QT-dispersion and MPV values; with regards to disease duration, disease activity, and localization in the study group (p>0.05). Conclusions: P-wave dispersion which is accepted as a risk factor for the development of atrial fibirilation was found to be high in our IBD patients. This demonstrates us that the risk of developing atrial fibrillation may be high in patients with IBD. No significant difference was found in the QT-dispersion, and in the MPV values when compared to the control group. PMID:21960745

DOGAN, Yuksel; SOYLU, Aliye; EREN, Gulay A.; POTUROGLU, Sule; DOLAPCIOGLU, Can; SONMEZ, Kenan; DUMAN, Habibe; SEVINDIR, Isa

2011-01-01

323

Zero field Hall effect in chiral p-wave superconductors near the Kosterlitz-Thouless transition  

NASA Astrophysics Data System (ADS)

A theory of vortex dynamics developed by Ambegaokar, Halperin, Nelson, and Siggia is employed to study two-dimensional chiral p-wave superconducting systems. Due to unequal values of drag coefficients of opposite vorticity specific to chiral p-wave cases, we find that a ``convective'' term, in addition to diffusivity, should enter the dynamical equations governing vortex pair unbinding process. As a consequence, we find a matrix form dielectric function and a new contribution to Hall conductance ?xy automatically follows even in zero magnetic field. We predict both the Hall conductance and power dissipation show a peak across the Kosterlitz-Thouless transition temperature. Their frequency dependence is also discussed. It is found that a set of frequency-dependent length scales, which controls the truncation of renormalization process, depends on both the convective and diffusive motion of vortices.

Kit Chung, Chun; Kato, Yusuke

2013-03-01

324

P-wave resonant state of the He4? hypernucleus in the 4He (K- ,?-) reaction  

NASA Astrophysics Data System (ADS)

We theoretically investigate a possible existence of a p-wave He4? resonant state with J? =1-, T ? 1 / 2 above the ? threshold, using a coupled (3 N- ?) + (3 N- ?) model with a spreading potential. We calculate inclusive and ?-? conversion ?- spectra in a 4He (K- ,?-) reaction at 1.5 GeV/c, ?lab = 4- 12 ° by the Green's function method in a distorted-wave impulse approximation. The pole position for the p-wave ? resonant state in He4? is determined on the Riemann sheets in the complex E plane. The result shows that a peak of the He4? resonant state is clearly obtained in the conversion spectra above the ? threshold, and that the angular distributions of these spectra enable extraction of the contribution of the resonant state from the ?- spectra. Effects of the ?-nucleus potential and the interference between ? and ? on the spectra are also discussed.

Harada, Toru; Hirabayashi, Yoshiharu

2015-01-01

325

Quasi-particle excitations around a pair of half-quantum vortices in p- wave superconductors  

NASA Astrophysics Data System (ADS)

Triplet superconductors such as Sr 2RuO 4 and Na xCoO 2? yH 2O are now found to be p-wave ( p x ± ip y) or f-wave (( p x ± ip y) cos cp z) superconductors. It was phenomenologically suggested that in these p-wave or f-wave superconductors, a pair of half-quantum vortices (HQVs) becomes stable. Using the Bogoliubov-de Gennes equation, previously we have analyzed quasi-particle excitations around an HQV at one end of a d-soliton for simplicity. In next study, we will investigate the stability of the pair of HQV’s, which are connected by the d-soliton. For this purpose, we have developed a new numerical method to solve the Bogoliubov-de Gennes equation for two vortices state, using Mathieu functions.

Niwa, Y.; Kato, M.; Maki, K.

2010-11-01

326

Observation of a p-wave one-neutron halo configuration in (37)Mg.  

PubMed

Cross sections of 1n-removal reactions from the neutron-rich nucleus (37)Mg on C and Pb targets and the parallel momentum distributions of the (37)Mg residues from the C target have been measured at 240??MeV/nucleon. A combined analysis of these distinct nuclear- and Coulomb-dominated reaction data shows that the (37)Mg ground state has a small 1n separation energy of 0.22(-0.09)(+0.12)??MeV and an appreciable p-wave neutron single-particle strength. These results confirm that (37)Mg lies near the edge of the "island of inversion" and has a sizable p-wave neutron halo component, the heaviest such system identified to date. PMID:24996084

Kobayashi, N; Nakamura, T; Kondo, Y; Tostevin, J A; Utsuno, Y; Aoi, N; Baba, H; Barthelemy, R; Famiano, M A; Fukuda, N; Inabe, N; Ishihara, M; Kanungo, R; Kim, S; Kubo, T; Lee, G S; Lee, H S; Matsushita, M; Motobayashi, T; Ohnishi, T; Orr, N A; Otsu, H; Otsuka, T; Sako, T; Sakurai, H; Satou, Y; Sumikama, T; Takeda, H; Takeuchi, S; Tanaka, R; Togano, Y; Yoneda, K

2014-06-20

327

Permeability and P-wave velocity change in granitic rocks under freeze–thaw cycles  

Microsoft Academic Search

An extensive experimental investigation of microstructural changes in granites under freeze–thaw cycles using permeability and P-wave velocity measurements is described. Two types of natural granite rocks are considered and tested under dry and saturated conditions. The specimens were subjected to 200 heating–cooling cycles (??20°C\\/?+?20°C); each cycle had a duration of 24 h. The results indicate that the ageing process decreases the

M. Takarli; W. Prince

2007-01-01

328

Variation of P-wave velocity before the Bear Valley, California, earthquake of 24 February 1972  

USGS Publications Warehouse

Residuals for P-wave traveltimes at a seismograph station near Bear Valley, California, for small, precisely located local earthquakes at distances of 20 to 70 kilometers show a sharp increase of nearly 0.3 second about 2 months before a magnitude 5.0 earthquake that occurred within a few kilometers of the station. This indicates that velocity changes observed elsewhere premonitory to earthquakes, possibly related to dilatancy, occur along the central section of the San Andreas fault system.

Robinson, R.; Wesson, R.L.; Ellsworth, W.L.

1974-01-01

329

P wave bottomonium spectral functions in the QGP from lattice NRQCD  

E-print Network

We present an overview of bottomonium spectral functions in the quark-gluon plasma, obtained by the FASTSUM collaboration, using lattice QCD simulations with two light quark flavours on anisotropic lattices. The bottom quark is treated nonrelativistically. While we find that the S wave ground states survive up to the highest temperature we consider, we have strong indications that P wave states melt immediately above Tc.

Gert Aarts; Chris Allton; Seyong Kim; Maria-Paola Lombardo; Sinead M. Ryan; Jon-Ivar Skullerud

2013-11-05

330

Geometrical optics for quasi-P waves: Theories and numerical methods  

NASA Astrophysics Data System (ADS)

The quasi-P wave in anisotropic solids is of practical importance in obtaining maximal imaging resolution in seismic exploration. The geometrical optics term in the asymptotic expansion for the wave characterizes the high frequency part of the quasi-P wave by using two functions: a phase (traveltime) function satisfying an eikonal equation and an amplitude function satisfying a transport equation. I develop theories and numerical methods for constructing the geometrical optics term of quasi-P waves in general anisotropic solids. The traveltime corresponding to the downgoing wave satisfies a paraxial eikonal equation, an evolution equation in depth. This paraxial eikonal equation takes into account the convexity of the quasi-P slowness surface and thus has a built-in reliable indicator of the ray velocity direction. Therefore, high- order finite-difference eikonal solvers are easily constructed by utilizing Weighted Essentially NonOscillating (WENO) schemes. Because the amplitude function is related to second-order derivatives of the traveltime, a third-order accurate eikonal solver for traveltimes is necessary to get a firstorder accurate amplitude. However, the eikonal equation with a point source has an upwind singularity at the source which renders all finite-difference eikonal solvers to be first-order accurate near the source. A new approach combining an adaptive-gridding strategy with WENO schemes can treat this singularity efficiently and can yield highly accurate traveltimes and amplitudes for both isotropic and anisotropic solids. A variety of numerical experiments verify that the new paraxial eikonal solver and adaptive-gridding-WENO approach are accurate and efficient for capturing the anisotropy. Therefore, the two new methods provide tools for constructing the geometrical optics term of the quasi-P wave in general anisotropic solids.

Qian, Jianliang

2000-10-01

331

The charm quark EDM and singlet P-wave charmonium production in supersymmetry  

E-print Network

We analyze the singlet $P$--wave charmonium production at $e^+ e^-$ colliders within the framework of unconstrained supersymmetry. We show that the CP--violating transitions, dominated by the gluino exchange, are typically four orders of magnitude larger than the CP--conserving ones, and former is generated by the electric dipole moment of the charm quark. Our results can be directly tested via the charmonium searches at the CLEO--c experiment.

Z. Z. Aydin; U. Erkarslan

2002-04-19

332

P-wave morphology correlation with left atrial volumes assessed by 2-dimensional echocardiography  

Microsoft Academic Search

To correlate prespecified P-wave morphologies with echocardiographically derived left atrial volumes (LAVs), we studied a convenience sample of 71 patients with predominantly normal left ventricular systolic function (mean ejection fraction = 58.2% ± 6.6%) who underwent concurrent 2-dimensional echocardiogram and 12-lead electrocardiogram. Left atrial volume was calculated from apical end-systolic images by the biplane method of disks and was indexed

James P. Birkbeck; David B. Wilson; Matthew A. Hall; David G. Meyers

2006-01-01

333

Three-dimensional P wave velocity model for the San Francisco Bay region, California  

Microsoft Academic Search

A new three-dimensional P wave velocity model for the greater San Francisco Bay region has been derived using the double-difference seismic tomography method, using data from about 5,500 chemical explosions or air gun blasts and approximately 6,000 earthquakes. The model region covers 140 km NE-SW by 240 km NW-SE, extending from 20 km south of Monterey to Santa Rosa and

Clifford H. Thurber; Thomas M. Brocher; Haijiang Zhang; Victoria E. Langenheim

2007-01-01

334

Simulation Results for Airborne Precision Spacing along Continuous Descent Arrivals  

NASA Technical Reports Server (NTRS)

This paper describes the results of a fast-time simulation experiment and a high-fidelity simulator validation with merging streams of aircraft flying Continuous Descent Arrivals through generic airspace to a runway at Dallas-Ft Worth. Aircraft made small speed adjustments based on an airborne-based spacing algorithm, so as to arrive at the threshold exactly at the assigned time interval behind their Traffic-To-Follow. The 40 aircraft were initialized at different altitudes and speeds on one of four different routes, and then merged at different points and altitudes while flying Continuous Descent Arrivals. This merging and spacing using flight deck equipment and procedures to augment or implement Air Traffic Management directives is called Flight Deck-based Merging and Spacing, an important subset of a larger Airborne Precision Spacing functionality. This research indicates that Flight Deck-based Merging and Spacing initiated while at cruise altitude and well prior to the Terminal Radar Approach Control entry can significantly contribute to the delivery of aircraft at a specified interval to the runway threshold with a high degree of accuracy and at a reduced pilot workload. Furthermore, previously documented work has shown that using a Continuous Descent Arrival instead of a traditional step-down descent can save fuel, reduce noise, and reduce emissions. Research into Flight Deck-based Merging and Spacing is a cooperative effort between government and industry partners.

Barmore, Bryan E.; Abbott, Terence S.; Capron, William R.; Baxley, Brian T.

2008-01-01

335

P-wave velocity structure of the uppermost mantle beneath Hawaii from traveltime tomography  

USGS Publications Warehouse

We examine the P-wave velocity structure beneath the island of Hawaii using P-wave residuals from teleseismic earthquakes recorded by the Hawaiian Volcano Observatory seismic network. The station geometry and distribution of events makes it possible to image the velocity structure between ~ 40 and 100 km depth with a lateral resolution of ~ 15 km and a vertical resolution of ~ 30 km. For depths between 40 and 80 km, P-wave velocities are up to 5 per cent slower in a broad elongated region trending SE-NW that underlies the island between the two lines defined by the volcanic loci. No direct correlation between the magnitude of the lithospheric anomaly and the current level of volcanic activity is apparent, but the slow region is broadened at ~ 19.8??N and narrow beneath Kilauea. In the case of the occanic lithosphere beneath Hawaii, slow seismic velocities are likely to be related to magma transport from the top of the melting zone at the base of the lithosphere to the surface. Thermal modelling shows that the broad elongated low-velocity zone cannot be explained in terms of conductive heating by one primary conduit per volcano but that more complicated melt pathways must exist.

Tilmann, F.J.; Benz, H.M.; Priestley, K.F.; Okubo, P.G.

2001-01-01

336

Queueing-blocking system with two arrival streams and guard channels  

Microsoft Academic Search

An approach to the study of a multichannel cutoff priority system for two Poisson arrival streams with distinct arrival rates and the same potential service time distribution is proposed. This approach makes it possible to obtain the state probabilities in simple closed-form expressions. These expressions provide a straightforward way to derive the distribution of the number of busy servers, the

ROCH GUERIN

1988-01-01

337

Harassment during arrival on land and departure to sea in southern elephant seals  

Microsoft Academic Search

During the breeding season female elephant seals spent most of their time on land inside harems. When they arrive on land before joining harems, and when they leave harems to return to sea, they are exposed to secondary males and may suffer intense harassment. Hence, arrival and departure present an ideal opportunity to test hypotheses concerning female tactics of harassment

F. Galimberti; L. Boitani; I. Marzetti

2000-01-01

338

Illuminating the near-sonic rupture velocities of the intracontinental Kokoxili Mw 7.8 and Denali fault Mw 7.9 strike-slip earthquakes with global P wave back projection imaging  

Microsoft Academic Search

The Denali and Kokoxili strike-slip earthquakes are two of the longest recent intracontinental ruptures. Previous studies report a range of rupture velocities. Here we image these earthquakes by reverse time migration of the intermediate-frequency P wave train recorded by global broadband seismometers. This technique permits a relatively direct measure of rupture velocity (speed and direction) as constrained by the radiated

Kristoffer T. Walker; Peter M. Shearer

2009-01-01

339

Finite-difference modelling to evaluate seismic P-wave and shear-wave field data  

NASA Astrophysics Data System (ADS)

High-resolution reflection seismic methods are an established non-destructive tool for engineering tasks. In the near surface, shear-wave reflection seismic measurements usually offer a higher spatial resolution in the same effective signal frequency spectrum than P-wave data, but data quality varies more strongly. To discuss the causes of these differences, we investigated a P-wave and a SH-wave seismic reflection profile measured at the same location on the island of Föhr, Germany and applied seismic reflection processing to the field data as well as finite-difference modelling of the seismic wave field. The simulations calculated were adapted to the acquisition field geometry, comprising 2 m receiver distance (1 m for SH wave) and 4 m shot distance along the 1.5 km long P-wave and 800 m long SH-wave profiles. A Ricker wavelet and the use of absorbing frames were first-order model parameters. The petrophysical parameters to populate the structural models down to 400 m depth were taken from borehole data, VSP (vertical seismic profile) measurements and cross-plot relations. The simulation of the P-wave wave-field was based on interpretation of the P-wave depth section that included a priori information from boreholes and airborne electromagnetics. Velocities for 14 layers in the model were derived from the analysis of five nearby VSPs (vP =1600-2300 m s-1). Synthetic shot data were compared with the field data and seismic sections were created. Major features like direct wave and reflections are imaged. We reproduce the mayor reflectors in the depth section of the field data, e.g. a prominent till layer and several deep reflectors. The SH-wave model was adapted accordingly but only led to minor correlation with the field data and produced a higher signal-to-noise ratio. Therefore, we suggest to consider for future simulations additional features like intrinsic damping, thin layering, or a near-surface weathering layer. These may lead to a better understanding of key parameters determining the data quality of near-surface shear-wave seismic measurements.

Burschil, T.; Beilecke, T.; Krawczyk, C. M.

2015-01-01

340

Velocity Structure of the Tibetan Lithosphere: Constraints from P-Wave Travel Times of Regional Earthquakes  

E-print Network

zone in the world (Yin and Harrison, 2000), and the continuing convergence has resulted in large scale­Tibetan Continental Lithosphere During Moun- tain Building) experiment was conducted along a north­south corridor al., 2004; and Liang et al., 2004; Liang and Song, 2006; Sun and Toksoz, 2006). Using teleseismic

Nowack, Robert L.

341

P-WAVE TIME-LAPSE SEISMIC DATA INTERPRETATION AT RULISON FIELD, PICEANCE BASIN, COLORADO  

E-print Network

in the Williams Fork, based on ultrasonic core measurements and diagnostic fracture initiation tests pressure change, so that seismic may be used as a tool to predict well performance prior to drilling. #12

342

Improvement to Airport Throughput Using Intelligent Arrival Scheduling and an Expanded Planning Horizon  

NASA Technical Reports Server (NTRS)

The first phase of this study investigated the amount of time a flight can be delayed or expedited within the Terminal Airspace using only speed changes. The Arrival Capacity Calculator analysis tool was used to predict the time adjustment envelope for standard descent arrivals and then for CDA arrivals. Results ranged from 0.77 to 5.38 minutes. STAR routes were configured for the ACES simulation, and a validation of the ACC results was conducted comparing the maximum predicted time adjustments to those seen in ACES. The final phase investigated full runway-to-runway trajectories using ACES. The radial distance used by the arrival scheduler was incrementally increased from 50 to 150 nautical miles (nmi). The increased Planning Horizon radii allowed the arrival scheduler to arrange, path stretch, and speed-adjust flights to more fully load the arrival stream. The average throughput for the high volume portion of the day increased from 30 aircraft per runway for the 50 nmi radius to 40 aircraft per runway for the 150 nmi radius for a traffic set representative of high volume 2018. The recommended radius for the arrival scheduler s Planning Horizon was found to be 130 nmi, which allowed more than 95% loading of the arrival stream.

Glaab, Patricia C.

2012-01-01

343

J-1 Scholar Pre-Arrival Guide  

E-print Network

J-1 Scholar Pre-Arrival Guide A Guide for Visiting Scholars #12;PAGE # I. KNOWING YOUR (AMIS), International Spouse Programs, Women's Resource Center, ADAPTS, Counseling Center 19 VII. MISCELLANEOUS INFORMATION Atlanta Attractions Know Your Rights Measurements Consulates in Atlanta

Li, Mo

344

Estimates of arrival directions of giant air showers  

NASA Astrophysics Data System (ADS)

The arrival directions of giant air showers generated in the atmosphere by the primary cosmic ray particles with energies above ˜5·10 19 eV may be connected with possible extragalactic sources, because the Larmor radius of such particles is too large. Besides it was suggested that the primary particles with enormous energies may be neutrons. In this case it is possible to avoid the energy loss in interactions with the microwave background radiation and arrival directions will strongly point to sources. Thus it is of primary importance to decrease possible errors in the estimates of arrival directions of giant air showers. To estimate the arrival direction of a giant air shower one has to have any model of its space-time structure. The simplest model of the shower time front is a model of the flat front when all particles are located in this front plane. It was shown that possible errors in estimates of the zenith and azimuth angles which characterize the arrival directions may be as large as 5°or even more. The ?2 method gives very large values of ?2. That means that this model is inconsistent with the data. A much more realistic model of a shower time front was suggested by Linsley. Calculations displayed that both the shower disk thickness and the average time delay depend on the energy of the primary particles. So the calculated time front of the shower for both electrons and muons may fit the data and thus provides better accuracy. The standard mathematical procedure to interpret data is the ?2 method. This method leads to reasonable estimates of the zenith and azimuth angles with uncertainties of 2÷3°. In some cases the minimax procedure may be utilized to interpret data. It was shown that the possible error in estimates of the zenith and azimuth angles may be decreased up to 0.5°. At last the fuzzy uncertain variables and the possibility theory are suggested here to be used for interpreting the data. Calculations were carried out in terms of the quark-gluon string model for primary protons and an observation level of 1020 g/cm. The Landau-Pomeranchuk-Migdal effect and interactions of neutral pions with nuclei in the atmosphere at high energies are taken into account. The Monte Carlo method was used for primary protons while cascades from numerous charged pions were considered with the help of cascade equations. Though experimental statistics is very low no evidence is found to prefer any directions. Thus the isotropic distribution of the arrival directions of giant air showers with energies above 10 19 eV seems to fit the data.

Antonov, E. E.; Buylova, I. L.; Dedenko, L. G.; Fedorova, G. F.; Fedunin, E. Yu.; Glushkov, A. V.; Kolosov, V. A.; Komissarova, T. M.; Pravdin, M. I.; Pyt'ev, Yu. P.; Roganova, T. M.; Sleptsov, I. E.

2002-08-01

345

Joint Tomographic Inversion of Body-Wave Arrivals and Gravity Data at the Sacramento-San Joaquin River Delta  

NASA Astrophysics Data System (ADS)

The Sacramento-San Joaquin River Delta (SSJRD) occurs at the confluence of the Sacramento and San Joaquin rivers in the Central Valley of California. The Central Valley is a sedimentary basin that divides the granitic Sierra Nevada range on the east from the heterogeneous Franciscan formation to the west. It is home to a series of levees that control about half of California's annual stream flow, and more than half of Californians get their drinking water from the SSJRD area. Previous studies show that ground motion from magnitude 6.0 earthquakes, which have recurrence intervals of about 100 years in the area, are capable of causing levee failure. While the highest risk for levee failure is in the western SSJRD, since it is near at least five major faults, a medium to high risk of catastrophic levee failure also exists for most of the central SSJRD. These assessments incorporate qualitative estimates of parameters such as basin amplification based on individual knowledge and experience, since geotechnical information is limited in the area. Likewise, two fault models are used in the study, which differ primarily in the assumed presence or absence of a blind thrust fault under the northwest corner of the SSJRD. To improve hazard assessment, particularly in regards to basin amplification of strong ground motion, local tomographic imaging is necessary to determine the shape of the Central Valley at depth and to help evaluate the presence of faults. We will present a new local P-wave velocity model for the SSJRD, determined from joint inversion of seismic arrival times and gravity measurements. For the purposes of this study, gravity data primarily complement body-wave data by providing information on shallow density structure and are more effective at delineating lateral density variations. Seismic waves provide better depth resolution but are limited by the spatial distribution of earthquake and receiver locations. Our datasets comprise over 213,000 (regional and local) arrival times and approximately 5000 local Bouguer-corrected gravity readings. We are developing a version of the seismic tomography code tomoDD, modified to incorporate gravity data. Published empirical relationships between density and seismic velocity will be used to connect the two data types. Current density-velocity relationships are based on rocks from different geologic settings and can not account for non-uniqueness in density and velocity for different rock types. We will strive to implement these density-velocity relationships with depth dependence in order to model them more realistically.

Teel, A.; Thurber, C. H.; Bennington, N. L.; Zhang, H.

2011-12-01

346

S and P-wave velocity structure beneath the Hawaiian hotspot from the PLUME deployments of ocean-bottom and land seismometers  

NASA Astrophysics Data System (ADS)

Seismological studies can provide key constraints on the existence and characteristics of mantle plumes. Remotely located oceanic hotspots pose challenges for mantle seismic imaging with land stations because of the limited areal extent of oceanic islands and thus are excellent targets for dedicated marine experiments. The PLUME project at Hawaii successfully deployed two networks of ~35 ocean-bottom seismometers and a concurrent set of portable land seismometers, providing unprecedented, dense seismic coverage around Hawaii across an ~1,000-km-wide aperture. Three-dimensional finite-frequency body-wave tomographic images of S- and P-wave velocity structure beneath the Hawaiian Islands show an upper-mantle low-velocity anomaly that is elongated in the direction of the island chain and surrounded by a high-velocity anomaly in the shallow upper mantle that is parabolic in map view. Low velocities continue downward to the mantle transition zone between 410 and 660 km depth and extend into the topmost lower mantle. For P-waves, comparisons of inversions with separate data sets at different frequencies suggest that contamination by water reverberations is not markedly biasing the imaging. Many aspects of the S- and P-wave images are consistent with each other and support the hypothesis that the Hawaiian hotspot is the result of an upwelling, high-temperature plume. The broad upper-mantle low-velocity region beneath the Hawaiian Islands may reflect the "diverging pancake" at the top of the upwelling zone; the surrounding region of high velocities could represent a downwelling curtain; and the low-velocity anomalies southeast of Hawaii in the transition zone and topmost lower mantle are consistent with predictions of a tilted plume conduit. However, there are some differences in upper mantle structure between P-wave and S-wave velocity. Inversions without station terms show a southwestward shift in the location of lowest P-wave velocities in the uppermost mantle relative to the pattern for shear waves, and inversions with station terms show differences between P-wave and S-wave velocity heterogeneity in the shallow upper mantle beneath and immediately east of the island of Hawaii. Upper mantle structure from both S and P waves is asymmetric, with lower velocities just southwest of Hawaii and higher velocities to the east. Independent Rayleigh-wave tomography of the lower lithosphere and asthenosphere reveals a similarly asymmetric upper mantle structure. Much work has been performed (e.g., examination of delay time patterns, examination of wave path coverage, resolution tests, squeezing tests, inversions with subsets of data, assessment of the possible contaminating effects of outside structure) to ascertain that the body wave inversions, and our interpretations, are well constrained.

Wolfe, C. J.; Laske, G.; Solomon, S. C.; Collins, J. A.; Detrick, R. S.; Orcutt, J. A.; Bercovici, D.; Hauri, E. H.

2011-12-01

347

Research Of Airborne Precision Spacing to Improve Airport Arrival Operations  

NASA Technical Reports Server (NTRS)

In September 2004, the European Organization for the Safety of Air Navigation (EUROCONTROL) and the United States Federal Aviation Administration (FAA) signed a Memorandum of Cooperation to mutually develop, modify, test, and evaluate systems, procedures, facilities, and devices to meet the need for safe and efficient air navigation and air traffic control in the future. In the United States and Europe, these efforts are defined within the architectures of the Next Generation Air Transportation System (NextGen) Program and Single European Sky Air Traffic Management Research (SESAR) Program respectively. Both programs have identified Airborne Spacing as a critical component, with Automatic Dependent Surveillance Broadcast (ADS-B) as a key enabler. Increased interest in reducing airport community noise and the escalating cost of aviation fuel has led to the use of Continuous Descent Arrival (CDA) procedures to reduce noise, emissions, and fuel usage compared to current procedures. To provide these operational enhancements, arrival flight paths into terminal areas are planned around continuous vertical descents that are closer to an optimum trajectory than those in use today. The profiles are designed to be near-idle descents from cruise altitude to the Final Approach Fix (FAF) and are typically without any level segments. By staying higher and faster than conventional arrivals, CDAs also save flight time for the aircraft operator. The drawback is that the variation of optimized trajectories for different types and weights of aircraft requires the Air Traffic Controller to provide more airspace around an aircraft on a CDA than on a conventional arrival procedure. This additional space decreases the throughput rate of the destination airport. Airborne self-spacing concepts have been developed to increase the throughput at high-demand airports by managing the inter-arrival spacing to be more precise and consistent using on-board guidance. It has been proposed that the additional space needed around an aircraft performing a CDA could be reduced or eliminated when using airborne spacing techniques.

Barmore, Bryan E.; Baxley, Brian T.; Murdoch, Jennifer L.

2011-01-01

348

Decays, contact P-wave interactions and hyperfine structure in Omega- exotic atoms  

E-print Network

Contact $P$-wave interactions connected to the Larmor interaction of a magnetic dipole and Thomas spin precession in the filed of an electric quadrupole are described and their implications for spectroscopy of exotic $\\Omega^{-}$-atoms are studied. In order to evaluate the magnitude of the contact $P$-wave interactions as compared to the conventional long-range interactions and the sensitivity of spectroscopic data to the $\\Omega^{-}$-hyperon quadrupole moment, we consider $2P$ states of $\\Omega ^{-}$ atoms formed with light stable nuclei with spins $I \\geq 1/2$ and atomic numbers $Z \\leq 10$. The energy level splitting caused by the contact interactions is 2-5 orders of magnitude smaller than the conventional long-range interactions. Strong decay widths of $p\\Omega ^{-}$ atoms due to reactions $p\\Omega^{-} \\to \\Lambda \\Xi^{0}$ and $p\\Omega^{-} \\to \\Sigma \\Xi$, induced by $t$-channel kaon exchanges, are calculated. $\\Omega ^{-}$ atoms formed with the light nuclei have strong widths 5-6 orders of magnitude higher than splitting caused by the contact interactions. The low-$L$ pattern in the energy spectra of intermediate- and high-$Z$ $\\Omega ^{-}$ atoms thus cannot be observed. The $\\Omega ^{-}$ quadrupole moment can be measured by observing $X$-rays from circular transitions between high-$L$ levels in $\\Omega^{-}$ exotic atoms. The effect of strong interactions in $^{208}$Pb$\\Omega ^{-}$ atoms is negligible starting from $L \\sim 10$. The contact $P$-wave interactions exist in ordinary atoms and $\\mu$-meson atoms.

M. I. Krivoruchenko; Amand Faessler

2008-04-05

349

P-wave pentaquark and its decay in the quark model with instanton induced interaction  

SciTech Connect

P-wave pentaquarks with strangeness +1, I=0, and J{sup P}=1/2{sup +} are studied in the nonrelativistic quark model with instanton induced interaction (III). We present their mass splittings and orbital-spin-isospin-color structures. It is found that decompositions of the wave functions are sensitive to III, while the mass splittings are insensitive. The decay of the lowest energy pentaquark, {theta}{sup +}, is found to be suppressed when the contribution of III is increased. Spin structure of the dominant components of the wave function is studied.

Shinozaki, Tetsuya; Oka, Makoto [Department of Physics, H-27, Tokyo Institute of Technology, Meguro, Tokyo 152-8551 (Japan); Takeuchi, Sachiko [Japan College of Social Work, Kiyose 204-8555 (Japan)

2006-09-01

350

Induced p-wave superfluidity in strongly interacting imbalanced Fermi gases  

SciTech Connect

The induced interaction among the majority spin species, due to the presence of the minority species, is computed for the case of a population-imbalanced resonantly interacting Fermi gas. It is shown that this interaction leads to an instability, at low temperatures, of the recently observed polaron Fermi liquid phase of strongly imbalanced Fermi gases to a p-wave superfluid state. We find that the associated transition temperature, while quite small in the weakly interacting BCS regime, is experimentally accessible in the strongly interacting unitary regime.

Patton, Kelly R.; Sheehy, Daniel E. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

2011-05-15

351

Creating p-wave superfluids and topological excitations in optical lattices  

SciTech Connect

We propose to realize a p-wave superfluid using bosons mixed with a single species of fermions in a deep optical lattice. We analyze with a self-consistent method its excitation spectrum in presence of a vortex, and we point out the range of interaction strengths in which the zero-energy mode with topological character exists on a finite optical lattice. Lattice effects are strongest close to fermionic half filling: here the linearity of the low-lying spectrum is lost, and a new class of extended zero-energy modes with checkerboard structure and d-wave symmetry appears.

Massignan, P. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona (Spain); Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); Sanpera, A. [Grup de Fisica Teorica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, E-08010 Barcelona (Spain); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels, Barcelona (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, E-08010 Barcelona (Spain)

2010-03-15

352

P wave morphology in guiding the ablation strategy of focal atrial tachycardias and atrial flutter.  

PubMed

Focal atrial tachycardias arise preferentially from specific locations within the atria. Careful analysis of the P wave can provide useful information about the chamber and likely site of origin within that chamber. Macro-reentrant atrial flutter also tends to occur over a limited number of potential circuits. In this case, the ECG usually gives a guide to the chamber of origin, but unless it shows a specific morphology it is less useful in delineating the circuit involved. Nonetheless, prior knowledge of the likely chamber of origin helps to plan the ablation strategy. PMID:25308814

Lee, Justin M S; Fynn, Simon P

2015-01-01

353

Ds1(2536)+ decays and the properties of P-wave charmed strange mesons  

NASA Astrophysics Data System (ADS)

Recently the Belle collaboration has measured a new decay channel for the charmed strange meson Ds1(2536)+(Ds1(2536)+?D+?-K+) together with an angular analysis of the Ds1(2536)+?D*+KS0 decay. We study this reaction in a constituent quark model which has been able to reproduce the hadronic phenomenology and the baryon-baryon interaction. The reported branching fractions and the properties of the Ds1(2536)+ state are nicely reproduced. Some consequences on the structure of the P-wave mesons are discussed.

Segovia, J.; Yasser, A. M.; Entem, D. R.; Fernández, F.

2009-09-01

354

Analysis and modeling of job arrivals in a production grid  

Microsoft Academic Search

In this paper we present an initial analysis of job arrivals in a production data-intensive Grid and investigate several traf- fic models for the interarrival time processes. Our analysis focuses on the heavy-tail behavior and autocorrelations, and the modeling is carried out at three different levels: Grid, Vir- tual Organization (VO), and region. A set of m-state Markov modulated Poisson

Hui Li; Michael Muskulus

2007-01-01

355

Modeling Job Arrivals in a Data-Intensive Grid  

Microsoft Academic Search

In this paper we present an initial analysis of job arrivals in a produc- tion data-intensive Grid and investigate several traffic models to characterize the interarrival time processes. Our analysis focuses on the heavy-tail behavior and autocorrelation structures, and the modeling is carried out at three different levels: Grid, Virtual Organization (VO), and region. A set of m-state Markov modulated

Hui Li; Michael Muskulus; Lex Wolters

2006-01-01

356

Analysis of sequencing and scheduling methods for arrival traffic  

NASA Technical Reports Server (NTRS)

The air traffic control subsystem that performs scheduling is discussed. The function of the scheduling algorithms is to plan automatically the most efficient landing order and to assign optimally spaced landing times to all arrivals. Several important scheduling algorithms are described and the statistical performance of the scheduling algorithms is examined. Scheduling brings order to an arrival sequence for aircraft. First-come-first-served scheduling (FCFS) establishes a fair order, based on estimated times of arrival, and determines proper separations. Because of the randomness of the traffic, gaps will remain in the scheduled sequence of aircraft. These gaps are filled, or partially filled, by time-advancing the leading aircraft after a gap while still preserving the FCFS order. Tightly scheduled groups of aircraft remain with a mix of heavy and large aircraft. Separation requirements differ for different types of aircraft trailing each other. Advantage is taken of this fact through mild reordering of the traffic, thus shortening the groups and reducing average delays. Actual delays for different samples with the same statistical parameters vary widely, especially for heavy traffic.

Neuman, Frank; Erzberger, Heinz

1990-01-01

357

Amplitude and angle of arrival measurements on a 28.56 GHz Earth-space path  

NASA Technical Reports Server (NTRS)

The amplitude and angle of arrival measurements on an Earth-space path using the 28.56 GHz COMSTAR D3 satellite beacon are described. These measurements were made by the Ohio State University ElectroScience Laboratory during the period September 1978 to September 1979. Monthly, quarterly, and annual distributions of attenuation, angle of arrival, and variance of both these parameters are reported. During this period, fades exceeding 29 dB for .00% of the time and angle of arrival fluctuations exceeding .12 degrees for .01% of the time were observed.

Devasirvatham, D. M. J.; Hodge, D. B.

1981-01-01

358

NASA's SOFIA Arrives in Christchurch, New Zealand, July 14, 2013 - Duration: 1:41.  

NASA Video Gallery

NASA's Stratospheric Observatory for Infrared Astronomy airborne observatory arrived at Christchurch International Airport, New Zealand, July 14 at 12:14 p.m. (New Zealand Standard Time) to investi...

359

P-Wave to Rayleigh-wave conversion coefficients for wedge corners; model experiments  

USGS Publications Warehouse

An analytic solution is not available for the diffraction of elastic waves by wedges; however, numerical solutions of finite-difference type are available for selected wedge angles. The P- to Rayleigh-wave conversion coefficients at wedge tips have been measured on two-dimensional seismic models for stress-free wedges with wedge angles, ??0, of 10, 30, 60, 90 and 120??. The conversion coefficients show two broad peaks and a minimum as a function of the angle between the wedge face and the direction of the incident P-wave. The minimum occurs for the P wave incident parallel to the wedge face and one maximum is near an incidence angle of 90?? to the wedge face. The amplitude of this maximum, relative to the other, decreases as the wedge angle increases. The asymmetry of the conversion coefficients, CPR(??; ??0), relative to parallel incidence (?? = 0) increases as the wedge angle increases. The locations of the maxima and the minimum as well as the asymmetry can be explained qualitatively. The conversion coefficients are measured with an accuracy of ??5% in those regions where there are no interfering waves. A comparison of the data for the 10?? wedge with the theoretical results for a half plane (0?? wedge) shows good correlation. ?? 1978.

Gangi, A.F.; Wesson, R.L.

1978-01-01

360

Seismic effects of incident P waves on an embedded foundation in poroelastic half-space  

NASA Astrophysics Data System (ADS)

Dynamic vibrations of a circular rigid foundation, which is embedded in poroelastic soil and subjected to incident P waves, are studied by semi-analytical methods in this present work. The motion of the soil is governed by Biot's dynamic poroelastic theory. A set of potentials are introduced to represent the incident waves, and the scattering waves caused by the foundation are considered based on the decomposition of the total wave field in soil. The soil along the vertical side of the foundation is assumed to be composed of series of infinitesimally thin poroelastic layers, while the soil under the foundation base is regarded as the poroelastic half-space and to be independent of the overlying soil. The interaction problem is solved by Hankel transforms. Then, combining the boundary conditions along the contact surface between the soil and the foundation and the dynamic equilibrium equation of the foundation, expressions of the vertical and rocking vibration amplitudes of the embedded foundation excited by the incident P waves are acquired. Numerical results are presented to demonstrate the influences of embedded depth, foundation mass, pore water in the soil and incident angle on the vibrations of the foundation.

Wang, Peng; Cai, Yuan-qiang; Ding, Guang-ya; Wang, Li-zhong

2012-03-01

361

p-wave Holographic Superconductors from Born-Infeld Black Holes  

E-print Network

We obtain (2+1) dimensional p-wave holographic superconductors from charged Born-Infeld black holes in the presence of massive charged vector fields in a bulk $AdS_4$ Einstein-Born-Infeld theory through the $AdS_4$-$CFT_3$ correspondence. Below a certain critical transition temperature the charged black hole develops vector hair that corresponds to charged vector condensate in the strongly coupled (2+1) dimensional boundary field theory that breaks both the $U(1)$ symmetry as well as the rotational invariance. The holographic free energy is computed for the boundary field theory which shows that the vector order parameter exhibits a rich phase structure involving zeroth order, first order, second order and retrograde phase transitions for different values of the backreaction and the Born-Infeld parameters. We numerically compute the ac conductivity for the p-wave superconducting phase of the strongly coupled (2+1) dimensional boundary field theory which also depends on the relative values of the parameters in...

Chaturvedi, Pankaj

2015-01-01

362

Application of P-wave Hybrid Theory to the Scattering of Electrons from He+ and Resonances in He and H ion  

NASA Technical Reports Server (NTRS)

The P-wave hybrid theory of electron-hydrogen elastic scattering [Phys. Rev. A 85, 052708 (2012)] is applied to the P-wave scattering from He ion. In this method, both short-range and long-range correlations are included in the Schroedinger equation at the same time, by using a combination of a modified method of polarized orbitals and the optical potential formalism. The short-correlation functions are of Hylleraas type. It is found that the phase shifts are not significantly affected by the modification of the target function by a method similar to the method of polarized orbitals and they are close to the phase shifts calculated earlier by Bhatia [Phys. Rev. A 69, 032714 (2004)]. This indicates that the correlation function is general enough to include the target distortion (polarization) in the presence of the incident electron. The important fact is that in the present calculation, to obtain similar results only a 20-term correlation function is needed in the wave function compared to the 220- term wave function required in the above-mentioned calculation. Results for the phase shifts, obtained in the present hybrid formalism, are rigorous lower bounds to the exact phase shifts. The lowest P-wave resonances in He atom and hydrogen ion have been calculated and compared with the results obtained using the Feshbach projection operator formalism [Phys. Rev. A, 11, 2018 (1975)]. It is concluded that accurate resonance parameters can be obtained by the present method, which has the advantage of including corrections due to neighboring resonances, bound states and the continuum in which these resonance are embedded.

Bhatia, A. K.

2012-01-01

363

P-wave Velocity, Density, and Vertical Stress Magnitude Along the Crustal Po Plain (Northern Italy) from Sonic Log Drilling Data  

NASA Astrophysics Data System (ADS)

In order to characterize better P-wave velocities for the shallow crust of the Po Plain and surrounding regions, we have selected 64 deep wells mainly located in the plain and also along the Apennine belt and Adriatic coast. In particular, we have analyzed the stratigraphic profiles for all wells, and the available sonic logs (37 out of 64). From these data we have examined the P-wave velocity trend with depth and estimated rock density following an empirical relationship between sonic velocity and density in sedimentary rocks. Then we have calculated, notably, for the first time in a large area of Italy, the overburden stress magnitude for each well. For instance, at a depth of 5 km we have found values varying from 105 to 130 MPa moving from the Adriatic coast to the Apennine belt. Consequently, the Apennine belt shows a maximum regional lithostatic gradient of around 26 MPa/km while the Po Plain and Adriatic region have values of around 21 MPa/km. The maximum density value that can be considered for the Apennine crustal belt corresponds to 2.65 g/cm3; in the Po Plain the mean density is around 2.25 g/cm3, while in the Adriatic area the average density has the lowest value in the region at 2.13 g/cm3. Although in this area a 2D crustal P-wave velocity model does not adequately constrain the complicated and uneven tectonics, we have nevertheless established a shallow model consisting of five separate layers. The strength of this paper lies in the possible use of these direct data, together with other derived geological and geophysical information, to build a 3D model of the area.

Montone, Paola; Mariucci, Maria Teresa

2015-01-01

364

Crustal structure of North Dakota from joint inversion of surface wave dispersion and teleseismic P-wave reciever functions  

NASA Astrophysics Data System (ADS)

Studying and determining crustal structure of the Earth is important for understanding the interior of the Earth. Using methods like receiver functions and surface wave dispersion allows the determination of differences in structure and composition through the crust. Jointly inverting receiver functions and surface wave dispersion reduces the error and over-interpretation of the crustal structure estimation. Receiver functions and surface wave dispersion invert well together because receiver functions are very sensitive to velocity contrasts and vertical travel times, and surface wave dispersion is sensitive to average velocity and insensitive to sharp velocity contrasts. By jointly inverting receiver functions and surface wave dispersion, shear wave velocity profiles can be created to determine the properties of the crustal structure and velocity contrasts. With the use of IRIS Transportable Array stations data throughout the United States, this thesis takes a closer look at the crustal structure of North Dakota through the joint inversion of surface wave dispersion and teleseismic P-wave receiver functions. The receiver functions in North Dakota show shallow sediment effects that affect the joint inversion process. In western North Dakota the Williston basin and in eastern North Dakota the Red River Valley cause ringing effects in the receiver functions. The shallow sediments in North Dakota control and overpower the rest of the crustal signal in the receiver functions, and thus affect the ability of determining the crustal shear wave velocity structure of North Dakota through the joint inversion of receiver functions and surface wave dispersion, thus the use of background geology is necessary.

Walsh, Braden Michael

365

Circum-Arctic mantle structure from global P-wave tomography - how consistent is it with plate-tectonic reconstructions?  

NASA Astrophysics Data System (ADS)

I present a preliminary, global-scale tomographic P-velocity model, and discuss it with a focus on the Arctic hemisphere. The model was obtained from waveform inversion of teleseismic P-waves, specifically using the method of multi-frequency inversion, an extension of finite-frequency tomography that systematically exploits the entire usable body-wave spectrum. The transition zone and mid-mantle are decently sampled, since the Arctic is surrounded by well-instrumented continents (Eurasia, North America, Japan). In addition, the past decade has seen the addition of a significant number of stations on Greenland and surrounding islands. I use a rigorously quality-controlled data set of broadband seismograms from IRIS, which is rather complete for the years 1999-2009, together with a smaller data set from the European data center ORFEUS. Global tomography models have rarely been discussed with a focus on the circum-Arctic region. Accordingly, this integrated investigation of tomography and plate tectonics is still in a reconnaissance stage. I compare my own model and a few other body-wave tomographies to a plate reconstruction model, in an attempt match up seismically fast anomalies (subducted slabs), with predicted paleo-trench locations. Shallow anomalies should correspond to recent subduction, deeper slabs to older subduction episodes. Slabs that are not overlain by a modeled trench at any time, or paleo-trenches without fast anomaly observed underneath, can point to gaps in our current understanding of the Arctic's plate-tectonic evolution.

Sigloch, K.

2012-04-01

366

Crustal P-wave velocity structure from Altyn Tagh to Longmen mountains along the Taiwan-Altay geoscience transect  

USGS Publications Warehouse

Based upon the seismic experiments along Geoscience Transect from the Altyn Tagh to the Longmen Mountains, the crustal P-wave velocity structure was derived to outline the characteristics of the crustal structure. The section shows a few significant features. The crustal thickness varies dramatically, and is consistent with tectonic settings. The Moho boundary abruptly drops to 73km depth beneath the southern Altyn Tagh from 50km below the Tarim basin, then rises again to about 58km depth beneath the Qaidam basin. Finally, the Moho drops again to about 70km underneath the Songpan-Garze Terrane and rises to 60km near the Longmen Mountains with a step-shape. Further southeast, the crust thins to 52km beneath the Sichuan basin in the southeast of the Longmen Mountains. In the north of the Kunlun fault, a low-velocity zone, which may be a layer of melted rocks due to high temperature and pressure at depth, exists in the the bottom of the middle crust. The two depressions of the Moho correlate with the Qilian and Songpan-Garze terranes, implying that these two mountains have thick roots. According to our results, it is deduced that the thick crust of the northeastern Tibetan Plateau probably is a result of east-west and northwest-southeast crustal shortening since Mesozoic time during the collision between the Asian and Indian plates.

Wang, Y.-X.; Mooney, W.D.; Han, G.-H.; Yuan, X.-C.; Jiang, M.

2005-01-01

367

Energy Harvesting Communications with Continuous Energy Arrivals  

E-print Network

Energy Harvesting Communications with Continuous Energy Arrivals Burak Varan Kaya Tutuncuoglu Aylin--This work considers an energy harvesting transmit- ter that gathers a continuous flow of energy from intermittent sources, thus relaxing the modeling assumption of discrete amounts of harvested energy present

Yener, Aylin

368

Wake Turbulence Mitigation for Arrivals (WTMA)  

NASA Technical Reports Server (NTRS)

The preliminary Wake Turbulence Mitigation for Arrivals (WTMA) concept of operations is described in this paper. The WTMA concept provides further detail to work initiated by the Wake Vortex Avoidance System Concept Evaluation Team and is an evolution of the Wake Turbulence Mitigation for Departure concept. Anticipated benefits about reducing wake turbulence separation standards in crosswind conditions, and candidate WTMA system considerations are discussed.

Williams, Daniel M.; Lohr, Gary W.; Trujillo, Anna C.

2008-01-01

369

New Accessions Arriving at Field Records  

USGS Multimedia Gallery

Materials arrive from across the country to be accessioned and processed at the Denver Library, Field Records Collection. Geologic Discipline scientists are encouraged to deposit their project materials and with the Field Records Collection. Materials in the collection are managed as Federal records...

370

Before you arrive... Drylands, Deserts & Desertification 2012  

E-print Network

1 Before you arrive... Drylands, Deserts & Desertification 2012 November 12-15, 2012 Sede Boqer that you can use to layer. Sde Boqer is part of the Negev desert, and will be cool in the mornings, warm on spending the weekend in any of the conference venues, please make sure to order food in advance, as almost

Prigozhin, Leonid

371

F-16: The Arrival of NASA 516  

NASA Technical Reports Server (NTRS)

NASA 516, NASA Langley's F-16A Research Support Aircraft is shown on arrival at the center in late summer of 1991. Delivered from Eglin AFB, NASA 516 provided an advanced fighter capability for Langley research pilots in support of advanced Fighter Research Programs at the center.

1991-01-01

372

Effects of p-wave annihilation on the angular power spectrum of extragalactic gamma-rays from dark matter annihilation  

SciTech Connect

We present a formalism for estimating the angular power spectrum of extragalactic gamma-rays produced by dark matter annihilating with any general velocity-dependent cross section. The relevant density and velocity distribution of dark matter is modeled as an ensemble of smooth, universal, rigid, disjoint, spherical halos with distribution and universal properties constrained by simulation data. We apply this formalism to theories of dark matter with p-wave annihilation, for which the relative-velocity-weighted annihilation cross section is {sigma}v=a+bv{sup 2}. We determine that this significantly increases the gamma-ray power if b/a > or approx. 10{sup 6}. The effect of p-wave annihilation on the angular power spectrum is very similar for the sample of particle physics models we explored, suggesting that the important effect for a given b/a is largely determined by the cosmic dark matter distribution. If the dark matter relic from strong p-wave theories is thermally produced, the intensities of annihilation gamma-rays are strongly p-wave suppressed, making them difficult to observe. If an angular power spectrum consistent with a strong p wave were to be observed, it would likely indicate nonthermal production of dark matter in the early Universe.

Campbell, Sheldon; Dutta, Bhaskar [Department of Physics and Astronomy, Texas A and M University, College Station, Texas 77843 (United States)

2011-10-01

373

Effects of exciting frequencies, grain sizes, and damage upon P-wave velocity for ultrasonic NDT of concrete  

NASA Astrophysics Data System (ADS)

This paper focuses on the experimental study of the effects of exciting frequencies, grain (aggregate) sizes, and damage upon the ultrasonic P-wave velocity when performing the ultrasonic nondestructive testing (NDT) for concrete specimens. Two batches of concrete and mortar specimens were prepared in the laboratory for the investigation of the effects from the stated factors upon the P-wave velocity. Damage here mostly refers to microcracks and microvoids in concrete. Five different aggregate sizes, 0' (mortar), 3/8', 1/2', 3/4', and 1', were selected to demonstrate the grain (aggregate) size effect. Exciting frequencies of the ultrasonic wave were set to range from 100 kHz to 1,000 kHz, with increment of 50 kHz, to demonstrate the frequency effect. Styrofoam particles were mixed into the comparison concrete and mortar specimens to simulate the distributed microvoids (damage). Different volume fractions of styrofoam particles were mixed into the mortar specimens in order to study the effect of different porosities (damage) upon the P-wave velocity. The experimental observations show that, for mortar and concrete specimens with aggregate sizes from 0 to 1 inch, the P-wave velocity would not be affected significantly within the tested frequency range (100 - 1000 kHz). The normalized P-wave velocity exhibits almost identical pattern upon the exciting frequencies for all specimens.

Ju, Jiann W.; Weng, Lisheng

2000-05-01

374

NASA's ATM Technology Demonstration-1: Integrated Concept of Arrival Operations  

NASA Technical Reports Server (NTRS)

This paper describes operations and procedures envisioned for NASA s Air Traffic Management (ATM) Technology Demonstration #1 (ATD-1). The ATD-1 Concept of Operations (ConOps) demonstration will integrate three NASA technologies to achieve high throughput, fuel-efficient arrival operations into busy terminal airspace. They are Traffic Management Advisor with Terminal Metering (TMA-TM) for precise time-based schedules to the runway and points within the terminal area, Controller-Managed Spacing (CMS) decision support tools for terminal controllers to better manage aircraft delay using speed control, and Flight deck Interval Management (FIM) avionics and flight crew procedures to conduct airborne spacing operations. The ATD-1 concept provides de-conflicted and efficient operations of multiple arrival streams of aircraft, passing through multiple merge points, from top-of-descent (TOD) to touchdown. It also enables aircraft to conduct Optimized Profile Descents (OPDs) from en route altitude to the runway, using primarily speed control to maintain separation and schedule. The ATD-1 project is currently addressing the challenges of integrating the three technologies, and implantation into an operational environment. Goals of the ATD-1 demonstration include increasing the throughput of high-density airports, reducing controller workload, increasing efficiency of arrival operations and the frequency of trajectory-based operations, and promoting aircraft ADS-B equipage.

Baxley, Brian T.; Swenson, Harry N.; Prevot, Thomas; Callantine, Todd J.

2012-01-01

375

Wilsonian RG Analysis of the P-wave Nucleon-Nucleon Scattering Including Pions  

NASA Astrophysics Data System (ADS)

We perform a Wilsonian renormalization group analysis for the nucleon-nucleon scattering in the P waves in the nuclear effective field theory including pions, in a similar way to the one done for the S-waves in our previous paper. We emphasize that the one-pion exchange interaction with large momentum transfer is of the same order as the leading contact interaction, so that there is no mismatch of the power counting. It is explicitly shown by obtaining consistent sets of renormalization group equations, that the cutoff dependence generated by the loop diagrams containing pion exchanges can be compensated by the cutoff dependence of the coupling constants of the contact interactions.

Harada, Koji; Kubo, Hirofumi; Sakaeda, Tatsuya; Yamamoto, Yuki

2013-08-01

376

Doubly excited P-wave resonance states of H- in Debye plasmas  

NASA Astrophysics Data System (ADS)

We investigate the doubly excited P-wave resonance states of H- system in Debye plasmas modeled by static screened Coulomb potentials. The screening effects of the plasma environment on resonance parameters (energy and width) are investigated by employing the complex-scaling method with Hylleraas-type wave functions for both the shape and Feshbach resonances associated with the H(N = 2 to 6) thresholds. Under the screening conditions, the H(N) threshold states are no longer l degenerate, and all the H- resonance energy levels are shifted away from their unscreened values toward the continuum. The influence of Debye plasmas on resonance widths has also been investigated. The shape resonance widths are broadened with increasing plasma screening strength, whereas the Feshbach resonance widths would generally decrease. Our results associated with the H(N = 2) and H(N = 3) thresholds are compared with others in the literature.

Jiao, L. G.; Ho, Y. K.

2013-08-01

377

Prediction of building limestone physical and mechanical properties by means of ultrasonic P-wave velocity.  

PubMed

The aim of this study was to evaluate ultrasonic P-wave velocity as a feature for predicting some physical and mechanical properties that describe the behavior of local building limestone. To this end, both ultrasonic testing and compressive tests were carried out on several limestone specimens and statistical correlation between ultrasonic velocity and density, compressive strength, and modulus of elasticity was studied. The effectiveness of ultrasonic velocity was evaluated by regression, with the aim of observing the coefficient of determination r(2) between ultrasonic velocity and the aforementioned parameters, and the mathematical expressions of the correlations were found and discussed. The strong relations that were established between ultrasonic velocity and limestone properties indicate that these parameters can be reasonably estimated by means of this nondestructive parameter. This may be of great value in a preliminary phase of the diagnosis and inspection of stone masonry conditions, especially when the possibility of sampling material cores is reduced. PMID:24511286

Concu, Giovanna; De Nicolo, Barbara; Valdes, Monica

2014-01-01

378

Current inversion at the edges of a chiral p -wave superconductor  

NASA Astrophysics Data System (ADS)

Motivated by Sr2RuO4, edge quasiparticle states are analyzed based on the self-consistent solution of the Bogolyubov-de Gennes equations for a topological chiral p -wave superconductor. Using a tight-binding model of a square lattice for the dominant ? band, we explore the nontrivial geometry and band structure dependence of the edge states and currents. As a peculiar finding, we show that, for high band fillings, currents flow in a reversed direction when comparing straight and zigzag edges. We give a simple explanation in terms of the positions of the zero-energy bound states using a quasiclassical picture. We also show that a Ginzburg-Landau approach can reproduce these results. Moreover, the band filling dependence of the most stable domain wall structure is discussed.

Bouhon, Adrien; Sigrist, Manfred

2014-12-01

379

Comparing the p-wave multipoles for ?0 photoproduction with low-energy predictions  

NASA Astrophysics Data System (ADS)

Recent estimates of the p-wave multipoles for p(?,?0) near threshold [J. C. Bergstrom, Phys. Rev. C 50, 2979 (1994)] are compared with new low-energy theorems (LETs) derived from heavy-baryon chiral perturbation theory. Very good agreement is obtained with the LET for the combination M1+-M1-, but a marked discrepancy exists with the LET for E1+. Comparison is also made with an explicit (model-dependent) evaluation of the multipoles which incorporates the off-shell behavior of the ?(1232) resonance in a generalized covariant form. Excellent agreement is observed for the multipole M1- including the isospin components, but again a substantial discrepancy exists with E1+. An experimental test of the conflicting E1+ results is suggested.

Bergstrom, J. C.

1995-10-01

380

Inclusive decays of ? into S- and P-wave charmonium states  

NASA Astrophysics Data System (ADS)

Inclusive S- and P-wave charmonium productions in the bottomonium ground state ?b decay are calculated at the leading order in the strong coupling constant ?s and quarkonium internal relative velocity v in the framework of the NRQCD factorization approach. We find the contribution of ?b??c_J+gg followed by ?c_J?J/?+? is also very important to inclusive J/? production in the ?b decays, which maybe helpful to the investigation of the color-octet mechanism in the inclusive J/? production in the ?b decays in the forthcoming LHCb and SuperB. As a complementary work, we also study the inclusive production of ?c, and ?cJ in the ?b decays, which may help us understand the X(3940) and X(3872) states.

He, Zhi-Guo; Li, Bai-Qing

2010-09-01

381

AdS-plane wave and p p -wave solutions of generic gravity theories  

NASA Astrophysics Data System (ADS)

We construct the anti-de Sitter-plane wave solutions of generic gravity theory built on the arbitrary powers of the Riemann tensor and its derivatives in analogy with the p p -wave solutions. In constructing the wave solutions of the generic theory, we show that the most general two-tensor built from the Riemann tensor and its derivatives can be written in terms of the traceless Ricci tensor. Quadratic gravity theory plays a major role; therefore, we revisit the wave solutions in this theory. As examples of our general formalism, we work out the six-dimensional conformal gravity and its nonconformal deformation as well as the tricritical gravity, the Lanczos-Lovelock theory, and string-generated cubic curvature theory.

Gürses, Metin; ?i?man, Tahsin ?a?r?; Tekin, Bayram

2014-12-01

382

Formation and propagation of Love waves from a P-wave source  

NASA Astrophysics Data System (ADS)

The objective of this research is to experimentally investigate and support, by finite element calculations, the formation and propagation of Love waves from a P-wave source due to scattering at material heterogeneities. A series of experiments were conducted where surface strains were measured parallel and perpendicular to a planar granite scattering surface. The granite wall that is cast in a surface layer waveguide of a low-impedance grout and then cast on a granite base provided the interface for generating horizontally polarized (SH) waves in the surface layer. The in-plane shear waves are the Love waves we measured at the surface. The P-wave source was a 1-cm-diameter spherical explosive of PETN diluted with microballoons to provide a charge density of 0.45 g/cm cast in a styrofoam sphere to further attenuate the peak pressure. We successfully measured the strains at three locations parallel to the wall and two locations perpendicular to the wall, and the test repeatability was good. Good agreement was also observed between the measured and calculated strain at all locations. The code calculations also showed that in-plane shear strains form along the surface layer/granite interface, and these shear strains propagate with little reduction in amplitude but transform relatively high-frequency oscillations to low-frequency wave packets. The experimental configuration used to generate and measure Love waves, an evaluation of the source used in the surface layer experiments, and results from finite element code calculations of the experiment are presented.

Florence, A. L.; Miller, S. A.; Kirkpatrick, S. W.

1992-01-01

383

Revision of P-wave velocity and thickness of hydrate layer in Shenhu Area, South China Sea  

NASA Astrophysics Data System (ADS)

To revise P-wave velocity and thickness of the hydrate layer in the Shenhu area of the South China Sea, acoustic and resistivity logging curves are reanalyzed. The waterlogging phenomenon is found in the shallow sediments of five drilling wells, which causes P-wave velocity to approximate the propagation velocity of sea water (about 1500 m s-1). This also affects the identification of the hydrate layer and results in the underestimate of its thickness. In addition, because there could be about a 5 m thick velocity ramp above or below the hydrate layer as interpreted by acoustic and resistivity logging curves, the recalibrated thickness of this layer is less than the original estimated thickness. The recalibrated P-wave velocity of the hydrate layer is also higher than the original estimated velocity. For the drilling well with a relatively thin hydrate layer, the velocity ramp plays a more important role in identifying and determining the thickness of the layer.

Gong, Jianming; Zhang, Xunhua; Zou, Changchun; Chen, Qiang; Wang, Lichen; Yuan, Chunfang; Hu, Gaowei; Jiang, Yubo

2014-10-01

384

Zero-Field Vortex-Induced Hall Effect and Polar Kerr Effect in Chiral p-Wave Superconductors near Kosterlitz-Thouless Transition  

NASA Astrophysics Data System (ADS)

In this work, we investigate polar Kerr effect and Ohmic conductivity induced by vortex dynamics in a chiral p-wave superconducting thin film near Kosterlitz-Thouless (KT) transition without explicitly applying magnetic field. Due to the broken time reversal symmetry in the superconducting state and the breaking of Galilean invariance by forces originated from impurities, a conductivity tensor with nonzero off-diagonal element is expected. We generalize the dynamical theory developed by Ambegaokar, Halperin, Nelson, and Siggia to obtain a matrix dielectric function describing vortex screening, which is further related to the conductivity tensor. Polar Kerr effect due to the nonzero Hall conductivity is studied. The corresponding Kerr angle is shown to be proportional to the imaginary part of off-diagonal component of the dielectric function in certain parameter regime. While the frequency and temperature dependence of dissipation in chiral p-wave context behave similarly to those of s-wave results, the Kerr angle exhibits some novel features near the KT transition. As a result, Kerr angle measurement in experiment can provide a probe of vortex dynamics described in this work.

Chung, C. K.; Kato, Y.

2014-04-01

385

A Realization of Quantum Non-Local Persistent Current: Coupled Metallic Rings through a P-Wave Chiral Superconducting Wire  

NASA Astrophysics Data System (ADS)

The excitations in the p-wave superconductors Sr2Ru O4, ^3He-A and the ?=52 quantum Hall effect are characterized by half vortices, which are zero mode energy Majorana fermions. We consider a p-wave superconducting wire for which the pairing order parameter vanishes at the edges and two zero modes appear at x=0 and x=L. Due to the charge conjugation of the Bogoliubov spectrum these zero modes are Majorana Fermions. The ground state is a Z2 doubly degenerate state and the single particle excitations are non-local. We couple the p-wave wire to two rings, which are pierced by external fluxes, and compute persistent current. The non-locality of the persistent current is manifested in the following way: (a) For a single ring with flux coupled to the p-wave wire at x=0 and grounded at x=L, due to the Andreev reflection the current in one ring will decay faster than if we decouple the wire. (b) For two rings with equal fluxes attached to the p-wave wire at x=0 and the second at x=L the current will be equal and independent of the length of the wire. When the flux is ? we will have a Berry phase of ?. (c) For dufferent fluxes the currents in the two rings will vanish. This situation is very different if instead of a p-wave wire we attach a metallic wire for which the current will be uncorrelated in the two rings.

Schmeltzer, David; Saxena, Avadh

2010-03-01

386

P-wave dispersion and its relationship to aortic stiffness in patients with acute myocardial infarction after cardiac rehabilitation  

PubMed Central

BACKGROUND The aim of our study was to investigate the P-wave dispersion from standard electrocardiograms (ECGs) in patients with acute myocardial infarction (AMI) after cardiac rehabilitation (CR) and determine its relation to arterial stiffness. METHODS This is a prospective study included 33 patients with AMI and successfully re-vascularized by percutaneous coronary intervention (PCI) underwent CR. Left ventricular ejection fraction (LVEF) was measured by biplane Simpson’s method. Left atrium (LA) volume was calculated. The maximum and minimum durations of P-waves (Pmax and Pmin, respectively) were detected, and the difference between Pmax and Pmin was defined as P-wave dispersion (Pd = Pmax-Pmin). Aortic elasticity parameters were measured. RESULTS LVEF was better after CR. The systolic and diastolic blood pressures decreased after CR, these differences were statistically significant. With exercise training, LA volume decreased significantly. Pmax and Pd values were significantly shorter after the CR program. The maximum and minimum P-waves and P-wave dispersion after CR were 97 ± 6 ms, 53 ± 5 ms, and 44 ± 5 ms, respectively. Aortic strain and distensibility increased and aortic stiffness index was decreased significantly. Aortic stiffness index was 0.4 ± 0.2 versus 0.3 ± 0.2, P = 0.001. Aortic stiffness and left atrial volume showed a moderate positive correlation with P-wave dispersion (r = 0.52, P = 0.005; r = 0.64, P < 0.001, respectively). CONCLUSION This study showed decreased arterial stiffness indexes in AMI patient’s participated CR, with a significant relationship between the electromechanical properties of the LA that may raise a question of the preventive effect of CR from atrial fibrillation and stroke in patients with acute myocardial infarction. PMID:25258633

Acar, Rezzan Deniz; Bulut, Mustafa; Ergün, Sunay; Yesin, Mahmut; Boztosun, Bilal; Akçakoyun, Mustafa

2014-01-01

387

Spring arrival response to climate change in birds: a case study from eastern Europe  

Microsoft Academic Search

This paper analyses the dependence of the first spring arrival dates of short\\/medium- and long-distance migrant bird species\\u000a on climate warming in eastern Europe. The timing of arrival of the selected species at the observation site correlates with\\u000a the North Atlantic Oscillation (NAO) index, air temperature, atmospheric pressure, precipitation and wind characteristics.\\u000a A positive correlation of fluctuations in winter and

Mecislovas Zalakevicius; Galina Bartkeviciene; Liutauras Raudonikis; Justinas Janulaitis

2006-01-01

388

Designing Cyclic Appointment Schedules for Outpatient Clinics with Scheduled and Unscheduled Patient Arrivals  

E-print Network

that balance the waiting time at the facility for unscheduled patients and the access time for scheduled; Service Operations; Appointment Schedul- ing; Queuing Theory; Stochastic Methods. 1 #12;1 Introduction demand and as a consequence low utilization and high waiting time (the time between the physical arrival

Boucherie, Richard J.

389

Optimal Integration of Departure and Arrivals in Terminal Airspace  

NASA Technical Reports Server (NTRS)

Coordination of operations with spatially and temporally shared resources such as route segments, fixes, and runways improves the efficiency of terminal airspace management. Problems in this category include scheduling and routing, thus they are normally difficult to solve compared with pure scheduling problems. In order to reduce the computational time, a fast time algorithm formulation using a non-dominated sorting genetic algorithm (NSGA) was introduced in this work and applied to a test case based on existing literature. The experiment showed that new method can solve the whole problem in fast time instead of solving sub-problems sequentially with a window technique. The results showed a 60% or 406 second delay reduction was achieved by sharing departure fixes (more details on the comparison with MILP results will be presented in the final paper). Furthermore, the NSGA algorithm was applied to a problem in LAX terminal airspace, where interactions between 28% of LAX arrivals and 10% of LAX departures are resolved by spatial segregation, which may introduce unnecessary delays. In this work, spatial segregation, temporal segregation, and hybrid segregation were formulated using the new algorithm. Results showed that spatial and temporal segregation approaches achieved similar delay. Hybrid segregation introduced much less delay than the other two approaches. For a total of 9 interacting departures and arrivals, delay reduction varied from 4 minutes to 6.4 minutes corresponding flight time uncertainty from 0 to 60 seconds. Considering the amount of flights that could be affected, total annual savings with hybrid segregation would be significant.

Xue, Min; Zelinski, Shannon Jean

2012-01-01

390

P-wave monitoring of an unconsolidated and partially saturated porous medium : an experimental study  

NASA Astrophysics Data System (ADS)

Nowadays, it is well admitted that hydrogeological properties of porous media (porosity, fluid saturation and permeability) can influence seismic properties. In geophysics, the major theory which links hydrogeological and seismic parameters is poroelasticity proposed by Biot (1956). The Biot relaxation process is due to the relative displacement of fluid in comparison to the solid which causes a significant attenuation of seismic waves, notably in unconsolidated and highly permeable media. Laboratory experiments are necessary to better understand the effects of fluids on velocity dispersion and attenuation of seismic waves but few ones are done in the low frequency range (1Hz to 10 kHz) where the wavelength is greater than heterogeneities size. In order to analyse the role of partial saturation on direct P-waves phase velocity and attenuation, we performed a laboratory experiment in the kiloHertz range to avoid scale effects between field studies and traditional ultrasonic laboratory measurements. This experiment consists in a sand-filled tank equiped with accelerometers and water capacitance probes, where seismic propagation is generated by hitting a steel ball on a granite plate. Several imbibition/drainage cycles were performed between the water and gas residual saturations. Seismic data were processed by a Continuous Wavelet Transform using the complex Morlet wavelet which was numerically validated using a viscoelastic 2D code for wave propagation (Specfem2D). Phase velocity of direct P-wave decreases with the increase of water content, that is quite consistent with Biot-Gassmann-Wood (BGW) limit of the Biot's theory both for imbibition and drainage. This behaviour indicates that the fluid mixture (gaz and water) can be averaged as an effective fluid, which is typical of field seismic applications. In this experiment, attenuation is very strong and cannot be fully explained by the macroscopic fluid flow of Biot's theory. It is necessary to introduce a viscoelastic contribution linked to the grain to grain overall losses, which are described by a constant Q-model. Moreover, hysteresis between imbibition and drainage are observed and explained by introducing an effective permeability of the mixture depending on water and gas relative permeabilities.

Barriere, J.; Bordes, C.; Sénéchal, P.; Brito, D.; Perroud, H.

2012-04-01

391

Automated Conflict Resolution, Arrival Management and Weather Avoidance for ATM  

NASA Technical Reports Server (NTRS)

The paper describes a unified solution to three types of separation assurance problems that occur in en-route airspace: separation conflicts, arrival sequencing, and weather-cell avoidance. Algorithms for solving these problems play a key role in the design of future air traffic management systems such as NextGen. Because these problems can arise simultaneously in any combination, it is necessary to develop integrated algorithms for solving them. A unified and comprehensive solution to these problems provides the foundation for a future air traffic management system that requires a high level of automation in separation assurance. The paper describes the three algorithms developed for solving each problem and then shows how they are used sequentially to solve any combination of these problems. The first algorithm resolves loss-of-separation conflicts and is an evolution of an algorithm described in an earlier paper. The new version generates multiple resolutions for each conflict and then selects the one giving the least delay. Two new algorithms, one for sequencing and merging of arrival traffic, referred to as the Arrival Manager, and the other for weather-cell avoidance are the major focus of the paper. Because these three problems constitute a substantial fraction of the workload of en-route controllers, integrated algorithms to solve them is a basic requirement for automated separation assurance. The paper also reviews the Advanced Airspace Concept, a proposed design for a ground-based system that postulates redundant systems for separation assurance in order to achieve both high levels of safety and airspace capacity. It is proposed that automated separation assurance be introduced operationally in several steps, each step reducing controller workload further while increasing airspace capacity. A fast time simulation was used to determine performance statistics of the algorithm at up to 3 times current traffic levels.

Erzberger, H.; Lauderdale, Todd A.; Chu, Yung-Cheng

2010-01-01

392

Multicomponent seismic data, combining P-wave and converted P-to-SV wave (C-wave) wavefields, provide inde-  

E-print Network

to improve P- wave reflection quality by combining hydrophone and ver- tical-geophone data and to improve objectives were to evaluate seismic attributes, such as VP/VS velocity ratios and Poisson's ratio derived to image the internal stratigra- phy of gas hydrate systems in the GOM warrants further study. Diagnostic

Texas at Austin, University of

393

9 CFR 93.804 - Declaration upon arrival.  

Code of Federal Regulations, 2010 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Elephants, Hippopotami, Rhinoceroses, and Tapirs...Declaration upon arrival. Upon arrival of an elephant, hippopotamus, rhinoceros, or...broker; (g) The region from which the elephant, hippopotamus, rhinoceros, or...

2010-01-01

394

7 CFR 352.7 - Notice of arrival.  

Code of Federal Regulations, 2011 CFR

... § 352.7 Notice of arrival. Immediately upon arrival of any shipment of plants or plant products (including noxious weeds) subject to this part and covered by a specific permit, the importer shall submit in duplicate through the...

2011-01-01

395

7 CFR 352.7 - Notice of arrival.  

... § 352.7 Notice of arrival. Immediately upon arrival of any shipment of plants or plant products (including noxious weeds) subject to this part and covered by a specific permit, the importer shall submit in duplicate through the...

2014-01-01

396

7 CFR 319.75-6 - Arrival notification.  

Code of Federal Regulations, 2010 CFR

...Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Khapra Beetle § 319.75-6 Arrival notification. Promptly upon arrival of any restricted article at a port of entry, the...

2010-01-01

397

7 CFR 319.75-6 - Arrival notification.  

Code of Federal Regulations, 2013 CFR

...Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Khapra Beetle § 319.75-6 Arrival notification. Promptly upon arrival of any restricted article at a port of entry, the...

2013-01-01

398

7 CFR 319.75-6 - Arrival notification.  

...Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Khapra Beetle § 319.75-6 Arrival notification. Promptly upon arrival of any restricted article at a port of entry, the...

2014-01-01

399

7 CFR 319.75-6 - Arrival notification.  

Code of Federal Regulations, 2011 CFR

...Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Khapra Beetle § 319.75-6 Arrival notification. Promptly upon arrival of any restricted article at a port of entry, the...

2011-01-01

400

7 CFR 319.75-6 - Arrival notification.  

Code of Federal Regulations, 2012 CFR

...Continued) ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Khapra Beetle § 319.75-6 Arrival notification. Promptly upon arrival of any restricted article at a port of entry, the...

2012-01-01

401

7 CFR 319.37-11 - Arrival notification.  

Code of Federal Regulations, 2011 CFR

...ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Nursery Stock, Plants, Roots, Bulbs, Seeds, and Other Plant Products 1,2 § 319.37-11 Arrival notification. Promptly upon arrival...

2011-01-01

402

7 CFR 319.37-11 - Arrival notification.  

Code of Federal Regulations, 2010 CFR

...ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Nursery Stock, Plants, Roots, Bulbs, Seeds, and Other Plant Products 1,2 § 319.37-11 Arrival notification. Promptly upon arrival...

2010-01-01

403

BCS-BEC Crossover and Chiral Anomaly in p-Wave Superfluids with the Symmetry of A1-Phase  

NASA Astrophysics Data System (ADS)

We solve the Leggett equations for BCS-BEC crossover in the 3D resonance p-wave superfluid with the symmetry of A1-phase. We calculate sound velocity, normal density and specific heat for the BCS-domain ( ?>0), BEC-domain ( ?<0) as well as close to important point ?=0 in 100% polarized case. We find the indications of quantum phase-transition close to the point ?( T=0)=0. Deep in BCS and BEC-domains the crossover ideas of Leggett and Nozieres, Schmitt-Rink work pretty well. We discuss the spectrum of orbital waves, the paradox of intrinsic angular momentum and complicated problem of chiral anomaly in BCS A1-phase at T=0. We present two different approaches to a chiral anomaly: one based on supersymmetric hydrodynamics, another one on the formal analogy with Dirac equation in quantum electrodynamics (QED theory). We evaluate the damping of nodal fermions due to different decay processes in superclean case at T=0 and find that we are in a ballistic regime ? ??1. We propose to use aerogel or nonmagnetic impurities to reach hydrodynamic regime ? ??1 at T=0. We discuss the concept of spectral flow and exact cancellations between time-derivatives of anomalous and quasiparticle currents in the equation for the conservation of total linear momentum. We propose to derive and solve a kinetic equation for nodal quasiparticles both in the hydrodynamic and in the ballistic regimes to demonstrate this cancellation explicitly. We briefly discuss the role of the other residual interactions different from damping and invite experimentalists to measure the spectrum and damping of orbital waves in A-phase of 3He at low temperatures.

Kagan, M. Y.; Efremov, D. V.

2010-03-01

404

Static and Dynamic Reservoir Characterization Using High Resolution P-Wave Velocity Data in Delhi Field, la  

NASA Astrophysics Data System (ADS)

Static and dynamic reservoir characterization was done on high resolution P-wave seismic data in Delhi Field, LA to study the complex stratigraphy of the Holt-Bryant sands and to delineate the CO2 flow path. The field is undergoing CO2 injection for enhanced oil recovery. The seismic data was bandwidth extended by Geotrace to decrease the tuning thickness effect. Once the authenticity of the added frequencies in the data was determined, the interpretation helped map thin Tuscaloosa and Paluxy sands. Cross-equalization was done on the baseline and monitor surveys to remove the non-repeatable noise in the data. Acoustic impedance (AI) inversion was done on the baseline and monitor surveys to map the changes in AI with CO2 injection in the field. Figure 1 shows the AI percentage change at Base Paluxy. The analysis helped identify areas that were not being swept by CO2. Figure 2 shows the CO2 flow paths in Tuscaloosa formation. The percentage change of AI with CO2 injection and pressure increase corresponded with the fluid substitution modeling results. Time-lapse interpretation helped in delineating the channels, high permeability zones and the bypassed zones in the reservoir.; Figure 1: P-impedance percentage difference map with a 2 ms window centered at the base of Paluxy with the production data from June 2010 overlain; the black dashed line is the oil-water contact; notice the negative impedance change below the OWC. The lighter yellow color shows area where Paluxy is not being swept completely. ; Figure 2: P-impedance percentage difference map at TUSC 7 top; the white triangles are TUSC 7 injectors and the white circles are TUSC 7 producers; the black polygons show the flow paths of CO2.

Hussain, S.; Davis, T.

2012-12-01

405

Metaheuristics to minimise makespan on parallel batch processing machines with dynamic job arrivals  

Microsoft Academic Search

Batch processing machines that can process a group of jobs simultaneously are often encountered in semiconductor manufacturing and metal heat treatment. This research investigates the scheduling problem on parallel batch processing machines in the presence of dynamic job arrivals and non-identical job sizes. The processing time and ready time of a batch are equal to the largest processing time and

Huaping Chen; Bing Du; George Q. Huang

2010-01-01

406

Designing Cyclic Appointment Schedules for Outpatient Clinics with Scheduled and Unscheduled Patient Arrivals  

E-print Network

process of scheduled arrivals. Appointment schedules that balance the waiting time at the facility and Scheduling; Queuing Theory; Stochastic Methods 1 Introduction Developing appointment schedules for service are a possible highly variable demand and as a consequence low utilization and high waiting time (the time

Boucherie, Richard J.

407

Modeling warning times for the Israel's earthquake early warning system  

NASA Astrophysics Data System (ADS)

In June 2012, the Israeli government approved the offer of the creation of an earthquake early warning system (EEWS) that would provide timely alarms for schools and colleges in Israel. A network configuration was chosen, consisting of a staggered line of ˜100 stations along the main regional faults: the Dead Sea fault and the Carmel fault, and an additional ˜40 stations spread more or less evenly over the country. A hybrid approach to the EEWS alarm was suggested, where a P-wave-based system will be combined with the S-threshold method. The former utilizes first arrivals to several stations closest to the event for prompt location and determination of the earthquake's magnitude from the first 3 s of the waveform data. The latter issues alarms, when the acceleration of the surface movement exceeds a threshold for at least two neighboring stations. The threshold will be chosen to be a peak acceleration level corresponding to a magnitude 5 earthquake at a short distance range (5-10 km). The warning times or lead times, i.e., times between the alarm signal arrival and arrival of the damaging S-waves, are considered for the P, S, and hybrid EEWS methods. For each of the approaches, the P- and the S-wave travel times and the alarm times were calculated using a standard 1D velocity model and some assumptions regarding the EEWS data latencies. Then, a definition of alarm effectiveness was introduced as a measure of the trade-off between the warning time and the shaking intensity. A number of strong earthquake scenarios, together with anticipated shaking intensities at important targets, namely cities with high populations, are considered. The scenarios demonstrated in probabilistic terms how the alarm effectiveness varies depending on the target distance from the epicenter and event magnitude.

Pinsky, Vladimir

2015-01-01

408

Transport Properties of Chiral p-wave Superconductor-Normal Metal Nanostructures  

NASA Astrophysics Data System (ADS)

In this thesis, we present a theory of electron transport for unconventional superconductors. We focus on the superconducting properties of Sr2RuO 4, which is a strong candidate for two dimensional p-wave superconductivity in electronic systems. We present Green function formulation of the theory of superconductivity and reduce the formulation within quasiclassical approximation. To study the systems with disordered normal metal junctions, we derive the boundary conditions of quasiclassical equations from the microscopic theory considering a spin active boundary. Boundary between normal metal and superconductor is modeled with Rashba type spin orbit coupling. An exact solution of the resulting equations are given and the resistance of the model system is calculated as a function of temperature, boundary transparency and superconducting state symmetry. The developed theory is used to study the phase transition of unconventional superconductors with increasing impurity concentration. It has been shown that, in the strong disordered regime, system can be modeled as Mattis model known from the theory of spin glasses. We show that with increasing disorder there will be two consecutive phase transitions: A phase transition from unconventional superconductor to s-wave superconductor followed by a transition from s-wave superconductor to normal metal. A qualitative phase diagram is prsented and corrections to Mattis model approximation is considered.

Keles, Ahmet

409

Hybrid Theory of P-Wave Electron-Hydrogen Elastic Scattering  

NASA Technical Reports Server (NTRS)

We report on a study of electron-hydrogen scattering, using a combination of a modified method of polarized orbitals and the optical potential formalism. The calculation is restricted to P waves in the elastic region, where the correlation functions are of Hylleraas type. It is found that the phase shifts are not significantly affected by the modification of the target function by a method similar to the method of polarized orbitals and they are close to the phase shifts calculated earlier by Bhatia. This indicates that the correlation function is general enough to include the target distortion (polarization) in the presence of the incident electron. The important fact is that in the present calculation, to obtain similar results only 35-term correlation function is needed in the wave function compared to the 220-term wave function required in the above-mentioned previous calculation. Results for the phase shifts, obtained in the present hybrid formalism, are rigorous lower bounds to the exact phase shifts.

Bhatia, Anand

2012-01-01

410

19 CFR 123.61 - Baggage arriving in baggage car.  

...2014-04-01 false Baggage arriving in baggage car. 123.61 Section 123.61 Customs...123.61 Baggage arriving in baggage car. An inward foreign manifest on Customs...used for all baggage arriving in baggage cars. [T.D. 70-121, 35 FR 8215,...

2014-04-01

411

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2011 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2011-01-01

412

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2013 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2013-01-01

413

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2012 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2012-01-01

414

9 CFR 93.706 - Notification of arrival.  

Code of Federal Regulations, 2010 CFR

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2010-01-01

415

9 CFR 93.706 - Notification of arrival.  

...CONVEYANCE AND SHIPPING CONTAINERS Miscellaneous Animals § 93.706 Notification of arrival. Upon the arrival of a hedgehog or tenrec at the port of first arrival in the United States, the importer or his or her agent must present the import...

2014-01-01

416

P-1 truss arrival at KSC  

NASA Technical Reports Server (NTRS)

On July 26, 2000 the P-1 truss arrived at Kennedy Space Center's Shuttle Landing Facility aboard its 'Super Guppy' transport. The P-1 truss, scheduled to fly in spring of 2002, is part of a total 10-truss, girder-like structure that will ultimately extend the length of a football field. Astronauts will attach the 14-by-15 foot structure to the port side of the center truss, SO, during the spring assembly flight. The 33,000-pound P- 1 will house the thermal radiator rotating joint (TRRJ) that will rotate the International Space Station's radiators away from the sun to increase their maximum cooling efficiency.

2000-01-01

417

Order of arrival structures arbuscular mycorrhizal colonization of plants.  

PubMed

Priority effects - the impact of a species' arrival on subsequent community development - have been shown to influence species composition in many organisms. Whether priority effects among arbuscular mycorrhizal fungi (AMF) structure fungal root communities is not well understood. Here, we investigated whether priority effects influence the success of two closely related AMF species (Rhizophagus irregularis and Glomus aggregatum), hypothesizing that a resident AMF suppresses invader success, this effect is time-dependent and a resident will experience reduced growth when invaded. We performed two glasshouse experiments using modified pots, which permitted direct inoculation of resident and invading AMF on the roots. We quantified intraradical AMF abundances using quantitative PCR and visual colonization percentages. We found that both fungi suppressed the invading species and that this effect was strongly dependent on the time lag between inoculations. In contrast to our expectations, neither resident AMF was negatively affected by invasion. We show that order of arrival can influence the abundance of AMF species colonizing a host. These priority effects can have important implications for AMF ecology and the use of fungal inocula in sustainable agriculture. PMID:25298030

Werner, Gijsbert D A; Kiers, E Toby

2014-10-01

418

Rapid expansion and pseudo spectral implementation for reverse time migration in VTI media  

NASA Astrophysics Data System (ADS)

In isotropic media, we use the scalar acoustic wave equation to perform reverse time migration (RTM) of the recorded pressure wavefield data. In anisotropic media, P- and SV-waves are coupled, and the elastic wave equation should be used for RTM. For computational efficiency, a pseudo-acoustic wave equation is often used. This may be solved using a coupled system of second-order partial differential equations. We solve these using a pseudo spectral method and the rapid expansion method (REM) for the explicit time marching. This method generates a degenerate SV-wave in addition to the P-wave arrivals of interest. To avoid this problem, the elastic wave equation for vertical transversely isotropic (VTI) media can be split into separate wave equations for P- and SV-waves. These separate wave equations are stable, and they can be effectively used to model and migrate seismic data in VTI media where |? - ?| is small. The artifact for the SV-wave has also been removed. The independent pseudo-differential wave equations can be solved one for each mode using the pseudo spectral method for the spatial derivatives and the REM for the explicit time advance of the wavefield. We show numerically stable and high-resolution modeling and RTM results for the pure P-wave mode in VTI media.

Pestana, Reynam C.; Ursin, Bjørn; Stoffa, Paul L.

2012-06-01

419

Measurement of parity-nonconserving rotation of neutron spin in the 0.734-eV p-wave resonance of $^{139}La$  

E-print Network

The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave resonance of $^{139}La$ was measured with the neutron transmission method. Two optically polarized $^3He$ cells were used before and behind a a 5-cm long $^{139}La$ target as a polarizer and an analyzer of neutron spin. The rotation angle was carefully measured by flipping the direction of $^3He$ polarization in the polarizer in sequence. The peak-to-peak value of the spin rotation was found to be $ (7.4 \\pm 1.1) \\times 10^{-3} $ rad/cm which was consistent with the previous experiments. But the result was statisticallly improved. The s-p mixing model gives the weak matrix element as $xW = (1.71 \\pm 0.25)$ meV. The value agrees well with the one deduced from the parity-nonconserving longitudinal asymmetry in the same resonance.

T. Haseyama; K. Asahi; J. D. Bowman; P. P. J. Delheij; H. Funahashi; S. Ishimoto; G. Jones; A. Masaike; Y. Masuda; Y. Matsuda; K. Morimoto; S. Muto; S. I. Penttilä; V. R. Pomeroy; K. Sakai; E. I. Sharapov; D. A. Smith; V. W. Yuan

2001-11-21

420

Recent Investigations and Findings about the 2d- and 3d- Neutron Strength Functions and the p-wave Scattering Radius  

NASA Astrophysics Data System (ADS)

Comprehensive and detailed investigations were recently undertaken due to the scarcity of available data on the neutron d-wave strength functions and the need to obtain precise average resonance parameters for advanced technologies. This information is derived by fitting available total cross section data from few keV to 14 MeV neutron energy using the least-squares method, where the total cross section is described in terms of the scattering radius R? for various partial waves, the s-, p-, d-, f- and g- neutron strength functions, neutron penetration factors and phase shifts. The present results reveal the following findings: (i) the peak of the 2d strength function is observed for the first time at A=50; (ii) due to nuclear deformation effects, the 3d-peak is depressed producing two peaks located at 152 and 170, similar to the s-wave case; (iii) except for the deformed mass region, a spherical optical model calculation for the d-wave strength function reasonably describes the trend of the present data; (iv) the derived s- and p-wave strength functions and the s-wave scattering radii are in good agreement with those obtained from the resolved energy region, as reported in the Atlas of Neutron Resonances; (v) the d-wave strength functions are however generally discrepant with available data; (vi) several d-wave strength functions are derived here for the first time; (vii) a new finding is that the p-wave scattering radii for 92 nuclei in the mass region 16O-242Pu exhibit minima roughly at A?80 and 230 and maxima at A?50 and 160.

Mughabghab, S. F.

2014-04-01

421

A probabilistic approach to the automatic recognition of underwater acoustic signals generated by teleseismic P-waves  

NASA Astrophysics Data System (ADS)

We present a new method for the automatic recognition of underwater acoustic signals generated by teleseismic P-waves. The method is based on the analysis of the relative power distribution among different frequency bands and utilizes the discrete wavelet transform (DWT) as a signal processing tool. The DWT can be performed in integer arithmetic on low-power CPU's which helps to minimize energy consumption. By analyzing the relative power distributions of a large number of P-wave signals, we derived a statistical model for P-waves. For each band we calculate the probability of committing a Type I error during recognition, i.e. the error of rejecting a P-wave signal while it should be accepted. The overall resemblance between a detected signal and the statistical model is then quantified by an empirical criterion C, which is a weighted average of all probabilities. The method was applied to the 6-month-long continuous records of seven ocean bottom hydrophones deployed in the Ligurian sea during the Grosmarin experiment. We also show that the signal-to-noise ratio (SNR) of the analyzed signal can be used as an additional recognition criterion and can help eliminate false positive recognitions. By running the recognition method on the complete data base of the Grosmarin experiment, thresholds C0 and SNR0 were determined which allowed to obtain a maximum rate of correct recognitions of 94% with zero false positives. Finally, the method was tested on an independent data set recorded by the same instrument as those used in the Grosmarin experiment, but deployed in a different geographic location. By applying the thresholds C0 and SNR0 found for the Grosmarin data, 75% of all detected teleseismic P-wave signals were recognized correctly with only two false positives, one of which is due to electronic noise and another is most likely due to a local earthquake. Our method is not limited to the recognition of teleseismic P-waves and can be applied to the recognition of any signals whose statistical models differ sufficiently from those of other intervening signals.

Sukhovich, A.; Irisson, J.; Simons, F. J.; Ogé, A.; Hello, Y.; Deschamps, A.; Nolet, G.

2011-12-01

422

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume VI S-Wave Measurements in Borehole C4997 Seismic Records, Wave-Arrival Identifications and Interpreted S-Wave Velocity Profile.  

SciTech Connect

Velocity measurements in shallow sediments from ground surface to approximately 370 to 400 feet bgs were collected by Redpath Geophysics using impulsive S- and P-wave seismic sources (Redpath 2007). Measurements below this depth within basalt and sedimentary interbeds were made by UTA between October and December 2006 using the T-Rex vibratory seismic source in each of the three boreholes. Results of these measurements including seismic records, wave-arrival identifications and interpreted velocity profiles are presented in the following six volumes: I. P-Wave Measurements in Borehole C4993 II. P-Wave Measurements in Borehole C4996 III. P-Wave Measurements in Borehole C4997 IV. S-Wave Measurements in Borehole C4993 V. S-Wave Measurements in Borehole C4996 VI. S-Wave Measurements in Borehole C4997 In this volume (VI), all S-wave measurements are presented that were performed in Borehole C4997 at the WTP with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver.

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

423

Deep Downhole Seismic Testing at the Waste Treatment Plant Site, Hanford, WA. Volume V S-Wave Measurements in Borehole C4996 Seismic Records, Wave-Arrival Identifications and Interpreted S-Wave Velocity Profile.  

SciTech Connect

Velocity measurements in shallow sediments from ground surface to approximately 370 to 400 feet bgs were collected by Redpath Geophysics using impulsive S- and P-wave seismic sources (Redpath 2007). Measurements below this depth within basalt and sedimentary interbeds were made by UTA between October and December 2006 using the T-Rex vibratory seismic source in each of the three boreholes. Results of these measurements including seismic records, wave-arrival identifications and interpreted velocity profiles are presented in the following six volumes: I. P-Wave Measurements in Borehole C4993 II. P-Wave Measurements in Borehole C4996 III. P-Wave Measurements in Borehole C4997 IV. S-Wave Measurements in Borehole C4993 V. S-Wave Measurements in Borehole C4996 VI. S-Wave Measurements in Borehole C4997 In this volume (V), all S-wave measurements are presented that were performed in Borehole C4996 at the WTP with T-Rex as the seismic source and the Lawrence Berkeley National Laboratory (LBNL) 3-D wireline geophone as the at-depth borehole receiver.

Stokoe, Kenneth H.; Li, Song Cheng; Cox, Brady R.; Menq, Farn-Yuh

2007-06-06

424

POSITIONING USING TIMEDIFFERENCE OF ARRIVAL MEASUREMENTS Fredrik Gustafsson and Fredrik Gunnarsson  

E-print Network

) measurements occurs in a range of ap­ plications from wireless communication networks to elec­ tronic warfare rather insensitive to fading is based on time of arrival (TOA). In future system, only the time's (0.4, 0.6 and 0.9 scale units, respectively). . Electronic warfare, where the problem

Gustafsson, Fredrik

425

Geographic Variation in Tsunami Warning Center Response Time: Identifying Areas of Greatest Concern  

NASA Astrophysics Data System (ADS)

Close to a tsunami source, people who feel an earthquake can self-evacuate to higher ground if they understand the significance of severe ground shaking. Far from a tsunami source, or even in the case of nearby “slow” earthquakes, people can only evacuate coastal areas if they receive a timely warning from a local civil defense agency or a dedicated tsunami warning center (TWC). This reality requires a TWC to operate differently from a typical seismic observatory, since a TWC must estimate the earthquake source parameters as fast as possible with a minimum of seismic data, then use these estimated source parameters to assess the tsunami-generating potential of the earthquake and issue warnings when appropriate. Using known constraints for likely tsunamigenic earthquakes such as location, tsunami and P-wave travel time, and the amount of data and time required to analyze an earthquake, we can predict how rapidly a TWC can issue a warning for the coastlines it is charged to protect. In our analysis we use the digitized convergent margins from the UTIG plate boundary data set as a proxy for subduction-zone earthquakes. We then calculate P-wave travel time on the surface of the earth using the IASPEI P-wave travel time table for shallow (33 km) sources. We also use these proxy sources to calculate tsunami travel time from these sources to coastlines with a 64-node Huygens construction method and GEBCO 2-minute global bathymetery. We estimate the warning center's analysis time for these proxy sources by summing the time required for a specific number of seismic stations to register the P-waves, the data transmission latency time from the stations to the warning center, and the typical time required to process these data. We apply this method to the Pacific Tsunami Warning Center (PTWC), which mitigates tsunami hazards in the Pacific Ocean, the Indian Ocean, and the Caribbean Sea. For this purpose PTWC collects and analyzes teleseismic data from a global seismic network. We estimate the time required for P-waves generated by subduction zone earthquakes to reach the number of stations typically needed to produce a tsunami warning. We then project these data to the nearest coastlines to produce a table of P-wave reception times for earthquakes affecting these coastlines. Next, we subtract these reception time values from the travel time of tsunamis from these earthquakes to the coastlines. The resulting data sets and corresponding maps reveal the time window of opportunity for populations to act upon PTWC's warnings and safely evacuate these coastal areas. Our maps show that while most of the world's coastal populations have an hour or more to evacuate after receiving a warning from PTWC, certain coastlines have less than an hour, and in the worst cases, the first tsunami wave will arrive before PTWC can warn the affected areas. While our analysis reveals response problems for a given tsunami warning center, it also highlights the solutions by indicating where to install and monitor additional seismic stations, and where data outages could have the greatest negative impact, thus showing where redundancy in station deployment is most critical.

Becker, N. C.; Sardiña, V.; Cessaro, R. K.; Fryer, G. J.; Weinstein, S.

2010-12-01

426

Manipulation of p-Wave Scattering of Cold Atoms in Low Dimensions Using the Magnetic Field Vector  

NASA Astrophysics Data System (ADS)

It is well known that the magnetic Feshbach resonances of cold atoms are sensitive to the magnitude of the external magnetic field. Much less attention has been paid to the direction of such a field. In this work we calculate the scattering properties of spin polarized fermionic atoms in reduced dimensions, near a p-wave Feshbach resonance. Because of the spatial anisotropy of the p-wave interaction, the scattering has a nontrivial dependence on both the magnitude and the direction of the magnetic field. In addition, we identify an inelastic scattering process which is impossible in the isotropic-interaction model; the rate of this process depends considerably on the direction of the magnetic field. Significantly, an Einstein-Podolsky-Rosen entangled pair of identical fermions may be produced during this inelastic collision. This work opens a new method to manipulate resonant cold atomic interactions.

Peng, Shi-Guo; Tan, Shina; Jiang, Kaijun

2014-06-01

427

Imbalanced ultracold Fermi gas in the weakly repulsive regime: Renormalization-group approach for p-wave superfluidity  

SciTech Connect

We theoretically study a possible pairing mechanism for a two-dimensional population imbalanced Fermi gas with short-range repulsive interactions, which can be realized on the upper branch of a Feshbach resonance. We use a well-controlled renormalization-group approach, which allows an unbiased study of the instabilities of imbalanced Fermi liquid without assumption of a broken symmetry and gives a numerical calculation of the transition temperature from microscopic parameters. Our results show a leading superfluid instability in the p-wave channel for the majority species. The corresponding mechanism is that there are effective attractive interactions for the majority species, induced by the particle-hole susceptibility of the minority species, where the mismatch of the Fermi surfaces of the two species plays an important role. We also propose an experimental protocol for detecting the