Tohyama, Mikio
2015-01-01
What is this sound? What does that sound indicate? These are two questions frequently heard in daily conversation. Sound results from the vibrations of elastic media and in daily life provides informative signals of events happening in the surrounding environment. In interpreting auditory sensations, the human ear seems particularly good at extracting the signal signatures from sound waves. Although exploring auditory processing schemes may be beyond our capabilities, source signature analysis is a very attractive area in which signal-processing schemes can be developed using mathematical expressions. This book is inspired by such processing schemes and is oriented to signature analysis of waveforms. Most of the examples in the book are taken from data of sound and vibrations; however, the methods and theories are mostly formulated using mathematical expressions rather than by acoustical interpretation. This book might therefore be attractive and informative for scientists, engineers, researchers, and graduat...
Statement for Doppler waveforms analysis.
Mahé, Guillaume; Boulon, Carine; Desormais, Ileana; Lacroix, Philippe; Bressollette, Luc; Guilmot, Jean-Louis; Le Hello, Claire; Sevestre, Marie-Antoinette; Pernod, Gilles; Constans, Joel; Boissier, Christian; Bura-Rivière, Alessandra
2017-08-01
Peripheral artery disease of the lower limbs (PAD) is a common disease. Evaluation of PAD is primarily based on non-invasive examinations with analysis of the arterial Doppler signal being a key element. However, the description of arterial Doppler waveforms morphologies varies considerably across medical schools and from country to country. In order to overcome this issue, the French College of Teachers for Vascular Medicine (Collège des Enseignants de Médecine Vasculaire; CEMV) has summarised the published data on Doppler waveforms analysis and proposes a new "Saint-Bonnet" classification system to describe Doppler waveforms morphologies. The simplified Saint-Bonnet classification comprises eight types and allows taking into account if the Doppler signal does not revert to baseline. This classification, which is based on previous classifications, could improve the descriptions of both physiological and pathological waveforms, recorded in lower limb arteries. According to the reviewed literature, recommendations about the use of Doppler waveforms are proposed. This statement is a preamble to reach an international consensus on the subject, which would standardize the description of arterial waveforms and improve the management of PAD patients.
Electronics via waveform analysis
Craig, Edwin C
1993-01-01
The author believes that a good basic understanding of electronics can be achieved by detailed visual analyses of the actual voltage waveforms present in selected circuits. The voltage waveforms included in this text were photographed using a 35-rrun camera in an attempt to make the book more attractive. This book is intended for the use of students with a variety of backgrounds. For this reason considerable material has been placed in the Appendix for those students who find it useful. The Appendix includes many basic electricity and electronic concepts as well as mathematical derivations that are not vital to the understanding of the circuit being discussed in the text at that time. Also some derivations might be so long that, if included in the text, it could affect the concentration of the student on the circuit being studied. The author has tried to make the book comprehensive enough so that a student could use it as a self-study course, providing one has access to adequate laboratory equipment.
Multi-waveform classification for seismic facies analysis
Song, Chengyun; Liu, Zhining; Wang, Yaojun; Li, Xingming; Hu, Guangmin
2017-04-01
Seismic facies analysis provides an effective way to delineate the heterogeneity and compartments within a reservoir. Traditional method is using the single waveform to classify the seismic facies, which does not consider the stratigraphy continuity, and the final facies map may affect by noise. Therefore, by defining waveforms in a 3D window as multi-waveform, we developed a new seismic facies analysis algorithm represented as multi-waveform classification (MWFC) that combines the multilinear subspace learning with self-organizing map (SOM) clustering techniques. In addition, we utilize multi-window dip search algorithm to extract multi-waveform, which reduce the uncertainty of facies maps in the boundaries. Testing the proposed method on synthetic data with different S/N, we confirm that our MWFC approach is more robust to noise than the conventional waveform classification (WFC) method. The real seismic data application on F3 block in Netherlands proves our approach is an effective tool for seismic facies analysis.
Automated Analysis, Classification, and Display of Waveforms
Kwan, Chiman; Xu, Roger; Mayhew, David; Zhang, Frank; Zide, Alan; Bonggren, Jeff
2004-01-01
A computer program partly automates the analysis, classification, and display of waveforms represented by digital samples. In the original application for which the program was developed, the raw waveform data to be analyzed by the program are acquired from space-shuttle auxiliary power units (APUs) at a sampling rate of 100 Hz. The program could also be modified for application to other waveforms -- for example, electrocardiograms. The program begins by performing principal-component analysis (PCA) of 50 normal-mode APU waveforms. Each waveform is segmented. A covariance matrix is formed by use of the segmented waveforms. Three eigenvectors corresponding to three principal components are calculated. To generate features, each waveform is then projected onto the eigenvectors. These features are displayed on a three-dimensional diagram, facilitating the visualization of the trend of APU operations.
Fast and efficient evaluation of gravitational waveforms via reduced-order spline interpolation
Galley, Chad R
2016-01-01
Numerical simulations of merging black hole binaries produce the most accurate gravitational waveforms. The availability of hundreds of these numerical relativity (NR) waveforms, often containing many higher spherical harmonic modes, allows one to study many aspects of gravitational waves. Amongst these are the response of data analysis pipelines, the calibration of semi-analytical models, the building of reduced-order surrogates, the estimation of the parameters of detected gravitational waves, and the composition of public catalogs of NR waveform data. The large number of generated NR waveforms consequently requires efficient data storage and handling, especially since many more waveforms will be generated at an increased rate in the forthcoming years. In addition, gravitational wave data analyses often require the NR waveforms to be interpolated and uniformly resampled at high sampling rates. Previously, this resulted in very large data files (up to $\\sim$ several GB) in memory-intensive operations, which ...
ANALYSIS AND APPLICATION OF LIDAR WAVEFORM DATA USING A PROGRESSIVE WAVEFORM DECOMPOSITION METHOD
Directory of Open Access Journals (Sweden)
J. Zhu
2012-09-01
Full Text Available Due to rich information of a full waveform of airborne LiDAR (light detection and ranging data, the analysis of full waveform has been an active area in LiDAR application. It is possible to digitally sample and store the entire reflected waveform of small-footprint instead of only discrete point clouds. Decomposition of waveform data, a key step in waveform data analysis, can be categorized to two typical methods: 1 the Gaussian modelling method such as the Non-linear least-squares (NLS algorithm and the maximum likelihood estimation using the Exception Maximization (EM algorithm. 2 pulse detection method—Average Square Difference Function (ASDF. However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform. In this paper, we proposed a fast algorithm—Progressive Waveform Decomposition (PWD method to extract local maxims and fit the echo with Gaussian function, and calculate other parameters from the raw waveform data. On the one hand, experiments are implemented to evaluate the PWD method and the results demonstrate its robustness and efficiency. On the other hand, with the PWD parametric analysis of the full-waveform instead of a 3D point cloud, some special applications are investigated afterward.
Waveform fitting and geometry analysis for full-waveform lidar feature extraction
Tsai, Fuan; Lai, Jhe-Syuan; Cheng, Yi-Hsiu
2016-10-01
This paper presents a systematic approach that integrates spline curve fitting and geometry analysis to extract full-waveform LiDAR features for land-cover classification. The cubic smoothing spline algorithm is used to fit the waveform curve of the received LiDAR signals. After that, the local peak locations of the waveform curve are detected using a second derivative method. According to the detected local peak locations, commonly used full-waveform features such as full width at half maximum (FWHM) and amplitude can then be obtained. In addition, the number of peaks, time difference between the first and last peaks, and the average amplitude are also considered as features of LiDAR waveforms with multiple returns. Based on the waveform geometry, dynamic time-warping (DTW) is applied to measure the waveform similarity. The sum of the absolute amplitude differences that remain after time-warping can be used as a similarity feature in a classification procedure. An airborne full-waveform LiDAR data set was used to test the performance of the developed feature extraction method for land-cover classification. Experimental results indicate that the developed spline curve- fitting algorithm and geometry analysis can extract helpful full-waveform LiDAR features to produce better land-cover classification than conventional LiDAR data and feature extraction methods. In particular, the multiple-return features and the dynamic time-warping index can improve the classification results significantly.
Lane marking detection based on waveform analysis and CNN
Ye, Yang Yang; Chen, Hou Jin; Hao, Xiao Li
2017-06-01
Lane markings detection is a very important part of the ADAS to avoid traffic accidents. In order to obtain accurate lane markings, in this work, a novel and efficient algorithm is proposed, which analyses the waveform generated from the road image after inverse perspective mapping (IPM). The algorithm includes two main stages: the first stage uses an image preprocessing including a CNN to reduce the background and enhance the lane markings. The second stage obtains the waveform of the road image and analyzes the waveform to get lanes. The contribution of this work is that we introduce local and global features of the waveform to detect the lane markings. The results indicate the proposed method is robust in detecting and fitting the lane markings.
Analysis of Gradient Waveform in Magnetic Resonance Imaging
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OU-YANG Shan-mei
2017-12-01
Full Text Available The accuracy of gradient pulse waveform affects image quality significantly in magnetic resonance imaging (MRI. Recording and analyzing the waveform of gradient pulse helps to make rapid and accurate diagnosis of spectrometer gradient hardware and/or pulse sequence. Using the virtual instrument software LabVIEW to control the high speed data acquisition card DAQ-2005, a multi-channel acquisition scheme was designed to collect the gradient outputs from a custom-made spectrometer. The collected waveforms were post-processed (i.e., histogram statistical analysis, data filtering and difference calculation to obtain feature points containing time and amplitude information. Experiments were carried out to validate the method, which is an auxiliary test method for the development of spectrometer and pulses sequence.
Analysis of acoustic emission waveforms from fatigue cracks
Bhuiyan, Md. Yeasin; Bao, Jingjing; Poddar, Banibrata; Giurgiutiu, Victor
2017-04-01
Acoustic emission (AE) monitoring technique is a well-known approach in the field of NDE/SHM. AE monitoring from the defect formation and failure in the materials were well studied by the researchers. However, conventional AE monitoring techniques are predominantly based on statistical analysis. In this study we focus on understanding the AE waveforms from the fatigue crack growth using physics based approach. The growth of the fatigue crack causes the acoustic emission in the material that propagates in the structure. One of the main challenges of this approach is to develop the physics based understanding of the AE source itself. The acoustic emission happens not only from the crack growth but also from the interaction of the crack lips during fatigue loading of the materials. As the waveforms are generated from the AE event, they propagate and create local vibration modes along the crack faces. Fatigue experiments were performed to generate the fatigue cracks. Several test specimens were used in the fatigue experiments and corresponding AE waveforms were captured. The AE waveforms were analyzed and distinguished into different groups based on the similar nature on both time domain and frequency domain. The experimental results are explained based on the physical observation of the specimen.
The 1930 Irpinia earthquake: collection and analysis of historical waveforms
Ferrari, G.; Megna, A.; Nardi, A.; Palombo, B.; Perniola, B.; Pino, N.
2002-12-01
The 1930 Irpinia earthquake is one of the most destructive events recorded by instruments in Italy. Several large events occurred in the same area before (1456, 1694, 1702, 1732, 1910) and after (1962, 1980, 1983) 1930. It has been hypothesized that significant differences characterized the source geometry. Early work carried out by several authors on macroseismic studies and a single-station waveform analysis, suggests a quasi-strike slip mechanism on an approximately EW-oriented fault plain. Conversely, all the major events in the area display normal fault mechanisms on Apennine-oriented (NW-SE) fault planes. In the present work we have collected about 45 waveforms for the 1930 earthquake, recorded in various European observatories, aiming to find precious hints on source geometry and kinematics. The seismograms have been rasterized, digitized and processed within the framework of the SISMOS project. The study of this earthquake is part of a wider ongoing research program on the 20th century Irpinia earthquakes (1910, 1030, 1962 and 1980) within the collaboration between the TROMOS and SISMOS projects of the National Institute of Geophysics and Volcanology. The search and recovery of the historical recordings is a unique opportunity to shed light upon scientific aspects related to this kind of investigation. Preliminary results about the 1930 earthquake waveform analysis are presented here.
ANALYSIS AND APPLICATION OF LIDAR WAVEFORM DATA USING A PROGRESSIVE WAVEFORM DECOMPOSITION METHOD
National Research Council Canada - National Science Library
J. Zhu; Z. Zhang; X. Hu; Z. Li
2012-01-01
...) pulse detection method-Average Square Difference Function (ASDF). However, the Gaussian modelling methods strongly rely on initial parameters, whereas the ASDF omits the importance of parameter information of the waveform...
Reference respiratory waveforms by minimum jerk model analysis
Energy Technology Data Exchange (ETDEWEB)
Anetai, Yusuke, E-mail: anetai@radonc.med.osaka-u.ac.jp; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Mizuno, Hirokazu; Ogawa, Kazuhiko [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita-shi, Osaka 565-0871 (Japan); Ota, Seiichi [Department of Medical Technology, Osaka University Hospital, Yamadaoka 2-15, Suita-shi, Osaka 565-0871 (Japan)
2015-09-15
Purpose: CyberKnife{sup ®} robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony{sup ®} mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. Methods: The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife{sup ®}. To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony{sup ®} mode, a tracking laser projection from CyberKnife{sup ®} was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior–inferior directions from six volunteers assessed on the same node of the same isocentric plan. Results: Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy
Reference respiratory waveforms by minimum jerk model analysis.
Anetai, Yusuke; Sumida, Iori; Takahashi, Yutaka; Yagi, Masashi; Ota, Seiichi; Mizuno, Hirokazu; Ogawa, Kazuhiko
2015-09-01
CyberKnife(®) robotic surgery system has the ability to deliver radiation to a tumor subject to respiratory movements using Synchrony(®) mode with less than 2 mm tracking accuracy. However, rapid and rough motion tracking causes mechanical tracking errors and puts mechanical stress on the robotic joint, leading to unexpected radiation delivery errors. During clinical treatment, patient respiratory motions are much more complicated, suggesting the need for patient-specific modeling of respiratory motion. The purpose of this study was to propose a novel method that provides a reference respiratory wave to enable smooth tracking for each patient. The minimum jerk model, which mathematically derives smoothness by means of jerk, or the third derivative of position and the derivative of acceleration with respect to time that is proportional to the time rate of force changed was introduced to model a patient-specific respiratory motion wave to provide smooth motion tracking using CyberKnife(®). To verify that patient-specific minimum jerk respiratory waves were being tracked smoothly by Synchrony(®) mode, a tracking laser projection from CyberKnife(®) was optically analyzed every 0.1 s using a webcam and a calibrated grid on a motion phantom whose motion was in accordance with three pattern waves (cosine, typical free-breathing, and minimum jerk theoretical wave models) for the clinically relevant superior-inferior directions from six volunteers assessed on the same node of the same isocentric plan. Tracking discrepancy from the center of the grid to the beam projection was evaluated. The minimum jerk theoretical wave reduced the maximum-peak amplitude of radial tracking discrepancy compared with that of the waveforms modeled by cosine and typical free-breathing model by 22% and 35%, respectively, and provided smooth tracking for radial direction. Motion tracking constancy as indicated by radial tracking discrepancy affected by respiratory phase was improved in the
Chong, Jiajun; Chu, Risheng; Ni, Sidao; Meng, Qingjun; Guo, Aizhi
2018-02-01
It is known that a receiver function has relatively weak constraint on absolute seismic wave velocity, and that joint inversion of the receiver function with surface wave dispersion has been widely applied to reduce the trade-off of velocity with interface depth. However, some studies indicate that the receiver function itself is capable for determining the absolute shear-wave velocity. In this study, we propose to measure the receiver function HV ratio which takes advantage of the amplitude information of the receiver function to constrain the shear-wave velocity. Numerical analysis indicates that the receiver function HV ratio is sensitive to the average shear-wave velocity in the depth range it samples, and can help to reduce the non-uniqueness of receiver function waveform inversion. A joint inversion scheme has been developed, and both synthetic tests and real data application proved the feasibility of the joint inversion.
Helwig, Nathaniel E; Hong, Sungjin; Polk, John D
2012-06-01
Gait data are typically collected in multivariate form, so some multivariate analysis is often used to understand interrelationships between observed data. Principal Component Analysis (PCA), a data reduction technique for correlated multivariate data, has been widely applied by gait analysts to investigate patterns of association in gait waveform data (e.g., interrelationships between joint angle waveforms from different subjects and/or joints). Despite its widespread use in gait analysis, PCA is for two-mode data, whereas gait data are often collected in higher-mode form. In this paper, we present the benefits of analyzing gait data via Parallel Factor Analysis (Parafac), which is a component analysis model designed for three- or higher-mode data. Using three-mode joint angle waveform data (subjects×time×joints), we demonstrate Parafac's ability to (a) determine interpretable components revealing the primary interrelationships between lower-limb joints in healthy gait and (b) identify interpretable components revealing the fundamental differences between normal and perturbed subjects' gait patterns across multiple joints. Our results offer evidence of the complex interconnections that exist between lower-limb joints and limb segments in both normal and abnormal gaits, confirming the need for the simultaneous analysis of multi-joint gait waveform data (especially when studying perturbed gait patterns). Copyright © 2011 Elsevier B.V. All rights reserved.
Soares, Denise Paschoal; de Castro, Marcelo Peduzzi; Mendes, Emilia Assunção; Machado, Leandro
2016-12-01
The alterations in gait pattern of people with transfemoral amputation leave them more susceptible to musculoskeletal injury. Principal component analysis is a method that reduces the amount of gait data and allows analyzing the entire waveform. To use the principal component analysis to compare the ground reaction force and center of pressure displacement waveforms obtained during gait between able-bodied subjects and both limbs of individuals with transfemoral amputation. This is a transversal study with a convenience sample. We used a force plate and pressure plate to record the anterior-posterior, medial-lateral and vertical ground reaction force, and anterior-posterior and medial-lateral center of pressure positions of 12 participants with transfemoral amputation and 20 able-bodied subjects during gait. The principal component analysis was performed to compare the gait waveforms between the participants with transfemoral amputation and the able-bodied individuals. The principal component analysis model explained between 74% and 93% of the data variance. In all ground reaction force and center of pressure waveforms relevant portions were identified; and always at least one principal component presented scores statistically different (p analysis was able to discriminate many portions of the stance phase between both lower limbs of people with transfemoral amputation compared to the able-bodied participants. Principal component analysis reduced the amount of data, allowed analyzing the whole waveform, and identified specific sub-phases of gait that were different between the groups. Therefore, this approach seems to be a powerful tool to be used in gait evaluation and following the rehabilitation status of people with transfemoral amputation. © The International Society for Prosthetics and Orthotics 2015.
Asymptotic Waveform Evaluation (AWE) Technique for Frequency Domain Electromagnetic Analysis
Cockrell, C. R.; Beck, F. B.
1996-01-01
The Asymptotic Waveform Evaluation (AWE) technique is applied to a generalized frequency domain electromagnetic problem. Most of the frequency domain techniques in computational electromagnetics result in a matrix equation, which is solved at a single frequency. In the AWE technique, the Taylor series expansion around that frequency is applied to the matrix equation. The coefficients of the Taylor's series are obtained in terms of the frequency derivatives of the matrices evaluated at the expansion frequency. The coefficients hence obtained will be used to predict the frequency response of the system over a frequency range. The detailed derivation of the coefficients (called 'moments') is given along with an illustration for electric field integral equation (or Method of Moments) technique. The radar cross section (RCS) frequency response of a square plate is presented using the AWE technique and is compared with the exact solution at various frequencies.
Automatic physiological waveform processing for FMRI noise correction and analysis.
Directory of Open Access Journals (Sweden)
Daniel J Kelley
2008-03-01
Full Text Available Functional MRI resting state and connectivity studies of brain focus on neural fluctuations at low frequencies which share power with physiological fluctuations originating from lung and heart. Due to the lack of automated software to process physiological signals collected at high magnetic fields, a gap exists in the processing pathway between the acquisition of physiological data and its use in fMRI software for both physiological noise correction and functional analyses of brain activation and connectivity. To fill this gap, we developed an open source, physiological signal processing program, called PhysioNoise, in the python language. We tested its automated processing algorithms and dynamic signal visualization on resting monkey cardiac and respiratory waveforms. PhysioNoise consistently identifies physiological fluctuations for fMRI noise correction and also generates covariates for subsequent analyses of brain activation and connectivity.
Paize, Fauzia; Carrol, Enitan; Downey, Colin; Parry, Christopher M; Green, Gerwyn; Diggle, Peter; Newland, Paul; Riordan, F A I; Thomson, Alistair; Hart, C A; Toh, Cheng-Hock
2011-11-01
A biphasic activated partial thromboplastin time waveform predicts sepsis and disseminated intravascular coagulation in adults. This has not been previously investigated in children. Our aim is to ascertain whether there are changes in the activated partial thromboplastin time waveform in children with meningococcal disease and to compare its diagnostic use with procalcitonin. Alder Hey Children's National Health Service Foundation Trust, Liverpool, UK. Thirty-six children admitted to the hospital for the treatment of suspected meningococcal disease had activated partial thromboplastin time waveform and procalcitonin analysis performed at admission. The light transmittance level at 18 secs was used to quantitate the waveform. Severity of disease was assessed using the Glasgow Meningococcal Septicaemia Prognostic Score, Pediatric Risk of Mortality III score, and the Pediatric Logistic Organ Dysfunction score. Twenty-four children had proven meningococcal disease, 12 had a presumed viral illness, and 20 control subjects were recruited. Transmittance level at 18 secs was lower in children with meningococcal disease and those with a viral illness (p Sensitivity and specificity was 0.91 and 0.96 for transmittance level at 18 secs and 0.92 and 1 for procalcitonin in identifying meningococcal disease. There was a significant difference in procalcitonin between children with meningococcal disease and those with a viral illness and control subjects (p thromboplastin time waveform is abnormal in children with meningococcal disease and may be a useful adjunct in the diagnosis and management of sepsis in children.
Speech analysis and synthesis based on pitch-synchronous segmentation of the speech waveform
Kang, George S.; Fransen, Lawrence J.
1994-11-01
This report describes a new speech analysis/synthesis method. This new technique does not attempt to model the human speech production mechanism. Instead, we represent the speech waveform directly in terms of the speech waveform defined in a pitch period. A significant merit of this approach is the complete elimination of pitch interference because each pitch-synchronously segmented waveform does not include a waveform discontinuity. One application of this new speech analysis/synthesis method is the alteration of speech characteristics directly on raw speech. With the increased use of man-made speech in tactical voice message systems and virtual reality environments, such a speech generation tool is highly desirable. Another application is speech encoding operation at low data rates (2400 b/s or less). According to speech intelligibility tests, our new 2400 b/s encoder outperforms the current 2400-b/s LPC. This is also true in noisy environments. Because most tactical platforms are noisy (e.g., helicopter, high-performance aircraft, tank, destroyer), our 2400-b/s speech encoding technique will make tactical voice communication more effective; it will become an indispensable capability for future C4I.
WAVEFORM ANALYSIS FOR THE EXTRACTION OF POST-FIRE VEGETATION CHARACTERISTICS
Directory of Open Access Journals (Sweden)
F. Pirotti
2012-08-01
Full Text Available Full-waveform is becoming increasingly available in today's LiDAR systems and the analysis of the full return signal can provide additional information on the reflecting surfaces. In this paper we present the results of an assessment on full-waveform analysis, as opposed to the more classic discrete return analysis, for discerning vegetation cover classes related to post-fire renovation. In the spring of 2011 an OPTECH ALTM sensor was used to survey an Alpine area of almost 20 km2 in the north of Italy. A forest fire event several years ago burned large patches of vegetation for a total of about 1.5 km2 . The renovation process in the area is varied because of the different interventions ranging from no intervention to the application of re-forestation techniques to accelerate the process of re-establishing protection forest. The LiDAR data was used to divide the study site into areas with different conditions in terms of re-establishment of the natural vegetation condition. The LiDAR survey provided both the full-waveform data in Optech's CSD+DGT (corrected sensor data and NDF+IDX (digitizer data with index file formats, and the discrete return in the LAS format. The method applied to the full-waveform uses canopy volume profiles obtained by modelling, whereas the method applied to discrete return uses point geometry and density indexes. The results of these two methods are assessed by ground truth obtained from sampling and comparison shows that the added information from the full-waveform does give a significant better discrimination of the vegetation cover classes.
Seppänen, Tiina M; Alho, Olli-Pekka; Seppänen, Tapio
2013-09-28
Respiratory effort belt measurement is a widely used method to monitor respiration. Signal waveforms of respiratory volume and flow may indicate pathological signs of several diseases and, thus, it would be highly desirable to predict them accurately. Calibrated effort belts are sufficiently accurate for estimating respiratory rate, but the respiratory volume and flow prediction accuracies degrade considerably with changes in the subject's body position and breathing style. An improved calibration method of respiratory effort belts is presented in this paper. It is based on an optimally trained FIR (Finite Impulse Response) filter bank constructed as a MISO system (Multiple-Input Single-Output) between respiratory effort belt signals and the spirometer in order to reduce waveform errors. Ten healthy adult volunteers were recruited. Breathing was varied between the following styles: metronome-guided controlled breathing rate of 0.1 Hz, 0.15 Hz, 0.25 Hz and 0.33 Hz, and a free rate that was felt normal by each subject. Body position was varied between supine, sitting and standing. The proposed calibration method was tested against these variations and compared with the state-of-the-art methods from the literature. Relative waveform error decreased 60-70% when predicting airflow under changing breathing styles. The coefficient of determination R2 varied between 0.88-0.95 and 0.65-0.79 with the proposed and the standard method, respectively. Standard deviation of respiratory volume error decreased even 80%. The proposed method outperformed other methods. Results show that not only the respiratory volume can be computed more precisely from the predicted airflow, but also the flow waveforms are very accurate with the proposed method. The method is robust to breathing style changes and body position changes improving greatly the accuracy of the calibration of respiratory effort belts over the standard method. The enhanced accuracy of the belt calibration offers
Adamsa, Bernhard; Bogdan, Mircea; Byrum, Karen; Genat, Jean-Francois C; Grabas, Herve; Frisch, Henry J; Kim, Heejong; Heintz, Mary K; Natoli, Tyler; Northrop, Richard; Oberla, Eric; Meehan, Samuel; May, Edward N; Stanek, Robert; Tang, Fukun; Varner, Gary; Yurtsev, Eugene
2009-01-01
The anodes of Micro-Channel Plate devices are coupled to fast transmission lines in order to reduce the number of electronics readout channels, and can provide two-dimension position measurements using two-ends delay timing. Tests with a laser and digital waveform analysis show that resolutions of a few hundreds of microns along the transmission line can be reached taking advantage of a few pico-second timing estimation. This technique is planned to be used in Micro-channel Plate devices integrating the transmission lines as anodes.
Deluzio, K J; Astephen, J L
2007-01-01
This study compared the gait of 50 patients with end-stage knee osteoarthritis to a group of 63 age-matched asymptomatic control subjects. The analysis focused on three gait waveform measures that were selected based on previous literature demonstrating their relevance to knee osteoarthritis (OA): the knee flexion angle, flexion moment, and adduction moment. The objective was to determine the biomechanical features of these gait measures related to knee osteoarthritis. Principal component analysis was used as a data reduction tool, as well as a preliminary step for further analysis to determine gait pattern differences between the OA and the control groups. These further analyses included statistical hypothesis testing to detect group differences, and discriminant analysis to quantify overall group separation and to establish a hierarchy of discriminatory ability among the gait waveform features. The two groups were separated with a misclassification rate (estimated by cross-validation) of 8%. The discriminatory features of the gait waveforms were, in order of their discriminatory ability: the amplitude of the flexion moment, the range of motion of the flexion angle, the magnitude of the flexion moment during early stance, and the magnitude of the adduction moment during stance.
Ji, Yanju; Huang, Wanyu; Yu, Mingmei; Guan, Shanshan; Wang, Yuan; Zhu, Yu
2017-01-01
This article studies full-waveform associated identification method of airborne time-domain electromagnetic method (ATEM) 3-d anomalies based on multiple linear regression analysis method. By using convolution algorithm, full-waveform theoretical responses are computed to derive sample library including switch-off-time period responses and off-time period responses. Extract full-waveform attributes from theoretical responses to derive linear regression equations which are used to identify the geological parameters. In order to improve the precision ulteriorly, we optimize the identification method by separating the sample library into different groups and identify the parameter respectively. Performance of full-waveform associated identification method with field data of wire-loop test experiments with ATEM system in Daedao of Changchun proves that the full-waveform associated identification method is feasible practically.
Ramirez, Ivan I; Arellano, Daniel H; Adasme, Rodrigo S; Landeros, Jose M; Salinas, Francisco A; Vargas, Alvaro G; Vasquez, Francisco J; Lobos, Ignacio A; Oyarzun, Magdalena L; Restrepo, Ruben D
2017-02-01
Waveform analysis by visual inspection can be a reliable, noninvasive, and useful tool for detecting patient-ventilator asynchrony. However, it is a skill that requires a properly trained professional. This observational study was conducted in 17 urban ICUs. Health-care professionals (HCPs) working in these ICUs were asked to recognize different types of asynchrony shown in 3 evaluation videos. The health-care professionals were categorized according to years of experience, prior training in mechanical ventilation, profession, and number of asynchronies identified correctly. A total of 366 HCPs were evaluated. Statistically significant differences were found when HCPs with and without prior training in mechanical ventilation (trained vs non-trained HCPs) were compared according to the number of asynchronies detected correctly (of the HCPs who identified 3 asynchronies, 63 [81%] trained vs 15 [19%] non-trained, P mechanical ventilation also increased, nearly 4-fold, their odds of identifying ≥2 asynchronies correctly (odds ratio 3.67, 95% CI 1.93-6.96, P mechanical ventilation increase their ability to identify asynchrony using waveform analysis. Neither experience nor profession proved to be a relevant factor to identify asynchrony correctly using waveform analysis. Copyright © 2017 by Daedalus Enterprises.
Health monitoring of Ceramic Matrix Composites from waveform-based analysis of Acoustic Emission
Directory of Open Access Journals (Sweden)
Maillet Emmanuel
2015-01-01
Full Text Available Ceramic Matrix Composites (CMCs are anticipated for use in the hot section of aircraft engines. Their implementation requires the understanding of the various damage modes that are involved and their relation to life expectancy. Acoustic Emission (AE has been shown to be an efficient technique for monitoring damage evolution in CMCs. However, only a waveform-based analysis of AE can offer the possibility to validate and precisely examine the recorded AE data with a view to damage localization and identification. The present work fully integrates wave initiation, propagation and acquisition in the analysis of Acoustic Emission waveforms recorded at various sensors, therefore providing more reliable information to assess the relation between Acoustic Emission and damage modes. The procedure allows selecting AE events originating from damage, accurate determination of their location as well as the characterization of effects of propagation on the recorded waveforms. This approach was developed using AE data recorded during tensile tests on carbon/carbon composites. It was then applied to melt-infiltrated SiC/SiC composites.
Park, Eunjin; Shin, Changsoo
2017-04-01
The controlled directional reception (CDR) method is a velocity analysis method using ray-tracing. It is one of the tomographic methods that use slope (or ray parameter), so it is often called the "slope tomography method". It does not require a pre-picking operation like traveltime tomography does. Auto-picked information from the local slant stack is regarded as more reliable than reflection traveltime picked directly from the seismic data. The method also provides more detailed information about the moveout than the imaging operator in migration-based velocity analysis (MVA). Therefore, we constructed a velocity macro-model using this strip-off CDR velocity analysis. When compared to the conventional CDR method, it increased the resolution of common receiver gathers (CRG) data and reduced computer storage space dramatically. Additionally, it improved the accuracy of the velocity model by using the migrated image as a background panel during the velocity analysis. The results obtained by this method were applied to full waveform inversion (FWI) as the initial velocity model. In FWI, an exact initial model is important because it reduces instability and increases the probability of convergence to the global minimum. It is significant that the CDR model is first applied as the initial model of FWI. We confirmed good inverted results from two realistic synthetic data tests by comparison with the results obtained using the conventional initial models. In particular, the CDR macro-model has great value on its high accuracy. It is expected to provide good results with difficult data, such as seismic data with a weathered zone or short offset, and so increase the accuracy compared with the conventional method. Furthermore, it is possible to apply to multi-parameter inversion. In summary, the macro-model obtained from strip-off CDR velocity analysis is suitable for frequency domain FWI. Three-dimensional exploration and exploration in complex terrains are being conducted
Analysis of LFM-waveform Libraries for Cognitive Tracking Maneuvering Targets
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Wang Hongyan
2016-01-01
Full Text Available Based on the idea of the waveform agility in cognitive radars，the waveform libraries for maneuvering target tracking are discussed. LFM-waveform libraries are designed according to different combinations of chirp parameters and FrFT rotation angles. By applying the interact multiple model (IMM algorithm in tracking maneuvering targets, transmitted waveform is called real time from the LFM-waveform libraries. The waveforms are selected from the library according to the criterion of maximum mutual information between the current state of knowledge of the model and the measurement. Simulation results show that waveform library containing certain amount LFM-waveforms can improve the performance of cognitive tracking radar.
Directory of Open Access Journals (Sweden)
Jason Robert Potas
Full Text Available Experimental electrophysiological assessment of evoked responses from regenerating nerves is challenging due to the typical complex response of events dispersed over various latencies and poor signal-to-noise ratio. Our objective was to automate the detection of compound action potential events and derive their latencies and magnitudes using a simple cross-correlation template comparison approach. For this, we developed an algorithm called Waveform Similarity Analysis. To test the algorithm, challenging signals were generated in vivo by stimulating sural and sciatic nerves, whilst recording evoked potentials at the sciatic nerve and tibialis anterior muscle, respectively, in animals recovering from sciatic nerve transection. Our template for the algorithm was generated based on responses evoked from the intact side. We also simulated noisy signals and examined the output of the Waveform Similarity Analysis algorithm with imperfect templates. Signals were detected and quantified using Waveform Similarity Analysis, which was compared to event detection, latency and magnitude measurements of the same signals performed by a trained observer, a process we called Trained Eye Analysis. The Waveform Similarity Analysis algorithm could successfully detect and quantify simple or complex responses from nerve and muscle compound action potentials of intact or regenerated nerves. Incorrectly specifying the template outperformed Trained Eye Analysis for predicting signal amplitude, but produced consistent latency errors for the simulated signals examined. Compared to the trained eye, Waveform Similarity Analysis is automatic, objective, does not rely on the observer to identify and/or measure peaks, and can detect small clustered events even when signal-to-noise ratio is poor. Waveform Similarity Analysis provides a simple, reliable and convenient approach to quantify latencies and magnitudes of complex waveforms and therefore serves as a useful tool for
Using arterial pressure waveform analysis for the assessment of fluid responsiveness.
Cannesson, Maxime; de Backer, Daniel; Hofer, Christoph K
2011-09-01
Predicting the effects of volume expansion on cardiac output and oxygen delivery is of major importance in different clinical scenarios. Functional hemodynamic parameters based on pulse waveform analysis, which are relying on the effects of mechanical ventilation on stroke volume and its surrogates, have been shown to be reliable predictors of fluid responsiveness during anesthesia and intensive care unit treatment, as demonstrated by several clinical studies and meta-analyses. However, different limitations of these parameters have to be considered when they are used in clinical practice. Today, they can be continuously and automatically monitored by a variety of commercially available devices. These parameters have been introduced into the concept of perioperative fluid management and hemodynamic optimization - an approach that may positively impact postoperative patients' outcomes. In this article, technical aspects of the assessment of the functional hemodynamic parameters derived from pulse waveform analysis are summarized, emphasizing their advantages, limitations and potential applications, primarily in a perioperative setting in order to improve patient outcome.
Griffiths, Rian L; Dexter, Alex; Creese, Andrew J; Cooper, Helen J
2015-10-21
Liquid extraction surface analysis (LESA) is a surface sampling technique that allows electrospray mass spectrometry analysis of a wide range of analytes directly from biological substrates. Here, we present LESA mass spectrometry coupled with high field asymmetric waveform ion mobility spectrometry (FAIMS) for the analysis of dried blood spots on filter paper. Incorporation of FAIMS in the workflow enables gas-phase separation of lipid and protein molecular classes, enabling analysis of both haemoglobin and a range of lipids (phosphatidylcholine or phosphatidylethanolamine, and sphingomyelin species) from a single extraction sample. The work has implications for multiplexed clinical assays of multiple analytes.
Kojo, M; Ogawa, T; Fukushima, N; Yamada, K; Goto, K
1995-05-01
We analyzed the carotid artery blood flow waveform (CABFW) through multivariate autoregressive analysis in a case with multicystic encephalomalacia (MCE) after neonatal asphyxia and compared the result with those of 35 healthy newborns. The total power of CABFW was at the -2 SD level of the value for 35 healthy newborns, and the power, % power, bio-informing amounts and damping time of component 3 (damping frequency 11.15 Hz) were less than -2 SD of the values in 35 healthy newborns. The Pulsatility Index (PI) of anterior cerebral artery (ACA) was high (0.76). These results suggest that cerebral blood flow decreases because of cerebral vasoconstriction in MCE after neonatal asphyxia.
Biomechanical parameters of the cornea after collagen crosslinking measured by waveform analysis.
Sedaghat, Mohamadreza; Naderi, Mostafa; Zarei-Ghanavati, Mehran
2010-10-01
To compare 2 corneal biomechanical parameters--corneal hysteresis (CH) and corneal resistance factor (CRF)--before and after collagen crosslinking (CXL) for keratoconus. Eye Research Center of Mashhad University of Medical Sciences, Khatam-al-Anbia Eye Hospital, Mashhad, and Department of Ophthalmology, Baqiyatallah University of Medical Science, Tehran, Iran. Case series study. Topical riboflavin was applied to the deepithelialized cornea every 3 minutes for 30 minutes and every 5 minutes during ultraviolet-A irradiation of the cornea. Corneal hysteresis and CRF were measured by biomechanical waveform analysis (Ocular Response Analyzer) before and 6 months after CXL. The values were compared using the paired Student t test. The study comprised 51 patients (56 eyes). The mean age of the patients was 23.27 years ± 6.3 (SD). Before CXL, the mean CH was 7.9 ± 1.5 mm Hg and the mean CRF was 7.3 ± 1.4 mm Hg. Six months after CXL, the mean values were 8.20 ± 1.5 mm Hg and 7.59 ± 1.5 mm Hg, respectively. The changes in CH and CRF were not statistically significant (P>.05). The changes in central corneal thickness and Goldmann-correlated intraocular pressure (IOP) between preoperatively and postoperatively were not statistically significant, although the change in corneal-compensated IOP was (P<.05). Although previous in vitro studies found a change in corneal rigidity, this study found no significant change in CH or CHF measured by biomechanical waveform analysis. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Shear and compressional velocity models of the mantle from cluster analysis of long-period waveforms
Houser, C.; Masters, G.; Shearer, P.; Laske, G.
2008-07-01
We present a new technique for the efficient measurement of the traveltimes of long period body wave phases. The technique is based on the fact that all arrivals of a particular seismic phase are remarkably similar in shape for a single event. This allows the application of cross-correlation techniques that are usually used in a regional context to measure precise global differential times. The analysis is enhanced by the inclusion of a clustering algorithm that automatically clusters waveforms by their degree of similarity. This allows the algorithm to discriminate against unusual or distorted waveforms and makes for an extremely efficient measurement technique. This technique can be applied to any seismic phase that is observed over a reasonably large distance range. Here, we present the results of applying the algorithm to the long-period channels of all data archived at the IRIS DMC from 1976 to 2005 for the seismic phases S and P (from 23° to 100°) and SS and PP (from 50° to 170°). The resulting large data sets are inverted along with existing surface wave and updated differential traveltime measurements for new mantle models of S and P velocity. The resolution of the new model is enhanced, particularly, in the mid-mantle where SS and PP turn. We find that slow anomalies in the central Pacific and Africa extend from the core-mantle boundary to the upper mantle, but their direct connection to surface hotspots is beyond our resolution. Furthermore, we find that fast anomalies that are likely associated with subducting slabs disappear between 1700 and 2500 km, and thus are not continuous features from the upper to lower mantle despite our extensive coverage and high resolution of the mid-mantle.
Delannoy, Bertrand; Guye, Marie-Laurence; Slaiman, Davy; Lehot, Jean-Jacques; Cannesson, Maxime
2009-01-01
Abstract Introduction Systemic inflammatory response syndrome (SIRS) is a frequent condition after cardiopulmonary bypass (CPB) and makes conventional biological tests fail to detect postoperative sepsis. Biphasic waveform (BPW) analysis is a new biological test derived from activated partial thromboplastin time that has recently been proposed for sepsis diagnosis. The aim of this stud...
Montenij, L.J.
2016-01-01
Cardiac output and preload are important variables in the hemodynamic optimization of critically ill patients in the operating room and intensive care unit. Arterial waveform analysis (AWA) enables continuous, minimally invasive measurement of CO from an arterial line, and provides dynamic
Hussain, Qurban; Haider, Shahbaz; Solangi, Noor Muhammad; Ali, Liaquat; Liaquat, Hammad; Ahmed, Fayyaz; Shahbaz, Sumera
2013-05-01
To observe the changes in Doppler waveform of hepatic vein after the administration of terlipressin, and to assess indirectly the efficacy of the drug to reduce the Hepatic Vein Pressure Gradient and portal pressure. The quasi-experimental study was conducted at the Jinnah Postgraduate Medical Centre, Karachi, from April 1 to November 25, 2011, and comprised 50 patients with cirrhosis with abnormal Doppler waveform of the hepatic vein. Patients with diseases causing abnormal hepatic vein doppler waveform were excluded. Doppler waveforms were studied for 20 minutes before and for 20 minutes after the administration of terlipressin. Tracings with best waveform before and after injection were saved for analysis. Changes in waveform after vasoactive drug were defined as mild, significant, marked and gross changes. SPSS 10 was used for statistical analysis. Of the 50 patients, 36 (72%) were males and 14 (28%) females. Commonest waveform was monophasic 38 (76%). Gross changes i.e. turning triphasic from monophasic waveform was observed in 8 (16%) patients. Significant gross changes were seen in 24 (48%) patients. Total number of patients showing improvement in waveform was 36 (72%). In no case, waveform deteriorated after the administration of terlipressin (p = 0.001). Non-invasive method of observing the improvement of hepatic vein waveform by duplex ultrasound, after more studies, may be an important tool for assessing and monitoring the effects of portal pressure lowering drugs.
Coifman, Ronald R.; Woog, Lionel J.
1995-09-01
Adapted wave form analysis, refers to a collection of FFT like adapted transform algorithms. Given an image these methods provide special matched collections of templates (orthonormal bases) enabling an efficient coding of the image. Perhaps the closest well known example of such coding method is provided by musical notation, where each segment of music is represented by a musical score made up of notes (templates) characterised by their duration, pitch, location and amplitude, our method corresponds to transcribing the music in as few notes as possible. The extension to images and video is straightforward we describe the image by collections of oscillatory patterns (paint brush strokes)of various sizes locations and amplitudes using a variety of orthogonal bases. These selected basis functions are chosen inside predefined libraries of oscillatory localized functions (trigonometric and wavelet-packets waveforms) so as to optimize the number of parameters needed to describe our object. These algorithms are of complexity N log N opening the door for a large range of applications in signal and image processing, such as compression, feature extraction denoising and enhancement. In particular we describe a class of special purpose compressions for fingerprint irnages, as well as denoising tools for texture and noise extraction. We start by relating traditional Fourier methods to wavelet, wavelet-packet based algorithms using a recent refinement of the windowed sine and cosine transforms. We will then derive an adapted local sine transform show it's relation to wavelet and wavelet-packet analysis and describe an analysis toolkit illustrating the merits of different adaptive and nonadaptive schemes.
Waveform Retracking and Emulation Experiment Analysis of Synthetic Aperture Radar Altimeter
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ZHAI Zhenhe
2017-02-01
Full Text Available Based on the synthetic aperture radar(SAR convolution model, the convolution computation formula about the derivative of three parameters of time migration, rise time and amplitude are deduced. The SAR waveform retracking is completed using numerical integration and Fourier transform. Besides, the echo waveform under SAR model is generated using the simulation orbit, troposphere, ionosphere and tide model. The comparison shows that the shape of echo waveform under SAR model is the same as that of CryoSat-2 1 Hz SAR. The experiments show that the accuracy of SAR altimeter retracking is about 5 cm under the 20 Hz data(about 350 m resolution, which are improved compared with that of the traditional model.
Analysis of full-waveform LiDAR data for classification of an orange orchard scene
Fieber, Karolina D.; Davenport, Ian J.; Ferryman, James M.; Gurney, Robert J.; Walker, Jeffrey P.; Hacker, Jorg M.
2013-08-01
Full-waveform laser scanning data acquired with a Riegl LMS-Q560 instrument were used to classify an orange orchard into orange trees, grass and ground using waveform parameters alone. Gaussian decomposition was performed on this data capture from the National Airborne Field Experiment in November 2006 using a custom peak-detection procedure and a trust-region-reflective algorithm for fitting Gauss functions. Calibration was carried out using waveforms returned from a road surface, and the backscattering coefficient γ was derived for every waveform peak. The processed data were then analysed according to the number of returns detected within each waveform and classified into three classes based on pulse width and γ. For single-peak waveforms the scatterplot of γ versus pulse width was used to distinguish between ground, grass and orange trees. In the case of multiple returns, the relationship between first (or first plus middle) and last return γ values was used to separate ground from other targets. Refinement of this classification, and further sub-classification into grass and orange trees was performed using the γ versus pulse width scatterplots of last returns. In all cases the separation was carried out using a decision tree with empirical relationships between the waveform parameters. Ground points were successfully separated from orange tree points. The most difficult class to separate and verify was grass, but those points in general corresponded well with the grass areas identified in the aerial photography. The overall accuracy reached 91%, using photography and relative elevation as ground truth. The overall accuracy for two classes, orange tree and combined class of grass and ground, yielded 95%. Finally, the backscattering coefficient γ of single-peak waveforms was also used to derive reflectance values of the three classes. The reflectance of the orange tree class (0.31) and ground class (0.60) are consistent with published values at the
Klotzsche, Anja; van der Kruk, Jan; Linde, Niklas; Doetsch, Joseph; Vereecken, Harry
2013-04-01
For an accurate characterization of aquifers, high resolution 3D visualization with a high resolution can greatly improve the understanding of the interior process of flow and transport. Over the last decades crosshole ground penetrating radar showed to be a powerful tool for the characterization of aquifers due to the possibility of providing high resolution images and the strong connection to porosity and soil water content. The full-waveform inversion of GPR, that incorporates the entire waveform, can significantly improve the model resolution compared to standard ray-based techniques that uses only a small fraction of the signal. Here, the 2D full-waveform inversion is applied to a gravel aquifer in Switzerland and analyzed in 3D by inverting six crosshole GPR planes acquired between four wells. The permittivity and conductivity results obtained by the full-waveform inversion for the saturated aquifer between 4m-10m depth showed sub-wavelength resolution images with mainly similar layering at the intersection of the planes and the borehole locations. In all the conductivity images the underlying lacustrine sediments (high clay content) are clearly identified. Additionally a high permittivity zone is resolved between 5m-6m depth in all the six GPR planes which indicates a high porosity zone that is possible acting as a zone of preferential flow. Due to the high contrast to the surrounding medium this layer is acting as an electromagnetic waveguide and causes high amplitude late arrival elongated wave trains with at least one order of magnitude higher trace energy in the GPR data for transmitters-receiver combinations in this zone. For the same receivers when the transmitter is located outside this zone a distinct minimum in the trace energy can be observed. Using these maxima and minima positions of the trace energy spectra, we developed a novel amplitude analysis approach that is able to identify waveguides and their boundaries already in the measured GPR data
Derive Icebridge Sea-Ice Freeboard and Thickness Data through Full Waveform Analysis
Yi, D.; Harbeck, J. P.; Manizade, S.; Hofton, M. A.; Kurtz, N. T.; Studinger, M.
2014-12-01
The current Operation IceBridge Airborne Topographic Mapper (ATM) sea-ice freeboard and thickness data product at the National Snow and Ice Data Center (NSIDC) requires coincident Digital Mapping System (DMS) imagery or Continuous Airborne Mapping By Optical Translator (CAMBOT) imagery to produce. However, some of the IceBridge ATM and Land, Vegetation, and Ice Sensor (LVIS) sea-ice flights have no coincident imagery data. In particular, the IceBridge "South Basin Transect" flights just north of the Canadian Archipelago have historically been flown under darkness (nighttime) and coincident imagery data are not available. Here we apply an algorithm using ATM waveform parameters to identify leads to derive sea-ice freeboard. ATM waveforms were fitted with Gaussian curves to calculate pulse width, peak location, pulse amplitude, and signal baseline. For each waveform, centroid, skewness, kurtosis, and pulse area were also calculated. Received waveform parameters, such as pulse width, pulse amplitude, pulse area, skewness, kurtosis, and transmitted/received pulse area ratio show a coherent response to variations of geophysical features along an ATM profile. These parameters, combined with elevation, were used to identify leads to enable sea-ice freeboard calculation. A similar algorithm is applied to the LVIS data to calculate sea-ice freeboard. Arctic sea-ice freeboards for ATM and LVIS data with no coincident visual imagery are derived in this study, extending the IceBridge sea-ice record over a large portion of thick multi-year sea ice. The results are evaluated/validated by using ATM data with coincident DMS imagery and near coincident ATM and LVIS data comparison.
Construction of Waveform Library in Cognitive Radar
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Yongqiang Guo
2017-08-01
Full Text Available Based on the thoughts of cognitive radar, Fractional Fourier Transform (FrFT is used to generate a rotatable waveform libraries of Frank coded/Barker coded waveform in this paper. Then, the ambiguity function is used to analyze the delay resolution, Doppler resolution, delay side-lobe level, and Doppler side-lobe level of the waveform libraries and orthogonality of them is also analyzed. Furthermore, we proved theoretically that there is a fixed coordinate transformation between the waveforms of library and its origin waveform. Therefore, the Cramér-Rao low bound (CRLB of motion parameters can be computed easily using the waveforms of the libraries, which facilitate the subsequent waveform scheduled work. Simulation results show that the library waveforms can reduce delay resolution to satisfy the different situations and can bring significant benefits for delay resolution, orthogonality and reuse interval.
Detailed analysis of tsunami waveforms generated by the 1946 Aleutian tsunami earthquake
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Y. Tanioka
2001-01-01
Full Text Available The 1946 Aleutian earthquake was a typical tsunami earthquake which generated abnormally larger tsunami than expected from its seismic waves. Previously, Johnson and Satake (1997 estimated the fault model of this earthquake using the tsunami waveforms observed at tide gauges. However, they did not model the second pulse of the tsunami at Honolulu although that was much larger than the first pulse. In this paper, we numerically computed the tsunami waveforms using the linear Boussinesq equation to determine the fault model which explains the observed tsunami waveforms including the large second pulse observed at Honolulu. The estimated fault width is 40–60 km which is much narrower than the fault widths of the typical great underthrust earthquakes, the 1957 Aleutian and the 1964 Alasuka earthquakes. A previous study of the 1896 Sanriku earthquake, another typical tsunami earthquake, suggested that the additional uplift of the sediments near the Japan Trench had a large effect on the tsunami generation. In this study, we also show that the additional uplift of the sediments near the trench, due to a large coseismic horizon-tal movement of the backstop, had a significant effect on the tsunami generation of the 1946 Aleutian earthquake. The estimated seismic moment of the 1946 Aleutian earthquake is 17–19 × 1020 20 Nm (Mw 8.1.
Page, Juliet A.; Hodgdon, Kathleen K.; Krecker, Peg; Cowart, Robbie; Hobbs, Chris; Wilmer, Clif; Koening, Carrie; Holmes, Theresa; Gaugler, Trent; Shumway, Durland L.;
2014-01-01
The Waveforms and Sonic boom Perception and Response (WSPR) Program was designed to test and demonstrate the applicability and effectiveness of techniques to gather data relating human subjective response to multiple low-amplitude sonic booms. It was in essence a practice session for future wider scale testing on naive communities, using a purpose built low-boom demonstrator aircraft. The low-boom community response pilot experiment was conducted in California in November 2011. The WSPR team acquired sufficient data to assess and evaluate the effectiveness of the various physical and psychological data gathering techniques and analysis methods.
ASKI: A modular toolbox for scattering-integral-based seismic full waveform inversion and sensitivity analysis utilizing external forward codes
Schumacher, Florian; Friederich, Wolfgang
Due to increasing computational resources, the development of new numerically demanding methods and software for imaging Earth's interior remains of high interest in Earth sciences. Here, we give a description from a user's and programmer's perspective of the highly modular, flexible and extendable software package ASKI-Analysis of Sensitivity and Kernel Inversion-recently developed for iterative scattering-integral-based seismic full waveform inversion. In ASKI, the three fundamental steps of solving the seismic forward problem, computing waveform sensitivity kernels and deriving a model update are solved by independent software programs that interact via file output/input only. Furthermore, the spatial discretizations of the model space used for solving the seismic forward problem and for deriving model updates, respectively, are kept completely independent. For this reason, ASKI does not contain a specific forward solver but instead provides a general interface to established community wave propagation codes. Moreover, the third fundamental step of deriving a model update can be repeated at relatively low costs applying different kinds of model regularization or re-selecting/weighting the inverted dataset without need to re-solve the forward problem or re-compute the kernels. Additionally, ASKI offers the user sensitivity and resolution analysis tools based on the full sensitivity matrix and allows to compose customized workflows in a consistent computational environment. ASKI is written in modern Fortran and Python, it is well documented and freely available under terms of the GNU General Public License (http://www.rub.de/aski).
An improved analysis of GW150914 using a fully spin-precessing waveform model
Abbott, B P; Abbott, T D; Abernathy, M R; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Adya, V B; Affeldt, C; Agathos, M; Agatsuma, K; Aggarwal, N; Aguiar, O D; Aiello, L; Ain, A; Ajith, P; Allen, B; Allocca, A; Altin, P A; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C C; Areeda, J S; Arnaud, N; Arun, K G; Ascenzi, S; Ashton, G; Ast, M; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Babak, S; Bacon, P; Bader, M K M; Baker, P T; Baldaccini, F; Ballardin, G; Ballmer, S W; Barayoga, J C; Barclay, S E; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barta, D; Bartlett, J; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Baune, C; Bavigadda, V; Bazzan, M; Bejger, M; Bell, A S; Berger, B K; Bergmann, G; Berry, C P L; Bersanetti, D; Bertolini, A; Betzwieser, J; Bhagwat, S; Bhandare, R; Bilenko, I A; Billingsley, G; Birch, J; Birney, R; Birnholtz, O; Biscans, S; Bisht, A; Bitossi, M; Biwer, C; Bizouard, M A; Blackburn, J K; Blair, C D; Blair, D G; Blair, R M; Bloemen, S; Bock, O; Boer, M; Bogaert, G; Bogan, C; Bohe, A; Bond, C; Bondu, F; Bonnand, R; Boom, B A; Bork, R; Boschi, V; Bose, S; Bouffanais, Y; Bozzi, A; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Brillet, A; Brinkmann, M; Brisson, V; Brockill, P; Broida, J E; Brooks, A F; Brown, D A; Brown, D D; Brown, N M; Brunett, S; Buchanan, C C; Buikema, A; Bulik, T; Bulten, H J; Buonanno, A; Buskulic, D; Buy, C; Byer, R L; Cabero, M; Cadonati, L; Cagnoli, G; Cahillane, C; Bustillo, J Calder'on; Callister, T; Calloni, E; Camp, J B; Cannon, K C; Cao, J; Capano, C D; Capocasa, E; Carbognani, F; Caride, S; Diaz, J Casanueva; Casentini, C; Caudill, S; Cavagli`a, M; Cavalier, F; Cavalieri, R; Cella, G; Cepeda, C B; Baiardi, L Cerboni; Cerretani, G; Cesarini, E; Chan, M; Chao, S; Charlton, P; Chassande-Mottin, E; Cheeseboro, B D; Chen, H Y; Chen, Y; Cheng, C; Chincarini, A; Chiummo, A; Cho, H S; Cho, M; Chow, J H; Christensen, N; Chu, Q; Chua, S; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C G; Cominsky, L; Constancio, M; Conte, A; Conti, L; Cook, D; Corbitt, T R; Cornish, N; Corsi, A; Cortese, S; Costa, C A; Coughlin, M W; Coughlin, S B; Coulon, J -P; Countryman, S T; Couvares, P; Cowan, E E; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Cripe, J; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Darman, N S; Dasgupta, A; Costa, C F Da Silva; Dattilo, V; Dave, I; Davier, M; Davies, G S; Daw, E J; Day, R; De, S; DeBra, D; Debreczeni, G; Degallaix, J; De Laurentis, M; Del'eglise, S; Del Pozzo, W; Denker, T; Dent, T; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Devine, R C; Dhurandhar, S; D'iaz, M C; Di Fiore, L; Di Giovanni, M; Di Girolamo, T; Di Lieto, A; Di Pace, S; Di Palma, I; Di Virgilio, A; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Ducrot, M; Dwyer, S E; Edo, T B; Edwards, M C; Effler, A; Eggenstein, H -B; Ehrens, P; Eichholz, J; Eikenberry, S S; Engels, W; Essick, R C; Etienne, Z; Etzel, T; Evans, M; Evans, T M; Everett, R; Factourovich, M; Fafone, V; Fair, H; Fairhurst, S; Fan, X; Fang, Q; Farinon, S; Farr, B; Farr, W M; Fauchon-Jones, E; Favata, M; Fays, M; Fehrmann, H; Fejer, M M; Fenyvesi, E; Ferrante, I; Ferreira, E C; Ferrini, F; Fidecaro, F; Fiori, I; Fiorucci, D; Fisher, R P; Flaminio, R; Fletcher, M; Fournier, J -D; Frasca, S; Frasconi, F; Frei, Z; Freise, A; Frey, R; Frey, V; Fritschel, P; Frolov, V V; Fulda, P; Fyffe, M; Gabbard, H A G; Gaebel, S; Gair, J R; Gammaitoni, L; Gaonkar, S G; Garufi, F; Gaur, G; Gehrels, N; Gemme, G; Geng, P; Genin, E; Gennai, A; George, J; Gergely, L; Germain, V; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S; Giaime, J A; Giardina, K D; Giazotto, A; Gill, K; Glaefke, A; Goetz, E; Goetz, R; Gondan, L; Gonz'alez, G; Castro, J M Gonzalez; Gopakumar, A; Gordon, N A; Gorodetsky, M L; Gossan, S E; Gosselin, M; Gouaty, R; Grado, A; Graef, C; Graff, P B; Granata, M; Grant, A; Gras, S; Gray, C; Greco, G; Green, A C; Groot, P; Grote, H; Grunewald, S; Guidi, G M; Guo, X; Gupta, A; Gupta, M K; Gushwa, K E; Gustafson, E K; Gustafson, R; Haas, R; Hacker, J J; Hall, B R; Hall, E D; Hammond, G; Haney, M; Hanke, M M; Hanks, J; Hanna, C; Hannam, M D; Hanson, J; Hardwick, T; Harms, J; Harry, G M; Harry, I W; Hart, M J; Hartman, M T; Haster, C -J; Haughian, K; Healy, J; Heidmann, A; Heintze, M C; Heitmann, H; Hello, P; Hemming, G; Hendry, M; Heng, I S; Hennig, J; Henry, J; Heptonstall, A W; Heurs, M; Hild, S; Hinder, I; Hoak, D; Hofman, D; Holt, K; Holz, D E; Hopkins, P; Hough, J; Houston, E A; Howell, E J; Hu, Y M; Huang, S; Huerta, E A; Huet, D; Hughey, B; Husa, S; Huttner, S H; Huynh-Dinh, T; Indik, N; Ingram, D R; Inta, R; Isa, H N; Isac, J -M; Isi, M; Isogai, T; Iyer, B R; Izumi, K; Jacqmin, T; Jang, H; Jani, K; Jaranowski, P; Jawahar, S; Jian, L; Jim'enez-Forteza, F; Johnson, W W; Johnson-McDaniel, N K; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalaghatgi, C V; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Kapadia, S J; Karki, S; Karvinen, K S; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, S; Kaur, T; Kawabe, K; K'ef'elian, F; Kehl, M S; Keitel, D; Kelley, D B; Kells, W; Kennedy, R; Key, J S; Khalili, F Y; Khan, I; Khan, S; Khan, Z; Khazanov, E A; Kijbunchoo, N; Kim, Chi-Woong; Kim, Chunglee; Kim, J; Kim, K; Kim, N; Kim, W; Kim, Y -M; Kimbrell, S J; King, E J; King, P J; Kissel, J S; Klein, B; Kleybolte, L; Klimenko, S; Koehlenbeck, S M; Koley, S; Kondrashov, V; Kontos, A; Korobko, M; Korth, W Z; Kowalska, I; Kozak, D B; Kringel, V; Krishnan, B; Kr'olak, A; Krueger, C; Kuehn, G; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Lackey, B D; Landry, M; Lange, J; Lantz, B; Lasky, P D; Laxen, M; Lazzarini, A; Lazzaro, C; Leaci, P; Leavey, S; Lebigot, E O; Lee, C H; Lee, H K; Lee, H M; Lee, K; Lenon, A; Leonardi, M; Leong, J R; Leroy, N; Letendre, N; Levin, Y; Lewis, J B; Li, T G F; Libson, A; Littenberg, T B; Lockerbie, N A; Lombardi, A L; London, L T; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lousto, C O; Lovelace, G; L"uck, H; Lundgren, A P; Lynch, R; Ma, Y; Machenschalk, B; MacInnis, M; Macleod, D M; Magana-Sandoval, F; Zertuche, L Magana; Magee, R M; Majorana, E; Maksimovic, I; Malvezzi, V; Man, N; Mandic, V; Mangano, V; Mansell, G L; Manske, M; Mantovani, M; Marchesoni, F; Marion, F; M'arka, S; M'arka, Z; Markosyan, A S; Maros, E; Martelli, F; Martellini, L; Martin, I W; Martynov, D V; Marx, J N; Mason, K; Masserot, A; Massinger, T J; Masso-Reid, M; Mastrogiovanni, S; Matichard, F; Matone, L; Mavalvala, N; Mazumder, N; McCarthy, R; McClelland, D E; McCormick, S; McGuire, S C; McIntyre, G; McIver, J; McManus, D J; McRae, T; McWilliams, S T; Meacher, D; Meadors, G D; Meidam, J; Melatos, A; Mendell, G; Mercer, R A; Merilh, E L; Merzougui, M; Meshkov, S; Messenger, C; Messick, C; Metzdorff, R; Meyers, P M; Mezzani, F; Miao, H; Michel, C; Middleton, H; Mikhailov, E E; Milano, L; Miller, A L; Miller, A; Miller, B B; Miller, J; Millhouse, M; Minenkov, Y; Ming, J; Mirshekari, S; Mishra, C; Mitra, S; Mitrofanov, V P; Mitselmakher, G; Mittleman, R; Moggi, A; Mohan, M; Mohapatra, S R P; Montani, M; Moore, B C; Moore, C J; Moraru, D; Moreno, G; Morriss, S R; Mossavi, K; Mours, B; Mow-Lowry, C M; Mueller, G; Muir, A W; Mukherjee, Arunava; Mukherjee, D; Mukherjee, S; Mukund, N; Mullavey, A; Munch, J; Murphy, D J; Murray, P G; Mytidis, A; Nardecchia, I; Naticchioni, L; Nayak, R K; Nedkova, K; Nelemans, G; Nelson, T J N; Neri, M; Neunzert, A; Newton, G; Nguyen, T T; Nielsen, A B; Nissanke, S; Nitz, A; Nocera, F; Nolting, D; Normandin, M E N; Nuttall, L K; Oberling, J; Ochsner, E; O'Dell, J; Oelker, E; Ogin, G H; Oh, J J; Oh, S H; Ohme, F; Oliver, M; Oppermann, P; Oram, Richard J; O'Reilly, B; O'Shaughnessy, R; Ottaway, D J; Overmier, H; Owen, B J; Pai, A; Pai, S A; Palamos, J R; Palashov, O; Palomba, C; Pal-Singh, A; Pan, H; Pankow, C; Pannarale, F; Pant, B C; Paoletti, F; Paoli, A; Papa, M A; Paris, H R; Parker, W; Pascucci, D; Pasqualetti, A; Passaquieti, R; Passuello, D; Patricelli, B; Patrick, Z; Pearlstone, B L; Pedraza, M; Pedurand, R; Pekowsky, L; Pele, A; Penn, S; Perreca, A; Perri, L M; Pfeiffer, H P; Phelps, M; Piccinni, O J; Pichot, M; Piergiovanni, F; Pierro, V; Pillant, G; Pinard, L; Pinto, I M; Pitkin, M; Poe, M; Poggiani, R; Popolizio, P; Post, A; Powell, J; Prasad, J; Predoi, V; Prestegard, T; Price, L R; Prijatelj, M; Principe, M; Privitera, S; Prix, R; Prodi, G A; Prokhorov, L; Puncken, O; Punturo, M; Puppo, P; P"urrer, M; Qi, H; Qin, J; Qiu, S; Quetschke, V; Quintero, E A; Quitzow-James, R; Raab, F J; Rabeling, D S; Radkins, H; Raffai, P; Raja, S; Rajan, C; Rakhmanov, M; Rapagnani, P; Raymond, V; Razzano, M; Re, V; Read, J; Reed, C M; Regimbau, T; Rei, L; Reid, S; Reitze, D H; Rew, H; Reyes, S D; Ricci, F; Riles, K; Rizzo, M; Robertson, N A; Robie, R; Robinet, F; Rocchi, A; Rolland, L; Rollins, J G; Roma, V J; Romano, J D; Romano, R; Romanov, G; Romie, J H; Rosi'nska, D; Rowan, S; R"udiger, A; Ruggi, P; Ryan, K; Sachdev, S; Sadecki, T; Sadeghian, L; Sakellariadou, M; Salconi, L; Saleem, M; Salemi, F; Samajdar, A; Sammut, L; Sanchez, E J; Sandberg, V; Sandeen, B; Sanders, J R; Sassolas, B; Sathyaprakash, B S; Saulson, P R; Sauter, O E S; Savage, R L; Sawadsky, A; Schale, P; Schilling, R; Schmidt, J; Schmidt, P; Schnabel, R; Schofield, R M S; Sch"onbeck, A; Schreiber, E; Schuette, D; Schutz, B F; Scott, J; Scott, S M; Sellers, D; Sengupta, A S; Sentenac, D; Sequino, V; Sergeev, A; Setyawati, Y; Shaddock, D A; Shaffer, T; Shahriar, M S; Shaltev, M; Shapiro, B; Shawhan, P; Sheperd, A; Shoemaker, D H; Shoemaker, D M; Siellez, K; Siemens, X; Sieniawska, M; Sigg, D; Silva, A D; Singer, A; Singer, L P; Singh, A; Singh, R; Singhal, A; Sintes, A M; Slagmolen, B J J; Smith, J R; Smith, N D; Smith, R J E; Son, E J; Sorazu, B; Sorrentino, F; Souradeep, T; Srivastava, A K; Staley, A; Steinke, M; Steinlechner, J; Steinlechner, S; Steinmeyer, D; Stephens, B C; Stevenson, S P; Stone, R; Strain, K A; Straniero, N; Stratta, G; Strauss, N A; Strigin, S; Sturani, R; Stuver, A L; Summerscales, T Z; Sun, L; Sunil, S; Sutton, P J; Swinkels, B L; Szczepa'nczyk, M J; Tacca, M; Talukder, D; Tanner, D B; T'apai, M; Tarabrin, S P; Taracchini, A; Taylor, R; Theeg, T; Thirugnanasambandam, M P; Thomas, E G; Thomas, M; Thomas, P; Thorne, K A; Thorne, K S; Thrane, E; Tiwari, S; Tiwari, V; Tokmakov, K V; Toland, K; Tomlinson, C; Tonelli, M; Tornasi, Z; Torres, C V; Torrie, C I; T"oyr"a, D; Travasso, F; Traylor, G; Trifir`o, D; Tringali, M C; Trozzo, L; Tse, M; Turconi, M; Tuyenbayev, D; Ugolini, D; Unnikrishnan, C S; Urban, A L; Usman, S A; Vahlbruch, H; Vajente, G; Valdes, G; Vallisneri, M; van Bakel, N; van Beuzekom, M; Brand, J F J van den; Broeck, C Van Den; Vander-Hyde, D C; van der Schaaf, L; van der Sluys, M V; van Heijningen, J V; Vano-Vinuales, A; van Veggel, A A; Vardaro, M; Vass, S; Vas'uth, M; Vaulin, R; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Verkindt, D; Vetrano, F; Vicer'e, A; Vinciguerra, S; Vine, D J; Vinet, J -Y; Vitale, S; Vo, T; Vocca, H; Vorvick, C; Voss, D V; Vousden, W D; Vyatchanin, S P; Wade, A R; Wade, L E; Wade, M; Walker, M; Wallace, L; Walsh, S; Wang, G; Wang, H; Wang, M; Wang, X; Wang, Y; Ward, R L; Warner, J; Was, M; Weaver, B; Wei, L -W; Weinert, M; Weinstein, A J; Weiss, R; Wen, L; Wessels, P; Westphal, T; Wette, K; Whelan, J T; Whiting, B F; Williams, R D; Williamson, A R; Willis, J L; Willke, B; Wimmer, M H; Winkler, W; Wipf, C C; Wittel, H; Woan, G; Woehler, J; Worden, J; Wright, J L; Wu, D S; Wu, G; Yablon, J; Yam, W; Yamamoto, H; Yancey, C C; Yu, H; Yvert, M; zny, A Zadro; Zangrando, L; Zanolin, M; Zendri, J -P; Zevin, M; Zhang, L; Zhang, M; Zhang, Y; Zhao, C; Zhou, M; Zhou, Z; Zhu, X J; Zucker, M E; Zuraw, S E; Zweizig, J
2016-01-01
This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) on September 14, 2015 [1]. Reference presented parameter estimation [2] of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom) and a 11-dimensional nonprecessing effective-one-body (EOB) model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR). Here we present new results that include a 15-dimensional precessing-spin waveform model (precessing EOBNR) developed within the EOB formalism. We find good agreement with the parameters estimated previously [2], and we quote updated component masses of $35^{+5}_{-3}\\mathrm{M}_\\odot$ and $30^{+3}_{-4}\\mathrm{M}_\\odot$ (where errors correspond to 90% symmetric credible intervals). We also present slightly tighter constraints on the dimensionless spin magnitudes of the two black holes, with a prima...
Harmonic arbitrary waveform generator
Energy Technology Data Exchange (ETDEWEB)
Roberts, Brock Franklin
2017-11-28
High frequency arbitrary waveforms have applications in radar, communications, medical imaging, therapy, electronic warfare, and charged particle acceleration and control. State of the art arbitrary waveform generators are limited in the frequency they can operate by the speed of the Digital to Analog converters that directly create their arbitrary waveforms. The architecture of the Harmonic Arbitrary Waveform Generator allows the phase and amplitude of the high frequency content of waveforms to be controlled without taxing the Digital to Analog converters that control them. The Harmonic Arbitrary Waveform Generator converts a high frequency input, into a precision, adjustable, high frequency arbitrary waveform.
Improved Analysis of GW150914 Using a Fully Spin-Precessing Waveform Model
Directory of Open Access Journals (Sweden)
2016-10-01
Full Text Available This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO in 2015 [Abbott et al. Phys. Rev. Lett. 116, 061102 (2016.]. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016.] presented parameter estimation of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom and an 11-dimensional nonprecessing effective-one-body (EOB model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR. Here, we present new results that include a 15-dimensional precessing-spin waveform model (precessing EOBNR developed within the EOB formalism. We find good agreement with the parameters estimated previously [Abbott et al. Phys. Rev. Lett. 116, 241102 (2016.], and we quote updated component masses of 35_{-3}^{+5} M_{⊙} and 30_{-4}^{+3} M_{⊙} (where errors correspond to 90% symmetric credible intervals. We also present slightly tighter constraints on the dimensionless spin magnitudes of the two black holes, with a primary spin estimate <0.65 and a secondary spin estimate <0.75 at 90% probability. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016.] estimated the systematic parameter-extraction errors due to waveform-model uncertainty by combining the posterior probability densities of precessing IMRPhenom and nonprecessing EOBNR. Here, we find that the two precessing-spin models are in closer agreement, suggesting that these systematic errors are smaller than previously quoted.
Directory of Open Access Journals (Sweden)
F. Pirotti
2013-10-01
Full Text Available For a correct use of metrics derived from processing of the full-waveform return signal from airborne laser scanner sensors any correlation which is not related to properties of the reflecting target must be known and, if possible, removed. In the following article we report on an analysis of correlation between several metrics extracted from the full-waveform return signal and scan characteristics (mainly range and type of land-cover (urban, grasslands, forests. The metrics taken in consideration are the amplitude, normalized amplitude, width (full width at half maximum, asymmetry indicators, left and right energy content, and the cross-section calculated from width and normalized amplitude considering the range effect. The results show that scan geometry in this case does not have a significant impact scans over forest cover, except for range affecting amplitude and width distribution. Over complex targets such as vegetation canopy, other factors such as incidence angle have little meaning, therefore corrections of range effect are the most meaningful. A strong correlation with the type of land-cover is also shown by the distribution of the values of the metrics in the different areas taken in consideration.
Piper, I R; Miller, J D
1995-06-01
Both laboratory and clinical trials have indicated the reliability of a new catheter-tip, strain-gauge intracranial pressure transducer. We report on the results of bench tests comparing the wave-form analysis capabilities of the new Codman intracranial pressure MicroSensor and a similar strain-gauge transducer. Good agreement was found between the two sensors with no significant nonlinearity or hysteresis over a measured pressure range from 0 to 100 mg Hg. Under "fluid-filled" conditions, the MicroSensor showed good reproduction of an arterial pressure wave form; when spectral analysis was used to analyze the two sensor types and break them down into harmonic components, no significant differences could be found for any of the first 10 amplitude and phase harmonics. If proven to stay robust after long-term clinical use, this sensor may be a useful alternative to the existing transducer systems for routinely monitoring the intracranial pressure and its wave form.
Kito, Minoru; Watanabe, Jumpei; Takeshita, Takaharu; Nishida, Yasuyuki
This paper presents an analysis of the steady and transient characteristics of capacitor-input-type diode rectifier circuits connected to a delta-star transformer in a three-phase rectangular-waveform distribution system. Equations are derived for the input current, output voltage, and total input power factor of the rectifier circuits. The total input power factor can be improved from 0.91 to 0.98 by using the delta-star transformer. Further, design methods are developed for both the input reactor and output capacitor of the rectifier circuits. A small input reactor is desirable for obtaining a large total input power factor and a constant output voltage. The output capacitor can be designed to obtain the required output voltage variation in steady and transient states. The effectiveness of the proposed analysis is experimentally verified by using a 2.4kW prototype.
Wang, Feng; Yang, Dongkai; Zhang, Bo; Li, Weiqiang
2018-03-01
This paper explores two types of mathematical functions to fit single- and full-frequency waveform of spaceborne Global Navigation Satellite System-Reflectometry (GNSS-R), respectively. The metrics of the waveforms, such as the noise floor, peak magnitude, mid-point position of the leading edge, leading edge slope and trailing edge slope, can be derived from the parameters of the proposed models. Because the quality of the UK TDS-1 data is not at the level required by remote sensing mission, the waveforms buried in noise or from ice/land are removed by defining peak-to-mean ratio, cosine similarity of the waveform before wind speed are retrieved. The single-parameter retrieval models are developed by comparing the peak magnitude, leading edge slope and trailing edge slope derived from the parameters of the proposed models with in situ wind speed from the ASCAT scatterometer. To improve the retrieval accuracy, three types of multi-parameter observations based on the principle component analysis (PCA), minimum variance (MV) estimator and Back Propagation (BP) network are implemented. The results indicate that compared to the best results of the single-parameter observation, the approaches based on the principle component analysis and minimum variance could not significantly improve retrieval accuracy, however, the BP networks obtain improvement with the RMSE of 2.55 m/s and 2.53 m/s for single- and full-frequency waveform, respectively.
The OSCAR experiment: using full-waveform inversion in the analysis of young oceanic crust
Silverton, Akela; Morgan, Joanna; Wilson, Dean; Hobbs, Richard
2017-04-01
The OSCAR experiment aims to derive an integrated model to better explain the effects of heat loss and alteration by hydrothermal fluids, associated with the cooling of young oceanic crust at an axial ridge. High-resolution seismic imaging of the sediments and basaltic basement can be used to map fluid flow pathways between the oceanic crust and the surrounding ocean. To obtain these high-resolution images, we undertake full-waveform inversion (FWI), an advanced seismic imaging technique capable of resolving velocity heterogeneities at a wide range of length scales, from background trends to fine-scale geological/crustal detail, in a fully data-driven automated manner. This technology is widely used within the petroleum sector due to its potential to obtain high-resolution P-wave velocity models that lead to improvements in migrated seismic images of the subsurface. Here, we use the P-wave velocity model obtained from travel-time tomography as the starting model in the application of acoustic, time-domain FWI to a multichannel streamer field dataset acquired in the east Pacific along a profile between the Costa Rica spreading centre and the Ocean Drilling Program (ODP) borehole 504B, where the crust is approximately six million years old. FWI iteratively improves the velocity model by minimizing the misfit between the predicted data and the field data. It seeks to find a high-fidelity velocity model that is capable of matching individual seismic waveforms of the original raw field dataset, with an initial focus on matching the low-frequency components of the early arriving energy. Quality assurance methods adopted during the inversion ensure convergence in the direction of the global minimum. We demonstrate that FWI is able to recover fine-scale, high-resolution velocity heterogeneities within the young oceanic crust along the profile. The highly resolved FWI velocity model is useful in the identification of the layer 2A/2B interface and low-velocity layers that
Full Waveform Analysis for Long-Range 3D Imaging Laser Radar
Directory of Open Access Journals (Sweden)
Wallace AndrewM
2010-01-01
Full Text Available The new generation of 3D imaging systems based on laser radar (ladar offers significant advantages in defense and security applications. In particular, it is possible to retrieve 3D shape information directly from the scene and separate a target from background or foreground clutter by extracting a narrow depth range from the field of view by range gating, either in the sensor or by postprocessing. We discuss and demonstrate the applicability of full-waveform ladar to produce multilayer 3D imagery, in which each pixel produces a complex temporal response that describes the scene structure. Such complexity caused by multiple and distributed reflection arises in many relevant scenarios, for example in viewing partially occluded targets, through semitransparent materials (e.g., windows and through distributed reflective media such as foliage. We demonstrate our methodology on 3D image data acquired by a scanning time-of-flight system, developed in our own laboratories, which uses the time-correlated single-photon counting technique.
Sensitivity analysis for elastic full-waveform inversion in VTI media
Kamath, Nishant
2014-08-05
Multiparameter full-waveform inversion (FWI) is generally nonunique, and the results are strongly influenced by the geometry of the experiment and the type of recorded data. Studying the sensitivity of different subsets of data to the model parameters may help in choosing an optimal acquisition design, inversion workflow, and parameterization. Here, we derive the Fréchet kernel for FWI of multicomponent data from a 2D VTI (tranversely isotropic with a vertical symmetry axis) medium. The kernel is obtained by linearizing the elastic wave equation using the Born approximation and employing the asymptotic Green\\'s function. The amplitude of the kernel (‘radiation pattern’) yields the angle-dependent energy scattered by a perturbation in a certain model parameter. The perturbations are described in terms of the P- and S-wave vertical velocities and the P-wave normal-moveout and horizontal velocities. The background medium is assumed to be homogeneous and isotropic, which allows us to obtain simple expressions for the radiation patterns corresonding to all four velocities. These patterns help explain the FWI results for multicomponent transmission data generated for Gaussian anomalies in the Thomsen parameters inserted into a homogeneous VTI medium.
Directory of Open Access Journals (Sweden)
Florian Schumacher
2016-01-01
Full Text Available Due to increasing computational resources, the development of new numerically demanding methods and software for imaging Earth’s interior remains of high interest in Earth sciences. Here, we give a description from a user’s and programmer’s perspective of the highly modular, flexible and extendable software package ASKI–Analysis of Sensitivity and Kernel Inversion–recently developed for iterative scattering-integral-based seismic full waveform inversion. In ASKI, the three fundamental steps of solving the seismic forward problem, computing waveform sensitivity kernels and deriving a model update are solved by independent software programs that interact via file output/input only. Furthermore, the spatial discretizations of the model space used for solving the seismic forward problem and for deriving model updates, respectively, are kept completely independent. For this reason, ASKI does not contain a specific forward solver but instead provides a general interface to established community wave propagation codes. Moreover, the third fundamental step of deriving a model update can be repeated at relatively low costs applying different kinds of model regularization or re-selecting/weighting the inverted dataset without need to re-solve the forward problem or re-compute the kernels. Additionally, ASKI offers the user sensitivity and resolution analysis tools based on the full sensitivity matrix and allows to compose customized workflows in a consistent computational environment. ASKI is written in modern Fortran and Python, it is well documented and freely available under terms of the GNU General Public License (http://www.rub.de/aski.
Yedlin, M. J.; Ben Horin, Y.; Kitov, I. O.; Margrave, G. F.; Rozhkov, M.
2016-12-01
We have collected and processed 1654 Jordan Phosphate Mines quarry blast waveforms recorded by the three component (3-C) station HRFI. Judging by satellite images taken for the same period, the largest spacing between these blasts might exceed 20 km while their seismic (ML) magnitudes vary in the range from 2 to 3. We have selected short waveform segments (8 min.) for each of 1654 signals, and aligned all waveforms to the Pn-wave arrival times as picked by the same detection procedure based on the STA/LTA threshold. For each event, we have created a waveform template. These waveform templates were obtained by appropriate bandpass filtering, with bands chosen heuristically by examining a spectrogram movie constructed from a subset of the data. We cross-correlated 1654x1654 waveform-template pairs in order to estimate the level of similarity between the measured signals as expressed by cross-correlation coefficient (CC). As a result of the cross-correlation procedure, a CC time series is created to which we apply standard STA/LTA detector with the same threshold as for the original waveforms to find arrival times in the CC domain. When only the Z-component is used for CC, the best four 12.5 s long templates can find all other 1653 signals. For 3-C records, there are 119 templates which can find all other signals and these observations highlight the importance of 3-C records for the performance of the waveform cross-correlation (WCC) technique. It is also found that longer templates result in lower cross-correlation because of larger difference in the shape of S-waves. To characterize the overall similarity of the whole set, we have used the Principal Component Analysis (PCA) as based on the Singular Value Decomposition technique. We have demonstrated that the level of eigenvalues falls to 0.2 for the first fifteen components and the first five components are able to find all 1654 signals when WCC is applied. Therefore, the first component obtained by SVD may serve as
Directory of Open Access Journals (Sweden)
Ole Broch
2012-01-01
Full Text Available Uncalibrated semi-invasive continous monitoring of cardiac index (CI has recently gained increasing interest. The aim of the present study was to compare the accuracy of CI determination based on arterial waveform analysis with transpulmonary thermodilution. Fifty patients scheduled for elective coronary surgery were studied after induction of anaesthesia and before and after cardiopulmonary bypass (CPB, respectively. Each patient was monitored with a central venous line, the PiCCO system, and the FloTrac/Vigileo-system. Measurements included CI derived by transpulmonary thermodilution and uncalibrated semi-invasive pulse contour analysis. Percentage changes of CI were calculated. There was a moderate, but significant correlation between pulse contour CI and thermodilution CI both before (2=0.72, <0.0001 and after (2=0.62, <0.0001 CPB, with a percentage error of 31% and 25%, respectively. Changes in pulse contour CI showed a significant correlation with changes in thermodilution CI both before (2=0.52, <0.0001 and after (2=0.67, <0.0001 CPB. Our findings demonstrated that uncalibrated semi-invasive monitoring system was able to reliably measure CI compared with transpulmonary thermodilution in patients undergoing elective coronary surgery. Furthermore, the semi-invasive monitoring device was able to track haemodynamic changes and trends.
An MCMC-based waveform analysis with p-type point contact detectors in the MAJORANA DEMONSTRATOR
Shanks, Benjamin; MAJORANA Collaboration
2017-01-01
Statistical signal processing can be a powerful tool for extracting as much information as possible from raw data. By fitting data to a physical model of signal generation on an event-by-event basis, it can be used to perform precise event reconstruction and enable efficient background rejection. Searches for neutrinoless double-beta decay must achieve extremely low backgrounds to reach sensitivities required for discovery, and so can benefit greatly from this analysis technique. The MAJORANA DEMONSTRATOR has implemented a Markov Chain Monte Carlo (MCMC) signal processing algorithm to fit waveforms from p-type point contact (PPC) germanium detectors. After a machine learning step to tune detector fields and electronics response parameters, the MCMC algorithm is able to reconstruct the time, energy and position of interactions within the PPC detector. The parameters estimated with this method will find many applications within the DEMONSTRATOR physics program, including background identification and rejection. This will prove important as the DEMONSTRATOR aims to reach its background goal of < 3 counts/tonne/yr in the region of interest. This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.
Acoustic impact testing and waveform analysis for damage detection in glued laminated timber
Feng Xu; Xiping Wang; Marko Teder; Yunfei Liu
2017-01-01
Delamination and decay are common structural defects in old glued laminated timber (glulam) buildings, which, if left undetected, could cause severe structural damage. This paper presents a new damage detection method for glulam inspection based on moment analysis and wavelet transform (WT) of impact acoustic signals. Acoustic signals were collected from a glulam arch...
Arterial waveform-analysis is of limited value in daily clinical practice in the intensive care unit
DEFF Research Database (Denmark)
Hennings, Louise Inkeri; Haase, Nicolai; Pedersen, Ulf Gøttrup
2015-01-01
INTRODUCTION: It is difficult to identify the patients who will respond to fluid therapy, but the arterial waveform-derived variables have reasonably predictive values for fluid responsiveness. However, the patient must fulfil a number of prerequisites for these variables to be valid. We assessed...... the proportion of intensive care unit (ICU) patients with shock who at the time of resuscitation fulfilled the prerequisites for using the arterial waveform-derived variables. METHODS: This was a prospective cohort study performed at six ICUs. The study included consecutive adult patients with shock (20 patients...... of arterial waveform-derived variables to predict fluid responsiveness. Thus, these variables may be of limited use during resuscitation in the ICU. FUNDING: none. TRIAL REGISTRATION: not relevant....
Arterial waveform-analysis is of limited value in daily clinical practice in the intensive care unit
DEFF Research Database (Denmark)
Henningsen, Louise; Haase, Nicolai; Pedersen, Ulf Gøttrup
2015-01-01
INTRODUCTION: It is difficult to identify the patients who will respond to fluid therapy, but the arterial waveform-derived variables have reasonably predictive values for fluid responsiveness. However, the patient must fulfil a number of prerequisites for these variables to be valid. We assessed...... the proportion of intensive care unit (ICU) patients with shock who at the time of resuscitation fulfilled the prerequisites for using the arterial waveform-derived variables. METHODS: This was a prospective cohort study performed at six ICUs. The study included consecutive adult patients with shock (20 patients...... of arterial waveform-derived variables to predict fluid responsiveness. Thus, these variables may be of limited use during resuscitation in the ICU....
Arterial waveform-analysis is of limited value in daily clinical practice in the intensive care unit
DEFF Research Database (Denmark)
Hennings, Louise Inkeri; Haase, Nicolai; Pedersen, Ulf Gøttrup
2015-01-01
INTRODUCTION: It is difficult to identify the patients who will respond to fluid therapy, but the arterial waveform-derived variables have reasonably predictive values for fluid responsiveness. However, the patient must fulfil a number of prerequisites for these variables to be valid. We assessed...... the proportion of intensive care unit (ICU) patients with shock who at the time of resuscitation fulfilled the prerequisites for using the arterial waveform-derived variables. METHODS: This was a prospective cohort study performed at six ICUs. The study included consecutive adult patients with shock (20 patients...
Human processing of short temporal intervals as revealed by an ERP waveform analysis
Directory of Open Access Journals (Sweden)
Yoshitaka eNakajima
2011-12-01
Full Text Available To clarify the time course over which the human brain processes information about durations up to ~300 ms, we reanalyzed the data that were previously reported by Mitsudo et al. (2009 using a multivariate analysis method. Event-related potentials were recorded from 19 scalp electrodes on 11 (9 original and 2 additional participants while they judged whether two neighboring empty time intervals—called t1 and t2 and marked by three tone bursts—had equal durations. There was also a control condition in which the participants were presented the same temporal patterns but without a judgment task. In the present reanalysis, we sought to visualize how the temporal patterns were represented in the brain over time. A correlation matrix across channels was calculated for each temporal pattern. Geometric separations between the correlation matrices were calculated, and subjected to multidimensional scaling. We performed such analyses for a moving 100-ms time window after the t1 presentations. In the windows centered at < 100 ms after the t2 presentation, the analyses revealed the local maxima of categorical separation between temporal patterns of perceptually equal durations versus perceptually unequal durations, both in the judgment condition and in the control condition. Such categorization of the temporal patterns was prominent only in narrow temporal regions. The analysis indicated that the participants determined whether the two neighboring time intervals were of equal duration mostly within 100 ms after the presentation of the temporal patterns. A very fast brain activity was related to the perception of elementary temporal patterns without explicit judgments. This is consistent with the findings of Mitsudo et al., and it is in line with the processing time hypothesis proposed by Nakajima et al. (2004. The validity of the correlation matrix analyses turned out to be an effective tool to grasp the overall responses of the brain to temporal
Haku, J; Nogami, K; Matsumoto, T; Ogiwara, K; Shima, M
2014-01-01
Assays to determine the optimal hemostatic effects of bypass therapy in hemophilia A (HA) patients with inhibitors are difficult to compare. Clot waveform analysis (CWA), based on the continuous monitoring of routine coagulation parameters (prothrombin time/activated partial thromboplastin time), offers a useful method for assessing global clotting function. To investigate the technique of CWA for the hemostatic monitoring of bypass therapy in HA patients with inhibitors. Ellagic acid (Elg), tissue factor (TF) or both (Elg/TF) were used as trigger reagents in CWA. The standard parameters - clot time (CT), maximum coagulation velocity (|min1|), and acceleration (|min2|) - were recorded. Optimal monitoring was defined as: (i) a significant difference in these parameters between plasma from HA patients with inhibitors and normal plasmas; and (ii) a significant improvement in these indices in HA patients with inhibitors after bypass therapy. Experiments in vitro demonstrated that there were significant differences between plasma from HA patients with inhibitors and normal plasma with various triggers, in the order Elg > Elg/TF > TF. Addition of therapeutically achievable concentrations of bypassing agents, however, showed significant improvements in the different parameters only with Elg/TF, suggesting that this reagent provided the most appropriate assay. A total of 20 plasmas from HA patients with inhibitors in which bypassing agents were infused were evaluated ex vivo by Elg/TF CWA. The postinfusion parameters CT and |min2| reflected clinical effects, and were close to normal levels. Furthermore, Elg/TF CWA facilitated quantitative evaluation of perioperative hemostatic management of bypass therapy in HA patients with inhibitors. CWA is a promising method for the quantitative monitoring of bypass therapy during routine automated clotting assays with a modified trigger reagent comprising a well-balanced mixture of Elg and TF. © 2013 International Society on
Directory of Open Access Journals (Sweden)
Norbert Pfeifer
2008-08-01
Full Text Available Airborne laser scanning (ALS is a remote sensing technique well-suited for 3D vegetation mapping and structure characterization because the emitted laser pulses are able to penetrate small gaps in the vegetation canopy. The backscattered echoes from the foliage, woody vegetation, the terrain, and other objects are detected, leading to a cloud of points. Higher echo densities (> 20 echoes/m2 and additional classification variables from full-waveform (FWF ALS data, namely echo amplitude, echo width and information on multiple echoes from one shot, offer new possibilities in classifying the ALS point cloud. Currently FWF sensor information is hardly used for classification purposes. This contribution presents an object-based point cloud analysis (OBPA approach, combining segmentation and classification of the 3D FWF ALS points designed to detect tall vegetation in urban environments. The definition tall vegetation includes trees and shrubs, but excludes grassland and herbage. In the applied procedure FWF ALS echoes are segmented by a seeded region growing procedure. All echoes sorted descending by their surface roughness are used as seed points. Segments are grown based on echo width homogeneity. Next, segment statistics (mean, standard deviation, and coefficient of variation are calculated by aggregating echo features such as amplitude and surface roughness. For classification a rule base is derived automatically from a training area using a statistical classification tree. To demonstrate our method we present data of three sites with around 500,000 echoes each. The accuracy of the classified vegetation segments is evaluated for two independent validation sites. In a point-wise error assessment, where the classification is compared with manually classified 3D points, completeness and correctness better than 90% are reached for the validation sites. In comparison to many other algorithms the proposed 3D point classification works on the original
Keenan, Daniel M; Roelfsema, Ferdinand; Biermasz, Nienke; Veldhuis, Johannes D
2003-09-01
The present study investigates the time-varying control of pituitary hormone secretion over the day and night (D/N). To this end, we implemented an analytical platform designed to reconstruct simultaneously 1) basal (nonpulsatile) secretion, 2) single or dual secretory-burst waveforms, 3) random effects on burst amplitude, 4) stochastic pulse-renewal properties, 5) biexponential elimination kinetics, and 6) experimental uncertainty. The statistical solution is conditioned on a priori pulse-onset times, which are estimated in the first stage. Primary data composed of thyrotropin (TSH) concentrations were monitored over 24 h in 27 healthy adults. According to statistical criteria, 21/27 profiles favored a dual compared with single secretory-burst waveform. An objectively defined waveform change point (D/N boundary) emerged at 2046 (+/-23 min), after which 1) the mass of TSH released per burst increases by 2.1-fold (P process. Further studies will be required to assess the generality of the foregoing distinctive control mechanisms in other hypothalamo-pituitary axes.
Zhang, Dongliang
2013-01-01
To increase the illumination of the subsurface and to eliminate the dependency of FWI on the source wavelet, we propose multiples waveform inversion (MWI) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. These virtual sources are used to numerically generate downgoing wavefields that are correlated with the backprojected surface-related multiples to give the migration image. Since the recorded data are treated as the virtual sources, knowledge of the source wavelet is not required, and the subsurface illumination is greatly enhanced because the entire free surface acts as an extended source compared to the radiation pattern of a traditional point source. Numerical tests on the Marmousi2 model show that the convergence rate and the spatial resolution of MWI is, respectively, faster and more accurate then FWI. The potential pitfall with this method is that the multiples undergo more than one roundtrip to the surface, which increases attenuation and reduces spatial resolution. This can lead to less resolved tomograms compared to conventional FWI. The possible solution is to combine both FWI and MWI in inverting for the subsurface velocity distribution.
Meldrum, Dara; Shouldice, Ciara; Conroy, Ronan; Jones, Kim; Forward, Malcolm
2014-01-01
Estimating the measurement error (reliability) of three dimensional gait analysis (3DGA) is crucial to interpretation of gait data. The purpose of this study was to investigate the intra-rater reliability of 3DGA and apply a novel method of visualising reliability of gait cycle waveforms. A test re-test design was employed. A convenience sample of 30 healthy adults (18F; 12 M: mean age 30 ± 6.8 years) participated. Subjects walked along a 10 m walkway at their preferred gait speed and 3DGA data were collected using a VICON(®) 3DGA system. Testing was performed by the same investigator on two separate days within two weeks. Data from 10 trials were averaged and analysed. The intraclass correlation coefficient (ICC), the standard error of measurement (SEM), minimal detectable change (MDC) and limits of agreement were calculated for kinetic and kinematic data. Bland and Altman plots were applied to gait cycle waveforms. Spatio-temporal parameters such as cadence, step length, velocity, step time and step width were highly repeatable generating ICC's of 0.90 and above and low SEM/MDC. Range of joint movement across the gait cycle was generally more reliable than either minimum or maximum values and higher ICCs were obtained for movement in the sagittal plane. For kinematic data the standard error of measurement was low (≤ 5) for the majority of parameters. Transverse plane measurements showed poor reliability with lowest ICC's. ICCs for kinetic data ranged from 0.51 to 0.81. Reliability of 3DGA has been estimated for our gait laboratory. Bland and Altman plots of gait cycle waveforms provide a useful addition to reliability analysis. Copyright © 2013 Elsevier B.V. All rights reserved.
Schumacher, F.; Friederich, W.
2015-12-01
We present the modularized software package ASKI which is a flexible and extendable toolbox for seismic full waveform inversion (FWI) as well as sensitivity or resolution analysis operating on the sensitivity matrix. It utilizes established wave propagation codes for solving the forward problem and offers an alternative to the monolithic, unflexible and hard-to-modify codes that have typically been written for solving inverse problems. It is available under the GPL at www.rub.de/aski. The Gauss-Newton FWI method for 3D-heterogeneous elastic earth models is based on waveform sensitivity kernels and can be applied to inverse problems at various spatial scales in both Cartesian and spherical geometries. The kernels are derived in the frequency domain from Born scattering theory as the Fréchet derivatives of linearized full waveform data functionals, quantifying the influence of elastic earth model parameters on the particular waveform data values. As an important innovation, we keep two independent spatial descriptions of the earth model - one for solving the forward problem and one representing the inverted model updates. Thereby we account for the independent needs of spatial model resolution of forward and inverse problem, respectively. Due to pre-integration of the kernels over the (in general much coarser) inversion grid, storage requirements for the sensitivity kernels are dramatically reduced.ASKI can be flexibly extended to other forward codes by providing it with specific interface routines that contain knowledge about forward code-specific file formats and auxiliary information provided by the new forward code. In order to sustain flexibility, the ASKI tools must communicate via file output/input, thus large storage capacities need to be accessible in a convenient way. Storing the complete sensitivity matrix to file, however, permits the scientist full manual control over each step in a customized procedure of sensitivity/resolution analysis and full
Data mining technique for fast retrieval of similar waveforms in Fusion massive databases
Energy Technology Data Exchange (ETDEWEB)
Vega, J. [Asociacion EURATOM/CIEMAT Para Fusion, Madrid (Spain)], E-mail: jesus.vega@ciemat.es; Pereira, A.; Portas, A. [Asociacion EURATOM/CIEMAT Para Fusion, Madrid (Spain); Dormido-Canto, S.; Farias, G.; Dormido, R.; Sanchez, J.; Duro, N. [Departamento de Informatica y Automatica, UNED, Madrid (Spain); Santos, M. [Departamento de Arquitectura de Computadores y Automatica, UCM, Madrid (Spain); Sanchez, E. [Asociacion EURATOM/CIEMAT Para Fusion, Madrid (Spain); Pajares, G. [Departamento de Arquitectura de Computadores y Automatica, UCM, Madrid (Spain)
2008-01-15
Fusion measurement systems generate similar waveforms for reproducible behavior. A major difficulty related to data analysis is the identification, in a rapid and automated way, of a set of discharges with comparable behaviour, i.e. discharges with 'similar' waveforms. Here we introduce a new technique for rapid searching and retrieval of 'similar' signals. The approach consists of building a classification system that avoids traversing the whole database looking for similarities. The classification system diminishes the problem dimensionality (by means of waveform feature extraction) and reduces the searching space to just the most probable 'similar' waveforms (clustering techniques). In the searching procedure, the input waveform is classified in any of the existing clusters. Then, a similarity measure is computed between the input signal and all cluster elements in order to identify the most similar waveforms. The inner product of normalized vectors is used as the similarity measure as it allows the searching process to be independent of signal gain and polarity. This development has been applied recently to TJ-II stellarator databases and has been integrated into its remote participation system.
Modelling transthoracic defibrillation waveforms.
Krasteva, V; Cansell, A; Daskalov, I
2000-01-01
Recent investigations connected with implantable defibrillators yielded new data on heart electrophysiology, resulting in reassessment of existing and advancing of new types of electrical impulses. Different electrical equivalent circuits were proposed for modelling intracardiac and transthoracic defibrillation pulse waveforms, comprising generator, electrode interface and tissue resistances. We attempted modelling of the transmembrane voltage Vm time course, induced by different applied voltage Vs waveforms, taking into account only the shapes and the relative Vs and Vm amplitudes. The excitable cell membrane impedance Zm was modelled with higher resistance and lower capacitance, so that a shunting effect on the generator and tissue resistances was avoided. The result was a very simple equivalent circuit. We proposed criteria for efficient defibrillation pulse waveforms yielding a straightforward approach to model existing and new pulses and to assess their efficiency.
Grevemeyer, Ingo; Lange, Dietrich; Schippkus, Sven
2016-04-01
The lithosphere is the outermost solid layer of the Earth and includes the brittle curst and brittle uppermost mantle. It is underlain by the asthenosphere, the weaker and hotter portion of the mantle. The boundary between the brittle lithosphere and the asthenosphere is call the lithosphere-asthenosphere boundary, or LAB. The oceanic lithosphere is created at spreading ridges and cools and thickens with age. Seismologists define the LAB by the presence of a low shear wave velocity zone beneath a high velocity lid. Surface waves from earthquakes occurring in young oceanic lithosphere should sample lithospheric structure when being recorded in the vicinity of a mid-ocean ridge. Here, we study group velocity and dispersion of Rayleigh waves caused by earthquakes occurring at transform faults in the Central Atlantic Ocean. Earthquakes were recorded either by a network of wide-band (up to 60 s) ocean-bottom seismometers (OBS) deployed at the Mid-Atlantic Ridge near 15°N or at the Global Seismic Network (GSN) Station ASCN on Ascension Island. Surface waves sampling young Atlantic lithosphere indicate systematic age-dependent changes of group velocities and dispersion of Rayleigh waves. With increasing plate age maximum group velocity increases (as a function of period), indicating cooling and thickening of the lithosphere. Shear wave velocity is derived inverting the observed dispersion of Rayleigh waves. Further, models derived from the OBS records were refined using waveform modelling of vertical component broadband data at periods of 15 to 40 seconds, constraining the velocity structure of the uppermost 100 km and hence in the depth interval of the mantle where lithospheric cooling is most evident. Waveform modelling supports that the thickness of lithosphere increases with age and that velocities in the lithosphere increase, too.
Facies Constrained Elastic Full Waveform Inversion
Zhang, Z.
2017-05-26
Current efforts to utilize full waveform inversion (FWI) as a tool beyond acoustic imaging applications, for example for reservoir analysis, face inherent limitations on resolution and also on the potential trade-off between elastic model parameters. Adding rock physics constraints does help to mitigate these issues. However, current approaches to add such constraints are based on averaged type rock physics regularization terms. Since the true earth model consists of different facies, averaging over those facies naturally leads to smoothed models. To overcome this, we propose a novel way to utilize facies based constraints in elastic FWI. A so-called confidence map is calculated and updated at each iteration of the inversion using both the inverted models and the prior information. The numerical example shows that the proposed method can reduce the cross-talks and also can improve the resolution of inverted elastic properties.
A novel PMT test system based on waveform sampling
Yin, S.; Ma, L.; Ning, Z.; Qian, S.; Wang, Y.; Jiang, X.; Wang, Z.; Yu, B.; Gao, F.; Zhu, Y.; Wang, Z.
2018-01-01
Comparing with the traditional test system based on a QDC and TDC and scaler, a test system based on waveform sampling is constructed for signal sampling of the 8"R5912 and the 20"R12860 Hamamatsu PMT in different energy states from single to multiple photoelectrons. In order to achieve high throughput and to reduce the dead time in data processing, the data acquisition software based on LabVIEW is developed and runs with a parallel mechanism. The analysis algorithm is realized in LabVIEW and the spectra of charge, amplitude, signal width and rising time are analyzed offline. The results from Charge-to-Digital Converter, Time-to-Digital Converter and waveform sampling are discussed in detailed comparison.
Gaussian Decomposition of Laser Altimeter Waveforms
Hofton, Michelle A.; Minster, J. Bernard; Blair, J. Bryan
1999-01-01
We develop a method to decompose a laser altimeter return waveform into its Gaussian components assuming that the position of each Gaussian within the waveform can be used to calculate the mean elevation of a specific reflecting surface within the laser footprint. We estimate the number of Gaussian components from the number of inflection points of a smoothed copy of the laser waveform, and obtain initial estimates of the Gaussian half-widths and positions from the positions of its consecutive inflection points. Initial amplitude estimates are obtained using a non-negative least-squares method. To reduce the likelihood of fitting the background noise within the waveform and to minimize the number of Gaussians needed in the approximation, we rank the "importance" of each Gaussian in the decomposition using its initial half-width and amplitude estimates. The initial parameter estimates of all Gaussians ranked "important" are optimized using the Levenburg-Marquardt method. If the sum of the Gaussians does not approximate the return waveform to a prescribed accuracy, then additional Gaussians are included in the optimization procedure. The Gaussian decomposition method is demonstrated on data collected by the airborne Laser Vegetation Imaging Sensor (LVIS) in October 1997 over the Sequoia National Forest, California.
Directory of Open Access Journals (Sweden)
Sohel Rana
2014-01-01
Full Text Available Non-Fourier heat conduction model with dual phase lag wave-diffusion model was analyzed by using well-conditioned asymptotic wave evaluation (WCAWE and finite element method (FEM. The non-Fourier heat conduction has been investigated where the maximum likelihood (ML and Tikhonov regularization technique were used successfully to predict the accurate and stable temperature responses without the loss of initial nonlinear/high frequency response. To reduce the increased computational time by Tikhonov WCAWE using ML (TWCAWE-ML, another well-conditioned scheme, called mass effect (ME T-WCAWE, is introduced. TWCAWE with ME (TWCAWE-ME showed more stable and accurate temperature spectrum in comparison to asymptotic wave evaluation (AWE and also partial Pade AWE without sacrificing the computational time. However, the TWCAWE-ML remains as the most stable and hence accurate model to analyze the fast transient thermal analysis of non-Fourier heat conduction model.
Rana, Sohel; Kanesan, Jeevan; Reza, Ahmed Wasif; Ramiah, Harikrishnan
2014-01-01
Non-Fourier heat conduction model with dual phase lag wave-diffusion model was analyzed by using well-conditioned asymptotic wave evaluation (WCAWE) and finite element method (FEM). The non-Fourier heat conduction has been investigated where the maximum likelihood (ML) and Tikhonov regularization technique were used successfully to predict the accurate and stable temperature responses without the loss of initial nonlinear/high frequency response. To reduce the increased computational time by Tikhonov WCAWE using ML (TWCAWE-ML), another well-conditioned scheme, called mass effect (ME) T-WCAWE, is introduced. TWCAWE with ME (TWCAWE-ME) showed more stable and accurate temperature spectrum in comparison to asymptotic wave evaluation (AWE) and also partial Pade AWE without sacrificing the computational time. However, the TWCAWE-ML remains as the most stable and hence accurate model to analyze the fast transient thermal analysis of non-Fourier heat conduction model.
Tam, Nicholas; Prins, Danielle; Divekar, Nikhil V; Lamberts, Robert P
2017-10-01
The aim of this study was to utilise one-dimensional statistical parametric mapping to compare differences between biomechanical and electromyographical waveforms in runners when running in barefoot or shod conditions. Fifty habitually shod runners were assessed during overground running at their current 10-km race running speed. Electromyography, kinematics and ground reaction forces were collected during these running trials. Joint kinetics were calculated using inverse dynamics. One-dimensional statistical parametric mapping one sample t-test was conducted to assess differences over an entire gait cycle on the variables of interest when barefoot or shod (pgait cycle) and swing phase (74-90%); at the ankle early stance (0-6%), mid-stance (28-38%) and swing phase (81-100%). Differences in sagittal plane moments were also found at the ankle during early stance (2, 4-5%) and knee during early stance (5-11%). Condition differences were also found in vertical ground reaction force during early stance between (3-10%). An acute bout of barefoot running in habitual shod runners invokes temporal differences throughout the gait cycle. Specifically, a co-ordinative responses between the knee and ankle joint in the sagittal plane with a delay in the impact transient peak; onset of the knee extension and ankle plantarflexion moment in the shod compared to barefoot condition was found. This appears to affect the delay in knee extension and ankle plantarflexion during late stance. This study provides a glimpse into the co-ordination of the lower limb when running in differing footwear. Copyright © 2017 Elsevier B.V. All rights reserved.
Bizarre Waveforms in Strong Motion Records
Directory of Open Access Journals (Sweden)
Baofeng Zhou
2015-01-01
Full Text Available This paper collects a rich set of strong motion records in some typical earthquakes domestic and abroad, checks its seismic events, converts the data format, corrects the zeroline and draws the waveform. Four kinds of abnormal phenomena on the acceleration waveform are revealed, such as spike, asymmetric waveform, obvious baseline drift, and strong motion records packets separation. Then reasonable processing approaches are derived from the preliminary analysis of the generation mechanism for abnormal phenomena. In addition to the effects on time history, Fourier amplitude spectrum and response spectrum are studied before and after strong motion records correction. It is shown that (1 mechanism of spikes is rather complicated; however spikes can be eliminated by “jerk” method, ratio method, and the consistency of the three-component PGA time; (2 mechanism of the asymmetric waveform is of diversity; however, to some extent, the Butterworth low-pass filtering can be applied to correct it; (3 two pieces of strong motion record packets can be connected by searching continuous and repeated data; (4 the method of cumulative adding can be used to find the clear baseline drift; (5 the abnormal waveform directly affects the characteristics of time history and frequency spectrum.
Rietbrock, A.; Hicks, S. P.; Chagas, B.; Detzel, H. A.
2014-12-01
slip style can be highly variable across the megathrust, with implications for fault processes such as postseismic fluid release. We also perform 3-D full waveform forward simulation using the spectral element code, SPECFEM3D, to understand the sensitivity of our moment tensor solutions with respect to 3-D velocity structure.
Ventilator waveform interpretation in mechanically ventilated small animals.
Corona, Terry M; Aumann, Marcel
2011-10-01
To review the topic of ventilator waveforms analysis with emphasis on interpretation of ventilator waveforms and their use in the management and monitoring of mechanically ventilated small animal patients. Human clinical studies, scientific reviews, and textbooks, as well as veterinary textbooks and clinical examples of ventilator waveforms in mechanically ventilated dogs. Ventilator waveforms are graphic representations of data collected from the ventilator and reflect patient-ventilator interactions. The 4 parameters pressure, volume, flow, and time are most descriptive of mechanical ventilation. Typically, 3 different graphs, also referred to as scalars, consisting of pressure versus time, volume versus time, and flow versus time, with time always plotted on the x-axis, are used. Changes in the ventilator settings as well as in the characteristics of the lungs such as airway resistance (R(aw)) and respiratory system compliance (C(rs)) can be recognized from specific variations in the waveforms. Flow-volume and pressure-volume loops provide additional information about changes in lung function. Patient-ventilator dyssynchrony is a common problem during mechanical ventilation and can lead to patient discomfort and an increased work of breathing. Ventilator waveforms are helpful to identify dyssynchrony, which can be divided into trigger, flow, cycle, and expiratory dyssynchrony. Ventilator waveforms allow the clinician to assess changes in respiratory mechanics, and can be useful in monitoring the progression of disease pathology and response to therapy. Adjustments in ventilator settings based on proper analysis and interpretation of these waveforms can help the clinician to optimize ventilation therapy. Ventilator waveforms are graphic representations of patient-ventilator interactions. Proper interpretation of ventilator waveforms affords the critical care clinician a better understanding of the patient's respiratory function, response to therapy, and causes
Effect of mechanical ventilation waveforms on airway wall shear.
Pidaparti, Ramana M; Swanson, John
2015-01-01
Better understanding of airway wall shear stress/strain rate is very important in order to prevent inflammation in patients undergoing mechanical ventilation due to respiratory problems in intensive-care medicine. The objective of this study was to investigate the role of mechanical ventilation waveforms on airway wall shear/strain rate using computational fluid dynamics analysis. Six different waveforms were considered to investigate the airway wall shear stress (WSS) from fluid dynamics analysis for the airway geometry of two-to-three generations. The simulation results showed that Original with Sine Inhale Waveform (OSIW) produced the highest WSS value and the Near True Sine Waveform produced the lowest WSS value. Also, the Original with Sine Inhale Waveform and the Short Sine Inhale with Long Sine Exhale Waveform (SSILSEW) produced a higher shear strain rate in comparison to the Original Waveform (OW). These results, combined with optimization, suggest that it is possible to develop a set of mechanical ventilation waveform strategies to avoid inflammation in the lung.
An expression analysis package for REDUCE
van Hulzen, J.A.; Hulshof, B.J.A.
1982-01-01
An expression analysis package for REDUCE 2 is presented. This package, completely written in Standard LISP, can be considered as an extension of the algebraic mode. It allows to interactively dismantled and/or modify the last output expression as it is desplayed or printed. An interface with the
Waveform Catalog, Extreme Mass Ratio Binary (Capture)
National Aeronautics and Space Administration — Numerically-generated gravitational waveforms for circular inspiral into Kerr black holes. These waveforms were developed using Scott Hughes' black hole perturbation...
Rapid Analysis Model: Reducing Analysis Time without Sacrificing Quality.
Lee, William W.; Owens, Diana
2001-01-01
Discusses the performance technology design process and the fact that the analysis phase is often being eliminated to speed up the process. Proposes a rapid analysis model that reduces time needed for analysis and still ensures more successful value-added solutions that focus on customer satisfaction. (LRW)
DEFF Research Database (Denmark)
Chiang Loh, Poh; Gao, Feng; Blaabjerg, Frede
2009-01-01
Three-level Z-source inverters are recent single-stage topological solutions proposed for buck-boost energy conversion with all favorable advantages of three-level switching retained. Despite their proven buck-boost capability, existing three-level Zsource inverters are either too costly...... while using lesser passive LC elements. Through detailed operational analysis, new operating modes of the REC Z-source inverters are identified, which when inserted appropriately to the inverter state sequence will always produce the desired voltage transfer gain with minimized commutation count...
Towards full waveform ambient noise inversion
Sager, Korbinian; Ermert, Laura; Boehm, Christian; Fichtner, Andreas
2018-01-01
In this work we investigate fundamentals of a method—referred to as full waveform ambient noise inversion—that improves the resolution of tomographic images by extracting waveform information from interstation correlation functions that cannot be used without knowing the distribution of noise sources. The fundamental idea is to drop the principle of Green function retrieval and to establish correlation functions as self-consistent observables in seismology. This involves the following steps: (1) We introduce an operator-based formulation of the forward problem of computing correlation functions. It is valid for arbitrary distributions of noise sources in both space and frequency, and for any type of medium, including 3-D elastic, heterogeneous and attenuating media. In addition, the formulation allows us to keep the derivations independent of time and frequency domain and it facilitates the application of adjoint techniques, which we use to derive efficient expressions to compute first and also second derivatives. The latter are essential for a resolution analysis that accounts for intra- and interparameter trade-offs. (2) In a forward modelling study we investigate the effect of noise sources and structure on different observables. Traveltimes are hardly affected by heterogeneous noise source distributions. On the other hand, the amplitude asymmetry of correlations is at least to first order insensitive to unmodelled Earth structure. Energy and waveform differences are sensitive to both structure and the distribution of noise sources. (3) We design and implement an appropriate inversion scheme, where the extraction of waveform information is successively increased. We demonstrate that full waveform ambient noise inversion has the potential to go beyond ambient noise tomography based on Green function retrieval and to refine noise source location, which is essential for a better understanding of noise generation. Inherent trade-offs between source and structure
Photonic Arbitrary Waveform Generation Technology
2006-06-01
comb component. The generated waveform is given as [13] ∑ = ++= K k kk tkA Atf 1 0 0 )co s( 2 )( αω (1) 5 where f(t) is the desired waveform, Ak...tone waveform is not directly obtained from an extension of the single tone case. Nonetheless, by using three optical carriers, one can obtain any...pair insertion loss is ~ -7 dB, with a channel to channel crosstalk between filter channels of ~ -15 dB. For some of the experiments carried
Seismic Waveform Characterization at LLNL: Analyst Guidelines and Issues
Energy Technology Data Exchange (ETDEWEB)
Ryall, F; Schultz, C A
2001-11-01
In the first section of this paper we present an overview of general set of procedures that we have followed in seismic waveform analysis. In the second section we discuss a number of issues and complexities that we have encountered in analysis of events in the Middle East, North Africa, Europe, and parts of the European Arctic. To illustrate these complexities we can include examples of waveforms recorded over a variety of paths in these regions.
Jian, Pei-Ru; Hung, Shu-Huei; Meng, Lingsen; Sun, Daoyuan
2017-04-01
The 2016 Mw 6.4 Meinong earthquake struck a previously unrecognized fault zone in midcrust beneath south Taiwan and inflicted heavy causalities in the populated Tainan City about 30 km northwest of the epicenter. Because of its relatively short rupture duration and P wave trains contaminated by large-amplitude depth phases and reverberations generated in the source region, accurate characterization of the rupture process and source properties for such a shallow strong earthquake remains challenging. Here we present a first high-resolution MUltiple SIgnal Classification back projection source image by using both P and depth-phase sP waves recorded at two large and dense arrays to understand the source behavior and consequent hazards of this peculiar catastrophic event. The results further corroborated by the directivity analysis indicate a unilateral rupture propagating northwestward and slightly downward on the shallow NE-dipping fault plane. The source radiation process is primarily characterized by one single peak, 7 s duration, with a total rupture length of 17 km and average rupture speed of 2.4 km/s. The rupture terminated immediately east of the prominent off-fault aftershock cluster about 20 km northwest of the hypocenter. Synergistic amplification of ground shaking by the directivity and strong excitation of sP and reverberations mainly caused the destruction concentrated in the area further to the northwest away from the rupture zone.
An adaptive delineator for photoplethysmography waveforms.
Soundararajan, Mohanalakshmi; Arunagiri, Sivasubramanian; Alagala, Swarnalatha
2016-12-01
Photoplethysmography (PPG) waveforms are rich in cardiovascular information, and hence, their analysis is significant in the diagnosis and prevention of cardiovascular diseases (CVDs). The second derivative of photoplethysmography (SDPPG) analysis for the accurate detection of significant points in characterising the PPG waveform is challenging. In this paper, a SDPPG analysis algorithm is proposed based on a resampling technique which normalises the signal and ensures the presence of all significant points of interest in all its recurrences. The proposed delineator detects a, b and e waves in SDPPG, which are based on the combined analysis of PPG waveforms and their second derivatives, characterising them beat-by-beat by electrocardiogram (ECG) signals. Experiments have been conducted on 46 PPG signal records, each of 10-s duration with low and varying amplitudes, and regular and irregular heart rhythms for healthy adults, as well as unhealthy and aged patients obtained from the large-scale openly available database PhysioNet. Based on the experiments conducted, it is found that the proposed algorithm performs better than existing methods in terms of sensitivity and positive predictivity with a highest sensitivity of 99.84% with respect to a (onset) and b waves, 99.67% for e waves (dicrotic notch), and 100% of positive predictivity for a and b waves and 99.82% in case of e waves.
Jin, Danian; Dai, Chenxi; Gong, Yushun; Lu, Yubao; Zhang, Lei; Quan, Weilun; Li, Yongqin
2017-02-01
Quantitative analysis of ventricular fibrillation (VF), such as amplitude spectral area (AMSA), predicts shock outcomes. However, there is no uniform definition of shock/cardiopulmonary resuscitation (CPR) success in out-of-hospital cardiac arrest (OHCA). The objective of this study is to investigate post-shock rhythm variations and the impact of shock/CPR success definition on the predictability of AMSA. A total of 554 shocks from 257 OHCA patients with VF as initial rhythm were analyzed. Post-shock rhythms were analyzed every 5s up to 120s and annotated as VF, asystole (AS) and organized rhythm (OR) at serial time intervals. Three shock/CPR success definitions were used to evaluate the predictability of AMSA: (1) termination of VF (ToVF); (2) return of organized electrical activity (ROEA); (3) return of potentially perfusing rhythm (RPPR). Rhythm changes occurred after 54.5% (N=302) of shocks and 85.8% (N=259) of them occurred within 60s after shock delivery. The observed post-shock rhythm changes were (1) from AS to VF (24.9%), (2) from OR to VF (16.1%), and (3) from AS to OR (12.1%). The area under the receiver operating characteristic curve (AUC) for AMSA as a predictor of shock/CPR success reached its maximum 60s post-shock. The AUC was 0.646 for ToVF, 0.782 for ROEA, and 0.835 for RPPR (pdefinition of shock/CPR success and performs best with the return of potentially perfusing rhythm endpoint for OHCA. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Sushma Tejwani
Full Text Available In this study, spectral analysis of the deformation signal from Corvis-ST (CoST and reflected light intensity from ocular response analyzer (ORA was performed to evaluate biomechanical concordance with each other.The study was non-interventional, observational, cross-sectional and involved 188 eyes from 94 normal subjects. Three measurements were made on each eye with ORA and CoST each and then averaged for each device. The deformation signal from CoST and reflected light intensity (applanation signal from ORA was compiled for all the eyes. The ORA signal was inverted about a line joining the two applanation peaks. All the signals were analyzed with Fourier series. The area under the signal curves (AUC, root mean square (RMS of all the harmonics, lower order (LO included 1st and 2nd order harmonic, higher order (HO up to 6th harmonic, CoST deformation amplitude (DA, corneal hysteresis (CH and corneal resistance factor (CRF were analyzed.The device variables and those calculated by Fourier transform were statistically significantly different between CoST and ORA. These variables also differed between the eyes of the same subject. There was also statistically significant influence of eyes (left vs. right on the differences in a sub-set of RMS variables only. CH and CRF differed statistically significantly between the eyes of subject (p<0.001 but not DA (p = 0.65.CoST was statistically significantly different from ORA. CoST may be useful in delineating true biomechanical differences between the eyes of a subject as it reports deformation.
Fast Prediction and Evaluation of Gravitational Waveforms Using Surrogate Models
Directory of Open Access Journals (Sweden)
Scott E. Field
2014-07-01
Full Text Available We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced order model in both parameter and physical dimensions that can be used as a surrogate for the true or fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant that is built for the fiducial waveform family. Third, a fit in the parameter dimension is performed for the waveform’s value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order O(mL+mc_{fit} online operations, where c_{fit} denotes the fitting function operation count and, typically, m≪L. The result is a compact, computationally efficient, and accurate surrogate model that retains the original physics of the fiducial waveform family while also being fast to evaluate. We generate accurate surrogate models for effective-one-body waveforms of nonspinning binary black hole coalescences with durations as long as 10^{5}M, mass ratios from 1 to 10, and for multiple spherical harmonic modes. We find that these surrogates are more than 3 orders of magnitude faster to evaluate as compared to the cost of generating effective-one-body waveforms in standard ways. Surrogate model building for other waveform families and models follows the same steps and has the same low computational online scaling cost. For expensive numerical simulations of binary black hole coalescences, we thus anticipate extremely large speedups in
LPI Radar Waveform Recognition Based on Time-Frequency Distribution
Directory of Open Access Journals (Sweden)
Ming Zhang
2016-10-01
Full Text Available In this paper, an automatic radar waveform recognition system in a high noise environment is proposed. Signal waveform recognition techniques are widely applied in the field of cognitive radio, spectrum management and radar applications, etc. We devise a system to classify the modulating signals widely used in low probability of intercept (LPI radar detection systems. The radar signals are divided into eight types of classifications, including linear frequency modulation (LFM, BPSK (Barker code modulation, Costas codes and polyphase codes (comprising Frank, P1, P2, P3 and P4. The classifier is Elman neural network (ENN, and it is a supervised classification based on features extracted from the system. Through the techniques of image filtering, image opening operation, skeleton extraction, principal component analysis (PCA, image binarization algorithm and Pseudo–Zernike moments, etc., the features are extracted from the Choi–Williams time-frequency distribution (CWD image of the received data. In order to reduce the redundant features and simplify calculation, the features selection algorithm based on mutual information between classes and features vectors are applied. The superiority of the proposed classification system is demonstrated by the simulations and analysis. Simulation results show that the overall ratio of successful recognition (RSR is 94.7% at signal-to-noise ratio (SNR of −2 dB.
Fast prediction and evaluation of gravitational waveforms using surrogate models
Field, Scott E; Hesthaven, Jan S; Kaye, Jason; Tiglio, Manuel
2013-01-01
[Abridged] We propose a solution to the problem of quickly and accurately predicting gravitational waveforms within any given physical model. The method is relevant for both real-time applications and in more traditional scenarios where the generation of waveforms using standard methods can be prohibitively expensive. Our approach is based on three offline steps resulting in an accurate reduced-order model that can be used as a surrogate for the true/fiducial waveform family. First, a set of m parameter values is determined using a greedy algorithm from which a reduced basis representation is constructed. Second, these m parameters induce the selection of m time values for interpolating a waveform time series using an empirical interpolant. Third, a fit in the parameter dimension is performed for the waveform's value at each of these m times. The cost of predicting L waveform time samples for a generic parameter choice is of order m L + m c_f online operations where c_f denotes the fitting function operation ...
Frequency-domain waveform inversion using the unwrapped phase
Choi, Yun Seok
2011-01-01
Phase wrapping in the frequency-domain (or cycle skipping in the time-domain) is the major cause of the local minima problem in the waveform inversion. The unwrapped phase has the potential to provide us with a robust and reliable waveform inversion, with reduced local minima. We propose a waveform inversion algorithm using the unwrapped phase objective function in the frequency-domain. The unwrapped phase, or what we call the instantaneous traveltime, is given by the imaginary part of dividing the derivative of the wavefield with respect to the angular frequency by the wavefield itself. As a result, the objective function is given a traveltime-like function, which allows us to smooth it and reduce its nonlinearity. The gradient of the objective function is computed using the back-propagation algorithm based on the adjoint-state technique. We apply both our waveform inversion algorithm using the unwrapped phase and the conventional waveform inversion and show that our inversion algorithm gives better convergence to the true model than the conventional waveform inversion. © 2011 Society of Exploration Geophysicists.
Towards quantitative connectivity analysis: reducing tractography biases.
Girard, Gabriel; Whittingstall, Kevin; Deriche, Rachid; Descoteaux, Maxime
2014-09-01
Diffusion MRI tractography is often used to estimate structural connections between brain areas and there is a fast-growing interest in quantifying these connections based on their position, shape, size and length. However, a portion of the connections reconstructed with tractography is biased by their position, shape, size and length. Thus, connections reconstructed are not equally distributed in all white matter bundles. Quantitative measures of connectivity based on the streamline distribution in the brain such as streamline count (density), average length and spatial extent (volume) are biased by erroneous streamlines produced by tractography algorithms. In this paper, solutions are proposed to reduce biases in the streamline distribution. First, we propose to optimize tractography parameters in terms of connectivity. Then, we propose to relax the tractography stopping criterion with a novel probabilistic stopping criterion and a particle filtering method, both based on tissue partial volume estimation maps calculated from a T1-weighted image. We show that optimizing tractography parameters, stopping and seeding strategies can reduce the biases in position, shape, size and length of the streamline distribution. These tractography biases are quantitatively reported using in-vivo and synthetic data. This is a critical step towards producing tractography results for quantitative structural connectivity analysis. Copyright © 2014 Elsevier Inc. All rights reserved.
The natural combination of full and image-based waveform inversion
Alkhalifah, Tariq Ali
2015-06-01
Integrating migration velocity analysis and full waveform inversion can help reduce the high non-linearity of the classic full waveform inversion objective function. The combination of inverting for the long and short wavelength components of the velocity model using a dual objective function that is sensitive to both components is still very expensive and have produced mixed results. We develop an approach that includes both components integrated to complement each other. We specifically utilize the image to generate reflections in our synthetic data only when the velocity model is not capable of producing such reflections. As a result, we get the migration velocity analysis working when we need it, and we mitigate its influence when the velocity model produces accurate reflections (possibly first for the low frequencies). This is achieved using a novel objective function that includes both objectives. Applications to a layered model and the Marmousi model demonstrate the main features of the approach. © 2015 European Association of Geoscientists & Engineers.
Directory of Open Access Journals (Sweden)
P. Crespo-Peremarch
2016-06-01
In order to assess this effect, 64 pairwise samples were selected in adjacent areas with similar canopy structure, but having different point densities. Two parameters were tested and evaluated to minimise this effect: voxel size and voxel value assignation testing maximum, mean, median, mode, percentiles 90 and 95. Student’s t-test or Wilcoxon test were used for the comparison of paired samples. Moreover, the absolute value of standardised paired samples was calculated to quantify dissimilarities. It was concluded that optimizing voxel size and voxel value assignation minimised the effect of point density variations and homogenised full-waveform metrics. Height/median ratio (HTMR and Vertical distribution ratio (VDR had the lowest variability between different densities, and Return waveform energy (RWE reached the best improvement with respect to initial data, being the difference between standardised paired samples 1.28 before and 0.69 after modification.
Multiparameter Elastic Full Waveform Inversion With Facies Constraints
Zhang, Zhendong
2017-08-17
Full waveform inversion (FWI) aims fully benefit from all the data characteristics to estimate the parameters describing the assumed physics of the subsurface. However, current efforts to utilize full waveform inversion as a tool beyond acoustic imaging applications, for example in reservoir analysis, faces inherent challenges related to the limited resolution and the potential trade-off between the elastic model parameters. Adding rock physics constraints does help to mitigate these issues, but current approaches to add such constraints are based on including them as a priori knowledge mostly valid around the well or as a boundary condition for the whole area. Since certain rock formations inside the Earth admit consistent elastic properties and relative values of elastic and anisotropic parameters (facies), utilizing such localized facies information in FWI can improve the resolution of inverted parameters. We propose a novel confidence map based approach to utilize the facies-based constraints in both isotropic and anisotropic elastic FWI. We invert for such a confidence map using Bayesian theory, in which the confidence map is updated at each iteration of the inversion using both the inverted models and a prior information. The numerical examples show that the proposed method can reduce the trade-offs and also can improve the resolution of the inverted elastic and anisotropic properties.
al Jarad, N; Davies, S W; Logan-Sinclair, R; Rudd, R M
1994-01-01
The aim of this study is to investigate lung crackle characteristics by time-expanded waveform (TEW) analysis in patients with asbestosis (AS), asbestos-related pleural disease (ARPD) and left ventricular failure (LVF). TEW was performed on a 33 s recording from each of 40 patients (12 AS, 17 ARPD and 11 LVF). They were 38 men and two women. Crackles on TEW were counted during inspiration and expiration, and the timing of clusters of crackles with respect to inspiration and expiration was noted. A total of 1117 crackles were identified. The initial deflection width (IDW) and the two cycle duration (2CD) were calculated for all crackles within one respiratory cycle for each patient (total of 298 crackles). Crackles were detected by TEW in all patients with AS, in seven patients with ARPD and in nine patients with LVF. Crackles in AS were mainly fine, mid- to late-inspiratory. Crackles in LVF took three patterns; in the first there were repetitive mid- to late inspiratory crackles similar to those seen in AS except that the crackles in LVF tended to be medium and coarse as well as fine (three patients); in the second crackles started early in inspiration followed by a crackle-free period then by another cluster of crackles lasting to the end of inspiration and to the early third of expiration (four patients) and in the third there were repetitive expiratory crackles with no or few inspiratory crackles (two patients). Crackles in ARPD generally took the configuration of fine crackles but another type of crackle preceded by a sharp deflection followed by an M-shape oscillation then by the largest oscillation was also found. IDW and 2CD for inspiratory crackles in ARPD were shorter than those in AS and LVF (for IDW P < 0.009 and P < 0.003 compared with AS and LVF respectively and for 2CD, P < 0.006 and P < 0.003 compared with AS and LVF respectively). IDW and 2CD in AS tended to be shorter than these for LVF but these results did not reach statistical significance. It
Phase-space topography characterization of nonlinear ultrasound waveforms.
Dehghan-Niri, Ehsan; Al-Beer, Helem
2018-03-01
Fundamental understanding of ultrasound interaction with material discontinuities having closed interfaces has many engineering applications such as nondestructive evaluation of defects like kissing bonds and cracks in critical structural and mechanical components. In this paper, to analyze the acoustic field nonlinearities due to defects with closed interfaces, the use of a common technique in nonlinear physics, based on a phase-space topography construction of ultrasound waveform, is proposed. The central idea is to complement the "time" and "frequency" domain analyses with the "phase-space" domain analysis of nonlinear ultrasound waveforms. A nonlinear time series method known as pseudo phase-space topography construction is used to construct equivalent phase-space portrait of measured ultrasound waveforms. Several nonlinear models are considered to numerically simulate nonlinear ultrasound waveforms. The phase-space response of the simulated waveforms is shown to provide different topographic information, while the frequency domain shows similar spectral behavior. Thus, model classification can be substantially enhanced in the phase-space domain. Experimental results on high strength aluminum samples show that the phase-space transformation provides a unique detection and classification capabilities. The Poincaré map of the phase-space domain is also used to better understand the nonlinear behavior of ultrasound waveforms. It is shown that the analysis of ultrasound nonlinearities is more convenient and informative in the phase-space domain than in the frequency domain. Copyright © 2017 Elsevier B.V. All rights reserved.
Using waveform cross correlation for automatic recovery of aftershock sequences
Bobrov, Dmitry; Kitov, Ivan; Rozhkov, Mikhail
2017-04-01
Aftershock sequences of the largest earthquakes are difficult to recover. There can be several hundred mid-sized aftershocks per hour within a few hundred km from each other recorded by the same stations. Moreover, these events generate thousands of reflected/refracted phases having azimuth and slowness close to those from the P-waves. Therefore, aftershock sequences with thousands of events represent a major challenge for automatic and interactive processing at the International Data Centre (IDC) of the Comprehensive Nuclear-Test-Ban Organization (CTBTO). Standard methods of detection and phase association do not use all information contained in signals. As a result, wrong association of the first and later phases, both regular and site specific, produces enormous number of wrong event hypotheses and destroys valid event hypotheses in automatic IDC processing. In turn, the IDC analysts have to reject false and recreate valid hypotheses wasting precious human resources. At the current level of the IDC catalogue completeness, the method of waveform cross correlation (WCC) can resolve most of detection and association problems fully utilizing the similarity of waveforms generated by aftershocks. Array seismic stations of the International monitoring system (IMS) can enhance the performance of the WCC method: reduce station-specific detection thresholds, allow accurate estimate of signal attributes, including relative magnitude, and effectively suppress irrelevant arrivals. We have developed and tested a prototype of an aftershock tool matching all IDC processing requirements and merged it with the current IDC pipeline. This tool includes creation of master events consisting of real or synthetic waveform templates at ten and more IMS stations; cross correlation (CC) of real-time waveforms with these templates, association of arrivals detected at CC-traces in event hypotheses; building events matching the IDC quality criteria; and resolution of conflicts between events
Brenner, Anita C.; Zwally, H. Jay; Bentley, Charles R.; Csatho, Bea M.; Harding, David J.; Hofton, Michelle A.; Minster, Jean-Bernard; Roberts, LeeAnne; Saba, Jack L.; Thomas, Robert H.;
2012-01-01
The primary purpose of the GLAS instrument is to detect ice elevation changes over time which are used to derive changes in ice volume. Other objectives include measuring sea ice freeboard, ocean and land surface elevation, surface roughness, and canopy heights over land. This Algorithm Theoretical Basis Document (ATBD) describes the theory and implementation behind the algorithms used to produce the level 1B products for waveform parameters and global elevation and the level 2 products that are specific to ice sheet, sea ice, land, and ocean elevations respectively. These output products, are defined in detail along with the associated quality, and the constraints, and assumptions used to derive them.
Radar Waveform Design in Active Communications Channel
Romero, Ric A.; Shepherd, Kevin D.
2013-01-01
In this paper, we investigate spectrally adaptive radar transmit waveform design and its effects on an active communication system. We specifically look at waveform design for point targets. The transmit waveform is optimized by accounting for the modulation spectrum of the communication system while trying to efficiently use the remaining spectrum. With the use of spectrally-matched radar waveform, we show that the SER detection performance of the communication system ...
Qu, Fujian; Zarubin, Fidel; Wollenzier, Brian; Nikolski, Vladimir P; Efimov, Igor R
2005-02-01
Implantable cardioverter defibrillator studies have established the superiority of biphasic waveforms over monophasic waveforms. However, external defibrillator studies of biphasic waveforms are not as widespread. Our objective was to compare the defibrillation efficacy of clinically used biphasic waveforms, i.e., truncated exponential, rectilinear, and quasi-sinusoidal (Gurvich) waveforms in a fibrillating heart model. Langendorff-perfused rabbit hearts (n = 10) were stained with a voltage-sensitive fluorescent dye, Di-4-ANEPPS. Transmembrane action potentials were optically mapped from the anterior epicardium. We found that the Gurvich waveform was significantly superior (p truncated exponential waveforms. The defibrillation thresholds (mean +/- SE) were as follows: Gurvich, 0.25 +/- 0.01 J; rectilinear-1, 0.34 +/- 0.01 J; rectilinear-2, 0.33 +/- 0.01 J; and truncated exponential, 0.32 +/- 0.02 J. Using optically recorded transmembrane responses, we determined the shock-response transfer function, which allowed us to predict the cellular response to waveforms at high accuracy. The passive parallel resistor-capacitor model (RC-model) predicted polarization superiority of the Gurvich waveform in the myocardium with a membrane time constant (taum) of less than 2 ms. The finding of a lower defibrillation threshold with the Gurvich waveform in an in vitro model of external defibrillation suggests that the Gurvich waveform may be important for future external defibrillator designs.
2169 steel waveform experiments.
Energy Technology Data Exchange (ETDEWEB)
Furnish, Michael David; Alexander, C. Scott; Reinhart, William Dodd; Brown, Justin L.
2012-11-01
In support of LLNL efforts to develop multiscale models of a variety of materials, we have performed a set of eight gas gun impact experiments on 2169 steel (21% Cr, 6% Ni, 9% Mn, balance predominantly Fe). These experiments provided carefully controlled shock, reshock and release velocimetry data, with initial shock stresses ranging from 10 to 50 GPa (particle velocities from 0.25 to 1.05 km/s). Both windowed and free-surface measurements were included in this experiment set to increase the utility of the data set, as were samples ranging in thickness from 1 to 5 mm. Target physical phenomena included the elastic/plastic transition (Hugoniot elastic limit), the Hugoniot, any phase transition phenomena, and the release path (windowed and free-surface). The Hugoniot was found to be nearly linear, with no indications of the Fe phase transition. Releases were non-hysteretic, and relatively consistent between 3- and 5-mmthick samples (the 3 mm samples giving slightly lower wavespeeds on release). Reshock tests with explosively welded impactors produced clean results; those with glue bonds showed transient releases prior to the arrival of the reshock, reducing their usefulness for deriving strength information. The free-surface samples, which were steps on a single piece of steel, showed lower wavespeeds for thin (1 mm) samples than for thicker (2 or 4 mm) samples. A configuration used for the last three shots allows release information to be determined from these free surface samples. The sample strength appears to increase with stress from ~1 GPa to ~ 3 GPa over this range, consistent with other recent work but about 40% above the Steinberg model.
Workflows for Full Waveform Inversions
Boehm, Christian; Krischer, Lion; Afanasiev, Michael; van Driel, Martin; May, Dave A.; Rietmann, Max; Fichtner, Andreas
2017-04-01
Despite many theoretical advances and the increasing availability of high-performance computing clusters, full seismic waveform inversions still face considerable challenges regarding data and workflow management. While the community has access to solvers which can harness modern heterogeneous computing architectures, the computational bottleneck has fallen to these often manpower-bounded issues that need to be overcome to facilitate further progress. Modern inversions involve huge amounts of data and require a tight integration between numerical PDE solvers, data acquisition and processing systems, nonlinear optimization libraries, and job orchestration frameworks. To this end we created a set of libraries and applications revolving around Salvus (http://salvus.io), a novel software package designed to solve large-scale full waveform inverse problems. This presentation focuses on solving passive source seismic full waveform inversions from local to global scales with Salvus. We discuss (i) design choices for the aforementioned components required for full waveform modeling and inversion, (ii) their implementation in the Salvus framework, and (iii) how it is all tied together by a usable workflow system. We combine state-of-the-art algorithms ranging from high-order finite-element solutions of the wave equation to quasi-Newton optimization algorithms using trust-region methods that can handle inexact derivatives. All is steered by an automated interactive graph-based workflow framework capable of orchestrating all necessary pieces. This naturally facilitates the creation of new Earth models and hopefully sparks new scientific insights. Additionally, and even more importantly, it enhances reproducibility and reliability of the final results.
Best waveform score for diagnosing keratoconus
Directory of Open Access Journals (Sweden)
Allan Luz
2013-12-01
Full Text Available PURPOSE: To test whether corneal hysteresis (CH and corneal resistance factor (CRF can discriminate between keratoconus and normal eyes and to evaluate whether the averages of two consecutive measurements perform differently from the one with the best waveform score (WS for diagnosing keratoconus. METHODS: ORA measurements for one eye per individual were selected randomly from 53 normal patients and from 27 patients with keratoconus. Two groups were considered the average (CH-Avg, CRF-Avg and best waveform score (CH-WS, CRF-WS groups. The Mann-Whitney U-test was used to evaluate whether the variables had similar distributions in the Normal and Keratoconus groups. Receiver operating characteristics (ROC curves were calculated for each parameter to assess the efficacy for diagnosing keratoconus and the same obtained for each variable were compared pairwise using the Hanley-McNeil test. RESULTS: The CH-Avg, CRF-Avg, CH-WS and CRF-WS differed significantly between the normal and keratoconus groups (p<0.001. The areas under the ROC curve (AUROC for CH-Avg, CRF-Avg, CH-WS, and CRF-WS were 0.824, 0.873, 0.891, and 0.931, respectively. CH-WS and CRF-WS had significantly better AUROCs than CH-Avg and CRF-Avg, respectively (p=0.001 and 0.002. CONCLUSION: The analysis of the biomechanical properties of the cornea through the ORA method has proved to be an important aid in the diagnosis of keratoconus, regardless of the method used. The best waveform score (WS measurements were superior to the average of consecutive ORA measurements for diagnosing keratoconus.
Breast imaging using waveform attenuation tomography
Li, Cuiping; Sandhu, Gursharan Y.; Boone, Michael; Duric, Neb
2017-03-01
Ex vivo studies using our ultrasound waveform attenuation algorithm have shown promising results for detection and characterization of lesions of different types. Our preliminary in vivo study shows that the waveform attenuation image has much higher resolution and can better delineate breast lesions boundaries than the corresponding ray-based attenuation image. In this study, we preprocessed our time domain waveforms acquired with a ring array and explored the directional transducer beam pattern to better match calculated wave fields with respect to the acquired wave fields. We have applied waveform attenuation to in vivo data and compared the resulting waveform attenuation images with the ray-based counterparts to assess the resolution and accuracy of the waveform attenuation reconstruction.
Blackman, Jonathan; Galley, Chad R; Szilagyi, Bela; Scheel, Mark A; Tiglio, Manuel; Hemberger, Daniel A
2015-01-01
Simulating a binary black hole coalescence by solving Einstein's equations is computationally expensive, requiring days to months of supercomputing time. In this paper, we construct an accurate and fast-to-evaluate surrogate model for numerical relativity (NR) waveforms from non-spinning binary black hole coalescences with mass ratios from $1$ to $10$ and durations corresponding to about $15$ orbits before merger. Our surrogate, which is built using reduced order modeling techniques, is distinct from traditional modeling efforts. We find that the full multi-mode surrogate model agrees with waveforms generated by NR to within the numerical error of the NR code. In particular, we show that our modeling strategy produces surrogates which can correctly predict NR waveforms that were {\\em not} used for the surrogate's training. For all practical purposes, then, the surrogate waveform model is equivalent to the high-accuracy, large-scale simulation waveform but can be evaluated in a millisecond to a second dependin...
Tang, W; Weil, M H; Sun, S; Povoas, H P; Klouche, K; Kamohara, T; Bisera, J
2001-09-01
To compare the effects of biphasic defibrillation waveforms and conventional monophasic defibrillation waveforms on the success of initial defibrillation, postresuscitation myocardial function, and duration of survival after prolonged duration of untreated ventricular fibrillation (VF), including the effects of epinephrine. Prospective, randomized, animal study. Animal laboratory and university-affiliated research and educational institute. Domestic pigs. VF was induced in 20 anesthetized domestic pigs receiving mechanical ventilation. After 10 min of untreated VF, the animals were randomized. Defibrillation was attempted with up to three 150-J biphasic waveform shocks or a conventional sequence of 200-J, 300-J, and 360-J monophasic waveform shocks. When reversal of VF was unsuccessful, precordial compression was performed for 1 min, with or without administration of epinephrine. The protocol was repeated until spontaneous circulation was restored or for a maximum of 15 min. No significant differences in the success of initial resuscitation or in the duration of survival were observed. However, significantly less impairment of myocardial function followed biphasic shocks. Administration of epinephrine reduced the total electrical energy required for successful resuscitation with both biphasic and monophasic waveform shocks. Lower-energy biphasic waveform shocks were as effective as conventional higher-energy monophasic waveform shocks for restoration of spontaneous circulation after 10 min of untreated VF. Significantly better postresuscitation myocardial function was observed after biphasic waveform defibrillation. Administration of epinephrine after prolonged cardiac arrest decreased the total energy required for successful resuscitation.
Seismic waveform analyses for the 1938 Off Fukushima earthquake sequence
Murotani, S.; Satake, K.
2016-12-01
The 1938 Off Fukushima (Shioya-oki) earthquakes sequence, which consists of five earthquakes of Mjmaranging from 6.9 to 7.5, occurred in the southern part of the 2011 Tohoku earthquake source area. In this region, the 1938 sequence was the only known M 7 earthquakes until the 2011 Tohoku earthquake occurred. Abe (1977, Tectonophysics) estimated the focal mechanisms and seismic moments of these events. The source parameters of the earthquake sequence are shown in the following table. However, the slip distributions are not known. Murotani et al. (2004, SSJ Fall Meeting) estimated slip distributions for event 1 (Mw 7.6, Fault size 60 km x 70 km), event 2 (Mw 7.9, Fault size 80 km x 60 km), and event 3 (Mw 7.8, Fault size 90 km x 60 km) from inversion of near-field seismic waveforms at Sendai, Niigata, Maebashi, Mito, and Hongo (Tokyo). We compared the observed teleseismic waveforms at Christchurch (CHR), De Bilt (DBN), Pasadena (PAS), and Pulkovo (PUL) with the calculated waveforms from these slip distributions. The result showed that the computed waveforms fairly reproduced the phases of the observation but the amplitudes for all events were several to several tens of times larger than the observations. It means that the slip amount and Mwobtained from the near field seismic waveforms inversion were over-estimated. For event 3, the slip distribution estimated from near-field data has two large slip areas (asperities) to the north and south of the hypocenter, although only the southern asperity was able to reproduce the observed near-field seismic waveforms. When we calculate the teleseismic waveforms using one asperity model, the amplitudes become small and the phases are reproduced better compared to two asperities model. Event 3 therefore seemed to have only one asperity. In addition to the re-analysis of near field seismic data, tsunami waveforms will be also computed and compared with the observations. This study was supported by JSPS KAKENHI Grant Number JP16H
Partitioned Waveform Inversion Applied to Eurasia and Northern Africa
Energy Technology Data Exchange (ETDEWEB)
bedle, H; Matzel, E; Flanagan, M
2006-07-27
This report summarizes the data analysis achieved during Heather Bedle's eleven-week Technical Scholar internship at Lawrence Livermore National Labs during the early summer 2006. The work completed during this internship resulted in constraints on the crustal and upper mantle S-velocity structure in Northern Africa, the Mediterranean, the Middle East, and Europe, through the fitting of regional waveform data. This data extends current raypath coverage and will be included in a joint inversion along with data from surface wave group velocity measurements, S and P teleseismic arrival time data, and receiver function data to create an improved velocity model of the upper mantle in this region. The tectonic structure of the North African/Mediterranean/Europe/Middle Eastern study region is extremely heterogeneous. This region consists of, among others, stable cratons and platforms such as the West Africa Craton, and Baltica in Northern Europe; oceanic subduction zones throughout the Mediterranean Sea where the African and Eurasian plate collide; regions of continental collision as the Arabian Plate moves northward into the Turkish Plate; and rifting in the Red Sea, separating the Arabian and Nubian shields. With such diverse tectonic structures, many of the waveforms were difficult to fit. This is not unexpected as the waveforms are fit using an averaged structure. In many cases the raypaths encounter several tectonic features, complicating the waveform, and making it hard for the software to converge on a 1D average structure. Overall, the quality of the waveform data was average, with roughly 30% of the waveforms being discarded due to excessive noise that interfered with the frequency ranges of interest. An inversion for the 3D S-velocity structure of this region was also performed following the methodology of Partitioned Waveform Inversion (Nolet, 1990; Van der Lee and Nolet, 1997). The addition of the newly fit waveforms drastically extends the range of the
Goldstone Solar System Radar Waveform Generator
Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Nguyen, Huy
2012-01-01
Due to distances and relative motions among the transmitter, target object, and receiver, the time-base between any transmitted and received signal will undergo distortion. Pre-distortion of the transmitted signal to compensate for this time-base distortion allows reception of an undistorted signal. In most radar applications, an arbitrary waveform generator (AWG) would be used to store the pre-calculated waveform and then play back this waveform during transmission. The Goldstone Solar System Radar (GSSR), however, has transmission durations that exceed the available memory storage of such a device. A waveform generator capable of real-time pre-distortion of a radar waveform to a given time-base distortion function is needed. To pre-distort the transmitted signal, both the baseband radar waveform and the RF carrier must be modified. In the GSSR, this occurs at the up-conversion mixing stage to an intermediate frequency (IF). A programmable oscillator (PO) is used to generate the IF along with a time-varying phase component that matches the time-base distortion of the RF carrier. This serves as the IF input to the waveform generator where it is mixed with a baseband radar waveform whose time-base has been distorted to match the given time-base distortion function producing the modulated IF output. An error control feedback loop is used to precisely control the time-base distortion of the baseband waveform, allowing its real-time generation. The waveform generator produces IF modulated radar waveforms whose time-base has been pre-distorted to match a given arbitrary function. The following waveforms are supported: continuous wave (CW), frequency hopped (FH), binary phase code (BPC), and linear frequency modulation (LFM). The waveform generator takes as input an IF with a time varying phase component that matches the time-base distortion of the carrier. The waveform generator supports interconnection with deep-space network (DSN) timing and frequency standards, and
Categorisation of full waveform data provided by laser scanning devices
Ullrich, Andreas; Pfennigbauer, Martin
2011-11-01
In 2004, a laser scanner device for commercial airborne laser scanning applications, the RIEGL LMS-Q560, was introduced to the market, making use of a radical alternative approach to the traditional analogue signal detection and processing schemes found in LIDAR instruments so far: digitizing the echo signals received by the instrument for every laser pulse and analysing these echo signals off-line in a so-called full waveform analysis in order to retrieve almost all information contained in the echo signal using transparent algorithms adaptable to specific applications. In the field of laser scanning the somewhat unspecific term "full waveform data" has since been established. We attempt a categorisation of the different types of the full waveform data found in the market. We discuss the challenges in echo digitization and waveform analysis from an instrument designer's point of view and we will address the benefits to be gained by using this technique, especially with respect to the so-called multi-target capability of pulsed time-of-flight LIDAR instruments.
Centered Differential Waveform Inversion with Minimum Support Regularization
Kazei, Vladimir
2017-05-26
Time-lapse full-waveform inversion has two major challenges. The first one is the reconstruction of a reference model (baseline model for most of approaches). The second is inversion for the time-lapse changes in the parameters. Common model approach is utilizing the information contained in all available data sets to build a better reference model for time lapse inversion. Differential (Double-difference) waveform inversion allows to reduce the artifacts introduced into estimates of time-lapse parameter changes by imperfect inversion for the baseline-reference model. We propose centered differential waveform inversion (CDWI) which combines these two approaches in order to benefit from both of their features. We apply minimum support regularization commonly used with electromagnetic methods of geophysical exploration. We test the CDWI method on synthetic dataset with random noise and show that, with Minimum support regularization, it provides better resolution of velocity changes than with total variation and Tikhonov regularizations in time-lapse full-waveform inversion.
Correcting low-frequency phase distortion in electroglottograph waveforms.
Rothenberg, Martin
2002-03-01
Dynamic high-pass filtering with a -3 dB frequency that is a factor of ten or more below the voice fundamental frequency has a negligible effect on the amplitudes of the Fourier components of an EGG waveform. However, such a filter can significantly distort the waveform due to distortion in the phase or time alignment of these Fourier components. Such high-pass filtering can be introduced purposefully to stabilize the waveform by attenuating low-frequency noise, or may be an undesired effect of using an amplification or data acquisition system designed for acoustic signals. For a given voice fundamental frequency, the amount of distortion depends greatly on the order or attenuation characteristics of the filter and on the type of EGG waveform. Both a high-order filter and a breathy voice tend to increase the amount of distortion. If the characteristics of the high-pass filter are known, there are a number of digital filter techniques that can be used to reduce the phase distortion. However, it is shown that a relatively simple analogue network can also be used to obtain a correction that suffices for most applications. If the precise characteristics of the filter are not known, the response to a square wave can be used to adjust the compensator parameters for an optimal correction.
National Research Council Canada - National Science Library
Huang, Jian; Walcott, Gregory P; Ruse, Richard B; Bohanan, Scott J; Killingsworth, Cheryl R; Ideker, Raymond E
2012-01-01
.... Defibrillation thresholds were determined for 11 waveforms-3 ascending-ramp waveforms, 3 descending-ramp waveforms, 3 rectilinear first-phase biphasic waveforms, a Gurvich waveform, and a truncated...
Waveform Diversity: Past, Present, and Future
2009-11-01
Pythagoras , continuing with the studies of Galileo, Fourier, and Maxwell. Examples of waveform diversity in nature, such as the bath sonar signal...music from the epoch of Pythagoras , continuing with the studies of Galileo, Fourier, and Maxwell. Examples of waveform diversity in nature, such as the
Biphasic truncated exponential waveform defibrillation.
White, R D; Blanton, D M
1999-01-01
This paper presents data from studies that have compared the efficacies of biphasic truncated exponential (BTE) and monophasic damped sine (MDS) waveform defibrillation in patients with out-of-hospital cardiac arrest and in in-hospital defibrillation. When a shock is delivered, rhythms evolve rapidly in a variety of directions and take different courses, even over a short time. When defibrillation is defined as termination of ventricular fibrillation at 5 seconds postshock, whether to an organized rhythm or asystole, low-energy BTE shocks appear to be more effective than high-energy MDS shocks in out-of-hospital arrest. For future research, the terms associated with defibrillation should be standardized and used uniformly by all investi-gators. In particular, there should be an agreed-upon definition of shock efficacy.
Synchronous Generator Model Parameter Estimation Based on Noisy Dynamic Waveforms
Berhausen, Sebastian; Paszek, Stefan
2016-01-01
In recent years, there have occurred system failures in many power systems all over the world. They have resulted in a lack of power supply to a large number of recipients. To minimize the risk of occurrence of power failures, it is necessary to perform multivariate investigations, including simulations, of power system operating conditions. To conduct reliable simulations, the current base of parameters of the models of generating units, containing the models of synchronous generators, is necessary. In the paper, there is presented a method for parameter estimation of a synchronous generator nonlinear model based on the analysis of selected transient waveforms caused by introducing a disturbance (in the form of a pseudorandom signal) in the generator voltage regulation channel. The parameter estimation was performed by minimizing the objective function defined as a mean square error for deviations between the measurement waveforms and the waveforms calculated based on the generator mathematical model. A hybrid algorithm was used for the minimization of the objective function. In the paper, there is described a filter system used for filtering the noisy measurement waveforms. The calculation results of the model of a 44 kW synchronous generator installed on a laboratory stand of the Institute of Electrical Engineering and Computer Science of the Silesian University of Technology are also given. The presented estimation method can be successfully applied to parameter estimation of different models of high-power synchronous generators operating in a power system.
Augmented kludge waveforms for detecting extreme-mass-ratio inspirals
Chua, Alvin J. K.; Moore, Christopher J.; Gair, Jonathan R.
2017-08-01
The extreme-mass-ratio inspirals (EMRIs) of stellar-mass compact objects into massive black holes are an important class of source for the future space-based gravitational-wave detector LISA. Detecting signals from EMRIs will require waveform models that are both accurate and computationally efficient. In this paper, we present the latest implementation of an augmented analytic kludge (AAK) model, publicly available at https://github.com/alvincjk/EMRI_Kludge_Suite as part of an EMRI waveform software suite. This version of the AAK model has improved accuracy compared to its predecessors, with two-month waveform overlaps against a more accurate fiducial model exceeding 0.97 for a generic range of sources; it also generates waveforms 5-15 times faster than the fiducial model. The AAK model is well suited for scoping out data analysis issues in the upcoming round of mock LISA data challenges. A simple analytic argument shows that it might even be viable for detecting EMRIs with LISA through a semicoherent template bank method, while the use of the original analytic kludge in the same approach will result in around 90% fewer detections.
Decomposition of LiDAR waveforms by B-spline-based modeling
Shen, Xiang; Li, Qing-Quan; Wu, Guofeng; Zhu, Jiasong
2017-06-01
Waveform decomposition is a widely used technique for extracting echoes from full-waveform LiDAR data. Most previous studies recommended the Gaussian decomposition approach, which employs the Gaussian function in laser pulse modeling. As the Gaussian-shape assumption is not always satisfied for real LiDAR waveforms, some other probability distributions (e.g., the lognormal distribution, the generalized normal distribution, and the Burr distribution) have also been introduced by researchers to fit sharply-peaked and/or heavy-tailed pulses. However, these models cannot be universally used, because they are only suitable for processing the LiDAR waveforms in particular shapes. In this paper, we present a new waveform decomposition algorithm based on the B-spline modeling technique. LiDAR waveforms are not assumed to have a priori shapes but rather are modeled by B-splines, and the shape of a received waveform is treated as the mixture of finite transmitted pulses after translation and scaling transformation. The performance of the new model was tested using two full-waveform data sets acquired by a Riegl LMS-Q680i laser scanner and an Optech Aquarius laser bathymeter, comparing with three classical waveform decomposition approaches: the Gaussian, generalized normal, and lognormal distribution-based models. The experimental results show that the B-spline model performed the best in terms of waveform fitting accuracy, while the generalized normal model yielded the worst performance in the two test data sets. Riegl waveforms have nearly Gaussian pulse shapes and were well fitted by the Gaussian mixture model, while the B-spline-based modeling algorithm produced a slightly better result by further reducing 6.4% of fitting residuals, largely benefiting from alleviating the adverse impact of the ringing effect. The pulse shapes of Optech waveforms, on the other hand, are noticeably right-skewed. The Gaussian modeling results deviated significantly from original signals, and
Waveform Fingerprinting for Efficient Seismic Signal Detection
Yoon, C. E.; OReilly, O. J.; Beroza, G. C.
2013-12-01
Cross-correlating an earthquake waveform template with continuous waveform data has proven a powerful approach for detecting events missing from earthquake catalogs. If templates do not exist, it is possible to divide the waveform data into short overlapping time windows, then identify window pairs with similar waveforms. Applying these approaches to earthquake monitoring in seismic networks has tremendous potential to improve the completeness of earthquake catalogs, but because effort scales quadratically with time, it rapidly becomes computationally infeasible. We develop a fingerprinting technique to identify similar waveforms, using only a few compact features of the original data. The concept is similar to human fingerprints, which utilize key diagnostic features to identify people uniquely. Analogous audio-fingerprinting approaches have accurately and efficiently found similar audio clips within large databases; example applications include identifying songs and finding copyrighted content within YouTube videos. In order to fingerprint waveforms, we compute a spectrogram of the time series, and segment it into multiple overlapping windows (spectral images). For each spectral image, we apply a wavelet transform, and retain only the sign of the maximum magnitude wavelet coefficients. This procedure retains just the large-scale structure of the data, providing both robustness to noise and significant dimensionality reduction. Each fingerprint is a high-dimensional, sparse, binary data object that can be stored in a database without significant storage costs. Similar fingerprints within the database are efficiently searched using locality-sensitive hashing. We test this technique on waveform data from the Northern California Seismic Network that contains events not detected in the catalog. We show that this algorithm successfully identifies similar waveforms and detects uncataloged low magnitude events in addition to cataloged events, while running to completion
Directory of Open Access Journals (Sweden)
Suwarno
2008-05-01
Full Text Available Ceramic outdoor insulators have been used in high voltage transmission lines since long time ago. Due to superiority in their resistance to pollution, recently, polymeric outdoor insulators are widely used. Epoxy resin is one polymer which shows good properties for outdoor insulation. During service, outdoor insulators may severe a certain degree of pollution which may reduce their surface resistance. Leakage current (LC usually increase and degradation may take place. This paper reports experimental results on the leakage current waveforms and arcing characteristics of epoxy resin under clean and salt fog. The samples used are blocks of epoxy resin with dimension of 250 x 50 x 20 mm3. The samples were put in a test chamber with dimension of 900x900x1200 mm3 with controllable humidity and pollution conditions. Clean and salt fog were generated according to IEC 60-1 and 507. The arcing experiment was done with incline plane test in accordance with IEC 587. AC voltage in the range from 5 kV to 50 kV with frequency of 50 Hz was applied. The LC waveforms up to flash over were measured. The magnitudes as well as harmonic content of the LC were analyzed. The correlation between LC waveforms and dry band arching phenomenon was elaborated. Visual observation of the arc on the sample surfaces was observed using a video camera. Experimental results indicated that LC magnitude on clean samples was slightly affected by humidity (RH. However, under salt fog, RH greatly affected the LC magnitude. The flashover voltage of clean samples under salt fog reduced significantly for fog conductivity of more than 1.2 mS/cm. Kaolin-polluted samples under salt fog showed an Ohmic behaviour. The LC magnitude was high and a large discrepancy of LC magnitude was observed for high applied voltage of larger than 25 kV. The largest LC magnitude was observed on salt-kaolin polluted samples under clean fog at high RH. LC waveforms analysis indicated that in general LC waveforms
Attosecond control of optical waveforms
Energy Technology Data Exchange (ETDEWEB)
Fuji, Takao [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Rauschenberger, Jens [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Gohle, Christoph [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Apolonski, Alexander [Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Institute of Automation and Electrometry, Russian Academy of Science, 630090 Novosibirsk, Russia (Russian Federation); Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Yakovlev, Vladislav S [Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Tempea, Gabriel [Femtolasers Produktions GmbH, Fernkorngasse 10, A-1100 Vienna (Austria); Haensch, Theodor W [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Krausz, Ferenc [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Department fuer Physik, Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Institut fuer Photonik, Technische Universitaet Wien, Gusshausstrasse 27/387, A-1040 Vienna (Austria)
2005-05-01
A new, monolithic scheme for stabilizing the phase between the carrier wave and the envelope (CE phase) in a train of few-cycle laser pulses is demonstrated. Self-phase modulation and second-harmonic generation or difference-frequency generation in a single periodically poled lithium niobate crystal, that transmits the main laser beam, allows for the CE-phase locking directly in the usable output. The monolithic scheme obviates the need for splitting off a fraction of the laser output for CE-phase control, coupling into microstructured fibre, as well as separation and recombination of spectral components. As a result, the CE-phase error integrated over the spectral range of 0.2 mHz-35 MHz is as small as 0.016 x 2{pi} rad. This implies that the phase of the field oscillations ({lambda} {approx} 830 nm) with respect to the pulse peak is locked to within 44 attoseconds, resulting in optical waveform control with subhundred attosecond fidelity for the first time.
Velocity Building by Reflection Waveform Inversion without Cycle-skipping
Guo, Qiang
2017-05-26
Reflection waveform inversion (RWI) provides estimation of low wavenumber model components using reflections generated from a migration/demigration process. The resulting model tends to be a good initial model for FWI. In fact, the optimization images to combine the migration velocity analysis (MVA) objectives (given here by RWI) and the FWI ones. However, RWI may still encounter cycle-skipping at far offsets if the velocity model is highly inaccurate. Similar to MVA, RWI is devoted to focusing reflection data to its true image positions, yet because of the cycle skipping potential we tend to initially use only near offsets. To make the inversion procedure more robust, we introduce the extended image into our RWI. Extending the model perturbations (or image) allows us to better fit the data at larger offsets even with an inaccurate velocity. Thus, we implement a nested approach to optimize the velocity and extended image simultaneously using the objective function of RWI. We slowly reduce the extension, as the image becomes focused, to allow wavepath updates from far offsets to near as a natural progression from long wavelength updates to shorter ones. Applications on synthetic data demonstrate the effectiveness of our method without much additional cost to RWI.
Waveform inversion for acoustic VTI media in frequency domain
Wu, Zedong
2016-09-06
Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the background model using a single scattered wavefield from an inverted perturbation. However, current RWI methods are mostly based on isotropic media assumption. We extend the idea of the combining inversion for the background model and perturbations to address transversely isotropic with a vertical axis of symmetry (VTI) media taking into consideration of the optimal parameter sensitivity information. As a result, we apply Born modeling corresponding to perturbations in only for the variable e to derive the relative reflected waveform inversion formulation. To reduce the number of parameters, we assume the background part of η = ε and work with a single variable to describe the anisotropic part of the wave propagation. Thus, the optimization variables are the horizontal velocity v, η = ε and the e perturbation. Application to the anisotropic version of Marmousi model with a single frequency of 2.5 Hz shows that this method can converge to the accurate result starting from a linearly increasing isotropic initial velocity. Application to a real dataset demonstrates the versatility of the approach.
Analysis on Dynamic Transmission Accuracy for RV Reducer
Directory of Open Access Journals (Sweden)
Zhang Fengshou
2017-01-01
Full Text Available By taking rotate vector (RV reducer as the research object, the factors affecting the transmission accuracy are studied, including the machining errors of the main parts, assembly errors, clearance, micro-displacement, gear mesh stiffness and damping, bearing stiffness. Based on Newton second law, the transmission error mathematical model of RV reducer is set up. Then, the RV reducer transmission error curve is achieved by solving the mathematical model using the Runge-Kutta methods under the combined action of various error factors. Through the analysis of RV reducer transmission test, it can be found that there are similar variation trend and frequency components compared the theoretical research and experimental result. The presented method is useful to the research on dynamic transmission accuracy of RV reducer, and also applies to research the transmission accuracy of other cycloid drive systems.
Sak, Mark; Duric, Neb; Littrup, Peter; Sherman, Mark; Gierach, Gretchen
2017-03-01
Ultrasound tomography (UST) is an emerging modality that can offer quantitative measurements of breast density. Recent breakthroughs in UST image reconstruction involve the use of a waveform reconstruction as opposed to a raybased reconstruction. The sound speed (SS) images that are created using the waveform reconstruction have a much higher image quality. These waveform images offer improved resolution and contrasts between regions of dense and fatty tissues. As part of a study that was designed to assess breast density changes using UST sound speed imaging among women undergoing tamoxifen therapy, UST waveform sound speed images were then reconstructed for a subset of participants. These initial results show that changes to the parenchymal tissue can more clearly be visualized when using the waveform sound speed images. Additional quantitative testing of the waveform images was also started to test the hypothesis that waveform sound speed images are a more robust measure of breast density than ray-based reconstructions. Further analysis is still needed to better understand how tamoxifen affects breast tissue.
Huang, Mingbo; Hu, Ding; Yu, Donglan; Zheng, Zhensheng; Wang, Kuijian
2011-12-01
Enhanced extracorporeal counterpulsation (EECP) information consists of both text and hemodynamic waveform data. At present EECP text information has been successfully managed through Web browser, while the management and sharing of hemodynamic waveform data through Internet has not been solved yet. In order to manage EECP information completely, based on the in-depth analysis of EECP hemodynamic waveform file of digital imaging and communications in medicine (DICOM) format and its disadvantages in Internet sharing, we proposed the use of the extensible markup language (XML), which is currently the Internet popular data exchange standard, as the storage specification for the sharing of EECP waveform data. Then we designed a web-based sharing system of EECP hemodynamic waveform data via ASP. NET 2.0 platform. Meanwhile, we specifically introduced the four main system function modules and their implement methods, including DICOM to XML conversion module, EECP waveform data management module, retrieval and display of EECP waveform module and the security mechanism of the system.
Wang, Jinglan; Tang, Wanchun; Brewer, James E; Freeman, Gary; Chang, Yun-Te; Weil, Max Harry
2007-08-01
To compare the rectilinear biphasic waveform with a biphasic truncated exponential waveform for pediatric defibrillation. Prospective, randomized study. Experimental laboratory of a university-affiliated research institute. Male domestic piglets (4-24 kg). Eleven piglets (4-8 kg), which represented a patient truncated exponential waveforms, comprising five shocks at five energy settings. Each group of five shocks was fixed at a predetermined energy value, depending on the body weight of the animal. Dose-response curves were constructed using logistic regression. Aortic pressure, electrocardiogram, left ventricular pressure, and left ventricular pressure value of 40 mm Hg were continually measured. Dose-response curves determined defibrillation thresholds at 50% (D50) and 90% (D90) probability of success. The rectilinear biphasic waveform defibrillated with truncated exponential waveform. The rectilinear biphasic waveform also successfully defibrillated with significantly less energy per body weight and per heart weight compared with a biphasic truncated exponential waveform. The rectilinear biphasic waveform has superior defibrillation performance compared with a biphasic truncated exponential waveform in a piglet defibrillation model for young children.
Georgia Tech Catalog of Gravitational Waveforms
Jani, Karan; Clark, James A; London, Lionel; Laguna, Pablo; Shoemaker, Deirdre
2016-01-01
This paper introduces a catalog of gravitational waveforms from the bank of simulations by the numerical relativity effort at Georgia Tech. Currently, the catalog consists of 452 distinct waveforms from more than 600 binary black hole simulations: 128 of the waveforms are from binaries with black hole spins aligned with the orbital angular momentum, and 324 are from precessing binary black hole systems. The waveforms from binaries with non-spinning black holes have mass-ratios $q = m_1/m_2 \\le 15$, and those with precessing, spinning black holes have $q \\le 8$. The waveforms expand a moderate number of orbits in the late inspiral, the burst during coalescence, and the ring-down of the final black hole. Examples of waveforms in the catalog matched against the widely used approximate models are presented. In addition, predictions of the mass and spin of the final black hole by phenomenological fits are tested against the results from the simulation bank. The role of the catalog in interpreting the GW150914 even...
Subjective loudness of "minimized" sonic boom waveforms.
Niedzwiecki, A; Ribner, H S
1978-12-01
For very long supersonic aircraft the "midfield" sonic boom signature may not have evolved fully into an N wave at ground level. Thus in current boom minimization techniques the shape of the aircraft may be tailored to optimize this midfield wave form for reduced subjective loudness. The present investigation tests a family of "flat-top" waveforms cited by Darden: all but one have a front shock height (deltapSH) less than the peak amplitude (deltapMAX). For equal subjective loudness, "flat top" vs N wave (peak overpressure deltapN), the peak amplitude of the "flat top" signature was found to be substantially higher than that of the N wave; thus for equal peak amplitude the "flat-top" signature was quieter. The results for equal loudness were well fitted by an emperical law deltapSH + 0.11deltapMAX = deltapN; the equivalence shows how the front shock amplitude (deltapSH) dominates the loudness. All this was found compatible with predictions by the method of Johnson and Robinson.
STEREO Observations of Turbulent Solar Wind Waveforms
Kellogg, Paul J.; Goetz, Keith; Monson, Steven J.
2017-04-01
Studies of solar wind turbulence have heretofore concentrated on Kolmogorov-type studies of the full MHD equations, without regard to the separate modes of the possible solutions. Further understanding of the nonlinear processes of the cascade, and especially transference of wave energy to particles, would seem to depend on more detailed understanding of the waves, their modes and their separate electric and magnetic fields. . A part of the SWAVES experiment on the STEREO spacecraft was designed to study the waves in the dissipation region of the turbulence spectrum. However, compatibility with SECCHI, the optical sensors, required that only monopole antennas could be accommodated, and these respond both to electric fields and to density fluctuations. This seemed to require that one measure four quantities with only three signals. After several years, the response of the antennas to density fluctuations was reduced, due to changes in photoemission coefficients, and measurement of separate electric fields became possible. It is found that sometimes there are short periods when a sinusoidal waveform appears which seems sufficiently pure to represent a single mode. Results of study of the fields of such waves will be presented.
Full Waveform Inversion Using Nonlinearly Smoothed Wavefields
Li, Y.
2017-05-26
The lack of low frequency information in the acquired data makes full waveform inversion (FWI) conditionally converge to the accurate solution. An initial velocity model that results in data with events within a half cycle of their location in the observed data was required to converge. The multiplication of wavefields with slightly different frequencies generates artificial low frequency components. This can be effectively utilized by multiplying the wavefield with itself, which is nonlinear operation, followed by a smoothing operator to extract the artificially produced low frequency information. We construct the objective function using the nonlinearly smoothed wavefields with a global-correlation norm to properly handle the energy imbalance in the nonlinearly smoothed wavefield. Similar to the multi-scale strategy, we progressively reduce the smoothing width applied to the multiplied wavefield to welcome higher resolution. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to the conventional FWI except for the adjoint source. Examples on the Marmousi 2 model demonstrate the feasibility of the proposed FWI method to mitigate the cycle-skipping problem in the case of a lack of low frequency information.
Closed-form Solution to Directly Design FACE Waveforms for Beampatterns Using Planar Array
Bouchoucha, Taha
2015-04-19
In multiple-input multiple-output radar systems, it is usually desirable to steer transmitted power in the region-of-interest. To do this, conventional methods optimize the waveform covariance matrix, R, for the desired beampattern, which is then used to generate actual transmitted waveforms. Both steps require constrained optimization, therefore, use iterative algorithms. The main challenges encountered in the existing approaches are the computational complexity and the design of waveforms to use in practice. In this paper, we provide a closed-form solution to design covariance matrix for the given beampattern using the planar array, which is then used to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope (FACE) waveforms. The proposed algorithm exploits the two-dimensional fast-Fourier-transform. The performance of our proposed algorithm is compared with existing methods that are based on semi-definite quadratic programming with the advantage of a considerably reduced complexity.
Metering error quantification under voltage and current waveform distortion
Wang, Tao; Wang, Jia; Xie, Zhi; Zhang, Ran
2017-09-01
With integration of more and more renewable energies and distortion loads into power grid, the voltage and current waveform distortion results in metering error in the smart meters. Because of the negative effects on the metering accuracy and fairness, it is an important subject to study energy metering combined error. In this paper, after the comparing between metering theoretical value and real recorded value under different meter modes for linear and nonlinear loads, a quantification method of metering mode error is proposed under waveform distortion. Based on the metering and time-division multiplier principles, a quantification method of metering accuracy error is proposed also. Analyzing the mode error and accuracy error, a comprehensive error analysis method is presented which is suitable for new energy and nonlinear loads. The proposed method has been proved by simulation.
Modelling Sensor and Target effects on LiDAR Waveforms
Rosette, J.; North, P. R.; Rubio, J.; Cook, B. D.; Suárez, J.
2010-12-01
The aim of this research is to explore the influence of sensor characteristics and interactions with vegetation and terrain properties on the estimation of vegetation parameters from LiDAR waveforms. This is carried out using waveform simulations produced by the FLIGHT radiative transfer model which is based on Monte Carlo simulation of photon transport (North, 1996; North et al., 2010). The opportunities for vegetation analysis that are offered by LiDAR modelling are also demonstrated by other authors e.g. Sun and Ranson, 2000; Ni-Meister et al., 2001. Simulations from the FLIGHT model were driven using reflectance and transmittance properties collected from the Howland Research Forest, Maine, USA in 2003 together with a tree list for a 200m x 150m area. This was generated using field measurements of location, species and diameter at breast height. Tree height and crown dimensions of individual trees were calculated using relationships established with a competition index determined for this site. Waveforms obtained by the Laser Vegetation Imaging Sensor (LVIS) were used as validation of simulations. This provided a base from which factors such as slope, laser incidence angle and pulse width could be varied. This has enabled the effect of instrument design and laser interactions with different surface characteristics to be tested. As such, waveform simulation is relevant for the development of future satellite LiDAR sensors, such as NASA’s forthcoming DESDynI mission (NASA, 2010), which aim to improve capabilities of vegetation parameter estimation. ACKNOWLEDGMENTS We would like to thank scientists at the Biospheric Sciences Branch of NASA Goddard Space Flight Center, in particular to Jon Ranson and Bryan Blair. This work forms part of research funded by the NASA DESDynI project and the UK Natural Environment Research Council (NE/F021437/1). REFERENCES NASA, 2010, DESDynI: Deformation, Ecosystem Structure and Dynamics of Ice. http
Deep brain stimulation: increasing efficiency by alternative waveforms
Directory of Open Access Journals (Sweden)
Argiti Katerina
2016-09-01
Full Text Available Deep brain stimulation (DBS is based on the effect of high frequency stimulation (HFS in neuronal tissue. As a therapy option for patients suffering from e.g. Parkinson’s disease, DBS has been used for decades. Despite the widespread use, the effect of HFS on neurons is not fully investigated. Improving the stimulation efficiency und specificity could increase the efficiency of the INS (internal neuronal stimulator as well as potentially reduce unwanted side effects. The effect of HFS on the GABAergic system was quantified using whole cell patch clamp electrophysiology during HFS stimulation in cortical human brain slices in vitro. Rectangular, sine, sawtooth and triangular waveforms were applied extracellularly. Since HFS has been hypothesized to increase the activity of the axons of GABAergic interneurons, a decrease in activity can be observed in the pyramidal cells that the interneurons project to. By isolating the incoming non- GABAergic events, we can filter out only the GABAA currents which can be verified using a GABAA antagonist. The results show that all the waveforms effectively increase the GABAA currents. The triangle waveform causes the highest significant increase in the activity which further increases over time after the stimulation was turned off.
Phylogenetic analysis of dissimilatory Fe(III)-reducing bacteria
Lonergan, D.J.; Jenter, H.L.; Coates, J.D.; Phillips, E.J.P.; Schmidt, T.M.; Lovley, D.R.
1996-01-01
Evolutionary relationships among strictly anaerobic dissimilatory Fe(III)- reducing bacteria obtained from a diversity of sedimentary environments were examined by phylogenetic analysis of 16S rRNA gene sequences. Members of the genera Geobacter, Desulfuromonas, Pelobacter, and Desulfuromusa formed a monophyletic group within the delta subdivision of the class Proteobacteria. On the basis of their common ancestry and the shared ability to reduce Fe(III) and/or S0, we propose that this group be considered a single family, Geobacteraceae. Bootstrap analysis, characteristic nucleotides, and higher- order secondary structures support the division of Geobacteraceae into two subgroups, designated the Geobacter and Desulfuromonas clusters. The genus Desulfuromusa and Pelobacter acidigallici make up a distinct branch with the Desulfuromonas cluster. Several members of the family Geobacteraceae, none of which reduce sulfate, were found to contain the target sequences of probes that have been previously used to define the distribution of sulfate-reducing bacteria and sulfate-reducing bacterium-like microorganisms. The recent isolations of Fe(III)-reducing microorganisms distributed throughout the domain Bacteria suggest that development of 16S rRNA probes that would specifically target all Fe(III) reducers may not be feasible. However, all of the evidence suggests that if a 16S rRNA sequence falls within the family Geobacteraceae, then the organism has the capacity for Fe(III) reduction. The suggestion, based on geological evidence, that Fe(III) reduction was the first globally significant process for oxidizing organic matter back to carbon dioxide is consistent with the finding that acetate-oxidizing Fe(III) reducers are phylogenetically diverse.
Design of pulse waveform for waveform division multiple access UWB wireless communication system.
Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu
2014-01-01
A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.
Dricker, Ilya G.
Seismic networks in the Commonwealth of Independent States (CIS) consist of more than a hundred broadband analog stations and have been in operation for more than 30 years. The longevity of the network, the number and distribution of stations, and the large number of earthquakes recorded has made the seismic data collected by the networks a valuable source of information about the structure of the Earth. The analog recording format and a lack of access to adequate computing facilities has resulted in most of these data undergoing only rudimentary analysis in the past. For this thesis I have collected and digitized several thousands analog records from the archives of more than 30 stations. I found that the quality of the digitized seismograms from the CIS analog stations is good enough to be useful in such types of analysis as the receiver functions, SKS splitting and SS-S differential travel times analysis. Studies of SKS phases recorded by stations in Eastern Europe suggest the existence of a present or recent large-scale mantle flow in central and eastern Europe, parallel to the Alpine belt, which is consistent with the hypothesis of flow proposed previously for the mantle beneath Western Europe. Application of SKS technique to the data recorded in the Altai and Sayan mountains of Central Asia show strain in the mantle beneath the Altai-Sayan region is similar, both in style and scale, to strain in the crust. The receiver functions technique was used to investigate the uppermost layers in the Khibina plutonic region of northern Russia. The results suggest that short (50 km) wavelength lateral variations in the depth of crust-mantle transition persist in this region, despite the cessation of rifting activity in the Kola peninsula in Devonian times. Finally, mapping the upper mantle velocity structure of the Tibetan Plateau and its surroundings with SS-S travel time residuals suggest that while the lithospere beneath southern Tibet is thickened by the India
WFCatalog: A catalogue for seismological waveform data
Trani, Luca; Koymans, Mathijs; Atkinson, Malcolm; Sleeman, Reinoud; Filgueira, Rosa
2017-09-01
This paper reports advances in seismic waveform description and discovery leading to a new seismological service and presents the key steps in its design, implementation and adoption. This service, named WFCatalog, which stands for waveform catalogue, accommodates features of seismological waveform data. Therefore, it meets the need for seismologists to be able to select waveform data based on seismic waveform features as well as sensor geolocations and temporal specifications. We describe the collaborative design methods and the technical solution showing the central role of seismic feature catalogues in framing the technical and operational delivery of the new service. Also, we provide an overview of the complex environment wherein this endeavour is scoped and the related challenges discussed. As multi-disciplinary, multi-organisational and global collaboration is necessary to address today's challenges, canonical representations can provide a focus for collaboration and conceptual tools for agreeing directions. Such collaborations can be fostered and formalised by rallying intellectual effort into the design of novel scientific catalogues and the services that support them. This work offers an example of the benefits generated by involving cross-disciplinary skills (e.g. data and domain expertise) from the early stages of design, and by sustaining the engagement with the target community throughout the delivery and deployment process.
Does chocolate reduce blood pressure? A meta-analysis
Directory of Open Access Journals (Sweden)
Ried Karin
2010-06-01
Full Text Available Abstract Background Dark chocolate and flavanol-rich cocoa products have attracted interest as an alternative treatment option for hypertension, a known risk factor for cardiovascular disease. Previous meta-analyses concluded that cocoa-rich foods may reduce blood pressure. Recently, several additional trials have been conducted with conflicting results. Our study summarises current evidence on the effect of flavanol-rich cocoa products on blood pressure in hypertensive and normotensive individuals. Methods We searched Medline, Cochrane and international trial registries between 1955 and 2009 for randomised controlled trials investigating the effect of cocoa as food or drink compared with placebo on systolic and diastolic blood pressure (SBP/DBP for a minimum duration of 2 weeks. We conducted random effects meta-analysis of all studies fitting the inclusion criteria, as well as subgroup analysis by baseline blood pressure (hypertensive/normotensive. Meta-regression analysis explored the association between type of treatment, dosage, duration or baseline blood pressure and blood pressure outcome. Statistical significance was set at P Results Fifteen trial arms of 13 assessed studies met the inclusion criteria. Pooled meta-analysis of all trials revealed a significant blood pressure-reducing effect of cocoa-chocolate compared with control (mean BP change ± SE: SBP: -3.2 ± 1.9 mmHg, P = 0.001; DBP: -2.0 ± 1.3 mmHg, P = 0.003. However, subgroup meta-analysis was significant only for the hypertensive or prehypertensive subgroups (SBP: -5.0 ± 3.0 mmHg; P = 0.0009; DBP: -2.7 ± 2.2 mm Hg, P = 0.01, while BP was not significantly reduced in the normotensive subgroups (SBP: -1.6 ± 2.3 mmHg, P = 0.17; DBP: -1.3 ± 1.6 mmHg, P = 0.12. Nine trials used chocolate containing 50% to 70% cocoa compared with white chocolate or other cocoa-free controls, while six trials compared high- with low-flavanol cocoa products. Daily flavanol dosages ranged from 30
Picking vs Waveform based detection and location methods for induced seismicity monitoring
Grigoli, Francesco; Boese, Maren; Scarabello, Luca; Diehl, Tobias; Weber, Bernd; Wiemer, Stefan; Clinton, John F.
2017-04-01
Microseismic monitoring is a common operation in various industrial activities related to geo-resouces, such as oil and gas and mining operations or geothermal energy exploitation. In microseismic monitoring we generally deal with large datasets from dense monitoring networks that require robust automated analysis procedures. The seismic sequences being monitored are often characterized by very many events with short inter-event times that can even provide overlapped seismic signatures. In these situations, traditional approaches that identify seismic events using dense seismic networks based on detections, phase identification and event association can fail, leading to missed detections and/or reduced location resolution. In recent years, to improve the quality of automated catalogues, various waveform-based methods for the detection and location of microseismicity have been proposed. These methods exploit the coherence of the waveforms recorded at different stations and do not require any automated picking procedure. Although this family of methods have been applied to different induced seismicity datasets, an extensive comparison with sophisticated pick-based detection and location methods is still lacking. We aim here to perform a systematic comparison in term of performance using the waveform-based method LOKI and the pick-based detection and location methods (SCAUTOLOC and SCANLOC) implemented within the SeisComP3 software package. SCANLOC is a new detection and location method specifically designed for seismic monitoring at local scale. Although recent applications have proved an extensive test with induced seismicity datasets have been not yet performed. This method is based on a cluster search algorithm to associate detections to one or many potential earthquake sources. On the other hand, SCAUTOLOC is more a "conventional" method and is the basic tool for seismic event detection and location in SeisComp3. This approach was specifically designed for
Robust spike classification based on frequency domain neural waveform features.
Yang, Chenhui; Yuan, Yuan; Si, Jennie
2013-12-01
We introduce a new spike classification algorithm based on frequency domain features of the spike snippets. The goal for the algorithm is to provide high classification accuracy, low false misclassification, ease of implementation, robustness to signal degradation, and objectivity in classification outcomes. In this paper, we propose a spike classification algorithm based on frequency domain features (CFDF). It makes use of frequency domain contents of the recorded neural waveforms for spike classification. The self-organizing map (SOM) is used as a tool to determine the cluster number intuitively and directly by viewing the SOM output map. After that, spike classification can be easily performed using clustering algorithms such as the k-Means. In conjunction with our previously developed multiscale correlation of wavelet coefficient (MCWC) spike detection algorithm, we show that the MCWC and CFDF detection and classification system is robust when tested on several sets of artificial and real neural waveforms. The CFDF is comparable to or outperforms some popular automatic spike classification algorithms with artificial and real neural data. The detection and classification of neural action potentials or neural spikes is an important step in single-unit-based neuroscientific studies and applications. After the detection of neural snippets potentially containing neural spikes, a robust classification algorithm is applied for the analysis of the snippets to (1) extract similar waveforms into one class for them to be considered coming from one unit, and to (2) remove noise snippets if they do not contain any features of an action potential. Usually, a snippet is a small 2 or 3 ms segment of the recorded waveform, and differences in neural action potentials can be subtle from one unit to another. Therefore, a robust, high performance classification system like the CFDF is necessary. In addition, the proposed algorithm does not require any assumptions on statistical
Dumlao, Morphy C; Xiao, Dan; Zhang, Daming; Fletcher, John; Donald, William A
2017-04-01
Active capillary dielectric barrier discharge ionization (DBDI) is emerging as a compact, low-cost, and robust method to form intact ions of small molecules for detection in near real time by portable mass spectrometers. Here, we demonstrate that by using a 10 kHz, ~2.5 kV p-p high-voltage square-wave alternating current plasma, active capillary DBDI can consume less than 1 μW of power. In contrast, the power consumed using a sine and triangle alternating current waveform is more than two orders of magnitude higher than that for the square waveform to obtain a similar voltage for plasma generation. Moreover, the plasma obtained using a square waveform can be significantly more homogenous than that obtained using sine and triangle waveforms. Protonated dimethyl methylphosphonate (DMMP) and deprotonated perfluorooctanoic acid (PFOA) can be detected at about the same or higher abundances using square-wave DBDI mass spectrometry compared with the use of sine and triangle waveforms. By use of benzylammonium thermometer ions, the extent of internal energy deposition using square, sine, or triangle waveform excited plasmas are essentially the same at the optimum voltages for ion detection. Using an H-bridge circuit driving a transformer optimized to reduce losses, square-wave active capillary DBDI can be continuously powered for ~50 h by common 9 V-battery (PP3). Graphical Abstract ᅟ.
Stepwise compensation waveform generation by using Josephson voltage standards for joule balance
Wang, Gang; Xu, Jinxin; You, Qiang; Li, Zhengkun; Zhang, Zhonghua
2017-01-01
Flux linkage difference in the new joule balance can be obtained by the time integration of the induced voltage u(t) from the suspended coil relative to a moving magnet driven by a dc motor translation platform. Due to the finite acceleration of the dc motor, the transition and waveform of u(t) are finite and not regular. To accurately measure the time integration of u(t), a compensation waveform with precision time integration should be synthesized. In this paper, a stepwise compensation waveform is synthesized by a programmable Josephson voltage standard (PJVS) according to u(t). The accuracy of measuring the stepwise waveform with multiple transitions can be improved by reducing the ratio of the time integrated value of the total transitions to the total waveform less than one part in 102 in the joule balance. The time integration of the rise/fall transition is measured by a synchronized reference square wave generated by another PJVS system. With the total time integration more than 20 Vs, the uncertainty of the generated stepwise waveform is within 5.2 × 10-8 VsV-1s-1. The result confirms that the PJVS has the capability to generate a stepwise compensation voltage for flux linkage difference measurement.
Photonic arbitrary waveform generator based on Taylor synthesis method
DEFF Research Database (Denmark)
Liao, Shasha; Ding, Yunhong; Dong, Jianji
2016-01-01
Arbitrary waveform generation has been widely used in optical communication, radar system and many other applications. We propose and experimentally demonstrate a silicon-on-insulator (SOI) on chip optical arbitrary waveform generator, which is based on Taylor synthesis method. In our scheme......, a Gaussian pulse is launched to some cascaded microrings to obtain first-, second- and third-order differentiations. By controlling amplitude and phase of the initial pulse and successive differentiations, we can realize an arbitrary waveform generator according to Taylor expansion. We obtain several typical...... waveforms such as square waveform, triangular waveform, flat-top waveform, sawtooth waveform, Gaussian waveform and so on. Unlike other schemes based on Fourier synthesis or frequency-to-time mapping, our scheme is based on Taylor synthesis method. Our scheme does not require any spectral disperser or large...
Waveform information from quantum mechanical entropy.
Funkhouser, Scott; Suski, William; Winn, Andrew
2016-06-01
Although the entropy of a given signal-type waveform is technically zero, it is nonetheless desirable to use entropic measures to quantify the associated information. Several such prescriptions have been advanced in the literature but none are generally successful. Here, we report that the Fourier-conjugated 'total entropy' associated with quantum-mechanical probabilistic amplitude functions (PAFs) is a meaningful measure of information in non-probabilistic real waveforms, with either the waveform itself or its (normalized) analytic representation acting in the role of the PAF. Detailed numerical calculations are presented for both adaptations, showing the expected informatic behaviours in a variety of rudimentary scenarios. Particularly noteworthy are the sensitivity to the degree of randomness in a sequence of pulses and potential for detection of weak signals.
Krylov subspace acceleration of waveform relaxation
Energy Technology Data Exchange (ETDEWEB)
Lumsdaine, A.; Wu, Deyun [Univ. of Notre Dame, IN (United States)
1996-12-31
Standard solution methods for numerically solving time-dependent problems typically begin by discretizing the problem on a uniform time grid and then sequentially solving for successive time points. The initial time discretization imposes a serialization to the solution process and limits parallel speedup to the speedup available from parallelizing the problem at any given time point. This bottleneck can be circumvented by the use of waveform methods in which multiple time-points of the different components of the solution are computed independently. With the waveform approach, a problem is first spatially decomposed and distributed among the processors of a parallel machine. Each processor then solves its own time-dependent subsystem over the entire interval of interest using previous iterates from other processors as inputs. Synchronization and communication between processors take place infrequently, and communication consists of large packets of information - discretized functions of time (i.e., waveforms).
Waveform information from quantum mechanical entropy
Funkhouser, Scott; Suski, William; Winn, Andrew
2016-06-01
Although the entropy of a given signal-type waveform is technically zero, it is nonetheless desirable to use entropic measures to quantify the associated information. Several such prescriptions have been advanced in the literature but none are generally successful. Here, we report that the Fourier-conjugated `total entropy' associated with quantum-mechanical probabilistic amplitude functions (PAFs) is a meaningful measure of information in non-probabilistic real waveforms, with either the waveform itself or its (normalized) analytic representation acting in the role of the PAF. Detailed numerical calculations are presented for both adaptations, showing the expected informatic behaviours in a variety of rudimentary scenarios. Particularly noteworthy are the sensitivity to the degree of randomness in a sequence of pulses and potential for detection of weak signals.
Deakin, Charles D; Connelly, Stephanie; Wharton, Rupert; Yuen, Ho Ming
2013-03-01
Several different biphasic waveforms are used clinically, but few studies have compared their efficacy. The two main waveforms are the biphasic rectilinear (BR) and biphasic truncated exponential (BTE) waveforms, both of which have important differences, particularly at the extremes of transthoracic impedance. To compare the efficacy of two commonly used defibrillation waveforms in the elective cardioversion of atrial fibrillation. In a prospective randomized controlled study, sequential adult patients undergoing elective cardioversion for AF were recruited. Patients were randomized to receive synchronized defibrillation using either a BR or BTE waveform, both using a 50J, 100J, 150J, 200J, 200J selected energy escalating protocol. Failure to cardiovert after the fifth shock was classed as failed defibrillation. The power of this study was 80% with 5% significance level to detect a difference of 20% or greater between groups. Survival analysis was used to compare the total energy delivered to achieve successful cardioversion between groups. A total of 202 patients were recruited, of which data are complete for 199 (100 BR; 99 BTE). Median number of shocks to achieve cardioversion was 2 for the BR waveform and 3 for the BTE waveform (P = 0.059). In the BR waveform group, 95/100 (95.0%) achieved sinus rhythm. In the BTE waveform group, 90/99 (90.9%) achieved sinus rhythm and this group required on average 117.1J more energy to achieve the outcome compared to the BR waveform group (P = 0.838). BR and BTE waveforms show similar high efficacy in the elective cardioversion of atrial fibrillation. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
Waveform Design for Wireless Power Transfer
Clerckx, Bruno; Bayguzina, Ekaterina
2016-12-01
Far-field Wireless Power Transfer (WPT) has attracted significant attention in recent years. Despite the rapid progress, the emphasis of the research community in the last decade has remained largely concentrated on improving the design of energy harvester (so-called rectenna) and has left aside the effect of transmitter design. In this paper, we study the design of transmit waveform so as to enhance the DC power at the output of the rectenna. We derive a tractable model of the non-linearity of the rectenna and compare with a linear model conventionally used in the literature. We then use those models to design novel multisine waveforms that are adaptive to the channel state information (CSI). Interestingly, while the linear model favours narrowband transmission with all the power allocated to a single frequency, the non-linear model favours a power allocation over multiple frequencies. Through realistic simulations, waveforms designed based on the non-linear model are shown to provide significant gains (in terms of harvested DC power) over those designed based on the linear model and over non-adaptive waveforms. We also compute analytically the theoretical scaling laws of the harvested energy for various waveforms as a function of the number of sinewaves and transmit antennas. Those scaling laws highlight the benefits of CSI knowledge at the transmitter in WPT and of a WPT design based on a non-linear rectenna model over a linear model. Results also motivate the study of a promising architecture relying on large-scale multisine multi-antenna waveforms for WPT. As a final note, results stress the importance of modeling and accounting for the non-linearity of the rectenna in any system design involving wireless power.
Signal processing in noise waveform radar
Kulpa, Krzysztof
2013-01-01
This book is devoted to the emerging technology of noise waveform radar and its signal processing aspects. It is a new kind of radar, which use noise-like waveform to illuminate the target. The book includes an introduction to basic radar theory, starting from classical pulse radar, signal compression, and wave radar. The book then discusses the properties, difficulties and potential of noise radar systems, primarily for low-power and short-range civil applications. The contribution of modern signal processing techniques to making noise radar practical are emphasized, and application examples
Principles of waveform diversity and design
Wicks, Michael
2011-01-01
This is the first book to discuss current and future applications of waveform diversity and design in subjects such as radar and sonar, communications systems, passive sensing, and many other technologies. Waveform diversity allows researchers and system designers to optimize electromagnetic and acoustic systems for sensing, communications, electronic warfare or combinations thereof. This book enables solutions to problems, explaining how each system performs its own particular function, as well as how it is affected by other systems and how those other systems may likewise be affected. It is
Colocated MIMO Radar: Beamforming, Waveform design, and Target Parameter Estimation
Jardak, Seifallah
2014-04-01
Thanks to its improved capabilities, the Multiple Input Multiple Output (MIMO) radar is attracting the attention of researchers and practitioners alike. Because it transmits orthogonal or partially correlated waveforms, this emerging technology outperformed the phased array radar by providing better parametric identifiability, achieving higher spatial resolution, and designing complex beampatterns. To avoid jamming and enhance the signal to noise ratio, it is often interesting to maximize the transmitted power in a given region of interest and minimize it elsewhere. This problem is known as the transmit beampattern design and is usually tackled as a two-step process: a transmit covariance matrix is firstly designed by minimizing a convex optimization problem, which is then used to generate practical waveforms. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method maps easily generated Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability density function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. The second part of this thesis covers the topic of target parameter estimation. To determine the reflection coefficient, spatial location, and Doppler shift of a target, maximum likelihood estimation yields the best performance. However, it requires a two dimensional search problem. Therefore, its computational complexity is prohibitively high. So, we proposed a reduced complexity and optimum performance algorithm which allows the two dimensional fast Fourier transform to jointly estimate the spatial location
Bennett, Johan R; Darragh, Karen M; Walsh, Simon J; Allen, Desmond J; Scott, Michael; Stevenson, Michael; Adgey, Jennifer A A; Anderson, John M C J; Manoharan, Ganesh
2014-03-01
Commercially available implantable defibrillators utilize a high-tilt waveform. Studies in atrial fibrillation and transthoracic defibrillation of ventricular fibrillation (VF) have shown improved defibrillation efficacy using low-tilt (LT) waveforms. We investigated the feasibility, efficacy, and safety of a LT waveform in the transvenous defibrillation of VF and hypothesized that it would be more efficacious than standard tilted biphasic (STB) waveforms. The investigation was performed in four phases in a porcine model: an efficacy study of LT monophasic waveforms (n = 9), an efficacy study of LT biphasic waveforms (n = 9), a comparison study between the most successful LT waveforms and clinically available STB waveforms (n = 15), and a safety study (n = 9). A total of 1,056 shocks were delivered (phase 1: 288, phase 2: 288, phase 3: 480). The LT biphasic 8/4-ms waveform was significantly more likely to successfully defibrillate than the LT monophasic and STB waveforms with an odds ratio of 122.3 (95% confidence interval: 32.5, 460.2, P defibrillation threshold (E50) for the LT 8/4-ms waveform was 12.7 J compared to 43.5 J and 45.5 J for STB waveforms 6/6 ms and 8/4 ms, respectively, and 47.7 J for LT 12-ms waveform. The LT 8/4-ms waveform had no lasting detrimental effect on cardiac function, and any transient hemodynamical or biochemical changes observed were comparable to those observed with STB waveforms. LT waveforms are effective and appear safe in transvenous defibrillation in a porcine model of VF. The LT biphasic 8/4-ms waveform is more efficacious than conventional waveforms. ©2013, The Authors. Journal compilation ©2013 Wiley Periodicals, Inc.
Waveform Analysis of UWB GPR Antennas
Directory of Open Access Journals (Sweden)
Julia Armesto
2009-03-01
Full Text Available Ground Penetrating Radar (GPR systems fall into the category of ultra-wideband (UWB devices. Most GPR equipment covers a frequency range between an octave and a decade by using short-time pulses. Each signal recorded by a GPR gathers a temporal log of attenuated and distorted versions of these pulses (due to the effect of the propagation medium plus possible electromagnetic interferences and noise. In order to make a good interpretation of this data and extract the most possible information during processing, a deep knowledge of the wavelet emitted by the antennas is essential. Moreover, some advanced processing techniques require specific knowledge of this signal to obtain satisfactory results. In this work, we carried out a series of tests in order to determine the source wavelet emitted by a ground-coupled antenna with a 500 MHz central frequency.
Glycolysis selectively shapes the presynaptic action potential waveform.
Lujan, Brendan; Kushmerick, Christopher; Banerjee, Tania Das; Dagda, Ruben K; Renden, Robert
2016-12-01
Mitochondria are major suppliers of cellular energy in neurons; however, utilization of energy from glycolysis vs. mitochondrial oxidative phosphorylation (OxPhos) in the presynaptic compartment during neurotransmission is largely unknown. Using presynaptic and postsynaptic recordings from the mouse calyx of Held, we examined the effect of acute selective pharmacological inhibition of glycolysis or mitochondrial OxPhos on multiple mechanisms regulating presynaptic function. Inhibition of glycolysis via glucose depletion and iodoacetic acid (1 mM) treatment, but not mitochondrial OxPhos, rapidly altered transmission, resulting in highly variable, oscillating responses. At reduced temperature, this same treatment attenuated synaptic transmission because of a smaller and broader presynaptic action potential (AP) waveform. We show via experimental manipulation and ion channel modeling that the altered AP waveform results in smaller Ca 2+ influx, resulting in attenuated excitatory postsynaptic currents (EPSCs). In contrast, inhibition of mitochondria-derived ATP production via extracellular pyruvate depletion and bath-applied oligomycin (1 μM) had no significant effect on Ca 2+ influx and did not alter the AP waveform within the same time frame (up to 30 min), and the resultant EPSC remained unaffected. Glycolysis, but not mitochondrial OxPhos, is thus required to maintain basal synaptic transmission at the presynaptic terminal. We propose that glycolytic enzymes are closely apposed to ATP-dependent ion pumps on the presynaptic membrane. Our results indicate a novel mechanism for the effect of hypoglycemia on neurotransmission. Attenuated transmission likely results from a single presynaptic mechanism at reduced temperature: a slower, smaller AP, before and independent of any effect on synaptic vesicle release or receptor activity. Copyright © 2016 the American Physiological Society.
Waveform relaxation methods for implicit differential equations
P.J. van der Houwen; W.A. van der Veen
1996-01-01
textabstractWe apply a Runge-Kutta-based waveform relaxation method to initial-value problems for implicit differential equations. In the implementation of such methods, a sequence of nonlinear systems has to be solved iteratively in each step of the integration process. The size of these systems
Analog circuit design designing waveform processing circuits
Feucht, Dennis
2010-01-01
The fourth volume in the set Designing Waveform-Processing Circuits builds on the previous 3 volumes and presents a variety of analog non-amplifier circuits, including voltage references, current sources, filters, hysteresis switches and oscilloscope trigger and sweep circuitry, function generation, absolute-value circuits, and peak detectors.
Boardsen, Scott A.; Hospodarsky, George B.; Kletzing, Craig A.; Engebretson, Mark J.; Pfaff, Robert F.; Wygant, John R.; Kurth, William S.; Averkamp, Terrance F.; Bounds, Scott R.; Green, Jim L.;
2016-01-01
We present a statistical survey of the latitudinal structure of the fast magnetosonic wave mode detected by the Van Allen Probes spanning the time interval of 21 September 2012 to 1 August 2014. We show that statistically, the latitudinal occurrence of the wave frequency (f) normalized by the local proton cyclotron frequency (f(sub cP)) has a distinct funnel-shaped appearance in latitude about the magnetic equator similar to that found in case studies. By comparing the observed E/B ratios with the model E/B ratio, using the observed plasma density and background magnetic field magnitude as input to the model E/B ratio, we show that this mode is consistent with the extra-ordinary (whistler) mode at wave normal angles (theta(sub k)) near 90 deg. Performing polarization analysis on synthetic waveforms composed from a superposition of extra-ordinary mode plane waves with theta(sub k) randomly chosen between 87 and 90 deg, we show that the uncertainty in the derived wave normal is substantially broadened, with a tail extending down to theta(sub k) of 60 deg, suggesting that another approach is necessary to estimate the true distribution of theta(sub k). We find that the histograms of the synthetically derived ellipticities and theta(sub k) are consistent with the observations of ellipticities and theta(sub k) derived using polarization analysis.We make estimates of the median equatorial theta(sub k) by comparing observed and model ray tracing frequency-dependent probability occurrence with latitude and give preliminary frequency dependent estimates of the equatorial theta(sub k) distribution around noon and 4 R(sub E), with the median of approximately 4 to 7 deg from 90 deg at f/f(sub cP) = 2 and dropping to approximately 0.5 deg from 90 deg at f/f(sub cP) = 30. The occurrence of waves in this mode peaks around noon near the equator at all radial distances, and we find that the overall intensity of these waves increases with AE*, similar to findings of other studies.
JTRS/SCA and Custom/SDR Waveform Comparison
Oldham, Daniel R.; Scardelletti, Maximilian C.
2007-01-01
This paper compares two waveform implementations generating the same RF signal using the same SDR development system. Both waveforms implement a satellite modem using QPSK modulation at 1M BPS data rates with one half rate convolutional encoding. Both waveforms are partitioned the same across the general purpose processor (GPP) and the field programmable gate array (FPGA). Both waveforms implement the same equivalent set of radio functions on the GPP and FPGA. The GPP implements the majority of the radio functions and the FPGA implements the final digital RF modulator stage. One waveform is implemented directly on the SDR development system and the second waveform is implemented using the JTRS/SCA model. This paper contrasts the amount of resources to implement both waveforms and demonstrates the importance of waveform partitioning across the SDR development system.
Manicke, Nicholas E.; Belford, Michael
2015-05-01
One limitation in the growing field of ambient or direct analysis methods is reduced selectivity caused by the elimination of chromatographic separations prior to mass spectrometric analysis. We explored the use of high-field asymmetric waveform ion mobility spectrometry (FAIMS), an ambient pressure ion mobility technique, to separate the closely related opiate isomers of morphine, hydromorphone, and norcodeine. These isomers cannot be distinguished by tandem mass spectrometry. Separation prior to MS analysis is, therefore, required to distinguish these compounds, which are important in clinical chemistry and toxicology. FAIMS was coupled to a triple quadrupole mass spectrometer, and ionization was performed using either a pneumatically assisted heated electrospray ionization source (H-ESI) or paper spray, a direct analysis method that has been applied to the direct analysis of dried blood spots and other complex samples. We found that FAIMS was capable of separating the three opiate structural isomers using both H-ESI and paper spray as the ionization source.
SAR processing with non-linear FM chirp waveforms.
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter
2006-12-01
Nonlinear FM (NLFM) waveforms offer a radar matched filter output with inherently low range sidelobes. This yields a 1-2 dB advantage in Signal-to-Noise Ratio over the output of a Linear FM (LFM) waveform with equivalent sidelobe filtering. This report presents details of processing NLFM waveforms in both range and Doppler dimensions, with special emphasis on compensating intra-pulse Doppler, often cited as a weakness of NLFM waveforms.
A long source area of the 1906 Colombia-Ecuador earthquake estimated from observed tsunami waveforms
Yamanaka, Yusuke; Tanioka, Yuichiro; Shiina, Takahiro
2017-12-01
The 1906 Colombia-Ecuador earthquake induced both strong seismic motions and a tsunami, the most destructive earthquake in the history of the Colombia-Ecuador subduction zone. The tsunami propagated across the Pacific Ocean, and its waveforms were observed at tide gauge stations in countries including Panama, Japan, and the USA. This study conducted slip inverse analysis for the 1906 earthquake using these waveforms. A digital dataset of observed tsunami waveforms at the Naos Island (Panama) and Honolulu (USA) tide gauge stations, where the tsunami was clearly observed, was first produced by consulting documents. Next, the two waveforms were applied in an inverse analysis as the target waveform. The results of this analysis indicated that the moment magnitude of the 1906 earthquake ranged from 8.3 to 8.6. Moreover, the dominant slip occurred in the northern part of the assumed source region near the coast of Colombia, where little significant seismicity has occurred, rather than in the southern part. The results also indicated that the source area, with significant slip, covered a long distance, including the southern, central, and northern parts of the region.[Figure not available: see fulltext.
Short ECG segments predict defibrillation outcome using quantitative waveform measures.
Coult, Jason; Sherman, Lawrence; Kwok, Heemun; Blackwood, Jennifer; Kudenchuk, Peter J; Rea, Thomas D
2016-12-01
Quantitative waveform measures of the ventricular fibrillation (VF) electrocardiogram (ECG) predict defibrillation outcome. Calculation requires an ECG epoch without chest compression artifact. However, pauses in CPR can adversely affect survival. Thus the potential use of waveform measures is limited by the need to pause CPR. We sought to characterize the relationship between the length of the CPR-free epoch and the ability to predict outcome. We conducted a retrospective investigation using the CPR-free ECG prior to first shock among out-of-hospital VF cardiac arrest patients in a large metropolitan region (n=442). Amplitude Spectrum Area (AMSA) and Median Slope (MS) were calculated using ECG epochs ranging from 5s to 0.2s. The relative ability of the measures to predict return of organized rhythm (ROR) and neurologically-intact survival was evaluated at different epoch lengths by calculating the area under the receiver operating characteristic curve (AUC) using the 5-s epoch as the referent group. Compared to the 5-s epoch, AMSA performance declined significantly only after reducing epoch length to 0.2s for ROR (AUC 0.77-0.74, p=0.03) and with epochs of ≤0.6s for neurologically-intact survival (AUC 0.72-0.70, p=0.04). MS performance declined significantly with epochs of ≤0.8s for ROR (AUC 0.78-0.77, p=0.04) and with epochs ≤1.6s for neurologically-intact survival (AUC 0.72-0.71, p=0.04). Waveform measures predict defibrillation outcome using very brief ECG epochs, a quality that may enable their use in current resuscitation algorithms designed to limit CPR interruption. Copyright Â© 2016 Elsevier Ireland Ltd. All rights reserved.
Hirschl, M M; Kittler, H; Woisetschläger, C; Siostrzonek, P; Staudinger, T; Kofler, J; Oschatz, E; Bur, A; Gwechenberger, M; Laggner, A N
2000-06-01
To compare the accuracy and reliability of thoracic electrical bioimpedance (TEB) and the arterial pulse waveform analysis with simultaneous measurement of thermodilution cardiac output (TD-CO) in critically ill patients. Prospective data collection. Emergency department and critical care unit in a 2,000-bed inner-city hospital. A total of 29 critically ill patients requiring invasive hemodynamic monitoring for clinical management were prospectively studied. Noninvasive cardiac output was simultaneously measured by a TEB device and by analysis of the arterial pulse waveform derived from the finger artery. Invasive cardiac output was determined by the thermodilution technique. A total of 175 corresponding TD-CO and noninvasive hemodynamic measurements were collected in 30-min intervals. They revealed an overall bias of 0.34 L/min/m2 (95% confidence interval, 0.24-0.44 L/min/m2; p 0.50 L/min/m2. The discrepancies of the arterial pulse waveform analysis correlated positively with the magnitude of the cardiac index (r2 = 0.29; p 0.50 L/min/m2. The magnitude of the discrepancies of the TEB was significantly correlated with age (r2 = 0.17; p = .02). Measurements were in phase in 93.2% of all arterial pulse waveform analysis and in 84.9% of all TEB readings (p < .001). The arterial pulse waveform analysis exhibits a greater accuracy and reliability as compared with the TEB with regard to overall bias, number of inaccurate readings, and phase lags. The arterial pulse waveform analysis may be useful for the monitoring of hemodynamic changes. However, both methods fail to be a substitute for the TD-CO because of a substantial percentage of inaccurate readings.
Porcine defibrillation thresholds with chopped biphasic truncated exponential waveforms.
Sullivan, Joseph L; Melnick, Sharon B; Chapman, Fred W; Walcott, Gregory P
2007-08-01
Conventional biphasic truncated exponential (BTE) waveforms have been studied extensively but less is known about "chopping modulated" BTE shocks. Previous studies comparing chopped and unchopped waveforms have found conflicting results. This study compared the defibrillation thresholds (DFTs) of a variety of chopped and unchopped BTE waveforms. Six anesthetized pigs were defibrillated after 15s of electrically induced ventricular fibrillation (VF). Three waveform types were studied: unchopped BTE, "short" duration chopped, and "long" duration chopped waveforms. Each type included waveforms generated with 50, 100, and 200 microF capacitances, giving 9 total waveforms. Shocks were delivered in a standard up-down protocol and the order of the waveforms was randomized. Defibrillation thresholds were calculated using a Bayesian logistic regression model. DFTs of the 50, 100, and 200 microF unchopped waveforms were 122+/-22, 124+/-22, and 126+/-22 J. Short chopped DFTs were at least 75+/-23 J higher than unchopped DFTs. Long chopped DFTs averaged 66+/-20 J more than short chopped DFTs. There is a 99.5% probability that the best of the chopped waveforms has a higher DFT than the worst of the unchopped waveforms, and a 95% probability that the difference is at least 37 J. DFT differences between capacitor values were less than 7 J for all waveform types. When treating swine with short-duration VF, chopped waveforms require more energy to defibrillate than unchopped waveforms. More study is required to assess the performance of chopped waveforms when treating cardiac arrest patients.
Wang, Lu; Xu, Lisheng; Feng, Shuting; Meng, Max Q-H; Wang, Kuanquan
2013-11-01
Analysis of pulse waveform is a low cost, non-invasive method for obtaining vital information related to the conditions of the cardiovascular system. In recent years, different Pulse Decomposition Analysis (PDA) methods have been applied to disclose the pathological mechanisms of the pulse waveform. All these methods decompose single-period pulse waveform into a constant number (such as 3, 4 or 5) of individual waves. Furthermore, those methods do not pay much attention to the estimation error of the key points in the pulse waveform. The estimation of human vascular conditions depends on the key points' positions of pulse wave. In this paper, we propose a Multi-Gaussian (MG) model to fit real pulse waveforms using an adaptive number (4 or 5 in our study) of Gaussian waves. The unknown parameters in the MG model are estimated by the Weighted Least Squares (WLS) method and the optimized weight values corresponding to different sampling points are selected by using the Multi-Criteria Decision Making (MCDM) method. Performance of the MG model and the WLS method has been evaluated by fitting 150 real pulse waveforms of five different types. The resulting Normalized Root Mean Square Error (NRMSE) was less than 2.0% and the estimation accuracy for the key points was satisfactory, demonstrating that our proposed method is effective in compressing, synthesizing and analyzing pulse waveforms. Copyright © 2013 Elsevier Ltd. All rights reserved.
Reducing the uncertainty in robotic machining by modal analysis
Alberdi, Iñigo; Pelegay, Jose Angel; Arrazola, Pedro Jose; Ørskov, Klaus Bonde
2017-10-01
The use of industrial robots for machining could lead to high cost and energy savings for the manufacturing industry. Machining robots offer several advantages respect to CNC machines such as flexibility, wide working space, adaptability and relatively low cost. However, there are some drawbacks that are preventing a widespread adoption of robotic solutions namely lower stiffness, vibration/chatter problems and lower accuracy and repeatability. Normally due to these issues conservative cutting parameters are chosen, resulting in a low material removal rate (MRR). In this article, an example of a modal analysis of a robot is presented. For that purpose the Tap-testing technology is introduced, which aims at maximizing productivity, reducing the uncertainty in the selection of cutting parameters and offering a stable process free from chatter vibrations.
Reducing spatial uncertainty in climatic maps through geostatistical analysis
Pesquer, Lluís; Ninyerola, Miquel; Pons, Xavier
2014-05-01
Climatic maps from meteorological stations and geographical co-variables can be obtained through correlative models (Ninyerola et al., 2000)*. Nevertheless, the spatial uncertainty of the resulting maps could be reduced. The present work is a new stage over those approaches aiming to study how to obtain better results while characterizing spatial uncertainty. The study area is Catalonia (32000 km2), a region with highly variable relief (0 to 3143 m). We have used 217 stations (321 to 1244 mm) to model the annual precipitation in two steps: 1/ multiple regression using geographical variables (elevation, distance to the coast, latitude, etc) and 2/ refinement of the results by adding the spatial interpolation of the regression residuals with inverse distance weighting (IDW), regularized splines with tension (SPT) or ordinary kriging (OK). Spatial uncertainty analysis is based on an independent subsample (test set), randomly selected in previous works. The main contribution of this work is the analysis of this test set as well as the search for an optimal process of division (split) of the stations in two sets, one used to perform the multiple regression and residuals interpolation (fit set), and another used to compute the quality (test set); optimal division should reduce spatial uncertainty and improve the overall quality. Two methods have been evaluated against classical methods: (random selection RS and leave-one-out cross-validation LOOCV): selection by Euclidian 2D-distance, and selection by anisotropic 2D-distance combined with a 3D-contribution (suitable weighted) from the most representative independent variable. Both methods define a minimum threshold distance, obtained by variogram analysis, between samples. Main preliminary results for LOOCV, RS (average from 10 executions), Euclidian criterion (EU), and for anisotropic criterion (with 1.1 value, UTMY coordinate has a bit more weight than UTMX) combined with 3D criteria (A3D) (1000 factor for elevation
Blackman, Jonathan; Field, Scott E.; Scheel, Mark A.; Galley, Chad R.; Hemberger, Daniel A.; Schmidt, Patricia; Smith, Rory
2017-05-01
We present the first surrogate model for gravitational waveforms from the coalescence of precessing binary black holes. We call this surrogate model NRSur4d2s. Our methodology significantly extends recently introduced reduced-order and surrogate modeling techniques, and is capable of directly modeling numerical relativity waveforms without introducing phenomenological assumptions or approximations to general relativity. Motivated by GW150914, LIGO's first detection of gravitational waves from merging black holes, the model is built from a set of 276 numerical relativity (NR) simulations with mass ratios q ≤2 , dimensionless spin magnitudes up to 0.8, and the restriction that the initial spin of the smaller black hole lies along the axis of orbital angular momentum. It produces waveforms which begin ˜30 gravitational wave cycles before merger and continue through ringdown, and which contain the effects of precession as well as all ℓ∈{2 ,3 } spin-weighted spherical-harmonic modes. We perform cross-validation studies to compare the model to NR waveforms not used to build the model and find a better agreement within the parameter range of the model than other, state-of-the-art precessing waveform models, with typical mismatches of 10-3. We also construct a frequency domain surrogate model (called NRSur4d2s_FDROM) which can be evaluated in 50 ms and is suitable for performing parameter estimation studies on gravitational wave detections similar to GW150914.
Gold - A novel deconvolution algorithm with optimization for waveform LiDAR processing
Zhou, Tan; Popescu, Sorin C.; Krause, Keith; Sheridan, Ryan D.; Putman, Eric
2017-07-01
Waveform Light Detection and Ranging (LiDAR) data have advantages over discrete-return LiDAR data in accurately characterizing vegetation structure. However, we lack a comprehensive understanding of waveform data processing approaches under different topography and vegetation conditions. The objective of this paper is to highlight a novel deconvolution algorithm, the Gold algorithm, for processing waveform LiDAR data with optimal deconvolution parameters. Further, we present a comparative study of waveform processing methods to provide insight into selecting an approach for a given combination of vegetation and terrain characteristics. We employed two waveform processing methods: (1) direct decomposition, (2) deconvolution and decomposition. In method two, we utilized two deconvolution algorithms - the Richardson-Lucy (RL) algorithm and the Gold algorithm. The comprehensive and quantitative comparisons were conducted in terms of the number of detected echoes, position accuracy, the bias of the end products (such as digital terrain model (DTM) and canopy height model (CHM)) from the corresponding reference data, along with parameter uncertainty for these end products obtained from different methods. This study was conducted at three study sites that include diverse ecological regions, vegetation and elevation gradients. Results demonstrate that two deconvolution algorithms are sensitive to the pre-processing steps of input data. The deconvolution and decomposition method is more capable of detecting hidden echoes with a lower false echo detection rate, especially for the Gold algorithm. Compared to the reference data, all approaches generate satisfactory accuracy assessment results with small mean spatial difference (parameter uncertainty analysis demonstrates that the Gold algorithm outperforms other approaches in dense vegetation areas, with the smallest RMSE, and the RL algorithm performs better in sparse vegetation areas in terms of RMSE. Additionally, the high
Early Cambrian wave-formed shoreline deposits
DEFF Research Database (Denmark)
Clemmensen, Lars B; Glad, Aslaug Clemmensen; Pedersen, Gunver Krarup
2017-01-01
. During this period, wave-formed shoreline sediments (the Vik Member, Hardeberga Formation) were deposited on Bornholm and are presently exposed at Strøby quarry. The sediments consist of fine- and medium-grained quartz-cemented arenites in association with a few silt-rich mudstones. The presence of well......-preserved subaqueous dunes and wave ripples indicates deposition in a wave-dominated upper shoreface (littoral zone) environment, and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and/or changing meteorological conditions. Discoidal...... imprints is related to either the formation of thin mud layers, formed during a period of calm water when winds blew offshore for a longer period, or to the growth of bacterial mats. The orientation of the wave-formed bedforms indicates a local palaeoshoreline trending NE–SW and facing a large ocean...
Programmable Clock Waveform Generation for CCD Readout
Energy Technology Data Exchange (ETDEWEB)
Vicente, J. de; Castilla, J.; Martinez, G.; Marin, J.
2006-07-01
Charge transfer efficiency in CCDs is closely related to the clock waveform. In this paper, an experimental framework to explore different FPGA based clock waveform generator designs is described. Two alternative design approaches for controlling the rise/fall edge times and pulse width of the CCD clock signal have been implemented: level-control and time-control. Both approaches provide similar characteristics regarding the edge linearity and noise. Nevertheless, dissimilarities have been found with respect to the area and frequency range of application. Thus, while the time-control approach consumes less area, the level control approach provides a wider range of clock frequencies since it does not suffer capacitor discharge effect. (Author) 8 refs.
Prototype of a transient waveform recording ASIC
Qin, J.; Zhao, L.; Cheng, B.; Chen, H.; Guo, Y.; Liu, S.; An, Q.
2018-01-01
The paper presents the design and measurement results of a transient waveform recording ASIC based on the Switched Capacitor Array (SCA) architecture. This 0.18 μm CMOS prototype device contains two channels and each channel employs a SCA of 128 samples deep, a 12-bit Wilkinson ADC and a serial data readout. A series of tests have been conducted and the results indicate that: a full 1 V signal voltage range is available, the input analog bandwidth is approximately 450 MHz and the sampling speed is adjustable from 0.076 to 3.2 Gsps (Gigabit Samples Per Second). For precision waveform timing extraction, careful calibration of timing intervals between samples is conducted to improve the timing resolution of such chips, and the timing precision of this ASIC is proved to be better than 15 ps RMS.
Large-scale seismic waveform quality metric calculation using Hadoop
Magana-Zook, S.; Gaylord, J. M.; Knapp, D. R.; Dodge, D. A.; Ruppert, S. D.
2016-09-01
In this work we investigated the suitability of Hadoop MapReduce and Apache Spark for large-scale computation of seismic waveform quality metrics by comparing their performance with that of a traditional distributed implementation. The Incorporated Research Institutions for Seismology (IRIS) Data Management Center (DMC) provided 43 terabytes of broadband waveform data of which 5.1 TB of data were processed with the traditional architecture, and the full 43 TB were processed using MapReduce and Spark. Maximum performance of 0.56 terabytes per hour was achieved using all 5 nodes of the traditional implementation. We noted that I/O dominated processing, and that I/O performance was deteriorating with the addition of the 5th node. Data collected from this experiment provided the baseline against which the Hadoop results were compared. Next, we processed the full 43 TB dataset using both MapReduce and Apache Spark on our 18-node Hadoop cluster. These experiments were conducted multiple times with various subsets of the data so that we could build models to predict performance as a function of dataset size. We found that both MapReduce and Spark significantly outperformed the traditional reference implementation. At a dataset size of 5.1 terabytes, both Spark and MapReduce were about 15 times faster than the reference implementation. Furthermore, our performance models predict that for a dataset of 350 terabytes, Spark running on a 100-node cluster would be about 265 times faster than the reference implementation. We do not expect that the reference implementation deployed on a 100-node cluster would perform significantly better than on the 5-node cluster because the I/O performance cannot be made to scale. Finally, we note that although Big Data technologies clearly provide a way to process seismic waveform datasets in a high-performance and scalable manner, the technology is still rapidly changing, requires a high degree of investment in personnel, and will likely
Should compression of coded waveforms be done before or after focusing
DEFF Research Database (Denmark)
Bjerngaard, R.T.; Jensen, Jørgen Arendt
2002-01-01
In medical ultrasound signal-to-noise ratio improvements of approximately 15-20 dB can be achieved by using coded waveforms. Exciting the transducer with an encoded waveform necessitates compression of the response which is computationally demanding. This paper investigates the possibility...... of reducing the workload without introducing errors. Ne 1 compression ltrations (convolutions) can be saved by inverting the precedence of compression and beamforming (called post-compression), when Ne is the number of transducer elements. Postcompression with dynamic receive focusing will theoretically...
Full-waveform inversion: Filling the gaps
Beydoun, Wafik B.
2015-09-01
After receiving an outstanding response to its inaugural workshop in 2013, SEG once again achieved great success with its 2015 SEG Middle East Workshop, “Full-waveform inversion: Filling the gaps,” which took place 30 March–1 April 2015 in Abu Dhabi, UAE. The workshop was organized by SEG, and its partner sponsors were Saudi Aramco (gold sponsor), ExxonMobil, and CGG. Read More: http://library.seg.org/doi/10.1190/tle34091106.1
The European seismological waveform framework EIDA
Trani, Luca; Koymans, Mathijs; Quinteros, Javier; Heinloo, Andres; Euchner, Fabian; Strollo, Angelo; Sleeman, Reinoud; Clinton, John; Stammler, Klaus; Danecek, Peter; Pedersen, Helle; Ionescu, Constantin; Pinar, Ali; Evangelidis, Christos
2017-04-01
The ORFEUS1 European Integrated Data Archive (EIDA2) federates (currently) 11 major European seismological data centres into a common organisational and operational framework which offers: (a) transparent and uniform access tools, advanced services and products for seismological waveform data; (b) a platform for establishing common policies for the curation of seismological waveform data and the description of waveform data by standardised quality metrics; (c) proper attribution and citation (e.g. data ownership). After its establishment in 2013, EIDA has been collecting and distributing seamlessly large amounts of seismological data and products to the research community and beyond. A major task of EIDA is the on-going improvement of the services, tools and products portfolio in order to meet the increasingly demanding users' requirements. At present EIDA is entering a new operational phase and will become the reference infrastructure for seismological waveform data in the pan-European infrastructure for solid-Earth science: EPOS (European Plate Observing System)3. The EIDA Next Generation developments, initiated within the H2020 project EPOS-IP, will provide a new infrastructure that will support the seismological and multidisciplinary EPOS community facilitating interoperability in a broader context. EIDA NG comprises a number of new services and products e.g.: Routing Service, Authentication Service, WFCatalog, Mediator, Station Book and more in the near future. In this contribution we present the current status of the EIDA NG developments and provide an overview of the usage of the new services and their impact on the user community. 1 www.orfeus-eu.org/ 2 www.orfeus-eu.org/eida/eida.html 3 www.epos-ip.org
Advanced Waveform Simulation for Seismic Monitoring
2008-09-01
velocity model. The method separates the main arrivals of the regional waveform into 5 windows: Pnl (vertical and radial components), Rayleigh (vertical and...ranges out to 10°, including extensive observations of crustal thinning and thickening and various Pnl complexities. Broadband modeling in 1D, 2D...existing models perform in predicting the various regional phases, Rayleigh waves, Love waves, and Pnl waves. Previous events from this Basin-and-Range
Flexible waveform-constrained optimization design method for cognitive radar
Zhang, Xiaowen; Wang, Kaizhi; Liu, Xingzhao
2017-07-01
The problem of waveform optimization design for cognitive radar (CR) in the presence of extended target with unknown target impulse response (TIR) is investigated. On the premise of ensuring the TIR estimation precision, a flexible waveform-constrained optimization design method taking both target detection and range resolution into account is proposed. In this method, both the estimate of TIR and transmitted waveform can be updated according to the environment information fed back by the receiver. Moreover, rather than optimizing waveforms for a single design criterion, the framework can synthesize waveforms that provide a trade-off between competing design criteria. The trade-off is determined by the parameter settings, which can be adjusted according to the requirement of radar performance in each cycle of CR. Simulation results demonstrate that CR with the proposed waveform performs better than a traditional radar system with a fixed waveform and offers more flexibility and practicability.
Sparse Frequency Waveform Design for Radar-Embedded Communication
Directory of Open Access Journals (Sweden)
Chaoyun Mai
2016-01-01
Full Text Available According to the Tag application with function of covert communication, a method for sparse frequency waveform design based on radar-embedded communication is proposed. Firstly, sparse frequency waveforms are designed based on power spectral density fitting and quasi-Newton method. Secondly, the eigenvalue decomposition of the sparse frequency waveform sequence is used to get the dominant space. Finally the communication waveforms are designed through the projection of orthogonal pseudorandom vectors in the vertical subspace. Compared with the linear frequency modulation waveform, the sparse frequency waveform can further improve the bandwidth occupation of communication signals, thus achieving higher communication rate. A certain correlation exists between the reciprocally orthogonal communication signals samples and the sparse frequency waveform, which guarantees the low SER (signal error rate and LPI (low probability of intercept. The simulation results verify the effectiveness of this method.
Time-dependent phase error correction using digital waveform synthesis
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin W.; Buskirk, Stephen
2017-10-10
The various technologies presented herein relate to correcting a time-dependent phase error generated as part of the formation of a radar waveform. A waveform can be pre-distorted to facilitate correction of an error induced into the waveform by a downstream operation/component in a radar system. For example, amplifier power droop effect can engender a time-dependent phase error in a waveform as part of a radar signal generating operation. The error can be quantified and an according complimentary distortion can be applied to the waveform to facilitate negation of the error during the subsequent processing of the waveform. A time domain correction can be applied by a phase error correction look up table incorporated into a waveform phase generator.
Seismic Structure of Southeast Asia from Full Waveform Seismic Ambient Noise Tomography
Cummins, P. R.; Saygin, E.; Fichtner, A.; Masturyono, M.
2015-12-01
We image the lower crust and upper-mantle structure of Southeast Asia with a 3D full waveform adjoint inversion scheme by directly inverting Green's functions retrieved from interstation seismic noise correlations. Synthetic Green's functions are computed at a period range between 10 and 40 s to simulate the wave propagation in the region. Misfits between observed and synthetic waveforms are reduced by iteratively updating model parameters using sensitivity kernels with a conjugate-gradient optimization method. The final model is verified via comparing the simulated waveforms with the recorded earthquakes in the region. The balanced coverage of rays in the region enabled us to image complex structure. The Australian plate is characterized with higher velocities for most of the crust, where most of Indonesia, and its surroundings show complex structure with low velocities. The transition from the oceanic part of the Australian Plate to the continental crust adjacent to the Banda Arc is clearly imaged.
Käufl, P.; Fichtner, A.; Igel, H.
2013-01-01
We present a first study to investigate the feasibility of a probabilistic 3-D full waveform inversion based on spectral-element simulations of seismic wave propagation and Monte Carlo exploration of the model space. Through a tectonic regionalization we reduce the dimension of the model space to
Coordinating Complementary Waveforms for Sidelobe Suppression
Dang, Wenbing; Howard, Stephen; Moran, William; Calderbank, Robert
2012-01-01
We present a general method for constructing radar transmit pulse trains and receive filters for which the radar point-spread function in delay and Doppler, given by the cross-ambiguity function of the transmit pulse train and the pulse train used in the receive filter, is essentially free of range sidelobes inside a Doppler interval around the zero-Doppler axis. The transmit pulse train is constructed by coordinating the transmission of a pair of Golay complementary waveforms across time according to zeros and ones in a binary sequence P. The pulse train used to filter the received signal is constructed in a similar way, in terms of sequencing the Golay waveforms, but each waveform in the pulse train is weighted by an element from another sequence Q. We show that a spectrum jointly determined by P and Q sequences controls the size of the range sidelobes of the cross-ambiguity function and by properly choosing P and Q we can clear out the range sidelobes inside a Doppler interval around the zero- Doppler axis...
Continuous high PRF waveforms for challenging environments
Jaroszewski, Steven; Corbeil, Allan; Ryland, Robert; Sobota, David
2017-05-01
Current airborne radar systems segment the available time-on-target during each beam dwell into multiple Coherent Processing Intervals (CPIs) in order to eliminate range eclipsing, solve for unambiguous range, and increase the detection performance against larger Radar Cross Section (RCS) targets. As a consequence, these radars do not realize the full Signal-to-Noise Ratio (SNR) increase and detection performance improvement that is possible. Continuous High Pulse Repetition Frequency (HPRF) waveforms and processing enables the coherent integration of all available radar data over the full time-on-target. This can greatly increase the SNR for air targets at long range and/or with weak radar returns and significantly improve the detection performance against such targets. TSC worked with its partner KeyW to implement a Continuous HPRF waveform in their Sahara radar testbed and obtained measured radar data on both a ground vehicle target and an airborne target of opportunity. This experimental data was processed by TSC to validate the expected benefits of Continuous HPRF waveforms.
Characterizing Geological Facies using Seismic Waveform Classification in Sarawak Basin
Zahraa, Afiqah; Zailani, Ahmad; Prasad Ghosh, Deva
2017-10-01
Numerous effort have been made to build relationship between geology and geophysics using different techniques throughout the years. The integration of these two most important data in oil and gas industry can be used to reduce uncertainty in exploration and production especially for reservoir productivity enhancement and stratigraphic identification. This paper is focusing on seismic waveform classification to different classes using neural network and to link them according to the geological facies which are established using the knowledge on lithology and log motif of well data. Seismic inversion is used as the input for the neural network to act as the direct lithology indicator reducing dependency on well calibration. The interpretation of seismic facies classification map provides a better understanding towards the lithology distribution, depositional environment and help to identify significant reservoir rock
Selamtzis, Andreas; Ternström, Sten
2017-07-01
Although it has been shown in previous research (Orlikoff, 1991; Henrich et al, 2005; Kuang et al, 2014; Awan, 2015) that there exists a relationship between the electroglottogram (EGG) waveform and the acoustic signal, this relationship is still not fully understood. To investigate this relationship, the EGG and acoustic signals were measured for four male amateur choir singers who each produced eight consecutive tones of increasing and decreasing vocal intensity. The EGG signals were processed cycle-synchronously to obtain the discrete Fourier transform, and the data were used as an input to a clustering algorithm. The acoustic signal was analyzed in terms of sound pressure level (dB SPL) and fundamental frequency (fo) of vibration, and the results of both EGG and acoustic analysis were depicted on a two-dimensional plane with fo on the x-axis and SPL on the y-axis. All the subjects were seen to have a weak, near-sinusoidal EGG waveform in their lowest SPL range, whereas increase in SPL coincided with progressive enrichment in harmonic content of the EGG waveforms. The results of the clustering were additionally used to classify waveforms across subjects to enable inter-subject comparisons and assessment of individual strategies of exploring the fo-SPL dimensions. In these male subjects, the EGG waveform shape appeared to vary with SPL and to remain essentially constant with fo over one octave. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
Ahmed, Sajid
2016-11-24
Various examples of methods and systems are provided for direct closed-form finite alphabet constant-envelope waveforms for planar array beampatterns. In one example, a method includes defining a waveform covariance matrix based at least in part upon a two-dimensional fast Fourier transform (2D-FFT) analysis of a frequency domain matrix Hf associated with a planar array of antennas. Symbols can be encoded based upon the waveform covariance matrix and the encoded symbols can be transmitted via the planar array of antennas. In another embodiment, a system comprises an N x M planar array of antennas and transmission circuitry configured to transmit symbols via a two-dimensional waveform beampattern defined based at least in part upon a 2D-FFT analysis of a frequency domain matrix Hf associated with the planar array of antennas.
Cao, Yingqiu; Rakhilin, Nikolai; Gordon, Philip H.; Shen, Xiling; Kan, Edwin C.
2015-01-01
Background Computationally efficient spike recognition methods are required for real-time analysis of extracellular neural recordings. The enteric nervous system (ENS) is important to human health but less well-understood with few appropriate spike recognition algorithms due to large waveform variability. New Method Here we present a method based on dynamic time warping (DTW) with high tolerance to variability in time and magnitude. Adaptive temporal gridding for fastDTW in similarity calculation significantly reduces the computational cost. The automated threshold selection allows for real-time classification for extracellular recordings. Results Our method is first evaluated on synthesized data at different noise levels, improving both classification accuracy and computational complexity over the conventional cross-correlation based template-matching method (CCTM) and PCA + k-means clustering without time warping. Our method is then applied to analyze the mouse enteric neural recording with mechanical and chemical stimuli. Successful classification of biphasic and monophasic spikes is achieved even when the spike variability is larger than millisecond in width and millivolt in magnitude. Comparison with Existing Method(s) In comparison with conventional template matching and clustering methods, the fastDTW method is computationally efficient with high tolerance to waveform variability. Conclusions We have developed an adaptive fastDTW algorithm for real-time spike classification of ENS recording with large waveform variability against colony motility, ambient changes and cellular heterogeneity. PMID:26719239
Classification Algorithms for Big Data Analysis, a Map Reduce Approach
Ayma, V. A.; Ferreira, R. S.; Happ, P.; Oliveira, D.; Feitosa, R.; Costa, G.; Plaza, A.; Gamba, P.
2015-03-01
Since many years ago, the scientific community is concerned about how to increase the accuracy of different classification methods, and major achievements have been made so far. Besides this issue, the increasing amount of data that is being generated every day by remote sensors raises more challenges to be overcome. In this work, a tool within the scope of InterIMAGE Cloud Platform (ICP), which is an open-source, distributed framework for automatic image interpretation, is presented. The tool, named ICP: Data Mining Package, is able to perform supervised classification procedures on huge amounts of data, usually referred as big data, on a distributed infrastructure using Hadoop MapReduce. The tool has four classification algorithms implemented, taken from WEKA's machine learning library, namely: Decision Trees, Naïve Bayes, Random Forest and Support Vector Machines (SVM). The results of an experimental analysis using a SVM classifier on data sets of different sizes for different cluster configurations demonstrates the potential of the tool, as well as aspects that affect its performance.
CLASSIFICATION ALGORITHMS FOR BIG DATA ANALYSIS, A MAP REDUCE APPROACH
Directory of Open Access Journals (Sweden)
V. A. Ayma
2015-03-01
Full Text Available Since many years ago, the scientific community is concerned about how to increase the accuracy of different classification methods, and major achievements have been made so far. Besides this issue, the increasing amount of data that is being generated every day by remote sensors raises more challenges to be overcome. In this work, a tool within the scope of InterIMAGE Cloud Platform (ICP, which is an open-source, distributed framework for automatic image interpretation, is presented. The tool, named ICP: Data Mining Package, is able to perform supervised classification procedures on huge amounts of data, usually referred as big data, on a distributed infrastructure using Hadoop MapReduce. The tool has four classification algorithms implemented, taken from WEKA’s machine learning library, namely: Decision Trees, Naïve Bayes, Random Forest and Support Vector Machines (SVM. The results of an experimental analysis using a SVM classifier on data sets of different sizes for different cluster configurations demonstrates the potential of the tool, as well as aspects that affect its performance.
Novel Reduced Parts Online Uninterruptible Power Supply
Directory of Open Access Journals (Sweden)
Bahram Ashrafi
2012-01-01
Full Text Available This paper presents design consideration and performance analysis of novel reduced parts online three-phase uninterruptible power supply (UPS system. The proposed UPS system is based on reduced switch count dual bridge matrix converter. It employs only six power switches and results in reducing the cost of the system compared to conventional online UPS topologies, while achieving excellent performance. The performance of the proposed system is evaluated through simulation in terms of input/output waveforms quality and shows the viability of topology.
Communication waveform properties of an exact folded-band chaotic oscillator
Blakely, Jonathan N.; Hahs, Daniel W.; Corron, Ned J.
2013-11-01
We interpret the waveform of an exact folded-band oscillator as an on-off keyed communication waveform. Unlike most nonlinear systems, this oscillator has a general analytic solution that allows for unusually exact analysis. Using this solution, we identify the key differences between a deterministic chaotic oscillation and an ideal on-off keying waveform to be (1) an inherent form of intersymbol interference and (2) a grammar restriction giving rise to a built-in variable length code. We define a simple coherent receiver based on a matched filter, and consider transmission in the presence of additive white Gaussian noise. Analytic expressions for upper and lower bounds on the probability of errors in receiving code letters are derived and shown to be consistent with numerical simulations.
Mergers of Black-Hole Binaries with Aligned Spins: Waveform Characteristics
Kelly, Bernard J.; Baker, John G.; vanMeter, James R.; Boggs, William D.; McWilliams, Sean T.; Centrella, Joan
2011-01-01
"We apply our gravitational-waveform analysis techniques, first presented in the context of nonspinning black holes of varying mass ratio [1], to the complementary case of equal-mass spinning black-hole binary systems. We find that, as with the nonspinning mergers, the dominant waveform modes phases evolve together in lock-step through inspiral and merger, supporting the previous model of the binary system as an adiabatically rigid rotator driving gravitational-wave emission - an implicit rotating source (IRS). We further apply the late-merger model for the rotational frequency introduced in [1], along with a new mode amplitude model appropriate for the dominant (2, plus or minus 2) modes. We demonstrate that this seven-parameter model performs well in matches with the original numerical waveform for system masses above - 150 solar mass, both when the parameters are freely fit, and when they are almost completely constrained by physical considerations."
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Willis, J L; Willke, B; Wimmer, M; Winkler, W; Wipf, C C; Wiseman, A G; Wittel, H; Woan, G; Worden, J; Yablon, J; Yakushin, I; Yamamoto, H; Yancey, C C; Yang, H; Yang, Z; Yoshida, S; Yvert, M; Zadrożny, A; Zanolin, M; Zendri, J -P; Zhang, Fan; Zhang, L; Zhao, C; Zhu, X J; Zucker, M E; Zuraw, S; Zweizig, J; Boyle, M; Brügmann, B; Buchman, L T; Campanelli, M; Chu, T; Etienne, Z B; Hannam, M; Healy, J; Hinder, I; Kidder, L E; Laguna, P; Liu, Y T; London, L; Lousto, C O; Lovelace, G; MacDonald, I; Marronetti, P; Mösta, P; Müller, D; Mundim, B C; Nakano, H; Paschalidis, V; Pekowsky, L; Pollney, D; Pfeiffer, H P; Ponce, M; Pürrer, M; Reifenberger, G; Reisswig, C; Santamaría, L; Scheel, M A; Shapiro, S L; Shoemaker, D; Sopuerta, C F; Sperhake, U; Szilágyi, B; Taylor, N W; Tichy, W; Tsatsin, P; Zlochower, Y
2014-01-01
The Numerical INJection Analysis (NINJA) project is a collaborative effort between members of the numerical relativity and gravitational-wave astrophysics communities. The purpose of NINJA is to study the ability to detect gravitational waves emitted from merging binary black holes and recover their parameters with next-generation gravitational-wave observatories. We report here on the results of the second NINJA project, NINJA-2, which employs 60 complete binary black hole hybrid waveforms consisting of a numerical portion modelling the late inspiral, merger, and ringdown stitched to a post-Newtonian portion modelling the early inspiral. In a "blind injection challenge" similar to that conducted in recent LIGO and Virgo science runs, we added 7 hybrid waveforms to two months of data recolored to predictions of Advanced LIGO and Advanced Virgo sensitivity curves during their first observing runs. The resulting data was analyzed by gravitational-wave detection algorithms and 6 of the waveforms were recovered w...
Directory of Open Access Journals (Sweden)
Deniss Stepins
2015-01-01
Full Text Available Electromagnetic interference (EMI is one of the major problems of switching power converters. This paper is devoted to switching frequency modulation used for conducted EMI suppression in switching power converters. Comprehensive theoretical analysis of switching power converter conducted EMI spectrum and EMI attenuation due the use of traditional ramp and multislope ramp modulation waveforms is presented. Expressions to calculate EMI spectrum and attenuation are derived. Optimization procedure of the multislope ramp modulation waveform is proposed to get maximum benefits from switching frequency modulation for EMI reduction. Experimental verification is also performed to prove that the optimized multislope ramp modulation waveform is very useful solution for effective EMI reduction in switching power converters.
Back-EMF waveform optimization of flux-reversal permanent magnet machines
Zhu, Xiaofeng; Hua, Wei
2017-05-01
Due to the special doubly-salient structure, flux-reversal permanent magnet (FRPM) machines typically suffer from relatively large torque and speed ripples, as well as acoustic noise and vibration, especially at low speeds. As one of the main sources of torque ripples, harmonics in phase back electro-motive-force (EMF) should be suppressed as much as possible in order to produce a smooth torque. In this paper, an improved configuration of FRPM machine is proposed by introducing a small space-gap between the two adjacent magnets belonging to the same stator tooth to improve the symmetry of phase back-EMF waveform. The influence of the small space-gap on phase back-EMF waveform is evaluated by employing 2D finite element analysis (FEA), and consequently, an optimal value of space-gap for a more sinusoidal back-EMF waveform is obtained.
Improvement of Input Current Waveform for Soft-Switching Boost DCM Converter with Unity Power Factor
Taniguchi, Katsunori; Morizane, Toshimitsu; Kimura, Noriyuki
In this paper, a soft-switching discontinuous mode (DCM) power factor corrected (PFC) converter is analyzed by applying the double Fourier series expansion. It is found that the fundamental component and higher-order harmonics included in the input current waveform are obtained by the Fourier series expansion of the mean value of the inductor current. From the theoretical analysis, a new method removing the distortion of the input current waveform is proposed. In spite of an open loop system, the proposed method makes a great improvement of the total harmonic distortion even if the ratio of output voltage to input voltage is very low.
Inventions on reducing keyboard size: A TRIZ based analysis
Mishra, Umakant
2013-01-01
A conventional computer keyboard consists of as many as 101 keys. The keyboard has several sections, such as text entry section, navigation section, and numeric keypad etc. and each having several keys on the keyboard. The size of the keyboard is a major inconvenience for portable computers, as they cannot be carried easily. Thus there are certain circumstances which compels to reduce the size of a keyboard. Reducing the size of a keyboard leads to several problems. A reduced size keyboard ma...
Alian, Aymen A; Galante, Nicholas J; Stachenfeld, Nina S; Silverman, David G; Shelley, Kirk H
2014-07-01
Lower body negative pressure (LBNP) creates a reversible hypovolemia by sequestrating blood volume in the lower extremities. This study sought to examine the impact of central hypovolemia on peripheral venous pressure (PVP) waveforms in spontaneously breathing subjects. With IRB approval, 11 healthy subjects underwent progressive LBNP (baseline, -30, -75, and -90 mmHg or until the subject became symptomatic). Each was monitored for heart rate (HR), finger arterial blood pressure (BP), a chest respiratory band and PVP waveforms which are generated from a transduced upper extremity intravenous site. The first subject was excluded from PVP analysis because of technical errors in collecting the venous pressure waveform. PVP waveforms were analyzed to determine venous pulse pressure, mean venous pressure, pulse width, maximum and minimum slope (time domain analysis) together with cardiac and respiratory modulations (frequency domain analysis). No changes of significance were found in the arterial BP values at -30 mmHg LBNP, while there were significant reductions in the PVP waveforms time domain parameters (except for 50% width of the respiration induced modulations) together with modulation of the PVP waveform at the cardiac frequency but not at the respiratory frequency. As the LBNP progressed, arterial systolic BP, mean BP and pulse pressure, PVP parameters and PVP cardiac modulation decreased significantly, while diastolic BP and HR increased significantly. Changes in hemodynamic and PVP waveform parameters reached a maximum during the symptomatic phase. During the recovery phase, there was a significant reduction in HR together with a significant increase in HR variability, mean PVP and PVP cardiac modulation. Thus, in response to mild hypovolemia induced by LBNP, changes in cardiac modulation and other PVP waveform parameters identified hypovolemia before detectable hemodynamic changes.
2013-03-01
intermediate frequency LFM linear frequency modulation MAP maximum a posteriori MATLAB® matrix laboratory ML maximun likelihood OFDM orthogonal frequency...cognitive radar and communication systems include threat recognition and analysis, communication interception/demodulation, effective adaptive jammer...resolution, and ambiguity of range and Doppler (range rate) of the target [21]. Variables that may be manipulated in RADAR waveforms include
Full waveform inversion using envelope-based global correlation norm
Oh, Ju-Won; Alkhalifah, Tariq
2018-01-01
To increase the feasibility of full waveform inversion on real data, we suggest a new objective function, which is defined as the global correlation of the envelopes of modeled and observed data. The envelope-based global correlation norm has the advantage of the envelope inversion that generates artificial low-frequency information, which provides the possibility to recover long-wavelength structure in an early stage. In addition, the envelope-based global correlation norm maintains the advantage of the global correlation norm, which reduces the sensitivity of the misfit to amplitude errors so that the performance of inversion on real data can be enhanced when the exact source wavelet is not available and more complex physics are ignored.
Digital Waveform Technology and the Next Generation of Mass Spectrometers
Hoffman, Nathan M.; Gotlib, Zachary P.; Opačić, Bojana; Huntley, Adam P.; Moon, Ashley M.; Donahoe, Katherine E. G.; Brabeck, Gregory F.; Reilly, Peter T. A.
2017-10-01
Ion traps and guides are integral parts of current commercial mass spectrometers. They are currently operated with sinusoidal waveform technology that has been developed over many years. Recently, digital waveform technology has begun to emerge and promises to supplant its older cousin because it presents new capabilities that result from the ability to instantaneously switch the frequency and duty cycle of the waveforms. This manuscript examines these capabilities and reveals their uses and effects on instrumentation. [Figure not available: see fulltext.
LLMapReduce: Multi-Level Map-Reduce for High Performance Data Analysis
2016-05-23
frequency of 21 text files over 3 compute tasks. The map-reduce jobs were executed with the BLOCK and MIMO options, and the total processing time was...Dynamic distributed dimensional data model (D4M) database and computation system. In Acoustics, Speech and Signal Processing (ICASSP), 2012...interconnects [6]), High performance math libraries (e.g., BLAS [7, 8], LAPACK [9], ScaLAPACK [10]) designed to exploit special processing hardware, High
Advances in waveform-agile sensing for tracking
Sira, Sandeep Prasad
2009-01-01
Recent advances in sensor technology and information processing afford a new flexibility in the design of waveforms for agile sensing. Sensors are now developed with the ability to dynamically choose their transmit or receive waveforms in order to optimize an objective cost function. This has exposed a new paradigm of significant performance improvements in active sensing: dynamic waveform adaptation to environment conditions, target structures, or information features. The manuscript provides a review of recent advances in waveform-agile sensing for target tracking applications. A dynamic wav
Experimental Analysis of Reduced-Sized Coplanar Waveguide Transmission Lines
Ponchak, George E.
2002-01-01
An experimental investigation of the use of capacitive loading of coplanar waveguides to reduce their line length and, thus the size, of monolithic microwave integrated circuits is presented. The reduced sized coplanar waveguides are compared to unloaded transmission lines and to lumped element transmission line segments. The phase bandwidth, defined by 2 percent error in S(sub 21), and the return loss bandwidth, defined by a return loss greater than 15 dB, of coplanar waveguides reduced from 0 to 90 percent are compared, and the insertion loss as a function of the size reduction is presented.
The signatures of acoustic emission waveforms from fatigue crack advancing in thin metallic plates
Yeasin Bhuiyan, Md; Giurgiutiu, Victor
2018-01-01
The acoustic emission (AE) waveforms from a fatigue crack advancing in a thin metallic plate possess diverse and complex spectral signatures. In this article, we analyze these waveform signatures in coordination with the load level during cyclic fatigue. The advancing fatigue crack may generate numerous AE hits while it grows under fatigue loading. We found that these AE hits can be sorted into various groups based on their AE waveform signatures. Each waveform group has a particular time-domain signal pattern and a specific frequency spectrum. This indicates that each group represents a certain AE event related to the fatigue crack growth behavior. In situ AE-fatigue experiments were conducted to monitor the fatigue crack growth with simultaneous measurement of AE signals, fatigue loading, and optical crack growth measurement. An in situ microscope was installed in the load-frame of the mechanical testing system (MTS) to optically monitor the fatigue crack growth and relate the AE signals with the crack growth measurement. We found the AE signal groups at higher load levels (75%–85% of maximum load) were different from the AE signal groups that happened at lower load levels (below 60% of load level). These AE waveform groups are highly related to the fatigue crack-related AE events. These AE signals mostly contain the higher frequency peaks (100 kHz, 230 kHz, 450 kHz, 550 kHz). Some AE signal groups happened as a clustered form that relates a sequence of small AE events within the fatigue crack. They happened at relatively lower load level (50%–60% of the maximum load). These AE signal groups may be related to crack friction and micro-fracture during the friction process. These AE signals mostly contain the lower frequency peaks (60 kHz, 100 kHz, 200 kHz). The AE waveform based analysis may give us comprehensive information of the metal fatigue.
Effects of waveform model systematics on the interpretation of GW150914
Abbott, B. P.; Abbott, R.; Abbott, T. D.; Abernathy, M. R.; Acernese, F.; Ackley, K.; Adams, C.; Adams, T.; Addesso, P.; Adhikari, R. X.; Adya, V. B.; Affeldt, C.; Agathos, M.; Agatsuma, K.; Aggarwal, N.; Aguiar, O. D.; Aiello, L.; Ain, A.; Ajith, P.; Allen, B.; Allocca, A.; Altin, P. A.; Ananyeva, A.; Anderson, S. B.; Anderson, W. G.; Appert, S.; Arai, K.; Araya, M. C.; Areeda, J. S.; Arnaud, N.; Arun, K. G.; Ascenzi, S.; Ashton, G.; Ast, M.; Aston, S. M.; Astone, P.; Aufmuth, P.; Aulbert, C.; Avila-Alvarez, A.; Babak, S.; Bacon, P.; Bader, M. K. M.; Baker, P. T.; Baldaccini, F.; Ballardin, G.; Ballmer, S. W.; Barayoga, J. C.; E Barclay, S.; Barish, B. C.; Barker, D.; Barone, F.; Barr, B.; Barsotti, L.; Barsuglia, M.; Barta, D.; Bartlett, J.; Bartos, I.; Bassiri, R.; Basti, A.; Batch, J. C.; Baune, C.; Bavigadda, V.; Bazzan, M.; Beer, C.; Bejger, M.; Belahcene, I.; Belgin, M.; Bell, A. S.; Berger, B. K.; Bergmann, G.; Berry, C. P. L.; Bersanetti, D.; Bertolini, A.; Betzwieser, J.; Bhagwat, S.; Bhandare, R.; Bilenko, I. A.; Billingsley, G.; Billman, C. R.; Birch, J.; Birney, R.; Birnholtz, O.; Biscans, S.; Bisht, A.; Bitossi, M.; Biwer, C.; Bizouard, M. A.; Blackburn, J. K.; Blackman, J.; Blair, C. D.; Blair, D. G.; Blair, R. M.; Bloemen, S.; Bock, O.; Boer, M.; Bogaert, G.; Bohe, A.; Bondu, F.; Bonnand, R.; Boom, B. A.; Bork, R.; Boschi, V.; Bose, S.; Bouffanais, Y.; Bozzi, A.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Branchesi, M.; E Brau, J.; Briant, T.; Brillet, A.; Brinkmann, M.; Brisson, V.; Brockill, P.; E Broida, J.; Brooks, A. F.; Brown, D. A.; Brown, D. D.; Brown, N. M.; Brunett, S.; Buchanan, C. C.; Buikema, A.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Buskulic, D.; Buy, C.; Byer, R. L.; Cabero, M.; Cadonati, L.; Cagnoli, G.; Cahillane, C.; Calderón Bustillo, J.; Callister, T. A.; Calloni, E.; Camp, J. B.; Cannon, K. C.; Cao, H.; Cao, J.; Capano, C. D.; Capocasa, E.; Carbognani, F.; Caride, S.; Casanueva Diaz, J.; Casentini, C.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C. B.; Cerboni Baiardi, L.; Cerretani, G.; Cesarini, E.; Chamberlin, S. J.; Chan, M.; Chao, S.; Charlton, P.; Chassande-Mottin, E.; Cheeseboro, B. D.; Chen, H. Y.; Chen, Y.; Cheng, H.-P.; Chincarini, A.; Chiummo, A.; Chmiel, T.; Cho, H. S.; Cho, M.; Chow, J. H.; Christensen, N.; Chu, Q.; Chua, A. J. K.; Chua, S.; Chung, S.; Ciani, G.; Clara, F.; Clark, J. A.; Cleva, F.; Cocchieri, C.; Coccia, E.; Cohadon, P.-F.; Colla, A.; Collette, C. G.; Cominsky, L.; Constancio, M., Jr.; Conti, L.; Cooper, S. J.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Cortese, S.; Costa, C. A.; Coughlin, M. W.; Coughlin, S. B.; Coulon, J.-P.; Countryman, S. T.; Couvares, P.; Covas, P. B.; E Cowan, E.; Coward, D. M.; Cowart, M. J.; Coyne, D. C.; Coyne, R.; E Creighton, J. D.; Creighton, T. D.; Cripe, J.; Crowder, S. G.; Cullen, T. J.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dal Canton, T.; Danilishin, S. L.; D'Antonio, S.; Danzmann, K.; Dasgupta, A.; Da Silva Costa, C. F.; Dattilo, V.; Dave, I.; Davier, M.; Davies, G. S.; Davis, D.; Daw, E. J.; Day, B.; Day, R.; De, S.; DeBra, D.; Debreczeni, G.; Degallaix, J.; De Laurentis, M.; Deléglise, S.; Del Pozzo, W.; Denker, T.; Dent, T.; Dergachev, V.; De Rosa, R.; DeRosa, R. T.; DeSalvo, R.; Devenson, J.; Devine, R. C.; Dhurandhar, S.; Díaz, M. C.; Di Fiore, L.; Di Giovanni, M.; Di Girolamo, T.; Di Lieto, A.; Di Pace, S.; Di Palma, I.; Di Virgilio, A.; Doctor, Z.; Dolique, V.; Donovan, F.; Dooley, K. L.; Doravari, S.; Dorrington, I.; Douglas, R.; Dovale Álvarez, M.; Downes, T. P.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Du, Z.; Ducrot, M.; E Dwyer, S.; Edo, T. B.; Edwards, M. C.; Effler, A.; Eggenstein, H.-B.; Ehrens, P.; Eichholz, J.; Eikenberry, S. S.; Eisenstein, R. A.; Essick, R. C.; Etienne, Z.; Etzel, T.; Evans, M.; Evans, T. M.; Everett, R.; Factourovich, M.; Fafone, V.; Fair, H.; Fairhurst, S.; Fan, X.; Farinon, S.; Farr, B.; Farr, W. M.; Fauchon-Jones, E. J.; Favata, M.; Fays, M.; Fehrmann, H.; Fejer, M. M.; Fernández Galiana, A.; Ferrante, I.; Ferreira, E. C.; Ferrini, F.; Fidecaro, F.; Fiori, I.; Fiorucci, D.; Fisher, R. P.; Flaminio, R.; Fletcher, M.; Fong, H.; Forsyth, S. S.; Fournier, J.-D.; Frasca, S.; Frasconi, F.; Frei, Z.; Freise, A.; Frey, R.; Frey, V.; Fries, E. M.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Gabbard, H.; Gadre, B. U.; Gaebel, S. M.; Gair, J. R.; Gammaitoni, L.; Gaonkar, S. G.; Garufi, F.; Gaur, G.; Gayathri, V.; Gehrels, N.; Gemme, G.; Genin, E.; Gennai, A.; George, J.; Gergely, L.; Germain, V.; Ghonge, S.; Ghosh, Abhirup; Ghosh, Archisman; Ghosh, S.; Giaime, J. A.; Giardina, K. D.; Giazotto, A.; Gill, K.; Glaefke, A.; Goetz, E.; Goetz, R.; Gondan, L.; González, G.; Gonzalez Castro, J. M.; Gopakumar, A.; Gorodetsky, M. L.; E Gossan, S.; Gosselin, M.; Gouaty, R.; Grado, A.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greco, G.; Green, A. C.; Groot, P.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guo, X.; Gupta, A.; Gupta, M. K.; E Gushwa, K.; Gustafson, E. K.; Gustafson, R.; Hacker, J. J.; Hall, B. R.; Hall, E. D.; Hammond, G.; Haney, M.; Hanke, M. M.; Hanks, J.; Hanna, C.; Hannam, M. D.; Hanson, J.; Hardwick, T.; Harms, J.; Harry, G. M.; Harry, I. W.; Hart, M. J.; Hartman, M. T.; Haster, C.-J.; Haughian, K.; Healy, J.; Heidmann, A.; Heintze, M. C.; Heitmann, H.; Hello, P.; Hemming, G.; Hendry, M.; Heng, I. S.; Hennig, J.; Henry, J.; Heptonstall, A. W.; Heurs, M.; Hild, S.; Hoak, D.; Hofman, D.; Holt, K.; E Holz, D.; Hopkins, P.; Hough, J.; Houston, E. A.; Howell, E. J.; Hu, Y. M.; Huerta, E. A.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Huynh-Dinh, T.; Indik, N.; Ingram, D. R.; Inta, R.; Isa, H. N.; Isac, J.-M.; Isi, M.; Isogai, T.; Iyer, B. R.; Izumi, K.; Jacqmin, T.; Jani, K.; Jaranowski, P.; Jawahar, S.; Jiménez-Forteza, F.; Johnson, W. W.; Jones, D. I.; Jones, R.; Jonker, R. J. G.; Ju, L.; Junker, J.; Kalaghatgi, C. V.; Kalogera, V.; Kandhasamy, S.; Kang, G.; Kanner, J. B.; Karki, S.; Karvinen, K. S.; Kasprzack, M.; Katsavounidis, E.; Katzman, W.; Kaufer, S.; Kaur, T.; Kawabe, K.; Kéfélian, F.; Keitel, D.; Kelley, D. B.; Kennedy, R.; Key, J. S.; Khalili, F. Y.; Khan, I.; Khan, S.; Khan, Z.; Khazanov, E. A.; Kijbunchoo, N.; Kim, Chunglee; Kim, J. C.; Kim, Whansun; Kim, W.; Kim, Y.-M.; Kimbrell, S. J.; King, E. J.; King, P. J.; Kirchhoff, R.; Kissel, J. S.; Klein, B.; Kleybolte, L.; Klimenko, S.; Koch, P.; Koehlenbeck, S. M.; Koley, S.; Kondrashov, V.; Kontos, A.; Korobko, M.; Korth, W. Z.; Kowalska, I.; Kozak, D. B.; Krämer, C.; Kringel, V.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, P.; Kumar, R.; Kuo, L.; Kutynia, A.; Lackey, B. D.; Landry, M.; Lang, R. N.; Lange, J.; Lantz, B.; Lanza, R. K.; Lartaux-Vollard, A.; Lasky, P. D.; Laxen, M.; Lazzarini, A.; Lazzaro, C.; Leaci, P.; Leavey, S.; Lebigot, E. O.; Lee, C. H.; Lee, H. K.; Lee, H. M.; Lee, K.; Lehmann, J.; Lenon, A.; Leonardi, M.; Leong, J. R.; Leroy, N.; Letendre, N.; Levin, Y.; Li, T. G. F.; Libson, A.; Littenberg, T. B.; Liu, J.; Lockerbie, N. A.; Lombardi, A. L.; London, L. T.; E Lord, J.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lough, J. D.; Lovelace, G.; Lück, H.; Lundgren, A. P.; Lynch, R.; Ma, Y.; Macfoy, S.; Machenschalk, B.; MacInnis, M.; Macleod, D. M.; Magaña-Sandoval, F.; Majorana, E.; Maksimovic, I.; Malvezzi, V.; Man, N.; Mandic, V.; Mangano, V.; Mansell, G. L.; Manske, M.; Mantovani, M.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martelli, F.; Martellini, L.; Martin, I. W.; Martynov, D. V.; Mason, K.; Masserot, A.; Massinger, T. J.; Masso-Reid, M.; Mastrogiovanni, S.; Matichard, F.; Matone, L.; Mavalvala, N.; Mazumder, N.; McCarthy, R.; E McClelland, D.; McCormick, S.; McGrath, C.; McGuire, S. C.; McIntyre, G.; McIver, J.; McManus, D. J.; McRae, T.; McWilliams, S. T.; Meacher, D.; Meadors, G. D.; Meidam, J.; Melatos, A.; Mendell, G.; Mendoza-Gandara, D.; Mercer, R. A.; Merilh, E. L.; Merzougui, M.; Meshkov, S.; Messenger, C.; Messick, C.; Metzdorff, R.; Meyers, P. M.; Mezzani, F.; Miao, H.; Michel, C.; Middleton, H.; E Mikhailov, E.; Milano, L.; Miller, A. L.; Miller, A.; Miller, B. B.; Miller, J.; Millhouse, M.; Minenkov, Y.; Ming, J.; Mirshekari, S.; Mishra, C.; Mitra, S.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Moggi, A.; Mohan, M.; Mohapatra, S. R. P.; Montani, M.; Moore, B. C.; Moore, C. J.; Moraru, D.; Moreno, G.; Morriss, S. R.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Muir, A. W.; Mukherjee, Arunava; Mukherjee, D.; Mukherjee, S.; Mukund, N.; Mullavey, A.; Munch, J.; Muniz, E. A. M.; Murray, P. G.; Mytidis, A.; Napier, K.; Nardecchia, I.; Naticchioni, L.; Nelemans, G.; Nelson, T. J. N.; Neri, M.; Nery, M.; Neunzert, A.; Newport, J. M.; Newton, G.; Nguyen, T. T.; Nielsen, A. B.; Nissanke, S.; Nitz, A.; Noack, A.; Nocera, F.; Nolting, D.; Normandin, M. E. N.; Nuttall, L. K.; Oberling, J.; Ochsner, E.; Oelker, E.; Ogin, G. H.; Oh, J. J.; Oh, S. H.; Ohme, F.; Oliver, M.; Oppermann, P.; Oram, Richard J.; O'Reilly, B.; O'Shaughnessy, R.; Ottaway, D. J.; Overmier, H.; Owen, B. J.; E Pace, A.; Page, J.; Pai, A.; Pai, S. A.; Palamos, J. R.; Palashov, O.; Palomba, C.; Pal-Singh, A.; Pan, H.; Pankow, C.; Pannarale, F.; Pant, B. C.; Paoletti, F.; Paoli, A.; Papa, M. A.; Paris, H. R.; Parker, W.; Pascucci, D.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patricelli, B.; Pearlstone, B. L.; Pedraza, M.; Pedurand, R.; Pekowsky, L.; Pele, A.; Penn, S.; Perez, C. J.; Perreca, A.; Perri, L. M.; Pfeiffer, H. P.; Phelps, M.; Piccinni, O. J.; Pichot, M.; Piergiovanni, F.; Pierro, V.; Pillant, G.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Poe, M.; Poggiani, R.; Popolizio, P.; Post, A.; Powell, J.; Prasad, J.; Pratt, J. W. W.; Predoi, V.; Prestegard, T.; Prijatelj, M.; Principe, M.; Privitera, S.; Prodi, G. A.; Prokhorov, L. G.; Puncken, O.; Punturo, M.; Puppo, P.; Pürrer, M.; Qi, H.; Qin, J.; Qiu, S.; Quetschke, V.; Quintero, E. A.; Quitzow-James, R.; Raab, F. J.; Rabeling, D. S.; Radkins, H.; Raffai, P.; Raja, S.; Rajan, C.; Rakhmanov, M.; Rapagnani, P.; Raymond, V.; Razzano, M.; Re, V.; Read, J.; Regimbau, T.; Rei, L.; Reid, S.; Reitze, D. H.; Rew, H.; Reyes, S. D.; Rhoades, E.; Ricci, F.; Riles, K.; Rizzo, M.; Robertson, N. A.; Robie, R.; Robinet, F.; Rocchi, A.; Rolland, L.; Rollins, J. G.; Roma, V. J.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sachdev, S.; Sadecki, T.; Sadeghian, L.; Sakellariadou, M.; Salconi, L.; Saleem, M.; Salemi, F.; Samajdar, A.; Sammut, L.; Sampson, L. M.; Sanchez, E. J.; Sandberg, V.; Sanders, J. R.; Sassolas, B.; Sathyaprakash, B. S.; Saulson, P. R.; Sauter, O.; Savage, R. L.; Sawadsky, A.; Schale, P.; Scheuer, J.; Schmidt, E.; Schmidt, J.; Schmidt, P.; Schnabel, R.; Schofield, R. M. S.; Schönbeck, A.; Schreiber, E.; Schuette, D.; Schutz, B. F.; Schwalbe, S. G.; Scott, J.; Scott, S. M.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sequino, V.; Sergeev, A.; Setyawati, Y.; Shaddock, D. A.; Shaffer, T. J.; Shahriar, M. S.; Shapiro, B.; Shawhan, P.; Sheperd, A.; Shoemaker, D. H.; Shoemaker, D. M.; Siellez, K.; Siemens, X.; Sieniawska, M.; Sigg, D.; Silva, A. D.; Singer, A.; Singer, L. P.; Singh, A.; Singh, R.; Singhal, A.; Sintes, A. M.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; E Smith, R. J.; Son, E. J.; Sorazu, B.; Sorrentino, F.; Souradeep, T.; Spencer, A. P.; Srivastava, A. K.; Staley, A.; Steinke, M.; Steinlechner, J.; Steinlechner, S.; Steinmeyer, D.; Stephens, B. C.; Stevenson, S. P.; Stone, R.; Strain, K. A.; Straniero, N.; Stratta, G.; E Strigin, S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sun, L.; Sunil, S.; Sutton, P. J.; Swinkels, B. L.; Szczepańczyk, M. J.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tápai, M.; Taracchini, A.; Taylor, R.; Theeg, T.; Thomas, E. G.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Tippens, T.; Tiwari, S.; Tiwari, V.; Tokmakov, K. V.; Toland, K.; Tomlinson, C.; Tonelli, M.; Tornasi, Z.; Torrie, C. I.; Töyrä, D.; Travasso, F.; Traylor, G.; Trifirò, D.; Trinastic, J.; Tringali, M. C.; Trozzo, L.; Tse, M.; Tso, R.; Turconi, M.; Tuyenbayev, D.; Ugolini, D.; Unnikrishnan, C. S.; Urban, A. L.; Usman, S. A.; Vahlbruch, H.; Vajente, G.; Valdes, G.; van Bakel, N.; van Beuzekom, M.; van den Brand, J. F. J.; Van Den Broeck, C.; Vander-Hyde, D. C.; van der Schaaf, L.; van Heijningen, J. V.; van Veggel, A. A.; Vardaro, M.; Varma, V.; Vass, S.; Vasúth, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Venkateswara, K.; Venugopalan, G.; Verkindt, D.; Vetrano, F.; Viceré, A.; Viets, A. D.; Vinciguerra, S.; Vine, D. J.; Vinet, J.-Y.; Vitale, S.; Vo, T.; Vocca, H.; Vorvick, C.; Voss, D. V.; Vousden, W. D.; Vyatchanin, S. P.; Wade, A. R.; E Wade, L.; Wade, M.; Walker, M.; Wallace, L.; Walsh, S.; Wang, G.; Wang, H.; Wang, M.; Wang, Y.; Ward, R. L.; Warner, J.; Was, M.; Watchi, J.; Weaver, B.; Wei, L.-W.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Weßels, P.; Westphal, T.; Wette, K.; Whelan, J. T.; Whiting, B. F.; Whittle, C.; Williams, D.; Williams, R. D.; Williamson, A. R.; Willis, J. L.; Willke, B.; Wimmer, M. H.; Winkler, W.; Wipf, C. C.; Wittel, H.; Woan, G.; Woehler, J.; Worden, J.; Wright, J. L.; Wu, D. S.; Wu, G.; Yam, W.; Yamamoto, H.; Yancey, C. C.; Yap, M. J.; Yu, Hang; Yu, Haocun; Yvert, M.; Zadrożny, A.; Zangrando, L.; Zanolin, M.; Zendri, J.-P.; Zevin, M.; Zhang, L.; Zhang, M.; Zhang, T.; Zhang, Y.; Zhao, C.; Zhou, M.; Zhou, Z.; Zhu, S. J.; Zhu, X. J.; E Zucker, M.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Boyle, M.; Chu, T.; Hemberger, D.; Hinder, I.; E Kidder, L.; Ossokine, S.; Scheel, M.; Szilagyi, B.; Teukolsky, S.; Vano Vinuales, A.
2017-05-01
Parameter estimates of GW150914 were obtained using Bayesian inference, based on three semi-analytic waveform models for binary black hole coalescences. These waveform models differ from each other in their treatment of black hole spins, and all three models make some simplifying assumptions, notably to neglect sub-dominant waveform harmonic modes and orbital eccentricity. Furthermore, while the models are calibrated to agree with waveforms obtained by full numerical solutions of Einstein’s equations, any such calibration is accurate only to some non-zero tolerance and is limited by the accuracy of the underlying phenomenology, availability, quality, and parameter-space coverage of numerical simulations. This paper complements the original analyses of GW150914 with an investigation of the effects of possible systematic errors in the waveform models on estimates of its source parameters. To test for systematic errors we repeat the original Bayesian analysis on mock signals from numerical simulations of a series of binary configurations with parameters similar to those found for GW150914. Overall, we find no evidence for a systematic bias relative to the statistical error of the original parameter recovery of GW150914 due to modeling approximations or modeling inaccuracies. However, parameter biases are found to occur for some configurations disfavored by the data of GW150914: for binaries inclined edge-on to the detector over a small range of choices of polarization angles, and also for eccentricities greater than ˜0.05. For signals with higher signal-to-noise ratio than GW150914, or in other regions of the binary parameter space (lower masses, larger mass ratios, or higher spins), we expect that systematic errors in current waveform models may impact gravitational-wave measurements, making more accurate models desirable for future observations.
Elastic reflection waveform inversion with variable density
Li, Yuanyuan
2017-08-17
Elastic full waveform inversion (FWI) provides a better description of the subsurface than those given by the acoustic assumption. However it suffers from a more serious cycle skipping problem compared with the latter. Reflection waveform inversion (RWI) provides a method to build a good background model, which can serve as an initial model for elastic FWI. Therefore, we introduce the concept of RWI for elastic media, and propose elastic RWI with variable density. We apply Born modeling to generate the synthetic reflection data by using optimized perturbations of P- and S-wave velocities and density. The inversion for the perturbations in P- and S-wave velocities and density is similar to elastic least-squares reverse time migration (LSRTM). An incorrect initial model will lead to some misfits at the far offsets of reflections; thus, can be utilized to update the background velocity. We optimize the perturbation and background models in a nested approach. Numerical tests on the Marmousi model demonstrate that our method is able to build reasonably good background models for elastic FWI with absence of low frequencies, and it can deal with the variable density, which is needed in real cases.
Directory of Open Access Journals (Sweden)
Daniel Tomas Naughton
2017-10-01
Full Text Available The widespread brittle failure of welded beam-to-column connections caused by the 1994 Northridge and 1995 Kobe earthquakes highlighted the need for retrofitting measures effective in reducing the strength demand imposed on connections under cyclic loading. Researchers presented the reduced beam section (RBS as a viable option to create a weak zone away from the connection, aiding the prevention of brittle failure at the connection weld. More recently, an alternative connection known as a reduced web section (RWS has been developed as a potential replacement, and initial studies show ideal performance in terms of rotational capacity and ductility. This study performs a series of non-linear static pushover analyses using a modal load case on three steel moment-resisting frames of 4-, 8-, and 16-storeys. The frames are studied with three different connection arrangements; fully fixed moment connections, RBSs and RWSs, in order to compare the differences in capacity curves, inter-storey drifts, and plastic hinge formation. The seismic-resistant connections have been modeled as non-linear hinges in ETABS, and their behavior has been defined by moment-rotation curves presented in previous recent research studies. The frames are displacement controlled to the maximum displacement anticipated in an earthquake with ground motions having a 2% probability of being exceeded in 50 years. The study concludes that RWSs perform satisfactorily when compared with frames with fully fixed moment connections in terms of providing consistent inter-storey drifts without drastic changes in drift between adjacent storeys in low- to mid-rise frames, without significantly compromising the overall strength capacity of the frames. The use of RWSs in taller frames causes an increase in inter-storey drifts in the lower storeys, as well as causing a large reduction in strength capacity (33%. Frames with RWSs behave comparably to frames with RBSs and are deemed a suitable
Sudoku Inspired Designs for Radar Waveforms and Antenna Arrays
Directory of Open Access Journals (Sweden)
Travis D. Bufler
2017-02-01
Full Text Available Sudoku puzzles, often seen in magazines and newspapers, are logic-based challenges where each entry within the puzzle is comprised of symbols adhering to row, column and box constraints. Previously, we had investigated their potential in frequency-hopped waveforms to achieve desirable radar ambiguity functions and compared them with random, as well as the more familiar Costas sequences. This paper further examines the properties of Sudoku codes in more detail through computational search and analysis. We examine the co-hit and cross-hit arrays, defined as the correlation between two sequences, to quickly and efficiently evaluate numerous Sudoku puzzles. Additionally, we investigate the use of Sudoku puzzles for antenna applications, including array interleaving, array thinning and random element spacing.
3-D waveform tomography sensitivity kernels for anisotropic media
Djebbi, Ramzi
2014-01-01
The complications in anisotropic multi-parameter inversion lie in the trade-off between the different anisotropy parameters. We compute the tomographic waveform sensitivity kernels for a VTI acoustic medium perturbation as a tool to investigate this ambiguity between the different parameters. We use dynamic ray tracing to efficiently handle the expensive computational cost for 3-D anisotropic models. Ray tracing provides also the ray direction information necessary for conditioning the sensitivity kernels to handle anisotropy. The NMO velocity and η parameter kernels showed a maximum sensitivity for diving waves which results in a relevant choice of those parameters in wave equation tomography. The δ parameter kernel showed zero sensitivity; therefore it can serve as a secondary parameter to fit the amplitude in the acoustic anisotropic inversion. Considering the limited penetration depth of diving waves, migration velocity analysis based kernels are introduced to fix the depth ambiguity with reflections and compute sensitivity maps in the deeper parts of the model.
Hu, Ding; Xie, Shuqun; Yu, Donglan; Zheng, Zhensheng; Wang, Kuijian
2010-04-01
The development of external counterpulsation (ECP) local area network system and extensible markup language (XML)-based remote ECP medical information system conformable to digital imaging and communications in medicine (DICOM) standard has been improving the digital interchangeablity and sharability of ECP data. However, the therapy process of ECP is a continuous and longtime supervision which builds a mass of waveform data. In order to reduce the storage space and improve the transmission efficiency, the waveform data with the normative format of ECP data files have to be compressed. In this article, we introduced the compression arithmetic of template matching and improved quick fitting of linear approximation distance thresholding (LADT) in combimation with the characters of enhanced external counterpulsation (EECP) waveform signal. The DICOM standard is used as the storage and transmission standard to make our system compatible with hospital information system. According to the rules of transfer syntaxes, we defined private transfer syntax for one-dimensional compressed waveform data and stored EECP data into a DICOM file. Testing result indicates that the compressed and normative data can be correctly transmitted and displayed between EECP workstations in our EECP laboratory.
Blackman, Jonathan; Field, Scott E; Galley, Chad R; Szilágyi, Béla; Scheel, Mark A; Tiglio, Manuel; Hemberger, Daniel A
2015-09-18
Simulating a binary black hole coalescence by solving Einstein's equations is computationally expensive, requiring days to months of supercomputing time. Using reduced order modeling techniques, we construct an accurate surrogate model, which is evaluated in a millisecond to a second, for numerical relativity (NR) waveforms from nonspinning binary black hole coalescences with mass ratios in [1, 10] and durations corresponding to about 15 orbits before merger. We assess the model's uncertainty and show that our modeling strategy predicts NR waveforms not used for the surrogate's training with errors nearly as small as the numerical error of the NR code. Our model includes all spherical-harmonic _{-2}Y_{ℓm} waveform modes resolved by the NR code up to ℓ=8. We compare our surrogate model to effective one body waveforms from 50M_{⊙} to 300M_{⊙} for advanced LIGO detectors and find that the surrogate is always more faithful (by at least an order of magnitude in most cases).
Traditional waveform based spike sorting yields biased rate code estimates.
Ventura, Valérie
2009-04-28
Much of neuroscience has to do with relating neural activity and behavior or environment. One common measure of this relationship is the firing rates of neurons as functions of behavioral or environmental parameters, often called tuning functions and receptive fields. Firing rates are estimated from the spike trains of neurons recorded by electrodes implanted in the brain. Individual neurons' spike trains are not typically readily available, because the signal collected at an electrode is often a mixture of activities from different neurons and noise. Extracting individual neurons' spike trains from voltage signals, which is known as spike sorting, is one of the most important data analysis problems in neuroscience, because it has to be undertaken prior to any analysis of neurophysiological data in which more than one neuron is believed to be recorded on a single electrode. All current spike-sorting methods consist of clustering the characteristic spike waveforms of neurons. The sequence of first spike sorting based on waveforms, then estimating tuning functions, has long been the accepted way to proceed. Here, we argue that the covariates that modulate tuning functions also contain information about spike identities, and that if tuning information is ignored for spike sorting, the resulting tuning function estimates are biased and inconsistent, unless spikes can be classified with perfect accuracy. This means, for example, that the commonly used peristimulus time histogram is a biased estimate of the firing rate of a neuron that is not perfectly isolated. We further argue that the correct conceptual way to view the problem out is to note that spike sorting provides information about rate estimation and vice versa, so that the two relationships should be considered simultaneously rather than sequentially. Indeed we show that when spike sorting and tuning-curve estimation are performed in parallel, unbiased estimates of tuning curves can be recovered even from
Method and apparatus for resonant frequency waveform modulation
Taubman, Matthew S [Richland, WA
2011-06-07
A resonant modulator device and process are described that provide enhanced resonant frequency waveforms to electrical devices including, e.g., laser devices. Faster, larger, and more complex modulation waveforms are obtained than can be obtained by use of conventional current controllers alone.
Multicenter study of principles-based waveforms for external defibrillation.
Bain, A C; Swerdlow, C D; Love, C J; Ellenbogen, K A; Deering, T F; Brewer, J E; Augostini, R S; Tchou, P J
2001-01-01
The efficacy of a shock waveform for external defibrillation depends on the waveform characteristics. Recently, design principles based on cardiac electrophysiology have been developed to determine optimal waveform characteristics. The objective of this clinical trial was to evaluate the efficacy of principles-based monophasic and biphasic waveforms for external defibrillation. A prospective, randomized, blinded, multicenter study of 118 patients undergoing electrophysiologic testing or receiving an implantable defibrillator was conducted. Ventricular fibrillation was induced, and defibrillation was attempted in each patient with a biphasic and a monophasic waveform. Patients were randomly placed into 2 groups: group 1 received shocks of escalating energy, and group 2 received only high-energy shocks. The biphasic waveform achieved a first-shock success rate of 100% in group 1 (95% confidence interval [CI] 95.1% to 100%) and group 2 (95% CI 94.6% to 100%), with average delivered energies of 201+/-17 J and 295+/-28 J, respectively. The monophasic waveform demonstrated a 96.7% (95% CI 89.1% to 100%) first-shock success rate and average delivered energy of 215+/-12 J for group 1 and a 98.2% (95% CI 91.7% to 100%) first-shock success rate and average delivered energy of 352+/-13 J for group 2. Using principles of electrophysiology, it is possible to design both biphasic and monophasic waveforms for external defibrillation that achieve a high first-shock efficacy.
Exploring tree species signature using waveform LiDAR data
Zhou, T.; Popescu, S. C.; Krause, K.
2015-12-01
Successful classification of tree species with waveform LiDAR data would be of considerable value to estimate the biomass stocks and changes in forests. Current approaches emphasize converting the full waveform data into discrete points to get larger amount of parameters and identify tree species using several discrete-points variables. However, ignores intensity values and waveform shapes which convey important structural characteristics. The overall goal of this study was to employ the intensity and waveform shape of individual tree as the waveform signature to detect tree species. The data was acquired by the National Ecological Observatory Network (NEON) within 250*250 m study area located in San Joaquin Experimental Range. Specific objectives were to: (1) segment individual trees using the smoothed canopy height model (CHM) derived from discrete LiDAR points; (2) link waveform LiDAR with above individual tree boundaries to derive sample signatures of three tree species and use these signatures to discriminate tree species in a large area; and (3) compare tree species detection results from discrete LiDAR data and waveform LiDAR data. An overall accuracy of the segmented individual tree of more than 80% was obtained. The preliminary results show that compared with the discrete LiDAR data, the waveform LiDAR signature has a higher potential for accurate tree species classification.
An Overview of Radar Waveform Optimization for Target Detection
Directory of Open Access Journals (Sweden)
Wang Lulu
2016-10-01
Full Text Available An optimal waveform design method that fully employs the knowledge of the target and the environment can further improve target detection performance, thus is of vital importance to research. In this paper, methods of radar waveform optimization for target detection are reviewed and summarized and provide the basis for the research.
Analysis of some methods for reduced rank Gaussian process regression
DEFF Research Database (Denmark)
Quinonero-Candela, J.; Rasmussen, Carl Edward
2005-01-01
proliferation of a number of cost-effective approximations to GPs, both for classification and for regression. In this paper we analyze one popular approximation to GPs for regression: the reduced rank approximation. While generally GPs are equivalent to infinite linear models, we show that Reduced Rank......While there is strong motivation for using Gaussian Processes (GPs) due to their excellent performance in regression and classification problems, their computational complexity makes them impractical when the size of the training set exceeds a few thousand cases. This has motivated the recent...... Gaussian Processes (RRGPs) are equivalent to finite sparse linear models. We also introduce the concept of degenerate GPs and show that they correspond to inappropriate priors. We show how to modify the RRGP to prevent it from being degenerate at test time. Training RRGPs consists both in learning...
An analysis of force-reduced toroidal magnets
Energy Technology Data Exchange (ETDEWEB)
Hill, J.L.; Amm, B.C.; Schwartz, J. [Univ. of Illinois, Urbana, IL (United States)
1994-07-01
Superconductors alleviate the problem of Joule losses in electromagnetic devices, but an upper limit on large-scale electromagnets remains the difficulty in supporting the Lorentz forces within such a magnet. The problem is magnified if the materials are brittle, such as a ceramic superconductor. Recently, the authors discussed a possible solution to this problem: electromagnets with a force-reduced winding. Producing such a phenomenon may greatly reduce the size and support needed. Force-free finite geometries are not possible due to the limits of the Virial theorem, but present-day magnet support masses are up to an order of magnitude greater than the Virial limit. Here the authors present results from finite element calculations indicating that this design offers substantial improvement over conventional approaches.
Synthetic tsunami waveform catalogs with kinematic constraints
Directory of Open Access Journals (Sweden)
M. A. Baptista
2017-07-01
Full Text Available In this study we present a comprehensive methodology to produce a synthetic tsunami waveform catalogue in the northeast Atlantic, east of the Azores islands. The method uses a synthetic earthquake catalogue compatible with plate kinematic constraints of the area. We use it to assess the tsunami hazard from the transcurrent boundary located between Iberia and the Azores, whose western part is known as the Gloria Fault. This study focuses only on earthquake-generated tsunamis. Moreover, we assume that the time and space distribution of the seismic events is known. To do this, we compute a synthetic earthquake catalogue including all fault parameters needed to characterize the seafloor deformation covering the time span of 20 000 years, which we consider long enough to ensure the representability of earthquake generation on this segment of the plate boundary. The computed time and space rupture distributions are made compatible with global kinematic plate models. We use the tsunami empirical Green's functions to efficiently compute the synthetic tsunami waveforms for the dataset of coastal locations, thus providing the basis for tsunami impact characterization. We present the results in the form of offshore wave heights for all coastal points in the dataset. Our results focus on the northeast Atlantic basin, showing that earthquake-induced tsunamis in the transcurrent segment of the Azores–Gibraltar plate boundary pose a minor threat to coastal areas north of Portugal and beyond the Strait of Gibraltar. However, in Morocco, the Azores, and the Madeira islands, we can expect wave heights between 0.6 and 0.8 m, leading to precautionary evacuation of coastal areas. The advantages of the method are its easy application to other regions and the low computation effort needed.
Designing waveforms for temporal encoding using a frequency sampling method
DEFF Research Database (Denmark)
Gran, Fredrik; Jensen, Jørgen Arendt
2007-01-01
In this paper a method for designing waveforms for temporal encoding in medical ultrasound imaging is described. The method is based on least squares optimization and is used to design nonlinear frequency modulated signals for synthetic transmit aperture imaging. By using the proposed design method......, the amplitude spectrum of the transmitted waveform can be optimized, such that most of the energy is transmitted where the transducer has large amplification. To test the design method, a waveform was designed for a BK8804 linear array transducer. The resulting nonlinear frequency modulated waveform...... waveform, on the other hand, was designed so that only frequencies where the transducer had a large amplification were excited. Hereby, unnecessary heating of the transducer could be avoided and the signal-tonoise ratio could be increased. The experimental ultrasound scanner RASMUS was used to evaluate...
Earthquake Fingerprints: Representing Earthquake Waveforms for Similarity-Based Detection
Bergen, K.; Beroza, G. C.
2016-12-01
New earthquake detection methods, such as Fingerprint and Similarity Thresholding (FAST), use fast approximate similarity search to identify similar waveforms in long-duration data without templates (Yoon et al. 2015). These methods have two key components: fingerprint extraction and an efficient search algorithm. Fingerprint extraction converts waveforms into fingerprints, compact signatures that represent short-duration waveforms for identification and search. Earthquakes are detected using an efficient indexing and search scheme, such as locality-sensitive hashing, that identifies similar waveforms in a fingerprint database. The quality of the search results, and thus the earthquake detection results, is strongly dependent on the fingerprinting scheme. Fingerprint extraction should map similar earthquake waveforms to similar waveform fingerprints to ensure a high detection rate, even under additive noise and small distortions. Additionally, fingerprints corresponding to noise intervals should have mutually dissimilar fingerprints to minimize false detections. In this work, we compare the performance of multiple fingerprint extraction approaches for the earthquake waveform similarity search problem. We apply existing audio fingerprinting (used in content-based audio identification systems) and time series indexing techniques and present modified versions that are specifically adapted for seismic data. We also explore data-driven fingerprinting approaches that can take advantage of labeled or unlabeled waveform data. For each fingerprinting approach we measure its ability to identify similar waveforms in a low signal-to-noise setting, and quantify the trade-off between true and false detection rates in the presence of persistent noise sources. We compare the performance using known event waveforms from eight independent stations in the Northern California Seismic Network.
Facial nerve action potentials: a study to assess waveform reliability.
Axon, P R; Ramsden, R T
2000-11-01
To assess the reliability of the orthodromic facial nerve action potential (FNAP), recorded from the intratemporal portion of the facial nerve on stimulation within the cerebellopontine angle. Prospective study. Tertiary referral center. Ten consecutive patients undergoing translabyrinthine resection of vestibular schwannoma. Diagnostic. Ten consecutive FNAPs were recorded on stimulation of the facial nerve within the cerebellopontine angle. The FNAP recording probe was placed directly on the nerve surface after the fallopian canal was opened at the second genu. Ten consecutive compound muscle action potentials (CMAPs) were recorded simultaneously from surface electrodes overlying the facial musculature, by use of a standardized electrode placement technique. The stimulating and recording equipment were removed (excluding CMAP surface electrodes) and reapplied, and FNAP and CMAP data were recorded for a second time (test/retest). Peak-to-peak amplitudes of all waveforms were calculated. The average FNAP peak-to-peak amplitude for all patients was larger than the CMAP peak-to-peak amplitude (2.60 mV and 1.07 mV, respectively). Random effects analysis of variance was performed to assess the individual components of variation. This showed that CMAP was less variable than FNAP for replicate error (10 consecutive FNAPs and CMAPs) and test/retest error. However, subject variance was less for FNAP, where subject variance was by far the largest contributor to overall variation. The reliability coefficient for FNAP was 0.995 and for the CMAP was 0.982, where absolute reliability is 1.0. These data confirm that the FNAP, recorded by the technique described here, is a reliable waveform when compared with the CMAP and is a valid method for assessing facial nerve function.
Use of paravascular admittance waveforms to monitor relative change in arterial blood pressure
Zielinski, Todd M.; Hettrick, Doug; Cho, Yong
2010-04-01
Non-invasive methods to monitor ambulatory blood pressure often have limitations that can affect measurement accuracy and patient adherence [1]. Minimally invasive measurement of a relative blood pressure surrogate with an implantable device may provide a useful chronic diagnostic and monitoring tool. We assessed a technique that uses electrocardiogram and paravascular admittance waveform morphology analysis to one, measure a time duration (vascular tone index, VTI in milliseconds) change from the electrocardiogram R-wave to admittance waveform peak and two, measure the admittance waveform minimum, maximum and magnitude as indicators of change in arterial compliance/distensibility or pulse pressure secondary to change in afterload. Methods: Five anesthetized domestic pigs (32 ± 4.2 kg) were used to study the effects of phenylephrine (1-5 ug/kg/min) on femoral artery pressure and admittance waveform morphology measured with a quadrapolar electrode array catheter placed next to the femoral artery to assess the relative change in arterial compliance due to change in peripheral vascular tone. Results: Statistical difference was observed (p blood pressure may be suitable for implantable devices to detect progression of cardiovascular disease such as hypertension.
Wang, Xuezhi; Huang, Xiaotao; Suvorova, Sofia; Moran, Bill
2018-01-01
Golay complementary waveforms can, in theory, yield radar returns of high range resolution with essentially zero sidelobes. In practice, when deployed conventionally, while high signal-to-noise ratios can be achieved for static target detection, significant range sidelobes are generated by target returns of nonzero Doppler causing unreliable detection. We consider signal processing techniques using Golay complementary waveforms to improve radar detection performance in scenarios involving multiple nonzero Doppler targets. A signal processing procedure based on an existing, so called, Binomial Design algorithm that alters the transmission order of Golay complementary waveforms and weights the returns is proposed in an attempt to achieve an enhanced illumination performance. The procedure applies one of three proposed waveform transmission ordering algorithms, followed by a pointwise nonlinear processor combining the outputs of the Binomial Design algorithm and one of the ordering algorithms. The computational complexity of the Binomial Design algorithm and the three ordering algorithms are compared, and a statistical analysis of the performance of the pointwise nonlinear processing is given. Estimation of the areas in the Delay–Doppler map occupied by significant range sidelobes for given targets are also discussed. Numerical simulations for the comparison of the performances of the Binomial Design algorithm and the three ordering algorithms are presented for both fixed and randomized target locations. The simulation results demonstrate that the proposed signal processing procedure has a better detection performance in terms of lower sidelobes and higher Doppler resolution in the presence of multiple nonzero Doppler targets compared to existing methods. PMID:29324708
Sensitivity based reduced approaches for structural reliability analysis
Indian Academy of Sciences (India)
captured by a safety-factor based approach due to the intricate nonlinear relationships between the system parameters and the natural frequencies. For these reasons a scientific and systematic approach is required to predict the probability of failure of a structure at the design stage. Probabilistic structural reliability analysis ...
Reduced cancer risk in vegetarians: an analysis of recent reports
Directory of Open Access Journals (Sweden)
Amy Joy Lanou
2010-12-01
Full Text Available Amy Joy Lanou1, Barbara Svenson21Department of Health and Wellness, 2Ramsey Library, University of North Carolina Asheville, Asheville, NC, USAAbstract: This report reviews current evidence regarding the relationship between vegetarian eating patterns and cancer risk. Although plant-based diets including vegetarian and vegan diets are generally considered to be cancer protective, very few studies have directly addressed this question. Most large prospective observational studies show that vegetarian diets are at least modestly cancer protective (10%–12% reduction in overall cancer risk although results for specific cancers are less clear. No long-term randomized clinical trials have been conducted to address this relationship. However, a broad body of evidence links specific plant foods such as fruits and vegetables, plant constituents such as fiber, antioxidants and other phytochemicals, and achieving and maintaining a healthy weight to reduced risk of cancer diagnosis and recurrence. Also, research links the consumption of meat, especially red and processed meats, to increased risk of several types of cancer. Vegetarian and vegan diets increase beneficial plant foods and plant constituents, eliminate the intake of red and processed meat, and aid in achieving and maintaining a healthy weight. The direct and indirect evidence taken together suggests that vegetarian diets are a useful strategy for reducing risk of cancer.Keywords: diet, vegan, prevention
Reduced cancer risk in vegetarians: an analysis of recent reports.
Lanou, Amy Joy; Svenson, Barbara
2010-12-20
This report reviews current evidence regarding the relationship between vegetarian eating patterns and cancer risk. Although plant-based diets including vegetarian and vegan diets are generally considered to be cancer protective, very few studies have directly addressed this question. Most large prospective observational studies show that vegetarian diets are at least modestly cancer protective (10%-12% reduction in overall cancer risk) although results for specific cancers are less clear. No long-term randomized clinical trials have been conducted to address this relationship. However, a broad body of evidence links specific plant foods such as fruits and vegetables, plant constituents such as fiber, antioxidants and other phytochemicals, and achieving and maintaining a healthy weight to reduced risk of cancer diagnosis and recurrence. Also, research links the consumption of meat, especially red and processed meats, to increased risk of several types of cancer. Vegetarian and vegan diets increase beneficial plant foods and plant constituents, eliminate the intake of red and processed meat, and aid in achieving and maintaining a healthy weight. The direct and indirect evidence taken together suggests that vegetarian diets are a useful strategy for reducing risk of cancer.
Accuracy of binary black hole waveform models for aligned-spin binaries
Kumar, Prayush; Chu, Tony; Fong, Heather; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela
2016-05-01
Coalescing binary black holes are among the primary science targets for second generation ground-based gravitational wave detectors. Reliable gravitational waveform models are central to detection of such systems and subsequent parameter estimation. This paper performs a comprehensive analysis of the accuracy of recent waveform models for binary black holes with aligned spins, utilizing a new set of 84 high-accuracy numerical relativity simulations. Our analysis covers comparable mass binaries (mass-ratio 1 ≤q ≤3 ), and samples independently both black hole spins up to a dimensionless spin magnitude of 0.9 for equal-mass binaries and 0.85 for unequal mass binaries. Furthermore, we focus on the high-mass regime (total mass ≳50 M⊙ ). The two most recent waveform models considered (PhenomD and SEOBNRv2) both perform very well for signal detection, losing less than 0.5% of the recoverable signal-to-noise ratio ρ , except that SEOBNRv2's efficiency drops slightly for both black hole spins aligned at large magnitude. For parameter estimation, modeling inaccuracies of the SEOBNRv2 model are found to be smaller than systematic uncertainties for moderately strong GW events up to roughly ρ ≲15 . PhenomD's modeling errors are found to be smaller than SEOBNRv2's, and are generally irrelevant for ρ ≲20 . Both models' accuracy deteriorates with increased mass ratio, and when at least one black hole spin is large and aligned. The SEOBNRv2 model shows a pronounced disagreement with the numerical relativity simulation in the merger phase, for unequal masses and simultaneously both black hole spins very large and aligned. Two older waveform models (PhenomC and SEOBNRv1) are found to be distinctly less accurate than the more recent PhenomD and SEOBNRv2 models. Finally, we quantify the bias expected from all four waveform models during parameter estimation for several recovered binary parameters: chirp mass, mass ratio, and effective spin.
Energy Technology Data Exchange (ETDEWEB)
HUANG, LIANJIE [Los Alamos National Laboratory; PRATT, R. GERHARD [Los Alamos National Laboratory; DURIC, NEB [Los Alamos National Laboratory; LITTRUP, PETER [Los Alamos National Laboratory
2007-01-25
Waveform tomography results are presented from 800 kHz ultrasound transmission scans of a breast phantom, and from an in vivo ultrasound breast scan: significant improvements are demonstrated in resolution over time-of-flight reconstructions. Quantitative reconstructions of both sound-speed and inelastic attenuation are recovered. The data were acquired in the Computed Ultrasound Risk Evaluation (CURE) system, comprising a 20 cm diameter solid-state ultrasound ring array with 256 active, non-beamforming transducers. Waveform tomography is capable of resolving variations in acoustic properties at sub-wavelength scales. This was verified through comparison of the breast phantom reconstructions with x-ray CT results: the final images resolve variations in sound speed with a spatial resolution close to 2 mm. Waveform tomography overcomes the resolution limit of time-of-flight methods caused by finite frequency (diffraction) effects. The method is a combination of time-of-flight tomography, and 2-D acoustic waveform inversion of the transmission arrivals in ultrasonic data. For selected frequency components of the waveforms, a finite-difference simulation of the visco-acoustic wave equation is used to compute synthetic data in the current model, and the data residuals are formed by subtraction. The residuals are used in an iterative, gradient-based scheme to update the sound-speed and attenuation model to produce a reduced misfit to the data. Computational efficiency is achieved through the use of time-reversal of the data residuals to construct the model updates. Lower frequencies are used first, to establish the long wavelength components of the image, and higher frequencies are introduced later to provide increased resolution.
Bouchoucha, Taha
2015-05-01
Multiple Input Multiple Output (MIMO) radar systems has attracted lately a lot of attention thanks to its advantage over the classical phased array radar systems. We site among these advantages the improvement of parametric identifiability, achievement of higher spatial resolution and design of complex beampatterns. In colocated multiple-input multiple-output radar systems, it is usually desirable to steer transmitted power in the region-of-interest in order to increase the Signal to Noise Ratio (SNR) and reduce any undesired signal and thus improve the detection process. This problem is also known as transmit beampattern design. To achieve this goal, conventional methods optimize the waveform covariance matrix, R, for the desired beampattern, which is then used to generate the actual transmitted waveforms. Both steps require constrained optimization. Most of the existing methods use iterative algorithms to solve these problems, therefore their computational complexity is very high which makes them hard to use in practice especially for real time radar applications. In this paper, we provide a closed-form solution to design the covariance matrix for a given beampattern in the three dimensional space using planar arrays, which is then used to derive a novel closed-form algorithm to directly design the finite-alphabet constant-envelope waveforms. The proposed algorithm exploits the two-dimensional discrete Fourier transform which is implemented using fast Fourier transform algorithm. Consequently, the computational complexity of the proposed beampattern solution is very low allowing it to be used for large arrays to change the beampattern in real time. We also show that the number of required snapshots in each waveform depends on the beampattern and that it is less than the total number of transmit antennas. In addition, we show that the proposed waveform design method can be used with non symmetric beampatterns. The performance of our proposed algorithm compares
Fractal analysis reveals reduced complexity of retinal vessels in CADASIL.
Directory of Open Access Journals (Sweden)
Michele Cavallari
Full Text Available The Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL affects mainly small cerebral arteries and leads to disability and dementia. The relationship between clinical expression of the disease and progression of the microvessel pathology is, however, uncertain as we lack tools for imaging brain vessels in vivo. Ophthalmoscopy is regarded as a window into the cerebral microcirculation. In this study we carried out an ophthalmoscopic examination in subjects with CADASIL. Specifically, we performed fractal analysis of digital retinal photographs. Data are expressed as mean fractal dimension (mean-D, a parameter that reflects complexity of the retinal vessel branching. Ten subjects with genetically confirmed diagnosis of CADASIL and 10 sex and age-matched control subjects were enrolled. Fractal analysis of retinal digital images was performed by means of a computer-based program, and the data expressed as mean-D. Brain MRI lesion volume in FLAIR and T1-weighted images was assessed using MIPAV software. Paired t-test was used to disclose differences in mean-D between CADASIL and control groups. Spearman rank analysis was performed to evaluate potential associations between mean-D values and both disease duration and disease severity, the latter expressed as brain MRI lesion volumes, in the subjects with CADASIL. The results showed that mean-D value of patients (1.42±0.05; mean±SD was lower than control (1.50±0.04; p = 0.002. Mean-D did not correlate with disease duration nor with MRI lesion volumes of the subjects with CADASIL. The findings suggest that fractal analysis is a sensitive tool to assess changes of retinal vessel branching, likely reflecting early brain microvessel alterations, in CADASIL patients.
Energy Technology Data Exchange (ETDEWEB)
Woo, Leta Yar-Li; Glass, Robert Scott; Fitzpatrick, Joseph Jay; Wang, Gangqiang; Henderson, Brett Tamatea; Lourdhusamy, Anthoniraj; Steppan, James John; Allmendinger, Klaus Karl
2018-01-02
A device for signal processing. The device includes a signal generator, a signal detector, and a processor. The signal generator generates an original waveform. The signal detector detects an affected waveform. The processor is coupled to the signal detector. The processor receives the affected waveform from the signal detector. The processor also compares at least one portion of the affected waveform with the original waveform. The processor also determines a difference between the affected waveform and the original waveform. The processor also determines a value corresponding to a unique portion of the determined difference between the original and affected waveforms. The processor also outputs the determined value.
An architecture for pre-warping general parametric frequency-modulated radar waveforms
Doerry, A. W.
2017-05-01
It is often advantageous to modify, or warp, radar waveforms, particularly with respect to group-delay and spectral dilation. These warping adjustments may facilitate real-time motion compensation of waveforms in radar systems, especially when those waveforms are generated by a digital parametric waveform generator. Relevant waveforms to this paper include Frequency Modulated (FM) waveforms, such as the Linear-FM (LFM) chirp, Non-Linear FM (NLFM) chirp, and other general FM waveforms. We present techniques for making fine adjustments to dynamically warp general FM waveforms.
Analysis of Fourier ptychographic microscopy with half reduced images
Zhou, Ao; Chen, Ni; Situ, Guohai
2018-01-01
Fourier ptychography microscopy (FPM) provides gigapixel imaging with both a high image resolution and a wide field-of-view (FOV). However, it is time consuming during the image capture process. In this paper, we perform an analysis on the FPM imaging process. With numerical and experimental comparison, we find that the reconstructed high resolution images with half number of the total captured images is less degenerated compare to that using all the captured images, especially in the case that the object is amplitude or phase-only.
Fractional Scaling Analysis for IRIS pressurizer reduced scale experiments
Energy Technology Data Exchange (ETDEWEB)
Bezerra da Silva, Mario Augusto, E-mail: mabs500@gmail.co [Departamento de Energia Nuclear - Centro de Tecnologia e Geociencias, Universidade Federal de Pernambuco, Av. Prof. Luiz Freire, 1000, 50740-540 Recife, PE (Brazil); Brayner de Oliveira Lira, Carlos Alberto, E-mail: cabol@ufpe.b [Departamento de Energia Nuclear - Centro de Tecnologia e Geociencias, Universidade Federal de Pernambuco, Av. Prof. Luiz Freire, 1000, 50740-540 Recife, PE (Brazil); Oliveira Barroso, Antonio Carlos de, E-mail: barroso@ipen.b [Instituto de Pesquisas Energeticas e Nucleares - Comissao Nacional de Energia Nuclear, Av. Prof. Lineu Prestes, 2242, 05508-900 Cidade Universitaria, Sao Paulo (Brazil)
2010-10-15
About twenty organizations joined in a consortium led by Westinghouse to develop an integral, modular and medium size pressurized water reactor (PWR), known as international reactor innovative and secure (IRIS), which is characterized by having most of its components inside the pressure vessel, eliminating or minimizing the probability of severe accidents. The pressurizer is responsible for pressure control in PWRs. A small continuous flow is maintained by the spray system in conventional pressurizers. This mini-flow allows a mixing between the reactor coolant and the pressurizer water, warranting acceptable limits for occasional differences in boron concentrations. There are neither surge lines nor spray in IRIS pressurizer, but surge and recirculation orifices that promote a circulation flow between primary system and pressurizer, avoiding power transients whether outsurges occur. The construction of models is a routine practice in engineering, being supported by similarity rules. A new method of scaling systems, Fractional Scaling Analysis, has been successfully used to analyze pressure variations, considering the most relevant agents of change. The aim of this analysis is to obtain the initial boron concentration ratio and the volumetric flows that ensure similar behavior for boron dispersion in a prototype and its model.
Generation of correlated finite alphabet waveforms using gaussian random variables
Jardak, Seifallah
2014-09-01
Correlated waveforms have a number of applications in different fields, such as radar and communication. It is very easy to generate correlated waveforms using infinite alphabets, but for some of the applications, it is very challenging to use them in practice. Moreover, to generate infinite alphabet constant envelope correlated waveforms, the available research uses iterative algorithms, which are computationally very expensive. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method map the Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability-density-function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. To generate equiprobable symbols, the area of each region is kept same. If the requirement is to have each symbol with its own unique probability, the proposed scheme allows us that as well. Although, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.
Source-independent elastic waveform inversion using a logarithmic wavefield
Choi, Yun Seok
2012-01-01
The logarithmic waveform inversion has been widely developed and applied to some synthetic and real data. In most logarithmic waveform inversion algorithms, the subsurface velocities are updated along with the source estimation. To avoid estimating the source wavelet in the logarithmic waveform inversion, we developed a source-independent logarithmic waveform inversion algorithm. In this inversion algorithm, we first normalize the wavefields with the reference wavefield to remove the source wavelet, and then take the logarithm of the normalized wavefields. Based on the properties of the logarithm, we define three types of misfit functions using the following methods: combination of amplitude and phase, amplitude-only, and phase-only. In the inversion, the gradient is computed using the back-propagation formula without directly calculating the Jacobian matrix. We apply our algorithm to noise-free and noise-added synthetic data generated for the modified version of elastic Marmousi2 model, and compare the results with those of the source-estimation logarithmic waveform inversion. For the noise-free data, the source-independent algorithms yield velocity models close to true velocity models. For random-noise data, the source-estimation logarithmic waveform inversion yields better results than the source-independent method, whereas for coherent-noise data, the results are reversed. Numerical results show that the source-independent and source-estimation logarithmic waveform inversion methods have their own merits for random- and coherent-noise data. © 2011.
SURFACE FITTING FILTERING OF LIDAR POINT CLOUD WITH WAVEFORM INFORMATION
Directory of Open Access Journals (Sweden)
S. Xing
2017-09-01
Full Text Available Full-waveform LiDAR is an active technology of photogrammetry and remote sensing. It provides more detailed information about objects along the path of a laser pulse than discrete-return topographic LiDAR. The point cloud and waveform information with high quality can be obtained by waveform decomposition, which could make contributions to accurate filtering. The surface fitting filtering method with waveform information is proposed to present such advantage. Firstly, discrete point cloud and waveform parameters are resolved by global convergent Levenberg Marquardt decomposition. Secondly, the ground seed points are selected, of which the abnormal ones are detected by waveform parameters and robust estimation. Thirdly, the terrain surface is fitted and the height difference threshold is determined in consideration of window size and mean square error. Finally, the points are classified gradually with the rising of window size. The filtering process is finished until window size is larger than threshold. The waveform data in urban, farmland and mountain areas from “WATER (Watershed Allied Telemetry Experimental Research” are selected for experiments. Results prove that compared with traditional method, the accuracy of point cloud filtering is further improved and the proposed method has highly practical value.
Truncated exponential versus damped sinusoidal waveform shocks for transthoracic defibrillation.
Behr, J C; Hartley, L L; York, D K; Brown, D D; Kerber, R E
1996-12-01
Currently available transthoracic defibrillators use either a damped sinusoidal or truncated exponential (TE) waveform. Truncated exponential waveforms deliver a long pulse if the transthoracic impedance is high; it has been suggested that such a long pulse may be less effective for defibrillation. Our objective was to compare the ability of damped sinusoidal (DS) waveform shocks versus TE waveform shocks to terminate ventricular fibrillation (VF) and achieve survival from witnessed cardiac arrest. We retrospectively reviewed field-recorded electrocardiograms from 86 patients with witnessed VF, treated by prehospital personnel equipped with DS or TE waveform defibrillators. Forty-four patients received 130 shocks from TE defibrillators; 42 patients received 108 shocks from DS defibrillators. There were no significant differences in time from arrest to first shock (8.0 vs 8.1 minutes), nor were there any differences in the size of the communities involved. The shocks resulted in the following rhythms: organized rhythm: TE: 15 of 130 (12%), DS: 24 of 108 (22%), p = 0.10 (NS); persistent VF: TE: 85 of 130 (65%), DS: 45 of 108 (42%), p <0.01; asystole: TE: 30 of 130 (23%), DS: 39 of 108 (36%), p = NS; and survival to hospital discharge: TE: 5 of 44 (11%), DS: 8 of 42 (19%), p = NS. We conclude that DS waveforms terminated VF more frequently than TE, but there was no significant difference in resumption of an organized rhythm or survival. A prospective comparison of these 2 waveforms is needed.
Surface Fitting Filtering of LIDAR Point Cloud with Waveform Information
Xing, S.; Li, P.; Xu, Q.; Wang, D.; Li, P.
2017-09-01
Full-waveform LiDAR is an active technology of photogrammetry and remote sensing. It provides more detailed information about objects along the path of a laser pulse than discrete-return topographic LiDAR. The point cloud and waveform information with high quality can be obtained by waveform decomposition, which could make contributions to accurate filtering. The surface fitting filtering method with waveform information is proposed to present such advantage. Firstly, discrete point cloud and waveform parameters are resolved by global convergent Levenberg Marquardt decomposition. Secondly, the ground seed points are selected, of which the abnormal ones are detected by waveform parameters and robust estimation. Thirdly, the terrain surface is fitted and the height difference threshold is determined in consideration of window size and mean square error. Finally, the points are classified gradually with the rising of window size. The filtering process is finished until window size is larger than threshold. The waveform data in urban, farmland and mountain areas from "WATER (Watershed Allied Telemetry Experimental Research)" are selected for experiments. Results prove that compared with traditional method, the accuracy of point cloud filtering is further improved and the proposed method has highly practical value.
Waveform LiDAR across forest biomass gradients
Montesano, P. M.; Nelson, R. F.; Dubayah, R.; Sun, G.; Ranson, J.
2011-12-01
Detailed information on the quantity and distribution of aboveground biomass (AGB) is needed to understand how it varies across space and changes over time. Waveform LiDAR data is routinely used to derive the heights of scattering elements in each illuminated footprint, and the vertical structure of vegetation is related to AGB. Changes in LiDAR waveforms across vegetation structure gradients can demonstrate instrument sensitivity to land cover transitions. A close examination of LiDAR waveforms in footprints across a forest gradient can provide new insight into the relationship of vegetation structure and forest AGB. In this study we use field measurements of individual trees within Laser Vegetation Imaging Sensor (LVIS) footprints along transects crossing forest to non-forest gradients to examine changes in LVIS waveform characteristics at sites with low (LVIS waveforms to detect the forest AGB interval along a forest - non-forest transition in which the LVIS waveform lose the ability to discern differences in AGB. Our results help identify the lower end the forest biomass range that a ~20m footprint waveform LiDAR can detect, which can help infer accumulation of biomass after disturbances and during forest expansion, and which can guide the use of LiDAR within a multi-sensor fusion biomass mapping approach.
A Meta-Analysis of Interventions to Reduce Loneliness
Masi, Christopher M.; Chen, Hsi-Yuan; Hawkley, Louise C.; Cacioppo, John T.
2013-01-01
Social and demographic trends are placing an increasing number of adults at risk for loneliness, an established risk factor for physical and mental illness. The growing costs of loneliness have led to a number of loneliness reduction interventions. Qualitative reviews have identified four primary intervention strategies: 1) improving social skills, 2) enhancing social support, 3) increasing opportunities for social contact, and 4) addressing maladaptive social cognition. An integrative meta-analysis of loneliness reduction interventions was conducted to quantify the effects of each strategy and to examine the potential role of moderator variables. Results revealed that single group pre-post and non-randomized comparison studies yielded larger mean effect sizes relative to randomized comparison studies. Among studies that used the latter design, the most successful interventions addressed maladaptive social cognition. This is consistent with current theories regarding loneliness and its etiology. Theoretical and methodological issues associated with designing new loneliness reduction interventions are discussed. PMID:20716644
ORA waveform-derived biomechanical parameters to distinguish normal from keratoconic eyes
Directory of Open Access Journals (Sweden)
Allan Luz
2013-04-01
Full Text Available PURPOSE: To evaluate the ability of the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Buffalo, NY to distinguish between normal and keratoconic eyes, by comparing pressure and waveform signal-derived parameters. METHODS: This retrospective comparative case series study included 112 patients with normal corneas and 41 patients with bilateral keratoconic eyes. One eye from each subject was randomly selected for analysis. Keratoconus diagnosis was based on clinical examinations, including Placido disk-based corneal topography and rotating Scheimpflug corneal tomography. Data from the ORA best waveform score (WS measurements were extracted using ORA software. Corneal hysteresis (CH, corneal resistance factor (CRF, Goldman-correlated intraocular pressure (IOPg, cornea-compensated intraocular pressure (IOPcc, and 37 parameters derived from the waveform signal were analyzed. Differences in the distributions among the groups were assessed using the Mann-Whitney test. Receiver operating characteristic (ROC curves were calculated. RESULTS: Statistically significant differences between keratoconic and normal eyes were found in all parameters (p<0.05 except IOPcc and W1. The area under the ROC curve (AUROC was greater than 0.85 for 11 parameters, including CH (0.852 and CRF (0.895. The parameters related to the area under the waveform peak during the second and first applanations (p2area and p1area had the best performances, with AUROCs of 0.939 and 0.929, respectively. The AUROCs for CRF, p2area, and p1area were significantly greater than that for CH. CONCLUSION: There are significant differences in biomechanical metrics between normal and keratoconic eyes. Compared with the pressure-derived parameters, corneal hysteresis and corneal resistance factor, novel waveform-derived ORA parameters provide better identification of keratoconus.
Averaging methods for extracting representative waveforms from motor unit action potential trains.
Malanda, Armando; Navallas, Javier; Rodriguez-Falces, Javier; Rodriguez-Carreño, Ignacio; Gila, Luis
2015-08-01
In the context of quantitative electromyography (EMG), it is of major interest to obtain a waveform that faithfully represents the set of potentials that constitute a motor unit action potential (MUAP) train. From this waveform, various parameters can be determined in order to characterize the MUAP for diagnostic analysis. The aim of this work was to conduct a thorough, in-depth review, evaluation and comparison of state-of-the-art methods for composing waveforms representative of MUAP trains. We evaluated nine averaging methods: Ensemble (EA), Median (MA), Weighted (WA), Five-closest (FCA), MultiMUP (MMA), Split-sweep median (SSMA), Sorted (SA), Trimmed (TA) and Robust (RA) in terms of three general-purpose signal processing figures of merit (SPMF) and seven clinically-used MUAP waveform parameters (MWP). The convergence rate of the methods was assessed as the number of potentials per MUAP train (NPM) required to reach a level of performance that was not significantly improved by increasing this number. Test material comprised 78 MUAP trains obtained from the tibialis anterioris of seven healthy subjects. Error measurements related to all SPMF and MWP parameters except MUAP amplitude descended asymptotically with increasing NPM for all methods. MUAP amplitude showed a consistent bias (around 4% for EA and SA and 1-2% for the rest). MA, TA and SSMA had the lowest SPMF and MWP error figures. Therefore, these methods most accurately preserve and represent MUAP physiological information of utility in clinical medical practice. The other methods, particularly WA, performed noticeably worse. Convergence rate was similar for all methods, with NPM values averaged among the nine methods, which ranged from 10 to 40, depending on the waveform parameter evaluated. Copyright © 2015 Elsevier Ltd. All rights reserved.
Notes on the integration of numerical relativity waveforms
Energy Technology Data Exchange (ETDEWEB)
Reisswig, Christian [Theoretical Astrophysics Including Relativity, California Institute of Technology, Pasadena, CA 91125 (United States); Pollney, Denis, E-mail: reisswig@tapir.caltech.edu [Departament de Fisica, Universitat de les Illes Balears, Palma de Mallorca E-07122 (Spain)
2011-10-01
The primary goal of numerical relativity is to provide estimates of the wave strain, h, from strong gravitational wave sources, to be used in detector templates. The simulations, however, typically measure waves in terms of the Weyl curvature component, {psi}{sub 4}. Assuming Bondi gauge, transforming to the strain h reduces to integration of {psi}{sub 4} twice in time. Integrations performed in either the time or frequency domain, however, lead to secular nonlinear drifts in the resulting strain h. These nonlinear drifts are not explained by the two unknown integration constants which can at most result in linear drifts. We identify a number of fundamental difficulties which can arise from integrating finite length, discretely sampled and noisy data streams. These issues are an artifact of post-processing data. They are independent of the characteristics of the original simulation, such as gauge or numerical method used. We suggest, however, a simple procedure for integrating numerical waveforms in the frequency domain, which is effective at strongly reducing spurious secular nonlinear drifts in the resulting strain.
Ultra High Voltage Surge Waveforms Measurement Using an Optical Transducer
Directory of Open Access Journals (Sweden)
Francisco G. PEÑA-LECONA
2010-05-01
Full Text Available Ultra high voltage surge waveforms measurement by means of a portable optical transducer is presented. The sensor system uses a transducer element based on the longitudinal electro-optic effect with a double pass configuration to obtain a better sensitivity. The transducer head is allocated to one meter of distance from the generating element of electric field and it is able to measure waveform surges from 515 kV up to 1090 kV with fast response. It is demonstrated that the telemetry of ultra high voltage surge waveforms can be successfully done by means of this proposed optical transducer.
Zeng, Yue; Tang, Fei; Zhai, Yadong; Wang, Xiaohao
2017-09-01
The traditional operation mode of high-field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) uses a one-way radio frequency (RF) voltage input as the dispersion voltage. This requires a high voltage input and limits power consumption reduction and miniaturization of instruments. With higher dispersion voltages or larger compensation voltages, there also exist problems such as low signal intensity or the fact that the dispersion voltage is no longer much larger than the compensation voltage. In this paper, a differential-RF-driven operation mode of FAIMS is proposed. The two-way RF is used to generate the dispersion field, and a phase difference is added between the two RFs to generate a single step waveform field. Theoretical analysis, and experimental results from an ethanol sample, showed that the peak positions of the ion spectra changed linearly (R2 = 0.9992) with the phase difference of the two RFs in the differential-RF-driven mode and that the peak intensity of the ion spectrum could be enhanced by more than eight times for ethanol ions. In this way, it is possible to convert the ion spectrum peaks outside the separation or compensation voltage range into a detectable range, by changing the phase difference. To produce the same separation electric field, the high-voltage direct current input voltage can be maximally reduced to half of that in the traditional operation mode. Without changing the drift region size or drift condition, the differential-RF-driven operation mode can reduce power consumption, increase signal-to-noise ratio, extend the application range of the dispersion voltage and compensation voltage, and improve FAIMS detection performance.
A Waveform Library Technique for Multi-Site Identification with the MAJORANA DEMONSTRATOR
Buuck, Micah; MAJORANA Collaboration
2017-01-01
The MAJORANA DEMONSTRATOR is a low-background array of 44.8 kg of germanium detectors searching for neutrinoless double-beta (0 νββ) decay in germanium-76, deployed 4,850 feet underground at the Sanford Underground Research Facility in Lead, South Dakota, USA. We aim to demonstrate background levels low enough to justify construction of a ton-scale experiment which will be able to fully probe the inverted-hierarchy region of the 0 νββ decay phase-space. In addition to reducing background through materials selection and experimental design, we are developing a range of analysis-based background-suppression techniques. One example is a waveform-library-based technique to reject background multi-site interactions. Here we present an overview of the technique and its current status. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, the Particle Astrophysics and Nuclear Physics Programs of the National Science Foundation, and the Sanford Underground Research Facility.
Theoretical performance of reiterated LMMSE filtering and coded radar waveforms
Ruggiano, M.; Stolp, E.; Van Genderen, P.
2009-01-01
Orthogonal frequency division multiplexing (OFDM) waveforms offer strong advantages for integrated communication and radar systems. However, they exhibit inherent high-range sidelobes after matched filtering when standard communication constellation symbols are used for the coding of the carriers.
ENHANCED COMPONENT DETECTION ALGORITHM OF FULL-WAVEFORM LIDAR DATA
Directory of Open Access Journals (Sweden)
M. Zhou
2013-05-01
Full Text Available When full-waveform LiDAR (FW-LiDAR data are applied to extract the component feature information of interest targets, there exist a problem of components lost during the waveform decomposition procedure, which severely constrains the performance of subsequent targets information extraction. Focusing on the problem above, an enhance component detection algorithm, which combines Finite Mixed Method (FMM, Levenberg-Marquardt (LM algorithm and Penalized Minimum Matching Distance (PMMD,is proposed in this paper. All of the algorithms for parameters initialization, waveform decomposition and missing component detection have been improved, which greatly increase the precision of component detection, and guarantee the precision of waveform decomposition that could help the weak information extraction of interest targets. The effectiveness of this method is verified by the experimental results of simulation and measured data.
Generation of correlated finite alphabet waveforms using gaussian random variables
Ahmed, Sajid
2016-01-13
Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.
Application of special waveform signals for eddy current testing of materials
Polyakov, V. V.; Gracheva, Ya. J.; Egorov, A. V.; Lependin, A. A.
2017-12-01
This paper presents an approach for multifrequency eddy current testing based on special waveform excitation signals. Digital processing of received signals provides data for experimental hodographs of a "sensor - testing sample" system. Hodographs for the testing of samples of aluminum materials with an applied dielectric layer demonstrates the reliability of the proposed approach. The application of principal component analysis improves the identification and differentiation of testing parameters. The obtained results can be used in systems for nondestructive testing of metallic materials and products.
An Initialization Technique for the Waveform-Relaxation Circuit Simulation
Habib, S. E.-D.; Al-Karim, G. J.
1999-01-01
This paper reports the development of the Cairo University Waveform Relaxation (CUWORX) simulator. In order to accelerate the convergence of the waveform relaxation (WR) in the presence of logic feedback, CUWORK is initialized via a logic simulator. This logic initialization scheme is shown to be highly effective for digital synchronous circuits. Additionally, this logic initialization scheme preserves fully the multi-rate properties of the WR algorithm.
Anisotropic wave-equation traveltime and waveform inversion
Feng, Shihang
2016-09-06
The wave-equation traveltime and waveform inversion (WTW) methodology is developed to invert for anisotropic parameters in a vertical transverse isotropic (VTI) meidum. The simultaneous inversion of anisotropic parameters v0, ε and δ is initially performed using the wave-equation traveltime inversion (WT) method. The WT tomograms are then used as starting background models for VTI full waveform inversion. Preliminary numerical tests on synthetic data demonstrate the feasibility of this method for multi-parameter inversion.
Information Encoding on a Pseudo Random Noise Radar Waveform
2013-03-01
antenna under test AWG arbitrary waveform generator AWGN additive white Gaussian noise BPSK binary phase shift keying CDMA code division multiple...focused on the orthogonal frequency-division multiplexing (OFDM) and code division multiple access ( CDMA ) waveforms. The Ohio State University has...components into a single unit allows for a more mobile compact platform. The plan is diagrammed in Figure 3.5. Figure 3.5: Planned modifications to
Fusion of synthetic aperture radiometer and noise waveform SAR images
Lukin, Konstantin A.; Kudriashov, V. V.
2014-01-01
Noise waveform SAR generates 2D SAR images of a scene. Advanced radiometric SAR imaging provides information on the objects thermal radiation, angular coordinates and even range. The brightness temperatures of rough and smooth surfaces are different. An active, noise waveform, operating mode of bistatic radiometer, based on antennae with beam synthesis, is considered with respect to the roughness criteria. The optimal and quasi-optimal algorithms for fusion of radiometric and SAR images are p...
Full Waveform Inversion Using Oriented Time Migration Method
Zhang, Zhendong
2016-04-12
Full waveform inversion (FWI) for reflection events is limited by its linearized update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate the resulting gradient can have an inaccurate update direction leading the inversion to converge into what we refer to as local minima of the objective function. In this thesis, I first look into the subject of full model wavenumber to analysis the root of local minima and suggest the possible ways to avoid this problem. And then I analysis the possibility of recovering the corresponding wavenumber components through the existing inversion and migration algorithms. Migration can be taken as a generalized inversion method which mainly retrieves the high wavenumber part of the model. Conventional impedance inversion method gives a mapping relationship between the migration image (high wavenumber) and model parameters (full wavenumber) and thus provides a possible cascade inversion strategy to retrieve the full wavenumber components from seismic data. In the proposed approach, consider a mild lateral variation in the model, I find an analytical Frechet derivation corresponding to the new objective function. In the proposed approach, the gradient is given by the oriented time-domain imaging method. This is independent of the background velocity. Specifically, I apply the oriented time-domain imaging (which depends on the reflection slope instead of a background velocity) on the data residual to obtain the geometrical features of the velocity perturbation. Assuming that density is constant, the conventional 1D impedance inversion method is also applicable for 2D or 3D velocity inversion within the process of FWI. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearized representations of the reflection response. To eliminate the cross-talk artifacts between different parameters, I
Faddy, Steven C; Jennings, Paul A
2016-02-10
). Secondary outcomes included risk of failure to revert VF to an organised rhythm following the first shock or up to three shocks, survival to hospital admission and survival to discharge. We included four trials (552 participants) that compared biphasic and monophasic waveform defibrillation in people with OHCA. Based on the assessment of five quality domains, we identified two trials that were at high risk of bias, one trial at unclear risk of bias and one trial at low risk of bias. The risk ratio (RR) for failure to achieve ROSC after biphasic compared to monophasic waveform defibrillation was 0.86 (95% CI 0.62 to 1.20; four trials, 552 participants). The RR for failure to defibrillate on the first shock following biphasic defibrillation compared to monophasic was 0.84 (95% CI 0.70 to 1.01; three trials, 450 participants); and 0.81 (95% CI 0.61 to 1.09; two trials, 317 participants) for one to three stacked shocks. The RR for failure to achieve ROSC after the first shock was 0.92 (95% CI 0.81 to 1.04; two trials, 285 participants). Biphasic waveforms did not reduce the risk of death before hospital admission (RR 1.05, 95% CI 0.90 to 1.23; three trials, 383 participants) or before hospital discharge (RR 1.05, 95% CI 0.78 to 1.42; four trials, 550 participants). There was no statistically significant heterogeneity in any of the pooled analyses. None of the included trials reported adverse events. It is uncertain whether biphasic defibrillators have an important effect on defibrillation success in people with OHCA. Further large studies are needed to provide adequate statistical power.
Design and Testing of Space Telemetry SCA Waveform
Mortensen, Dale J.; Handler, Louis M.; Quinn, Todd M.
2006-01-01
A Software Communications Architecture (SCA) Waveform for space telemetry is being developed at the NASA Glenn Research Center (GRC). The space telemetry waveform is implemented in a laboratory testbed consisting of general purpose processors, field programmable gate arrays (FPGAs), analog-to-digital converters (ADCs), and digital-to-analog converters (DACs). The radio hardware is integrated with an SCA Core Framework and other software development tools. The waveform design is described from both the bottom-up signal processing and top-down software component perspectives. Simulations and model-based design techniques used for signal processing subsystems are presented. Testing with legacy hardware-based modems verifies proper design implementation and dynamic waveform operations. The waveform development is part of an effort by NASA to define an open architecture for space based reconfigurable transceivers. Use of the SCA as a reference has increased understanding of software defined radio architectures. However, since space requirements put a premium on size, mass, and power, the SCA may be impractical for today s space ready technology. Specific requirements for an SCA waveform and other lessons learned from this development are discussed.
Full Elastic Waveform Search Engine for Near Surface Imaging
Zhang, J.; Zhang, X.
2014-12-01
For processing land seismic data, the near-surface problem is often very complex and may severely affect our capability to image the subsurface. The current state-of-the-art technology for near surface imaging is the early arrival waveform inversion that solves an acoustic wave-equation problem. However, fitting land seismic data with acoustic wavefield is sometimes invalid. On the other hand, performing elastic waveform inversion is very time-consuming. Similar to a web search engine, we develop a full elastic waveform search engine that includes a large database with synthetic elastic waveforms accounting for a wide range of interval velocity models in the CMP domain. With each CMP gather of real data as an entry, the search engine applies Multiple-Randomized K-Dimensional (MRKD) tree method to find approximate best matches to the entry in about a second. Interpolation of the velocity models at CMP positions creates 2D or 3D Vp, Vs, and density models for the near surface area. The method does not just return one solution; it gives a series of best matches in a solution space. Therefore, the results can help us to examine the resolution and nonuniqueness of the final solution. Further, this full waveform search method can avoid the issues of initial model and cycle skipping that the method of full waveform inversion is difficult to deal with.
Adaptive Waveform Design for Cognitive Radar in Multiple Targets Situations
Directory of Open Access Journals (Sweden)
Xiaowen Zhang
2018-02-01
Full Text Available In this paper, the problem of cognitive radar (CR waveform optimization design for target detection and estimation in multiple extended targets situations is investigated. This problem is analyzed in signal-dependent interference, as well as additive channel noise for extended targets with unknown target impulse response (TIR. To address this problem, an improved algorithm is employed for target detection by maximizing the detection probability of the received echo on the promise of ensuring the TIR estimation precision. In this algorithm, an additional weight vector is introduced to achieve a trade-off among different targets. Both the estimate of TIR and transmit waveform can be updated at each step based on the previous step. Under the same constraint on waveform energy and bandwidth, the information theoretical approach is also considered. In addition, the relationship between the waveforms that are designed based on the two criteria is discussed. Unlike most existing works that only consider single target with temporally correlated characteristics, waveform design for multiple extended targets is considered in this method. Simulation results demonstrate that compared with linear frequency modulated (LFM signal, waveforms designed based on maximum detection probability and maximum mutual information (MI criteria can make radar echoes contain more multiple-target information and improve radar performance as a result.
Optimal current waveforms for brushless permanent magnet motors
Moehle, Nicholas; Boyd, Stephen
2015-07-01
In this paper, we give energy-optimal current waveforms for a permanent magnet synchronous motor that result in a desired average torque. Our formulation generalises previous work by including a general back-electromotive force (EMF) wave shape, voltage and current limits, an arbitrary phase winding connection, a simple eddy current loss model, and a trade-off between power loss and torque ripple. Determining the optimal current waveforms requires solving a small convex optimisation problem. We show how to use the alternating direction method of multipliers to find the optimal current in milliseconds or hundreds of microseconds, depending on the processor used, which allows the possibility of generating optimal waveforms in real time. This allows us to adapt in real time to changes in the operating requirements or in the model, such as a change in resistance with winding temperature, or even gross changes like the failure of one winding. Suboptimal waveforms are available in tens or hundreds of microseconds, allowing for quick response after abrupt changes in the desired torque. We demonstrate our approach on a simple numerical example, in which we give the optimal waveforms for a motor with a sinusoidal back-EMF, and for a motor with a more complicated, nonsinusoidal waveform, in both the constant-torque region and constant-power region.
3D Electric Waveforms of Solar Wind Turbulence
Kellogg, P. J.; Goetz, K.; Monson, S. J.
2018-01-01
Electric fields provide the major coupling between the turbulence of the solar wind and particles. A large part of the turbulent spectrum of fluctuations in the solar wind is thought to be kinetic Alfvén waves; however, whistlers have recently been found to be important. In this article, we attempt to determine the mode identification of individual waveforms using the three-dimensional antenna system of the SWaves experiments on the STEREO spacecraft. Samples are chosen using waveforms with an apparent periodic structure, selected visually. The short antennas of STEREO respond to density fluctuations and to electric fields. Measurement of four quantities using only three antennas presents a problem. Methods to overcome or to ignore this difficulty are presented. We attempt to decide whether the waveforms correspond to the whistler mode or the Alfvén mode by using the direction of rotation of the signal. Most of the waveforms are so oblique—nearly linearly polarized—that the direction cannot be determined. However, about one third of the waveforms can be identified, and whistlers and Alfvén waves are present in roughly equal numbers. The selected waveforms are very intense but intermittent and are orders of magnitude stronger than the average, yet their accumulated signal accounts for a large fraction of the average. The average, however, is supposed to be the result of a turbulent mixture of many waves, not short coherent events. This presents a puzzle for future work.
Graph-Laplacian features for neural waveform classification.
Ghanbari, Yasser; Papamichalis, Panos E; Spence, Larry
2011-05-01
Analysis of extracellular recordings of neural action potentials (known as spikes) is highly dependent upon the accuracy of neural waveform classification, commonly referred to as spike sorting. Feature extraction is an important stage of this process because it can limit the quality of clustering that is performed in the feature space. Principal components analysis (PCA) is the most commonly used feature extraction method employed for neural spike recordings. To improve upon PCA's feature extraction performance for neural spike sorting, we revisit the PCA procedure to analyze its weaknesses and describe an improved feature extraction method. This paper proposes a linear feature extraction technique that we call graph-Laplacian features, which simultaneously minimizes the graph Laplacian and maximizes variance. The algorithm's performance is compared with PCA and a wavelet-coefficient-based feature extraction algorithm on simulated single-electrode neural data. A cluster-quality metric is proposed to quantitatively measure the algorithm performance. The results show that the proposed algorithm produces more compact and well-separated clusters compared to the other approaches. © 2011 IEEE
Detection of mouse cough based on sound monitoring and respiratory airflow waveforms.
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Liyan Chen
Full Text Available Detection for cough in mice has never yielded clearly audible sounds, so there is still a great deal of debates as to whether mice can cough in response to tussive stimuli. Here we introduce an approach for detection of mouse cough based on sound monitoring and airflow signals. 40 Female BALB/c mice were pretreated with normal saline, codeine, capasazepine or desensitized with capsaicin. Single mouse was put in a plethysmograph, exposed to aerosolized 100 µmol/L capsaicin for 3 min, followed by continuous observation for 3 min. Airflow signals of total 6 min were recorded and analyzed to detect coughs. Simultaneously, mouse cough sounds were sensed by a mini-microphone, monitored manually by an operator. When manual and automatic detection coincided, the cough was positively identified. Sound and sound waveforms were also recorded and filtered for further analysis. Body movements were observed by operator. Manual versus automated counts were compared. Seven types of airflow signals were identified by integrating manual and automated monitoring. Observation of mouse movements and analysis of sound waveforms alone did not produce meaningful data. Mouse cough numbers decreased significantly after all above drugs treatment. The Bland-Altman and consistency analysis between automatic and manual counts was 0.968 and 0.956. The study suggests that the mouse is able to present with cough, which could be detected by sound monitoring and respiratory airflow waveform changes.
Estimation of fracture parameters using elastic full-waveform inversion
Zhang, Zhendong
2017-08-17
Current methodologies to characterize fractures at the reservoir scale have serious limitations in spatial resolution and suffer from uncertainties in the inverted parameters. Here, we propose to estimate the spatial distribution and physical properties of fractures using full-waveform inversion (FWI) of multicomponent surface seismic data. An effective orthorhombic medium with five clusters of vertical fractures distributed in a checkboard fashion is used to test the algorithm. A shape regularization term is added to the objective function to improve the estimation of the fracture azimuth, which is otherwise poorly constrained. The cracks are assumed to be penny-shaped to reduce the nonuniqueness in the inverted fracture weaknesses and achieve a faster convergence. To better understand the inversion results, we analyze the radiation patterns induced by the perturbations in the fracture weaknesses and orientation. Due to the high-resolution potential of elastic FWI, the developed algorithm can recover the spatial fracture distribution and identify localized “sweet spots” of intense fracturing. However, the fracture azimuth can be resolved only using long-offset data.
Monofrequency waveform acquisition and inversion: A new paradigm
Alkhalifah, Tariq Ali
2014-08-05
In seismic inversion, we tend to use the geometrical behavior of the wavefield (the kinematics), extracted from the data, to constrain the long wavelength model components and use the recorded reections to invert for the short wavelength features in a process referred to as full waveform inversion (FWI). For such a recipe, single frequency (the right frequency) data are capable of providing the ingredients for both model components. A frequency that provides model wavelengths (through the transmission components) low enough to update the background and high enough (reections) to map the scattering may render the other frequencies almost obsolete, especially large offset data are available to provide the transition from background to scattering components. Thus, I outline a scenario in which we acquire dedicated mono frequency data, allowing for more time to inject more of that single frequency energy at a reduced cost. The cost savings can be utilized to acquire larger offsets, which is an important for constraining the background model. Combing this single frequency data with a hierarchical scattering angle filter strategy in FWI, and potentially reection FWI, provides an opportunity to invert for complex models starting even with poor initial velocity models. The objective of this new paradigm is a high resolution model of the Earth to replace our focus on the image, which requires a band of frequencies.
Multi-parameter full waveform inversion using Poisson
Oh, Juwon
2016-07-21
In multi-parameter full waveform inversion (FWI), the success of recovering each parameter is dependent on characteristics of the partial derivative wavefields (or virtual sources), which differ according to parameterisation. Elastic FWIs based on the two conventional parameterisations (one uses Lame constants and density; the other employs P- and S-wave velocities and density) have low resolution of gradients for P-wave velocities (or ). Limitations occur because the virtual sources for P-wave velocity or (one of the Lame constants) are related only to P-P diffracted waves, and generate isotropic explosions, which reduce the spatial resolution of the FWI for these parameters. To increase the spatial resolution, we propose a new parameterisation using P-wave velocity, Poisson\\'s ratio, and density for frequency-domain multi-parameter FWI for isotropic elastic media. By introducing Poisson\\'s ratio instead of S-wave velocity, the virtual source for the P-wave velocity generates P-S and S-S diffracted waves as well as P-P diffracted waves in the partial derivative wavefields for the P-wave velocity. Numerical examples of the cross-triangle-square (CTS) model indicate that the new parameterisation provides highly resolved descent directions for the P-wave velocity. Numerical examples of noise-free and noisy data synthesised for the elastic Marmousi-II model support the fact that the new parameterisation is more robust for noise than the two conventional parameterisations.
Waveform Inversion for Estimating the Topography of Three Dimensional Basin Structure
Aoi, S.
2001-12-01
It is well known that the long-period strong ground motion observed in a sedimentary basin is strongly affected by the depth distribution of soft sediments. For accurate simulation of ground motion, it is very important to construct a basin model that can explain the observed waveform in this period. I propose a waveform inversion scheme that estimates three-dimensional basin structure, in particular the depth of the boundary between sediment and bedrock. This study is an extension of the boundary shape waveform inversion scheme (Aoi et al., BSSA, 1995, 1997) to a three-dimensional structure. The idea is to directly parameterize the basin topography and invert it by using long-period strong ground motions including basin induced waves as well as direct waves. The depth of the topography is represented by a series of model parameters and basis functions which are rectangular (boxcar) functions. By this choice of basis functions, the inversion determines the average depth of the bedrock inside rectangles with the constraint that the observation equation, which is non-linear in the model parameter, be satisfied best in the sense of least squares. The observation equation is linearized and solved iteratively. To stabilize the inversion and reduce the amount of calculation, a hierarchical scheme is used that starts the inversion with fewer parameters and increases them gradually. In this study, the finite difference method (FDM) with discontinuous grid (Aoi and fujiwara, BSSA, 1999) is used to calculate waveforms. Sensitivity functions are obtained numerically, by taking the difference of waveforms from perturbed and unperturbed models. The correction values of the parameters obtained by solving the linearized observation equation for each iteration are rounded to the nearest multiple of the grid spacing for the same reason. The validity of the proposed inversion method is tested by the numerical experiment. The assumed target model is typical of the size of middle
System and Method for Generating a Frequency Modulated Linear Laser Waveform
Pierrottet, Diego F. (Inventor); Petway, Larry B. (Inventor); Amzajerdian, Farzin (Inventor); Barnes, Bruce W. (Inventor); Lockard, George E. (Inventor); Hines, Glenn D. (Inventor)
2017-01-01
A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.
2008-04-04
Presentation, San- Agustin , FL, September, 2006 Invited Speaker, Peyman Milanfar, International Conference on Image Processing, Atlanta, GA, Oct...Invited Speaker, Sina Farsiu, Sony Electronics, San Jose , CA, Feb. 2007 Invited Speaker, Peyman Milanfar Conference on Applied Inverse Problems
National Research Council Canada - National Science Library
Milanfar, Peyman
2008-01-01
This program was intended to develop theory a broad range of algorithms and proof of concept in detection, estimation, and reconstruction of objects embedded in turbid media, which hamper visibility...
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Irene Y. H. Gu
2007-01-01
Full Text Available This paper describes an efficient yet accurate methodology for estimating system damping. The proposed technique is based on linear dynamic system theory and the Hilbert damping analysis. The proposed technique requires capacitor switching waveforms only. The detected envelope of the intrinsic transient portion of the voltage waveform after capacitor bank energizing and its decay rate along with the damped resonant frequency are used to quantify effective X/R ratio of a system. Thus, the proposed method provides complete knowledge of system impedance characteristics. The estimated system damping can also be used to evaluate the system vulnerability to various PQ disturbances, particularly resonance phenomena, so that a utility may take preventive measures and improve PQ of the system.
Alfieri, Luisa
2015-12-01
Power quality (PQ) disturbances are becoming an important issue in smart grids (SGs) due to the significant economic consequences that they can generate on sensible loads. However, SGs include several distributed energy resources (DERs) that can be interconnected to the grid with static converters, which lead to a reduction of the PQ levels. Among DERs, wind turbines and photovoltaic systems are expected to be used extensively due to the forecasted reduction in investment costs and other economic incentives. These systems can introduce significant time-varying voltage and current waveform distortions that require advanced spectral analysis methods to be used. This paper provides an application of advanced parametric methods for assessing waveform distortions in SGs with dispersed generation. In particular, the Standard International Electrotechnical Committee (IEC) method, some parametric methods (such as Prony and Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT)), and some hybrid methods are critically compared on the basis of their accuracy and the computational effort required.
Dietrich, Tim
2014-01-01
We reexamine the gravitational collapse of rotating neutron stars to black holes by new 3+1 numerical relativity simulations employing the Z4c formulation of Einstein equations, the moving puncture gauge conditions, and a conservative mesh refinement scheme or the general relativistic hydrodynamics. The end state of the collapse is compared to the vacuum spacetime resulting from the evolution of spinning puncture initial data. Using a local analysis for the metric fields, we demonstrate that the two spacetimes atually agree. Gravitational waveforms are analyzed in some detail. We connect the emission of radiation to the collapse dynamics using simplified spacetime diagrams, and discuss the similarity of the waveform structure with the one of black hole perturbation theory.
Okamoto, T.; Takenaka, H.; Hara, T.; Nakamura, T.; Aoki, T.
2014-12-01
We analyze "seismic" rupture process of the March 11, 2011 Tohoku-Oki earthquake (GCMT Mw9.1) by using a non-linear multi-time-window waveform inversion method. We incorporate the effect of the near-source laterally heterogeneous structure on the synthetic Green's tensor waveforms; otherwise the analysis may result in erroneous solutions [1]. To increase the resolution we use teleseismic and strong-motion seismograms jointly because the one-sided distribution of strong-motion station may cause reduced resolution near the trench axis [2]. We use a 2.5D FDM [3] for teleseismic P-waves and a full 3D FDM that incorporates topography, oceanic water layer, 3D heterogeneity and attenuation for strong-motions [4]. We apply multi-GPU acceleration by using the TSUBAME supercomputer in Tokyo Institute of Technology [5]. We "validated" the Green's tensor waveforms with a point-source moment tensor inversion analysis for a small (Mw5.8) shallow event: we confirm the observed waveforms are reproduced well with the synthetics.The inferred slip distribution using the 2.5D and 3D Green's functions has large slips (max. 37 m) near the hypocenter and small slips near the trench (figure). Also an isolated slip region is identified close to Fukushima prefecture. These features are similar to those obtained by our preliminary study [4]. The land-ward large slips and trench-ward small slips have also been reported by [2]. It is remarkable that we confirmed these features by using data-validated Green's functions. On the other hand very large slips are inferred close to the trench when we apply "1D" Green's functions that do not incorporate the lateral heterogeneity. Our result suggests the trench-ward large deformation that caused large tsunamis did not radiate strong seismic waves. Very slow slips (e.g., the tsunami earthquake), delayed slips and anelastic deformation are among the candidates of the physical processes of the deformation.[1] Okamoto and Takenaka, EPS, 61, e17-e20, 2009
Alkhalifah, Tariq Ali
2012-09-25
Traveltime inversion focuses on the geometrical features of the waveform (traveltimes), which is generally smooth, and thus, tends to provide averaged (smoothed) information of the model. On other hand, general waveform inversion uses additional elements of the wavefield including amplitudes to extract higher resolution information, but this comes at the cost of introducing non-linearity to the inversion operator, complicating the convergence process. We use unwrapped phase-based objective functions in waveform inversion as a link between the two general types of inversions in a domain in which such contributions to the inversion process can be easily identified and controlled. The instantaneous traveltime is a measure of the average traveltime of the energy in a trace as a function of frequency. It unwraps the phase of wavefields yielding far less non-linearity in the objective function than that experienced with conventional wavefields, yet it still holds most of the critical wavefield information in its frequency dependency. However, it suffers from non-linearity introduced by the model (or reflectivity), as reflections from independent events in our model interact with each other. Unwrapping the phase of such a model can mitigate this non-linearity as well. Specifically, a simple modification to the inverted domain (or model), can reduce the effect of the model-induced non-linearity and, thus, make the inversion more convergent. Simple numerical examples demonstrate these assertions.
Multi-source waveform inversion of marine streamer data using the normalized wavefield
Choi, Yun Seok
2012-01-01
Even though the encoded multi-source approach dramatically reduces the computational cost of waveform inversion, it is generally not applicable to marine streamer data. This is because the simultaneous-sources modeled data cannot be muted to comply with the configuration of the marine streamer data, which causes differences in the number of stacked-traces, or energy levels, between the modeled and observed data. Since the conventional L2 norm does not account for the difference in energy levels, multi-source inversion based on the conventional L2 norm does not work for marine streamer data. In this study, we propose the L2, approximated L2, and L1 norm using the normalized wavefields for the multi-source waveform inversion of marine streamer data. Since the normalized wavefields mitigate the different energy levels between the observed and modeled wavefields, the multi-source waveform inversion using the normalized wavefields can be applied to marine streamer data. We obtain the gradient of the objective functions using the back-propagation algorithm. To conclude, the gradient of the L2 norm using the normalized wavefields is exactly the same as that of the global correlation norm. In the numerical examples, the new objective functions using the normalized wavefields generate successful results whereas conventional L2 norm does not.
Relative location using waveform cross correlation: comparison of the Aitik and Kiruna mines
Rozhkov, Mikhail; Bobrov, Dmitry; Kitov, Ivan; Yedlin, Matthew
2017-04-01
Waveform cross correlation (WCC) is a powerful tool of signal detection from repeated events like mining blasts. In this study, we use seismic data measured at four array stations (ARCES, FINES, NOA, and HFS) of the International Monitoring System (IMS) from two quarries in Sweden - the Aitik copper and Kiruna iron mines. Both mines are characterized by intensive blasting practice, with hundreds of blasts found by the International Data Centre and available in its Reviewed Events Bulletin. In our previous study, we applied the WCC method to these repeated signals and estimated the overall similarity of signals at one mine and between mines. In order to provide the best use of the whole multitude of historical events and to reduce the number of waveform templates needed for comprehensive signal detection and association, we applied several high-order factorization techniques to the tensor based representation of seismic array data, so the lower order tensor construction was used as synthetic waveform template set. As a result, we found that signals from two mines might correlate and the only reliable method to actually distinguish between blasts conducted at the Aitik and Kiruna mines is to locate them using arrival times obtained by cross correlation. Here, we present select results of detection, relative location and mine identification as obtained since the end of 2016. This is an out-of-sample test of the procedures related to the WCC method.
Cervantes, Felix A; Backus, Elaine A; Godfrey, Larry; Wallis, Christopher; Akbar, Waseem; Clark, Thomas L; Rojas, Maria G
2017-10-01
Probing behavior of Lygus lineolaris (Palisot de Beauvois) has previously been characterized with electropenetrography (EPG). Cell rupturing (CR) and ingestion (I) EPG waveforms were identified as the two main stylet-probing behaviors by adult L. lineolaris. However, characterization and identification of EPG waveforms are not complete until specific events of a particular waveform are correlated to insect probing. With the use of EPG, histology, microscopy, and chemical analysis, probing behavior of L. lineolaris on pin-head cotton squares was studied. Occurrences of waveforms CR and I were artificially terminated during the EPG recording. Histological samples of probed cotton squares were prepared and analyzed to correlate specific types and occurrences of feeding damage location and plant responses to insect feeding. Both CR and I occurred in the staminal column of the cotton square. Cell rupturing events elicited the production of dark-red deposits seen in histological staining that were demonstrated via chemical analysis to contain condensed tannins. We hypothesize that wounding and saliva secreted during CR triggered release of tannins, because tannin production was positively correlated with the number of probes with single CR events performed by L. lineolaris. Degraded plant tissue and tannins were removed from the staminal column during occurrence of waveform I. These results conclude the process of defining CR and I as probing waveforms performed by L. lineolaris on pin-head cotton squares. These biological definitions will now allow EPG to be used to quantitatively compare L. lineolaris feeding among different plant treatments, with the goal of improving pest management tactics against this pest. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by (a) US Government employee(s) and is in the public domain in the US.
Spectral implementation of full waveform inversion based on reflections
Wu, Zedong
2014-01-01
Using the reflection imaging process as a source to model reflections for full waveform inversion (FWI), referred to as reflection FWI (RFWI), allows us to update the background component of the model, and avoid using the relatively costly migration velocity analysis (MVA), which usually relies on extended images. However, RFWI requires a good image to represent the current reflectivity, as well as, some effort to obtain good smooth gradients. We develop a spectral implementation of RFWI where the wavefield extrapolations and gradient evaluation are performed in the wavenumber domain, obtaining clean dispersion free and fast extrapolations. The gradient, in this case, yields three terms, two of which provide us with each side of the rabbit ear kernel, and the third, often ignored, provides a normalization of the reflectivity within the kernel, which can be used to obtain a reflectivity free background update. Since the image is imperfect (it is an adjoint, not an inverse), an optimization process for the third term scaling is implemented to achieve the smoothest gradient update. A rare application of RFWI on the reflectivity infested Marmousi model shows some of the potential of the approach.
Action potential waveform variability limits multi-unit separation in freely behaving rats.
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Peter Stratton
Full Text Available Extracellular multi-unit recording is a widely used technique to study spontaneous and evoked neuronal activity in awake behaving animals. These recordings are done using either single-wire or multiwire electrodes such as tetrodes. In this study we have tested the ability of single-wire electrodes to discriminate activity from multiple neurons under conditions of varying noise and neuronal cell density. Using extracellular single-unit recording, coupled with iontophoresis to drive cell activity across a wide dynamic range, we studied spike waveform variability, and explored systematic differences in single-unit spike waveform within and between brain regions as well as the influence of signal-to-noise ratio (SNR on the similarity of spike waveforms. We also modelled spike misclassification for a range of cell densities based on neuronal recordings obtained at different SNRs. Modelling predictions were confirmed by classifying spike waveforms from multiple cells with various SNRs using a leading commercial spike-sorting system. Our results show that for single-wire recordings, multiple units can only be reliably distinguished under conditions of high recording SNR (≥ 4 and low neuronal density (≈ 20,000/ mm(3. Physiological and behavioural changes, as well as technical limitations typical of awake animal preparations, reduce the accuracy of single-channel spike classification, resulting in serious classification errors. For SNR <4, the probability of misclassifying spikes approaches 100% in many cases. Our results suggest that in studies where the SNR is low or neuronal density is high, separation of distinct units needs to be evaluated with great caution.
CSIR Research Space (South Africa)
Van Aardt, JAN
2012-07-01
Full Text Available this relationship vary by the area used for signal integration?). Results have significant implications in terms of a cost-benefit analysis: The use of a discrete return instead of a waveform system leads to a reduction in cost, data volume, signal complexity...
Waveform Integrity in Atrial Fibrillation: The Forgotten Issue of Cardiac Electrophysiology.
Martínez-Iniesta, Miguel; Ródenas, Juan; Alcaraz, Raúl; Rieta, José J
2017-08-01
Atrial fibrillation (AF) is the most common arrhythmia in clinical practice with an increasing prevalence of about 15% in the elderly. Despite other alternatives, catheter ablation is currently considered as the first-line therapy for the treatment of AF. This strategy relies on cardiac electrophysiology systems, which use intracardiac electrograms (EGM) as the basis to determine the cardiac structures contributing to sustain the arrhythmia. However, the noise-free acquisition of these recordings is impossible and they are often contaminated by different perturbations. Although suppression of nuisance signals without affecting the original EGM pattern is essential for any other later analysis, not much attention has been paid to this issue, being frequently considered as trivial. The present work introduces the first thorough study on the significant fallout that regular filtering, aimed at reducing acquisition noise, provokes on EGM pattern morphology. This approach has been compared with more refined denoising strategies. Performance has been assessed both in time and frequency by well established parameters for EGM characterization. The study comprised synthesized and real EGMs with unipolar and bipolar recordings. Results reported that regular filtering altered substantially atrial waveform morphology and was unable to remove moderate amounts of noise, thus turning time and spectral characterization of the EGM notably inaccurate. Methods based on Wavelet transform provided the highest ability to preserve EGM morphology with improvements between 20 and beyond 40%, to minimize dominant atrial frequency estimation error with up to 25% reduction, as well as to reduce huge levels of noise with up to 10 dB better reduction. Consequently, these algorithms are recommended as a replacement of regular filtering to avoid significant alterations in the EGMs. This could lead to more accurate and truthful analyses of atrial activity dynamics aimed at understanding and
Working Performance Analysis of Rolling Bearings Used in Mining Electric Excavator Crowd Reducer
Zhang, Y. H.; Hou, G.; Chen, G.; Liang, J. F.; Zheng, Y. M.
2017-12-01
Refer to the statistical load data of digging process, on the basis of simulation analysis of crowd reducer system dynamics, the working performance simulation analysis of rolling bearings used in crowd reducer of large mining electric excavator is completed. The contents of simulation analysis include analysis of internal load distribution, rolling elements contact stresses and rolling bearing fatigue life. The internal load characteristics of rolling elements in cylindrical roller bearings are obtained. The results of this study identified that all rolling bearings satisfy the requirements of contact strength and fatigue life. The rationality of bearings selection and arrangement is also verified.
Ocular pressure waveform reflects ventricular bigeminy and aortic insufficiency
Directory of Open Access Journals (Sweden)
Jean B Kassem
2015-01-01
Full Text Available Ocular pulse amplitude (OPA is defined as the difference between maximum and minimum intraocular pressure (IOP during a cardiac cycle. Average values of OPA range from 1 to 4 mmHg. The purpose of this investigation is to determine the source of an irregular IOP waveform with elevated OPA in a 48-year-old male. Ocular pressure waveforms had an unusual shape consistent with early ventricular contraction. With a normal IOP, OPA was 9 mmHg, which is extraordinarily high. The subject was examined by a cardiologist and was determined to be in ventricular bigeminy. In addition, he had bounding carotid pulses and echocardiogram confirmed aortic insufficiency. After replacement of the aortic valve, the bigeminy resolved and the ocular pulse waveform became regular in appearance with an OPA of 1.6-2.0 mmHg. The ocular pressure waveform is a direct reflection of hemodynamics. Evaluating this waveform may provide an additional opportunity for screening subjects for cardiovascular anomalies and arrhythmias.
Inversion of acoustic waveforms for velocity and attenuation
Sun, Xinhua
In this dissertation, I present some new schemes and techniques for processing of acoustic waveform data. New objective functions are developed for waveform inversion. I use synthetic acoustic borehole waveform data to demonstrate their novel features. These schemes require neither prior deconvolution nor knowledge of the source- receiver wavelet. The most powerful of them is the fourwise processor, which is applicable to data sets from multiple shots and receivers even when each shot has a different unknown signature and each receiver has a different unknown impulse response. I apply this scheme to inversion for shear wave velocity from the ODP sonic data measured by an LSS tool, containing two uncalibrated transmitters and receivers. A 3-D search of waveform inversion gives stable results of formation S-wave velocity inverted from the monopole sonic data in a slow formation. In addition, I develop new techniques to extract P- and S-wave attenuation from sonic logging data. The success of the techniques lies in the separation of attenuation-related wave attributes from other effects unrelated to attenuation. The wave attributes related to borehole diameter, formation density, and velocity changes are removed by use of synthetic sonograms. The novelty of the techniques is first to use a single receiver data set to extract a relative attenuation profile, then to correct it to absolute attenuation using multiple receiver data sets. The techniques are applicable to both monopole and dipole waveform log data for either P- or S-wave attenuation.
Validity of linear acoustics for prediction of waveforms caused by sonically moving laser beams.
Pierce, A D; Berthelot, Y H
1988-03-01
The question is raised as to whether the analysis of the generation of sound by a laser beam moving over a water surface at the sound speed c for an interminable time period requires consideration of nonlinear effects. A principal consideration in this regard is whether the linear acoustics theory predicts a pressure waveform that is bounded in the asymptotic limit when the laser irradiation time is arbitrarily large. It is shown that a bounded asymptotic limit exists when the upper boundary condition corresponds (as is more nearly appropriate) to that of a pressure release surface, but not when it corresponds to that of a rigid surface. The asymptotic solution to the appropriate inhomogeneous wave equation is given exactly for the former case, and it is shown that the highest asymptotic amplitudes, given specified laser power and beam radius a, occur in the limit of a very small light absorption coefficient mu. In this limit, the peak amplitude is independent of mu and occurs at a depth of 0.88/mu. An approximate solution for the pressure waveform at intermediate times establishes that the characteristic time for buildup to the asymptotic limit is of the order of 2.5/(c mu 2a). If this time is substantially shorter than the time that a plane-wave pulse with the asymptotic waveform would take to develop a shock wave, then accumulative nonlinear effects are of minor importance.
Energy Technology Data Exchange (ETDEWEB)
Soleimani, Effat; Mokhtari-Dizaji, Manijhe [Dept. of Medical Physics, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Fatouraee, Nasser [Dept. of Medical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Saben, Hazhir [Dept. Radiology, Imaging Center of Imam Khomaini Hospital, Tehran Medical Sciences University, Tehran (Iran, Islamic Republic of)
2017-04-15
The aim of this study was to introduce and implement a noninvasive method to derive the carotid artery pressure waveform directly by processing diagnostic sonograms of the carotid artery. Ultrasound image sequences of 20 healthy male subjects (age, 36±9 years) were recorded during three cardiac cycles. The internal diameter and blood velocity waveforms were extracted from consecutive sonograms over the cardiac cycles by using custom analysis programs written in MATLAB. Finally, the application of a mathematical equation resulted in time changes of the arterial pressure. The resulting pressures were calibrated using the mean and the diastolic pressure of the radial artery. A good correlation was found between the mean carotid blood pressure obtained from the ultrasound image processing and the mean radial blood pressure obtained using a standard digital sphygmomanometer (R=0.91). The mean absolute difference between the carotid calibrated pulse pressures and those measured clinically was -1.333±6.548 mm Hg. The results of this study suggest that consecutive sonograms of the carotid artery can be used for estimating a blood pressure waveform. We believe that our results promote a noninvasive technique for clinical applications that overcomes the reproducibility problems of common carotid artery tonometry with technical and anatomical causes.
Vuilliez, A; Floccard, B; Sobas, F; Chopin, N; Allaouchiche, B
2007-03-01
The biphasic waveform (BPW) is an abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time on a specific photometric haemostasis autoanalyzer. This abnormality is related to calcium-dependent formation of complexes between C reactive protein and very low density lipoprotein. Biphasic waveform had a high sensitivity and negative predictive value for the identification of patients with severe sepsis and septic shock. On day 3, the time course of the biphasic waveform is a marker for the prognosis of sepsis-related mortality. The BPW is not a surrogate marker for C-reactive protein or procalcitonin and provides additional information. Further trials should be necessary using BPW for diagnostic and management procedures. Compared with other laboratory markers such as C reactive protein or procalcitonin, activated partial thromboplastin time waveform analysis is a tool that is rapid, inexpensive, effective and available 24 hours a day. When the analyzer is locally available, waveform analysis of this routine coagulation test provides information for the diagnosis of severe sepsis and the prognosis of septic patients.
Tabara, Yasuharu; Takahashi, Yoshimitsu; Kohara, Katsuhiko; Setoh, Kazuya; Kawaguchi, Takahisa; Terao, Chikashi; Igase, Michiya; Yamada, Ryo; Kosugi, Shinji; Sekine, Akihiro; Miki, Tetsuro; Nakayama, Takeo; Matsuda, Fumihiko
2013-08-01
Central systolic blood pressure (cSBP) has been postulated to correlate closely with cardiovascular risk. Identifying factors associated with cSBP is therefore important. Prolonged QT interval is known to be associated with cardiovascular outcomes and might also be associated with the arterial waveform and cSBP. We investigated the possible associations between electrocardiogram wave interval and cSBP in general population samples. Brachial blood pressure and radial arterial waveform were measured simultaneously. Augmentation index (AIx) was calculated from the radial waveform as the ratio of the height of the late systolic peak to that of the first peak. cSBP was defined as the absolute pressure of the late systolic peak. In the first panel (n = 8,085), QT interval was strongly association with AIx (r = 0.330; P blood pressure, heart rate, and pulse wave velocity, multivariable analysis with adjustment for these covariables nevertheless identified longer corrected QT interval as an independent determinant of increased AIx and smaller pulse pressure amplification (PPa; brachial SBP minus cSBP) (β = -0.066; P < 0.001). This association was replicated in the independent second panel (n = 1,412) (β = -0.105; P < 0.001). In contrast, QRS interval was positively associated with PPa (β = 0.056; P < 0.001). Longer QT interval and short QRS duration were significantly associated with arterial waveform and PPa. Our results provide a clue to the elucidation of unidentified mechanisms of the increased cardiovascular outcome and mortality risks in subjects with longer QT interval.
Arroucau, Pierre; Grannell, James; Lebedev, Sergei; Bean, Chris J.; Möllhoff, Martin; Blake, Tom; Horan, Clare
2017-04-01
Earthquake monitoring in intraplate continental interiors requires the detection of low magnitude events in regions that are sometimes poorly instrumented due to low estimated hazard and risk. According to existing catalogues, the seismic activity of Ireland is characterized by low magnitude, infrequent earthquakes. This is expected as Ireland is located several hundred kilometers away from the closest plate boundaries. However, the lack of seismic activity is still surprising in comparison with that of Great Britain, its closest neighbour. Since Ireland's historical seismic station coverage was significantly sparser than that of Great Britain, a possible instrumental bias has been invoked, but recent results obtained from the analysis of waveforms recorded at dense temporary arrays and new permanent stations tend to confirm the relative quiet seismogenic behaviour of Ireland's crust. However, classical detection methods are known to fail if site conditions are too noisy, hence very low magnitude events can still be missed. Such events are of primary importance for seismotectonic studies, so in this work we investigate the possibility of producing new detections by cross-correlating the available continuous waveform data with waveform templates from catalogue earthquakes. Preliminary results show that more than 200 new events can be identified over the past 5 years, which is particularly significant considering the 120 events present in the catalogue for the period 1980-2016. Despite the limitation of the technique to events whose location and source characteristics are close to previously known ones, these results demonstrate that waveform template cross-correlation can successfully be used to lower detection thresholds in a seismically quiet region such as Ireland.
Pirli, Myrto; Gibbons, Steven J.; Schweitzer, Johannes
2011-07-01
Cross-correlation analysis was applied to events in the 2003 Lefkada Island, Greece, sequence in order to identify clusters of seismicity within the extensive aftershock sequence along a fault zone of approximately 100 km length. Data from the small-aperture TRISAR array, covering the first 2 days of aftershock activity, were used. Array-based waveform correlation has a great advantage over single channel correlation analysis in that the validity of waveform matches with relatively low correlation coefficients can be examined by checking the alignment of correlation traces on the different channels. The length of the fault zone leads inevitably to a great diversity in the waveforms, although a small number of clusters of very similar events emerge from the TRISAR data. Events which the correlation analysis had placed within the same cluster were listed in the ISC Bulletin with separations of up to tens of kilometres. This made it necessary to check the validity of the TRISAR clusters by applying the same procedure independently to the three-component stations of the National Seismographic Network of the National Observatory of Athens, located at local to regional distances from the aftershock area. Results suggest that array-based waveform correlation provides a robust tool both for identifying event clusters within large aftershock areas and for identifying situations in which bulletin event location estimates need re-evaluation.
Classification of Pulse Waveforms Using Edit Distance with Real Penalty
Directory of Open Access Journals (Sweden)
Zhang Dongyu
2010-01-01
Full Text Available Abstract Advances in sensor and signal processing techniques have provided effective tools for quantitative research in traditional Chinese pulse diagnosis (TCPD. Because of the inevitable intraclass variation of pulse patterns, the automatic classification of pulse waveforms has remained a difficult problem. In this paper, by referring to the edit distance with real penalty (ERP and the recent progress in -nearest neighbors (KNN classifiers, we propose two novel ERP-based KNN classifiers. Taking advantage of the metric property of ERP, we first develop an ERP-induced inner product and a Gaussian ERP kernel, then embed them into difference-weighted KNN classifiers, and finally develop two novel classifiers for pulse waveform classification. The experimental results show that the proposed classifiers are effective for accurate classification of pulse waveform.
Shaping the spectrum of random-phase radar waveforms
Doerry, Armin W.; Marquette, Brandeis
2017-05-09
The various technologies presented herein relate to generation of a desired waveform profile in the form of a spectrum of apparently random noise (e.g., white noise or colored noise), but with precise spectral characteristics. Hence, a waveform profile that could be readily determined (e.g., by a spoofing system) is effectively obscured. Obscuration is achieved by dividing the waveform into a series of chips, each with an assigned frequency, wherein the sequence of chips are subsequently randomized. Randomization can be a function of the application of a key to the chip sequence. During processing of the echo pulse, a copy of the randomized transmitted pulse is recovered or regenerated against which the received echo is correlated. Hence, with the echo energy range-compressed in this manner, it is possible to generate a radar image with precise impulse response.
Generating Correlated QPSK Waveforms By Exploiting Real Gaussian Random Variables
Jardak, Seifallah
2012-11-01
The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift- keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV’s). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) schemes that can better approximate the desired beampattern.
Closed-loop waveform control of boost inverter
DEFF Research Database (Denmark)
Zhu, Guo Rong; Xiao, Cheng Yuan; Wang, Haoran
2016-01-01
The input current of single-phase inverter typically has an AC ripple component at twice the output frequency, which causes a reduction in both the operating lifetime of its DC source and the efficiency of the system. In this paper, the closed-loop performance of a proposed waveform control method...... to eliminate such a ripple current in boost inverter is investigated. The small-signal stability and the dynamic characteristic of the inverter system for input voltage or wide range load variations under the closed-loop waveform control method are studied. It is validated that with the closedloop waveform...... control, not only was stability achieved, the reference voltage of the boost inverter capacitors can be instantaneously adjusted to match the new load, thereby achieving improved ripple mitigation for a wide load range. Furthermore, with the control and feedback mechanism, there is minimal level of ripple...
Full-waveform inversion using a nonlinearly smoothed wavefield
Li, Yuanyuan
2017-12-08
Conventional full-waveform inversion (FWI) based on the least-squares misfit function faces problems in converging to the global minimum when using gradient methods because of the cycle-skipping phenomena. An initial model producing data that are at most a half-cycle away from the observed data is needed for convergence to the global minimum. Low frequencies are helpful in updating low-wavenumber components of the velocity model to avoid cycle skipping. However, low enough frequencies are usually unavailable in field cases. The multiplication of wavefields of slightly different frequencies adds artificial low-frequency components in the data, which can be used for FWI to generate a convergent result and avoid cycle skipping. We generalize this process by multiplying the wavefield with itself and then applying a smoothing operator to the multiplied wavefield or its square to derive the nonlinearly smoothed wavefield, which is rich in low frequencies. The global correlation-norm-based objective function can mitigate the dependence on the amplitude information of the nonlinearly smoothed wavefield. Therefore, we have evaluated the use of this objective function when using the nonlinearly smoothed wavefield. The proposed objective function has much larger convexity than the conventional objective functions. We calculate the gradient of the objective function using the adjoint-state technique, which is similar to that of the conventional FWI except for the adjoint source. We progressively reduce the smoothing width applied to the nonlinear wavefield to naturally adopt the multiscale strategy. Using examples on the Marmousi 2 model, we determine that the proposed FWI helps to generate convergent results without the need for low-frequency information.
The waveform correlation event detection system global prototype software design
Energy Technology Data Exchange (ETDEWEB)
Beiriger, J.I.; Moore, S.G.; Trujillo, J.R.; Young, C.J.
1997-12-01
The WCEDS prototype software system was developed to investigate the usefulness of waveform correlation methods for CTBT monitoring. The WCEDS prototype performs global seismic event detection and has been used in numerous experiments. This report documents the software system design, presenting an overview of the system operation, describing the system functions, tracing the information flow through the system, discussing the software structures, and describing the subsystem services and interactions. The effectiveness of the software design in meeting project objectives is considered, as well as opportunities for code refuse and lessons learned from the development process. The report concludes with recommendations for modifications and additions envisioned for regional waveform-correlation-based detector.
Krylov-subspace acceleration of time periodic waveform relaxation
Energy Technology Data Exchange (ETDEWEB)
Lumsdaine, A. [Univ. of Notre Dame, IN (United States)
1994-12-31
In this paper the author uses Krylov-subspace techniques to accelerate the convergence of waveform relaxation applied to solving systems of first order time periodic ordinary differential equations. He considers the problem in the frequency domain and presents frequency dependent waveform GMRES (FDWGMRES), a member of a new class of frequency dependent Krylov-subspace techniques. FDWGMRES exhibits many desirable properties, including finite termination independent of the number of timesteps and, for certain problems, a convergence rate which is bounded from above by the convergence rate of GMRES applied to the static matrix problem corresponding to the linear time-invariant ODE.
Petrofsky, J; Laymon, M; Prowse, M; Gunda, S; Batt, J
2009-01-01
Electrical stimulation is a commonly used modality for both athletic training and physical therapy. However, there are limited objective data available to determine the waveform which provides the maximum muscle strength as well as minimizing pain. In the present investigation, two groups of subjects were examined. Group 1 was composed of six males and four females and group 2 was composed of three male and three female subjects. The first series of experiments investigated muscle strength with stimulation at currents of 20, 40 and 60 milliamps using sine, square, Russian and interferential waveforms evaluating strength production and pain as outcomes. The second phase of experiments compared the effect of the different waveforms on current dispersion in surface versus deep muscle electrodes with these same waveforms. The results of the experiments showed that sine wave stimulation produced significantly greater muscle strength and significantly less pain than square wave, Russian or interferential stimulation at that same current. The most painful stimulation was square wave. Strength production was greatest with sine wave and least with Russian and interferential. An explanation of these findings may be the filtering effect of the fat layer separating skin from muscle. The highly conductive muscle and skin dermal layers would form the plates of a capacitor separated by the subcutaneous fat layer providing an RC filter. This filtering effect, while allowing sine wave stimulation to pass to the muscle, reduced power transfer in square wave, Russian and interferential stimulation is observed.
Roohi, Shirzad; Sneeuw, Nico; Tseng, Kuo-Hsin; Shum, CK
2014-05-01
Pulse-limited-satellite altimetry was originally designed for oceanographic observations but has been extended to monitor inland water bodies. So far, studying water level variations of inland water bodies, e.g. lakes, has been a challenge for this type of altimetry in terms of data quality. The returned altimetry waveforms could be seriously contaminated by topography and environmental error sources. Retracking is an efficacious method against this contamination to improve the accuracy of range measurement and consequently robust water level determination. In addition, the choice of an optimal retracking algorithm appropriate for the specific regional water bodies is very important in this respect. In this study we processed 18 Hz Envisat RA2 altimetry data, i.e. Sensor Geophysical Data records (SGDR), with respective different retrackers and 1 Hz Geophysical Data Records (GDRs) of this mission by on-board retrackers. First, for a given waveform the whole waveform, called full-waveform, was processed to estimate retracked water level variation using OCOG, Threshold and β-parameter retrackers. In the next step we assumed that the reflecting surface inside the radar foot print is a complex surface with different responses. Therefore a given waveform considered as a combination of a number of small waveforms, called sub-waveform. Each sub-waveform was processed by all of the mentioned retrackers to determine water level variations. Finally the result of different retracked heights were compared with on-board retrackers, and with available in-situ gauge data. The largest salt lake in the middle east, Urmia lake, has been selected as a testing area in this study. This lake is drying up due to climate change and human activities, e.g. irrigation and dam construction. Our retracking analysis shows that the sub-waveform retracking outperforms the full-waveform retracking. The minimum RMS, i.e. 18 cm, was obtained by sub-waveform, retracked with Threshold 50% algorithm
Park, Yunhui; Pyun, Sukjoon
2017-03-01
As full waveform inversion (FWI) requires large computation time, a variety of techniques have been suggested to reduce the computational burden. In this study, we use wavenumber-space-time domain modelling, which directly generates common mid-point (CMP) gathers, to implement the FWI algorithm. The modelling technique, which is suitable for laterally invariant velocity models, synthesises CMP gathers efficiently by using limited wavenumber components, and therefore allows reduced computation time for FWI. To consider the accuracy as well as the efficiency of FWI, the Gauss-Newton method using the approximate Hessian matrix is chosen in this study. Rather than using all of the wavenumber components, our FWI algorithm can be accelerated by using only a few components. The wavenumber components can be chosen through an analysis of the residual wavefields. To validate the usefulness of our method, we first use a one-dimensional (1D) velocity model. From the 1D model example, we note that our FWI algorithm can be successful if given a reliable initial velocity model and sufficient data with a long offset distance. Even though our algorithm is valid for only horizontally layered velocity models, we apply our algorithm to a two-dimensional (2D) velocity model with lateral velocity variations. Through the 2D velocity example, we confirm that our FWI can be used to estimate subsurface structures with dipping interfaces if the dips are moderate and the structures can thus be considered to be locally flat.
Kim, Maureen L; Kim, Soo G; Park, David S; Gross, Jay N; Ferrick, Kevin J; Palma, Eugen C; Fisher, John D
2004-12-01
Success rates of cardioversion with a defibrillator using the truncated exponential biphasic waveform (with a maximum energy of 360 J) and a defibrillator using the rectilinear biphasic waveform (with a maximum energy of 200 J) were randomly compared in 145 patients. Success rates at 50, 100, 150, and 200 J were not significantly different, but 2 patients who did not achieve cardioversion after a 200-J maximum energy shock by the rectilinear device underwent successful cardioversion with a 360-J shock by the truncated exponential device after crossover.
URBAN TREE CLASSIFICATION USING FULL-WAVEFORM AIRBORNE LASER SCANNING
Directory of Open Access Journals (Sweden)
Zs. Koma
2016-06-01
Full Text Available Vegetation mapping in urban environments plays an important role in biological research and urban management. Airborne laser scanning provides detailed 3D geodata, which allows to classify single trees into different taxa. Until now, research dealing with tree classification focused on forest environments. This study investigates the object-based classification of urban trees at taxonomic family level, using full-waveform airborne laser scanning data captured in the city centre of Vienna (Austria. The data set is characterised by a variety of taxa, including deciduous trees (beeches, mallows, plane trees and soapberries and the coniferous pine species. A workflow for tree object classification is presented using geometric and radiometric features. The derived features are related to point density, crown shape and radiometric characteristics. For the derivation of crown features, a prior detection of the crown base is performed. The effects of interfering objects (e.g. fences and cars which are typical in urban areas on the feature characteristics and the subsequent classification accuracy are investigated. The applicability of the features is evaluated by Random Forest classification and exploratory analysis. The most reliable classification is achieved by using the combination of geometric and radiometric features, resulting in 87.5% overall accuracy. By using radiometric features only, a reliable classification with accuracy of 86.3% can be achieved. The influence of interfering objects on feature characteristics is identified, in particular for the radiometric features. The results indicate the potential of using radiometric features in urban tree classification and show its limitations due to anthropogenic influences at the same time.
Waveform inversion of surface waves at geotechnical scale
Billien, M.; Maupin, V.
2003-04-01
The depth profile of the shear modulus in the Earth is commonly measured by analysing the dispersion of surface waves, and this at very different scales, from a few meters in geotechnique, to a few hundred km in seismology. In geotechnique, inverting seismograms for the shear modulus of the structure is a challenging problem due to the very large span of possible model parameters and to the highly non-linear relation between model and wavefield. We present here an analysis of how a global search algorithm can be used to solve this problem. The technique is based on comparing the data with complete synthetic seismograms and using a so-called neighbourhood algorithm to search in an efficient way for models which best fit the data. The synthetic seismograms are made in plane layered structures with the discrete wavenumber integration method. Multimode surface waves can be treated without extracting the modal dispersion curves, and models with decreasing velocity with depth can be analysed. The performance of the method is of course strongly dependent on the misfit function which is used to compare data and synthetics. In most cases, misfits calculated in the frequency domain lead to better results than misfits calculated in the time domain. Since the surface layers have a much larger influence on the waveforms than the parameters of the deeper layers, we found necessary to use the search algorithm in an iterative way, searching first for the velocity in the first layer, and then refining iteratively the profile with depth. Although global search methods with computation of full synthetic seismograms can of course not compete with linearised inversions of dispersion curves in terms of computation time, we show that they are feasible on an ordinary workstation in a reasonable amount of time, and can therefore be an alternative inversion method for complex datasets.
A new parameterization for waveform inversion in acoustic orthorhombic media
Masmoudi, Nabil
2016-05-26
Orthorhombic anisotropic model inversion is extra challenging because of the multiple parameter nature of the inversion problem. The high number of parameters required to describe the medium exerts considerable trade-off and additional nonlinearity to a full-waveform inversion (FWI) application. Choosing a suitable set of parameters to describe the model and designing an effective inversion strategy can help in mitigating this problem. Using the Born approximation, which is the central ingredient of the FWI update process, we have derived radiation patterns for the different acoustic orthorhombic parameterizations. Analyzing the angular dependence of scattering (radiation patterns) of the parameters of different parameterizations starting with the often used Thomsen-Tsvankin parameterization, we have assessed the potential trade-off between the parameters and the resolution in describing the data and inverting for the parameters. The analysis led us to introduce new parameters ϵd, δd, and ηd, which have azimuthally dependent radiation patterns, but keep the scattering potential of the transversely isotropic parameters stationary with azimuth (azimuth independent). The novel parameters ϵd, δd, and ηd are dimensionless and represent a measure of deviation between the vertical planes in orthorhombic anisotropy. Therefore, these deviation parameters offer a new parameterization style for an acoustic orthorhombic medium described by six parameters: three vertical transversely isotropic (VTI) parameters, two deviation parameters, and one parameter describing the anisotropy in the horizontal symmetry plane. The main feature of any parameterization based on the deviation parameters, is the azimuthal independency of the modeled data with respect to the VTI parameters, which allowed us to propose practical inversion strategies based on our experience with the VTI parameters. This feature of the new parameterization style holds for even the long-wavelength components of
Euler, G. G.; Hartse, H. E.; MacCarthy, J.
2016-12-01
Using waveform cross-correlation, 1000 repeating events in the seismic bulletin published by the Kazakhstan National Data Center from 2002 to 2007 were identified. Most of these repeating events could be grouped into 17 clusters that we then relocated by picking phases on the stacked waveforms of seismic stations KURK, MKAR, KKAR, BVAR and ZALV. Inspection of satellite imagery near the relocations identified visual evidence of open-pit mining within 10 km of most of our seismic locations. We then demonstrate that once waveform templates are established for a given mine, continuous data can be scanned to find additional, unreported events from the same mine. In particular, we detect several unreported Kara-Zhyra coal mine explosions from the first half of 2004, and we also find a November, 2009 explosion at the same mine used for the Comprehensive Test-Ban Treaty Organization's National Data Center Preparedness Exercise known as NPE2009. From time-of-day analysis we learned that mine shots in eastern Kazakhstan typically occurred between noon and 1 pm and between 6 and 7 pm local time while less frequent shooting occurred anytime from 6 am up through 8 pm. We also identified one mine that shoots frequently near midnight on Saturdays, which is the first reported seismic evidence in this region of prevalent non-daytime mining activity. Consistent with expectations for mining activity, all reported magnitudes for the mining events were mb ≤ 3.5. We subsequently used this information to create a ground-truth earthquake dataset by selecting (1) events of any magnitude when they occur during hours 21, 22, and 23 UTC (3, 4, and 5 am local time), (2) events of mb ≥ 4.0 regardless of origin time, and (3) any events displaying significant waveform correlation with an event of mb ≥ 4.0. These results show that combining bulletin information, waveform correlation results, and satellite imagery can improve ground-truth data set quality used in seismic research for
On the Contribution of Head Waves to Full Waveform Inversion
Kazei, V.V.; Ponomarenko, A.V.; Troyan, V.N.; Kashtan, B.M.; Mulder, W.A.
2012-01-01
Full waveform inversion suffers from local minima, due to a lack of low frequencies in the data. A reflector below the zone of interest may, however, help in recovering the long-wavelength components of a velocity perturbation, as demonstrated in a paper by Mora. With the Born approximation for the
Seismic Broadband Full Waveform Inversion by shot/receiver refocusing
Haffinger, P.R.
2013-01-01
Full waveform inversion is a tool to obtain high-resolution property models of the subsurface from seismic data. However, the technique is computationally expens- ive and so far no multi-dimensional implementation exists to achieve a resolution that can directly be used for seismic interpretation
The effect of nifedipine on fetal umbilical Doppler waveforms in ...
African Journals Online (AJOL)
The effect of nifedipine 5 mg administered sublingually to pregnant hypertensive patients was examined in a randomised controlled double-blind study. The effect on maternal blood pressure and the fetal umbilical artery Doppler waveform was studied for 30 minutes before and 30 minutes after administration of the drug or ...
Waveform inversion for Earth structure: Progress and Prospects
Geller, R. J.; Kawai, K.; Fuji, N.; Konishi, K.
2012-12-01
Throughout the history of seismology, knowledge of Earth structure has advanced significantly when new techniques were applied to large datasets; the J-B model and travel-time tomography are two notable examples. Recent progress in inversion of seismic body wave waveforms appears to be another such notable instance. In this talk we mainly review and summarize work by our group. In order to realize the goal of being able to invert seismic body wave waveforms, several technical developments were necessary. First, we developed accurate and efficient methods for computing synthetic seismograms (Kawai et al., GJI, 2006 and works cited therein) and their partial derivatives (Geller and Hara, GJI, 1993). Efficient software for handling large datasets, and robust methods for making static corrections (Fuji et al., 2010, PEPI) were also necessary. Finally, methods for solving the inverse problem to obtain models with appropriate parametrization and methods for confirming the resolution and robustness of the results of the inversion were also required (Konishi et al., EPSL, 2009; Kawai and Geller, JGR, 2010). We have developed the necessary methods for waveform inversion and have applied them to determine 3-D models of S-wave velocity in the lowermost mantle (submitted for publication). We have also conducted waveform inversion for anisotropy (Kawai and Geller, EPSL, 2010) and anelasticity (Fuji et al., PEPI, 2010). In the near future prospects are bright for applying these methods to much larger datasets for obtaining high-resolution 3-D images of larger regions.
On the potential of OFDM enhancements as 5G waveforms
DEFF Research Database (Denmark)
Berardinelli, Gilberto; Pajukoski, Kari; Lähetkangas, Eeva
2014-01-01
Division Multiplexing (OFDM) and its recently proposed enhancements as 5G waveforms, mainly focusing on their capability to cope with our requirements. Significant focus is given to the novel zero-tail paradigm, which allows boosting the OFDM flexibility while circumventing demerits such as poor spectral...
A nonlinear approach of elastic reflection waveform inversion
Guo, Qiang
2016-09-06
Elastic full waveform inversion (EFWI) embodies the original intention of waveform inversion at its inception as it is a better representation of the mostly solid Earth. However, compared with the acoustic P-wave assumption, EFWI for P- and S-wave velocities using multi-component data admitted mixed results. Full waveform inversion (FWI) is a highly nonlinear problem and this nonlinearity only increases under the elastic assumption. Reflection waveform inversion (RWI) can mitigate the nonlinearity by relying on transmissions from reflections focused on inverting low wavenumber components of the model. In our elastic endeavor, we split the P- and S-wave velocities into low wavenumber and perturbation components and propose a nonlinear approach to invert for both of them. The new optimization problem is built on an objective function that depends on both background and perturbation models. We utilize an equivalent stress source based on the model perturbation to generate reflection instead of demigrating from an image, which is applied in conventional RWI. Application on a slice of an ocean-bottom data shows that our method can efficiently update the low wavenumber parts of the model, but more so, obtain perturbations that can be added to the low wavenumbers for a high resolution output.
Waveform Diversity and Design for Interoperating Radar Systems
2013-01-01
University Di Pisa Department Di Ingegneria Dell Informazione Elettronica, Informatica , Telecomunicazioni Via Girolamo Caruso 16 Pisa, Italy 56122...NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) University Di Pisa Department Di Ingegneria Dell Informazione Elettronica, Informatica ...DIPARTIMENTO DI INGEGNERIA DELL’INFORMAZIONE ELETTRONICA, INFORMATICA , TELECOMUNICAZIONI WAVEFORM DIVERSITY AND DESIGN FOR INTEROPERATING
Implementation and Testing of the Protected Tactical Waveform (PTW)
2015-10-12
ECU ) Integration In a deployed system, the PTS terminal modem design partitions all critical security functionality into an NSA- certified ECU . A...demonstrations, and risk- reduction demonstrations for a terminal End Cryptographic Unit ( ECU ) prototype. Index Terms—Satellite communications...Waveform (PTW), which provides specifications for baseband framing, modulation and coding, dynamic link adaptation protocols, and security features for
Multisource waveform inversion of marine streamer data using normalized wavefield
Choi, Yun Seok
2013-09-01
Multisource full-waveform inversion based on the L1- and L2-norm objective functions cannot be applied to marine streamer data because it does not take into account the unmatched acquisition geometries between the observed and modeled data. To apply multisource full-waveform inversion to marine streamer data, we construct the L1- and L2-norm objective functions using the normalized wavefield. The new residual seismograms obtained from the L1- and L2-norms using the normalized wavefield mitigate the problem of unmatched acquisition geometries, which enables multisource full-waveform inversion to work with marine streamer data. In the new approaches using the normalized wavefield, we used the back-propagation algorithm based on the adjoint-state technique to efficiently calculate the gradients of the objective functions. Numerical examples showed that multisource full-waveform inversion using the normalized wavefield yields much better convergence for marine streamer data than conventional approaches. © 2013 Society of Exploration Geophysicists.
Energy Technology Data Exchange (ETDEWEB)
Moon, Joo Hyun; Park, Moon Soo; Lee, Un Jang; Song, Jae Hyuk; Kim, Byeong Soo; Kim, Chong Uk [Seoul National Univ., Seoul (Korea, Republic of)
2003-01-15
To reduce Occupational Radiation Dose (ORD) effectively and enhance the radiological safety, the comprehensive assessment of the experiences to reduce ORD should be made by regulatory body as well as utilities. Hence, the objective of this study is to assess the experiences for reducing ORD from the regulatory viewpoint. With the research objective, the followings are performed in this research; analysis of occupational dose trends at domestic and foreign NPPs, identification of the effective technologies for reducing ORD, examination of the effects of the technologies for reducing ORD, derivation of the regulatory means for implementing he research results. From this study, the regulatory means for effective reduction of ORD are derived. Hence, the results can be utilized as a basic materials for ALARA requirements.
The effect of placebo adherence on reducing cardiovascular mortality: a meta-analysis.
Yue, Zhao; Cai, Cheng; Ai-Fang, Yang; Feng-Min, Tang; Li, Chen; Bin, Wang
2014-03-01
We aim to demonstrate the effect of placebo adherence on reducing CV mortality. Good adherence, whether to drug or placebo treatment, is associated with lower CV mortality. However, current evidence for the positive effect of placebo adherence on reducing CV mortality is relatively weak. We conducted a fixed-effect meta-analysis of eight randomized clinical trials to evaluate the effect of placebo adherence on reducing CV mortality. We made a comparison between good placebo adherence and poor drug adherence. Compared with poor adherence to drug treatment, good adherence to placebo treatment was associated with lower CV mortality (OR = 0.68, 95% CI 0.60-0.77). Good adherence to placebo has a positive effect on reducing CV mortality. The effect of adherence on reducing CV mortality may be independent of the drug effect.
National Research Council Canada - National Science Library
ZHAO Quanhua; LI Hongying; LI Yu
2015-01-01
.... Therefore, waveform decomposition is the key to full waveform LiDAR data processing. However, in waveform decomposition, determining the number of the components is a focus and difficult problem...
Manoharan, Ganesh; Evans, Noel; Allen, Desmond; Anderson, John; Adgey, Jennifer
2004-04-06
The passive implantable atrial defibrillator (PIAD) (with no battery or discharging capacitor and powered transcutaneously by radio-frequency energy) delivering a novel monophasic low-tilt waveform is more efficacious than the standard monophasic waveform at atrial defibrillation. Standard biphasic (STB) waveforms, however, are more efficacious and safer than monophasic waveforms. This study compared the efficacy and safety of the PIAD waveform with biphasic waveforms. Sustained atrial fibrillation (AF) was induced by rapid atrial pacing. Cardioversion was attempted via 2 atrial defibrillation leads. The efficacy of the PIAD was compared with 3 biphasic waveforms (standard, single rounded, and double rounded) at varying voltage settings in 10 pigs. After a synchronized shock, hemodynamic changes between the PIAD, standard biphasic, and monophasic waveforms were compared at 1.5 and 3.0 J in 12 pigs. Myocardial injury (biochemical and histological) after ten 5-J PIAD shocks was compared with a no-shock group in 14 pigs. The PIAD 100-V setting was significantly more efficacious than the STB (100/-50 V: 100% [1.88+/-0.02 J] versus 90% [0.89+/-0.0 J]; P=0.025). No arrhythmic, hemodynamic, or myocardial injury was observed with the PIAD waveform. Defibrillation with the PIAD is more efficacious than with the STB waveform and appears safe. This device could provide a more effective option for cardioversion.
VG2 URA PWS RAW EXPERIMENT WAVEFORM 60MS V1.0
National Aeronautics and Space Administration — This data set consists of electric field waveform samples from the Voyager 2 Plasma Wave Receiver waveform receiver obtained during the Uranus encounter. The...
GLAS/ICESat L1B Global Waveform-based Range Corrections Data V034
National Aeronautics and Space Administration — The level 1B waveform parameterization data will contain waveform-based range corrections and surface characteristics at the full 40 per second resolution. Data...
IceBridge LVIS L1B Geolocated Return Energy Waveforms V002
National Aeronautics and Space Administration — The IceBridge LVIS L1B Geolocated Return Energy Waveforms (ILVIS1B) data set contains Greenland and Antarctica laser altimetry return energy waveform measurements...
VG2 NEP PWS RAW EXPERIMENT WAVEFORM 60MS V1.0
National Aeronautics and Space Administration — This data set consists of electric field waveform samples from the Voyager 2 Plasma Wave Receiver waveform receiver obtained during the Neptune encounter. The...
Huang, Jian; Walcott, Gregory P; Ruse, Richard B; Bohanan, Scott J; Killingsworth, Cheryl R; Ideker, Raymond E
2012-09-11
We tested the hypothesis that the shape of the shock waveform affects not only the defibrillation threshold but also the amount of cardiac damage. Defibrillation thresholds were determined for 11 waveforms-3 ascending-ramp waveforms, 3 descending-ramp waveforms, 3 rectilinear first-phase biphasic waveforms, a Gurvich waveform, and a truncated exponential biphasic waveform-in 6 pigs with electrodes in the right ventricular apex and superior vena cava. The ascending, descending, and rectilinear waveforms had 4-, 8-, and 16-millisecond first phases and a 3.5-millisecond rectilinear second phase that was half the voltage of the first phase. The exponential biphasic waveform had a 60% first-phase and a 50% second-phase tilt. In a second study, we attempted to defibrillate after 10 seconds of ventricular fibrillation with a single ≈30-J shock (6 pigs successfully defibrillated with 8-millisecond ascending, 8-millisecond rectilinear, and truncated exponential biphasic waveforms). Troponin I blood levels were determined before and 2 to 10 hours after the shock. The lowest-energy defibrillation threshold was for the 8-milliseconds ascending ramp (14.6±7.3 J [mean±SD]), which was significantly less than for the truncated exponential (19.6±6.3 J). Six hours after shock, troponin I was significantly less for the ascending-ramp waveform (0.80±0.54 ng/mL) than for the truncated exponential (1.92±0.47 ng/mL) or the rectilinear waveform (1.17±0.45 ng/mL). The ascending ramp has a significantly lower defibrillation threshold and at ≈30 J causes 58% less troponin I release than the truncated exponential biphasic shock. Therefore, the shock waveform affects both the defibrillation threshold and the amount of cardiac damage.
Bai, Guang-Fu; Hu, Lin; Jiang, Yang; Tian, Jing; Zi, Yue-Jiao; Wu, Ting-Wei; Huang, Feng-Qin
2017-08-01
In this paper, a photonic microwave waveform generator based on a dual-parallel Mach-Zehnder modulator is proposed and experimentally demonstrated. In this reported scheme, only one radio frequency signal is used to drive the dual-parallel Mach-Zehnder modulator. Meanwhile, dispersive elements or filters are not required in the proposed scheme, which make the scheme simpler and more stable. In this way, six variables can be adjusted. Through the different combinations of these variables, basic waveforms with full duty and small duty cycle can be generated. Tunability of the generator can be achieved by adjusting the frequency of the RF signal and the optical carrier. The corresponding theoretical analysis and simulation have been conducted. With guidance of theory and simulation, proof-of-concept experiments are carried out. The basic waveforms, including Gaussian, saw-up, and saw-down waveforms, with full duty and small duty cycle are generated at the repetition rate of 2 GHz. The theoretical and simulation results agree with the experimental results very well.
Test Waveform Applications for JPL STRS Operating Environment
Lux, James P.; Peters, Kenneth J.; Taylor, Gregory H.; Lang, Minh; Stern, Ryan A.; Duncan, Courtney B.
2013-01-01
This software demonstrates use of the JPL Space Telecommunications Radio System (STRS) Operating Environment (OE), tests APIs (application programming interfaces) presented by JPL STRS OE, and allows for basic testing of the underlying hardware platform. This software uses the JPL STRS Operating Environment ["JPL Space Tele com - munications Rad io System Operating Environment,"(NPO-4776) NASA Tech Briefs, commercial edition, Vol. 37, No. 1 (January 2013), p. 47] to interact with the JPL-SDR Software Defined Radio developed for the CoNNeCT (COmmunications, Navigation, and Networking rEconfigurable Testbed) Project as part of the SCaN Testbed installed on the International Space Station (ISS). These are the first applications that are compliant with the new NASA STRS Architecture Standard. Several example waveform applications are provided to demonstrate use of the JPL STRS OE for the JPL-SDR platform used for the CoNNeCT Project. The waveforms provide a simple digitizer and playback capability for the SBand RF slice, and a simple digitizer for the GPS slice [CoNNeCT Global Positioning System RF Module, (NPO-47764) NASA Tech Briefs, commercial edition, Vol. 36, No. 3 (March 2012), p. 36]. These waveforms may be used for hardware test, as well as for on-orbit or laboratory checkout. Additional example waveforms implement SpaceWire and timer modules, which can be used for time transfer and demonstration of communication between the two Xilinx FPGAs in the JPLSDR. The waveforms are also compatible with ground-based use of the JPL STRS OE on radio breadboards and Linux.
Guilhem, A.; Dreger, D. S.; Hutchings, L. J.; Johnson, L.
2012-12-01
We investigate moment tensor solutions and their uncertainties for magnitude (M) ~3 earthquakes located in the northwest Geysers geothermal field, California. We are exploiting an unusual opportunity where data for M~3 events have been recorded by three different networks and have moment tensor solutions calculated by three different methods. We solve for both deviatoric and full moment tensor solutions. The data sets include local short-period instruments (4.5 Hz) of the 30 stations of the Lawrence Berkeley National Laboratory (LBNL), with which we obtain waveform inversion solutions at relatively high frequencies (i.e., up to 2.5 Hz), and regionally distributed broadband stations operated by the Berkeley Seismological Laboratory (BSL), with which are used to provide waveform inversion solutions with data filtered at longer periods (i.e., > 10 sec). We also utilize the LBNL data to obtain moment tensor solutions by fitting the P-wave first motions. The USGS, LBNL, and BSL obtain different event locations, utilize different velocity models, and analyze different frequency bands and wave types (i.e., body waves for LBNL method and primarily surface waves for the BSL analysis). Preliminary results indicate that the BSL and LBNL waveform modeling analyses give similar results in terms of nodal plane characteristics, moment magnitude, and moment tensor decomposition. Analysis of the P-wave first motions recorded by LBNL stations can illuminate complexities in the source processes when compared to waveform moment tensor solutions. We discuss uncertainties in the source inversions that use broadband and/or short-period waveform modeling, and in the source inversions from first motions only. We also combine the different datasets and compare their individual importance as they can help illustrate the complex source processes happening in the Geysers. This study introduces the possibility to interpret the seismic sources as complex processes in which both shear and tensile
Full-waveform inversion of GPR data for civil engineering applications
van der Kruk, Jan; Kalogeropoulos, Alexis; Hugenschmidt, Johannes; Klotzsche, Anja; Busch, Sebastian; Vereecken, Harry
2014-05-01
content increasing frequency-dependent conductivity values were obtained. The off-ground full-waveform inversion was extended to invert for positive and negative gradients in conductivity and the conductivity gradient direction could be correctly identified. Experimental specimen containing gradients were generated by exposing a concrete slab to controlled wetting-drying cycles using a saline solution. Full-waveform inversion of the measured data correctly identified the conductivity gradient direction which was confirmed by destructive analysis. On-ground CMP GPR data measured over a concrete layer overlying a metal plate show interfering multiple reflections, which indicates that the structure acts as a waveguide. Calculation of the phase-velocity spectrum shows the presence of several higher order modes. Whereas the dispersion inversion returns the thickness and layer height, the full-waveform inversion was also able to estimate quantitative conductivity values. This abstract is a contribution to COST Action TU1208
Sets of Waveform and Mismatched Filter Pairs for Clutter Suppression in Marine Radar Application
I.V. Koshevyy; Victoria Popova
2017-01-01
Sets of waveform and mismatched filter pairs are used. On the contrary with Golays matched waveform filter pair the mismatched waveform filter pair does exist for all N (number pulses in waveform). Using corresponding shapes of filter good Doppler tolerance may be provided. This property together with a good range side-lobs level suppression makes it’s attractable for use in marine radar.
Joint Filter and Waveform Design for Radar STAP in Signal Dependent Interference
Setlur, Pawan; Rangaswamy, Muralidhar
2015-01-01
Waveform design is a pivotal component of the fully adaptive radar construct. In this paper we consider waveform design for radar space time adaptive processing (STAP), accounting for the waveform dependence of the clutter correlation matrix. Due to this dependence, in general, the joint problem of receiver filter optimization and radar waveform design becomes an intractable, non-convex optimization problem, Nevertheless, it is however shown to be individually convex either in the filter or i...
Sánchez-Caballero, S.; Sellés, M. A.; Pla, R.; Seguí, J.
2012-04-01
The aim of this paper is to introduce a method to reduce the weight in structures which are subjected to multiple restrictions like deformation, max allowable stress, natural frequency, etc…. The method is shown through the analysis of an aluminum bracket, whose maximum stress and deformation is well defined. The analysis is done using the Structural and Design of Experiments modules of Ansys Workbench v12.1. As result of the method a weight reduction of 50,2% is achieved.
Efficacy of Acupuncture in Reducing Preoperative Anxiety: A Meta-Analysis
Hyojeong Bae; Hyunsu Bae; Byung-Il Min; Seunghun Cho
2014-01-01
Background. Acupuncture has been shown to reduce preoperative anxiety in several previous randomized controlled trials (RCTs). In order to assess the preoperative anxiolytic efficacy of acupuncture therapy, this study conducted a meta-analysis of an array of appropriate studies. Methods. Four electronic databases (MEDLINE, EMBASE, CENTRAL, and CINAHL) were searched up to February 2014. In the meta-analysis data were included from RCT studies in which groups receiving preoperative acupuncture ...
A new optimization approach for source-encoding full-waveform inversion
Moghaddam, P.P.; Keers, H.; Herrmann, F.J.; Mulder, W.A.
2013-01-01
Waveform inversion is the method of choice for determining a highly heterogeneous subsurface structure. However, conventional waveform inversion requires that the wavefield for each source is computed separately. This makes it very expensive for realistic 3D seismic surveys. Source-encoding waveform
2014-11-01
Predicting Electrocardiogram and Arterial Blood Pressure Waveforms with Different Echo State Network Architectures Allan Fong, MS1,3, Ranjeev...the medical staff in Intensive Care Units. The ability to predict electrocardiogram and arterial blood pressure waveforms can potentially help the...type of neural network for mining, understanding, and predicting electrocardiogram and arterial blood pressure waveforms. Several network
On the potential of various approaches in load analysis to reduce the frequency of sports injuries
Nigg, Benno M.; Bobbert, Maarten
1990-01-01
the purpose of this paper is to discuss various approaches used in load analysis with special consideration of whether there is some evidence that these approaches have actually contributed to a reduction of sport injuries and whether these approaches have the theoretical potential to reduce the
Online air analysis of reduced sulfur compounds at a swine facility
Reduced sulfur compounds are emitted from waste management handling and can be important in odor production and atmospheric chemistry. Data on the emissions of these compounds have been obtained using off-line sampling and analysis methods, but on-line methods providing information on temporal chang...
Full waveform inversion based on scattering angle enrichment with application to real dataset
Wu, Zedong
2015-08-19
Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI). However, the drawback of the existing RWI methods is inability to utilize diving waves and the extra sensitivity to the migrated image. We propose a combined FWI and RWI optimization problem through dividing the velocity into the background and perturbed components. We optimize both the background and perturbed components, as independent parameters. The new objective function is quadratic with respect to the perturbed component, which will reduce the nonlinearity of the optimization problem. Solving this optimization provides a true amplitude image and utilizes the diving waves to update the velocity of the shallow parts. To insure a proper wavenumber continuation, we use an efficient scattering angle filter to direct the inversion at the early stages to direct energy corresponding to large (smooth velocity) scattering angles to the background velocity update and the small (high wavenumber) scattering angles to the perturbed velocity update. This efficient implementation of the filter is fast and requires less memory than the conventional approach based on extended images. Thus, the new FWI procedure updates the background velocity mainly along the wavepath for both diving and reflected waves in the initial stages. At the same time, it updates the perturbation with mainly reflections (filtering out the diving waves). To demonstrate the capability of this method, we apply it to a real 2D marine dataset.
Heeding the waveform inversion nonlinearity by unwrapping the model and data
Alkhalifah, Tariq Ali
2012-01-01
Unlike traveltime inversion, waveform inversion provides relatively higher-resolution inverted models. This feature, however, comes at the cost of introducing complex nonlinearity to the inversion operator complicating the convergence process. We use unwrapped-phase-based objective functions to reduce such nonlinearity in a domain in which the high-frequency component is given by the traveltime inversion. Such information is packaged in a frequency-dependent attribute (or traveltime) that can be easily manipulated at different frequencies. It unwraps the phase of the wavefield yielding far less nonlinearity in the objective function than those experienced with the conventional misfit objective function, and yet it still holds most of the critical waveform information in its frequency dependency. However, it suffers from nonlinearity introduced by the model (or reflectivity), as events interact with each other (something like cross talk). This stems from the sinusoidal nature of the band-limited reflectivity model. Unwrapping the phase for such a model can mitigate this nonlinearity as well. Specifically, a simple modification to the inverted domain (or model), can reduce the effect of the model-induced nonlinearity and, thus, make the inversion more convergent. Simple examples are used to highlight such features.
Sick, Benjamin; Joswig, Manfred
2017-03-01
Events from induced seismicity suffer from low signal-to-noise ratios and noise spikes due to the industrial setting. Low magnitude thresholds are needed for traffic light warning systems. Conventional automatic location methods rely on independent picking of first arrivals from seismic wave onsets at recordings of single stations. Picking is done separately and without feedback from the actual location algorithm. If the recording network is small or only few phases can be associated, single wrong associations can lead to large errors in hypocentre locations and magnitude. Event location by source scanning which was established in the last two decades can provide more robust results. This study investigates how source-scanning can be extended and improved by integrating information from seismic arrays, that is, waveform stacking and Fisher ratio. These array methods rely on the coherency of the raw filtered waveforms while traditional source scanning uses a characteristic function to obtain coherency from otherwise incoherent waveforms between distant stations. Short-term/long-term average (STA/LTA) serves as the characteristic function and single station vertical-component traces for P-phases and radial and transverse components for S-phases are used. For array stations, the STA/LTA of the stacked vertical seismogram which is furthermore weighted by the STA/LTA of the Fisher ratio, dependent on backazimuth and slowness, is utilized for P-phases. The new method is tested on two diverse data sets from induced seismicity monitoring. In the chosen examples, the extension by array-processing techniques can reduce mean hypocentre errors up to a factor of 2.9, resolve ambiguities and further restrain the location.
Impacts of oil spills on altimeter waveforms and radar backscatter cross section
Cheng, Yongcun; Tournadre, Jean; Li, Xiaofeng; Xu, Qing; Chapron, Bertrand
2017-05-01
Ocean surface films can damp short capillary-gravity waves, reduce the surface mean square slope, and induce "sigma0 blooms" in satellite altimeter data. No study has ascertained the effect of such film on altimeter measurements due to lack of film data. The availability of Environmental Response Management Application (ERMA) oil cover, daily oil spill extent, and thickness data acquired during the Deepwater Horizon (DWH) oil spill accident provides a unique opportunity to evaluate the impact of surface film on altimeter data. In this study, the Jason-1/2 passes nearest to the DWH platform are analyzed to understand the waveform distortion caused by the spill as well as the variation of σ0 as a function of oil thickness, wind speed, and radar band. Jason-1/2 Ku-band σ0 increased by 10 dB at low wind speed (<3 m s-1) in the oil-covered area. The mean σ0 in Ku and C bands increased by 1.0-3.5 dB for thick oil and 0.9-2.9 dB for thin oil while the waveforms are strongly distorted. As the wind increases up to 6 m s-1, the mean σ0 bloom and waveform distortion in both Ku and C bands weakened for both thick and thin oil. When wind exceeds 6 m s-1, only does the σ0 in Ku band slightly increase by 0.2-0.5 dB for thick oil. The study shows that high-resolution altimeter data can certainly help better evaluate the thickness of oil spill, particularly at low wind speeds.
Directory of Open Access Journals (Sweden)
Shilpa Bhandari
2016-01-01
Full Text Available Objectives. This study aims to evaluate perinatal outcomes such as gestational age at delivery and live birth rate in singleton and twin gestation with or without fetal reduction. Method. A retrospective analysis was done on patients which were divided into reduced and unreduced groups on the basis of order of reduction of one or more fetuses between 6 and 13 weeks of gestation. Patients records were studied to note gestational age at delivery/abortion, birth weight, and neonatal outcome. Result. The cohort included a total of 292 patients: 102 singletons and 190 twins. 52 pregnancies were reduced in singleton cohort and 68 were reduced in twin cohort. No statistical difference was observed in live birth rate, gestational age at delivery, and birth weight and significant higher incidence of IUGR was observed in reduced and unreduced twin gestation. In singleton pregnancies however preterm delivery rate increased with fetal reduction. Conclusion. Although reduction does not reduce the live birth rate, it does reduce gestation age of delivery and birth weight of newborn. This effect is more apparent when multiple gestation is reduced to singleton.
Sundermier, A.; Slinkard, M.; Perry, J.; Schaff, D. P.; Young, C. J.; Richards, P. G.
2016-12-01
Waveform correlation techniques have proven effectiveness detecting repeated events from large aftershock sequences; however, application for monitoring a large region over a long time period has yet to be adequately explored. We applied waveform correlation to six years of continuous waveform data at eleven stations spread through Eastern Asia, using automatically generated templates from historical archives going back to the time of station installation, in some cases as far back as 1986. Our study region includes the countries of China, North Korea, South Korea, Mongolia, Nepal, Bhutan, Bangladesh, and parts of Russia, Kazakhstan, Kyrgyzstan, Tajikistan, Afghanistan, Pakistan, India, Myanmar, Thailand, Laos, and Vietnam. We used nine China Digital Network (CD/IC) and two other available stations which had continuous coverage from 2006-2012; this yielded 11 stations which spanned 40 degrees in latitude and 70 degrees in longitude with an average nearest-neighbor distance between stations of 842 km. To declare a detected event, we require coincident correlations at 2 or more stations, so station spacing has a strong effect on our detection threshold. We compare our detection results to the ISC catalog to analyze the effectiveness and challenges associated with applying waveform correlation on a broad regional and multi-year scale. Our best results were obtained in the vicinity of the 2008 Wenchuan aftershock sequence where each station had two other stations within a 1000 km radius. We include analysis of the impact of network geometry, historical template library span and size, and template phase to provide direction for future regional studies using waveform correlation.
Analytic family of post-merger template waveforms
Del Pozzo, Walter; Nagar, Alessandro
2017-06-01
Building on the analytical description of the post-merger (ringdown) waveform of coalescing, nonprecessing, spinning binary black holes introduced by Damour and Nagar [Phys. Rev. D 90, 024054 (2014), 10.1103/PhysRevD.90.024054], we propose an analytic, closed form, time-domain, representation of the ℓ=m =2 gravitational radiation mode emitted after merger. This expression is given as a function of the component masses and dimensionless spins (m1 ,2,χ1 ,2) of the two inspiraling objects, as well as of the mass MBH and (complex) frequency σ1 of the fundamental quasinormal mode of the remnant black hole. Our proposed template is obtained by fitting the post-merger waveform part of several publicly available numerical relativity simulations from the Simulating eXtreme Spacetimes (SXS) catalog and then suitably interpolating over (symmetric) mass ratio and spins. We show that this analytic expression accurately reproduces (˜0.01 rad ) the phasing of the post-merger data of other data sets not used in its construction. This is notably the case of the spin-aligned run SXS:BBH:0305, whose intrinsic parameters are consistent with the 90% credible intervals reported in the parameter-estimation followup of GW150914 by B.P. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016), 10.1103/PhysRevLett.116.241102]. Using SXS waveforms as "experimental" data, we further show that our template could be used on the actual GW150914 data to perform a new measure of the complex frequency of the fundamental quasinormal mode so as to exploit the complete (high signal-to-noise-ratio) post-merger waveform. We assess the usefulness of our proposed template by analyzing, in a realistic setting, SXS full inspiral-merger-ringdown waveforms and constructing posterior probability distribution functions for the central frequency damping time of the first overtone of the fundamental quasinormal mode as well as for the physical parameters of the systems. We also briefly explore the possibility
Venkat, Raghu B.; Sawant, Amit; Suh, Yelin; George, Rohini; Keall, Paul J.
2008-06-01
The aim of this research was to investigate the effectiveness of a novel audio-visual biofeedback respiratory training tool to reduce respiratory irregularity. The audiovisual biofeedback system acquires sample respiratory waveforms of a particular patient and computes a patient-specific waveform to guide the patient's subsequent breathing. Two visual feedback models with different displays and cognitive loads were investigated: a bar model and a wave model. The audio instructions were ascending/descending musical tones played at inhale and exhale respectively to assist in maintaining the breathing period. Free-breathing, bar model and wave model training was performed on ten volunteers for 5 min for three repeat sessions. A total of 90 respiratory waveforms were acquired. It was found that the bar model was superior to free breathing with overall rms displacement variations of 0.10 and 0.16 cm, respectively, and rms period variations of 0.77 and 0.33 s, respectively. The wave model was superior to the bar model and free breathing for all volunteers, with an overall rms displacement of 0.08 cm and rms periods of 0.2 s. The reduction in the displacement and period variations for the bar model compared with free breathing was statistically significant (p = 0.005 and 0.002, respectively); the wave model was significantly better than the bar model (p = 0.006 and 0.005, respectively). Audiovisual biofeedback with a patient-specific guiding waveform significantly reduces variations in breathing. The wave model approach reduces cycle-to-cycle variations in displacement by greater than 50% and variations in period by over 70% compared with free breathing. The planned application of this device is anatomic and functional imaging procedures and radiation therapy delivery.
Energy Technology Data Exchange (ETDEWEB)
Venkat, Raghu B; Sawant, Amit; Suh, Yelin; Keall, Paul J [Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847 (United States); George, Rohini [Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA (United States)], E-mail: Paul.Keall@stanford.edu
2008-06-07
The aim of this research was to investigate the effectiveness of a novel audio-visual biofeedback respiratory training tool to reduce respiratory irregularity. The audiovisual biofeedback system acquires sample respiratory waveforms of a particular patient and computes a patient-specific waveform to guide the patient's subsequent breathing. Two visual feedback models with different displays and cognitive loads were investigated: a bar model and a wave model. The audio instructions were ascending/descending musical tones played at inhale and exhale respectively to assist in maintaining the breathing period. Free-breathing, bar model and wave model training was performed on ten volunteers for 5 min for three repeat sessions. A total of 90 respiratory waveforms were acquired. It was found that the bar model was superior to free breathing with overall rms displacement variations of 0.10 and 0.16 cm, respectively, and rms period variations of 0.77 and 0.33 s, respectively. The wave model was superior to the bar model and free breathing for all volunteers, with an overall rms displacement of 0.08 cm and rms periods of 0.2 s. The reduction in the displacement and period variations for the bar model compared with free breathing was statistically significant (p = 0.005 and 0.002, respectively); the wave model was significantly better than the bar model (p = 0.006 and 0.005, respectively). Audiovisual biofeedback with a patient-specific guiding waveform significantly reduces variations in breathing. The wave model approach reduces cycle-to-cycle variations in displacement by greater than 50% and variations in period by over 70% compared with free breathing. The planned application of this device is anatomic and functional imaging procedures and radiation therapy delivery. (note)
Initiation of ventricular contraction as reflected in the aortic pressure waveform.
van Houwelingen, Marc J; Merkus, Daphne; te Lintel Hekkert, Maaike; van Dijk, Geert; Hoeks, Arnold P G; Duncker, Dirk J
2012-04-01
Prior to aortic valve opening, aortic pressure is perturbed by ventricular contraction. The onset of this pressure perturbation coincides with the onset of the left ventricular (LV) isovolumic contraction, and hence will be referred to as the start of the arterially detected isovolumic contraction (AIC(start)). In the present study we test the hypothesis that the pressure perturbation indeed has a cardiac origin. In ten Yorkshire-Landrace swine, waveform intensity analysis demonstrated that AIC(start) was followed by a positive intensity wave (0.3 × 10(5) ± 0.3 × 10(5) W (m(2) s(2))(-1)). Timing analysis of LV and aortic pressure waveform showed that AIC(start) was preceded by a LV pressure perturbation (3.8 ± 1.8 ms, p < 0.001). These novel cardiac timing and aortic wave intensity findings reveal the cardiac origin of the pressure perturbation. In 15 Yorkshire-Landrace swine, myocardial motion analysis showed a significantly higher rate of segment shortening during the first part of the LV pressure perturbation. Therefore, both the LV and aortic pressure perturbation are most likely caused by the early phase of myocardial contraction, which also causes mitral valve closure. Consequently, AIC(start) is useful in the determination of the isovolumic contraction period, a well-known marker to quantify cardiac dysfunction. © 2012 Institute of Physics and Engineering in Medicine
Molecular analysis of the metabolic rates of discrete subsurface populations of sulfate reducers
Energy Technology Data Exchange (ETDEWEB)
Miletto, M.; Williams, K.H.; N' Guessan, A.L.; Lovley, D.R.
2011-04-01
Elucidating the in situ metabolic activity of phylogenetically diverse populations of sulfate-reducing microorganisms that populate anoxic sedimentary environments is key to understanding subsurface ecology. Previous pure culture studies have demonstrated that transcript abundance of dissimilatory (bi)sulfite reductase genes is correlated with the sulfate reducing activity of individual cells. To evaluate whether expression of these genes was diagnostic for subsurface communities, dissimilatory (bi)sulfite reductase gene transcript abundance in phylogenetically distinct sulfate-reducing populations was quantified during a field experiment in which acetate was added to uranium-contaminated groundwater. Analysis of dsrAB sequences prior to the addition of acetate indicated that Desulfobacteraceae, Desulfobulbaceae, and Syntrophaceae-related sulfate reducers were the most abundant. Quantifying dsrB transcripts of the individual populations suggested that Desulfobacteraceae initially had higher dsrB transcripts per cell than Desulfobulbaceae or Syntrophaceae populations, and that the activity of Desulfobacteraceae increased further when the metabolism of dissimilatory metal reducers competing for the added acetate declined. In contrast, dsrB transcript abundance in Desulfobulbaceae and Syntrophaceae remained relatively constant, suggesting a lack of stimulation by added acetate. The indication of higher sulfate-reducing activity in the Desulfobacteraceae was consistent with the finding that Desulfobacteraceae became the predominant component of the sulfate-reducing community. Discontinuing acetate additions resulted in a decline in dsrB transcript abundance in the Desulfobacteraceae. These results suggest that monitoring transcripts of dissimilatory (bi)sulfite reductase genes in distinct populations of sulfate reducers can provide insight into the relative rates of metabolism of different components of the sulfate-reducing community and their ability to respond to
Directory of Open Access Journals (Sweden)
Sobhani Narges
2008-11-01
Full Text Available Abstract Background Doppler flow velocity waveform analysis of fetal vessels is one of the main methods for evaluating fetus health before labor. Doppler waves of middle cerebral artery (MCA can predict most of the at risk fetuses in high risk pregnancies. In this study, we tried to obtain normal values and their nomograms during pregnancy for Doppler flow velocity indices of MCA in 20 – 40 weeks of normal pregnancies in Iranian population and compare their pattern with other countries' nomograms. Methods During present descriptive cross-sectional study, 1037 normal pregnant women with 20th–40th week gestational age were underwent MCA Doppler study. All cases were studied by gray scale ultrasonography initially and Doppler of MCA afterward. Resistive Index (RI, Pulsative Index (PI, Systolic/Diastolic ratio (S/D ratio, and Peak Systolic Velocity (PSV values of MCA were determined for all of the subjects. Results Results of present study showed that RI, PI, S/D ratio values of MCA decreased with parabolic pattern and PSV value increased with simple pattern, as gestational age progressed. These changes were statistically significant (P = 0.000 for all of indices and more characteristic during late weeks of pregnancy. Conclusion Values of RI, PI and S/D ratio indices reduced toward the end of pregnancy, but PSV increased. Despite the trivial difference, nomograms of various Doppler indices in present study have similar pattern with other studies.
NLAS: Improving the Accessibility and Utility of Lidar Waveform Data in the Earth Sciences
Crosby, C. J.; Blair, J. B.; Carabajal, C. C.; Haran, T. M.; Hofton, M. A.; Khalsa, S. S.; McWhirter, J.; Meertens, C. M.; Nandigam, V.
2011-12-01
NLAS services and provides integrated access to the GSFC and NSIDC-hosted datasets along with OpenTopography hosted data. In addition to providing access to LiDAR point data OpenTopography provides on-demand generation of user-specified derived topographic data products. Data distilled from the 15 standard ICESat products will be made available through NLAS. The LVIS waveform vector is a unique method for storing lidar waveforms that allows end-users to perform their own waveform analysis at full accuracy. An expanded version of this LVIS data product will be available through NLAS. NLAS is also developing a unified lidar data content and encoding convention to enable straightforward and unambiguous interpretation of waveform data (single and multiple waveforms per footprint) with the aim of spurring the broader adoption of both space and airborne lidar waveform data and increase opportunities for joint analysis of such data sets.
TOTAL HARMONIC DISTORTION ANALYSIS OF MATRIX CONVERTER
K. Kandan; Senthilkumar,K.; Dhivya, K.
2016-01-01
This paper deals with the validation and design analysis of Matrix converter for variable frequency using mathematical equations. The analysis was done using Venturini modulation algorithm. The PI controller is used for Matrix converter to reduce Total Harmonic Distortion (THD) in the output current. The comparative study is done for open loop and closed loop PI compensation in MATLAB-Simulink. Furthermore, the output waveforms are produced with significant reduction in the Total Harmonic Dis...
Lamb, Frederick K.; Miller, M. Coleman
2014-08-01
We have developed new, more sophisticated, and much faster Bayesian analysis methods that enable us to estimate the masses and radii of rapidly rotating, oblate neutron stars using the energy-resolved waveforms of their X-ray burst oscillations and to determine the uncertainties in these mass and radius estimates. We first generate the energy-resolved burst oscillation waveforms that would be produced by a hot spot on various rapidly rotating, oblate stars, using the oblate-star Schwarzschild-spacetime (OS) approximation. In generating these synthetic data, we assume that 1 million counts have been collected from the hot spot and that the background is 9 million counts. This produces a realistic modulation amplitude and a total number of counts comparable to the number that could be obtained by a future space mission such as the proposed LOFT or AXTAR missions or the accepted NICER mission by combining data from many bursts from a given star. We then compute the joint posterior distribution of the mass M and radius R in standard models, for each synthetic waveform, and use these posterior distributions to determine the 1-, 2-, and 3-sigma confidence regions in the M-R plane for each synthetic waveform and model. We report here the confidence regions obtained when Schwarzschild+Doppler (S+D) and OS waveform models are used, including results obtained when the properties of the star used to generate the synthetic waveform data differ from the properties of the star used in modeling the waveform. These results are based on research supported by NSF grant AST0709015 at the University of Illinois and NSF grant AST0708424 at the University of Maryland.
Digitally Synthesized Alternative Current Sinusoidal Waveform for Resistive Sensor Measurements
Directory of Open Access Journals (Sweden)
K. N. Trachanidis
2011-01-01
Full Text Available This paper presents a circuit that has the ability to provide a sinusoidal current waveform. The produced waveform is alternative,so it takes positive and negative values. This circuit comprises a microcontroller, a DAC with current outputand a fast electronic switch. The sine wave samples are stored in the microcontroller’s data memory and are applied to theDAC’s digital 8-bit input. The complementary output currents are connected alternatively through the electronic switch tothe ground. At pre-calculated timing the microcontroller changes the polarity of the switch, allowing the DAC’s output, asalternative current, to flow through the resistive sensor (load, ending through the switch to the ground. Another microcontrolleracting as data acquisition chip, at the positive peaks is sampling the voltage across the load. These measurements aretransferred through the serial port to a PC, where the resistance is calculated and presented on screen.
Laser-generated focused ultrasound for arbitrary waveforms
Chan, Weiwei; Hies, Thomas; Ohl, Claus-Dieter
2016-10-01
Transducers for laser generated focused ultrasound can achieve photoacoustic waves with several hundred bars positive pressure in water. Previous designs employed concave glass substrates decorated with catalytically grown carbon nanotubes. Here, we show that arbitrarily shaped surfaces made of polymers and printed with 3d printers allow the generation of waveforms with complex temporal and spatial shape. We first present three different polymer materials together with a simplified deposition technique. This is achieved by painting layers of carbon-nanotube powder and polydimethylsiloxane. Together with a clear resin (Formlabs Photopolymer Clear Resin), pressure amplitudes of 300 bar peak positive were obtained. With the flexibility of polymer substrates, complex waveforms can be generated. This is demonstrated with a stepped surface which launches two waves separated by 0.8 μs. Detailed pressure measurements are supported with shadowgraphy images and simulations of the wave.
Primary study for detection of arterial blood pressure waveform components.
Paradkar, Neeraj; Chowdhury, Shubhajit Roy
2015-01-01
The paper presents a technique to detect significant systolic peaks, the percussion (P) and tidal peak (T) and diastolic peak (D) from the arterial blood pressure (ABP) waveform. The technique is aimed at robust detection even in presence of significant noise. Singular Value Decomposition (SVD) based dominant period extraction of the ABP waveform followed by wavelet transform and local peak detection is applied to detect the points of interest. MIMIC-II ABP databse serves as a training dataset to select SVD and wavelet transform parameters and CSL Benchmark database is used to analyze the technique. Salient systolic peak detection for the CSL dataset was performed with positive predictive value and sensitivity figures of 98.48% and 99.24% respectively.
Image-domain full waveform inversion: Field data example
Zhang, Sanzong
2014-08-05
The main difficulty with the data-domain full waveform inversion (FWI) is that it tends to get stuck in the local minima associated with the waveform misfit function. This is the result of cycle skipping which degrades the low-wavenumber update in the absence of low-frequencies and long-offset data. An image-domain objective function is defined as the normed difference between the predicted and observed common image gathers (CIGs) in the subsurface offset domain. This new objective function is not constrained by cycle skipping at the far subsurface offsets. To test the effectiveness of this method, we apply it to marine data recorded in the Gulf of Mexico. Results show that image-domain FWI is less sensitive to the initial model and the absence of low-frequency data compared with conventional FWI. The liability, however, is that it is almost an order of magnitude more expensive than standard FWI.
A high voltage asymmetric waveform generator for FAIMS.
Canterbury, Jesse D; Gladden, James; Buck, Lon; Olund, Roy; MacCoss, Michael J
2010-07-01
High field asymmetric waveform ion mobility spectrometry (FAIMS) has been used increasingly in recent years as an additional method of ion separation and selection before mass spectrometry. The FAIMS electrodes are relatively simple to design and fabricate for laboratories wishing to implement their own FAIMS designs. However, construction of the electronics apparatus needed to produce the required high magnitude asymmetric electric field oscillating at a frequency of several hundred kilohertz is not trivial. Here we present an entirely custom-built electronics setup capable of supplying the required waveforms and voltages. The apparatus is relatively simple and inexpensive to implement. We also present data acquired on this system demonstrating the use of FAIMS as a gas-phase ion filter interface to an ion trap mass spectrometer. Copyright 2010 American Society for Mass Spectrometry. Published by Elsevier Inc. All rights reserved.
Experimental evaluation of acceleration waveform replication on electrohydraulic shaking tables
Directory of Open Access Journals (Sweden)
Gang Shen
2016-10-01
Full Text Available An electrohydraulic shaking table is an essential experimental facility in many industrial applications to real-time simulate actual vibration situations including structural vibration and earthquake. However, there is still a challenging area for its acceleration waveform replication because acceleration output responses of the electrohydraulic shaking table would not be as intended in magnitude and phase of an acceleration closed-loop system due to inherent hydraulic nonlinear dynamics of electrohydraulic servo systems. Thus, how to accurately and coordinately control parallel hydraulic actuators of the electrohydraulic shaking table is a critical issue; so, many control techniques have been developed to address the issue. Some currently used key techniques in this field are reviewed in the article, which are the objectives of academic investigations and industrial applications. The article reviews some new control algorithms for the electrohydraulic shaking table to obtain high-fidelity acceleration waveform replication accuracy.
Zhang, Hong-Xuan; Goutsias, John
2011-03-21
Sensitivity analysis is a valuable task for assessing the effects of biological variability on cellular behavior. Available techniques require knowledge of nominal parameter values, which cannot be determined accurately due to experimental uncertainty typical to problems of systems biology. As a consequence, the practical use of existing sensitivity analysis techniques may be seriously hampered by the effects of unpredictable experimental variability. To address this problem, we propose here a probabilistic approach to sensitivity analysis of biochemical reaction systems that explicitly models experimental variability and effectively reduces the impact of this type of uncertainty on the results. The proposed approach employs a recently introduced variance-based method to sensitivity analysis of biochemical reaction systems [Zhang et al., J. Chem. Phys. 134, 094101 (2009)] and leads to a technique that can be effectively used to accommodate appreciable levels of experimental variability. We discuss three numerical techniques for evaluating the sensitivity indices associated with the new method, which include Monte Carlo estimation, derivative approximation, and dimensionality reduction based on orthonormal Hermite approximation. By employing a computational model of the epidermal growth factor receptor signaling pathway, we demonstrate that the proposed technique can greatly reduce the effect of experimental variability on variance-based sensitivity analysis results. We expect that, in cases of appreciable experimental variability, the new method can lead to substantial improvements over existing sensitivity analysis techniques.
(DURIP) MIMO Radar Testbed for Waveform Adaptive Sensing Research
2015-06-17
SDR ) testbed. The testbed consists of 14 micro SDR platforms with two transmit and one receive antennas and a standalone SDR with 4 transmit and 4...receive channels multiplexed to 32 x 32 antenna array through a switching matrix. These SDR platforms can adaptively modify both transmit waveforms... SDR ) testbed. The testbed consists of 14 micro SDR platforms with two transmit and one receive antennas and a standalone SDR with 4 transmit and 4
DISECA - A Matlab code for dispersive waveform calculations
Czech Academy of Sciences Publication Activity Database
Gaždová, Renata; Vilhelm, J.
2011-01-01
Roč. 38, č. 4 (2011), s. 526-531 ISSN 0266-352X R&D Projects: GA AV ČR IAA300460705 Institutional research plan: CEZ:AV0Z30460519 Keywords : velocity dispersion * synthetic waveform * seismic method Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.987, year: 2011 http://www.sciencedirect.com/science/article/pii/S0266352X11000425
A synthesis of RLC circuits for arbitrary waveform generation
Chi, Dong Pyo; Kim, Jinsoo
1998-10-01
We consider an electrical network in which the series of resistor, inductor and capacitor are connected in parallel. When the finite measurements of the current are given, we present a method to construct an RLC circuit which generates the current fitting the measurements. This method will be useful to synthesize the voltage (or current) source of an arbitrary waveform which is necessary in the measurement of damage of a semiconductor device caused by an electrostatic discharge.
MURI: Adaptive Waveform Design for Full Spectral Dominance
2011-03-11
bats or dolphins for echo-location, for use in waveform-agile tracking [14]-[16]. We developed a sequential Bayesian algorithm for estimating the...2.4.2 Cognitive Radar for Target Tracking in Multipath Scenarios . . . . . . . . . . . . . . . 10 2.4.3 Sparsity-Based Multi-Target Tracking Using OFDM...jamming. 2.4.2 Cognitive Radar for Target Tracking in Multipath Scenarios Problem Description In [37], we addressed the problem of target tracking in a
Frequency-Dependent Blanking with Digital Linear Chirp Waveform Synthesis
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Andrews, John M. [General Atomics Aeronautical Systems, Inc., San Diego, CA (United States)
2014-07-01
Wideband radar systems, especially those that operate at lower frequencies such as VHF and UHF, are often restricted from transmitting within or across specific frequency bands in order to prevent interference to other spectrum users. Herein we describe techniques for notching the transmitted spectrum of a generated and transmitted radar waveform. The notches are fully programmable as to their location, and techniques are given that control the characteristics of the notches.
Automating the Classification of Field Leakage Current Waveforms
D. Pylarinos; K. Siderakis; Pyrgioti, E.; E. Thalassinakis; I. Vitellas
2011-01-01
Leakage current monitoring is widely employed to investigate the performance of high voltage insulators and the development of surface activity. Field measurements offer an exact view of experienced activity and insulators’ performance, which are strongly correlated to local conditions. The required long term monitoring however, results to the accumulation of vast amounts of data. Therefore, an identification system for the classification of field leakage current waveforms rises as a ne...
Waveform design and diversity for advanced radar systems
Gini, Fulvio
2012-01-01
In recent years, various algorithms for radar signal design, that rely heavily upon complicated processing and/or antenna architectures, have been suggested. These techniques owe their genesis to several factors, including revolutionary technological advances (new flexible waveform generators, high speed signal processing hardware, digital array radar technology, etc.) and the stressing performance requirements, often imposed by defence applications in areas such as airborne early warning and homeland security.Increasingly complex operating scenarios calls for sophisticated algorithms with the
Winkle, R A; Mead, R H; Ruder, M A; Gaudiani, V; Buch, W S; Pless, B; Sweeney, M; Schmidt, P
1989-01-01
The standard implantable defibrillator waveform is a truncated exponential of approximately 6 msec duration. This study compares the defibrillation efficacy of a standard monophasic truncated exponential to a biphasic 12 msec truncated exponential waveform in 21 patients undergoing automatic implantable cardioverter defibrillator (AICD) surgery. For the biphasic waveform, the polarity was reversed and remaining capacitor voltage was attenuated by 75% after 6 msec. Two hundred thirty episodes of VF were induced with 115 "matched pairs" of monophasic and biphasic waveforms of identical initial capacitor voltages given over a range from 70 to 600 V (0.35 to 25.7 joules). The biphasic waveform was superior to the monophasic waveform (p less than 0.006), especially for "low energy" defibrillation. For initial voltages less than 200 V, the percent successful defibrillation was 28% for the monophasic waveform versus 64% for the biphasic waveform and from 200 to 290 V (energies less than 6.4 joules) it was 45% versus 69%. There was no difference in the two waveforms in time to the first QRS complex or in the blood pressure following defibrillation. This study shows that a 12 msec biphasic truncated exponential is superior to a 6 msec monophasic waveform for defibrillation in man, especially at energies less than 6.4 joules. The waveform can be achieved in an implanted device without any increase in capacitor size or in battery energy consumption.
Feng, Shaoqi; Qin, Chuan; Shang, Kuanping; Pathak, Shibnath; Lai, Weicheng; Guan, Binbin; Clements, Matthew; Su, Tiehui; Liu, Guangyao; Lu, Hongbo; Scott, Ryan P; Ben Yoo, S J
2017-04-17
This paper demonstrates rapidly reconfigurable, high-fidelity optical arbitrary waveform generation (OAWG) in a heterogeneous photonic integrated circuit (PIC). The heterogeneous PIC combines advantages of high-speed indium phosphide (InP) modulators and low-loss, high-contrast silicon nitride (Si3N4) arrayed waveguide gratings (AWGs) so that high-fidelity optical waveform syntheses with rapid waveform updates are possible. The generated optical waveforms spanned a 160 GHz spectral bandwidth starting from an optical frequency comb consisting of eight comb lines separated by 20 GHz channel spacing. The Error Vector Magnitude (EVM) values of the generated waveforms were approximately 16.4%. The OAWG module can rapidly and arbitrarily reconfigure waveforms upon every pulse arriving at 2 ns repetition time. The result of this work indicates the feasibility of truly dynamic optical arbitrary waveform generation where the reconfiguration rate or the modulator bandwidth must exceed the channel spacing of the AWG and the optical frequency comb.
Estimation of Tropical Forest Structure Using the Full Waveform Lidar from ICESat
Palace, M. W.; Hagen, S.; Braswell, B. H.; Hunter, M. O.; Ducey, M.
2009-12-01
The Amazon basin contains the world’s largest continuous tropical forest constituting 40% of the remaining area for this ecotype and is made up of heterogeneous canopies and forest communities with unique assemblages of tree species, complex vegetation dynamics and history, and high biodiversity. Forest structural components include canopy geometry and tree architecture, size distributions of trees, and are closely linked with ecosystem functioning. The dynamic processes of growth and disturbance are reflected in the structural components of forest. Large footprint lidar has been used to estimate biomass in tropical and temperate forests, primarily through the correlation with field measured height, basal area, and plot biomass estimates. However, in tall-stature forests height loses much of its correlation with basal area, so the height-biomass curve becomes asymptotic and is associated with greater error at large biomass values. Use of lidar in such an analysis also does not include estimations of other stand level structural properties. We used full lidar waveforms from ICESat GLAS to estimate forest stand structure. We developed a 3D canopy model that uses trunk or crown diameter distributions and allometric equations of associated crown depth and canopy height to generate a synthetic canopy. Using geometric series of tree size distributions, we generated thousands of synthetic vegetation profiles. These synthesized forest canopy profiles were rapidly and efficiently compared with lidar waveforms and matches identified using least squared difference. Using GLAS lidar waveforms, we identified patterns of forest structure across Amazonia. . Landscape level estimates of q-values derived from lidar estimates are similar to estimates of q-values from field based data from a 400 ha area in Tapajos National Forest, approximately q=1.7, with a range of 1.69 to 1.82 per 100 ha plot. Estimates comparing field data collected in areas associated specifically with a GLAS
Arbitrary waveform modulated pulse EPR at 200 GHz
Kaminker, Ilia; Barnes, Ryan; Han, Songi
2017-06-01
We report here on the implementation of arbitrary waveform generation (AWG) capabilities at ∼200 GHz into an Electron Paramagnetic Resonance (EPR) and Dynamic Nuclear Polarization (DNP) instrument platform operating at 7 T. This is achieved with the integration of a 1 GHz, 2 channel, digital to analog converter (DAC) board that enables the generation of coherent arbitrary waveforms at Ku-band frequencies with 1 ns resolution into an existing architecture of a solid state amplifier multiplier chain (AMC). This allows for the generation of arbitrary phase- and amplitude-modulated waveforms at 200 GHz with >150 mW power. We find that the non-linearity of the AMC poses significant difficulties in generating amplitude-modulated pulses at 200 GHz. We demonstrate that in the power-limited regime of ω1 10 MHz) spin manipulation in incoherent (inversion), as well as coherent (echo formation) experiments. Highlights include the improvement by one order of magnitude in inversion bandwidth compared to that of conventional rectangular pulses, as well as a factor of two in improvement in the refocused echo intensity at 200 GHz.
Multibeam synthesis of high-power subcycle field waveforms
Serebryannikov, E. E.; Panchenko, V. Ya.; Zheltikov, A. M.
2017-09-01
We identify physical scenarios whereby high-peak-power subcycle attosecond field waveforms can be synthesized by coherently combining a multibeam high-order harmonic output generated by a laser driver consisting of a pair of few-cycle pulses with different carrier frequencies. With the relative amplitudes, phases, and group delays of these driver pulses carefully adjusted in each of the driver beams toward confining the recollisions of highest-ponderomotive-energy electrons to an extremely short time gate within a fraction of the driver field cycle, the phase-matched multibeam high-harmonic output can be tailored to yield an intense isolated subgigawatt sub-10-attosecond field waveform. As a general tendency, propagation effects are shown to limit the minimum pulse width of the multibeam high-harmonic output. Still, with appropriate optimization of the gas pressure and the beam geometry, ≈10 -as field waveforms can be synthesized at the expense of one to two orders of magnitude of the output radiation energy.
Frequency-domain waveform inversion using the phase derivative
Choi, Yun Seok
2013-09-26
Phase wrapping in the frequency domain or cycle skipping in the time domain is the major cause of the local minima problem in the waveform inversion when the starting model is far from the true model. Since the phase derivative does not suffer from the wrapping effect, its inversion has the potential of providing a robust and reliable inversion result. We propose a new waveform inversion algorithm using the phase derivative in the frequency domain along with the exponential damping term to attenuate reflections. We estimate the phase derivative, or what we refer to as the instantaneous traveltime, by taking the derivative of the Fourier-transformed wavefield with respect to the angular frequency, dividing it by the wavefield itself and taking the imaginary part. The objective function is constructed using the phase derivative and the gradient of the objective function is computed using the back-propagation algorithm. Numerical examples show that our inversion algorithm with a strong damping generates a tomographic result even for a high ‘single’ frequency, which can be a good initial model for full waveform inversion and migration.
Waveform simulation of predominant periods in Osaka basin
Petukhin, A.; Tsurugi, M.
2016-12-01
Predominant period of strong ground motions is an important parameter in earthquake engineering practice. Resonance at predominant period may result in collapse of building. Usually, predominant periods are associated with the soil resonances. However, considering that strong ground motions are composed from source, path and site effects, predominant periods are affected by source and propagation path too. From another side, 3D basin interferences may amplify quite different periods, depending on site location relatively to the basin edges and independently on the soil depth. Moreover, constructive or destructive interference of waves from different asperities of a large source may enhance or diminish amplitudes at a particular predominant period respectively. In this study, to demonstrate variations of predominant periods due to complicated effects above, we simulated wavefield snapshots and waveforms at a few representative sites of Osaka basin, Japan. Seismic source is located in Nankai trough, hosting anticipated M9 earthquake. 3D velocity structure is combined from JIVSM velocity structure (Koketsu et al., 2012) and Osaka basin structure of Iwaki and Iwata, 2011. 3D-FDM method is used to simulate waveforms. Simulation results confirm some previous results that due to elongated elliptical shape of Osaka basin, interference effects are strong and peak amplitudes has characteristic stripped pattern elongated in parallel to the long axis of basin. We demonstrate that predominant periods have similar pattern and value of predominant period may strongly depend on the location of site and azimuthal orientation of waveform component.
Accuracy of binary black hole waveform models for aligned-spin binaries
Kumar, Prayush; Fong, Heather; Pfeiffer, Harald P; Boyle, Michael; Hemberger, Daniel A; Kidder, Lawrence E; Scheel, Mark A; Szilagyi, Bela
2016-01-01
Coalescing binary black holes are among the primary science targets for second generation ground-based gravitational wave (GW) detectors. Reliable GW models are central to detection of such systems and subsequent parameter estimation. This paper performs a comprehensive analysis of the accuracy of recent waveform models for binary black holes with aligned spins, utilizing a new set of $84$ high-accuracy numerical relativity simulations. Our analysis covers comparable mass binaries ($1\\le m_1/m_2\\le 3$), and samples independently both black hole spins up to dimensionless spin-magnitude of $0.9$ for equal-mass binaries and $0.85$ for unequal mass binaries. Furthermore, we focus on the high-mass regime (total mass $\\gtrsim 50M_\\odot$). The two most recent waveform models considered (PhenomD and SEOBNRv2) both perform very well for signal detection, losing less than 0.5\\% of the recoverable signal-to-noise ratio $\\rho$, except that SEOBNRv2's efficiency drops mildly for both black hole spins aligned with large ma...
Tang, Ce; Wang, Pei; Gong, Yushun; Wei, Liang; Li, Yongqin; Zhang, Shaoxiang
2016-05-01
Biphasic waveforms are superior to monophasic waveforms for the termination of ventricular fibrillation (VF). However, whether triphasic waveforms are more effective than biphasic ones is still controversial. In the present study, we investigated the effects of second and third phase duration of triphasic rectangle waveform on defibrillation efficacy in a rabbit model of VF. VF was electrically induced and untreated for 30s in 20 New Zealand rabbits. A defibrillatory shock was applied with one of the 7 waveforms: 6 triphasic rectangle waveforms and a biphasic rectangle waveform. The triphasic waveforms had identical first duration but with different second and third phase durations. A 5 step up-and-down protocol was utilized for determining the defibrillation threshold (DFT). After a 5min interval, the procedure was repeated. A total of 35 cardiac arrest events and defibrillations were investigated for each animal. Two triphasic waveforms with identical first and second phase duration but shorter third phase duration had significantly lower DFT energy than biphasic waveform (0.57±0.18J vs. 0.80±0.28J, p=0.001; 0.60±0.18J vs. 0.80±0.28J, p=0.003). However, no statistical difference in DFT energy was observed between the two triaphsic waveforms that had identical phase duration but different voltages (0.57±0.18J vs. 0.60±0.18J, p=0.638). Phase durations played a main role on defibrillation success for triphasic rectangle waveforms. The optimal triphasic rectangle waveforms that composed of identical second and first phase durations but with shorter third pulse were superior to biphasic rectangle waveform for ventricular defibrillation. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Analysis of a Proposed Two-Frequency Radar Waveform
1974-11-01
PROGRAM ELEMENT, PROJECT, TASK AREA II WORK UNIT NUMBERS 65378 fiA II. REPORT DATE November 1974 IS. NUMBER OF PAGES IS. SECURITY CLASS...AUOR /• +(UI) ■ AUJ.-U).-A«>..)T.+ cp.] id dl o lo o iddili + A cos[(Au) -i«)J- fAu )JJ)t+2(Uu -AuOR /C+(UJ -^1«,)^+ cpj Iddl olo
Analysis of Soldier Radio Waveform Performance in Operational Test
2015-05-01
IDA committee, Dr. Steve Warner (Chair), Dr. Jason M. Gonzales, Ms. Keri L. Dorman, Dr. Leo H. Jones, Dr. David A. Sparrow and MG Charles G. Sutten...Antennas & Propagation Library), Washington DC: Artech House , 2007. 14. Y. Okumura, “Field Strength and its Variability in VHF and UHF Land-mobile
Methods, systems and apparatus for adjusting duty cycle of pulse width modulated (PWM) waveforms
Energy Technology Data Exchange (ETDEWEB)
Gallegos-Lopez, Gabriel; Kinoshita, Michael H; Ransom, Ray M; Perisic, Milun
2013-05-21
Embodiments of the present invention relate to methods, systems and apparatus for controlling operation of a multi-phase machine in a vector controlled motor drive system when the multi-phase machine operates in an overmodulation region. The disclosed embodiments provide a mechanism for adjusting a duty cycle of PWM waveforms so that the correct phase voltage command signals are applied at the angle transitions. This can reduce variations/errors in the phase voltage command signals applied to the multi-phase machine so that phase current may be properly regulated thus reducing current/torque oscillation, which can in turn improve machine efficiency and performance, as well as utilization of the DC voltage source.
Djebbi, Ramzi
2015-08-19
The instantaneous traveltime is able to reduce the non-linearity of full waveform inversion (FWI) that originates from the wrapping of the phase. However, the adjoint state method in this case requires a total of 5 modeling calculations to compute the gradient. Also, considering the larger modeling cost for anisotropic wavefield extrapolation and the necessity to use a line-search algorithm to estimate a step length that depends on the parameters scale, we propose to calculate the gradient based on the instantaneous traveltime sensitivity kernels. We, specifically, use the sensitivity kernels computed using dynamic ray-tracing to build the gradient. The resulting update is computed using a matrix decomposition and accordingly the computational cost is reduced. We consider a simple example where an anomaly is embedded into a constant background medium and we compute the update for the VTI wave equation parameterized using vh, η and ε.
2014-01-01
Analysis Improvement Group Cdma Code Division Multiple Access CMSP commercial mobile service provider CORBA Common Object Request Broker Architecture COTS...component of a planned tactical military communications system) and the long- term evolution (LTE) waveform (a key component of advanced commercial mobile ...most contribute to its less-than-favorable comparison with LTE, four stand out. First, the amount spent on JTRS Ground Mobile Radio (GMR) and WNW
Correlation analysis for reducing signature-based WAF false positives rates
Directory of Open Access Journals (Sweden)
Valeriya Grigorjevna Shervarly
2015-12-01
Full Text Available This paper addresses the problem of reducing the number of false positives of signature-based WAF. We propose an automatic method for detecting specific signatures which give high FP rates for the given web application using correlation analysis. The proposed method is based on a statistical analysis of the relationship between the total number of HTTP-transactions observed by WAF, and the number of signatures alerts. The proposed method doesn't require the learning phase, and may be used in production in continuous manner, making it more comfortable for the end user of the WAF.
EMF signals and ion/ligand binding kinetics: prediction of bioeffective waveform parameters.
Pilla, A A; Muehsam, D J; Markov, M S; Sisken, B F
1999-02-01
The kinetics of an electromagnetic field (EMF) target pathway are used to estimate frequency windows for EMF bioeffects. Ion/ligand binding is characterized via first order kinetics from which a specific electrical impedance can be derived. The resistance/capacitance properties of the binding pathway impedance, determined by the kinetics of the rate-determining step, define the frequency range over which the target pathway is most sensitive to external EMF. Applied signals may thus be configured such that their spectral content closely matches that of the target, using evaluation of the signal to thermal noise ratio to optimize waveform parameters. Using the approach proposed in this study, a pulsed radio frequency (PRF) waveform, currently employed clinically for soft tissue repair, was returned by modulation of burst duration, producing significant bioeffects at substantially reduced signal amplitude. Application is made to Ca2+/Calmodulin-dependent myosin phosphorylation, for which the binding time constants may be estimated from reported kinetics, neurite outgrowth from embryonic chick dorsal root explants and bone repair in a fracture model. The results showed that the retuned signal produced increased phosphorylation rates, neurite outgrowth and biomechanical strength that were indistinguishable from those produced by the clinical signal, but with a tenfold reduction in peak signal amplitude, approximately 800-fold reduction in average amplitude and approximately 10(6)-fold reduction in average power.
Application of weighted early-arrival waveform inversion to shallow land data
Yu, Han
2014-03-01
Seismic imaging of deep land targets is usually difficult since the near-surface velocities are not accurately estimated. Recent studies have shown that inverting traces weighted by the energy of the early-arrivals can improve the accuracy of estimating shallow velocities. In this work, it is explained by showing that the associated misfit gradient function tends to be sensitive to the kinetics of wave propagation and insensitive to the dynamics. A synthetic example verifies the theoretical predictions and shows that the effects of noise and unpredicted amplitude variations in the inversion are reduced using this weighted early arrival waveform inversion (WEWI). We also apply this method to a 2D land data set for estimating the near-surface velocity distribution. The reverse time migration images suggest that, compared to the tomogram inverted directly from the early arrival waveforms, the WEWI tomogram provides a more convincing velocity model and more focused reflections in the deeper part of the image. © 2014 Elsevier B.V.
Ultrasonic computed tomography based on full-waveform inversion for bone quantitative imaging
Bernard, Simon; Monteiller, Vadim; Komatitsch, Dimitri; Lasaygues, Philippe
2017-09-01
We introduce an ultrasonic quantitative imaging method for long bones based on full-waveform inversion. The cost function is defined as the difference in the L 2-norm sense between observed data and synthetic results at a given iteration of the iterative inversion process. For simplicity, and in order to reduce the computational cost, we use a two-dimensional acoustic approximation. The inverse problem is solved iteratively based on a quasi-Newton technique called the Limited-memory Broyden-Fletcher-Goldfarb-Shanno method. We show how the technique can be made to work fine for benchmark models consisting of a single cylinder, and then five cylinders, the latter case including significant multiple diffraction effects. We then show pictures obtained for a tibia-fibula bone pair model. Convergence is fast, typically in 15 to 30 iterations in practice in each frequency band used. We discuss the so-called ‘cycle skipping’ effect that can occur in such full waveform inversion techniques and make them remain trapped in a local minimum of the cost function. We illustrate strategies that can be used in practice to avoid this. Future work should include viscoelastic materials rather than acoustic, and real data instead of synthetic data.
MoghaddamHosseini, Vahideh; Nazarzadeh, Milad; Jahanfar, Shayesteh
2017-11-07
Fear of childbirth is a problematic mental health issue during pregnancy. But, effective interventions to reduce this problem are not well understood. To examine effective interventions for reducing fear of childbirth. The Cochrane Central Register of Controlled Trials, PubMed, Embase and PsycINFO were searched since inception till September 2017 without any restriction. Randomised controlled trials and quasi-randomised controlled trials comparing interventions for treatment of fear of childbirth were included. The standardized mean differences were pooled using random and fixed effect models. The heterogeneity was determined using the Cochran's test and I(2) index and was further explored in meta-regression model and subgroup analyses. Ten studies inclusive of 3984 participants were included in the meta-analysis (2 quasi-randomized and 8 randomized clinical trials). Eight studies investigated education and two studies investigated hypnosis-based intervention. The pooled standardized mean differences of fear for the education intervention and hypnosis group in comparison with control group were -0.46 (95% CI -0.73 to -0.19) and -0.22 (95% CI -0.34 to -0.10), respectively. Both types of interventions were effective in reducing fear of childbirth; however our pooled results revealed that educational interventions may reduce fear with double the effect of hypnosis. Further large scale randomized clinical trials and individual patient data meta-analysis are warranted for assessing the association. Copyright © 2017 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.
Interventions to reduce sexual prejudice: a study-space analysis and meta-analytic review.
Bartoş, SE; Berger, I; Hegarty, P
2014-01-01
Sexual prejudice is an important threat to the physical and mental well-being of lesbians, gay men, and bisexual people. Therefore, we reviewed the effectiveness of interventions designed to reduce such prejudice. A study-space analysis was performed on published and unpublished papers from all over the world to identify well-studied and underexplored issues. Most studies were conducted with North American undergraduates and were educational in nature. Dissertations were often innovative and ...
Music interventions to reduce stress and anxiety in pregnancy: a systematic review and meta-analysis
Corbijn van Willenswaard, K; Lynn, F.; McNeill, J.; McQueen, K.; Dennis, C-L; Lobel, M; Alderdice, F.
2017-01-01
Background Stress and anxiety are common in pregnancy and shown to have adverse effects on maternal and infant health outcomes. The aim of this review and meta-analysis was to assess the effectiveness of music-based interventions in reducing levels of stress or anxiety among pregnant women. Methods Six databases were searched using key terms relating to pregnancy, psychological stress, anxiety and music. Inclusion criteria were randomised controlled or quasi-experimental trials that assessed ...
Music interventions to reduce stress and anxiety in pregnancy: a systematic review and meta-analysis
Corbijn van Willenswaard, K; Lynn, F; McNeill, J; McQueen, K.; Dennis, C-L; Lobel, M; Alderdice, F.
2017-01-01
Background Stress and anxiety are common in pregnancy and shown to have adverse effects on maternal and infant health outcomes. The aim of this review and meta-analysis was to assess the effectiveness of music-based interventions in reducing levels of stress or anxiety among pregnant women. Methods Six databases were searched using key terms relating to pregnancy, psychological stress, anxiety and music. Inclusion criteria were randomised controlled or quasi-experimental trials that...
Energy Technology Data Exchange (ETDEWEB)
Noll, L.A.; Burchfield, T.E.
1982-01-01
The article describes the calculation of the reduced surface excess from a continuous flow experiment. The desirability of using surface excess is considered. The usual method of frontal analysis is explained, and its shortcomings are briefly mentioned. The results of both methods of calculation are shown using the Everett model, and these results are compared with each other and with the thermal data gathered simultaneously. Calculation of surface excess for a flowing multicomponent system is outlined. 4 figures, 3 tables.
Sums of Spike Waveform Features for Motor Decoding
Directory of Open Access Journals (Sweden)
Jie Li
2017-07-01
Full Text Available Traditionally, the key step before decoding motor intentions from cortical recordings is spike sorting, the process of identifying which neuron was responsible for an action potential. Recently, researchers have started investigating approaches to decoding which omit the spike sorting step, by directly using information about action potentials' waveform shapes in the decoder, though this approach is not yet widespread. Particularly, one recent approach involves computing the moments of waveform features and using these moment values as inputs to decoders. This computationally inexpensive approach was shown to be comparable in accuracy to traditional spike sorting. In this study, we use offline data recorded from two Rhesus monkeys to further validate this approach. We also modify this approach by using sums of exponentiated features of spikes, rather than moments. Our results show that using waveform feature sums facilitates significantly higher hand movement reconstruction accuracy than using waveform feature moments, though the magnitudes of differences are small. We find that using the sums of one simple feature, the spike amplitude, allows better offline decoding accuracy than traditional spike sorting by expert (correlation of 0.767, 0.785 vs. 0.744, 0.738, respectively, for two monkeys, average 16% reduction in mean-squared-error, as well as unsorted threshold crossings (0.746, 0.776; average 9% reduction in mean-squared-error. Our results suggest that the sums-of-features framework has potential as an alternative to both spike sorting and using unsorted threshold crossings, if developed further. Also, we present data comparing sorted vs. unsorted spike counts in terms of offline decoding accuracy. Traditional sorted spike counts do not include waveforms that do not match any template (“hash”, but threshold crossing counts do include this hash. On our data and in previous work, hash contributes to decoding accuracy. Thus, using the
Sums of Spike Waveform Features for Motor Decoding.
Li, Jie; Li, Zheng
2017-01-01
Traditionally, the key step before decoding motor intentions from cortical recordings is spike sorting, the process of identifying which neuron was responsible for an action potential. Recently, researchers have started investigating approaches to decoding which omit the spike sorting step, by directly using information about action potentials' waveform shapes in the decoder, though this approach is not yet widespread. Particularly, one recent approach involves computing the moments of waveform features and using these moment values as inputs to decoders. This computationally inexpensive approach was shown to be comparable in accuracy to traditional spike sorting. In this study, we use offline data recorded from two Rhesus monkeys to further validate this approach. We also modify this approach by using sums of exponentiated features of spikes, rather than moments. Our results show that using waveform feature sums facilitates significantly higher hand movement reconstruction accuracy than using waveform feature moments, though the magnitudes of differences are small. We find that using the sums of one simple feature, the spike amplitude, allows better offline decoding accuracy than traditional spike sorting by expert (correlation of 0.767, 0.785 vs. 0.744, 0.738, respectively, for two monkeys, average 16% reduction in mean-squared-error), as well as unsorted threshold crossings (0.746, 0.776; average 9% reduction in mean-squared-error). Our results suggest that the sums-of-features framework has potential as an alternative to both spike sorting and using unsorted threshold crossings, if developed further. Also, we present data comparing sorted vs. unsorted spike counts in terms of offline decoding accuracy. Traditional sorted spike counts do not include waveforms that do not match any template ("hash"), but threshold crossing counts do include this hash. On our data and in previous work, hash contributes to decoding accuracy. Thus, using the comparison between
Interventions to reduce stress in university students: a review and meta-analysis.
Regehr, Cheryl; Glancy, Dylan; Pitts, Annabel
2013-05-15
Recent research has revealed concerning rates of anxiety and depression among university students. Nevertheless, only a small percentage of these students receive treatment from university health services. Universities are thus challenged with instituting preventative programs that address student stress and reduce resultant anxiety and depression. A systematic review of the literature and meta-analysis was conducted to examine the effectiveness of interventions aimed at reducing stress in university students. Studies were eligible for inclusion if the assignment of study participants to experimental or control groups was by random allocation or parallel cohort design. Retrieved studies represented a variety of intervention approaches with students in a broad range of programs and disciplines. Twenty-four studies, involving 1431 students were included in the meta-analysis. Cognitive, behavioral and mindfulness interventions were associated with decreased symptoms of anxiety. Secondary outcomes included lower levels of depression and cortisol. Included studies were limited to those published in peer reviewed journals. These studies over-represent interventions with female students in Western countries. Studies on some types of interventions such as psycho-educational and arts based interventions did not have sufficient data for inclusion in the meta-analysis. This review provides evidence that cognitive, behavioral, and mindfulness interventions are effective in reducing stress in university students. Universities are encouraged to make such programs widely available to students. In addition however, future work should focus on developing stress reduction programs that attract male students and address their needs. Copyright © 2012 Elsevier B.V. All rights reserved.
Schumacher, F.; Friederich, W.; Lamara, S.
2016-02-01
We present a new conceptual approach to scattering-integral-based seismic full waveform inversion (FWI) that allows a flexible, extendable, modular and both computationally and storage-efficient numerical implementation. To achieve maximum modularity and extendability, interactions between the three fundamental steps carried out sequentially in each iteration of the inversion procedure, namely, solving the forward problem, computing waveform sensitivity kernels and deriving a model update, are kept at an absolute minimum and are implemented by dedicated interfaces. To realize storage efficiency and maximum flexibility, the spatial discretization of the inverted earth model is allowed to be completely independent of the spatial discretization employed by the forward solver. For computational efficiency reasons, the inversion is done in the frequency domain. The benefits of our approach are as follows: (1) Each of the three stages of an iteration is realized by a stand-alone software program. In this way, we avoid the monolithic, unflexible and hard-to-modify codes that have often been written for solving inverse problems. (2) The solution of the forward problem, required for kernel computation, can be obtained by any wave propagation modelling code giving users maximum flexibility in choosing the forward modelling method. Both time-domain and frequency-domain approaches can be used. (3) Forward solvers typically demand spatial discretizations that are significantly denser than actually desired for the inverted model. Exploiting this fact by pre-integrating the kernels allows a dramatic reduction of disk space and makes kernel storage feasible. No assumptions are made on the spatial discretization scheme employed by the forward solver. (4) In addition, working in the frequency domain effectively reduces the amount of data, the number of kernels to be computed and the number of equations to be solved. (5) Updating the model by solving a large equation system can be
Monnier, S.; Lumley, D. E.; Kamei, R.; Goncharov, A.; Shragge, J. C.
2016-12-01
Ocean Bottom Seismic datasets have become increasingly used in recent years to develop high-resolution, wavelength-scale P-wave velocity models of the lithosphere from waveform inversion, due to their recording of long-offset transmitted phases. New OBS surveys evolve towards novel acquisition geometries involving longer offsets (several hundreds of km), broader frequency content (1-100 Hz), while receiver sampling often remains sparse (several km). Therefore, it is critical to assess the effects of such geometries on the eventual success and resolution of waveform inversion velocity models. In this study, we investigate the feasibility of waveform inversion on the Bart 2D OBS profile acquired offshore Western Australia, to investigate regional crustal and Moho structures. The dataset features 14 broadband seismometers (0.01-100 Hz) from AuScope's national OBS fleet, offsets in excess of 280 km, and a sparse receiver sampling (18 km). We perform our analysis in four stages: (1) field data analysis, (2) 2D P-wave velocity model building, synthetic data (3) modelling, and (4) waveform inversion. Data exploration shows high-quality active-source signal down to 2Hz, and usable first arrivals to offsets greater than 100 km. The background velocity model is constructed by combining crustal and Moho information in continental reference models (e.g., AuSREM, AusMoho). These low-resolution studies suggest a crustal thickness of 20-25 km along our seismic line and constitute a starting point for synthetic modelling and inversion. We perform synthetic 2D time-domain modelling to: (1) evaluate the misfit between synthetic and field data within the usable frequency band (2-10 Hz); (2) validate our velocity model; and (3) observe the effects of sparse OBS interval on data quality. Finally, we apply 2D acoustic frequency-domain waveform inversion to the synthetic data to generate velocity model updates. The inverted model is compared to the reference model to investigate the
Reduced order models for thermal analysis : final report : LDRD Project No. 137807.
Energy Technology Data Exchange (ETDEWEB)
Hogan, Roy E., Jr.; Gartling, David K.
2010-09-01
This LDRD Senior's Council Project is focused on the development, implementation and evaluation of Reduced Order Models (ROM) for application in the thermal analysis of complex engineering problems. Two basic approaches to developing a ROM for combined thermal conduction and enclosure radiation problems are considered. As a prerequisite to a ROM a fully coupled solution method for conduction/radiation models is required; a parallel implementation is explored for this class of problems. High-fidelity models of large, complex systems are now used routinely to verify design and performance. However, there are applications where the high-fidelity model is too large to be used repetitively in a design mode. One such application is the design of a control system that oversees the functioning of the complex, high-fidelity model. Examples include control systems for manufacturing processes such as brazing and annealing furnaces as well as control systems for the thermal management of optical systems. A reduced order model (ROM) seeks to reduce the number of degrees of freedom needed to represent the overall behavior of the large system without a significant loss in accuracy. The reduction in the number of degrees of freedom of the ROM leads to immediate increases in computational efficiency and allows many design parameters and perturbations to be quickly and effectively evaluated. Reduced order models are routinely used in solid mechanics where techniques such as modal analysis have reached a high state of refinement. Similar techniques have recently been applied in standard thermal conduction problems e.g. though the general use of ROM for heat transfer is not yet widespread. One major difficulty with the development of ROM for general thermal analysis is the need to include the very nonlinear effects of enclosure radiation in many applications. Many ROM methods have considered only linear or mildly nonlinear problems. In the present study a reduced order model is
How Effective Is Road Mitigation at Reducing Road-Kill? A Meta-Analysis
Rytwinski, Trina; Soanes, Kylie; Jaeger, Jochen A. G.; Fahrig, Lenore; Findlay, C. Scott; Houlahan, Jeff; van der Ree, Rodney; van der Grift, Edgar A
2016-01-01
Road traffic kills hundreds of millions of animals every year, posing a critical threat to the populations of many species. To address this problem there are more than forty types of road mitigation measures available that aim to reduce wildlife mortality on roads (road-kill). For road planners, deciding on what mitigation method to use has been problematic because there is little good information about the relative effectiveness of these measures in reducing road-kill, and the costs of these measures vary greatly. We conducted a meta-analysis using data from 50 studies that quantified the relationship between road-kill and a mitigation measure designed to reduce road-kill. Overall, mitigation measures reduce road-kill by 40% compared to controls. Fences, with or without crossing structures, reduce road-kill by 54%. We found no detectable effect on road-kill of crossing structures without fencing. We found that comparatively expensive mitigation measures reduce large mammal road-kill much more than inexpensive measures. For example, the combination of fencing and crossing structures led to an 83% reduction in road-kill of large mammals, compared to a 57% reduction for animal detection systems, and only a 1% for wildlife reflectors. We suggest that inexpensive measures such as reflectors should not be used until and unless their effectiveness is tested using a high-quality experimental approach. Our meta-analysis also highlights the fact that there are insufficient data to answer many of the most pressing questions that road planners ask about the effectiveness of road mitigation measures, such as whether other less common mitigation measures (e.g., measures to reduce traffic volume and/or speed) reduce road mortality, or to what extent the attributes of crossing structures and fences influence their effectiveness. To improve evaluations of mitigation effectiveness, studies should incorporate data collection before the mitigation is applied, and we recommend a
Cumulative subgroup analysis to reduce waste in clinical research for individualised medicine.
Song, Fujian; Bachmann, Max O
2016-12-15
Although subgroup analyses in clinical trials may provide evidence for individualised medicine, their conduct and interpretation remain controversial. Subgroup effect can be defined as the difference in treatment effect across patient subgroups. Cumulative subgroup analysis refers to a series of repeated pooling of subgroup effects after adding data from each of related trials chronologically, to investigate the accumulating evidence for subgroup effects. We illustrated the clinical relevance of cumulative subgroup analysis in two case studies using data from published individual patient data (IPD) meta-analyses. Computer simulations were also conducted to examine the statistical properties of cumulative subgroup analysis. In case study 1, an IPD meta-analysis of 10 randomised trials (RCTs) on beta blockers for heart failure reported significant interaction of treatment effects with baseline rhythm. Cumulative subgroup analysis could have detected the subgroup effect 15 years earlier, with five fewer trials and 71% less patients, than the IPD meta-analysis which first reported it. Case study 2 involved an IPD meta-analysis of 11 RCTs on treatments for pulmonary arterial hypertension that reported significant subgroup effect by aetiology. Cumulative subgroup analysis could have detected the subgroup effect 6 years earlier, with three fewer trials and 40% less patients than the IPD meta-analysis. Computer simulations have indicated that cumulative subgroup analysis increases the statistical power and is not associated with inflated false positives. To reduce waste of research data, subgroup analyses in clinical trials should be more widely conducted and adequately reported so that cumulative subgroup analyses could be timely performed to inform clinical practice and further research.
Restoration of clipped seismic waveforms using projection onto convex sets method.
Zhang, Jinhai; Hao, Jinlai; Zhao, Xu; Wang, Shuqin; Zhao, Lianfeng; Wang, Weimin; Yao, Zhenxing
2016-12-14
The seismic waveforms would be clipped when the amplitude exceeds the upper-limit dynamic range of seismometer. Clipped waveforms are typically assumed not useful and seldom used in waveform-based research. Here, we assume the clipped components of the waveform share the same frequency content with the un-clipped components. We leverage this similarity to convert clipped waveforms to true waveforms by iteratively reconstructing the frequency spectrum using the projection onto convex sets method. Using artificially clipped data we find that statistically the restoration error is ~1% and ~5% when clipped at 70% and 40% peak amplitude, respectively. We verify our method using real data recorded at co-located seismometers that have different gain controls, one set to record large amplitudes on scale and the other set to record low amplitudes on scale. Using our restoration method we recover 87 out of 93 clipped broadband records from the 2013 Mw6.6 Lushan earthquake. Estimating that we recover 20 clipped waveforms for each M5.0+ earthquake, so for the ~1,500 M5.0+ events that occur each year we could restore ~30,000 clipped waveforms each year, which would greatly enhance useable waveform data archives. These restored waveform data would also improve the azimuthal station coverage and spatial footprint.
Pathway-based analysis using reduced gene subsets in genome-wide association studies
Directory of Open Access Journals (Sweden)
Liu Jianjun
2011-01-01
Full Text Available Abstract Background Single Nucleotide Polymorphism (SNP analysis only captures a small proportion of associated genetic variants in Genome-Wide Association Studies (GWAS partly due to small marginal effects. Pathway level analysis incorporating prior biological information offers another way to analyze GWAS's of complex diseases, and promises to reveal the mechanisms leading to complex diseases. Biologically defined pathways are typically comprised of numerous genes. If only a subset of genes in the pathways is associated with disease then a joint analysis including all individual genes would result in a loss of power. To address this issue, we propose a pathway-based method that allows us to test for joint effects by using a pre-selected gene subset. In the proposed approach, each gene is considered as the basic unit, which reduces the number of genetic variants considered and hence reduces the degrees of freedom in the joint analysis. The proposed approach also can be used to investigate the joint effect of several genes in a candidate gene study. Results We applied this new method to a published GWAS of psoriasis and identified 6 biologically plausible pathways, after adjustment for multiple testing. The pathways identified in our analysis overlap with those reported in previous studies. Further, using simulations across a range of gene numbers and effect sizes, we demonstrate that the proposed approach enjoys higher power than several other approaches to detect associated pathways. Conclusions The proposed method could increase the power to discover susceptibility pathways and to identify associated genes using GWAS. In our analysis of genome-wide psoriasis data, we have identified a number of relevant pathways for psoriasis.
DEFF Research Database (Denmark)
Keskinen, Johanna; Zibar, Majken Caroline Looms; Moreau, Julien
2014-01-01
-time tomography. The new models also reflect the variability seen in 1D drill core analysis. The results indicate that full-waveform inversion is a well-suited inversion technique for high-resolution time-lapse-based flow characterization. Read More: http://library.seg.org/doi/abs/10.1190/segam2014-1199.1...... techniques provide models that are overly smooth and have relatively low resolution. We present preliminary results from full-waveform inversion of data collected in strongly heterogeneous chalk. The resolution of the tomograms has improved significantly compared to models obtained from travel...
Huang, Jian; Walcott, Gregory P.; Ruse, Richard B.; Bohanan, Scott J.; Killingsworth, Cheryl R.; Ideker, Raymond E.
2014-01-01
Background We tested the hypothesis that the shape of the shock waveform affects not only the defibrillation threshold (DFT), but also the amount of cardiac damage. Methods and Results DFTs were determined for 11 waveforms: 3 ascending ramp, 3 descending ramp, and 3 rectilinear first phase biphasic waveforms, a Gurvich waveform, and a truncated exponential biphasic waveform in 6 pigs with electrodes in the RV apex and SVC. The ascending, descending and rectilinear waveforms had 4, 8 and 16 ms 1st phases and a 3.5 ms 2nd rectilinear phase half the voltage of the 1st phase. The exponential biphasic waveform had a 60% 1st phase and a 50% 2nd phase tilt. In a second study, we attempted to defibrillate after 10 s of VF with a single ≈ 30 J shock (6 pigs successfully defibrillated with 8 ms ascending, 8 ms rectilinear wave and truncated exponential biphasic waveforms). Troponin I blood levels were determined before and 2 to 10 hrs after the shock. The lowest energy DFT was for the 8 ms ascending ramp (14.6±7.3 SD J), which was significantly less than for the truncated exponential (19.6±6.3 J). Six hours postshock, troponin I in ng/ml was significantly less for the ascending ramp (0.80±0.54) than for the truncated exponential (1.92±0.47) or the rectilinear waveform (1.17 ±0.45). Conclusions The ascending ramp has a significantly lower DFT, and at ≈ 30 J causes 58% less troponin I release than the truncated exponential biphasic shock. Therefore, the shock waveform affects both the DFT and the amount of cardiac damage. PMID:22865891
Genetic Analysis of Reduced γ-Tocopherol Content in Ethiopian Mustard Seeds
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Elena García-Navarro
2016-01-01
Full Text Available Ethiopian mustard (Brassica carinata A. Braun line BCT-6, with reduced γ-tocopherol content in the seeds, has been previously developed. The objective of this research was to conduct a genetic analysis of seed tocopherols in this line. BCT-6 was crossed with the conventional line C-101 and the F1, F2, and BC plant generations were analyzed. Generation mean analysis using individual scaling tests indicated that reduced γ-tocopherol content fitted an additive-dominant genetic model with predominance of additive effects and absence of epistatic interactions. This was confirmed through a joint scaling test and additional testing of the goodness of fit of the model. Conversely, epistatic interactions were identified for total tocopherol content. Estimation of the minimum number of genes suggested that both γ- and total tocopherol content may be controlled by two genes. A positive correlation between total tocopherol content and the proportion of γ-tocopherol was identified in the F2 generation. Additional research on the feasibility of developing germplasm with high tocopherol content and reduced concentration of γ-tocopherol is required.
Epithermal Neutron Activation Analysis (ENAA) of Cr(VI)-reducer Basalt-inhabiting Bacteria
Tsibakhashvili, N Ya; Kirkesali, E I; Aksenova, N G; Kalabegishvili, T L; Murusidze, I G; Mosulishvili, L M; Holman, H Y N
2005-01-01
Epithermal neutron activation analysis (ENAA) has been applied to studying elemental composition of Cr(VI)-reducer bacteria isolated from polluted basalts from the Republic of Georgia. Cr(VI)-reducing ability of the bacteria was examined by electron spin resonance (ESR) demonstrating that the bacteria differ in the rates of Cr(VI) reduction. A well-pronounced correlation between the ability of the bacteria to accumulate Cr(V) and their ability to reduce Cr(V) to Cr(III) observed in our experiments is discussed. Elemental analysis of these bacteria also revealed that basalt-inhabiting bacteria are distinguished by relative contents of essential elements such as K, Na, Mg, Fe, Mn, Zn, and Co. A high rate of Cr(III) formation correlates with a high concentration of Co in the bacterium. ENAA detected some similarity in the elemental composition of the bacteria. The relatively high contents of Fe detected in the bacteria (140-340 $\\mu $g/g of dry weight) indicate bacterial adaptation to the environmental condition...
Zhao, Quanhua; LI, HONGYING; Li, Yu
2015-01-01
Full waveform LiDAR data record the signal of the backscattered laser pulse. The elevation and the energy information of ground targets can be effectively obtained by decomposition of the full waveform LiDAR data. Therefore, waveform decomposition is the key to full waveform LiDAR data processing. However, in waveform decomposition, determining the number of the components is a focus and difficult problem. To this end, this paper presents a method which can automatically determine the number....
Energy Technology Data Exchange (ETDEWEB)
Lin, Youzuo [Los Alamos National Laboratory; Huang, Lianjie [Los Alamos National Laboratory; Zhang, Zhigang [Los Alamos National Laboratory
2011-01-01
Double-difference waveform inversion is a promising tool for quantitative monitoring for enhanced geothermal systems (EGS). The method uses time-lapse seismic data to jointly inverts for reservoir changes. Due to the ill-posedness of waveform inversion, it is a great challenge to obtain reservoir changes accurately and efficiently, particularly when using timelapse seismic reflection data. To improve reconstruction, we develop a spatially-variant total-variation regularization scheme into double-difference waveform inversion to improve the inversion accuracy and robustness. The new regularization scheme employs different regularization parameters in different regions of the model to obtain an optimal regularization in each area. We compare the results obtained using a spatially-variant parameter with those obtained using a constant regularization parameter. Utilizing a spatially-variant regularization scheme, the target monitoring regions are well reconstructed and the image noise is significantly reduced outside the monitoring regions. Our numerical examples demonstrate that the spatially-variant total-variation regularization scheme provides the flexibility to regularize local regions based on the a priori spatial information without increasing computational costs and the computer memory requirement.
Interventions to reduce sexual prejudice: a study-space analysis and meta-analytic review.
Bartoş, Sebastian E; Berger, Israel; Hegarty, Peter
2014-01-01
Sexual prejudice is an important threat to the physical and mental well-being of lesbians, gay men, and bisexual people. Therefore, we reviewed the effectiveness of interventions designed to reduce such prejudice. A study-space analysis was performed on published and unpublished papers from all over the world to identify well-studied and underexplored issues. Most studies were conducted with North American undergraduates and were educational in nature. Dissertations were often innovative and well designed but were rarely published. We then performed meta-analyses on sets of comparable studies. Education, contact with gay people, and combining contact with education had a medium-size effect on several measures of sexual prejudice. The manipulation of social norms was effective in reducing antigay behavior. Other promising interventions, such as the use of entertainment media to promote tolerance, need further investigation. More research is also needed on populations other than American students, particularly groups who may have higher levels of sexual prejudice.
Directory of Open Access Journals (Sweden)
Xin-Bing Cheng
2010-07-01
Full Text Available The Blumlein pulse forming line (BPFL consisting of an inner coaxial pulse forming line (PFL and an outer coaxial PFL is widely used in the field of pulsed power, especially for intense electron-beam accelerators (IEBA. The output voltage waveform determines the quality and characteristics of the output beam current of the IEBA. Comparing with the conventional BPFL, an IEBA based on a helical type BPFL can increase the duration of the output voltage in the same geometrical volume. However, for the helical type BPFL, the voltage waveform on a matched load may be distorted which influences the electron-beam quality. In this paper, an IEBA based on helical type BPFL is studied theoretically. Based on telegrapher equations of the BPFL, a formula for the output voltage of IEBA is obtained when the transition section is taken into account, where the transition section is between the middle cylinder of BPFL and the load. From the theoretical analysis, it is found that the wave impedance and transit time of the transition section influence considerably the main pulse voltage waveform at the load, a step is formed in front of the main pulse, and a sharp spike is also formed at the end of the main pulse. In order to get a well-shaped square waveform at the load and to improve the electron-beam quality of such an accelerator, the wave impedance of the transition section should be equal to that of the inner PFL of helical type BPFL and the transit time of the transition section should be designed as short as possible. Experiments performed on an IEBA with the helical type BPFL show reasonable agreement with theoretical analysis.
Reduced Order Models for Decision Analysis and Upscaling of Aquifer Heterogeneity
Vesselinov, V. V.; O'Malley, D.; Alexandrov, B.; Moore, B.
2016-12-01
Model-based analyses such as uncertainty quantification, sensitivity analysis, and decision support using complex physics models with numerous model parameters and typically require a huge number of model evaluations (on order of 106). Furthermore, model simulations of complex physics may require substantial computational time. For example, accounting for simultaneously occurring physical processes such as fluid flow and biogeochemical reactions in heterogeneous porous medium may require days of wall-clock computational time. To address these issues, we have developed a methodology for reduced order modeling, which couples support vector regression (SVR), genetic algorithms (GA) and artificial and convolutional neural network (ANN/CNN). SVR is applied to predict the model behavior within prior uncertainty ranges associated with the model parameters. ANN and CNN procedures are applied to upscale heterogeneity of the porous medium. In the upscaling process, fine-scale high-resolution models of heterogeneity are applied to inform coarse-resolution models which have improved computational efficiency while capturing the impact of fine-scale effects at the course scale of interest. These techniques are tested independently on a series of synthetic problems. We also present a decision analysis related to contaminant remediation where the developed reduced order models are applied to reproduce groundwater flow and contaminant transport in a synthetic heterogeneous aquifer. The decision analysis is performed using Bayesian-Information-Gap Decision Theory which is implemented as part of the MADS framework (https://github.com/madsjulia/Mads.jl).
Energy Technology Data Exchange (ETDEWEB)
Kim, H., E-mail: heejongkim@uchicago.edu [Department of Radiology, University of Chicago, Chicago, IL 60637 (United States); Chen, C.-T.; Eclov, N. [Department of Radiology, University of Chicago, Chicago, IL 60637 (United States); Ronzhin, A.; Murat, P.; Ramberg, E.; Los, S. [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Wyrwicz, A.M.; Li, L. [NorthShore University HealthSystem Research Institute, Evanston, IL 60201 (United States); Kao, C.-M. [Department of Radiology, University of Chicago, Chicago, IL 60637 (United States)
2015-06-01
We are developing a time-of-flight Positron Emission Tomography (PET) detector by using silicon photo-multipliers (SiPM) on a strip-line and high speed waveform sampling data acquisition. In this design, multiple SiPMs are connected on a single strip-line and signal waveforms on the strip-line are sampled at two ends of the strip to reduce readout channels while fully exploiting the fast time response of SiPMs. In addition to the deposited energy and time information, the position of the hit SiPM along the strip-line is determined by the arrival time difference of the waveform. Due to the insensitivity of the SiPMs to magnetic fields and the compact front-end electronics, the detector approach is highly attractive for developing a PET insert system for a magnetic resonance imaging (MRI) scanner to provide simultaneous PET/MR imaging. To investigate the feasibility, experimental tests using prototype detector modules have been conducted inside a 9.4 T small animal MRI scanner (Bruker BioSpec 94/30 imaging spectrometer). On the prototype strip-line board, 16 SiPMs (5.2 mm pitch) are installed on two strip-lines and coupled to 2×8 LYSO scintillators (5.0×5.0×10.0 mm{sup 3} with 5.2 mm pitch). The outputs of the strip-line boards are connected to a Domino-Ring-Sampler (DRS4) evaluation board for waveform sampling. Preliminary experimental results show that the effect of interference on the MRI image due to the PET detector is negligible and that PET detector performance is comparable with the results measured outside the MRI scanner.
Static aeroelastic analysis including geometric nonlinearities based on reduced order model
Directory of Open Access Journals (Sweden)
Changchuan Xie
2017-04-01
Full Text Available This paper describes a method proposed for modeling large deflection of aircraft in nonlinear aeroelastic analysis by developing reduced order model (ROM. The method is applied for solving the static aeroelastic and static aeroelastic trim problems of flexible aircraft containing geometric nonlinearities; meanwhile, the non-planar effects of aerodynamics and follower force effect have been considered. ROMs are computational inexpensive mathematical representations compared to traditional nonlinear finite element method (FEM especially in aeroelastic solutions. The approach for structure modeling presented here is on the basis of combined modal/finite element (MFE method that characterizes the stiffness nonlinearities and we apply that structure modeling method as ROM to aeroelastic analysis. Moreover, the non-planar aerodynamic force is computed by the non-planar vortex lattice method (VLM. Structure and aerodynamics can be coupled with the surface spline method. The results show that both of the static aeroelastic analysis and trim analysis of aircraft based on structure ROM can achieve a good agreement compared to analysis based on the FEM and experimental result.
Waveform inversion schemes for 3D density structure
Blom, N.; Fichtner, A.
2014-12-01
We develop waveform inversion schemes for density, based on numerical wave propagation, adjoint techniques and various non-seismological constraints to enhance resolution. Density variations drive convection in the Earth and serve as a discriminator between thermal and compositional heterogeneities. However, classical seismological observables and gravity provide only weak constraints, with strong trade-offs. To put additional constraints on density structure, we develop waveform inversion schemes that exploit the seismic waveform itself for the benefit of improved density resolution. Our inversion scheme is intended to incorporate any information that can help to constrain 3D density structure. This includes non-seismological information, such as gravity and the geoid, the mass and moment of inertia of the Earth, and mineral physical constraints on maximum density heterogeneities (assuming reasonable variations in temperature and composition). In a series of initial synthetic experiments, we aim to construct efficient optimisation schemes that allow us to assimilate all the available types of information. For this, we use 2D numerical wave propagation combined with adjoint techniques for the computation of sensitivity kernels. With these kernels, we drive gradient-based optimisation schemes that incorporate our non-seismological constraints. Specifically, we assess the usefulness of an inversion strategy where additional information is used as hard constraints, as opposed to the optimisation of a single objective functional that incorporates all the information. Hard constraints may consist of the Earth's mass or moment of inertia, and are applied by solving a separate optimisation problem to project the initial (unconstrained) solution onto an allowed range. These synthetic experiments will allow us to assess to what extent velocity and density structure need to be coupled in order to obtain useful and meaningful results to a density inversion.
Finite Element and Plate Theory Modeling of Acoustic Emission Waveforms
Prosser, W. H.; Hamstad, M. A.; Gary, J.; OGallagher, A.
1998-01-01
A comparison was made between two approaches to predict acoustic emission waveforms in thin plates. A normal mode solution method for Mindlin plate theory was used to predict the response of the flexural plate mode to a point source, step-function load, applied on the plate surface. The second approach used a dynamic finite element method to model the problem using equations of motion based on exact linear elasticity. Calculations were made using properties for both isotropic (aluminum) and anisotropic (unidirectional graphite/epoxy composite) materials. For simulations of anisotropic plates, propagation along multiple directions was evaluated. In general, agreement between the two theoretical approaches was good. Discrepancies in the waveforms at longer times were caused by differences in reflections from the lateral plate boundaries. These differences resulted from the fact that the two methods used different boundary conditions. At shorter times in the signals, before reflections, the slight discrepancies in the waveforms were attributed to limitations of Mindlin plate theory, which is an approximate plate theory. The advantages of the finite element method are that it used the exact linear elasticity solutions, and that it can be used to model real source conditions and complicated, finite specimen geometries as well as thick plates. These advantages come at a cost of increased computational difficulty, requiring lengthy calculations on workstations or supercomputers. The Mindlin plate theory solutions, meanwhile, can be quickly generated on personal computers. Specimens with finite geometry can also be modeled. However, only limited simple geometries such as circular or rectangular plates can easily be accommodated with the normal mode solution technique. Likewise, very limited source configurations can be modeled and plate theory is applicable only to thin plates.
Geipel, Josephine; Koenig, Julian; Hillecke, Thomas K; Resch, Franz; Kaess, Michael
2018-01-01
Existing systematic reviews provide evidence that music therapy is an effective intervention in the treatment of children and adolescents with psychopathology. The objective of the present review was to systematically review and quantify the effects of music-based interventions in reducing internalizing symptoms (i.e., depression and anxiety) in children and adolescents using a meta-analytical approach. Databases and journals were systematically screened for studies eligible for inclusion in meta-analysis on the effects of music-based interventions in reducing internalizing symptoms. A random-effect meta-analysis using standardized mean differences (SMD) was conducted. Five studies were included. Analysis of data from (randomized) controlled trials, yielded a significant main effect (Hedge's g = -0.73; 95%CI [-1.42;-0.04], Z = 2.08, p = 0.04, k = 5), indicating a greater reduction of internalizing symptoms in youth receiving music-based interventions (n = 100) compared to different control group interventions (n = 95). The existing evidence is limited to studies of low power and methodological quality. Included studies were highly heterogeneous with respect to the nature of the intervention, the measurements applied, the samples studied, and the study design. Findings indicate that music-based interventions may be efficient in reducing the severity of internalizing symptoms in children and adolescents. While these results are encouraging with respect to the application of music-based intervention, rigorous research is necessary to replicate existing findings and provide a broader base of evidence. More research adopting well controlled study designs of high methodological quality is needed. Copyright © 2017 Elsevier B.V. All rights reserved.
Goniewicz Krzysztof; Goniewicz Mariusz; Pawłowski Witold; Czerski Robert
2017-01-01
Goniewicz Krzysztof, Goniewicz Mariusz, Pawłowski Witold, Czerski Robert. The analysis of activities and social campaigns aimed at reducing children’s risk of traffic incidents. Journal of Education, Health and Sport. 2017;7(8):1494-1505. eISSN 2391-8306. DOI http://dx.doi.org/10.5281/zenodo.1068323 http://ojs.ukw.edu.pl/index.php/johs/article/view/5071 https://pbn.nauka.gov.pl/sedno-webapp/works/839338 The journal has had 7 points in Ministry of Scie...
Waveform feature extraction algorithms for IceCube
Energy Technology Data Exchange (ETDEWEB)
Wallraff, Marius; Boersma, David; Wiebusch, Christopher [III. Physikalisches Institut, RWTH Aachen (Germany)
2010-07-01
The IceCube Neutrino Observatory at South Pole consists of digital optical modules (DOMs) deep down in the ice equipped with photomultipliers to capture Cherenkov light induced by muons and other particles. These DOMs digitize the analogue pulse shapes of the photomultiplier signals. The large amount of information has to be condensed for later particle track and energy reconstructions. This talk presents a new framework (the NewFeatureExtractor) to extract the arrival times and the number of photons. Three algorithms have been implemented in this framework to analyze different types of waveforms. Their performance is tested by comparison between experimental and simulated data and by comparison with earlier algorithms.
Interferometric full-waveform inversion of time-lapse data
Sinha, Mrinal
2017-08-17
One of the key challenges associated with time-lapse surveys is ensuring the repeatability between the baseline and monitor surveys. Non-repeatability between the surveys is caused by varying environmental conditions over the course of different surveys. To overcome this challenge, we propose the use of interferometric full waveform inversion (IFWI) for inverting the velocity model from data recorded by baseline and monitor surveys. A known reflector is used as the reference reflector for IFWI, and the data are naturally redatumed to this reference reflector using natural reflections as the redatuming operator. This natural redatuming mitigates the artifacts introduced by the repeatability errors that originate above the reference reflector.
Ultrafast chirped optical waveform recorder using a time microscope
Bennett, Corey Vincent
2015-04-21
A new technique for capturing both the amplitude and phase of an optical waveform is presented. This technique can capture signals with many THz of bandwidths in a single shot (e.g., temporal resolution of about 44 fs), or be operated repetitively at a high rate. That is, each temporal window (or frame) is captured single shot, in real time, but the process may be run repeatedly or single-shot. By also including a variety of possible demultiplexing techniques, this process is scalable to recoding continuous signals.
A Denoising Method for LiDAR Full-Waveform Data
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Xudong Lai
2015-01-01
Full Text Available Decomposition of LiDAR full-waveform data can not only enhance the density and positioning accuracy of a point cloud, but also provide other useful parameters, such as pulse width, peak amplitude, and peak position which are important information for subsequent processing. Full-waveform data usually contain some random noises. Traditional filtering algorithms always cause distortion in the waveform. λ/μ filtering algorithm is based on Mean Shift method. It can smooth the signal iteratively and will not cause any distortion in the waveform. In this paper, an improved λ/μ filtering algorithm is proposed, and several experiments on both simulated waveform data and real waveform data are implemented to prove the effectiveness of the proposed algorithm.
Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter.
Yue, Wenzhen; Zhang, Yan; Liu, Yimin; Xie, Jingwen
2016-06-17
Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter's power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods.
Radar Constant-Modulus Waveform Design with Prior Information of the Extended Target and Clutter
Directory of Open Access Journals (Sweden)
Wenzhen Yue
2016-06-01
Full Text Available Radar waveform design is of great importance for radar system performances and has drawn considerable attention recently. Constant modulus is an important waveform design consideration, both from the point of view of hardware realization and to allow for full utilization of the transmitter’s power. In this paper, we consider the problem of constant-modulus waveform design for extended target detection with prior information about the extended target and clutter. At first, we propose an arbitrary-phase unimodular waveform design method via joint transmitter-receiver optimization. We exploit a semi-definite relaxation technique to transform an intractable non-convex problem into a convex problem, which can then be efficiently solved. Furthermore, quadrature phase shift keying waveform is designed, which is easier to implement than arbitrary-phase waveforms. Numerical results demonstrate the effectiveness of the proposed methods.
Investigation of Leakage Current Waveforms Recorded in a Coastal High Voltage Substation
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E. Thalassinakis
2011-06-01
Full Text Available Leakage current monitoring is a widely employed technique to monitor the performance of outdoor insulation. The evaluation of leakage current waveforms recorded in the field, offers significant information since insulation’s performance is strongly linked with local conditions, and the waveforms’ shape correlate to different types of surface activity. In this paper, an investigation of leakage current waveforms recorded in a 150 kV coastal Substations suffering which suffers intense marine pollution is presented. Investigation of the recorded waveforms verified the basic waveform shapes described in the literature. Further, several variations of the basic types and complex waveforms, as well as field related waveforms, are presented. The need for added categorization criteria in the case of field measurements is discussed.
Sinusoidal oscillators and waveform generators using modern electronic circuit building blocks
Senani, Raj; Singh, V K; Sharma, R K
2016-01-01
This book serves as a single-source reference to sinusoidal oscillators and waveform generators, using classical as well as a variety of modern electronic circuit building blocks. It provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators and includes a catalogue of over 600 configurations of oscillators and waveform generators, describing their relevant design details and salient performance features/limitations. The authors discuss a number of interesting, open research problems and include a comprehensive collection of over 1500 references on oscillators and non-sinusoidal waveform generators/relaxation oscillators. Offers readers a single-source reference to everything connected to sinusoidal oscillators and waveform generators, using classical as well as modern electronic circuit building blocks; Provides a state-of-the-art review of a large variety of sinusoidal oscillators and waveform generators; Includes a catalog of over 600 configurations of oscillato...
High-resolution Fracture Characterization Using Elastic Full-waveform Inversion
Zhang, Z.
2017-05-26
Current methodologies to characterize fractures at the reservoir scale have serious limitations in spatial resolution. Here, we propose to estimate both the spatial distribution and physical properties of fractures using full waveform inversion (FWI) of multicomponent surface seismic data. An effective orthorhombic medium with five clusters of vertical fractures distributed in a checkboard fashion is used to test the algorithm. To better understand the inversion results, we analyze the FWI radiation patterns of the fracture weaknesses. A shape regularization term is added to the objective function to improve the inversion for the horizontal weakness, which is otherwise poorly constrained. Alternatively, a simplified model of penny-shaped cracks is used to reduce the nonuniqueness in the inverted weaknesses and achieve a faster convergence.
Pope, Jason E; Falowski, Steven; Deer, Tim R
2015-07-01
In recent years, software development has been key to the next generation of neuromodulation devices. In this review, we will describe the new strategies for electrical waveform delivery for spinal cord stimulation. A systematic literature review was performed using bibliographic databases, limited to the English language and human data, between 2010 and 2014. The literature search yielded three articles on burst stimulation and four articles on high-frequency stimulation. High-frequency and burst stimulation may offer advantages over tonic stimulation, as data suggest improved patient tolerance, comparable increase in function and possible success with a subset of patients refractory to tonic spinal cord stimulation. High-frequency and burst stimulation are new ways to deliver energy to the spinal cord that may offer advantages over tonic stimulation. These may offer new salvage strategies to mitigate spinal cord stimulation failure and improve cost-effectiveness by reducing explant rate.
Accurate Methods for Signal Processing of Distorted Waveforms in Power Systems
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Langella R
2007-01-01
Full Text Available A primary problem in waveform distortion assessment in power systems is to examine ways to reduce the effects of spectral leakage. In the framework of DFT approaches, line frequency synchronization techniques or algorithms to compensate for desynchronization are necessary; alternative approaches such as those based on the Prony and ESPRIT methods are not sensitive to desynchronization, but they often require significant computational burden. In this paper, the signal processing aspects of the problem are considered; different proposals by the same authors regarding DFT-, Prony-, and ESPRIT-based advanced methods are reviewed and compared in terms of their accuracy and computational efforts. The results of several numerical experiments are reported and analysed; some of them are in accordance with IEC Standards, while others use more open scenarios.
An intelligent detection method for high-field asymmetric waveform ion mobility spectrometry.
Li, Yue; Yu, Jianwen; Ruan, Zhiming; Chen, Chilai; Chen, Ran; Wang, Han; Liu, Youjiang; Wang, Xiaozhi; Li, Shan
2017-01-01
In conventional high-field asymmetric waveform ion mobility spectrometry signal acquisition, multi-cycle detection is time consuming and limits somewhat the technique's scope for rapid field detection. In this study, a novel intelligent detection approach has been developed in which a threshold was set on the relative error of α parameters, which can eliminate unnecessary time spent on detection. In this method, two full-spectrum scans were made in advance to obtain the estimated compensation voltage at different dispersion voltages, resulting in a narrowing down of the whole scan area to just the peak area(s) of interest. This intelligent detection method can reduce the detection time to 5-10% of that of the original full-spectrum scan in a single cycle.
Full Waveform Inversion with Multisource Frequency Selection of Marine Streamer Data
Huang, Yunsong
2017-10-27
The theory and practice of multisource full waveform inversion of marine supergathers are described with a frequency-selection strategy. The key enabling property of frequency selection is that it eliminates the crosstalk among sources, thus overcoming the aperture mismatch of marine multisource inversion. Tests on multisource full waveform inversion of synthetic marine data and Gulf of Mexico data show speedups of 4× and 8×, respectively, compared to conventional full waveform inversion.
Analysis of Potential Alternatives to Reduce NASA's Cost of Human Access to Space
1998-01-01
The purpose of this report is to analyze NASA's potential options for significantly reducing the cost of human access to space. The opinions expressed in this report are based on Hawthorne, Krauss & Associates' ("HKA") interaction with NASA and several of its key contractors over the past nine months. This report is not intended to be an exhaustive quantitative analysis of the various options available to NASA. Instead, its purpose is to outline key decision-related issues that the agency should consider prior to making a decision as to which option to pursue. This report attempts to bring a private-sector perspective to bear on the issue of reducing the cost of human access to space. HKA believes that the key to the NASA's success in reducing those costs over the long-term is the involvement of the private-sector incentives and disciplines--which is achieved only through the assumption of risk by the private sector, not through a traditional contractor relationship--is essential to achieve significant long-term cost reductions.
Qualitative analysis of factors that increase and reduce involvement in gambling
Directory of Open Access Journals (Sweden)
Egidijus
2015-12-01
Full Text Available During the rapid development of gambling business, the number of pathological gamblers is increasing as well. The problem of pathological gambling is just as important as alcoholism or drug addiction. However, there is a lack of information and research of this topicin Lithuania. The aim of work: to investigate and analyse the factors that increase or reduce involvement in gambling. Research questions: 1 What factors increase involvement in gambling? 2 What factors reduce involvement in gambling? Critical case sampling was used for selection of the participants. Subjects were required to a have experience of involvement in gambling for at least one year; b have experience of negative impact of gambling on quality of life; c have at least 6 months of gambling abstinence. Five individuals participated in the research; all of them were males who live in Vilnius. Age of the participants varied from 19 to 45. Semi-structured interviews were used to collect data. Interviews were recorded and transcribed verbatim. The matic analysis of the data led to the identification of four major the matic categories: psychological factors; social relations; material well being; quality of life. There search results show that negatyve childhood experience, gambling friends, escaping from various troubles, disputes in family and high financial needs can increase involvement in gambling. Factors that reduce involvement in gambling are: feeling support of social environment, proper evaluation of financial position, awareness of one‘s own addiction to gambling and desire to change life.
Changing diet and physical activity to reduce gestational weight gain: a meta-analysis.
Gardner, B; Wardle, J; Poston, L; Croker, H
2011-07-01
Excessive pregnancy weight gain is associated with adverse maternal and child health outcomes. Intervention developers have assumed that adopting a healthier diet and increasing physical activity in pregnancy can limit weight gain, but evaluations of such interventions have yielded mixed results. Recent reviews of this literature have not identified defining characteristics of effective interventions. We systematically reviewed 10 published controlled trials of interventions that aimed to reduce gestational weight gain through changes in diet or physical activity. Characteristics of the sample, intervention content and delivery, and methodology were categorized. Meta-analysis showed that, overall, diet and physical activity change was effective in reducing gestational weight gain, but there was considerable heterogeneity in outcomes. Our analysis points to sample characteristics and aspects of intervention design, content, delivery and evaluation which differ between studies and may explain variation in effectiveness. Failure to evaluate changes in behaviour or its psychological determinants, and under-reporting of intervention content, may obscure identification of the processes by which weight change is effected. This limits our ability to discern active intervention ingredients. We suggest that behaviour-based gestational weight gain reduction interventions be more systematically designed, evaluated and reported to build on insights from behavioural science. © 2011 The Authors. obesity reviews © 2011 International Association for the Study of Obesity.
Efficacy of Acupuncture in Reducing Preoperative Anxiety: A Meta-Analysis
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Hyojeong Bae
2014-01-01
Full Text Available Background. Acupuncture has been shown to reduce preoperative anxiety in several previous randomized controlled trials (RCTs. In order to assess the preoperative anxiolytic efficacy of acupuncture therapy, this study conducted a meta-analysis of an array of appropriate studies. Methods. Four electronic databases (MEDLINE, EMBASE, CENTRAL, and CINAHL were searched up to February 2014. In the meta-analysis data were included from RCT studies in which groups receiving preoperative acupuncture treatment were compared with control groups receiving a placebo for anxiety. Results. Fourteen publications (N = 1,034 were included. Six publications, using the State-Trait Anxiety Inventory-State (STAI-S, reported that acupuncture interventions led to greater reductions in preoperative anxiety relative to sham acupuncture (mean difference = 5.63, P < .00001, 95% CI [4.14, 7.11]. Further eight publications, employing visual analogue scales (VAS, also indicated significant differences in preoperative anxiety amelioration between acupuncture and sham acupuncture (mean difference = 19.23, P < .00001, 95% CI [16.34, 22.12]. Conclusions. Acupuncture therapy aiming at reducing preoperative anxiety has a statistically significant effect relative to placebo or nontreatment conditions. Well-designed and rigorous studies that employ large sample sizes are necessary to corroborate this finding.
Efficacy of acupuncture in reducing preoperative anxiety: a meta-analysis.
Bae, Hyojeong; Bae, Hyunsu; Min, Byung-Il; Cho, Seunghun
2014-01-01
Background. Acupuncture has been shown to reduce preoperative anxiety in several previous randomized controlled trials (RCTs). In order to assess the preoperative anxiolytic efficacy of acupuncture therapy, this study conducted a meta-analysis of an array of appropriate studies. Methods. Four electronic databases (MEDLINE, EMBASE, CENTRAL, and CINAHL) were searched up to February 2014. In the meta-analysis data were included from RCT studies in which groups receiving preoperative acupuncture treatment were compared with control groups receiving a placebo for anxiety. Results. Fourteen publications (N = 1,034) were included. Six publications, using the State-Trait Anxiety Inventory-State (STAI-S), reported that acupuncture interventions led to greater reductions in preoperative anxiety relative to sham acupuncture (mean difference = 5.63, P anxiety amelioration between acupuncture and sham acupuncture (mean difference = 19.23, P Acupuncture therapy aiming at reducing preoperative anxiety has a statistically significant effect relative to placebo or nontreatment conditions. Well-designed and rigorous studies that employ large sample sizes are necessary to corroborate this finding.
Failure mode and effect analysis in blood transfusion: a proactive tool to reduce risks.
Lu, Yao; Teng, Fang; Zhou, Jie; Wen, Aiqing; Bi, Yutian
2013-12-01
The aim of blood transfusion risk management is to improve the quality of blood products and to assure patient safety. We utilize failure mode and effect analysis (FMEA), a tool employed for evaluating risks and identifying preventive measures to reduce the risks in blood transfusion. The failure modes and effects occurring throughout the whole process of blood transfusion were studied. Each failure mode was evaluated using three scores: severity of effect (S), likelihood of occurrence (O), and probability of detection (D). Risk priority numbers (RPNs) were calculated by multiplying the S, O, and D scores. The plan-do-check-act cycle was also used for continuous improvement. Analysis has showed that failure modes with the highest RPNs, and therefore the greatest risk, were insufficient preoperative assessment of the blood product requirement (RPN, 245), preparation time before infusion of more than 30 minutes (RPN, 240), blood transfusion reaction occurring during the transfusion process (RPN, 224), blood plasma abuse (RPN, 180), and insufficient and/or incorrect clinical information on request form (RPN, 126). After implementation of preventative measures and reassessment, a reduction in RPN was detected with each risk. The failure mode with the second highest RPN, namely, preparation time before infusion of more than 30 minutes, was shown in detail to prove the efficiency of this tool. FMEA evaluation model is a useful tool in proactively analyzing and reducing the risks associated with the blood transfusion procedure. © 2013 American Association of Blood Banks.
Choi, Yun Seok
2011-09-01
Full waveform inversion requires a good estimation of the source wavelet to improve our chances of a successful inversion. This is especially true for an encoded multisource time-domain implementation, which, conventionally, requires separate-source modeling, as well as the Fourier transform of wavefields. As an alternative, we have developed the source-independent time-domain waveform inversion using convolved wavefields. Specifically, the misfit function consists of the convolution of the observed wavefields with a reference trace from the modeled wavefield, plus the convolution of the modeled wavefields with a reference trace from the observed wavefield. In this case, the source wavelet of the observed and the modeled wavefields are equally convolved with both terms in the misfit function, and thus, the effects of the source wavelets are eliminated. Furthermore, because the modeled wavefields play a role of low-pass filtering, the observed wavefields in the misfit function, the frequency-selection strategy from low to high can be easily adopted just by setting the maximum frequency of the source wavelet of the modeled wavefields; and thus, no filtering is required. The gradient of the misfit function is computed by back-propagating the new residual seismograms and applying the imaging condition, similar to reverse-time migration. In the synthetic data evaluations, our waveform inversion yields inverted models that are close to the true model, but demonstrates, as predicted, some limitations when random noise is added to the synthetic data. We also realized that an average of traces is a better choice for the reference trace than using a single trace. © 2011 Society of Exploration Geophysicists.
Zhang, Hao; Zou, Weiwen; Chen, Jianping
2015-03-15
We propose a method to generate a widely tunable linearly chirped microwave waveform based on spectral filtering and unbalanced dispersion. Heterodyne beating between two differently dispersed optical pulses in a photodetector produces the linearly chirped microwave waveform. Desired waveforms with flexible and independent control of the center frequency and sweep bandwidth can be obtained by simply tuning two optical filters. Simulation and experimental investigations are carried out, and the results are in good agreement. The measured microwave waveform has ∼5.2-ns pulse duration and ∼64-GHz sweep bandwidth, corresponding to a time-bandwidth product of ∼166.4 and a compression ratio of ∼248.
Cook, L B
1997-12-01
The degree of rebreathing in Mapleson A, C and D breathing systems for sinusoidal and exponential flow waveforms is analysed mathematically. The effects of altering the I:E ratio and of introducing an expiratory pause are investigated. The results for sinusoidal waveforms closely resemble those for a square wave. Exponential flow waveforms produce results similar to triangular flow waveforms. The Mapleson A system is always the most efficient. The Mapleson C system is efficient when the I:E ratio is 1:1, becoming less efficient with longer expiration and very inefficient with an expiratory pause. The Mapleson D system becomes efficient when the expiratory pause is long.
GO JUPITER PWS EDITED EDR 1KHZ WAVEFORM RECEIVER V1.0
National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...
GO JUPITER PWS EDITED EDR 10KHZ WAVEFORM RECEIVER V1.0
National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...
GO JUPITER PWS EDITED EDR 80KHZ WAVEFORM RECEIVER V1.0
National Aeronautics and Space Administration — This data set includes wideband waveform measurements from the Galileo plasma wave receiver obtained during Jupiter orbital operations. These data were obtained...
Directory of Open Access Journals (Sweden)
Giovanni Corona
Full Text Available Hyponatremia is the most common electrolyte disorder and it is associated with increased morbidity and mortality. However, there is no clear demonstration that the improvement of serum sodium concentration ([Na(+] counteracts the increased risk of mortality associated with hyponatremia. Thus, we performed a meta-analysis that included the published studies that addressed the effect of hyponatremia improvement on mortality.A Medline, Embase and Cochrane search was performed to retrieve all English-language studies of human subjects published up to June 30th 2014, using the following words: "hyponatremia", "hyponatraemia", "mortality", "morbidity" and "sodium". Fifteen studies satisfied inclusion criteria encompassing a total of 13,816 patients. The identification of relevant abstracts, the selection of studies and the subsequent data extraction were performed independently by two of the authors, and conflicts resolved by a third investigator. Across all fifteen studies, any improvement of hyponatremia was associated with a reduced risk of overall mortality (OR=0.57[0.40-0.81]. The association was even stronger when only those studies (n=8 reporting a threshold for serum [Na(+] improvement to >130 mmol/L were considered (OR=0.51[0.31-0.86]. The reduced mortality rate persisted at follow-up (OR=0.55[0.36-0.84] at 12 months. Meta-regression analyses showed that the reduced mortality associated with hyponatremia improvement was more evident in older subjects and in those with lower serum [Na(+] at enrollment.This meta-analysis documents for the first time that improvement in serum [Na(+] in hyponatremic patients is associated with a reduction of overall mortality.
Meta-analysis: Does garlic intake reduce risk of gastric cancer?
Kodali, R T; Eslick, Guy D
2015-01-01
In the past 2 decades, various epidemiological studies investigated whether garlic can positively modify the risk of gastric cancer. Garlic contains numerous sulfide compounds, including diallyl trisulfide, which have anticarcinogenic properties. We conducted a meta-analysis to determine if garlic intake reduces the risk of gastric cancer. An electronic search of MEDLINE, PubMed, and EMBASE to June 2014 was completed. There were 14 case control studies, 2 randomized controlled studies, and 1 cohort study that fulfilled our inclusion criteria. We used a random effects model to calculate pooled odds ratios (OR) and 95% confidence intervals (CIs) for risk of gastric cancer with garlic consumption. Meta-analysis of a total of 8,621 cases and 14,889 controls was conducted. Significant variability in duration of garlic intake and reference categories for amount of intake was noted. High, low, and any garlic intake were all associated with reduced risk of gastric cancer. High intake had the most significant risk reduction, OR = 0.49 (95% CI: 0.38-0.62). Heterogeneity was low (I² = 30.85, P = 0.17). A more modest risk reduction was associated with low intake, OR = 0.75 (95% CI: 0.58-0.97). Half of the studies did not separate garlic intake into high or low amounts, intake was only noted as consumption vs. non-consumption. Any amount of consumption still showed a risk reduction similar to low intake, OR = 0.77 (95% CI: 0.60-1.00). Low and any amount of consumption showed moderate heterogeneity (58% and 45%, respectively). Garlic intake appears to be associated with reduced risk of gastric cancer. Further high quality studies are required to confirm this finding and to assess the amount of garlic that needs to be consumed for protective effect.
Directory of Open Access Journals (Sweden)
Susanne Goebels
2017-01-01
Full Text Available Purpose. To build new models with the Ocular Response Analyzer (ORA waveform parameters to create new indices analogous to established topographic keratoconus indices. Method. Biomechanical, tomographic, and topographic measurements of 505 eyes from the Homburger Keratoconus Centre were included. Thirty-seven waveform parameters (WF were derived from the biomechanical measurement with the ORA. Area under curve (ROC, receiver operating characteristic was used to quantify the screening performance. A logistic regression analysis was used to create two new keratoconus prediction models based on these waveform parameters to resample the clinically established keratoconus indices from Pentacam and TMS-5. Results. ROC curves show the best results for the waveform parameters p1area, p2area, h1, h2, dive1, mslew1, aspect1, aplhf, and dslope1. The new keratoconus prediction model to resample the Pentacam topographic keratoconus index (TKC was WFTKC = −4.068 + 0.002 × p2area − 0.005 × dive1 − 0.01 × h1 − 2.501 × aplhf, which achieves a sensitivity of 90.3% and specificity of 89.4%; to resample the TMS-5 keratoconus classification index (KCI it was WFKCI = −3.606 + 0.002 × p2area, which achieves a sensitivity of 75.4% and a specificity of 81.8%. Conclusion. In addition to the biomechanically provided Keratoconus Index two new indices which were based on the topographic gold standards (either Pentacam or TMS-5 were created. Of course, these do not replace the original topographic measurement.
Goebels, Susanne; Eppig, Timo; Wagenpfeil, Stefan; Cayless, Alan; Seitz, Berthold; Langenbucher, Achim
2017-01-01
Purpose. To build new models with the Ocular Response Analyzer (ORA) waveform parameters to create new indices analogous to established topographic keratoconus indices. Method. Biomechanical, tomographic, and topographic measurements of 505 eyes from the Homburger Keratoconus Centre were included. Thirty-seven waveform parameters (WF) were derived from the biomechanical measurement with the ORA. Area under curve (ROC, receiver operating characteristic) was used to quantify the screening performance. A logistic regression analysis was used to create two new keratoconus prediction models based on these waveform parameters to resample the clinically established keratoconus indices from Pentacam and TMS-5. Results. ROC curves show the best results for the waveform parameters p1area, p2area, h1, h2, dive1, mslew1, aspect1, aplhf, and dslope1. The new keratoconus prediction model to resample the Pentacam topographic keratoconus index (TKC) was WFTKC = -4.068 + 0.002 × p2area - 0.005 × dive1 - 0.01 × h1 - 2.501 × aplhf, which achieves a sensitivity of 90.3% and specificity of 89.4%; to resample the TMS-5 keratoconus classification index (KCI) it was WFKCI = -3.606 + 0.002 × p2area, which achieves a sensitivity of 75.4% and a specificity of 81.8%. Conclusion. In addition to the biomechanically provided Keratoconus Index two new indices which were based on the topographic gold standards (either Pentacam or TMS-5) were created. Of course, these do not replace the original topographic measurement.
Continuous-waveform constant-current isolated physiological stimulator
Holcomb, Mark R.; Devine, Jack M.; Harder, Rene; Sidorov, Veniamin Y.
2012-04-01
We have developed an isolated continuous-waveform constant-current physiological stimulator that is powered and controlled by universal serial bus (USB) interface. The stimulator is composed of a custom printed circuit board (PCB), 16-MHz MSP430F2618 microcontroller with two integrated 12-bit digital to analog converters (DAC0, DAC1), high-speed H-Bridge, voltage-controlled current source (VCCS), isolated USB communication and power circuitry, two isolated transistor-transistor logic (TTL) inputs, and a serial 16 × 2 character liquid crystal display. The stimulators are designed to produce current stimuli in the range of ±15 mA indefinitely using a 20V source and to be used in ex vivo cardiac experiments, but they are suitable for use in a wide variety of research or student experiments that require precision control of continuous waveforms or synchronization with external events. The device was designed with customization in mind and has features that allow it to be integrated into current and future experimental setups. Dual TTL inputs allow replacement by two or more traditional stimulators in common experimental configurations. The MSP430 software is written in C++ and compiled with IAR Embedded Workbench 5.20.2. A control program written in C++ runs on a Windows personal computer and has a graphical user interface that allows the user to control all aspects of the device.
Full waveform tomography of the South Atlantic upper mantle
Colli, Lorenzo; Bunge, Hans-Peter
2015-04-01
We developed a full waveform tomography of the upper mantle beneath the South Atlantic region using an adjoint method. This required 5000 wavefield simulations and a total of 750 thousand CPU-hours. The 3D seismic structure thus retrieved can help us answering various key questions concerning the geodynamic evolution of the region: (1) How and to which extent does the South Atlantic plume system feed the asthenosphere in the oceanic basin and adjacent regions? (2) What are the current thermal states of the lithosphere below the Walvis Ridge and the Etendeka and Paraná continental flood basalts? (3) Is the asthenosphere thin or thick? (4) What is the characteristic planform of asthenospheric flow? (5) Is the prominent topographic gradient across the South Atlantic region from Africa to South America explicable solely in terms of lower mantle structure, or do we also find a systematic gradient in upper mantle heterogeneity across the ocean basin? Full waveform tomography allows us to exploit information from seismograms in a very efficient way. Our approach is thus well suited for regions with comparatively low data coverage such as the South Atlantic.
3D frequency-domain ultrasound waveform tomography breast imaging
Sandhu, Gursharan Yash; West, Erik; Li, Cuiping; Roy, Olivier; Duric, Neb
2017-03-01
Frequency-domain ultrasound waveform tomography is a promising method for the visualization and characterization of breast disease. It has previously been shown to accurately reconstruct the sound speed distributions of breasts of varying densities. The reconstructed images show detailed morphological and quantitative information that can help differentiate different types of breast disease including benign and malignant lesions. The attenuation properties of an ex vivo phantom have also been assessed. However, the reconstruction algorithms assumed a 2D geometry while the actual data acquisition process was not. Although clinically useful sound speed images can be reconstructed assuming this mismatched geometry, artifacts from the reconstruction process exist within the reconstructed images. This is especially true for registration across different modalities and when the 2D assumption is violated. For example, this happens when a patient's breast is rapidly sloping. It is also true for attenuation imaging where energy lost or gained out of the plane gets transformed into artifacts within the image space. In this paper, we will briefly review ultrasound waveform tomography techniques, give motivation for pursuing the 3D method, discuss the 3D reconstruction algorithm, present the results of 3D forward modeling, show the mismatch that is induced by the violation of 3D modeling via numerical simulations, and present a 3D inversion of a numerical phantom.
Precisely synchronous and cascadable multi-channel arbitrary waveform generator
Liu, Ke; Tian, Shulin; Guo, Guangkun; Xiao, Yindong
2017-03-01
The output bandwidth and the capability to generate multiple analog outputs with accurately adjustable relative phase are important specifications of arbitrary waveform generator (AWG). To increase the output bandwidth, AWG with a multi-memory paralleled direct digital synthesizer structure (DDS) was proposed to break through operating speed limitations of memory and field programmable gate array. But this structure does complicate synchronization of the analog outputs. This paper proposes a structure for synchronization of the outputs of multi-channel high speed AWG that generates arbitrary waveforms using a multi-memory paralleled DDS. Careful distribution of the clock and trigger signals enables elimination of the random initial phase caused by the frequency divider. Based on this structure, a four-channel 600 mega samples per second AWG is designed. An embedded clock synchronization calibration module is designed to eliminate the random phase difference caused by a frequency divider inside a digital-to-analog converter. The AWG provides a 240 MHz bandwidth, 16 mega-samples storage depth, inter-channel initial skew accuracy less than 150 ps, and 0.0001° phase resolution, which can be used to generate two pairs of I/Q signals or a pair of differential I/Q signals for the quadrature modulator. Additionally, more AWGs can be cascaded to obtain more output channels with an output timing skew between adjacent channels of less than 1.6 ns.
On the generation of waveforms having comb-shaped spectra
Black, Bruce A.
1988-05-01
Two techniques, direct sequence and spread spectrum and frequency hopping are widely used to provide an antijam capability for communications systems. To test the effectiveness of such systems, suitable jammers must be devised. A frequency hopping system can be jammed by wideband noise, by a following frequency hopped carrier (if the hopper is slow enough), or by a multitone jamming signal. Multitone jamming signals are considered advantageous in that jamming power is not wasted on frequencies never visited by the frequency hopper, as is the case when wideband noise is used. This report considers several classes of waveforms having power spectra that are approximately comb-shaped. The report relates the properties of the comb spectrum to the time-domain properties of the waveforms. These are the repeated pseudorandom sequence, used to modulate a carrier, and the frequency-swept sinusoid. A good quality comb spectrum should have uniformly strong teeth over its passband, and the spectrum should fall away rapidly at the band edges. To minimize the distortion caused by saturating power amplifiers, it is helpful is the time-domain function has a constant envelope. It is shown that a pseudorandom sequence that is low-pass filtered prior to modulation can produce a very uniform comb with sharp band edges, provided that the required width of the comb is not excessive. A swept-frequency sinusoid can produce a comb of very wide bandwidth, also with sharp band edges.
Hepatic arterial waveforms on early posttransplant Doppler ultrasound.
Hedegard, Wade C; Bhatt, Shweta; Saad, Wael; Rubens, Deborah; Dogra, Vikram
2011-03-01
To determine the significance of spectral Doppler hepatic artery waveforms obtained in the first 10 days after primary liver transplantation and to determine the best early predictor of hepatic arterial thrombosis (HAT). A total of 645 patients were retrospectively followed up to 1 year after liver transplantation. Doppler waveforms of the hepatic arteries were categorized as normal, abnormally elevated, not visualized, or with resistive index (RI) hepatic artery on Doppler evaluation and 56 (8.7%) developed HAT or stenosis within the first year after transplantation. Odds ratios (ORs) demonstrate that a single nonvisualized hepatic artery (OR, 9.66; 95% confidence interval [CI], 4.51-20.70) has a much higher incidence of HAT in the first 10 days after transplantation compared to low RI (OR, 1.93; 95% CI, 0.77-4.79)] or high RI (OR, 1.06; 95% CI, 0.44-2.55]. The loss or reversal of diastolic flow on Doppler ultrasound performed in the first 10 days after transplantation does not seem to correlate with active or impending HAT. Absence of hepatic arterial flow Doppler signal in the first 10 days after liver transplantation is associated with higher incidence of thrombosis than previously demonstrated, whereas persistently high diastolic flow early on seems to be more significant and leads to further hepatic arterial complications than decreased diastolic flow.
Acquisition of L2 Japanese Geminates: Training with Waveform Displays
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Miki Motohashi-Saigo
2009-06-01
Full Text Available The value of waveform displays as visual feedback was explored in a training study involving perception and production of L2 Japanese by beginning-level L1 English learners. A pretest-posttest design compared auditory-visual (AV and auditory-only (A-only Web-based training. Stimuli were singleton and geminate /t,k,s/ followed by /a,u/ in two conditions (isolated words, carrier sentences. Fillers with long vowels were included. Participants completed a forced-choice identification task involving minimal triplets: singletons, geminates, long vowels (e.g., sasu, sassu, saasu. Results revealed a significant improvement in geminate identification following training, especially for AV; b significant effect of geminate (lowest scores for /s/; c no significant effect of condition; and d no significant improvement for the control group. Most errors were misperceptions of geminates as long vowels. Test of generalization revealed 5% decline in accuracy for AV and 14% for A-only. Geminate production improved significantly (especially for AV based on rater judgments; improvement was greatest for /k/ and smallest for /s/. Most production errors involved substitution of a singleton for a geminate. Post-study interviews produced positive comments on Web-based training. Waveforms increased awareness of durational differences. Results support the effectiveness of auditory-visual input in L2 perception training with transfer to novel stimuli and improved production.
Elastic reflection based waveform inversion with a nonlinear approach
Guo, Qiang
2017-08-16
Full waveform inversion (FWI) is a highly nonlinear problem due to the complex reflectivity of the Earth, and this nonlinearity only increases under the more expensive elastic assumption. In elastic media, we need a good initial P-wave velocity and even a better initial S-wave velocity models with accurate representation of the low model wavenumbers for FWI to converge. However, inverting for the low wavenumber components of P- and S-wave velocities using reflection waveform inversion (RWI) with an objective to fit the reflection shape, rather than produce reflections, may mitigate the limitations of FWI. Because FWI, performing as a migration operator, is in preference of the high wavenumber updates along reflectors. We propose a nonlinear elastic RWI that inverts for both the low wavenumber and perturbation components of the P- and S-wave velocities. To generate the full elastic reflection wavefields, we derive an equivalent stress source made up by the inverted model perturbations and incident wavefields. We update both the perturbation and propagation parts of the velocity models in a nested fashion. Applications on synthetic isotropic models and field data show that our method can efficiently update the low and high wavenumber parts of the models.
Can no-tillage reduce nitrate and phosphorus loss? A meta-analysis
Daryanto, S.; Wang, L.; Jacinthe, P. A.
2016-12-01
Alternative land management practices, particularly no-tillage (NT), have been promoted to improve yield and to reduce nitrate (NO3-) and phosphorus (P) to the environment. The outcomes, however, have been variable. To address the uncertainty, we conducted a meta-analysis to obtain robust results of NT on reducing NO3- and P loss in comparison with conventional tillage (CT) using hydrological condition, transport pathway, soil texture, tillage duration, crop species, and their interactions as the co-varying factors. Overall, NT was more efficient than CT in reducing NO3- leaching via groundwater (-16%) and in deep soil water (-26%), and from coarse- (-20%) and medium-textured soils (-18%). NT management, however, could not reduce NO3- loss from runoff and fine-textured soils, likely due to crust and macropores development. While we expected that greater NO3- reduction would proportionally correspond with the duration of NT application, results might vary depending on transport pathway. The effect of NT on NO3- loss was more pronounced during wet years and interacted with transport pathway and soil texture. The effect of crop species was less significant in determining NO3- loss, particularly when sub-surface artificial drainage was applied. In contrast to NO3-, NT management increased dissolved P loss regardless of all the co-varying factors and even at greater extent when the fields were planted with soybean. This study provides the first comprehensive assessment of NT on nutrient loss from agricultural fields and suggests that complementary land management practices in combination with NT are necessary to minimize nutrient loss.
Finite element analysis of rapid canine retraction through reducing resistance and distraction
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Junjie XUE
2014-01-01
Full Text Available Objective: The aims of this study were to compare different surgical approaches to rapid canine retraction by designing and selecting the most effective method of reducing resistance by a three-dimensional finite element analysis. Material and Methods: Three-dimensional finite element models of different approaches to rapid canine retraction by reducing resistance and distraction were established, including maxillary teeth, periodontal ligament, and alveolar. The models were designed to dissect the periodontal ligament, root, and alveolar separately. A 1.5 N force vector was loaded bilaterally to the center of the crown between first molar and canine, to retract the canine distally. The value of total deformation was used to assess the initial displacement of the canine and molar at the beginning of force loading. Stress intensity and force distribution were analyzed and evaluated by Ansys 13.0 through comparison of equivalent (von Mises stress and maximum shear stress. Results: The maximum value of total deformation with the three kinds of models occurred in the distal part of the canine crown and gradually reduced from the crown to the apex of the canine; compared with the canines in model 3 and model 1, the canine in model 2 had the maximum value of displacement, up to 1.9812 mm. The lowest equivalent (von Mises stress and the lowest maximum shear stress were concentrated mainly on the distal side of the canine root in model 2. The distribution of equivalent (von Mises stress and maximum shear stress on the PDL of the canine in the three models was highly concentrated on the distal edge of the canine cervix. . Conclusions: Removal of the bone in the pathway of canine retraction results in low stress intensity for canine movement. Periodontal distraction aided by surgical undermining of the interseptal bone would reduce resistance and effectively accelerate the speed of canine retraction.
The use of synthetic master events for waveform cross correlation
Rozhkov, Mikhail; Bobrov, Dmitry; Kitov, Ivan
2013-04-01
It has been clearly demonstrated that waveform cross correlation substantially improves signal detection, phase association and event building. These processes are inherently related to the Comprehensive Nuclear-Test-Ban Treaty (CTBT) monitoring. The workhorse of cross correlation is the set of seismic master events (earthquakes or explosions) with high quality waveform templates recorded at array stations of the International Monitoring System (IMS). For the monitoring to be globally uniform, these master events have to be evenly distributed and their template waveforms should be representative and pure. However, global seismicity is characterized by a non-uniform distribution. Therefore, the master events selected from the Reviewed Event Bulletin (REB) produced by the International Data Centre (IDC) can be found in the areas constrained by the global seismicity. There are two principal possibilities to populate the globe with master events: to replicate real REB events or to build synthetic events. Here we compare the performance of these two approaches as applied to the aftershock sequence of the April 11, 2012 Sumatera earthquake. To compute synthetic waveforms, we use AK135 teleseismic velocity model and local CRUST-2 models for source and receiver, and four different source functions representing three different source mechanisms for earthquakes and one for explosion. The synthetic modeling is performed for teleseismic events and based on the stationary phase approximation to a wave equation solution developed by J. Hudson. The grid covering the aftershock area consists of 16 points. For each grid point, we find detections associated with real, replicated, and four versions of synthetic master events at seven IMS array stations, and then build event hypothesis using the Local Association (LA) procedure based on the clustering of origin times as estimated by back projection of the relevant arrival times with known master/station travel times. Then all
Data analysis strategies for reducing the influence of the bias in cross-cultural research.
Sindik, Josko
2012-03-01
In cross-cultural research, researchers have to adjust the constructs and associated measurement instruments that have been developed in one culture and then imported for use in another culture. Importing concepts from other cultures is often simply reduced to language adjustment of the content in the items of the measurement instruments that define a certain (psychological) construct. In the context of cross-cultural research, test bias can be defined as a generic term for all nuisance factors that threaten the validity of cross-cultural comparisons. Bias can be an indicator that instrument scores based on the same items measure different traits and characteristics across different cultural groups. To reduce construct, method and item bias,the researcher can consider these strategies: (1) simply comparing average results in certain measuring instruments; (2) comparing only the reliability of certain dimensions of the measurement instruments, applied to the "target" and "source" samples of participants, i.e. from different cultures; (3) comparing the "framed" factor structure (fixed number of factors) of the measurement instruments, applied to the samples from the "target" and "source" cultures, using explorative factor analysis strategy on separate samples; (4) comparing the complete constructs ("unframed" factor analysis, i.e. unlimited number of factors) in relation to their best psychometric properties and the possibility of interpreting (best suited to certain cultures, applying explorative strategy of factor analysis); or (5) checking the similarity of the constructs in the samples from different cultures (using structural equation modeling approach). Each approach has its advantages and disadvantages. The advantages and lacks of each approach are discussed.
Challenges in reducing the computational time of QSTS simulations for distribution system analysis.
Energy Technology Data Exchange (ETDEWEB)
Deboever, Jeremiah [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiaochen [Georgia Inst. of Technology, Atlanta, GA (United States); Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States); Therrien, Francis [CME International T& D, St. Bruno, QC (Canada)
2017-06-01
The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10 to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.
3D elastic-orthorhombic anisotropic full-waveform inversion: Application to field OBC data
Oh, Juwon
2016-09-06
For the purpose of extracting higher resolution information from a 3D field data set, we apply a 3D elastic orthorhombic (ORT) anisotropic full waveform inversion (FWI) to hopefully better represent the physics of the Earth. We utilize what we consider as the optimal parameterization for surface acquired seismic data over a potentially orthorhombic media. This parameterization admits the possibility of incorporating a hierarchical implementation moving from higher anisotropy symmetry to lower ones. From the analysis of the radiation pattern of this new parameterization, we focus the inversion of the 3D data on the parameters that may have imprint on the data with minimal tradeoff, and as a result we invert for the horizontal P-wave velocity model, an ε1 model, its orthorhombic deviation, and the shear wave velocity. The inverted higher resolution models provide reasonable insights of the medium.
Nonlinear Acoustic Response of an Aircraft Fuselage Sidewall Structure by a Reduced-Order Analysis
Przekop, Adam; Rizzi, Stephen A.; Groen, David S.
2006-01-01
A reduced-order nonlinear analysis of a structurally complex aircraft fuselage sidewall panel is undertaken to explore issues associated with application of such analyses to practical structures. Of primary interest is the trade-off between computational efficiency and accuracy. An approach to modal basis selection is offered based upon the modal participation in the linear regime. The nonlinear static response to a uniform pressure loading and nonlinear random response to a uniformly distributed acoustic loading are computed. Comparisons of the static response with a nonlinear static solution in physical degrees-of-freedom demonstrate the efficacy of the approach taken for modal basis selection. Changes in the modal participation as a function of static and random loading levels suggest a means for improvement in the basis selection.
eRDF Analyser: An interactive GUI for electron reduced density function analysis
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Janaki Shanmugam
2017-01-01
Full Text Available eRDF Analyser is an interactive MATLAB GUI for reduced density function (RDF or pair distribution function (PDF analysis of amorphous and polycrystalline materials to study their local structure. It is developed as an integrated tool with an easy-to-use interface that offers a streamlined approach to extract RDF from electron diffraction data without the need for external routines. The software incorporates recent developments in scattering factor parameterisation and an automated fitting routine for the atomic scattering curve. It also features an automated optimisation routine for determination of the position of the centre of diffraction patterns recorded using both central and off-centre locations of the incident beam. It is available in both open source code (MATLAB m-file and executable form.
The Effectiveness of Aromatherapy in Reducing Pain: A Systematic Review and Meta-Analysis
Sheafer, Heather; Tepper, Deborah
2016-01-01
Background. Aromatherapy refers to the medicinal or therapeutic use of essential oils absorbed through the skin or olfactory system. Recent literature has examined the effectiveness of aromatherapy in treating pain. Methods. 12 studies examining the use of aromatherapy for pain management were identified through an electronic database search. A meta-analysis was performed to determine the effects of aromatherapy on pain. Results. There is a significant positive effect of aromatherapy (compared to placebo or treatments as usual controls) in reducing pain reported on a visual analog scale (SMD = −1.18, 95% CI: −1.33, −1.03; p aromatherapy is more consistent for treating nociceptive (SMD = −1.57, 95% CI: −1.76, −1.39, p aromatherapy is most effective in treating postoperative pain (SMD = −1.79, 95% CI: −2.08, −1.51, p aromatherapy can successfully treat pain when combined with conventional treatments. PMID:28070420
eRDF Analyser: An interactive GUI for electron reduced density function analysis
Shanmugam, Janaki; Borisenko, Konstantin B.; Chou, Yu-Jen; Kirkland, Angus I.
eRDF Analyser is an interactive MATLAB GUI for reduced density function (RDF) or pair distribution function (PDF) analysis of amorphous and polycrystalline materials to study their local structure. It is developed as an integrated tool with an easy-to-use interface that offers a streamlined approach to extract RDF from electron diffraction data without the need for external routines. The software incorporates recent developments in scattering factor parameterisation and an automated fitting routine for the atomic scattering curve. It also features an automated optimisation routine for determination of the position of the centre of diffraction patterns recorded using both central and off-centre locations of the incident beam. It is available in both open source code (MATLAB m-file) and executable form.
Corbijn van Willenswaard, Kyrsten; Lynn, Fiona; McNeill, Jenny; McQueen, Karen; Dennis, Cindy-Lee; Lobel, Marci; Alderdice, Fiona
2017-07-27
Stress and anxiety are common in pregnancy and shown to have adverse effects on maternal and infant health outcomes. The aim of this review and meta-analysis was to assess the effectiveness of music-based interventions in reducing levels of stress or anxiety among pregnant women. Six databases were searched using key terms relating to pregnancy, psychological stress, anxiety and music. Inclusion criteria were randomised controlled or quasi-experimental trials that assessed the effect of music during pregnancy and measured levels of psychological stress or anxiety as a primary or secondary outcome. Two authors independently assessed and extracted data. Quality assessment was performed using The Cochrane Collaboration risk of bias criteria. Meta-analyses were conducted to assess stress and anxiety reduction following a music-based intervention compared to a control group that received routine antenatal care. Five studies with 1261 women were included. Music interventions significantly reduced levels of maternal anxiety (Standardised Mean Difference (SMD): -0.21; 95% Confidence Interval (CI) -0.39, -0.03; p = 0.02). There was no significant effect on general stress (SMD: -0.08; 95% CI -0.25, 0.09; p = 0.35) or pregnancy-specific stress (SMD: -0.02; 95% CI -0.19, 0.15; p = 0.80). The methodological quality of included studies was moderate to weak, all studies having a high or unclear risk of bias in allocation concealment, blinding and selective outcome reporting. There is evidence that music-based interventions may reduce anxiety in pregnancy; however, the methodological quality of the studies was moderate to weak. Additional research is warranted focusing on rigour of assessment, intensity of interventions delivered and methodological limitations.
Nabagiez, John P; Shariff, Masood A; Molloy, William J; Demissie, Seleshi; McGinn, Joseph T
2016-09-01
A physician assistant home care (PAHC) program providing house calls was initiated to reduce hospital readmissions after adult cardiac surgery. The purpose of our study was to compare 30-day PAHC and pre-PAHC readmission rate, length of stay, and cost. Patients who underwent adult cardiac surgery in the 48 months from September 2008 through August 2012 were retrospectively reviewed using pre-PAHC patients as the control group. Readmission rate, length of stay, and health care cost, as measured by hospital billing, were compared between groups matched with propensity score. Of the 1,185 patients who were discharged directly home, 155 (13%) were readmitted. Total readmissions for the control group (n = 648) was 101 patients (16%) compared with the PAHC group (n = 537) total readmissions of 54 (10%), a 38% reduction in the rate of readmission (p = 0.0049). Propensity score matched groups showed a rate reduction of 41% with 17% (62 of 363) for the control compared with 10% (37 of 363) for the PAHC group (p = 0.0061). The average hospital bill per readmission was $39,100 for the control group and $56,600 for the PAHC group (p = 0.0547). The cost of providing home visits was $25,300 for 363 propensity score matched patients. The PAHC program reduced the 30-day readmission rate by 41% for propensity score matched patients. Analysis demonstrated a savings of $977,500 at a cost of $25,300 over 2 years, or $39 in health care saved, in terms of hospital billing, for every $1 spent. Therefore, a home visit by a cardiac surgical physician assistant is a cost-effective strategy to reduce readmissions after cardiac surgery. Copyright © 2016 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
A Healthy Dietary Pattern Reduces Lung Cancer Risk: A Systematic Review and Meta-Analysis
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Yanlai Sun
2016-03-01
Full Text Available Background: Diet and nutrients play an important role in cancer development and progress; a healthy dietary pattern has been found to be associated with several types of cancer. However, the association between a healthy eating pattern and lung cancer risk is still unclear. Objective: Therefore, we conducted a systematic review with meta-analysis to evaluate whether a healthy eating pattern might reduce lung cancer risk. Methods: We identified relevant studies from the PubMed and Embase databases up to October 2015, and the relative risks were extracted and combined by the fixed-effects model when no substantial heterogeneity was observed; otherwise, the random-effects model was employed. Subgroup and publication bias analyses were also performed. Results: Finally, eight observational studies were included in the meta-analysis. The pooled relative risk of lung cancer for the highest vs. lowest category of healthy dietary pattern was 0.81 (95% confidence interval, CI: 0.75–0.86, and no significant heterogeneity was detected. The relative risks (RRs for non-smokers, former smokers and current smokers were 0.89 (95% CI: 0.63–1.27, 0.74 (95% CI: 0.62–0.89 and 0.86 (95% CI: 0.79–0.93, respectively. The results remained stable in subgroup analyses by other confounders and sensitivity analysis. Conclusions: The results of our meta-analysis suggest that a healthy dietary pattern is associated with a lower lung cancer risk, and they provide more beneficial evidence for changing the diet pattern in the general population.
Laamiri, Imen; Khouaja, Anis; Messaoud, Hassani
2015-03-01
In this paper we provide a convergence analysis of the alternating RGLS (Recursive Generalized Least Square) algorithm used for the identification of the reduced complexity Volterra model describing stochastic non-linear systems. The reduced Volterra model used is the 3rd order SVD-PARAFC-Volterra model provided using the Singular Value Decomposition (SVD) and the Parallel Factor (PARAFAC) tensor decomposition of the quadratic and the cubic kernels respectively of the classical Volterra model. The Alternating RGLS (ARGLS) algorithm consists on the execution of the classical RGLS algorithm in alternating way. The ARGLS convergence was proved using the Ordinary Differential Equation (ODE) method. It is noted that the algorithm convergence canno׳t be ensured when the disturbance acting on the system to be identified has specific features. The ARGLS algorithm is tested in simulations on a numerical example by satisfying the determined convergence conditions. To raise the elegies of the proposed algorithm, we proceed to its comparison with the classical Alternating Recursive Least Squares (ARLS) presented in the literature. The comparison has been built on a non-linear satellite channel and a benchmark system CSTR (Continuous Stirred Tank Reactor). Moreover the efficiency of the proposed identification approach is proved on an experimental Communicating Two Tank system (CTTS). Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Analysis of world terror networks from the reduced Google matrix of Wikipedia
El Zant, Samer; Frahm, Klaus M.; Jaffrès-Runser, Katia; Shepelyansky, Dima L.
2018-01-01
We apply the reduced Google matrix method to analyze interactions between 95 terrorist groups and determine their relationships and influence on 64 world countries. This is done on the basis of the Google matrix of the English Wikipedia (2017) composed of 5 416 537 articles which accumulate a great part of global human knowledge. The reduced Google matrix takes into account the direct and hidden links between a selection of 159 nodes (articles) appearing due to all paths of a random surfer moving over the whole network. As a result we obtain the network structure of terrorist groups and their relations with selected countries including hidden indirect links. Using the sensitivity of PageRank to a weight variation of specific links we determine the geopolitical sensitivity and influence of specific terrorist groups on world countries. The world maps of the sensitivity of various countries to influence of specific terrorist groups are obtained. We argue that this approach can find useful application for more extensive and detailed data bases analysis.
Shi, Xiuqin; Xue, Wenhua; Liang, Shuhong; Zhao, Jie; Zhang, Xiaojian
2016-12-28
According to previous meta-analyses, coffee consumption reduces the risk of type 2 diabetes mellitus. However, the underlying mechanism remains unknown. Whether caffeine, the key ingredient in coffee, has a beneficial effect on the glycemic homeostasis and the anti-diabetic effect is particularly controversial. The aim of this study was to summarize the effect of acute caffeine ingestion on insulin sensitivity in healthy men. A comprehensive literature search for papers published before April 2016 was conducted in EMBASE, PubMed, and Cochrane Library databases. Randomized controlled trials (RCTs) that investigated the effect of caffeine on insulin sensitivity in healthy humans without diabetes were included. A random effects meta-analysis was conducted using Review Manager 5.3. The search yielded 7 RCTs in which caffeine intake was the single variant. Compared with placebo, caffeine intake significantly decreased the insulin sensitivity index, with a standardized mean difference of -2.06 (95% confidence interval -2.67 to -1.44, I2 = 49%, P for heterogeneity = 0.06). Acute caffeine ingestion reduces insulin sensitivity in healthy subjects. Thus, in the short term, caffeine might shift glycemic homeostasis toward hyperglycemia. Long-term trials investigating the role of caffeine in the anti-diabetic effect of coffee are needed.
Health care failure mode and effect analysis to reduce NICU line-associated bloodstream infections.
Chandonnet, Celeste J; Kahlon, Prerna S; Rachh, Pratik; Degrazia, Michele; Dewitt, Eileen C; Flaherty, Kathleen A; Spigel, Nadine; Packard, Stephanie; Casey, Denise; Rachwal, Christine; Agrawal, Pankaj B
2013-06-01
Central line-associated bloodstream infections (CLABSIs) in NICU result in increased mortality, morbidity, and length of stay. Our NICU experienced an increase in the number of CLABSIs over a 2-year period. We sought to reduce risks for CLABSIs using health care failure mode and effect analysis (HFMEA) by analyzing central line insertion, maintenance, and removal practices. A multidisciplinary team was assembled that included clinicians from nursing, neonatology, surgery, infection prevention, pharmacy, and quality management. Between March and October 2011, the team completed the HFMEA process and implemented action plans that included reeducation, practice changes, auditing, and outcome measures. The HFMEA identified 5 common failure modes that contribute to the development of CLABSIs. These included contamination, suboptimal environment of care, improper documentation and evaluation of central venous catheter dressing integrity, issues with equipment and suppliers, and lack of knowledge. Since implementing the appropriate action plans, the NICU has experienced a significant decrease in CLABSIs from 2.6 to 0.8 CLABSIs per 1000 line days. The process of HFMEA helped reduce the CLABSI rate and reinforce the culture of continuous quality improvement and safety in the NICU.
Petley, Graham W; Deakin, Charles D
2013-07-01
Maintaining contact with the patient during defibrillator discharge has been proposed as a method for reducing no flow time but