Sample records for accurate source locations

  1. Towards an accurate real-time locator of infrasonic sources

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Blom, P.; Polozov, A.; Marcillo, O.; Arrowsmith, S.; Hofstetter, A.

    2017-11-01

    Infrasonic signals propagate from an atmospheric source via media with stochastic and fast space-varying conditions. Hence, their travel time, the amplitude at sensor recordings and even manifestation in the so-called "shadow zones" are random. Therefore, the traditional least-squares technique for locating infrasonic sources is often not effective, and the problem for the best solution must be formulated in probabilistic terms. Recently, a series of papers has been published about Bayesian Infrasonic Source Localization (BISL) method based on the computation of the posterior probability density function (PPDF) of the source location, as a convolution of a priori probability distribution function (APDF) of the propagation model parameters with likelihood function (LF) of observations. The present study is devoted to the further development of BISL for higher accuracy and stability of the source location results and decreasing of computational load. We critically analyse previous algorithms and propose several new ones. First of all, we describe the general PPDF formulation and demonstrate that this relatively slow algorithm might be among the most accurate algorithms, provided the adequate APDF and LF are used. Then, we suggest using summation instead of integration in a general PPDF calculation for increased robustness, but this leads us to the 3D space-time optimization problem. Two different forms of APDF approximation are considered and applied for the PPDF calculation in our study. One of them is previously suggested, but not yet properly used is the so-called "celerity-range histograms" (CRHs). Another is the outcome from previous findings of linear mean travel time for the four first infrasonic phases in the overlapping consecutive distance ranges. This stochastic model is extended here to the regional distance of 1000 km, and the APDF introduced is the probabilistic form of the junction between this travel time model and range-dependent probability

  2. Location of acoustic emission sources generated by air flow

    PubMed

    Kosel; Grabec; Muzic

    2000-03-01

    The location of continuous acoustic emission sources is a difficult problem of non-destructive testing. This article describes one-dimensional location of continuous acoustic emission sources by using an intelligent locator. The intelligent locator solves a location problem based on learning from examples. To verify whether continuous acoustic emission caused by leakage air flow can be located accurately by the intelligent locator, an experiment on a thin aluminum band was performed. Results show that it is possible to determine an accurate location by using a combination of a cross-correlation function with an appropriate bandpass filter. By using this combination, discrete and continuous acoustic emission sources can be located by using discrete acoustic emission sources for locator learning.

  3. Hydrogen atoms can be located accurately and precisely by x-ray crystallography.

    PubMed

    Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M; Woźniak, Krzysztof; Jayatilaka, Dylan

    2016-05-01

    Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A-H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A-H bond lengths with those from neutron measurements for A-H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors.

  4. Hydrogen atoms can be located accurately and precisely by x-ray crystallography

    PubMed Central

    Woińska, Magdalena; Grabowsky, Simon; Dominiak, Paulina M.; Woźniak, Krzysztof; Jayatilaka, Dylan

    2016-01-01

    Precise and accurate structural information on hydrogen atoms is crucial to the study of energies of interactions important for crystal engineering, materials science, medicine, and pharmacy, and to the estimation of physical and chemical properties in solids. However, hydrogen atoms only scatter x-radiation weakly, so x-rays have not been used routinely to locate them accurately. Textbooks and teaching classes still emphasize that hydrogen atoms cannot be located with x-rays close to heavy elements; instead, neutron diffraction is needed. We show that, contrary to widespread expectation, hydrogen atoms can be located very accurately using x-ray diffraction, yielding bond lengths involving hydrogen atoms (A–H) that are in agreement with results from neutron diffraction mostly within a single standard deviation. The precision of the determination is also comparable between x-ray and neutron diffraction results. This has been achieved at resolutions as low as 0.8 Å using Hirshfeld atom refinement (HAR). We have applied HAR to 81 crystal structures of organic molecules and compared the A–H bond lengths with those from neutron measurements for A–H bonds sorted into bonds of the same class. We further show in a selection of inorganic compounds that hydrogen atoms can be located in bridging positions and close to heavy transition metals accurately and precisely. We anticipate that, in the future, conventional x-radiation sources at in-house diffractometers can be used routinely for locating hydrogen atoms in small molecules accurately instead of large-scale facilities such as spallation sources or nuclear reactors. PMID:27386545

  5. Continuous wavelet transform analysis and modal location analysis acoustic emission source location for nuclear piping crack growth monitoring

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mohd, Shukri; Holford, Karen M.; Pullin, Rhys

    2014-02-12

    Source location is an important feature of acoustic emission (AE) damage monitoring in nuclear piping. The ability to accurately locate sources can assist in source characterisation and early warning of failure. This paper describe the development of a novelAE source location technique termed 'Wavelet Transform analysis and Modal Location (WTML)' based on Lamb wave theory and time-frequency analysis that can be used for global monitoring of plate like steel structures. Source location was performed on a steel pipe of 1500 mm long and 220 mm outer diameter with nominal thickness of 5 mm under a planar location test setup usingmore » H-N sources. The accuracy of the new technique was compared with other AE source location methods such as the time of arrival (TOA) techniqueand DeltaTlocation. Theresults of the study show that the WTML method produces more accurate location resultscompared with TOA and triple point filtering location methods. The accuracy of the WTML approach is comparable with the deltaT location method but requires no initial acoustic calibration of the structure.« less

  6. Nonexposure Accurate Location K-Anonymity Algorithm in LBS

    PubMed Central

    2014-01-01

    This paper tackles location privacy protection in current location-based services (LBS) where mobile users have to report their exact location information to an LBS provider in order to obtain their desired services. Location cloaking has been proposed and well studied to protect user privacy. It blurs the user's accurate coordinate and replaces it with a well-shaped cloaked region. However, to obtain such an anonymous spatial region (ASR), nearly all existent cloaking algorithms require knowing the accurate locations of all users. Therefore, location cloaking without exposing the user's accurate location to any party is urgently needed. In this paper, we present such two nonexposure accurate location cloaking algorithms. They are designed for K-anonymity, and cloaking is performed based on the identifications (IDs) of the grid areas which were reported by all the users, instead of directly on their accurate coordinates. Experimental results show that our algorithms are more secure than the existent cloaking algorithms, need not have all the users reporting their locations all the time, and can generate smaller ASR. PMID:24605060

  7. Accurate source location from waves scattered by surface topography: Applications to the Nevada and North Korean test sites

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Wang, N.; Bao, X.; Flinders, A. F.

    2016-12-01

    Scattered waves generated near the source contains energy converted from the near-field waves to the far-field propagating waves, which can be used to achieve location accuracy beyond the diffraction limit. In this work, we apply a novel full-wave location method that combines a grid-search algorithm with the 3D Green's tensor database to locate the Non-Proliferation Experiment (NPE) at the Nevada test site and the North Korean nuclear tests. We use the first arrivals (Pn/Pg) and their immediate codas, which are likely dominated by waves scattered at the surface topography near the source, to determine the source location. We investigate seismograms in the frequency of [1.0 2.0] Hz to reduce noises in the data and highlight topography scattered waves. High resolution topographic models constructed from 10 and 90 m grids are used for Nevada and North Korea, respectively. The reference velocity model is based on CRUST 1.0. We use the collocated-grid finite difference method on curvilinear grids to calculate the strain Green's tensor and obtain synthetic waveforms using source-receiver reciprocity. The `best' solution is found based on the least-square misfit between the observed and synthetic waveforms. To suppress random noises, an optimal weighting method for three-component seismograms is applied in misfit calculation. Our results show that the scattered waves are crucial in improving resolution and allow us to obtain accurate solutions with a small number of stations. Since the scattered waves depends on topography, which is known at the wavelengths of regional seismic waves, our approach yields absolute, instead of relative, source locations. We compare our solutions with those of USGS and other studies. Moreover, we use differential waveforms to locate pairs of the North Korea tests from years 2006, 2009, 2013 and 2016 to further reduce the effects of unmodeled heterogeneities and errors in the reference velocity model.

  8. Locating the source of spreading in temporal networks

    NASA Astrophysics Data System (ADS)

    Huang, Qiangjuan; Zhao, Chengli; Zhang, Xue; Yi, Dongyun

    2017-02-01

    The topological structure of many real networks changes with time. Thus, locating the sources of a temporal network is a creative and challenging problem, as the enormous size of many real networks makes it unfeasible to observe the state of all nodes. In this paper, we propose an algorithm to solve this problem, named the backward temporal diffusion process. The proposed algorithm calculates the shortest temporal distance to locate the transmission source. We assume that the spreading process can be modeled as a simple diffusion process and by consensus dynamics. To improve the location accuracy, we also adopt four strategies to select which nodes should be observed by ranking their importance in the temporal network. Our paper proposes a highly accurate method for locating the source in temporal networks and is, to the best of our knowledge, a frontier work in this field. Moreover, our framework has important significance for controlling the transmission of diseases or rumors and formulating immediate immunization strategies.

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roussel-Dupre, R.; Symbalisty, E.; Fox, C.

    2009-08-01

    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 themore » 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).« less

  10. Simultaneous head tissue conductivity and EEG source location estimation.

    PubMed

    Akalin Acar, Zeynep; Acar, Can E; Makeig, Scott

    2016-01-01

    Accurate electroencephalographic (EEG) source localization requires an electrical head model incorporating accurate geometries and conductivity values for the major head tissues. While consistent conductivity values have been reported for scalp, brain, and cerebrospinal fluid, measured brain-to-skull conductivity ratio (BSCR) estimates have varied between 8 and 80, likely reflecting both inter-subject and measurement method differences. In simulations, mis-estimation of skull conductivity can produce source localization errors as large as 3cm. Here, we describe an iterative gradient-based approach to Simultaneous tissue Conductivity And source Location Estimation (SCALE). The scalp projection maps used by SCALE are obtained from near-dipolar effective EEG sources found by adequate independent component analysis (ICA) decomposition of sufficient high-density EEG data. We applied SCALE to simulated scalp projections of 15cm(2)-scale cortical patch sources in an MR image-based electrical head model with simulated BSCR of 30. Initialized either with a BSCR of 80 or 20, SCALE estimated BSCR as 32.6. In Adaptive Mixture ICA (AMICA) decompositions of (45-min, 128-channel) EEG data from two young adults we identified sets of 13 independent components having near-dipolar scalp maps compatible with a single cortical source patch. Again initialized with either BSCR 80 or 25, SCALE gave BSCR estimates of 34 and 54 for the two subjects respectively. The ability to accurately estimate skull conductivity non-invasively from any well-recorded EEG data in combination with a stable and non-invasively acquired MR imaging-derived electrical head model could remove a critical barrier to using EEG as a sub-cm(2)-scale accurate 3-D functional cortical imaging modality. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Simultaneous head tissue conductivity and EEG source location estimation

    PubMed Central

    Acar, Can E.; Makeig, Scott

    2015-01-01

    Accurate electroencephalographic (EEG) source localization requires an electrical head model incorporating accurate geometries and conductivity values for the major head tissues. While consistent conductivity values have been reported for scalp, brain, and cerebrospinal fluid, measured brain-to-skull conductivity ratio (BSCR) estimates have varied between 8 and 80, likely reflecting both inter-subject and measurement method differences. In simulations, mis-estimation of skull conductivity can produce source localization errors as large as 3 cm. Here, we describe an iterative gradient-based approach to Simultaneous tissue Conductivity And source Location Estimation (SCALE). The scalp projection maps used by SCALE are obtained from near-dipolar effective EEG sources found by adequate independent component analysis (ICA) decomposition of sufficient high-density EEG data. We applied SCALE to simulated scalp projections of 15 cm2-scale cortical patch sources in an MR image-based electrical head model with simulated BSCR of 30. Initialized either with a BSCR of 80 or 20, SCALE estimated BSCR as 32.6. In Adaptive Mixture ICA (AMICA) decompositions of (45-min, 128-channel) EEG data from two young adults we identified sets of 13 independent components having near-dipolar scalp maps compatible with a single cortical source patch. Again initialized with either BSCR 80 or 25, SCALE gave BSCR estimates of 34 and 54 for the two subjects respectively. The ability to accurately estimate skull conductivity non-invasively from any well-recorded EEG data in combination with a stable and non-invasively acquired MR imaging-derived electrical head model could remove a critical barrier to using EEG as a sub-cm2-scale accurate 3-D functional cortical imaging modality. PMID:26302675

  12. Locating the source of diffusion in complex networks by time-reversal backward spreading.

    PubMed

    Shen, Zhesi; Cao, Shinan; Wang, Wen-Xu; Di, Zengru; Stanley, H Eugene

    2016-03-01

    Locating the source that triggers a dynamical process is a fundamental but challenging problem in complex networks, ranging from epidemic spreading in society and on the Internet to cancer metastasis in the human body. An accurate localization of the source is inherently limited by our ability to simultaneously access the information of all nodes in a large-scale complex network. This thus raises two critical questions: how do we locate the source from incomplete information and can we achieve full localization of sources at any possible location from a given set of observable nodes. Here we develop a time-reversal backward spreading algorithm to locate the source of a diffusion-like process efficiently and propose a general locatability condition. We test the algorithm by employing epidemic spreading and consensus dynamics as typical dynamical processes and apply it to the H1N1 pandemic in China. We find that the sources can be precisely located in arbitrary networks insofar as the locatability condition is assured. Our tools greatly improve our ability to locate the source of diffusion in complex networks based on limited accessibility of nodal information. Moreover, they have implications for controlling a variety of dynamical processes taking place on complex networks, such as inhibiting epidemics, slowing the spread of rumors, pollution control, and environmental protection.

  13. Locating the source of diffusion in complex networks by time-reversal backward spreading

    NASA Astrophysics Data System (ADS)

    Shen, Zhesi; Cao, Shinan; Wang, Wen-Xu; Di, Zengru; Stanley, H. Eugene

    2016-03-01

    Locating the source that triggers a dynamical process is a fundamental but challenging problem in complex networks, ranging from epidemic spreading in society and on the Internet to cancer metastasis in the human body. An accurate localization of the source is inherently limited by our ability to simultaneously access the information of all nodes in a large-scale complex network. This thus raises two critical questions: how do we locate the source from incomplete information and can we achieve full localization of sources at any possible location from a given set of observable nodes. Here we develop a time-reversal backward spreading algorithm to locate the source of a diffusion-like process efficiently and propose a general locatability condition. We test the algorithm by employing epidemic spreading and consensus dynamics as typical dynamical processes and apply it to the H1N1 pandemic in China. We find that the sources can be precisely located in arbitrary networks insofar as the locatability condition is assured. Our tools greatly improve our ability to locate the source of diffusion in complex networks based on limited accessibility of nodal information. Moreover, they have implications for controlling a variety of dynamical processes taking place on complex networks, such as inhibiting epidemics, slowing the spread of rumors, pollution control, and environmental protection.

  14. Source Identification and Location Techniques

    NASA Technical Reports Server (NTRS)

    Weir, Donald; Bridges, James; Agboola, Femi; Dougherty, Robert

    2001-01-01

    Mr. Weir presented source location results obtained from an engine test as part of the Engine Validation of Noise Reduction Concepts program. Two types of microphone arrays were used in this program to determine the jet noise source distribution for the exhaust from a 4.3 bypass ratio turbofan engine. One was a linear array of 16 microphones located on a 25 ft. sideline and the other was a 103 microphone 3-D "cage" array in the near field of the jet. Data were obtained from a baseline nozzle and from numerous nozzle configuration using chevrons and/or tabs to reduce the jet noise. Mr. Weir presented data from two configurations: the baseline nozzle and a nozzle configuration with chevrons on both the core and bypass nozzles. This chevron configuration had achieved a jet noise reduction of 4 EPNdB in small scale tests conducted at the Glenn Research Center. IR imaging showed that the chevrons produced significant improvements in mixing and greatly reduced the length of the jet potential core. Comparison of source location data from the 1-D phased array showed a shift of the noise sources towards the nozzle and clear reductions of the sources due to the noise reduction devices. Data from the 3-D array showed a single source at a frequency of 125 Hz. located several diameters downstream from the nozzle exit. At 250 and 400 Hz., multiple sources, periodically spaced, appeared to exist downstream of the nozzle. The trend of source location moving toward the nozzle exit with increasing frequency was also observed. The 3-D array data also showed a reduction in source strength with the addition of chevrons. The overall trend of source location with frequency was compared for the two arrays and with classical experience. Similar trends were observed. Although overall trends with frequency and addition of suppression devices were consistent between the data from the 1-D and the 3-D arrays, a comparison of the details of the inferred source locations did show differences. A

  15. Microseismic source locations with deconvolution migration

    NASA Astrophysics Data System (ADS)

    Wu, Shaojiang; Wang, Yibo; Zheng, Yikang; Chang, Xu

    2018-03-01

    Identifying and locating microseismic events are critical problems in hydraulic fracturing monitoring for unconventional resources exploration. In contrast to active seismic data, microseismic data are usually recorded with unknown source excitation time and source location. In this study, we introduce deconvolution migration by combining deconvolution interferometry with interferometric cross-correlation migration (CCM). This method avoids the need for the source excitation time and enhances both the spatial resolution and robustness by eliminating the square term of the source wavelets from CCM. The proposed algorithm is divided into the following three steps: (1) generate the virtual gathers by deconvolving the master trace with all other traces in the microseismic gather to remove the unknown excitation time; (2) migrate the virtual gather to obtain a single image of the source location and (3) stack all of these images together to get the final estimation image of the source location. We test the proposed method on complex synthetic and field data set from the surface hydraulic fracturing monitoring, and compare the results with those obtained by interferometric CCM. The results demonstrate that the proposed method can obtain a 50 per cent higher spatial resolution image of the source location, and more robust estimation with smaller errors of the localization especially in the presence of velocity model errors. This method is also beneficial for source mechanism inversion and global seismology applications.

  16. Locating People Diagnosed With HIV for Public Health Action: Utility of HIV Case Surveillance and Other Data Sources.

    PubMed

    Padilla, Mabel; Mattson, Christine L; Scheer, Susan; Udeagu, Chi-Chi N; Buskin, Susan E; Hughes, Alison J; Jaenicke, Thomas; Wohl, Amy Rock; Prejean, Joseph; Wei, Stanley C

    Human immunodeficiency virus (HIV) case surveillance and other health care databases are increasingly being used for public health action, which has the potential to optimize the health outcomes of people living with HIV (PLWH). However, often PLWH cannot be located based on the contact information available in these data sources. We assessed the accuracy of contact information for PLWH in HIV case surveillance and additional data sources and whether time since diagnosis was associated with accurate contact information in HIV case surveillance and successful contact. The Case Surveillance-Based Sampling (CSBS) project was a pilot HIV surveillance system that selected a random population-based sample of people diagnosed with HIV from HIV case surveillance registries in 5 state and metropolitan areas. From November 2012 through June 2014, CSBS staff members attempted to locate and interview 1800 sampled people and used 22 data sources to search for contact information. Among 1063 contacted PLWH, HIV case surveillance data provided accurate telephone number, address, or HIV care facility information for 239 (22%), 412 (39%), and 827 (78%) sampled people, respectively. CSBS staff members used additional data sources, such as support services and commercial people-search databases, to locate and contact PLWH with insufficient contact information in HIV case surveillance. PLWH diagnosed <1 year ago were more likely to have accurate contact information in HIV case surveillance than were PLWH diagnosed ≥1 year ago ( P = .002), and the benefit from using additional data sources was greater for PLWH with more longstanding HIV infection ( P < .001). When HIV case surveillance cannot provide accurate contact information, health departments can prioritize searching additional data sources, especially for people with more longstanding HIV infection.

  17. Enhancing source location protection in wireless sensor networks

    NASA Astrophysics Data System (ADS)

    Chen, Juan; Lin, Zhengkui; Wu, Di; Wang, Bailing

    2015-12-01

    Wireless sensor networks are widely deployed in the internet of things to monitor valuable objects. Once the object is monitored, the sensor nearest to the object which is known as the source informs the base station about the object's information periodically. It is obvious that attackers can capture the object successfully by localizing the source. Thus, many protocols have been proposed to secure the source location. However, in this paper, we examine that typical source location protection protocols generate not only near but also highly localized phantom locations. As a result, attackers can trace the source easily from these phantom locations. To address these limitations, we propose a protocol to enhance the source location protection (SLE). With phantom locations far away from the source and widely distributed, SLE improves source location anonymity significantly. Theory analysis and simulation results show that our SLE provides strong source location privacy preservation and the average safety period increases by nearly one order of magnitude compared with existing work with low communication cost.

  18. A precise and accurate acupoint location obtained on the face using consistency matrix pointwise fusion method.

    PubMed

    Yanq, Xuming; Ye, Yijun; Xia, Yong; Wei, Xuanzhong; Wang, Zheyu; Ni, Hongmei; Zhu, Ying; Xu, Lingyu

    2015-02-01

    To develop a more precise and accurate method, and identified a procedure to measure whether an acupoint had been correctly located. On the face, we used an acupoint location from different acupuncture experts and obtained the most precise and accurate values of acupoint location based on the consistency information fusion algorithm, through a virtual simulation of the facial orientation coordinate system. Because of inconsistencies in each acupuncture expert's original data, the system error the general weight calculation. First, we corrected each expert of acupoint location system error itself, to obtain a rational quantification for each expert of acupuncture and moxibustion acupoint location consistent support degree, to obtain pointwise variable precision fusion results, to put every expert's acupuncture acupoint location fusion error enhanced to pointwise variable precision. Then, we more effectively used the measured characteristics of different acupuncture expert's acupoint location, to improve the measurement information utilization efficiency and acupuncture acupoint location precision and accuracy. Based on using the consistency matrix pointwise fusion method on the acupuncture experts' acupoint location values, each expert's acupoint location information could be calculated, and the most precise and accurate values of each expert's acupoint location could be obtained.

  19. Travel-time source-specific station correction improves location accuracy

    NASA Astrophysics Data System (ADS)

    Giuntini, Alessandra; Materni, Valerio; Chiappini, Stefano; Carluccio, Roberto; Console, Rodolfo; Chiappini, Massimo

    2013-04-01

    Accurate earthquake locations are crucial for investigating seismogenic processes, as well as for applications like verifying compliance to the Comprehensive Test Ban Treaty (CTBT). Earthquake location accuracy is related to the degree of knowledge about the 3-D structure of seismic wave velocity in the Earth. It is well known that modeling errors of calculated travel times may have the effect of shifting the computed epicenters far from the real locations by a distance even larger than the size of the statistical error ellipses, regardless of the accuracy in picking seismic phase arrivals. The consequences of large mislocations of seismic events in the context of the CTBT verification is particularly critical in order to trigger a possible On Site Inspection (OSI). In fact, the Treaty establishes that an OSI area cannot be larger than 1000 km2, and its larger linear dimension cannot be larger than 50 km. Moreover, depth accuracy is crucial for the application of the depth event screening criterion. In the present study, we develop a method of source-specific travel times corrections based on a set of well located events recorded by dense national seismic networks in seismically active regions. The applications concern seismic sequences recorded in Japan, Iran and Italy. We show that mislocations of the order of 10-20 km affecting the epicenters, as well as larger mislocations in hypocentral depths, calculated from a global seismic network and using the standard IASPEI91 travel times can be effectively removed by applying source-specific station corrections.

  20. Joint Inversion of Source Location and Source Mechanism of Induced Microseismics

    NASA Astrophysics Data System (ADS)

    Liang, C.

    2014-12-01

    Seismic source mechanism is a useful property to indicate the source physics and stress and strain distribution in regional, local and micro scales. In this study we jointly invert source mechanisms and locations for microseismics induced in fluid fracturing treatment in the oil and gas industry. For the events that are big enough to see waveforms, there are quite a few techniques can be applied to invert the source mechanism including waveform inversion, first polarity inversion and many other methods and variants based on these methods. However, for events that are too small to identify in seismic traces such as the microseismics induced by the fluid fracturing in the Oil and Gas industry, a source scanning algorithms (SSA for short) with waveform stacking are usually applied. At the same time, a joint inversion of location and source mechanism are possible but at a cost of high computation budget. The algorithm is thereby called Source Location and Mechanism Scanning Algorithm, SLMSA for short. In this case, for given velocity structure, all possible combinations of source locations (X,Y and Z) and source mechanism (Strike, Dip and Rake) are used to compute travel-times and polarities of waveforms. Correcting Normal moveout times and polarities, and stacking all waveforms, the (X, Y, Z , strike, dip, rake) combination that gives the strongest stacking waveform is identified as the solution. To solve the problem of high computation problem, CPU-GPU programing is applied. Numerical datasets are used to test the algorithm. The SLMSA has also been applied to a fluid fracturing datasets and reveal several advantages against the location only method: (1) for shear sources, the source only program can hardly locate them because of the canceling out of positive and negative polarized traces, but the SLMSA method can successfully pick up those events; (2) microseismic locations alone may not be enough to indicate the directionality of micro-fractures. The statistics of

  1. An FBG acoustic emission source locating system based on PHAT and GA

    NASA Astrophysics Data System (ADS)

    Shen, Jing-shi; Zeng, Xiao-dong; Li, Wei; Jiang, Ming-shun

    2017-09-01

    Using the acoustic emission locating technology to monitor the health of the structure is important for ensuring the continuous and healthy operation of the complex engineering structures and large mechanical equipment. In this paper, four fiber Bragg grating (FBG) sensors are used to establish the sensor array to locate the acoustic emission source. Firstly, the nonlinear locating equations are established based on the principle of acoustic emission, and the solution of these equations is transformed into an optimization problem. Secondly, time difference extraction algorithm based on the phase transform (PHAT) weighted generalized cross correlation provides the necessary conditions for the accurate localization. Finally, the genetic algorithm (GA) is used to solve the optimization model. In this paper, twenty points are tested in the marble plate surface, and the results show that the absolute locating error is within the range of 10 mm, which proves the accuracy of this locating method.

  2. Enhancements to the Bayesian Infrasound Source Location Method

    DTIC Science & Technology

    2012-09-01

    ENHANCEMENTS TO THE BAYESIAN INFRASOUND SOURCE LOCATION METHOD Omar E. Marcillo, Stephen J. Arrowsmith, Rod W. Whitaker, and Dale N. Anderson Los...ABSTRACT We report on R&D that is enabling enhancements to the Bayesian Infrasound Source Location (BISL) method for infrasound event location...the Bayesian Infrasound Source Location Method 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER

  3. Acoustic emission source location in complex structures using full automatic delta T mapping technique

    NASA Astrophysics Data System (ADS)

    Al-Jumaili, Safaa Kh.; Pearson, Matthew R.; Holford, Karen M.; Eaton, Mark J.; Pullin, Rhys

    2016-05-01

    An easy to use, fast to apply, cost-effective, and very accurate non-destructive testing (NDT) technique for damage localisation in complex structures is key for the uptake of structural health monitoring systems (SHM). Acoustic emission (AE) is a viable technique that can be used for SHM and one of the most attractive features is the ability to locate AE sources. The time of arrival (TOA) technique is traditionally used to locate AE sources, and relies on the assumption of constant wave speed within the material and uninterrupted propagation path between the source and the sensor. In complex structural geometries and complex materials such as composites, this assumption is no longer valid. Delta T mapping was developed in Cardiff in order to overcome these limitations; this technique uses artificial sources on an area of interest to create training maps. These are used to locate subsequent AE sources. However operator expertise is required to select the best data from the training maps and to choose the correct parameter to locate the sources, which can be a time consuming process. This paper presents a new and improved fully automatic delta T mapping technique where a clustering algorithm is used to automatically identify and select the highly correlated events at each grid point whilst the "Minimum Difference" approach is used to determine the source location. This removes the requirement for operator expertise, saving time and preventing human errors. A thorough assessment is conducted to evaluate the performance and the robustness of the new technique. In the initial test, the results showed excellent reduction in running time as well as improved accuracy of locating AE sources, as a result of the automatic selection of the training data. Furthermore, because the process is performed automatically, this is now a very simple and reliable technique due to the prevention of the potential source of error related to manual manipulation.

  4. High-precision source location of the 1978 November 19 gamma-ray burst

    NASA Technical Reports Server (NTRS)

    Cline, T. L.; Desai, U. D.; Teegarden, B. J.; Pizzichini, G.; Evans, W. D.; Klebesadel, R. W.; Laros, J. G.; Barat, C.; Hurley, K.; Niel, M.

    1981-01-01

    The celestial source location of the November 19, 1978, intense gamma ray burst has been determined from data obtained with the interplanetary gamma-ray sensor network by means of long-baseline wave front timing instruments. Each of the instruments was designed for studying events with observable spectra of approximately greater than 100 keV, and each provides accurate event profile timing in the several millisecond range. The data analysis includes the following: the triangulated region is centered at (gamma, delta) 1950 = (1h16m32s, -28 deg 53 arcmin), at -84 deg galactic latitude, where the star density is very low and the obscuration negligible. The gamma-ray burst source region, consistent with that of a highly polarized radio source described by Hjellming and Ewald (1981), may assist in the source modeling and may facilitate the understanding of the source process. A marginally identifiable X-ray source was also found by an Einstein Observatory investigation. It is concluded that the burst contains redshifted positron annihilation and nuclear first-excited iron lines, which is consistent with a neutron star origin.

  5. Examining ERP correlates of recognition memory: Evidence of accurate source recognition without recollection

    PubMed Central

    Addante, Richard, J.; Ranganath, Charan; Yonelinas, Andrew, P.

    2012-01-01

    Recollection is typically associated with high recognition confidence and accurate source memory. However, subjects sometimes make accurate source memory judgments even for items that are not confidently recognized, and it is not known whether these responses are based on recollection or some other memory process. In the current study, we measured event related potentials (ERPs) while subjects made item and source memory confidence judgments in order to determine whether recollection supported accurate source recognition responses for items that were not confidently recognized. In line with previous studies, we found that recognition memory was associated with two ERP effects: an early on-setting FN400 effect, and a later parietal old-new effect [Late Positive Component (LPC)], which have been associated with familiarity and recollection, respectively. The FN400 increased gradually with item recognition confidence, whereas the LPC was only observed for highly confident recognition responses. The LPC was also related to source accuracy, but only for items that had received a high confidence item recognition response; accurate source judgments to items that were less confidently recognized did not exhibit the typical ERP correlate of recollection or familiarity, but rather showed a late, broadly distributed negative ERP difference. The results indicate that accurate source judgments of episodic context can occur even when recollection fails. PMID:22548808

  6. Distributed fiber sensing system with wide frequency response and accurate location

    NASA Astrophysics Data System (ADS)

    Shi, Yi; Feng, Hao; Zeng, Zhoumo

    2016-02-01

    A distributed fiber sensing system merging Mach-Zehnder interferometer and phase-sensitive optical time domain reflectometer (Φ-OTDR) is demonstrated for vibration measurement, which requires wide frequency response and accurate location. Two narrow line-width lasers with delicately different wavelengths are used to constitute the interferometer and reflectometer respectively. A narrow band Fiber Bragg Grating is responsible for separating the two wavelengths. In addition, heterodyne detection is applied to maintain the signal to noise rate of the locating signal. Experiment results show that the novel system has a wide frequency from 1 Hz to 50 MHz, limited by the sample frequency of data acquisition card, and a spatial resolution of 20 m, according to 200 ns pulse width, along 2.5 km fiber link.

  7. Lithospheric Models of the Middle East to Improve Seismic Source Parameter Determination/Event Location Accuracy

    DTIC Science & Technology

    2012-09-01

    State Award Nos. DE-AC52-07NA27344/24.2.3.2 and DOS_SIAA-11-AVC/NMA-1 ABSTRACT The Middle East is a tectonically complex and seismically...active region. The ability to accurately locate earthquakes and other seismic events in this region is complicated by tectonics , the uneven...and seismic source parameters show that this activity comes from tectonic events. This work is informed by continuous or event-based regional

  8. Development of an accurate transmission line fault locator using the global positioning system satellites

    NASA Technical Reports Server (NTRS)

    Lee, Harry

    1994-01-01

    A highly accurate transmission line fault locator based on the traveling-wave principle was developed and successfully operated within B.C. Hydro. A transmission line fault produces a fast-risetime traveling wave at the fault point which propagates along the transmission line. This fault locator system consists of traveling wave detectors located at key substations which detect and time tag the leading edge of the fault-generated traveling wave as if passes through. A master station gathers the time-tagged information from the remote detectors and determines the location of the fault. Precise time is a key element to the success of this system. This fault locator system derives its timing from the Global Positioning System (GPS) satellites. System tests confirmed the accuracy of locating faults to within the design objective of +/-300 meters.

  9. A robust recognition and accurate locating method for circular coded diagonal target

    NASA Astrophysics Data System (ADS)

    Bao, Yunna; Shang, Yang; Sun, Xiaoliang; Zhou, Jiexin

    2017-10-01

    As a category of special control points which can be automatically identified, artificial coded targets have been widely developed in the field of computer vision, photogrammetry, augmented reality, etc. In this paper, a new circular coded target designed by RockeTech technology Corp. Ltd is analyzed and studied, which is called circular coded diagonal target (CCDT). A novel detection and recognition method with good robustness is proposed in the paper, and implemented on Visual Studio. In this algorithm, firstly, the ellipse features of the center circle are used for rough positioning. Then, according to the characteristics of the center diagonal target, a circular frequency filter is designed to choose the correct center circle and eliminates non-target noise. The precise positioning of the coded target is done by the correlation coefficient fitting extreme value method. Finally, the coded target recognition is achieved by decoding the binary sequence in the outer ring of the extracted target. To test the proposed algorithm, this paper has carried out simulation experiments and real experiments. The results show that the CCDT recognition and accurate locating method proposed in this paper can robustly recognize and accurately locate the targets in complex and noisy background.

  10. Location identification for indoor instantaneous point contaminant source by probability-based inverse Computational Fluid Dynamics modeling.

    PubMed

    Liu, X; Zhai, Z

    2008-02-01

    Indoor pollutions jeopardize human health and welfare and may even cause serious morbidity and mortality under extreme conditions. To effectively control and improve indoor environment quality requires immediate interpretation of pollutant sensor readings and accurate identification of indoor pollution history and source characteristics (e.g. source location and release time). This procedure is complicated by non-uniform and dynamic contaminant indoor dispersion behaviors as well as diverse sensor network distributions. This paper introduces a probability concept based inverse modeling method that is able to identify the source location for an instantaneous point source placed in an enclosed environment with known source release time. The study presents the mathematical models that address three different sensing scenarios: sensors without concentration readings, sensors with spatial concentration readings, and sensors with temporal concentration readings. The paper demonstrates the inverse modeling method and algorithm with two case studies: air pollution in an office space and in an aircraft cabin. The predictions were successfully verified against the forward simulation settings, indicating good capability of the method in finding indoor pollutant sources. The research lays a solid ground for further study of the method for more complicated indoor contamination problems. The method developed can help track indoor contaminant source location with limited sensor outputs. This will ensure an effective and prompt execution of building control strategies and thus achieve a healthy and safe indoor environment. The method can also assist the design of optimal sensor networks.

  11. Accurate relative location estimates for the North Korean nuclear tests using empirical slowness corrections

    NASA Astrophysics Data System (ADS)

    Gibbons, S. J.; Pabian, F.; Näsholm, S. P.; Kværna, T.; Mykkeltveit, S.

    2017-01-01

    Declared North Korean nuclear tests in 2006, 2009, 2013 and 2016 were observed seismically at regional and teleseismic distances. Waveform similarity allows the events to be located relatively with far greater accuracy than the absolute locations can be determined from seismic data alone. There is now significant redundancy in the data given the large number of regional and teleseismic stations that have recorded multiple events, and relative location estimates can be confirmed independently by performing calculations on many mutually exclusive sets of measurements. Using a 1-D global velocity model, the distances between the events estimated using teleseismic P phases are found to be approximately 25 per cent shorter than the distances between events estimated using regional Pn phases. The 2009, 2013 and 2016 events all take place within 1 km of each other and the discrepancy between the regional and teleseismic relative location estimates is no more than about 150 m. The discrepancy is much more significant when estimating the location of the more distant 2006 event relative to the later explosions with regional and teleseismic estimates varying by many hundreds of metres. The relative location of the 2006 event is challenging given the smaller number of observing stations, the lower signal-to-noise ratio and significant waveform dissimilarity at some regional stations. The 2006 event is however highly significant in constraining the absolute locations in the terrain at the Punggye-ri test-site in relation to observed surface infrastructure. For each seismic arrival used to estimate the relative locations, we define a slowness scaling factor which multiplies the gradient of seismic traveltime versus distance, evaluated at the source, relative to the applied 1-D velocity model. A procedure for estimating correction terms which reduce the double-difference time residual vector norms is presented together with a discussion of the associated uncertainty. The modified

  12. Accurate Vehicle Location System Using RFID, an Internet of Things Approach.

    PubMed

    Prinsloo, Jaco; Malekian, Reza

    2016-06-04

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved.

  13. Accurate Vehicle Location System Using RFID, an Internet of Things Approach

    PubMed Central

    Prinsloo, Jaco; Malekian, Reza

    2016-01-01

    Modern infrastructure, such as dense urban areas and underground tunnels, can effectively block all GPS signals, which implies that effective position triangulation will not be achieved. The main problem that is addressed in this project is the design and implementation of an accurate vehicle location system using radio-frequency identification (RFID) technology in combination with GPS and the Global system for Mobile communication (GSM) technology, in order to provide a solution to the limitation discussed above. In essence, autonomous vehicle tracking will be facilitated with the use of RFID technology where GPS signals are non-existent. The design of the system and the results are reflected in this paper. An extensive literature study was done on the field known as the Internet of Things, as well as various topics that covered the integration of independent technology in order to address a specific challenge. The proposed system is then designed and implemented. An RFID transponder was successfully designed and a read range of approximately 31 cm was obtained in the low frequency communication range (125 kHz to 134 kHz). The proposed system was designed, implemented, and field tested and it was found that a vehicle could be accurately located and tracked. It is also found that the antenna size of both the RFID reader unit and RFID transponder plays a critical role in the maximum communication range that can be achieved. PMID:27271638

  14. Locating an atmospheric contamination source using slow manifolds

    NASA Astrophysics Data System (ADS)

    Tang, Wenbo; Haller, George; Baik, Jong-Jin; Ryu, Young-Hee

    2009-04-01

    Finite-size particle motion in fluids obeys the Maxey-Riley equations, which become singular in the limit of infinitesimally small particle size. Because of this singularity, finding the source of a dispersed set of small particles is a numerically ill-posed problem that leads to exponential blowup. Here we use recent results on the existence of a slow manifold in the Maxey-Riley equations to overcome this difficulty in source inversion. Specifically, we locate the source of particles by projecting their dispersed positions on a time-varying slow manifold, and by advecting them on the manifold in backward time. We use this technique to locate the source of a hypothetical anthrax release in an unsteady three-dimensional atmospheric wind field in an urban street canyon.

  15. Detection, Source Location, and Analysis of Volcano Infrasound

    NASA Astrophysics Data System (ADS)

    McKee, Kathleen F.

    The study of volcano infrasound focuses on low frequency sound from volcanoes, how volcanic processes produce it, and the path it travels from the source to our receivers. In this dissertation we focus on detecting, locating, and analyzing infrasound from a number of different volcanoes using a variety of analysis techniques. These works will help inform future volcano monitoring using infrasound with respect to infrasonic source location, signal characterization, volatile flux estimation, and back-azimuth to source determination. Source location is an important component of the study of volcano infrasound and in its application to volcano monitoring. Semblance is a forward grid search technique and common source location method in infrasound studies as well as seismology. We evaluated the effectiveness of semblance in the presence of significant topographic features for explosions of Sakurajima Volcano, Japan, while taking into account temperature and wind variations. We show that topographic obstacles at Sakurajima cause a semblance source location offset of 360-420 m to the northeast of the actual source location. In addition, we found despite the consistent offset in source location semblance can still be a useful tool for determining periods of volcanic activity. Infrasonic signal characterization follows signal detection and source location in volcano monitoring in that it informs us of the type of volcanic activity detected. In large volcanic eruptions the lowermost portion of the eruption column is momentum-driven and termed the volcanic jet or gas-thrust zone. This turbulent fluid-flow perturbs the atmosphere and produces a sound similar to that of jet and rocket engines, known as jet noise. We deployed an array of infrasound sensors near an accessible, less hazardous, fumarolic jet at Aso Volcano, Japan as an analogue to large, violent volcanic eruption jets. We recorded volcanic jet noise at 57.6° from vertical, a recording angle not normally feasible

  16. Acoustic Emission Source Location Using a Distributed Feedback Fiber Laser Rosette

    PubMed Central

    Huang, Wenzhu; Zhang, Wentao; Li, Fang

    2013-01-01

    This paper proposes an approach for acoustic emission (AE) source localization in a large marble stone using distributed feedback (DFB) fiber lasers. The aim of this study is to detect damage in structures such as those found in civil applications. The directional sensitivity of DFB fiber laser is investigated by calculating location coefficient using a method of digital signal analysis. In this, autocorrelation is used to extract the location coefficient from the periodic AE signal and wavelet packet energy is calculated to get the location coefficient of a burst AE source. Normalization is processed to eliminate the influence of distance and intensity of AE source. Then a new location algorithm based on the location coefficient is presented and tested to determine the location of AE source using a Delta (Δ) DFB fiber laser rosette configuration. The advantage of the proposed algorithm over the traditional methods based on fiber Bragg Grating (FBG) include the capability of: having higher strain resolution for AE detection and taking into account two different types of AE source for location. PMID:24141266

  17. Accurate modeling and inversion of electrical resistivity data in the presence of metallic infrastructure with known location and dimension

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johnson, Timothy C.; Wellman, Dawn M.

    2015-06-26

    Electrical resistivity tomography (ERT) has been widely used in environmental applications to study processes associated with subsurface contaminants and contaminant remediation. Anthropogenic alterations in subsurface electrical conductivity associated with contamination often originate from highly industrialized areas with significant amounts of buried metallic infrastructure. The deleterious influence of such infrastructure on imaging results generally limits the utility of ERT where it might otherwise prove useful for subsurface investigation and monitoring. In this manuscript we present a method of accurately modeling the effects of buried conductive infrastructure within the forward modeling algorithm, thereby removing them from the inversion results. The method ismore » implemented in parallel using immersed interface boundary conditions, whereby the global solution is reconstructed from a series of well-conditioned partial solutions. Forward modeling accuracy is demonstrated by comparison with analytic solutions. Synthetic imaging examples are used to investigate imaging capabilities within a subsurface containing electrically conductive buried tanks, transfer piping, and well casing, using both well casings and vertical electrode arrays as current sources and potential measurement electrodes. Results show that, although accurate infrastructure modeling removes the dominating influence of buried metallic features, the presence of metallic infrastructure degrades imaging resolution compared to standard ERT imaging. However, accurate imaging results may be obtained if electrodes are appropriately located.« less

  18. Preserving Source Location Privacy for Energy Harvesting WSNs.

    PubMed

    Huang, Changqin; Ma, Ming; Liu, Yuxin; Liu, Anfeng

    2017-03-30

    Fog (From cOre to edGe) computing employs a huge number of wireless embedded devices to enable end users with anywhere-anytime-to-anything connectivity. Due to their operating nature, wireless sensor nodes often work unattended, and hence are exposed to a variety of attacks. Preserving source-location privacy plays a key role in some wireless sensor network (WSN) applications. In this paper, a redundancy branch convergence-based preserved source location privacy scheme (RBCPSLP) is proposed for energy harvesting sensor networks, with the following advantages: numerous routing branches are created in non-hotspot areas with abundant energy, and those routing branches can merge into a few routing paths before they reach the hotspot areas. The generation time, the duration of routing, and the number of routing branches are then decided independently based on the amount of energy obtained, so as to maximize network energy utilization, greatly enhance privacy protection, and provide long network lifetimes. Theoretical analysis and experimental results show that the RBCPSLP scheme allows a several-fold improvement of the network energy utilization as well as the source location privacy preservation, while maximizing network lifetimes.

  19. Preserving Source Location Privacy for Energy Harvesting WSNs

    PubMed Central

    Huang, Changqin; Ma, Ming; Liu, Yuxin; Liu, Anfeng

    2017-01-01

    Fog (From cOre to edGe) computing employs a huge number of wireless embedded devices to enable end users with anywhere-anytime-to-anything connectivity. Due to their operating nature, wireless sensor nodes often work unattended, and hence are exposed to a variety of attacks. Preserving source-location privacy plays a key role in some wireless sensor network (WSN) applications. In this paper, a redundancy branch convergence-based preserved source location privacy scheme (RBCPSLP) is proposed for energy harvesting sensor networks, with the following advantages: numerous routing branches are created in non-hotspot areas with abundant energy, and those routing branches can merge into a few routing paths before they reach the hotspot areas. The generation time, the duration of routing, and the number of routing branches are then decided independently based on the amount of energy obtained, so as to maximize network energy utilization, greatly enhance privacy protection, and provide long network lifetimes. Theoretical analysis and experimental results show that the RBCPSLP scheme allows a several-fold improvement of the network energy utilization as well as the source location privacy preservation, while maximizing network lifetimes. PMID:28358341

  20. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small business...

  1. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 1 2012-10-01 2012-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small business...

  2. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 1 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small business...

  3. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 1 2014-10-01 2014-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small business...

  4. 48 CFR 19.202-2 - Locating small business sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 1 2013-10-01 2013-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 19.202-2 Locating small business sources. The contracting officer must, to the extent practicable, encourage maximum participation by small business...

  5. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS acquisitions...

  6. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 4 2013-10-01 2013-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS acquisitions...

  7. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 4 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS acquisitions...

  8. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 7 2014-10-01 2014-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations to...

  9. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 4 2012-10-01 2012-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS acquisitions...

  10. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 48 Federal Acquisition Regulations System 7 2013-10-01 2012-10-01 true Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations to...

  11. 48 CFR 319.202-2 - Locating small business sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 4 2014-10-01 2014-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 319.202-2 Locating small business sources. (a) OPDIVs shall foster, to the extent practicable, maximum participation by small businesses in HHS acquisitions...

  12. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations to...

  13. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 48 Federal Acquisition Regulations System 7 2011-10-01 2011-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations to...

  14. 48 CFR 2919.202-2 - Locating small business sources.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 48 Federal Acquisition Regulations System 7 2012-10-01 2012-10-01 false Locating small business... SOCIOECONOMIC PROGRAMS SMALL BUSINESS AND SMALL DISADVANTAGED BUSINESS CONCERNS Policies 2919.202-2 Locating small business sources. Any procurement conducted on an unrestricted basis will include solicitations to...

  15. Locating multiple diffusion sources in time varying networks from sparse observations.

    PubMed

    Hu, Zhao-Long; Shen, Zhesi; Cao, Shinan; Podobnik, Boris; Yang, Huijie; Wang, Wen-Xu; Lai, Ying-Cheng

    2018-02-08

    Data based source localization in complex networks has a broad range of applications. Despite recent progress, locating multiple diffusion sources in time varying networks remains to be an outstanding problem. Bridging structural observability and sparse signal reconstruction theories, we develop a general framework to locate diffusion sources in time varying networks based solely on sparse data from a small set of messenger nodes. A general finding is that large degree nodes produce more valuable information than small degree nodes, a result that contrasts that for static networks. Choosing large degree nodes as the messengers, we find that sparse observations from a few such nodes are often sufficient for any number of diffusion sources to be located for a variety of model and empirical networks. Counterintuitively, sources in more rapidly varying networks can be identified more readily with fewer required messenger nodes.

  16. Accurate Damage Location in Complex Composite Structures and Industrial Environments using Acoustic Emission

    NASA Astrophysics Data System (ADS)

    Eaton, M.; Pearson, M.; Lee, W.; Pullin, R.

    2015-07-01

    The ability to accurately locate damage in any given structure is a highly desirable attribute for an effective structural health monitoring system and could help to reduce operating costs and improve safety. This becomes a far greater challenge in complex geometries and materials, such as modern composite airframes. The poor translation of promising laboratory based SHM demonstrators to industrial environments forms a barrier to commercial up take of technology. The acoustic emission (AE) technique is a passive NDT method that detects elastic stress waves released by the growth of damage. It offers very sensitive damage detection, using a sparse array of sensors to detect and globally locate damage within a structure. However its application to complex structures commonly yields poor accuracy due to anisotropic wave propagation and the interruption of wave propagation by structural features such as holes and thickness changes. This work adopts an empirical mapping technique for AE location, known as Delta T Mapping, which uses experimental training data to account for such structural complexities. The technique is applied to a complex geometry composite aerospace structure undergoing certification testing. The component consists of a carbon fibre composite tube with varying wall thickness and multiple holes, that was loaded under bending. The damage location was validated using X-ray CT scanning and the Delta T Mapping technique was shown to improve location accuracy when compared with commercial algorithms. The onset and progression of damage were monitored throughout the test and used to inform future design iterations.

  17. Toward a probabilistic acoustic emission source location algorithm: A Bayesian approach

    NASA Astrophysics Data System (ADS)

    Schumacher, Thomas; Straub, Daniel; Higgins, Christopher

    2012-09-01

    Acoustic emissions (AE) are stress waves initiated by sudden strain releases within a solid body. These can be caused by internal mechanisms such as crack opening or propagation, crushing, or rubbing of crack surfaces. One application for the AE technique in the field of Structural Engineering is Structural Health Monitoring (SHM). With piezo-electric sensors mounted to the surface of the structure, stress waves can be detected, recorded, and stored for later analysis. An important step in quantitative AE analysis is the estimation of the stress wave source locations. Commonly, source location results are presented in a rather deterministic manner as spatial and temporal points, excluding information about uncertainties and errors. Due to variability in the material properties and uncertainty in the mathematical model, measures of uncertainty are needed beyond best-fit point solutions for source locations. This paper introduces a novel holistic framework for the development of a probabilistic source location algorithm. Bayesian analysis methods with Markov Chain Monte Carlo (MCMC) simulation are employed where all source location parameters are described with posterior probability density functions (PDFs). The proposed methodology is applied to an example employing data collected from a realistic section of a reinforced concrete bridge column. The selected approach is general and has the advantage that it can be extended and refined efficiently. Results are discussed and future steps to improve the algorithm are suggested.

  18. Accurate characterisation of hole size and location by projected fringe profilometry

    NASA Astrophysics Data System (ADS)

    Wu, Yuxiang; Dantanarayana, Harshana G.; Yue, Huimin; Huntley, Jonathan M.

    2018-06-01

    The ability to accurately estimate the location and geometry of holes is often required in the field of quality control and automated assembly. Projected fringe profilometry is a potentially attractive technique on account of being non-contacting, of lower cost, and orders of magnitude faster than the traditional coordinate measuring machine. However, we demonstrate in this paper that fringe projection is susceptible to significant (hundreds of µm) measurement artefacts in the neighbourhood of hole edges, which give rise to errors of a similar magnitude in the estimated hole geometry. A mechanism for the phenomenon is identified based on the finite size of the imaging system’s point spread function and the resulting bias produced near to sample discontinuities in geometry and reflectivity. A mathematical model is proposed, from which a post-processing compensation algorithm is developed to suppress such errors around the holes. The algorithm includes a robust and accurate sub-pixel edge detection method based on a Fourier descriptor of the hole contour. The proposed algorithm was found to reduce significantly the measurement artefacts near the hole edges. As a result, the errors in estimated hole radius were reduced by up to one order of magnitude, to a few tens of µm for hole radii in the range 2–15 mm, compared to those from the uncompensated measurements.

  19. Acoustical Emission Source Location in Thin Rods Through Wavelet Detail Crosscorrelation

    DTIC Science & Technology

    1998-03-01

    NAVAL POSTGRADUATE SCHOOL Monterey, California THESIS ACOUSTICAL EMISSION SOURCE LOCATION IN THIN RODS THROUGH WAVELET DETAIL CROSSCORRELATION...ACOUSTICAL EMISSION SOURCE LOCATION IN THIN RODS THROUGH WAVELET DETAIL CROSSCORRELATION 6. AUTHOR(S) Jerauld, Joseph G. 5. FUNDING NUMBERS Grant...frequency characteristics of Wavelet Analysis. Software implementation now enables the exploration of the Wavelet Transform to identify the time of

  20. Lower Learning Difficulty and Fluoroscopy Reduction of Transforaminal Percutaneous Endoscopic Lumbar Discectomy with an Accurate Preoperative Location Method.

    PubMed

    Fan, Guoxin; Gu, Xin; Liu, Yifan; Wu, Xinbo; Zhang, Hailong; Gu, Guangfei; Guan, Xiaofei; He, Shisheng

    2016-01-01

    Transforaminal percutaneous endoscopic lumbar discectomy (tPELD) poses great challenges for junior surgeons. Beginners often require repeated attempts using fluoroscopy causing more punctures, which may significantly undermine their confidence and increase the radiation exposure to medical staff and patients. Moreover, the impact of an accurate location on the learning curve of tPELD has not been defined. The study aimed to investigate the impact of an accurate preoperative location method on learning difficulty and fluoroscopy time of tPELD. Retrospective evaluation. Patients receiving tPELD by one surgeon with a novel accurate preoperative location method were regarded as Group A, and those receiving tPELD by another surgeon with a conventional fluoroscopy method were regarded as Group B. From January 2012 to August 2014, we retrospectively reviewed the first 80 tPELD cases conducted by 2 junior surgeons. The operation time, fluoroscopy times, preoperative location time, and puncture-channel time were thoroughly analyzed. The operation time of the first 20 patients were 99.75 ± 10.38 minutes in Group A and 115.7 ± 16.46 minutes in Group B, while the operation time of all 80 patients was 88.36 ± 11.56 minutes in Group A and 98.26 ± 14.90 minutes in Group B. Significant differences were detected in operation time between the 2 groups, both for the first 20 patients and total 80 patients (P < 0.05). The fluoroscopy times were 26.78 ± 4.17 in Group A and 33.98 ± 2.69 in Group B (P < 0.001). The preoperative location time was 3.43 ± 0.61 minutes in Group A and 5.59 ± 1.46 minutes in Group B (P < 0.001). The puncture-channel time was 27.20 ± 4.49 minutes in Group A and 34.64 ± 8.35 minutes in Group B (P < 0.001). There was a moderate correlation between preoperative location time and puncture-channel time (r = 0.408, P < 0.001), and a moderate correlation between preoperative location time and fluoroscopy times (r = 0.441, P < 0.001). Mild correlations were

  1. Poynting-vector based method for determining the bearing and location of electromagnetic sources

    DOEpatents

    Simons, David J.; Carrigan, Charles R.; Harben, Philip E.; Kirkendall, Barry A.; Schultz, Craig A.

    2008-10-21

    A method and apparatus is utilized to determine the bearing and/or location of sources, such as, alternating current (A.C.) generators and loads, power lines, transformers and/or radio-frequency (RF) transmitters, emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. When both a source and field sensors (electric and magnetic) are static, a bearing to the electromagnetic source can be obtained. If a single set of electric (E) and magnetic (B) sensors are in motion, multiple measurements permit location of the source. The method can be extended to networks of sensors allowing determination of the location of both stationary and moving sources.

  2. A new protocol to accurately determine microtubule lattice seam location

    DOE PAGES

    Zhang, Rui; Nogales, Eva

    2015-09-28

    Microtubules (MTs) are cylindrical polymers of αβ-tubulin that display pseudo-helical symmetry due to the presence of a lattice seam of heterologous lateral contacts. The structural similarity between α- and β-tubulin makes it difficult to computationally distinguish them in the noisy cryo-EM images, unless a marker protein for the tubulin dimer, such as kinesin motor domain, is present. We have developed a new data processing protocol that can accurately determine αβ-tubulin register and seam location for MT segments. Our strategy can handle difficult situations, where the marker protein is relatively small or the decoration of marker protein is sparse. Using thismore » new seam-search protocol, combined with movie processing for data from a direct electron detection camera, we were able to determine the cryo-EM structures of MT at 3.5. Å resolution in different functional states. The successful distinction of α- and β-tubulin allowed us to visualize the nucleotide state at the E-site and the configuration of lateral contacts at the seam.« less

  3. Location of long-period events below Kilauea Volcano using seismic amplitudes and accurate relative relocation

    USGS Publications Warehouse

    Battaglia, J.; Got, J.-L.; Okubo, P.

    2003-01-01

    We present methods for improving the location of long-period (LP) events, deep and shallow, recorded below Kilauea Volcano by the permanent seismic network. LP events might be of particular interest to understanding eruptive processes as their source mechanism is assumed to directly involve fluid transport. However, it is usually difficult or impossible to locate their source using traditional arrival time methods because of emergent wave arrivals. At Kilauea, similar LP waveform signatures suggest the existence of LP multiplets. The waveform similarity suggests spatially close sources, while catalog solutions using arrival time estimates are widely scattered beneath Kilauea's summit caldera. In order to improve estimates of absolute LP location, we use the distribution of seismic amplitudes corrected for station site effects. The decay of the amplitude as a function of hypocentral distance is used for inferring LP location. In a second stage, we use the similarity of the events to calculate their relative positions. The analysis of the entire LP seismicity recorded between January 1997 and December 1999 suggests that a very large part of the LP event population, both deep and shallow, is generated by a small number of compact sources. Deep events are systematically composed of a weak high-frequency onset followed by a low-frequency wave train. Aligning the low-frequency wave trains does not lead to aligning the onsets indicating the two parts of the signal are dissociated. This observation favors an interpretation in terms of triggering and resonance of a magmatic conduit. Instead of defining fault planes, the precise relocation of similar LP events, based on the alignment of the high-energy low-frequency wave trains, defines limited size volumes. Copyright 2003 by the American Geophysical Union.

  4. Accurate Simulation of Acoustic Emission Sources in Composite Plates

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Gorman, M. R.

    1994-01-01

    Acoustic emission (AE) signals propagate as the extensional and flexural plate modes in thin composite plates and plate-like geometries such as shells, pipes, and tubes. The relative amplitude of the two modes depends on the directionality of the source motion. For source motions with large out-of-plane components such as delaminations or particle impact, the flexural or bending plate mode dominates the AE signal with only a small extensional mode detected. A signal from such a source is well simulated with the standard pencil lead break (Hsu-Neilsen source) on the surface of the plate. For other sources such as matrix cracking or fiber breakage in which the source motion is primarily in-plane, the resulting AE signal has a large extensional mode component with little or no flexural mode observed. Signals from these type sources can also be simulated with pencil lead breaks. However, the lead must be fractured on the edge of the plate to generate an in-plane source motion rather than on the surface of the plate. In many applications such as testing of pressure vessels and piping or aircraft structures, a free edge is either not available or not in a desired location for simulation of in-plane type sources. In this research, a method was developed which allows the simulation of AE signals with a predominant extensional mode component in composite plates requiring access to only the surface of the plate.

  5. Comparison of hybrid receptor models to locate PCB sources in Chicago

    NASA Astrophysics Data System (ADS)

    Hsu, Ying-Kuang; Holsen, Thomas M.; Hopke, Philip K.

    Results of three hybrid receptor models, potential source contribution function (PSCF), concentration weighted trajectory (CWT), and residence time weighted concentration (RTWC), were compared for locating polychlorinated biphenyl (PCB) sources contributing to the atmospheric concentrations in Chicago. Variations of these models, including PSCF using mean and 75% criterion concentrations, joint probability PSCF (JP-PSCF), changes of point filters and grid cell sizes for RTWC, and PSCF using wind trajectories started at different altitudes, are also discussed. Modeling results were relatively consistent between models. However, no single model provided as complete information as was obtained by using all of them. CWT and 75% PSCF appears to be able to distinguish between larger sources and moderate ones. RTWC resolved high potential source areas. RTWC and JP-PSCF pooling data from all sampling sites removed the trailing effect often seen in PSCF modeling. PSCF results using average concentration criteria, appears to identify both moderate and major sources. Each model has advantages and disadvantages. However, used in combination, they provide information that is not available if only one of them is used. For short-range atmospheric transport, PSCF results were consistent when using wind trajectories starting at different heights. Based on the archived PCB data, the modeling results indicate there is a large potential source area between Joliet and Kankakee, IL, and two moderate sources to the northwest and south of Chicago. On the south side of Chicago in the neighborhood of Lake Calumet, several PCB sources were identified. Other unidentified potential source location(s) will require additional upwind/downwind field sampling to verify modeling results.

  6. Probabilistic location estimation of acoustic emission sources in isotropic plates with one sensor

    NASA Astrophysics Data System (ADS)

    Ebrahimkhanlou, Arvin; Salamone, Salvatore

    2017-04-01

    This paper presents a probabilistic acoustic emission (AE) source localization algorithm for isotropic plate structures. The proposed algorithm requires only one sensor and uniformly monitors the entire area of such plates without any blind zones. In addition, it takes a probabilistic approach and quantifies localization uncertainties. The algorithm combines a modal acoustic emission (MAE) and a reflection-based technique to obtain information pertaining to the location of AE sources. To estimate confidence contours for the location of sources, uncertainties are quantified and propagated through the two techniques. The approach was validated using standard pencil lead break (PLB) tests on an Aluminum plate. The results demonstrate that the proposed source localization algorithm successfully estimates confidence contours for the location of AE sources.

  7. Quantification of Methane Source Locations and Emissions in AN Urban Setting

    NASA Astrophysics Data System (ADS)

    Crosson, E.; Richardson, S.; Tan, S. M.; Whetstone, J.; Bova, T.; Prasad, K. R.; Davis, K. J.; Phillips, N. G.; Turnbull, J. C.; Shepson, P. B.; Cambaliza, M. L.

    2011-12-01

    The regulation of methane emissions from urban sources such as landfills and waste-water treatment facilities is currently a highly debated topic in the US and in Europe. This interest is fueled, in part, by recent measurements indicating that urban emissions are a significant source of Methane (CH4) and in fact may be substantially higher than current inventory estimates(1). As a result, developing methods for locating and quantifying emissions from urban methane sources is of great interest to industries such as landfill and wastewater treatment facility owners, watchdog groups, and the governmental agencies seeking to evaluate or enforce regulations. In an attempt to identify major methane source locations and emissions in Boston, Indianapolis, and the Bay Area, systematic measurements of CH4 concentrations and meteorology data were made at street level using a vehicle mounted cavity ringdown analyzer. A number of discrete sources were detected at concentration levels in excess of 15 times background levels. Using Gaussian plume models as well as tomographic techniques, methane source locations and emission rates will be presented. In addition, flux chamber measurements of discrete sources such as those found in natural gas leaks will also be presented. (1) Wunch, D., P.O. Wennberg, G.C. Toon, G. Keppel-Aleks, and Y.G. Yavin, Emissions of Greenhouse Gases from a North American Megacity, Geophysical Research Letters, Vol. 36, L15810, doi:10.1029/2009GL)39825, 2009.

  8. Awakening the BALROG: BAyesian Location Reconstruction Of GRBs

    NASA Astrophysics Data System (ADS)

    Burgess, J. Michael; Yu, Hoi-Fung; Greiner, Jochen; Mortlock, Daniel J.

    2018-05-01

    The accurate spatial location of gamma-ray bursts (GRBs) is crucial for both accurately characterizing their spectra and follow-up observations by other instruments. The Fermi Gamma-ray Burst Monitor (GBM) has the largest field of view for detecting GRBs as it views the entire unocculted sky, but as a non-imaging instrument it relies on the relative count rates observed in each of its 14 detectors to localize transients. Improving its ability to accurately locate GRBs and other transients is vital to the paradigm of multimessenger astronomy, including the electromagnetic follow-up of gravitational wave signals. Here we present the BAyesian Location Reconstruction Of GRBs (BALROG) method for localizing and characterizing GBM transients. Our approach eliminates the systematics of previous approaches by simultaneously fitting for the location and spectrum of a source. It also correctly incorporates the uncertainties in the location of a transient into the spectral parameters and produces reliable positional uncertainties for both well-localized sources and those for which the GBM data cannot effectively constrain the position. While computationally expensive, BALROG can be implemented to enable quick follow-up of all GBM transient signals. Also, we identify possible response problems that require attention and caution when using standard, public GBM detector response matrices. Finally, we examine the effects of including the uncertainty in location on the spectral parameters of GRB 080916C. We find that spectral parameters change and no extra components are required when these effects are included in contrast to when we use a fixed location. This finding has the potential to alter both the GRB spectral catalogues and the reported spectral composition of some well-known GRBs.

  9. Surface Properties Associated With Dust Storm Plume's Point-Source Locations In The Border Region Of The US And Mexico

    NASA Astrophysics Data System (ADS)

    Bleiweiss, M. P.; DuBois, D. W.; Flores, M. I.

    2013-12-01

    Dust storms in the border region of the Southwest US and Northern Mexico are a serious problem for air quality (PM10 exceedances), health (Valley Fever is pandemic in the region) and transportation (road closures and deadly traffic accidents). In order to better understand the phenomena, we are attempting to identify critical characteristics of dust storm sources so that, possibly, one can perform more accurate predictions of events and, thus, mitigate some of the deleterious effects. Besides the emission mechanisms for dust storm production that are tied to atmospheric dynamics, one must know those locations whose source characteristics can be tied to dust production and, therefore, identify locations where a dust storm is eminent under favorable atmospheric dynamics. During the past 13 years, we have observed, on satellite imagery, more than 500 dust events in the region and are in the process of identifying the source regions for the dust plumes that make up an event. Where satellite imagery exists with high spatial resolution (less than or equal to 250m), dust 'plumes' appear to be made up of individual and merged plumes that are emitted from a 'point source' (smaller than the resolution of the imagery). In particular, we have observed events from the ASTER sensor whose spatial resolution is 15m as well as Landsat whose spatial resolution is 30m. Tying these source locations to surface properties such as NDVI, albedo, and soil properties (percent sand, silt, clay, and gravel; soil moisture; etc.) will identify regions with enhanced capability to produce a dust storm. This, along with atmospheric dynamics, will allow the forecast of dust events. The analysis of 10 events from the period 2004-2013, for which we have identified 1124 individual plumes, will be presented.

  10. PULSED ION SOURCE

    DOEpatents

    Martina, E.F.

    1958-10-14

    An improved pulsed ion source of the type where the gas to be ionized is released within the source by momentary heating of an electrode occluded with the gas is presented. The other details of the ion source construction include an electron emitting filament and a positive reference grid, between which an electron discharge is set up, and electrode means for withdrawing the ions from the source. Due to the location of the gas source behind the electrode discharge region, and the positioning of the vacuum exhaust system on the opposite side of the discharge, the released gas is drawn into the electron discharge and ionized in accurately controlled amounts. Consequently, the output pulses of the ion source may be accurately controlled.

  11. Locating Microseism Sources Using Spurious Arrivals in Intercontinental Noise Correlations

    NASA Astrophysics Data System (ADS)

    Retailleau, Lise; Boué, Pierre; Stehly, Laurent; Campillo, Michel

    2017-10-01

    The accuracy of Green's functions retrieved from seismic noise correlations in the microseism frequency band is limited by the uneven distribution of microseism sources at the surface of the Earth. As a result, correlation functions are often biased as compared to the expected Green's functions, and they can include spurious arrivals. These spurious arrivals are seismic arrivals that are visible on the correlation and do not belong to the theoretical impulse response. In this article, we propose to use Rayleigh wave spurious arrivals detected on correlation functions computed between European and United States seismic stations to locate microseism sources in the Atlantic Ocean. We perform a slant stack on a time distance gather of correlations obtained from an array of stations that comprises a regional deployment and a distant station. The arrival times and the apparent slowness of the spurious arrivals lead to the location of their source, which is obtained through a grid search procedure. We discuss improvements in the location through this methodology as compared to classical back projection of microseism energy. This method is interesting because it only requires an array and a distant station on each side of an ocean, conditions that can be met relatively easily.

  12. Anatomically constrained dipole adjustment (ANACONDA) for accurate MEG/EEG focal source localizations

    NASA Astrophysics Data System (ADS)

    Im, Chang-Hwan; Jung, Hyun-Kyo; Fujimaki, Norio

    2005-10-01

    This paper proposes an alternative approach to enhance localization accuracy of MEG and EEG focal sources. The proposed approach assumes anatomically constrained spatio-temporal dipoles, initial positions of which are estimated from local peak positions of distributed sources obtained from a pre-execution of distributed source reconstruction. The positions of the dipoles are then adjusted on the cortical surface using a novel updating scheme named cortical surface scanning. The proposed approach has many advantages over the conventional ones: (1) as the cortical surface scanning algorithm uses spatio-temporal dipoles, it is robust with respect to noise; (2) it requires no a priori information on the numbers and initial locations of the activations; (3) as the locations of dipoles are restricted only on a tessellated cortical surface, it is physiologically more plausible than the conventional ECD model. To verify the proposed approach, it was applied to several realistic MEG/EEG simulations and practical experiments. From the several case studies, it is concluded that the anatomically constrained dipole adjustment (ANACONDA) approach will be a very promising technique to enhance accuracy of focal source localization which is essential in many clinical and neurological applications of MEG and EEG.

  13. Cartilage immunoprivilege depends on donor source and lesion location.

    PubMed

    Arzi, B; DuRaine, G D; Lee, C A; Huey, D J; Borjesson, D L; Murphy, B G; Hu, J C Y; Baumgarth, N; Athanasiou, K A

    2015-09-01

    The ability to repair damaged cartilage is a major goal of musculoskeletal tissue engineering. Allogeneic (same species, different individual) or xenogeneic (different species) sources can provide an attractive source of chondrocytes for cartilage tissue engineering, since autologous (same individual) cells are scarce. Immune rejection of non-autologous hyaline articular cartilage has seldom been considered due to the popular notion of "cartilage immunoprivilege". The objective of this study was to determine the suitability of allogeneic and xenogeneic engineered neocartilage tissue for cartilage repair. To address this, scaffold-free tissue engineered articular cartilage of syngeneic (same genetic background), allogeneic, and xenogeneic origin were implanted into two different locations of the rabbit knee (n=3 per group/location). Xenogeneic engineered cartilage and control xenogeneic chondral explants provoked profound innate inflammatory and adaptive cellular responses, regardless of transplant location. Cytological quantification of immune cells showed that, while allogeneic neocartilage elicited an immune response in the patella, negligible responses were observed when implanted into the trochlea; instead the responses were comparable to microfracture-treated empty defect controls. Allogeneic neocartilage survived within the trochlea implant site and demonstrated graft integration into the underlying bone. In conclusion, the knee joint cartilage does not represent an immune privileged site, strongly rejecting xenogeneic but not allogeneic chondrocytes in a location-dependent fashion. This difference in location-dependent survival of allogeneic tissue may be associated with proximity to the synovium. Through a series of in vivo studies this research demonstrates that articular cartilage is not fully immunoprivileged. In addition, we now show that anatomical location of the defect, even within the same joint compartment, strongly influences the degree of the

  14. Acoustic emission source location in composite structure by Voronoi construction using geodesic curve evolution.

    PubMed

    Gangadharan, R; Prasanna, G; Bhat, M R; Murthy, C R L; Gopalakrishnan, S

    2009-11-01

    Conventional analytical/numerical methods employing triangulation technique are suitable for locating acoustic emission (AE) source in a planar structure without structural discontinuities. But these methods cannot be extended to structures with complicated geometry, and, also, the problem gets compounded if the material of the structure is anisotropic warranting complex analytical velocity models. A geodesic approach using Voronoi construction is proposed in this work to locate the AE source in a composite structure. The approach is based on the fact that the wave takes minimum energy path to travel from the source to any other point in the connected domain. The geodesics are computed on the meshed surface of the structure using graph theory based on Dijkstra's algorithm. By propagating the waves in reverse virtually from these sensors along the geodesic path and by locating the first intersection point of these waves, one can get the AE source location. In this work, the geodesic approach is shown more suitable for a practicable source location solution in a composite structure with arbitrary surface containing finite discontinuities. Experiments have been conducted on composite plate specimens of simple and complex geometry to validate this method.

  15. Determining the sensitivity of the amplitude source location (ASL) method through active seismic sources: An example from Te Maari Volcano, New Zealand

    NASA Astrophysics Data System (ADS)

    Walsh, Braden; Jolly, Arthur; Procter, Jonathan

    2017-04-01

    Using active seismic sources on Tongariro Volcano, New Zealand, the amplitude source location (ASL) method is calibrated and optimized through a series of sensitivity tests. By applying a geologic medium velocity of 1500 m/s and an attenuation value of Q=60 for surface waves along with amplification factors computed from regional earthquakes, the ASL produced location discrepancies larger than 1.0 km horizontally and up to 0.5 km in depth. Through the use of sensitivity tests on input parameters, we show that velocity and attenuation models have moderate to strong influences on the location results, but can be easily constrained. Changes in locations are accommodated through either lateral or depth movements. Station corrections (amplification factors) and station geometry strongly affect the ASL locations laterally, horizontally and in depth. Calibrating the amplification factors through the exploitation of the active seismic source events reduced location errors for the sources by up to 50%.

  16. Locating arbitrarily time-dependent sound sources in three dimensional space in real time.

    PubMed

    Wu, Sean F; Zhu, Na

    2010-08-01

    This paper presents a method for locating arbitrarily time-dependent acoustic sources in a free field in real time by using only four microphones. This method is capable of handling a wide variety of acoustic signals, including broadband, narrowband, impulsive, and continuous sound over the entire audible frequency range, produced by multiple sources in three dimensional (3D) space. Locations of acoustic sources are indicated by the Cartesian coordinates. The underlying principle of this method is a hybrid approach that consists of modeling of acoustic radiation from a point source in a free field, triangulation, and de-noising to enhance the signal to noise ratio (SNR). Numerical simulations are conducted to study the impacts of SNR, microphone spacing, source distance and frequency on spatial resolution and accuracy of source localizations. Based on these results, a simple device that consists of four microphones mounted on three mutually orthogonal axes at an optimal distance, a four-channel signal conditioner, and a camera is fabricated. Experiments are conducted in different environments to assess its effectiveness in locating sources that produce arbitrarily time-dependent acoustic signals, regardless whether a sound source is stationary or moves in space, even toward behind measurement microphones. Practical limitations on this method are discussed.

  17. All-Direction Random Routing for Source-Location Privacy Protecting against Parasitic Sensor Networks.

    PubMed

    Wang, Na; Zeng, Jiwen

    2017-03-17

    Wireless sensor networks are deployed to monitor the surrounding physical environments and they also act as the physical environments of parasitic sensor networks, whose purpose is analyzing the contextual privacy and obtaining valuable information from the original wireless sensor networks. Recently, contextual privacy issues associated with wireless communication in open spaces have not been thoroughly addressed and one of the most important challenges is protecting the source locations of the valuable packages. In this paper, we design an all-direction random routing algorithm (ARR) for source-location protecting against parasitic sensor networks. For each package, the routing process of ARR is divided into three stages, i.e., selecting a proper agent node, delivering the package to the agent node from the source node, and sending it to the final destination from the agent node. In ARR, the agent nodes are randomly chosen in all directions by the source nodes using only local decisions, rather than knowing the whole topology of the networks. ARR can control the distributions of the routing paths in a very flexible way and it can guarantee that the routing paths with the same source and destination are totally different from each other. Therefore, it is extremely difficult for the parasitic sensor nodes to trace the packages back to the source nodes. Simulation results illustrate that ARR perfectly confuses the parasitic nodes and obviously outperforms traditional routing-based schemes in protecting source-location privacy, with a marginal increase in the communication overhead and energy consumption. In addition, ARR also requires much less energy than the cloud-based source-location privacy protection schemes.

  18. All-Direction Random Routing for Source-Location Privacy Protecting against Parasitic Sensor Networks

    PubMed Central

    Wang, Na; Zeng, Jiwen

    2017-01-01

    Wireless sensor networks are deployed to monitor the surrounding physical environments and they also act as the physical environments of parasitic sensor networks, whose purpose is analyzing the contextual privacy and obtaining valuable information from the original wireless sensor networks. Recently, contextual privacy issues associated with wireless communication in open spaces have not been thoroughly addressed and one of the most important challenges is protecting the source locations of the valuable packages. In this paper, we design an all-direction random routing algorithm (ARR) for source-location protecting against parasitic sensor networks. For each package, the routing process of ARR is divided into three stages, i.e., selecting a proper agent node, delivering the package to the agent node from the source node, and sending it to the final destination from the agent node. In ARR, the agent nodes are randomly chosen in all directions by the source nodes using only local decisions, rather than knowing the whole topology of the networks. ARR can control the distributions of the routing paths in a very flexible way and it can guarantee that the routing paths with the same source and destination are totally different from each other. Therefore, it is extremely difficult for the parasitic sensor nodes to trace the packages back to the source nodes. Simulation results illustrate that ARR perfectly confuses the parasitic nodes and obviously outperforms traditional routing-based schemes in protecting source-location privacy, with a marginal increase in the communication overhead and energy consumption. In addition, ARR also requires much less energy than the cloud-based source-location privacy protection schemes. PMID:28304367

  19. Algorithms for System Identification and Source Location.

    NASA Astrophysics Data System (ADS)

    Nehorai, Arye

    This thesis deals with several topics in least squares estimation and applications to source location. It begins with a derivation of a mapping between Wiener theory and Kalman filtering for nonstationary autoregressive moving average (ARMO) processes. Applying time domain analysis, connections are found between time-varying state space realizations and input-output impulse response by matrix fraction description (MFD). Using these connections, the whitening filters are derived by the two approaches, and the Kalman gain is expressed in terms of Wiener theory. Next, fast estimation algorithms are derived in a unified way as special cases of the Conjugate Direction Method. The fast algorithms included are the block Levinson, fast recursive least squares, ladder (or lattice) and fast Cholesky algorithms. The results give a novel derivation and interpretation for all these methods, which are efficient alternatives to available recursive system identification algorithms. Multivariable identification algorithms are usually designed only for left MFD models. In this work, recursive multivariable identification algorithms are derived for right MFD models with diagonal denominator matrices. The algorithms are of prediction error and model reference type. Convergence analysis results obtained by the Ordinary Differential Equation (ODE) method are presented along with simulations. Sources of energy can be located by estimating time differences of arrival (TDOA's) of waves between the receivers. A new method for TDOA estimation is proposed for multiple unknown ARMA sources and additive correlated receiver noise. The method is based on a formula that uses only the receiver cross-spectra and the source poles. Two algorithms are suggested that allow tradeoffs between computational complexity and accuracy. A new time delay model is derived and used to show the applicability of the methods for non -integer TDOA's. Results from simulations illustrate the performance of the

  20. Locating non-volcanic tremor along the San Andreas Fault using a multiple array source imaging technique

    USGS Publications Warehouse

    Ryberg, T.; Haberland, C.H.; Fuis, G.S.; Ellsworth, W.L.; Shelly, D.R.

    2010-01-01

    Non-volcanic tremor (NVT) has been observed at several subduction zones and at the San Andreas Fault (SAF). Tremor locations are commonly derived by cross-correlating envelope-transformed seismic traces in combination with source-scanning techniques. Recently, they have also been located by using relative relocations with master events, that is low-frequency earthquakes that are part of the tremor; locations are derived by conventional traveltime-based methods. Here we present a method to locate the sources of NVT using an imaging approach for multiple array data. The performance of the method is checked with synthetic tests and the relocation of earthquakes. We also applied the method to tremor occurring near Cholame, California. A set of small-aperture arrays (i.e. an array consisting of arrays) installed around Cholame provided the data set for this study. We observed several tremor episodes and located tremor sources in the vicinity of SAF. During individual tremor episodes, we observed a systematic change of source location, indicating rapid migration of the tremor source along SAF. ?? 2010 The Authors Geophysical Journal International ?? 2010 RAS.

  1. On the source location of radiation belt relativistic electrons

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Blake, J. B.

    2000-02-01

    Observations from the High Sensitivity Telescope (HIST) on Polar made around Janurary and May 1998 are used to constrain the source location of outer radiation belt relativistic electrons. Phase space densities calculated as a function of the three adiabatic invariants show positive radial gradients for L<4, suggestive of no source in that region. In particular, the peak intensity near L=3 of a large enhancement beginning on May 4, 1998, appears to have been formed by inward transport over a period of several days. For L>4, peaks in the radial dependence of the phase space density are suggestive of a local electron source that may be nonadiabatic acceleration or pitch angle scattering. However, discrepancies in the results obtained with different magnetic field models and at different local times make this a tentative conclusion.

  2. Source location of the smooth high-frequency radio emissions from Uranus

    NASA Technical Reports Server (NTRS)

    Farrell, W. M.; Calvert, W.

    1989-01-01

    The source location of the smooth high-frequency radio emissions from Uranus has been determined. Specifically, by fitting the signal dropouts which occurred as Voyager traversed the hollow center of the emission pattern to a symmetrical cone centered on the source magnetic field direction at the cyclotron frequency, a southern-hemisphere (nightside) source was found at approximately 56 deg S, 219 deg W. The half-angle for the hollow portion of the emission pattern was found to be 13 deg.

  3. Bayesian statistics applied to the location of the source of explosions at Stromboli Volcano, Italy

    USGS Publications Warehouse

    Saccorotti, G.; Chouet, B.; Martini, M.; Scarpa, R.

    1998-01-01

    We present a method for determining the location and spatial extent of the source of explosions at Stromboli Volcano, Italy, based on a Bayesian inversion of the slowness vector derived from frequency-slowness analyses of array data. The method searches for source locations that minimize the error between the expected and observed slowness vectors. For a given set of model parameters, the conditional probability density function of slowness vectors is approximated by a Gaussian distribution of expected errors. The method is tested with synthetics using a five-layer velocity model derived for the north flank of Stromboli and a smoothed velocity model derived from a power-law approximation of the layered structure. Application to data from Stromboli allows for a detailed examination of uncertainties in source location due to experimental errors and incomplete knowledge of the Earth model. Although the solutions are not constrained in the radial direction, excellent resolution is achieved in both transverse and depth directions. Under the assumption that the horizontal extent of the source does not exceed the crater dimension, the 90% confidence region in the estimate of the explosive source location corresponds to a small volume extending from a depth of about 100 m to a maximum depth of about 300 m beneath the active vents, with a maximum likelihood source region located in the 120- to 180-m-depth interval.

  4. Identification of sources of aerosol particles in three locations in eastern Botswana

    NASA Astrophysics Data System (ADS)

    Chimidza, S.; Moloi, K.

    2000-07-01

    Airborne particles have been collected using a dichotomous virtual impactor at three different locations in the eastern part of Botswana: Serowe, Selibe-Phikwe, and Francistown. The particles were separated into two fractions (fine and coarse). Sampling at the three locations was done consecutively during the months of July and August, which are usually dry and stable. The sampling time for each sample was 12 hours during the day. For elemental composition, energy-dispersive x-ray fluorescence technique was used. Correlations and principal component analysis with varimax rotation were used to identify major sources of aerosol particles. In all the three places, soil was found to be the main source of aerosol particles. A copper-nickel mine and smelter at Selibe-Phikwe was found to be not only a source of copper and nickel particles in Selibe-Phikwe but also a source of these particles in far places like Serowe. In Selibe-Phikwe and Francistown, car exhaust was found to be the major source of fine particles of lead and bromine.

  5. Deep space target location with Hubble Space Telescope (HST) and Hipparcos data

    NASA Technical Reports Server (NTRS)

    Null, George W.

    1988-01-01

    Interplanetary spacecraft navigation requires accurate a priori knowledge of target positions. A concept is presented for attaining improved target ephemeris accuracy using two future Earth-orbiting optical observatories, the European Space Agency (ESA) Hipparcos observatory and the Nasa Hubble Space Telescope (HST). Assuming nominal observatory performance, the Hipparcos data reduction will provide an accurate global star catalog, and HST will provide a capability for accurate angular measurements of stars and solar system bodies. The target location concept employs HST to observe solar system bodies relative to Hipparcos catalog stars and to determine the orientation (frame tie) of these stars to compact extragalactic radio sources. The target location process is described, the major error sources discussed, the potential target ephemeris error predicted, and mission applications identified. Preliminary results indicate that ephemeris accuracy comparable to the errors in individual Hipparcos catalog stars may be possible with a more extensive HST observing program. Possible future ground and spacebased replacements for Hipparcos and HST astrometric capabilities are also discussed.

  6. Planar location of the simulative acoustic source based on fiber optic sensor array

    NASA Astrophysics Data System (ADS)

    Liang, Yi-Jun; Liu, Jun-feng; Zhang, Qiao-ping; Mu, Lin-lin

    2010-06-01

    A fiber optic sensor array which is structured by four Sagnac fiber optic sensors is proposed to detect and locate a simulative source of acoustic emission (AE). The sensing loops of Sagnac interferometer (SI) are regarded as point sensors as their small size. Based on the derived output light intensity expression of SI, the optimum work condition of the Sagnac fiber optic sensor is discussed through the simulation of MATLAB. Four sensors are respectively placed on a steel plate to structure the sensor array and the location algorithms are expatiated. When an impact is generated by an artificial AE source at any position of the plate, the AE signal will be detected by four sensors at different times. With the help of a single chip microcomputer (SCM) which can calculate the position of the AE source and display it on LED, we have implemented an intelligent detection and location.

  7. Autonomous robotic platforms for locating radio sources buried under rubble

    NASA Astrophysics Data System (ADS)

    Tasu, A. S.; Anchidin, L.; Tamas, R.; Paun, M.; Danisor, A.; Petrescu, T.

    2016-12-01

    This paper deals with the use of autonomous robotic platforms able to locate radio signal sources such as mobile phones, buried under collapsed buildings as a result of earthquakes, natural disasters, terrorism, war, etc. This technique relies on averaging position data resulting from a propagation model implemented on the platform and the data acquired by robotic platforms at the disaster site. That allows us to calculate the approximate position of radio sources buried under the rubble. Based on measurements, a radio map of the disaster site is made, very useful for locating victims and for guiding specific rubble lifting machinery, by assuming that there is a victim next to a mobile device detected by the robotic platform; by knowing the approximate position, the lifting machinery does not risk to further hurt the victims. Moreover, by knowing the positions of the victims, the reaction time is decreased, and the chances of survival for the victims buried under the rubble, are obviously increased.

  8. Determination of Jet Noise Radiation Source Locations using a Dual Sideline Cross-Correlation/Spectrum Technique

    NASA Technical Reports Server (NTRS)

    Allen, C. S.; Jaeger, S. M.

    1999-01-01

    The goal of our efforts is to extrapolate nearfield jet noise measurements to the geometric far field where the jet noise sources appear to radiate from a single point. To accomplish this, information about the location of noise sources in the jet plume, the radiation patterns of the noise sources and the sound pressure level distribution of the radiated field must be obtained. Since source locations and radiation patterns can not be found with simple single microphone measurements, a more complicated method must be used.

  9. Effect of source location and listener location on ILD cues in a reverberant room

    NASA Astrophysics Data System (ADS)

    Ihlefeld, Antje; Shinn-Cunningham, Barbara G.

    2004-05-01

    Short-term interaural level differences (ILDs) were analyzed for simulations of the signals that would reach a listener in a reverberant room. White noise was convolved with manikin head-related impulse responses measured in a classroom to simulate different locations of the source relative to the manikin and different manikin positions in the room. The ILDs of the signals were computed within each third-octave band over a relatively short time window to investigate how reliably ILD cues encode source laterality. Overall, the mean of the ILD magnitude increases with lateral angle and decreases with distance, as expected. Increasing reverberation decreases the mean ILD magnitude and increases the variance of the short-term ILD, so that the spatial information carried by ILD cues is degraded by reverberation. These results suggest that the mean ILD is not a reliable cue for determining source laterality in a reverberant room. However, by taking into account both the mean and variance, the distribution of high-frequency short-term ILDs provides some spatial information. This analysis suggests that, in order to use ILDs to judge source direction in reverberant space, listeners must accumulate information about how the short-term ILD varies over time. [Work supported by NIDCD and AFOSR.

  10. An automated multi-scale network-based scheme for detection and location of seismic sources

    NASA Astrophysics Data System (ADS)

    Poiata, N.; Aden-Antoniow, F.; Satriano, C.; Bernard, P.; Vilotte, J. P.; Obara, K.

    2017-12-01

    We present a recently developed method - BackTrackBB (Poiata et al. 2016) - allowing to image energy radiation from different seismic sources (e.g., earthquakes, LFEs, tremors) in different tectonic environments using continuous seismic records. The method exploits multi-scale frequency-selective coherence in the wave field, recorded by regional seismic networks or local arrays. The detection and location scheme is based on space-time reconstruction of the seismic sources through an imaging function built from the sum of station-pair time-delay likelihood functions, projected onto theoretical 3D time-delay grids. This imaging function is interpreted as the location likelihood of the seismic source. A signal pre-processing step constructs a multi-band statistical representation of the non stationary signal, i.e. time series, by means of higher-order statistics or energy envelope characteristic functions. Such signal-processing is designed to detect in time signal transients - of different scales and a priori unknown predominant frequency - potentially associated with a variety of sources (e.g., earthquakes, LFE, tremors), and to improve the performance and the robustness of the detection-and-location location step. The initial detection-location, based on a single phase analysis with the P- or S-phase only, can then be improved recursively in a station selection scheme. This scheme - exploiting the 3-component records - makes use of P- and S-phase characteristic functions, extracted after a polarization analysis of the event waveforms, and combines the single phase imaging functions with the S-P differential imaging functions. The performance of the method is demonstrated here in different tectonic environments: (1) analysis of the one year long precursory phase of 2014 Iquique earthquake in Chile; (2) detection and location of tectonic tremor sources and low-frequency earthquakes during the multiple episodes of tectonic tremor activity in southwestern Japan.

  11. Estimation of source locations of total gaseous mercury measured in New York State using trajectory-based models

    NASA Astrophysics Data System (ADS)

    Han, Young-Ji; Holsen, Thomas M.; Hopke, Philip K.

    Ambient gaseous phase mercury concentrations (TGM) were measured at three locations in NY State including Potsdam, Stockton, and Sterling from May 2000 to March 2005. Using these data, three hybrid receptor models incorporating backward trajectories were used to identify source areas for TGM. The models used were potential source contribution function (PSCF), residence time weighted concentration (RTWC), and simplified quantitative transport bias analysis (SQTBA). Each model was applied using multi-site measurements to resolve the locations of important mercury sources for New York State. PSCF results showed that southeastern New York, Ohio, Indiana, Tennessee, Louisiana, and Virginia were important TGM source areas for these sites. RTWC identified Canadian sources including the metal production facilities in Ontario and Quebec, but US regional sources including the Ohio River Valley were also resolved. Sources in southeastern NY, Massachusetts, western Pennsylvania, Indiana, and northern Illinois were identified to be significant by SQTBA. The three modeling results were combined to locate the most important probable source locations, and those are Ohio, Indiana, Illinois, and Wisconsin. The Atlantic Ocean was suggested to be a possible source as well.

  12. An efficient closed-form solution for acoustic emission source location in three-dimensional structures

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Xibing; Dong, Longjun, E-mail: csudlj@163.com; Australian Centre for Geomechanics, The University of Western Australia, Crawley, 6009

    This paper presents an efficient closed-form solution (ECS) for acoustic emission(AE) source location in three-dimensional structures using time difference of arrival (TDOA) measurements from N receivers, N ≥ 6. The nonlinear location equations of TDOA are simplified to linear equations. The unique analytical solution of AE sources for unknown velocity system is obtained by solving the linear equations. The proposed ECS method successfully solved the problems of location errors resulting from measured deviations of velocity as well as the existence and multiplicity of solutions induced by calculations of square roots in existed close-form methods.

  13. Acoustic Location of Lightning Using Interferometric Techniques

    NASA Astrophysics Data System (ADS)

    Erives, H.; Arechiga, R. O.; Stock, M.; Lapierre, J. L.; Edens, H. E.; Stringer, A.; Rison, W.; Thomas, R. J.

    2013-12-01

    Acoustic arrays have been used to accurately locate thunder sources in lightning flashes. The acoustic arrays located around the Magdalena mountains of central New Mexico produce locations which compare quite well with source locations provided by the New Mexico Tech Lightning Mapping Array. These arrays utilize 3 outer microphones surrounding a 4th microphone located at the center, The location is computed by band-passing the signal to remove noise, and then computing the cross correlating the outer 3 microphones with respect the center reference microphone. While this method works very well, it works best on signals with high signal to noise ratios; weaker signals are not as well located. Therefore, methods are being explored to improve the location accuracy and detection efficiency of the acoustic location systems. The signal received by acoustic arrays is strikingly similar to th signal received by radio frequency interferometers. Both acoustic location systems and radio frequency interferometers make coherent measurements of a signal arriving at a number of closely spaced antennas. And both acoustic and interferometric systems then correlate these signals between pairs of receivers to determine the direction to the source of the received signal. The primary difference between the two systems is the velocity of propagation of the emission, which is much slower for sound. Therefore, the same frequency based techniques that have been used quite successfully with radio interferometers should be applicable to acoustic based measurements as well. The results presented here are comparisons between the location results obtained with current cross correlation method and techniques developed for radio frequency interferometers applied to acoustic signals. The data were obtained during the summer 2013 storm season using multiple arrays sensitive to both infrasonic frequency and audio frequency acoustic emissions from lightning. Preliminary results show that

  14. Combined mine tremors source location and error evaluation in the Lubin Copper Mine (Poland)

    NASA Astrophysics Data System (ADS)

    Leśniak, Andrzej; Pszczoła, Grzegorz

    2008-08-01

    A modified method of mine tremors location used in Lubin Copper Mine is presented in the paper. In mines where an intensive exploration is carried out a high accuracy source location technique is usually required. The effect of the flatness of the geophones array, complex geological structure of the rock mass and intense exploitation make the location results ambiguous in such mines. In the present paper an effective method of source location and location's error evaluations are presented, combining data from two different arrays of geophones. The first consists of uniaxial geophones spaced in the whole mine area. The second is installed in one of the mining panels and consists of triaxial geophones. The usage of the data obtained from triaxial geophones allows to increase the hypocenter vertical coordinate precision. The presented two-step location procedure combines standard location methods: P-waves directions and P-waves arrival times. Using computer simulations the efficiency of the created algorithm was tested. The designed algorithm is fully non-linear and was tested on the multilayered rock mass model of the Lubin Copper Mine, showing a computational better efficiency than the traditional P-wave arrival times location algorithm. In this paper we present the complete procedure that effectively solves the non-linear location problems, i.e. the mine tremor location and measurement of the error propagation.

  15. Acoustic emission non-destructive testing of structures using source location techniques.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Beattie, Alan G.

    2013-09-01

    The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one onmore » aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments.« less

  16. Achieving perceptually-accurate aural telepresence

    NASA Astrophysics Data System (ADS)

    Henderson, Paul D.

    Immersive multimedia requires not only realistic visual imagery but also a perceptually-accurate aural experience. A sound field may be presented simultaneously to a listener via a loudspeaker rendering system using the direct sound from acoustic sources as well as a simulation or "auralization" of room acoustics. Beginning with classical Wave-Field Synthesis (WFS), improvements are made to correct for asymmetries in loudspeaker array geometry. Presented is a new Spatially-Equalized WFS (SE-WFS) technique to maintain the energy-time balance of a simulated room by equalizing the reproduced spectrum at the listener for a distribution of possible source angles. Each reproduced source or reflection is filtered according to its incidence angle to the listener. An SE-WFS loudspeaker array of arbitrary geometry reproduces the sound field of a room with correct spectral and temporal balance, compared with classically-processed WFS systems. Localization accuracy of human listeners in SE-WFS sound fields is quantified by psychoacoustical testing. At a loudspeaker spacing of 0.17 m (equivalent to an aliasing cutoff frequency of 1 kHz), SE-WFS exhibits a localization blur of 3 degrees, nearly equal to real point sources. Increasing the loudspeaker spacing to 0.68 m (for a cutoff frequency of 170 Hz) results in a blur of less than 5 degrees. In contrast, stereophonic reproduction is less accurate with a blur of 7 degrees. The ventriloquist effect is psychometrically investigated to determine the effect of an intentional directional incongruence between audio and video stimuli. Subjects were presented with prerecorded full-spectrum speech and motion video of a talker's head as well as broadband noise bursts with a static image. The video image was displaced from the audio stimulus in azimuth by varying amounts, and the perceived auditory location measured. A strong bias was detectable for small angular discrepancies between audio and video stimuli for separations of less than 8

  17. A Supervised Statistical Learning Approach for Accurate Legionella pneumophila Source Attribution during Outbreaks

    PubMed Central

    Buultjens, Andrew H.; Chua, Kyra Y. L.; Baines, Sarah L.; Kwong, Jason; Gao, Wei; Cutcher, Zoe; Adcock, Stuart; Ballard, Susan; Schultz, Mark B.; Tomita, Takehiro; Subasinghe, Nela; Carter, Glen P.; Pidot, Sacha J.; Franklin, Lucinda; Seemann, Torsten; Gonçalves Da Silva, Anders

    2017-01-01

    ABSTRACT Public health agencies are increasingly relying on genomics during Legionnaires' disease investigations. However, the causative bacterium (Legionella pneumophila) has an unusual population structure, with extreme temporal and spatial genome sequence conservation. Furthermore, Legionnaires' disease outbreaks can be caused by multiple L. pneumophila genotypes in a single source. These factors can confound cluster identification using standard phylogenomic methods. Here, we show that a statistical learning approach based on L. pneumophila core genome single nucleotide polymorphism (SNP) comparisons eliminates ambiguity for defining outbreak clusters and accurately predicts exposure sources for clinical cases. We illustrate the performance of our method by genome comparisons of 234 L. pneumophila isolates obtained from patients and cooling towers in Melbourne, Australia, between 1994 and 2014. This collection included one of the largest reported Legionnaires' disease outbreaks, which involved 125 cases at an aquarium. Using only sequence data from L. pneumophila cooling tower isolates and including all core genome variation, we built a multivariate model using discriminant analysis of principal components (DAPC) to find cooling tower-specific genomic signatures and then used it to predict the origin of clinical isolates. Model assignments were 93% congruent with epidemiological data, including the aquarium Legionnaires' disease outbreak and three other unrelated outbreak investigations. We applied the same approach to a recently described investigation of Legionnaires' disease within a UK hospital and observed a model predictive ability of 86%. We have developed a promising means to breach L. pneumophila genetic diversity extremes and provide objective source attribution data for outbreak investigations. IMPORTANCE Microbial outbreak investigations are moving to a paradigm where whole-genome sequencing and phylogenetic trees are used to support epidemiological

  18. Optimal Design for Placements of Tsunami Observing Systems to Accurately Characterize the Inducing Earthquake

    NASA Astrophysics Data System (ADS)

    Mulia, Iyan E.; Gusman, Aditya Riadi; Satake, Kenji

    2017-12-01

    Recently, there are numerous tsunami observation networks deployed in several major tsunamigenic regions. However, guidance on where to optimally place the measurement devices is limited. This study presents a methodological approach to select strategic observation locations for the purpose of tsunami source characterizations, particularly in terms of the fault slip distribution. Initially, we identify favorable locations and determine the initial number of observations. These locations are selected based on extrema of empirical orthogonal function (EOF) spatial modes. To further improve the accuracy, we apply an optimization algorithm called a mesh adaptive direct search to remove redundant measurement locations from the EOF-generated points. We test the proposed approach using multiple hypothetical tsunami sources around the Nankai Trough, Japan. The results suggest that the optimized observation points can produce more accurate fault slip estimates with considerably less number of observations compared to the existing tsunami observation networks.

  19. Joint Source Location and Focal Mechanism Inversion: efficiency, accuracy and applications

    NASA Astrophysics Data System (ADS)

    Liang, C.; Yu, Y.

    2017-12-01

    The analysis of induced seismicity has become a common practice to evaluate the results of hydraulic fracturing treatment. Liang et al (2016) proposed a joint Source Scanning Algorithms (jSSA for short) to obtain microseismic events and focal mechanisms simultaneously. The jSSA is superior over traditional SSA in many aspects, but the computation cost is too significant to be applied in real time monitoring. In this study, we have developed several scanning schemas to reduce computation time. A multi-stage scanning schema is proved to be able to improve the efficiency significantly while also retain its accuracy. A series of tests have been carried out by using both real field data and synthetic data to evaluate the accuracy of the method and its dependence on noise level, source depths, focal mechanisms and other factors. The surface-based arrays have better constraints on horizontal location errors (<20m) and angular errors of P axes (within 10 degree, for S/N>0.5). For sources with varying rakes, dips, strikes and depths, the errors are mostly controlled by the partition of positive and negative polarities in different quadrants. More evenly partitioned polarities in different quadrants yield better results in both locations and focal mechanisms. Nevertheless, even with bad resolutions for some FMs, the optimized jSSA method can still improve location accuracies significantly. Based on much more densely distributed events and focal mechanisms, a gridded stress inversion is conducted to get a evenly distributed stress field. The full potential of the jSSA has yet to be explored in different directions, especially in earthquake seismology as seismic array becoming incleasingly dense.

  20. Source location impact on relative tsunami strength along the U.S. West Coast

    NASA Astrophysics Data System (ADS)

    Rasmussen, L.; Bromirski, P. D.; Miller, A. J.; Arcas, D.; Flick, R. E.; Hendershott, M. C.

    2015-07-01

    Tsunami propagation simulations are used to identify which tsunami source locations would produce the highest amplitude waves on approach to key population centers along the U.S. West Coast. The reasons for preferential influence of certain remote excitation sites are explored by examining model time sequences of tsunami wave patterns emanating from the source. Distant bathymetric features in the West and Central Pacific can redirect tsunami energy into narrow paths with anomalously large wave height that have disproportionate impact on small areas of coastline. The source region generating the waves can be as little as 100 km along a subduction zone, resulting in distinct source-target pairs with sharply amplified wave energy at the target. Tsunami spectral ratios examined for transects near the source, after crossing the West Pacific, and on approach to the coast illustrate how prominent bathymetric features alter wave spectral distributions, and relate to both the timing and magnitude of waves approaching shore. To contextualize the potential impact of tsunamis from high-amplitude source-target pairs, the source characteristics of major historical earthquakes and tsunamis in 1960, 1964, and 2011 are used to generate comparable events originating at the highest-amplitude source locations for each coastal target. This creates a type of "worst-case scenario," a replicate of each region's historically largest earthquake positioned at the fault segment that would produce the most incoming tsunami energy at each target port. An amplification factor provides a measure of how the incoming wave height from the worst-case source compares to the historical event.

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

    NASA Astrophysics Data System (ADS)

    Sibaev, Marat; Crittenden, Deborah L.

    2016-06-01

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

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

    PubMed

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

    2016-07-01

    Current animal models of episodic memory are usually based on demonstrating integrated memory for what happened, where it happened, and when an event took place. These models aim to capture the testable features of the definition of human episodic memory which stresses the temporal component of the memory as a unique piece of source information that allows us to disambiguate one memory from another. Recently though, it has been suggested that a more accurate model of human episodic memory would include contextual rather than temporal source information, as humans' memory for time is relatively poor. Here, two experiments were carried out investigating human memory for temporal and contextual source information, along with the underlying dual process retrieval processes, using an immersive virtual environment paired with a 'Remember-Know' memory task. Experiment 1 (n=28) showed that contextual information could only be retrieved accurately using recollection, while temporal information could be retrieved using either recollection or familiarity. Experiment 2 (n=24), which used a more difficult task, resulting in reduced item recognition rates and therefore less potential for contamination by ceiling effects, replicated the pattern of results from Experiment 1. Dual process theory predicts that it should only be possible to retrieve source context from an event using recollection, and our results are consistent with this prediction. That temporal information can be retrieved using familiarity alone suggests that it may be incorrect to view temporal context as analogous to other typically used source contexts. This latter finding supports the alternative proposal that time since presentation may simply be reflected in the strength of memory trace at retrieval - a measure ideally suited to trace strength interrogation using familiarity, as is typically conceptualised within the dual process framework. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Sound Spectrum Influences Auditory Distance Perception of Sound Sources Located in a Room Environment

    PubMed Central

    Spiousas, Ignacio; Etchemendy, Pablo E.; Eguia, Manuel C.; Calcagno, Esteban R.; Abregú, Ezequiel; Vergara, Ramiro O.

    2017-01-01

    Previous studies on the effect of spectral content on auditory distance perception (ADP) focused on the physically measurable cues occurring either in the near field (low-pass filtering due to head diffraction) or when the sound travels distances >15 m (high-frequency energy losses due to air absorption). Here, we study how the spectrum of a sound arriving from a source located in a reverberant room at intermediate distances (1–6 m) influences the perception of the distance to the source. First, we conducted an ADP experiment using pure tones (the simplest possible spectrum) of frequencies 0.5, 1, 2, and 4 kHz. Then, we performed a second ADP experiment with stimuli consisting of continuous broadband and bandpass-filtered (with center frequencies of 0.5, 1.5, and 4 kHz and bandwidths of 1/12, 1/3, and 1.5 octave) pink-noise clips. Our results showed an effect of the stimulus frequency on the perceived distance both for pure tones and filtered noise bands: ADP was less accurate for stimuli containing energy only in the low-frequency range. Analysis of the frequency response of the room showed that the low accuracy observed for low-frequency stimuli can be explained by the presence of sparse modal resonances in the low-frequency region of the spectrum, which induced a non-monotonic relationship between binaural intensity and source distance. The results obtained in the second experiment suggest that ADP can also be affected by stimulus bandwidth but in a less straightforward way (i.e., depending on the center frequency, increasing stimulus bandwidth could have different effects). Finally, the analysis of the acoustical cues suggests that listeners judged source distance using mainly changes in the overall intensity of the auditory stimulus with distance rather than the direct-to-reverberant energy ratio, even for low-frequency noise bands (which typically induce high amount of reverberation). The results obtained in this study show that, depending on the spectrum

  4. Sound Spectrum Influences Auditory Distance Perception of Sound Sources Located in a Room Environment.

    PubMed

    Spiousas, Ignacio; Etchemendy, Pablo E; Eguia, Manuel C; Calcagno, Esteban R; Abregú, Ezequiel; Vergara, Ramiro O

    2017-01-01

    Previous studies on the effect of spectral content on auditory distance perception (ADP) focused on the physically measurable cues occurring either in the near field (low-pass filtering due to head diffraction) or when the sound travels distances >15 m (high-frequency energy losses due to air absorption). Here, we study how the spectrum of a sound arriving from a source located in a reverberant room at intermediate distances (1-6 m) influences the perception of the distance to the source. First, we conducted an ADP experiment using pure tones (the simplest possible spectrum) of frequencies 0.5, 1, 2, and 4 kHz. Then, we performed a second ADP experiment with stimuli consisting of continuous broadband and bandpass-filtered (with center frequencies of 0.5, 1.5, and 4 kHz and bandwidths of 1/12, 1/3, and 1.5 octave) pink-noise clips. Our results showed an effect of the stimulus frequency on the perceived distance both for pure tones and filtered noise bands: ADP was less accurate for stimuli containing energy only in the low-frequency range. Analysis of the frequency response of the room showed that the low accuracy observed for low-frequency stimuli can be explained by the presence of sparse modal resonances in the low-frequency region of the spectrum, which induced a non-monotonic relationship between binaural intensity and source distance. The results obtained in the second experiment suggest that ADP can also be affected by stimulus bandwidth but in a less straightforward way (i.e., depending on the center frequency, increasing stimulus bandwidth could have different effects). Finally, the analysis of the acoustical cues suggests that listeners judged source distance using mainly changes in the overall intensity of the auditory stimulus with distance rather than the direct-to-reverberant energy ratio, even for low-frequency noise bands (which typically induce high amount of reverberation). The results obtained in this study show that, depending on the spectrum of

  5. Possible Source Location of the Terrestrial Myriametric Radio Burst

    NASA Astrophysics Data System (ADS)

    Fung, S. F.; Shao, X.; Frey, H. U.; Garcia, L. N.

    2013-12-01

    Fung et al. [2013] reported recently the identification of a terrestrial myriametric radio burst (TMRB) that was possibly a result from a dayside high latitude reconnection process. The TMRB was observed simultaneously by the IMAGE and Geotail satellites when the satellites were located at widely different latitudes on opposite sides of the Earth in nearly the same meridional plane. The TMRB was observed when the interplanetary field was northward. Its intensity seemed to be modulated by the IMF Bz component while the source directions (relative to the Geotail positions over the TMRB interval) also seemed to respond to the changes in the IMF By component. In this paper, we will present further observations from the IMAGE FUV data during the TMRB interval, revealing the presence of a bright proton aurora spot at the cusp foot print and thus confirming the presence of high-latitude dayside reconnection at the time. We have also performed a CCMC run-on-request of a global magnetospheric simulation for a time period over the TMRB interval. We will present the CCMC results and discuss the possible identification of the location of the TMRB source. Fung, S. F., K. Hashimoto, H. Kojima, S. A. Boardsen, L. N. Garcia, H. Matsumoto, J. L. Green, and B. W. Reinisch (2013), Terrestrial myriametric radio burst observed by IMAGE and Geotail satellites, J. Geophys. Res. Space Physics, 118, 1101-1111, doi:10.1002/jgra.50149.

  6. In situ, accurate, surface-enhanced Raman scattering detection of cancer cell nucleus with synchronous location by an alkyne-labeled biomolecular probe.

    PubMed

    Zhang, Jing; Liang, Lijia; Guan, Xin; Deng, Rong; Qu, Huixin; Huang, Dianshuai; Xu, Shuping; Liang, Chongyang; Xu, Weiqing

    2018-01-01

    A surface-enhanced Raman scattering (SERS) method for in situ detection and analysis of the intranuclear biomolecular information of a cell has been developed based on a small, biocompatible, nuclear-targeting alkyne-tagged deoxyribonucleic acid (DNA) probe (5-ethynyl-2'-deoxyuridine, EDU) that can specially accumulate in the cell nucleus during DNA replications to precisely locate the nuclear region without disturbance in cell biological activities and functions. Since the specific alkyne group shows a Raman peak in the Raman-silent region of cells, it is an interior label to visualize the nuclear location synchronously in real time when measuring the SERS spectra of a cell. Because no fluorescent-labeled dyes were used for locating cell nuclei, this method is simple, nondestructive, non- photobleaching, and valuable for the in situ exploration of vital physiological processes with DNA participation in cell organelles. Graphical abstract A universal strategy was developed to accurately locate the nuclear region and obtain precise molecular information of cell nuclei by SERS.

  7. Fast and accurate detection of spread source in large complex networks.

    PubMed

    Paluch, Robert; Lu, Xiaoyan; Suchecki, Krzysztof; Szymański, Bolesław K; Hołyst, Janusz A

    2018-02-06

    Spread over complex networks is a ubiquitous process with increasingly wide applications. Locating spread sources is often important, e.g. finding the patient one in epidemics, or source of rumor spreading in social network. Pinto, Thiran and Vetterli introduced an algorithm (PTVA) to solve the important case of this problem in which a limited set of nodes act as observers and report times at which the spread reached them. PTVA uses all observers to find a solution. Here we propose a new approach in which observers with low quality information (i.e. with large spread encounter times) are ignored and potential sources are selected based on the likelihood gradient from high quality observers. The original complexity of PTVA is O(N α ), where α ∈ (3,4) depends on the network topology and number of observers (N denotes the number of nodes in the network). Our Gradient Maximum Likelihood Algorithm (GMLA) reduces this complexity to O (N 2 log (N)). Extensive numerical tests performed on synthetic networks and real Gnutella network with limitation that id's of spreaders are unknown to observers demonstrate that for scale-free networks with such limitation GMLA yields higher quality localization results than PTVA does.

  8. Comparison of two trajectory based models for locating particle sources for two rural New York sites

    NASA Astrophysics Data System (ADS)

    Zhou, Liming; Hopke, Philip K.; Liu, Wei

    Two back trajectory-based statistical models, simplified quantitative transport bias analysis and residence-time weighted concentrations (RTWC) have been compared for their capabilities of identifying likely locations of source emissions contributing to observed particle concentrations at Potsdam and Stockton, New York. Quantitative transport bias analysis (QTBA) attempts to take into account the distribution of concentrations around the directions of the back trajectories. In full QTBA approach, deposition processes (wet and dry) are also considered. Simplified QTBA omits the consideration of deposition. It is best used with multiple site data. Similarly the RTWC approach uses concentrations measured at different sites along with the back trajectories to distribute the concentration contributions across the spatial domain of the trajectories. In this study, these models are used in combination with the source contribution values obtained by the previous positive matrix factorization analysis of particle composition data from Potsdam and Stockton. The six common sources for the two sites, sulfate, soil, zinc smelter, nitrate, wood smoke and copper smelter were analyzed. The results of the two methods are consistent and locate large and clearly defined sources well. RTWC approach can find more minor sources but may also give unrealistic estimations of the source locations.

  9. Measurement of Jovian decametric Io-related source location and beam shape

    NASA Technical Reports Server (NTRS)

    Maeda, K.; Carr, T. D.

    1992-01-01

    The paper presents new information on the locations of the Io-related sources A and C (i.e., Io-A and Io-C) and on the shapes of their emission beams on the basis of measurements of the Jovian decametric activity that was recorded by Voyager 1 and 2. In two instances, the same dynamic spectral arc event in the recorded data of the two spacecraft was recorded, providing in each case an opportunity to observe the same emission beam over a wide range of frequencies from two considerably different directions. The propagation-corrected centroid times of each of the Voyager-1 arcs are found to be coincident with those of the corresponding Voyager-2 arc in a particular frequency range, but not at other frequencies. The hypothesis that emission beams are in the form of thin, almost conical sheets, the cone opening angle decreasing with increasing frequency, is confirmed. It is demonstrated that both the Io-A and Io-C sources were located near the northern foot of the magnetic flux tube that was connected to Io.

  10. Accurate Analysis of the Change in Volume, Location, and Shape of Metastatic Cervical Lymph Nodes During Radiotherapy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Takao, Seishin, E-mail: takao@mech-me.eng.hokudai.ac.jp; Tadano, Shigeru; Taguchi, Hiroshi

    2011-11-01

    Purpose: To establish a method for the accurate acquisition and analysis of the variations in tumor volume, location, and three-dimensional (3D) shape of tumors during radiotherapy in the era of image-guided radiotherapy. Methods and Materials: Finite element models of lymph nodes were developed based on computed tomography (CT) images taken before the start of treatment and every week during the treatment period. A surface geometry map with a volumetric scale was adopted and used for the analysis. Six metastatic cervical lymph nodes, 3.5 to 55.1 cm{sup 3} before treatment, in 6 patients with head and neck carcinomas were analyzed inmore » this study. Three fiducial markers implanted in mouthpieces were used for the fusion of CT images. Changes in the location of the lymph nodes were measured on the basis of these fiducial markers. Results: The surface geometry maps showed convex regions in red and concave regions in blue to ensure that the characteristics of the 3D tumor geometries are simply understood visually. After the irradiation of 66 to 70 Gy in 2 Gy daily doses, the patterns of the colors had not changed significantly, and the maps before and during treatment were strongly correlated (average correlation coefficient was 0.808), suggesting that the tumors shrank uniformly, maintaining the original characteristics of the shapes in all 6 patients. The movement of the gravitational center of the lymph nodes during the treatment period was everywhere less than {+-}5 mm except in 1 patient, in whom the change reached nearly 10 mm. Conclusions: The surface geometry map was useful for an accurate evaluation of the changes in volume and 3D shapes of metastatic lymph nodes. The fusion of the initial and follow-up CT images based on fiducial markers enabled an analysis of changes in the location of the targets. Metastatic cervical lymph nodes in patients were suggested to decrease in size without significant changes in the 3D shape during radiotherapy. The

  11. Statistical study of coronal mass ejection source locations: Understanding CMEs viewed in coronagraphs

    NASA Astrophysics Data System (ADS)

    Wang, Yuming; Chen, Caixia; Gui, Bin; Shen, Chenglong; Ye, Pinzhong; Wang, S.

    2011-04-01

    How to properly understand coronal mass ejections (CMEs) viewed in white light coronagraphs is crucial to many relative researches in solar and space physics. The issue is now particularly addressed in this paper through studying the source locations of all the 1078 Large Angle and Spectrometric Coronagraph (LASCO) CMEs listed in Coordinated Data Analysis Workshop (CDAW) CME catalog during 1997-1998 and their correlation with CMEs' apparent parameters. By manually checking LASCO and Extreme Ultraviolet Imaging Telescope (EIT) movies of these CMEs, we find that, except 231 CMEs whose source locations cannot be identified due to poor data, there are 288 CMEs with location identified on the frontside solar disk, 234 CMEs appearing above solar limb, and 325 CMEs without evident eruptive signatures in the field of view of EIT. On the basis of the statistical results of CMEs' source locations, there are four physical issues: (1) the missing rate of CMEs by SOHO LASCO and EIT, (2) the mass of CMEs, (3) the causes of halo CMEs, and (4) the deflections of CMEs in the corona, are exhaustively analyzed. It is found that (1) about 32% frontside CMEs cannot be recognized by SOHO, (2) the brightness of a CME at any heliocentric distance is roughly positively correlated with its speed, and the CME mass derived from the brightness is probably overestimated, (3) both projection effect and violent eruption are the major causes of halo CMEs, and especially for limb halo CMEs the latter is the primary one, and (4) most CMEs deflected toward equator near the solar minimum; these deflections can be classified into three types: the asymmetrical expansion, the nonradial ejection, and the deflected propagation.

  12. Locating and Quantifying Broadband Fan Sources Using In-Duct Microphones

    NASA Technical Reports Server (NTRS)

    Dougherty, Robert P.; Walker, Bruce E.; Sutliff, Daniel L.

    2010-01-01

    In-duct beamforming techniques have been developed for locating broadband noise sources on a low-speed fan and quantifying the acoustic power in the inlet and aft fan ducts. The NASA Glenn Research Center's Advanced Noise Control Fan was used as a test bed. Several of the blades were modified to provide a broadband source to evaluate the efficacy of the in-duct beamforming technique. Phased arrays consisting of rings and line arrays of microphones were employed. For the imaging, the data were mathematically resampled in the frame of reference of the rotating fan. For both the imaging and power measurement steps, array steering vectors were computed using annular duct modal expansions, selected subsets of the cross spectral matrix elements were used, and the DAMAS and CLEAN-SC deconvolution algorithms were applied.

  13. Accurate, reliable prototype earth horizon sensor head

    NASA Technical Reports Server (NTRS)

    Schwarz, F.; Cohen, H.

    1973-01-01

    The design and performance is described of an accurate and reliable prototype earth sensor head (ARPESH). The ARPESH employs a detection logic 'locator' concept and horizon sensor mechanization which should lead to high accuracy horizon sensing that is minimally degraded by spatial or temporal variations in sensing attitude from a satellite in orbit around the earth at altitudes in the 500 km environ 1,2. An accuracy of horizon location to within 0.7 km has been predicted, independent of meteorological conditions. This corresponds to an error of 0.015 deg-at 500 km altitude. Laboratory evaluation of the sensor indicates that this accuracy is achieved. First, the basic operating principles of ARPESH are described; next, detailed design and construction data is presented and then performance of the sensor under laboratory conditions in which the sensor is installed in a simulator that permits it to scan over a blackbody source against background representing the earth space interface for various equivalent plant temperatures.

  14. A study on locating the sonic source of sinusoidal magneto-acoustic signals using a vector method.

    PubMed

    Zhang, Shunqi; Zhou, Xiaoqing; Ma, Ren; Yin, Tao; Liu, Zhipeng

    2015-01-01

    Methods based on the magnetic-acoustic effect are of great significance in studying the electrical imaging properties of biological tissues and currents. The continuous wave method, which is commonly used, can only detect the current amplitude without the sound source position. Although the pulse mode adopted in magneto-acoustic imaging can locate the sonic source, the low measuring accuracy and low SNR has limited its application. In this study, a vector method was used to solve and analyze the magnetic-acoustic signal based on the continuous sine wave mode. This study includes theory modeling of the vector method, simulations to the line model, and experiments with wire samples to analyze magneto-acoustic (MA) signal characteristics. The results showed that the amplitude and phase of the MA signal contained the location information of the sonic source. The amplitude and phase obeyed the vector theory in the complex plane. This study sets a foundation for a new technique to locate sonic sources for biomedical imaging of tissue conductivity. It also aids in studying biological current detecting and reconstruction based on the magneto-acoustic effect.

  15. A source-attractor approach to network detection of radiation sources

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Qishi; Barry, M. L..; Grieme, M.

    Radiation source detection using a network of detectors is an active field of research for homeland security and defense applications. We propose Source-attractor Radiation Detection (SRD) method to aggregate measurements from a network of detectors for radiation source detection. SRD method models a potential radiation source as a magnet -like attractor that pulls in pre-computed virtual points from the detector locations. A detection decision is made if a sufficient level of attraction, quantified by the increase in the clustering of the shifted virtual points, is observed. Compared with traditional methods, SRD has the following advantages: i) it does not requiremore » an accurate estimate of the source location from limited and noise-corrupted sensor readings, unlike the localizationbased methods, and ii) its virtual point shifting and clustering calculation involve simple arithmetic operations based on the number of detectors, avoiding the high computational complexity of grid-based likelihood estimation methods. We evaluate its detection performance using canonical datasets from Domestic Nuclear Detection Office s (DNDO) Intelligence Radiation Sensors Systems (IRSS) tests. SRD achieves both lower false alarm rate and false negative rate compared to three existing algorithms for network source detection.« less

  16. Helicopter magnetic survey conducted to locate wells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Veloski, G.A.; Hammack, R.W.; Stamp, V.

    2008-07-01

    A helicopter magnetic survey was conducted in August 2007 over 15.6 sq mi at the Naval Petroleum Reserve No. 3’s (NPR-3) Teapot Dome Field near Casper, Wyoming. The survey’s purpose was to accurately locate wells drilled there during more than 90 years of continuous oilfield operation. The survey was conducted at low altitude and with closely spaced flight lines to improve the detection of wells with weak magnetic response and to increase the resolution of closely spaced wells. The survey was in preparation for a planned CO2 flood for EOR, which requires a complete well inventory with accurate locations formore » all existing wells. The magnetic survey was intended to locate wells missing from the well database and to provide accurate locations for all wells. The ability of the helicopter magnetic survey to accurately locate wells was accomplished by comparing airborne well picks with well locations from an intense ground search of a small test area.« less

  17. A simplified approach to characterizing a kilovoltage source spectrum for accurate dose computation.

    PubMed

    Poirier, Yannick; Kouznetsov, Alexei; Tambasco, Mauro

    2012-06-01

    %. The HVL and kVp are sufficient for characterizing a kV x-ray source spectrum for accurate dose computation. As these parameters can be easily and accurately measured, they provide for a clinically feasible approach to characterizing a kV energy spectrum to be used for patient specific x-ray dose computations. Furthermore, these results provide experimental validation of our novel hybrid dose computation algorithm. © 2012 American Association of Physicists in Medicine.

  18. An Improved Source-Scanning Algorithm for Locating Earthquake Clusters or Aftershock Sequences

    NASA Astrophysics Data System (ADS)

    Liao, Y.; Kao, H.; Hsu, S.

    2010-12-01

    The Source-scanning Algorithm (SSA) was originally introduced in 2004 to locate non-volcanic tremors. Its application was later expanded to the identification of earthquake rupture planes and the near-real-time detection and monitoring of landslides and mud/debris flows. In this study, we further improve SSA for the purpose of locating earthquake clusters or aftershock sequences when only a limited number of waveform observations are available. The main improvements include the application of a ground motion analyzer to separate P and S waves, the automatic determination of resolution based on the grid size and time step of the scanning process, and a modified brightness function to utilize constraints from multiple phases. Specifically, the improved SSA (named as ISSA) addresses two major issues related to locating earthquake clusters/aftershocks. The first one is the massive amount of both time and labour to locate a large number of seismic events manually. And the second one is to efficiently and correctly identify the same phase across the entire recording array when multiple events occur closely in time and space. To test the robustness of ISSA, we generate synthetic waveforms consisting of 3 separated events such that individual P and S phases arrive at different stations in different order, thus making correct phase picking nearly impossible. Using these very complicated waveforms as the input, the ISSA scans all model space for possible combination of time and location for the existence of seismic sources. The scanning results successfully associate various phases from each event at all stations, and correctly recover the input. To further demonstrate the advantage of ISSA, we apply it to the waveform data collected by a temporary OBS array for the aftershock sequence of an offshore earthquake southwest of Taiwan. The overall signal-to-noise ratio is inadequate for locating small events; and the precise arrival times of P and S phases are difficult to

  19. Trends in energy intake among US children by eating location and food source, 1977-2006.

    PubMed

    Poti, Jennifer M; Popkin, Barry M

    2011-08-01

    Little is known about the influence of location of food consumption and preparation upon daily energy intake of children. To examine trends in daily energy intake by children for foods eaten at home or away from home, by source of preparation, and for combined categories of eating location and food source. The analysis uses data from 29,217 children aged 2 to 18 years from the 1977-1978 Nationwide Food Consumption Survey, 1989-1991 and 1994-1998 Continuing Survey of Food Intakes by Individuals, and 2003-2006 National Health and Nutrition Examination Surveys. Nationally representative weighted percentages and means of daily energy intake by eating location were analyzed for trends from 1977 to 2006. Comparisons by food source were examined from 1994 to 2006. Analyses were repeated for three age groups: 2 to 6 years, 7 to 12 years, and 13 to 18 years. Difference testing was conducted using a t test. Increased energy intake (+179 kcal/day) by children from 1977-2006 was associated with a major increase in energy eaten away from home (+255 kcal/day). The percentage of daily energy eaten away from home increased from 23.4% to 33.9% from 1977-2006. No further increase was observed from 1994-2006, but the sources of energy shifted. The percentage of energy from fast food increased to surpass intake from schools and become the largest contributor to foods prepared away from home for all age groups. For foods eaten away from home, the percentage of daily energy from stores increased to become the largest source of energy eaten away from home. Fast food eaten at home and store-bought food eaten away from home increased significantly. Eating location and food source significantly influence daily energy intake for children. Foods prepared away from home, including fast food eaten at home and store-prepared food eaten away from home, are fueling the increase in total energy intake. However, further research using alternative data sources is necessary to verify that store

  20. Identifying elements of the plumbing system beneath Kilauea Volcano, Hawaii, from the source locations of very-long-period signals

    USGS Publications Warehouse

    Almendros, J.; Chouet, B.; Dawson, P.; Bond, T.

    2002-01-01

    We analyzed 16 seismic events recorded by the Hawaiian broad-band seismic network at Kilauca Volcano during the period September 9-26, 1999. Two distinct types of event are identified based on their spectral content, very-long-period (VLP) waveform, amplitude decay pattern and particle motion. We locate the VLP signals with a method based on analyses of semblance and particle motion. Different source regions are identified for the two event types. One source region is located at depths of ~1 km beneath the northeast edge of the Halemaumau pit crater. A second region is located at depths of ~8 km below the northwest quadrant of Kilauea caldera. Our study represents the first time that such deep sources have been identified in VLP data at Kilauea. This discovery opens the possibility of obtaining a detailed image of the location and geometry of the magma plumbing system beneath this volcano based on source locations and moment tensor inversions of VLP signals recorded by a permanent, large-aperture broad-band network.

  1. Characteristics of Love and Rayleigh waves in ambient noise: wavetype ratio, source location and seasonal behavior

    NASA Astrophysics Data System (ADS)

    Juretzek, C.; Perleth, M.; Hadziioannou, C.

    2015-12-01

    Ambient seismic noise has become an important source of signal for tomography and monitoring purposes. Better understanding of the noise field characteristics is crucial to further improve noise applications. Our knowledge about the common and different origins of Love and Rayleigh waves in the microseism bands is still limited. This applies in particular to constraints on source locations and source mechanisms of Love waves. Here, 3-component beamforming is used to distinguish between the differently polarized wave types present in the noise field recorded at several arrays across Europe. The focus lies on frequencies around the primary and secondary microseismic bands. We compare characteristics of Love and Rayleigh wave noise, such as source directions and frequency content. Further, Love to Rayleigh wave ratios are measured at each array, and a dependence on direction is observed. We constrain the corresponding source regions of both wave types by backprojection. By using a full year of data in 2013, we are able to track the seasonal changes in our observations of Love-to-Rayleigh ratio and source locations.

  2. Application Research of Horn Array Multi-Beam Antenna in Reference Source System for Satellite Interference Location

    NASA Astrophysics Data System (ADS)

    Zhou, Ping; Lin, Hui; Zhang, Qi

    2018-01-01

    The reference source system is a key factor to ensure the successful location of the satellite interference source. Currently, the traditional system used a mechanical rotating antenna which leaded to the disadvantages of slow rotation and high failure-rate, which seriously restricted the system’s positioning-timeliness and became its obvious weaknesses. In this paper, a multi-beam antenna scheme based on the horn array was proposed as a reference source for the satellite interference location, which was used as an alternative to the traditional reference source antenna. The new scheme has designed a small circularly polarized horn antenna as an element and proposed a multi-beamforming algorithm based on planar array. Moreover, the simulation analysis of horn antenna pattern, multi-beam forming algorithm and simulated satellite link cross-ambiguity calculation have been carried out respectively. Finally, cross-ambiguity calculation of the traditional reference source system has also been tested. The comparison between the results of computer simulation and the actual test results shows that the scheme is scientific and feasible, obviously superior to the traditional reference source system.

  3. Development of double-pair double difference location algorithm and its application to the regular earthquakes and non-volcanic tremors

    NASA Astrophysics Data System (ADS)

    Guo, H.; Zhang, H.

    2016-12-01

    Relocating high-precision earthquakes is a central task for monitoring earthquakes and studying the structure of earth's interior. The most popular location method is the event-pair double-difference (DD) relative location method, which uses the catalog and/or more accurate waveform cross-correlation (WCC) differential times from event pairs with small inter-event separations to the common stations to reduce the effect of the velocity uncertainties outside the source region. Similarly, Zhang et al. [2010] developed a station-pair DD location method which uses the differential times from common events to pairs of stations to reduce the effect of the velocity uncertainties near the source region, to relocate the non-volcanic tremors (NVT) beneath the San Andreas Fault (SAF). To utilize advantages of both DD location methods, we have proposed and developed a new double-pair DD location method to use the differential times from pairs of events to pairs of stations. The new method can remove the event origin time and station correction terms from the inversion system and cancel out the effects of the velocity uncertainties near and outside the source region simultaneously. We tested and applied the new method on the northern California regular earthquakes to validate its performance. In comparison, among three DD location methods, the new double-pair DD method can determine more accurate relative locations and the station-pair DD method can better improve the absolute locations. Thus, we further proposed a new location strategy combining station-pair and double-pair differential times to determine accurate absolute and relative locations at the same time. For NVTs, it is difficult to pick the first arrivals and derive the WCC event-pair differential times, thus the general practice is to measure station-pair envelope WCC differential times. However, station-pair tremor locations are scattered due to the low-precision relative locations. The ability that double-pair data

  4. Gravitational wave hotspots: Ranking potential locations of single-source gravitational wave emission

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simon, Joseph; Polin, Abigail; Lommen, Andrea

    2014-03-20

    The steadily improving sensitivity of pulsar timing arrays (PTAs) suggests that gravitational waves (GWs) from supermassive black hole binary (SMBHB) systems in the nearby universe will be detectable sometime during the next decade. Currently, PTAs assume an equal probability of detection from every sky position, but as evidence grows for a non-isotropic distribution of sources, is there a most likely sky position for a detectable single source of GWs? In this paper, a collection of Galactic catalogs is used to calculate various metrics related to the detectability of a single GW source resolvable above a GW background, assuming that everymore » galaxy has the same probability of containing an SMBHB. Our analyses of these data reveal small probabilities that one of these sources is currently in the PTA band, but as sensitivity is improved regions of consistent probability density are found in predictable locations, specifically around local galaxy clusters.« less

  5. Estimation of source location and ground impedance using a hybrid multiple signal classification and Levenberg-Marquardt approach

    NASA Astrophysics Data System (ADS)

    Tam, Kai-Chung; Lau, Siu-Kit; Tang, Shiu-Keung

    2016-07-01

    A microphone array signal processing method for locating a stationary point source over a locally reactive ground and for estimating ground impedance is examined in detail in the present study. A non-linear least square approach using the Levenberg-Marquardt method is proposed to overcome the problem of unknown ground impedance. The multiple signal classification method (MUSIC) is used to give the initial estimation of the source location, while the technique of forward backward spatial smoothing is adopted as a pre-processer of the source localization to minimize the effects of source coherence. The accuracy and robustness of the proposed signal processing method are examined. Results show that source localization in the horizontal direction by MUSIC is satisfactory. However, source coherence reduces drastically the accuracy in estimating the source height. The further application of Levenberg-Marquardt method with the results from MUSIC as the initial inputs improves significantly the accuracy of source height estimation. The present proposed method provides effective and robust estimation of the ground surface impedance.

  6. Location of acoustic radiators and inversion for energy density using radio-frequency sources and thunder recordings

    NASA Astrophysics Data System (ADS)

    Anderson, J.; Johnson, J. B.; Arechiga, R. O.; Edens, H. E.; Thomas, R. J.

    2011-12-01

    We use radio frequency (VHF) pulse locations mapped with the New Mexico Tech Lightning Mapping Array (LMA) to study the distribution of thunder sources in lightning channels. A least squares inversion is used to fit channel acoustic energy radiation with broadband (0.01 to 500 Hz) acoustic recordings using microphones deployed local (< 10 km) to the lightning. We model the thunder (acoustic) source as a superposition of line segments connecting the LMA VHF pulses. An optimum branching algorithm is used to reconstruct conductive channels delineated by VHF sources, which we discretize as a superposition of finely-spaced (0.25 m) acoustic point sources. We consider total radiated thunder as a weighted superposition of acoustic waves from individual channels, each with a constant current along its length that is presumed to be proportional to acoustic energy density radiated per unit length. Merged channels are considered as a linear sum of current-carrying branches and radiate proportionally greater acoustic energy. Synthetic energy time series for a given microphone location are calculated for each independent channel. We then use a non-negative least squares inversion to solve for channel energy densities to match the energy time series determined from broadband acoustic recordings across a 4-station microphone network. Events analyzed by this method have so far included 300-1000 VHF sources, and correlations as high as 0.5 between synthetic and recorded thunder energy were obtained, despite the presence of wind noise and 10-30 m uncertainty in VHF source locations.

  7. LLNL Location and Detection Research

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Myers, S C; Harris, D B; Anderson, M L

    2003-07-16

    We present two LLNL research projects in the topical areas of location and detection. The first project assesses epicenter accuracy using a multiple-event location algorithm, and the second project employs waveform subspace Correlation to detect and identify events at Fennoscandian mines. Accurately located seismic events are the bases of location calibration. A well-characterized set of calibration events enables new Earth model development, empirical calibration, and validation of models. In a recent study, Bondar et al. (2003) develop network coverage criteria for assessing the accuracy of event locations that are determined using single-event, linearized inversion methods. These criteria are conservative andmore » are meant for application to large bulletins where emphasis is on catalog completeness and any given event location may be improved through detailed analysis or application of advanced algorithms. Relative event location techniques are touted as advancements that may improve absolute location accuracy by (1) ensuring an internally consistent dataset, (2) constraining a subset of events to known locations, and (3) taking advantage of station and event correlation structure. Here we present the preliminary phase of this work in which we use Nevada Test Site (NTS) nuclear explosions, with known locations, to test the effect of travel-time model accuracy on relative location accuracy. Like previous studies, we find that the reference velocity-model and relative-location accuracy are highly correlated. We also find that metrics based on travel-time residual of relocated events are not a reliable for assessing either velocity-model or relative-location accuracy. In the topical area of detection, we develop specialized correlation (subspace) detectors for the principal mines surrounding the ARCES station located in the European Arctic. Our objective is to provide efficient screens for explosions occurring in the mines of the Kola Peninsula (Kovdor

  8. Identify source location and release time for pollutants undergoing super-diffusion and decay: Parameter analysis and model evaluation

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Sun, HongGuang; Lu, Bingqing; Garrard, Rhiannon; Neupauer, Roseanna M.

    2017-09-01

    Backward models have been applied for four decades by hydrologists to identify the source of pollutants undergoing Fickian diffusion, while analytical tools are not available for source identification of super-diffusive pollutants undergoing decay. This technical note evaluates analytical solutions for the source location and release time of a decaying contaminant undergoing super-diffusion using backward probability density functions (PDFs), where the forward model is the space fractional advection-dispersion equation with decay. Revisit of the well-known MADE-2 tracer test using parameter analysis shows that the peak backward location PDF can predict the tritium source location, while the peak backward travel time PDF underestimates the tracer release time due to the early arrival of tracer particles at the detection well in the maximally skewed, super-diffusive transport. In addition, the first-order decay adds additional skewness toward earlier arrival times in backward travel time PDFs, resulting in a younger release time, although this impact is minimized at the MADE-2 site due to tritium's half-life being relatively longer than the monitoring period. The main conclusion is that, while non-trivial backward techniques are required to identify pollutant source location, the pollutant release time can and should be directly estimated given the speed of the peak resident concentration for super-diffusive pollutants with or without decay.

  9. Trends in energy intake among US children by eating location and food source, 1977–2006

    PubMed Central

    Poti, Jennifer M.; Popkin, Barry M.

    2011-01-01

    Background Little is known about the impact of location of food consumption and preparation upon daily energy intake for children. Objective To examine trends in daily energy intake by children for foods eaten at home or away-from-home, by source of preparation, and for combined categories of eating location and food source. Subjects The analysis uses data from 29,217 children aged 2–18 years from the 1977–1978 Nationwide Food Consumption Survey, 1989–1991 and 1994–1998 Continuing Survey of Food Intake by Individuals, and 2003–2006 National Health and Nutrition Examination Surveys. Methods Nationally representative weighted percentages and means of daily energy intake by eating location were analyzed for trends from 1977 to 2006. Comparisons by food source were examined from 1994 to 2006. Analyses were repeated for 3 age groups: 2–6, 7–12, and 13–18 year olds. Difference testing was conducted using a t test. Results Increased energy intake (+179 kcal/d) by children from 1977–2006 was associated with a major increase in calories eaten away-from-home (+255 kcal/d). The percentage of kcal/d eaten away-from-home increased from 23.4% to 33.9% from 1977–2006. No further increase was observed from 1994–2006, but the sources of calories shifted. The percentage of calories from fast food increased to surpass intake from schools and become the largest contributor to foods prepared away-from-home for all age groups. For foods eaten away-from-home, the percentage of kcal/d from stores increased to become the largest source of calories eaten away-from-home. Fast food eaten at home and store-bought food eaten away-from-home increased significantly. Conclusion Eating location and food source significantly impact daily energy intake for children. Foods prepared away-from-home, including fast food eaten at home and store-prepared food eaten away-from-home, are fueling the increase in total calorie intake. However, further research using alternative data

  10. Decision analysis of emergency ventilation and evacuation strategies against suddenly released contaminant indoors by considering the uncertainty of source locations.

    PubMed

    Cai, Hao; Long, Weiding; Li, Xianting; Kong, Lingjuan; Xiong, Shuang

    2010-06-15

    In case hazardous contaminants are suddenly released indoors, the prompt and proper emergency responses are critical to protect occupants. This paper aims to provide a framework for determining the optimal combination of ventilation and evacuation strategies by considering the uncertainty of source locations. The certainty of source locations is classified as complete certainty, incomplete certainty, and complete uncertainty to cover all the possible situations. According to this classification, three types of decision analysis models are presented. A new concept, efficiency factor of contaminant source (EFCS), is incorporated in these models to evaluate the payoffs of the ventilation and evacuation strategies. A procedure of decision-making based on these models is proposed and demonstrated by numerical studies of one hundred scenarios with ten ventilation modes, two evacuation modes, and five source locations. The results show that the models can be useful to direct the decision analysis of both the ventilation and evacuation strategies. In addition, the certainty of the source locations has an important effect on the outcomes of the decision-making. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Automated seismic waveform location using Multichannel Coherency Migration (MCM)-I. Theory

    NASA Astrophysics Data System (ADS)

    Shi, Peidong; Angus, Doug; Rost, Sebastian; Nowacki, Andy; Yuan, Sanyi

    2018-03-01

    With the proliferation of dense seismic networks sampling the full seismic wavefield, recorded seismic data volumes are getting bigger and automated analysis tools to locate seismic events are essential. Here, we propose a novel Multichannel Coherency Migration (MCM) method to locate earthquakes in continuous seismic data and reveal the location and origin time of seismic events directly from recorded waveforms. By continuously calculating the coherency between waveforms from different receiver pairs, MCM greatly expands the available information which can be used for event location. MCM does not require phase picking or phase identification, which allows fully automated waveform analysis. By migrating the coherency between waveforms, MCM leads to improved source energy focusing. We have tested and compared MCM to other migration-based methods in noise-free and noisy synthetic data. The tests and analysis show that MCM is noise resistant and can achieve more accurate results compared with other migration-based methods. MCM is able to suppress strong interference from other seismic sources occurring at a similar time and location. It can be used with arbitrary 3D velocity models and is able to obtain reasonable location results with smooth but inaccurate velocity models. MCM exhibits excellent location performance and can be easily parallelized giving it large potential to be developed as a real-time location method for very large datasets.

  12. 40 CFR Table 2d to Subpart Zzzz of... - Requirements for Existing Stationary RICE Located at Area Sources of HAP Emissions

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... RICE Located at Area Sources of HAP Emissions 2d Table 2d to Subpart ZZZZ of Part 63 Protection of... 2d Table 2d to Subpart ZZZZ of Part 63—Requirements for Existing Stationary RICE Located at Area... requirements for existing stationary RICE located at area sources of HAP emissions: For each . . . You must...

  13. A robust statistical estimation (RoSE) algorithm jointly recovers the 3D location and intensity of single molecules accurately and precisely

    NASA Astrophysics Data System (ADS)

    Mazidi, Hesam; Nehorai, Arye; Lew, Matthew D.

    2018-02-01

    In single-molecule (SM) super-resolution microscopy, the complexity of a biological structure, high molecular density, and a low signal-to-background ratio (SBR) may lead to imaging artifacts without a robust localization algorithm. Moreover, engineered point spread functions (PSFs) for 3D imaging pose difficulties due to their intricate features. We develop a Robust Statistical Estimation algorithm, called RoSE, that enables joint estimation of the 3D location and photon counts of SMs accurately and precisely using various PSFs under conditions of high molecular density and low SBR.

  14. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at a Major Source of HAP...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Ignition Stationary RICE Located at a Major Source of HAP Emissions and Existing Spark Ignition Stationary RICE ⤠500 HP Located at a Major Source of HAP Emissions 2c Table 2c to Subpart ZZZZ of Part 63... Stationary RICE Located at a Major Source of HAP Emissions and Existing Spark Ignition Stationary RICE ≤ 500...

  15. Source contribution of PM₂.₅ at different locations on the Malaysian Peninsula.

    PubMed

    Ee-Ling, Ooi; Mustaffa, Nur Ili Hamizah; Amil, Norhaniza; Khan, Md Firoz; Latif, Mohd Talib

    2015-04-01

    This study determined the source contribution of PM2.5 (particulate matter <2.5 μm) in air at three locations on the Malaysian Peninsula. PM2.5 samples were collected using a high volume sampler equipped with quartz filters. Ion chromatography was used to determine the ionic composition of the samples and inductively coupled plasma mass spectrometry was used to determine the concentrations of heavy metals. Principal component analysis with multilinear regressions were used to identify the possible sources of PM2.5. The range of PM2.5 was between 10 ± 3 and 30 ± 7 µg m(-3). Sulfate (SO4 (2-)) was the major ionic compound detected and zinc was found to dominate the heavy metals. Source apportionment analysis revealed that motor vehicle and soil dust dominated the composition of PM2.5 in the urban area. Domestic waste combustion dominated in the suburban area, while biomass burning dominated in the rural area.

  16. Locating Sensors for Detecting Source-to-Target Patterns of Special Nuclear Material Smuggling: A Spatial Information Theoretic Approach

    PubMed Central

    Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

    2010-01-01

    In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy. PMID:22163641

  17. Locating sensors for detecting source-to-target patterns of special nuclear material smuggling: a spatial information theoretic approach.

    PubMed

    Przybyla, Jay; Taylor, Jeffrey; Zhou, Xuesong

    2010-01-01

    In this paper, a spatial information-theoretic model is proposed to locate sensors for detecting source-to-target patterns of special nuclear material (SNM) smuggling. In order to ship the nuclear materials from a source location with SNM production to a target city, the smugglers must employ global and domestic logistics systems. This paper focuses on locating a limited set of fixed and mobile radiation sensors in a transportation network, with the intent to maximize the expected information gain and minimize the estimation error for the subsequent nuclear material detection stage. A Kalman filtering-based framework is adapted to assist the decision-maker in quantifying the network-wide information gain and SNM flow estimation accuracy.

  18. Reconstruction of source location in a network of gravitational wave interferometric detectors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cavalier, Fabien; Barsuglia, Matteo; Bizouard, Marie-Anne

    2006-10-15

    This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a {chi}{sup 2} minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructedmore » one is about 1 deg. . We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 deg. on the source direction can be reached for 99% of the sky.« less

  19. Bayesian inverse modeling and source location of an unintended 131I release in Europe in the fall of 2011

    NASA Astrophysics Data System (ADS)

    Tichý, Ondřej; Šmídl, Václav; Hofman, Radek; Šindelářová, Kateřina; Hýža, Miroslav; Stohl, Andreas

    2017-10-01

    In the fall of 2011, iodine-131 (131I) was detected at several radionuclide monitoring stations in central Europe. After investigation, the International Atomic Energy Agency (IAEA) was informed by Hungarian authorities that 131I was released from the Institute of Isotopes Ltd. in Budapest, Hungary. It was reported that a total activity of 342 GBq of 131I was emitted between 8 September and 16 November 2011. In this study, we use the ambient concentration measurements of 131I to determine the location of the release as well as its magnitude and temporal variation. As the location of the release and an estimate of the source strength became eventually known, this accident represents a realistic test case for inversion models. For our source reconstruction, we use no prior knowledge. Instead, we estimate the source location and emission variation using only the available 131I measurements. Subsequently, we use the partial information about the source term available from the Hungarian authorities for validation of our results. For the source determination, we first perform backward runs of atmospheric transport models and obtain source-receptor sensitivity (SRS) matrices for each grid cell of our study domain. We use two dispersion models, FLEXPART and Hysplit, driven with meteorological analysis data from the global forecast system (GFS) and from European Centre for Medium-range Weather Forecasts (ECMWF) weather forecast models. Second, we use a recently developed inverse method, least-squares with adaptive prior covariance (LS-APC), to determine the 131I emissions and their temporal variation from the measurements and computed SRS matrices. For each grid cell of our simulation domain, we evaluate the probability that the release was generated in that cell using Bayesian model selection. The model selection procedure also provides information about the most suitable dispersion model for the source term reconstruction. Third, we select the most probable location of

  20. Revision of earthquake hypocentre locations in global bulletin data sets using source-specific station terms

    NASA Astrophysics Data System (ADS)

    Nooshiri, Nima; Saul, Joachim; Heimann, Sebastian; Tilmann, Frederik; Dahm, Torsten

    2017-02-01

    Global earthquake locations are often associated with very large systematic travel-time residuals even for clear arrivals, especially for regional and near-regional stations in subduction zones because of their strongly heterogeneous velocity structure. Travel-time corrections can drastically reduce travel-time residuals at regional stations and, in consequence, improve the relative location accuracy. We have extended the shrinking-box source-specific station terms technique to regional and teleseismic distances and adopted the algorithm for probabilistic, nonlinear, global-search location. We evaluated the potential of the method to compute precise relative hypocentre locations on a global scale. The method has been applied to two specific test regions using existing P- and pP-phase picks. The first data set consists of 3103 events along the Chilean margin and the second one comprises 1680 earthquakes in the Tonga-Fiji subduction zone. Pick data were obtained from the GEOFON earthquake bulletin, produced using data from all available, global station networks. A set of timing corrections varying as a function of source position was calculated for each seismic station. In this way, we could correct the systematic errors introduced into the locations by the inaccuracies in the assumed velocity structure without explicitly solving for a velocity model. Residual statistics show that the median absolute deviation of the travel-time residuals is reduced by 40-60 per cent at regional distances, where the velocity anomalies are strong. Moreover, the spread of the travel-time residuals decreased by ˜20 per cent at teleseismic distances (>28°). Furthermore, strong variations in initial residuals as a function of recording distance are smoothed out in the final residuals. The relocated catalogues exhibit less scattered locations in depth and sharper images of the seismicity associated with the subducting slabs. Comparison with a high-resolution local catalogue reveals that

  1. Microseismic response characteristics modeling and locating of underground water supply pipe leak

    NASA Astrophysics Data System (ADS)

    Wang, J.; Liu, J.

    2015-12-01

    In traditional methods of pipeline leak location, geophones must be located on the pipe wall. If the exact location of the pipeline is unknown, the leaks cannot be identified accurately. To solve this problem, taking into account the characteristics of the pipeline leak, we propose a continuous random seismic source model and construct geological models to investigate the proposed method for locating underground pipeline leaks. Based on two dimensional (2D) viscoacoustic equations and the staggered grid finite-difference (FD) algorithm, the microseismic wave field generated by a leaking pipe is modeled. Cross-correlation analysis and the simulated annealing (SA) algorithm were utilized to obtain the time difference and the leak location. We also analyze and discuss the effect of the number of recorded traces, the survey layout, and the offset and interval of the traces on the accuracy of the estimated location. The preliminary results of the simulation and data field experiment indicate that (1) a continuous random source can realistically represent the leak microseismic wave field in a simulation using 2D visco-acoustic equations and a staggered grid FD algorithm. (2) The cross-correlation method is effective for calculating the time difference of the direct wave relative to the reference trace. However, outside the refraction blind zone, the accuracy of the time difference is reduced by the effects of the refracted wave. (3) The acquisition method of time difference based on the microseismic theory and SA algorithm has a great potential for locating leaks from underground pipelines from an array located on the ground surface. Keywords: Viscoacoustic finite-difference simulation; continuous random source; simulated annealing algorithm; pipeline leak location

  2. Revision of earthquake hypocenter locations in GEOFON bulletin data using global source-specific station terms technique

    NASA Astrophysics Data System (ADS)

    Nooshiri, N.; Saul, J.; Heimann, S.; Tilmann, F. J.; Dahm, T.

    2015-12-01

    The use of a 1D velocity model for seismic event location is often associated with significant travel-time residuals. Particularly for regional stations in subduction zones, where the velocity structure strongly deviates from the assumed 1D model, residuals of up to ±10 seconds are observed even for clear arrivals, which leads to strongly biased locations. In fact, due to mostly regional travel-time anomalies, arrival times at regional stations do not match the location obtained with teleseismic picks, and vice versa. If the earthquake is weak and only recorded regionally, or if fast locations based on regional stations are needed, the location may be far off the corresponding teleseismic location. In this case, implementation of travel-time corrections may leads to a reduction of the travel-time residuals at regional stations and, in consequence, significantly improve the relative location accuracy. Here, we have extended the source-specific station terms (SSST) technique to regional and teleseismic distances and adopted the algorithm for probabilistic, non-linear, global-search earthquake location. The method has been applied to specific test regions using P and pP phases from the GEOFON bulletin data for all available station networks. By using this method, a set of timing corrections has been calculated for each station varying as a function of source position. In this way, an attempt is made to correct for the systematic errors, introduced by limitations and inaccuracies in the assumed velocity structure, without solving for a new earth model itself. In this presentation, we draw on examples of the application of this global SSST technique to relocate earthquakes from the Tonga-Fiji subduction zone and from the Chilean margin. Our results have been showing a considerable decrease of the root-mean-square (RMS) residual in earthquake location final catalogs, a major reduction of the median absolute deviation (MAD) of the travel

  3. Time-reversal imaging techniques applied to tremor waveforms near Cholame, California to locate tectonic tremor

    NASA Astrophysics Data System (ADS)

    Horstmann, T.; Harrington, R. M.; Cochran, E. S.

    2012-12-01

    Thurber et al. (2006) interpolated to a grid spacing of 50 m. Such grid spacing corresponds to frequencies of up to 8 Hz, which is suitable to calculate the wave propagation of tremor. Our dataset contains continuous broadband data from 13 STS-2 seismometers deployed from May 2010 to July 2011 along the Cholame segment of the San Andreas Fault as well as data from the HRSN and PBO networks. Initial synthetic results from tests on a 2D plane using a line of 15 receivers suggest that we are able to recover accurate event locations to within 100 m horizontally and 300 m depth. We conduct additional synthetic tests to determine the influence of signal-to-noise ratio, number of stations used, and the uncertainty in the velocity model on the location result by adding noise to the seismograms and perturbations to the velocity model. Preliminary results show accurate show location results to within 400 m with a median signal-to-noise ratio of 3.5 and 5% perturbations in the velocity model. The next steps will entail performing the synthetic tests on the 3D velocity model, and applying the method to tremor waveforms. Furthermore, we will determine the spatial and temporal distribution of the source locations and compare our results to those by Sumy and others.

  4. Detection, localization and classification of multiple dipole-like magnetic sources using magnetic gradient tensor data

    NASA Astrophysics Data System (ADS)

    Gang, Yin; Yingtang, Zhang; Hongbo, Fan; Zhining, Li; Guoquan, Ren

    2016-05-01

    We have developed a method for automatic detection, localization and classification (DLC) of multiple dipole sources using magnetic gradient tensor data. First, we define modified tilt angles to estimate the approximate horizontal locations of the multiple dipole-like magnetic sources simultaneously and detect the number of magnetic sources using a fixed threshold. Secondly, based on the isotropy of the normalized source strength (NSS) response of a dipole, we obtain accurate horizontal locations of the dipoles. Then the vertical locations are calculated using magnitude magnetic transforms of magnetic gradient tensor data. Finally, we invert for the magnetic moments of the sources using the measured magnetic gradient tensor data and forward model. Synthetic and field data sets demonstrate effectiveness and practicality of the proposed method.

  5. Double point source W-phase inversion: Real-time implementation and automated model selection

    USGS Publications Warehouse

    Nealy, Jennifer; Hayes, Gavin

    2015-01-01

    Rapid and accurate characterization of an earthquake source is an extremely important and ever evolving field of research. Within this field, source inversion of the W-phase has recently been shown to be an effective technique, which can be efficiently implemented in real-time. An extension to the W-phase source inversion is presented in which two point sources are derived to better characterize complex earthquakes. A single source inversion followed by a double point source inversion with centroid locations fixed at the single source solution location can be efficiently run as part of earthquake monitoring network operational procedures. In order to determine the most appropriate solution, i.e., whether an earthquake is most appropriately described by a single source or a double source, an Akaike information criterion (AIC) test is performed. Analyses of all earthquakes of magnitude 7.5 and greater occurring since January 2000 were performed with extended analyses of the September 29, 2009 magnitude 8.1 Samoa earthquake and the April 19, 2014 magnitude 7.5 Papua New Guinea earthquake. The AIC test is shown to be able to accurately select the most appropriate model and the selected W-phase inversion is shown to yield reliable solutions that match published analyses of the same events.

  6. The source location of mantle plumes from 3D spherical models of mantle convection

    NASA Astrophysics Data System (ADS)

    Li, Mingming; Zhong, Shijie

    2017-11-01

    Mantle plumes are thought to originate from thermal boundary layers such as Earth's core-mantle boundary (CMB), and may cause intraplate volcanism such as large igneous provinces (LIPs) on the Earth's surface. Previous studies showed that the original eruption sites of deep-sourced LIPs for the last 200 Myrs occur mostly above the margins of the seismically-observed large low shear velocity provinces (LLSVPs) in the lowermost mantle. However, the mechanism that leads to the distribution of the LIPs is not clear. The location of the LIPs is largely determined by the source location of mantle plumes, but the question is under what conditions mantle plumes form outside, at the edges, or above the middle of LLSVPs. Here, we perform 3D geodynamic calculations and theoretical analyses to study the plume source location in the lowermost mantle. We find that a factor of five decrease of thermal expansivity and a factor of two increase of thermal diffusivity from the surface to the CMB, which are consistent with mineral physics studies, significantly reduce the number of mantle plumes forming far outside of thermochemical piles (i.e., LLSVPs). An increase of mantle viscosity in the lowermost mantle also reduces number of plumes far outside of piles. In addition, we find that strong plumes preferentially form at/near the edges of piles and are generally hotter than that forming on top of piles, which may explain the observations that most LIPs occur above LLSVP margins. However, some plumes originated at pile edges can later appear above the middle of piles due to lateral movement of the plumes and piles and morphologic changes of the piles. ∼65-70% strong plumes are found within 10 degrees from pile edges in our models. Although plate motion exerts significant controls over the large-scale mantle convection in the lower mantle, mantle plume formation at the CMB remains largely controlled by thermal boundary layer instability which makes it difficult to predict geographic

  7. Precise tremor source locations and amplitude variations along the lower-crustal central San Andreas Fault

    USGS Publications Warehouse

    Shelly, David R.; Hardebeck, Jeanne L.

    2010-01-01

    We precisely locate 88 tremor families along the central San Andreas Fault using a 3D velocity model and numerous P and S wave arrival times estimated from seismogram stacks of up to 400 events per tremor family. Maximum tremor amplitudes vary along the fault by at least a factor of 7, with by far the strongest sources along a 25 km section of the fault southeast of Parkfield. We also identify many weaker tremor families, which have largely escaped prior detection. Together, these sources extend 150 km along the fault, beneath creeping, transitional, and locked sections of the upper crustal fault. Depths are mostly between 18 and 28 km, in the lower crust. Epicenters are concentrated within 3 km of the surface trace, implying a nearly vertical fault. A prominent gap in detectible activity is located directly beneath the region of maximum slip in the 2004 magnitude 6.0 Parkfield earthquake.

  8. Classification of event location using matched filters via on-floor accelerometers

    NASA Astrophysics Data System (ADS)

    Woolard, Americo G.; Malladi, V. V. N. Sriram; Alajlouni, Sa'ed; Tarazaga, Pablo A.

    2017-04-01

    Recent years have shown prolific advancements in smart infrastructures, allowing buildings of the modern world to interact with their occupants. One of the sought-after attributes of smart buildings is the ability to provide unobtrusive, indoor localization of occupants. The ability to locate occupants indoors can provide a broad range of benefits in areas such as security, emergency response, and resource management. Recent research has shown promising results in occupant building localization, although there is still significant room for improvement. This study presents a passive, small-scale localization system using accelerometers placed around the edges of a small area in an active building environment. The area is discretized into a grid of small squares, and vibration measurements are processed using a pattern matching approach that estimates the location of the source. Vibration measurements are produced with ball-drops, hammer-strikes, and footsteps as the sources of the floor excitation. The developed approach uses matched filters based on a reference data set, and the location is classified using a nearest-neighbor search. This approach detects the appropriate location of impact-like sources i.e. the ball-drops and hammer-strikes with a 100% accuracy. However, this accuracy reduces to 56% for footsteps, with the average localization results being within 0.6 m (α = 0.05) from the true source location. While requiring a reference data set can make this method difficult to implement on a large scale, it may be used to provide accurate localization abilities in areas where training data is readily obtainable. This exploratory work seeks to examine the feasibility of the matched filter and nearest neighbor search approach for footstep and event localization in a small, instrumented area within a multi-story building.

  9. Long Period (LP) volcanic earthquake source location at Merapi volcano by using dense array technics

    NASA Astrophysics Data System (ADS)

    Metaxian, Jean Philippe; Budi Santoso, Agus; Laurin, Antoine; Subandriyo, Subandriyo; Widyoyudo, Wiku; Arshab, Ghofar

    2015-04-01

    Since 2010, Merapi shows unusual activity compared to last decades. Powerful phreatic explosions are observed; some of them are preceded by LP signals. In the literature, LP seismicity is thought to be originated within the fluid, and therefore to be representative of the pressurization state of the volcano plumbing system. Another model suggests that LP events are caused by slow, quasi-brittle, low stress-drop failure driven by transient upper-edifice deformations. Knowledge of the spatial distribution of LP events is fundamental for better understanding the physical processes occurring in the conduit, as well as for the monitoring and the improvement of eruption forecasting. LP events recorded at Merapi have a spectral content dominated by frequencies between 0.8 and 3 Hz. To locate the source of these events, we installed a seismic antenna composed of 4 broadband CMG-6TD Güralp stations. This network has an aperture of 300 m. It is located on the site of Pasarbubar, between 500 and 800 m from the crater rim. Two multi-parameter stations (seismic, tiltmeter, S-P) located in the same area, equipped with broadband CMG-40T Güralp sensors may also be used to complete the data of the antenna. The source of LP events is located by using different approaches. In the first one, we used a method based on the measurement of the time delays between the early beginnings of LP events for each array receiver. The observed differences of time delays obtained for each pair of receivers are compared to theoretical values calculated from the travel times computed between grid nodes, which are positioned in the structure, and each receiver. In a second approach, we estimate the slowness vector by using MUSIC algorithm applied to 3-components data. From the slowness vector, we deduce the back-azimuth and the incident angle, which give an estimation of LP source depth in the conduit. This work is part of the Domerapi project funded by French Agence Nationale de la Recherche (https

  10. Relation Between Sprite Distribution and Source Locations of VHF Pulses Derived From JEM- GLIMS Measurements

    NASA Astrophysics Data System (ADS)

    Sato, Mitsuteru; Mihara, Masahiro; Ushio, Tomoo; Morimoto, Takeshi; Kikuchi, Hiroshi; Adachi, Toru; Suzuki, Makoto; Yamazaki, Atsushi; Takahashi, Yukihiro

    2015-04-01

    JEM-GLIMS is continuing the comprehensive nadir observations of lightning and TLEs using optical instruments and electromagnetic wave receivers since November 2012. For the period between November 20, 2012 and November 30, 2014, JEM-GLIMS succeeded in detecting 5,048 lightning events. A total of 567 events in 5,048 lightning events were TLEs, which were mostly elves events. To identify the sprite occurrences from the transient optical flash data, it is necessary to perform the following data analysis: (1) a subtraction of the appropriately scaled wideband camera data from the narrowband camera data; (2) a calculation of intensity ratio between different spectrophotometer channels; and (3) an estimation of the polarization and CMC for the parent CG discharges using ground-based ELF measurement data. From a synthetic comparison of these results, it is confirmed that JEM-GLISM succeeded in detecting sprite events. The VHF receiver (VITF) onboard JEM-GLIMS uses two patch-type antennas separated by a 1.6-m interval and can detect VHF pulses emitted by lightning discharges in the 70-100 MHz frequency range. Using both an interferometric technique and a group delay technique, we can estimate the source locations of VHF pulses excited by lightning discharges. In the event detected at 06:41:15.68565 UT on June 12, 2014 over central North America, sprite was distributed with a horizontal displacement of 20 km from the peak location of the parent lightning emission. In this event, a total of 180 VHF pulses were simultaneously detected by VITF. From the detailed data analysis of these VHF pulse data, it is found that the majority of the source locations were placed near the area of the dim lightning emission, which may imply that the VHF pulses were associated with the in-cloud lightning current. At the presentation, we will show detailed comparison between the spatiotemporal characteristics of sprite emission and source locations of VHF pulses excited by the parent lightning

  11. Affective attitudes to face images associated with intracerebral EEG source location before face viewing.

    PubMed

    Pizzagalli, D; Koenig, T; Regard, M; Lehmann, D

    1999-01-01

    We investigated whether different, personality-related affective attitudes are associated with different brain electric field (EEG) sources before any emotional challenge (stimulus exposure). A 27-channel EEG was recorded in 15 subjects during eyes-closed resting. After recording, subjects rated 32 images of human faces for affective appeal. The subjects in the first (i.e., most negative) and fourth (i.e., most positive) quartile of general affective attitude were further analyzed. The EEG data (mean=25+/-4. 8 s/subject) were subjected to frequency-domain model dipole source analysis (FFT-Dipole-Approximation), resulting in 3-dimensional intracerebral source locations and strengths for the delta-theta, alpha, and beta EEG frequency band, and for the full range (1.5-30 Hz) band. Subjects with negative attitude (compared to those with positive attitude) showed the following source locations: more inferior for all frequency bands, more anterior for the delta-theta band, more posterior and more right for the alpha, beta and 1.5-30 Hz bands. One year later, the subjects were asked to rate the face images again. The rating scores for the same face images were highly correlated for all subjects, and original and retest affective mean attitude was highly correlated across subjects. The present results show that subjects with different affective attitudes to face images had different active, cerebral, neural populations in a task-free condition prior to viewing the images. We conclude that the brain functional state which implements affective attitude towards face images as a personality feature exists without elicitors, as a continuously present, dynamic feature of brain functioning. Copyright 1999 Elsevier Science B.V.

  12. 40 CFR 55.14 - Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Requirements that apply to OCS sources... REGULATIONS § 55.14 Requirements that apply to OCS sources located within 25 miles of States' seaward boundaries, by State. (a) The requirements of this section shall apply to OCS sources as set forth below. In...

  13. UTILIZING RESULTS FROM INSAR TO DEVELOP SEISMIC LOCATION BENCHMARKS AND IMPLICATIONS FOR SEISMIC SOURCE STUDIES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    M. BEGNAUD; ET AL

    2000-09-01

    Obtaining accurate seismic event locations is one of the most important goals for monitoring detonations of underground nuclear teats. This is a particular challenge at small magnitudes where the number of recording stations may be less than 20. Although many different procedures are being developed to improve seismic location, most procedures suffer from inadequate testing against accurate information about a seismic event. Events with well-defined attributes, such as latitude, longitude, depth and origin time, are commonly referred to as ground truth (GT). Ground truth comes in many forms and with many different levels of accuracy. Interferometric Synthetic Aperture Radar (InSAR)more » can provide independent and accurate information (ground truth) regarding ground surface deformation and/or rupture. Relating surface deformation to seismic events is trivial when events are large and create a significant surface rupture, such as for the M{sub w} = 7.5 event that occurred in the remote northern region of the Tibetan plateau in 1997. The event, which was a vertical strike slip even appeared anomalous in nature due to the lack of large aftershocks and had an associated surface rupture of over 180 km that was identified and modeled using InSAR. The east-west orientation of the fault rupture provides excellent ground truth for latitude, but is of limited use for longitude. However, a secondary rupture occurred 50 km south of the main shock rupture trace that can provide ground truth with accuracy within 5 km. The smaller, 5-km-long secondary rupture presents a challenge for relating the deformation to a seismic event. The rupture is believed to have a thrust mechanism; the dip of the fimdt allows for some separation between the secondary rupture trace and its associated event epicenter, although not as much as is currently observed from catalog locations. Few events within the time period of the InSAR analysis are candidates for the secondary rupture. Of these, we

  14. Simultaneous EEG and MEG source reconstruction in sparse electromagnetic source imaging.

    PubMed

    Ding, Lei; Yuan, Han

    2013-04-01

    Electroencephalography (EEG) and magnetoencephalography (MEG) have different sensitivities to differently configured brain activations, making them complimentary in providing independent information for better detection and inverse reconstruction of brain sources. In the present study, we developed an integrative approach, which integrates a novel sparse electromagnetic source imaging method, i.e., variation-based cortical current density (VB-SCCD), together with the combined use of EEG and MEG data in reconstructing complex brain activity. To perform simultaneous analysis of multimodal data, we proposed to normalize EEG and MEG signals according to their individual noise levels to create unit-free measures. Our Monte Carlo simulations demonstrated that this integrative approach is capable of reconstructing complex cortical brain activations (up to 10 simultaneously activated and randomly located sources). Results from experimental data showed that complex brain activations evoked in a face recognition task were successfully reconstructed using the integrative approach, which were consistent with other research findings and validated by independent data from functional magnetic resonance imaging using the same stimulus protocol. Reconstructed cortical brain activations from both simulations and experimental data provided precise source localizations as well as accurate spatial extents of localized sources. In comparison with studies using EEG or MEG alone, the performance of cortical source reconstructions using combined EEG and MEG was significantly improved. We demonstrated that this new sparse ESI methodology with integrated analysis of EEG and MEG data could accurately probe spatiotemporal processes of complex human brain activations. This is promising for noninvasively studying large-scale brain networks of high clinical and scientific significance. Copyright © 2011 Wiley Periodicals, Inc.

  15. Real-Time Localization of Moving Dipole Sources for Tracking Multiple Free-Swimming Weakly Electric Fish

    PubMed Central

    Jun, James Jaeyoon; Longtin, André; Maler, Leonard

    2013-01-01

    In order to survive, animals must quickly and accurately locate prey, predators, and conspecifics using the signals they generate. The signal source location can be estimated using multiple detectors and the inverse relationship between the received signal intensity (RSI) and the distance, but difficulty of the source localization increases if there is an additional dependence on the orientation of a signal source. In such cases, the signal source could be approximated as an ideal dipole for simplification. Based on a theoretical model, the RSI can be directly predicted from a known dipole location; but estimating a dipole location from RSIs has no direct analytical solution. Here, we propose an efficient solution to the dipole localization problem by using a lookup table (LUT) to store RSIs predicted by our theoretically derived dipole model at many possible dipole positions and orientations. For a given set of RSIs measured at multiple detectors, our algorithm found a dipole location having the closest matching normalized RSIs from the LUT, and further refined the location at higher resolution. Studying the natural behavior of weakly electric fish (WEF) requires efficiently computing their location and the temporal pattern of their electric signals over extended periods. Our dipole localization method was successfully applied to track single or multiple freely swimming WEF in shallow water in real-time, as each fish could be closely approximated by an ideal current dipole in two dimensions. Our optimized search algorithm found the animal’s positions, orientations, and tail-bending angles quickly and accurately under various conditions, without the need for calibrating individual-specific parameters. Our dipole localization method is directly applicable to studying the role of active sensing during spatial navigation, or social interactions between multiple WEF. Furthermore, our method could be extended to other application areas involving dipole source

  16. Source Repeatability of Time-Lapse Offset VSP Surveys for Monitoring CO2 Injection

    NASA Astrophysics Data System (ADS)

    Zhang, Z.; Huang, L.; Rutledge, J. T.; Denli, H.; Zhang, H.; McPherson, B. J.; Grigg, R.

    2009-12-01

    Time-lapse vertical seismic profiling (VSP) surveys have the potential to remotely track the migration of injected CO2 within a geologic formation. To accurately detect small changes due to CO2 injection, the sources of time-lapse VSP surveys must be located exactly at the same positions. However, in practice, the source locations can vary from one survey to another survey. Our numerical simulations demonstrate that a variation of a few meters in the VSP source locations can result in significant changes in time-lapse seismograms. To address the source repeatability issue, we apply double-difference tomography to downgoing waves of time-lapse offset VSP data to invert for the source locations and the velocity structures simultaneously. In collaboration with Resolute Natural Resources, Navajo National Oil and Gas Company, and the Southwest Regional Partnership on Carbon Sequestration under the support of the U.S. Department of Energy’s National Energy Technology Laboratory, one baseline and two repeat offset VSP datasets were acquired in 2007-2009 for monitoring CO2 injection at the Aneth oil field in Utah. A cemented geophone string was used to acquire the data for one zero-offset and seven offset source locations. During the data acquisition, there was some uncertainty in the repeatability of the source locations relative to the baseline survey. Our double-difference tomography results of the Aneth time-lapse VSP data show that the source locations for different surveys are separated up to a few meters. Accounting for these source location variations during VSP data analysis will improve reliability of time-lapse VSP monitoring.

  17. Generating Accurate 3d Models of Architectural Heritage Structures Using Low-Cost Camera and Open Source Algorithms

    NASA Astrophysics Data System (ADS)

    Zacharek, M.; Delis, P.; Kedzierski, M.; Fryskowska, A.

    2017-05-01

    These studies have been conductedusing non-metric digital camera and dense image matching algorithms, as non-contact methods of creating monuments documentation.In order toprocess the imagery, few open-source software and algorithms of generating adense point cloud from images have been executed. In the research, the OSM Bundler, VisualSFM software, and web application ARC3D were used. Images obtained for each of the investigated objects were processed using those applications, and then dense point clouds and textured 3D models were created. As a result of post-processing, obtained models were filtered and scaled.The research showedthat even using the open-source software it is possible toobtain accurate 3D models of structures (with an accuracy of a few centimeters), but for the purpose of documentation and conservation of cultural and historical heritage, such accuracy can be insufficient.

  18. Are pain location and physical examinations useful in locating a tear site of the rotator cuff?

    PubMed

    Itoi, Eiji; Minagawa, Hiroshi; Yamamoto, Nobuyuki; Seki, Nobutoshi; Abe, Hidekazu

    2006-02-01

    Pain is the most common symptom of patients with rotator cuff tendinopathy, but little is known about the relationship between the site of pain and the site of cuff pathologic lesions. Also, accuracies of physical examinations used to locate a tear by assessing the muscle strength seem to be affected by the threshold for muscle weakness, but no studies have been reported regarding the efficacies of physical examinations in reference to their threshold. Pain location is useful in locating a tear site. Efficacies of physical examinations to evaluate the function of the cuff muscles depend on the threshold for muscle weakness. Case series; Level of evidence, 4. The authors retrospectively reviewed the clinical charts of 160 shoulders of 149 patients (mean age, 53 years) with either rotator cuff tears (140 shoulders) or cuff tendinitis (20 shoulders). The location of pain was recorded on a standardized form with 6 different areas. The diagnostic accuracies of the following tests were assessed with various thresholds for muscle weakness: supraspinatus test, the external rotation strength test, and the lift-off test. Lateral and anterior portions of the shoulder were the most common sites of pain regardless of existence of tear or tear location. The supraspinatus test was most accurate when it was assessed to have positive results with the muscle strength less than manual muscle testing grade 5, whereas the lift-off test was most accurate with a threshold less than grade 3. The external rotation strength test was most accurate with a threshold of less than grade 4+. The authors conclude that pain location is not useful in locating the site of a tear, whereas the physical examinations aiming to locate the tear site are clinically useful when assessed to have positive results with appropriate threshold for muscle weakness.

  19. Application of near real-time radial semblance to locate the shallow magmatic conduit at Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Dawson, P.; Whilldin, D.; Chouet, B.

    2004-01-01

    Radial Semblance is applied to broadband seismic network data to provide source locations of Very-Long-Period (VLP) seismic energy in near real time. With an efficient algorithm and adequate network coverage, accurate source locations of VLP energy are derived to quickly locate the shallow magmatic conduit system at Kilauea Volcano, Hawaii. During a restart in magma flow following a brief pause in the current eruption, the shallow magmatic conduit is pressurized, resulting in elastic radiation from various parts of the conduit system. A steeply dipping distribution of VLP hypocenters outlines a region extending from sea level to about 550 m elevation below and just east of the Halemaumau Pit Crater. The distinct hypocenters suggest the shallow plumbing system beneath Halemaumau consists of a complex plexus of sills and dikes. An unconstrained location for a section of the conduit is also observed beneath the region between Kilauea Caldera and Kilauea Iki Crater.

  20. Investigation of source location determination from Magsat magnetic anomalies: The Euler method approach

    NASA Technical Reports Server (NTRS)

    Ravat, Dhananjay

    1996-01-01

    The applicability of the Euler method of source location determination was investigated on several model situations pertinent to satellite-data scale situations as well as Magsat data of Europe. Our investigations enabled us to understand the end-member cases for which the Euler method will work with the present satellite magnetic data and also the cases for which the assumptions implicit in the Euler method will not be met by the present satellite magnetic data. These results have been presented in one invited lecture at the Indo-US workshop on Geomagnetism in Studies of the Earth's Interior in August 1994 in Pune, India, and at one presentation at the 21st General Assembly of the IUGG in July 1995 in Boulder, CO. A new method, called Anomaly Attenuation Rate (AAR) Method (based on the Euler method), was developed during this study. This method is scale-independent and is appropriate to locate centroids of semi-compact three dimensional sources of gravity and magnetic anomalies. The method was presented during 1996 Spring AGU meeting and a manuscript describing this method is being prepared for its submission to a high-ranking journal. The grant has resulted in 3 papers and presentations at national and international meetings and one manuscript of a paper (to be submitted shortly to a reputable journal).

  1. Location-assured, multifactor authentication on smartphones via LTE communication

    NASA Astrophysics Data System (ADS)

    Kuseler, Torben; Lami, Ihsan A.; Al-Assam, Hisham

    2013-05-01

    With the added security provided by LTE, geographical location has become an important factor for authentication to enhance the security of remote client authentication during mCommerce applications using Smartphones. Tight combination of geographical location with classic authentication factors like PINs/Biometrics in a real-time, remote verification scheme over the LTE layer connection assures the authenticator about the client itself (via PIN/biometric) as well as the client's current location, thus defines the important aspects of "who", "when", and "where" of the authentication attempt without eaves dropping or man on the middle attacks. To securely integrate location as an authentication factor into the remote authentication scheme, client's location must be verified independently, i.e. the authenticator should not solely rely on the location determined on and reported by the client's Smartphone. The latest wireless data communication technology for mobile phones (4G LTE, Long-Term Evolution), recently being rolled out in various networks, can be employed to enhance this location-factor requirement of independent location verification. LTE's Control Plane LBS provisions, when integrated with user-based authentication and independent source of localisation factors ensures secure efficient, continuous location tracking of the Smartphone. This feature can be performed during normal operation of the LTE-based communication between client and network operator resulting in the authenticator being able to verify the client's claimed location more securely and accurately. Trials and experiments show that such algorithm implementation is viable for nowadays Smartphone-based banking via LTE communication.

  2. 40 CFR Table 2d to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary RICE Located at Area Sources of HAP...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Ignition Stationary RICE Located at Area Sources of HAP Emissions 2d Table 2d to Subpart ZZZZ of Part 63... Stationary RICE Located at Area Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must comply with the following emission and operating limitations for existing compression ignition stationary RICE...

  3. Effects of sound source location and direction on acoustic parameters in Japanese churches.

    PubMed

    Soeta, Yoshiharu; Ito, Ken; Shimokura, Ryota; Sato, Shin-ichi; Ohsawa, Tomohiro; Ando, Yoichi

    2012-02-01

    In 1965, the Catholic Church liturgy changed to allow priests to face the congregation. Whereas Church tradition, teaching, and participation have been much discussed with respect to priest orientation at Mass, the acoustical changes in this regard have not yet been examined scientifically. To discuss acoustic desired within churches, it is necessary to know the acoustical characteristics appropriate for each phase of the liturgy. In this study, acoustic measurements were taken at various source locations and directions using both old and new liturgies performed in Japanese churches. A directional loudspeaker was used as the source to provide vocal and organ acoustic fields, and impulse responses were measured. Various acoustical parameters such as reverberation time and early decay time were analyzed. The speech transmission index was higher for the new Catholic liturgy, suggesting that the change in liturgy has improved speech intelligibility. Moreover, the interaural cross-correlation coefficient and early lateral energy fraction were higher and lower, respectively, suggesting that the change in liturgy has made the apparent source width smaller. © 2012 Acoustical Society of America

  4. Locating hazardous gas leaks in the atmosphere via modified genetic, MCMC and particle swarm optimization algorithms

    NASA Astrophysics Data System (ADS)

    Wang, Ji; Zhang, Ru; Yan, Yuting; Dong, Xiaoqiang; Li, Jun Ming

    2017-05-01

    Hazardous gas leaks in the atmosphere can cause significant economic losses in addition to environmental hazards, such as fires and explosions. A three-stage hazardous gas leak source localization method was developed that uses movable and stationary gas concentration sensors. The method calculates a preliminary source inversion with a modified genetic algorithm (MGA) and has the potential to crossover with eliminated individuals from the population, following the selection of the best candidate. The method then determines a search zone using Markov Chain Monte Carlo (MCMC) sampling, utilizing a partial evaluation strategy. The leak source is then accurately localized using a modified guaranteed convergence particle swarm optimization algorithm with several bad-performing individuals, following selection of the most successful individual with dynamic updates. The first two stages are based on data collected by motionless sensors, and the last stage is based on data from movable robots with sensors. The measurement error adaptability and the effect of the leak source location were analyzed. The test results showed that this three-stage localization process can localize a leak source within 1.0 m of the source for different leak source locations, with measurement error standard deviation smaller than 2.0.

  5. Fuel from wastewater : harnessing a potential energy source in Canada through the co-location of algae biofuel production to sources of effluent, heat and CO2.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Passell, Howard David; Whalen, Jake; Pienkos, Philip P.

    2010-12-01

    Sandia National Laboratories is collaborating with the National Research Council (NRC) Canada and the National Renewable Energy Laboratory (NREL) to develop a decision-support model that will evaluate the tradeoffs associated with high-latitude algae biofuel production co-located with wastewater, CO2, and waste heat. This project helps Canada meet its goal of diversifying fuel sources with algae-based biofuels. The biofuel production will provide a wide range of benefits including wastewater treatment, CO2 reuse and reduction of demand for fossil-based fuels. The higher energy density in algae-based fuels gives them an advantage over crop-based biofuels as the 'production' footprint required is much less,more » resulting in less water consumed and little, if any conversion of agricultural land from food to fuel production. Besides being a potential source for liquid fuel, algae have the potential to be used to generate electricity through the burning of dried biomass, or anaerobically digested to generate methane for electricity production. Co-locating algae production with waste streams may be crucial for making algae an economically valuable fuel source, and will certainly improve its overall ecological sustainability. The modeling process will address these questions, and others that are important to the use of water for energy production: What are the locations where all resources are co-located, and what volumes of algal biomass and oil can be produced there? In locations where co-location does not occur, what resources should be transported, and how far, while maintaining economic viability? This work is being funded through the U.S. Department of Energy (DOE) Biomass Program Office of Energy Efficiency and Renewable Energy, and is part of a larger collaborative effort that includes sampling, strain isolation, strain characterization and cultivation being performed by the NREL and Canada's NRC. Results from the NREL / NRC collaboration including specific

  6. Locating single-point sources from arrival times containing large picking errors (LPEs): the virtual field optimization method (VFOM)

    NASA Astrophysics Data System (ADS)

    Li, Xi-Bing; Wang, Ze-Wei; Dong, Long-Jun

    2016-01-01

    Microseismic monitoring systems using local location techniques tend to be timely, automatic and stable. One basic requirement of these systems is the automatic picking of arrival times. However, arrival times generated by automated techniques always contain large picking errors (LPEs), which may make the location solution unreliable and cause the integrated system to be unstable. To overcome the LPE issue, we propose the virtual field optimization method (VFOM) for locating single-point sources. In contrast to existing approaches, the VFOM optimizes a continuous and virtually established objective function to search the space for the common intersection of the hyperboloids, which is determined by sensor pairs other than the least residual between the model-calculated and measured arrivals. The results of numerical examples and in-site blasts show that the VFOM can obtain more precise and stable solutions than traditional methods when the input data contain LPEs. Furthermore, we discuss the impact of LPEs on objective functions to determine the LPE-tolerant mechanism, velocity sensitivity and stopping criteria of the VFOM. The proposed method is also capable of locating acoustic sources using passive techniques such as passive sonar detection and acoustic emission.

  7. 40 CFR Table 2c to Subpart Zzzz of... - Requirements for Existing Compression Ignition Stationary Rice Located at Major Sources of HAP...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., non-black start CI 500 HP a. Limit concentration of CO in the stationary RICE exhaust to 23 ppmvd or... Ignition Stationary Rice Located at Major Sources of HAP Emissions 2c Table 2c to Subpart ZZZZ of Part 63... Stationary Rice Located at Major Sources of HAP Emissions As stated in §§ 63.6600 and 63.6640, you must...

  8. Extracting Time-Accurate Acceleration Vectors From Nontrivial Accelerometer Arrangements.

    PubMed

    Franck, Jennifer A; Blume, Janet; Crisco, Joseph J; Franck, Christian

    2015-09-01

    Sports-related concussions are of significant concern in many impact sports, and their detection relies on accurate measurements of the head kinematics during impact. Among the most prevalent recording technologies are videography, and more recently, the use of single-axis accelerometers mounted in a helmet, such as the HIT system. Successful extraction of the linear and angular impact accelerations depends on an accurate analysis methodology governed by the equations of motion. Current algorithms are able to estimate the magnitude of acceleration and hit location, but make assumptions about the hit orientation and are often limited in the position and/or orientation of the accelerometers. The newly formulated algorithm presented in this manuscript accurately extracts the full linear and rotational acceleration vectors from a broad arrangement of six single-axis accelerometers directly from the governing set of kinematic equations. The new formulation linearizes the nonlinear centripetal acceleration term with a finite-difference approximation and provides a fast and accurate solution for all six components of acceleration over long time periods (>250 ms). The approximation of the nonlinear centripetal acceleration term provides an accurate computation of the rotational velocity as a function of time and allows for reconstruction of a multiple-impact signal. Furthermore, the algorithm determines the impact location and orientation and can distinguish between glancing, high rotational velocity impacts, or direct impacts through the center of mass. Results are shown for ten simulated impact locations on a headform geometry computed with three different accelerometer configurations in varying degrees of signal noise. Since the algorithm does not require simplifications of the actual impacted geometry, the impact vector, or a specific arrangement of accelerometer orientations, it can be easily applied to many impact investigations in which accurate kinematics need

  9. Optimization of light source parameters in the photodynamic therapy of heterogeneous prostate

    NASA Astrophysics Data System (ADS)

    Li, Jun; Altschuler, Martin D.; Hahn, Stephen M.; Zhu, Timothy C.

    2008-08-01

    The three-dimensional (3D) heterogeneous distributions of optical properties in a patient prostate can now be measured in vivo. Such data can be used to obtain a more accurate light-fluence kernel. (For specified sources and points, the kernel gives the fluence delivered to a point by a source of unit strength.) In turn, the kernel can be used to solve the inverse problem that determines the source strengths needed to deliver a prescribed photodynamic therapy (PDT) dose (or light-fluence) distribution within the prostate (assuming uniform drug concentration). We have developed and tested computational procedures to use the new heterogeneous data to optimize delivered light-fluence. New problems arise, however, in quickly obtaining an accurate kernel following the insertion of interstitial light sources and data acquisition. (1) The light-fluence kernel must be calculated in 3D and separately for each light source, which increases kernel size. (2) An accurate kernel for light scattering in a heterogeneous medium requires ray tracing and volume partitioning, thus significant calculation time. To address these problems, two different kernels were examined and compared for speed of creation and accuracy of dose. Kernels derived more quickly involve simpler algorithms. Our goal is to achieve optimal dose planning with patient-specific heterogeneous optical data applied through accurate kernels, all within clinical times. The optimization process is restricted to accepting the given (interstitially inserted) sources, and determining the best source strengths with which to obtain a prescribed dose. The Cimmino feasibility algorithm is used for this purpose. The dose distribution and source weights obtained for each kernel are analyzed. In clinical use, optimization will also be performed prior to source insertion to obtain initial source positions, source lengths and source weights, but with the assumption of homogeneous optical properties. For this reason, we compare the

  10. A Review of Advancements in Particulate Matter Sampling and Analysis and its Application to Identifying Source Impacts at Receptor Locations

    EPA Science Inventory

    Time-integrated (typically 24-hr) filter-based methods (historical methods) form the underpinning of our understanding of the fate, impact of source emissions at receptor locations (source impacts), and potential health and welfare effects of particulate matter (PM) in air. Over...

  11. Do Skilled Elementary Teachers Hold Scientific Conceptions and Can They Accurately Predict the Type and Source of Students' Preconceptions of Electric Circuits?

    ERIC Educational Resources Information Center

    Lin, Jing-Wen

    2016-01-01

    Holding scientific conceptions and having the ability to accurately predict students' preconceptions are a prerequisite for science teachers to design appropriate constructivist-oriented learning experiences. This study explored the types and sources of students' preconceptions of electric circuits. First, 438 grade 3 (9 years old) students were…

  12. Consumption of added sugars among US children and adults by food purchase location and food source.

    PubMed

    Drewnowski, Adam; Rehm, Colin D

    2014-09-01

    The proposed changes to the Nutrition Facts Label by the US Food and Drug Administration will include information on added sugars for the first time. The objective was to evaluate the sources of added sugars in the diets of a representative sample of US children and adults by food purchase location and food source (eg, food group). This cross-sectional study among 31,035 children, adolescents, and adults aged ≥6 y from the 2003-2004, 2005-2006, 2007-2008, and 2009-2010 NHANES used data from a 24-h dietary recall to evaluate consumption of added sugars. Food locations of origin were identified as stores (supermarket or grocery store), quick-service restaurants/pizza (QSRs), full-service restaurants (FSRs), schools, and others (eg, vending machines or gifts). Added sugars consumption by food purchase location was evaluated by age, family income-to-poverty ratio, and race-ethnicity. Food group sources of added sugars were identified by using the National Cancer Institute food categories. Added sugars accounted for ∼14.1% of total dietary energy. Between 65% and 76% of added sugars came from stores, 6% and 12% from QSRs, and 4% and 6% from FSRs, depending on age. Older adults (aged ≥51 y) obtained a significantly greater proportion of added sugars from stores than did younger adults. Lower-income adults obtained a significantly greater proportion of added sugars from stores than did higher-income adults. Intake of added sugars did not vary by family income among children/adolescents. Soda and energy and sports drinks were the largest food group sources of added sugars (34.4%), followed by grain desserts (12.7%), fruit drinks (8.0%), candy (6.7%), and dairy desserts (5.6%). Most added sugars came from foods obtained from stores. The proposed changes to the Nutrition Facts Label should capture the bulk of added sugars in the US food supply, which suggests that the recommended changes have the potential to reduce added sugars consumption. © 2014 American Society

  13. Improved phase arrival estimate and location for local earthquakes in South Korea

    NASA Astrophysics Data System (ADS)

    Morton, E. A.; Rowe, C. A.; Begnaud, M. L.

    2012-12-01

    The Korean Institute of Geoscience and Mineral Resources (KIGAM) and the Korean Meteorological Agency (KMA) regularly report local (distance < ~1200 km) seismicity recorded with their networks; we obtain preliminary event location estimates as well as waveform data, but no phase arrivals are reported, so the data are not immediately useful for earthquake location. Our goal is to identify seismic events that are sufficiently well-located to provide accurate seismic travel-time information for events within the KIGAM and KMA networks, and also recorded by some regional stations. Toward that end, we are using a combination of manual phase identification and arrival-time picking, with waveform cross-correlation, to cluster events that have occurred in close proximity to one another, which allows for improved phase identification by comparing the highly correlating waveforms. We cross-correlate the known events with one another on 5 seismic stations and cluster events that correlate above a correlation coefficient threshold of 0.7, which reveals few clusters containing few events each. The small number of repeating events suggests that the online catalogs have had mining and quarry blasts removed before publication, as these can contribute significantly to repeating seismic sources in relatively aseismic regions such as South Korea. The dispersed source locations in our catalog, however, are ideal for seismic velocity modeling by providing superior sampling through the dense seismic station arrangement, which produces favorable event-to-station ray path coverage. Following careful manual phase picking on 104 events chosen to provide adequate ray coverage, we re-locate the events to obtain improved source coordinates. The re-located events are used with Thurber's Simul2000 pseudo-bending local tomography code to estimate the crustal structure on the Korean Peninsula, which is an important contribution to ongoing calibration for events of interest in the region.

  14. Transport of perfluoroalkyl substances (PFAS) from an arctic glacier to downstream locations: implications for sources.

    PubMed

    Kwok, Karen Y; Yamazaki, Eriko; Yamashita, Nobuyoshi; Taniyasu, Sachi; Murphy, Margaret B; Horii, Yuichi; Petrick, Gert; Kallerborn, Roland; Kannan, Kurunthachalam; Murano, Kentaro; Lam, Paul K S

    2013-03-01

    Perfluoroalkyl substances (PFAS) have been globally detected in various environmental matrices, yet their fate and transport to the Arctic is still unclear, especially for the European Arctic. In this study, concentrations of 17 PFAS were quantified in two ice cores (n=26), surface snow (n=9) and surface water samples (n=14) collected along a spatial gradient in Svalbard, Norway. Concentrations of selected ions (Na(+), SO4(2-), etc.) were also determined for tracing the origins and sources of PFAS. Perfluorobutanoate (PFBA), perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were the dominant compounds found in ice core samples. Taking PFOA, PFNA and perfluorooctane-sulfonate (PFOS) as examples, higher concentrations were detected in the middle layers of the ice cores representing the period of 1997-2000. Lower concentrations of C8-C12 perfluorocarboxylates (PFCAs) were detected in comparison with concentrations measured previously in an ice core from the Canadian Arctic, indicating that contamination levels in the European Arctic are lower. Average PFAS concentrations were found to be lower in surface snow and melted glacier water samples, while increased concentrations were observed in river water downstream near the coastal area. Perfluorohexanesulfonate (PFHxS) was detected in the downstream locations, but not in the glacier, suggesting existence of local sources of this compound. Long-range atmospheric transport of PFAS was the major deposition pathway for the glaciers, while local sources (e.g., skiing activities) were identified in the downstream locations. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Comparison of imaging modalities and source-localization algorithms in locating the induced activity during deep brain stimulation of the STN.

    PubMed

    Mideksa, K G; Singh, A; Hoogenboom, N; Hellriegel, H; Krause, H; Schnitzler, A; Deuschl, G; Raethjen, J; Schmidt, G; Muthuraman, M

    2016-08-01

    One of the most commonly used therapy to treat patients with Parkinson's disease (PD) is deep brain stimulation (DBS) of the subthalamic nucleus (STN). Identifying the most optimal target area for the placement of the DBS electrodes have become one of the intensive research area. In this study, the first aim is to investigate the capabilities of different source-analysis techniques in detecting deep sources located at the sub-cortical level and validating it using the a-priori information about the location of the source, that is, the STN. Secondly, we aim at an investigation of whether EEG or MEG is best suited in mapping the DBS-induced brain activity. To do this, simultaneous EEG and MEG measurement were used to record the DBS-induced electromagnetic potentials and fields. The boundary-element method (BEM) have been used to solve the forward problem. The position of the DBS electrodes was then estimated using the dipole (moving, rotating, and fixed MUSIC), and current-density-reconstruction (CDR) (minimum-norm and sLORETA) approaches. The source-localization results from the dipole approaches demonstrated that the fixed MUSIC algorithm best localizes deep focal sources, whereas the moving dipole detects not only the region of interest but also neighboring regions that are affected by stimulating the STN. The results from the CDR approaches validated the capability of sLORETA in detecting the STN compared to minimum-norm. Moreover, the source-localization results using the EEG modality outperformed that of the MEG by locating the DBS-induced activity in the STN.

  16. Earthquake location in island arcs

    USGS Publications Warehouse

    Engdahl, E.R.; Dewey, J.W.; Fujita, K.

    1982-01-01

    -velocity lithospheric slab. In application, JHD has the practical advantage that it does not require the specification of a theoretical velocity model for the slab. Considering earthquakes within a 260 km long by 60 km wide section of the Aleutian main thrust zone, our results suggest that the theoretical velocity structure of the slab is presently not sufficiently well known that accurate locations can be obtained independently of locally recorded data. Using a locally recorded earthquake as a calibration event, JHD gave excellent results over the entire section of the main thrust zone here studied, without showing a strong effect that might be attributed to spatially varying source-station anomalies. We also calibrated the ray-tracing method using locally recorded data and obtained results generally similar to those obtained by JHD. ?? 1982.

  17. Real-time identification of indoor pollutant source positions based on neural network locator of contaminant sources and optimized sensor networks.

    PubMed

    Vukovic, Vladimir; Tabares-Velasco, Paulo Cesar; Srebric, Jelena

    2010-09-01

    A growing interest in security and occupant exposure to contaminants revealed a need for fast and reliable identification of contaminant sources during incidental situations. To determine potential contaminant source positions in outdoor environments, current state-of-the-art modeling methods use computational fluid dynamic simulations on parallel processors. In indoor environments, current tools match accidental contaminant distributions with cases from precomputed databases of possible concentration distributions. These methods require intensive computations in pre- and postprocessing. On the other hand, neural networks emerged as a tool for rapid concentration forecasting of outdoor environmental contaminants such as nitrogen oxides or sulfur dioxide. All of these modeling methods depend on the type of sensors used for real-time measurements of contaminant concentrations. A review of the existing sensor technologies revealed that no perfect sensor exists, but intensity of work in this area provides promising results in the near future. The main goal of the presented research study was to extend neural network modeling from the outdoor to the indoor identification of source positions, making this technology applicable to building indoor environments. The developed neural network Locator of Contaminant Sources was also used to optimize number and allocation of contaminant concentration sensors for real-time prediction of indoor contaminant source positions. Such prediction should take place within seconds after receiving real-time contaminant concentration sensor data. For the purpose of neural network training, a multizone program provided distributions of contaminant concentrations for known source positions throughout a test building. Trained networks had an output indicating contaminant source positions based on measured concentrations in different building zones. A validation case based on a real building layout and experimental data demonstrated the ability

  18. Locating S-wave sources for the SPE-5 explosion using time reversal methods and a close-in, 1000 sensor network

    NASA Astrophysics Data System (ADS)

    Myers, S. C.; Pitarka, A.; Mellors, R. J.

    2016-12-01

    The Source Physics Experiment (SPE) is producing new data to study the generation of seismic waves from explosive sources. Preliminary results show that far-field S-waves are generated both within the non-elastic volume surrounding explosive sources and by P- to S-wave scattering. The relative contribution of non-elastic phenomenology and elastic-wave scattering to far-field S-waves has been debated for decades, and numerical simulations based on the SPE experiments are addressing this question. The match between observed and simulated data degrades with event-station distance and with increasing time in each seismogram. This suggests that a more accurate model of subsurface elastic properties could result in better agreement between observed and simulated seismograms. A detailed model of subsurface structure has been developed using geologic maps and the extensive database of borehole logs, but uncertainty in structural details remains high. The large N instrument deployment during the SPE-5 experiment offers an opportunity to use time-reversal techniques to back project the wave field into the subsurface to locate significant sources of scattered energy. The large N deployment was nominally 1000, 5 Hz sensors (500 Z and 500 3C geophones) deployed in a roughly rectangular array to the south and east of the SPE-5 shot. Sensor spacing was nominally 50 meters in the interior portion of the array and 100 meters in the outer region, with two dense lines at 25 m spacing. The array covers the major geologic boundary between the Yucca Flat basin and the granitic Climax Stock in which the SPE experiments have been conducted. Improved mapping of subsurface scatterers is expected to result in better agreement between simulated and observed seismograms and aid in our understanding of S-wave generation from explosions. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

  19. DEEP WIDEBAND SINGLE POINTINGS AND MOSAICS IN RADIO INTERFEROMETRY: HOW ACCURATELY DO WE RECONSTRUCT INTENSITIES AND SPECTRAL INDICES OF FAINT SOURCES?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rau, U.; Bhatnagar, S.; Owen, F. N., E-mail: rurvashi@nrao.edu

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  1. A Bayesian framework for infrasound location

    NASA Astrophysics Data System (ADS)

    Modrak, Ryan T.; Arrowsmith, Stephen J.; Anderson, Dale N.

    2010-04-01

    We develop a framework for location of infrasound events using backazimuth and infrasonic arrival times from multiple arrays. Bayesian infrasonic source location (BISL) developed here estimates event location and associated credibility regions. BISL accounts for unknown source-to-array path or phase by formulating infrasonic group velocity as random. Differences between observed and predicted source-to-array traveltimes are partitioned into two additive Gaussian sources, measurement error and model error, the second of which accounts for the unknown influence of wind and temperature on path. By applying the technique to both synthetic tests and ground-truth events, we highlight the complementary nature of back azimuths and arrival times for estimating well-constrained event locations. BISL is an extension to methods developed earlier by Arrowsmith et al. that provided simple bounds on location using a grid-search technique.

  2. Accurate visible speech synthesis based on concatenating variable length motion capture data.

    PubMed

    Ma, Jiyong; Cole, Ron; Pellom, Bryan; Ward, Wayne; Wise, Barbara

    2006-01-01

    We present a novel approach to synthesizing accurate visible speech based on searching and concatenating optimal variable-length units in a large corpus of motion capture data. Based on a set of visual prototypes selected on a source face and a corresponding set designated for a target face, we propose a machine learning technique to automatically map the facial motions observed on the source face to the target face. In order to model the long distance coarticulation effects in visible speech, a large-scale corpus that covers the most common syllables in English was collected, annotated and analyzed. For any input text, a search algorithm to locate the optimal sequences of concatenated units for synthesis is desrcribed. A new algorithm to adapt lip motions from a generic 3D face model to a specific 3D face model is also proposed. A complete, end-to-end visible speech animation system is implemented based on the approach. This system is currently used in more than 60 kindergarten through third grade classrooms to teach students to read using a lifelike conversational animated agent. To evaluate the quality of the visible speech produced by the animation system, both subjective evaluation and objective evaluation are conducted. The evaluation results show that the proposed approach is accurate and powerful for visible speech synthesis.

  3. Using geomagnetic birefringence to locate sources of impulsive, terrestrial VHF signals detected by satellites on orbit

    NASA Astrophysics Data System (ADS)

    Jacobson, Abram R.; Shao, Xuan-Min

    2001-07-01

    The Earth's ionosphere is magnetized by the geomagnetic field and imposes birefringent modulation on VHF radio signals propagating through the ionosphere. Satellites viewing VHF emissions from terrestrial sources receive ordinary and extraordinary modes successively from each broadband pulse emitted by the source. The birefringent intermode frequency separation can be used to determine the value of ƒce cos β, where ƒce is the electron gyrofrequency and β is the angle between the wave vector k and the geomagnetic field B at the point where the VHF ray path intersects the ionosphere. Successive receptions of multiple signals (from the same source) cause variation in ƒce cos β, and from the resulting variation in the signal intermode frequency separation the source location on Earth can be inferred. We test the method with signals emitted by the Los Alamos Portable Pulser and received by the FORTE satellite.

  4. A double-correlation tremor-location method

    NASA Astrophysics Data System (ADS)

    Li, Ka Lok; Sgattoni, Giulia; Sadeghisorkhani, Hamzeh; Roberts, Roland; Gudmundsson, Olafur

    2017-02-01

    A double-correlation method is introduced to locate tremor sources based on stacks of complex, doubly-correlated tremor records of multiple triplets of seismographs back projected to hypothetical source locations in a geographic grid. Peaks in the resulting stack of moduli are inferred source locations. The stack of the moduli is a robust measure of energy radiated from a point source or point sources even when the velocity information is imprecise. Application to real data shows how double correlation focuses the source mapping compared to the common single correlation approach. Synthetic tests demonstrate the robustness of the method and its resolution limitations which are controlled by the station geometry, the finite frequency of the signal, the quality of the used velocity information and noise level. Both random noise and signal or noise correlated at time shifts that are inconsistent with the assumed velocity structure can be effectively suppressed. Assuming a surface wave velocity, we can constrain the source location even if the surface wave component does not dominate. The method can also in principle be used with body waves in 3-D, although this requires more data and seismographs placed near the source for depth resolution.

  5. Cable-fault locator

    NASA Technical Reports Server (NTRS)

    Cason, R. L.; Mcstay, J. J.; Heymann, A. P., Sr.

    1979-01-01

    Inexpensive system automatically indicates location of short-circuited section of power cable. Monitor does not require that cable be disconnected from its power source or that test signals be applied. Instead, ground-current sensors are installed in manholes or at other selected locations along cable run. When fault occurs, sensors transmit information about fault location to control center. Repair crew can be sent to location and cable can be returned to service with minimum of downtime.

  6. Improved centroid moment tensor analyses in the NIED AQUA (Accurate and QUick Analysis system for source parameters)

    NASA Astrophysics Data System (ADS)

    Kimura, H.; Asano, Y.; Matsumoto, T.

    2012-12-01

    The rapid determination of hypocentral parameters and their transmission to the public are valuable components of disaster mitigation. We have operated an automatic system for this purpose—termed the Accurate and QUick Analysis system for source parameters (AQUA)—since 2005 (Matsumura et al., 2006). In this system, the initial hypocenter, the moment tensor (MT), and the centroid moment tensor (CMT) solutions are automatically determined and posted on the NIED Hi-net Web site (www.hinet.bosai.go.jp). This paper describes improvements made to the AQUA to overcome limitations that became apparent after the 2011 Tohoku Earthquake (05:46:17, March 11, 2011 in UTC). The improvements included the processing of NIED F-net velocity-type strong motion records, because NIED F-net broadband seismographs are saturated for great earthquakes such as the 2011 Tohoku Earthquake. These velocity-type strong motion seismographs provide unsaturated records not only for the 2011 Tohoku Earthquake, but also for recording stations located close to the epicenters of M>7 earthquakes. We used 0.005-0.020 Hz records for M>7.5 earthquakes, in contrast to the 0.01-0.05 Hz records employed in the original system. The initial hypocenters determined based on arrival times picked by using seismograms recorded by NIED Hi-net stations can have large errors in terms of magnitude and hypocenter location, especially for great earthquakes or earthquakes located far from the onland Hi-net network. The size of the 2011 Tohoku Earthquake was initially underestimated in the AQUA to be around M5 at the initial stage of rupture. Numerous aftershocks occurred at the outer rise east of the Japan trench, where a great earthquake is anticipated to occur. Hence, we modified the system to repeat the MT analyses assuming a larger size, for all earthquakes for which the magnitude was initially underestimated. We also broadened the search range of centroid depth for earthquakes located far from the onland Hi

  7. Site Characterization of the Source Physics Experiment Phase II Location Using Seismic Reflection Data

    NASA Astrophysics Data System (ADS)

    Sexton, E. A.; Snelson, C. M.; Chipman, V.; Emer, D. F.; White, R. L.; Emmitt, R.; Wright, A. A.; Drellack, S.; Huckins-Gang, H.; Mercadante, J.; Floyd, M.; McGowin, C.; Cothrun, C.; Bonal, N.

    2013-12-01

    An objective of the Source Physics Experiment (SPE) is to identify low-yield nuclear explosions from a regional distance. Low-yield nuclear explosions can often be difficult to discriminate among the clutter of natural and man-made explosive events (e.g., earthquakes and mine blasts). The SPE is broken into three phases. Phase I has provided the first of the physics-based data to test the empirical models that have been used to discriminate nuclear events. The Phase I series of tests were placed within a highly fractured granite body. The evolution of the project has led to development of Phase II, to be placed within the opposite end member of geology, an alluvium environment, thereby increasing the database of waveforms to build upon in the discrimination models. Both the granite and alluvium sites have hosted nearby nuclear tests, which provide comparisons for the chemical test data. Phase III of the SPE is yet to be determined. For Phase II of the experiment, characterization of the location is required to develop the geologic/geophysical models for the execution of the experiment. Criteria for the location are alluvium thickness of approximately 170 m and a water table below 170 m; minimal fracturing would be ideal. A P-wave mini-vibroseis survey was conducted at a potential site in alluvium to map out the subsurface geology. The seismic reflection profile consisted of 168 geophone stations, spaced 5 m apart. The mini-vibe was a 7,000-lb peak-force source, starting 57.5 m off the north end of the profile and ending 57.5 m past the southern-most geophone. The length of the profile was 835 m. The source points were placed every 5 m, equally spaced between geophones to reduce clipping. The vibroseis sweep was from 20 Hz down to 180 Hz over 8 seconds, and four sweeps were stacked at each shot location. The shot gathers show high signal-to-noise ratios with clear first arrivals across the entire spread and the suggestion of some shallow reflectors. The data were

  8. SoundCompass: A Distributed MEMS Microphone Array-Based Sensor for Sound Source Localization

    PubMed Central

    Tiete, Jelmer; Domínguez, Federico; da Silva, Bruno; Segers, Laurent; Steenhaut, Kris; Touhafi, Abdellah

    2014-01-01

    Sound source localization is a well-researched subject with applications ranging from localizing sniper fire in urban battlefields to cataloging wildlife in rural areas. One critical application is the localization of noise pollution sources in urban environments, due to an increasing body of evidence linking noise pollution to adverse effects on human health. Current noise mapping techniques often fail to accurately identify noise pollution sources, because they rely on the interpolation of a limited number of scattered sound sensors. Aiming to produce accurate noise pollution maps, we developed the SoundCompass, a low-cost sound sensor capable of measuring local noise levels and sound field directionality. Our first prototype is composed of a sensor array of 52 Microelectromechanical systems (MEMS) microphones, an inertial measuring unit and a low-power field-programmable gate array (FPGA). This article presents the SoundCompass’s hardware and firmware design together with a data fusion technique that exploits the sensing capabilities of the SoundCompass in a wireless sensor network to localize noise pollution sources. Live tests produced a sound source localization accuracy of a few centimeters in a 25-m2 anechoic chamber, while simulation results accurately located up to five broadband sound sources in a 10,000-m2 open field. PMID:24463431

  9. Development of a Persistent Reactive Treatment Zone for Containment of Sources Located in Lower-Permeability Strata

    NASA Astrophysics Data System (ADS)

    Marble, J.; Carroll, K. C.; Brusseau, M. L.; Plaschke, M.; Brinker, F.

    2013-12-01

    Source zones located in relatively deep, low-permeability formations provide special challenges for remediation. Application of permeable reactive barriers, in-situ thermal, or electrokinetic methods would be expensive and generally impractical. In addition, the use of enhanced mass-removal approaches based on reagent injection (e.g., ISCO, enhanced-solubility reagents) is likely to be ineffective. One possible approach for such conditions is to create a persistent treatment zone for purposes of containment. This study examines the efficacy of this approach for containment and treatment of contaminants in a lower permeability zone using potassium permanganate (KMnO4) as the reactant. A localized 1,1-dichloroethene (DCE) source zone is present in a section of the Tucson International Airport Area (TIAA) Superfund Site. Characterization studies identified the source of DCE to be located in lower-permeability strata adjacent to the water table. Bench-scale studies were conducted using core material collected from boreholes drilled at the site to measure DCE concentrations and determine natural oxidant demand. The reactive zone was created by injecting ~1.7% KMnO4 solution into multiple wells screened within the lower-permeability unit. The site has been monitored for ~8 years to characterize the spatial distribution of DCE and permanganate. KMnO4 continues to persist at the site, demonstrating successful creation of a long-term reactive zone. Additionally, the footprint of the DCE contaminant plume in groundwater has decreased continuously with time. This project illustrates the application of ISCO as a reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass flux into groundwater.

  10. Consumption of added sugars among US children and adults by food purchase location and food source123

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D

    2014-01-01

    Background: The proposed changes to the Nutrition Facts Label by the US Food and Drug Administration will include information on added sugars for the first time. Objective: The objective was to evaluate the sources of added sugars in the diets of a representative sample of US children and adults by food purchase location and food source (eg, food group). Design: This cross-sectional study among 31,035 children, adolescents, and adults aged ≥6 y from the 2003–2004, 2005–2006, 2007–2008, and 2009–2010 NHANES used data from a 24-h dietary recall to evaluate consumption of added sugars. Food locations of origin were identified as stores (supermarket or grocery store), quick-service restaurants/pizza (QSRs), full-service restaurants (FSRs), schools, and others (eg, vending machines or gifts). Added sugars consumption by food purchase location was evaluated by age, family income-to-poverty ratio, and race-ethnicity. Food group sources of added sugars were identified by using the National Cancer Institute food categories. Results: Added sugars accounted for ∼14.1% of total dietary energy. Between 65% and 76% of added sugars came from stores, 6% and 12% from QSRs, and 4% and 6% from FSRs, depending on age. Older adults (aged ≥51 y) obtained a significantly greater proportion of added sugars from stores than did younger adults. Lower-income adults obtained a significantly greater proportion of added sugars from stores than did higher-income adults. Intake of added sugars did not vary by family income among children/adolescents. Soda and energy and sports drinks were the largest food group sources of added sugars (34.4%), followed by grain desserts (12.7%), fruit drinks (8.0%), candy (6.7%), and dairy desserts (5.6%). Conclusions: Most added sugars came from foods obtained from stores. The proposed changes to the Nutrition Facts Label should capture the bulk of added sugars in the US food supply, which suggests that the recommended changes have the potential to

  11. Airborne system for detection and location of radio interference sources

    NASA Astrophysics Data System (ADS)

    Audone, Bruno; Pastore, Alberto

    1992-11-01

    The rapid expansion of telecommunication has practically saturated every band of Radio Frequency Spectrum; a similar expansion of electrical and electronic devices has affected all radio communications which are, in some way, influenced by a large amount of interferences, either intentionally or unintentionally produced. Operational consequences of these interferences, particularly in the frequency channels used for aeronautical services, can be extremely dangerous, making mandatory a tight control of Electromagnetic Spectrum. The present paper analyzes the requirements and the problems related to the surveillance, for civil application, of the Electromagnetic Spectrum between 20 and 1000 MHz, with particular attention to the detection and location of radio interference sources; after a brief introduction and the indication of the advantages of an airborne versus ground installation, the airborne system designed by Alenia in cooperation with Italian Ministry of Post and Telecommunication, its practical implementation and the prototype installation on board of a small twin turboprop aircraft for experimentation purposes is presented. The results of the flight tests are also analyzed and discussed.

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

    NASA Technical Reports Server (NTRS)

    Fischer, E.

    1979-01-01

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

  13. Limitations of Phased Array Beamforming in Open Rotor Noise Source Imaging

    NASA Technical Reports Server (NTRS)

    Horvath, Csaba; Envia, Edmane; Podboy, Gary G.

    2013-01-01

    Phased array beamforming results of the F31/A31 historical baseline counter-rotating open rotor blade set were investigated for measurement data taken on the NASA Counter-Rotating Open Rotor Propulsion Rig in the 9- by 15-Foot Low-Speed Wind Tunnel of NASA Glenn Research Center as well as data produced using the LINPROP open rotor tone noise code. The planar microphone array was positioned broadside and parallel to the axis of the open rotor, roughly 2.3 rotor diameters away. The results provide insight as to why the apparent noise sources of the blade passing frequency tones and interaction tones appear at their nominal Mach radii instead of at the actual noise sources, even if those locations are not on the blades. Contour maps corresponding to the sound fields produced by the radiating sound waves, taken from the simulations, are used to illustrate how the interaction patterns of circumferential spinning modes of rotating coherent noise sources interact with the phased array, often giving misleading results, as the apparent sources do not always show where the actual noise sources are located. This suggests that a more sophisticated source model would be required to accurately locate the sources of each tone. The results of this study also have implications with regard to the shielding of open rotor sources by airframe empennages.

  14. Reverse radiance: a fast accurate method for determining luminance

    NASA Astrophysics Data System (ADS)

    Moore, Kenneth E.; Rykowski, Ronald F.; Gangadhara, Sanjay

    2012-10-01

    Reverse ray tracing from a region of interest backward to the source has long been proposed as an efficient method of determining luminous flux. The idea is to trace rays only from where the final flux needs to be known back to the source, rather than tracing in the forward direction from the source outward to see where the light goes. Once the reverse ray reaches the source, the radiance the equivalent forward ray would have represented is determined and the resulting flux computed. Although reverse ray tracing is conceptually simple, the method critically depends upon an accurate source model in both the near and far field. An overly simplified source model, such as an ideal Lambertian surface substantially detracts from the accuracy and thus benefit of the method. This paper will introduce an improved method of reverse ray tracing that we call Reverse Radiance that avoids assumptions about the source properties. The new method uses measured data from a Source Imaging Goniometer (SIG) that simultaneously measures near and far field luminous data. Incorporating this data into a fast reverse ray tracing integration method yields fast, accurate data for a wide variety of illumination problems.

  15. Explosion Source Location Study Using Collocated Acoustic and Seismic Networks in Israel

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Gitterman, Y.; Arrowsmith, S.; Ben-Horin, Y.

    2013-12-01

    infrasonic phases of the two distant arrays; 2) a standard robust grid-search location procedure based on phase picks and a constant celerity for a phase (tropospheric or stratospheric) was applied; 3) a joint coordinate grid-search procedure using array waveforms and phase picks was tested, 4) the Bayesian Infrasonic Source Localization (BISL) method, incorporating semi-empirical model-based prior information, was modified for array+network configuration and applied to the ground-truth events. For this purpose we accumulated data of the former observations of the air-to-ground infrasonic phases to compute station specific ground-truth Celerity-Range Histograms (ssgtCRH) and/or model-based CRH (mbCRH), which allow to essentially improve the location results. For building the mbCRH the local meteo-data and the ray-tracing modeling in 3 available azimuth ranges, accounting seasonal variations of winds directivity (quadrants North:315-45, South: 135-225, East 45-135) have been used.

  16. Fuel from Wastewater - Harnessing a Potential Energy Source in Canada through the Co-location of Algae Biofuel Production to Sources of Effluent, Heat and CO2

    NASA Astrophysics Data System (ADS)

    Klise, G. T.; Roach, J. D.; Passell, H. D.; Moreland, B. D.; O'Leary, S. J.; Pienkos, P. T.; Whalen, J.

    2010-12-01

    Sandia National Laboratories is collaborating with the National Research Council (NRC) Canada and the National Renewable Energy Laboratory (NREL) to develop a decision-support model that will evaluate the tradeoffs associated with high-latitude algae biofuel production co-located with wastewater, CO2, and waste heat. This project helps Canada meet its goal of diversifying fuel sources with algae-based biofuels. The biofuel production will provide a wide range of benefits including wastewater treatment, CO2 reuse and reduction of demand for fossil-based fuels. The higher energy density in algae-based fuels gives them an advantage over crop-based biofuels as the “production” footprint required is much less, resulting in less water consumed and little, if any conversion of agricultural land from food to fuel production. Besides being a potential source for liquid fuel, algae have the potential to be used to generate electricity through the burning of dried biomass, or anaerobically digested to generate methane for electricity production. Co-locating algae production with waste streams may be crucial for making algae an economically valuable fuel source, and will certainly improve its overall ecological sustainability. The modeling process will address these questions, and others that are important to the use of water for energy production: What are the locations where all resources are co-located, and what volumes of algal biomass and oil can be produced there? In locations where co-location does not occur, what resources should be transported, and how far, while maintaining economic viability? This work is being funded through the U.S. Department of Energy (DOE) Biomass Program Office of Energy Efficiency and Renewable Energy, and is part of a larger collaborative effort that includes sampling, strain isolation, strain characterization and cultivation being performed by the NREL and Canada’s NRC. Results from the NREL / NRC collaboration including specific

  17. New approaches for automatic threedimensional source localization of acoustic emissions--Applications to concrete specimens.

    PubMed

    Kurz, Jochen H

    2015-12-01

    The task of locating a source in space by measuring travel time differences of elastic or electromagnetic waves from the source to several sensors is evident in varying fields. The new concepts of automatic acoustic emission localization presented in this article are based on developments from geodesy and seismology. A detailed description of source location determination in space is given with the focus on acoustic emission data from concrete specimens. Direct and iterative solvers are compared. A concept based on direct solvers from geodesy extended by a statistical approach is described which allows a stable source location determination even for partly erroneous onset times. The developed approach is validated with acoustic emission data from a large specimen leading to travel paths up to 1m and therefore to noisy data with errors in the determined onsets. The adaption of the algorithms from geodesy to the localization procedure of sources of elastic waves offers new possibilities concerning stability, automation and performance of localization results. Fracture processes can be assessed more accurately. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Acoustic sources of opportunity in the marine environment - Applied to source localization and ocean sensing

    NASA Astrophysics Data System (ADS)

    Verlinden, Christopher M.

    Controlled acoustic sources have typically been used for imaging the ocean. These sources can either be used to locate objects or characterize the ocean environment. The processing involves signal extraction in the presence of ambient noise, with shipping being a major component of the latter. With the advent of the Automatic Identification System (AIS) which provides accurate locations of all large commercial vessels, these major noise sources can be converted from nuisance to beacons or sources of opportunity for the purpose of studying the ocean. The source localization method presented here is similar to traditional matched field processing, but differs in that libraries of data-derived measured replicas are used in place of modeled replicas. In order to account for differing source spectra between library and target vessels, cross-correlation functions are compared instead of comparing acoustic signals directly. The library of measured cross-correlation function replicas is extrapolated using waveguide invariant theory to fill gaps between ship tracks, fully populating the search grid with estimated replicas allowing for continuous tracking. In addition to source localization, two ocean sensing techniques are discussed in this dissertation. The feasibility of estimating ocean sound speed and temperature structure, using ship noise across a drifting volumetric array of hydrophones suspended beneath buoys, in a shallow water marine environment is investigated. Using the attenuation of acoustic energy along eigenray paths to invert for ocean properties such as temperature, salinity, and pH is also explored. In each of these cases, the theory is developed, tested using numerical simulations, and validated with data from acoustic field experiments.

  19. Reconstructing Spatial Distributions from Anonymized Locations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Horey, James L; Forrest, Stephanie; Groat, Michael

    2012-01-01

    Devices such as mobile phones, tablets, and sensors are often equipped with GPS that accurately report a person's location. Combined with wireless communication, these devices enable a wide range of new social tools and applications. These same qualities, however, leave location-aware applications vulnerable to privacy violations. This paper introduces the Negative Quad Tree, a privacy protection method for location aware applications. The method is broadly applicable to applications that use spatial density information, such as social applications that measure the popularity of social venues. The method employs a simple anonymization algorithm running on mobile devices, and a more complex reconstructionmore » algorithm on a central server. This strategy is well suited to low-powered mobile devices. The paper analyzes the accuracy of the reconstruction method in a variety of simulated and real-world settings and demonstrates that the method is accurate enough to be used in many real-world scenarios.« less

  20. Lightning Location Using Acoustic Signals

    NASA Astrophysics Data System (ADS)

    Badillo, E.; Arechiga, R. O.; Thomas, R. J.

    2013-05-01

    In the summer of 2011 and 2012 a network of acoustic arrays was deployed in the Magdalena mountains of central New Mexico to locate lightning flashes. A Times-Correlation (TC) ray-tracing-based-technique was developed in order to obtain the location of lightning flashes near the network. The TC technique, locates acoustic sources from lightning. It was developed to complement the lightning location of RF sources detected by the Lightning Mapping Array (LMA) developed at Langmuir Laboratory, in New Mexico Tech. The network consisted of four arrays with four microphones each. The microphones on each array were placed in a triangular configuration with one of the microphones in the center of the array. The distance between the central microphone and the rest of them was about 30 m. The distance between centers of the arrays ranged from 500 m to 1500 m. The TC technique uses times of arrival (TOA) of acoustic waves to trace back the location of thunder sources. In order to obtain the times of arrival, the signals were filtered in a frequency band of 2 to 20 hertz and cross-correlated. Once the times of arrival were obtained, the Levenberg-Marquardt algorithm was applied to locate the spatial coordinates (x,y, and z) of thunder sources. Two techniques were used and contrasted to compute the accuracy of the TC method: Nearest-Neighbors (NN), between acoustic and LMA located sources, and standard deviation from the curvature matrix of the system as a measure of dispersion of the results. For the best case scenario, a triggered lightning event, the TC method applied with four microphones, located sources with a median error of 152 m and 142.9 m using nearest-neighbors and standard deviation respectively.; Results of the TC method in the lightning event recorded at 18:47:35 UTC, August 6, 2012. Black dots represent the results computed. Light color dots represent the LMA data for the same event. The results were obtained with the MGTM station (four channels). This figure

  1. Full moment tensor and source location inversion based on full waveform adjoint method

    NASA Astrophysics Data System (ADS)

    Morency, C.

    2012-12-01

    The development of high-performance computing and numerical techniques enabled global and regional tomography to reach high levels of precision, and seismic adjoint tomography has become a state-of-the-art tomographic technique. The method was successfully used for crustal tomography of Southern California (Tape et al., 2009) and Europe (Zhu et al., 2012). Here, I will focus on the determination of source parameters (full moment tensor and location) based on the same approach (Kim et al, 2011). The method relies on full wave simulations and takes advantage of the misfit between observed and synthetic seismograms. An adjoint wavefield is calculated by back-propagating the difference between observed and synthetics from the receivers to the source. The interaction between this adjoint wavefield and the regular forward wavefield helps define Frechet derivatives of the source parameters, that is, the sensitivity of the misfit with respect to the source parameters. Source parameters are then recovered by minimizing the misfit based on a conjugate gradient algorithm using the Frechet derivatives. First, I will demonstrate the method on synthetic cases before tackling events recorded at the Geysers. The velocity model used at the Geysers is based on the USGS 3D velocity model. Waveform datasets come from the Northern California Earthquake Data Center. Finally, I will discuss strategies to ultimately use this method to characterize smaller events for microseismic and induced seismicity monitoring. References: - Tape, C., Q. Liu, A. Maggi, and J. Tromp, 2009, Adjoint tomography of the Southern California crust: Science, 325, 988992. - Zhu, H., Bozdag, E., Peter, D., and Tromp, J., 2012, Structure of the European upper mantle revealed by adjoint method: Nature Geoscience, 5, 493-498. - Kim, Y., Q. Liu, and J. Tromp, 2011, Adjoint centroid-moment tensor inversions: Geophys. J. Int., 186, 264278. Prepared by LLNL under Contract DE-AC52-07NA27344.

  2. Characterizing and locating air pollution sources in a complex industrial district using optical remote sensing technology and multivariate statistical modeling.

    PubMed

    Chang, Pao-Erh Paul; Yang, Jen-Chih Rena; Den, Walter; Wu, Chang-Fu

    2014-09-01

    Emissions of volatile organic compounds (VOCs) are most frequent environmental nuisance complaints in urban areas, especially where industrial districts are nearby. Unfortunately, identifying the responsible emission sources of VOCs is essentially a difficult task. In this study, we proposed a dynamic approach to gradually confine the location of potential VOC emission sources in an industrial complex, by combining multi-path open-path Fourier transform infrared spectrometry (OP-FTIR) measurement and the statistical method of principal component analysis (PCA). Close-cell FTIR was further used to verify the VOC emission source by measuring emitted VOCs from selected exhaust stacks at factories in the confined areas. Multiple open-path monitoring lines were deployed during a 3-month monitoring campaign in a complex industrial district. The emission patterns were identified and locations of emissions were confined by the wind data collected simultaneously. N,N-Dimethyl formamide (DMF), 2-butanone, toluene, and ethyl acetate with mean concentrations of 80.0 ± 1.8, 34.5 ± 0.8, 103.7 ± 2.8, and 26.6 ± 0.7 ppbv, respectively, were identified as the major VOC mixture at all times of the day around the receptor site. As the toxic air pollutant, the concentrations of DMF in air samples were found exceeding the ambient standard despite the path-average effect of OP-FTIR upon concentration levels. The PCA data identified three major emission sources, including PU coating, chemical packaging, and lithographic printing industries. Applying instrumental measurement and statistical modeling, this study has established a systematic approach for locating emission sources. Statistical modeling (PCA) plays an important role in reducing dimensionality of a large measured dataset and identifying underlying emission sources. Instrumental measurement, however, helps verify the outcomes of the statistical modeling. The field study has demonstrated the feasibility of

  3. An interpretation of induced electric currents in long pipelines caused by natural geomagnetic sources of the upper atmosphere

    USGS Publications Warehouse

    Campbell, W.H.

    1986-01-01

    Electric currents in long pipelines can contribute to corrosion effects that limit the pipe's lifetime. One cause of such electric currents is the geomagnetic field variations that have sources in the Earth's upper atmosphere. Knowledge of the general behavior of the sources allows a prediction of the occurrence times, favorable locations for the pipeline effects, and long-term projections of corrosion contributions. The source spectral characteristics, the Earth's conductivity profile, and a corrosion-frequency dependence limit the period range of the natural field changes that affect the pipe. The corrosion contribution by induced currents from geomagnetic sources should be evaluated for pipelines that are located at high and at equatorial latitudes. At midlatitude locations, the times of these natural current maxima should be avoided for the necessary accurate monitoring of the pipe-to-soil potential. ?? 1986 D. Reidel Publishing Company.

  4. Integration of video and infrasound to understand source locations and vent geometry at Erebus Volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Jones, K. R.; Aster, R. C.; Johnson, J. B.; Kyle, P. R.; McIntosh, W. C.

    2007-05-01

    Infrasound monitoring at Erebus volcano has enabled us to quantify eruption energetics and precisely determine the source location of Strombolian eruptions. Since January 2006 we have operated a three-element network of identical infrasound pressure transducers, to track explosive eruptions, triangulate source locations of the eruptions, and distinguish activity from several vents with diverse activities. In December 2006 the network was expanded to six identical pressure transducers with improved azimuthal distribution sited ~300 m to 700 m from the erupting vents. These sensors have a dynamic range of +/-125 Pa and are able to record non-distorted waveforms for almost all eruptive events. Since January 2006, eruptions have been identified from locations within the ~40 m diameter phonolitic lava lake, an adjacent smaller "active vent", and a vent ~80 m distant from the lava lake known as "Werner's". Since late 2005 until the end of 2006, activity was considerably elevated at the "lava lake", from which frequent (up to six per day) explosions were noted. These events entailed gas bubble bursts, some of which were capable of ejecting bombs more than 1 km distant and producing infrasonic transients in excess of 100 Pa at a distance of 700 m. Activity from "Werner's" vent was much more subdued in terms of eruptive frequency and the radiated acoustic energy, with all signals less than about 5 Pa at 700 m. Activity from the "active vent" was also observed, though notably, these acoustic transients were extended in duration in terms of time (> 5 s to more than 30 s), which reflects extended duration ash-venting source mechanisms, corroborated by video records. The updated infrasound network has operated through a relative lull in eruptive intensity (November - December 2006 - January 2007). Since January 2007 more frequent and larger explosions from the lava lake have been observed and recorded with infrasound and video. We quantify this recent upsurge in lava lake

  5. Preliminary Design of a Lightning Optical Camera and ThundEr (LOCATE) Sensor

    NASA Technical Reports Server (NTRS)

    Phanord, Dieudonne D.; Koshak, William J.; Rybski, Paul M.; Arnold, James E. (Technical Monitor)

    2001-01-01

    The preliminary design of an optical/acoustical instrument is described for making highly accurate real-time determinations of the location of cloud-to-ground (CG) lightning. The instrument, named the Lightning Optical Camera And ThundEr (LOCATE) sensor, will also image the clear and cloud-obscured lightning channel produced from CGs and cloud flashes, and will record the transient optical waveforms produced from these discharges. The LOCATE sensor will consist of a full (360 degrees) field-of-view optical camera for obtaining CG channel image and azimuth, a sensitive thunder microphone for obtaining CG range, and a fast photodiode system for time-resolving the lightning optical waveform. The optical waveform data will be used to discriminate CGs from cloud flashes. Together, the optical azimuth and thunder range is used to locate CGs and it is anticipated that a network of LOCATE sensors would determine CG source location to well within 100 meters. All of this would be accomplished for a relatively inexpensive cost compared to present RF lightning location technologies, but of course the range detection is limited and will be quantified in the future. The LOCATE sensor technology would have practical applications for electric power utility companies, government (e.g. NASA Kennedy Space Center lightning safety and warning), golf resort lightning safety, telecommunications, and other industries.

  6. Determining the seismic source mechanism and location for an explosive eruption with limited observational data: Augustine Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Dawson, Phillip B.; Chouet, Bernard A.; Power, John

    2011-02-01

    Waveform inversions of the very-long-period components of the seismic wavefield produced by an explosive eruption that occurred on 11 January, 2006 at Augustine Volcano, Alaska constrain the seismic source location to near sea level beneath the summit of the volcano. The calculated moment tensors indicate the presence of a volumetric source mechanism. Systematic reconstruction of the source mechanism shows the source consists of a sill intersected by either a sub-vertical east-west trending dike or a sub-vertical pipe and a weak single force. The trend of the dike may be controlled by the east-west trending Augustine-Seldovia arch. The data from the network of broadband sensors is limited to fourteen seismic traces, and synthetic modeling confirms the ability of the network to recover the source mechanism. The synthetic modeling also provides a guide to the expected capability of a broadband network to resolve very-long-period source mechanisms, particularly when confronted with limited observational data.

  7. BlueDetect: An iBeacon-Enabled Scheme for Accurate and Energy-Efficient Indoor-Outdoor Detection and Seamless Location-Based Service

    PubMed Central

    Zou, Han; Jiang, Hao; Luo, Yiwen; Zhu, Jianjie; Lu, Xiaoxuan; Xie, Lihua

    2016-01-01

    The location and contextual status (indoor or outdoor) is fundamental and critical information for upper-layer applications, such as activity recognition and location-based services (LBS) for individuals. In addition, optimizations of building management systems (BMS), such as the pre-cooling or heating process of the air-conditioning system according to the human traffic entering or exiting a building, can utilize the information, as well. The emerging mobile devices, which are equipped with various sensors, become a feasible and flexible platform to perform indoor-outdoor (IO) detection. However, power-hungry sensors, such as GPS and WiFi, should be used with caution due to the constrained battery storage on mobile device. We propose BlueDetect: an accurate, fast response and energy-efficient scheme for IO detection and seamless LBS running on the mobile device based on the emerging low-power iBeacon technology. By leveraging the on-broad Bluetooth module and our proposed algorithms, BlueDetect provides a precise IO detection service that can turn on/off on-board power-hungry sensors smartly and automatically, optimize their performances and reduce the power consumption of mobile devices simultaneously. Moreover, seamless positioning and navigation services can be realized by it, especially in a semi-outdoor environment, which cannot be achieved by GPS or an indoor positioning system (IPS) easily. We prototype BlueDetect on Android mobile devices and evaluate its performance comprehensively. The experimental results have validated the superiority of BlueDetect in terms of IO detection accuracy, localization accuracy and energy consumption. PMID:26907295

  8. IMPRESS: medical location-aware decision making during emergencies

    NASA Astrophysics Data System (ADS)

    Gkotsis, I.; Eftychidis, G.; Leventakis, G.; Mountzouris, M.; Diagourtas, D.; Kostaridis, A.; Hedel, R.; Olunczek, A.; Hahmann, S.

    2017-09-01

    Emergency situations and mass casualties involve several agencies and public authorities, which need to gather data from the incident scene and exchange geo-referenced information to provide fast and accurate first aid to the people in need. Tracking patients on their way to the hospitals can prove critical in taking lifesaving decisions. Increased and continuous flow of information combined by vital signs and geographic location of emergency victims can greatly reduce the response time of the medical emergency chain and improve the efficiency of disaster medicine activity. Recent advances in mobile positioning systems and telecommunications are providing the technology needed for the development of location-aware medical applications. IMPRESS is an advanced ICT platform based on adequate technologies for developing location-aware medical response during emergencies. The system incorporates mobile and fixed components that collect field data from diverse sources, support medical location and situation-based services and share information on the patient's transport from the field to the hospitals. In IMPRESS platform tracking of victims, ambulances and emergency services vehicles is integrated with medical, traffic and crisis management information into a common operational picture. The Incident Management component of the system manages operational resources together with patient tracking data that contain vital sign values and patient's status evolution. Thus, it can prioritize emergency transport decisions, based on medical and location-aware information. The solution combines positioning and information gathered and owned by various public services involved in MCIs or large-scale disasters. IMPRESS solution, were validated in field and table top exercises in cooperation with emergency services and hospitals.

  9. The January 2014 Northern Cuba Earthquake Sequence - Unusual Location and Unexpected Source Mechanism Variability

    NASA Astrophysics Data System (ADS)

    Braunmiller, J.; Thompson, G.; McNutt, S. R.

    2017-12-01

    On 9 January 2014, a magnitude Mw=5.1 earthquake occurred along the Bahamas-Cuba suture at the northern coast of Cuba revealing a surprising seismic hazard source for both Cuba and southern Florida where it was widely felt. Due to its location, the event and its aftershocks (M>3.5) were recorded only at far distances (300+ km) resulting in high-detection thresholds, low location accuracy, and limited source parameter resolution. We use three-component regional seismic data to study the sequence. High-pass filtered seismograms at the closest site in southern Florida are similar in character suggesting a relatively tight event cluster and revealing additional, smaller aftershocks not included in the ANSS or ISC catalogs. Aligning on the P arrival and low-pass filtering (T>10 s) uncovers a surprise polarity flip of the large amplitude surface waves on vertical seismograms for some aftershocks relative to the main shock. We performed regional moment tensor inversions of the main shock and its largest aftershocks using complete three-component seismograms from stations distributed throughout the region to confirm the mechanism changes. Consistent with the GCMT solution, we find an E-W trending normal faulting mechanism for the main event and for one immediate aftershock. Two aftershocks indicate E-W trending reverse faulting with essentially flipped P- and T-axes relative to the normal faulting events (and the same B-axes). Within uncertainties, depths of the two event families are indistinguishable and indicate shallow faulting (<10 km). One intriguing possible interpretation is that both families ruptured the same fault with reverse mechanisms compensating for overshooting. However, activity could also be spatially separated either vertically (with reverse mechanisms possibly below extension) or laterally. The shallow source depth and the 200-km long uplifted chain of islands indicate that larger, shallow and thus potentially tsunamigenic earthquakes could occur just

  10. Accurate estimation of seismic source parameters of induced seismicity by a combined approach of generalized inversion and genetic algorithm: Application to The Geysers geothermal area, California

    NASA Astrophysics Data System (ADS)

    Picozzi, M.; Oth, A.; Parolai, S.; Bindi, D.; De Landro, G.; Amoroso, O.

    2017-05-01

    The accurate determination of stress drop, seismic efficiency, and how source parameters scale with earthquake size is an important issue for seismic hazard assessment of induced seismicity. We propose an improved nonparametric, data-driven strategy suitable for monitoring induced seismicity, which combines the generalized inversion technique together with genetic algorithms. In the first step of the analysis the generalized inversion technique allows for an effective correction of waveforms for attenuation and site contributions. Then, the retrieved source spectra are inverted by a nonlinear sensitivity-driven inversion scheme that allows accurate estimation of source parameters. We therefore investigate the earthquake source characteristics of 633 induced earthquakes (Mw 2-3.8) recorded at The Geysers geothermal field (California) by a dense seismic network (i.e., 32 stations, more than 17.000 velocity records). We find a nonself-similar behavior, empirical source spectra that require an ωγ source model with γ > 2 to be well fit and small radiation efficiency ηSW. All these findings suggest different dynamic rupture processes for smaller and larger earthquakes and that the proportion of high-frequency energy radiation and the amount of energy required to overcome the friction or for the creation of new fractures surface changes with earthquake size. Furthermore, we observe also two distinct families of events with peculiar source parameters that in one case suggests the reactivation of deep structures linked to the regional tectonics, while in the other supports the idea of an important role of steeply dipping faults in the fluid pressure diffusion.

  11. 40 CFR 141.703 - Sampling locations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 23 2011-07-01 2011-07-01 false Sampling locations. 141.703 Section... Monitoring Requirements § 141.703 Sampling locations. (a) Systems required to conduct source water monitoring... a sampling tap is available where the sources are combined prior to treatment, systems must collect...

  12. Accuracy evaluation of distance inverse square law in determining virtual electron source location in Siemens Primus linac.

    PubMed

    Douk, Hamid Shafaei; Aghamiri, Mahmoud Reza; Ghorbani, Mahdi; Farhood, Bagher; Bakhshandeh, Mohsen; Hemmati, Hamid Reza

    2018-01-01

    The aim of this study is to evaluate the accuracy of the inverse square law (ISL) method for determining location of virtual electron source ( S Vir ) in Siemens Primus linac. So far, different experimental methods have presented for determining virtual and effective electron source location such as Full Width at Half Maximum (FWHM), Multiple Coulomb Scattering (MCS), and Multi Pinhole Camera (MPC) and Inverse Square Law (ISL) methods. Among these methods, Inverse Square Law is the most common used method. Firstly, Siemens Primus linac was simulated using MCNPX Monte Carlo code. Then, by using dose profiles obtained from the Monte Carlo simulations, the location of S Vir was calculated for 5, 7, 8, 10, 12 and 14 MeV electron energies and 10 cm × 10 cm, 15 cm × 15 cm, 20 cm × 20 cm and 25 cm × 25 cm field sizes. Additionally, the location of S Vir was obtained by the ISL method for the mentioned electron energies and field sizes. Finally, the values obtained by the ISL method were compared to the values resulted from Monte Carlo simulation. The findings indicate that the calculated S Vir values depend on beam energy and field size. For a specific energy, with increase of field size, the distance of S Vir increases for most cases. Furthermore, for a special applicator, with increase of electron energy, the distance of S Vir increases for most cases. The variation of S Vir values versus change of field size in a certain energy is more than the variation of S Vir values versus change of electron energy in a certain field size. According to the results, it is concluded that the ISL method can be considered as a good method for calculation of S Vir location in higher electron energies (14 MeV).

  13. Configuration of electro-optic fire source detection system

    NASA Astrophysics Data System (ADS)

    Fabian, Ram Z.; Steiner, Zeev; Hofman, Nir

    2007-04-01

    The recent fighting activities in various parts of the world have highlighted the need for accurate fire source detection on one hand and fast "sensor to shooter cycle" capabilities on the other. Both needs can be met by the SPOTLITE system which dramatically enhances the capability to rapidly engage hostile fire source with a minimum of casualties to friendly force and to innocent bystanders. Modular system design enable to meet each customer specific requirements and enable excellent future growth and upgrade potential. The design and built of a fire source detection system is governed by sets of requirements issued by the operators. This can be translated into the following design criteria: I) Long range, fast and accurate fire source detection capability. II) Different threat detection and classification capability. III) Threat investigation capability. IV) Fire source data distribution capability (Location, direction, video image, voice). V) Men portability. ) In order to meet these design criteria, an optimized concept was presented and exercised for the SPOTLITE system. Three major modular components were defined: I) Electro Optical Unit -Including FLIR camera, CCD camera, Laser Range Finder and Marker II) Electronic Unit -including system computer and electronic. III) Controller Station Unit - Including the HMI of the system. This article discusses the system's components definition and optimization processes, and also show how SPOTLITE designers successfully managed to introduce excellent solutions for other system parameters.

  14. Information spreading by a combination of MEG source estimation and multivariate pattern classification.

    PubMed

    Sato, Masashi; Yamashita, Okito; Sato, Masa-Aki; Miyawaki, Yoichi

    2018-01-01

    To understand information representation in human brain activity, it is important to investigate its fine spatial patterns at high temporal resolution. One possible approach is to use source estimation of magnetoencephalography (MEG) signals. Previous studies have mainly quantified accuracy of this technique according to positional deviations and dispersion of estimated sources, but it remains unclear how accurately MEG source estimation restores information content represented by spatial patterns of brain activity. In this study, using simulated MEG signals representing artificial experimental conditions, we performed MEG source estimation and multivariate pattern analysis to examine whether MEG source estimation can restore information content represented by patterns of cortical current in source brain areas. Classification analysis revealed that the corresponding artificial experimental conditions were predicted accurately from patterns of cortical current estimated in the source brain areas. However, accurate predictions were also possible from brain areas whose original sources were not defined. Searchlight decoding further revealed that this unexpected prediction was possible across wide brain areas beyond the original source locations, indicating that information contained in the original sources can spread through MEG source estimation. This phenomenon of "information spreading" may easily lead to false-positive interpretations when MEG source estimation and classification analysis are combined to identify brain areas that represent target information. Real MEG data analyses also showed that presented stimuli were able to be predicted in the higher visual cortex at the same latency as in the primary visual cortex, also suggesting that information spreading took place. These results indicate that careful inspection is necessary to avoid false-positive interpretations when MEG source estimation and multivariate pattern analysis are combined.

  15. Information spreading by a combination of MEG source estimation and multivariate pattern classification

    PubMed Central

    Sato, Masashi; Yamashita, Okito; Sato, Masa-aki

    2018-01-01

    To understand information representation in human brain activity, it is important to investigate its fine spatial patterns at high temporal resolution. One possible approach is to use source estimation of magnetoencephalography (MEG) signals. Previous studies have mainly quantified accuracy of this technique according to positional deviations and dispersion of estimated sources, but it remains unclear how accurately MEG source estimation restores information content represented by spatial patterns of brain activity. In this study, using simulated MEG signals representing artificial experimental conditions, we performed MEG source estimation and multivariate pattern analysis to examine whether MEG source estimation can restore information content represented by patterns of cortical current in source brain areas. Classification analysis revealed that the corresponding artificial experimental conditions were predicted accurately from patterns of cortical current estimated in the source brain areas. However, accurate predictions were also possible from brain areas whose original sources were not defined. Searchlight decoding further revealed that this unexpected prediction was possible across wide brain areas beyond the original source locations, indicating that information contained in the original sources can spread through MEG source estimation. This phenomenon of “information spreading” may easily lead to false-positive interpretations when MEG source estimation and classification analysis are combined to identify brain areas that represent target information. Real MEG data analyses also showed that presented stimuli were able to be predicted in the higher visual cortex at the same latency as in the primary visual cortex, also suggesting that information spreading took place. These results indicate that careful inspection is necessary to avoid false-positive interpretations when MEG source estimation and multivariate pattern analysis are combined. PMID:29912968

  16. Determining the source locations of martian meteorites: Hapke mixture models applied to CRISM simulated data of igneous mineral mixtures and martian meteorites

    NASA Astrophysics Data System (ADS)

    Harris, Jennifer; Grindrod, Peter

    2017-04-01

    At present, martian meteorites represent the only samples of Mars available for study in terrestrial laboratories. However, these samples have never been definitively tied to source locations on Mars, meaning that the fundamental geological context is missing. The goal of this work is to link the bulk mineralogical analyses of martian meteorites to the surface geology of Mars through spectral mixture analysis of hyperspectral imagery. Hapke radiation transfer modelling has been shown to provide accurate (within 5 - 10% absolute error) mineral abundance values from laboratory derived hyperspectral measurements of binary [1] and ternary [2] mixtures of plagioclase, pyroxene and olivine. These three minerals form the vast bulk of the SNC meteorites [3] and the bedrock of the Amazonian provinces on Mars that are inferred to be the source regions for these meteorites based on isotopic aging. Spectral unmixing through the Hapke model could be used to quantitatively analyse the Martian surface and pinpoint the exact craters from which the SNC meteorites originated. However the Hapke model is complex with numerous variables, many of which are determinable in laboratory conditions but not from remote measurements of a planetary surface. Using binary and tertiary spectral mixtures and martian meteorite spectra from the RELAB spectral library, the accuracy of Hapke abundance estimation is investigated in the face of increasing constraints and simplifications to simulate CRISM data. Constraints and simplifications include reduced spectral resolution, additional noise, unknown endmembers and unknown particle physical characteristics. CRISM operates in two spectral resolutions, the Full Resolution Targeted (FRT) with which it has imaged approximately 2% of the martian surface, and the lower spectral resolution MultiSpectral Survey mode (MSP) with which it has covered the vast majority of the surface. On resampling the RELAB spectral mixtures to these two wavelength ranges it was

  17. Preprocessor with spline interpolation for converting stereolithography into cutter location source data

    NASA Astrophysics Data System (ADS)

    Nagata, Fusaomi; Okada, Yudai; Sakamoto, Tatsuhiko; Kusano, Takamasa; Habib, Maki K.; Watanabe, Keigo

    2017-06-01

    The authors have developed earlier an industrial machining robotic system for foamed polystyrene materials. The developed robotic CAM system provided a simple and effective interface without the need to use any robot language between operators and the machining robot. In this paper, a preprocessor for generating Cutter Location Source data (CLS data) from Stereolithography (STL data) is first proposed for robotic machining. The preprocessor enables to control the machining robot directly using STL data without using any commercially provided CAM system. The STL deals with a triangular representation for a curved surface geometry. The preprocessor allows machining robots to be controlled through a zigzag or spiral path directly calculated from STL data. Then, a smart spline interpolation method is proposed and implemented for smoothing coarse CLS data. The effectiveness and potential of the developed approaches are demonstrated through experiments on actual machining and interpolation.

  18. The impact of runoff generation mechanisms on the location of critical source areas

    USGS Publications Warehouse

    Lyon, S.W.; McHale, M.R.; Walter, M.T.; Steenhuis, T.S.

    2006-01-01

    Identifying phosphorus (P) source areas and transport pathways is a key step in decreasing P loading to natural water systems. This study compared the effects of two modeled runoff generation processes - saturation excess and infiltration excess - on total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations in 10 catchment streams of a Catskill mountain watershed in southeastern New York. The spatial distribution of runoff from forested land and agricultural land was generated for both runoff processes; results of both distributions were consistent with Soil Conservation Service-Curve Number (SCS-CN) theory. These spatial runoff distributions were then used to simulate stream concentrations of TP and SRP through a simple equation derived from an observed relation between P concentration and land use; empirical results indicate that TP and SRP concentrations increased with increasing percentage of agricultural land. Simulated TP and SRP stream concentrations predicted for the 10 catchments were strongly affected by the assumed runoff mechanism. The modeled TP and SRP concentrations produced by saturation excess distribution averaged 31 percent higher and 42 percent higher, respectively, than those produced by the infiltration excess distribution. Misrepresenting the primary runoff mechanism could not only produce erroneous concentrations, it could fail to correctly locate critical source areas for implementation of best management practices. Thus, identification of the primary runoff mechanism is critical in selection of appropriate models in the mitigation of nonpoint source pollution. Correct representation of runoff processes is also critical in the future development of biogeochemical transport models, especially those that address nutrient fluxes.

  19. Three-dimensional orientation and location-dependent varying rules of radiographic angles of the acetabular cup.

    PubMed

    Zhao, Jing-Xin; Su, Xiu-Yun; Zhao, Zhe; Xiao, Ruo-Xiu; Zhang, Li-Cheng; Tang, Pei-Fu

    2018-02-17

    The aim of this study is to demonstrate the varying rules of radiographic angles following varying three-dimensional (3D) orientations and locations of cup using an accurate mathematical model. A cone model is established to address the quantitative relationship between the opening circle of cup and its ellipse projection on radiograph. The varying rules of two-dimensional (2D) radiographic anteversion (RA) and inclination (RI) angles can be analyzed. When the centre of cup is located above X-ray source, with proper 3D RI/RA angles, 2D RA angle can be equal to its 3D counterpart, and 2D RI angle is usually greater than its 3D counterpart. Except for the original point on hip-centered anterior-posterior radiograph, there is no area on radiograph where both 2D RA and RI angles are equal to their 3D counterparts simultaneously. This study proposes an innovative model for accurately explaining how 2D RA/RI angles of cup are varying following different 3D RA/RI angles and location of cup. The analysis results provide clinicians an intuitive grasp of knowledge about 2D RA/RI angles greater or smaller than their 3D counterparts post-operatively. The established model may allow determining the effects of pelvic rotations on 2D radiographic angles of cup.

  20. Seismo-volcano source localization with triaxial broad-band seismic array

    NASA Astrophysics Data System (ADS)

    Inza, L. A.; Mars, J. I.; Métaxian, J. P.; O'Brien, G. S.; Macedo, O.

    2011-10-01

    Seismo-volcano source localization is essential to improve our understanding of eruptive dynamics and of magmatic systems. The lack of clear seismic wave phases prohibits the use of classical location methods. Seismic antennas composed of one-component (1C) seismometers provide a good estimate of the backazimuth of the wavefield. The depth estimation, on the other hand, is difficult or impossible to determine. As in classical seismology, the use of three-component (3C) seismometers is now common in volcano studies. To determine the source location parameters (backazimuth and depth), we extend the 1C seismic antenna approach to 3Cs. This paper discusses a high-resolution location method using a 3C array survey (3C-MUSIC algorithm) with data from two seismic antennas installed on an andesitic volcano in Peru (Ubinas volcano). One of the main scientific questions related to the eruptive process of Ubinas volcano is the relationship between the magmatic explosions and long-period (LP) swarms. After introducing the 3C array theory, we evaluate the robustness of the location method on a full wavefield 3-D synthetic data set generated using a digital elevation model of Ubinas volcano and an homogeneous velocity model. Results show that the backazimuth determined using the 3C array has a smaller error than a 1C array. Only the 3C method allows the recovery of the source depths. Finally, we applied the 3C approach to two seismic events recorded in 2009. Crossing the estimated backazimuth and incidence angles, we find sources located 1000 ± 660 m and 3000 ± 730 m below the bottom of the active crater for the explosion and the LP event, respectively. Therefore, extending 1C arrays to 3C arrays in volcano monitoring allows a more accurate determination of the source epicentre and now an estimate for the depth.

  1. LEAP: Looking beyond pixels with continuous-space EstimAtion of Point sources

    NASA Astrophysics Data System (ADS)

    Pan, Hanjie; Simeoni, Matthieu; Hurley, Paul; Blu, Thierry; Vetterli, Martin

    2017-12-01

    Context. Two main classes of imaging algorithms have emerged in radio interferometry: the CLEAN algorithm and its multiple variants, and compressed-sensing inspired methods. They are both discrete in nature, and estimate source locations and intensities on a regular grid. For the traditional CLEAN-based imaging pipeline, the resolution power of the tool is limited by the width of the synthesized beam, which is inversely proportional to the largest baseline. The finite rate of innovation (FRI) framework is a robust method to find the locations of point-sources in a continuum without grid imposition. The continuous formulation makes the FRI recovery performance only dependent on the number of measurements and the number of sources in the sky. FRI can theoretically find sources below the perceived tool resolution. To date, FRI had never been tested in the extreme conditions inherent to radio astronomy: weak signal / high noise, huge data sets, large numbers of sources. Aims: The aims were (i) to adapt FRI to radio astronomy, (ii) verify it can recover sources in radio astronomy conditions with more accurate positioning than CLEAN, and possibly resolve some sources that would otherwise be missed, (iii) show that sources can be found using less data than would otherwise be required to find them, and (iv) show that FRI does not lead to an augmented rate of false positives. Methods: We implemented a continuous domain sparse reconstruction algorithm in Python. The angular resolution performance of the new algorithm was assessed under simulation, and with visibility measurements from the LOFAR telescope. Existing catalogs were used to confirm the existence of sources. Results: We adapted the FRI framework to radio interferometry, and showed that it is possible to determine accurate off-grid point-source locations and their corresponding intensities. In addition, FRI-based sparse reconstruction required less integration time and smaller baselines to reach a comparable

  2. The density and location of the X-ray absorbing gas in AGN

    NASA Astrophysics Data System (ADS)

    Netzer, H.

    Chandra and XMM-Newton have opened the era of real X-ray spectroscopy. The launch of these spacecraft was followed with great expectations to solve some of the mysteries of AGN, including the determination of the accurate profile of the iron Kα line, the ionization and location of the warm absorbing gas (the "warm absorber", hereafter WA) and the AGN-starburst connection. So far, only a small subset of those big questions have been answered. In particular, new observations of several type-I AGN are providing the first clues about the nature of the various soft X-ray spectral components and the location of the WA. Perhaps the best example regarding the WA location and the various spectral components is the new Chandra observation of NGC 3516. This is a well known Seyfert 1 galaxy that happened to be in a very low state at the time of observations (October 2000). The analysis by Netzer et al (2002) gives the following new results: The X-ray continuum is extremely hard (Γ < 1) and is very different from a single power-law continuum. Its shape is entirely consistent with the fading of the source by a factor of ~8 between 1994 (ASCA observation) and 2000 assuming a 1022 cm-2 line-of sight WA which reacts to the flux of the central ionizing source. A correlation between the observed changes in the source spectral energy distribution (SED) and the hard (E>5 keV) energy luminosity of the source. This can be used to set an upper limit of about 6 × 1017 cm on the WA location. There is a significant contribution, at high energies, from a cold reflecting remote gas which is constant in time and is producing most of the narrow component of the Kα line. The combination of a highly variable central source and a constant far-away ``reflector'' is required to explain the time dependent SED of NGC 3516. The generalization of these results (assuming they are typical) to other type I AGN is very important. They suggest that in many sources much (or even most) of the apparent

  3. Assessment of background particulate matter concentrations in small cities and rural locations--Prince George, Canada.

    PubMed

    Veira, Andreas; Jackson, Peter L; Ainslie, Bruce; Fudge, Dennis

    2013-07-01

    concentrations for small cities in sparsely populated regions like northern British Columbia. In rural areas like northern British Columbia, particulate matter (PM) monitoring stations are usually located close to emission sources and residential areas in order to assess the PM impact on human health. Thus there is a lack of accurate PM background concentration data that represent PM ambient concentrations in the absence of local emissions. The background calculation method developed in this study uses observed meteorological data as well as local source emission locations and provides annual, seasonal and precipitation-related PM background concentrations that are comparable to literature values for four out of six monitoring stations.

  4. ION SOURCE FOR A CALUTRON

    DOEpatents

    Lofgren, E.J.

    1959-04-14

    This patcnt relates to calutron devices and deals particularly with the mechanism used to produce the beam of ions wherein a charge material which is a vapor at room temperature is used. A charge container located outside the tank is connected through several conduits to various points along the arc chamber of the ion source. In addition, the rate of flow of the vapor to the arc chamber is controlled by a throttle valve in each conduit. By this arrangement the arc can be regulated accurately and without appreciable time lag, inasmuch as the rate of vapor flow is immediately responsive to the manipulation of the throttle valves.

  5. North Alabama Lightning Mapping Array (LMA): VHF Source Retrieval Algorithm and Error Analyses

    NASA Technical Reports Server (NTRS)

    Koshak, W. J.; Solakiewicz, R. J.; Blakeslee, R. J.; Goodman, S. J.; Christian, H. J.; Hall, J.; Bailey, J.; Krider, E. P.; Bateman, M. G.; Boccippio, D.

    2003-01-01

    Two approaches are used to characterize how accurately the North Alabama Lightning Mapping Array (LMA) is able to locate lightning VHF sources in space and in time. The first method uses a Monte Carlo computer simulation to estimate source retrieval errors. The simulation applies a VHF source retrieval algorithm that was recently developed at the NASA Marshall Space Flight Center (MSFC) and that is similar, but not identical to, the standard New Mexico Tech retrieval algorithm. The second method uses a purely theoretical technique (i.e., chi-squared Curvature Matrix Theory) to estimate retrieval errors. Both methods assume that the LMA system has an overall rms timing error of 50 ns, but all other possible errors (e.g., multiple sources per retrieval attempt) are neglected. The detailed spatial distributions of retrieval errors are provided. Given that the two methods are completely independent of one another, it is shown that they provide remarkably similar results. However, for many source locations, the Curvature Matrix Theory produces larger altitude error estimates than the (more realistic) Monte Carlo simulation.

  6. Direct-location versus verbal report methods for measuring auditory distance perception in the far field.

    PubMed

    Etchemendy, Pablo E; Spiousas, Ignacio; Calcagno, Esteban R; Abregú, Ezequiel; Eguia, Manuel C; Vergara, Ramiro O

    2018-06-01

    In this study we evaluated whether a method of direct location is an appropriate response method for measuring auditory distance perception of far-field sound sources. We designed an experimental set-up that allows participants to indicate the distance at which they perceive the sound source by moving a visual marker. We termed this method Cross-Modal Direct Location (CMDL) since the response procedure involves the visual modality while the stimulus is presented through the auditory modality. Three experiments were conducted with sound sources located from 1 to 6 m. The first one compared the perceived distances obtained using either the CMDL device or verbal report (VR), which is the response method more frequently used for reporting auditory distance in the far field, and found differences on response compression and bias. In Experiment 2, participants reported visual distance estimates to the visual marker that were found highly accurate. Then, we asked the same group of participants to report VR estimates of auditory distance and found that the spatial visual information, obtained from the previous task, did not influence their reports. Finally, Experiment 3 compared the same responses that Experiment 1 but interleaving the methods, showing a weak, but complex, mutual influence. However, the estimates obtained with each method remained statistically different. Our results show that the auditory distance psychophysical functions obtained with the CMDL method are less susceptible to previously reported underestimation for distances over 2 m.

  7. Concurrent and Accurate Short Read Mapping on Multicore Processors.

    PubMed

    Martínez, Héctor; Tárraga, Joaquín; Medina, Ignacio; Barrachina, Sergio; Castillo, Maribel; Dopazo, Joaquín; Quintana-Ortí, Enrique S

    2015-01-01

    We introduce a parallel aligner with a work-flow organization for fast and accurate mapping of RNA sequences on servers equipped with multicore processors. Our software, HPG Aligner SA (HPG Aligner SA is an open-source application. The software is available at http://www.opencb.org, exploits a suffix array to rapidly map a large fraction of the RNA fragments (reads), as well as leverages the accuracy of the Smith-Waterman algorithm to deal with conflictive reads. The aligner is enhanced with a careful strategy to detect splice junctions based on an adaptive division of RNA reads into small segments (or seeds), which are then mapped onto a number of candidate alignment locations, providing crucial information for the successful alignment of the complete reads. The experimental results on a platform with Intel multicore technology report the parallel performance of HPG Aligner SA, on RNA reads of 100-400 nucleotides, which excels in execution time/sensitivity to state-of-the-art aligners such as TopHat 2+Bowtie 2, MapSplice, and STAR.

  8. Manually locating physical and virtual reality objects.

    PubMed

    Chen, Karen B; Kimmel, Ryan A; Bartholomew, Aaron; Ponto, Kevin; Gleicher, Michael L; Radwin, Robert G

    2014-09-01

    In this study, we compared how users locate physical and equivalent three-dimensional images of virtual objects in a cave automatic virtual environment (CAVE) using the hand to examine how human performance (accuracy, time, and approach) is affected by object size, location, and distance. Virtual reality (VR) offers the promise to flexibly simulate arbitrary environments for studying human performance. Previously, VR researchers primarily considered differences between virtual and physical distance estimation rather than reaching for close-up objects. Fourteen participants completed manual targeting tasks that involved reaching for corners on equivalent physical and virtual boxes of three different sizes. Predicted errors were calculated from a geometric model based on user interpupillary distance, eye location, distance from the eyes to the projector screen, and object. Users were 1.64 times less accurate (p < .001) and spent 1.49 times more time (p = .01) targeting virtual versus physical box corners using the hands. Predicted virtual targeting errors were on average 1.53 times (p < .05) greater than the observed errors for farther virtual targets but not significantly different for close-up virtual targets. Target size, location, and distance, in addition to binocular disparity, affected virtual object targeting inaccuracy. Observed virtual box inaccuracy was less than predicted for farther locations, suggesting possible influence of cues other than binocular vision. Human physical interaction with objects in VR for simulation, training, and prototyping involving reaching and manually handling virtual objects in a CAVE are more accurate than predicted when locating farther objects.

  9. The Remote Food Photography Method accurately estimates dry powdered foods—the source of calories for many infants

    PubMed Central

    Duhé, Abby F.; Gilmore, L. Anne; Burton, Jeffrey H.; Martin, Corby K.; Redman, Leanne M.

    2016-01-01

    Background Infant formula is a major source of nutrition for infants with over half of all infants in the United States consuming infant formula exclusively or in combination with breast milk. The energy in infant powdered formula is derived from the powder and not the water making it necessary to develop methods that can accurately estimate the amount of powder used prior to reconstitution. Objective To assess the use of the Remote Food Photography Method (RFPM) to accurately estimate the weight of infant powdered formula before reconstitution among the standard serving sizes. Methods For each serving size (1-scoop, 2-scoop, 3-scoop, and 4-scoop), a set of seven test bottles and photographs were prepared including the recommended gram weight of powdered formula of the respective serving size by the manufacturer, three bottles and photographs containing 15%, 10%, and 5% less powdered formula than recommended, and three bottles and photographs containing 5%, 10%, and 15% more powdered formula than recommended (n=28). Ratio estimates of the test photographs as compared to standard photographs were obtained using standard RFPM analysis procedures. The ratio estimates and the United States Department of Agriculture (USDA) data tables were used to generate food and nutrient information to provide the RFPM estimates. Statistical Analyses Performed Equivalence testing using the two one-sided t- test (TOST) approach was used to determine equivalence between the actual gram weights and the RFPM estimated weights for all samples, within each serving size, and within under-prepared and over-prepared bottles. Results For all bottles, the gram weights estimated by the RFPM were within 5% equivalence bounds with a slight under-estimation of 0.05 g (90% CI [−0.49, 0.40]; p<0.001) and mean percent error ranging between 0.32% and 1.58% among the four serving sizes. Conclusion The maximum observed mean error was an overestimation of 1.58% of powdered formula by the RFPM under

  10. Coupling a Neural Network with Atmospheric Flow Simulations to Locate and Quantify CH4 Emissions at Well Pads

    NASA Astrophysics Data System (ADS)

    Travis, B. J.; Sauer, J.; Dubey, M. K.

    2017-12-01

    Methane (CH4) leaks from oil and gas production fields are a potentially significant source of atmospheric methane. US DOE's ARPA-E office is supporting research to locate methane emissions at 10 m size well pads to within 1 m. A team led by Aeris Technologies, and that includes LANL, Planetary Science Institute and Rice University has developed an autonomous leak detection system (LDS) employing a compact laser absorption methane sensor, a sonic anemometer and multiport sampling. The LDS system analyzes monitoring data using a convolutional neural network (cNN) to locate and quantify CH4 emissions. The cNN was trained using three sources: (1) ultra-high-resolution simulations of methane transport provided by LANL's coupled atmospheric transport model HIGRAD, for numerous controlled methane release scenarios and methane sampling configurations under variable atmospheric conditions, (2) Field tests at the METEC site in Ft. Collins, CO., and (3) Field data from other sites where point-source surface methane releases were monitored downwind. A cNN learning algorithm is well suited to problems in which the training and observed data are noisy, or correspond to complex sensor data as is typical of meteorological and sensor data over a well pad. Recent studies with our cNN emphasize the importance of tracking wind speeds and directions at fine resolution ( 1 second), and accounting for variations in background CH4 levels. A few cases illustrate the importance of sufficiently long monitoring; short monitoring may not provide enough information to determine accurately a leak location or strength, mainly because of short-term unfavorable wind directions and choice of sampling configuration. Length of multiport duty cycle sampling and sample line flush time as well as number and placement of monitoring sensors can significantly impact ability to locate and quantify leaks. Source location error at less than 10% requires about 30 or more training cases.

  11. Pelvic orientation for total hip arthroplasty in lateral decubitus: can it be accurately measured?

    PubMed

    Sykes, Alice M; Hill, Janet C; Orr, John F; Gill, Harinderjit S; Salazar, Jose J; Humphreys, Lee D; Beverland, David E

    2016-05-16

    During total hip arthroplasty (THA), accurately predicting acetabular cup orientation remains a key challenge, in great part because of uncertainty about pelvic orientation. This pilot study aimed to develop and validate a technique to measure pelvic orientation; establish its accuracy in the location of anatomical landmarks and subsequently; investigate if limb movement during a simulated surgical procedure alters pelvic orientation. The developed technique measured 3-D orientation of an isolated Sawbone pelvis, it was then implemented to measure pelvic orientation in lateral decubitus with post-THA patients (n = 20) using a motion capture system. Orientation of the isolated Sawbone pelvis was accurately measured, demonstrated by high correlations with angular data from a coordinate measurement machine; R-squared values close to 1 for all pelvic axes. When applied to volunteer subjects, largest movements occurred about the longitudinal pelvic axis; internal and external pelvic rotation. Rotations about the anteroposterior axis, which directly affect inclination angles, showed >75% of participants had movement within ±5° of neutral, 0°. The technique accurately measured orientation of the isolated bony pelvis. This was not the case in a simulated theatre environment. Soft tissue landmarks were difficult to palpate repeatedly. These findings have direct clinical relevance, landmark registration in lateral decubitus is a potential source of error, contributing here to large ranges in measured movement. Surgeons must be aware that present techniques using bony landmarks to reference pelvic orientation for cup implantation, both computer-based and mechanical, may not be sufficiently accurate.

  12. HPSLPred: An Ensemble Multi-Label Classifier for Human Protein Subcellular Location Prediction with Imbalanced Source.

    PubMed

    Wan, Shixiang; Duan, Yucong; Zou, Quan

    2017-09-01

    Predicting the subcellular localization of proteins is an important and challenging problem. Traditional experimental approaches are often expensive and time-consuming. Consequently, a growing number of research efforts employ a series of machine learning approaches to predict the subcellular location of proteins. There are two main challenges among the state-of-the-art prediction methods. First, most of the existing techniques are designed to deal with multi-class rather than multi-label classification, which ignores connections between multiple labels. In reality, multiple locations of particular proteins imply that there are vital and unique biological significances that deserve special focus and cannot be ignored. Second, techniques for handling imbalanced data in multi-label classification problems are necessary, but never employed. For solving these two issues, we have developed an ensemble multi-label classifier called HPSLPred, which can be applied for multi-label classification with an imbalanced protein source. For convenience, a user-friendly webserver has been established at http://server.malab.cn/HPSLPred. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Atmospheric Transport Modelling confining potential source location of East-Asian radionuclide detections in May 2010

    NASA Astrophysics Data System (ADS)

    Ross, J. Ole; Ceranna, Lars

    2016-04-01

    The radionuclide component of the International Monitoring System (IMS) to verify compliance with the Comprehensive Nuclear-Test-Ban Treaty (CTBT) is in place to detect tiny traces of fission products from nuclear explosions in the atmosphere. The challenge for the interpretation of IMS radionuclide data is to discriminate radionuclide sources of CTBT relevance against emissions from nuclear facilities. Remarkable activity concentrations of Ba/La-140 occurred at the IMS radionuclide stations RN 37 (Okinawa) and RN 58 (Ussurysk) mid of May 2010. In those days also an elevated Xe-133 level was measured at RN 38 (Takasaki). Additional regional measurements of radioxenon were reported in the press and further analyzed in various publications. The radionuclide analysis gives evidence for the presence of a nuclear fission source between 10 and 12 May 2010. Backward Atmospheric Transport Modelling (ATM) with HYSPLIT driven by 0.2° ECMWF meteorological data for the IMS samples indicates that, assuming a single source, a wide range of source regions is possible including the Korean Peninsula, the Sea of Japan (East Sea), and parts of China and Russia. Further confinement of the possible source location can be provided by atmospheric backtracking for the assumed sampling periods of the reported regional xenon measurements. New studies indicate a very weak seismic event at the DPRK test site on early 12 May 2010. Forward ATM for a pulse release caused by this event shows fairly good agreement with the observed radionuclide signature. Nevertheless, the underlying nuclear fission scenario remains quite unclear and speculative even if assuming a connection between the waveform and the radionuclide event.

  14. Multi-ball and one-ball geolocation and location verification

    NASA Astrophysics Data System (ADS)

    Nelson, D. J.; Townsend, J. L.

    2017-05-01

    We present analysis methods that may be used to geolocate emitters using one or more moving receivers. While some of the methods we present may apply to a broader class of signals, our primary interest is locating and tracking ships from short pulsed transmissions, such as the maritime Automatic Identification System (AIS.) The AIS signal is difficult to process and track since the pulse duration is only 25 milliseconds, and the pulses may only be transmitted every six to ten seconds. Several fundamental problems are addressed, including demodulation of AIS/GMSK signals, verification of the emitter location, accurate frequency and delay estimation and identification of pulse trains from the same emitter. In particular, we present several new correlation methods, including cross-cross correlation that greatly improves correlation accuracy over conventional methods and cross- TDOA and cross-FDOA functions that make it possible to estimate time and frequency delay without the need of computing a two dimensional cross-ambiguity surface. By isolating pulses from the same emitter and accurately tracking the received signal frequency, we are able to accurately estimate the emitter location from the received Doppler characteristics.

  15. Two Simon tasks with different sources of conflict: an ERP study of motion- and location-based compatibility effects.

    PubMed

    Galashan, Daniela; Wittfoth, Matthias; Fehr, Thorsten; Herrmann, Manfred

    2008-07-01

    Behavioral and electrophysiological correlates of two Simon tasks were examined using comparable stimuli but different task-irrelevant and conflict-inducing stimulus features. Whereas target shape was always the task-relevant stimulus attribute, either target location (location-based task) or motion direction within the target stimuli (motion-based task) was used as a source of conflict. Data from ten healthy participants who performed both tasks are presented. In the motion-based task the incompatible condition showed smaller P300 amplitudes at Pz than the compatible condition and the location-based task yielded a trend towards a reduced P300 amplitude in the incompatible condition. For both tasks, no P300 latency differences between the conditions were found at Pz. The results suggest that the motion-based task elicits behavioral and electrophysiological effects comparable with regular Simon tasks. As all stimuli in the motion-based Simon task were presented centrally the present data strongly argue against the attention-shifting account as an explanatory approach.

  16. Extragalactic radio sources - Accurate positions from very-long-baseline interferometry observations

    NASA Technical Reports Server (NTRS)

    Rogers, A. E. E.; Counselman, C. C., III; Hinteregger, H. F.; Knight, C. A.; Robertson, D. S.; Shapiro, I. I.; Whitney, A. R.; Clark, T. A.

    1973-01-01

    Relative positions for 12 extragalactic radio sources have been determined via wide-band very-long-baseline interferometry (wavelength of about 3.8 cm). The standard error, based on consistency between results from widely separated periods of observation, appears to be no more than 0.1 sec for each coordinate of the seven sources that were well observed during two or more periods. The uncertainties in the coordinates determined for the other five sources are larger, but in no case exceed 0.5 sec.

  17. Three-dimensional multi bioluminescent sources reconstruction based on adaptive finite element method

    NASA Astrophysics Data System (ADS)

    Ma, Xibo; Tian, Jie; Zhang, Bo; Zhang, Xing; Xue, Zhenwen; Dong, Di; Han, Dong

    2011-03-01

    Among many optical molecular imaging modalities, bioluminescence imaging (BLI) has more and more wide application in tumor detection and evaluation of pharmacodynamics, toxicity, pharmacokinetics because of its noninvasive molecular and cellular level detection ability, high sensitivity and low cost in comparison with other imaging technologies. However, BLI can not present the accurate location and intensity of the inner bioluminescence sources such as in the bone, liver or lung etc. Bioluminescent tomography (BLT) shows its advantage in determining the bioluminescence source distribution inside a small animal or phantom. Considering the deficiency of two-dimensional imaging modality, we developed three-dimensional tomography to reconstruct the information of the bioluminescence source distribution in transgenic mOC-Luc mice bone with the boundary measured data. In this paper, to study the osteocalcin (OC) accumulation in transgenic mOC-Luc mice bone, a BLT reconstruction method based on multilevel adaptive finite element (FEM) algorithm was used for localizing and quantifying multi bioluminescence sources. Optical and anatomical information of the tissues are incorporated as a priori knowledge in this method, which can reduce the ill-posedness of BLT. The data was acquired by the dual modality BLT and Micro CT prototype system that was developed by us. Through temperature control and absolute intensity calibration, a relative accurate intensity can be calculated. The location of the OC accumulation was reconstructed, which was coherent with the principle of bone differentiation. This result also was testified by ex vivo experiment in the black 96-plate well using the BLI system and the chemiluminescence apparatus.

  18. The need for harmonization of methods for finding locations and magnitudes of air pollution sources using observations of concentrations and wind fields

    NASA Astrophysics Data System (ADS)

    Hanna, Steven R.; Young, George S.

    2017-01-01

    What do the terms "top-down", "inverse", "backwards", "adjoint", "sensor data fusion", "receptor", "source term estimation (STE)", to name several appearing in the current literature, have in common? These varied terms are used by different disciplines to describe the same general methodology - the use of observations of air pollutant concentrations and knowledge of wind fields to identify air pollutant source locations and/or magnitudes. Academic journals are publishing increasing numbers of papers on this topic. Examples of scenarios related to this growing interest, ordered from small scale to large scale, are: use of real-time samplers to quickly estimate the location of a toxic gas release by a terrorist at a large public gathering (e.g., Haupt et al., 2009);

  19. Enhance the Value of a Research Paper: Choosing the Right References and Writing them Accurately.

    PubMed

    Bavdekar, Sandeep B

    2016-03-01

    References help readers identify and locate sources used for justifying the need for conducting the research study, verify methods employed in the study and for discussing the interpretation of results and implications of the study. It is extremely essential that references are accurate and complete. This article provides suggestions regarding choosing references and writing reference list. References are a list of sources that are selected by authors to represent the best documents concerning the research study.1 They constitute the foundation of any research paper. Although generally written towards the end of the article-writing process, they are nevertheless extremely important. They provide the context for the hypothesis and help justify the need for conducting the research study. Authors use references to inform readers about the techniques used for conducting the study and convince them about the appropriateness of methodology used. References help provide appropriate perspective in which the research findings should be seen and interpreted. This communication will discuss the purpose of citations, how to select quality sources for citing and the importance of accuracy while writing the reference list. © Journal of the Association of Physicians of India 2011.

  20. Drinking water from alternative water sources: differences in beliefs, social norms and factors of perceived behavioural control across eight Australian locations.

    PubMed

    Dolnicar, S; Hurlimann, A

    2009-01-01

    Australia is facing serious challenges in the management of water in various urban and regional locations. Two popular responses to these challenges are increasing supply through alternative water sources such as recycled and desalinated water. However, significant gaps exist in our knowledge of community attitudes to these alternative sources of water, particularly for potable use. This paper reports results from an Australian study of community attitudes to alternative water sources. Sixty six qualitative interviews were held at eight locations with distinctly different water situations. This paper explores all three antecedents to the behaviour of drinking recycled water and desalinated water as postulated by the Theory of Planned Behaviour: attitudes, social norms and factors of perceived behavioural control. Key results indicate that while people hold both positive and negative beliefs (mostly cost, health and environmental concerns) about water from alternative sources, nearly all of them are willing to drink it if the water crisis were to deteriorate further. People also feel they lack knowledge and state that information from scientists would influence their decision to drink recycled and desalinated water most. Friends and relatives are most influential in preventing people from drinking recycled water. The findings reported in this paper have major implications for water policy, and will be of particular interest to water engineers. The paper raises a provocative question: Is it better to avoid public consultation in introducing water from alternative sources?

  1. A fast and accurate frequency estimation algorithm for sinusoidal signal with harmonic components

    NASA Astrophysics Data System (ADS)

    Hu, Jinghua; Pan, Mengchun; Zeng, Zhidun; Hu, Jiafei; Chen, Dixiang; Tian, Wugang; Zhao, Jianqiang; Du, Qingfa

    2016-10-01

    Frequency estimation is a fundamental problem in many applications, such as traditional vibration measurement, power system supervision, and microelectromechanical system sensors control. In this paper, a fast and accurate frequency estimation algorithm is proposed to deal with low efficiency problem in traditional methods. The proposed algorithm consists of coarse and fine frequency estimation steps, and we demonstrate that it is more efficient than conventional searching methods to achieve coarse frequency estimation (location peak of FFT amplitude) by applying modified zero-crossing technique. Thus, the proposed estimation algorithm requires less hardware and software sources and can achieve even higher efficiency when the experimental data increase. Experimental results with modulated magnetic signal show that the root mean square error of frequency estimation is below 0.032 Hz with the proposed algorithm, which has lower computational complexity and better global performance than conventional frequency estimation methods.

  2. [Correlating landscape pattern with total nitrogen concentration using a location-weighted sink-source landscape index in the Haihe River Basin, China].

    PubMed

    Sun, Ran-Hao; Chen, Li-Ding; Wang, Wei; Wang, Zhao-Ming

    2012-06-01

    Understanding the effect of land cover pattern on nutrient losses is of great importance in management of water resources. The extensive application of mechanism models is limited in large-scale watersheds owing to the intensive data and calibration requirements. On the other hand, the traditional landscape indexes only take the areas and types of land cover into account, considering less about their topographic features and spatial patterns. We constructed a location-weighted landscape index (LWLI) based on the Lorenz curve, which plots the cumulative proportion of areas for sink and source landscapes respectively against cumulative proportion of their relative location to the outlet in a watershed, including relative elevation, distance and slope. We assessed the effect of land cover pattern on total nitrogen losses in the Haihe River. Firstly, 26 watersheds were derived from 1: 250 000 digital elevation model (DEM), and their "source" and "sink" landscape types were identified from Landsat TM images in 2007. The source" landscapes referred to the paddy land, dry land and residential area, correspondingly the "sink" landscapes referred to the forest and grassland. Secondly, LWLI was calculated according to the landscape types and spatial patterns for each watershed. Thirdly, we accessed the effect of land cover pattern on total nitrogen (TN) flux according to the value of LWLI, comparing with the area proportion of sink-source landscapes. The correlation coefficients were different in three parts of Haihe River, i. e., 0.86, 0.67 and 0.65 in the Yanshan Mts, Taihang Mts and lower Haihe River. The results showed strong correlations between TN and LWLI in contrast to the weak correlations between TN and area proportion of sink and source landscape types. This study indicates the spatial pattern of land cover is essential for accessing the nutrient losses, and the location-weighted landscape pattern analysis may be an alternate to existing water quality models

  3. Assessment of User Home Location Geoinference Methods

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harrison, Joshua J.; Bell, Eric B.; Corley, Courtney D.

    2015-05-29

    This study presents an assessment of multiple approaches to determine the home and/or other important locations to a Twitter user. In this study, we present a unique approach to the problem of geotagged data sparsity in social media when performing geoinferencing tasks. Given the sparsity of explicitly geotagged Twitter data, the ability to perform accurate and reliable user geolocation from a limited number of geotagged posts has proven to be quite useful. In our survey, we have achieved accuracy rates of over 86% in matching Twitter user profile locations with their inferred home locations derived from geotagged posts.

  4. Locating Groundwater Pollution Source using Breakthrough Curve Characteristics and Artificial Neural Networks

    NASA Astrophysics Data System (ADS)

    Kumar, J.; Jain, A.; Srivastava, R.

    2005-12-01

    are peak concentration, time to peak concentration, the widths of the breakthrough curves at 50% and 75% of the peak concentration, and the time base of the breakthrough curve. The second ANN model employs only the first four parameters leaving out the time base. The measurement of breakthrough curve at an observation well involves very high costs in sample collection at suitable time intervals and analysis for various contaminants. The receding portions of the breakthrough curves are normally very long and excluding the time base from modeling would result in considerable cost savings. The feed-forward multi-layer perceptron (MLP) type neural networks trained using the back-propagation algorithm, are employed in this study. The ANN models for the two approaches were developed using simulated data generated for conservative pollutant transport through a homogeneous aquifer. A new approach for ANN training using back-propagation is employed that considers two different error statistics to prevent over-training and under-training of the ANNs. The preliminary results indicate that the ANNs are able to identify the location of the pollution source very efficiently from both the methods of the breakthrough curves characterization.

  5. Detection performance of three different lightning location networks in Beijing area based on accurate fast antenna records

    NASA Astrophysics Data System (ADS)

    Srivastava, A.; Tian, Y.; Wang, D.; Yuan, S.; Chen, Z.; Sun, Z.; Qie, X.

    2016-12-01

    Scientists have developed the regional and worldwide lightning location network to study the lightning physics and locating the lightning stroke. One of the key issue in all the networks; to recognize the performance of the network. The performance of each network would be different based on the regional geographic conditions and the instrumental limitation. To improve the performance of the network. it is necessary to know the ground truth of the network and to discuss about the detection efficiency (DE) and location accuracy (LA). A comparative study has been discussed among World Wide Lightning Location Network (WWLLN), ADvanced TOA and Direction system (ADTD) and Beijing Lightning NETwork (BLNET) lightning detection network in Beijing area. WWLLN locate the cloud to ground (CG) and strong inter cloud (IC) globally without demonstrating any differences. ADTD locate the CG strokes in the entire China as regional. Both these networks are long range detection system that does not provide the focused details of a thunderstorm. BLNET can locate the CG and IC and is focused on thunderstorm detection. The waveform of fast antenna checked manually and the relative DE among the three networks has been obtained based on the CG strokes. The relative LA has been obtained using the matched flashes among these networks as well as LA obtained using the strike on the tower. The relative DE of BLNET is much higher than the ADTD and WWLLN as these networks has approximately similar relative DE. The relative LA of WWLLN and ADTD location is eastward and northward respectively from the BLNET. The LA based on tower observation is relatively high-quality in favor of BLNET. The ground truth of WWLLN, ADTD and BLNET has been obtained and found the performance of BLNET network is much better. This study is helpful to improve the performance of the networks and to provide a belief of LA that can follow the thunderstorm path with the prediction and forecasting of thunderstorm and

  6. Inflatable bladder provides accurate calibration of pressure switch

    NASA Technical Reports Server (NTRS)

    Smith, N. J.

    1965-01-01

    Calibration of a pressure switch is accurately checked by a thin-walled circular bladder. It is placed in the pressure switch and applies force to the switch diaphragm when expanded by an external pressure source. The disturbance to the normal operation of the switch is minimal.

  7. Examining the spatial congruence between data obtained with a novel activity location questionnaire, continuous GPS tracking, and prompted recall surveys

    PubMed Central

    2013-01-01

    Background Place and health researchers are increasingly interested in integrating individuals’ mobility and the experience they have with multiple settings in their studies. In practice, however, few tools exist which allow for rapid and accurate gathering of detailed information on the geographic location of places where people regularly undertake activities. We describe the development and validation of a new activity location questionnaire which can be useful in accounting for multiple environmental influences in large population health investigations. Methods To develop the questionnaire, we relied on a literature review of similar data collection tools and on results of a pilot study wherein we explored content validity, test-retest reliability, and face validity. To estimate convergent validity, we used data from a study of users of a public bicycle share program conducted in Montreal, Canada in 2011. We examined the spatial congruence between questionnaire data and data from three other sources: 1) one-week GPS tracks; 2) activity locations extracted from the GPS tracks; and 3) a prompted recall survey of locations visited during the day. Proximity and convex hull measures were used to compare questionnaire-derived data and GPS and prompted recall survey data. Results In the sample, 75% of questionnaire-reported activity locations were located within 400 meters of an activity location recorded on the GPS track or through the prompted recall survey. Results from convex hull analyses suggested questionnaire activity locations were more concentrated in space than GPS or prompted-recall locations. Conclusions The new questionnaire has high convergent validity and can be used to accurately collect data on regular activity spaces in terms of locations regularly visited. The methods, measures, and findings presented provide new material to further study mobility in place and health research. PMID:24025119

  8. Intelligent navigation and accurate positioning of an assist robot in indoor environments

    NASA Astrophysics Data System (ADS)

    Hua, Bin; Rama, Endri; Capi, Genci; Jindai, Mitsuru; Tsuri, Yosuke

    2017-12-01

    Intact robot's navigation and accurate positioning in indoor environments are still challenging tasks. Especially in robot applications, assisting disabled and/or elderly people in museums/art gallery environments. In this paper, we present a human-like navigation method, where the neural networks control the wheelchair robot to reach the goal location safely, by imitating the supervisor's motions, and positioning in the intended location. In a museum similar environment, the mobile robot starts navigation from various positions, and uses a low-cost camera to track the target picture, and a laser range finder to make a safe navigation. Results show that the neural controller with the Conjugate Gradient Backpropagation training algorithm gives a robust response to guide the mobile robot accurately to the goal position.

  9. Relative Source Locations of Continuous Tremor Before and After the Subplinian Events at Shinmoe-dake, in 2011

    NASA Astrophysics Data System (ADS)

    Ichihara, M.; Matsumoto, S.

    2017-11-01

    Volcano monitoring systems are not always ready to resolve signals at the onset of eruptive activity. This study makes use of stations installed later to calibrate the performance of the stations that had been operated before the eruption. Seven stations recorded continuous volcanic tremor before and during the subplinian eruptions of Shinmoe-dake, Japan, in 2011. We estimated the source locations of the tremor using the amplitude distribution. The stability of the analysis was obtained by careful selection of time windows in which signals from a single source are dominated. The site effects and the regional attenuation factor were evaluated using tremor recorded after the major eruptions by a dense seismic array and a good number of stations. A tremor source changed its depth beneath the crater for 1 week before the major eruption, rising from a depth of a few kilometer to the water layer 3 times, each of which occurred following shallow inflation and minor eruptions. It is interpreted as migration of gas probably with magma, which further transported heat to the water layer and triggered the subplinian eruptions.

  10. Method and System for Gamma-Ray Localization Induced Spacecraft Navigation Using Celestial Gamma-Ray Sources

    NASA Technical Reports Server (NTRS)

    Hisamoto, Chuck (Inventor); Arzoumanian, Zaven (Inventor); Sheikh, Suneel I. (Inventor)

    2015-01-01

    A method and system for spacecraft navigation using distant celestial gamma-ray bursts which offer detectable, bright, high-energy events that provide well-defined characteristics conducive to accurate time-alignment among spatially separated spacecraft. Utilizing assemblages of photons from distant gamma-ray bursts, relative range between two spacecraft can be accurately computed along the direction to each burst's source based upon the difference in arrival time of the burst emission at each spacecraft's location. Correlation methods used to time-align the high-energy burst profiles are provided. The spacecraft navigation may be carried out autonomously or in a central control mode of operation.

  11. The Remote Food Photography Method Accurately Estimates Dry Powdered Foods-The Source of Calories for Many Infants.

    PubMed

    Duhé, Abby F; Gilmore, L Anne; Burton, Jeffrey H; Martin, Corby K; Redman, Leanne M

    2016-07-01

    Infant formula is a major source of nutrition for infants, with more than half of all infants in the United States consuming infant formula exclusively or in combination with breast milk. The energy in infant powdered formula is derived from the powder and not the water, making it necessary to develop methods that can accurately estimate the amount of powder used before reconstitution. Our aim was to assess the use of the Remote Food Photography Method to accurately estimate the weight of infant powdered formula before reconstitution among the standard serving sizes. For each serving size (1 scoop, 2 scoops, 3 scoops, and 4 scoops), a set of seven test bottles and photographs were prepared as follow: recommended gram weight of powdered formula of the respective serving size by the manufacturer; three bottles and photographs containing 15%, 10%, and 5% less powdered formula than recommended; and three bottles and photographs containing 5%, 10%, and 15% more powdered formula than recommended (n=28). Ratio estimates of the test photographs as compared to standard photographs were obtained using standard Remote Food Photography Method analysis procedures. The ratio estimates and the US Department of Agriculture data tables were used to generate food and nutrient information to provide the Remote Food Photography Method estimates. Equivalence testing using the two one-sided t tests approach was used to determine equivalence between the actual gram weights and the Remote Food Photography Method estimated weights for all samples, within each serving size, and within underprepared and overprepared bottles. For all bottles, the gram weights estimated by the Remote Food Photography Method were within 5% equivalence bounds with a slight underestimation of 0.05 g (90% CI -0.49 to 0.40; P<0.001) and mean percent error ranging between 0.32% and 1.58% among the four serving sizes. The maximum observed mean error was an overestimation of 1.58% of powdered formula by the Remote

  12. Testing seismic amplitude source location for fast debris-flow detection at Illgraben, Switzerland

    NASA Astrophysics Data System (ADS)

    Walter, Fabian; Burtin, Arnaud; McArdell, Brian W.; Hovius, Niels; Weder, Bianca; Turowski, Jens M.

    2017-06-01

    Heavy precipitation can mobilize tens to hundreds of thousands of cubic meters of sediment in steep Alpine torrents in a short time. The resulting debris flows (mixtures of water, sediment and boulders) move downstream with velocities of several meters per second and have a high destruction potential. Warning protocols for affected communities rely on raising awareness about the debris-flow threat, precipitation monitoring and rapid detection methods. The latter, in particular, is a challenge because debris-flow-prone torrents have their catchments in steep and inaccessible terrain, where instrumentation is difficult to install and maintain. Here we test amplitude source location (ASL) as a processing scheme for seismic network data for early warning purposes. We use debris-flow and noise seismograms from the Illgraben catchment, Switzerland, a torrent system which produces several debris-flow events per year. Automatic in situ detection is currently based on geophones mounted on concrete check dams and radar stage sensors suspended above the channel. The ASL approach has the advantage that it uses seismometers, which can be installed at more accessible locations where a stable connection to mobile phone networks is available for data communication. Our ASL processing uses time-averaged ground vibration amplitudes to estimate the location of the debris-flow front. Applied to continuous data streams, inversion of the seismic amplitude decay throughout the network is robust and efficient, requires no manual identification of seismic phase arrivals and eliminates the need for a local seismic velocity model. We apply the ASL technique to a small debris-flow event on 19 July 2011, which was captured with a temporary seismic monitoring network. The processing rapidly detects the debris-flow event half an hour before arrival at the outlet of the torrent and several minutes before detection by the in situ alarm system. An analysis of continuous seismic records furthermore

  13. Joint probabilistic determination of earthquake location and velocity structure: application to local and regional events

    NASA Astrophysics Data System (ADS)

    Beucler, E.; Haugmard, M.; Mocquet, A.

    2016-12-01

    The most widely used inversion schemes to locate earthquakes are based on iterative linearized least-squares algorithms and using an a priori knowledge of the propagation medium. When a small amount of observations is available for moderate events for instance, these methods may lead to large trade-offs between outputs and both the velocity model and the initial set of hypocentral parameters. We present a joint structure-source determination approach using Bayesian inferences. Monte-Carlo continuous samplings, using Markov chains, generate models within a broad range of parameters, distributed according to the unknown posterior distributions. The non-linear exploration of both the seismic structure (velocity and thickness) and the source parameters relies on a fast forward problem using 1-D travel time computations. The a posteriori covariances between parameters (hypocentre depth, origin time and seismic structure among others) are computed and explicitly documented. This method manages to decrease the influence of the surrounding seismic network geometry (sparse and/or azimuthally inhomogeneous) and a too constrained velocity structure by inferring realistic distributions on hypocentral parameters. Our algorithm is successfully used to accurately locate events of the Armorican Massif (western France), which is characterized by moderate and apparently diffuse local seismicity.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. High accurate time system of the Low Latitude Meridian Circle.

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Wang, Feng; Li, Zhiming

    In order to obtain the high accurate time signal for the Low Latitude Meridian Circle (LLMC), a new GPS accurate time system is developed which include GPS, 1 MC frequency source and self-made clock system. The second signal of GPS is synchronously used in the clock system and information can be collected by a computer automatically. The difficulty of the cancellation of the time keeper can be overcomed by using this system.

  16. Invariance of wearing location of Omron-BI pedometers: a validation study.

    PubMed

    Zhu, Weimo; Lee, Miyoung

    2010-11-01

    The purpose of this study was to investigate the validity and reliability evidences of the Omron BI pedometer, which could count steps taken even when worn at different locations on the body. Forty (20 males and 20 females) adults were recruited to walk wearing 5 sets, 1 set at a time, of 10 BI pedometers during testing, 1 each at 10 different locations. For comparison, they also wore 2 Yamax Digi-Walker SW-200 pedometers and a Dynastream AMP 331 activity monitor. The subjects walked in 3 free-living conditions: a flat sidewalk, stairs, and mixed conditions. Except for a slight decrease in accuracy in the pant pocket locations, Omron BI pedometers counted steps accurately across other locations when subjects walked on the flat sidewalk, and the performance was consistent across devices and trials. When the subjects climbed up stairs, however, the absolute error % of the pant pocket locations increased significantly (P < .05) and similar or higher error rates were found in the AMP 331 and SW-200s. The Omron BI pedometer can accurately count steps when worn at various locations on the body in free-living conditions except for front pant pocket locations, especially when climbing stairs.

  17. Accurate estimation of object location in an image sequence using helicopter flight data

    NASA Technical Reports Server (NTRS)

    Tang, Yuan-Liang; Kasturi, Rangachar

    1994-01-01

    In autonomous navigation, it is essential to obtain a three-dimensional (3D) description of the static environment in which the vehicle is traveling. For a rotorcraft conducting low-latitude flight, this description is particularly useful for obstacle detection and avoidance. In this paper, we address the problem of 3D position estimation for static objects from a monocular sequence of images captured from a low-latitude flying helicopter. Since the environment is static, it is well known that the optical flow in the image will produce a radiating pattern from the focus of expansion. We propose a motion analysis system which utilizes the epipolar constraint to accurately estimate 3D positions of scene objects in a real world image sequence taken from a low-altitude flying helicopter. Results show that this approach gives good estimates of object positions near the rotorcraft's intended flight-path.

  18. Accurate Land Company, Inc., Acadia Subdivision, Plat 1 and Plat 2

    EPA Pesticide Factsheets

    The EPA is providing notice of an Administrative Penalty Assessment in the form of an Expedited Storm Water Settlement Agreement against Accurate Land Company, Inc., a business located at 12035 University Ave., Suite 100, Clive, IA 50235, for alleged viola

  19. Magnetic Data Interpretation for the Source-Edge Locations in Parts of the Tectonically Active Transition Zone of the Narmada-Son Lineament in Central India

    NASA Astrophysics Data System (ADS)

    Ghosh, G. K.

    2016-02-01

    The study has been carried out in the transition zone of the Narmada-Son lineament (NSL) which is seismically active with various geological complexities, upwarp movement of the mantle material into the crust through fault, fractures lamination and upwelling. NSL is one of the most prominent lineaments in central India after the Himalaya in the Indian geology. The area of investigation extends from longitude 80.25°E to 81.50°E and latitude 23.50°N to 24.37°N in the central part of the Indian continent. Different types of subsurface geological formations viz. alluvial, Gondwana, Deccan traps, Vindhyan, Mahakoshal, Granite and Gneisses groups exist in this area with varying geological ages. In this study area tectonic movement and crustal variation have been taken place during the past time and which might be reason for the variation of magnetic field. Magnetic anomaly suggests that the area has been highly disturbed which causes the Narmada-Son lineament trending in the ENE-WSW direction. Magnetic anomaly variation has been taken place due to the lithological variations subject to the changes in the geological contacts like thrusts and faults in this area. Shallow and deeper sources have been distinguished using frequency domain analysis by applying different filters. To enhance the magnetic data, various types of derivatives to identify the source-edge locations of the causative source bodies. The present study carried out the interpretation using total horizontal derivative, tilt angle derivative, horizontal tilt angle derivative and Cos (θ) derivative map to get source-edge locations. The results derived from various derivatives of magnetic data have been compared with the basement depth solutions calculated from 3D Euler deconvolution. It is suggested that total horizontal derivative, tilt angle derivative and Cos (θ) derivative are the most useful tools for identifying the multiple source edge locations of the causative bodies in this tectonically active

  20. System and Method of Locating Lightning Strikes

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J. (Inventor); Starr, Stanley O. (Inventor)

    2002-01-01

    A system and method of determining locations of lightning strikes has been described. The system includes multiple receivers located around an area of interest, such as a space center or airport. Each receiver monitors both sound and electric fields. The detection of an electric field pulse and a sound wave are used to calculate an area around each receiver in which the lighting is detected. A processor is coupled to the receivers to accurately determine the location of the lighting strike. The processor can manipulate the receiver data to compensate for environmental variables such as wind, temperature, and humidity. Further, each receiver processor can discriminate between distant and local lightning strikes.

  1. Experimentally determining the locations of two astigmatic images for an underwater light source

    NASA Astrophysics Data System (ADS)

    Yang, Pao-Keng; Liu, Jian-You; Ying, Shang-Ping

    2015-05-01

    Images formed by an underwater object from light rays refracted in the sagittal and tangential planes are located at different positions for an oblique viewing position. The overlapping of these two images from the observer's perspective will thus prevent the image-splitting astigmatism from being directly observable. In this work, we present a heuristic method to experimentally visualize the astigmatism. A point light source is used as an underwater object and the emerging wave front is recorded using a Shack-Hartmann wave-front sensor. The wave front is found to deform from a circular paraboloid to an elliptic paraboloid as the viewing position changes from normal to oblique. Using geometric optics, we derive an analytical expression for the image position as a function of the rotating angle of an arm used to carry the wave-front sensor in our experimental setup. The measured results are seen to be in good agreement with the theoretical predictions.

  2. Locating waterfowl observations on aerial surveys

    USGS Publications Warehouse

    Butler, W.I.; Hodges, J.I.; Stehn, R.A.

    1995-01-01

    We modified standard aerial survey data collection to obtain the geographic location for each waterfowl observation on surveys in Alaska during 1987-1993. Using transect navigation with CPS (global positioning system), data recording on continuously running tapes, and a computer data input program, we located observations with an average deviation along transects of 214 m. The method provided flexibility in survey design and data analysis. Although developed for geese nesting near the coast of the Yukon-Kuskokwim Delta, the methods are widely applicable and were used on other waterfowl surveys in Alaska to map distribution and relative abundance of waterfowl. Accurate location data with GIS analysis and display may improve precision and usefulness of data from any aerial transect survey.

  3. Intrusion-Tolerant Location Information Services in Intelligent Vehicular Networks

    NASA Astrophysics Data System (ADS)

    Yan, Gongjun; Yang, Weiming; Shaner, Earl F.; Rawat, Danda B.

    Intelligent Vehicular Networks, known as Vehicle-to-Vehicle and Vehicle-to-Roadside wireless communications (also called Vehicular Ad hoc Networks), are revolutionizing our daily driving with better safety and more infortainment. Most, if not all, applications will depend on accurate location information. Thus, it is of importance to provide intrusion-tolerant location information services. In this paper, we describe an adaptive algorithm that detects and filters the false location information injected by intruders. Given a noisy environment of mobile vehicles, the algorithm estimates the high resolution location of a vehicle by refining low resolution location input. We also investigate results of simulations and evaluate the quality of the intrusion-tolerant location service.

  4. An optimized inverse modelling method for determining the location and strength of a point source releasing airborne material in urban environment

    NASA Astrophysics Data System (ADS)

    Efthimiou, George C.; Kovalets, Ivan V.; Venetsanos, Alexandros; Andronopoulos, Spyros; Argyropoulos, Christos D.; Kakosimos, Konstantinos

    2017-12-01

    An improved inverse modelling method to estimate the location and the emission rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry is incorporated in the Computational Fluid Dynamics code ADREA-HF and presented in this paper. The key improvement in relation to the previous version of the method lies in a two-step segregated approach. At first only the source coordinates are analysed using a correlation function of measured and calculated concentrations. In the second step the source rate is identified by minimizing a quadratic cost function. The validation of the new algorithm is performed by simulating the MUST wind tunnel experiment. A grid-independent flow field solution is firstly attained by applying successive refinements of the computational mesh and the final wind flow is validated against the measurements quantitatively and qualitatively. The old and new versions of the source term estimation method are tested on a coarse and a fine mesh. The new method appeared to be more robust, giving satisfactory estimations of source location and emission rate on both grids. The performance of the old version of the method varied between failure and success and appeared to be sensitive to the selection of model error magnitude that needs to be inserted in its quadratic cost function. The performance of the method depends also on the number and the placement of sensors constituting the measurement network. Of significant interest for the practical application of the method in urban settings is the number of concentration sensors required to obtain a ;satisfactory; determination of the source. The probability of obtaining a satisfactory solution - according to specified criteria -by the new method has been assessed as function of the number of sensors that constitute the measurement network.

  5. Improving Infrasound Signal Detection and Event Location in the Western US Using Atmospheric Modeling

    NASA Astrophysics Data System (ADS)

    Dannemann, F. K.; Park, J.; Marcillo, O. E.; Blom, P. S.; Stump, B. W.; Hayward, C.

    2016-12-01

    Data from five infrasound arrays in the western US jointly operated by University of Utah Seismograph Station and Southern Methodist University are used to test a database-centric processing pipeline, InfraPy, for automated event detection, association and location. Infrasonic array data from a one-year time period (January 1 2012 to December 31 2012) are used. This study focuses on the identification and location of 53 ground-truth verified events produced from near surface military explosions at the Utah Test and Training Range (UTTR). Signals are detected using an adaptive F-detector, which accounts for correlated and uncorrelated time-varying noise in order to reduce false detections due to the presence of coherent noise. Variations in detection azimuth and correlation are found to be consistent with seasonal changes in atmospheric winds. The Bayesian infrasonic source location (BISL) method is used to produce source location and time credibility contours based on posterior probability density functions. Updates to the previous BISL methodology include the application of celerity range and azimuth deviation distributions in order to accurately account for the spatial and temporal variability of infrasound propagation through the atmosphere. These priors are estimated by ray tracing through Ground-to-Space (G2S) atmospheric models as a function of season and time of day using historic atmospheric characterizations from 2007 to 2013. Out of the 53 events, 31 are successfully located using the InfraPy pipeline. Confidence contour areas for maximum a posteriori event locations produce error estimates which are reduced a maximum of 98% and an average of 25% from location estimates utilizing a simple time independent uniform atmosphere. We compare real-time ray tracing results with the statistical atmospheric priors used in this study to examine large time differences between known origin times and estimated origin times that might be due to the misidentification of

  6. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space- based observatories drive the end-to-end data analysis and distribution requirements. The Swift mission is managed by the GSFC, and includes an international team of contributors that each bring their unique perspective that have proven invaluable to the mission. The spacecraft bus, provided by Spectrum Astro, Inc. was procured through a Rapid Spacecraft Development Office (RSDO) contract by the GSFC. There are three instruments: the Burst Alert Telescope (BAT) provided by the GSFC; the X-Ray Telescope (XRT) provided by a team led by the Pennsylvania State University (PSU); and the Ultra-Violet Optical Telescope (UVOT), again managed by PSU. The Mission Operations Center (MOC) was developed by and is located at PSU. Science archiving and data analysis centers are located at the GSFC, in the UK and in Italy.

  7. Turbulence spectra in the noise source regions of the flow around complex surfaces

    NASA Technical Reports Server (NTRS)

    Olsen, W. A.; Boldman, D. R.

    1983-01-01

    The complex turbulent flow around three complex surfaces was measured in detail with a hot wire. The measured data include extensive spatial surveys of the mean velocity and turbulence intensity and measurements of the turbulence spectra and scale length at many locations. The publication of the turbulence data is completed by reporting a summary of the turbulence spectra that were measured within the noise source locations of the flow. The results suggest some useful simplifications in modeling the very complex turbulent flow around complex surfaces for aeroacoustic predictive models. The turbulence spectra also show that noise data from scale models of moderate size can be accurately scaled up to full size.

  8. Microseismic monitoring of soft-rock landslide: contribution of a 3D velocity model for the location of seismic sources.

    NASA Astrophysics Data System (ADS)

    Floriane, Provost; Jean-Philippe, Malet; Cécile, Doubre; Julien, Gance; Alessia, Maggi; Agnès, Helmstetter

    2015-04-01

    Characterizing the micro-seismic activity of landslides is an important parameter for a better understanding of the physical processes controlling landslide behaviour. However, the location of the seismic sources on landslides is a challenging task mostly because of (a) the recording system geometry, (b) the lack of clear P-wave arrivals and clear wave differentiation, (c) the heterogeneous velocities of the ground. The objective of this work is therefore to test whether the integration of a 3D velocity model in probabilistic seismic source location codes improves the quality of the determination especially in depth. We studied the clay-rich landslide of Super-Sauze (French Alps). Most of the seismic events (rockfalls, slidequakes, tremors...) are generated in the upper part of the landslide near the main scarp. The seismic recording system is composed of two antennas with four vertical seismometers each located on the east and west sides of the seismically active part of the landslide. A refraction seismic campaign was conducted in August 2014 and a 3D P-wave model has been estimated using the Quasi-Newton tomography inversion algorithm. The shots of the seismic campaign are used as calibration shots to test the performance of the different location methods and to further update the 3D velocity model. Natural seismic events are detected with a semi-automatic technique using a frequency threshold. The first arrivals are picked using a kurtosis-based method and compared to the manual picking. Several location methods were finally tested. We compared a non-linear probabilistic method coupled with the 3D P-wave model and a beam-forming method inverted for an apparent velocity. We found that the Quasi-Newton tomography inversion algorithm provides results coherent with the original underlaying topography. The velocity ranges from 500 m.s-1 at the surface to 3000 m.s-1 in the bedrock. For the majority of the calibration shots, the use of a 3D velocity model

  9. Approaches to the study of neural coding of sound source location and sound envelope in real environments

    PubMed Central

    Kuwada, Shigeyuki; Bishop, Brian; Kim, Duck O.

    2012-01-01

    The major functions of the auditory system are recognition (what is the sound) and localization (where is the sound). Although each of these has received considerable attention, rarely are they studied in combination. Furthermore, the stimuli used in the bulk of studies did not represent sound location in real environments and ignored the effects of reverberation. Another ignored dimension is the distance of a sound source. Finally, there is a scarcity of studies conducted in unanesthetized animals. We illustrate a set of efficient methods that overcome these shortcomings. We use the virtual auditory space method (VAS) to efficiently present sounds at different azimuths, different distances and in different environments. Additionally, this method allows for efficient switching between binaural and monaural stimulation and alteration of acoustic cues singly or in combination to elucidate neural mechanisms underlying localization and recognition. Such procedures cannot be performed with real sound field stimulation. Our research is designed to address the following questions: Are IC neurons specialized to process what and where auditory information? How does reverberation and distance of the sound source affect this processing? How do IC neurons represent sound source distance? Are neural mechanisms underlying envelope processing binaural or monaural? PMID:22754505

  10. A measurement-based generalized source model for Monte Carlo dose simulations of CT scans

    PubMed Central

    Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun

    2018-01-01

    The goal of this study is to develop a generalized source model (GSM) for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients’ CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology. PMID:28079526

  11. A measurement-based generalized source model for Monte Carlo dose simulations of CT scans

    NASA Astrophysics Data System (ADS)

    Ming, Xin; Feng, Yuanming; Liu, Ransheng; Yang, Chengwen; Zhou, Li; Zhai, Hezheng; Deng, Jun

    2017-03-01

    The goal of this study is to develop a generalized source model for accurate Monte Carlo dose simulations of CT scans based solely on the measurement data without a priori knowledge of scanner specifications. The proposed generalized source model consists of an extended circular source located at x-ray target level with its energy spectrum, source distribution and fluence distribution derived from a set of measurement data conveniently available in the clinic. Specifically, the central axis percent depth dose (PDD) curves measured in water and the cone output factors measured in air were used to derive the energy spectrum and the source distribution respectively with a Levenberg-Marquardt algorithm. The in-air film measurement of fan-beam dose profiles at fixed gantry was back-projected to generate the fluence distribution of the source model. A benchmarked Monte Carlo user code was used to simulate the dose distributions in water with the developed source model as beam input. The feasibility and accuracy of the proposed source model was tested on a GE LightSpeed and a Philips Brilliance Big Bore multi-detector CT (MDCT) scanners available in our clinic. In general, the Monte Carlo simulations of the PDDs in water and dose profiles along lateral and longitudinal directions agreed with the measurements within 4%/1 mm for both CT scanners. The absolute dose comparison using two CTDI phantoms (16 cm and 32 cm in diameters) indicated a better than 5% agreement between the Monte Carlo-simulated and the ion chamber-measured doses at a variety of locations for the two scanners. Overall, this study demonstrated that a generalized source model can be constructed based only on a set of measurement data and used for accurate Monte Carlo dose simulations of patients’ CT scans, which would facilitate patient-specific CT organ dose estimation and cancer risk management in the diagnostic and therapeutic radiology.

  12. Consider the source: Children link the accuracy of text-based sources to the accuracy of the author.

    PubMed

    Vanderbilt, Kimberly E; Ochoa, Karlena D; Heilbrun, Jayd

    2018-05-06

    The present research investigated whether young children link the accuracy of text-based information to the accuracy of its author. Across three experiments, three- and four-year-olds (N = 231) received information about object labels from accurate and inaccurate sources who provided information both in text and verbally. Of primary interest was whether young children would selectively rely on information provided by more accurate sources, regardless of the form in which the information was communicated. Experiment 1 tested children's trust in text-based information (e.g., books) written by an author with a history of either accurate or inaccurate verbal testimony and found that children showed greater trust in books written by accurate authors. Experiment 2 replicated the findings of Experiment 1 and extended them by showing that children's selective trust in more accurate text-based sources was not dependent on experience trusting or distrusting the author's verbal testimony. Experiment 3 investigated this understanding in reverse by testing children's trust in verbal testimony communicated by an individual who had authored either accurate or inaccurate text-based information. Experiment 3 revealed that children showed greater trust in individuals who had authored accurate rather than inaccurate books. Experiment 3 also demonstrated that children used the accuracy of text-based sources to make inferences about the mental states of the authors. Taken together, these results suggest children do indeed link the reliability of text-based sources to the reliability of the author. Statement of Contribution Existing knowledge Children use sources' prior accuracy to predict future accuracy in face-to-face verbal interactions. Children who are just learning to read show increased trust in text bases (vs. verbal) information. It is unknown whether children consider authors' prior accuracy when judging the accuracy of text-based information. New knowledge added by this

  13. Self characterization of a coded aperture array for neutron source imaging

    DOE PAGES

    Volegov, P. L.; Danly, C. R.; Fittinghoff, D. N.; ...

    2014-12-15

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning DT plasma during the stagnation stage of ICF implosions. Since the neutron source is small (~100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be preciselymore » aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.« less

  14. Self characterization of a coded aperture array for neutron source imaging

    NASA Astrophysics Data System (ADS)

    Volegov, P. L.; Danly, C. R.; Fittinghoff, D. N.; Guler, N.; Merrill, F. E.; Wilde, C. H.

    2014-12-01

    The neutron imaging system at the National Ignition Facility (NIF) is an important diagnostic tool for measuring the two-dimensional size and shape of the neutrons produced in the burning deuterium-tritium plasma during the stagnation stage of inertial confinement fusion implosions. Since the neutron source is small (˜100 μm) and neutrons are deeply penetrating (>3 cm) in all materials, the apertures used to achieve the desired 10-μm resolution are 20-cm long, triangular tapers machined in gold foils. These gold foils are stacked to form an array of 20 apertures for pinhole imaging and three apertures for penumbral imaging. These apertures must be precisely aligned to accurately place the field of view of each aperture at the design location, or the location of the field of view for each aperture must be measured. In this paper we present a new technique that has been developed for the measurement and characterization of the precise location of each aperture in the array. We present the detailed algorithms used for this characterization and the results of reconstructed sources from inertial confinement fusion implosion experiments at NIF.

  15. Influence of sound source location on the behavior and physiology of the precedence effect in cats.

    PubMed

    Dent, Micheal L; Tollin, Daniel J; Yin, Tom C T

    2009-08-01

    Psychophysical experiments on the precedence effect (PE) in cats have shown that they localize pairs of auditory stimuli presented from different locations in space based on the spatial position of the stimuli and the interstimulus delay (ISD) between the stimuli in a manner similar to humans. Cats exhibit localization dominance for pairs of transient stimuli with |ISDs| from approximately 0.4 to 10 ms, summing localization for |ISDs| < 0.4 ms and breakdown of fusion for |ISDs| > 10 ms, which is the approximate echo threshold. The neural correlates to the PE have been described in both anesthetized and unanesthetized animals at many levels from auditory nerve to cortex. Single-unit recordings from the inferior colliculus (IC) and auditory cortex of cats demonstrate that neurons respond to both lead and lag sounds at ISDs above behavioral echo thresholds, but the response to the lag is reduced at shorter ISDs, consistent with localization dominance. Here the influence of the relative locations of the leading and lagging sources on the PE was measured behaviorally in a psychophysical task and physiologically in the IC of awake behaving cats. At all configurations of lead-lag stimulus locations, the cats behaviorally exhibited summing localization, localization dominance, and breakdown of fusion. Recordings from the IC of awake behaving cats show neural responses paralleling behavioral measurements. Both behavioral and physiological results suggest systematically shorter echo thresholds when stimuli are further apart in space.

  16. Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

    PubMed Central

    Dent, Micheal L.; Tollin, Daniel J.; Yin, Tom C. T.

    2009-01-01

    Psychophysical experiments on the precedence effect (PE) in cats have shown that they localize pairs of auditory stimuli presented from different locations in space based on the spatial position of the stimuli and the interstimulus delay (ISD) between the stimuli in a manner similar to humans. Cats exhibit localization dominance for pairs of transient stimuli with |ISDs| from ∼0.4 to 10 ms, summing localization for |ISDs| < 0.4 ms and breakdown of fusion for |ISDs| > 10 ms, which is the approximate echo threshold. The neural correlates to the PE have been described in both anesthetized and unanesthetized animals at many levels from auditory nerve to cortex. Single-unit recordings from the inferior colliculus (IC) and auditory cortex of cats demonstrate that neurons respond to both lead and lag sounds at ISDs above behavioral echo thresholds, but the response to the lag is reduced at shorter ISDs, consistent with localization dominance. Here the influence of the relative locations of the leading and lagging sources on the PE was measured behaviorally in a psychophysical task and physiologically in the IC of awake behaving cats. At all configurations of lead-lag stimulus locations, the cats behaviorally exhibited summing localization, localization dominance, and breakdown of fusion. Recordings from the IC of awake behaving cats show neural responses paralleling behavioral measurements. Both behavioral and physiological results suggest systematically shorter echo thresholds when stimuli are further apart in space. PMID:19439668

  17. Contributed Review: Source-localization algorithms and applications using time of arrival and time difference of arrival measurements

    NASA Astrophysics Data System (ADS)

    Li, Xinya; Deng, Zhiqun Daniel; Rauchenstein, Lynn T.; Carlson, Thomas J.

    2016-04-01

    Locating the position of fixed or mobile sources (i.e., transmitters) based on measurements obtained from sensors (i.e., receivers) is an important research area that is attracting much interest. In this paper, we review several representative localization algorithms that use time of arrivals (TOAs) and time difference of arrivals (TDOAs) to achieve high signal source position estimation accuracy when a transmitter is in the line-of-sight of a receiver. Circular (TOA) and hyperbolic (TDOA) position estimation approaches both use nonlinear equations that relate the known locations of receivers and unknown locations of transmitters. Estimation of the location of transmitters using the standard nonlinear equations may not be very accurate because of receiver location errors, receiver measurement errors, and computational efficiency challenges that result in high computational burdens. Least squares and maximum likelihood based algorithms have become the most popular computational approaches to transmitter location estimation. In this paper, we summarize the computational characteristics and position estimation accuracies of various positioning algorithms. By improving methods for estimating the time-of-arrival of transmissions at receivers and transmitter location estimation algorithms, transmitter location estimation may be applied across a range of applications and technologies such as radar, sonar, the Global Positioning System, wireless sensor networks, underwater animal tracking, mobile communications, and multimedia.

  18. Researchermap: a tool for visualizing author locations using Google maps.

    PubMed

    Rastegar-Mojarad, Majid; Bales, Michael E; Yu, Hong

    2013-01-01

    We hereby present ResearcherMap, a tool to visualize locations of authors of scholarly papers. In response to a query, the system returns a map of author locations. To develop the system we first populated a database of author locations, geocoding institution locations for all available institutional affiliation data in our database. The database includes all authors of Medline papers from 1990 to 2012. We conducted a formative heuristic usability evaluation of the system and measured the system's accuracy and performance. The accuracy of finding the accurate address is 97.5% in our system.

  19. Accurate beacon positioning method for satellite-to-ground optical communication.

    PubMed

    Wang, Qiang; Tong, Ling; Yu, Siyuan; Tan, Liying; Ma, Jing

    2017-12-11

    In satellite laser communication systems, accurate positioning of the beacon is essential for establishing a steady laser communication link. For satellite-to-ground optical communication, the main influencing factors on the acquisition of the beacon are background noise and atmospheric turbulence. In this paper, we consider the influence of background noise and atmospheric turbulence on the beacon in satellite-to-ground optical communication, and propose a new locating algorithm for the beacon, which takes the correlation coefficient obtained by curve fitting for image data as weights. By performing a long distance laser communication experiment (11.16 km), we verified the feasibility of this method. Both simulation and experiment showed that the new algorithm can accurately obtain the position of the centroid of beacon. Furthermore, for the distortion of the light spot through atmospheric turbulence, the locating accuracy of the new algorithm was 50% higher than that of the conventional gray centroid algorithm. This new approach will be beneficial for the design of satellite-to ground optical communication systems.

  20. Eliminating the influence of source spectrum of white light scanning interferometry through time-delay estimation algorithm

    NASA Astrophysics Data System (ADS)

    Zhou, Yunfei; Cai, Hongzhi; Zhong, Liyun; Qiu, Xiang; Tian, Jindong; Lu, Xiaoxu

    2017-05-01

    In white light scanning interferometry (WLSI), the accuracy of profile measurement achieved with the conventional zero optical path difference (ZOPD) position locating method is closely related with the shape of interference signal envelope (ISE), which is mainly decided by the spectral distribution of illumination source. For a broadband light with Gaussian spectral distribution, the corresponding shape of ISE reveals a symmetric distribution, so the accurate ZOPD position can be achieved easily. However, if the spectral distribution of source is irregular, the shape of ISE will become asymmetric or complex multi-peak distribution, WLSI cannot work well through using ZOPD position locating method. Aiming at this problem, we propose time-delay estimation (TDE) based WLSI method, in which the surface profile information is achieved by using the relative displacement of interference signal between different pixels instead of the conventional ZOPD position locating method. Due to all spectral information of interference signal (envelope and phase) are utilized, in addition to revealing the advantage of high accuracy, the proposed method can achieve profile measurement with high accuracy in the case that the shape of ISE is irregular while ZOPD position locating method cannot work. That is to say, the proposed method can effectively eliminate the influence of source spectrum.

  1. The SAFOD Pilot Hole seismic array: Wave propagation effects as a function of sensor depth and source location

    NASA Astrophysics Data System (ADS)

    Chavarria, J. Andres; Malin, Peter E.; Shalev, Eylon

    2004-05-01

    In July 2002 we installed a vertical array of seismometers in the San Andreas Fault Observatory at Depth (SAFOD) Pilot Hole (PH). The bottom of this 32 level, 1240 m long array of 3- components is located at a depth of ~2100 m below ground. Surface-explosion and microearthquake seismograms recorded by the array give valuable insights into the structure of the SAFOD site. The ratios of P- and S-wave velocities (Vp/Vs) along the array suggest the presence of two faults intersecting the PH. The Vp/Vs ratios also depend on source location, with high values to the NW, and lower ones to the SE, correlating with high and low creep rates along the SAF, respectively. Since higher ratios can be produced by increasing fluid saturation, we suggest that this effect might account for both our observations and their correlation with the creep distribution.

  2. Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine

    NASA Astrophysics Data System (ADS)

    Ottermo, Fredric; Möllerström, Erik; Nordborg, Anders; Hylander, Jonny; Bernhoff, Hans

    2017-07-01

    Noise levels emitted from a 200 kW H-rotor vertical-axis wind turbine have been measured using a microphone array at four different positions, each at a hub-height distance from the tower. The microphone array, comprising 48 microphones in a spiral pattern, allows for directional mapping of the noise sources in the range of 500 Hz to 4 kHz. The produced images indicate that most of the noise is generated in a narrow azimuth-angle range, compatible with the location where increased turbulence is known to be present in the flow, as a result of the previous passage of a blade and its support arms. It is also shown that a semi-empirical model for inflow-turbulence noise seems to produce noise levels of the correct order of magnitude, based on the amount of turbulence that could be expected from power extraction considerations.

  3. Station Correction Uncertainty in Multiple Event Location Algorithms and the Effect on Error Ellipses

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Erickson, Jason P.; Carlson, Deborah K.; Ortiz, Anne

    Accurate location of seismic events is crucial for nuclear explosion monitoring. There are several sources of error in seismic location that must be taken into account to obtain high confidence results. Most location techniques account for uncertainties in the phase arrival times (measurement error) and the bias of the velocity model (model error), but they do not account for the uncertainty of the velocity model bias. By determining and incorporating this uncertainty in the location algorithm we seek to improve the accuracy of the calculated locations and uncertainty ellipses. In order to correct for deficiencies in the velocity model, itmore » is necessary to apply station specific corrections to the predicted arrival times. Both master event and multiple event location techniques assume that the station corrections are known perfectly, when in reality there is an uncertainty associated with these corrections. For multiple event location algorithms that calculate station corrections as part of the inversion, it is possible to determine the variance of the corrections. The variance can then be used to weight the arrivals associated with each station, thereby giving more influence to stations with consistent corrections. We have modified an existing multiple event location program (based on PMEL, Pavlis and Booker, 1983). We are exploring weighting arrivals with the inverse of the station correction standard deviation as well using the conditional probability of the calculated station corrections. This is in addition to the weighting already given to the measurement and modeling error terms. We re-locate a group of mining explosions that occurred at Black Thunder, Wyoming, and compare the results to those generated without accounting for station correction uncertainty.« less

  4. Accurate electron gun-positioning mechanism for electron beam-mapping of large cross-section magnetic surfaces

    NASA Astrophysics Data System (ADS)

    Anderson, F. S. B.; Middleton, F.; Colchin, R. J.; Million, D.

    1989-04-01

    A method of accurately supporting and positioning an electron source inside a large cross-sectional area magnetic field which provides very low electron beam occlusion is reported. The application of electrical discharge machining to the fabrication of a 1-m truss support structure has provided an extremely long, rigid and mechanically strong electron gun support. Reproducible electron gun positioning to within 1 mm has been achieved at any location within a 1×0.6-m2 area. The extremely thin sections of the support truss (≤1.5 mm) have kept the electron beam occlusion to less than 3 mm. The support and drive mechanism have been designed and fabricated at the University of Wisconsin for application to the mapping of the magnetic surface structure of the Advanced Toroidal Facility torsatron1 at the Oak Ridge National Laboratory.

  5. Locating the source of projectile fluid droplets

    NASA Astrophysics Data System (ADS)

    Varney, Christopher R.; Gittes, Fred

    2011-08-01

    The ill-posed projectile problem of finding the source height from spattered droplets of viscous fluid is a longstanding obstacle to accident reconstruction and crime-scene analysis. It is widely known how to infer the impact angle of droplets on a surface from the elongation of their impact profiles. However, the lack of velocity information makes finding the height of the origin from the impact position and angle of individual drops not possible. From aggregate statistics of the spatter and basic equations of projectile motion, we introduce a reciprocal correlation plot that is effective when the polar launch angle is concentrated in a narrow range. The vertical coordinate depends on the orientation of the spattered surface and equals the tangent of the impact angle for a level surface. When the horizontal plot coordinate is twice the reciprocal of the impact distance, we can infer the source height as the slope of the data points in the reciprocal correlation plot. If the distribution of launch angles is not narrow, failure of the method is evident in the lack of linear correlation. We perform a number of experimental trials, as well as numerical calculations and show that the height estimate is relatively insensitive to aerodynamic drag. Besides its possible relevance for crime investigation, reciprocal-plot analysis of spatter may find application to volcanism and other topics and is most immediately applicable for undergraduate science and engineering students in the context of crime-scene analysis.

  6. Strong S-wave attenuation and actively degassing magma beneath Taal volcano, Philippines, inferred from source location analysis using high-frequency seismic amplitudes

    NASA Astrophysics Data System (ADS)

    Kumagai, H.; Lacson, R. _Jr., Jr.; Maeda, Y.; Figueroa, M. S., II; Yamashina, T.

    2014-12-01

    Taal volcano, Philippines, is one of the world's most dangerous volcanoes given its history of explosive eruptions and its close proximity to populated areas. A key feature of these eruptions is that the eruption vents were not limited to Main Crater but occurred on the flanks of Volcano Island. This complex eruption history and the fact that thousands of people inhabit the island, which has been declared a permanent danger zone, together imply an enormous potential for disasters. The Philippine Institute of Volcanology and Seismology (PHIVOLCS) constantly monitors Taal, and international collaborations have conducted seismic, geodetic, electromagnetic, and geochemical studies to investigate the volcano's magma system. Realtime broadband seismic, GPS, and magnetic networks were deployed in 2010 to improve monitoring capabilities and to better understand the volcano. The seismic network has recorded volcano-tectonic (VT) events beneath Volcano Island. We located these VT events based on high-frequency seismic amplitudes, and found that some events showed considerable discrepancies between the amplitude source locations and hypocenters determined by using onset arrival times. Our analysis of the source location discrepancies points to the existence of a region of strong S-wave attenuation near the ground surface beneath the east flank of Volcano Island. This region is beneath the active fumarolic area and above sources of pressure contributing inflation and deflation, and it coincides with a region of high electrical conductivity. The high-attenuation region matches that inferred from an active-seismic survey conducted at Taal in 1993. Our results, synthesized with previous results, suggest that this region represents actively degassing magma near the surface, and imply a high risk of future eruptions on the east flank of Volcano Island.

  7. Holographic Location of Distant Points (PREPRINT)

    DTIC Science & Technology

    2010-06-01

    respects and the nonimaging systems have significant advantages. This paper shows how to use holograms to construct a flat, solid, small, accurate, small... nonimaging point location system. 15. SUBJECT TERMS imagery, holographic 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT: SAR 18...respects and the nonimaging systems we have discussed earlier (1, 2) have significant advantages. This paper shows how to use holograms to construct a

  8. Macro and micro diversity of Clostridium difficile isolates from diverse sources and geographical locations.

    PubMed

    Stabler, Richard A; Dawson, Lisa F; Valiente, Esmeralda; Cairns, Michelle D; Martin, Melissa J; Donahue, Elizabeth H; Riley, Thomas V; Songer, J Glenn; Kuijper, Ed J; Dingle, Kate E; Wren, Brendan W

    2012-01-01

    Clostridium difficile has emerged rapidly as the leading cause of antibiotic-associated diarrheal disease, with the temporal and geographical appearance of dominant PCR ribotypes such as 017, 027 and 078. Despite this continued threat, we have a poor understanding of how or why particular variants emerge and the sources of strains that dominate different human populations. We have undertaken a breadth genotyping study using multilocus sequence typing (MLST) analysis of 385 C. difficile strains from diverse sources by host (human, animal and food), geographical locations (North America, Europe and Australia) and PCR ribotypes. Results identified 18 novel sequence types (STs) and 3 new allele sequences and confirmed the presence of five distinct clonal lineages generally associated with outbreaks of C. difficile infection in humans. Strains of animal and food origin were found of both ST-1 and ST-11 that are frequently associated with human disease. An in depth MLST analysis of the evolutionary distant ST-11/PCR ribotype 078 clonal lineage revealed that ST-11 can be found in alternative but closely related PCR ribotypes and PCR ribotype 078 alleles contain mutations generating novel STs. PCR ribotype 027 and 017 lineages may consist of two divergent subclades. Furthermore evidence of microdiversity was present within the heterogeneous clade 1. This study helps to define the evolutionary origin of dominant C. difficile lineages and demonstrates that C. difficile is continuing to evolve in concert with human activity.

  9. Are secondary data sources on the neighbourhood food environment accurate? Case-study in Glasgow, UK.

    PubMed

    Cummins, Steven; Macintyre, Sally

    2009-12-01

    To assess the validity of a publicly available list of food stores through field observations of their existence, in order to contribute to research on neighbourhood food environments and health. All multiple-owned supermarkets, and a 1 in 8 sample of other food outlets, listed in 1997 and 2007 in the public register of food premises held by Glasgow City Council, Scotland, were visited to establish whether they were trading as foodstores. Postcode sectors in which foodstores were located were classified into least, middling and most deprived neighbourhoods. In total, 325 listed foodstores were visited in 1997 and 508 in 2007. Of these 87% and 88%, respectively, were trading as foodstores. There was a very slight gradient in validity by deprivation, with validity higher in least deprived neighbourhoods, though this was not statistically significant. There was reasonable, but not perfect, agreement between the list of food premises and field observations, with nearly 1 in 9 of sampled foodstores not present on the ground. Since the use of inaccurate secondary data sources may affect estimates of relationships between the neighbourhood food environment and health, further work is required to establish the validity of such data in different contexts.

  10. Underwater hydrophone location survey

    NASA Technical Reports Server (NTRS)

    Cecil, Jack B.

    1993-01-01

    The Atlantic Undersea Test and Evaluation Center (AUTEC) is a U.S. Navy test range located on Andros Island, Bahamas, and a Division of the Naval Undersea Warfare Center (NUWC), Newport, RI. The Headquarters of AUTEC is located at a facility in West Palm Beach, FL. AUTEC's primary mission is to provide the U.S. Navy with a deep-water test and evaluation facility for making underwater acoustic measurements, testing and calibrating sonars, and providing accurate underwater, surface, and in-air tracking data on surface ships, submarines, aircraft, and weapon systems. Many of these programs are in support of Antisubmarine Warfare (ASW), undersea research and development programs, and Fleet assessment and operational readiness trials. Most tests conducted at AUTEC require precise underwater tracking (plus or minus 3 yards) of multiple acoustic signals emitted with the correct waveshape and repetition criteria from either a surface craft or underwater vehicle.

  11. Approach to identifying pollutant source and matching flow field

    NASA Astrophysics Data System (ADS)

    Liping, Pang; Yu, Zhang; Hongquan, Qu; Tao, Hu; Wei, Wang

    2013-07-01

    Accidental pollution events often threaten people's health and lives, and it is necessary to identify a pollutant source rapidly so that prompt actions can be taken to prevent the spread of pollution. But this identification process is one of the difficulties in the inverse problem areas. This paper carries out some studies on this issue. An approach using single sensor information with noise was developed to identify a sudden continuous emission trace pollutant source in a steady velocity field. This approach first compares the characteristic distance of the measured concentration sequence to the multiple hypothetical measured concentration sequences at the sensor position, which are obtained based on a source-three-parameter multiple hypotheses. Then we realize the source identification by globally searching the optimal values with the objective function of the maximum location probability. Considering the large amount of computation load resulting from this global searching, a local fine-mesh source search method based on priori coarse-mesh location probabilities is further used to improve the efficiency of identification. Studies have shown that the flow field has a very important influence on the source identification. Therefore, we also discuss the impact of non-matching flow fields with estimation deviation on identification. Based on this analysis, a method for matching accurate flow field is presented to improve the accuracy of identification. In order to verify the practical application of the above method, an experimental system simulating a sudden pollution process in a steady flow field was set up and some experiments were conducted when the diffusion coefficient was known. The studies showed that the three parameters (position, emission strength and initial emission time) of the pollutant source in the experiment can be estimated by using the method for matching flow field and source identification.

  12. Location of Microearthquakes in Various Noisy Environments Using Envelope Stacking

    NASA Astrophysics Data System (ADS)

    Oye, V.; Gharti, H.

    2009-12-01

    Monitoring of microearthquakes is routinely conducted in various environments such as hydrocarbon and geothermal reservoirs, mines, dams, seismically active faults, volcanoes, nuclear power plants and CO2 storages. In many of these cases the handled data is sensitive and the interpretation of the data may be vital. In some cases, such as during mining or hydraulic fracturing activities, the number of microearthquakes is very large with tens to thousands of events per hour. In others, almost no events occur during a week and furthermore, it might not be anticipated that many events occur at all. However, the general setup of seismic networks, including surface and downhole stations, is usually optimized to record as many microearthquakes as possible, thereby trying to lower the detection threshold of the network. This process is obviously limited to some extent. Most microearthquake location techniques take advantage of a combination of P- and S-wave onset times that often can be picked reliably in an automatic mode. Moreover, when using seismic wave onset times, sometimes in combination with seismic wave polarization, these methods are more accurate compared to migration-based location routines. However, many events cannot be located because their magnitude is too small, i.e. the P- and/or S-wave onset times cannot be picked accurately on a sufficient number of receivers. Nevertheless, these small events are important for the interpretation of the processes that are monitored and even an inferior estimate of event locations and strengths is valuable information. Moreover, the smaller the event the more often such events statistically occur and the more important such additional information becomes. In this study we try to enhance the performance of any microseismic network, providing additional estimates of event locations below the actual detection threshold. We present a migration-based event location method, where we project the recorded seismograms onto the ray

  13. Development and Validation of a Multidisciplinary Tool for Accurate and Efficient Rotorcraft Noise Prediction (MUTE)

    NASA Technical Reports Server (NTRS)

    Liu, Yi; Anusonti-Inthra, Phuriwat; Diskin, Boris

    2011-01-01

    A physics-based, systematically coupled, multidisciplinary prediction tool (MUTE) for rotorcraft noise was developed and validated with a wide range of flight configurations and conditions. MUTE is an aggregation of multidisciplinary computational tools that accurately and efficiently model the physics of the source of rotorcraft noise, and predict the noise at far-field observer locations. It uses systematic coupling approaches among multiple disciplines including Computational Fluid Dynamics (CFD), Computational Structural Dynamics (CSD), and high fidelity acoustics. Within MUTE, advanced high-order CFD tools are used around the rotor blade to predict the transonic flow (shock wave) effects, which generate the high-speed impulsive noise. Predictions of the blade-vortex interaction noise in low speed flight are also improved by using the Particle Vortex Transport Method (PVTM), which preserves the wake flow details required for blade/wake and fuselage/wake interactions. The accuracy of the source noise prediction is further improved by utilizing a coupling approach between CFD and CSD, so that the effects of key structural dynamics, elastic blade deformations, and trim solutions are correctly represented in the analysis. The blade loading information and/or the flow field parameters around the rotor blade predicted by the CFD/CSD coupling approach are used to predict the acoustic signatures at far-field observer locations with a high-fidelity noise propagation code (WOPWOP3). The predicted results from the MUTE tool for rotor blade aerodynamic loading and far-field acoustic signatures are compared and validated with a variation of experimental data sets, such as UH60-A data, DNW test data and HART II test data.

  14. A phase coherence approach to identifying co-located earthquakes and tremor

    NASA Astrophysics Data System (ADS)

    Hawthorne, J. C.; Ampuero, J.-P.

    2018-05-01

    We present and use a phase coherence approach to identify seismic signals that have similar path effects but different source time functions: co-located earthquakes and tremor. The method used is a phase coherence-based implementation of empirical matched field processing, modified to suit tremor analysis. It works by comparing the frequency-domain phases of waveforms generated by two sources recorded at multiple stations. We first cross-correlate the records of the two sources at a single station. If the sources are co-located, this cross-correlation eliminates the phases of the Green's function. It leaves the relative phases of the source time functions, which should be the same across all stations so long as the spatial extent of the sources are small compared with the seismic wavelength. We therefore search for cross-correlation phases that are consistent across stations as an indication of co-located sources. We also introduce a method to obtain relative locations between the two sources, based on back-projection of interstation phase coherence. We apply this technique to analyse two tremor-like signals that are thought to be composed of a number of earthquakes. First, we analyse a 20 s long seismic precursor to a M 3.9 earthquake in central Alaska. The analysis locates the precursor to within 2 km of the mainshock, and it identifies several bursts of energy—potentially foreshocks or groups of foreshocks—within the precursor. Second, we examine several minutes of volcanic tremor prior to an eruption at Redoubt Volcano. We confirm that the tremor source is located close to repeating earthquakes identified earlier in the tremor sequence. The amplitude of the tremor diminishes about 30 s before the eruption, but the phase coherence results suggest that the tremor may persist at some level through this final interval.

  15. The status of accurately locating forest inventory and analysis plots using the Global Positioning System

    Treesearch

    Michael Hoppus; Andrew Lister

    2007-01-01

    Historically, field crews used Global Positioning System (GPS) coordinates to establish and relocate plots, as well as document their general location. During the past 5 years, the increase in Geographic Information System (GIS) capabilities and in customer requests to use the spatial relationships between Forest Inventory and Analysis (FIA) plot data and other GIS...

  16. Truncated RAP-MUSIC (TRAP-MUSIC) for MEG and EEG source localization.

    PubMed

    Mäkelä, Niko; Stenroos, Matti; Sarvas, Jukka; Ilmoniemi, Risto J

    2018-02-15

    Electrically active brain regions can be located applying MUltiple SIgnal Classification (MUSIC) on magneto- or electroencephalographic (MEG; EEG) data. We introduce a new MUSIC method, called truncated recursively-applied-and-projected MUSIC (TRAP-MUSIC). It corrects a hidden deficiency of the conventional RAP-MUSIC algorithm, which prevents estimation of the true number of brain-signal sources accurately. The correction is done by applying a sequential dimension reduction to the signal-subspace projection. We show that TRAP-MUSIC significantly improves the performance of MUSIC-type localization; in particular, it successfully and robustly locates active brain regions and estimates their number. We compare TRAP-MUSIC and RAP-MUSIC in simulations with varying key parameters, e.g., signal-to-noise ratio, correlation between source time-courses, and initial estimate for the dimension of the signal space. In addition, we validate TRAP-MUSIC with measured MEG data. We suggest that with the proposed TRAP-MUSIC method, MUSIC-type localization could become more reliable and suitable for various online and offline MEG and EEG applications. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Close binding of identity and location in visual feature perception

    NASA Technical Reports Server (NTRS)

    Johnston, J. C.; Pashler, H.

    1990-01-01

    The binding of identity and location information in disjunctive feature search was studied. Ss searched a heterogeneous display for a color or a form target, and reported both target identity and location. To avoid better than chance guessing of target identity (by choosing the target less likely to have been seen), the difficulty of the two targets was equalized adaptively; a mathematical model was used to quantify residual effects. A spatial layout was used that minimized postperceptual errors in reporting location. Results showed strong binding of identity and location perception. After correction for guessing, no perception of identity without location was found. A weak trend was found for accurate perception of target location without identity. We propose that activated features generate attention-calling "interrupt" signals, specifying only location; attention then retrieves the properties at that location.

  18. Noise Source Location and Flow Field Measurements on Supersonic Jets and Implications Regarding Broadband Shock Noise

    NASA Technical Reports Server (NTRS)

    Podboy, Gary G.; Wernet, Mark P.; Clem, Michelle M.; Fagan, Amy F.

    2017-01-01

    An experiment was conducted in an effort to obtain data that would provide a better understanding of the origins of broadband shock noise (BBSN). Phased array noise source location and two types of flow field data (background oriented schlieren and particle image velocimetry) were acquired on unheated, single-stream jets. Results are presented for one subsonic and four supersonic operating conditions. These data show that BBSN is created primarily in the downstream portion of the shock train with peak BBSN production occurring near where the average size of the turbulent structures is equal to the shockcell spacing. These data tend to validate theories that BBSN is created by turbulent structures that are as large or larger than the shock spacing.

  19. Noise Sources in Photometry and Radial Velocities

    NASA Astrophysics Data System (ADS)

    Oshagh, Mahmoudreza

    The quest for Earth-like, extrasolar planets (exoplanets), especially those located inside the habitable zone of their host stars, requires techniques sensitive enough to detect the faint signals produced by those planets. The radial velocity (RV) and photometric transit methods are the most widely used and also the most efficient methods for detecting and characterizing exoplanets. However, presence of astrophysical "noise" makes it difficult to detect and accurately characterize exoplanets. It is important to note that the amplitude of such astrophysical noise is larger than both the signal of Earth-like exoplanets and state-of-the-art instrumentation limit precision, making this a pressing topic that needs to be addressed. In this chapter, I present a general review of the main sources of noise in photometric and RV observations, namely, stellar oscillations, granulation, and magnetic activity. Moreover, for each noise source I discuss the techniques and observational strategies which allow us to mitigate their impact.

  20. A novel multi-segment path analysis based on a heterogeneous velocity model for the localization of acoustic emission sources in complex propagation media.

    PubMed

    Gollob, Stephan; Kocur, Georg Karl; Schumacher, Thomas; Mhamdi, Lassaad; Vogel, Thomas

    2017-02-01

    In acoustic emission analysis, common source location algorithms assume, independently of the nature of the propagation medium, a straight (shortest) wave path between the source and the sensors. For heterogeneous media such as concrete, the wave travels in complex paths due to the interaction with the dissimilar material contents and with the possible geometrical and material irregularities present in these media. For instance, cracks and large air voids present in concrete influence significantly the way the wave travels, by causing wave path deviations. Neglecting these deviations by assuming straight paths can introduce significant errors to the source location results. In this paper, a novel source localization method called FastWay is proposed. It accounts, contrary to most available shortest path-based methods, for the different effects of material discontinuities (cracks and voids). FastWay, based on a heterogeneous velocity model, uses the fastest rather than the shortest travel paths between the source and each sensor. The method was evaluated both numerically and experimentally and the results from both evaluation tests show that, in general, FastWay was able to locate sources of acoustic emissions more accurately and reliably than the traditional source localization methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Sodium intakes of US children and adults from foods and beverages by location of origin and by specific food source.

    PubMed

    Drewnowski, Adam; Rehm, Colin D

    2013-05-28

    Sodium intakes, from foods and beverages, of 22,852 persons in the National Health and Nutrition Examination Surveys (NHANES 2003-2008) were examined by specific food source and by food location of origin. Analyses were based on a single 24-h recall. Separate analyses were conducted for children (6-11 years of age), adolescents (12-19), and adults (20-50 and ≥51 years). Grouping of like foods (e.g., food sources) used a scheme proposed by the National Cancer Institute, which divides foods/beverages into 96 food subgroups (e.g., pizza, yeast breads or cold cuts). Food locations of origin were stores (e.g., grocery, convenience and specialty stores), quick-service restaurant/pizza (QSR), full-service restaurant (FSR), school, or other. Food locations of sodium were also evaluated by race/ethnicity amongst adults. Stores provided between 58.1% and 65.2% of dietary sodium, whereas QSR and FSR together provided between 18.9% and 31.8% depending on age. The proportion of sodium from QSR varied from 10.1% to 19.9%, whereas that from FSR varied from 3.4% to 13.3%. School meals provided 10.4% of sodium for 6-11 year olds and 6.0% for 12-19 year olds. Pizza from QSR, the top away from home food item, provided 5.4% of sodium in adolescents. QSR pizza, chicken, burgers and Mexican dishes combined provided 7.8% of total sodium in adult diets. Most sodium came from foods purchased in stores. Food manufacturers, restaurants, and grocery stores all have a role to play in reducing the amount of sodium in the American diet.

  2. Sodium Intakes of US Children and Adults from Foods and Beverages by Location of Origin and by Specific Food Source

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D.

    2013-01-01

    Sodium intakes, from foods and beverages, of 22,852 persons in the National Health and Nutrition Examination Surveys (NHANES 2003–2008) were examined by specific food source and by food location of origin. Analyses were based on a single 24-h recall. Separate analyses were conducted for children (6–11 years of age), adolescents (12–19), and adults (20–50 and ≥51 years). Grouping of like foods (e.g., food sources) used a scheme proposed by the National Cancer Institute, which divides foods/beverages into 96 food subgroups (e.g., pizza, yeast breads or cold cuts). Food locations of origin were stores (e.g., grocery, convenience and specialty stores), quick-service restaurant/pizza (QSR), full-service restaurant (FSR), school, or other. Food locations of sodium were also evaluated by race/ethnicity amongst adults. Stores provided between 58.1% and 65.2% of dietary sodium, whereas QSR and FSR together provided between 18.9% and 31.8% depending on age. The proportion of sodium from QSR varied from 10.1% to 19.9%, whereas that from FSR varied from 3.4% to 13.3%. School meals provided 10.4% of sodium for 6–11 year olds and 6.0% for 12–19 year olds. Pizza from QSR, the top away from home food item, provided 5.4% of sodium in adolescents. QSR pizza, chicken, burgers and Mexican dishes combined provided 7.8% of total sodium in adult diets. Most sodium came from foods purchased in stores. Food manufacturers, restaurants, and grocery stores all have a role to play in reducing the amount of sodium in the American diet. PMID:23760055

  3. Brady's Geothermal Field - March 2016 Vibroseis SEG-Y Files and UTM Locations

    DOE Data Explorer

    Kurt Feigl

    2016-03-31

    PoroTomo March 2016 (Task 6.4) Updated vibroseis source locations with UTM locations. Supersedes gdr.openei.org/submissions/824. Updated vibroseis source location data for Stages 1-4, PoroTomo March 2016. This revision includes source point locations in UTM format (meters) for all four Stages of active source acquisition. Vibroseis sweep data were collected on a Signature Recorder unit (mfr Seismic Source) mounted in the vibroseis cab during the March 2016 PoroTomo active seismic survey Stages 1 to 4. Each sweep generated a GPS timed SEG-Y file with 4 input channels and a 20 second record length. Ch1 = pilot sweep, Ch2 = accelerometer output from the vibe's mass, Ch3 = accel output from the baseplase, and Ch4 = weighted sum of the accelerometer outputs. SEG-Y files are available via the links below.

  4. Advances in audio source seperation and multisource audio content retrieval

    NASA Astrophysics Data System (ADS)

    Vincent, Emmanuel

    2012-06-01

    Audio source separation aims to extract the signals of individual sound sources from a given recording. In this paper, we review three recent advances which improve the robustness of source separation in real-world challenging scenarios and enable its use for multisource content retrieval tasks, such as automatic speech recognition (ASR) or acoustic event detection (AED) in noisy environments. We present a Flexible Audio Source Separation Toolkit (FASST) and discuss its advantages compared to earlier approaches such as independent component analysis (ICA) and sparse component analysis (SCA). We explain how cues as diverse as harmonicity, spectral envelope, temporal fine structure or spatial location can be jointly exploited by this toolkit. We subsequently present the uncertainty decoding (UD) framework for the integration of audio source separation and audio content retrieval. We show how the uncertainty about the separated source signals can be accurately estimated and propagated to the features. Finally, we explain how this uncertainty can be efficiently exploited by a classifier, both at the training and the decoding stage. We illustrate the resulting performance improvements in terms of speech separation quality and speaker recognition accuracy.

  5. Collaborative mining of graph patterns from multiple sources

    NASA Astrophysics Data System (ADS)

    Levchuk, Georgiy; Colonna-Romanoa, John

    2016-05-01

    Intelligence analysts require automated tools to mine multi-source data, including answering queries, learning patterns of life, and discovering malicious or anomalous activities. Graph mining algorithms have recently attracted significant attention in intelligence community, because the text-derived knowledge can be efficiently represented as graphs of entities and relationships. However, graph mining models are limited to use-cases involving collocated data, and often make restrictive assumptions about the types of patterns that need to be discovered, the relationships between individual sources, and availability of accurate data segmentation. In this paper we present a model to learn the graph patterns from multiple relational data sources, when each source might have only a fragment (or subgraph) of the knowledge that needs to be discovered, and segmentation of data into training or testing instances is not available. Our model is based on distributed collaborative graph learning, and is effective in situations when the data is kept locally and cannot be moved to a centralized location. Our experiments show that proposed collaborative learning achieves learning quality better than aggregated centralized graph learning, and has learning time comparable to traditional distributed learning in which a knowledge of data segmentation is needed.

  6. Neural population encoding and decoding of sound source location across sound level in the rabbit inferior colliculus

    PubMed Central

    Delgutte, Bertrand

    2015-01-01

    At lower levels of sensory processing, the representation of a stimulus feature in the response of a neural population can vary in complex ways across different stimulus intensities, potentially changing the amount of feature-relevant information in the response. How higher-level neural circuits could implement feature decoding computations that compensate for these intensity-dependent variations remains unclear. Here we focused on neurons in the inferior colliculus (IC) of unanesthetized rabbits, whose firing rates are sensitive to both the azimuthal position of a sound source and its sound level. We found that the azimuth tuning curves of an IC neuron at different sound levels tend to be linear transformations of each other. These transformations could either increase or decrease the mutual information between source azimuth and spike count with increasing level for individual neurons, yet population azimuthal information remained constant across the absolute sound levels tested (35, 50, and 65 dB SPL), as inferred from the performance of a maximum-likelihood neural population decoder. We harnessed evidence of level-dependent linear transformations to reduce the number of free parameters in the creation of an accurate cross-level population decoder of azimuth. Interestingly, this decoder predicts monotonic azimuth tuning curves, broadly sensitive to contralateral azimuths, in neurons at higher levels in the auditory pathway. PMID:26490292

  7. Applying time-reverse-imaging techniques to locate individual low-frequency earthquakes on the San Andreas fault near Cholame, California

    NASA Astrophysics Data System (ADS)

    Horstmann, T.; Harrington, R. M.; Cochran, E.; Shelly, D. R.

    2013-12-01

    Observations of non-volcanic tremor have become ubiquitous in recent years. In spite of the abundance of observations, locating tremor remains a difficult task because of the lack of distinctive phase arrivals. Here we use time-reverse-imaging techniques that do not require identifying phase arrivals to locate individual low-frequency-earthquakes (LFEs) within tremor episodes on the San Andreas fault near Cholame, California. Time windows of 1.5-second duration containing LFEs are selected from continuously recorded waveforms of the local seismic network filtered between 1-5 Hz. We propagate the time-reversed seismic signal back through the subsurface using a staggered-grid finite-difference code. Assuming all rebroadcasted waveforms result from similar wave fields at the source origin, we search for wave field coherence in time and space to obtain the source location and origin time where the constructive interference is a maximum. We use an interpolated velocity model with a grid spacing of 100 m and a 5 ms time step to calculate the relative curl field energy amplitudes for each rebroadcasted seismogram every 50 ms for each grid point in the model. Finally, we perform a grid search for coherency in the curl field using a sliding time window, and taking the absolute value of the correlation coefficient to account for differences in radiation pattern. The highest median cross-correlation coefficient value over at a given grid point indicates the source location for the rebroadcasted event. Horizontal location errors based on the spatial extent of the highest 10% cross-correlation coefficient are on the order of 4 km, and vertical errors on the order of 3 km. Furthermore, a test of the method using earthquake data shows that the method produces an identical hypocentral location (within errors) as that obtained by standard ray-tracing methods. We also compare the event locations to a LFE catalog that locates the LFEs from stacked waveforms of repeated LFEs

  8. Real-time realizations of the Bayesian Infrasonic Source Localization Method

    NASA Astrophysics Data System (ADS)

    Pinsky, V.; Arrowsmith, S.; Hofstetter, A.; Nippress, A.

    2015-12-01

    The Bayesian Infrasonic Source Localization method (BISL), introduced by Mordak et al. (2010) and upgraded by Marcillo et al. (2014) is destined for the accurate estimation of the atmospheric event origin at local, regional and global scales by the seismic and infrasonic networks and arrays. The BISL is based on probabilistic models of the source-station infrasonic signal propagation time, picking time and azimuth estimate merged with a prior knowledge about celerity distribution. It requires at each hypothetical source location, integration of the product of the corresponding source-station likelihood functions multiplied by a prior probability density function of celerity over the multivariate parameter space. The present BISL realization is generally time-consuming procedure based on numerical integration. The computational scheme proposed simplifies the target function so that integrals are taken exactly and are represented via standard functions. This makes the procedure much faster and realizable in real-time without practical loss of accuracy. The procedure executed as PYTHON-FORTRAN code demonstrates high performance on a set of the model and real data.

  9. Emitter location errors in electronic recognition system

    NASA Astrophysics Data System (ADS)

    Matuszewski, Jan; Dikta, Anna

    2017-04-01

    The paper describes some of the problems associated with emitter location calculations. This aspect is the most important part of the series of tasks in the electronic recognition systems. The basic tasks include: detection of emission of electromagnetic signals, tracking (determining the direction of emitter sources), signal analysis in order to classify different emitter types and the identification of the sources of emission of the same type. The paper presents a brief description of the main methods of emitter localization and the basic mathematical formulae for calculating their location. The errors' estimation has been made to determine the emitter location for three different methods and different scenarios of emitters and direction finding (DF) sensors deployment in the electromagnetic environment. The emitter has been established using a special computer program. On the basis of extensive numerical calculations, the evaluation of precise emitter location in the recognition systems for different configuration alignment of bearing devices and emitter was conducted. The calculations which have been made based on the simulated data for different methods of location are presented in the figures and respective tables. The obtained results demonstrate that calculation of the precise emitter location depends on: the number of DF sensors, the distances between emitter and DF sensors, their mutual location in the reconnaissance area and bearing errors. The precise emitter location varies depending on the number of obtained bearings. The higher the number of bearings, the better the accuracy of calculated emitter location in spite of relatively high bearing errors for each DF sensor.

  10. A passive RFID-based location system for personnel and asset monitoring.

    PubMed

    Hsiao, Rong-Shue; Kao, Chun-Hao; Chen, Tian-Xiang; Chen, Jui-Lun

    2018-01-01

    Typical radio frequency identification (RFID) access control system can be ineffective if an unauthorized person tailgates an authorized person through an access area. To propose a system by using indoor locating and tracking techniques address this problem, which is to prevent unauthorized Alzheimer's and dementia patients from getting lost including by tailgating. To achieve accurate target location, passive RFID deployment strategy is studied and a fingerprinting based passive RFID localization algorithm is proposed. The proposed system was evaluated in a building environment to simulate the performance of access control. RFID reader was installed on ceiling near the access area and tags were stitched on both shoulders of the experiment subject's garments. The probability of the error distance within 0.3 m achieved 97% in the warning area; the location precision achieved 97% within 0.4 m in the monitoring area. The result showed that if an unauthorized person enters the restricted area, the system can initiate an alert signal accurately. Therefore, the proposed system is very suitable to be used in nursing home or hospital to prevent unauthorized personnel and assets entering/exiting a confined location.

  11. Method of fan sound mode structure determination computer program user's manual: Microphone location program

    NASA Technical Reports Server (NTRS)

    Pickett, G. F.; Wells, R. A.; Love, R. A.

    1977-01-01

    A computer user's manual describing the operation and the essential features of the microphone location program is presented. The Microphone Location Program determines microphone locations that ensure accurate and stable results from the equation system used to calculate modal structures. As part of the computational procedure for the Microphone Location Program, a first-order measure of the stability of the equation system was indicated by a matrix 'conditioning' number.

  12. PADF electromagnetic source localization using extremum seeking control

    NASA Astrophysics Data System (ADS)

    Al Issa, Huthaifa A.; Ordóñez, Raúl

    2014-10-01

    Wireless Sensor Networks (WSNs) are a significant technology attracting considerable research interest. Recent advances in wireless communications and electronics have enabled the development of low-cost, low-power and multi-functional sensors that are small in size and communicate over short distances. Most WSN applications require knowing or measuring locations of thousands of sensors accurately. For example, sensing data without knowing the sensor location is often meaningless. Locations of sensor nodes are fundamental to providing location stamps, locating and tracking objects, forming clusters, and facilitating routing. This research focused on the modeling and implementation of distributed, mobile radar sensor networks. In particular, we worked on the problem of Position-Adaptive Direction Finding (PADF), to determine the location of a non- collaborative transmitter, possibly hidden within a structure, by using a team of cooperative intelligent sensor networks. Position-Adaptive radar concepts have been formulated and investigated at the Air Force Research Laboratory (AFRL) within the past few years. In this paper, we present the simulation performance analysis on the application aspect. We apply Extremum Seeking Control (ESC) schemes by using the swarm seeking problem, where the goal is to design a control law for each individual sensor that can minimize the error metric by adapting the sensor positions in real-time, thereby minimizing the unknown estimation error. As a result we achieved source seeking and collision avoidance of the entire group of the sensor positions.

  13. Distinct regions of the hippocampus are associated with memory for different spatial locations.

    PubMed

    Jeye, Brittany M; MacEvoy, Sean P; Karanian, Jessica M; Slotnick, Scott D

    2018-05-15

    In the present functional magnetic resonance imaging (fMRI) study, we aimed to evaluate whether distinct regions of the hippocampus were associated with spatial memory for items presented in different locations of the visual field. In Experiment 1, during the study phase, participants viewed abstract shapes in the left or right visual field while maintaining central fixation. At test, old shapes were presented at fixation and participants classified each shape as previously in the "left" or "right" visual field followed by an "unsure"-"sure"-"very sure" confidence rating. Accurate spatial memory for shapes in the left visual field was isolated by contrasting accurate versus inaccurate spatial location responses. This contrast produced one hippocampal activation in which the interaction between item type and accuracy was significant. The analogous contrast for right visual field shapes did not produce activity in the hippocampus; however, the contrast of high confidence versus low confidence right-hits produced one hippocampal activation in which the interaction between item type and confidence was significant. In Experiment 2, the same paradigm was used but shapes were presented in each quadrant of the visual field during the study phase. Accurate memory for shapes in each quadrant, exclusively masked by accurate memory for shapes in the other quadrants, produced a distinct activation in the hippocampus. A multi-voxel pattern analysis (MVPA) of hippocampal activity revealed a significant correlation between behavioral spatial location accuracy and hippocampal MVPA accuracy across participants. The findings of both experiments indicate that distinct hippocampal regions are associated with memory for different visual field locations. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Using meta-information of a posteriori Bayesian solutions of the hypocentre location task for improving accuracy of location error estimation

    NASA Astrophysics Data System (ADS)

    Debski, Wojciech

    2015-06-01

    The spatial location of sources of seismic waves is one of the first tasks when transient waves from natural (uncontrolled) sources are analysed in many branches of physics, including seismology, oceanology, to name a few. Source activity and its spatial variability in time, the geometry of recording network, the complexity and heterogeneity of wave velocity distribution are all factors influencing the performance of location algorithms and accuracy of the achieved results. Although estimating of the earthquake foci location is relatively simple, a quantitative estimation of the location accuracy is really a challenging task even if the probabilistic inverse method is used because it requires knowledge of statistics of observational, modelling and a priori uncertainties. In this paper, we addressed this task when statistics of observational and/or modelling errors are unknown. This common situation requires introduction of a priori constraints on the likelihood (misfit) function which significantly influence the estimated errors. Based on the results of an analysis of 120 seismic events from the Rudna copper mine operating in southwestern Poland, we propose an approach based on an analysis of Shanon's entropy calculated for the a posteriori distribution. We show that this meta-characteristic of the a posteriori distribution carries some information on uncertainties of the solution found.

  15. Trace elements and common ions in southeastern Idaho snow: Regional air pollutant tracers for source area emissions

    USGS Publications Warehouse

    Abbott, M.; Einerson, J.; Schuster, P.; Susong, D.; Taylor, Howard E.; ,

    2004-01-01

    Snow sampling and analysis methods which produce accurate and ultra-low measurements of trace elements and common ion concentration in southeastern Idaho snow, were developed. Snow samples were collected over two winters to assess trace elements and common ion concentrations in air pollutant fallout across the southeastern Idaho. The area apportionment of apportionment of fallout concentrations measured at downwind location were investigated using pattern recognition and multivariate statistical technical techniques. Results show a high level of contribution from phosphates processing facilities located outside Pocatello in the southern portion of the Eastern Snake River Plain, and no obvious source area profiles other than at Pocatello.

  16. Precisely locating the Klamath Falls, Oregon, earthquakes

    USGS Publications Warehouse

    Qamar, A.; Meagher, K.L.

    1993-01-01

    In this article we present preliminary results of a close-in, instrumental study of the Klamath Falls earthquake sequence, carried as a cooperative effort by scientists from the U.S Geological Survey (USGS) and universities in Washington, Orgeon, and California. In addition to obtaining much mroe accurate earthquake locations, this study has improved our understanding of the relationship between seismicity and mapped faults in the region. 

  17. Montana SIP: Table c, (viii) Administrative Rules of Montana, Subchapter 10, Preconstruction Permit Requirements for Major Stationary Sources or Major Modifications Locating Within Attainment or Unclassified Areas

    EPA Pesticide Factsheets

    Montana SIP: Table c, (viii) Administrative Rules of Montana, Subchapter 10, Preconstruction Permit Requirements for Major Stationary Sources or Major Modifications Locating Within Attainment or Unclassified Areas

  18. Measurements of scalar released from point sources in a turbulent boundary layer

    NASA Astrophysics Data System (ADS)

    Talluru, K. M.; Hernandez-Silva, C.; Philip, J.; Chauhan, K. A.

    2017-04-01

    Measurements of velocity and concentration fluctuations for a horizontal plume released at several wall-normal locations in a turbulent boundary layer (TBL) are discussed in this paper. The primary objective of this study is to establish a systematic procedure to acquire accurate single-point concentration measurements for a substantially long time so as to obtain converged statistics of long tails of probability density functions of concentration. Details of the calibration procedure implemented for long measurements are presented, which include sensor drift compensation to eliminate the increase in average background concentration with time. While most previous studies reported measurements where the source height is limited to, {{s}z}/δ ≤slant 0.2 , where s z is the wall-normal source height and δ is the boundary layer thickness, here results of concentration fluctuations when the plume is released in the outer layer are emphasised. Results of mean and root-mean-square (r.m.s.) profiles of concentration for elevated sources agree with the well-accepted reflected Gaussian model (Fackrell and Robins 1982 J. Fluid. Mech. 117). However, there is clear deviation from the reflected Gaussian model for source in the intermittent region of TBL particularly at locations higher than the source itself. Further, we find that the plume half-widths are different for the mean and r.m.s. concentration profiles. Long sampling times enabled us to calculate converged probability density functions at high concentrations and these are found to exhibit exponential distribution.

  19. A Fast and Accurate Sparse Continuous Signal Reconstruction by Homotopy DCD with Non-Convex Regularization

    PubMed Central

    Wang, Tianyun; Lu, Xinfei; Yu, Xiaofei; Xi, Zhendong; Chen, Weidong

    2014-01-01

    In recent years, various applications regarding sparse continuous signal recovery such as source localization, radar imaging, communication channel estimation, etc., have been addressed from the perspective of compressive sensing (CS) theory. However, there are two major defects that need to be tackled when considering any practical utilization. The first issue is off-grid problem caused by the basis mismatch between arbitrary located unknowns and the pre-specified dictionary, which would make conventional CS reconstruction methods degrade considerably. The second important issue is the urgent demand for low-complexity algorithms, especially when faced with the requirement of real-time implementation. In this paper, to deal with these two problems, we have presented three fast and accurate sparse reconstruction algorithms, termed as HR-DCD, Hlog-DCD and Hlp-DCD, which are based on homotopy, dichotomous coordinate descent (DCD) iterations and non-convex regularizations, by combining with the grid refinement technique. Experimental results are provided to demonstrate the effectiveness of the proposed algorithms and related analysis. PMID:24675758

  20. Carbene footprinting accurately maps binding sites in protein-ligand and protein-protein interactions

    NASA Astrophysics Data System (ADS)

    Manzi, Lucio; Barrow, Andrew S.; Scott, Daniel; Layfield, Robert; Wright, Timothy G.; Moses, John E.; Oldham, Neil J.

    2016-11-01

    Specific interactions between proteins and their binding partners are fundamental to life processes. The ability to detect protein complexes, and map their sites of binding, is crucial to understanding basic biology at the molecular level. Methods that employ sensitive analytical techniques such as mass spectrometry have the potential to provide valuable insights with very little material and on short time scales. Here we present a differential protein footprinting technique employing an efficient photo-activated probe for use with mass spectrometry. Using this methodology the location of a carbohydrate substrate was accurately mapped to the binding cleft of lysozyme, and in a more complex example, the interactions between a 100 kDa, multi-domain deubiquitinating enzyme, USP5 and a diubiquitin substrate were located to different functional domains. The much improved properties of this probe make carbene footprinting a viable method for rapid and accurate identification of protein binding sites utilizing benign, near-UV photoactivation.

  1. 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)

    Casper, Paul W.; Bent, Rodney B.

    1991-01-01

    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.

  2. Smart Location Database - Service

    EPA Pesticide Factsheets

    The Smart Location Database (SLD) summarizes over 80 demographic, built environment, transit service, and destination accessibility attributes for every census block group in the United States. Future updates to the SLD will include additional attributes which summarize the relative location efficiency of a block group when compared to other block groups within the same metropolitan region. EPA also plans to periodically update attributes and add new attributes to reflect latest available data. A log of SLD updates is included in the SLD User Guide. See the user guide for a full description of data sources, data currency, and known limitations: https://edg.epa.gov/data/Public/OP/SLD/SLD_userguide.pdf

  3. Smart Location Database - Download

    EPA Pesticide Factsheets

    The Smart Location Database (SLD) summarizes over 80 demographic, built environment, transit service, and destination accessibility attributes for every census block group in the United States. Future updates to the SLD will include additional attributes which summarize the relative location efficiency of a block group when compared to other block groups within the same metropolitan region. EPA also plans to periodically update attributes and add new attributes to reflect latest available data. A log of SLD updates is included in the SLD User Guide. See the user guide for a full description of data sources, data currency, and known limitations: https://edg.epa.gov/data/Public/OP/SLD/SLD_userguide.pdf

  4. Improved method for retinotopy constrained source estimation of visual evoked responses

    PubMed Central

    Hagler, Donald J.; Dale, Anders M.

    2011-01-01

    Retinotopy constrained source estimation (RCSE) is a method for non-invasively measuring the time courses of activation in early visual areas using magnetoencephalography (MEG) or electroencephalography (EEG). Unlike conventional equivalent current dipole or distributed source models, the use of multiple, retinotopically-mapped stimulus locations to simultaneously constrain the solutions allows for the estimation of independent waveforms for visual areas V1, V2, and V3, despite their close proximity to each other. We describe modifications that improve the reliability and efficiency of this method. First, we find that increasing the number and size of visual stimuli results in source estimates that are less susceptible to noise. Second, to create a more accurate forward solution, we have explicitly modeled the cortical point spread of individual visual stimuli. Dipoles are represented as extended patches on the cortical surface, which take into account the estimated receptive field size at each location in V1, V2, and V3 as well as the contributions from contralateral, ipsilateral, dorsal, and ventral portions of the visual areas. Third, we implemented a map fitting procedure to deform a template to match individual subject retinotopic maps derived from functional magnetic resonance imaging (fMRI). This improves the efficiency of the overall method by allowing automated dipole selection, and it makes the results less sensitive to physiological noise in fMRI retinotopy data. Finally, the iteratively reweighted least squares (IRLS) method was used to reduce the contribution from stimulus locations with high residual error for robust estimation of visual evoked responses. PMID:22102418

  5. Low-cost asset tracking using location-aware camera phones

    NASA Astrophysics Data System (ADS)

    Chen, David; Tsai, Sam; Kim, Kyu-Han; Hsu, Cheng-Hsin; Singh, Jatinder Pal; Girod, Bernd

    2010-08-01

    Maintaining an accurate and up-to-date inventory of one's assets is a labor-intensive, tedious, and costly operation. To ease this difficult but important task, we design and implement a mobile asset tracking system for automatically generating an inventory by snapping photos of the assets with a smartphone. Since smartphones are becoming ubiquitous, construction and deployment of our inventory management solution is simple and costeffective. Automatic asset recognition is achieved by first segmenting individual assets out of the query photo and then performing bag-of-visual-features (BoVF) image matching on the segmented regions. The smartphone's sensor readings, such as digital compass and accelerometer measurements, can be used to determine the location of each asset, and this location information is stored in the inventory for each recognized asset. As a special case study, we demonstrate a mobile book tracking system, where users snap photos of books stacked on bookshelves to generate a location-aware book inventory. It is shown that segmenting the book spines is very important for accurate feature-based image matching into a database of book spines. Segmentation also provides the exact orientation of each book spine, so more discriminative upright local features can be employed for improved recognition. This system's mobile client has been implemented for smartphones running the Symbian or Android operating systems. The client enables a user to snap a picture of a bookshelf and to subsequently view the recognized spines in the smartphone's viewfinder. Two different pose estimates, one from BoVF geometric matching and the other from segmentation boundaries, are both utilized to accurately draw the boundary of each spine in the viewfinder for easy visualization. The BoVF representation also allows matching each photo of a bookshelf rack against a photo of the entire bookshelf, and the resulting feature matches are used in conjunction with the smartphone

  6. Accurately Mapping M31's Microlensing Population

    NASA Astrophysics Data System (ADS)

    Crotts, Arlin

    2004-07-01

    We propose to augment an existing microlensing survey of M31 with source identifications provided by a modest amount of ACS {and WFPC2 parallel} observations to yield an accurate measurement of the masses responsible for microlensing in M31, and presumably much of its dark matter. The main benefit of these data is the determination of the physical {or "einstein"} timescale of each microlensing event, rather than an effective {"FWHM"} timescale, allowing masses to be determined more than twice as accurately as without HST data. The einstein timescale is the ratio of the lensing cross-sectional radius and relative velocities. Velocities are known from kinematics, and the cross-section is directly proportional to the {unknown} lensing mass. We cannot easily measure these quantities without knowing the amplification, hence the baseline magnitude, which requires the resolution of HST to find the source star. This makes a crucial difference because M31 lens m ass determinations can be more accurate than those towards the Magellanic Clouds through our Galaxy's halo {for the same number of microlensing events} due to the better constrained geometry in the M31 microlensing situation. Furthermore, our larger survey, just completed, should yield at least 100 M31 microlensing events, more than any Magellanic survey. A small amount of ACS+WFPC2 imaging will deliver the potential of this large database {about 350 nights}. For the whole survey {and a delta-function mass distribution} the mass error should approach only about 15%, or about 6% error in slope for a power-law distribution. These results will better allow us to pinpoint the lens halo fraction, and the shape of the halo lens spatial distribution, and allow generalization/comparison of the nature of halo dark matter in spiral galaxies. In addition, we will be able to establish the baseline magnitude for about 50, 000 variable stars, as well as measure an unprecedentedly deta iled color-magnitude diagram and luminosity

  7. Improved integrated sniper location system

    NASA Astrophysics Data System (ADS)

    Figler, Burton D.; Spera, Timothy J.

    1999-01-01

    In July of 1995, Lockheed Martin IR Imaging Systems, of Lexington, Massachusetts began the development of an integrated sniper location system for the Defense Advanced Research Projects Agency and for the Department of the Navy's Naval Command Control & Ocean Surveillance Center, RDTE Division in San Diego, California. The I-SLS integrates acoustic and uncooled infrared sensing technologies to provide an affordable and highly effective sniper detection and location capability. This system, its performance and results from field tests at Camp Pendleton, California, in October 1996 were described in a paper presented at the November 1996 SPIE Photonics East Symposium1 on Enabling Technologies for Law Enforcement and Security. The I-SLS combines an acoustic warning system with an uncooled infrared warning system. The acoustic warning system has been developed by SenTech, Inc., of Lexington, Massachusetts. This acoustic warning system provides sniper detection and coarse location information based upon the muzzle blast of the sniper's weapon and/or upon the shock wave produced by the sniper's bullet, if the bullet is supersonic. The uncooled infrared warning system provides sniper detection and fine location information based upon the weapon's muzzle flash. In addition, the uncooled infrared warning system can provide thermal imagery that can be used to accurately locate and identify the sniper. Combining these two technologies improves detection probability, reduces false alarm rate and increases utility. In the two years since the last report of the integrated sniper location system, improvements have been made and a second field demonstration was planned. In this paper, we describe the integrated sniper location system modifications in preparation for the new field demonstration. In addition, fundamental improvements in the uncooled infrared sensor technology continue to be made. These improvements include higher sensitivity (lower minimum resolvable temperature

  8. Identification of 4th intercostal space using sternal notch to xiphoid length for accurate electrocardiogram lead placement.

    PubMed

    Day, Kevin; Oliva, Isabel; Krupinski, Elizabeth; Marcus, Frank

    2015-01-01

    Precordial ECG lead placement is difficult in obese patients with increased chest wall soft tissues due to inaccurate palpation of the intercostal spaces. We investigated whether the length of the sternum (distance between the sternal notch and xiphoid process) can accurately predict the location of the 4th intercostal space, which is the traditional location for V1 lead position. Fifty-five consecutive adult chest computed tomography examinations were reviewed for measurements. The sternal notch to right 4th intercostal space distance was 67% of the sternal notch to xiphoid process length with an overall correlation of r=0.600 (p<0.001). The above measurement may be utilized to locate the 4th intercostal space for accurate placement of the precordial electrodes in adults in whom the 4th intercostal space cannot be found by physical exam. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Location and source characteristics of the 2016 January 6 North Korean nuclear test constrained by InSAR

    NASA Astrophysics Data System (ADS)

    Wei, Meng

    2017-05-01

    The interferometric synthetic aperture radar (InSAR) data from the Japan Aerospace Exploration Agency ALOS-2 satellite show possible deformation associated with the 2016 January 6 North Korean nuclear test whereas the European Space Agency Sentinel-1A data are decorrelated. This is the first time that deformation related to a nuclear test has been measured since 1992. Here, I present two interpretations of the observed deformation: First, the deformation can be explained by a triggered landslide on the western slope of Mt Mantap, with a displacement of up to 10 cm across a patch of 1 km2. Second, the observation may be from uplift created by the nuclear explosion. In the second interpretation, the location, depth and cavity size can be estimated from a topography-corrected homogenous half-space model (Mogi). The preferred location of the 2016 January 6 event is 41.2993°N 129.0715°E, with an uncertainty of 100 m. The estimated depth is 420-700 m and the cavity radius is 23-27 m. Based on empirical data and the assumption of granite as the host rock, the yield is estimated to be 11.6-24.4 kilotons of TNT, which is consistent with previous results based on seismic data. With these two interpretations, I demonstrate that InSAR data provide an independent tool to locate and estimate source characteristics of nuclear tests in North Korea. The ambiguity of interpretation is mainly due to the limited InSAR data acquisition. Future frequent data collection by current and upcoming InSAR satellites will allow full use of InSAR for nuclear monitoring and characterization in North Korea and around the world.

  10. Lunar Impact Flash Locations from NASA's Lunar Impact Monitoring Program

    NASA Technical Reports Server (NTRS)

    Moser, D. E.; Suggs, R. M.; Kupferschmidt, L.; Feldman, J.

    2015-01-01

    dependent upon LRO finding a fresh impact crater associated with one of the impact flashes recorded by Earth-based instruments, either the bright event of March 2013 or any other in the database of impact observations. To find the crater, LRO needed an accurate area to search. This Technical Memorandum (TM) describes the geolocation technique developed to accurately determine the impact flash location, and by association, the location of the crater, thought to lie directly beneath the brightest portion of the flash. The workflow and software tools used to geolocate the impact flashes are described in detail, along with sources of error and uncertainty and a case study applying the workflow to the bright impact flash in March 2013. Following the successful geolocation of the March 2013 flash, the technique was applied to all impact flashes detected by the MEO between November 7, 2005, and January 3, 2014.

  11. Efficient Location of Research Reference Sources in the Field of Dance.

    ERIC Educational Resources Information Center

    Kissinger, Pat; Jay, Danielle

    More than 45 basic dance reference research sources that would be useful to students, scholars, teachers, historians, and therapists are discussed in this bibliographic essay. Aspects of dance covered include choreography, criticism, teaching principles, aesthetic theory, dance therapy, and history. Sources are grouped by type: dictionaries and…

  12. Fast and Accurate Detection of Spread Source in Large Complex Networks

    DTIC Science & Technology

    the patient one in epidemics, or source of rumor spreading in social network. Pinto, Thiran and Vetterli introduced an algorithm (PTVA) to solve the...important case of this problem in which a limited set of nodes act as observers and report times at which the spread reached them. PTVA uses all

  13. Groundwater Pollution Source Identification using Linked ANN-Optimization Model

    NASA Astrophysics Data System (ADS)

    Ayaz, Md; Srivastava, Rajesh; Jain, Ashu

    2014-05-01

    Groundwater is the principal source of drinking water in several parts of the world. Contamination of groundwater has become a serious health and environmental problem today. Human activities including industrial and agricultural activities are generally responsible for this contamination. Identification of groundwater pollution source is a major step in groundwater pollution remediation. Complete knowledge of pollution source in terms of its source characteristics is essential to adopt an effective remediation strategy. Groundwater pollution source is said to be identified completely when the source characteristics - location, strength and release period - are known. Identification of unknown groundwater pollution source is an ill-posed inverse problem. It becomes more difficult for real field conditions, when the lag time between the first reading at observation well and the time at which the source becomes active is not known. We developed a linked ANN-Optimization model for complete identification of an unknown groundwater pollution source. The model comprises two parts- an optimization model and an ANN model. Decision variables of linked ANN-Optimization model contain source location and release period of pollution source. An objective function is formulated using the spatial and temporal data of observed and simulated concentrations, and then minimized to identify the pollution source parameters. In the formulation of the objective function, we require the lag time which is not known. An ANN model with one hidden layer is trained using Levenberg-Marquardt algorithm to find the lag time. Different combinations of source locations and release periods are used as inputs and lag time is obtained as the output. Performance of the proposed model is evaluated for two and three dimensional case with error-free and erroneous data. Erroneous data was generated by adding uniformly distributed random error (error level 0-10%) to the analytically computed concentration

  14. Source apportionment and location by selective wind sampling and Positive Matrix Factorization.

    PubMed

    Venturini, Elisa; Vassura, Ivano; Raffo, Simona; Ferroni, Laura; Bernardi, Elena; Passarini, Fabrizio

    2014-10-01

    In order to determine the pollution sources in a suburban area and identify the main direction of their origin, PM2.5 was collected with samplers coupled with a wind select sensor and then subjected to Positive Matrix Factorization (PMF) analysis. In each sample, soluble ions, organic carbon, elemental carbon, levoglucosan, metals, and Polycyclic Aromatic Hydrocarbons (PAHs) were determined. PMF results identified six main sources affecting the area: natural gas home appliances, motor vehicles, regional transport, biomass combustion, manufacturing activities, and secondary aerosol. The connection of factor temporal trends with other parameters (i.e., temperature, PM2.5 concentration, and photochemical processes) confirms factor attributions. PMF analysis indicated that the main source of PM2.5 in the area is secondary aerosol. This should be mainly due to regional contributions, owing to both the secondary nature of the source itself and the higher concentration registered in inland air masses. The motor vehicle emission source contribution is also important. This source likely has a prevalent local origin. The most toxic determined components, i.e., PAHs, Cd, Pb, and Ni, are mainly due to vehicular traffic. Even if this is not the main source in the study area, it is the one of greatest concern. The application of PMF analysis to PM2.5 collected with this new sampling technique made it possible to obtain more detailed results on the sources affecting the area compared to a classical PMF analysis.

  15. A new wave front shape-based approach for acoustic source localization in an anisotropic plate without knowing its material properties.

    PubMed

    Sen, Novonil; Kundu, Tribikram

    2018-07-01

    Estimating the location of an acoustic source in a structure is an important step towards passive structural health monitoring. Techniques for localizing an acoustic source in isotropic structures are well developed in the literature. Development of similar techniques for anisotropic structures, however, has gained attention only in the recent years and has a scope of further improvement. Most of the existing techniques for anisotropic structures either assume a straight line wave propagation path between the source and an ultrasonic sensor or require the material properties to be known. This study considers different shapes of the wave front generated during an acoustic event and develops a methodology to localize the acoustic source in an anisotropic plate from those wave front shapes. An elliptical wave front shape-based technique was developed first, followed by the development of a parametric curve-based technique for non-elliptical wave front shapes. The source coordinates are obtained by minimizing an objective function. The proposed methodology does not assume a straight line wave propagation path and can predict the source location without any knowledge of the elastic properties of the material. A numerical study presented here illustrates how the proposed methodology can accurately estimate the source coordinates. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Identification of Novel Perfluoroalkyl Ether Carboxylic Acids (PFECAs) and Sulfonic Acids (PFESAs) in Natural Waters Using Accurate Mass Time-of-Flight Mass Spectrometry (TOFMS).

    PubMed

    Strynar, Mark; Dagnino, Sonia; McMahen, Rebecca; Liang, Shuang; Lindstrom, Andrew; Andersen, Erik; McMillan, Larry; Thurman, Michael; Ferrer, Imma; Ball, Carol

    2015-10-06

    Recent scientific scrutiny and concerns over exposure, toxicity, and risk have led to international regulatory efforts resulting in the reduction or elimination of certain perfluorinated compounds from various products and waste streams. Some manufacturers have started producing shorter chain per- and polyfluorinated compounds to try to reduce the potential for bioaccumulation in humans and wildlife. Some of these new compounds contain central ether oxygens or other minor modifications of traditional perfluorinated structures. At present, there has been very limited information published on these "replacement chemistries" in the peer-reviewed literature. In this study we used a time-of-flight mass spectrometry detector (LC-ESI-TOFMS) to identify fluorinated compounds in natural waters collected from locations with historical perfluorinated compound contamination. Our workflow for discovery of chemicals included sequential sampling of surface water for identification of potential sources, nontargeted TOFMS analysis, molecular feature extraction (MFE) of samples, and evaluation of features unique to the sample with source inputs. Specifically, compounds were tentatively identified by (1) accurate mass determination of parent and/or related adducts and fragments from in-source collision-induced dissociation (CID), (2) in-depth evaluation of in-source adducts formed during analysis, and (3) confirmation with authentic standards when available. We observed groups of compounds in homologous series that differed by multiples of CF2 (m/z 49.9968) or CF2O (m/z 65.9917). Compounds in each series were chromatographically separated and had comparable fragments and adducts produced during analysis. We detected 12 novel perfluoroalkyl ether carboxylic and sulfonic acids in surface water in North Carolina, USA using this approach. A key piece of evidence was the discovery of accurate mass in-source n-mer formation (H(+) and Na(+)) differing by m/z 21.9819, corresponding to the

  17. Sound source localization and segregation with internally coupled ears: the treefrog model

    PubMed Central

    Christensen-Dalsgaard, Jakob

    2016-01-01

    Acoustic signaling plays key roles in mediating many of the reproductive and social behaviors of anurans (frogs and toads). Moreover, acoustic signaling often occurs at night, in structurally complex habitats, such as densely vegetated ponds, and in dense breeding choruses characterized by high levels of background noise and acoustic clutter. Fundamental to anuran behavior is the ability of the auditory system to determine accurately the location from where sounds originate in space (sound source localization) and to assign specific sounds in the complex acoustic milieu of a chorus to their correct sources (sound source segregation). Here, we review anatomical, biophysical, neurophysiological, and behavioral studies aimed at identifying how the internally coupled ears of frogs contribute to sound source localization and segregation. Our review focuses on treefrogs in the genus Hyla, as they are the most thoroughly studied frogs in terms of sound source localization and segregation. They also represent promising model systems for future work aimed at understanding better how internally coupled ears contribute to sound source localization and segregation. We conclude our review by enumerating directions for future research on these animals that will require the collaborative efforts of biologists, physicists, and roboticists. PMID:27730384

  18. EEG source localization: Sensor density and head surface coverage.

    PubMed

    Song, Jasmine; Davey, Colin; Poulsen, Catherine; Luu, Phan; Turovets, Sergei; Anderson, Erik; Li, Kai; Tucker, Don

    2015-12-30

    The accuracy of EEG source localization depends on a sufficient sampling of the surface potential field, an accurate conducting volume estimation (head model), and a suitable and well-understood inverse technique. The goal of the present study is to examine the effect of sampling density and coverage on the ability to accurately localize sources, using common linear inverse weight techniques, at different depths. Several inverse methods are examined, using the popular head conductivity. Simulation studies were employed to examine the effect of spatial sampling of the potential field at the head surface, in terms of sensor density and coverage of the inferior and superior head regions. In addition, the effects of sensor density and coverage are investigated in the source localization of epileptiform EEG. Greater sensor density improves source localization accuracy. Moreover, across all sampling density and inverse methods, adding samples on the inferior surface improves the accuracy of source estimates at all depths. More accurate source localization of EEG data can be achieved with high spatial sampling of the head surface electrodes. The most accurate source localization is obtained when the voltage surface is densely sampled over both the superior and inferior surfaces. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  19. Multimodal Spatial Calibration for Accurately Registering EEG Sensor Positions

    PubMed Central

    Chen, Shengyong; Xiao, Gang; Li, Xiaoli

    2014-01-01

    This paper proposes a fast and accurate calibration method to calibrate multiple multimodal sensors using a novel photogrammetry system for fast localization of EEG sensors. The EEG sensors are placed on human head and multimodal sensors are installed around the head to simultaneously obtain all EEG sensor positions. A multiple views' calibration process is implemented to obtain the transformations of multiple views. We first develop an efficient local repair algorithm to improve the depth map, and then a special calibration body is designed. Based on them, accurate and robust calibration results can be achieved. We evaluate the proposed method by corners of a chessboard calibration plate. Experimental results demonstrate that the proposed method can achieve good performance, which can be further applied to EEG source localization applications on human brain. PMID:24803954

  20. The Use of LiDAR Elevation Data and Satellite Imagery to Locate Critical Source Areas to Diffuse Pollution in Agricultural Watersheds

    NASA Astrophysics Data System (ADS)

    Drouin, Ariane; Michaud, Aubert; Thériault, Georges; Beaudin, Isabelle; Rodrigue, Jean-François; Denault, Jean-Thomas; Desjardins, Jacques; Côté, Noémi

    2013-04-01

    In Quebec / Canada, water quality improvement in rural areas greatly depends on the reduction of diffuse pollution. Indeed, point source pollution has been reduced significantly in Canada in recent years by creating circumscribed pits for manure and removing animals from stream. Diffuse pollution differs from point source pollution because it is spread over large areas. In agricultural areas, sediment loss by soil and riverbank erosion along with loss of nutrients (phosphorus, nitrogen, etc.) and pesticides from fields represent the main source of non-point source pollution. The factor mainly responsible for diffuse pollution in agricultural areas is surface runoff occurring in poorly drained areas in fields. The presence of these poorly drained areas is also one of the most limiting factors in crop productivity. Thus, a reconciliation of objectives at the farm (financial concern for farmers) and off-farm concerns (environmental concern) is possible. In short, drainage, runoff, erosion, water quality and crop production are all interconnected issues that need to be tackled together. Two complementary data sources are mainly used in the diagnosis of drainage, surface runoff and erosion : elevation data and multispectral satellite images. In this study of two watersheds located in Québec (Canada), LiDAR elevation data and satellite imagery (QuickBird, Spot and Landsat) were acquired. The studied territories have been partitioned in hydrologic response units (HRUs) according to sub-basins, soils, elevation (topographic index) and land use. These HRUs are afterwards used in a P index software (P-Edit) that calculates the quantities of sediments and phosphorus exported from each HRUs. These exports of sediments and phosphorus are validated with hydrometric and water quality data obtain in two sub-basins and are also compared to soil brightness index derived from multispectral images. This index is sensitive to soil moisture and thus highlights areas where the soil is

  1. Mental Health and Drivers of Need in Emergent and Non-Emergent Emergency Department (ED) Use: Do Living Location and Non-Emergent Care Sources Matter?

    PubMed

    McManus, Moira C; Cramer, Robert J; Boshier, Maureen; Akpinar-Elci, Muge; Van Lunen, Bonnie

    2018-01-13

    Emergency department (ED) utilization has increased due to factors such as admissions for mental health conditions, including suicide and self-harm. We investigate direct and moderating influences on non-emergent ED utilization through the Behavioral Model of Health Services Use. Through logistic regression, we examined correlates of ED use via 2014 New York State Department of Health Statewide Planning and Research Cooperative System outpatient data. Consistent with the primary hypothesis, mental health admissions were associated with emergent use across models, with only a slight decrease in effect size in rural living locations. Concerning moderating effects, Spanish/Hispanic origin was associated with increased likelihood for emergent ED use in the rural living location model, and non-emergent ED use for the no non-emergent source model. 'Other' ethnic origin increased the likelihood of emergent ED use for rural living location and no non-emergent source models. The findings reveal 'need', including mental health admissions, as the largest driver for ED use. This may be due to mental healthcare access, or patients with mental health emergencies being transported via first responders to the ED, as in the case of suicide, self-harm, manic episodes or psychotic episodes. Further educating ED staff on this patient population through gatekeeper training may ensure patients receive the best treatment and aid in driving access to mental healthcare delivery changes.

  2. Locating sources within a dense sensor array using graph clustering

    NASA Astrophysics Data System (ADS)

    Gerstoft, P.; Riahi, N.

    2017-12-01

    We develop a model-free technique to identify weak sources within dense sensor arrays using graph clustering. No knowledge about the propagation medium is needed except that signal strengths decay to insignificant levels within a scale that is shorter than the aperture. We then reinterpret the spatial coherence matrix of a wave field as a matrix whose support is a connectivity matrix of a graph with sensors as vertices. In a dense network, well-separated sources induce clusters in this graph. The geographic spread of these clusters can serve to localize the sources. The support of the covariance matrix is estimated from limited-time data using a hypothesis test with a robust phase-only coherence test statistic combined with a physical distance criterion. The latter criterion ensures graph sparsity and thus prevents clusters from forming by chance. We verify the approach and quantify its reliability on a simulated dataset. The method is then applied to data from a dense 5200 element geophone array that blanketed of the city of Long Beach (CA). The analysis exposes a helicopter traversing the array and oil production facilities.

  3. Considerations in Phase Estimation and Event Location Using Small-aperture Regional Seismic Arrays

    NASA Astrophysics Data System (ADS)

    Gibbons, Steven J.; Kværna, Tormod; Ringdal, Frode

    2010-05-01

    The global monitoring of earthquakes and explosions at decreasing magnitudes necessitates the fully automatic detection, location and classification of an ever increasing number of seismic events. Many seismic stations of the International Monitoring System are small-aperture arrays designed to optimize the detection and measurement of regional phases. Collaboration with operators of mines within regional distances of the ARCES array, together with waveform correlation techniques, has provided an unparalleled opportunity to assess the ability of a small-aperture array to provide robust and accurate direction and slowness estimates for phase arrivals resulting from well-constrained events at sites of repeating seismicity. A significant reason for the inaccuracy of current fully-automatic event location estimates is the use of f- k slowness estimates measured in variable frequency bands. The variability of slowness and azimuth measurements for a given phase from a given source region is reduced by the application of almost any constant frequency band. However, the frequency band resulting in the most stable estimates varies greatly from site to site. Situations are observed in which regional P- arrivals from two sites, far closer than the theoretical resolution of the array, result in highly distinct populations in slowness space. This means that the f- k estimates, even at relatively low frequencies, can be sensitive to source and path-specific characteristics of the wavefield and should be treated with caution when inferring a geographical backazimuth under the assumption of a planar wavefront arriving along the great-circle path. Moreover, different frequency bands are associated with different biases meaning that slowness and azimuth station corrections (commonly denoted SASCs) cannot be calibrated, and should not be used, without reference to the frequency band employed. We demonstrate an example where fully-automatic locations based on a source-region specific

  4. Passive Coherent Detection and Target Location with Multiple Non-Cooperative Transmitters

    DTIC Science & Technology

    2015-06-01

    to detect, separate, classify, locate, and track sources of emissions in multi-target environments—triggered the development of passive radar...radar capitalizes on transmitters of opportunity to detect and locate sources of transmission or targets without deliberate emissions . The...equipment as all necessary hardware is currently available on most naval ships. 3 Bistatic radar geometry. Figure 1. B. HISTORY The concept of

  5. Improving Kinematic Accuracy of Soft Wearable Data Gloves by Optimizing Sensor Locations

    PubMed Central

    Kim, Dong Hyun; Lee, Sang Wook; Park, Hyung-Soon

    2016-01-01

    Bending sensors enable compact, wearable designs when used for measuring hand configurations in data gloves. While existing data gloves can accurately measure angular displacement of the finger and distal thumb joints, accurate measurement of thumb carpometacarpal (CMC) joint movements remains challenging due to crosstalk between the multi-sensor outputs required to measure the degrees of freedom (DOF). To properly measure CMC-joint configurations, sensor locations that minimize sensor crosstalk must be identified. This paper presents a novel approach to identifying optimal sensor locations. Three-dimensional hand surface data from ten subjects was collected in multiple thumb postures with varied CMC-joint flexion and abduction angles. For each posture, scanned CMC-joint contours were used to estimate CMC-joint flexion and abduction angles by varying the positions and orientations of two bending sensors. Optimal sensor locations were estimated by the least squares method, which minimized the difference between the true CMC-joint angles and the joint angle estimates. Finally, the resultant optimal sensor locations were experimentally validated. Placing sensors at the optimal locations, CMC-joint angle measurement accuracies improved (flexion, 2.8° ± 1.9°; abduction, 1.9° ± 1.2°). The proposed method for improving the accuracy of the sensing system can be extended to other types of soft wearable measurement devices. PMID:27240364

  6. Characterizing and sourcing ambient PM2.5 over key emission regions in China III: Carbon isotope based source apportionment of black carbon

    NASA Astrophysics Data System (ADS)

    Yu, Kuangyou; Xing, Zhenyu; Huang, Xiaofeng; Deng, Junjun; Andersson, August; Fang, Wenzheng; Gustafsson, Örjan; Zhou, Jiabin; Du, Ke

    2018-03-01

    Regional haze over China has severe implications for air quality and regional climate. To effectively combat these effects the high uncertainties regarding the emissions from different sources needs to be reduced. In this paper, which is the third in a series on the sources of PM2.5 in pollution hotspot regions of China, we focus on the sources of black carbon aerosols (BC), using carbon isotope signatures. Four-season samples were collected at two key locations: Beijing-Tianjin-Hebei (BTH, part of Northern China plain), and the Pearl River Delta (PRD). We find that that fossil fuel combustion was the predominant source of BC in both BTH and PRD regions, accounting for 75 ± 5%. However, the contributions of what fossil fuel components were dominating differed significantly between BTH and PRD, and varied dramatically with seasons. Coal combustion is overall the all-important BC source in BTH, accounting for 46 ± 12% of the BC in BTH, with the maximum value (62%) found in winter. In contrast for the PRD region, liquid fossil fuel combustion (e.g., oil, diesel, and gasoline) is the dominant source of BC, with an annual mean value of 41 ± 15% and the maximum value of 55% found in winter. Region- and season-specific source apportionments are recommended to both accurately assess the climate impact of carbonaceous aerosol emissions and to effectively mitigate deteriorating air quality caused by carbonaceous aerosols.

  7. Source memory in the rat.

    PubMed

    Crystal, Jonathon D; Alford, Wesley T; Zhou, Wenyi; Hohmann, Andrea G

    2013-03-04

    Source memory is a representation of the origin (source) of information. When source information is bound together, it makes a memory episodic, allowing us to differentiate one event from another. Here, we asked whether rats remember the source of encoded information. Rats foraged for distinctive flavors of food that replenished (or failed to replenish) at its recently encountered location according to a source-information rule. To predict replenishment, rats needed to remember where they had encountered a preferred food type (chocolate) with self-generated (walking along a runway encountering chocolate) or experimenter-generated (placement of the rat at the chocolate site by an experimenter) cues. Three lines of evidence implicate the presence of source memory. First, rats selectively adjusted revisits to the chocolate location based on source information, under conditions in which familiarity of events could not produce successful performance. Second, source memory was dissociated from location memory by different decay rates. Third, temporary inactivation of the CA3 region of the hippocampus with lidocaine selectively eliminated source memory, suggesting that source memory is dependent upon an intact hippocampus. Development of an animal model of source memory may be valuable to probe the biological underpinnings of memory disorders marked by impairments in source memory. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Source memory in the rat

    PubMed Central

    Crystal, Jonathon D.; Alford, Wesley T.; Zhou, Wenyi; Hohmann, Andrea G.

    2013-01-01

    Summary Source memory is a representation of the origin (source) of information. When source information is bound together, it makes a memory episodic, allowing us to differentiate one event from another [1, 2]. Here we asked if rats remember the source of encoded information. Rats foraged for distinctive flavors of food that replenished (or failed to replenish) at its recently encountered location according to a source-information rule. To predict replenishment, rats needed to remember where they had encountered a preferred food type (chocolate) with self-generated (walking along a runway encountering chocolate) or experimenter-generated (placement of the rat at the chocolate site by an experimenter) cues. Three lines of evidence implicate the presence of source memory. First, rats selectively adjusted revisits to the chocolate location based on source information, under conditions in which familiarity of events could not produce successful performance. Second, source memory was dissociated from location memory by different decay rates. Third, temporary inactivation of the CA3 region of the hippocampus with lidocaine selectively eliminated source memory, suggesting that source memory is dependent upon an intact hippocampus. Development of an animal model of source memory may be valuable to probe the biological underpinnings of memory disorders marked by impairments in source memory. PMID:23394830

  9. 16 CFR 500.6 - Net quantity of contents declaration, location.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., location. 500.6 Section 500.6 Commercial Practices FEDERAL TRADE COMMISSION RULES, REGULATIONS, STATEMENT... contents separately and accurately stated on the principal display panel. (b) The declaration of net quantity shall appear as a distinct item on the principal display panel, shall be separated (by at least a...

  10. TRIPPy: Python-based Trailed Source Photometry

    NASA Astrophysics Data System (ADS)

    Fraser, Wesley C.; Alexandersen, Mike; Schwamb, Megan E.; Marsset, Michael E.; Pike, Rosemary E.; Kavelaars, JJ; Bannister, Michele T.; Benecchi, Susan; Delsanti, Audrey

    2016-05-01

    TRIPPy (TRailed Image Photometry in Python) uses a pill-shaped aperture, a rectangle described by three parameters (trail length, angle, and radius) to improve photometry of moving sources over that done with circular apertures. It can generate accurate model and trailed point-spread functions from stationary background sources in sidereally tracked images. Appropriate aperture correction provides accurate, unbiased flux measurement. TRIPPy requires numpy, scipy, matplotlib, Astropy (ascl:1304.002), and stsci.numdisplay; emcee (ascl:1303.002) and SExtractor (ascl:1010.064) are optional.

  11. Probing Motion of Fast Radio Burst Sources by Timing Strongly Lensed Repeaters

    NASA Astrophysics Data System (ADS)

    Dai, Liang; Lu, Wenbin

    2017-09-01

    Given the possible repetitive nature of fast radio bursts (FRBs), their cosmological origin, and their high occurrence, detection of strongly lensed sources due to intervening galaxy lenses is possible with forthcoming radio surveys. We show that if multiple images of a repeating source are resolved with VLBI, using a method independent of lens modeling, accurate timing could reveal non-uniform motion, either physical or apparent, of the emission spot. This can probe the physical nature of FRBs and their surrounding environments, constraining scenarios including orbital motion around a stellar companion if FRBs require a compact star in a special system, and jet-medium interactions for which the location of the emission spot may randomly vary. The high timing precision possible for FRBs (˜ms) compared with the typical time delays between images in galaxy lensing (≳10 days) enables the measurement of tiny fractional changes in the delays (˜ {10}-9) and hence the detection of time-delay variations induced by relative motions between the source, the lens, and the Earth. We show that uniform cosmic peculiar velocities only cause the delay time to drift linearly, and that the effect from the Earth’s orbital motion can be accurately subtracted, thus enabling a search for non-trivial source motion. For a timing accuracy of ˜1 ms and a repetition rate (of detected bursts) of ˜0.05 per day of a single FRB source, non-uniform displacement ≳0.1-1 au of the emission spot perpendicular to the line of sight is detectable if repetitions are seen over a period of hundreds of days.

  12. How accurate is unenhanced multidetector-row CT (MDCT) for localization of renal calculi?

    PubMed

    Goetschi, Stefan; Umbehr, Martin; Ullrich, Stephan; Glenck, Michael; Suter, Stefan; Weishaupt, Dominik

    2012-11-01

    To investigate the correlation between unenhanced MDCT and intraoperative findings with regard to the exact anatomical location of renal calculi. Fifty-nine patients who underwent unenhanced MDCT for suspected urinary stone disease, and who underwent subsequent flexible ureterorenoscopy (URS) as treatment of nephrolithiasis were included in this retrospective study. All MDCT data sets were independently reviewed by three observers with different degrees of experience in reading CT. Each observer was asked to indicate presence and exact anatomical location of any calcification within pyelocaliceal system, renal papilla or renal cortex. Results were compared to intraoperative findings which have been defined as standard of reference. Calculi not described at surgery, but present on MDCT data were counted as renal cortex calcifications. Overall 166 calculi in 59 kidneys have been detected on MDCT, 100 (60.2%) were located in the pyelocaliceal system and 66 (39.8%) in the renal parenchyma. Of the 100 pyelocaliceal calculi, 84 (84%) were correctly located on CT data sets by observer 1, 62 (62%) by observer 2, and 71 (71%) by observer 3. Sensitivity/specificity was 90-94% and 50-100% if only pyelocaliceal calculi measuring >4 mm in size were considered. For pyelocaliceal calculi≤4 mm in size diagnostic performance of MDCT was inferior. Compared to flexible URS, unenhanced MDCT is accurate for distinction between pyelocaliceal calculi and renal parenchyma calcifications if renal calculi are >4 mm in size. For smaller renal calculi, unenhanced MDCT is less accurate and distinction between a pyelocaliceal calculus and renal parenchyma calcification is difficult. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  13. Semantic Location Extraction from Crowdsourced Data

    NASA Astrophysics Data System (ADS)

    Koswatte, S.; Mcdougall, K.; Liu, X.

    2016-06-01

    Crowdsourced Data (CSD) has recently received increased attention in many application areas including disaster management. Convenience of production and use, data currency and abundancy are some of the key reasons for attracting this high interest. Conversely, quality issues like incompleteness, credibility and relevancy prevent the direct use of such data in important applications like disaster management. Moreover, location information availability of CSD is problematic as it remains very low in many crowd sourced platforms such as Twitter. Also, this recorded location is mostly related to the mobile device or user location and often does not represent the event location. In CSD, event location is discussed descriptively in the comments in addition to the recorded location (which is generated by means of mobile device's GPS or mobile communication network). This study attempts to semantically extract the CSD location information with the help of an ontological Gazetteer and other available resources. 2011 Queensland flood tweets and Ushahidi Crowd Map data were semantically analysed to extract the location information with the support of Queensland Gazetteer which is converted to an ontological gazetteer and a global gazetteer. Some preliminary results show that the use of ontologies and semantics can improve the accuracy of place name identification of CSD and the process of location information extraction.

  14. Improvements of the offshore earthquake locations in the Earthquake Early Warning System

    NASA Astrophysics Data System (ADS)

    Chen, Ta-Yi; Hsu, Hsin-Chih

    2017-04-01

    Since 2014 the Earthworm Based Earthquake Alarm Reporting (eBEAR) system has been operated and been used to issue warnings to schools. In 2015 the system started to provide warnings to the public in Taiwan via television and the cell phone. Online performance of the eBEAR system indicated that the average reporting times afforded by the system are approximately 15 and 28 s for inland and offshore earthquakes, respectively. The eBEAR system in average can provide more warning time than the current EEW system (3.2 s and 5.5 s for inland and offshore earthquakes, respectively). However, offshore earthquakes were usually located poorly because only P-wave arrivals were used in the eBEAR system. Additionally, in the early stage of the earthquake early warning system, only fewer stations are available. The poor station coverage may be a reason to answer why offshore earthquakes are difficult to locate accurately. In the Geiger's inversion procedure of earthquake location, we need to put an initial hypocenter and origin time into the location program. For the initial hypocenter, we defined some test locations on the offshore area instead of using the average of locations from triggered stations. We performed 20 programs concurrently running the Geiger's method with different pre-defined initial position to locate earthquakes. We assume that if the program with the pre-defined initial position is close to the true earthquake location, during the iteration procedure of the Geiger's method the processing time of this program should be less than others. The results show that using pre-defined locations for trial-hypocenter in the inversion procedure is able to improve the accurate of offshore earthquakes. Especially for EEW system, in the initial stage of the EEW system, only use 3 or 5 stations to locate earthquakes may lead to bad results because of poor station coverage. In this study, the pre-defined trial-locations provide a feasible way to improve the estimations of

  15. Hiding the Source Based on Limited Flooding for Sensor Networks.

    PubMed

    Chen, Juan; Lin, Zhengkui; Hu, Ying; Wang, Bailing

    2015-11-17

    Wireless sensor networks are widely used to monitor valuable objects such as rare animals or armies. Once an object is detected, the source, i.e., the sensor nearest to the object, generates and periodically sends a packet about the object to the base station. Since attackers can capture the object by localizing the source, many protocols have been proposed to protect source location. Instead of transmitting the packet to the base station directly, typical source location protection protocols first transmit packets randomly for a few hops to a phantom location, and then forward the packets to the base station. The problem with these protocols is that the generated phantom locations are usually not only near the true source but also close to each other. As a result, attackers can easily trace a route back to the source from the phantom locations. To address the above problem, we propose a new protocol for source location protection based on limited flooding, named SLP. Compared with existing protocols, SLP can generate phantom locations that are not only far away from the source, but also widely distributed. It improves source location security significantly with low communication cost. We further propose a protocol, namely SLP-E, to protect source location against more powerful attackers with wider fields of vision. The performance of our SLP and SLP-E are validated by both theoretical analysis and simulation results.

  16. A Map/INS/Wi-Fi Integrated System for Indoor Location-Based Service Applications

    PubMed Central

    Yu, Chunyang; Lan, Haiyu; Gu, Fuqiang; Yu, Fei; El-Sheimy, Naser

    2017-01-01

    In this research, a new Map/INS/Wi-Fi integrated system for indoor location-based service (LBS) applications based on a cascaded Particle/Kalman filter framework structure is proposed. Two-dimension indoor map information, together with measurements from an inertial measurement unit (IMU) and Received Signal Strength Indicator (RSSI) value, are integrated for estimating positioning information. The main challenge of this research is how to make effective use of various measurements that complement each other in order to obtain an accurate, continuous, and low-cost position solution without increasing the computational burden of the system. Therefore, to eliminate the cumulative drift caused by low-cost IMU sensor errors, the ubiquitous Wi-Fi signal and non-holonomic constraints are rationally used to correct the IMU-derived navigation solution through the extended Kalman Filter (EKF). Moreover, the map-aiding method and map-matching method are innovatively combined to constrain the primary Wi-Fi/IMU-derived position through an Auxiliary Value Particle Filter (AVPF). Different sources of information are incorporated through a cascaded structure EKF/AVPF filter algorithm. Indoor tests show that the proposed method can effectively reduce the accumulation of positioning errors of a stand-alone Inertial Navigation System (INS), and provide a stable, continuous and reliable indoor location service. PMID:28574471

  17. A Map/INS/Wi-Fi Integrated System for Indoor Location-Based Service Applications.

    PubMed

    Yu, Chunyang; Lan, Haiyu; Gu, Fuqiang; Yu, Fei; El-Sheimy, Naser

    2017-06-02

    In this research, a new Map/INS/Wi-Fi integrated system for indoor location-based service (LBS) applications based on a cascaded Particle/Kalman filter framework structure is proposed. Two-dimension indoor map information, together with measurements from an inertial measurement unit (IMU) and Received Signal Strength Indicator (RSSI) value, are integrated for estimating positioning information. The main challenge of this research is how to make effective use of various measurements that complement each other in order to obtain an accurate, continuous, and low-cost position solution without increasing the computational burden of the system. Therefore, to eliminate the cumulative drift caused by low-cost IMU sensor errors, the ubiquitous Wi-Fi signal and non-holonomic constraints are rationally used to correct the IMU-derived navigation solution through the extended Kalman Filter (EKF). Moreover, the map-aiding method and map-matching method are innovatively combined to constrain the primary Wi-Fi/IMU-derived position through an Auxiliary Value Particle Filter (AVPF). Different sources of information are incorporated through a cascaded structure EKF/AVPF filter algorithm. Indoor tests show that the proposed method can effectively reduce the accumulation of positioning errors of a stand-alone Inertial Navigation System (INS), and provide a stable, continuous and reliable indoor location service.

  18. Fast 3D elastic micro-seismic source location using new GPU features

    NASA Astrophysics Data System (ADS)

    Xue, Qingfeng; Wang, Yibo; Chang, Xu

    2016-12-01

    In this paper, we describe new GPU features and their applications in passive seismic - micro-seismic location. Locating micro-seismic events is quite important in seismic exploration, especially when searching for unconventional oil and gas resources. Different from the traditional ray-based methods, the wave equation method, such as the method we use in our paper, has a remarkable advantage in adapting to low signal-to-noise ratio conditions and does not need a person to select the data. However, because it has a conspicuous deficiency due to its computation cost, these methods are not widely used in industrial fields. To make the method useful, we implement imaging-like wave equation micro-seismic location in a 3D elastic media and use GPU to accelerate our algorithm. We also introduce some new GPU features into the implementation to solve the data transfer and GPU utilization problems. Numerical and field data experiments show that our method can achieve a more than 30% performance improvement in GPU implementation just by using these new features.

  19. Locating very high energy gamma-ray sources with arcminute accuracy

    NASA Technical Reports Server (NTRS)

    Akerlof, C. W.; Cawley, M. F.; Chantell, M.; Harris, K.; Lawrence, M. A.; Fegan, D. J.; Lang, M. J.; Hillas, A. M.; Jennings, D. G.; Lamb, R. C.

    1991-01-01

    The angular accuracy of gamma-ray detectors is intrinsically limited by the physical processes involved in photon detection. Although a number of pointlike sources were detected by the COS B satellite, only two have been unambiguously identified by time signature with counterparts at longer wavelengths. By taking advantage of the extended longitudinal structure of VHE gamma-ray showers, measurements in the TeV energy range can pinpoint source coordinates to arcminute accuracy. This has now been demonstrated with new data analysis procedures applied to observations of the Crab Nebula using Cherenkov air shower imaging techniques. With two telescopes in coincidence, the individual event circular probable error will be 0.13 deg. The half-cone angle of the field of view is effectively 1 deg.

  20. Locating and decoding barcodes in fuzzy images captured by smart phones

    NASA Astrophysics Data System (ADS)

    Deng, Wupeng; Hu, Jiwei; Liu, Quan; Lou, Ping

    2017-07-01

    With the development of barcodes for commercial use, people's requirements for detecting barcodes by smart phone become increasingly pressing. The low quality of barcode image captured by mobile phone always affects the decoding and recognition rates. This paper focuses on locating and decoding EAN-13 barcodes in fuzzy images. We present a more accurate locating algorithm based on segment length and high fault-tolerant rate algorithm for decoding barcodes. Unlike existing approaches, location algorithm is based on the edge segment length of EAN -13 barcodes, while our decoding algorithm allows the appearance of fuzzy region in barcode image. Experimental results are performed on damaged, contaminated and scratched digital images, and provide a quite promising result for EAN -13 barcode location and decoding.

  1. Mass spectrometry-based protein identification with accurate statistical significance assignment.

    PubMed

    Alves, Gelio; Yu, Yi-Kuo

    2015-03-01

    Assigning statistical significance accurately has become increasingly important as metadata of many types, often assembled in hierarchies, are constructed and combined for further biological analyses. Statistical inaccuracy of metadata at any level may propagate to downstream analyses, undermining the validity of scientific conclusions thus drawn. From the perspective of mass spectrometry-based proteomics, even though accurate statistics for peptide identification can now be achieved, accurate protein level statistics remain challenging. We have constructed a protein ID method that combines peptide evidences of a candidate protein based on a rigorous formula derived earlier; in this formula the database P-value of every peptide is weighted, prior to the final combination, according to the number of proteins it maps to. We have also shown that this protein ID method provides accurate protein level E-value, eliminating the need of using empirical post-processing methods for type-I error control. Using a known protein mixture, we find that this protein ID method, when combined with the Sorić formula, yields accurate values for the proportion of false discoveries. In terms of retrieval efficacy, the results from our method are comparable with other methods tested. The source code, implemented in C++ on a linux system, is available for download at ftp://ftp.ncbi.nlm.nih.gov/pub/qmbp/qmbp_ms/RAId/RAId_Linux_64Bit. Published by Oxford University Press 2014. This work is written by US Government employees and is in the public domain in the US.

  2. Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2004-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  3. Swift Gamma-ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

    NASA Technical Reports Server (NTRS)

    Bundas, David J.

    2005-01-01

    The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UT, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

  4. Optimization of the Number and Location of Tsunami Stations in a Tsunami Warning System

    NASA Astrophysics Data System (ADS)

    An, C.; Liu, P. L. F.; Pritchard, M. E.

    2014-12-01

    Optimizing the number and location of tsunami stations in designing a tsunami warning system is an important and practical problem. It is always desirable to maximize the capability of the data obtained from the stations for constraining the earthquake source parameters, and to minimize the number of stations at the same time. During the 2011 Tohoku tsunami event, 28 coastal gauges and DART buoys in the near-field recorded tsunami waves, providing an opportunity for assessing the effectiveness of those stations in identifying the earthquake source parameters. Assuming a single-plane fault geometry, inversions of tsunami data from combinations of various number (1~28) of stations and locations are conducted and evaluated their effectiveness according to the residues of the inverse method. Results show that the optimized locations of stations depend on the number of stations used. If the stations are optimally located, 2~4 stations are sufficient to constrain the source parameters. Regarding the optimized location, stations must be uniformly spread in all directions, which is not surprising. It is also found that stations within the source region generally give worse constraint of earthquake source than stations farther from source, which is due to the exaggeration of model error in matching large amplitude waves at near-source stations. Quantitative discussions on these findings will be given in the presentation. Applying similar analysis to the Manila Trench based on artificial scenarios of earthquakes and tsunamis, the optimal location of tsunami stations are obtained, which provides guidance of deploying a tsunami warning system in this region.

  5. Determination of the Best Ground Penetrating Radar Source Signal Type for the Accurate Location of Underground Utilities

    DTIC Science & Technology

    1988-09-01

    si2sna- loss was hige tra-e-: td A.R concluded that the- a~oroxim-at _’ns u-sed in heanalytical model may h-ave intrcou,_ce,, scom.e error :nothe...amplitudes f-om the Phase 2 measurements were in general significant1y 104 co cl -\\ Lnf C~’j tD .0n 1 -O21 w -- -L a u4 oCLa - I N -4 - n -7 c -4 > V) r...responses of the same device are uispla~ td . Tie Fr-equiency Domain refie~tion measuremient is a composite iesponise of* all of’ the discontinuities

  6. Global mapping of transposon location.

    PubMed

    Gabriel, Abram; Dapprich, Johannes; Kunkel, Mark; Gresham, David; Pratt, Stephen C; Dunham, Maitreya J

    2006-12-15

    Transposable genetic elements are ubiquitous, yet their presence or absence at any given position within a genome can vary between individual cells, tissues, or strains. Transposable elements have profound impacts on host genomes by altering gene expression, assisting in genomic rearrangements, causing insertional mutations, and serving as sources of phenotypic variation. Characterizing a genome's full complement of transposons requires whole genome sequencing, precluding simple studies of the impact of transposition on interindividual variation. Here, we describe a global mapping approach for identifying transposon locations in any genome, using a combination of transposon-specific DNA extraction and microarray-based comparative hybridization analysis. We use this approach to map the repertoire of endogenous transposons in different laboratory strains of Saccharomyces cerevisiae and demonstrate that transposons are a source of extensive genomic variation. We also apply this method to mapping bacterial transposon insertion sites in a yeast genomic library. This unique whole genome view of transposon location will facilitate our exploration of transposon dynamics, as well as defining bases for individual differences and adaptive potential.

  7. An accurate model for predicting high frequency noise of nanoscale NMOS SOI transistors

    NASA Astrophysics Data System (ADS)

    Shen, Yanfei; Cui, Jie; Mohammadi, Saeed

    2017-05-01

    A nonlinear and scalable model suitable for predicting high frequency noise of N-type Metal Oxide Semiconductor (NMOS) transistors is presented. The model is developed for a commercial 45 nm CMOS SOI technology and its accuracy is validated through comparison with measured performance of a microwave low noise amplifier. The model employs the virtual source nonlinear core and adds parasitic elements to accurately simulate the RF behavior of multi-finger NMOS transistors up to 40 GHz. For the first time, the traditional long-channel thermal noise model is supplemented with an injection noise model to accurately represent the noise behavior of these short-channel transistors up to 26 GHz. The developed model is simple and easy to extract, yet very accurate.

  8. Automated location detection of injection site for preclinical stereotactic neurosurgery procedure

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Shiva; Wu, Hemmings C. H.

    2017-03-01

    Currently, during stereotactic neurosurgery procedures, the manual task of locating the proper area for needle insertion or implantation of electrode/cannula/optic fiber can be time consuming. The requirement of the task is to quickly and accurately find the location for insertion. In this study we investigate an automated method to locate the entry point of region of interest. This method leverages a digital image capture system, pattern recognition, and motorized stages. Template matching of known anatomical identifiable regions is used to find regions of interest (e.g. Bregma) in rodents. For our initial study, we tackle the problem of automatically detecting the entry point.

  9. Sensor Fusion to Infer Locations of Standing and Reaching Within the Home in Incomplete Spinal Cord Injury.

    PubMed

    Lonini, Luca; Reissman, Timothy; Ochoa, Jose M; Mummidisetty, Chaithanya K; Kording, Konrad; Jayaraman, Arun

    2017-10-01

    The objective of rehabilitation after spinal cord injury is to enable successful function in everyday life and independence at home. Clinical tests can assess whether patients are able to execute functional movements but are limited in assessing such information at home. A prototype system is developed that detects stand-to-reach activities, a movement with important functional implications, at multiple locations within a mock kitchen. Ten individuals with incomplete spinal cord injuries performed a sequence of standing and reaching tasks. The system monitored their movements by combining two sources of information: a triaxial accelerometer, placed on the subject's thigh, detected sitting or standing, and a network of radio frequency tags, wirelessly connected to a wrist-worn device, detected reaching at three locations. A threshold-based algorithm detected execution of the combined tasks and accuracy was measured by the number of correctly identified events. The system was shown to have an average accuracy of 98% for inferring when individuals performed stand-to-reach activities at each tag location within the same room. The combination of accelerometry and tags yielded accurate assessments of functional stand-to-reach activities within a home environment. Optimization of this technology could simplify patient compliance and allow clinicians to assess functional home activities.

  10. An accurate discontinuous Galerkin method for solving point-source Eikonal equation in 2-D heterogeneous anisotropic media

    NASA Astrophysics Data System (ADS)

    Le Bouteiller, P.; Benjemaa, M.; Métivier, L.; Virieux, J.

    2018-03-01

    Accurate numerical computation of wave traveltimes in heterogeneous media is of major interest for a large range of applications in seismics, such as phase identification, data windowing, traveltime tomography and seismic imaging. A high level of precision is needed for traveltimes and their derivatives in applications which require quantities such as amplitude or take-off angle. Even more challenging is the anisotropic case, where the general Eikonal equation is a quartic in the derivatives of traveltimes. Despite their efficiency on Cartesian meshes, finite-difference solvers are inappropriate when dealing with unstructured meshes and irregular topographies. Moreover, reaching high orders of accuracy generally requires wide stencils and high additional computational load. To go beyond these limitations, we propose a discontinuous-finite-element-based strategy which has the following advantages: (1) the Hamiltonian formalism is general enough for handling the full anisotropic Eikonal equations; (2) the scheme is suitable for any desired high-order formulation or mixing of orders (p-adaptivity); (3) the solver is explicit whatever Hamiltonian is used (no need to find the roots of the quartic); (4) the use of unstructured meshes provides the flexibility for handling complex boundary geometries such as topographies (h-adaptivity) and radiation boundary conditions for mimicking an infinite medium. The point-source factorization principles are extended to this discontinuous Galerkin formulation. Extensive tests in smooth analytical media demonstrate the high accuracy of the method. Simulations in strongly heterogeneous media illustrate the solver robustness to realistic Earth-sciences-oriented applications.

  11. A Preliminary ZEUS Lightning Location Error Analysis Using a Modified Retrieval Theory

    NASA Technical Reports Server (NTRS)

    Elander, Valjean; Koshak, William; Phanord, Dieudonne

    2004-01-01

    The ZEUS long-range VLF arrival time difference lightning detection network now covers both Europe and Africa, and there are plans for further expansion into the western hemisphere. In order to fully optimize and assess ZEUS lightning location retrieval errors and to determine the best placement of future receivers expected to be added to the network, a software package is being developed jointly between the NASA Marshall Space Flight Center (MSFC) and the University of Nevada Las Vegas (UNLV). The software package, called the ZEUS Error Analysis for Lightning (ZEAL), will be used to obtain global scale lightning location retrieval error maps using both a Monte Carlo approach and chi-squared curvature matrix theory. At the core of ZEAL will be an implementation of an Iterative Oblate (IO) lightning location retrieval method recently developed at MSFC. The IO method will be appropriately modified to account for variable wave propagation speed, and the new retrieval results will be compared with the current ZEUS retrieval algorithm to assess potential improvements. In this preliminary ZEAL work effort, we defined 5000 source locations evenly distributed across the Earth. We then used the existing (as well as potential future ZEUS sites) to simulate arrival time data between source and ZEUS site. A total of 100 sources were considered at each of the 5000 locations, and timing errors were selected from a normal distribution having a mean of 0 seconds and a standard deviation of 20 microseconds. This simulated "noisy" dataset was analyzed using the IO algorithm to estimate source locations. The exact locations were compared with the retrieved locations, and the results are summarized via several color-coded "error maps."

  12. An Impact-Location Estimation Algorithm for Subsonic Uninhabited Aircraft

    NASA Technical Reports Server (NTRS)

    Bauer, Jeffrey E.; Teets, Edward

    1997-01-01

    An impact-location estimation algorithm is being used at the NASA Dryden Flight Research Center to support range safety for uninhabited aerial vehicle flight tests. The algorithm computes an impact location based on the descent rate, mass, and altitude of the vehicle and current wind information. The predicted impact location is continuously displayed on the range safety officer's moving map display so that the flightpath of the vehicle can be routed to avoid ground assets if the flight must be terminated. The algorithm easily adapts to different vehicle termination techniques and has been shown to be accurate to the extent required to support range safety for subsonic uninhabited aerial vehicles. This paper describes how the algorithm functions, how the algorithm is used at NASA Dryden, and how various termination techniques are handled by the algorithm. Other approaches to predicting the impact location and the reasons why they were not selected for real-time implementation are also discussed.

  13. Lunar Pickup Ions Observed by ARTEMIS: Spatial and Temporal Distribution and Constraints on Species and Source Locations

    NASA Technical Reports Server (NTRS)

    Halekas, Jasper S.; Poppe, A. R.; Delory, G. T.; Sarantos, M.; Farrell, W. M.; Angelopoulos, V.; McFadden, J. P.

    2012-01-01

    ARTEMIS observes pickup ions around the Moon, at distances of up to 20,000 km from the surface. The observed ions form a plume with a narrow spatial and angular extent, generally seen in a single energy/angle bin of the ESA instrument. Though ARTEMIS has no mass resolution capability, we can utilize the analytically describable characteristics of pickup ion trajectories to constrain the possible ion masses that can reach the spacecraft at the observation location in the correct energy/angle bin. We find that most of the observations are consistent with a mass range of approx. 20-45 amu, with a smaller fraction consistent with higher masses, and very few consistent with masses below 15 amu. With the assumption that the highest fluxes of pickup ions come from near the surface, the observations favor mass ranges of approx. 20-24 and approx. 36-40 amu. Although many of the observations have properties consistent with a surface or near-surface release of ions, some do not, suggesting that at least some of the observed ions have an exospheric source. Of all the proposed sources for ions and neutrals about the Moon, the pickup ion flux measured by ARTEMIS correlates best with the solar wind proton flux, indicating that sputtering plays a key role in either directly producing ions from the surface, or producing neutrals that subsequently become ionized.

  14. Locating articular cartilage in MR images

    NASA Astrophysics Data System (ADS)

    Folkesson, Jenny; Dam, Erik; Pettersen, Paola; Olsen, Ole F.; Nielsen, Mads; Christiansen, Claus

    2005-04-01

    Accurate computation of the thickness of the articular cartilage is of great importance when diagnosing and monitoring the progress of joint diseases such as osteoarthritis. A fully automated cartilage assessment method is preferable compared to methods using manual interaction in order to avoid inter- and intra-observer variability. As a first step in the cartilage assessment, we present an automatic method for locating articular cartilage in knee MRI using supervised learning. The next step will be to fit a variable shape model to the cartilage, initiated at the location found using the method presented in this paper. From the model, disease markers will be extracted for the quantitative evaluation of the cartilage. The cartilage is located using an ANN-classifier, where every voxel is classified as cartilage or non-cartilage based on prior knowledge of the cartilage structure. The classifier is tested using leave-one-out-evaluation, and we found the average sensitivity and specificity to be 91.0% and 99.4%, respectively. The center of mass calculated from voxels classified as cartilage are similar to the corresponding values calculated from manual segmentations, which confirms that this method can find a good initial position for a shape model.

  15. Identification of Watershed-scale Critical Source Areas Using Bayesian Maximum Entropy Spatiotemporal Analysis

    NASA Astrophysics Data System (ADS)

    Roostaee, M.; Deng, Z.

    2017-12-01

    The states' environmental agencies are required by The Clean Water Act to assess all waterbodies and evaluate potential sources of impairments. Spatial and temporal distributions of water quality parameters are critical in identifying Critical Source Areas (CSAs). However, due to limitations in monetary resources and a large number of waterbodies, available monitoring stations are typically sparse with intermittent periods of data collection. Hence, scarcity of water quality data is a major obstacle in addressing sources of pollution through management strategies. In this study spatiotemporal Bayesian Maximum Entropy method (BME) is employed to model the inherent temporal and spatial variability of measured water quality indicators such as Dissolved Oxygen (DO) concentration for Turkey Creek Watershed. Turkey Creek is located in northern Louisiana and has been listed in 303(d) list for DO impairment since 2014 in Louisiana Water Quality Inventory Reports due to agricultural practices. BME method is proved to provide more accurate estimates than the methods of purely spatial analysis by incorporating space/time distribution and uncertainty in available measured soft and hard data. This model would be used to estimate DO concentration at unmonitored locations and times and subsequently identifying CSAs. The USDA's crop-specific land cover data layers of the watershed were then used to determine those practices/changes that led to low DO concentration in identified CSAs. Primary results revealed that cultivation of corn and soybean as well as urban runoff are main contributing sources in low dissolved oxygen in Turkey Creek Watershed.

  16. pyQms enables universal and accurate quantification of mass spectrometry data.

    PubMed

    Leufken, Johannes; Niehues, Anna; Sarin, L Peter; Wessel, Florian; Hippler, Michael; Leidel, Sebastian A; Fufezan, Christian

    2017-10-01

    Quantitative mass spectrometry (MS) is a key technique in many research areas (1), including proteomics, metabolomics, glycomics, and lipidomics. Because all of the corresponding molecules can be described by chemical formulas, universal quantification tools are highly desirable. Here, we present pyQms, an open-source software for accurate quantification of all types of molecules measurable by MS. pyQms uses isotope pattern matching that offers an accurate quality assessment of all quantifications and the ability to directly incorporate mass spectrometer accuracy. pyQms is, due to its universal design, applicable to every research field, labeling strategy, and acquisition technique. This opens ultimate flexibility for researchers to design experiments employing innovative and hitherto unexplored labeling strategies. Importantly, pyQms performs very well to accurately quantify partially labeled proteomes in large scale and high throughput, the most challenging task for a quantification algorithm. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. Accurate Land Company, Inc., Acadia Subdivision, Plat 1 and Plat 2 - Clean Water Act Public Notice

    EPA Pesticide Factsheets

    The EPA is providing notice of an Administrative Penalty Assessment in the form of an Expedited Storm Water Settlement Agreement against Accurate Land Company, Inc., a business located at 12035 University Ave., Suite 100, Clive, IA 50235, for alleged viola

  18. Integrating smart-phone based momentary location tracking with fixed site air quality monitoring for personal exposure assessment.

    PubMed

    Su, Jason G; Jerrett, Michael; Meng, Ying-Ying; Pickett, Melissa; Ritz, Beate

    2015-02-15

    Epidemiological studies investigating relationships between environmental exposures from air pollution and health typically use residential addresses as a single point for exposure, while environmental exposures in transit, at work, school or other locations are largely ignored. Personal exposure monitors measure individuals' exposures over time; however, current personal monitors are intrusive and cannot be operated at a large scale over an extended period of time (e.g., for a continuous three months) and can be very costly. In addition, spatial locations typically cannot be identified when only personal monitors are used. In this paper, we piloted a study that applied momentary location tracking services supplied by smart phones to identify an individual's location in space-time for three consecutive months (April 28 to July 28, 2013) using available Wi-Fi networks. Individual exposures in space-time to the traffic-related pollutants Nitrogen Oxides (NOX) were estimated by superimposing an annual mean NOX concentration surface modeled using the Land Use Regression (LUR) modeling technique. Individual's exposures were assigned to stationary (including home, work and other stationary locations) and in-transit (including commute and other travel) locations. For the individual, whose home/work addresses were known and the commute route was fixed, it was found that 95.3% of the time, the individual could be accurately identified in space-time. The ambient concentration estimated at the home location was 21.01 ppb. When indoor/outdoor infiltration, indoor sources of air pollution and time spent outdoors were taken into consideration, the individual's cumulative exposures were 28.59 ppb and 96.49 ppb, assuming a respective indoor/outdoor ratio of 1.33 and 5.00. Integrating momentary location tracking services with fixed-site field monitoring, plus indoor-outdoor air exchange calibration, makes exposure assessment of a very large population over an extended time period

  19. Photochemical parameters of atmospheric source gases: accurate determination of OH reaction rate constants over atmospheric temperatures, UV and IR absorption spectra

    NASA Astrophysics Data System (ADS)

    Orkin, V. L.; Khamaganov, V. G.; Martynova, L. E.; Kurylo, M. J.

    2012-12-01

    The emissions of halogenated (Cl, Br containing) organics of both natural and anthropogenic origin contribute to the balance of and changes in the stratospheric ozone concentration. The associated chemical cycles are initiated by the photochemical decomposition of the portion of source gases that reaches the stratosphere. Reactions with hydroxyl radicals and photolysis are the main processes dictating the compound lifetime in the troposphere and release of active halogen in the stratosphere for a majority of halogen source gases. Therefore, the accuracy of photochemical data is of primary importance for the purpose of comprehensive atmospheric modeling and for simplified kinetic estimations of global impacts on the atmosphere, such as in ozone depletion (i.e., the Ozone Depletion Potential, ODP) and climate change (i.e., the Global Warming Potential, GWP). The sources of critically evaluated photochemical data for atmospheric modeling, NASA/JPL Publications and IUPAC Publications, recommend uncertainties within 10%-60% for the majority of OH reaction rate constants with only a few cases where uncertainties lie at the low end of this range. These uncertainties can be somewhat conservative because evaluations are based on the data from various laboratories obtained during the last few decades. Nevertheless, even the authors of the original experimental works rarely estimate the total combined uncertainties of the published OH reaction rate constants to be less than ca. 10%. Thus, uncertainties in the photochemical properties of potential and current atmospheric trace gases obtained under controlled laboratory conditions still may constitute a major source of uncertainty in estimating the compound's environmental impact. One of the purposes of the presentation is to illustrate the potential for obtaining accurate laboratory measurements of the OH reaction rate constant over the temperature range of atmospheric interest. A detailed inventory of accountable sources of

  20. Calibration and operational data for a compact photodiode detector useful for monitoring the location of moving sources of positron emitting radioisotopes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marsland, M. G.; Dehnel, M. P.; Theroux, J.

    2013-04-19

    D-Pace has developed a compact cost-effective gamma detector system based on technology licensed from TRIUMF. These photodiode detectors are convenient for detecting the presence of positron emitting radioisotopes, particularly for the case of transport of radioisotopes from a PET cyclotron to hotlab, or from one location to another in an automated radiochemistry processing unit. This paper describes recent calibration experiments undertaken at the Turku PET Centre for stationary and moving sources of F18 and C11 in standard setups. The practical diagnostic utility of using several of these devices to track the transport of radioisotopes from the cyclotron to hotlab ismore » illustrated. For example, such a detector system provides: a semi-quantitative indication of total activity, speed of transport, location of any activity lost en route and effectiveness of follow-up system flushes, a means of identifying bolus break-up, feedback useful for deciding when to change out tubing.« less

  1. New approach for point pollution source identification in rivers based on the backward probability method.

    PubMed

    Wang, Jiabiao; Zhao, Jianshi; Lei, Xiaohui; Wang, Hao

    2018-06-13

    Pollution risk from the discharge of industrial waste or accidental spills during transportation poses a considerable threat to the security of rivers. The ability to quickly identify the pollution source is extremely important to enable emergency disposal of pollutants. This study proposes a new approach for point source identification of sudden water pollution in rivers, which aims to determine where (source location), when (release time) and how much pollutant (released mass) was introduced into the river. Based on the backward probability method (BPM) and the linear regression model (LR), the proposed LR-BPM converts the ill-posed problem of source identification into an optimization model, which is solved using a Differential Evolution Algorithm (DEA). The decoupled parameters of released mass are not dependent on prior information, which improves the identification efficiency. A hypothetical case study with a different number of pollution sources was conducted to test the proposed approach, and the largest relative errors for identified location, release time, and released mass in all tests were not greater than 10%. Uncertainty in the LR-BPM is mainly due to a problem with model equifinality, but averaging the results of repeated tests greatly reduces errors. Furthermore, increasing the gauging sections further improves identification results. A real-world case study examines the applicability of the LR-BPM in practice, where it is demonstrated to be more accurate and time-saving than two existing approaches, Bayesian-MCMC and basic DEA. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. The Chandra Source Catalog : Automated Source Correlation

    NASA Astrophysics Data System (ADS)

    Hain, Roger; Evans, I. N.; Evans, J. D.; Glotfelty, K. J.; Anderson, C. S.; Bonaventura, N. R.; Chen, J. C.; Davis, J. E.; Doe, S. M.; Fabbiano, G.; Galle, E.; Gibbs, D. G.; Grier, J. D.; Hall, D. M.; Harbo, P. N.; He, X.; Houck, J. C.; Karovska, M.; Lauer, J.; McCollough, M. L.; McDowell, J. C.; Miller, J. B.; Mitschang, A. W.; Morgan, D. L.; Nichols, J. S.; Nowak, M. A.; Plummer, D. A.; Primini, F. A.; Refsdal, B. L.; Rots, A. H.; Siemiginowska, A. L.; Sundheim, B. A.; Tibbetts, M. S.; Van Stone, D. W.; Winkelman, S. L.; Zografou, P.

    2009-01-01

    Chandra Source Catalog (CSC) master source pipeline processing seeks to automatically detect sources and compute their properties. Since Chandra is a pointed mission and not a sky survey, different sky regions are observed for a different number of times at varying orientations, resolutions, and other heterogeneous conditions. While this provides an opportunity to collect data from a potentially large number of observing passes, it also creates challenges in determining the best way to combine different detection results for the most accurate characterization of the detected sources. The CSC master source pipeline correlates data from multiple observations by updating existing cataloged source information with new data from the same sky region as they become available. This process sometimes leads to relatively straightforward conclusions, such as when single sources from two observations are similar in size and position. Other observation results require more logic to combine, such as one observation finding a single, large source and another identifying multiple, smaller sources at the same position. We present examples of different overlapping source detections processed in the current version of the CSC master source pipeline. We explain how they are resolved into entries in the master source database, and examine the challenges of computing source properties for the same source detected multiple times. Future enhancements are also discussed. This work is supported by NASA contract NAS8-03060 (CXC).

  3. Accurate determination of segmented X-ray detector geometry

    PubMed Central

    Yefanov, Oleksandr; Mariani, Valerio; Gati, Cornelius; White, Thomas A.; Chapman, Henry N.; Barty, Anton

    2015-01-01

    Recent advances in X-ray detector technology have resulted in the introduction of segmented detectors composed of many small detector modules tiled together to cover a large detection area. Due to mechanical tolerances and the desire to be able to change the module layout to suit the needs of different experiments, the pixels on each module might not align perfectly on a regular grid. Several detectors are designed to permit detector sub-regions (or modules) to be moved relative to each other for different experiments. Accurate determination of the location of detector elements relative to the beam-sample interaction point is critical for many types of experiment, including X-ray crystallography, coherent diffractive imaging (CDI), small angle X-ray scattering (SAXS) and spectroscopy. For detectors with moveable modules, the relative positions of pixels are no longer fixed, necessitating the development of a simple procedure to calibrate detector geometry after reconfiguration. We describe a simple and robust method for determining the geometry of segmented X-ray detectors using measurements obtained by serial crystallography. By comparing the location of observed Bragg peaks to the spot locations predicted from the crystal indexing procedure, the position, rotation and distance of each module relative to the interaction region can be refined. We show that the refined detector geometry greatly improves the results of experiments. PMID:26561117

  4. Accurate determination of segmented X-ray detector geometry

    DOE PAGES

    Yefanov, Oleksandr; Mariani, Valerio; Gati, Cornelius; ...

    2015-10-22

    Recent advances in X-ray detector technology have resulted in the introduction of segmented detectors composed of many small detector modules tiled together to cover a large detection area. Due to mechanical tolerances and the desire to be able to change the module layout to suit the needs of different experiments, the pixels on each module might not align perfectly on a regular grid. Several detectors are designed to permit detector sub-regions (or modules) to be moved relative to each other for different experiments. Accurate determination of the location of detector elements relative to the beam-sample interaction point is critical formore » many types of experiment, including X-ray crystallography, coherent diffractive imaging (CDI), small angle X-ray scattering (SAXS) and spectroscopy. For detectors with moveable modules, the relative positions of pixels are no longer fixed, necessitating the development of a simple procedure to calibrate detector geometry after reconfiguration. We describe a simple and robust method for determining the geometry of segmented X-ray detectors using measurements obtained by serial crystallography. By comparing the location of observed Bragg peaks to the spot locations predicted from the crystal indexing procedure, the position, rotation and distance of each module relative to the interaction region can be refined. Furthermore, we show that the refined detector geometry greatly improves the results of experiments.« less

  5. Location estimation in wireless sensor networks using spring-relaxation technique.

    PubMed

    Zhang, Qing; Foh, Chuan Heng; Seet, Boon-Chong; Fong, A C M

    2010-01-01

    Accurate and low-cost autonomous self-localization is a critical requirement of various applications of a large-scale distributed wireless sensor network (WSN). Due to its massive deployment of sensors, explicit measurements based on specialized localization hardware such as the Global Positioning System (GPS) is not practical. In this paper, we propose a low-cost WSN localization solution. Our design uses received signal strength indicators for ranging, light weight distributed algorithms based on the spring-relaxation technique for location computation, and the cooperative approach to achieve certain location estimation accuracy with a low number of nodes with known locations. We provide analysis to show the suitability of the spring-relaxation technique for WSN localization with cooperative approach, and perform simulation experiments to illustrate its accuracy in localization.

  6. Providing a USSD location based clinic finder in South Africa: did it work?

    PubMed

    Parsons, Annie Neo; Timler, Dagmar

    2014-01-01

    A new mHealth service, Clinic Finder, was designed to provide a location-based service for any cellphone user in South Africa dialing a dedicated USSD string to find the nearest public primary health care facility. The service was funded by a European Union grant to Cell-Life to support the National Department of Health. Clinic Finder's aims were to provide a reliable and accurate service, and to assess both the most effective means of advertising the service as well as interest in the service. Users dialing the USSD string are asked to agree to geo-location (Vodacom and MTN users) or asked to enter their province, town and street (virtual network users and those choosing not to geo-locate). The service provider, AAT, sends the data to Cell-Life where an SMS with details of the nearest public primary health care facility is sent to the user by Cell-Life's open-source Communicate platform. The service was advertised on 3 days in 2014 using two different means: a newspaper ad on 20 May 2014 and Please Call Me ads on 30 July 2014 and 14 August 2014. 28.2% of unique users on 20 May 2014, 10.5% of unique users on 30 July 2014 and 92.8% of unique users on 14 August 2014 who agreed to geo-location successfully received SMSs. However, only 4.2%, 0.5%, and 2.4% of unique users responding to each advertisement who did not geo-locate then received an SMS. A small survey of users following the 20 May 2014 newspaper ad found overall interest in the idea of Clinic Finder, though unsuccessful users were more likely to dislike the service. The overall experience of using location based services and USSD for Clinic Finder suggests a need in the field of mHealth for wider availability of data on service usability and effectiveness.

  7. Fixed-Wing Micro Aerial Vehicle for Accurate Corridor Mapping

    NASA Astrophysics Data System (ADS)

    Rehak, M.; Skaloud, J.

    2015-08-01

    In this study we present a Micro Aerial Vehicle (MAV) equipped with precise position and attitude sensors that together with a pre-calibrated camera enables accurate corridor mapping. The design of the platform is based on widely available model components to which we integrate an open-source autopilot, customized mass-market camera and navigation sensors. We adapt the concepts of system calibration from larger mapping platforms to MAV and evaluate them practically for their achievable accuracy. We present case studies for accurate mapping without ground control points: first for a block configuration, later for a narrow corridor. We evaluate the mapping accuracy with respect to checkpoints and digital terrain model. We show that while it is possible to achieve pixel (3-5 cm) mapping accuracy in both cases, precise aerial position control is sufficient for block configuration, the precise position and attitude control is required for corridor mapping.

  8. Application of a Persistent Dissolved-phase Reactive Treatment Zone for Mitigation of Mass Discharge from Sources Located in Lower-Permeability Sediments

    PubMed Central

    Marble, J.C.; Brusseau, M.L.; Carroll, K.C.; Plaschke, M.; Fuhrig, L.; Brinker, F.

    2015-01-01

    The purpose of this study is to examine the development and effectiveness of a persistent dissolved-phase treatment zone, created by injecting potassium permanganate solution, for mitigating discharge of contaminant from a source zone located in a relatively deep, low-permeability formation. A localized 1,1-dichloroethene (DCE) source zone comprising dissolved- and sorbed-phase mass is present in lower permeability strata adjacent to a sand/gravel unit in a section of the Tucson International Airport Area (TIAA) Superfund Site. The results of bench-scale studies conducted using core material collected from boreholes drilled at the site indicated that natural oxidant demand was low, which would promote permanganate persistence. The reactive zone was created by injecting a permanganate solution into multiple wells screened across the interface between the lower-permeability and higher-permeability units. The site has been monitored for nine years to characterize the spatial distribution of DCE and permanganate. Permanganate continues to persist at the site, and a substantial and sustained decrease in DCE concentrations in groundwater has occurred after the permanganate injection.. These results demonstrate successful creation of a long-term, dissolved-phase reactive-treatment zone that reduced mass discharge from the source. This project illustrates the application of in-situ chemical oxidation as a persistent dissolved-phase reactive-treatment system for lower-permeability source zones, which appears to effectively mitigate persistent mass discharge into groundwater. PMID:26300570

  9. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, Bahram A.; Maestre, Marcos F.; Fish, Richard H.; Johnston, William E.

    1997-01-01

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations add reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage.

  10. Method and apparatus for accurately manipulating an object during microelectrophoresis

    DOEpatents

    Parvin, B.A.; Maestre, M.F.; Fish, R.H.; Johnston, W.E.

    1997-09-23

    An apparatus using electrophoresis provides accurate manipulation of an object on a microscope stage for further manipulations and reactions. The present invention also provides an inexpensive and easily accessible means to move an object without damage to the object. A plurality of electrodes are coupled to the stage in an array whereby the electrode array allows for distinct manipulations of the electric field for accurate manipulations of the object. There is an electrode array control coupled to the plurality of electrodes for manipulating the electric field. In an alternative embodiment, a chamber is provided on the stage to hold the object. The plurality of electrodes are positioned in the chamber, and the chamber is filled with fluid. The system can be automated using visual servoing, which manipulates the control parameters, i.e., x, y stage, applying the field, etc., after extracting the significant features directly from image data. Visual servoing includes an imaging device and computer system to determine the location of the object. A second stage having a plurality of tubes positioned on top of the second stage, can be accurately positioned by visual servoing so that one end of one of the plurality of tubes surrounds at least part of the object on the first stage. 11 figs.

  11. Rapidly locating and characterizing pollutant releases in buildings.

    PubMed

    Sohn, Michael D; Reynolds, Pamela; Singh, Navtej; Gadgil, Ashok J

    2002-12-01

    Releases of airborne contaminants in or near a building can lead to significant human exposures unless prompt response measures are taken. However, possible responses can include conflicting strategies, such as shutting the ventilation system off versus running it in a purge mode or having occupants evacuate versus sheltering in place. The proper choice depends in part on knowing the source locations, the amounts released, and the likely future dispersion routes of the pollutants. We present an approach that estimates this information in real time. It applies Bayesian statistics to interpret measurements of airborne pollutant concentrations from multiple sensors placed in the building and computes best estimates and uncertainties of the release conditions. The algorithm is fast, capable of continuously updating the estimates as measurements stream in from sensors. We demonstrate the approach using a hypothetical pollutant release in a five-room building. Unknowns to the interpretation algorithm include location, duration, and strength of the source, and some building and weather conditions. Two sensor sampling plans and three levels of data quality are examined. Data interpretation in all examples is rapid; however, locating and characterizing the source with high probability depends on the amount and quality of data and the sampling plan.

  12. Active Electro-Location of Objects in the Underwater Environment Based on the Mixed Polarization Multiple Signal Classification Algorithm

    PubMed Central

    Guo, Lili; Qi, Junwei; Xue, Wei

    2018-01-01

    This article proposes a novel active localization method based on the mixed polarization multiple signal classification (MP-MUSIC) algorithm for positioning a metal target or an insulator target in the underwater environment by using a uniform circular antenna (UCA). The boundary element method (BEM) is introduced to analyze the boundary of the target by use of a matrix equation. In this method, an electric dipole source as a part of the locating system is set perpendicularly to the plane of the UCA. As a result, the UCA can only receive the induction field of the target. The potential of each electrode of the UCA is used as spatial-temporal localization data, and it does not need to obtain the field component in each direction compared with the conventional fields-based localization method, which can be easily implemented in practical engineering applications. A simulation model and a physical experiment are constructed. The simulation and the experiment results provide accurate positioning performance, with the help of verifying the effectiveness of the proposed localization method in underwater target locating. PMID:29439495

  13. Accurate quantification of magnetic particle properties by intra-pair magnetophoresis for nanobiotechnology

    NASA Astrophysics Data System (ADS)

    van Reenen, Alexander; Gao, Yang; Bos, Arjen H.; de Jong, Arthur M.; Hulsen, Martien A.; den Toonder, Jaap M. J.; Prins, Menno W. J.

    2013-07-01

    The application of magnetic particles in biomedical research and in-vitro diagnostics requires accurate characterization of their magnetic properties, with single-particle resolution and good statistics. Here, we report intra-pair magnetophoresis as a method to accurately quantify the field-dependent magnetic moments of magnetic particles and to rapidly generate histograms of the magnetic moments with good statistics. We demonstrate our method with particles of different sizes and from different sources, with a measurement precision of a few percent. We expect that intra-pair magnetophoresis will be a powerful tool for the characterization and improvement of particles for the upcoming field of particle-based nanobiotechnology.

  14. Time reversal optical tomography locates fluorescent targets in a turbid medium

    NASA Astrophysics Data System (ADS)

    Wu, Binlin; Cai, W.; Gayen, S. K.

    2013-03-01

    A fluorescence optical tomography approach that extends time reversal optical tomography (TROT) to locate fluorescent targets embedded in a turbid medium is introduced. It uses a multi-source illumination and multi-detector signal acquisition scheme, along with TR matrix formalism, and multiple signal classification (MUSIC) to construct pseudo-image of the targets. The samples consisted of a single or two small tubes filled with water solution of Indocyanine Green (ICG) dye as targets embedded in a 250 mm × 250 mm × 60 mm rectangular cell filled with Intralipid-20% suspension as the scattering medium. The ICG concentration was 1μM, and the Intralipid-20% concentration was adjusted to provide ~ 1-mm transport length for both excitation wavelength of 790 nm and fluorescence wavelength around 825 nm. The data matrix was constructed using the diffusely transmitted fluorescence signals for all scan positions, and the TR matrix was constructed by multiplying data matrix with its transpose. A pseudo spectrum was calculated using the signal subspace of the TR matrix. Tomographic images were generated using the pseudo spectrum. The peaks in the pseudo images provided locations of the target(s) with sub-millimeter accuracy. Concurrent transmission TROT measurements corroborated fluorescence-TROT findings. The results demonstrate that TROT is a fast approach that can be used to obtain accurate three-dimensional position information of fluorescence targets embedded deep inside a highly scattering medium, such as, a contrast-enhanced tumor in a human breast.

  15. Test to Extract Soil Properties Using the Seismic HammerTM Active Seismic Source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Rebekah F.; Abbott, Robert E.

    Geologic material properties are necessary parameters for ground motion modeling and are difficult and expensive to obtain via traditional methods. Alternative methods to estimate soil properties require a measurement of the ground's response to a force. A possible method of obtaining these measurements is active-source seismic surveys, but measurements of the ground response at the source must also be available. The potential of seismic sources to obtain soil properties is limited, however, by the repeatability of the source. Explosives, and hammer surveys are not repeatable because of variable ground coupling or swing strength. On the other hand, the Seismic Hammermore » TM (SH) is consistent in the amount of energy it inputs into the ground. In addition, it leaves large physical depressions as a result of ground compaction. The volume of ground compaction varies by location. Here, we hypothesize that physical depressions left in the earth by the SH correlate to energy recorded by nearby geophones, and therefore are a measurement of soil physical properties. Using measurements of the volume of shot holes, we compare the spatial distribution of the volume of ground compacted between the different shot locations. We then examine energy recorded by the nearest 50 geophones and compare the change in amplitude across hits at the same location. Finally, we use the percent difference between the energy recorded by the first and later hits at a location to test for a correlation to the volume of the shot depressions. We find that: * Ground compaction at the shot-depression does cluster geographically, but does not correlate to known surface features. * Energy recorded by nearby geophones reflects ground refusal after several hits. * There is no correlation to shot volume and changes in energy at particular shot locations. Deeper material properties (i.e. below the depth of surface compaction) may be contributing to the changes in energy propagation. * Without further

  16. PM₁₀ and PM₂.₅ sources at an insular location in the western Mediterranean by using source apportionment techniques.

    PubMed

    Pey, Jorge; Alastuey, Andrés; Querol, Xavier

    2013-07-01

    PM₁₀ and PM₂.₅ chemical composition has been determined at a suburban insular site in the Balearic Islands (Spain) during almost one and a half year. As a result, 200 samples with more than 50 chemical parameters analyzed have been obtained. The whole database has been analyzed by two receptor modelling techniques (Principal Component Analysis and Positive Matrix Factorisation) in order to identify the main PM sources. After that, regression analyses with respect to the PM mass concentrations were conducted to quantify the daily contributions of each source. Four common sources were identified by both receptor models: secondary nitrate coupled with vehicular emissions, secondary sulphate influenced by fuel-oil combustion, aged marine aerosols and mineral dust. In addition, PCA isolated harbour emissions and a mixed anthropogenic factor containing industrial emissions; whereas PMF isolated an additional mineral factor interpreted as road dust+harbour emissions, and a vehicular abrasion products factor. The use of both methodologies appeared complementary. Nevertheless, PMF sources by themselves were better differentiated. Besides these receptor models, a specific methodology to quantify African dust was also applied. The combination of these three source apportionment tools allowed the identification of 8 sources, being 4 of them mineral (African, regional, urban and harbour dusts). As a summary, 29% of PM₁₀ was attributed to natural sources (African dust, regional dust and sea spray), whereas the proportion diminished to 11% in PM₂.₅. Furthermore, the secondary sulphate source, which accounted for about 22 and 32% of PM₁₀ and PM₂.₅, is strongly linked to the aged polluted air masses residing over the western Mediterranean in the warm period. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. FECAL POLLUTION, PUBLIC HEALTH AND MICROBIAL SOURCE TRACKING

    EPA Science Inventory

    Microbial source tracking (MST) seeks to provide information about sources of fecal water contamination. Without knowledge of sources, it is difficult to accurately model risk assessments, choose effective remediation strategies, or bring chronically polluted waters into complian...

  18. Implosion Source Development and Diego Garcia Reflections

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Harben, P E; Boro, C

    2001-06-01

    Calibration of hydroacoustic stations for nuclear explosion monitoring is important for increasing monitoring capability and confidence from newly installed stations and from existing stations. Past work at Ascension Island has shown that ship-towed airguns can be effectively used for local calibrations such as sensor location, amplitude and phase response, and T-phase coupling in the case of T-phase stations. At regional and ocean-basin distances from a station, the calibration focus is on acoustic travel time, transmission loss, bathymetric shadowing, diffraction, and reflection as recorded at a particular station. Such station calibrations will lead to an overall network calibration that seeks tomore » maximize detection, location, and discrimination capability of events with acoustic signatures. Active-source calibration of hydroacoustic stations at regional and ocean-basin scales has not been attempted to date, but we have made significant headway addressing how such calibrations could be accomplished. We have developed an imploding sphere source that can be used instead of explosives on research and commercial vessels without restriction. The imploding sphere has been modeled using the Lawrence Livermore National Laboratory hydrodynamic code CALE and shown to agree with field data. The need for boosted energy in the monitoring band (2-100 Hz) has led us to develop a 5-sphere implosion device that was tested in the Pacific Ocean earlier this year. Boosting the energy in the monitoring band can be accomplished by a combination of increasing the implosion volume (i.e. the 5-sphere device) and imploding at shallower depths. Although active source calibrations will be necessary at particular locations and for particular objectives, the newly installed Diego Garcia station in the Indian Ocean has shown that earthquakes can be used to help understand regional blockages and the locations responsible for observed hydroacoustic reflections. We have analyzed several

  19. Controlled-source seismic interferometry with one way wave fields

    NASA Astrophysics Data System (ADS)

    van der Neut, J.; Wapenaar, K.; Thorbecke, J. W.

    2008-12-01

    In Seismic Interferometry we generally cross-correlate registrations at two receiver locations and sum over an array of sources to retrieve a Green's function as if one of the receiver locations hosts a (virtual) source and the other receiver location hosts an actual receiver. One application of this concept is to redatum an area of surface sources to a downhole receiver location, without requiring information about the medium between the sources and receivers, thus providing an effective tool for imaging below complex overburden, which is also known as the Virtual Source method. We demonstrate how elastic wavefield decomposition can be effectively combined with controlled-source Seismic Interferometry to generate virtual sources in a downhole receiver array that radiate only down- or upgoing P- or S-waves with receivers sensing only down- or upgoing P- or S- waves. For this purpose we derive exact Green's matrix representations from a reciprocity theorem for decomposed wavefields. Required is the deployment of multi-component sources at the surface and multi- component receivers in a horizontal borehole. The theory is supported with a synthetic elastic model, where redatumed traces are compared with those of a directly modeled reflection response, generated by placing active sources at the virtual source locations and applying elastic wavefield decomposition on both source and receiver side.

  20. Source localization of temporal lobe epilepsy using PCA-LORETA analysis on ictal EEG recordings.

    PubMed

    Stern, Yaki; Neufeld, Miriam Y; Kipervasser, Svetlana; Zilberstein, Amir; Fried, Itzhak; Teicher, Mina; Adi-Japha, Esther

    2009-04-01

    Localizing the source of an epileptic seizure using noninvasive EEG suffers from inaccuracies produced by other generators not related to the epileptic source. The authors isolated the ictal epileptic activity, and applied a source localization algorithm to identify its estimated location. Ten ictal EEG scalp recordings from five different patients were analyzed. The patients were known to have temporal lobe epilepsy with a single epileptic focus that had a concordant MRI lesion. The patients had become seizure-free following partial temporal lobectomy. A midinterval (approximately 5 seconds) period of ictal activity was used for Principal Component Analysis starting at ictal onset. The level of epileptic activity at each electrode (i.e., the eigenvector of the component that manifest epileptic characteristic), was used as an input for low-resolution tomography analysis for EEG inverse solution (Zilberstain et al., 2004). The algorithm accurately and robustly identified the epileptic focus in these patients. Principal component analysis and source localization methods can be used in the future to monitor the progression of an epileptic seizure and its expansion to other areas.

  1. Newspaper archives + text mining = rich sources of historical geo-spatial data

    NASA Astrophysics Data System (ADS)

    Yzaguirre, A.; Smit, M.; Warren, R.

    2016-04-01

    Newspaper archives are rich sources of cultural, social, and historical information. These archives, even when digitized, are typically unstructured and organized by date rather than by subject or location, and require substantial manual effort to analyze. The effort of journalists to be accurate and precise means that there is often rich geo-spatial data embedded in the text, alongside text describing events that editors considered to be of sufficient importance to the region or the world to merit column inches. A regional newspaper can add over 100,000 articles to its database each year, and extracting information from this data for even a single country would pose a substantial Big Data challenge. In this paper, we describe a pilot study on the construction of a database of historical flood events (location(s), date, cause, magnitude) to be used in flood assessment projects, for example to calibrate models, estimate frequency, establish high water marks, or plan for future events in contexts ranging from urban planning to climate change adaptation. We then present a vision for extracting and using the rich geospatial data available in unstructured text archives, and suggest future avenues of research.

  2. Big6 Stage 3 - Location and Access Treasure Hunting

    ERIC Educational Resources Information Center

    Darrow, Rob

    2005-01-01

    Locating sources and accessing the information they contain is part of the Big6 approach to information problem solving. In this stage of knowing where to look and how to find the required source, library media specialists train students in the use of the card catalog in the library media center.

  3. Location error uncertainties - an advanced using of probabilistic inverse theory

    NASA Astrophysics Data System (ADS)

    Debski, Wojciech

    2016-04-01

    The spatial location of sources of seismic waves is one of the first tasks when transient waves from natural (uncontrolled) sources are analyzed in many branches of physics, including seismology, oceanology, to name a few. Source activity and its spatial variability in time, the geometry of recording network, the complexity and heterogeneity of wave velocity distribution are all factors influencing the performance of location algorithms and accuracy of the achieved results. While estimating of the earthquake foci location is relatively simple a quantitative estimation of the location accuracy is really a challenging task even if the probabilistic inverse method is used because it requires knowledge of statistics of observational, modelling, and apriori uncertainties. In this presentation we addressed this task when statistics of observational and/or modeling errors are unknown. This common situation requires introduction of apriori constraints on the likelihood (misfit) function which significantly influence the estimated errors. Based on the results of an analysis of 120 seismic events from the Rudna copper mine operating in southwestern Poland we illustrate an approach based on an analysis of Shanon's entropy calculated for the aposteriori distribution. We show that this meta-characteristic of the aposteriori distribution carries some information on uncertainties of the solution found.

  4. Locating Supplemental Sources of Revenue to Finance Universities in Nigeria.

    ERIC Educational Resources Information Center

    Ogunla, Akin L.

    1989-01-01

    Identifies possible sources of supplemental income to finance Nigerian universities, including households and commercial and industrial firms. A consumption tax imposed on certain goods and services would generate needed funds. Also, because firms employ university graduates to earn higher profits, their turnover income should be taxed to support…

  5. 46 CFR 108.171 - Class I, Division 1 locations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... locations. The following are Class I, Division 1 locations: (a) An enclosed space that contains any part of the mud circulating system that has an opening into the space and is between the well and final... possible source of gas release. (c) An enclosed space that is on the drill floor, and is not separated by a...

  6. 46 CFR 108.171 - Class I, Division 1 locations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... locations. The following are Class I, Division 1 locations: (a) An enclosed space that contains any part of the mud circulating system that has an opening into the space and is between the well and final... possible source of gas release. (c) An enclosed space that is on the drill floor, and is not separated by a...

  7. 46 CFR 108.171 - Class I, Division 1 locations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... locations. The following are Class I, Division 1 locations: (a) An enclosed space that contains any part of the mud circulating system that has an opening into the space and is between the well and final... possible source of gas release. (c) An enclosed space that is on the drill floor, and is not separated by a...

  8. 46 CFR 108.171 - Class I, Division 1 locations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... locations. The following are Class I, Division 1 locations: (a) An enclosed space that contains any part of the mud circulating system that has an opening into the space and is between the well and final... possible source of gas release. (c) An enclosed space that is on the drill floor, and is not separated by a...

  9. 46 CFR 108.171 - Class I, Division 1 locations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... locations. The following are Class I, Division 1 locations: (a) An enclosed space that contains any part of the mud circulating system that has an opening into the space and is between the well and final... possible source of gas release. (c) An enclosed space that is on the drill floor, and is not separated by a...

  10. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    NASA Technical Reports Server (NTRS)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  11. Measuring and monitoring KIPT Neutron Source Facility Reactivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cao, Yan; Gohar, Yousry; Zhong, Zhaopeng

    2015-08-01

    Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on developing and constructing a neutron source facility at Kharkov, Ukraine. The facility consists of an accelerator-driven subcritical system. The accelerator has a 100 kW electron beam using 100 MeV electrons. The subcritical assembly has k eff less than 0.98. To ensure the safe operation of this neutron source facility, the reactivity of the subcritical core has to be accurately determined and continuously monitored. A technique which combines the area-ratio method and the flux-to-current ratio method is purposed to determine themore » reactivity of the KIPT subcritical assembly at various conditions. In particular, the area-ratio method can determine the absolute reactivity of the subcritical assembly in units of dollars by performing pulsed-neutron experiments. It provides reference reactivities for the flux-to-current ratio method to track and monitor the reactivity deviations from the reference state while the facility is at other operation modes. Monte Carlo simulations are performed to simulate both methods using the numerical model of the KIPT subcritical assembly. It is found that the reactivities obtained from both the area-ratio method and the flux-to-current ratio method are spatially dependent on the neutron detector locations and types. Numerical simulations also suggest optimal neutron detector locations to minimize the spatial effects in the flux-to-current ratio method. The spatial correction factors are calculated using Monte Carlo methods for both measuring methods at the selected neutron detector locations. Monte Carlo simulations are also performed to verify the accuracy of the flux-to-current ratio method in monitoring the reactivity swing during a fuel burnup cycle.« less

  12. Achieve Location Privacy-Preserving Range Query in Vehicular Sensing

    PubMed Central

    Lu, Rongxing; Ma, Maode; Bao, Haiyong

    2017-01-01

    Modern vehicles are equipped with a plethora of on-board sensors and large on-board storage, which enables them to gather and store various local-relevant data. However, the wide application of vehicular sensing has its own challenges, among which location-privacy preservation and data query accuracy are two critical problems. In this paper, we propose a novel range query scheme, which helps the data requester to accurately retrieve the sensed data from the distributive on-board storage in vehicular ad hoc networks (VANETs) with location privacy preservation. The proposed scheme exploits structured scalars to denote the locations of data requesters and vehicles, and achieves the privacy-preserving location matching with the homomorphic Paillier cryptosystem technique. Detailed security analysis shows that the proposed range query scheme can successfully preserve the location privacy of the involved data requesters and vehicles, and protect the confidentiality of the sensed data. In addition, performance evaluations are conducted to show the efficiency of the proposed scheme, in terms of computation delay and communication overhead. Specifically, the computation delay and communication overhead are not dependent on the length of the scalar, and they are only proportional to the number of vehicles. PMID:28786943

  13. Achieve Location Privacy-Preserving Range Query in Vehicular Sensing.

    PubMed

    Kong, Qinglei; Lu, Rongxing; Ma, Maode; Bao, Haiyong

    2017-08-08

    Modern vehicles are equipped with a plethora of on-board sensors and large on-board storage, which enables them to gather and store various local-relevant data. However, the wide application of vehicular sensing has its own challenges, among which location-privacy preservation and data query accuracy are two critical problems. In this paper, we propose a novel range query scheme, which helps the data requester to accurately retrieve the sensed data from the distributive on-board storage in vehicular ad hoc networks (VANETs) with location privacy preservation. The proposed scheme exploits structured scalars to denote the locations of data requesters and vehicles, and achieves the privacy-preserving location matching with the homomorphic Paillier cryptosystem technique. Detailed security analysis shows that the proposed range query scheme can successfully preserve the location privacy of the involved data requesters and vehicles, and protect the confidentiality of the sensed data. In addition, performance evaluations are conducted to show the efficiency of the proposed scheme, in terms of computation delay and communication overhead. Specifically, the computation delay and communication overhead are not dependent on the length of the scalar, and they are only proportional to the number of vehicles.

  14. Line-Constrained Camera Location Estimation in Multi-Image Stereomatching.

    PubMed

    Donné, Simon; Goossens, Bart; Philips, Wilfried

    2017-08-23

    Stereomatching is an effective way of acquiring dense depth information from a scene when active measurements are not possible. So-called lightfield methods take a snapshot from many camera locations along a defined trajectory (usually uniformly linear or on a regular grid-we will assume a linear trajectory) and use this information to compute accurate depth estimates. However, they require the locations for each of the snapshots to be known: the disparity of an object between images is related to both the distance of the camera to the object and the distance between the camera positions for both images. Existing solutions use sparse feature matching for camera location estimation. In this paper, we propose a novel method that uses dense correspondences to do the same, leveraging an existing depth estimation framework to also yield the camera locations along the line. We illustrate the effectiveness of the proposed technique for camera location estimation both visually for the rectification of epipolar plane images and quantitatively with its effect on the resulting depth estimation. Our proposed approach yields a valid alternative for sparse techniques, while still being executed in a reasonable time on a graphics card due to its highly parallelizable nature.

  15. Calibration Techniques for Accurate Measurements by Underwater Camera Systems

    PubMed Central

    Shortis, Mark

    2015-01-01

    Calibration of a camera system is essential to ensure that image measurements result in accurate estimates of locations and dimensions within the object space. In the underwater environment, the calibration must implicitly or explicitly model and compensate for the refractive effects of waterproof housings and the water medium. This paper reviews the different approaches to the calibration of underwater camera systems in theoretical and practical terms. The accuracy, reliability, validation and stability of underwater camera system calibration are also discussed. Samples of results from published reports are provided to demonstrate the range of possible accuracies for the measurements produced by underwater camera systems. PMID:26690172

  16. The 2012 Emilia seismic sequence (Northern Italy): Imaging the thrust fault system by accurate aftershock location

    NASA Astrophysics Data System (ADS)

    Govoni, Aladino; Marchetti, Alessandro; De Gori, Pasquale; Di Bona, Massimo; Lucente, Francesco Pio; Improta, Luigi; Chiarabba, Claudio; Nardi, Anna; Margheriti, Lucia; Agostinetti, Nicola Piana; Di Giovambattista, Rita; Latorre, Diana; Anselmi, Mario; Ciaccio, Maria Grazia; Moretti, Milena; Castellano, Corrado; Piccinini, Davide

    2014-05-01

    Starting from late May 2012, the Emilia region (Northern Italy) was severely shaken by an intense seismic sequence, originated from a ML 5.9 earthquake on May 20th, at a hypocentral depth of 6.3 km, with thrust-type focal mechanism. In the following days, the seismic rate remained high, counting 50 ML ≥ 2.0 earthquakes a day, on average. Seismicity spreads along a 30 km east-west elongated area, in the Po river alluvial plain, in the nearby of the cities Ferrara and Modena. Nine days after the first shock, another destructive thrust-type earthquake (ML 5.8) hit the area to the west, causing further damage and fatalities. Aftershocks following this second destructive event extended along the same east-westerly trend for further 20 km to the west, thus illuminating an area of about 50 km in length, on the whole. After the first shock struck, on May 20th, a dense network of temporary seismic stations, in addition to the permanent ones, was deployed in the meizoseismal area, leading to a sensible improvement of the earthquake monitoring capability there. A combined dataset, including three-component seismic waveforms recorded by both permanent and temporary stations, has been analyzed in order to obtain an appropriate 1-D velocity model for earthquake location in the study area. Here we describe the main seismological characteristics of this seismic sequence and, relying on refined earthquakes location, we make inferences on the geometry of the thrust system responsible for the two strongest shocks.

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

    NASA Astrophysics Data System (ADS)

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

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

  18. Real-time locating systems (RTLS) in healthcare: a condensed primer

    PubMed Central

    2012-01-01

    Real-time locating systems (RTLS, also known as real-time location systems) have become an important component of many existing ubiquitous location aware systems. While GPS (global positioning system) has been quite successful as an outdoor real-time locating solution, it fails to repeat this success indoors. A number of RTLS technologies have been used to solve indoor tracking problems. The ability to accurately track the location of assets and individuals indoors has many applications in healthcare. This paper provides a condensed primer of RTLS in healthcare, briefly covering the many options and technologies that are involved, as well as the various possible applications of RTLS in healthcare facilities and their potential benefits, including capital expenditure reduction and workflow and patient throughput improvements. The key to a successful RTLS deployment lies in picking the right RTLS option(s) and solution(s) for the application(s) or problem(s) at hand. Where this application-technology match has not been carefully thought of, any technology will be doomed to failure or to achieving less than optimal results. PMID:22741760

  19. Real-time locating systems (RTLS) in healthcare: a condensed primer.

    PubMed

    Kamel Boulos, Maged N; Berry, Geoff

    2012-06-28

    Real-time locating systems (RTLS, also known as real-time location systems) have become an important component of many existing ubiquitous location aware systems. While GPS (global positioning system) has been quite successful as an outdoor real-time locating solution, it fails to repeat this success indoors. A number of RTLS technologies have been used to solve indoor tracking problems. The ability to accurately track the location of assets and individuals indoors has many applications in healthcare. This paper provides a condensed primer of RTLS in healthcare, briefly covering the many options and technologies that are involved, as well as the various possible applications of RTLS in healthcare facilities and their potential benefits, including capital expenditure reduction and workflow and patient throughput improvements. The key to a successful RTLS deployment lies in picking the right RTLS option(s) and solution(s) for the application(s) or problem(s) at hand. Where this application-technology match has not been carefully thought of, any technology will be doomed to failure or to achieving less than optimal results.

  20. 3D-Web-GIS RFID Location Sensing System for Construction Objects

    PubMed Central

    2013-01-01

    Construction site managers could benefit from being able to visualize on-site construction objects. Radio frequency identification (RFID) technology has been shown to improve the efficiency of construction object management. The objective of this study is to develop a 3D-Web-GIS RFID location sensing system for construction objects. An RFID 3D location sensing algorithm combining Simulated Annealing (SA) and a gradient descent method is proposed to determine target object location. In the algorithm, SA is used to stabilize the search process and the gradient descent method is used to reduce errors. The locations of the analyzed objects are visualized using the 3D-Web-GIS system. A real construction site is used to validate the applicability of the proposed method, with results indicating that the proposed approach can provide faster, more accurate, and more stable 3D positioning results than other location sensing algorithms. The proposed system allows construction managers to better understand worksite status, thus enhancing managerial efficiency. PMID:23864821

  1. 3D-Web-GIS RFID location sensing system for construction objects.

    PubMed

    Ko, Chien-Ho

    2013-01-01

    Construction site managers could benefit from being able to visualize on-site construction objects. Radio frequency identification (RFID) technology has been shown to improve the efficiency of construction object management. The objective of this study is to develop a 3D-Web-GIS RFID location sensing system for construction objects. An RFID 3D location sensing algorithm combining Simulated Annealing (SA) and a gradient descent method is proposed to determine target object location. In the algorithm, SA is used to stabilize the search process and the gradient descent method is used to reduce errors. The locations of the analyzed objects are visualized using the 3D-Web-GIS system. A real construction site is used to validate the applicability of the proposed method, with results indicating that the proposed approach can provide faster, more accurate, and more stable 3D positioning results than other location sensing algorithms. The proposed system allows construction managers to better understand worksite status, thus enhancing managerial efficiency.

  2. Adaptive learning compressive tracking based on Markov location prediction

    NASA Astrophysics Data System (ADS)

    Zhou, Xingyu; Fu, Dongmei; Yang, Tao; Shi, Yanan

    2017-03-01

    Object tracking is an interdisciplinary research topic in image processing, pattern recognition, and computer vision which has theoretical and practical application value in video surveillance, virtual reality, and automatic navigation. Compressive tracking (CT) has many advantages, such as efficiency and accuracy. However, when there are object occlusion, abrupt motion and blur, similar objects, and scale changing, the CT has the problem of tracking drift. We propose the Markov object location prediction to get the initial position of the object. Then CT is used to locate the object accurately, and the classifier parameter adaptive updating strategy is given based on the confidence map. At the same time according to the object location, extract the scale features, which is able to deal with object scale variations effectively. Experimental results show that the proposed algorithm has better tracking accuracy and robustness than current advanced algorithms and achieves real-time performance.

  3. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... provisions of the Act of August 12, 1953 (67 Stat. 539), and particularly sec. 3 thereof, any mining claim... deposit which is a fissionable source material and which, except for the possible contrary construction of... affected by such possible contrary construction, be valid and effective, in all respects to the same extent...

  4. 43 CFR 3746.1 - Mining locations for fissionable source materials.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... provisions of the Act of August 12, 1953 (67 Stat. 539), and particularly sec. 3 thereof, any mining claim... deposit which is a fissionable source material and which, except for the possible contrary construction of... affected by such possible contrary construction, be valid and effective, in all respects to the same extent...

  5. Ejectable underwater sound source recovery assembly

    NASA Technical Reports Server (NTRS)

    Irick, S. C. (Inventor)

    1974-01-01

    An underwater sound source is described that may be ejectably mounted on any mobile device that travels over water, to facilitate in the location and recovery of the device when submerged. A length of flexible line maintains a connection between the mobile device and the sound source. During recovery, the sound source is located be particularly useful in the recovery of spent rocket motors that bury in the ocean floor upon impact.

  6. InSAR Surface Deformation and Source Modelling at Semisopochnoi Island During the 2014 and 2015 Seismic Swarms with Constraints from Geochemical and Seismic Analysis

    NASA Astrophysics Data System (ADS)

    DeGrandpre, K.; Pesicek, J. D.; Lu, Z.

    2017-12-01

    During the summer of 2014 and the early spring of 2015 two notable increases in seismic activity at Semisopochnoi Island in the western Aleutian islands were recorded on AVO seismometers on Semisopochnoi and neighboring islands. These seismic swarms did not lead to an eruption. This study employs interferometric synthetic aperture radar (InSAR) techniques using TerraSAR-X images in conjunction with more accurately relocating the recorded seismic events through simultaneous inversion of event travel times and a three-dimensional velocity model using tomoDD. The InSAR images exhibit surprising coherence and an island wide spatial distribution of inflation that is then used in Mogi, Okada, spheroid, and ellipsoid source models in order to define the three-dimensional location and volume change required for a source at the volcano to produce the observed surface deformation. The tomoDD relocations provide a more accurate and realistic three-dimensional velocity model as well as a tighter clustering of events for both swarms that clearly outline a linear seismic void within the larger group of shallow (<10 km) seismicity. The source models are fit to this void and pressure estimates from geochemical analysis are used to verify the storage depth of magmas at Semisopochnoi. Comparisons of calculated source cavity, magma injection, and surface deformation volumes are made in order to assess the reality behind the various modelling estimates. Incorporating geochemical and seismic data to provide constraints on surface deformation source inversions provides an interdisciplinary approach that can be used to make more accurate interpretations of dynamic observations.

  7. A multi-subject evaluation of uncertainty in anatomical landmark location on shoulder kinematic description.

    PubMed

    Langenderfer, Joseph E; Rullkoetter, Paul J; Mell, Amy G; Laz, Peter J

    2009-04-01

    An accurate assessment of shoulder kinematics is useful for understanding healthy normal and pathological mechanics. Small variability in identifying and locating anatomical landmarks (ALs) has potential to affect reported shoulder kinematics. The objectives of this study were to quantify the effect of landmark location variability on scapular and humeral kinematic descriptions for multiple subjects using probabilistic analysis methods, and to evaluate the consistency in results across multiple subjects. Data from 11 healthy subjects performing humeral elevation in the scapular plane were used to calculate Euler angles describing humeral and scapular kinematics. Probabilistic analyses were performed for each subject to simulate uncertainty in the locations of 13 upper-extremity ALs. For standard deviations of 4 mm in landmark location, the analysis predicted Euler angle envelopes between the 1 and 99 percentile bounds of up to 16.6 degrees . While absolute kinematics varied with the subject, the average 1-99% kinematic ranges for the motion were consistent across subjects and sensitivity factors showed no statistically significant differences between subjects. The description of humeral kinematics was most sensitive to the location of landmarks on the thorax, while landmarks on the scapula had the greatest effect on the description of scapular elevation. The findings of this study can provide a better understanding of kinematic variability, which can aid in making accurate clinical diagnoses and refining kinematic measurement techniques.

  8. Locating PHEV exchange stations in V2G

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pan, Feng; Bent, Russell; Berscheid, Alan

    2010-01-01

    Plug-in hybrid electric vehicle (PREV) is an environment friendly modem transportation method and has been rapidly penetrate the transportation system. Renewable energy is another contributor to clean power but the associated intermittence increases the uncertainty in power generation. As a foreseen benefit of a vchicle-to-grid (V2G) system, PREV supporting infrastructures like battery exchange stations can provide battery service to PREV customers as well as being plugged into a power grid as energy sources and stabilizer. The locations of exchange stations are important for these two objectives under constraints from both ,transportation system and power grid. To model this location problemmore » and to understand and analyze the benefit of a V2G system, we develop a two-stage stochastic program to optimally locate the stations prior to the realizations of battery demands, loads, and generation capacity of renewable power sources. Based on this model, we use two data sets to construct the V2G systems and test the benefit and the performance of these systems.« less

  9. Spectroscopic confirmation of the optical identification of X-ray sources used to determine accurate positions for the anomalous X-ray pulsars 1E 2259+58.6 and 4U 0142+61

    NASA Astrophysics Data System (ADS)

    van den Berg, M.; Verbunt, F.

    2001-03-01

    Optical spectra show that two proposed counterparts for X-ray sources detected near 1E 2259+58.6 are late G stars, and a proposed counterpart for a source near 4U 0142+61 is a dMe star. The X-ray luminosities are as expected for such stars. We thus confirm the optical identification of the three X-ray objects, and thereby the correctness of the accurate positions for 1E 2259+58.6 and 4U 0142+61 based on them. Based on observations made with the William Herschel Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  10. An iterative method for obtaining the optimum lightning location on a spherical surface

    NASA Technical Reports Server (NTRS)

    Chao, Gao; Qiming, MA

    1991-01-01

    A brief introduction to the basic principles of an eigen method used to obtain the optimum source location of lightning is presented. The location of the optimum source is obtained by using multiple direction finders (DF's) on a spherical surface. An improvement of this method, which takes the distance of source-DF's as a constant, is presented. It is pointed out that using a weight factor of signal strength is not the most ideal method because of the inexact inverse signal strength-distance relation and the inaccurate signal amplitude. An iterative calculation method is presented using the distance from the source to the DF as a weight factor. This improved method has higher accuracy and needs only a little more calculation time. Some computer simulations for a 4DF system are presented to show the improvement of location through use of the iterative method.

  11. Microseismic event location by master-event waveform stacking

    NASA Astrophysics Data System (ADS)

    Grigoli, F.; Cesca, S.; Dahm, T.

    2016-12-01

    Waveform stacking location methods are nowadays extensively used to monitor induced seismicity monitoring assoiciated with several underground industrial activities such as Mining, Oil&Gas production and Geothermal energy exploitation. In the last decade a significant effort has been spent to develop or improve methodologies able to perform automated seismological analysis for weak events at a local scale. This effort was accompanied by the improvement of monitoring systems, resulting in an increasing number of large microseismicity catalogs. The analysis of microseismicity is challenging, because of the large number of recorded events often characterized by a low signal-to-noise ratio. A significant limitation of the traditional location approaches is that automated picking is often done on each seismogram individually, making little or no use of the coherency information between stations. In order to improve the performance of the traditional location methods, in the last year, alternative approaches have been proposed. These methods exploits the coherence of the waveforms recorded at different stations and do not require any automated picking procedure. The main advantage of this methods relies on their robustness even when the recorded waveforms are very noisy. On the other hand, like any other location method, the location performance strongly depends on the accuracy of the available velocity model. When dealing with inaccurate velocity models, in fact, location results can be affected by large errors. Here we will introduce a new automated waveform stacking location method which is less dependent on the knowledge of the velocity model and presents several benefits, which improve the location accuracy: 1) it accounts for phase delays due to local site effects, e.g. surface topography or variable sediment thickness 2) theoretical velocity model are only used to estimate travel times within the source volume, and not along the whole source-sensor path. We

  12. Physical Therapists Make Accurate and Appropriate Discharge Recommendations for Patients Who Are Acutely Ill

    PubMed Central

    Fields, Christina J.; Fernandez, Natalia

    2010-01-01

    Background Acute care physical therapists contribute to the complex process of patient discharge planning. As physical therapists are experts at evaluating functional abilities and are able to incorporate various other factors relevant to discharge planning, it was expected that physical therapists’ recommendations of patient discharge location would be both accurate and appropriate. Objective This study determined how often the therapists’ recommendations for patient discharge location and services were implemented, representing the accuracy of the recommendations. The impact of unimplemented recommendations on readmission rate was examined, reflecting the appropriateness of the recommendations. Design This retrospective study included the discharge recommendations of 40 acute care physical therapists for 762 patients in a large academic medical center. The frequency of mismatch between the physical therapist's recommendation and the patient's actual discharge location and services was calculated. The mismatch variable had 3 levels: match, mismatch with services lacking, or mismatch with different services. Regression analysis was used to test whether mismatch status, patient age, length of admission, or discharge location predicted patient readmittance. Results Overall, physical therapists’ discharge recommendations were implemented 83% of the time. Patients were 2.9 times more likely to be readmitted when the therapist's discharge recommendation was not implemented and recommended follow-up services were lacking (mismatch with services lacking) compared with patients with a match. Limitations This study was limited to one facility. Limited information about the patients was collected, and data on patient readmission to other facilities were not collected. Conclusions This study supports the role of physical therapists in discharge planning in the acute care setting. Physical therapists demonstrated the ability to make accurate and appropriate discharge

  13. Real-time Accurate Surface Reconstruction Pipeline for Vision Guided Planetary Exploration Using Unmanned Ground and Aerial Vehicles

    NASA Technical Reports Server (NTRS)

    Almeida, Eduardo DeBrito

    2012-01-01

    This report discusses work completed over the summer at the Jet Propulsion Laboratory (JPL), California Institute of Technology. A system is presented to guide ground or aerial unmanned robots using computer vision. The system performs accurate camera calibration, camera pose refinement and surface extraction from images collected by a camera mounted on the vehicle. The application motivating the research is planetary exploration and the vehicles are typically rovers or unmanned aerial vehicles. The information extracted from imagery is used primarily for navigation, as robot location is the same as the camera location and the surfaces represent the terrain that rovers traverse. The processed information must be very accurate and acquired very fast in order to be useful in practice. The main challenge being addressed by this project is to achieve high estimation accuracy and high computation speed simultaneously, a difficult task due to many technical reasons.

  14. Text Content Pushing Technology Research Based on Location and Topic

    NASA Astrophysics Data System (ADS)

    Wei, Dongqi; Wei, Jianxin; Wumuti, Naheman; Jiang, Baode

    2016-11-01

    In the field, geological workers usually want to obtain related geological background information in the working area quickly and accurately. This information exists in the massive geological data, text data is described in natural language accounted for a large proportion. This paper studied location information extracting method in the mass text data; proposed a geographic location—geological content—geological content related algorithm based on Spark and Mapreduce2, finally classified content by using KNN, and built the content pushing system based on location and topic. It is running in the geological survey cloud, and we have gained a good effect in testing by using real geological data.

  15. Comparing methods for Earthquake Location

    NASA Astrophysics Data System (ADS)

    Turkaya, Semih; Bodin, Thomas; Sylvander, Matthieu; Parroucau, Pierre; Manchuel, Kevin

    2017-04-01

    There are plenty of methods available for locating small magnitude point source earthquakes. However, it is known that these different approaches produce different results. For each approach, results also depend on a number of parameters which can be separated into two main branches: (1) parameters related to observations (number and distribution of for example) and (2) parameters related to the inversion process (velocity model, weighting parameters, initial location etc.). Currently, the results obtained from most of the location methods do not systematically include quantitative uncertainties. The effect of the selected parameters on location uncertainties is also poorly known. Understanding the importance of these different parameters and their effect on uncertainties is clearly required to better constrained knowledge on fault geometry, seismotectonic processes and at the end to improve seismic hazard assessment. In this work, realized in the frame of the SINAPS@ research program (http://www.institut-seism.fr/projets/sinaps/), we analyse the effect of different parameters on earthquakes location (e.g. type of phase, max. hypocentral separation etc.). We compare several codes available (Hypo71, HypoDD, NonLinLoc etc.) and determine their strengths and weaknesses in different cases by means of synthetic tests. The work, performed for the moment on synthetic data, is planned to be applied, in a second step, on data collected by the Midi-Pyrénées Observatory (OMP).

  16. Adaptive Environmental Source Localization and Tracking with Unknown Permittivity and Path Loss Coefficients †

    PubMed Central

    Fidan, Barış; Umay, Ilknur

    2015-01-01

    Accurate signal-source and signal-reflector target localization tasks via mobile sensory units and wireless sensor networks (WSNs), including those for environmental monitoring via sensory UAVs, require precise knowledge of specific signal propagation properties of the environment, which are permittivity and path loss coefficients for the electromagnetic signal case. Thus, accurate estimation of these coefficients has significant importance for the accuracy of location estimates. In this paper, we propose a geometric cooperative technique to instantaneously estimate such coefficients, with details provided for received signal strength (RSS) and time-of-flight (TOF)-based range sensors. The proposed technique is integrated to a recursive least squares (RLS)-based adaptive localization scheme and an adaptive motion control law, to construct adaptive target localization and adaptive target tracking algorithms, respectively, that are robust to uncertainties in aforementioned environmental signal propagation coefficients. The efficiency of the proposed adaptive localization and tracking techniques are both mathematically analysed and verified via simulation experiments. PMID:26690441

  17. Accurate high-throughput structure mapping and prediction with transition metal ion FRET

    PubMed Central

    Yu, Xiaozhen; Wu, Xiongwu; Bermejo, Guillermo A.; Brooks, Bernard R.; Taraska, Justin W.

    2013-01-01

    Mapping the landscape of a protein’s conformational space is essential to understanding its functions and regulation. The limitations of many structural methods have made this process challenging for most proteins. Here, we report that transition metal ion FRET (tmFRET) can be used in a rapid, highly parallel screen, to determine distances from multiple locations within a protein at extremely low concentrations. The distances generated through this screen for the protein Maltose Binding Protein (MBP) match distances from the crystal structure to within a few angstroms. Furthermore, energy transfer accurately detects structural changes during ligand binding. Finally, fluorescence-derived distances can be used to guide molecular simulations to find low energy states. Our results open the door to rapid, accurate mapping and prediction of protein structures at low concentrations, in large complex systems, and in living cells. PMID:23273426

  18. Photon escape probabilities in a semi-infinite plane-parallel medium. [from electron plasma surrounding galactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Williams, A. C.; Elsner, R. F.; Weisskopf, M. C.; Darbro, W.

    1984-01-01

    It is shown in this work how to obtain the probabilities of photons escaping from a cold electron plasma environment after having undergone an arbitrary number of scatterings. This is done by retaining the exact differential cross section for Thomson scattering as opposed to using its polarization and angle averaged form. The results are given in the form of recursion relations. The geometry used is the semi-infinite plane-parallel geometry witlh a photon source located on a plane at an arbitrary optical depth below the surface. Analytical expressions are given for the probabilities which are accurate over a wide range of initial optical depth. These results can be used to model compact X-ray galactic sources which are surrounded by an electron-rich plasma.

  19. A realistic multimodal modeling approach for the evaluation of distributed source analysis: application to sLORETA.

    PubMed

    Cosandier-Rimélé, D; Ramantani, G; Zentner, J; Schulze-Bonhage, A; Dümpelmann, M

    2017-10-01

    Electrical source localization (ESL) deriving from scalp EEG and, in recent years, from intracranial EEG (iEEG), is an established method in epilepsy surgery workup. We aimed to validate the distributed ESL derived from scalp EEG and iEEG, particularly regarding the spatial extent of the source, using a realistic epileptic spike activity simulator. ESL was applied to the averaged scalp EEG and iEEG spikes of two patients with drug-resistant structural epilepsy. The ESL results for both patients were used to outline the location and extent of epileptic cortical patches, which served as the basis for designing a spatiotemporal source model. EEG signals for both modalities were then generated for different anatomic locations and spatial extents. ESL was subsequently performed on simulated signals with sLORETA, a commonly used distributed algorithm. ESL accuracy was quantitatively assessed for iEEG and scalp EEG. The source volume was overestimated by sLORETA at both EEG scales, with the error increasing with source size, particularly for iEEG. For larger sources, ESL accuracy drastically decreased, and reconstruction volumes shifted to the center of the head for iEEG, while remaining stable for scalp EEG. Overall, the mislocalization of the reconstructed source was more pronounced for iEEG. We present a novel multiscale framework for the evaluation of distributed ESL, based on realistic multiscale EEG simulations. Our findings support that reconstruction results for scalp EEG are often more accurate than for iEEG, owing to the superior 3D coverage of the head. Particularly the iEEG-derived reconstruction results for larger, widespread generators should be treated with caution.

  20. A realistic multimodal modeling approach for the evaluation of distributed source analysis: application to sLORETA

    NASA Astrophysics Data System (ADS)

    Cosandier-Rimélé, D.; Ramantani, G.; Zentner, J.; Schulze-Bonhage, A.; Dümpelmann, M.

    2017-10-01

    Objective. Electrical source localization (ESL) deriving from scalp EEG and, in recent years, from intracranial EEG (iEEG), is an established method in epilepsy surgery workup. We aimed to validate the distributed ESL derived from scalp EEG and iEEG, particularly regarding the spatial extent of the source, using a realistic epileptic spike activity simulator. Approach. ESL was applied to the averaged scalp EEG and iEEG spikes of two patients with drug-resistant structural epilepsy. The ESL results for both patients were used to outline the location and extent of epileptic cortical patches, which served as the basis for designing a spatiotemporal source model. EEG signals for both modalities were then generated for different anatomic locations and spatial extents. ESL was subsequently performed on simulated signals with sLORETA, a commonly used distributed algorithm. ESL accuracy was quantitatively assessed for iEEG and scalp EEG. Main results. The source volume was overestimated by sLORETA at both EEG scales, with the error increasing with source size, particularly for iEEG. For larger sources, ESL accuracy drastically decreased, and reconstruction volumes shifted to the center of the head for iEEG, while remaining stable for scalp EEG. Overall, the mislocalization of the reconstructed source was more pronounced for iEEG. Significance. We present a novel multiscale framework for the evaluation of distributed ESL, based on realistic multiscale EEG simulations. Our findings support that reconstruction results for scalp EEG are often more accurate than for iEEG, owing to the superior 3D coverage of the head. Particularly the iEEG-derived reconstruction results for larger, widespread generators should be treated with caution.

  1. Performance Evaluation of Block Acquisition and Tracking Algorithms Using an Open Source GPS Receiver Platform

    NASA Technical Reports Server (NTRS)

    Ramachandran, Ganesh K.; Akopian, David; Heckler, Gregory W.; Winternitz, Luke B.

    2011-01-01

    Location technologies have many applications in wireless communications, military and space missions, etc. US Global Positioning System (GPS) and other existing and emerging Global Navigation Satellite Systems (GNSS) are expected to provide accurate location information to enable such applications. While GNSS systems perform very well in strong signal conditions, their operation in many urban, indoor, and space applications is not robust or even impossible due to weak signals and strong distortions. The search for less costly, faster and more sensitive receivers is still in progress. As the research community addresses more and more complicated phenomena there exists a demand on flexible multimode reference receivers, associated SDKs, and development platforms which may accelerate and facilitate the research. One of such concepts is the software GPS/GNSS receiver (GPS SDR) which permits a facilitated access to algorithmic libraries and a possibility to integrate more advanced algorithms without hardware and essential software updates. The GNU-SDR and GPS-SDR open source receiver platforms are such popular examples. This paper evaluates the performance of recently proposed block-corelator techniques for acquisition and tracking of GPS signals using open source GPS-SDR platform.

  2. Development of Advanced Signal Processing and Source Imaging Methods for Superparamagnetic Relaxometry

    PubMed Central

    Huang, Ming-Xiong; Anderson, Bill; Huang, Charles W.; Kunde, Gerd J.; Vreeland, Erika C.; Huang, Jeffrey W.; Matlashov, Andrei N.; Karaulanov, Todor; Nettles, Christopher P.; Gomez, Andrew; Minser, Kayla; Weldon, Caroline; Paciotti, Giulio; Harsh, Michael; Lee, Roland R.; Flynn, Edward R.

    2017-01-01

    Superparamagnetic Relaxometry (SPMR) is a highly sensitive technique for the in vivo detection of tumor cells and may improve early stage detection of cancers. SPMR employs superparamagnetic iron oxide nanoparticles (SPION). After a brief magnetizing pulse is used to align the SPION, SPMR measures the time decay of SPION using Super-conducting Quantum Interference Device (SQUID) sensors. Substantial research has been carried out in developing the SQUID hardware and in improving the properties of the SPION. However, little research has been done in the pre-processing of sensor signals and post-processing source modeling in SPMR. In the present study, we illustrate new pre-processing tools that were developed to: 1) remove trials contaminated with artifacts, 2) evaluate and ensure that a single decay process associated with bounded SPION exists in the data, 3) automatically detect and correct flux jumps, and 4) accurately fit the sensor signals with different decay models. Furthermore, we developed an automated approach based on multi-start dipole imaging technique to obtain the locations and magnitudes of multiple magnetic sources, without initial guesses from the users. A regularization process was implemented to solve the ambiguity issue related to the SPMR source variables. A procedure based on reduced chi-square cost-function was introduced to objectively obtain the adequate number of dipoles that describe the data. The new pre-processing tools and multi-start source imaging approach have been successfully evaluated using phantom data. In conclusion, these tools and multi-start source modeling approach substantially enhance the accuracy and sensitivity in detecting and localizing sources from the SPMR signals. Furthermore, multi-start approach with regularization provided robust and accurate solutions for a poor SNR condition similar to the SPMR detection sensitivity in the order of 1000 cells. We believe such algorithms will help establishing the industrial

  3. Efficient Processing of Data for Locating Lightning Strikes

    NASA Technical Reports Server (NTRS)

    Medelius, Pedro J.; Starr, Stan

    2003-01-01

    Two algorithms have been devised to increase the efficiency of processing of data in lightning detection and ranging (LDAR) systems so as to enable the accurate location of lightning strikes in real time. In LDAR, the location of a lightning strike is calculated by solving equations for the differences among the times of arrival (DTOAs) of the lightning signals at multiple antennas as functions of the locations of the antennas and the speed of light. The most difficult part of the problem is computing the DTOAs from digitized versions of the signals received by the various antennas. One way (a time-domain approach) to determine the DTOAs is to compute cross-correlations among variously differentially delayed replicas of the digitized signals and to select, as the DTOAs, those differential delays that yield the maximum correlations. Another way (a frequency-domain approach) to determine the DTOAs involves the computation of cross-correlations among Fourier transforms of variously differentially phased replicas of the digitized signals, along with utilization of the relationship among phase difference, time delay, and frequency.

  4. Source-Monitoring Training Facilitates Preschoolers' Eyewitness Memory Performance.

    ERIC Educational Resources Information Center

    Thierry, Karen L.; Spence, Melanie J.

    2002-01-01

    Investigated whether source-monitoring training would decrease 3- to 4-year-olds' suggestibility. After observing live or video target-events, children received source-monitoring or recognition (control) training. Found that children given source-monitoring training were more accurate than control group children in response to misleading and…

  5. Microseismic imaging using Geometric-mean Reverse-Time Migration in Hydraulic Fracturing Monitoring

    NASA Astrophysics Data System (ADS)

    Yin, J.; Ng, R.; Nakata, N.

    2017-12-01

    Unconventional oil and gas exploration techniques such as hydraulic fracturing are associated with microseismic events related to the generation and development of fractures. For example, hydraulic fracturing, which is popular in Southern Oklahoma, produces earthquakes that are greater than magnitude 2.0. Finding the accurate locations, and mechanisms, of these events provides important information of local stress conditions, fracture distribution, hazard assessment, and economical impact. The accurate source location is also important to separate fracking-induced and wastewater disposal induced seismicity. Here, we implement a wavefield-based imaging method called Geometric-mean Reverse-Time Migration (GmRTM), which takes the advantage of accurate microseismic location based on wavefield back projection. We apply GmRTM to microseismic data collected during hydraulic fracturing for imaging microseismic source locations, and potentially, fractures. Assuming an accurate velocity model, GmRTM can improve the spatial resolution of source locations compared to HypoDD or P/S travel-time based methods. We will discuss the results from GmRTM and HypoDD using this field dataset and synthetic data.

  6. Local and regional factors affecting atmospheric mercury speciation at a remote location

    USGS Publications Warehouse

    Manolopoulos, H.; Schauer, J.J.; Purcell, M.D.; Rudolph, T.M.; Olson, M.L.; Rodger, B.; Krabbenhoft, D.P.

    2007-01-01

    Atmospheric concentrations of elemental (Hg0), reactive gaseous (RGM), and particulate (PHg) mercury were measured at two remote sites in the midwestern United States. Concurrent measurements of Hg0, PHg, and RGM obtained at Devil's Lake and Mt. Horeb, located approximately 65 km apart, showed that Hg0 and PHg concentrations were affected by regional, as well as local sources, while RGM was mainly impacted by local sources. Plumes reaching the Devil's Lake site from a nearby coal-fired power plant significantly impacted SO2 and RGM concentrations at Devil's Lake, but had little impact on Hg0. Our findings suggest that traditional modeling approaches to assess sources of mercury deposited that utilize source emissions and large-scale grids may not be sufficient to predict mercury deposition at sensitive locations due to the importance of small-scale sources and processes. We suggest the use of a receptor-based monitoring to better understand mercury source-receptor relationships. ?? 2007 NRC Canada.

  7. Sources of Caffeine in Diets of US Children and Adults: Trends by Beverage Type and Purchase Location.

    PubMed

    Drewnowski, Adam; Rehm, Colin D

    2016-03-10

    New sources of caffeine, besides coffee and tea, have been introduced into the US food supply. Data on caffeine consumption age and purchase location can help guide public health policy. National Health and Nutrition Examination Surveys (NHANES) were used to estimate population-level caffeine intakes, using data from 24-h dietary recall. First, caffeine intakes by age-group and beverage type were estimated using the most recent 2011-2012 data (n = 7456). Second, fourteen years trends in caffeine consumption, overall and by beverage type, were evaluated for adults and children. Trend analyses were conducted by age groups. Last, trends in caffeine intakes by purchase location and beverage type were estimated. In 2011-2012, children aged four to eight years consumed the least caffeine (15 mg/day), and adults aged 51-70 years consumed the most (213 mg/day). The population mean (age ≥ four years) was 135 mg/day, driven largely by coffee (90 mg/day), tea (25 mg/day), and soda (21 mg/day). For the 14-19 years and 20-34 years age-groups, energy drinks contributed 6 mg/day (9.9%) and 5 mg/day (4.5%), respectively. The bulk of caffeine came from store-bought coffee and tea. Among both children and adults combined, caffeine intakes declined from 175 mg/day (1999-2000) to 142 mg/day (2011-2012), largely driven by a drop in caffeine from soda (41 mg/day to 21 mg/day). Store-bought coffee and tea remain principal drivers of caffeine intake in the US. Sodas and energy drinks make minor contributions to overall caffeine intakes.

  8. Sources of Caffeine in Diets of US Children and Adults: Trends by Beverage Type and Purchase Location

    PubMed Central

    Drewnowski, Adam; Rehm, Colin D.

    2016-01-01

    New sources of caffeine, besides coffee and tea, have been introduced into the US food supply. Data on caffeine consumption age and purchase location can help guide public health policy. National Health and Nutrition Examination Surveys (NHANES) were used to estimate population-level caffeine intakes, using data from 24-h dietary recall. First, caffeine intakes by age-group and beverage type were estimated using the most recent 2011–2012 data (n = 7456). Second, fourteen years trends in caffeine consumption, overall and by beverage type, were evaluated for adults and children. Trend analyses were conducted by age groups. Last, trends in caffeine intakes by purchase location and beverage type were estimated. In 2011–2012, children aged four to eight years consumed the least caffeine (15 mg/day), and adults aged 51–70 years consumed the most (213 mg/day). The population mean (age ≥ four years) was 135 mg/day, driven largely by coffee (90 mg/day), tea (25 mg/day), and soda (21 mg/day). For the 14–19 years and 20–34 years age-groups, energy drinks contributed 6 mg/day (9.9%) and 5 mg/day (4.5%), respectively. The bulk of caffeine came from store-bought coffee and tea. Among both children and adults combined, caffeine intakes declined from 175 mg/day (1999–2000) to 142 mg/day (2011–2012), largely driven by a drop in caffeine from soda (41 mg/day to 21 mg/day). Store-bought coffee and tea remain principal drivers of caffeine intake in the US. Sodas and energy drinks make minor contributions to overall caffeine intakes. PMID:26978391

  9. Wave-equation migration velocity inversion using passive seismic sources

    NASA Astrophysics Data System (ADS)

    Witten, B.; Shragge, J. C.

    2015-12-01

    Seismic monitoring at injection sites (e.g., CO2 sequestration, waste water disposal, hydraulic fracturing) has become an increasingly important tool for hazard identification and avoidance. The information obtained from this data is often limited to seismic event properties (e.g., location, approximate time, moment tensor), the accuracy of which greatly depends on the estimated elastic velocity models. However, creating accurate velocity models from passive array data remains a challenging problem. Common techniques rely on picking arrivals or matching waveforms requiring high signal-to-noise data that is often not available for the magnitude earthquakes observed over injection sites. We present a new method for obtaining elastic velocity information from earthquakes though full-wavefield wave-equation imaging and adjoint-state tomography. The technique exploits the fact that the P- and S-wave arrivals originate at the same time and location in the subsurface. We generate image volumes by back-propagating P- and S-wave data through initial Earth models and then applying a correlation-based extended-imaging condition. Energy focusing away from zero lag in the extended image volume is used as a (penalized) residual in an adjoint-state tomography scheme to update the P- and S-wave velocity models. We use an acousto-elastic approximation to greatly reduce the computational cost. Because the method requires neither an initial source location or origin time estimate nor picking of arrivals, it is suitable for low signal-to-noise datasets, such as microseismic data. Synthetic results show that with a realistic distribution of microseismic sources, P- and S-velocity perturbations can be recovered. Although demonstrated at an oil and gas reservoir scale, the technique can be applied to problems of all scales from geologic core samples to global seismology.

  10. Subsurface solute transport with one-, two-, and three-dimensional arbitrary shape sources

    NASA Astrophysics Data System (ADS)

    Chen, Kewei; Zhan, Hongbin; Zhou, Renjie

    2016-07-01

    Solutions with one-, two-, and three-dimensional arbitrary shape source geometries will be very helpful tools for investigating a variety of contaminant transport problems in the geological media. This study proposed a general method to develop new solutions for solute transport in a saturated, homogeneous aquifer (confined or unconfined) with a constant, unilateral groundwater flow velocity. Several typical source geometries, such as arbitrary line sources, vertical and horizontal patch sources, circular and volumetric sources, were considered. The sources can sit on the upper or lower aquifer boundary to simulate light non-aqueous-phase-liquids (LNAPLs) or dense non-aqueous-phase-liquids (DNAPLs), respectively, or can be located anywhere inside the aquifer. The developed new solutions were tested against previous benchmark solutions under special circumstances and were shown to be robust and accurate. Such solutions can also be used as a starting point for the inverse problem of source zone and source geometry identification in the future. The following findings can be obtained from analyzing the solutions. The source geometry, including shape and orientation, generally played an important role for the concentration profile through the entire transport process. When comparing the inclined line sources with the horizontal line sources, the concentration contours expanded considerably along the vertical direction, and shrank considerably along the groundwater flow direction. A planar source sitting on the upper aquifer boundary (such as a LNAPL pool) would lead to significantly different concentration profiles compared to a planar source positioned in a vertical plane perpendicular to the flow direction. For a volumetric source, its dimension along the groundwater flow direction became less important compared to its other two dimensions.

  11. Stratification of a closed region containing two buoyancy sources

    NASA Astrophysics Data System (ADS)

    Thompson, Andrew; Linden, Paul

    2005-11-01

    Many closed systems such as lakes, ocean basins, rooms etc. have inputs of buoyancy at different levels. We address the question of how the resulting stratification depends on the location of these sources. For example a lake is heated and cooled at the surface, while for a room cool air may be applied at the ceiling but the heat source may be a person standing on the floor. We present an experimental study of convection in a finite box in which we systematically vary the vertical location of two well-separated, constant buoyancy sources. We specifically consider the case of a dense source and a light source so that there is no net buoyancy flux into the tank. We study the development of the large-time stratification in the tank, which falls between one of two limits. When the location of the dense source is significantly higher than the light source, the fluid is well mixed and the system remains largely unstratified. When the location of the light source is significantly higher than the dense source, a two- layer stratification develops. We find that the circulation pattern is dominated by counter-flowing shear layers (Wong, Griffiths & Hughes, 2001), whose number and strength are strongly influenced by the buoyancy source locations. The shear layers are the primary means of communication between the plumes and thus play a large role in the resulting stratification. We support our findings with a simple numerical model.

  12. Antarctic Meteorite Location Map Series

    NASA Technical Reports Server (NTRS)

    Schutt, John (Editor); Fessler, Brian (Editor); Cassidy, William (Editor)

    1989-01-01

    Antarctica has been a prolific source of meteorites since meteorite concentrations were discovered in 1969. The Antarctic Search For Meteorites (ANSMET) project has been active over much of the Trans-Antarctic Mountain Range. The first ANSMET expedition (a joint U.S.-Japanese effort) discovered what turned out to be a significant concentration of meteorites at the Allan Hills in Victoria Land. Later reconnaissance in this region resulted in the discovery of meteorite concentrations on icefields to the west of the Allan Hills, at Reckling Moraine, and Elephant Moraine. Antarctic meteorite location maps (reduced versions) of the Allan Hills main, near western, middle western, and far western icefields and the Elephant Moraine icefield are presented. Other Antarctic meteorite location maps for the specimens found by the ANSMET project are being prepared.

  13. Automated vehicle location, data recording, friction measurement and applicator control for winter road maintenance.

    DOT National Transportation Integrated Search

    2010-02-01

    The first part of this project conducted a detailed evaluation of the ability of a new friction measurement system to : provide an accurate measure of road conditions. A system that records friction coefficient as a function of road : location was de...

  14. Numerical Simulation of the 2004 Indian Ocean Tsunami: Accurate Flooding and drying in Banda Aceh

    NASA Astrophysics Data System (ADS)

    Cui, Haiyang; Pietrzak, Julie; Stelling, Guus; Androsov, Alexey; Harig, Sven

    2010-05-01

    The Indian Ocean Tsunami on December 26, 2004 caused one of the largest tsunamis in recent times and led to widespread devastation and loss of life. One of the worst hit regions was Banda Aceh, which is the capital of the Aceh province, located in the northern part of Sumatra, 150km from the source of the earthquake. A German-Indonesian Tsunami Early Warning System (GITEWS) (www.gitews.de) is currently under active development. The work presented here is carried out within the GITEWS framework. One of the aims of this project is the development of accurate models with which to simulate the propagation, flooding and drying, and run-up of a tsunami. In this context, TsunAWI has been developed by the Alfred Wegener Institute; it is an explicit, () finite element model. However, the accurate numerical simulation of flooding and drying requires the conservation of mass and momentum. This is not possible in the current version of TsunAWi. The P1NC - P1element guarantees mass conservation in a global sense, yet as we show here it is important to guarantee mass conservation at the local level, that is within each individual cell. Here an unstructured grid, finite volume ocean model is presented. It is derived from the P1NC - P1 element, and is shown to be mass and momentum conserving. Then a number of simulations are presented, including dam break problems flooding over both a wet and a dry bed. Excellent agreement is found. Then we present simulations for Banda Aceh, and compare the results to on-site survey data, as well as to results from the original TsunAWI code.

  15. Modelling optimal location for pre-hospital helicopter emergency medical services.

    PubMed

    Schuurman, Nadine; Bell, Nathaniel J; L'Heureux, Randy; Hameed, Syed M

    2009-05-09

    Increasing the range and scope of early activation/auto launch helicopter emergency medical services (HEMS) may alleviate unnecessary injury mortality that disproportionately affects rural populations. To date, attempts to develop a quantitative framework for the optimal location of HEMS facilities have been absent. Our analysis used five years of critical care data from tertiary health care facilities, spatial data on origin of transport and accurate road travel time catchments for tertiary centres. A location optimization model was developed to identify where the expansion of HEMS would cover the greatest population among those currently underserved. The protocol was developed using geographic information systems (GIS) to measure populations, distances and accessibility to services. Our model determined Royal Inland Hospital (RIH) was the optimal site for an expanded HEMS - based on denominator population, distance to services and historical usage patterns. GIS based protocols for location of emergency medical resources can provide supportive evidence for allocation decisions - especially when resources are limited. In this study, we were able to demonstrate conclusively that a logical choice exists for location of additional HEMS. This protocol could be extended to location analysis for other emergency and health services.

  16. Location, Location, Location: Where Do Location-Based Services Fit into Your Institution's Social Media Mix?

    ERIC Educational Resources Information Center

    Nekritz, Tim

    2011-01-01

    Foursquare is a location-based social networking service that allows users to share their location with friends. Some college administrators have been thinking about whether and how to take the leap into location-based services, which are also known as geosocial networking services. These platforms, which often incorporate gaming elements like…

  17. Low temperature ion source for calutrons

    DOEpatents

    Veach, Allen M.; Bell, Jr., William A.; Howell, Jr., George D.

    1981-01-01

    A new ion source assembly for calutrons has been provided for the efficient separation of elements having high vapor pressures. The strategic location of cooling pads and improved insulation permits operation of the source at lower temperatures. A vapor valve constructed of graphite and located in a constantly increasing temperature gradient provides reliable control of the vapor flow from the charge bottle to the arc chamber. A pronounced saving in calutron operating time and equipment maintenance has been achieved with the use of the present ion source.

  18. Low temperature ion source for calutrons

    DOEpatents

    Veach, A.M.; Bell, W.A. Jr.; Howell, G.D. Jr.

    1979-10-10

    A new ion source assembly for calutrons has been provided for the efficient separation of elements having high vapor pressures. The strategic location of cooling pads and improved insulation permits operation of the source at lower temperatures. A vapor valve constructed of graphite and located in a constantly increasing temperature gradient provides reliable control of the vapor flow from the charge bottle to the arc chamber. A pronounced saving in calutron operating time and equipment maintenance has been achieved with the use of the present ion source.

  19. Scalar Dispersion from Point Sources in a Realistic Urban Environment

    NASA Astrophysics Data System (ADS)

    Salesky, S.; Giometto, M. G.; Christen, A.; Parlange, M. B.

    2016-12-01

    Accurate modeling of scalar dispersion within and above urban canopies is critical to properly predict air quality and dispersion (e.g. accidental contaminant release) in urban environments. We perform large eddy simulations (LES) of scalar dispersion from point sources in a typical North American neighborhood using topography and foliage density derived from airborne LIDAR scans with 1 m resolution in Vancouver, BC, Canada. The added drag force due to trees is parameterized in the LES as a function of the leaf area density (LAD) profile. Conversely, drag from buildings is accounted for using a direct forcing approach immersed-boundary method. The scalar advection-diffusion equation is discretized in a finite-volume framework, and accurate mass conservation is enforced through a recently developed Cartesian cut cell method. Simulations are performed with trees for different values of LAD, representative of summer and winter conditions, as well as a case without trees. The effects of varying mean wind direction (derived from observed wind climatologies) on dispersion patterns are also considered. Scalar release locations in the LES are informed by spatially distributed measurements of carbon dioxide concentration; CO2 is used as a tracer for fossil fuel emissions, since source strengths are well-known and the contribution from biological processes in this setting is small (<10%). The effects of leaf area density, source height, and wind direction on scalar statistics including the growth of the mean concentration plume and the fraction that escapes the urban canopy layer will be considered. In a companion study, the presence of trees was found to strongly modify sweep and ejection patterns for the momentum flux; here we consider the related issue of how vegetation influences coherent structures responsible for scalar transport.

  20. Technique to determine location of radio sources from measurements taken on spinning spacecraft

    NASA Technical Reports Server (NTRS)

    Fainberg, J.

    1979-01-01

    The procedure developed to extract average source direction and average source size from spin-modulated radio astronomy data measured on the IMP-6 spacecraft is described. Because all measurements are used, rather than just finding maxima or minima in the data, the method is very sensitive, even in the presence of large amounts of noise. The technique is applicable to all experiments with directivity characteristics. It is suitable for onboard processing on satellites to reduce the data flow to Earth. The application to spin-modulated nonpolarized radio astronomy data is made and includes the effects of noise, background, and second source interference. The analysis was tested with computer simulated data and the results agree with analytic predictions. Applications of this method with IMP-6 radio data have led to: (1) determination of source positions of traveling solar radio bursts at large distances from the Sun; (2) mapping of magnetospheric radio emissions by radio triangulation; and (3) detection of low frequency radio emissions from Jupiter and Saturn.

  1. The Subread aligner: fast, accurate and scalable read mapping by seed-and-vote

    PubMed Central

    Liao, Yang; Smyth, Gordon K.; Shi, Wei

    2013-01-01

    Read alignment is an ongoing challenge for the analysis of data from sequencing technologies. This article proposes an elegantly simple multi-seed strategy, called seed-and-vote, for mapping reads to a reference genome. The new strategy chooses the mapped genomic location for the read directly from the seeds. It uses a relatively large number of short seeds (called subreads) extracted from each read and allows all the seeds to vote on the optimal location. When the read length is <160 bp, overlapping subreads are used. More conventional alignment algorithms are then used to fill in detailed mismatch and indel information between the subreads that make up the winning voting block. The strategy is fast because the overall genomic location has already been chosen before the detailed alignment is done. It is sensitive because no individual subread is required to map exactly, nor are individual subreads constrained to map close by other subreads. It is accurate because the final location must be supported by several different subreads. The strategy extends easily to find exon junctions, by locating reads that contain sets of subreads mapping to different exons of the same gene. It scales up efficiently for longer reads. PMID:23558742

  2. Noise Source Identification in a Reverberant Field Using Spherical Beamforming

    NASA Astrophysics Data System (ADS)

    Choi, Young-Chul; Park, Jin-Ho; Yoon, Doo-Byung; Kwon, Hyu-Sang

    Identification of noise sources, their locations and strengths, has been taken great attention. The method that can identify noise sources normally assumes that noise sources are located at a free field. However, the sound in a reverberant field consists of that coming directly from the source plus sound reflected or scattered by the walls or objects in the field. In contrast to the exterior sound field, reflections are added to sound field. Therefore, the source location estimated by the conventional methods may give unacceptable error. In this paper, we explain the effects of reverberant field on interior source identification process and propose the method that can identify noise sources in the reverberant field.

  3. Predicting Debris-Slide Locations in Northwestern California

    Treesearch

    Mark E. Reid; Stephen D. Ellen; Dianne L. Brien; Juan de la Fuente; James N. Falls; Billie G. Hicks; Eric C. Johnson

    2007-01-01

    We tested four topographic models for predicting locations of debris-slide sources: 1) slope; 2) proximity to stream; 3) SHALSTAB with "standard" parameters; and 4) debris-slide-prone landforms, which delineates areas similar to "inner gorge" and "headwall swale" using experience-based rules. These approaches were compared in three diverse...

  4. Near-source mobile methane emission estimates using EPA Method33a and a novel probabilistic approach as a basis for leak quantification in urban areas

    NASA Astrophysics Data System (ADS)

    Albertson, J. D.

    2015-12-01

    Methane emissions from underground pipeline leaks remain an ongoing issue in the development of accurate methane emission inventories for the natural gas supply chain. Application of mobile methods during routine street surveys would help address this issue, but there are large uncertainties in current approaches. In this paper, we describe results from a series of near-source (< 30 m) controlled methane releases where an instrumented van was used to measure methane concentrations during both fixed location sampling and during mobile traverses immediately downwind of the source. The measurements were used to evaluate the application of EPA Method 33A for estimating methane emissions downwind of a source and also to test the application of a new probabilistic approach for estimating emission rates from mobile traverse data.

  5. Accurate interlaminar stress recovery from finite element analysis

    NASA Technical Reports Server (NTRS)

    Tessler, Alexander; Riggs, H. Ronald

    1994-01-01

    The accuracy and robustness of a two-dimensional smoothing methodology is examined for the problem of recovering accurate interlaminar shear stress distributions in laminated composite and sandwich plates. The smoothing methodology is based on a variational formulation which combines discrete least-squares and penalty-constraint functionals in a single variational form. The smoothing analysis utilizes optimal strains computed at discrete locations in a finite element analysis. These discrete strain data are smoothed with a smoothing element discretization, producing superior accuracy strains and their first gradients. The approach enables the resulting smooth strain field to be practically C1-continuous throughout the domain of smoothing, exhibiting superconvergent properties of the smoothed quantity. The continuous strain gradients are also obtained directly from the solution. The recovered strain gradients are subsequently employed in the integration o equilibrium equations to obtain accurate interlaminar shear stresses. The problem is a simply-supported rectangular plate under a doubly sinusoidal load. The problem has an exact analytic solution which serves as a measure of goodness of the recovered interlaminar shear stresses. The method has the versatility of being applicable to the analysis of rather general and complex structures built of distinct components and materials, such as found in aircraft design. For these types of structures, the smoothing is achieved with 'patches', each patch covering the domain in which the smoothed quantity is physically continuous.

  6. Location Sensitive Deep Convolutional Neural Networks for Segmentation of White Matter Hyperintensities.

    PubMed

    Ghafoorian, Mohsen; Karssemeijer, Nico; Heskes, Tom; van Uden, Inge W M; Sanchez, Clara I; Litjens, Geert; de Leeuw, Frank-Erik; van Ginneken, Bram; Marchiori, Elena; Platel, Bram

    2017-07-11

    The anatomical location of imaging features is of crucial importance for accurate diagnosis in many medical tasks. Convolutional neural networks (CNN) have had huge successes in computer vision, but they lack the natural ability to incorporate the anatomical location in their decision making process, hindering success in some medical image analysis tasks. In this paper, to integrate the anatomical location information into the network, we propose several deep CNN architectures that consider multi-scale patches or take explicit location features while training. We apply and compare the proposed architectures for segmentation of white matter hyperintensities in brain MR images on a large dataset. As a result, we observe that the CNNs that incorporate location information substantially outperform a conventional segmentation method with handcrafted features as well as CNNs that do not integrate location information. On a test set of 50 scans, the best configuration of our networks obtained a Dice score of 0.792, compared to 0.805 for an independent human observer. Performance levels of the machine and the independent human observer were not statistically significantly different (p-value = 0.06).

  7. Source Population and Acceleration Location of Suprathermal Heavy Ions in Corotating Interaction Regions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Filwett, R. J.; Desai, M. I.; Dayeh, M. A.

    2017-03-20

    We have analyzed the ∼20–320 keV nucleon{sup −1} suprathermal (ST) heavy ion abundances in 41 corotating interaction regions (CIRs) observed by the Wind spacecraft from 1995 January to 2008 December. Our results are: (1) the CIR Fe/CNO and NeS/CNO ratios vary with the sunspot number, with values being closer to average solar energetic particle event values during solar maxima and lower than nominal solar wind values during solar minima. The physical mechanism responsible for the depleted abundances during solar minimum remains an open question. (2) The Fe/CNO increases with energy in the 6 events that occurred during solar maximum, whilemore » no such trends are observed for the 35 events during solar minimum. (3) The Fe/CNO shows no correlation with the average solar wind speed. (4) The Fe/CNO is well correlated with the corresponding upstream ∼20–320 keV nucleon{sup −1} Fe/CNO and not with the solar wind Fe/O measured by ACE in 31 events. Using the correlations between the upstream ∼20–40 keV nucleon{sup −1} Fe/CNO and the ∼20–320 keV nucleon{sup −1} Fe/CNO in CIRs, we estimate that, on average, the ST particles traveled ∼2 au along the nominal Parker spiral field line, which corresponds to upper limits for the radial distance of the source or acceleration location of ∼1 au beyond Earth orbit. Our results are consistent with those obtained from recent surveys, and confirm that CIR ST heavy ions are accelerated more locally, and are at odds with the traditional viewpoint that CIR ions seen at 1 au are bulk solar wind ions accelerated between 3 and 5 au.« less

  8. Microseismic imaging using a source function independent full waveform inversion method

    NASA Astrophysics Data System (ADS)

    Wang, Hanchen; Alkhalifah, Tariq

    2018-07-01

    At the heart of microseismic event measurements is the task to estimate the location of the source microseismic events, as well as their ignition times. The accuracy of locating the sources is highly dependent on the velocity model. On the other hand, the conventional microseismic source locating methods require, in many cases, manual picking of traveltime arrivals, which do not only lead to manual effort and human interaction, but also prone to errors. Using full waveform inversion (FWI) to locate and image microseismic events allows for an automatic process (free of picking) that utilizes the full wavefield. However, FWI of microseismic events faces incredible nonlinearity due to the unknown source locations (space) and functions (time). We developed a source function independent FWI of microseismic events to invert for the source image, source function and the velocity model. It is based on convolving reference traces with these observed and modelled to mitigate the effect of an unknown source ignition time. The adjoint-state method is used to derive the gradient for the source image, source function and velocity updates. The extended image for the source wavelet in Z axis is extracted to check the accuracy of the inverted source image and velocity model. Also, angle gathers are calculated to assess the quality of the long wavelength component of the velocity model. By inverting for the source image, source wavelet and the velocity model simultaneously, the proposed method produces good estimates of the source location, ignition time and the background velocity for synthetic examples used here, like those corresponding to the Marmousi model and the SEG/EAGE overthrust model.

  9. Error analysis in stereo vision for location measurement of 3D point

    NASA Astrophysics Data System (ADS)

    Li, Yunting; Zhang, Jun; Tian, Jinwen

    2015-12-01

    Location measurement of 3D point in stereo vision is subjected to different sources of uncertainty that propagate to the final result. For current methods of error analysis, most of them are based on ideal intersection model to calculate the uncertainty region of point location via intersecting two fields of view of pixel that may produce loose bounds. Besides, only a few of sources of error such as pixel error or camera position are taken into account in the process of analysis. In this paper we present a straightforward and available method to estimate the location error that is taken most of source of error into account. We summed up and simplified all the input errors to five parameters by rotation transformation. Then we use the fast algorithm of midpoint method to deduce the mathematical relationships between target point and the parameters. Thus, the expectations and covariance matrix of 3D point location would be obtained, which can constitute the uncertainty region of point location. Afterwards, we turned back to the error propagation of the primitive input errors in the stereo system and throughout the whole analysis process from primitive input errors to localization error. Our method has the same level of computational complexity as the state-of-the-art method. Finally, extensive experiments are performed to verify the performance of our methods.

  10. Military Service Records and Unit Histories: A Guide to Locating Sources

    DTIC Science & Technology

    2012-07-26

    records, therefoa- e , written authorization from the veta -an or ne.’Ct of kin is not rEqUired. However, in ordet" to protect the privacy of the...line E -mail: MPR.center@nara.gov Older military personnel records (generally prior to World War I, depending on the service branch) are located at...AFB, DC 20032-5000 E -mail: afhso.research@pentagon.af.mil http://www.afhso.af.mil/ (202) 404-2264 National Museum of the U.S. Air Force 1100

  11. Locating hydrothermal acoustic sources at Old Faithful Geyser using Matched Field Processing

    NASA Astrophysics Data System (ADS)

    Cros, E.; Roux, P.; Vandemeulebrouck, J.; Kedar, S.

    2011-10-01

    In 1992, a large and dense array of geophones was placed around the geyser vent of Old Faithful, in the Yellowstone National Park, to determine the origin of the seismic hydrothermal noise recorded at the surface of the geyser and to understand its dynamics. Old Faithful Geyser (OFG) is a small-scale hydrothermal system where a two-phase flow mixture erupts every 40 to 100 min in a high continuous vertical jet. Using Matched Field Processing (MFP) techniques on 10-min-long signal, we localize the source of the seismic pulses recorded at the surface of the geyser. Several MFP approaches are compared in this study, the frequency-incoherent and frequency-coherent approach, as well as the linear Bartlett processing and the non-linear Minimum Variance Distorsionless Response (MVDR) processing. The different MFP techniques used give the same source position with better focalization in the case of the MVDR processing. The retrieved source position corresponds to the geyser conduit at a depth of 12 m and the localization is in good agreement with in situ measurements made at Old Faithful in past studies.

  12. A Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) Determined from Phased Microphone Arrays

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Humphreys, William M.

    2006-01-01

    Current processing of acoustic array data is burdened with considerable uncertainty. This study reports an original methodology that serves to demystify array results, reduce misinterpretation, and accurately quantify position and strength of acoustic sources. Traditional array results represent noise sources that are convolved with array beamform response functions, which depend on array geometry, size (with respect to source position and distributions), and frequency. The Deconvolution Approach for the Mapping of Acoustic Sources (DAMAS) method removes beamforming characteristics from output presentations. A unique linear system of equations accounts for reciprocal influence at different locations over the array survey region. It makes no assumption beyond the traditional processing assumption of statistically independent noise sources. The full rank equations are solved with a new robust iterative method. DAMAS is quantitatively validated using archival data from a variety of prior high-lift airframe component noise studies, including flap edge/cove, trailing edge, leading edge, slat, and calibration sources. Presentations are explicit and straightforward, as the noise radiated from a region of interest is determined by simply summing the mean-squared values over that region. DAMAS can fully replace existing array processing and presentations methodology in most applications. It appears to dramatically increase the value of arrays to the field of experimental acoustics.

  13. Improved ultrasound transducer positioning by fetal heart location estimation during Doppler based heart rate measurements.

    PubMed

    Hamelmann, Paul; Vullings, Rik; Schmitt, Lars; Kolen, Alexander F; Mischi, Massimo; van Laar, Judith O E H; Bergmans, Jan W M

    2017-09-21

    Doppler ultrasound (US) is the most commonly applied method to measure the fetal heart rate (fHR). When the fetal heart is not properly located within the ultrasonic beam, fHR measurements often fail. As a consequence, clinical staff need to reposition the US transducer on the maternal abdomen, which can be a time consuming and tedious task. In this article, a method is presented to aid clinicians with the positioning of the US transducer to produce robust fHR measurements. A maximum likelihood estimation (MLE) algorithm is developed, which provides information on fetal heart location using the power of the Doppler signals received in the individual elements of a standard US transducer for fHR recordings. The performance of the algorithm is evaluated with simulations and in vitro experiments performed on a beating-heart setup. Both the experiments and the simulations show that the heart location can be accurately determined with an error of less than 7 mm within the measurement volume of the employed US transducer. The results show that the developed algorithm can be used to provide accurate feedback on fetal heart location for improved positioning of the US transducer, which may lead to improved measurements of the fHR.

  14. Error properties of Argos satellite telemetry locations using least squares and Kalman filtering.

    PubMed

    Boyd, Janice D; Brightsmith, Donald J

    2013-01-01

    Study of animal movements is key for understanding their ecology and facilitating their conservation. The Argos satellite system is a valuable tool for tracking species which move long distances, inhabit remote areas, and are otherwise difficult to track with traditional VHF telemetry and are not suitable for GPS systems. Previous research has raised doubts about the magnitude of position errors quoted by the satellite service provider CLS. In addition, no peer-reviewed publications have evaluated the usefulness of the CLS supplied error ellipses nor the accuracy of the new Kalman filtering (KF) processing method. Using transmitters hung from towers and trees in southeastern Peru, we show the Argos error ellipses generally contain <25% of the true locations and therefore do not adequately describe the true location errors. We also find that KF processing does not significantly increase location accuracy. The errors for both LS and KF processing methods were found to be lognormally distributed, which has important repercussions for error calculation, statistical analysis, and data interpretation. In brief, "good" positions (location codes 3, 2, 1, A) are accurate to about 2 km, while 0 and B locations are accurate to about 5-10 km. However, due to the lognormal distribution of the errors, larger outliers are to be expected in all location codes and need to be accounted for in the user's data processing. We evaluate five different empirical error estimates and find that 68% lognormal error ellipses provided the most useful error estimates. Longitude errors are larger than latitude errors by a factor of 2 to 3, supporting the use of elliptical error ellipses. Numerous studies over the past 15 years have also found fault with the CLS-claimed error estimates yet CLS has failed to correct their misleading information. We hope this will be reversed in the near future.

  15. A Robust Sound Source Localization Approach for Microphone Array with Model Errors

    NASA Astrophysics Data System (ADS)

    Xiao, Hua; Shao, Huai-Zong; Peng, Qi-Cong

    In this paper, a robust sound source localization approach is proposed. The approach retains good performance even when model errors exist. Compared with previous work in this field, the contributions of this paper are as follows. First, an improved broad-band and near-field array model is proposed. It takes array gain, phase perturbations into account and is based on the actual positions of the elements. It can be used in arbitrary planar geometry arrays. Second, a subspace model errors estimation algorithm and a Weighted 2-Dimension Multiple Signal Classification (W2D-MUSIC) algorithm are proposed. The subspace model errors estimation algorithm estimates unknown parameters of the array model, i. e., gain, phase perturbations, and positions of the elements, with high accuracy. The performance of this algorithm is improved with the increasing of SNR or number of snapshots. The W2D-MUSIC algorithm based on the improved array model is implemented to locate sound sources. These two algorithms compose the robust sound source approach. The more accurate steering vectors can be provided for further processing such as adaptive beamforming algorithm. Numerical examples confirm effectiveness of this proposed approach.

  16. Is GPS telemetry location error screening beneficial?

    USGS Publications Warehouse

    Ironside, Kirsten E.; Mattson, David J.; Arundel, Terry; Hansen, Jered R.

    2017-01-01

    The accuracy of global positioning system (GPS) locations obtained from study animals tagged with GPS monitoring devices has been a concern as to the degree it influences assessments of movement patterns, space use, and resource selection estimates. Many methods have been proposed for screening data to retain the most accurate positions for analysis, based on dilution of precision (DOP) measures, and whether the position is a two dimensional or three dimensional fix. Here we further explore the utility of these measures, by testing a Telonics GEN3 GPS collar's positional accuracy across a wide range of environmental conditions. We found the relationship between location error and fix dimension and DOP metrics extremely weak (r2adj ∼ 0.01) in our study area. Environmental factors such as topographic exposure, canopy cover, and vegetation height explained more of the variance (r2adj = 15.08%). Our field testing covered sites where sky-view was so limited it affected GPS performance to the degree fix attempts failed frequently (fix success rates ranged 0.00–100.00% over 67 sites). Screening data using PDOP did not effectively reduce the location error in the remaining dataset. Removing two dimensional fixes reduced the mean location error by 10.95 meters, but also resulted in a 54.50% data reduction. Therefore screening data under the range of conditions sampled here would reduce information on animal movement with minor improvements in accuracy and potentially introduce bias towards more open terrain and vegetation.

  17. Identification and location of catenary insulator in complex background based on machine vision

    NASA Astrophysics Data System (ADS)

    Yao, Xiaotong; Pan, Yingli; Liu, Li; Cheng, Xiao

    2018-04-01

    It is an important premise to locate insulator precisely for fault detection. Current location algorithms for insulator under catenary checking images are not accurate, a target recognition and localization method based on binocular vision combined with SURF features is proposed. First of all, because of the location of the insulator in complex environment, using SURF features to achieve the coarse positioning of target recognition; then Using binocular vision principle to calculate the 3D coordinates of the object which has been coarsely located, realization of target object recognition and fine location; Finally, Finally, the key is to preserve the 3D coordinate of the object's center of mass, transfer to the inspection robot to control the detection position of the robot. Experimental results demonstrate that the proposed method has better recognition efficiency and accuracy, can successfully identify the target and has a define application value.

  18. An Accurate Co-registration Method for Airborne Repeat-pass InSAR

    NASA Astrophysics Data System (ADS)

    Dong, X. T.; Zhao, Y. H.; Yue, X. J.; Han, C. M.

    2017-10-01

    Interferometric Synthetic Aperture Radar (InSAR) technology plays a significant role in topographic mapping and surface deformation detection. Comparing with spaceborne repeat-pass InSAR, airborne repeat-pass InSAR solves the problems of long revisit time and low-resolution images. Due to the advantages of flexible, accurate, and fast obtaining abundant information, airborne repeat-pass InSAR is significant in deformation monitoring of shallow ground. In order to getting precise ground elevation information and interferometric coherence of deformation monitoring from master and slave images, accurate co-registration must be promised. Because of side looking, repeat observing path and long baseline, there are very different initial slant ranges and flight heights between repeat flight paths. The differences of initial slant ranges and flight height lead to the pixels, located identical coordinates on master and slave images, correspond to different size of ground resolution cells. The mismatching phenomenon performs very obvious on the long slant range parts of master image and slave image. In order to resolving the different sizes of pixels and getting accurate co-registration results, a new method is proposed based on Range-Doppler (RD) imaging model. VV-Polarization C-band airborne repeat-pass InSAR images were used in experiment. The experiment result shows that the proposed method leads to superior co-registration accuracy.

  19. Acoustic localization of triggered lightning

    NASA Astrophysics Data System (ADS)

    Arechiga, Rene O.; Johnson, Jeffrey B.; Edens, Harald E.; Thomas, Ronald J.; Rison, William

    2011-05-01

    We use acoustic (3.3-500 Hz) arrays to locate local (<20 km) thunder produced by triggered lightning in the Magdalena Mountains of central New Mexico. The locations of the thunder sources are determined by the array back azimuth and the elapsed time since discharge of the lightning flash. We compare the acoustic source locations with those obtained by the Lightning Mapping Array (LMA) from Langmuir Laboratory, which is capable of accurately locating the lightning channels. To estimate the location accuracy of the acoustic array we performed Monte Carlo simulations and measured the distance (nearest neighbors) between acoustic and LMA sources. For close sources (<5 km) the mean nearest-neighbors distance was 185 m compared to 100 m predicted by the Monte Carlo analysis. For far distances (>6 km) the error increases to 800 m for the nearest neighbors and 650 m for the Monte Carlo analysis. This work shows that thunder sources can be accurately located using acoustic signals.

  20. Large arterial occlusive strokes as a medical emergency: need to accurately predict clot location.

    PubMed

    Vanacker, Peter; Faouzi, Mohamed; Eskandari, Ashraf; Maeder, Philippe; Meuli, Reto; Michel, Patrik

    2017-10-01

    Endovascular treatment for acute ischemic stroke with a large intracranial occlusion was recently shown to be effective. Timely knowledge of the presence, site, and extent of arterial occlusions in the ischemic territory has the potential to influence patient selection for endovascular treatment. We aimed to find predictors of large vessel occlusive strokes, on the basis of available demographic, clinical, radiological, and laboratory data in the emergency setting. Patients enrolled in ASTRAL registry with acute ischemic stroke and computed tomography (CT)-angiography within 12 h of stroke onset were selected and categorized according to occlusion site. Easily accessible variables were used in a multivariate analysis. Of 1645 patients enrolled, a significant proportion (46.2%) had a large vessel occlusion in the ischemic territory. The main clinical predictors of any arterial occlusion were in-hospital stroke [odd ratios (OR) 2.1, 95% confidence interval 1.4-3.1], higher initial National Institute of Health Stroke Scale (OR 1.1, 1.1-1.2), presence of visual field defects (OR 1.9, 1.3-2.6), dysarthria (OR 1.4, 1.0-1.9), or hemineglect (OR 2.0, 1.4-2.8) at admission and atrial fibrillation (OR 1.7, 1.2-2.3). Further, the following radiological predictors were identified: time-to-imaging (OR 0.9, 0.9-1.0), early ischemic changes (OR 2.3, 1.7-3.2), and silent lesions on CT (OR 0.7, 0.5-1.0). The area under curve for this analysis was 0.85. Looking at different occlusion sites, National Institute of Health Stroke Scale and early ischemic changes on CT were independent predictors in all subgroups. Neurological deficits, stroke risk factors, and CT findings accurately identify acute ischemic stroke patients at risk of symptomatic vessel occlusion. Predicting the presence of these occlusions may impact emergency stroke care in regions with limited access to noninvasive vascular imaging.

  1. Investigation of Finite Sources through Time Reversal

    NASA Astrophysics Data System (ADS)

    Kremers, S.; Brietzke, G.; Igel, H.; Larmat, C.; Fichtner, A.; Johnson, P. A.; Huang, L.

    2008-12-01

    Under certain conditions time reversal is a promising method to determine earthquake source characteristics without any a-priori information (except the earth model and the data). It consists of injecting flipped-in-time records from seismic stations within the model to create an approximate reverse movie of wave propagation from which the location of the source point and other information might be inferred. In this study, the backward propagation is performed numerically using a spectral element code. We investigate the potential of time reversal to recover finite source characteristics (e.g., size of ruptured area, location of asperities, rupture velocity etc.). We use synthetic data from the SPICE kinematic source inversion blind test initiated to investigate the performance of current kinematic source inversion approaches (http://www.spice- rtn.org/library/valid). The synthetic data set attempts to reproduce the 2000 Tottori earthquake with 33 records close to the fault. We discuss the influence of relaxing the ignorance to prior source information (e.g., origin time, hypocenter, fault location, etc.) on the results of the time reversal process.

  2. First LOCSMITH locations of deep moonquakes

    NASA Astrophysics Data System (ADS)

    Hempel, S.; Knapmeyer, M.; Sens-Schönfelder, C.; Oberst, J.

    2008-09-01

    Introduction Several thousand seismic events were recorded by the Apollo seismic network from 19691977. Different types of events can be distinguished: meteoroid impacts, thermal quakes and internally caused moonquakes. The latter subdivide into shallow (100 to 300km) and deep moonquakes (700 to 1100km), which are by far the most common events. The deep quakes would be no immediate danger to inhabitated stations on the Earth's Moon because of their relatively low magnitude and great depth. However, they bear important information on lunar structure and evolution, and their distribution probably reflects their source mechanism. In this study, we reinvestigate location patterns of deep lunar quakes. LOCSMITH The core of this study is a new location method (LOCSMITH, [1]). This algorithm uses time intervals rather than time instants as input, which contain the dedicated arrival with probability 1. LOCSMITH models and compares theoretical and actual travel times on a global scale and uses an adaptive grid to search source locations compatible with all observations. The output is a set of all possible hypocenters for the considered region of repeating, tidally triggered moonquake activity, called clusters. The shape and size of these sets gives a better estimate of the location uncertainty than the formal standard deviations returned by classical methods. This is used for grading of deep moonquake clusters according to the currently available data quality. Classification of deep moonquakes As first step, we establish a reciprocal dependence of size and shape of LOCSMITH location clouds on number of arrivals. Four different shapes are recognized, listed here in an order corresponding to decreasing spatial resolution: 1. "Balls", which are well defined and relatively small types of sets resembling the commonly assumed error ellipsoid. These are found in the best cases with many observations. Locations in this shape are obtained for clusters 1, 18 or 33, these were already

  3. Source-receptor probability of atmospheric long-distance dispersal of viruses to Israel from the eastern Mediterranean area.

    PubMed

    Klausner, Z; Klement, E; Fattal, E

    2018-02-01

    Viruses that affect the health of humans and farm animals can spread over long distances via atmospheric mechanisms. The phenomenon of atmospheric long-distance dispersal (LDD) is associated with severe consequences because it may introduce pathogens into new areas. The introduction of new pathogens to Israel was attributed to LDD events numerous times. This provided the motivation for this study which is aimed to identify all the locations in the eastern Mediterranean that may serve as sources for pathogen incursion into Israel via LDD. This aim was achieved by calculating source-receptor relationship probability maps. These maps describe the probability that an infected vector or viral aerosol, once airborne, will have an atmospheric route that can transport it to a distant location. The resultant probability maps demonstrate a seasonal tendency in the probability of specific areas to serve as sources for pathogen LDD into Israel. Specifically, Cyprus' season is the summer; southern Turkey and the Greek islands of Crete, Karpathos and Rhodes are associated with spring and summer; lower Egypt and Jordan may serve as sources all year round, except the summer months. The method used in this study can easily be implemented to any other geographic region. The importance of this study is the ability to provide a climatologically valid and accurate risk assessment tool to support long-term decisions regarding preparatory actions for future outbreaks long before a specific outbreak occurs. © 2017 Blackwell Verlag GmbH.

  4. Onshore industrial wind turbine locations for the United States

    USGS Publications Warehouse

    Diffendorfer, Jay E.; Compton, Roger; Kramer, Louisa; Ancona, Zach; Norton, Donna

    2017-01-01

    This dataset provides industrial-scale onshore wind turbine locations in the United States, corresponding facility information, and turbine technical specifications. The database has wind turbine records that have been collected, digitized, locationally verified, and internally quality controlled. Turbines from the Federal Aviation Administration Digital Obstacles File, through product release date July 22, 2013, were used as the primary source of turbine data points. The dataset was subsequently revised and reposted as described in the revision histories for the report. Verification of the turbine positions was done by visual interpretation using high-resolution aerial imagery in Environmental Systems Research Institute (Esri) ArcGIS Desktop. Turbines without Federal Aviation Administration Obstacles Repository System numbers were visually identified and point locations were added to the collection. We estimated a locational error of plus or minus 10 meters for turbine locations. Wind farm facility names were identified from publicly available facility datasets. Facility names were then used in a Web search of additional industry publications and press releases to attribute additional turbine information (such as manufacturer, model, and technical specifications of wind turbines). Wind farm facility location data from various wind and energy industry sources were used to search for and digitize turbines not in existing databases. Technical specifications for turbines were assigned based on the wind turbine make and model as described in literature, specifications listed in the Federal Aviation Administration Digital Obstacles File, and information on the turbine manufacturer’s Web site. Some facility and turbine information on make and model did not exist or was difficult to obtain. Thus, uncertainty may exist for certain turbine specifications. That uncertainty was rated and a confidence was recorded for both location and attribution data quality.

  5. 46 CFR 108.421 - Location of fire pumps and associated equipment.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Location of fire pumps and associated equipment. 108.421... pumps and associated equipment. Each fire pump required by § 108.415, and the source of power, controls, sea connections for the fire pump, and booster pumps, if installed, must be installed in locations...

  6. Engineering assessment of low-level liquid waste disposal caisson locations at the 618-11 Burial Grounds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Phillips, S.J.; Fischer, D.D.; Crawford, R.C.

    1982-06-01

    Rockwell Hanford Operations is currently involved in an extensive effort to perform interim ground surface stabilization activities at retired low-level waste burial grounds located at the Hanford Site, Richland, Washington. The principal objective of these activities is to promote increased occupational and radiological safety at burial grounds. Interim stabilization activities include: (1) load testing (traversing burial ground surfaces with heavy equipment to promote incipient collapse of void spaces within the disposal structure and overburden), (2) barrier placement (placement of a {ge} 0.6 m soil barrier over existing overburden), and (3) revegetation (establishment of shallow rooted vegetation on the barrier tomore » mitigate deep rooted plant growth and to reduce erosion). Low-level waste disposal caissons were used in 300 Area Burial Grounds as internment structures for containerized liquid wastes. These caissons, by virtue of their contents, design and methods of closure, require long-term performance evaluation. As an initial activity to evaluate long-term performance, the accurate location of these structures is required. This topical report summarizes engineering activities used to locate caissons in the subsurface environment at the Burial Ground. Activities were conducted to locate caissons during surface stabilization activities. The surface locations were marked, photographed, and recorded on an as built engineering drawing. The recorded location of these caissons will augment long-term observations of confinement structure and engineered surface barrier performance. In addition, accurate caisson location will minimize occupational risk during monitoring and observation activities periodically conducted at the burial ground.« less

  7. Location, Location, Location!

    ERIC Educational Resources Information Center

    Ramsdell, Kristin

    2004-01-01

    Of prime importance in real estate, location is also a key element in the appeal of romances. Popular geographic settings and historical periods sell, unpopular ones do not--not always with a logical explanation, as the author discovered when she conducted a survey on this topic last year. (Why, for example, are the French Revolution and the…

  8. Wave field synthesis of a virtual source located in proximity to a loudspeaker array.

    PubMed

    Lee, Jung-Min; Choi, Jung-Woo; Kim, Yang-Hann

    2013-09-01

    For the derivation of 2.5-dimensional operator in wave field synthesis, a virtual source is assumed to be positioned far from a loudspeaker array. However, such far-field approximation inevitably results in a reproduction error when the virtual source is placed adjacent to an array. In this paper, a method is proposed to generate a virtual source close to and behind a continuous line array of loudspeakers. A driving function is derived by reducing a surface integral (Rayleigh integral) to a line integral based on the near-field assumption. The solution is then combined with the far-field formula of wave field synthesis by introducing a weighting function that can adjust the near- and far-field contribution of each driving function. This enables production of a virtual source anywhere in relation to the array. Simulations show the proposed method can reduce the reproduction error to below -18 dB, regardless of the virtual source position.

  9. SU-E-T-284: Revisiting Reference Dosimetry for the Model S700 Axxent 50 KV{sub p} Electronic Brachytherapy Source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hiatt, JR; Rivard, MJ

    2014-06-01

    Purpose: The model S700 Axxent electronic brachytherapy source by Xoft was characterized in 2006 by Rivard et al. The source design was modified in 2006 to include a plastic centering insert at the source tip to more accurately position the anode. The objectives of the current study were to establish an accurate Monte Carlo source model for simulation purposes, to dosimetrically characterize the new source and obtain its TG-43 brachytherapy dosimetry parameters, and to determine dose differences between the source with and without the centering insert. Methods: Design information from dissected sources and vendor-supplied CAD drawings were used to devisemore » the source model for radiation transport simulations of dose distributions in a water phantom. Collision kerma was estimated as a function of radial distance, r, and polar angle, θ, for determination of reference TG-43 dosimetry parameters. Simulations were run for 10{sup 10} histories, resulting in statistical uncertainties on the transverse plane of 0.03% at r=1 cm and 0.08% at r=10 cm. Results: The dose rate distribution the transverse plane did not change beyond 2% between the 2006 model and the current study. While differences exceeding 15% were observed near the source distal tip, these diminished to within 2% for r>1.5 cm. Differences exceeding a factor of two were observed near θ=150° and in contact with the source, but diminished to within 20% at r=10 cm. Conclusions: Changes in source design influenced the overall dose rate and distribution by more than 2% over a third of the available solid angle external from the source. For clinical applications using balloons or applicators with tissue located within 5 cm from the source, dose differences exceeding 2% were observed only for θ>110°. This study carefully examined the current source geometry and presents a modern reference TG-43 dosimetry dataset for the model S700 source.« less

  10. Modelling the Source of Blasting for the Numerical Simulation of Blast-Induced Ground Vibrations: A Review

    NASA Astrophysics Data System (ADS)

    Ainalis, Daniel; Kaufmann, Olivier; Tshibangu, Jean-Pierre; Verlinden, Olivier; Kouroussis, Georges

    2017-01-01

    The mining and construction industries have long been faced with considerable attention and criticism in regard to the effects of blasting. The generation of ground vibrations is one of the most significant factors associated with blasting and is becoming increasingly important as mining sites are now regularly located near urban areas. This is of concern to not only the operators of the mine but also residents. Mining sites are subjected to an inevitable compromise: a production blast is designed to fragment the utmost amount of rock possible; however, any increase in the blast can generate ground vibrations which can propagate great distances and cause structural damage or discomfort to residents in surrounding urban areas. To accurately predict the propagation of ground vibrations near these sensitive areas, the blasting process and surrounding environment must be characterised and understood. As an initial step, an accurate model of the source of blast-induced vibrations is required. This paper presents a comprehensive review of the approaches to model the blasting source in order to critically evaluate developments in the field. An overview of the blasting process and description of the various factors which influence the blast performance and subsequent ground vibrations are also presented. Several approaches to analytically model explosives are discussed. Ground vibration prediction methods focused on seed waveform and charge weight scaling techniques are presented. Finally, numerical simulations of the blasting source are discussed, including methods to estimate blasthole wall pressure time-history, and hydrodynamic codes.

  11. Prerequisites for Accurate Monitoring of River Discharge Based on Fixed-Location Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Kästner, K.; Hoitink, A. J. F.; Torfs, P. J. J. F.; Vermeulen, B.; Ningsih, N. S.; Pramulya, M.

    2018-02-01

    River discharge has to be monitored reliably for effective water management. As river discharge cannot be measured directly, it is usually inferred from the water level. This practice is unreliable at places where the relation between water level and flow velocity is ambiguous. In such a case, the continuous measurement of the flow velocity can improve the discharge prediction. The emergence of horizontal acoustic Doppler current profilers (HADCPs) has made it possible to continuously measure the flow velocity. However, the profiling range of HADCPs is limited, so that a single instrument can only partially cover a wide cross section. The total discharge still has to be determined with a model. While the limitations of rating curves are well understood, there is not yet a comprehensive theory to assess the accuracy of discharge predicted from velocity measurements. Such a theory is necessary to discriminate which factors influence the measurements, and to improve instrument deployment as well as discharge prediction. This paper presents a generic method to assess the uncertainty of discharge predicted from range-limited velocity profiles. The theory shows that a major source of error is the variation of the ratio between the local and cross-section-averaged velocity. This variation is large near the banks, where HADCPs are usually deployed and can limit the advantage gained from the velocity measurement. We apply our theory at two gauging stations situated in the Kapuas River, Indonesia. We find that at one of the two stations the index velocity does not outperform a simple rating curve.

  12. Source apportionment of hydrocarbons measured in the Eagle Ford shale

    NASA Astrophysics Data System (ADS)

    Roest, G. S.; Schade, G. W.

    2016-12-01

    The rapid development of unconventional oil and gas in the US has led to hydrocarbon emissions that are yet to be accurately quantified. Emissions from the Eagle Ford Shale in southern Texas, one of the most productive shale plays in the U.S., have received little attention due to a sparse air quality monitoring network, thereby limiting studies of air quality within the region. We use hourly atmospheric hydrocarbon and meteorological data from three locations in the Eagle Ford Shale to assess their sources. Data are available from the Texas commission of environmental quality (TCEQ) air quality monitors in Floresville, a small town southeast of San Antonio and just north of the shale area; and Karnes city, a midsize rural city in the center of the shale. Our own measurements were carried out at a private ranch in rural Dimmit County in southern Texas from April to November of 2015. Air quality monitor data from the TCEQ were selected for the same time period. Non-negative matrix factorization in R (package NMF) was used to determine likely sources and their contributions above background. While the TCEQ monitor data consisted mostly of hydrocarbons, our own data include both CO, CO2, O3, and NOx. We find that rural Dimmit County hydrocarbons are dominated by oil and gas development sources, while central shale hydrocarbons at the TCEQ monitoring sites have a mix of sources including car traffic. However, oil and gas sources also dominate hydrocarbons at Floresville and Karnes City. Toxic benzene is nearly exclusively due to oil and gas development sources, including flaring, which NMF identifies as a major hydrocarbon source in Karnes City. Other major sources include emissions of light weight alkanes (C2-C5) from raw natural gas emissions and a larger set of alkanes (C2-C10) from oil sources, including liquid storage tanks.

  13. Lightning location system supervising Swedish power transmission network

    NASA Technical Reports Server (NTRS)

    Melin, Stefan A.

    1991-01-01

    For electric utilities, the ability to prevent or minimize lightning damage on personnel and power systems is of great importance. Therefore, the Swedish State Power Board, has been using data since 1983 from a nationwide lightning location system (LLS) for accurately locating lightning ground strikes. Lightning data is distributed and presented on color graphic displays at regional power network control centers as well as at the national power system control center for optimal data use. The main objectives for use of LLS data are: supervising the power system for optimal and safe use of the transmission and generating capacity during periods of thunderstorms; warning service to maintenance and service crews at power line and substations to end operations hazardous when lightning; rapid positioning of emergency crews to locate network damage at areas of detected lightning; and post analysis of power outages and transmission faults in relation to lightning, using archived lightning data for determination of appropriate design and insulation levels of equipment. Staff have found LLS data useful and economically justified since the availability of power system has increased as well as level of personnel safety.

  14. Vehicular sources in acoustic propagation experiments

    NASA Technical Reports Server (NTRS)

    Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

    1990-01-01

    One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

  15. Vehicular sources in acoustic propagation experiments

    NASA Astrophysics Data System (ADS)

    Prado, Gervasio; Fitzgerald, James; Arruda, Anthony; Parides, George

    1990-12-01

    One of the most important uses of acoustic propagation models lies in the area of detection and tracking of vehicles. Propagation models are used to compute transmission losses in performance prediction models and to analyze the results of past experiments. Vehicles can also provide the means for cost effective experiments to measure acoustic propagation conditions over significant ranges. In order to properly correlate the information provided by the experimental data and the propagation models, the following issues must be taken into consideration: the phenomenology of the vehicle noise sources must be understood and characterized; the vehicle's location or 'ground truth' must be accurately reproduced and synchronized with the acoustic data; and sufficient meteorological data must be collected to support the requirements of the propagation models. The experimental procedures and instrumentation needed to carry out propagation experiments are discussed. Illustrative results are presented for two cases. First, a helicopter was used to measure propagation losses at a range of 1 to 10 Km. Second, a heavy diesel-powered vehicle was used to measure propagation losses in the 300 to 2200 m range.

  16. Accounting for location and timing in NO{sub x} emission trading programs. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nichols, A.L.

    1997-12-01

    This report describes approaches to designing emission trading programs for nitrogen oxides (NO{sub x}) to account for the locations of emission sources. When a trading region is relatively small, program managers can assume that the location of the sources engaging in trades has little or no effect. However, if policy makers extend the program to larger regions, this assumption may be questioned. Therefore, EPRI has undertaken a survey of methods for incorporating location considerations into trading programs. Application of the best method may help to preserve, and even enhance, the flexibility and savings afforded utilities by emission trading.

  17. Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

    NASA Technical Reports Server (NTRS)

    Alter, Stephen J.; Brauckmann, Gregory J.; Kleb, Bil; Streett, Craig L; Glass, Christopher E.; Schuster, David M.

    2015-01-01

    Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads.

  18. On concentrated solute sources in faulted aquifers

    NASA Astrophysics Data System (ADS)

    Robinson, N. I.; Werner, A. D.

    2017-06-01

    Finite aperture faults and fractures within aquifers (collectively called 'faults' hereafter) theoretically enable flowing water to move through them but with refractive displacement, both on entry and exit. When a 2D or 3D point source of solute concentration is located upstream of the fault, the plume emanating from the source relative to one in a fault-free aquifer is affected by the fault, both before it and after it. Previous attempts to analyze this situation using numerical methods faced challenges in overcoming computational constraints that accompany requisite fine mesh resolutions. To address these, an analytical solution of this problem is developed and interrogated using statistical evaluation of solute distributions. The method of solution is based on novel spatial integral representations of the source with axes rotated from the direction of uniform water flow and aligning with fault faces and normals. Numerical exemplification is given to the case of a 2D steady state source, using various parameter combinations. Statistical attributes of solute plumes show the relative impact of parameters, the most important being, fault rotation, aperture and conductivity ratio. New general observations of fault-affected solution plumes are offered, including: (a) the plume's mode (i.e. peak concentration) on the downstream face of the fault is less displaced than the refracted groundwater flowline, but at some distance downstream of the fault, these realign; (b) porosities have no influence in steady state calculations; (c) previous numerical modeling results of barrier faults show significant boundary effects. The current solution adds to available benchmark problems involving fractures, faults and layered aquifers, in which grid resolution effects are often barriers to accurate simulation.

  19. Optimizing the real-time automatic location of the events produced in Romania using an advanced processing system

    NASA Astrophysics Data System (ADS)

    Neagoe, Cristian; Grecu, Bogdan; Manea, Liviu

    2016-04-01

    National Institute for Earth Physics (NIEP) operates a real time seismic network which is designed to monitor the seismic activity on the Romanian territory, which is dominated by the intermediate earthquakes (60-200 km) from Vrancea area. The ability to reduce the impact of earthquakes on society depends on the existence of a large number of high-quality observational data. The development of the network in recent years and an advanced seismic acquisition are crucial to achieving this objective. The software package used to perform the automatic real-time locations is Seiscomp3. An accurate choice of the Seiscomp3 setting parameters is necessary to ensure the best performance of the real-time system i.e., the most accurate location for the earthquakes and avoiding any false events. The aim of this study is to optimize the algorithms of the real-time system that detect and locate the earthquakes in the monitored area. This goal is pursued by testing different parameters (e.g., STA/LTA, filters applied to the waveforms) on a data set of representative earthquakes of the local seismicity. The results are compared with the locations from the Romanian Catalogue ROMPLUS.

  20. Transfer of location-specific control to untrained locations.

    PubMed

    Weidler, Blaire J; Bugg, Julie M

    2016-11-01

    Recent research highlights a seemingly flexible and automatic form of cognitive control that is triggered by potent contextual cues, as exemplified by the location-specific proportion congruence effect--reduced compatibility effects in locations associated with a high as compared to low likelihood of conflict. We investigated just how flexible location-specific control is by examining whether novel locations effectively cue control for congruency-unbiased stimuli. In two experiments, biased (mostly compatible or mostly incompatible) training stimuli appeared in distinct locations. During a final block, unbiased (50% compatible) stimuli appeared in novel untrained locations spatially linked to biased locations. The flanker compatibly effect was reduced for unbiased stimuli in novel locations linked to a mostly incompatible compared to a mostly compatible location, indicating transfer. Transfer was observed when stimuli appeared along a linear function (Experiment 1) or in rings of a bullseye (Experiment 2). The novel transfer effects imply that location-specific control is more flexible than previously reported and further counter the complex stimulus-response learning account of location-specific proportion congruence effects. We propose that the representation and retrieval of control settings in untrained locations may depend on environmental support and the presentation of stimuli in novel locations that fall within the same categories of space as trained locations.