Simple Waveforms, Simply Described
Baker, John G.
2008-01-01
Since the first Lazarus Project calculations, it has been frequently noted that binary black hole merger waveforms are 'simple.' In this talk we examine some of the simple features of coalescence and merger waveforms from a variety of binary configurations. We suggest an interpretation of the waveforms in terms of an implicit rotating source. This allows a coherent description, of both the inspiral waveforms, derivable from post-Newtonian(PN) calculations, and the numerically determined merger-ringdown. We focus particularly on similarities in the features of various Multipolar waveform components Generated by various systems. The late-time phase evolution of most L these waveform components are accurately described with a sinple analytic fit. We also discuss apparent relationships among phase and amplitude evolution. Taken together with PN information, the features we describe can provide an approximate analytic description full coalescence wavefoRms. complementary to other analytic waveforns approaches.
Quirk, Kevin J.; Srinivasan, Meera
2012-01-01
The minimum-shift-keying (MSK) radar waveform is formed by periodically extending a waveform that separately modulates the in-phase and quadrature- phase components of the carrier with offset pulse-shaped pseudo noise (PN) sequences. To generate this waveform, a pair of periodic PN sequences is each passed through a pulse-shaping filter with a half sinusoid impulse response. These shaped PN waveforms are then offset by half a chip time and are separately modulated on the in-phase and quadrature phase components of an RF carrier. This new radar waveform allows an increase in radar resolution without the need for additional spectrum. In addition, it provides self-interference suppression and configurable peak sidelobes. Compared strictly on the basis of the expressions for delay resolution, main-lobe bandwidth, effective Doppler bandwidth, and peak ambiguity sidelobe, it appears that bi-phase coded (BPC) outperforms the new MSK waveform. However, a radar waveform must meet certain constraints imposed by the transmission and reception of the modulation, as well as criteria dictated by the observation. In particular, the phase discontinuity of the BPC waveform presents a significant impediment to the achievement of finer resolutions in radar measurements a limitation that is overcome by using the continuous phase MSK waveform. The phase continuity, and the lower fractional out-of-band power of MSK, increases the allowable bandwidth compared with BPC, resulting in a factor of two increase in the range resolution of the radar. The MSK waveform also has been demonstrated to have an ambiguity sidelobe structure very similar to BPC, where the sidelobe levels can be decreased by increasing the length of the m-sequence used in its generation. This ability to set the peak sidelobe level is advantageous as it allows the system to be configured to a variety of targets, including those with a larger dynamic range. Other conventionally used waveforms that possess an even greater
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The DSP Based Waveform Generator is used for CSR Control system to control special controlled objects, such as the pulsed power supply for magnets, RF system, injection and extraction synchronization, global CSR synchronization etc. This intelligent controller based on 4800 MIPS DSP and 256M SDRAM technology will supply highly stable and highly accurate reference waveform used by the power supply of magnets. The specifications are as follows:
Griffin, Maurice; Sugawara, Glen
1995-02-01
A system for storing an arbitrary waveform on nonvolatile random access memory (NVRAM) device and generating an analog signal using the NVRAM device is described. A central processing unit is used to synthesize an arbitrary waveform and create a digital representation of the waveform and transfer the digital representation to a microprocessor which, in turn, writes the digital data into an NVRAM device which has been mapped into a portion of the microprocessor address space. The NVRAM device is removed from address space and placed into an independent waveform generation unit. In the waveform generation unit, an address clock provides an address timing signal and a cycle clock provides a transmit signal. Both signals are applied to an address generator. When both signals are present, the address generator generates and transmits to the NVRAM device a new address for each cycle of the address timing signal. In response to each new address generated, the NVRAM devices provides a digital output which is applied to a digital to analog converter. The converter produces a continuous analog output which is smoothed by a filter to produce the arbitrary waveform.
Esper, Stephen A; Pinsky, Michael R
2014-12-01
The bedside measurement of continuous arterial pressure values from waveform analysis has been routinely available via indwelling arterial catheterization for >50 years. Invasive blood pressure monitoring has been utilized in critically ill patients, in both the operating room and critical care units, to facilitate rapid diagnoses of cardiovascular insufficiency and monitor response to treatments aimed at correcting abnormalities before the consequences of either hypo- or hypertension are seen. Minimally invasive techniques to estimate cardiac output (CO) have gained increased appeal. This has led to the increased interest in arterial waveform analysis to provide this important information, as it is measured continuously in many operating rooms and intensive care units. Arterial waveform analysis also allows for the calculation of many so-called derived parameters intrinsically created by this pulse pressure profile. These include estimates of left ventricular stroke volume (SV), CO, vascular resistance, and during positive-pressure breathing, SV variation, and pulse pressure variation. This article focuses on the principles of arterial waveform analysis and their determinants, components of the arterial system, and arterial pulse contour. It will also address the advantage of measuring real-time CO by the arterial waveform and the benefits to measuring SV variation. Arterial waveform analysis has gained a large interest in the overall assessment and management of the critically ill and those at a risk of hemodynamic deterioration.
Full Waveform Inversion Using Waveform Sensitivity Kernels
Schumacher, Florian; Friederich, Wolfgang
2013-04-01
We present a full waveform inversion concept for applications ranging from seismological to enineering contexts, in which the steps of forward simulation, computation of sensitivity kernels, and the actual inversion are kept separate of each other. We derive waveform sensitivity kernels from Born scattering theory, which for unit material perturbations are identical to the Born integrand for the considered path between source and receiver. The evaluation of such a kernel requires the calculation of Green functions and their strains for single forces at the receiver position, as well as displacement fields and strains originating at the seismic source. We compute these quantities in the frequency domain using the 3D spectral element code SPECFEM3D (Tromp, Komatitsch and Liu, 2008) and the 1D semi-analytical code GEMINI (Friederich and Dalkolmo, 1995) in both, Cartesian and spherical framework. We developed and implemented the modularized software package ASKI (Analysis of Sensitivity and Kernel Inversion) to compute waveform sensitivity kernels from wavefields generated by any of the above methods (support for more methods is planned), where some examples will be shown. As the kernels can be computed independently from any data values, this approach allows to do a sensitivity and resolution analysis first without inverting any data. In the context of active seismic experiments, this property may be used to investigate optimal acquisition geometry and expectable resolution before actually collecting any data, assuming the background model is known sufficiently well. The actual inversion step then, can be repeated at relatively low costs with different (sub)sets of data, adding different smoothing conditions. Using the sensitivity kernels, we expect the waveform inversion to have better convergence properties compared with strategies that use gradients of a misfit function. Also the propagation of the forward wavefield and the backward propagation from the receiver
Compressive full waveform lidar
Yang, Weiyi; Ke, Jun
2017-05-01
To avoid high bandwidth detector, fast speed A/D converter, and large size memory disk, a compressive full waveform LIDAR system, which uses a temporally modulated laser instead of a pulsed laser, is studied in this paper. Full waveform data from NEON (National Ecological Observatory Network) are used. Random binary patterns are used to modulate the source. To achieve 0.15 m ranging resolution, a 100 MSPS A/D converter is assumed to make measurements. SPIRAL algorithm with canonical basis is employed when Poisson noise is considered in the low illuminated condition.
Quantum optical waveform conversion
Kielpinski, D; Wiseman, HM
2010-01-01
Currently proposed architectures for long-distance quantum communication rely on networks of quantum processors connected by optical communications channels [1,2]. The key resource for such networks is the entanglement of matter-based quantum systems with quantum optical fields for information transmission. The optical interaction bandwidth of these material systems is a tiny fraction of that available for optical communication, and the temporal shape of the quantum optical output pulse is often poorly suited for long-distance transmission. Here we demonstrate that nonlinear mixing of a quantum light pulse with a spectrally tailored classical field can compress the quantum pulse by more than a factor of 100 and flexibly reshape its temporal waveform, while preserving all quantum properties, including entanglement. Waveform conversion can be used with heralded arrays of quantum light emitters to enable quantum communication at the full data rate of optical telecommunications.
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.
Assessing Accuracy of Waveform Models against Numerical Relativity Waveforms
Pürrer, Michael; LVC Collaboration
2016-03-01
We compare currently available phenomenological and effective-one-body inspiral-merger-ringdown models for gravitational waves (GW) emitted from coalescing black hole binaries against a set of numerical relativity waveforms from the SXS collaboration. Simplifications are used in the construction of some waveform models, such as restriction to spins aligned with the orbital angular momentum, no inclusion of higher harmonics in the GW radiation, no modeling of eccentricity and the use of effective parameters to describe spin precession. In contrast, NR waveforms provide us with a high fidelity representation of the ``true'' waveform modulo small numerical errors. To focus on systematics we inject NR waveforms into zero noise for early advanced LIGO detector sensitivity at a moderately optimistic signal-to-noise ratio. We discuss where in the parameter space the above modeling assumptions lead to noticeable biases in recovered parameters.
Optimizing defibrillation waveforms for ICDs.
Kroll, Mark W; Swerdlow, Charles D
2007-04-01
While no simple electrical descriptor provides a good measure of defibrillation efficacy, the waveform parameters that most directly influence defibrillation are voltage and duration. Voltage is a critical parameter for defibrillation because its spatial derivative defines the electrical field that interacts with the heart. Similarly, waveform duration is a critical parameter because the shock interacts with the heart for the duration of the waveform. Shock energy is the most often cited metric of shock strength and an ICD's capacity to defibrillate, but it is not a direct measure of shock effectiveness. Despite the physiological complexities of defibrillation, a simple approach in which the heart is modeled as passive resistor-capacitor (RC) network has proved useful for predicting efficient defibrillation waveforms. The model makes two assumptions: (1) The goal of both a monophasic shock and the first phase of a biphasic shock is to maximize the voltage change in the membrane at the end of the shock for a given stored energy. (2) The goal of the second phase of a biphasic shock is to discharge the membrane back to the zero potential, removing the charge deposited by the first phase. This model predicts that the optimal waveform rises in an exponential upward curve, but such an ascending waveform is difficult to generate efficiently. ICDs use electronically efficient capacitive-discharge waveforms, which require truncation for effective defibrillation. Even with optimal truncation, capacitive-discharge waveforms require more voltage and energy to achieve the same membrane voltage than do square waves and ascending waveforms. In ICDs, the value of the shock output capacitance is a key intermediary in establishing the relationship between stored energy-the key determinant of ICD size-and waveform voltage as a function of time, the key determinant of defibrillation efficacy. The RC model predicts that, for capacitive-discharge waveforms, stored energy is minimized
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...
Energy Technology Data Exchange (ETDEWEB)
Shin, Chang Soo; Park, Keun Pil [Korea Inst. of Geology Mining and Materials, Taejon (Korea, Republic of); Suh, Jung Hee; Hyun, Byung Koo; Shin, Sung Ryul [Seoul National University, Seoul (Korea, Republic of)
1995-12-01
The seismic reflection exploration technique which is one of the geophysical methods for oil exploration became effectively to image the subsurface structure with rapid development of computer. However, the imagining of subsurface based on the conventional data processing is almost impossible to obtain the information on physical properties of the subsurface such as velocity and density. Since seismic data are implicitly function of velocities of subsurface, it is necessary to develop the inversion method that can delineate the velocity structure using seismic topography and waveform inversion. As a tool to perform seismic inversion, seismic forward modeling program using ray tracing should be developed. In this study, we have developed the algorithm that calculate the travel time of the complex geologic structure using shooting ray tracing by subdividing the geologic model into blocky structure having the constant velocity. With the travel time calculation, the partial derivatives of travel time can be calculated efficiently without difficulties. Since the current ray tracing technique has a limitation to calculate the travel times for extremely complex geologic model, our aim in the future is to develop the powerful ray tracer using the finite element technique. After applying the pseudo waveform inversion to the seismic data of Korea offshore, we can obtain the subsurface velocity model and use the result in bring up the quality of the seismic data processing. If conventional seismic data processing and seismic interpretation are linked with this inversion technique, the high quality of seismic data processing can be expected to image the structure of the subsurface. Future research area is to develop the powerful ray tracer of ray tracing which can calculate the travel times for the extremely complex geologic model. (author). 39 refs., 32 figs., 2 tabs.
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...
Zhang, D. L.
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.
STRS Compliant FPGA Waveform Development
Nappier, Jennifer; Downey, Joseph
2008-01-01
The Space Telecommunications Radio System (STRS) Architecture Standard describes a standard for NASA space software defined radios (SDRs). It provides a common framework that can be used to develop and operate a space SDR in a reconfigurable and reprogrammable manner. One goal of the STRS Architecture is to promote waveform reuse among multiple software defined radios. Many space domain waveforms are designed to run in the special signal processing (SSP) hardware. However, the STRS Architecture is currently incomplete in defining a standard for designing waveforms in the SSP hardware. Therefore, the STRS Architecture needs to be extended to encompass waveform development in the SSP hardware. A transmit waveform for space applications was developed to determine ways to extend the STRS Architecture to a field programmable gate array (FPGA). These extensions include a standard hardware abstraction layer for FPGAs and a standard interface between waveform functions running inside a FPGA. Current standards were researched and new standard interfaces were proposed. The implementation of the proposed standard interfaces on a laboratory breadboard SDR will be presented.
Waveform-dependent absorbing metasurfaces
Wakatsuchi, Hiroki; Rushton, Jeremiah J; Sievenpiper, Daniel F
2014-01-01
We present the first use of a waveform-dependent absorbing metasurface for high-power pulsed surface currents. The new type of nonlinear metasurface, composed of circuit elements including diodes, is capable of storing high power pulse energy to dissipate it between pulses, while allowing propagation of small signals. Interestingly, the absorbing performance varies for high power pulses but not for high power continuous waves (CWs), since the capacitors used are fully charged up. Thus, the waveform dependence enables us to distinguish various signal types (i.e. CW or pulse) even at the same frequency, which potentially creates new kinds of microwave technologies and applications.
An MSK Waveform for Radar Applications
Quirk, Kevin J.; Srinivasan, Meera
2009-01-01
We introduce a minimum shift keying (MSK) waveform developed for use in radar applications. This waveform is characterized in terms of its spectrum, autocorrelation, and ambiguity function, and is compared with the conventionally used bi-phase coded (BPC) radar signal. It is shown that the MSK waveform has several advantages when compared with the BPC waveform, and is a better candidate for deep-space radar imaging systems such as NASA's Goldstone Solar System Radar.
Radar Waveform Design in Active Communications Channel
Ric A. Romero; 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 ...
Generating nonlinear FM chirp waveforms for radar.
Energy Technology Data Exchange (ETDEWEB)
Doerry, Armin Walter
2006-09-01
Nonlinear FM 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 waveform with equivalent sidelobe filtering. This report presents design and implementation techniques for Nonlinear FM waveforms.
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.
Why Waveform Correlation Sometimes Fails
Carmichael, J.
2015-12-01
Waveform correlation detectors used in explosion monitoring scan noisy geophysical data to test two competing hypotheses: either (1) an amplitude-scaled version of a template waveform is present, or, (2) no signal is present at all. In reality, geophysical wavefields that are monitored for explosion signatures include waveforms produced by non-target sources that are partially correlated with the waveform template. Such signals can falsely trigger correlation detectors, particularly at low thresholds required to monitor for smaller target explosions. This challenge is particularly formidable when monitoring known test sites for seismic disturbances, since uncatalogued natural seismicity is (generally) more prevalent at lower magnitudes, and could be mistaken for small explosions. To address these challenges, we identify real examples in which correlation detectors targeting explosions falsely trigger on both site-proximal earthquakes (Figure 1, below) and microseismic "noise". Motivated by these examples, we quantify performance loss when applying these detectors, and re-evaluate the correlation-detector's hypothesis test. We thereby derive new detectors from more general hypotheses that admit unknown background seismicity, and apply these to real data. From our treatment, we derive "rules of thumb'' for proper template and threshold selection in heavily cluttered signal environments. Last, we answer the question "what is the probability of falsely detecting an earthquake collocated at a test site?", using correlation detectors that include explosion-triggered templates. Figure Top: An eight-channel data stream (black) recorded from an earthquake near a mine. Red markers indicate a detection. Middle: The correlation statistic computed by scanning the template against the data stream at top. The red line indicates the threshold for event declaration, determined by a false-alarm on noise probability constraint, as computed from the signal-absent distribution using
Phenomenological gravitational waveforms from spinning coalescing binaries
Sturani, R; Cadonati, L; Guidi, G M; Healy, J; Shoemaker, D; Vicere', A
2010-01-01
An accurate knowledge of the coalescing binary gravitational waveform is crucial for match filtering techniques, which are currently used in the observational searches performed by the LIGO-Virgo collaboration. Following an earlier paper by the same authors we expose the construction of analytical phenomenological waveforms describing the signal sourced by generically spinning binary systems. The gap between the initial inspiral part of the waveform, described by spin-Taylor approximants, and its final ring-down part, described by damped exponentials, is bridged by a phenomenological phase calibrated by comparison with the dominant spherical harmonic mode of a set of waveforms including both numerical and phenomenological waveforms of a different type. All waveforms considered describe equal mass systems with dimension-less spin magnitudes equal to 0.6. The noise-weighted overlap integral between numerical and phenomenological waveforms ranges between 0.93 and 0.98 for a wide span of mass values.
Fractal characteristics for binary noise radar waveform
Li, Bing C.
2016-05-01
Noise radars have many advantages over conventional radars and receive great attentions recently. The performance of a noise radar is determined by its waveforms. Investigating characteristics of noise radar waveforms has significant value for evaluating noise radar performance. In this paper, we use binomial distribution theory to analyze general characteristics of binary phase coded (BPC) noise waveforms. Focusing on aperiodic autocorrelation function, we demonstrate that the probability distributions of sidelobes for a BPC noise waveform depend on the distances of these sidelobes to the mainlobe. The closer a sidelobe to the mainlobe, the higher the probability for this sidelobe to be a maximum sidelobe. We also develop Monte Carlo framework to explore the characteristics that are difficult to investigate analytically. Through Monte Carlo experiments, we reveal the Fractal relationship between the code length and the maximum sidelobe value for BPC waveforms, and propose using fractal dimension to measure noise waveform performance.
Visualization and analysis of lidar waveform data
Olsen, Richard C.; Metcalf, Jeremy P.
2017-05-01
LiDAR waveform analysis is a relatively new activity in the area of laser scanning. The work described here is an exploration of a different approach to visualization and analysis, following the structure that has evolved for the analysis of imaging spectroscopy data (hyperspectral imaging). The waveform data are transformed into 3-dimensional data structures that provide xy position information, and a z-coordinate, which is the digitized waveform. This allows for representation of the data in spatial and waveform space, the extraction of characteristic spectra, and the development of regions of interest. This representation allows for the application of standard spectral classification tools such as the maximum likelihood classifier.
Seismic waveform modeling over cloud
Luo, Cong; Friederich, Wolfgang
2016-04-01
With the fast growing computational technologies, numerical simulation of seismic wave propagation achieved huge successes. Obtaining the synthetic waveforms through numerical simulation receives an increasing amount of attention from seismologists. However, computational seismology is a data-intensive research field, and the numerical packages usually come with a steep learning curve. Users are expected to master considerable amount of computer knowledge and data processing skills. Training users to use the numerical packages, correctly access and utilize the computational resources is a troubled task. In addition to that, accessing to HPC is also a common difficulty for many users. To solve these problems, a cloud based solution dedicated on shallow seismic waveform modeling has been developed with the state-of-the-art web technologies. It is a web platform integrating both software and hardware with multilayer architecture: a well designed SQL database serves as the data layer, HPC and dedicated pipeline for it is the business layer. Through this platform, users will no longer need to compile and manipulate various packages on the local machine within local network to perform a simulation. By providing users professional access to the computational code through its interfaces and delivering our computational resources to the users over cloud, users can customize the simulation at expert-level, submit and run the job through it.
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
Optical arbitrary waveform characterization using linear spectrograms.
Jiang, Zhi; Leaird, Daniel E; Long, Christopher M; Boppart, Stephen A; Weiner, Andrew M
2010-08-01
We demonstrate the first application of linear spectrogram methods based on electro-optic phase modulation to characterize optical arbitrary waveforms generated under spectral line-by-line control. This approach offers both superior sensitivity and self-referencing capability for retrieval of periodic high repetition rate optical arbitrary waveforms.
Digital Waveform Generator Basedon FPGA
Directory of Open Access Journals (Sweden)
Shoucheng Ding
2012-07-01
Full Text Available Field Programmable Gate Array (FPGA of the Cyclone II series was as the core processor of frequency meter and the Quartus II was as the development plat form. This article had designed the fully digital signal generator. It use dall-digital frequency synthesizer technology and FPGA programming implemented the three waveforms: sin wave and square wave and triangle wave. The frequency was adjustable through10- bit phase accumulator and the analog multiplier achieved amplitude modulation. Using 51soft nuclear FPGA wrote a C program and realized the in put control word. The 4 × 4 matrix keyboard inputted frequency or amplitude value and the LCD1602displayedthem. The test results show that the system has high precision, distortion and low.
Cannon, Kipp; Hanna, Chad; Keppel, Drew; Pfeiffer, Harald
2012-01-01
Matched-filtering for the identification of compact object mergers in gravitational-wave antenna data involves the comparison of the data stream to a bank of template gravitational waveforms. Typically the template bank is constructed from phenomenological waveform models since these can be evaluated for an arbitrary choice of physical parameters. Recently it has been proposed that singular value decomposition (SVD) can be used to reduce the number of templates required for detection. As we show here, another benefit of SVD is its removal of biases from the phenomenological templates along with a corresponding improvement in their ability to represent waveform signals obtained from numerical relativity (NR) simulations. Using these ideas, we present a method that calibrates a reduced SVD basis of phenomenological waveforms against NR waveforms in order to construct a new waveform approximant with improved accuracy and faithfulness compared to the original phenomenological model. The new waveform family is giv...
Implementation of Pulse Radar Waveform Based on Software Radio Platform
Wang Dong; Dong Jian; Xiao Shunping
2015-01-01
Based on the frequency and phase modulated signal, the authors design some commonly-used pulse radar baseband waveform, such as linear frequency modulated waveform, nonlinear frequency modulated waveform, Costas waveform, Barker coding waveform and multi-phase coded waveform, and the authors compare their performance, such as the peak side lobe ratio, the Rayleigh resolution in time and distance resolution. Then, based on the software radio platform NI PXIe-5644R, the authors design the timin...
Improved retracking algorithm for oceanic altimeter waveforms
Institute of Scientific and Technical Information of China (English)
Lifeng Bao; Yang Lu; Yong Wang
2009-01-01
Over the deep oceans without land/ice interference, the waveforms created by the return altimeter pulse generally follow the ocean model of Brown, and the corresponding range can be properly determined using the result from an onboard tracker. In the case of com-plex altimeter waveforms corrupted due to a variety of reasons, the processor on the satellite cannot properly determine the center of the leading edge, and range observations can be in error. As an efficacious method to improve the precision of those altimeter observations with complex waveforms, waveform retracking is required to reprocess the original returning pulse. Based on basic altimeter theory and the geometric feature of altimeter waveforms, we developed a new altimeter waveform retracker, which is valid for all altimeter wave-forms once there exists a reasonable returning signal. The performances of the existing Beta-5 retracker, threshold retracker, improved threshold retracker, and the new retracker are assessed in the experimental regions (China Seas and its adjacent regions), and the improvements in the accuracy of sea surface height are investigated by the difference between retracked altimeter observations and ref-erenced geoid. The comparisons denote that the new algorithm gives the best performance in both the open ocean and coastal regions. Also, the new retracker presents a uniform performance in the whole test region. Besides, there is a significant improvement in the short-wavelength precision and the spatial resolution of sea surface height after retracking process.
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
Parallel Algorithm in Surface Wave Waveform Inversion
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In Surface wave waveform inversion, we want to reconstruct 3Dshear wav e velocity structure, which calculation beyond the capability of the powerful pr esent day personal computer or even workstation. So we designed a high parallele d algorithm and carried out the inversion on Parallel computer based on the part itioned waveform inversion (PWI). It partitions the large scale optimization pro blem into a number of independent small scale problems and reduces the computati onal effort by several orders of magnitude. We adopted surface waveform inversio n with a equal block(2°×2°) discretization.
Periodic, pseudonoise waveforms for multifunction coherent ladar.
Dierking, Matthew P; Duncan, Bradley D
2010-04-01
We report the use of periodic, pseudonoise waveforms in a multifunction coherent ladar system. We exploit the Doppler sensitivity of these waveforms, as well as agile processing, to enable diverse ladar functions, including high range resolution imaging, macro-Doppler imaging, synthetic aperture ladar, and range-resolved micro-Doppler imaging. We present analytic expressions and simulations demonstrating the utility of pseudonoise waveforms for each of the ladar modes. We also discuss a laboratory pseudonoise ladar system that was developed to demonstrate range compression and range-resolved micro-Doppler imaging, as well as the phase recovery common to each of the coherent modes.
Optimal pseudorandom pulse position modulation ladar waveforms.
Fluckiger, David U; Boland, Brian F; Marcus, Eran
2015-03-20
An algorithm for generating optimal pseudorandom pulse position modulation (PRPPM) waveforms for ladar ranging is presented. Bistatic ladar systems using Geiger-mode avalanche photodiodes require detection of several pulses in order to generate sufficient target statistics to satisfy some detection decision rule. For targets with large initial range uncertainty, it becomes convenient to transmit a pulse train with large ambiguity range. One solution is to employ a PRPPM waveform. An optimal PRPPM waveform will have minimal sidelobes: equivalent to 1 or 0 counts after the pulse correlation filter (compression). This can be accomplished by generating PRPPM pulse trains with optimal or minimal sidelobe autocorrelation.
Selection of Carrier Waveforms for PWM Inverter
Institute of Scientific and Technical Information of China (English)
陈国呈; 屈克庆; 许春雨; 孙承波
2003-01-01
In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonancetrigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.
High-Voltage, Asymmetric-Waveform Generator
Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik
2008-01-01
The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise
GRC GSFC TDRSS Waveform Metrics Report
Mortensen, Dale J.
2013-01-01
The report presents software metrics and porting metrics for the GGT Waveform. The porting was from a ground-based COTS SDR, the SDR-3000, to the CoNNeCT JPL SDR. The report does not address any of the Operating Environment (OE) software development, nor the original TDRSS waveform development at GSFC for the COTS SDR. With regard to STRS, the report presents compliance data and lessons learned.
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...
Georgia tech catalog of gravitational waveforms
Jani, Karan; Healy, James; Clark, James A.; London, Lionel; Laguna, Pablo; Shoemaker, Deirdre
2016-10-01
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 ≤ 15, and those with precessing, spinning black holes have q ≤ 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 event and future massive binary black-hole search in LIGO is discussed. The Georgia Tech catalog is publicly available at einstein.gatech.edu/catalog.
Platform for Postprocessing Waveform-Based NDE
Roth, Don
2008-01-01
Taking advantage of the similarities that exist among all waveform-based non-destructive evaluation (NDE) methods, a common software platform has been developed containing multiple- signal and image-processing techniques for waveforms and images. The NASA NDE Signal and Image Processing software has been developed using the latest versions of LabVIEW, and its associated Advanced Signal Processing and Vision Toolkits. The software is useable on a PC with Windows XP and Windows Vista. The software has been designed with a commercial grade interface in which two main windows, Waveform Window and Image Window, are displayed if the user chooses a waveform file to display. Within these two main windows, most actions are chosen through logically conceived run-time menus. The Waveform Window has plots for both the raw time-domain waves and their frequency- domain transformations (fast Fourier transform and power spectral density). The Image Window shows the C-scan image formed from information of the time-domain waveform (such as peak amplitude) or its frequency-domain transformation at each scan location. The user also has the ability to open an image, or series of images, or a simple set of X-Y paired data set in text format. Each of the Waveform and Image Windows contains menus from which to perform many user actions. An option exists to use raw waves obtained directly from scan, or waves after deconvolution if system wave response is provided. Two types of deconvolution, time-based subtraction or inverse-filter, can be performed to arrive at a deconvolved wave set. Additionally, the menu on the Waveform Window allows preprocessing of waveforms prior to image formation, scaling and display of waveforms, formation of different types of images (including non-standard types such as velocity), gating of portions of waves prior to image formation, and several other miscellaneous and specialized operations. The menu available on the Image Window allows many further image
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.
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.
SCA Waveform Development for Space Telemetry
Mortensen, Dale J.; Kifle, Multi; Hall, C. Steve; Quinn, Todd M.
2004-01-01
The NASA Glenn Research Center is investigating and developing suitable reconfigurable radio architectures for future NASA missions. This effort is examining software-based open-architectures for space based transceivers, as well as common hardware platform architectures. The Joint Tactical Radio System's (JTRS) Software Communications Architecture (SCA) is a candidate for the software approach, but may need modifications or adaptations for use in space. An in-house SCA compliant waveform development focuses on increasing understanding of software defined radio architectures and more specifically the JTRS SCA. Space requirements put a premium on size, mass, and power. This waveform development effort is key to evaluating tradeoffs with the SCA for space applications. Existing NASA telemetry links, as well as Space Exploration Initiative scenarios, are the basis for defining the waveform requirements. Modeling and simulations are being developed to determine signal processing requirements associated with a waveform and a mission-specific computational burden. Implementation of the waveform on a laboratory software defined radio platform is proceeding in an iterative fashion. Parallel top-down and bottom-up design approaches are employed.
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...
Photonic arbitrary waveform generator based on Taylor synthesis method.
Liao, Shasha; Ding, Yunhong; Dong, Jianji; Yan, Siqi; Wang, Xu; Zhang, Xinliang
2016-10-17
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 dispersion, which are difficult to fabricate on chip. Our scheme is compact and capable for integration with electronics.
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).
Wavelet analysis of the impedance cardiogram waveforms
Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.
2012-12-01
Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.
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.
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.
Filter transient response to EEG waveforms.
Shirakawa, S; Smith, J R; Azumi, K
1987-01-01
The response of two types of linear filters to sinusoidal bursts was calculated to demonstrate how filters can distort EEG waveforms. Results show that the wider the filter bandwidth the less is the distortion, and for a given bandwidth, the higher the filter order the greater the distortion. The response of a linear phase filter was also calculated to demonstrate that this type of filter can also cause waveform distortion, although it is normally less than that caused by Butterworth, Tchebychev and elliptic filters.
High-Energy Optical Parametric Waveform Synthesizer
Muecke, Oliver D.; Cirmi, G.; Fang, S.; Rossi, G. M.; Chia, Shih-Hsuan; Kärtner, F. X.; Manzoni, C.; Farinello, P.; Cerullo, and G.
2014-01-01
We discuss the ongoing development of a phase-stable, multi-mJ 3-channel parametric waveform synthesizer generating a 2-octave-wide spectrum (0.52-2.4μm). After two amplification stages, the combined >125-μJ output supports 1.9-fs waveforms. First preliminary FROG-characterization results of the second-stage outputs demonstrate the feasibility to recompress all three channels simultaneously close to the Fourier limit. Energy scaling to ~2 mJ is achieved after three amplification stages. The f...
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
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
Fractal Dimension of Voice-Signal Waveforms
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The fractal dimension is one important parameter that characterizes waveforms. In this paper, we derive a new method to calculate fractal dimension of digital voice-signal waveforms. We show that fractal dimension is an efficient tool for speaker recognition or speech recognition. It can be used to identify different speakers or distinguish speech. We apply our results to Chinese speaker recognition and numerical experiment shows that fractal dimension is an efficient parameter to characterize individual Chinese speakers. We have developed a semiautomatic voiceprint analysis system based on the theory of this paper and former researches.
A New Method of Designing Waveform Codebook
Institute of Scientific and Technical Information of China (English)
1998-01-01
The codebook search takes much operation quantity in CELP coder. The paper puts forward a new method redesigning the waveform codebook known, and lists the experimental data. It has been proved that the operation complexity and transmission bit rate were decreased by using the new codebook, and the synthesis speech quality was high.
Waveform Selectivity at the Same Frequency
Wakatsuchi, Hiroki; Anzai, Daisuke; Rushton, Jeremiah J.; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F.
2015-01-01
Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of circuit elements are then combined to absorb or transmit specific waveforms in between. This waveform selectivity gives us another degree of freedom to control electromagnetic waves in various fields including wireless communications, as our simulation reveals that the metasurfaces are capable of varying bit error rates in response to different waveforms. PMID:25866071
Windowing Waveform Relaxation of Initial Value Problems
Institute of Scientific and Technical Information of China (English)
Yao-lin Jiang
2006-01-01
We present a windowing technique of waveform relaxation for dynamic systems. An effective estimation on window length is derived by an iterative error expression provided here. Relaxation processes can be speeded up if one takes the windowing technique in advance. Numerical experiments are given to further illustrate the theoretical analysis.
Resolution analysis in full waveform inversion
Fichtner, A.; Trampert, J.
2011-01-01
We propose a new method for the quantitative resolution analysis in full seismic waveform inversion that overcomes the limitations of classical synthetic inversions while being computationally more efficient and applicable to any misfit measure. The method rests on (1) the local quadratic approximat
Seismic Waveform Inversion by Stochastic Optimization
Directory of Open Access Journals (Sweden)
Tristan van Leeuwen
2011-01-01
Full Text Available We explore the use of stochastic optimization methods for seismic waveform inversion. The basic principle of such methods is to randomly draw a batch of realizations of a given misfit function and goes back to the 1950s. The ultimate goal of such an approach is to dramatically reduce the computational cost involved in evaluating the misfit. Following earlier work, we introduce the stochasticity in waveform inversion problem in a rigorous way via a technique called randomized trace estimation. We then review theoretical results that underlie recent developments in the use of stochastic methods for waveform inversion. We present numerical experiments to illustrate the behavior of different types of stochastic optimization methods and investigate the sensitivity to the batch size and the noise level in the data. We find that it is possible to reproduce results that are qualitatively similar to the solution of the full problem with modest batch sizes, even on noisy data. Each iteration of the corresponding stochastic methods requires an order of magnitude fewer PDE solves than a comparable deterministic method applied to the full problem, which may lead to an order of magnitude speedup for waveform inversion in practice.
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.
Processing Waveforms as Trees for Pattern Recognition.
1986-05-01
patterns (after Ganong (15]) 5.7 ECG Classification As in the previous example, waveforms were simulated with additive colored gaussian noise. In order to...Principles and Techniques- (AAPG Course Note Series 13), Amer. Assoc. Pet. Geol., Tulsa, OK,p. 86, (1984). [15] W. F. Ganong , Review of Medical Physiology. Lange, Los Altos, CA. pp. 393-408, (1973). /
I.A.L. Groenenberg (Irene); W.C.J. Hop (Wim); J.W. Wladimiroff (Juriy)
1991-01-01
markdownabstract__Abstract__ Reproducibility of flow velocity waveform recording and analysis was studied at fetal cardiac level (ductus arteriosus, pulmonary artery and ascending aorta) in 42 normal pregnancies. The flow velocity parameters studied were the peak systolic velocity (PSV),
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.
Application of arbitrary waveform generator for noise radar
Lukin, Konstantin A.; Zemlyaniy, Oleg V.; Vyplavin, Pavlo L.; Palamarchuk, Volodymyr P.
2011-10-01
The approach, when the waveforms of different types are exploited in the same radar (waveform diversity) requires new-generation sources of initial signals. For generating of different types of waveforms in the same radar we suggest using Arbitrary Waveform Generator, that allows output any type of pre-programmed signal in real time. We have carried out preliminary experimental tests of the stepped-delay mode of UHF-band radar evaluation kit. The series of experimental testing shows efficiency AWG application in radar with variety of sounding waveforms.
Butlin, Mark; Qasem, Ahmad; Avolio, Alberto P
2012-01-01
There is increasing interest in non-invasive estimation of central aortic waveform parameters in the clinical setting. However, controversy has arisen around radial tonometric based systems due to the requirement of a trained operator or lack of ease of use, especially in the clinical environment. A recently developed device utilizes a novel algorithm for brachial cuff based assessment of aortic pressure values and waveform (SphygmoCor XCEL, AtCor Medical). The cuff was inflated to 10 mmHg below an individual's diastolic blood pressure and the brachial volume displacement waveform recorded. The aortic waveform was derived using proprietary digital signal processing and transfer function applied to the recorded waveform. The aortic waveform was also estimated using a validated technique (radial tonometry based assessment, SphygmoCor, AtCor Medical). Measurements were taken in triplicate with each device in 30 people (17 female) aged 22 to 79 years of age. An average for each device for each individual was calculated, and the results from the two devices were compared using regression and Bland-Altman analysis. A high correlation was found between the devices for measures of aortic systolic (R(2)=0.99) and diastolic (R(2)=0.98) pressure. Augmentation index and subendocardial viability ratio both had a between device R(2) value of 0.82. The difference between devices for measured aortic systolic pressure was 0.5±1.8 mmHg, and for augmentation index, 1.8±7.0%. The brachial cuff based approach, with an individualized sub-diastolic cuff pressure, provides an operator independent method of assessing not only systolic pressure, but also aortic waveform features, comparable to existing validated tonometric-based methods.
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.
LISA parameter estimation using numerical merger waveforms
Energy Technology Data Exchange (ETDEWEB)
Thorpe, J I; McWilliams, S T; Kelly, B J; Fahey, R P; Arnaud, K; Baker, J G, E-mail: James.I.Thorpe@nasa.go [NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771 (United States)
2009-05-07
Recent advances in numerical relativity provide a detailed description of the waveforms of coalescing massive black hole binaries (MBHBs), expected to be the strongest detectable LISA sources. We present a preliminary study of LISA's sensitivity to MBHB parameters using a hybrid numerical/analytic waveform for equal-mass, non-spinning holes. The Synthetic LISA software package is used to simulate the instrument response, and the Fisher information matrix method is used to estimate errors in the parameters. Initial results indicate that inclusion of the merger signal can significantly improve the precision of some parameter estimates. For example, the median parameter errors for an ensemble of systems with total redshifted mass of 10{sup 6} M{sub o-dot} at a redshift of z approx 1 were found to decrease by a factor of slightly more than two for signals with merger as compared to signals truncated at the Schwarzchild ISCO.
LISA parameter estimation using numerical merger waveforms
Thorpe, J I; Kelly, B J; Fahey, R P; Arnaud, K; Baker, J G
2008-01-01
Recent advances in numerical relativity provide a detailed description of the waveforms of coalescing massive black hole binaries (MBHBs), expected to be the strongest detectable LISA sources. We present a preliminary study of LISA's sensitivity to MBHB parameters using a hybrid numerical/analytic waveform for equal-mass, non-spinning holes. The Synthetic LISA software package is used to simulate the instrument response and the Fisher information matrix method is used to estimate errors in the parameters. Initial results indicate that inclusion of the merger signal can significantly improve the precision of some parameter estimates. For example, the median parameter errors for an ensemble of systems with total redshifted mass of one million Solar masses at a redshift of one were found to decrease by a factor of slightly more than two for signals with merger as compared to signals truncated at the Schwarzchild ISCO.
Comparing numerical and analytic approximate gravitational waveforms
Afshari, Nousha; Lovelace, Geoffrey; SXS Collaboration
2016-03-01
A direct observation of gravitational waves will test Einstein's theory of general relativity under the most extreme conditions. The Laser Interferometer Gravitational-Wave Observatory, or LIGO, began searching for gravitational waves in September 2015 with three times the sensitivity of initial LIGO. To help Advanced LIGO detect as many gravitational waves as possible, a major research effort is underway to accurately predict the expected waves. In this poster, I will explore how the gravitational waveform produced by a long binary-black-hole inspiral, merger, and ringdown is affected by how fast the larger black hole spins. In particular, I will present results from simulations of merging black holes, completed using the Spectral Einstein Code (black-holes.org/SpEC.html), including some new, long simulations designed to mimic black hole-neutron star mergers. I will present comparisons of the numerical waveforms with analytic approximations.
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
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
Waveforms Measured in Confined Thermobaric Explosion
Energy Technology Data Exchange (ETDEWEB)
Reichenbach, H; Neuwald, P; Kuhl, A L
2007-05-04
Experiments with 1.5-g Shock-Dispersed-Fuel (SDF) charges have been conducted in six different chambers. Both flake Aluminum and TNT were used as the fuel. Static pressure gauges on the chamber wall were the main diagnostic. Waveforms for explosions in air were significantly larger than those in nitrogen - thereby demonstrating a strong thermobaric (combustion) effect. This effect increases as the confinement volume decreases and the mixture richness approaches 1.
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
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.
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.
Binary Black Holes: Mergers, Dynamics, and Waveforms
Centrella, Joan
2007-04-01
The final merger of two black holes is expected to be the strongest gravitational wave source for ground-based interferometers such as LIGO, VIRGO, and GEO600, as well as the space-based interferometer LISA. Observing these sources with gravitational wave detectors requires that we know the radiation waveforms they emit. Since these mergers take place in regions of extreme gravity, we need to solve Einstein's equations of general relativity on a computer in order to calculate these waveforms. For more than 30 years, scientists have tried to compute black hole mergers using the methods of numerical relativity. The resulting computer codes have been plagued by instabilities, causing them to crash well before the black holes in the binary could complete even a single orbit. Within the past few years, however, this situation has changed dramatically, with a series of remarkable breakthroughs. This talk will focus on new simulations that are revealing the dynamics and waveforms of binary black hole mergers, and their applications in gravitational wave detection, data analysis, and astrophysics.
Full waveform inversion for ultrasonic flaw identification
Seidl, Robert; Rank, Ernst
2017-02-01
Ultrasonic Nondestructive Testing is concerned with detecting flaws inside components without causing physical damage. It is possible to detect flaws using ultrasound measurements but usually no additional details about the flaw like position, dimension or orientation are available. The information about these details is hidden in the recorded experimental signals. The idea of full waveform inversion is to adapt the parameters of an initial simulation model of the undamaged specimen by minimizing the discrepancy between these simulated signals and experimentally measured signals of the flawed specimen. Flaws in the structure are characterized by a change or deterioration in the material properties. Commonly, full waveform inversion is mostly applied in seismology on a larger scale to infer mechanical properties of the earth. We propose to use acoustic full waveform inversion for structural parameters to visualize the interior of the component. The method is adapted to US NDT by combining multiple similar experiments on the test component as the typical small amount of sensors is not sufficient for a successful imaging. It is shown that the combination of simulations and multiple experiments can be used to detect flaws and their position, dimension and orientation in emulated simulation cases.
The Waveform Server: A Web-based Interactive Seismic Waveform Interface
Newman, R. L.; Clemesha, A.; Lindquist, K. G.; Reyes, J.; Steidl, J. H.; Vernon, F. L.
2009-12-01
Seismic waveform data has traditionally been displayed on machines that are either local area networked to, or directly host, a seismic networks waveform database(s). Typical seismic data warehouses allow online users to query and download data collected from regional networks passively, without the scientist directly visually assessing data coverage and/or quality. Using a suite of web-based protocols, we have developed an online seismic waveform interface that directly queries and displays data from a relational database through a web-browser. Using the Python interface to Datascope and the Python-based Twisted network package on the server side, and the jQuery Javascript framework on the client side to send and receive asynchronous waveform queries, we display broadband seismic data using the HTML Canvas element that is globally accessible by anyone using a modern web-browser. The system is used to display data from the USArray experiment, a US continent-wide migratory transportable seismic array. We are currently creating additional interface tools to create a rich-client interface for accessing and displaying seismic data that can be deployed to any system running Boulder Real Time Technology's (BRTT) Antelope Real Time System (ARTS). The software is freely available from the Antelope contributed code Git repository. Screenshot of the web-based waveform server interface
Processing Aftershock Sequences Using Waveform Correlation
Resor, M. E.; Procopio, M. J.; Young, C. J.; Carr, D. B.
2008-12-01
For most event monitoring systems, the objective is to keep up with the flow of incoming data, producing a bulletin with some modest, relatively constant, time delay after present time, often a period of a few hours or less. Because the association problem scales exponentially and not linearly with the number of detections, a dramatic increase in seismicity due to an aftershock sequence can easily cause the bulletin delay time to increase dramatically. In some cases, the production of a bulletin may cease altogether, until the automatic system can catch up. For a nuclear monitoring system, the implications of such a delay could be dire. Given the expected similarity between a mainshock and aftershocks, it has been proposed that waveform correlation may provide a powerful means to simultaneously increase the efficiency of processing aftershock sequences, while also lowering the detection threshold and improving the quality of the event solutions. However, many questions remain unanswered. What are the key parameters for achieving the best correlations between waveforms (window length, filtering, etc.), and are they sequence-dependent? What is the overall percentage of similar events in an aftershock sequence, i.e. what is the maximum level of efficiency that a waveform correlation could be expected to achieve? Finally, how does this percentage of events vary among sequences? Using data from the aftershock sequence for the December 26, 2004 Mw 9.1 Sumatra event, we investigate these issues by building and testing a prototype waveform correlation event detection system that automatically expands its library of known events as new signatures are indentified in the aftershock sequence (by traditional signal detection and event processing). Our system tests all incoming data against this dynamic library, thereby identify any similar events before traditional processing takes place. In the region surrounding the Sumatra event, the NEIC EDR contains 4997 events in the 9
The Multiple Waveform Persistent Peak (MWaPP) Retracker for SAR waveforms
DEFF Research Database (Denmark)
Villadsen, Heidi; Andersen, Ole Baltazar; Stenseng, Lars
using CryoSat-2 20Hz SAR data, but due to the similarities between the Sentinel-3 SRAL altimeter and the SIRAL altimeter on-board CryoSat-2 an adaption of the method will be straightforward. The MWaPP retracker is based on a sub-waveform retracker, but takes the shape of adjacent waveforms into account...... before selecting the sub-waveform belonging to nadir. This is new compared to primary peak retrackers, and alleviates a lot of snagging due to off-nadir bright targets, but also topography challenges. The results from the MWaPP retracker show a significant decrease in the standard deviation of the mean...
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.
Preconditioning Strategies in Elastic Full Waveform Inversion.
Matharu, G.; Sacchi, M. D.
2016-12-01
Elastic full waveform inversion (FWI) is inherently more non-linear than its acoustic counterpart, a property that stems from the increased model space of the problem. Whereas acoustic media can be parametrized by density and P-wave velocity, visco-elastic media are parametrized by density, attenuation and 21 independent coefficients of the elastic tensor. Imposing assumptions of isotropy and perfect elasticity to simplify the physics, reduces the number of independent parameters required to characterize a medium. Isotropic, elastic media can be parametrized in terms of density and the Lamé parameters. The different parameters can exhibit trade-off that manifest as attributes in the data. In the context of FWI, this means that certain parameters cannot be uniquely resolved. An ideal model update in full waveform inversion is equivalent to a Newton step. Explicit computation of the Hessian and its inverse is not computationally feasible in elastic FWI. The inverse Hessian scales the gradients to account for trade-off between parameters as well as compensating for inadequate illumination related to source-receiver coverage. Gradient preconditioners can be applied to mimic the action of the inverse Hessian and partially correct for inaccuracies in the gradient. In this study, we investigate the effects of model reparametrization by recasting a regularized form of the least-squares waveform misfit into a preconditioned formulation. New model parameters are obtained by applying invertible weighting matrices to the model vector. The weighting matrices are related to estimates of the prior model covariance matrix and incorporate information about spatially variant correlations of model parameters as well as correlations between independent parameters. We compare the convergence of conventional FWI to FWI after model reparametrization.
Optimal Transport for Seismic Full Waveform Inversion
Engquist, Bjorn; Yang, Yunan
2016-01-01
Full waveform inversion is a successful procedure for determining properties of the earth from surface measurements in seismology. This inverse problem is solved by a PDE constrained optimization where unknown coefficients in a computed wavefield are adjusted to minimize the mismatch with the measured data. We propose using the Wasserstein metric, which is related to optimal transport, for measuring this mismatch. Several advantageous properties are proved with regards to convexity of the objective function and robustness with respect to noise. The Wasserstein metric is computed by solving a Monge-Ampere equation. We describe an algorithm for computing its Frechet gradient for use in the optimization. Numerical examples are given.
A new earthquake location method based on the waveform inversion
Wu, Hao; Huang, Xueyuan; Yang, Dinghui
2016-01-01
In this paper, a new earthquake location method based on the waveform inversion is proposed. As is known to all, the waveform misfit function is very sensitive to the phase shift between the synthetic waveform signal and the real waveform signal. Thus, the convergence domain of the conventional waveform based earthquake location methods is very small. In present study, by introducing and solving a simple sub-optimization problem, we greatly expand the convergence domain of the waveform based earthquake location method. According to a large number of numerical experiments, the new method expands the range of convergence by several tens of times. This allows us to locate the earthquake accurately even from some relatively bad initial values.
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.
Waveform Optimization for SWIPT with Nonlinear Energy Harvester Modeling
Clerckx, Bruno
2016-01-01
Simultaneous Wireless Information and Power Transfer (SWIPT) has attracted significant attention in the communication community. The problem of waveform design for SWIPT has however never been addressed so far. In this paper, a novel SWIPT transceiver architecture is introduced relying on the superposition of multisine and OFDM waveforms at the transmitter and a power-splitter receiver equipped with an energy harvester and an information decoder capable of cancelling the multisine waveforms. ...
RF arbitrary waveform generation using tunable planar lightwave circuits
Samadi, P.; Chen, L. R.; Callender, C.; Dumais, P.; Jacob, S.; Celo, D.
2011-07-01
We demonstrate photonically-assisted generation of RF arbitrary waveforms using planar lightwave circuits (PLCs) fabricated on silica-on-silicon. We exploit thermo-optic effects in silica in order to tune the response of the PLC and hence reconfigure the generated waveform. We demonstrate the generation of pulse trains at 40 GHz and 80 GHz with flat-top, Gaussian, and apodized profiles. These results demonstrate the potential for RF arbitrary waveform generation using chip-scale photonic solutions.
Information Encoding on a Pseudo Random Noise Radar Waveform
2013-03-01
PSEUDO RANDOM NOISE RADAR WAVEFORM THESIS Joshua A. Hardin, Captain, USAF AFIT-ENG-13-M-22 DEPARTMENT OF THE AIR FORCE AIR...protection in the United States. AFIT-ENG-13-M-22 INFORMATION ENCODING ON A PSEUDO RANDOM NOISE RADAR WAVEFORM THESIS Presented to the Faculty...INFORMATION ENCODING ON A PSEUDO RANDOM NOISE RADAR WAVEFORM I. Introduction 1.1 Problem Description Navigation requires knowledge of current
Adaptive multi-step Full Waveform Inversion based on Waveform Mode Decomposition
Hu, Yong; Han, Liguo; Xu, Zhuo; Zhang, Fengjiao; Zeng, Jingwen
2017-04-01
Full Waveform Inversion (FWI) can be used to build high resolution velocity models, but there are still many challenges in seismic field data processing. The most difficult problem is about how to recover long-wavelength components of subsurface velocity models when seismic data is lacking of low frequency information and without long-offsets. To solve this problem, we propose to use Waveform Mode Decomposition (WMD) method to reconstruct low frequency information for FWI to obtain a smooth model, so that the initial model dependence of FWI can be reduced. In this paper, we use adjoint-state method to calculate the gradient for Waveform Mode Decomposition Full Waveform Inversion (WMDFWI). Through the illustrative numerical examples, we proved that the low frequency which is reconstructed by WMD method is very reliable. WMDFWI in combination with the adaptive multi-step inversion strategy can obtain more faithful and accurate final inversion results. Numerical examples show that even if the initial velocity model is far from the true model and lacking of low frequency information, we still can obtain good inversion results with WMD method. From numerical examples of anti-noise test, we see that the adaptive multi-step inversion strategy for WMDFWI has strong ability to resist Gaussian noise. WMD method is promising to be able to implement for the land seismic FWI, because it can reconstruct the low frequency information, lower the dominant frequency in the adjoint source, and has a strong ability to resist noise.
On the accuracy and precision of numerical waveforms: effect of waveform extraction methodology
Chu, Tony; Fong, Heather; Kumar, Prayush; Pfeiffer, Harald P.; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela
2016-08-01
We present a new set of 95 numerical relativity simulations of non-precessing binary black holes (BBHs). The simulations sample comprehensively both black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1-3. The simulations cover on average 24 inspiral orbits, plus merger and ringdown, with low initial orbital eccentricities e\\lt {10}-4. A subset of the simulations extends the coverage of non-spinning BBHs up to mass ratio q = 10. Gravitational waveforms at asymptotic infinity are computed with two independent techniques: extrapolation and Cauchy characteristic extraction. An error analysis based on noise-weighted inner products is performed. We find that numerical truncation error, error due to gravitational wave extraction, and errors due to the Fourier transformation of signals with finite length of the numerical waveforms are of similar magnitude, with gravitational wave extraction errors dominating at noise-weighted mismatches of ˜ 3× {10}-4. This set of waveforms will serve to validate and improve aligned-spin waveform models for gravitational wave science.
Altunc, Serhat; Baum, Carl E.; Christodoulou, Christos G.; Schamiloglu, Edl; Buchenauer, C. Jerald
2008-08-01
Impulse radiating antennas (IRAs) are designed to radiate very fast pulses in a narrow beam with low dispersion and high field amplitude. For this reason they have been used in a variety of applications. IRAs have been developed for use in the transient far-field region using parabolic reflectors. However, in this paper we focus in the near field region and develop the field waveform at the second focus of a prolate-spheroidal IRA. Certain skin cancers can be killed by the application of a high-amplitude electric field pulse. This can be accomplished by either inserting electrodes near the skin cancer or by applying fast, high-electric field pulses without direct contact. We investigate a new manifestation of an IRA, in which we use a prolate spheroid as a reflector instead of a parabolic reflector and focus in the near-field region instead of the far-field region. This technique minimizes skin damage associated with inserting electrodes near the tumor. Analytical and experimental behaviors for the focal waveforms of two and four-feed arm prolate-spheroidal IRAs are explored. With appropriate choice of the driving waveform we maximize the impulse field at the second focus. The focal waveform of a prolate-spheroidal IRA has been explained theoretically and verified experimentally.
Waveform interative techniques for device transient simulation on parallel machines
Energy Technology Data Exchange (ETDEWEB)
Lumsdaine, A. [Univ. of Notre Dame, IN (United States); Reichelt, M.W. [Massachusetts Institute of Technology, Cambridge, MA (United States)
1993-12-31
In this paper we describe our experiences with parallel implementations of several different waveform algorithms for performing transient simulation of semiconductor devices. Because of their inherent computation and communication structure, waveform methods are well suited to MIMD-type parallel machines having a high communication latency - such as a cluster of workstations. Experimental results using pWORDS, a parallel waveform-based device transient simulation program, in conjunction with PVM running on a cluster of eight workstations demonstrate that parallel waveform techniques are an efficient and faster alternative to standard simulation algorithms.
Adaptive Robust Waveform Selection for Unknown Target Detection in Clutter
Institute of Scientific and Technical Information of China (English)
Lu-Lu Wang; Hong-Qiang Wang; Yu-Liang Qin; Yong-Qiang Cheng
2014-01-01
@@@A basic assumption of most recently proposed waveform design algorithms is that the target impulse response is a known deterministic function or a stochastic process with a known power spectral density (PSD). However, it is well-known that a target impulse response is neither easily nor accurately obtained; besides it changes sharply with attitude angles. Both of the aforementioned cases complicate the waveform design process. In this paper, an adaptive robust waveform selection method for unknown target detection in clutter is proposed. The target impulse response is considered to be unknown but belongs to a known uncertainty set. An adaptive waveform library is devised by using a signal-to-clutter-plus-noise ratio (SCNR)- based optimal waveform design method. By applying the minimax robust waveform selection method, the optimal robust waveform is selected to ensure the lowest performance bound of the unknown target detection in clutter. Results show that the adaptive waveform library outperforms the predefined linear frequency modulation (LFM) waveform library on the SCNR bound.
Designing waveforms for temporal encoding using a frequency sampling method
DEFF Research Database (Denmark)
Gran, Fredrik; Jensen, Jørgen Arendt
2007-01-01
, 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...... for the linear frequency modulated signal) were tested for both waveforms in simulation with respect to the Doppler frequency shift occurring when probing moving objects. It was concluded that the Doppler effect of moving targets does not significantly degrade the filtered output. Finally, in vivo measurements...
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
Waveform Freezing of Sonic Booms Revisited
Cleveland, Robin O.; Blackstock, David T.
1996-01-01
Nonlinear distortion of sonic booms propagating in the atmosphere is strongly affected by stratification and geometrical spreading. For a downward propagating sonic boom in a standard atmosphere, stratification and spreading cause a slowing down of nonlinear distortion. In certain cases a stage is reached where no further distortion takes place. When this happens, the waveform is said to be frozen. In previous work the authors argued that for most HSCT designs and flight conditions being considered, the sonic boom is not frozen when it reaches the ground. The criterion used was the value of the distortion distance x bar is a measure of the nonlinear distortion suffered by the wave (and is closely related to Hayes's E variable). The aircraft must be at an altitude greater than 27 km (80,000 ft) for x bar at the groun be within 95% of its asymptotic value. However, work reported here demonstrates that the ground waveform is much closer to the frozen state than indicated by the previous analysis. In the new analysis, duration of the sonic boom is used as the criterion for judging closeness of approach tz frozen state. In order for the duration of the sonic boom at the ground to be within 95% of its frozen value, the flight altitude of the aircraft needs to be only 15 km (45,000 ft).
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.
ADVANCED WAVEFORM SIMULATION FOR SEISMIC MONITORING EVENTS
Energy Technology Data Exchange (ETDEWEB)
Helmberger, D; Tromp, J; Rodgers, A
2007-07-16
Comprehensive test ban monitoring in terms of location and discrimination has progressed significantly in recent years. However, the characterization of sources and the estimation of low yields remains a particular challenge. As the recent Korean shot demonstrated, we can probably expect to have a small set of teleseismic, far-regional and high-frequency regional data to analyze in estimating the yield of an event. Since stacking helps to bring signals out of the noise, it becomes useful to conduct comparable analyses on neighboring events, earthquakes in this case. If these auxiliary events have accurate moments and source descriptions, we have a means of directly comparing effective source strengths. Although we will rely on modeling codes, 1D, 2D, and 3D, we will also apply a broadband calibration procedure to use longer periods (P>5s) waveform data to calibrate short-period (P between .5 to 2 Hz) and high-frequency (P between 2 to 10 Hz) as path specify station corrections from well-known regional sources. We have expanded our basic Cut-and-Paste (CAP) methodology to include not only timing shifts but also amplitude (f) corrections at recording sites. The name of this method was derived from source inversions that allow timing shifts between 'waveform segments' (or cutting the seismogram up and re-assembling) to correct for crustal variation. For convenience, we will refer to these f-dependent refinements as CAP+ for (SP) and CAP++ for still higher frequency. These methods allow the retrieval of source parameters using only P-waveforms where radiation patterns are obvious as demonstrated in this report and are well suited for explosion P-wave data. The method is easily extended to all distances because it uses Green's function although there may be some changes required in t* to adjust for offsets between local vs. teleseismic distances. In short, we use a mixture of model-dependent and empirical corrections to tackle the path effects. Although
Towards Full-Waveform Ambient Noise Inversion
Sager, Korbinian; Ermert, Laura; Afanasiev, Michael; Boehm, Christian; Fichtner, Andreas
2017-04-01
Noise tomography usually works under the assumption that the inter-station ambient noise correlation is equal to a scaled version of the Green function between the two receivers. This assumption, however, is only met under specific conditions, e.g. wavefield diffusivity and equipartitioning, or the isotropic distribution of both mono- and dipolar uncorrelated noise sources. These assumptions are typically not satisfied in the Earth. This inconsistency inhibits the exploitation of the full waveform information contained in noise correlations in order to constrain Earth structure and noise generation. To overcome this limitation, we attempt to develop a method that consistently accounts for the distribution of noise sources, 3D heterogeneous Earth structure and the full seismic wave propagation physics. This is intended to improve the resolution of tomographic images, to refine noise source distribution, and thereby to contribute to a better understanding of both Earth structure and noise generation. First, we develop an inversion strategy based on a 2D finite-difference code using adjoint techniques. To enable a joint inversion for noise sources and Earth structure, we investigate the following aspects: i) the capability of different misfit functionals to image wave speed anomalies and source distribution and ii) possible source-structure trade-offs, especially to what extent unresolvable structure can be mapped into the inverted noise source distribution and vice versa. In anticipation of real-data applications, we present an extension of the open-source waveform modelling and inversion package Salvus (http://salvus.io). It allows us to compute correlation functions in 3D media with heterogeneous noise sources at the surface and the corresponding sensitivity kernels for the distribution of noise sources and Earth structure. By studying the effect of noise sources on correlation functions in 3D, we validate the aforementioned inversion strategy and prepare the
Tera-sample-per-second Real-time Waveform Digitizer
Han, Y; Jalali, B; Han, Yan; Boyraz, Ozdal; Jalali, Bahram
2005-01-01
We demonstrate a real-time transient waveform digitizer with a record 1 TSa/s (Tera-Sample/sec) sampling rate. This is accomplished by using a photonic time stretch preprocessor which slows down the electrical waveform before it is captured by an electronic digitizer.
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.
Automated multimode inversion of surface and S waveforms
Lebedev, Sergei; Nolet, Guust; Meier, Thomas; Hilst, R.D. van der
2005-01-01
Inversion of the surface, S, and multiple-S waveforms is an effective means of constraining the structure of the upper mantle, including the transition zone. Exploiting the resolving power of the enormous volume of presently available data requires efficiency of data processing and waveform modellin
Analysis of a Proposed Two-Frequency Radar Waveform
1974-11-01
Rice and Dugundji . The waveform at the Input of the detector is u(t) -§ cn cos (UM: + f^) (1) A frequency q called the "midband frequency"is selected...Analysis of Random Noise," Bell Systi Technical Journal. Vol 23, p 81, 1944. 11. J. Dugundji , "Bivelopes and Pre-Envelopes of Real Waveforms," IRE
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.
Waveform Selectivity at the Same Frequency
Wakatsuchi, Hiroki; Rushton, Jeremiah J; Gao, Fei; Kim, Sanghoon; Sievenpiper, Daniel F
2014-01-01
Electromagnetic properties depend on the composition of materials, i.e. either angstrom scales of molecules or, for metamaterials, subwavelength periodic structures. Each material behaves differently in accordance with the frequency of an incoming electromagnetic wave due to the frequency dispersion or the resonance of the periodic structures. This indicates that if the frequency is fixed, the material always responds in the same manner unless it has nonlinearity. However, such nonlinearity is controlled by the magnitude of the incoming wave or other bias. Therefore, it is difficult to distinguish different incoming waves at the same frequency. Here we present a new concept of circuit-based metasurfaces to selectively absorb or transmit specific types of waveforms even at the same frequency. The metasurfaces, integrated with schottky diodes as well as either capacitors or inductors, selectively absorb short or long pulses, respectively. The two types of the circuit elements are then combined to absorb or tran...
Heartrate variation of umbilical artery Doppler waveforms.
Hoskins, P R; Johnstone, F D; Chambers, S E; Haddad, N G; White, G; McDicken, W N
1989-01-01
Umbilical artery Doppler waveforms from 20 patients were used to investigate the dependence of resistance index and pulsatility index on beat to beat pulse length over short time periods for individual patients, and on the usefulness of a common normalisation formula. For individual patients the resistance index and pulsatility index were only partially correlated with pulse length. Changes in both indices occurred independently of pulse length. Use of a common normalisation formula resulted in no significant reduction of the coefficient of variation of the resistance index (p greater than 0.1), and a reduction in the coefficient of variation of the pulsatility index of 10% (p greater than 0.001). It is concluded that short term changes in resistance index and pulsatility index cannot be corrected by a common normalisation formula.
Direct Waveform Inversion by Iterative Inverse Propagation
Schlottmann, R B
2009-01-01
Seismic waves are the most sensitive probe of the Earth's interior we have. With the dense data sets available in exploration, images of subsurface structures can be obtained through processes such as migration. Unfortunately, relating these surface recordings to actual Earth properties is non-trivial. Tomographic techniques use only a small amount of the information contained in the full seismogram and result in relatively low resolution images. Other methods use a larger amount of the seismogram but are based on either linearization of the problem, an expensive statistical search over a limited range of models, or both. We present the development of a new approach to full waveform inversion, i.e., inversion which uses the complete seismogram. This new method, which falls under the general category of inverse scattering, is based on a highly non-linear Fredholm integral equation relating the Earth structure to itself and to the recorded seismograms. An iterative solution to this equation is proposed. The res...
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.
Waveform Synthesizer For Imaging And Ranging Applications
DUDLEY, PETER A.; [et al
2004-11-30
Frequency dependent corrections are provided for quadrature imbalance. An operational procedure filters imbalance effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of quadrature imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.
Integrating Biosystem Models Using Waveform Relaxation
Directory of Open Access Journals (Sweden)
Stephen Baigent
2008-12-01
Full Text Available Modelling in systems biology often involves the integration of component models into larger composite models. How to do this systematically and efficiently is a significant challenge: coupling of components can be unidirectional or bidirectional, and of variable strengths. We adapt the waveform relaxation (WR method for parallel computation of ODEs as a general methodology for computing systems of linked submodels. Four test cases are presented: (i a cascade of unidirectionally and bidirectionally coupled harmonic oscillators, (ii deterministic and stochastic simulations of calcium oscillations, (iii single cell calcium oscillations showing complex behaviour such as periodic and chaotic bursting, and (iv a multicellular calcium model for a cell plate of hepatocytes. We conclude that WR provides a flexible means to deal with multitime-scale computation and model heterogeneity. Global solutions over time can be captured independently of the solution techniques for the individual components, which may be distributed in different computing environments.
Synthetic tsunami waveform catalogs with kinematic constraints
Baptista, Maria Ana; Miranda, Jorge Miguel; Matias, Luis; Omira, Rachid
2017-07-01
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.
Design of a 9-loop quasi-exponential waveform generator.
Banerjee, Partha; Shukla, Rohit; Shyam, Anurag
2015-12-01
We know in an under-damped L-C-R series circuit, current follows a damped sinusoidal waveform. But if a number of sinusoidal waveforms of decreasing time period, generated in an L-C-R circuit, be combined in first quarter cycle of time period, then a quasi-exponential nature of output current waveform can be achieved. In an L-C-R series circuit, quasi-exponential current waveform shows a rising current derivative and thereby finds many applications in pulsed power. Here, we have described design and experiment details of a 9-loop quasi-exponential waveform generator. In that, design details of magnetic switches have also been described. In the experiment, output current of 26 kA has been achieved. It has been shown that how well the experimentally obtained output current profile matches with the numerically computed output.
On the accuracy and precision of numerical waveforms: Effect of waveform extraction methodology
Chu, Tony; Kumar, Prayush; Pfeiffer, Harald P; Boyle, Michael; Hemberger, Daniel A; Kidder, Lawrence E; Scheel, Mark A; Szilagyi, Bela
2015-01-01
We present a new set of 95 numerical relativity simulations of non-precessing binary black holes (BBHs). The simulations sample comprehensively both black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1 to 3. The simulations cover on average 24 inspiral orbits, plus merger and ringdown, with low initial orbital eccentricities $e<10^{-4}$. A subset of the simulations extends the coverage of non-spinning BBHs up to mass ratio $q=10$. Gravitational waveforms at asymptotic infinity are computed with two independent techniques, extrapolation, and Cauchy characteristic extraction. An error analysis based on noise-weighted inner products is performed. We find that numerical truncation error, error due to gravitational wave extraction, and errors due to the finite length of the numerical waveforms are of similar magnitude, with gravitational wave extraction errors somewhat dominating at noise-weighted mismatches of $\\sim 3\\times 10^{-4}$. This set of waveforms will serve to validate and improve ali...
Simulation of Full-Waveform Laser Altimeter Echowaveform
Lv, Y.; Tong, X. H.; Liu, S. J.; Xie, H.; Luan, K. F.; Liu, J.
2016-06-01
Change of globe surface height is an important factor to study human living environment. The Geoscience Laser Altimeter System (GLAS) on ICESat is the first laser-ranging instrument for continuous global observations of the Earth. In order to have a comprehensive understanding of full-waveform laser altimeter, this study simulated the operating mode of ICESat and modeled different terrains' (platform terrain, slope terrain, and artificial terrain) echo waveforms based on the radar equation. By changing the characteristics of the system and the targets, numerical echo waveforms can be achieved. Hereafter, we mainly discussed the factors affecting the amplitude and size (width) of the echoes. The experimental results implied that the slope of the terrain, backscattering coefficient and reflectivity, target height, target position in the footprint and area reacted with the pulse all can affect the energy distribution of the echo waveform and the receiving time. Finally, Gaussian decomposition is utilized to decompose the echo waveform. From the experiment, it can be noted that the factors which can affect the echo waveform and by this way we can know more about large footprint full-waveform satellite laser altimeter.
Design and implementation of a hospital wide waveform capture system.
Blum, James M; Joo, Heyon; Lee, Henry; Saeed, Mohammed
2015-06-01
The use of telemetry and invasive monitoring is exceptionally common in modern healthcare. To date the vast majority of this information is not stored for more than a brief duration on the local monitor. This prohibits extensive investigation into waveform data. We describe a system to collect such data in a quaternary care facility. Using standardized "packet sniffing" technology along with routine manual documentation, we reverse engineered the Unity network protocol used to transmit waveform data across the University of Michigan mission critical monitor network. Data was subsequently captured using a proprietary piece of software writing waveform data to local disks. Nightly, this data is post-processed using data from the admit-discharge-transfer system into individual patient waveforms for the day regardless of location. Over a 10 month period, over 2,785 individual patients had a total of 65,112 waveforms captured 15,978 from the operating rooms and 49,134 from the ICUs. The average OR case collected over 11 MB of data. The average single day data collection consisted of 8.6 GB of data. Entire hospital waveform data collection is possible using internally developed software enabling research on waveform data with minimal technical burden. Further research is required to determine the long-term storage and processing of such data.
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.
Adaptive Prony method for waveform distortion detection in power systems
Energy Technology Data Exchange (ETDEWEB)
Bracale, A.; Carpinelli, G. [Electrical Engineering Department, University of Napoli, Via Claudio 21, 80125 Napoli (Italy); Caramia, P. [Industrial Engineering Department, University of Cassino (Italy)
2007-06-15
IEC Standards characterize the waveform distortions in power systems with the amplitudes of harmonic and interharmonic groupings (subgroups and groups) calculated by using the waveform spectral components obtained with a 5 Hz frequency resolution DFT. In some cases the power system waveforms are characterized by means of spectral signal components that the DFT with 5 Hz frequency resolution is unable to capture with sufficient accuracy. In this paper a new Prony method is proposed to calculate the harmonic and interharmonic subgroups. This method is based on an adaptive technique that acts with the aim of minimizing the mean square relative error of signal estimation. (author)
Compressive full-waveform LIDAR with low-cost sensor
Yang, Weiyi; Ke, Jun
2016-10-01
Full-waveform LiDAR is a method that digitizes the complete waveform of backscattered pulses to obtain range information of multi-targets. To avoid expensive sensors in conventional full-waveform LiDAR system, a new system based on compressive sensing method is presented in this paper. The non-coherent continuous-wave laser is modulated by electro-optical modulator with pseudo-random sequences. A low-bandwidth detector and a low-bandwidth analog-digital converter are used to acquire the returned signal. OMP algorithm is employed to reconstruct the high resolution range information.
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
General Dynamic (GD) Launch Waveform On-Orbit Performance Report
Briones, Janette C.; Shalkhauser, Mary Jo
2014-01-01
The purpose of this report is to present the results from the GD SDR on-orbit performance testing using the launch waveform over TDRSS. The tests include the evaluation of well-tested waveform modes, the operation of RF links that are expected to have high margins, the verification of forward return link operation (including full duplex), the verification of non-coherent operational models, and the verification of radio at-launch operational frequencies. This report also outlines the launch waveform tests conducted and comparisons to the results obtained from ground testing.
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.
Full Waveform Inversion of Solar Interior Flows
Hanasoge, Shravan M
2014-01-01
The inference of flows of material in the interior of the Sun is a subject of major interest in helioseismology. Here we apply techniques of Full Waveform Inversion (FWI) to synthetic data to test flow inversions. In this idealized setup, we do not model seismic realization noise, training the focus entirely on the problem of whether a chosen supergranulation flow model can be seismically recovered. We define the misfit functional as a sum of L_2 norm deviations in travel times between prediction and observation, as measured using short-distance f and p_1 filtered and large-distance unfiltered $p$ modes. FWI allows for the introduction of measurements of choice and iteratively improving the background model, while monitoring the evolution of the misfit in all desired categories. Although the misfit is seen to uniformly reduce in all categories, convergence to the true model is very slow, possibly because it is trapped in a local minimum. The primary source of error is inaccurate depth localization, which, owi...
Tsunami waveform inversion by adjoint methods
Pires, Carlos; Miranda, Pedro M. A.
2001-09-01
An adjoint method for tsunami waveform inversion is proposed, as an alternative to the technique based on Green's functions of the linear long wave model. The method has the advantage of being able to use the nonlinear shallow water equations, or other appropriate equation sets, and to optimize an initial state given as a linear or nonlinear function of any set of free parameters. This last facility is used to perform explicit optimization of the focal fault parameters, characterizing the initial sea surface displacement of tsunamigenic earthquakes. The proposed methodology is validated with experiments using synthetic data, showing the possibility of recovering all relevant details of a tsunami source from tide gauge observations, providing that the adjoint method is constrained in an appropriate manner. It is found, as in other methods, that the inversion skill of tsunami sources increases with the azimuthal and temporal coverage of assimilated tide gauge stations; furthermore, it is shown that the eigenvalue analysis of the Hessian matrix of the cost function provides a consistent and useful methodology to choose the subset of independent parameters that can be inverted with a given dataset of observations and to evaluate the error of the inversion process. The method is also applied to real tide gauge series, from the tsunami of the February 28, 1969, Gorringe Bank earthquake, suggesting some reasonable changes to the assumed focal parameters of that event. It is suggested that the method proposed may be able to deal with transient tsunami sources such as those generated by submarine landslides.
Waveform Analysis of AE in Composites
Prosser, William H.
1998-01-01
Advanced, waveform based acoustic emission (AE) techniques have been developed to evaluate damage mechanisms in the testing of composite materials. This approach, more recently referred to as Modal AE, provides an enhanced capability to discriminate and eliminate noise signals from those generated by damage mechanisms. Much more precise source location can also be obtained in comparison to conventional, threshold crossing arrival time determination techniques. Two successful examples of the application of Modal AE are presented in this work. In the first, the initiation of transverse matrix cracking in cross-ply, tensile coupons was monitored. In these tests, it was documented that the same source mechanism, matrix cracking, can produce widely different AE signal amplitudes dependent on laminate stacking sequence and thickness. These results, taken together with well known propagation effects of attenuation and dispersion of AE signals in composite laminates, cast further doubt on the validity of simple amplitude or amplitude distribution analysis for AE source determination. For the second example, delamination propagation in composite ring specimens was monitored. Pressurization of these composite rings is used to simulate the stresses in a composite rocket motor case. AE signals from delamination propagation were characterized by large amplitude flexural plate mode components which have long signal durations because of the large dispersion of this mode.
Waveform synthesis for imaging and ranging applications
Doerry, Armin W.; Dudley, Peter A.; Dubert, Dale F.; Tise, Bertice L.
2004-12-07
Frequency dependent corrections are provided for quadrature imbalance and Local Oscillator (LO) feed-through. An operational procedure filters imbalance and LO feed-through effects without prior calibration or equalization. Waveform generation can be adjusted/corrected in a synthetic aperture radar system (SAR), where a rolling phase shift is applied to the SAR's QDWS signal where it is demodulated in a receiver; unwanted energies, such as LO feed-through and/or imbalance energy, are separated from a desired signal in Doppler; the separated energy is filtered from the receiver leaving the desired signal; and the separated energy in the receiver is measured to determine the degree of imbalance that is represented by it. Calibration methods can also be implemented into synthesis. The degree of LO feed-through and imbalance can be used to determine calibration values that can then be provided as compensation for frequency dependent errors in components, such as the QDWS and SSB mixer, affecting quadrature signal quality.
Inversion method for initial tsunami waveform reconstruction
Directory of Open Access Journals (Sweden)
V. V. Voronin
2014-12-01
Full Text Available This paper deals with the application of r-solution method to recover the initial tsunami waveform in a tsunami source area by remote water-level measurements. Wave propagation is considered within the scope of a linear shallow-water theory. An ill-posed inverse problem is regularized by means of least square inversion using a truncated SVD approach. The properties of obtained solution are determined to a large extent by the properties of an inverse operator, which were numerically investigated. The method presented allows one to control instability of the numerical solution and to obtain an acceptable result in spite of ill-posedness of the problem. It is shown that the accuracy of tsunami source reconstruction strongly depends on the signal-to-noise ratio, the azimuthal coverage of recording stations with respect to the source area and bathymetric features along the wave path. The numerical experiments were carried out with synthetic data and various computational domains including a real bathymetry. The method proposed allows us to make a preliminary prediction of the efficiency of the inversion with a given set of the recording stations and to find out the most informative part of the existing observation system. This essential property of the method can prove to be useful in designing a monitoring system for tsunamis.
A scalable, fast and multichannel arbitrary waveform generator
Baig, Muhammad Tanveer; Wiese, Andreas; Heidbrink, Stefan; Ziolkowski, Michael; Wunderlich, Christof
2013-01-01
This article reports on development of a multichannel arbitrary waveform generator (MAWG), which simultaneously generates arbitrary voltage waveforms on 24 independent channels with a dynamic update rate of up to 25 Msps. A real-time execution of a single waveform and/or sequence of multiple waveforms in succession, with a user programmable arbitrary sequence order is provided under the control of a stand-alone sequencer circuit implemented using an FPGA. The device is operated using an internal clock and can be synced to other devices by means of the TTL pulses. The device can be used for output voltages in the range of up to +-9 V with a drift rate below +-10 uV/min and a maximum deviation less than +- 300 uVpp over a period of two hours.
Multiscale Stategies in Automatic Image-Domain Waveform Tomography
Institute of Scientific and Technical Information of China (English)
Yujin Liu; Zhenchun Li
2015-01-01
Multiscale strategies are very important in the successful application of waveform-based velocity inversion. The strategy that sequentially preceeds from long to short scale of velocity model, has been well developed in full waveform inversion (FWI) to solve the local mininum problem. In contrast, it’s not well understood in the image-domain waveform tomography (IWT), which back-projects incoherent waveform components of the common image gather into velocity updates. IWT is less prone to local minimum problem but tends to build long-scale model with low resolution. In order to build both long- and short-scale model by IWT, we discuss several multiscale strategies restricted in the image domain. The strategies include model reparameterization, objective function switching and gradient rescaling. Numerical tests on Marmsousi model and real data demonstrate that our proposed multiscale IWT is effective in buidling velocity model with wide wavenumber spectrum.
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.
Hybridizing Gravitationl Waveforms of Inspiralling Binary Neutron Star Systems
Cullen, Torrey; LIGO Collaboration
2016-03-01
Gravitational waves are ripples in space and time and were predicted to be produced by astrophysical systems such as binary neutron stars by Albert Einstein. These are key targets for Laser Interferometer and Gravitational Wave Observatory (LIGO), which uses template waveforms to find weak signals. The simplified template models are known to break down at high frequency, so I wrote code that constructs hybrid waveforms from numerical simulations to accurately cover a large range of frequencies. These hybrid waveforms use Post Newtonian template models at low frequencies and numerical data from simulations at high frequencies. They are constructed by reading in existing Post Newtonian models with the same masses as simulated stars, reading in the numerical data from simulations, and finding the ideal frequency and alignment to ``stitch'' these waveforms together.
Multifocal pattern VEP perimetry: analysis of sectoral waveforms.
Klistorner, A I; Graham, S L
1999-01-01
The objective detection of local visual field defects using multi-focal pattern visual evoked potentials (VEP) has recently been described. The individual waveforms show variable polarity in different parts of the visual field due to underlying cortical convolutions. Normal trace arrays were examined to determine if certain areas of similar waveform could be grouped for analysis, while minimising cancellation of data. The VEP was assessed using multi-focal pseudo-randomly alternated pattern stimuli which were cortically scaled in size. Bipolar occipital electrodes were used for recording. Waveforms were compared for different locations within the field up to 25 degrees of eccentricity. Analysis of sectors showing similarly shaped waveforms was performed. Twelve normal subjects were studied. Grouping waveforms by sectors of similar waveform increased the total calculated upper hemifield amplitude by 60%, compared with simple summations of responses for the whole hemifield. The inferior hemifield showed more consistent waveforms throughout, with the amplitude only increasing by 11% with sectoral summation. Intra-subject variability (10.6%) is less for sectors than for individual points (17.3%). Inter-subject amplitude differences are high, calculated at 56% for individual points and 45% for sectors. Due to differences in waveform as a result of underlying cortical anatomy, individual VEP responses from multifocal recordings should be grouped as sectors along the vertical meridian and above and below the horizontal, rather than by hemifields or quadrants. This finding is significant if one is considering within-field grouping strategies similar to the glaucoma hemifield test used in conventional perimetry, or reporting derived overall VEP amplitudes and latencies from a multifocal recording. Large amplitude variations between individuals and small signals from horizontal and upper field seen in single channel recording, still limit the application of this technique as
Binary black hole waveform extraction at null infinity
Energy Technology Data Exchange (ETDEWEB)
Babiuc, M C [Department of Physics, Marshall University, Huntington, WV 25755 (United States); Winicour, J [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Zlochower, Y, E-mail: babiuc@marshall.edu [Center for Computational Relativity and Gravitation and School of Mathematical Sciences, Rochester Institute of Technology, Rochester, NY 14623 (United States)
2011-07-07
In this paper, we present a work in progress toward an efficient and economical computational module which interfaces between Cauchy and characteristic evolution codes. Our goal is to provide a standardized waveform extraction tool for the numerical relativity community which will allow CCE to be readily applied to a generic Cauchy code. The tool provides a means of unambiguous comparison between the waveforms generated by evolution codes based upon different formulations of the Einstein equations and different numerical approximation.
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.
Use and Abuse of the Model Waveform Accuracy Standards
Lindblom, Lee
2010-02-01
Accuracy standards have been developed to ensure that the waveforms used for gravitational-wave data analysis are good enough to serve their intended purposes. These standards place constraints on certain norms of the frequency-domain representations of the waveform errors. Examples will be presented of possible misinterpretations and misapplications of these standards, whose effect could be to vitiate the quality control they were intended to enforce. Suggestions will be given for ways to avoid these problems. )
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.
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.
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.
Estimation of airway obstruction using oximeter plethysmograph waveform data
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Desmond Renee' A
2005-06-01
Full Text Available Abstract Background Validated measures to assess the severity of airway obstruction in patients with obstructive airway disease are limited. Changes in the pulse oximeter plethysmograph waveform represent fluctuations in arterial flow. Analysis of these fluctuations might be useful clinically if they represent physiologic perturbations resulting from airway obstruction. We tested the hypothesis that the severity of airway obstruction could be estimated using plethysmograph waveform data. Methods Using a closed airway circuit with adjustable inspiratory and expiratory pressure relief valves, airway obstruction was induced in a prospective convenience sample of 31 healthy adult subjects. Maximal change in airway pressure at the mouthpiece was used as a surrogate measure of the degree of obstruction applied. Plethysmograph waveform data and mouthpiece airway pressure were acquired for 60 seconds at increasing levels of inspiratory and expiratory obstruction. At each level of applied obstruction, mean values for maximal change in waveform area under the curve and height as well as maximal change in mouth pressure were calculated for sequential 7.5 second intervals. Correlations of these waveform variables with mouth pressure values were then performed to determine if the magnitude of changes in these variables indicates the severity of airway obstruction. Results There were significant relationships between maximal change in area under the curve (P Conclusion The findings suggest that mathematic interpretation of plethysmograph waveform data may estimate the severity of airway obstruction and be of clinical utility in objective assessment of patients with obstructive airway diseases.
Quantification of wave reflection using peripheral blood pressure waveforms.
Kim, Chang-Sei; Fazeli, Nima; McMurtry, M Sean; Finegan, Barry A; Hahn, Jin-Oh
2015-01-01
This paper presents a novel minimally invasive method for quantifying blood pressure (BP) wave reflection in the arterial tree. In this method, two peripheral BP waveforms are analyzed to obtain an estimate of central aortic BP waveform, which is used together with a peripheral BP waveform to compute forward and backward pressure waves. These forward and backward waves are then used to quantify the strength of wave reflection in the arterial tree. Two unique strengths of the proposed method are that 1) it replaces highly invasive central aortic BP and flow waveforms required in many existing methods by less invasive peripheral BP waveforms, and 2) it does not require estimation of characteristic impedance. The feasibility of the proposed method was examined in an experimental swine subject under a wide range of physiologic states and in 13 cardiac surgery patients. In the swine subject, the method was comparable to the reference method based on central aortic BP and flow. In cardiac surgery patients, the method was able to estimate forward and backward pressure waves in the absence of any central aortic waveforms: on the average, the root-mean-squared error between actual versus computed forward and backward pressure waves was less than 5 mmHg, and the error between actual versus computed reflection index was less than 0.03.
Biomass Estimation for Individual Trees using Waveform LiDAR
Wang, K.; Kumar, P.; Dutta, D.
2015-12-01
Vegetation biomass information is important for many ecological models that include terrestrial vegetation in their simulations. Biomass has strong influences on carbon, water, and nutrient cycles. Traditionally biomass estimation requires intensive, and often destructive, field measurements. However, with advances in technology, airborne LiDAR has become a convenient tool for acquiring such information on a large scale. In this study, we use infrared full waveform LiDAR to estimate biomass information for individual trees in the Sangamon River basin in Illinois, USA. During this process, we also develop automated geolocation calibration algorithms for raw waveform LiDAR data. In the summer of 2014, discrete and waveform LiDAR data were collected over the Sangamon River basin. Field measurements commonly used in biomass equations such as diameter at breast height and total tree height were also taken for four sites across the basin. Using discrete LiDAR data, individual trees are delineated. For each tree, a voxelization methods is applied to all waveforms associated with the tree to result in a pseudo-waveform. By relating biomass extrapolated using field measurements from a training set of trees to waveform metrics for each corresponding tree, we are able to estimate biomass on an individual tree basis. The results can be especially useful as current models increase in resolution.
Influential factors for pressure pulse waveform in healthy young adults.
Du, Yi; Wang, Ling; Li, Shuyu; Zhi, Guang; Li, Deyu; Zhang, Chi
2015-01-01
The effects of gender and other contributory factors on pulse waveform are still under arguments. In view of different results caused by few considerations of possible influential factors and general agreement of gender relating to pulse waveform, this study aims to address the confounding factors interfering with the association between gender and pulse waveform characteristics. A novel method was proposed to noninvasively detect pressure pulse wave and assess the morphology of pulse wave. Forty healthy young subjects were included in the present research. Height, weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured manually and body mass index (BMI), pulse blood pressure (PP) and heart rate (HR) were calculated automatically. Student's t test was used to analyze the gender difference and analysis of variance (ANOVA) to examine the effects of intrinsic factors. Univariate regression analysis was performed to assess the main factors on the waveform characteristics. Waveform features were found significantly different between genders. However this study indicates that the main factors for time-related and amplitude-related parameters are HR and SBP respectively. In conclusion, the impact of HR and SBP on pulse waveform features should not be underestimated, especially when analyzing the gender difference.
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.
Waveform descriptor for pulse onset detection of intracranial pressure signal.
Yang, Li; Zhao, Mingxi; Peng, Chenglin; Hu, Xiao; Feng, Hua; Ji, Zhong
2012-03-01
We present an algorithm to identify the onset of intracranial pressure (ICP) pulses. The algorithm creates a waveform descriptor to extract the feature of each local minimum of the waveform and then identifies the onset by comparing the feature with a customized template. The waveform descriptor is derived by transforming the vectors connecting a given point and the local waveform samples around it into log-polar coordinates and ranking them into uniform bins. Using an ICP dataset consisting of 40933 normal beats and 306 segments of artifacts and noise, we investigated the performance of our algorithm (waveform descriptor, WD), global minimum within a sliding window (GM) and two other algorithms originally proposed for arterial blood pressure (ABP) signal (slope sum function, SSF and pulse waveform delineator, PUD). As a result, all the four algorithms showed good performance and WD showed overall better one. At a tolerance level of 30 ms (i.e., the predicted onset and ground truth were considered as correctly matched if the distance between the two was equal or less than 30 ms), WD achieved a sensitivity of 0.9723 and PPV of 0.9475, GM achieved a sensitivity of 0.9226 and PPV of 0.8968, PUD achieved a sensitivity of 0.9599 and PPV of 0.9327 and SSF, a sensitivity of 0.9720 and PPV of 0.9136. The evaluation indicates that the algorithms are effective for identifying the onset of ICP pulses.
An improved driving waveform reference grayscale of electrophoretic displays
Wang, Li; Yi, Zichuan; Peng, Bao; Zhou, Guofu
2015-10-01
Driving waveform is an important component for gray scale display on the electrophoretic display (EPD). In the traditional driving waveform, a white reference gray scale is formed before writing a new image. However, the reflectance value can not reach agreement in each gray scale transformation. In this paper, a new driving waveform, which has a short waiting time after the formation of reference gray scale, is proposed to improve the consistency of reference gray scale. Firstly, the property of the particles in the microcapsule is analyzed and the change of the EPD reflectance after the white reference gray scale formation is studied. Secondly, the reflectance change curve is fitted by using polynomial and the duration of the waiting time is determined. Thirdly, a set of the new driving waveform is designed by using the rule of DC balance and some real E-ink commercial EPDs are used to test the performance. Experimental results show that the effect of the new driving waveform has a better performance than traditional waveforms.
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.
Talker identification from analysis of raw complex waveforms
Stokes, Michael A.
2002-05-01
Stokes (1996) demonstrated that visual inspection of raw complex waveforms can be used to identify a vowel produced by a talker. This research resulted in the MAS Model of Vowel Perception and Production (Stokes, 1998; http://home.indy.net/~masmodel/). More recently, another experiment extended this work to female talkers as well as male talkers (Stokes, 2001). Together, this research represents the only ongoing comprehensive research involving visual inspection of raw complex waveforms for identifying vowels produced by any talker. As an extension of the work, the present study involves identifying a talker from a waveform display. Unique voice signatures identified from waveform displays are used to identify a talker from a set of 10 talkers in the same way as one would identify a person from fingerprints. In two trials (the word who'd in trial 1 and heed in trial 2), a talker was correctly identified from a set of 10 unique talkers per trial using small visual samples of waveforms and matching it to a waveform sample of the talkers to be identified.
Schumacher, Florian; Friederich, Wolfgang; Lamara, Samir; Gutt, Phillip; Paffrath, Marcel
2015-04-01
We present a seismic full waveform inversion concept for applications ranging from seismological to enineering contexts, based on sensitivity kernels for full waveforms. The kernels are derived from Born scattering theory as the Fréchet derivatives of linearized frequency-domain full waveform data functionals, quantifying the influence of elastic earth model parameters and density on the data values. For a specific source-receiver combination, the kernel is computed from the displacement and strain field spectrum originating from the source evaluated throughout the inversion domain, as well as the Green function spectrum and its strains originating from the receiver. By storing the wavefield spectra of specific sources/receivers, they can be re-used for kernel computation for different specific source-receiver combinations, optimizing the total number of required forward simulations. In the iterative inversion procedure, the solution of the forward problem, the computation of sensitivity kernels and the derivation of a model update is held completely separate. In particular, the model description for the forward problem and the description of the inverted model update are kept independent. Hence, the resolution of the inverted model as well as the complexity of solving the forward problem can be iteratively increased (with increasing frequency content of the inverted data subset). This may regularize the overall inverse problem and optimizes the computational effort of both, solving the forward problem and computing the model update. The required interconnection of arbitrary unstructured volume and point grids is realized by generalized high-order integration rules and 3D-unstructured interpolation methods. The model update is inferred solving a minimization problem in a least-squares sense, resulting in Gauss-Newton convergence of the overall inversion process. The inversion method was implemented in the modularized software package ASKI (Analysis of Sensitivity
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.
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)
2014-01-01
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.
Global and local waveform simulations using the VERCE platform
Garth, Thomas; Saleh, Rafiq; Spinuso, Alessandro; Gemund, Andre; Casarotti, Emanuele; Magnoni, Federica; Krischner, Lion; Igel, Heiner; Schlichtweg, Horst; Frank, Anton; Michelini, Alberto; Vilotte, Jean-Pierre; Rietbrock, Andreas
2017-04-01
In recent years the potential to increase resolution of seismic imaging by full waveform inversion has been demonstrated on a range of scales from basin to continental scales. These techniques rely on harnessing the computational power of large supercomputers, and running large parallel codes to simulate the seismic wave field in a three-dimensional geological setting. The VERCE platform is designed to make these full waveform techniques accessible to a far wider spectrum of the seismological community. The platform supports the two widely used spectral element simulation programs SPECFEM3D Cartesian, and SPECFEM3D globe, allowing users to run a wide range of simulations. In the SPECFEM3D Cartesian implementation the user can run waveform simulations on a range of pre-loaded meshes and velocity models for specific areas, or upload their own velocity model and mesh. In the new SPECFEM3D globe implementation, the user will be able to select from a number of continent scale model regions, or perform waveform simulations for the whole earth. Earthquake focal mechanisms can be downloaded within the platform, for example from the GCMT catalogue, or users can upload their own focal mechanism catalogue through the platform. The simulations can be run on a range of European supercomputers in the PRACE network. Once a job has been submitted and run through the platform, the simulated waveforms can be manipulated or downloaded for further analysis. The misfit between the simulated and recorded waveforms can then be calculated through the platform through three interoperable workflows, for raw-data access (FDSN) and caching, pre-processing and finally misfit. The last workflow makes use of the Pyflex analysis software. In addition, the VERCE platform can be used to produce animations of waveform propagation through the velocity model, and synthetic shakemaps. All these data-products are made discoverable and re-usable thanks to the VERCE data and metadata management layer. We
Gao, Mingwu; Rose, William C; Fetics, Barry; Kass, David A; Chen, Chen-Huan; Mukkamala, Ramakrishna
2016-09-14
Generalized transfer functions (GTFs) are available to compute the more relevant central blood pressure (BP) waveform from a more easily measured radial BP waveform. However, GTFs are population averages and therefore may not adapt to variations in pulse pressure (PP) amplification (ratio of radial to central PP). A simple adaptive transfer function (ATF) was developed. First, the transfer function is defined in terms of the wave travel time and reflection coefficient parameters of an arterial model. Then, the parameters are estimated from the radial BP waveform by exploiting the observation that central BP waveforms exhibit exponential diastolic decays. The ATF was assessed using the original data that helped popularize the GTF. These data included radial BP waveforms and invasive reference central BP waveforms from cardiac catheterization patients. The data were divided into low, middle, and high PP amplification groups. The ATF estimated central BP with greater accuracy than GTFs in the low PP amplification group (e.g., central systolic BP and PP root-mean-square-errors of 3.3 and 4.2 mm Hg versus 6.2 and 7.1 mm Hg; p ≤ 0.05) while showing similar accuracy in the higher PP amplification groups. The ATF may permit more accurate, non-invasive central BP monitoring in elderly and hypertensive patients.
Estimation of earthquake source parameters by the inversion of waveform data: synthetic waveforms
Sipkin, S.A.
1982-01-01
Two methods are presented for the recovery of a time-dependent moment-tensor source from waveform data. One procedure utilizes multichannel signal-enhancement theory; in the other a multichannel vector-deconvolution approach, developed by Oldenburg (1982) and based on Backus-Gilbert inverse theory, is used. These methods have the advantage of being extremely flexible; both may be used either routinely or as research tools for studying particular earthquakes in detail. Both methods are also robust with respect to small errors in the Green's functions and may be used to refine estimates of source depth by minimizing the misfits to the data. The multichannel vector-deconvolution approach, although it requires more interaction, also allows a trade-off between resolution and accuracy, and complete statistics for the solution are obtained. The procedures have been tested using a number of synthetic body-wave data sets, including point and complex sources, with satisfactory results. ?? 1982.
Quantitative analysis of sensor for pressure waveform measurement
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Tyan Chu-Chang
2010-01-01
Full Text Available Abstract Background Arterial pressure waveforms contain important diagnostic and physiological information since their contour depends on a healthy cardiovascular system 1. A sensor was placed at the measured artery and some contact pressure was used to measure the pressure waveform. However, where is the location of the sensor just about enough to detect a complete pressure waveform for the diagnosis? How much contact pressure is needed over the pulse point? These two problems still remain unresolved. Method In this study, we propose a quantitative analysis to evaluate the pressure waveform for locating the position and applying the appropriate force between the sensor and the radial artery. The two-axis mechanism and the modified sensor have been designed to estimate the radial arterial width and detect the contact pressure. The template matching method was used to analyze the pressure waveform. In the X-axis scan, we found that the arterial diameter changed waveform (ADCW and the pressure waveform would change from small to large and then back to small again when the sensor was moved across the radial artery. In the Z-axis scan, we also found that the ADCW and the pressure waveform would change from small to large and then back to small again when the applied contact pressure continuously increased. Results In the X-axis scan, the template correlation coefficients of the left and right boundaries of the radial arterial width were 0.987 ± 0.016 and 0.978 ± 0.028, respectively. In the Z-axis scan, when the excessive contact pressure was more than 100 mm Hg, the template correlation was below 0.983. In applying force, when using the maximum amplitude as the criteria level, the lower contact pressure (r = 0.988 ± 0.004 was better than the higher contact pressure (r = 0.976 ± 0.012. Conclusions Although, the optimal detective position has to be close to the middle of the radial arterial, the pressure waveform also has a good completeness with
A Time Domain Waveform for Testing General Relativity
Huwyler, Cédric; Jetzer, Philippe
2014-01-01
Gravitational-wave parameter estimation is only as good as the theory the waveform generation models are based upon. It is therefore crucial to test General Relativity (GR) once data becomes available. Many previous works, such as studies connected with the ppE framework by Yunes and Pretorius, rely on the stationary phase approximation (SPA) to model deviations from GR in the frequency domain. As Fast Fourier Transform algorithms have become considerably faster and in order to circumvent possible problems with the SPA, we test GR with corrected time domain waveforms instead of SPA waveforms. Since a considerable amount of work has been done already in the field using SPA waveforms, we establish a connection between leading-order-corrected waveforms in time and frequency domain, concentrating on phase-only corrected terms. In a Markov Chain Monte Carlo study, whose results are preliminary and will only be available later, we will assess the ability of the eLISA detector to measure deviations from GR for signa...
Ocular pressure waveform reflects ventricular bigeminy and aortic insufficiency
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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.
Breast ultrasound computed tomography using waveform inversion with source encoding
Wang, Kun; Matthews, Thomas; Anis, Fatima; Li, Cuiping; Duric, Neb; Anastasio, Mark A.
2015-03-01
Ultrasound computed tomography (USCT) holds great promise for improving the detection and management of breast cancer. Because they are based on the acoustic wave equation, waveform inversion-based reconstruction methods can produce images that possess improved spatial resolution properties over those produced by ray-based methods. However, waveform inversion methods are computationally demanding and have not been applied widely in USCT breast imaging. In this work, source encoding concepts are employed to develop an accelerated USCT reconstruction method that circumvents the large computational burden of conventional waveform inversion methods. This method, referred to as the waveform inversion with source encoding (WISE) method, encodes the measurement data using a random encoding vector and determines an estimate of the speed-of-sound distribution by solving a stochastic optimization problem by use of a stochastic gradient descent algorithm. Computer-simulation studies are conducted to demonstrate the use of the WISE method. Using a single graphics processing unit card, each iteration can be completed within 25 seconds for a 128 × 128 mm2 reconstruction region. The results suggest that the WISE method maintains the high spatial resolution of waveform inversion methods while significantly reducing the computational burden.
Shaping the spectrum of random-phase radar waveforms
Energy Technology Data Exchange (ETDEWEB)
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.
Stimulator with arbitrary waveform for auditory evoked potentials
Energy Technology Data Exchange (ETDEWEB)
Martins, H R; Romao, M; Placido, D; Provenzano, F; Tierra-Criollo, C J [Universidade Federal de Minas Gerais (UFMG), Departamento de Engenharia Eletrica (DEE), Nucleo de Estudos e Pesquisa em Engenharia Biomedica NEPEB, Av. Ant. Carlos, 6627, sala 2206, Pampulha, Belo Horizonte, MG, 31.270-901 (Brazil)
2007-11-15
The technological improvement helps many medical areas. The audiometric exams involving the auditory evoked potentials can make better diagnoses of auditory disorders. This paper proposes the development of a stimulator based on Digital Signal Processor. This stimulator is the first step of an auditory evoked potential system based on the ADSP-BF533 EZ KIT LITE (Analog Devices Company - USA). The stimulator can generate arbitrary waveform like Sine Waves, Modulated Amplitude, Pulses, Bursts and Pips. The waveforms are generated through a graphical interface programmed in C++ in which the user can define the parameters of the waveform. Furthermore, the user can set the exam parameters as number of stimuli, time with stimulation (Time ON) and time without stimulus (Time OFF). In future works will be implemented another parts of the system that includes the acquirement of electroencephalogram and signal processing to estimate and analyze the evoked potential.
Fast evaluation of asymptotic waveforms from gravitational perturbations
Benedict, Alex G; Lau, Stephen R
2012-01-01
In the context of blackhole perturbation theory, we describe both exact evaluation of an asymptotic waveform from a time series recorded at a finite radial location and its numerical approximation. From the user's standpoint our technique is easy to implement, affords high accuracy, and works for both axial (Regge-Wheeler) and polar (Zerilli) sectors. Our focus is on the ease of implementation with publicly available numerical tables, either as part of an existing evolution code or a post-processing step. Nevertheless, we also present a thorough theoretical discussion of asymptotic waveform evaluation and radiation boundary conditions, which need not be understood by a user of our methods. In particular, we identify (both in the time and frequency domains) analytical asymptotic waveform evaluation kernels, and describe their approximation by techniques developed by Alpert, Greengard, and Hagstrom. This paper also presents new results on the evaluation of far-field signals for the ordinary (acoustic) wave equa...
Schwarz waveform relaxation algorithm for heat equations with distributed delay
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Wu Shu-Lin
2016-01-01
Full Text Available Heat equations with distributed delay are a class of mathematic models that has wide applications in many fields. Numerical computation plays an important role in the investigation of these equations, because the analytic solutions of partial differential equations with time delay are usually unavailable. On the other hand, duo to the delay property, numerical computation of these equations is time-consuming. To reduce the computation time, we analyze in this paper the Schwarz waveform relaxation algorithm with Robin transmission conditions. The Robin transmission conditions contain a free parameter, which has a significant effect on the convergence rate of the Schwarz waveform relaxation algorithm. Determining the Robin parameter is therefore one of the top-priority matters for the study of the Schwarz waveform relaxation algorithm. We provide new formula to fix the Robin parameter and we show numerically that the new Robin parameter is more efficient than the one proposed previously in the literature.
Classification of Pulse Waveforms Using Edit Distance with Real Penalty
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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.
Model Waveform Accuracy Requirements for the $\\chi^2$ Discriminator
Lindblom, Lee
2016-01-01
This paper derives accuracy standards for model gravitational waveforms required to ensure proper use of the $\\chi^2$ discriminator test in gravitational wave (GW) data analysis. These standards are different from previously established requirements for detection and waveform parameter measurement based on signal-to-noise optimization. We present convenient formulae both for evaluating and interpreting the contribution of model errors to measured $\\chi^2$ values. Motivated by these formula, we also present an enhanced, complexified variant of the standard $\\chi^2$ statistic used in GW searches. While our results are not directly relevant to current searches (which use the $\\chi^2$ test only to veto signal candidates with extremely high $\\chi^2$ values), they could be useful in future GW searches and as figures of merit for model gravitational waveforms.
A 10 tesla table-top controlled waveform magnet.
Roy Choudhury, Aditya N; Venkataraman, V
2012-04-01
Controlled waveform magnets (CWMs) are a class of pulsed magnets whose pulse shape with time can be programmed by the user. With a CWM, the user gains control not only over the magnitude of the field but also over its rate of change. In this work we present a table-top CWM, driven by a capacitor bank, capable of producing virtually any user-shaped magnetic field waveform up to 10 tesla. Insulated gate bipolar transistor chips have been paralleled to form the high current switch and paralleled chips of SiC Schottky diodes form the crowbar diode module. Sample controlled waveforms including flat-tops up to 10 tesla and some triangular magnetic field pulses have been successfully generated for 10-20 ms with a ripple <1%.
Autocorrelation Properties of OFDM Timing Synchronization Waveforms Employing Pilot Subcarriers
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Oktay Üreten
2009-01-01
Full Text Available We investigate the autocorrelation properties of timing synchronization waveforms that are generated by embedded frequency domain pilot tones in orthogonal frequency division multiplex (OFDM systems. The waveforms are composed by summing a selected number of OFDM subcarriers such that the autocorrelation function (ACF of the resulting time waveform has desirable sidelobe behavior. Analytical expressions for the periodic and aperiodic ACF sidelobe energy are derived. Sufficient conditions for minimum and maximum aperiodic ACF sidelobe energy for a given number of pilot tones are presented. Several useful properties of the pilot design problem, such as invariance under transformations and equivalence of complementary sets are demonstrated analytically. Pilot tone design discussion is expanded to the ACF sidelobe peak minimization problem by including various examples and simulation results obtained from a genetic search algorithm.
Autocorrelation Properties of OFDM Timing Synchronization Waveforms Employing Pilot Subcarriers
Directory of Open Access Journals (Sweden)
Taşcıoğlu Selçuk
2009-01-01
Full Text Available Abstract We investigate the autocorrelation properties of timing synchronization waveforms that are generated by embedded frequency domain pilot tones in orthogonal frequency division multiplex (OFDM systems. The waveforms are composed by summing a selected number of OFDM subcarriers such that the autocorrelation function (ACF of the resulting time waveform has desirable sidelobe behavior. Analytical expressions for the periodic and aperiodic ACF sidelobe energy are derived. Sufficient conditions for minimum and maximum aperiodic ACF sidelobe energy for a given number of pilot tones are presented. Several useful properties of the pilot design problem, such as invariance under transformations and equivalence of complementary sets are demonstrated analytically. Pilot tone design discussion is expanded to the ACF sidelobe peak minimization problem by including various examples and simulation results obtained from a genetic search algorithm.
Agile high resolution arbitrary waveform generator with jitterless frequency stepping
Reilly, Peter T. A.; Koizumi, Hideya
2010-05-11
Jitterless transition of the programmable clock waveform is generated employing a set of two coupled direct digital synthesis (DDS) circuits. The first phase accumulator in the first DDS circuit runs at least one cycle of a common reference clock for the DDS circuits ahead of the second phase accumulator in the second DDS circuit. As a phase transition through the beginning of a phase cycle is detected from the first phase accumulator, a first phase offset word and a second phase offset word for the first and second phase accumulators are calculated and loaded into the first and second DDS circuits. The programmable clock waveform is employed as a clock input for the RAM address controller. A well defined jitterless transition in frequency of the arbitrary waveform is provided which coincides with the beginning of the phase cycle of the DDS output signal from the second DDS circuit.
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.
Ultra-wideband noise radar based on optical waveform generation
Grodensky, Daniel; Kravitz, Daniel; Zadok, Avi
2012-06-01
A microwave-photonic, ultra-wideband (UWB) noise radar system is proposed and demonstrated. The system brings together photonic generation of UWB waveforms and fiber-optic distribution. The use of UWB noise provides high ranging resolution and better immunity to interception and jamming. Distribution over fibers allows for the separation the radar-operating personnel and equipment from the location of the front-end. The noise waveforms are generated using the amplified spontaneous emission that is associated with stimulated Brillouin scattering in a standard optical fiber, or with an erbium-doped fiber amplifier. Our experiments demonstrate a proof of concept for an integrated radar system, driven by optically generated UWB noise waveforms of more than 1 GHz bandwidth that are distributed over 10 km distance. The detection of concealed metallic object and the resolving of two targets with the anticipated ranging resolution are reported.
Design of output voltage waveform on magnetic encoder
Energy Technology Data Exchange (ETDEWEB)
Shi Yu E-mail: shiyu_aaa@163.com; Zhang Huaiwu; Jiang Xiangdong; Wen Qiye; Han Baoshan
2004-11-01
A novel design model based on slant multi-phase filter (SMPF) theory is presented. By the theory nth harmonic voltage (n=2nd, 3rd and 4th...(V)) can be reduced easily. Magnetic encoder with sinusoidal output voltage waveform has been developed and sinusoidal output waveform can be easily improved. The minimum of distortion factor was observed when the difference of slant phase is 2{pi}3. This result agrees with SMPF theory value {phi}=4.904 deg. (p=0.8 mm, l=3 mm, {delta}{theta}=2{pi}3]. This result can be widely used in magnetoresistive sensor fields.
Efficient 2d full waveform inversion using Fortran coarray
Ryu, Donghyun; Kim, ahreum; Ha, Wansoo
2016-04-01
We developed a time-domain seismic inversion program using the coarray feature of the Fortran 2008 standard to parallelize the algorithm. We converted a 2d acoustic parallel full waveform inversion program with Message Passing Interface (MPI) to a coarray program and examined performance of the two inversion programs. The results show that the speed of the waveform inversion program using the coarray is slightly faster than that of the MPI version. The standard coarray lacks features for collective communication; however, it can be improved in following standards since it is introduced recently. The parallel algorithm can be applied for 3D seismic data processing.
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.
A Novel Memory Compress Algorithm for Arbitrary Waveform Generator
Institute of Scientific and Technical Information of China (English)
吕铁良; 仇玉林
2000-01-01
A memory compress algorithm for 12-bit Arbitrary Waveform Generator (AWG) is presented and optimized. It can compress waveform memory for a sinusoid to 16× 13hits with a Spurious-Free Dynamic Range (SFDR) 90.7dBc (1/1890 of uncompressed memory at the same SFDR) and to 8× 12bits with a SFDR 79dBc. Its hardware cost is six adders and two multipliers. Exploiting this memory compress technique makes it possible to build a high performance AWG on a chip.
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
Full waveform modelling and misfit calculation using the VERCE platform
Garth, Thomas; Spinuso, Alessandro; Casarotti, Emanuele; Magnoni, Federica; Krischner, Lion; Igel, Heiner; Schwichtenberg, Horst; Frank, Anton; Vilotte, Jean-Pierre; Rietbrock, Andreas
2016-04-01
In recent years the increasing resolution of seismic imagining by full waveform inversion has opened new research perspectives and practices. These methods rely on harnessing the computational power of large supercomputers and new storage capabilities, to run large parallel codes to simulate the seismic wave field in three-dimensional geological settings. The VERCE platform is designed to make these full waveform techniques accessible to a far wider spectrum of the seismological community. VERCE empowers a broad base of seismology researchers to harvest the new opportunities provided by well-established high-performance wave simulation codes such as SPECFEM3D. It meets a range of seismic research needs by eliminating the technical difficulties associated with using these codes, allowing users to focus on their research questions. VERCE delivers this power to seismologists through its science gateway, supporting wave simulation codes on each of the provided computing resources. Users can design their waveform simulation scenarios making use of a library of pre-loaded meshes and velocity models, and services for selecting earthquake focal mechanisms, seismic stations and recorded waveforms from existing catalogues, such as the GCMT catalogue, and FDSN data sources. They can also supply their own mesh, velocity model, earthquake catalogue and seismic observations. They can submit the simulations onto different computing resources, where VERCE provides codes that are tuned and supported for those resources. The simulations can currently be run on a range of European supercomputers in the PRACE network, including superMUC at LRZ, GALILEO at CINECA and on selected resources like Drachenfels at SCAI and within the EGI network. The gateway automates and looks after all these stages, but supplies seismologists with a provenance system that allows them to manage a large series of runs, review progress, and explore the results. The platform automates misfit analysis between
Sonar waveforms for reverberation rejection, part I: theory
Doist, Y.; Deruz, L.; Been, R.
2000-01-01
The influence of the waveform of the transmitted signal on the signal to reverberation ratio induced at the processing output of a moving sonar array is analysed on an theoretical basis. Three main classes of signals are analysed: wide band signals with a flat spectrum (for instance FM signals), con
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
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
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.
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.
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.
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.
Notched spectrum: from probing waveforms to receive filters
Jiang, Yi; Gianelli, Christopher D.
2013-05-01
The increasing demand for wireless data services and communications is expanding the frequency footprint of both civilian and military wireless networks, and hence encroaches upon spectrum traditionally reserved for radar systems. To maximize spectral efficiency, it is desirable for a modern radar system to use waveforms with the ability to fit into tightly controlled spectral regions, which requires the formation of nulls with required notching levels on prescribed frequency stop-bands. Additionally, the waveform should posses a low peak-to-average ratio (PAR), and have good auto-correlation performance. In this work, we propose a novel method for the design of such a waveform using alternating convex optimization. The core module of the proposed algorithm is a fast Fourier transform, which makes the algorithm quite efficient and can handle waveform designs with up to 105 samples. Moreover, our algorithm can achieve a flexible tradeoff between PAR and reduced pass band ripple. A simple application in synthetic aperture radar is considered to highlight the performance of the design algorithm.
Automated microseismic event location using Master-Event Waveform Stacking
Grigoli, Francesco; Cesca, Simone; Krieger, Lars; Kriegerowski, Marius; Gammaldi, Sergio; Horalek, Josef; Priolo, Enrico; Dahm, Torsten
2016-05-01
Accurate and automated locations of microseismic events are desirable for many seismological and industrial applications. The analysis of microseismicity is particularly challenging because of weak seismic signals with low signal-to-noise ratio. Traditional location approaches rely on automated picking, based on individual seismograms, and make no use of the coherency information between signals at different stations. This strong limitation has been overcome by full-waveform location methods, which exploit the coherency of waveforms at different stations and improve the location robustness even in presence of noise. However, the performance of these methods strongly depend on the accuracy of the adopted velocity model, which is often quite rough; inaccurate models result in large location errors. We present an improved waveform stacking location method based on source-specific station corrections. Our method inherits the advantages of full-waveform location methods while strongly mitigating the dependency on the accuracy of the velocity model. With this approach the influence of an inaccurate velocity model on the results is restricted to the estimation of travel times solely within the seismogenic volume, but not for the entire source-receiver path. We finally successfully applied our new method to a realistic synthetic dataset as well as real data.
A marked point process for modeling lidar waveforms.
Mallet, Clément; Lafarge, Florent; Roux, Michel; Soergel, Uwe; Bretar, Frédéric; Heipke, Christian
2010-12-01
Lidar waveforms are 1-D signals representing a train of echoes caused by reflections at different targets. Modeling these echoes with the appropriate parametric function is useful to retrieve information about the physical characteristics of the targets. This paper presents a new probabilistic model based upon a marked point process which reconstructs the echoes from recorded discrete waveforms as a sequence of parametric curves. Such an approach allows to fit each mode of a waveform with the most suitable function and to deal with both, symmetric and asymmetric, echoes. The model takes into account a data term, which measures the coherence between the models and the waveforms, and a regularization term, which introduces prior knowledge on the reconstructed signal. The exploration of the associated configuration space is performed by a reversible jump Markov chain Monte Carlo (RJMCMC) sampler coupled with simulated annealing. Experiments with different kinds of lidar signals, especially from urban scenes, show the high potential of the proposed approach. To further demonstrate the advantages of the suggested method, actual laser scans are classified and the results are reported.
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.
Applying the Moment Distance Framework to LiDAR Waveforms
Salas, E. L.; Aguilar-Amuchastegui, N.; Henebry, G. M.
2010-12-01
In the past decade or so, there have only been limited approaches formulated for the analysis of waveform LiDAR data. We illustrate how the Moment Distance (MD) framework can characterize the shape of the LiDAR waveforms using simple, computationally fast, geometric operations. We assess the relationship of the MD metrics to some key waveform landmarks - such as locations of peaks, power of returns, and pseudo-heights - using LVIS datasets acquired over a tropical forest in La Selva, Costa Rica in 1998 and 2005. We also apply the MD framework to 2003 LVIS data from Howland Forest, Maine. We also explore the effects of noise on the MD Index (MDI). Our results reveal that the MDI can capture important dynamics in canopy structure. Movement in the location of the peaks is detected by shifts in the MDI. Because this new approach responds to waveform shape, it is more sensitive to changes of location of peak returns than to the power of the return. Results also suggest a positive relationship between the MDI and the canopy pseudo-height.
Structural similarity regularization scheme for multiparameter seismic full waveform inversion
Li, M.; Liang, L.; Abubakar, A.; Van den Berg, P.M.
2013-01-01
We introduce a new regularization scheme for multiparameter seismic full-waveform inversion (FWI). Using this scheme, we can constrain spatial variations of parameters which are having a weak sensitivity with the one that having a good sensitivity to the measurement, assuming that these parameters h
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...
Analysis of LFM-waveform Libraries for Cognitive Tracking Maneuvering Targets
Directory of Open Access Journals (Sweden)
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.
GLAS/ICESat L1B Global Waveform-based Range Corrections Data V033
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...
Non-sinusoidal waveform effects on heat transfer performance in pulsating pipe flow
Directory of Open Access Journals (Sweden)
R. Roslan
2016-12-01
Full Text Available In the present paper, an unsteady motion of fluid flow in a pulsating pipe is studied to determine the effect of non-sinusoidal waveforms on the heat transfer performance. Three non-sinusoidal waveforms, namely sawtooth, square and triangular waveforms have been considered. Explicit analytical expressions for a periodic laminar flow describing the flow and heat transfer at small and large times with sawtooth and square pressure waveforms have been derived using Bessel transform technique. The heat transfer performance of periodic flow at sawtooth and square pressure waveforms has been compared with the published result for triangular waveform [1]. The temperature performance for a triangular waveform pressure is very different from the sawtooth and square pressure waveforms.
Ultralow-velocity zone geometries resolved by multidimensional waveform modelling
Vanacore, E. A.; Rost, S.; Thorne, M. S.
2016-07-01
Ultralow-velocity zones (ULVZs) are thin patches of material with strongly reduced seismic wave speeds situated on top of the core-mantle boundary (CMB). A common phase used to detect ULVZs is SPdKS (SKPdS), an SKS wave with a short diffracted P leg along the CMB. Most previous efforts have examined ULVZ properties using 1-D waveform modelling approaches. We present waveform modelling results using the 2.5-D finite-difference algorithm PSVaxi allowing us better insight into ULVZ structure and location. We characterize ULVZ waveforms based on ULVZ elastic properties, shape and position along the SPdKS ray path. In particular, we vary the ULVZ location (e.g. source or receiver side), ULVZ topographical profiles (e.g. boxcar, trapezoidal or Gaussian) and ULVZ lateral scale along great circle path (2.5°, 5°, 10°). We observe several waveform effects absent in 1-D ULVZ models and show evidence for waveform effects allowing the differentiation between source and receiver side ULVZs. Early inception of the SPdKS/SKPdS phase is difficult to detect for receiver-side ULVZs with maximum shifts in SKPdS initiation of ˜3° in epicentral distance, whereas source-side ULVZs produce maximum shifts of SPdKS initiation of ˜5°, allowing clear separation of source- versus receiver-side structure. We present a case study using data from up to 300 broad-band stations in Turkey recorded between 2005 and 2010. We observe a previously undetected ULVZ in the southern Atlantic Ocean region centred near 45°S, 12.5°W, with a lateral scale of ˜3°, VP reduction of 10 per cent, VS reduction of 30 per cent and density increase of 10 per cent relative to PREM.
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.
Effects of waveform model systematics on the interpretation of GW150914
2016-01-01
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 e...
Assessment of waveform control method for mitigation of low-frequency current ripple
Zhu, GR; Wang, HR; Xiao, CY; Kang, Y.; Tan, SC
2013-01-01
Waveform control method can mitigate such a low-frequency ripple current being drawn from the DC distribution while the DC distribution system delivers AC power to the load through a differential inverter. Assessment on the waveform control method and comparative study between with and without waveform control method are proposed in this paper1. Experimental results are provided to explain the operation and showcase the performance between with and without the waveform control method. Results...
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...
Electrical penetration graph (EPG) monitoring has been used extensively to elucidate mechanisms of resistance in plants to insect herbivores with piercing-sucking mouthparts, or stylets. Characterization of waveforms produced by insects during stylet probing is essential to the application of this ...
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
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
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
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
The shaping of a national ignition campaign pulsed waveform
Energy Technology Data Exchange (ETDEWEB)
Brunton, Gordon, E-mail: brunton2@llnl.gov [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Erbert, Gaylen; Browning, Don; Tse, Eddy [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States)
2012-12-15
Highlights: Black-Right-Pointing-Pointer NIF pulse is generated using an electro-optic modulator to vary the intensity of light. Black-Right-Pointing-Pointer Electrical impulse generators, each with a 300 ps pulse Gaussian signal are utilized. Black-Right-Pointing-Pointer Adjusting the impulse amplitude for 140 impulses, produces a pulsed waveform. Black-Right-Pointing-Pointer System auto shapes 48 waveforms with to 275:1 contrast ratio with 3% absolute error. - Abstract: The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is a stadium-sized facility containing a 192 beam, 1.8 MJ, 500 TW ultraviolet laser system used for inertial confinement fusion research. For each experimental shot, NIF must deliver a precise amount of laser power on the target for successful and efficient target ignition, and these characteristics vary depending on the physics of the particular campaign. The precise temporal shape, energy and timing characteristics of a pulsed waveform target interaction are key components in meeting the experimental goals. Each NIF pulse is generated in the Master Oscillator Room (MOR) using an electro-optic modulator to vary the intensity of light in response to an electrical input. The electrical drive signal to the modulator is produced using a unique, high-performance arbitrary waveform generator (AWG). This AWG sums the output of 140 electrical impulse generators, each producing a 300 ps pulse width Gaussian signal separated in time by 250 ps. By adjusting the amplitudes and summing the 140 impulses, a pulsed waveform can be sculpted from a seed 45 ns square pulse. Using software algorithms written for NIF's Integrated Computer Control System (ICCS), the system is capable of autonomously shaping 48 unique experimental pulsed waveforms for each shot that have demonstrated up to 275:1 contrast ratio with {+-}3% absolute error averaged over any 2 ns interval, meeting the stringent pulse requirements needed to achieve ignition
High-frequency chest compression: effect of the third generation compression waveform.
Milla, Carlos E; Hansen, Leland G; Weber, Adam; Warwick, Warren J
2004-01-01
High-frequency chest compression (HFCC) therapy has become the prevailing form of airway clearance for patients with cystic fibrosis (CF) in the United States. The original square waveform was replaced in 1995 with a sine waveform without published evidence of an equality of effectiveness. The recent development of a triangle waveform for HFCC provided the opportunity to compare the functional and therapeutic effects of different waveforms. Clinical testing was done in patients at home with therapy times recorded with all sputum collected in preweighed sealable vials. The eight study patients with CF were regular users of a sine waveform device. They produced sputum consistently and were clinically stable. They used their optimum frequencies for therapy for each waveform and, for one week for each waveform, collected all sputum during their twice-daily timed HFCC therapies. After collection, these vials were reweighed, desiccated, and reweighed to calculate wet and dry weights of sputum per minute of therapy time. Frequency associated vest pressures transmitted to the mouth, and induced airflows at the mouth were measured in healthy volunteers. The pressure waveforms produced in the vest were, in shape, faithfully demonstrable at the mouth. In the healthy subject the transmission occurred in 2 ms and was attenuated to about 75% of the vest pressure for the triangle waveform and 60% for the sine waveform. All patients produced more sputum with the triangle waveform than with the sine waveform. The mean increase was 20%+ range of 4% to 41%. P value was HFCC should investigate the other effects of the sine and triangle waveforms, as well as the neglected square waveform, on mucus clearance and determine the best frequencies for each waveform, disease, and patient.
Effects of output waveforms on penetration for Nd: YAG laser welding
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
By using a Nd: YAG laser welding system devised for transmitting continuous, rectangular and pulsed waveforms, comprehensive and deep investigation is focused on the effects of several parameters of rectangular waveform and pulsed output wave superimposed on a rectangular waveform on the penetration depth of weld. Research results indicate that the average power, duty cycle, frequency and peak power of rectangular wave affect the weld penetration depth to different extent. Results of experiments and analysis also indicate that the pulse delay time, pulse width and the power ratio of pulse to rectangular waveform seriously influence the penetration when the pulsed wave is superimposed on a rectangular waveform.
Signal waveform detection with statistical automaton for internet and web service streaming.
Tseng, Kuo-Kun; Ji, Yuzhu; Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying
2014-01-01
In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.
Signal Waveform Detection with Statistical Automaton for Internet and Web Service Streaming
Directory of Open Access Journals (Sweden)
Kuo-Kun Tseng
2014-01-01
Full Text Available In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.
A method of waveform design based on mutual information
Institute of Scientific and Technical Information of China (English)
Bo JIU; Hongwei LIU; Liya LI; Shunjun WU
2009-01-01
A novel method called the general waterfilling, which is suitable when clutter is not negligible, is proposed to solve the waveform design problem of broadband radar for the recognition of multiple extended targets. The uncertainty of the target's radar signatures is decreased via maximizing the mutual information between a random extended target and the received signal. Then, the general water-filling method is employed to the waveform design problem for multiple extended targets identification to increase the separability of multiple targets. Experimental results evaluated the efficiency of the proposed method. Compared to chirp signal and water-filling signal,our method improves the classification rates and even performs better at low signal-to-interference-plus-noise ratio (SINR).
An electro-optic waveform interconnect based on quantum interference
Qin, Li-Guo; Gong, Shang-Qing
2016-01-01
The ability to modulate an optical field via an electric field is regarded as a key function of electro-optic interconnects, which are used in optical communications and information processing systems. One of the main required devices for such interconnects is the electro-optic modulator (EOM). Current EOM based on the electro-optic effect and the electro-absorption effect often is bulky and power inefficient due to the weak electro-optic properties of its constituent materials. Here we propose a new mechanism to produce an arbitrary-waveform EOM based on the quantum interference, in which both the real and imaginary parts of the susceptibility are engineered coherently with the superhigh efficiency. Based on this EOM, a waveform interconnect from the voltage to the modulated optical absorption is realised. We expect that such a new type of electro-optic interconnect will have a broad range of applications including the optical communications and network.
Software Communication Architecture Implementation and Its Waveform Application
Institute of Scientific and Technical Information of China (English)
SUN Pei-gang; ZHAO Hai; WANG Ting-chang; FAN Jian-hua
2006-01-01
This paper attempts to do a research on the development of software defined radio(SDR) based on software communication architecture(SCA). Firstly, SCA is studied and a whole reference model of SCA3.0 core framework (CF)is realized; Secondly, an application-specific FM3TR waveform is implemented on the platform of common software based on the reference model; Thirdly, from the point of view of real-time performance and software reuse, tests and validations are made on the above realized CF reference model and FM3TR waveform. As a result, the SCA-compliant SDR has favorable interoperability and software portability and can satisfy the real-time performance requirements which are not too rigorous.
TOF Spectroscopy measurement with waveform Digitizer at TMSR Photoneutron Source
Liu, Longxiang; Ma, Yugang; Cao, Xiguang; Cai, Xiangzhou; Chen, Jingen; Zhang, Guilin; Han, Jianlong; Zhang, Guogiang; Hu, Jifeng; Wang, Xiaohe
2015-01-01
The Photo-Neutron Source(PNS,phase 1), is an electron linear accelerator (linac) based pulsed neutron facility, combined with TOF technique, was constructed for nuclear data measurement of Thorium Molten Salt Reactor(TMSR) in Shanghai Institute of Applied Physics(SINAP) at JiaDing campus. The TOF detector signal, with the arrive time, pulse shape and pulse hight information, was recorded by a waveform digitizer. Through the pulse-shape discrimination(PSD) between neutrons and gamma-rays and time of Gamma Flash and Neutron signal analyse, the neutron TOF spectrum was deduced with this simple electronics design, and a new DAQ system based on waveform digitizer was used in this test experiment.
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.
Transient sodium current at subthreshold voltages: activation by EPSP waveforms.
Carter, Brett C; Giessel, Andrew J; Sabatini, Bernardo L; Bean, Bruce P
2012-09-20
Tetrodotoxin (TTX)-sensitive sodium channels carry large transient currents during action potentials and also "persistent" sodium current, a noninactivating TTX-sensitive current present at subthreshold voltages. We examined gating of subthreshold sodium current in dissociated cerebellar Purkinje neurons and hippocampal CA1 neurons, studied at 37°C with near-physiological ionic conditions. Unexpectedly, in both cell types small voltage steps at subthreshold voltages activated a substantial component of transient sodium current as well as persistent current. Subthreshold EPSP-like waveforms also activated a large component of transient sodium current, but IPSP-like waveforms engaged primarily persistent sodium current with only a small additional transient component. Activation of transient as well as persistent sodium current at subthreshold voltages produces amplification of EPSPs that is sensitive to the rate of depolarization and can help account for the dependence of spike threshold on depolarization rate, as previously observed in vivo.
A versatile waveform generator for testing neuroelectric signal processors.
Kohn, A F
1989-08-01
A multi-channel waveform generator was designed for testing neuroelectric signal processors. Smooth transient signals that resemble action potentials or evoked potentials are generated by a second order switched capacitor filter excited by brief rectangular pulses. The choice of an integrated circuit switched capacitor filter simplified the design by circumventing some of the disadvantages of conventional active filters. The waveform generator is versatile, with several signal parameters being independently adjustable from front panel controls: duration, waveshape, latency, amplitude and signal-to-noise ratio. The generator has been used for testing evoked potential acquisition and processing systems, for evaluating the effects of analog filters on evoked potentials and for testing systems designed to detect and classify trains of multi-unit action potentials.
Leveraging waveform complexity for confident detection of gravitational waves
Kanner, Jonah B; Cornish, Neil; Millhouse, Meg; Xhakaj, Enia; Salemi, Francesco; Drago, Marco; Vedovato, Gabriele; Klimenko, Sergey
2016-01-01
The recent completion of Advanced LIGO suggests that gravitational waves (GWs) may soon be directly observed. Past searches for gravitational-wave transients have been impacted by transient noise artifacts, known as glitches, introduced into LIGO data due to instrumental and environmental effects. In this work, we explore how waveform complexity, instead of signal-to-noise ratio, can be used to rank event candidates and distinguish short duration astrophysical signals from glitches. We test this framework using a new hierarchical pipeline that directly compares the Bayesian evidence of explicit signal and glitch models. The hierarchical pipeline is shown to have strong performance, and in particular, allows high-confidence detections of a range of waveforms at realistic signal-to-noise ratio with a two detector network.
Waveform effects of a metastable olivine tongue in subducting slabs
Vidale, John E.; Williams, Quentin; Houston, Heidi
1991-01-01
Velocity models of subducting slabs with a kinetically-depressed olivine to beta- and gamma-spinel transition are constructed, and the effect that such structures would have on teleseismic P waveforms are examined using a full-wave finite-difference method. These 2D calculations yielded waveforms at a range of distances in the downdip direction. The slab models included a wedge-shaped, low-velocity metastable olivine tongue (MOTO) to a depth of 670 km, as well as a plausible thermal anomaly; one model further included a 10-km-thick fast layer on the surface of the slab. The principal effect of MOTO is to produce grazing reflections at wide angles off the phase boundary, generating a secondary arrival 0 to 4 seconds after the initial arrival depending on the take-off angle. The amplitude and timing of this feature vary with the lateral location of the seismic source within the slab cross-section.
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.
Waveform relaxation for the computational homogenization of multiscale magnetoquasistatic problems
Niyonzima, I.; Geuzaine, C.; Schöps, S.
2016-12-01
This paper proposes the application of the waveform relaxation method to the homogenization of multiscale magnetoquasistatic problems. In the monolithic heterogeneous multiscale method, the nonlinear macroscale problem is solved using the Newton-Raphson scheme. The resolution of many mesoscale problems per Gauß point allows to compute the homogenized constitutive law and its derivative by finite differences. In the proposed approach, the macroscale problem and the mesoscale problems are weakly coupled and solved separately using the finite element method on time intervals for several waveform relaxation iterations. The exchange of information between both problems is still carried out using the heterogeneous multiscale method. However, the partial derivatives can now be evaluated exactly by solving only one mesoscale problem per Gauß point.
Analytic gravitational waveforms for generic precessing compact binaries
Chatziioannou, Katerina; Cornish, Neil; Yunes, Nicolas
2016-01-01
Binary systems of two compact objects circularize and spiral toward each other via the emission of gravitational waves. The coupling of the spins of each object with the orbital angular momentum causes the orbital plane to precess, which leads to modulation of the gravitational wave signal. Until now, generating frequency-domain waveforms for fully precessing systems for use in gravitational wave data analysis meant numerically integrating the equations of motion, then Fourier transforming the result, which is very computationally intensive for systems that complete hundreds or thousands of cycles in the sensitive band of a detector. Previously, analytic solutions were only available for certain special cases or for simplified models. Here we describe the construction of closed-form, frequency-domain waveforms for fully-precessing, quasi-circular binary inspirals.
Optimal control of photoelectron emission by realistic waveforms
Solanpää, Janne; Räsänen, Esa
2016-01-01
Recent experimental techniques in multicolor waveform synthesis allow the temporal shaping of strong femtosecond laser pulses with applications in the control of quantum mechanical processes in atoms, molecules, and nanostructures. Prediction of the shapes of the optimal waveforms can be done computationally using quantum optimal control theory (QOCT). In this work we bring QOCT to experimental feasibility by providing an optimal control scheme with realistic pulse representation. We apply the technique to optimal control of above-threshold photoelectron emission from a one-dimensional hydrogen atom. By mixing different spectral channels and thus lowering the intensity requirements for individual channels, the resulting optimal pulses can extend the cutoff energies by at least up to 50% and bring up the electron yield by several orders of magnitude. Insights into the electron dynamics for optimized photoelectron emission are obtained with a semiclassical two-step model.
Leveraging waveform complexity for confident detection of gravitational waves
Kanner, Jonah B.; Littenberg, Tyson B.; Cornish, Neil; Millhouse, Meg; Xhakaj, Enia; Salemi, Francesco; Drago, Marco; Vedovato, Gabriele; Klimenko, Sergey
2016-01-01
The recent completion of Advanced LIGO suggests that gravitational waves may soon be directly observed. Past searches for gravitational-wave transients have been impacted by transient noise artifacts, known as glitches, introduced into LIGO data due to instrumental and environmental effects. In this work, we explore how waveform complexity, instead of signal-to-noise ratio, can be used to rank event candidates and distinguish short duration astrophysical signals from glitches. We test this framework using a new hierarchical pipeline that directly compares the Bayesian evidence of explicit signal and glitch models. The hierarchical pipeline is shown to perform well and, in particular, to allow high-confidence detections of a range of waveforms at a realistic signal-to-noise ratio with a two-detector network.
Waveform effects of a metastable olivine tongue in subducting slabs
Vidale, John E.; Williams, Quentin; Houston, Heidi
1991-01-01
Velocity models of subducting slabs with a kinetically-depressed olivine to beta- and gamma-spinel transition are constructed, and the effect that such structures would have on teleseismic P waveforms are examined using a full-wave finite-difference method. These 2D calculations yielded waveforms at a range of distances in the downdip direction. The slab models included a wedge-shaped, low-velocity metastable olivine tongue (MOTO) to a depth of 670 km, as well as a plausible thermal anomaly; one model further included a 10-km-thick fast layer on the surface of the slab. The principal effect of MOTO is to produce grazing reflections at wide angles off the phase boundary, generating a secondary arrival 0 to 4 seconds after the initial arrival depending on the take-off angle. The amplitude and timing of this feature vary with the lateral location of the seismic source within the slab cross-section.
Analysis of Chaotic Waveforms for Application to Active Sonar Systems
1993-06-01
Noise-Reduced Signal. Figure 4-2. Noise Reduction Power Spectra : (a) Power Spectrum of Lorenz Waveform; (b) Gaussian Noise; (c) Signal Plus Noise; and (d...dimension, theoretic entropy and Lyapunov exponent, are also described for completeness even though they are not used in this study. 2.5.1 Correlation...For each lical center, a data covariance matrix is formed using the nearest neighbors. Singular value decomposition ( SVD ) is then applied to the matrix
MURI: Adaptive Waveform Design for Full Spectral Dominance
2011-03-11
response of a uniform linear array 3 ( ULA ) with BIC. We derived the maximum likelihood estimates (MLEs) of the DOAs and computed the Cramér-Rao bound (CRB...Elnour, 2006-2007 IEEE Antennas and Propagation Society Graduate Fellowship award. (Advisor: Danilo Erricolo) • Murat Akcakaya, Best Student Paper...Award (first place) at the 2010 Waveform Diversity & Design Conference. (Co-author: Arye Nehorai) • Murat Akcakaya, co-author, Best Student Paper
Optimal storage and retrieval of single-photon waveforms.
Zhou, Shuyu; Zhang, Shanchao; Liu, Chang; Chen, J F; Wen, Jianming; Loy, M M T; Wong, G K L; Du, Shengwang
2012-10-22
We report an experimental demonstration of optimal storage and retrieval of heralded single-photon wave packets using electromagnetically induced transparency (EIT) in cold atoms at a high optical depth. We obtain an optimal storage efficiency of (49 ± 3)% for single-photon waveforms with a temporal likeness of 96%. Our result brings the EIT quantum light-matter interface closer to practical quantum information applications.
PMT waveform modeling at the Daya Bay experiment
Institute of Scientific and Technical Information of China (English)
S(o)ren JETTER; Dan DWYER; JIANG Wen-Qi; LIU Da-Wei; WANG Yi-Fang; WANG Zhi-Min; WEN Liang-Jian
2012-01-01
Detailed measurements of Hamamatsu R5912 photomultiplier signals are presented,including the single photoelectron charge response,waveform shape,nonlinearity,saturation,overshoot,oscillation,prepulsing,and afterpulsing.The results were used to build a detailed model of the PMT signal characteristics over a wide range of light intensities.Including the PMT model in simulated Daya Bay particle interactions shows no significant systematic effects that are detrimental to the experimental sensitivity.
Comparison of three arterial pulse waveform classification techniques.
Allen, J; Murray, A
1996-01-01
Peripheral pulse waveforms can become stretched and damped with increasing severity of peripheral vascular disease (PVD) and hence could provide valuable diagnostic information. This study compares the diagnostic performance of 3 established classification techniques (a linear discriminant classifier, a k-nearest neighbour classifier, and an artificial neural network) for the detection of lower limb arterial disease from pulse waveforms obtained using photoelectric plethysmography (PPG). Pulse waveforms and pre- and post-exercise Doppler ultrasound ankle to brachial pressure indices (ABPI) were obtained from patients attending a vascular measurement laboratory. A single PPG pulse from each big toe was recorded direct to computer, pre-processed, and then used as classifier input data. The correct classifier outputs were the corresponding ABPI diagnostic classification. Pulse and ABPI measurements from 100 legs were used as training data for each classifier, and the computed classifications for pulses from a further 266 legs were then compared with their ABPI diagnoses. The diagnostic accuracy of the artificial neural network (80%; was higher than for the optimized k-nearest neighbour classifier (k = 27, accuracy 76% and the linear discriminant classifier (71%). The Kappa measure of agreement which excludes chance was highest for the artificial neural network (57%) and significantly higher than that of the linear discriminant classifier (Kappa 40%, p < 0.05). The value of Kappa for the optimized k-nearest neighbour classifier (k = 27) was intermediate at 47%. This study has shown that classifiers can be taught to discriminate between small, and perhaps subtle, differences in features. We have demonstrated that artificial neural networks can be used to classify arterial pulse waveforms, and can perform better overall than k-nearest neighbour or linear discriminant classifiers for this application.
Arbitrary waveform generator to improve laser diode driver performance
Fulkerson, Jr, Edward Steven
2015-11-03
An arbitrary waveform generator modifies the input signal to a laser diode driver circuit in order to reduce the overshoot/undershoot and provide a "flat-top" signal to the laser diode driver circuit. The input signal is modified based on the original received signal and the feedback from the laser diode by measuring the actual current flowing in the laser diode after the original signal is applied to the laser diode.
Individual Flagellar Waveform Affects Collective Behavior of Chlamydomonas reinhardtii.
Kage, Azusa; Mogami, Yoshihiro
2015-08-01
Bioconvection is a form of collective motion that occurs spontaneously in the suspension of swimming microorganisms. In a previous study, we quantitatively described the "pattern transition," a phase transition phenomenon that so far has exclusively been observed in bioconvection of the unicellular green alga Chlamydomonas. We suggested that the transition could be induced by changes in the balance between the gravitational and shear-induced torques, both of which act to determine the orientation of the organism in the shear flow. As both of the torques should be affected by the geometry of the Chlamydomonas cell, alteration in the flagellar waveform might change the extent of torque generation by altering overall geometry of the cell. Based on this working hypothesis, we examined bioconvection behavior of two flagellar mutants of Chlamydomonas reinhardtii, ida1 and oda2, making reference to the wild type. Flagella of ida1 beat with an abnormal waveform, while flagella of oda2 show a normal waveform but lower beat frequency. As a result, both mutants had swimming speed of less than 50% of the wild type. ida1 formed bioconvection patterns with smaller spacing than those of wild type and oda2. Two-axis view revealed the periodic movement of the settling blobs of ida1, while oda2 showed qualitatively similar behavior to that of wild type. Unexpectedly, ida1 showed stronger negative gravitaxis than did wild type, while oda2 showed relatively weak gravitaxis. These findings suggest that flagellar waveform, not swimming speed or beat frequency, strongly affect bioconvection behavior in C. reinhardtii.
Acquisition of L2 Japanese Geminates: Training with Waveform Displays
Motohashi-Saigo, Miki; Hardison, Debra M.
2009-01-01
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…
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
Photonic Synthesis and Processing of Ultrabroadband Radio-Frequency Waveforms
2009-11-17
Filed in Foreign Countries? (5d-2) Was the assignment forwarded to the contracting officer? (5e) N Foreign Countries of application ( 5g -2): 5 Jason D...techniques given the fixed electronic pulse shaping networks used to generated monocycle waveforms. Finally, the delay between adjacent monocycles is tunable...Dispersion Compensation In moving our RF-AWG technique and apparatus towards applications in wireless RF systems, we have begun to investigate
Advanced waveform decomposition for high-speed videoendoscopy analysis.
Ikuma, Takeshi; Kunduk, Melda; McWhorter, Andrew J
2013-05-01
This article presents a novel approach to analyze nonperiodic vocal fold behavior of high-speed videoendoscopy (HSV) data. Although HSV can capture true vibrational motions of the vocal folds, its clinical advantage over the videostroboscopy has not widely been accepted. One of the key advantages of the HSV over the videostroboscopy is its ability to capture vocal folds' nonperiodic behavior, which is more prominent in pathological vocal folds. However, such nonperiodicity in the HSV data has not been fully explored quantitatively beyond simple perturbation analysis. This article presents an advanced waveform modeling and decomposition technique for HSV-based waveforms. Waveforms are modeled to have three components: harmonic signal, deterministic nonharmonic signal, and random nonharmonic signal. This decomposition is motivated by the fact that voice disorders introduce signal content that is nonharmonic but carries deterministic quality such as subharmonic or modulating content. The proposed model is aimed to isolate such disordered behaviors as deterministic nonharmonic signal and quantify them. In addition to the model, the article outlines model parameter estimation procedures and a family of harmonics-to-noise ratio (HNR) parameters. The proposed HNR parameters include harmonics-to-deterministic-noise ratio (HDNR) and harmonics-to-random-noise ratio. A preliminary study demonstrates the effectiveness of the extended model and its HNR parameters. Vocal folds with and without benign lesions (Nwith = 13; Nwithout = 20) were studied with HSV glottal area waveforms. All three HNR parameters significantly distinguished the disordered condition, and the HDNR reported the largest effect size (Cohen's d = 2.04).
A Convergent Iterative Algorithm for Solving Elastic Waveform Inversion
Institute of Scientific and Technical Information of China (English)
张剑锋
1994-01-01
The numerical method for elastic waveform inversion is studied and a convergent iterative algorithm is achieved by designing vinual source and altering objective function of the optimization solution in the computational process, which enables the solutions to converge to the real values and improves the convergence rate by changing the property of curved surface of the objective function, thus opening a new way for further developing the optimization solution of inverse problems.
Strategies for efficient resolution analysis in full-waveform inversion
Fichtner, A.; van Leeuwen, T.; Trampert, J.
2016-12-01
Full-waveform inversion is developing into a standard method in the seismological toolbox. It combines numerical wave propagation for heterogeneous media with adjoint techniques in order to improve tomographic resolution. However, resolution becomes increasingly difficult to quantify because of the enormous computational requirements. Here we present two families of methods that can be used for efficient resolution analysis in full-waveform inversion. They are based on the targeted extraction of resolution proxies from the Hessian matrix, which is too large to store and to compute explicitly. Fourier methods rest on the application of the Hessian to Earth models with harmonic oscillations. This yields the Fourier spectrum of the Hessian for few selected wave numbers, from which we can extract properties of the tomographic point-spread function for any point in space. Random probing methods use uncorrelated, random test models instead of harmonic oscillations. Auto-correlating the Hessian-model applications for sufficiently many test models also characterises the point-spread function. Both Fourier and random probing methods provide a rich collection of resolution proxies. These include position- and direction-dependent resolution lengths, and the volume of point-spread functions as indicator of amplitude recovery and inter-parameter trade-offs. The computational requirements of these methods are equivalent to approximately 7 conjugate-gradient iterations in full-waveform inversion. This is significantly less than the optimisation itself, which may require tens to hundreds of iterations to reach convergence. In addition to the theoretical foundations of the Fourier and random probing methods, we show various illustrative examples from real-data full-waveform inversion for crustal and mantle structure.
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.
"Kludge" gravitational waveforms for a test-body orbiting a Kerr black hole
Babak, S; Gair, J R; Glampedakis, K; Hughes, S A; Babak, Stanislav; Fang, Hua; Gair, Jonathan R.; Glampedakis, Kostas; Hughes, Scott A.
2006-01-01
One of the most exciting potential sources of gravitational waves for low-frequency, space-based gravitational wave (GW) detectors such as the proposed Laser Interferometer Space Antenna (LISA) is the inspiral of compact objects into massive black holes in the centers of galaxies. The detection of waves from such "extreme mass ratio inspiral" systems (EMRIs) and extraction of information from those waves require template waveforms. The systems' extreme mass ratio means that their waveforms can be determined accurately using black hole perturbation theory. Such calculations are computationally very expensive. There is a pressing need for families of approximate waveforms that may be generated cheaply and quickly but which still capture the main features of true waveforms. In this paper, we introduce a family of such "kludge" waveforms and describe ways to generate them. We assess performance of the introduced approximations by comparing "kludge" waveforms to accurate waveforms obtained by solving the Teukolsky...
Reconstructing core-collapse supernovae waveforms with advanced era interferometers
McIver, Jessica; LIGO Scientific Collaboration
2015-04-01
Among of the wide range of potentially interesting astrophysical sources for Advanced LIGO and Advanced Virgo are galactic core-collapse supernovae. Although detectable core-collapse supernovae have a low expected rate (a few per century, or less) these signals would yield a wealth of new physics in the form of many messengers. Of particular interest is the insight into the explosion mechanism driving core-collapse supernovae that can be gleaned from the reconstructed gravitational wave signal. A well-reconstructed waveform will allow us to assess the likelihood of different explosion models, perform model selection, and potentially map unexpected features to new physics. This talk will present a study evaluating the current performance of the reconstruction of core-collapse supernovae gravitational wave signals. We used simulated waveforms modeled after different explosion mechanisms that we first injected into fake strain data re-colored to the expected Advanced LIGO/Virgo noise curves and then reconstructed using the pipelines Coherent Waveburst 2G and BayesWave. We will discuss the impact of these results on our ability to accurately reconstruct core-collapse supernovae signals, and by extension, other potential astrophysical generators of rich, complex waveforms.
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.
Characterizing Canopy Structure Using Waveform LiDAR
Wang, K.; Kumar, P.
2016-12-01
The structure of light penetration through the canopy plays an important role in water, carbon, and energy fluxes between the biosphere and the atmosphere. Canopy clumping, a description of foliage distribution, is one of the major aspects of canopy structure that significantly influence light and vegetation interaction. Airborne full-waveform LiDAR data contains large amounts of vegetation structural information, and is a powerful tool for providing detailed foliage distribution information for large areas of vegetation. In this study, we present a method for describing physical canopy clumping structure for individual trees that can resolve fine scale variations in foliage distribution. We first utilize the K-means clustering algorithm to extract structure from the large amounts of vegetation data provided by full-waveform LiDAR. Then we find representative traits for data clusters and use them to classify the clusters into three groups. Based on these traits, we draw conclusions about physical representations of each group, and identify two groups to contain structurally significant clusters. This study demonstrates that large amounts of canopy structural information can be extracted from waveform LiDAR data. The fine resolution canopy clumping structure found by the method described in this work can be used as valuable input for ecological models.
Excitation Waveform Design for Lamb Wave Pulse Compression.
Lin, Jing; Hua, Jiadong; Zeng, Liang; Luo, Zhi
2016-01-01
Most ultrasonic guided wave methods focus on tone burst excitation to reduce the effect of dispersion so as to facilitate signal interpretation. However, the resolution of the output cannot attain a very high value because time duration of the excitation waveform cannot be very small. To overcome this limitation, a pulse compression technique is introduced to Lamb wave propagation to achieve a δ-like correlation so as to obtain a high resolution for inspection. Ideal δ-like correlation is impossible as only a finite frequency bandwidth can propagate. The primary purpose of this paper is to design a proper excitation waveform for Lamb wave pulse compression, which shortens the correlation as close as possible to a δ function. To achieve this purpose, the performance of some typical signals is discussed in pulse compression, which include linear chirp (L-Chirp) signal, nonlinear chirp (NL-Chirp) signal, Barker code (BC), and Golay complementary code (GCC). In addition, how the excitation frequency range influences inspection resolution is investigated. A strategy for the frequency range determination is established subsequently. Finally, an experiment is carried out on an aluminum plate where these typical signals are used as excitations at different frequency ranges. The quantitative comparisons of the pulse compression responses validate the theoretical findings. By utilizing the experimental data, the improvement of pulse compression in resolution compared with tone burst excitation is also validated, and the robustness of the waveform design method to inaccuracies in the dispersion compensation is discussed as well.
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.
EPOS-S: Integrated access to seismological waveforms
Sleeman, Reinoud; Strollo, Angelo; Michelini, Alberto; Clinton, John; Gueguen, Philippe; Luzi, Lucia; Pinar, Ali; Diaz, Jordi; Ceken, Ulubey; Evangelidis, Christos; Haslinger, Florian
2016-04-01
The main challenges of the EPOS TCS Seismology are to improve and to extend existing services to access earthquake waveforms (ORFEUS), parameters (EMSC) and hazard data and products (EFEHR), and producing a single framework that is technically integrated within the EPOS architecture. Technical developments in the services for seismological waveforms and associated data, including the compilation of station metadata and installing common data archival and sharing policies are within ORFEUS and its Working Groups. The focus is on 1) the development of the next generation software architecture for the European Integrated (seismological) Data Archive EIDA based on standardized webservices, the implementation of a data quality service and the realisation of a mediator service; 2) the development of EIDA-compliant services for strong motion data and acceleration data and the extension of the station metadata model; 3) the integration of data from mobile networks and OBS waveforms into EIDA by implementing mechanisms for coordination of transnational access and multinational experiments at available pools of OBS and mobile seismic stations; 4) achieve close integration with other EPOS TCS and the ICS with regard to interoperability and common use of tools & services, common and coordinated data models and metadata formats, and common computational platforms and IT solution implementations. This presentation will present the status of and current developments towards the above objectives.
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.
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.
Institute of Scientific and Technical Information of China (English)
Lü Xiaoqing; Cao Biao; Zeng Min; Huang Zenghao
2005-01-01
Aim at improving the stability of the Short-circuiting Gas Metal Arc Welding ( GMA W-S) process for the enhanced speed usage, effects of current waveform parameters during short-term on the welding stability have been investigated by experimental method. The welding power source used for the research is an inverter with a special current waveform control. It is shown that the spatter decreases at first then increases with each increase of the low current period, current increase rate and the maximum current limit. The test results are provided for welding of 1 mm and 3 mm mild steel at speed of 1.2 m/min. The stable GMA W-S process under high speed welding condition has been achieved by optimizing the parameters.
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
Sums of Spike Waveform Features for Motor Decoding
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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
Velocity Structure Determination Through Seismic Waveform Modeling and Time Deviations
Savage, B.; Zhu, L.; Tan, Y.; Helmberger, D. V.
2001-12-01
Through the use of seismic waveforms recorded by TriNet, a dataset of earthquake focal mechanisms and deviations (time shifts) relative to a standard model facilitates the investigation of the crust and uppermost mantle of southern California. The CAP method of focal mechanism determination, in use by TriNet on a routine basis, provides time shifts for surface waves and Pnl arrivals independently relative to the reference model. These shifts serve as initial data for calibration of local and regional seismic paths. Time shifts from the CAP method are derived by splitting the Pnl section of the waveform, the first arriving Pn to just before the arrival of the S wave, from the much slower surface waves then cross-correlating the data with synthetic waveforms computed from a standard model. Surface waves interact with the entire crust, but the upper crust causes the greatest effect. Whereas, Pnl arrivals sample the deeper crust, upper mantle, and source region. This natural division separates the upper from lower crust for regional calibration and structural modeling and allows 3-D velocity maps to be created using the resulting time shifts. Further examination of Pnl and other arrivals which interact with the Moho illuminate the complex nature of this boundary. Initial attempts at using the first 10 seconds of the Pnl section to determine upper most mantle structure have proven insightful. Two large earthquakes north of southern California in Nevada and Mammoth Lakes, CA allow the creation of record sections from 200 to 600 km. As the paths swing from east to west across southern California, simple 1-D models turn into complex structure, dramatically changing the waveform character. Using finite difference models to explain the structure, we determine that a low velocity zone is present at the base of the crust and extends to 100 km in depth. Velocity variations of 5 percent of the mantle in combination with steeply sloping edges produces complex waveform variations
Accuracy Assessment for Multi-Channel ECG Waveforms Using Soft Computing Methodologies
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Menta Srinivasulu
2014-07-01
Full Text Available ECG waveform rhythmic analysis is very important. In recent trends, analysis processes of ECG waveform applications are available in smart devices. Still, existing methods are not able to accomplish the complete accuracy assessment while classify the multi-channel ECG waveforms. In this paper, proposed analysis of accuracy assessment of the classification of multi-channel ECG waveforms using most popular Soft Computing algorithms. In this research, main focus is on the better rule generation to analyze the multi-channel ECG waveforms. Analysis is mainly done inSoft Computing methods like the Decision Trees with different pruning analysis, Logistic Model Trees with different regression process and Support Vector Machine with Particle Swarm Optimization (SVM-PSO. All these analysis methods are trained and tested with MIT-BIH 12 channel ECG waveforms. Before trained these methods, MSO-FIR filter should be used as data preprocessing for removal of noise from original multi-channel ECG waveforms. MSO technique is used for automatically finding out the cutoff frequency of multichannel ECG waveforms which is used in low-pass filtering process. The classification performance is discussed using mean squared error, member function, classification accuracy, complexity of design, and area under curve on MIT-BIH data. Additionally, this research work is extended for the samples of multi-channel ECG waveforms from the Scope diagnostic center, Hyderabad. Our study assets the best process using the Soft Computing methods for analysis of multi-channel ECG waveforms.
Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms
Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng
2013-04-01
Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.
Full-waveform data for building roof step edge localization
Słota, Małgorzata
2015-08-01
Airborne laser scanning data perfectly represent flat or gently sloped areas; to date, however, accurate breakline detection is the main drawback of this technique. This issue becomes particularly important in the case of modeling buildings, where accuracy higher than the footprint size is often required. This article covers several issues related to full-waveform data registered on building step edges. First, the full-waveform data simulator was developed and presented in this paper. Second, this article provides a full description of the changes in echo amplitude, echo width and returned power caused by the presence of edges within the laser footprint. Additionally, two important properties of step edge echoes, peak shift and echo asymmetry, were noted and described. It was shown that these properties lead to incorrect echo positioning along the laser center line and can significantly reduce the edge points' accuracy. For these reasons and because all points are aligned with the center of the beam, regardless of the actual target position within the beam footprint, we can state that step edge points require geometric corrections. This article presents a novel algorithm for the refinement of step edge points. The main distinguishing advantage of the developed algorithm is the fact that none of the additional data, such as emitted signal parameters, beam divergence, approximate edge geometry or scanning settings, are required. The proposed algorithm works only on georeferenced profiles of reflected laser energy. Another major advantage is the simplicity of the calculation, allowing for very efficient data processing. Additionally, the developed method of point correction allows for the accurate determination of points lying on edges and edge point densification. For this reason, fully automatic localization of building roof step edges based on LiDAR full-waveform data with higher accuracy than the size of the lidar footprint is feasible.
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
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.
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.
Magnetic Field Gradient Waveform Monitoring for Magnetic Resonance
Han, Hui
Linear magnetic field gradients have played a central role in Magnetic Resonance Imaging (MRI) since Fourier Transform MRI was proposed three decades ago. Their primary function is to encode spatial information into MR signals. Magnetic field gradients are also used to sensitize the image contrast to coherent and/or incoherent motion, to selectively enhance an MR signal, and to minimize image artifacts. Modern MR imaging techniques increasingly rely on the implementation of complex gradient waveforms for the manipulation of spin dynamics. However, gradient system infidelities caused by eddy currents, gradient amplifier imperfections and group delays, often result in image artifacts and other errors (e.g., phase and intensity errors). This remains a critical problem for a wide range of MRI techniques on modern commercial systems, but is of particular concern for advanced MRI pulse sequences. Measuring the real magnetic field gradients, i.e., characterizing eddy currents, is critical to addressing and remedying this problem. Gradient measurement and eddy current calibration are therefore a general topic of importance to the science of MRI. The Magnetic Field Gradient Monitor (MFGM) idea was proposed and developed specifically to meet these challenges. The MFGM method is the heart of this thesis. MFGM methods permit a variety of magnetic field gradient problems to be investigated and systematically remedied. Eddy current effects associated with MR compatible metallic pressure vessels were analyzed, simulated, measured and corrected. The appropriate correction of eddy currents may enable most MR/MRI applications with metallic pressure vessels. Quantitative imaging (1D/2D) with model pressure vessels was successfully achieved by combining image reconstruction with MFGM determined gradient waveform behaviour. Other categories of MR applications with metallic vessels, including diffusion measurement and spin echo SPI T2 mapping, cannot be realized solely by MFGM guided
A complete waveform model for compact binaries on eccentric orbits
Huerta, Eliu; Agarwal, Bhanu; George, Daniel; Kumar, Prayush
2016-03-01
The detection of compact binaries with significant eccentricity in the sensitivity band of gravitational wave detectors will provide critical insights on the dynamics and formation channels of these events. In order to search for these systems and place constraints on their rates, we present an inspiral-merger-ringdown time domain waveform model that describes the GW emission from compact binaries on orbits with low to moderate values of eccentricity. We use this model to explore the detectability of these events in the context of advanced LIGO.
The Lazarus project: Plunge waveforms from inspiralling black holes
Baker, J.; Brügmann, B.; Campanelli, M.; Lousto, C.; Takahashi, R.
2001-10-01
We study the coalescence of binary black holes from the innermost stable circular orbit down to the final single rotating black hole. We use a technique that combines the full numerical approach to solve Einstein equations, applied in the truly nonlinear regime, and linearized perturbation theory around the final distorted single black hole at later times. We thus produce an estimate for the plunge radiation with a non negligible signal lasting for over t~100M, and we obtain estimates of the total gravitational radiated energy and angular momentum during this process, plunging time, and waveforms. .
Test definitions for the evaluation of digital waveform recorders.
Energy Technology Data Exchange (ETDEWEB)
Kromer, Richard Paul (R.P. Kromer Consulting, Albuquerque, NM); Hart, Darren M.; Harris, James Mark
2007-07-01
This Test Definition for the Evaluation of Digitizing Waveform Recorders (DWR) defines the process that can be performed as part of the evaluation and testing of geophysical sensors, digitizers, sensor subsystems and geophysical station/array systems. The objectives are to (1) evaluate the overall technical performance of the DWR, measure the distortions introduced by the high resolution digitizers and provide a performance check of the internal calibrator if provided and (2) evaluate the technical performance of the DWR for a specific sensor application. The results of these evaluations can be compared to the manufacturer's specifications and any relevant application requirements or specifications.
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...
Maximally Flat Waveforms with Finite Number of Harmonics in Class-F Power Amplifiers
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Anamarija Juhas
2013-01-01
Full Text Available In this paper general solution to the problem of finding maximally flat waveforms with finite number of harmonics (maximally flat trigonometric polynomials is provided. Waveform coefficients are expressed in closed form as functions of harmonic orders. Two special cases of maximally flat waveforms (so-called maximally flat even harmonic and maximally flat odd harmonic waveforms, which proved to play an important role in class-F and inverse class-F power amplifier (PA operations, are also considered. For these two special types of waveforms, coefficients are expressed as functions of two parameters only. Closed form expressions for efficiency and power output capability of class-F and inverse class-F PA operations with maximally flat waveforms are also provided as explicit functions of number of a harmonics.
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 ...
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.
Application of Waveform Factors in Extracting Fault Trend of Rotary Machines
Institute of Scientific and Technical Information of China (English)
YE Yu-gang; ZUO Yun-bo; HUANG Xiao-bin
2009-01-01
Vibration intensity and non-dimensional amplitude parameters are often used to extract the fault trend of rotary machines. But, they are the parameters related to energy, and can not describe the fault trend because of varying load and conditions or too slight change of vibration signal. For this reason, three non-dimensional parameters are presented, namely waveform repeatability factor, waveform jumping factor and waveform similarity factor, called as waveform factors jointly, which are based on statistics analysis for the waveform and sensitive to the change of signal waveform. When they are used to extract the fault trend of rotary machines as a kind of technology of instrument and meter, they can reflect the fault trend better than the vibration intensity, peak amplitude and margin index.
Arbitrary waveform generator and differentiator employing an integrated optical pulse shaper.
Liao, Shasha; Ding, Yunhong; Dong, Jianji; Yang, Ting; Chen, Xiaolin; Gao, Dingshan; Zhang, Xinliang
2015-05-04
We propose and demonstrate an optical arbitrary waveform generator and high-order photonic differentiator based on a four-tap finite impulse response (FIR) silicon-on-insulator (SOI) on-chip circuit. Based on amplitude and phase modulation of each tap controlled by thermal heaters, we obtain several typical waveforms such as triangular waveform, sawtooth waveform, square waveform and Gaussian waveform, etc., assisted by an optical frequency comb injection. Unlike other proposed schemes, our scheme does not require a spectral disperser which is difficult to fabricate on chip with high resolution. In addition, we demonstrate first-, second- and third-order differentiators based on the optical pulse shaper. Our scheme can switch the differentiator patterns from first- to third-order freely. In addition, our scheme has distinct advantages of compactness, capability for integration with electronics.
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.
All-Optical Temporal Differentiator Using a High Resolution Optical Arbitrary Waveform Shaper
Institute of Scientific and Technical Information of China (English)
DONG Jian-Ji; LUO Bo-Wen; ZHANG Yin; LEI Lei; HUANG De-Xiu; ZHANG Xin-Liang
2012-01-01
We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper, which is based on liquid crystal on silicon switching elements, and both amplitude and phase of the spectrum are programmable. By designing specific transfer functions with the optical waveform shaper, we obtain first-, second-, and third-order differentiators for periodic pulses with small average errors. We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.%We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper,which is based on liquid crystal on silicon switching elements,and both amplitude and phase of the spectrum are programmable.By designing specific transfer functions with the optical waveform shaper,we obtain first-,second-,and third-order differentiators for periodic pulses with small average errors.We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.
Channel Influence Mitigation in Pseudo-noise Waveform Design for Radar Applications
Directory of Open Access Journals (Sweden)
J. S. Kulpa
2014-04-01
Full Text Available Noise Radar is a rapidly developing technology which uses noise or pseudo-noise waveforms as sounding signals to de- tect targets of interest. The advantages of such waveforms are no range nor velocity ambiguities, the possibility of using continuous waveform and low probability of intercept. However, the noise waveform correlation sidelobes are spread across the entire range–Doppler plane and their level is de- termined by the time-bandwidth product. Such sidelobes limit the detection capability in the multitarget environment. Several algorithms exist that decrease the sidelobe level and thus enhance dynamic range of the radar, but they are very susceptible to distortions in an analogue channel. In this paper the author presents a method to create low-sidelobe waveforms using a filtering algorithm designed for given channel, decreasing the analogue front-end impact on the final properties of the waveforms.
Effects of Forest Disturbances on Forest Structural Parameters Retrieval from Lidar Waveform Data
Ranson, K, Lon; Sun, G.
2011-01-01
The effect of forest disturbance on the lidar waveform and the forest biomass estimation was demonstrated by model simulation. The results show that the correlation between stand biomass and the lidar waveform indices changes when the stand spatial structure changes due to disturbances rather than the natural succession. This has to be considered in developing algorithms for regional or global mapping of biomass from lidar waveform data.
FULL WAVEFORM LIDAR EXPLOITATION TECHNIQUE AND ITS EVALUATION IN THE MIXED FOREST HILLY REGION
Chhatkuli, S.; Mano, K; Kogure, T.; Tachibana, K.; H. Shimamura
2012-01-01
In this paper a full waveform exploitation technique and its evaluation in the mixed forest hilly region is presented. The increment in ground penetration by using the full waveform exploitation technique compared to the discrete LiDAR pulses during autumn and winter season is evaluated. The results showed that the technique used for the full waveform exploitation has effectively increased the ground penetration by 50 % and 20 %, respectively, during autumn and winter in the mixed fo...
Hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver
Energy Technology Data Exchange (ETDEWEB)
Oguzkurt, Levent [Department of Radiology, Adana Teaching and Medical Research Center, Baskent University, Adana 01250 (Turkey)]. E-mail: loguzkurt@yahoo.com; Yildirim, Tulin [Department of Radiology, Adana Teaching and Medical Research Center, Baskent University, Adana 01250 (Turkey); Torun, Dilek [Department of Nephrology, Adana Teaching and Medical Research Center, Baskent University, Adana (Turkey); Tercan, Fahri [Department of Radiology, Adana Teaching and Medical Research Center, Baskent University, Adana 01250 (Turkey); Kizilkilic, Osman [Department of Radiology, Adana Teaching and Medical Research Center, Baskent University, Adana 01250 (Turkey); Niron, E. Alp [Department of Radiology, Baskent University, Ankara (Turkey)
2005-05-01
Objective: To determine the incidence of abnormal hepatic vein Doppler waveform in patients with diffuse fatty infiltration of the liver (FIL). Materials and methods: In this prospective study, 40 patients with diffuse FIL and 50 normal healthy adults who served as control group underwent hepatic vein (HV) Doppler ultrasonography. The patients with the diagnosis of FIL were 23 men (57.5%) and 17 women aged 30-62 years (mean age {+-} S.D., 42 {+-} 12 years). Subjects in the control group were 27 men (54%) and 23 women aged 34-65 years (mean age {+-} S.D., 45 {+-} 14 years). The diagnosis of FIL was confirmed with computed tomography density measurements. The waveforms of HV were classified into three groups: regular triphasic waveform, biphasic waveform without a reverse flow, and monophasic or flat waveform. Etiological factors for FIL were diabetes mellitus (DM), hyperlipidemia and obesity (body mass index > 25). Serum lipid profile was obtained from all the patients with FIL. Results: Seventeen of the 40 patients (43%) with FIL had an abnormal HV Doppler waveform, whereas only one of the 50 (2%) healthy subjects had an abnormal waveform. The difference in the distribution of normal Doppler waveform pattern between the patients and the control group was significant (P < 0.001). No differences were found in the behaviour of the hepatic vein Doppler waveform in relation to the different etiologic factors for FIL (P > 0.05). There was not any correlation between the degree of fat infiltration and the hepatic vein waveform pattern (P = 0.60). Conclusion: Patients with fatty liver has a high rate of an abnormal hepatic vein Doppler waveform pattern which can be biphasic or monophasic. We could not find a relation between the etiological factors for FIL and the occurrence of an abnormal HV Doppler waveform.
FULL WAVEFORM LIDAR EXPLOITATION TECHNIQUE AND ITS EVALUATION IN THE MIXED FOREST HILLY REGION
S. Chhatkuli; Mano, K; Kogure, T; Tachibana, K; H. Shimamura
2012-01-01
In this paper a full waveform exploitation technique and its evaluation in the mixed forest hilly region is presented. The increment in ground penetration by using the full waveform exploitation technique compared to the discrete LiDAR pulses during autumn and winter season is evaluated. The results showed that the technique used for the full waveform exploitation has effectively increased the ground penetration by 50 % and 20 %, respectively, during autumn and winter in the mixed fo...
2014-12-01
RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM FOR COGNITIVE RADAR by Jo-Yen Nieh December 2014 Dissertation...TYPE AND DATES COVERED Dissertation 4. TITLE AND SUBTITLE INTEGRATED RANGE-DOPPLER MAP AND EXTENDED TARGET CLASSIFICATION WITH ADAPTIVE WAVEFORM ...design an extended target classification scheme while determining the target’s range-and-Doppler location with the use of adaptive waveform for a
An Identification Method of Magnetizing Inrush Current Phenomena by Voltage Waveform
Naitoh, Tadashi; Takeda, Keiki; Toyama, Atsushi; Maeda, Tatsuhiko
In this paper, the authors propose a new identification method of the magnetizing inrush current phenomena. In general, the identification is done using with current waveform. However, the saturation of current transformer can't give waveform. Therefore, the authors introduce the identification method using with voltage waveform, in which the saturation of voltage transformer doesn't happen. And then, applying the Aitken's Δ2-process, it is showed that the new identification method gives the exact saturation on/off time.
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.
Influence of Surface Topography on ICESat/GLAS Forest Height Estimation and Waveform Shape
Directory of Open Access Journals (Sweden)
Claudia Hilbert
2012-07-01
Full Text Available This study explores ICESat/GLAS waveform data in Thuringian Forest, a low mountain range located in central Germany. Lidar remote sensing has been proven to directly derive tree height as a key variable of forest structure. The GLAS signal is, however, very sensitive to surface topography because of the large footprint size. This study therefore focuses on forests in a mountainous area to assess the potential of GLAS data to derive terrain elevation and tree height. The work enhances the empirical knowledge about the interaction between GLAS waveform and landscape structure regarding a special temperate forest site with a complex terrain. An algorithm to retrieve tree height directly from GLA01 waveform data is proposed and compared to an approach using GLA14 Gaussian parameters. The results revealed that GLAS height estimates were accurate for areas with a slope up to 10° whereas waveforms of areas above 15° were problematic. Slopes between 10–15° have been found to be a critical crossover. Further, different waveform shape types and landscape structure classes were developed as a new possibility to explore the waveform in its whole structure. Based on the detailed analysis of some waveform examples, it could be demonstrated that the waveform shape can be regarded as a product of the complex interaction between surface and canopy structure. Consequently, there is a great variety of waveform shapes which in turn considerably hampers GLAS tree height extraction in areas with steep slopes and complex forest conditions.
Energy-efficient waveform shapes for neural stimulation revealed with a genetic algorithm
Wongsarnpigoon, Amorn; Grill, Warren M.
2010-08-01
The energy efficiency of stimulation is an important consideration for battery-powered implantable stimulators. We used a genetic algorithm (GA) to determine the energy-optimal waveform shape for neural stimulation. The GA was coupled to a computational model of extracellular stimulation of a mammalian myelinated axon. As the GA progressed, waveforms became increasingly energy efficient and converged upon an energy-optimal shape. The results of the GA were consistent across several trials, and resulting waveforms resembled truncated Gaussian curves. When constrained to monophasic cathodic waveforms, the GA produced waveforms that were symmetric about the peak, which occurred approximately during the middle of the pulse. However, when the cathodic waveforms were coupled to rectangular charge-balancing anodic pulses, the location and sharpness of the peak varied with the duration and timing (i.e., before or after the cathodic phase) of the anodic phase. In a model of a population of mammalian axons and in vivo experiments on a cat sciatic nerve, the GA-optimized waveforms were more energy efficient and charge efficient than several conventional waveform shapes used in neural stimulation. If used in implantable neural stimulators, GA-optimized waveforms could prolong battery life, thereby reducing the frequency of recharge intervals, the volume of implanted pulse generators, and the costs and risks of battery-replacement surgeries.
Simulation of droplet transfer process and current waveform control of CO2 arc welding
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
A simulation system used in the arc welding short-circuit transfer process and current waveform control process was developed in this paper. The simulation results are basically consistent with welding technical experiments. The simulation system can be used to simulate and test the current waveform control parameters with welding variables. By this simulation system, the influence regularities of the current waveform control parameters in the CO2 arc welding droplet short-circuit transfer process can be got. Moreover, the basic mode of real-time current waveform control can be also established by the simulation testing.
Vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography.
Ogino, Akihiro; Onishi, Kiyoshi
2014-01-01
We performed vascular waveform analysis of flap-feeding vessels using color Doppler ultrasonography and evaluated the blood flow in the flaps prior to surgery. Vascular waveform analysis was performed in 19 patients. The analyzed parameters included the vascular diameter, flow volume, flow velocity, resistance index, pulsatility index, and acceleration time. The arterial waveform was classified into 5 types based on the partially modified blood flow waveform classification reported by Hirai et al.; in particular, D-1a, D-1b, and D-2 were considered as normal waveforms. They were 4 patients which observed abnormal vascular waveform among 19 patients (D-4 : 1, D-3 : 1, and Poor detect : 2). The case which presented D-4 waveform changed the surgical procedure, and a favorable outcome was achieved. Muscle flap of the case which presented D-3 waveform was partially necrosed. The case which detected blood flow poorly was judged to be the vascular obstruction of the internal thoracic artery. In the evaluation of blood flow in flaps using color Doppler ultrasonography, determination of not only basic blood flow information, such as the vascular distribution and diameter and flow velocity, but also the flow volume, vascular resistance, and arterial waveform is essential to elucidate the hemodynamics of the flap.
Sensitivity of the gradient oscillatory number to flow input waveform shapes.
Shimogonya, Yuji; Kumamaru, Hiroshige; Itoh, Kazuhiro
2012-04-05
The sensitivity of the gradient oscillatory number (GON), which is a potential hemodynamic indicator for cerebral aneurysm initiation, to flow input waveform shapes was examined by performing computational fluid dynamics (CFD) simulations of an anatomical model of a human internal carotid artery under three different waveform shape conditions. The local absolute variation (standard deviation) and relative variation (coefficient of variation) of the GON calculations for three waveform shapes were computed to quantify the variation in GON due to waveform shape changes. For all waveform shapes, an elevated GON was evident at a known aneurysm site, albeit occurring at additional sites. No significant differences were observed among the qualitative GON distributions derived using the three different waveform shapes. These results suggest that the GON is largely insensitive to the variability in flow input waveform shapes. The quantitative analysis revealed that GON displays an improved relative variation over a relatively high GON range. We therefore conclude that it is reasonable to use assumed flow input waveform shapes as a substitute for individual real waveform shapes for the detection of possible GON elevations of individual clinical cases in large-scale studies, where the higher values of GON are of primary interest.
The development of advanced spread spectrum LFM waveforms for enhanced SAR and GMTI
Kirk, John C.; Darden, Scott; Majumder, Uttam K.; Minardi, Michael J.; Bell, Mark R.
2016-05-01
Advanced spread spectrum linear frequency modulated (LFM) waveforms are being developed for advanced capability synthetic aperture radar (SAR) and ground moving target indication (GMTI) applications. We have demonstrated by analysis and simulation the feasibility of these new type waveforms and are now in the process of implementing them in hardware. The basic approach is to combine a traditional LFM radar waveform with a direct sequence spread spectrum (DSSS) waveform, and then on receive to de-spread the return and capture the resultant LFM return for traditional matched filter processing and enhanced SAR and GMTI. We show the analysis, simulation and some preliminary hardware results.
Arbitrary Waveform Generator for Quantum Information Processing with Trapped Ions
Bowler, R; Britton, J W; Sawyer, B C; Amini, J
2013-01-01
Atomic ions confined in multi-electrode traps have been proposed as a basis for scalable quantum information processing. This scheme involves transporting ions between spatially distinct locations by use of time-varying electric potentials combined with laser or microwave pulses for quantum logic in specific locations. We report the development of a fast multi-channel arbitrary waveform generator for applying the time-varying electric potentials used for transport and for shaping quantum logic pulses. The generator is based on a field-programmable gate array controlled ensemble of 16-bit digital-to-analog converters with an update frequency of 50 MHz and an output range of $\\pm$10 V. The update rate of the waveform generator is much faster than relevant motional frequencies of the confined ions in our experiments, allowing diabatic control of the ion motion. Numerous pre-loaded sets of time-varying voltages can be selected with 40 ns latency conditioned on real-time signals. Here we describe the device and de...
Acquisition of L2 Japanese Geminates: Training with Waveform Displays
Directory of Open Access Journals (Sweden)
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.
Control of ion energy and angular distributions using voltage waveform
Energy Technology Data Exchange (ETDEWEB)
Rauf, S.
1999-07-01
A number of plasma-aided microelectronics manufacturing processes sensitively depend on the ion characteristics at the substrate, in particular the ion energy (IEDF) and angular (IADF) distribution functions. The outcome of these processes can be much more precisely controlled if one has direct control over the IEDFs and IADFs. Past studies have explored the influence of rb bias voltage amplitude and frequency, inductive power deposition and gas pressure on the ion characteristics at the substrate. The factor that influences the ion dynamics most is however the time-dependent sheath voltage and, as demonstrated in this paper, sheath voltage can be accurately controlled using the rf bias voltage waveform. In this paper, the authors computationally examine the influence of the rf bias voltage waveform on the IEDFs and IADFs at the substrate in an inductively coupled plasma (ICP) reactor. This study has been conducted using a coupled set of the Hybrid Plasma Equipment Model (HPEM) and a circuit model, and the Plasma Chemistry Monte Carlo Simulation (PCMCS).
Guided Wave Tomography Based on Full-Waveform Inversion.
Rao, Jing; Ratassepp, Madis; Fan, Zheng
2016-02-29
In this paper, a guided wave tomography method based on Full Waveform Inversion (FWI) is developed for accurate and high resolu- tion reconstruction of the remaining wall thickness in isotropic plates. The forward model is computed in the frequency domain by solving a full-wave equation in a two-dimensional acoustic model, accounting for higher order eects such as diractions and multiple scattering. Both numerical simulations and experiments were carried out to obtain the signals of a dispersive guided mode propagating through defects. The inversion was based on local optimization of a waveform mist func- tion between modeled and measured data, and was applied iteratively to discrete frequency components from low to high frequencies. The resulting wave velocity maps were then converted to thickness maps by the dispersion characteristics of selected guided modes. The results suggest that the FWI method is capable to reconstruct the thickness map of a irregularly shaped defect accurately on a 10 mm thick plate with the thickness error within 0.5 mm.
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.
Waveform design for cognitive radar: target detection in heavy clutter
Kirk, Benjamin H.; Narayanan, Ram M.; Martone, Anthony F.; Sherbondy, Kelly D.
2016-05-01
In many applications of radar systems, detection of targets in environments with heavy clutter and interference can be difficult. It is desired that a radar system should detect targets at a further range as well as be able to detect these targets with very few false positive or negative readings. In a cognitive radar system, there are ways that these negative effects can be mitigated and target detection can be significantly improved. An important metric to focus on for increasing target detectability is the signal-to-clutter ratio (SCR). Cognitive radar offers solutions to issues such as this with the use of a priori knowledge of targets and environments as well as real time adaptations. A feature of cognitive radar that is of interest is the ability to adapt and optimize transmitted waveforms to a given situation. A database is used to hold a priori and dynamic knowledge of the operational environment and targets to be detected, such as clutter characteristics and target radar cross-section (RCS) estimations. Assuming this knowledge is available or can be estimated in real-time, the transmitted waveform can be tailored using methods such as transmission of a spectrum corresponding to the target-to-clutter ratio (TCR). These methods provide significant improvement in distinguishing targets from clutter or interference.
Platform for Post-Processing Waveform-Based NDE
Roth, Don J.
2010-01-01
Signal- and image-processing methods are commonly needed to extract information from the waves, improve resolution of, and highlight defects in an image. Since some similarity exists for all waveform-based nondestructive evaluation (NDE) methods, it would seem that a common software platform containing multiple signal- and image-processing techniques to process the waveforms and images makes sense where multiple techniques, scientists, engineers, and organizations are involved. NDE Wave & Image Processor Version 2.0 software provides a single, integrated signal- and image-processing and analysis environment for total NDE data processing and analysis. It brings some of the most useful algorithms developed for NDE over the past 20 years into a commercial-grade product. The software can import signal/spectroscopic data, image data, and image series data. This software offers the user hundreds of basic and advanced signal- and image-processing capabilities including esoteric 1D and 2D wavelet-based de-noising, de-trending, and filtering. Batch processing is included for signal- and image-processing capability so that an optimized sequence of processing operations can be applied to entire folders of signals, spectra, and images. Additionally, an extensive interactive model-based curve-fitting facility has been included to allow fitting of spectroscopy data such as from Raman spectroscopy. An extensive joint-time frequency module is included for analysis of non-stationary or transient data such as that from acoustic emission, vibration, or earthquake data.
LPI Radar Waveform Recognition Based on Time-Frequency Distribution.
Zhang, Ming; Liu, Lutao; Diao, Ming
2016-10-12
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.
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.
Plant Electrical Signal Classification Based on Waveform Similarity
Directory of Open Access Journals (Sweden)
Yang Chen
2016-10-01
Full Text Available (1 Background: Plant electrical signals are important physiological traits which reflect plant physiological state. As a kind of phenotypic data, plant action potential (AP evoked by external stimuli—e.g., electrical stimulation, environmental stress—may be associated with inhibition of gene expression related to stress tolerance. However, plant AP is a response to environment changes and full of variability. It is an aperiodic signal with refractory period, discontinuity, noise, and artifacts. In consequence, there are still challenges to automatically recognize and classify plant AP; (2 Methods: Therefore, we proposed an AP recognition algorithm based on dynamic difference threshold to extract all waveforms similar to AP. Next, an incremental template matching algorithm was used to classify the AP and non-AP waveforms; (3 Results: Experiment results indicated that the template matching algorithm achieved a classification rate of 96.0%, and it was superior to backpropagation artificial neural networks (BP-ANNs, supported vector machine (SVM and deep learning method; (4 Conclusion: These findings imply that the proposed methods are likely to expand possibilities for rapidly recognizing and classifying plant action potentials in the database in the future.
Pan, Yi; Taracchini, Andrea; Kidder, Lawrence E; Mroue, Abdul H; Pfeiffer, Harald P; Scheel, Mark A; Szilagyi, Bela
2013-01-01
We describe a general procedure to generate spinning, precessing waveforms that include inspiral, merger and ringdown stages in the effective-one-body (EOB) approach. The procedure uses a precessing frame in which precession-induced amplitude and phase modulations are minimized, and an inertial frame, aligned with the spin of the final black hole, in which we carry out the matching of the inspiral-plunge to merger-ringdown waveforms. As a first application, we build spinning, precessing EOB waveforms for the gravitational modes l=2 such that in the nonprecessing limit those waveforms agree with the EOB waveforms recently calibrated to numerical-relativity waveforms. Without recalibrating the EOB model, we then compare EOB and post-Newtonian precessing waveforms to two numerical-relativity waveforms produced by the Caltech-Cornell-CITA collaboration. The numerical waveforms are strongly precessing and have 35 and 65 gravitational-wave cycles. We find a remarkable agreement between EOB and numerical-relativity ...
A technique for the generation of customizable ultra-wideband pseudo-noise waveforms
Vela, Russell; Erisman, David; Narayanan, Ram M.
2011-06-01
Noise excitation sources in radar systems have become increasingly useful in applications requiring wideband spectral responses and covertness. However, in applications requiring spectral controllability, traditional analog noise sources prove troublesome and require additional hardware such as sets of digital filters whose own spectral characteristics must also be accounted for. In an effort to reduce these issues and increase the applications of noise waveforms, a technique for generating a fully controllable pseudo-noise waveform is presented. This pseudo-noise waveform will be generated through the use of a multi-tone waveform. By randomizing the phase angles and setting the appropriate amplitudes to the individual tones, the result is a waveform whose temporal pattern resembles noise and frequency response is broadband. The capabilities of this digitally produced pseudo-noise multi-tone waveform is presented by optimization via a water-filling technique, thereby producing a flat spectral response for a user defined amplitude, effectively removing the spectral effects of the radar components. This optimized waveform is used to present methods for increasing signal to noise ratio (SNR) of cross-correlated responses of the waveform through the application of window functions to the waveform. As a whole, this paper showcases the ability to use this pseudo-noise multi-tone waveform for complete ultra-wideband (UWB) spectral control through water-filling and a method for increasing SNR of the cross correlated response of the transmitted and received radar waveform for a bandwidth of 2.5 GHz ranging from 2 to 4.5 GHz.
Institute of Scientific and Technical Information of China (English)
Ren Tingzhi; Liu Cai
2004-01-01
A new non-sinusoidal oscillation waveform is constructed for controlling the mold oscillation during continuous casting. Casting velocity and oscillation parameters are then established for a computer model of the continuous casting process. The waveform distortion coefficient ε of waveform function is close to the waveform distortion rate α, so ε is taken for ε when the basic parameters are selected initially. The waveform function can be created for the servo hydraulic system or the mechanical driving system. Industrial scale experiments show the waveform function is effective.
Full Seismic Waveform Inversion for the Japanese Islands
Žukauskaitė, Saulė; Steptoe, Hamish; Fichtner, Andreas
2015-04-01
We present a seismic tomography model for the Japanese archipelago obtained using full waveform inversion and adjoint methods. A credible seismic velocity model is essential for the Japan region as a means to further our understanding of earthquake source mechanics by allowing for more accurate seismic source inversion, to benefit seismic hazard assessment as well as early warning systems, and to comprehend the complexity of the tectonic setting. The study area covers the Japanese islands, Taiwan, Korean peninsula, easternmost parts of China and Russia, Sakhalin and the majority of the Kuril Islands chain. The domain extends down into the mantle transition zone. We choose 58 earthquakes of magnitudes Mw5.0 - 6.9 distributed across the model domain as uniformly as possible. The data are obtained from several seismic networks in the area, namely F-net in Japan, BATS in Taiwan, South Korean National Earthquake Network and several stations from each China National Seismic Network, New China Digital Seismograph Network, Global Seismograph Network and Korean Seismic Network made available by IRIS Data Management Center. To facilitate full waveform inversion the forward problem is solved numerically using the spectral element method (SEM), which comes with the geometric flexibility of the finite-elements method and the accuracy of the spectral methods. Owing to the SEM and the advance in High Performance Computing we are able to perform numerical simulations of seismic waves in realistic 3D heterogeneous visco-elastic structures. Differences between the calculated and the real waveforms are quantified using the time-frequency misfits (Fichtner et al., 2008), which allow us to explore the temporal evolution of the frequency content of the data with no need to identify specific seismic phases. We use adjoint methods as an effective means to obtain sensitivity kernels and ultimately gradients, required for iterative gradient-based minimisation techniques. The obtained model
Full Waveform Seismic Inversion for the Japan Region
Žukauskaitė, Saulė; Steptoe, Hamish; Fichtner, Andreas
2014-05-01
We present a seismic tomography model for the Japan archipelago obtained using full waveform inversion and adjoint methods. A high-resolution seismic velocity model is essential for Japan as means to comprehend and characterize the complexity of the tectonic setting, and to further our understanding of earthquake sources and rupture propagation. The study area covers the Japanese islands - an area between 20°-50°N and 130°-160°E - and extends to a maximum depth of 500 km. In virtue of complicated tectonics and resulting high seismicity, dense seismic networks are present in Japan and surrounding countries. We make use of broadband data from three networks - F-net in Japan, BATS in Taiwan, and notably, the National Earthquake Network in South Korea. Due to access difficulties, data from this network had not been used in the preceding tomographic study of the same area. We use >50 carefully selected earthquakes, located within the model area and occurring between 1999 and the present. Magnitudes of the events are restricted to 5≤Mw≤6.9 for a point source approximation to be valid. A spectral-element method is used for forward waveform calculation, which comes with the geometric flexibility of finite-elements method and the accuracy of spectral methods. To quantify differences between the observed and synthetic waveforms, we use time-frequency misfits, which exploit the evolution of the frequency content of the data in time. The sensitivities (Fréchet kernels) are then calculated using adjoint methods. The employed methodology allows us to explain the data of dominant period as low as 10 s. To prevent possible over-fitting of the data, we ensure that final misfits are not lower than those obtained if additional (not yet used) data are incorporated. The final results of this study will contribute to the 'Comprehensive Earth Model' being developed by the Computational Seismology group at ETH, with the aim to represent the snapshot of the current knowledge of
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
Mitigating local minima in full-waveform inversion by expanding the search space
Herrmann, Felix J.; van Leeuwen, Tristan
2013-01-01
Wave-equation based inversions, such as full-waveform inversion, are challenging because of their computational costs, memory requirements, and reliance on accurate initial models. To confront these issues, we propose a novel formulation of full-waveform inversion based on a penalty method. In this
Waveform measurement in mocrowave device characterization: impact on power amplifiers design
Directory of Open Access Journals (Sweden)
Roberto Quaglia
2016-07-01
Full Text Available This paper describes an example of a measurement setup enabling waveform measurements during the load-pull characterization of a microwave power device. The significance of this measurement feature is highlighted showing how waveform engineering can be exploited to design high efficiency microwave power amplifiers.
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...
2009-09-01
Narrowband Waveform over Slow, Flat Nakagami Fading Channels,” Proc. IEEE MILCOM, November 2008. [13] Bernard Sklar, Digital Communications...JTIDS.Link-16-type Waveform Transmitted over Nakagami Fading Channels with Pulsed-Noise Interference,” Proc. IEEE Military Commun. Conf., 2008
Suitability of post-Newtonian/numerical-relativity hybrid waveforms for gravitational wave detectors
Energy Technology Data Exchange (ETDEWEB)
MacDonald, Ilana; Nissanke, Samaya; Pfeiffer, Harald P, E-mail: macdonald@astro.utoronto.ca [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8 (Canada)
2011-07-07
This paper presents a study of the sufficient accuracy of post-Newtonian and numerical relativity waveforms for the most demanding usage case: parameter estimation of strong sources in advanced gravitational wave detectors. For black hole binaries, these detectors require accurate waveform models which can be constructed by fusing an analytical post-Newtonian inspiral waveform with a numerical relativity merger-ringdown waveform. We perform a comprehensive analysis of errors that enter such 'hybrid waveforms'. We find that the post-Newtonian waveform must be aligned with the numerical relativity waveform to exquisite accuracy, about 1/100 of a gravitational wave cycle. Phase errors in the inspiral phase of the numerical relativity simulation must be controlled to {approx}< 0.1 rad. (These numbers apply to moderately optimistic estimates about the number of GW sources; exceptionally strong signals require even smaller errors.) The dominant source of error arises from the inaccuracy of the investigated post-Newtonian Taylor approximants. Using our error criterion, even at 3.5th post-Newtonian order, hybridization has to be performed significantly before the start of the longest currently available numerical waveforms which cover 30 gravitational wave cycles. The current investigation is limited to the equal-mass, zero-spin case and does not take into account calibration errors of the gravitational wave detectors.
Noninvasive arterial blood pressure waveform monitoring using two- element ultrasound system.
Seo, Joohyun; Pietrangelo, Sabino J; Lee, Hae-Seung; Sodini, Charles G
2015-04-01
This work details noninvasive arterial blood pressure (ABP) waveform estimation based on an arterial vessel cross-sectional area measurement combined with an elasticity measurement of the vessel, represented by pulse wave velocity (PWV), using a two-element ultrasound system. The overall ABP waveform estimation is validated in a custom-designed experimental setup mimicking the heart and an arterial vessel segment with two single element transducers, assuming a constant hemodynamic system. The estimation of local PWV using the flow-area method produces unbiased elasticity estimation of the tube in a pressure waveform comparison. The measured PWV using 16 cardiac cycles of data is 8.47 + 0.63 m/s with an associated scaling error of -1.56 + 14.0% in a direct pressure waveform comparison, showing negligible bias error on average. The distension waveform obtained from a complex cross-correlation model estimator (C3M) reliably traces small pressure changes reflected by the diameter change. The excellent agreement of an estimated pressure waveform to the reference pressure waveform suggests the promising potential of a readily available, inexpensive, and portable ABP waveform monitoring device.
Waveform model of a laser altimeter for an elliptical Gaussian beam.
Yue, Ma; Mingwei, Wang; Guoyuan, Li; Xiushan, Lu; Fanlin, Yang
2016-03-10
The current waveform model of a laser altimeter is based on the Gaussian laser beam of the fundamental mode, whose cross section is a circular spot, whereas some of the cross sections of Geoscience Laser Altimeter System lasers are closer to elliptical spots. Based on the expression of the elliptical Gaussian beam and the waveform theory of laser altimeters, the primary parameters of an echo waveform were derived. In order to examine the deduced expressions, a laser altimetry waveform simulator and waveform processing software were programmed and improved under the circumstance of an elliptical Gaussian beam. The result shows that all the biases between the theoretical and simulated waveforms were less than 0.5%, and the derived model of an elliptical spot is universal and can also be used for the conventional circular spot. The shape of the waveforms is influenced by the ellipticity of the laser spot, the target slope, and the "azimuth angle" between the major axis and the slope direction. This article provides the waveform theoretical basis of a laser altimeter under an elliptical Gaussian beam.
Time domain reflectometry waveform analysis with second order bounded mean oscillation
Tangent-line methods and adaptive waveform interpretation with Gaussian filtering (AWIGF) have been proposed for determining reflection positions of time domain reflectometry (TDR) waveforms. However, the accuracy of those methods is limited for short probe TDR sensors. Second order bounded mean osc...
Within-footprint roughness measurements using ICESat/GLAS waveform and LVIS elevation
Li, Xiaolu; Xu, Kai; Xu, Lijun
2016-12-01
The surface roughness is an important characteristic over an ice sheet or glacier, since it is an identification of boundary-layer meteorology and is an important limiter on the accuracy of surface-height measurements. In this paper, we propose a simulation method to derive the within-footprint roughness (called simulation-derived roughness) using ICESat/GLAS echo waveform, laser vegetation imaging sensor (LVIS) elevations, and laser profile array (LPA) images of ICESat/GLAS. By dividing the within-footprint surface into several elements, a simulation echo waveform can be obtained as the sum of the elementary pulses reflected from each surface element. The elevation of the surface elements, which is utilized to get the return time of the elementary pulses, is implemented based on an LVIS interpolated elevation using a radial basis function (RBF) neural network. The intensity of the elementary pulses can be obtained from the thresholded LPA images. Based on the return time and the intensity of the elementary pulses, we used the particle swarm optimization (PSO) method to approximate the simulation waveform to the ICESat/GLAS echo waveform. The full width at half maximum) (FWHM) of the elementary pulse was extracted from the simulation waveform for estimating the simulation-derived roughness. By comparing with the elevation-derived roughness (derived from the elevation) and the waveform-derived roughness (derived from the ICESat/GLAS waveform), the proposed algorithm can exclude the slope effect from waveform width broadening for describing the roughness of the surface elements.
Reduced order model for binary neutron star waveforms with tidal interactions
Lackey, Benjamin; Bernuzzi, Sebastiano; Galley, Chad
2016-03-01
Observations of inspiralling binary neutron star (BNS) systems with Advanced LIGO can be used to determine the unknown neutron-star equation of state by measuring the phase shift in the gravitational waveform due to tidal interactions. Unfortunately, this requires computationally efficient waveform models for use in parameter estimation codes that typically require 106-107 sequential waveform evaluations, as well as accurate waveform models with phase errors less than 1 radian over the entire inspiral to avoid systematic errors in the measured tidal deformability. The effective one body waveform model with l = 2 , 3, and 4 tidal multipole moments is currently the most accurate model for BNS systems, but takes several minutes to evaluate. We develop a reduced order model of this waveform by constructing separate orthonormal bases for the amplitude and phase evolution. We find that only 10-20 bases are needed to reconstruct any BNS waveform with a starting frequency of 10 Hz. The coefficients of these bases are found with Chebyshev interpolation over the waveform parameter space. This reduced order model has maximum errors of 0.2 radians, and results in a speedup factor of more than 103, allowing parameter estimation codes to run in days to weeks rather than decades.
The Performance of Altimeter Waveform Retrackers at Lake Baikal
Directory of Open Access Journals (Sweden)
Yuchan Yi
2013-01-01
Full Text Available At each of five fixed locations along the ground tracks of JASON-1 and ENVISAT, a repeat-track analysis of 1-Hz sea surface height (SSH data has been conducted to assess the performance of waveform retrackers over Lake Baikal in Siberia, Russia. This simple analysis of time series at each point location is needed to minimize the effect of the range correction artifacts in current Geophysical Data Record (GDR data products of radar altimeters in in-land areas. Using the retracked data available in the GDRs as the baseline, two retrackers are evaluated in terms of the number of valid data points produced and the degree of agreement with in-situ data of water level record. The threshold retrackers that are based on the amplitude of the robust OCOG algorithm (Offset Center of Gravity are found to perform the best in Lake Baikal.
Automatic physiological waveform processing for FMRI noise correction and analysis.
Directory of Open Access Journals (Sweden)
Daniel J Kelley
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.
Digitally Recorded Impulse Voltage Waveform and its Parameters
Sato, Shuji; Ichikawa, Hironori; Saitou, Tatsunori; Harada, Tatsuya; Hanai, Masahiro
Whereas high resolution digital recorders are used in recording the impulse voltage tests in prominent accreditation laboratories worldwide, a usage of an 8 bit recorder is also allowed by IEC publication. An 8 bit recorder is, due to its nature, known to record a waveform with 0.4% vertical resolution and it has not been appreciated for determining a peak value of lightning impulse in the reference measuring system where the scale factor is often evaluated with 0.1% or less uncertainty. This paper demonstrates simulation in which an 8 bit record with an internal noise is fed into the lightning impulse parameter determination software and the computed parameters were compared with theoretical values. The results show that, if suitable software is used, errors in parameters deduced from an 8 bit record is as small as those derived from a 12 bit record, suggesting an inexpensive 8 bit recorder can replace a 12 bit in impulse voltage measurements.
Pulsar average waveforms and hollow cone beam models
Backer, D. C.
1975-01-01
An analysis of pulsar average waveforms at radio frequencies from 40 MHz to 15 GHz is presented. The analysis is based on the hypothesis that the observer sees one cut of a hollow-cone beam pattern and that stationary properties of the emission vary over the cone. The distributions of apparent cone widths for different observed forms of the average pulse profiles (single, double/unresolved, double/resolved, triple and multiple) are in modest agreement with a model of a circular hollow-cone beam with random observer-spin axis orientation, a random cone axis-spin axis alignment, and a small range of physical hollow-cone parameters for all objects.
Full waveform hyperspectral LiDAR for terrestrial laser scanning.
Hakala, Teemu; Suomalainen, Juha; Kaasalainen, Sanna; Chen, Yuwei
2012-03-26
We present the design of a full waveform hyperspectral light detection and ranging (LiDAR) and the first demonstrations of its applications in remote sensing. The novel instrument produces a 3D point cloud with spectral backscattered reflectance data. This concept has a significant impact on remote sensing and other fields where target 3D detection and identification is crucial, such as civil engineering, cultural heritage, material processing, or geomorphological studies. As both the geometry and spectral information on the target are available from a single measurement, this technology will extend the scope of imaging spectroscopy into spectral 3D sensing. To demonstrate the potential of the instrument in the remote sensing of vegetation, 3D point clouds with backscattered reflectance and spectral indices are presented for a specimen of Norway spruce.
Early arrival waveform inversion of shallow seismic land data
Hanafy, Sherif M.
2013-09-22
We estimate the near-surface velocity distribution over Wadi Qudaid in Saudi Arabia by applying early arrival waveform inversion (EWI) to shallow seismic land data collected with source-receiver offsets no longer than 232 m. The main purpose is to characterize the shallow subsurface for its water storage and reuse potential. To enhance the accuracy of EWI, we extracted a natural source wavelet from the data, and also corrected for the attenuation effects with an estimated factor Q. Results suggest that, compared to traveltime tomography, EWI can generate a highly resolved velocity tomogram from shallow seismic data. The more accurate EWI tomogram can make an economically important difference in assessing the storage potential of this wadi; in this case we find an increase of 18% of storage potential in the EWI tomogram relative to the traveltime tomogram. This approach suggests that FWI might be a more accurate means for economically characterizing the water storage potential for wadis’ throughout the world.
Full-waveform inversion: From near surface to deep
Alkhalifah, Tariq Ali
2013-11-01
The ancient Persian Gulf port city of Muscat provided a spectacular setting for the SEG\\'s 2013 Workshop on Full-waveform Inversion (FWI). This active R&D topic attracted about 36 oral presentations and 20 or so posters, which added up to three intense days of ideas, images, and discussion. FWI has progressed from academic research topic to commercial workflow component in roughly 10 years, with many case studies documenting improved imaging and business value and others documenting a definite need for improved understanding of algorithms and applicability. Along with fundamental research issues of worldwide importance, the meeting provided an opportunity to showcase implications of the Middle East\\'s particular exploration challenges for the further development of FWI.
Multigrid waveform relaxation on spatial finite element meshes
Energy Technology Data Exchange (ETDEWEB)
Janssen, J. [Katholieke Universiteit Leuven (Belgium); Vandewalle, S. [Caltech, Pasadena, CA (United States)
1994-12-31
The authors shall discuss the numerical solution of a parabolic partial differential equation {partial_derivative}u/{partial_derivative}t(x,t) = Lu(x,t) + f(x,t), x{element_of}{Omega}, t>0, (1) supplied with a boundary condition and given initial values. The spatial finite element discretization of (1) on a discrete grid {Omega}{sub h} leads to an initial value problem of the form B{dot u} + Au = f, u(0) = u{sub o}, t > 0, (2) with B a non-singular matrix. The waveform relaxation method is a method for solving ordinary differential equations. It differs from most standard iterative techniques in that it is a continuous-time method, iterating with functions in time, and thereby well-suited for parallel computation.
Detection of underground pipeline based on Golay waveform design
Dai, Jingjing; Xu, Dazhuan
2017-08-01
The detection of underground pipeline is an important problem in the development of the city, but the research about it is not mature at present. In this paper, based on the principle of waveform design in wireless communication, we design an acoustic signal detection system to detect the location of underground pipelines. According to the principle of acoustic localization, we chose DSP-F28335 as the development board, and use DA and AD module as the master control chip. The DA module uses complementary Golay sequence as emission signal. The AD module acquisiting data synchronously, so that the echo signals which containing position information of the target is recovered through the signal processing. The test result shows that the method in this paper can not only calculate the sound velocity of the soil, but also can locate the location of underground pipelines accurately.
Efficient And Portable SDR Waveform Development: The Nucleus Concept
Ramakrishnan, Venkatesh; Kempf, Torsten; Kammler, David; Ascheid, Gerd; Meyr, Heinrich; Adrat, Marc; Antweiler, Markus
2009-01-01
Future wireless communication systems should be flexible to support different waveforms (WFs) and be cognitive to sense the environment and tune themselves. This has lead to tremendous interest in software defined radios (SDRs). Constraints like throughput, latency and low energy demand high implementation efficiency. The tradeoff of going for a highly efficient implementation is the increase of porting effort to a new hardware (HW) platform. In this paper, we propose a novel concept for WF development, the Nucleus concept, that exploits the common structure in various wireless signal processing algorithms and provides a way for efficient and portable implementation. Tool assisted WF mapping and exploration is done efficiently by propagating the implementation and interface properties of Nuclei. The Nucleus concept aims at providing software flexibility with high level programmability, but at the same time limiting HW flexibility to maximize area and energy efficiency.
Analyzing the Waveform of the Shunchang Earthquakes in Fujian Province
Institute of Scientific and Technical Information of China (English)
Hong Xing; Ye Wenyan; Shao Pingrong
2008-01-01
On March 13,2007,two earthquakes with M4.7 and M4.6 occurred in Zhengfang Village,Shunchang,Fujian.The M4.7 earthquake is the most intensive one in the Fujian region since the establishment of the Fujian digital seismic networks.These two earthquakes provide us with valuable first-hand observation data for seismological research.This paper analyzes their wave forms and concludes that (1) the crustal thickness in the seismic region is estimated to be about 40km according to the observed head-wave critical distance;(2) there is a salient difference between the ratios of S-wave's maximum amplitudes of these two earthquakes;(3) the focal depth of the M4.7 earthquake is estimated to be 8.4km according to the clear depth phrase sPn in waveforms,which is the same with the result of other determination methods.
Triangle/Square Waveform Generator Using Area Efficient Hysteresis Comparator
Directory of Open Access Journals (Sweden)
M. Drinovsky
2016-06-01
Full Text Available A function generator generating both square and triangle waveforms is proposed. The generator employs only one low area comparator with accurate hysteresis set by a bias current and a resistor. Oscillation frequency and its non-idealities are analyzed. The function of the proposed circuit is demonstrated on a design of 1 MHz oscillator in STMicroelectronics 180 nm BCD technology. The designed circuit is thoroughly simulated including trimming evaluation. It consumes 4.1 μA at 1.8 V and takes 0.0126 mm2 of silicon area. The temperature variation from -40°C to 125°C is ±1.5 % and the temperature coefficient is 127 ppm/°C.
Full Waveform Inversion for Reservoir Characterization - A Synthetic Study
Zabihi Naeini, E.
2017-05-26
Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI) as an alternative tool for higher-resolution reservoir characterization. An important step in developing reservoir-oriented FWI is the implementation of facies-based rock physics constraints adapted from the classic methods. We show that such constraints can be incorporated into FWI by adding appropriately designed regularization terms to the objective function. The advantages of the proposed algorithm are demonstrated on both isotropic and VTI (transversely isotropic with a vertical symmetry axis) models with pronounced lateral and vertical heterogeneity. The inversion results are explained using the theoretical radiation patterns produced by perturbations in the medium parameters.
Detector apparatus having a hybrid pixel-waveform readout system
Meng, Ling-Jian
2014-10-21
A gamma ray detector apparatus comprises a solid state detector that includes a plurality of anode pixels and at least one cathode. The solid state detector is configured for receiving gamma rays during an interaction and inducing a signal in an anode pixel and in a cathode. An anode pixel readout circuit is coupled to the plurality of anode pixels and is configured to read out and process the induced signal in the anode pixel and provide triggering and addressing information. A waveform sampling circuit is coupled to the at least one cathode and configured to read out and process the induced signal in the cathode and determine energy of the interaction, timing of the interaction, and depth of interaction.
Conditioning the full waveform inversion gradient to welcome anisotropy
Alkhalifah, Tariq Ali
2014-08-05
Multi-parameter full waveform inversion (FWI) suffers from the complex nonlinearity in the objective function, compounded by the eventual tradeoff between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade off. The filter is based on representing the gradient in the time-lag normalized domain in which the small scattering angles of the gradient update is initially muted out. A model update hierarchical filtering strategy includes applying varying degree of filtering to the different parameter updates. A feature not easily accessible to simple data decimation. Using both FWI and reection based FWI (RFWI), two strategies to combat the tradeoff between anisotropic parameters are outlined.
3-D waveform tomography sensitivity kernels for anisotropic media
Djebbi, R.
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.
Measurement of vehicles speed with full waveform lidar
Muzal, Michał; Mierczyk, Zygmunt; Zygmunt, Marek; Wojtanowski, Jacek; Piotrowski, Wiesław
2016-12-01
Measurement of vehicles speed by means of displacement measurement with "time of flight" lidar requires gathering of accurate information about distance to the vehicle in a set time interval. As with any pulsed laser lidar, its maximum range is limited by available incoming signal to noise ratio. That ratio determines not only maximum range, but also accuracy of measurement. For fast and precise measurements of speed of the vehicles their displacement should bee measured with centimeter accuracy. However that demand is hard to reach on long distances and poor quality of the echo signal. Improving accuracy beyond given by a single pulse probing requires emission of several probing pulses. Total displacement error will than fall with the square root of the number of executed measurements. Yet this method will not extend available distance beyond the limit set by threshold detection systems. Acquisition of the full waveform of received signals is a method that allows extension of maximum range through synchronic addition of subsequent waveforms. Doing so improves SNR by a well-known factor of square root of the number of carried additions. Disadvantage of this method is that it requires use of fast analog to digital converters for data acquisition, and simple distance calculation algorithms may not give the adequate accuracy due to relatively long sampling period of reasonable priced ADC's. In this article more advanced algorithms of distance calculations that base on ADC raw data are presented and analyzed. Practical implementation of algorithm in prototype design of laser speed gun is shown along with real life test results.
Fong, Allan; Mittu, Ranjeev; Ratwani, Raj; Reggia, James
2014-01-01
Alarm fatigue caused by false alarms and alerts is an extremely important issue for the medical staff in Intensive Care Units. The ability to predict electrocardiogram and arterial blood pressure waveforms can potentially help the staff and hospital systems better classify a patient's waveforms and subsequent alarms. This paper explores the use of Echo State Networks, a specific type of neural network for mining, understanding, and predicting electrocardiogram and arterial blood pressure waveforms. Several network architectures are designed and evaluated. The results show the utility of these echo state networks, particularly ones with larger integrated reservoirs, for predicting electrocardiogram waveforms and the adaptability of such models across individuals. The work presented here offers a unique approach for understanding and predicting a patient's waveforms in order to potentially improve alarm generation. We conclude with a brief discussion of future extensions of this research.
Effects of waveform model systematics on the interpretation of GW150914
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; 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; 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; 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; 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 A; Calloni, E; Camp, J B; Cannon, K C; Cao, H; 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; 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; 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; Cowan, E E; Coward, D M; Cowart, M J; Coyne, D C; Coyne, R; Creighton, J D E; Creighton, T D; Cripe, J; Crowder, S G; Cullen, T J; Cumming, A; Cunningham, L; Cuoco, E; Canton, T Dal; Danilishin, S L; D'Antonio, S; Danzmann, K; Dasgupta, A; Costa, C F Da Silva; 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; Del'eglise, 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; 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; Doctor, Z; Dolique, V; Donovan, F; Dooley, K L; Doravari, S; Dorrington, I; Douglas, R; 'Alvarez, M Dovale; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Ducrot, M; Dwyer, S E; 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; Galiana, A Fern'andez; 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; Gonz'alez, G; Castro, J M Gonzalez; Gopakumar, A; Gorodetsky, M L; Gossan, S E; 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; Gushwa, K E; 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; Holz, D E; 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; Jim'enez-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; K'ef'elian, 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; Kr"amer, C; Kringel, V; Krishnan, B; Kr'olak, 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; Lord, J E; Lorenzini, M; Loriette, V; Lormand, M; Losurdo, G; Lough, J D; Lovelace, G; L"uck, H; Lundgren, A P; Lynch, R; Ma, Y; Macfoy, S; Machenschalk, B; MacInnis, M; Macleod, D M; Magana-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; M'arka, S; M'arka, 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; McClelland, D E; 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; 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; 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; Pace, A E; 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; 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; 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; 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; 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; Sch"onbeck, 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; 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Valdes, G; 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 Heijningen, J V; van Veggel, A A; Vardaro, M; Varma, V; Vass, S; Vas'uth, M; Vecchio, A; Vedovato, G; Veitch, J; Veitch, P J; Venkateswara, K; Venugopalan, G; Verkindt, D; Vetrano, F; Vicer'e, 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; Wade, L E; 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; zny, A Zadro; 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; Zucker, M E; Zweizig, J; Boyle, M; Chu, T; Hemberger, D; Hinder, I; Kidder, L E; Ossokine, S; Scheel, M; Szilagyi, B; Teukolsky, S; Vano-Vinuales, A
2016-01-01
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 analyses on mock signals from numerical simulations of a serie...
Fast Frequency-domain Waveforms for Spin-Precessing Binary Inspirals
Klein, Antoine; Yunes, Nicolás
2014-01-01
The detection and characterization of gravitational wave signals from compact binary coalescence events relies on accurate waveform templates in the frequency domain. The stationary phase approximation (SPA) can be used to compute closed-form frequency-domain waveforms for non-precessing, quasi-circular binary inspirals. However, until now, no fast frequency-domain waveforms have existed for generic, spin-precessing quasi-circular compact binary inspirals. Templates for these systems have had to be computed via a discrete Fourier transform of finely sampled time-domain waveforms, which is far more computationally expensive than those constructed directly in the frequency-domain, especially for those systems that are dominated by the inspiral part. There are two obstacles to deriving frequency-domain waveforms for precessing systems: (i) the spin-precession equations do not admit closed-form solutions for generic systems; (ii) the SPA fails catastrophically. Presently there is no general solution to the first ...
Mergers of black-hole binaries with aligned spins: Waveform characteristics
Kelly, Bernard J; Boggs, William D; McWilliams, Sean T; Centrella, Joan
2011-01-01
We conduct a descriptive analysis of the multipolar structure of gravitational-radiation waveforms from equal-mass aligned-spin mergers, following an approach first presented in the complementary context of nonspinning black holes of varying mass ratio [Baker et al., Phys. Rev. D 78:044046 (2008)]. We find that, as with the nonspinning mergers, the dominant waveform mode phases evolve together in lock-step through inspiral and merger, supporting the previous waveform description in terms of an adiabatically rigid rotator driving gravitational-wave emission -- an implicit rotating source (IRS). We further apply the late-time merger-ringdown model for the rotational frequency introduced in Baker et al. (2008), along with an improved amplitude model appropriate for the dominant (2,+/- 2) modes. This provides a quantitative description of the merger-ringdown waveforms, and suggests that the major features of these waveforms can be described with reference only to the intrinsic parameters associated with the state...
Carotid arterial blood pressure waveform monitoring using a portable ultrasound system.
Joohyun Seo; Pietrangelo, Sabino J; Hae-Seung Lee; Sodini, Charles G
2015-08-01
This work presents a non-invasive arterial blood pressure (ABP) waveform monitoring technique using ultrasound. A portable ultrasound system to excite ultrasound transducers and acquire data is designed with off-the-shelf components. The insonation angles are identified using a vector Doppler technique based on the cosine dependency of the Doppler signals. The pulse pressure of an estimated waveform at the left common carotid artery is compared to the standard sphygmomanometer measurement in a clinical test. The estimated carotid ABP waveform shows excellent agreement to the finger ABP waveform with expected discrepancy of the systolic peak shape due to different measurement sites. The proposed method also tracks slow blood pressure fluctuations. This validation on human subjects shows potential for a noninvasive blood pressure waveform monitoring device at central arterial sites.
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...
GLAS/ICESat L1B Global Waveform-based Range Corrections Data (HDF5) V033
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...
Estimating extracellular spike waveforms from CA1 pyramidal cells with multichannel electrodes.
Molden, Sturla; Moldestad, Olve; Storm, Johan F
2013-01-01
Extracellular (EC) recordings of action potentials from the intact brain are embedded in background voltage fluctuations known as the "local field potential" (LFP). In order to use EC spike recordings for studying biophysical properties of neurons, the spike waveforms must be separated from the LFP. Linear low-pass and high-pass filters are usually insufficient to separate spike waveforms from LFP, because they have overlapping frequency bands. Broad-band recordings of LFP and spikes were obtained with a 16-channel laminar electrode array (silicone probe). We developed an algorithm whereby local LFP signals from spike-containing channel were modeled using locally weighted polynomial regression analysis of adjoining channels without spikes. The modeled LFP signal was subtracted from the recording to estimate the embedded spike waveforms. We tested the method both on defined spike waveforms added to LFP recordings, and on in vivo-recorded extracellular spikes from hippocampal CA1 pyramidal cells in anaesthetized mice. We show that the algorithm can correctly extract the spike waveforms embedded in the LFP. In contrast, traditional high-pass filters failed to recover correct spike shapes, albeit produceing smaller standard errors. We found that high-pass RC or 2-pole Butterworth filters with cut-off frequencies below 12.5 Hz, are required to retrieve waveforms comparable to our method. The method was also compared to spike-triggered averages of the broad-band signal, and yielded waveforms with smaller standard errors and less distortion before and after the spike.
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.
Mechanical properties of concrete to cyclic uniaxial tensile loading using variable waveforms
Indian Academy of Sciences (India)
YUZHI CHEN; XUDONG CHEN; JINGWU BU
2017-01-01
The mechanical properties of concrete under cyclic tensile loading using square waveform, sine waveform and ramp waveform are studied. The experiments are performed on a closed-loop electro-hydraulic servo-controlled material testing system (MTS). The axial strain, dissipated energy per loading cycle, the damage evolution law and deformation modulus are mainly studied. The results show that the three-stageevolution law of axial strain and damage variable of concrete under ramp waveform and sine waveform are more obvious than those under the square waveform. The dissipated energy changes at different stages of fatigue life.At the beginning and end of the fatigue life, the rate of dissipated energy is higher than that at the medium stage of the fatigue time, which is attributed to the formation of cracks. The evolution of deformation modulus of concrete subjected to cyclic tensile loading using three loading waveforms also shows three stages: fast increase in the damage—increase at a slow constant rate—and accelerated increase in damage until failure.
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
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
Sano, Michael B.; Fan, Richard E.; Xing, Lei
2017-01-01
Irreversible electroporation (IRE) is a promising non-thermal treatment for inoperable tumors which uses short (50–100 μs) high voltage monopolar pulses to disrupt the membranes of cells within a well-defined volume. Challenges with IRE include complex treatment planning and the induction of intense muscle contractions. High frequency IRE (H-FIRE) uses bursts of ultrashort (0.25–5 μs) alternating polarity pulses to produce more predictable ablations and alleviate muscle contractions associated with IRE. However, H-FIRE generally ablates smaller volumes of tissue than IRE. This study shows that asymmetric H-FIRE waveforms can be used to create ablation volumes equivalent to standard IRE treatments. Lethal thresholds (LT) of 505 V/cm and 1316 V/cm were found for brain cancer cells when 100 μs IRE and 2 μs symmetric H-FIRE waveforms were used. In contrast, LT as low as 536 V/cm were found for 2 μs asymmetric H-FIRE waveforms. Reversible electroporation thresholds were 54% lower than LTs for symmetric waveforms and 33% lower for asymmetric waveforms indicating that waveform symmetry can be used to tune the relative sizes of reversible and irreversible ablation zones. Numerical simulations predicted that asymmetric H-FIRE waveforms are capable of producing ablation volumes which were 5.8–6.3x larger than symmetric H-FIRE waveforms indicating that in vivo investigation of asymmetric waveforms is warranted.
Sawhorse waveform voltammetry for selective detection of adenosine, ATP, and hydrogen peroxide.
Ross, Ashley E; Venton, B Jill
2014-08-05
Fast-scan cyclic voltammetry (FSCV) is an electrochemistry technique which allows subsecond detection of neurotransmitters in vivo. Adenosine detection using FSCV has become increasingly popular but can be difficult because of interfering agents which oxidize at or near the same potential as adenosine. Triangle shaped waveforms are traditionally used for FSCV, but modified waveforms have been introduced to maximize analyte sensitivity and provide stability at high scan rates. Here, a modified sawhorse waveform was used to maximize the time for adenosine oxidation and to manipulate the shapes of cyclic voltammograms (CVs) of analytes which oxidize at the switching potential. The optimized waveform consists of scanning at 400 V/s from -0.4 to 1.35 V and holding briefly for 1.0 ms followed by a ramp back down to -0.4 V. This waveform allows the use of a lower switching potential for adenosine detection. Hydrogen peroxide and ATP also oxidize at the switching potential and can interfere with adenosine measurements in vivo; however, their CVs were altered with the sawhorse waveform and they could be distinguished from adenosine. Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP. In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1. The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.
Progress toward post-adiabatic EMRI waveforms using the multiscale approximation
Moxon, Jordan; Flanagan, Eanna; Hinderer, Tanja; Pound, Adam
2017-01-01
I present updates on an analytic approximation method for use in computing orbits and waveforms for Extreme Mass Ratio Inspirals (EMRIs). EMRIs are of particular interest for future space-based gravitational wave detectors, such as (e)LISA. Such gravitational wave detectors will depend on precise predictions of the waveform to take full advantage of the available data. The analytic approximation method for which I present new developments is based on second order self force methods, improved by use of the two-timescale approximation method. Once complete, this method will allow efficient computations of highly accurate EMRI waveforms.
Mikóczi, Balázs; Forgács, Péter; Vasúth, Mátyás
2015-08-01
The inspiral and merger of supermassive black hole binary systems with high orbital eccentricity are among the promising sources of the advanced gravitational wave observatories. In this paper we compute gravitational waveforms in the frequency domain to the first post-Newtonian order, emitted by compact binary systems with arbitrary eccentricity. Our results are fully analytic, ready-to-use expressions of the waveforms in terms of a suitable generalization of Hansen coefficients known from celestial mechanics. Secular terms induced by the eccentricity are eliminated by introducing a suitable phase shift. The obtained waveforms have a rather simple structure, greatly facilitating their use in applications.
Closed form of optimal current waveform for class-F PA up to fourth harmonic
Indian Academy of Sciences (India)
Anamarija Juhas; Ladislav A Novak
2015-04-01
In this paper, rigorous analytical derivation of the coefficients of optimal current waveform for class-F power amplifier (PA) up to fourth harmonic (dc, 1st, 2nd and 4th harmonic) is presented. The coefficients of the optimal current waveform along with related maximum attainable efficiency are provided in closed form. The results obtained are also of interest for the inverse class-F, in the case when optimal voltage waveform consists of dc, 1st, 2nd and 4th harmonic.
Littenberg, Tyson; LIGO Scientific Collaboration
2016-03-01
The BayesWave burst detection and characterization algorithm was used during the first Advanced LIGO observing run as a follow-up analysis to candidate transient gravitational wave events. Among the BayesWave data products are robust reconstructed waveforms and probability density functions for metrics such as duration, bandwidth, etc. used to characterize the waveforms. We will demonstrate how the waveform metrics can be used to infer the astrophysical nature of a gravitational wave source, and present the status of BayesWave studies from the first advanced LIGO observing run.
Matched-filtering and parameter estimation of ringdown waveforms
Berti, Emanuele; Cardoso, Vitor; Cavaglia, Marco
2007-01-01
Using recent results from numerical relativity simulations of non-spinning binary black hole mergers we revisit the problem of detecting ringdown waveforms and of estimating the source parameters, considering both LISA and Earth-based interferometers. We find that Advanced LIGO and EGO could detect intermediate-mass black holes of mass up to about 1000 solar masses out to a luminosity distance of a few Gpc. For typical multipolar energy distributions, we show that the single-mode ringdown templates presently used for ringdown searches in the LIGO data stream can produce a significant event loss (> 10% for all detectors in a large interval of black hole masses) and very large parameter estimation errors on the black hole's mass and spin. We estimate that more than 10^6 templates would be needed for a single-stage multi-mode search. Therefore, we recommend a "two stage" search to save on computational costs: single-mode templates can be used for detection, but multi-mode templates or Prony methods should be use...
Efficient scattering angle filtering for Full waveform inversion
Alkhalifah, Tariq Ali
2015-08-19
Controlling the scattering angles between the state and the adjoint variables for the energy admitted into an inversion gradient or an image can help improve these functions for objectives in full waveform inversion (FWI) or seismic imaging. However, the access of the scattering angle information usually requires an axis extension that could be costly, especially in 3D. For the purpose of a scattering angle filter, I develop techniques that utilize the mapping nature (no domain extension) of the filter for constant-velocity background models to interpolate between such filtered gradients using the actual velocity. The concept has well known roots in the application of phase-shift-plus-interpolation utilized commonly in the downward continuation process. If the difference between the minimum and maximum velocity of the background medium is large, we obtain filtered gradients corresponding to more constant velocity backgrounds and use linear interpolation between such velocities. The accuracy of this approximation for the Marmousi model gradient demonstrates the e ectiveness of the approach.
Binaural masking level differences with a variety of waveforms.
Henning, G B; Gaskell, H
1981-05-01
Binaural masking level differences (BMLDs) were measured in a standard two-interval forced-choice detection task. The signals were (a) 250-ms bursts of pure tones, (b) amplitude-modulated waveforms with either high- or low-frequency carriers, and (c) 20-microseconds clicks. The pure tones and clicks were presented either eith zero phase difference between the ears or with an 180 degrees phase difference between the ears: the AM tones were presented in several different interaural phase conditions, only some of which lead to changes in the apparent location of the signal source. The noise against which all the signals were detected was white, broad-band, and identical at the ears. BMLDs were invariably small with high-frequency signals and with clicks. Although the magnitude of the BMLD obtained with low-frequency signals appeared to be related to the Observers' ability to lateralize the signal, there is a simpler explanation based on the assumption that detection of low-frequency AM signals is determined by independent detection of its components.
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.
D'' beneath the Arctic from inversion of shear waveforms
Kawai, Kenji; Geller, Robert J.; Fuji, Nobuaki
2007-11-01
The structure of the D'' region beneath the Arctic has not previously been studied in detail. Using waveform inversion, we find that the average S-wave velocity in D'' beneath the Arctic is about 0.04 km/s higher than PREM, which is consistent with the existence of post-perovskite (ppv) in D''. It is difficult to strongly constrain the fine structure of S-velocity within D'' due to the small number of stations at epicentral distances Δ weighting those stations heavily in the inversion, we show that the data suggest the existence of high S-velocity in the upper half of D'' and low S-velocity in the lower half, consistent with the possibility of a double crossing (ppv -> pv reverse phase transition) within D''. We conduct a computational experiment to show that resolution of the velocity structure within D'' could be significantly improved by temporary installation of a portable array of seismographs in northern Canada, which would greatly increase the number of stations in the range 70° < Δ < 90°.
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.
Attosecond Steering of Electrons with Optimised Strong Field Waveforms
Haessler, S; Fan, G; Witting, T; Squibb, R; Chipperfield, L; Zaïr, A; Andriukaitis, G; Pugžlys, A; Tisch, J W G; Marangos, J P; Baltuška, A
2013-01-01
Quasi-free field driven electron trajectories are a key element of strong-field dynamics. Upon recollision with the parent ion, the energy transferred from the field to the electron may be released as attosecond duration XUV emission1,2 in the process of high harmonic generation (HHG). The conventional sinusoidal driver fields set limitations on the maximum value of this energy transfer, and it has been predicted that this limit can be significantly exceeded by an appropriately ramped-up cycle-shape3.Here, we present an experimental realization of such cycle-shaped waveforms and demonstrate control of the HHG process on the single-atom quantum level via attosecond steering of the electron trajectories. With our optimized optical cycles, we boost the field-ionization launching the electron trajectories, increase the subsequent field-to-electron energy transfer, and reduce the trajectory duration, to obtain greatly enhanced HHG efficiency as well as spectral extension compared to sinusoidal drivers. This applic...
Full waveform inversion with extrapolated low frequency data
Li, Yunyue Elita
2016-01-01
The availability of low frequency data is an important factor in the success of full waveform inversion (FWI) in the acoustic regime. The low frequencies help determine the kinematically relevant, low-wavenumber components of the velocity model, which are in turn needed to avoid convergence of FWI to spurious local minima. However, acquiring data below 2 or 3 Hz from the field is a challenging and expensive task. In this paper we explore the possibility of synthesizing the low frequencies computationally from high-frequency data, and use the resulting prediction of the missing data to seed the frequency sweep of FWI. As a signal processing problem, bandwidth extension is a very nonlinear and delicate operation. It requires a high-level interpretation of bandlimited seismic records into individual events, each of which is extrapolable to a lower (or higher) frequency band from the non-dispersive nature of the wave propagation model. We propose to use the phase tracking method for the event separation task. The...
Velocity Building by Reflection Waveform Inversion without Cycle-skipping
Guo, Q.
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.
Scattering-angle based filtering of the waveform inversion gradients
Alkhalifah, Tariq Ali
2014-11-22
Full waveform inversion (FWI) requires a hierarchical approach to maneuver the complex non-linearity associated with the problem of velocity update. In anisotropic media, the non-linearity becomes far more complex with the potential trade-off between the multiparameter description of the model. A gradient filter helps us in accessing the parts of the gradient that are suitable to combat the potential non-linearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which the low scattering angle of the gradient update is initially muted out in the FWI implementation, in what we may refer to as a scattering angle continuation process. The result is a low wavelength update dominated by the transmission part of the update gradient. In this case, even 10 Hz data can produce vertically near-zero wavenumber updates suitable for a background correction of the model. Relaxing the filtering at a later stage in the FWI implementation allows for smaller scattering angles to contribute higher-resolution information to the model. The benefits of the extended domain based filtering of the gradient is not only it\\'s ability in providing low wavenumber gradients guided by the scattering angle, but also in its potential to provide gradients free of unphysical energy that may correspond to unrealistic scattering angles.
A complete waveform model for compact binaries on eccentric orbits
Huerta, E A; Agarwal, Bhanu; George, Daniel; Schive, Hsi-Yu; Pfeiffer, Harald P; Chu, Tony; Boyle, Michael; Hemberger, Daniel A; Kidder, Lawrence E; Scheel, Mark A; Szilagyi, Bela
2016-01-01
We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are non-spinning, and which evolve on orbits with low to moderate eccentricity. The inspiral evolution is described using third order post-Newtonian equations both for the equations of motion of the binary, and its far-zone radiation field. This latter component also includes instantaneous, tails and tails-of-tails contributions, and a contribution due to non-linear memory. This framework reduces to the post-Newtonian approximant $\\texttt{TaylorT4}$ at third post-Newtonian order in the zero eccentricity limit. To improve phase accuracy, we also incorporate higher-order post-Newtonian corrections for the energy flux of quasi-circular binaries and gravitational self-force corrections to the binding energy of compact binaries. This enhanced prescription for the inspiral evolution is combined with a fully analytical prescription for the merger-ringdown evolution constructed using a c...
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.
Accurate and efficient waveforms for compact binaries on eccentric orbits
Huerta, E A; McWilliams, Sean T; O'Shaughnessy, Richard; Yunes, Nicolas
2014-01-01
Compact binaries that emit gravitational waves in the sensitivity band of ground-based detectors can have non-negligible eccentricities just prior to merger, depending on the formation scenario. We develop a purely analytic, frequency-domain model for gravitational waves emitted by compact binaries on orbits with small eccentricity, which reduces to the quasi-circular post-Newtonian approximant TaylorF2 at zero eccentricity and to the post-circular approximation of Yunes et al. (2009) at small eccentricity. Our model uses a spectral approximation to the (post-Newtonian) Kepler problem to model the orbital phase as a function of frequency, accounting for eccentricity effects up to ${\\cal{O}}(e^8)$ at each post-Newtonian order. Our approach accurately reproduces an alternative time-domain eccentric waveform model for eccentricities $e\\in [0, 0.4]$ and binaries with total mass less than 12 solar masses. As an application, we evaluate the signal amplitude that eccentric binaries produce in different networks of e...
Conditioning the full-waveform inversion gradient to welcome anisotropy
Alkhalifah, Tariq Ali
2015-04-23
Multiparameter full-waveform inversion (FWI) suffers from complex nonlinearity in the objective function, compounded by the eventual trade-off between the model parameters. A hierarchical approach based on frequency and arrival time data decimation to maneuver the complex nonlinearity associated with this problem usually falls short in anisotropic media. In place of data decimation, I use a model gradient filter approach to access the parts of the gradient more suitable to combat the potential nonlinearity and parameter trade-off. The filter is based on representing the gradient in the time-lag normalized domain, in which small scattering-angles of the gradient update are initially muted out. The model update hierarchical filtering strategy include applying varying degrees of filtering to the different anisotropic parameter updates, a feature not easily accessible to simple data decimation. Using FWI and reflection-based FWI, when the modeled data are obtained with the single-scattering theory, allows access to additional low model wavenumber components. Combining such access to wavenumbers with scattering-angle filters applied to the individual parameter gradients allows for multiple strategies to avoid complex FWI nonlinearity as well as the parameter trade-off.
Waveform inversion of mantle Love waves: The born seismogram approach
Tanimoto, T.
1983-01-01
Normal mode theory, extended to the slightly laterally heterogeneous Earth by the first-order Born approximation, is applied to the waveform inversion of mantle Love waves (200-500 sec) for the Earth's lateral heterogeneity at l=2 and a spherically symmetric anelasticity (Q sub mu) structure. The data are from the Global Digital Seismograph Network (GDSN). The l=2 pattern is very similar to the results of other studies that used either different methods, such as phase velocity measurements and multiplet location measurements, or a different data set, such as mantle Rayleigh waves from different instruments. The results are carefully analyzed for variance reduction and are most naturally explained by heterogeneity in the upper 420 km. Because of the poor resolution of the data set for the deep interior, however, a fairly large heterogeneity in the transition zones, of the order of up to 3.5% in shear wave velocity, is allowed. It is noteworthy that Love waves of this period range can not constrain the structure below 420 km and thus any model presented by similar studies below this depth are likely to be constrained by Rayleigh waves (spheroidal modes) only.
Waveform inversion of mantle Love waves - The Born seismogram approach
Tanimoto, T.
1984-01-01
Normal mode theory, extended to the slightly laterally heterogeneous earth by the first-order Born approximation, is applied to the waveform inversion of mantle Love waves (200-500 sec) for the earth's lateral heterogeneity at l = 2 and a spherically symmetric anelasticity (Q sub mu) structure. The data are from the Global Digital Seismograph Network (GDSN). The l = 2 pattern is very similar to the results of other studies that used either different methods, such as phase velocity measurements and multiplet location measurements, or a different data set, such as mantle Rayleigh waves from different instruments. The results are carefully analyzed for variance reduction and are most naturally explained by heterogeneity in the upper 420 km. Because of the poor resolution of the data set for the deep interior, however, a fairly large heterogeneity in the transition zones, of the order of up to 3.5 percent in shear wave velocity, is allowed. It is noteworthy that Love waves of this period range can not constrain the structure below 420 km and thus any model presented by similar studies below this depth are likely to be constrained by Rayleigh waves (spheroidal modes) only.
Vennin, Samuel; Mayer, Alexia; Li, Ye; Fok, Henry; Clapp, Brian; Alastruey, Jordi; Chowienczyk, Phil
2015-09-01
Estimation of aortic and left ventricular (LV) pressure usually requires measurements that are difficult to acquire during the imaging required to obtain concurrent LV dimensions essential for determination of LV mechanical properties. We describe a novel method for deriving aortic pressure from the aortic flow velocity. The target pressure waveform is divided into an early systolic upstroke, determined by the water hammer equation, and a diastolic decay equal to that in the peripheral arterial tree, interposed by a late systolic portion described by a second-order polynomial constrained by conditions of continuity and conservation of mean arterial pressure. Pulse wave velocity (PWV, which can be obtained through imaging), mean arterial pressure, diastolic pressure, and diastolic decay are required inputs for the algorithm. The algorithm was tested using 1) pressure data derived theoretically from prespecified flow waveforms and properties of the arterial tree using a single-tube 1-D model of the arterial tree, and 2) experimental data acquired from a pressure/Doppler flow velocity transducer placed in the ascending aorta in 18 patients (mean ± SD: age 63 ± 11 yr, aortic BP 136 ± 23/73 ± 13 mmHg) at the time of cardiac catheterization. For experimental data, PWV was calculated from measured pressures/flows, and mean and diastolic pressures and diastolic decay were taken from measured pressure (i.e., were assumed to be known). Pressure reconstructed from measured flow agreed well with theoretical pressure: mean ± SD root mean square (RMS) error 0.7 ± 0.1 mmHg. Similarly, for experimental data, pressure reconstructed from measured flow agreed well with measured pressure (mean RMS error 2.4 ± 1.0 mmHg). First systolic shoulder and systolic peak pressures were also accurately rendered (mean ± SD difference 1.4 ± 2.0 mmHg for peak systolic pressure). This is the first noninvasive derivation of aortic pressure based on fluid dynamics (flow and wave speed) in the
Geosat Geodetic Mission Waveform Data Records (WDR) for May, 1985 (NODC Accession 0002365)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Canopy Height Estimation by Characterizing Waveform LiDAR Geometry Based on Shape-Distance Metric
National Research Council Canada - National Science Library
Ariel L. Salas, Eric; M. Henebry, Geoffrey
2016-01-01
.... Unlike any existing methods, we illustrate how the new Moment Distance (MD) framework can characterize the canopy height based on the geometry and return power of the LiDAR waveform without having to go through curve modeling processes...
Geosat Exact Repeat Mission Waveform Data Records (WDR) (NODC Accession 0061150)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains waveform data records (WDRs) from the US Navy Geodetic Satellite (GEOSAT) Exact Repeat Mission (ERM) for the time period of November 08,...
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.
Xu, Da; Ryan, Kathy L; Rickards, Caroline A; Zhang, Guanqun; Convertino, Victor A; Mukkamala, Ramakrishna
2010-01-01
Pulse wave velocity (PWV) is a marker of arterial stiffness and may permit continuous, non-invasive, and cuff-less monitoring of blood pressure. Here, robust PWV estimation was sought by application of system identification to proximal and distal arterial waveforms. In this approach, the system that optimally couples the proximal waveform to the distal waveform is identified, and the time delay of this system is then used to calculate PWV. To demonstrate proof-of-concept, a standard identification technique was applied to non-invasive impedance cardiography and peripheral arterial blood pressure waveforms from six humans subjected to progressive reductions in central blood volume induced by lower body negative pressure. This technique estimated diastolic pressure with an overall root-mean-squared-error of 5.2 mmHg. For comparison, the conventional detection method for estimating PWV yielded a corresponding error of 8.3 mmHg.
Geosat Geodetic Mission Waveform Data Records (WDR) for June, 1985 (NODC Accession 0002551)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for April, 1986 (NODC Accession 0002561)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Directory of Open Access Journals (Sweden)
Kirk H. Shelley
2012-02-01
Full Text Available The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform.
Geosat Geodetic Mission Waveform Data Records (WDR) for August, 1986 (NODC Accession 0002565)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for January, 1986 (NODC Accession 0002558)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for October, 1985 (NODC Accession 0002555)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for September, 1985 (NODC Accession 0002554)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for November, 1985 (NODC Accession 0002556)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Alian, Aymen A; Shelley, Kirk H
2012-01-01
The photoplethysmographic waveform sits at the core of the most used, and arguably the most important, clinical monitor, the pulse oximeter. Interestingly, the pulse oximeter was discovered while examining an artifact during the development of a noninvasive cardiac output monitor. This article will explore the response of the pulse oximeter waveform to various modes of ventilation. Modern digital signal processing is allowing for a re-examination of this ubiquitous signal. The effect of ventilation on the photoplethysmographic waveform has long been thought of as a source of artifact. The primary goal of this article is to improve the understanding of the underlying physiology responsible for the observed phenomena, thereby encouraging the utilization of this understanding to develop new methods of patient monitoring. The reader will be presented with a review of respiratory physiology followed by numerous examples of the impact of ventilation on the photoplethysmographic waveform.
Geosat Geodetic Mission Waveform Data Records (WDR) for August, 1985 (NODC Accession 0002553)
National Oceanic and Atmospheric Administration, Department of Commerce — his accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for July, 1985 (NODC Accession 0002552)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for April, 1985 (NODC Accession 0002364)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for February, 1986 (NODC Accession 0002559)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Telenkov, Sergey A; Alwi, Rudolf; Mandelis, Andreas
2013-10-01
Photoacoustic (PA) imaging of biological tissues using laser diodes instead of conventional Q-switched pulsed systems provides an attractive alternative for biomedical applications. However, the relatively low energy of laser diodes operating in the pulsed regime, results in generation of very weak acoustic waves, and low signal-to-noise ratio (SNR) of the detected signals. This problem can be addressed if optical excitation is modulated using custom waveforms and correlation processing is employed to increase SNR through signal compression. This work investigates the effect of the parameters of the modulation waveform on the resulting correlation signal and offers a practical means for optimizing PA signal detection. The advantage of coherent signal averaging is demonstrated using theoretical analysis and a numerical model of PA generation. It was shown that an additional 5-10 dB of SNR can be gained through waveform engineering by adjusting the parameters and profile of optical modulation waveforms.
Mikóczi, Balázs; Vasúth, Mátyás
2015-01-01
The inspiral and merger of supermassive black hole binary systems with high orbital eccentricity are among the promising sources of the advanced gravitational wave observatories. In this paper we derive analytic ready-to-use first post-Newtonian eccentric waveform in Fourier domain with the use of Hansen coefficients. Introducing generic perturbations of celestial mechanics we have generalized the Hansen expansion to the first post-Newtonian order which are then used to express the waveforms. Taking into account the high eccentricity of the orbit leads to the appearance of secular terms in the waveform which are eliminated with the introduction of a phase shift. The waveforms have a systematic structure and as our main result these are expressed in a tabular form.
Gravitational waveforms for neutron star binaries from binary black hole simulations
Barkett, Kevin; Haas, Roland; Ott, Christian D; Bernuzzi, Sebastiano; Brown, Duncan A; Szilágyi, Béla; Kaplan, Jeffrey D; Lippuner, Jonas; Muhlberger, Curran D; Foucart, Francois; Duez, Matthew D
2015-01-01
Gravitational waves from binary neutron star (BNS) and black-hole/neutron star (BHNS) inspirals are primary sources for detection by the Advanced Laser Interferometer Gravitational-Wave Observatory. The tidal forces acting on the neutron stars induce changes in the phase evolution of the gravitational waveform, and these changes can be used to constrain the nuclear equation of state. Current methods of generating BNS and BHNS waveforms rely on either computationally challenging full 3D hydrodynamical simulations or approximate analytic solutions. We introduce a new method for computing inspiral waveforms for BNS/BHNS systems by adding the post-Newtonian (PN) tidal effects to full numerical simulations of binary black holes (BBHs), effectively replacing the non-tidal terms in the PN expansion with BBH results. Comparing a waveform generated with this method against a full hydrodynamical simulation of a BNS inspiral yields a phase difference of $<1$ radian over $\\sim 15$ orbits. The numerical phase accuracy ...
Johnson-McDaniel, Nathan; Ghosh, Abhirup; Ghosh, Archisman; Samajdar, Anuradha; Ajith, Parameswaran; Del Pozzo, Walter
2016-03-01
We describe a variety of self-consistent modifications of the effective-one-body framework that yield kludge modified gravity inspiral-merger-ringdown (IMR) waveforms. These waveforms do not correspond to any particular modified theory of gravity, but offer parametrized deviations from general relativity in various regimes. They can thus be used to test the performance of various gravitational wave tests of general relativity (GR). As an example, we introduce the IMR consistency test, which tests for consistency between the estimations of the final mass and spin from the inspiral and merger-ringdown portions of a binary black hole waveform. We show that for reasonable source parameters and SNRs in Advanced LIGO, this test is able to detect a deviation from GR with high confidence for certain modifications of the GR energy flux that are not constrained by observations of the double pulsar. We also consider the performance of a parameterized test of GR on these kludge modified gravity waveforms.
Seafloor classification using echo- waveforms: A method employing hybrid neural network architecture
Digital Repository Service at National Institute of Oceanography (India)
Chakraborty, B.; Mahale, V.; DeSouza, C.; Das, P.
This letter presents seafloor classification study results of a hybrid artificial neural network architecture known as learning vector quantization. Single beam echo-sounding backscatter waveform data from three different seafloors of the western...
Geosat Geodetic Mission Waveform Data Records (WDR) for July, 1986 (NODC Accession 0002564)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Geosat Geodetic Mission Waveform Data Records (WDR) for March, 1985 (NODC Accession 0002363)
National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains one month of waveform data records (WDRs) from the GEOSAT Geodetic Mission (GM) and(or) Exact Repeat Mission (ERM) for the time period of...
Wang, Kun; Anis, Fatima; Li, Cuiping; Duric, Neb; Anastasio, Mark A
2015-01-01
Ultrasound computed tomography (USCT) holds great promise for improving the detection and management of breast cancer. Because they are based on the acoustic wave equation, waveform inversion-based reconstruction methods can produce images that possess improved spatial resolution properties over those produced by ray-based methods. However, waveform inversion methods are computationally demanding and have not been applied widely in USCT breast imaging. In this work, source encoding concepts are employed to develop an accelerated USCT reconstruction method that circumvents the large computational burden of conventional waveform inversion methods. This method, referred to as the waveform inversion with source encoding (WISE) method, encodes the measurement data using a random encoding vector and determines an estimate of the sound speed distribution by solving a stochastic optimization problem by use of a stochastic gradient descent algorithm. Both computer-simulation and experimental phantom studies are conduc...
"Complete" gravitational waveforms for black-hole binaries with non-precessing spins
Ajith, P; Husa, S; Chen, Y; Brügmann, B; Dorband, N; Müller, D; Ohme, F; Pollney, D; Reisswig, C; Santamaria, L; Seiler, J
2009-01-01
We present the first analytical inspiral-merger-ringdown gravitational waveforms from black-hole (BH) binaries with non-precessing spins. By matching a post-Newtonian description of the inspiral to a set of numerical calculations performed in full general relativity, we obtain a waveform family with a conveniently small number of physical parameters. The physical content of these waveforms includes the "orbital hang-up" effect, when BHs are spinning rapidly along the direction of the orbital angular momentum. These waveforms will allow us to detect a larger parameter space of BH binary coalescence, to explore various scientific questions related to GW astronomy, and could dramatically improve the expected detection rates of GW detectors.
Kanno, Atsushi; Tien Dat, Pham; Kuri, Toshiaki; Hosako, Iwao; Kawanishi, Tetsuya; Yoshida, Yuki; Kitayama, Ken-ichi
2015-01-01
In this paper, we describe seamless networks based on millimeter and terahertz wave radio links using waveform transfer over optical fibers. Coherent optical transceivers with digital signal processing provide transmission impairment compensation in both optical and radio sections, where devices for the signal processing are implemented at edges of the links. Waveforms, which include the modulation formats, the symbol rates, etc., are maintained in the entire links, to reduce transmission latency and energy consumption in the network.
Pulsed Field Waveforms for Magnetization of HTS Gd-Ba-Cu-O Bulk Magnets
Energy Technology Data Exchange (ETDEWEB)
Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Matsuzaki, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Morita, E [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Sakashita, H [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Harada, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Ogata, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Kimura, Y [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Miki, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Kitano, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)
2006-06-01
Progress in pulse magnetization technique for high-temperature superconductor bulks of melt-textured RE-Ba-Cu-O with large diameter is important for the realization of power applications. We studied the pulsed power source and pulsed field waveforms to enhance to improve the magnetization properties for Gd-Ba-Cu-O bulk. The risetime and duration of pulse waveform effectively varied distribution of magnetic flux.
Fast Real-Time Digital Monitoring of Signal Waveform Quality Using an FPGA
S. Talha Ahsan; Hugh McCann
2013-01-01
The real-time or offline monitoring of signal waveform quality is important in many applications, such as electrical power quality monitoring, measurement of waveform distortion in recording systems and monitoring of electrical excitation in active measurement systems. This study presents a signal monitoring system based on a Field-Programmable Gate Array (FPGA), which receives digitized samples of analogue voltage developed across a sense resistor and performs signal processing in real time....
On the application of neural networks to the classification of phase modulated waveforms
Buchenroth, Anthony; Yim, Joong Gon; Nowak, Michael; Chakravarthy, Vasu
2017-04-01
Accurate classification of phase modulated radar waveforms is a well-known problem in spectrum sensing. Identification of such waveforms aids situational awareness enabling radar and communications spectrum sharing. While various feature extraction and engineering approaches have sought to address this problem, the use of a machine learning algorithm that best utilizes these features is becomes foremost. In this effort, a comparison of a standard shallow and a deep learning approach are explored. Experiments provide insights into classifier architecture, training procedure, and performance.
Very long-period GPS waveforms. What can GPS bring to Earth seismic velocity models?
Kelevitz, K.; Houlie, N.; Nissen-Meyer, T.; Boschi, L.; Giardini, D.; Rothacher, M.
2014-12-01
It is now admitted that high rate GPS observations can provide reliable surface displacement waveforms. For long-period (T > 5s) transients, it was shown that GPS and seismometer (STS-1) displacements are in agreement at least for vertical component [Houlié et al., 2011]. We propose here to supplement existing long-period seismic networks with high rate (>= 1Hz) GPS data in order to improve the resolution of global seismic velocity models. We aim at extending the use of GPS measurements beyond the range of STS-1 in the low frequency end (T>1000s). We present the results of the processing of 1Hz GPS records of the Hokkaido, Sumatra and Tohoku earthquakes (25th of September, 2003, Mw = 8.3; 26th of December, 2004, Mw = 8.9; 11th of March, 2011, Mw = 9.1, respectively). 3D waveforms phase time-series have been used to recover the ground motion histories at the GPS sites. Through the better resolution of inversion of the GPS phase observations, we determine displacement waveforms of periods ranging from 30 seconds to 1300 seconds for a selection of sites. We compare inverted GPS waveforms with STS-1 waveforms, superconducting gravity waveforms and synthetic waveforms computed using 3D global wave propagation with SPECFEM. We find that the GPS waveforms are in agreement with the SPECFEM synthetic data and are able to fill the period-gap between the broadband seismometer STS-1 data and the normal mode period range detected by the superconducting gravimeters. References: Houlié, N., G. Occhipinti, T. Blanchard, N. Shapiro, P. Lognonne, and M. Murakami (2011), New approach to detect seismic surface waves in 1Hz-sampled GPS time series, Scientific reports, 1, 44.
Revealing time-unlocked brain activity from MEG measurements by common waveform estimation.
Directory of Open Access Journals (Sweden)
Yusuke Takeda
Full Text Available Brain activities related to cognitive functions, such as attention, occur with unknown and variable delays after stimulus onsets. Recently, we proposed a method (Common Waveform Estimation, CWE that could extract such brain activities from magnetoencephalography (MEG or electroencephalography (EEG measurements. CWE estimates spatiotemporal MEG/EEG patterns occurring with unknown and variable delays, referred to here as unlocked waveforms, without hypotheses about their shapes. The purpose of this study is to demonstrate the usefulness of CWE for cognitive neuroscience. For this purpose, we show procedures to estimate unlocked waveforms using CWE and to examine their role. We applied CWE to the MEG epochs during Go trials of a visual Go/NoGo task. This revealed unlocked waveforms with interesting properties, specifically large alpha oscillations around the temporal areas. To examine the role of the unlocked waveform, we attempted to estimate the strength of the brain activity of the unlocked waveform in various conditions. We made a spatial filter to extract the component reflecting the brain activity of the unlocked waveform, applied this spatial filter to MEG data under different conditions (a passive viewing, a simple reaction time, and Go/NoGo tasks, and calculated the powers of the extracted components. Comparing the powers across these conditions suggests that the unlocked waveforms may reflect the inhibition of the task-irrelevant activities in the temporal regions while the subject attends to the visual stimulus. Our results demonstrate that CWE is a potential tool for revealing new findings of cognitive brain functions without any hypothesis in advance.
Garth, Thomas; Rietbrock, Andreas; Hicks, Steve; Fuenzalida Velasco, Amaya; Casarotti, Emanuele; Spinuso, Alessandro
2015-04-01
The VERCE platform is an online portal that allows full waveform simulations to be run for any region where a suitable velocity model exists. We use this facility to simulate the waveforms from aftershock earthquakes from the 2014 Pisagua earthquake, and 2010 Maule earthquake that occurred at the subduction zone mega thrust in Northern and Central Chile respectively. Simulations are performed using focal mechanisms from both global earthquake catalogues, and regional earthquake catalogues. The VERCE platform supports specFEM Cartesian, and simulations are run using meshes produced by CUBIT. The full waveform modelling techniques supported on the VERCE platform are used to test the validity of a number of subduction zone velocity models from the Chilean subduction zone. For the Maule earthquake we use a 2D and 3D travel time tomography model of the rupture area (Hicks et al. 2011; 2014). For the Pisagua earthquake we test a 2D/3D composite velocity model based on tomographic studies of the region (e.g. Husen et al. 2000, Contreyes-Reyes et al. 2012) and slab1.0 (Hayes et al. 2012). Focal mechanisms from the cGMT catalogue and local focal mechanisms calculated using ISOLA (e.g. Agurto et al. 2012) are used in the simulations. The waveforms produced are directly compared to waveforms recorded on the temporary deployment for the Maule earthquake aftershocks, and waveforms recorded on the IPOC network for the Pisagua earthquake aftershocks. This work demonstrates how the VERCE platform allows waveforms from the full 3D simulations to be easily produced, allowing us to quantify the validity of both the velocity model and the source mechanisms. These simulations therefore provide an independent test of the velocity models produced synthetically and by travel time tomography studies. Initial results show that the waveform is reasonably well reproduced in the 0.05 - 0.25 frequency band using a refined 3D travel time tomography, and locally calculated focal mechanisms.
Optimal design of basic pulse waveforms for THSS UWB radio systems
Institute of Scientific and Technical Information of China (English)
Jia Lin; Zhang Zhongzhao
2005-01-01
Ultrawide bandwidth (UWB) radio, a very promising technique carrying information in very short basic pulses, has properties that make it a viable candidate for short-range wireless communications. In this paper, several short-pulse waveforms based on Gaussian genetic monocycle as well as Gaussian pulse waveform, as candidates of basic UWB pulse waveforms, are firstly proposed and investigated. Their spectrum characteristics, bit transmission rate (BTR), and bit error rate (BER) performance in AWGN channel using time hopping spread spectrum (THSS) and pulse position modulation (PPM) are simulated and evaluated. The numerical results are compared and show that the basic pulse waveforms determine the spectrum characteristics of UWB signals and have much effect on the performance of UWB radio system. The performance of UWB radio system achieved by the proposed basic pulse waveforms is much better than that of UWB radio system realized by other used basic pulse waveforms under the uniform conditions. Also,the polarity of these short basic pulses does not affect the performance of UWB radio system.
On decomposing stimulus and response waveforms in event-related potentials recordings.
Yin, Gang; Zhang, Jun
2011-06-01
Event-related potentials (ERPs) reflect the brain activities related to specific behavioral events, and are obtained by averaging across many trial repetitions with individual trials aligned to the onset of a specific event, e.g., the onset of stimulus (s-aligned) or the onset of the behavioral response (r-aligned). However, the s-aligned and r-aligned ERP waveforms do not purely reflect, respectively, underlying stimulus (S-) or response (R-) component waveform, due to their cross-contaminations in the recorded ERP waveforms. Zhang [J. Neurosci. Methods, 80, pp. 49-63, 1998] proposed an algorithm to recover the pure S-component waveform and the pure R-component waveform from the s-aligned and r-aligned ERP average waveforms-however, due to the nature of this inverse problem, a direct solution is sensitive to noise that disproportionally affects low-frequency components, hindering the practical implementation of this algorithm. Here, we apply the Wiener deconvolution technique to deal with noise in input data, and investigate a Tikhonov regularization approach to obtain a stable solution that is robust against variances in the sampling of reaction-time distribution (when number of trials is low). Our method is demonstrated using data from a Go/NoGo experiment about image classification and recognition.
Flow patterns and shear stress waveforms in intracranial aneurysms: The effect of pulsatility
Sotiropoulos, Fotis; Le, Trung; Borazjani, Iman
2009-11-01
The wall shear stress on the dome of intracranial aneurysms has been hypothesized to be an important factor in aneurysm pathology and depends strongly on the hemodynamics inside the dome. The importance of patient-specific geometry on the hemodynamics of aneurysms has long been established but the significance of patient-specific inflow waveform is largely unexplored. In this work we seek to systematically investigate and quantify the effects of inflow waveform on aneurysm hemodynamics. We carry out high resolution numerical simulations for an anatomic intracranial aneurysm obtained from 3D rotational angiography (3DRA) data for various inflow waveforms. We show that both the vortex formation process and wall-shear stress dynamics on the aneurysm dome depend strongly on the characteristics of the inflow waveform. We also present preliminary evidence suggesting that a simple non-dimensional number (named the Aneurysm number), incorporating both geometry and inflow waveform effects, could be a good qualitative predictor of the general hemodynamic patterns that will arise in a given aneurysm geometry for a particular waveform.
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.
Energy Technology Data Exchange (ETDEWEB)
Altinkaya, Naime, E-mail: naimeto@yahoo.com [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Koc, Zafer, E-mail: koczafer@gmail.com [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Ulusan, Serife, E-mail: sulusan@hotmail.com [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Demir, Senay, E-mail: drsenaydemir@hotmail.com [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey); Gurel, Kamil, E-mail: kamilgurel@hotmail.com [Department of Radiology, Baskent University Medical School, Adana (Turkey); Baskent University, Faculty of Medicine, Department of Radiology, Adana (Turkey)
2011-07-15
Objective: This study was performed to determine the variations in Doppler waveforms and flow velocity during respiratory manoeuvres in healthy individuals with no liver disease. Materials and methods: In total, 100 individuals (75 women and 25 men) without known cardiac or liver disease were examined prospectively with duplex Doppler ultrasonography (US). We recorded the Doppler waveforms and peak systolic velocities (V{sub max}) of the middle hepatic vein during normal respiration, during breath-holding after quiet expiration and also during deep inspiration. Doppler waveforms are categorised as triphasic, biphasic or monophasic. Results: During normal respiration, hepatic venous waveforms were triphasic in 93% of subjects, monophasic in 6% and biphasic in 1%. During breath-holding after quiet expiration, the percentages were 91%, 6% and 3%, respectively. During deep inspiration, they were 80%, 18% and 2%, respectively. Although significant differences were noted between rates during deep inspiration and normal respiration, they were quite similar during normal respiration and breath-holding after quiet expiration (P < 0.05). The values of V{sub max} were significantly higher during normal respiration compared to quiet expiration and during quiet expiration compared to deep inspiration (P < 0.05). Conclusion: The velocities and waveforms of hepatic veins varied during respiratory manoeuvres. The status of respiration must be taken into consideration whilst examining the hepatic vein waveforms and velocities with duplex Doppler US.
A Generalized Algorithm Deriving Vegetation Height from ICESat/GLAS Waveforms
Green, G. M.; Ni-Meister, W.; Lee, S.
2010-12-01
A location-insensitive geometric algorithm for extracting vegetation height from ICESat/GLAS waveform data has recently been developed and validated in a deciduous broadleaf biome with promising results. The current study extends the validation to different biomes using globally-available input data. Airborne lidar was used to evaluate the accuracy of the height algorithm in boreal, chaparral, temperate/deciduous, arctic, and urban settings, in preparation for applying the algorithm globally. The model is dependent on surface slope and on the extent of the transmitted and received waveforms. Different sources of slope information (SRTM, NED, airborne lidar) were compared for their effects on the slope term of the model. Non-vegetated flat surfaces isolated the effect of the transmit waveform, and suggested adjustments to the corresponding term. Accuracy of the waveform extent was found to be dependent on the quality of shots used, and an algorithm for filtering noisy waveforms based on waveform shape was developed. The choice of digital elevation model affected the slope term, and we found that SRTM yielded usable results when compared to NED and small-footprint lidar.
Chen, Shun-Ping; Hu, Yuan-Ping
2015-05-01
This study investigated the value of analyzing spectral Doppler waveform patterns and measuring the peak reversed velocity (PRV) of the vertebral artery (VA) in predicting proximal severe subclavian artery (SA) stenosis and occlusion. Fifty-one patients with proximal SA stenosis were studied retrospectively. Based on the depth of the mid-systolic notch, the Doppler waveforms of the ipsilateral VA were divided into five subtypes (type I, n = 8; type II, n = 8; type III, n = 6; type IV, n = 13; and type V, n = 16). PRV was also measured. PRV receiver operating characteristic curves were constructed to obtain the best cutoff value for predicting severe SA stenosis or complete SA occlusion. The results indicated that both VA Doppler waveform and PRV were associated with the degree of SA stenosis (p waveform in the VA had similar accuracy in predicting SA occlusion (84.3%, 43/51). PRV was more accurate than VA waveforms in predicting severe SA stenosis (98%, 50/51 vs. 94.1%, 48/51). However, no significant differences between the two methods in predicting severe SA stenosis were observed (p = 0.84). Thus, with severe obstruction of the SA, typical Doppler waveform patterns of the VA could be observed. PRV is a helpful criterion in predicting severe stenosis and occlusion of the SA.
Connolly, Mark; He, Xing; Gonzalez, Nestor; Vespa, Paul; DiStefano, Joe; Hu, Xiao
2014-03-01
Due to the inaccessibility of the cranial vault, it is difficult to study cerebral blood flow dynamics directly. A mathematical model can be useful to study these dynamics. The model presented here is a novel combination of a one-dimensional fluid flow model representing the major vessels of the circle of Willis (CoW), with six individually parameterized auto-regulatory models of the distal vascular beds. This model has the unique ability to simulate high temporal resolution flow and velocity waveforms, amenable to pulse-waveform analysis, as well as sophisticated phenomena such as auto-regulation. Previous work with human patients has shown that vasodilation induced by CO2 inhalation causes 12 consistent pulse-waveform changes as measured by the morphological clustering and analysis of intracranial pressure algorithm. To validate this model, we simulated vasodilation and successfully reproduced 9 out of the 12 pulse-waveform changes. A subsequent sensitivity analysis found that these 12 pulse-waveform changes were most affected by the parameters associated with the shape of the smooth muscle tension response and vessel elasticity, providing insight into the physiological mechanisms responsible for observed changes in the pulse-waveform shape.
Phase-modulated waveform design for extended target detection in the presence of clutter.
Gong, Xuhua; Meng, Huadong; Wei, Yimin; Wang, Xiqin
2011-01-01
The problem to be addressed in this paper is a phase-modulated waveform design for the detection of extended targets contaminated by signal-dependent noise (clutter) and additive noise in practical radar systems. An optimal waveform design method that leads to the energy spectral density (ESD) of signal under the maximum signal-to-clutter-and-noise ratio (SCNR) criterion is introduced first. In order to make full use of the transmission power, a novel phase-iterative algorithm is then proposed for designing the phase-modulated waveform with a constant envelope, whose ESD matches the optimal one. This method is proven to be able to achieve a small SCNR loss by minimizing the mean-square spectral distance between the optimal waveform and the designed waveform. The results of extensive simulations demonstrate that our approach provides less than 1 dB SCNR loss when the signal duration is greater than 1 μs, and outperforms the stationary phase method and other phase-modulated waveform design methods.
Blackman, Jonathan; Field, Scott; Galley, Chad; Hemberger, Daniel; Scheel, Mark; Schmidt, Patricia; Smith, Rory; SXS Collaboration Collaboration
2016-03-01
We are now in the advanced detector era of gravitational wave astronomy, and the merger of two black holes (BHs) is one of the most promising sources of gravitational waves that could be detected on earth. To infer the BH masses and spins, the observed signal must be compared to waveforms predicted by general relativity for millions of binary configurations. Numerical relativity (NR) simulations can produce accurate waveforms, but are prohibitively expensive to use for parameter estimation. Other waveform models are fast enough but may lack accuracy in portions of the parameter space. Numerical relativity surrogate models attempt to rapidly predict the results of a NR code with a small or negligible modeling error, after being trained on a set of input waveforms. Such surrogate models are ideal for parameter estimation, as they are both fast and accurate, and have already been built for the case of non-spinning BHs. Using 250 input waveforms, we build a surrogate model for waveforms from the Spectral Einstein Code (SpEC) for a subspace of precessing systems.
Improved threshold retracker for satellite altimeter waveform retracking over coastal sea
Institute of Scientific and Technical Information of China (English)
GUO Jinyun; HWANG Cheiway; CHANG Xiaotao; LIU Yuting
2006-01-01
Data quality is a key factor for the application of satellite altimetry to geodesy and oceanography. Accuracy of altimetry is limited in the coastal area because the altimeter waveforms are seriously contaminated by topography and environmental pollution. So waveform retracking is needed to compute the range correction of geophysical data records (GDRs) for better accuracy. In this paper, a new waveform retracker named the improved threshold retracker (ITR) is put forward. The retracker first builds sub-waveforms based on leading edges detected in a waveform, then determines the middle point of each leading edge to compute the retracking range correction,finally calculates the referenced sea surface heights according to the geoid undulation from a local geopotential model and tide heights from an ocean tide model, and compares it with all retracking ranges to determine the best one. As a test, altimeter waveforms of Geosat/GM are retracked around the Taiwan coastal area. The result shows that accuracy of ITR method is two times better than that of theβ-5-parameter function-fitting method and threshold method, and three times better than that of GDRs. ITR can efficiently improve the altimetry accuracy of the coastal sea area.
Phase-Modulated Waveform Design for Extended Target Detection in the Presence of Clutter
Directory of Open Access Journals (Sweden)
Xiqin Wang
2011-07-01
Full Text Available The problem to be addressed in this paper is a phase-modulated waveform design for the detection of extended targets contaminated by signal-dependent noise (clutter and additive noise in practical radar systems. An optimal waveform design method that leads to the energy spectral density (ESD of signal under the maximum signal-to-clutter-and-noise ratio (SCNR criterion is introduced first. In order to make full use of the transmission power, a novel phase-iterative algorithm is then proposed for designing the phase-modulated waveform with a constant envelope, whose ESD matches the optimal one. This method is proven to be able to achieve a small SCNR loss by minimizing the mean-square spectral distance between the optimal waveform and the designed waveform. The results of extensive simulations demonstrate that our approach provides less than 1 dB SCNR loss when the signal duration is greater than 1 μs, and outperforms the stationary phase method and other phase-modulated waveform design methods.
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.
Effective-one-body waveforms for binary neutron stars using surrogate models
Lackey, Benjamin D; Galley, Chad R; Meidam, Jeroen; Broeck, Chris Van Den
2016-01-01
Gravitational-wave observations of binary neutron star systems can provide information about the masses, spins, and structure of neutron stars. However, this requires accurate and computationally efficient waveform models that take <1s to evaluate for use in Bayesian parameter estimation codes that perform 10^7 - 10^8 waveform evaluations. We present a surrogate model of a nonspinning effective-one-body waveform model with l = 2, 3, and 4 tidal multipole moments that reproduces waveforms of binary neutron star numerical simulations up to merger. The surrogate is built from compact sets of effective-one-body waveform amplitude and phase data that each form a reduced basis. We find that 12 amplitude and 7 phase basis elements are sufficient to reconstruct any binary neutron star waveform with a starting frequency of 10Hz. The surrogate has maximum errors of 3.8% in amplitude (0.04% excluding the last 100M before merger) and 0.043 radians in phase. The version implemented in the LIGO Algorithm Library takes ~...
Urban Tree Classification Using Full-Waveform Airborne Laser Scanning
Koma, Zs.; Koenig, K.; Höfle, B.
2016-06-01
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.
Lossy Wavefield Compression for Full-Waveform Inversion
Boehm, C.; Fichtner, A.; de la Puente, J.; Hanzich, M.
2015-12-01
We present lossy compression techniques, tailored to the inexact computation of sensitivity kernels, that significantly reduce the memory requirements of adjoint-based minimization schemes. Adjoint methods are a powerful tool to solve tomography problems in full-waveform inversion (FWI). Yet they face the challenge of massive memory requirements caused by the opposite directions of forward and adjoint simulations and the necessity to access both wavefields simultaneously during the computation of the sensitivity kernel. Thus, storage, I/O operations, and memory bandwidth become key topics in FWI. In this talk, we present strategies for the temporal and spatial compression of the forward wavefield. This comprises re-interpolation with coarse time steps and an adaptive polynomial degree of the spectral element shape functions. In addition, we predict the projection errors on a hierarchy of grids and re-quantize the residuals with an adaptive floating-point accuracy to improve the approximation. Furthermore, we use the first arrivals of adjoint waves to identify "shadow zones" that do not contribute to the sensitivity kernel at all. Updating and storing the wavefield within these shadow zones is skipped, which reduces memory requirements and computational costs at the same time. Compared to check-pointing, our approach has only a negligible computational overhead, utilizing the fact that a sufficiently accurate sensitivity kernel does not require a fully resolved forward wavefield. Furthermore, we use adaptive compression thresholds during the FWI iterations to ensure convergence. Numerical experiments on the reservoir scale and for the Western Mediterranean prove the high potential of this approach with an effective compression factor of 500-1000. Furthermore, it is computationally cheap and easy to integrate in both, finite-differences and finite-element wave propagation codes.
Forward and Backward Pressure Waveform Morphology in Hypertension
Li, Ye; Gu, Haotian; Fok, Henry; Alastruey, Jordi
2017-01-01
We tested the hypothesis that increased pulse wave reflection and altered backward waveform morphology contribute to increased pulse pressure in subjects with higher pulse pressure compared with lower pulse pressure and to actions of vasoactive drugs to increase pulse pressure. We examined the relationship of backward to forward wave morphology in 158 subjects who were evaluated for hypertension (including some normotensive subjects) divided into 3 groups by central pulse pressure: group 1, 33±6.5 mm Hg; group 2, 45±4.1 mm Hg; and group 3, 64±12.9 mm Hg (means±SD) and in healthy normotensive subjects during administration of inotropic and vasomotor drugs. Aortic pressure and flow in the aortic root were estimated by carotid tonometry and Doppler sonography, respectively. Morphology of the backward wave relative to the forward wave was similar in subjects in the lowest and highest tertiles of pulse pressure. Similar results were seen with the inotropic, vasopressor and vasodilator drugs, dobutamine, norepinephrine, and phentolamine, with the backward wave maintaining a constant ratio to the forward wave. However, nitroglycerin, a drug with a specific action to dilate muscular conduit arteries, reduced the amplitude of the backward wave relative to the forward wave from 0.26±0.018 at baseline to 0.19±0.019 during nitroglycerin 30 μg/min IV (P<0.01). These results are best explained by an approximately constant amount of reflection of the forward wave from the peripheral vasculature. The amount of reflection can be modified by dilation of peripheral muscular conduit arteries but contributes little to increased pulse pressure in hypertension. PMID:27920128
Consensus-Based Sorting of Neuronal Spike Waveforms
Fournier, Julien; Mueller, Christian M.; Shein-Idelson, Mark; Hemberger, Mike
2016-01-01
Optimizing spike-sorting algorithms is difficult because sorted clusters can rarely be checked against independently obtained “ground truth” data. In most spike-sorting algorithms in use today, the optimality of a clustering solution is assessed relative to some assumption on the distribution of the spike shapes associated with a particular single unit (e.g., Gaussianity) and by visual inspection of the clustering solution followed by manual validation. When the spatiotemporal waveforms of spikes from different cells overlap, the decision as to whether two spikes should be assigned to the same source can be quite subjective, if it is not based on reliable quantitative measures. We propose a new approach, whereby spike clusters are identified from the most consensual partition across an ensemble of clustering solutions. Using the variability of the clustering solutions across successive iterations of the same clustering algorithm (template matching based on K-means clusters), we estimate the probability of spikes being clustered together and identify groups of spikes that are not statistically distinguishable from one another. Thus, we identify spikes that are most likely to be clustered together and therefore correspond to consistent spike clusters. This method has the potential advantage that it does not rely on any model of the spike shapes. It also provides estimates of the proportion of misclassified spikes for each of the identified clusters. We tested our algorithm on several datasets for which there exists a ground truth (simultaneous intracellular data), and show that it performs close to the optimum reached by a support vector machine trained on the ground truth. We also show that the estimated rate of misclassification matches the proportion of misclassified spikes measured from the ground truth data. PMID:27536990
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.
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
Directory of Open Access Journals (Sweden)
Kristina Koenig
2016-09-01
Full Text Available In recent years, small-footprint full-waveform airborne laser scanning has become readily available and established for vegetation studies in the fields of forestry, agriculture and urban studies. Independent of the field of application and the derived final product, each study uses features to classify a target object and to assess its characteristics (e.g., tree species. These laser scanning features describe an observable characteristic of the returned laser signal (e.g., signal amplitude or a quantity of an object (e.g., height-width ratio of the tree crown. In particular, studies dealing with tree species classification apply a variety of such features as input. However, an extensive overview, categorization and comparison of features from full-waveform airborne laser scanning and how they relate to specific tree species are still missing. This review identifies frequently used full-waveform airborne laser scanning-based point cloud and waveform features for tree species classification and compares the applied features and their characteristics for specific tree species detection. Furthermore, limiting and influencing factors on feature characteristics and tree classification are discussed with respect to vegetation structure, data acquisition and processing.
2D acoustic-elastic coupled waveform inversion in the Laplace domain
Bae, Hoseuk
2010-04-01
Although waveform inversion has been intensively studied in an effort to properly delineate the Earth\\'s structures since the early 1980s, most of the time- and frequency-domain waveform inversion algorithms still have critical limitations in their applications to field data. This may be attributed to the highly non-linear objective function and the unreliable low-frequency components. To overcome the weaknesses of conventional waveform inversion algorithms, the acoustic Laplace-domain waveform inversion has been proposed. The Laplace-domain waveform inversion has been known to provide a long-wavelength velocity model even for field data, which may be because it employs the zero-frequency component of the damped wavefield and a well-behaved logarithmic objective function. However, its applications have been confined to 2D acoustic media.We extend the Laplace-domain waveform inversion algorithm to a 2D acoustic-elastic coupled medium, which is encountered in marine exploration environments. In 2D acoustic-elastic coupled media, the Laplace-domain pressures behave differently from those of 2D acoustic media, although the overall features are similar to each other. The main differences are that the pressure wavefields for acoustic-elastic coupled media show negative values even for simple geological structures unlike in acoustic media, when the Laplace damping constant is small and the water depth is shallow. The negative values may result from more complicated wave propagation in elastic media and at fluid-solid interfaces.Our Laplace-domain waveform inversion algorithm is also based on the finite-element method and logarithmic wavefields. To compute gradient direction, we apply the back-propagation technique. Under the assumption that density is fixed, P- and S-wave velocity models are inverted from the pressure data. We applied our inversion algorithm to the SEG/EAGE salt model and the numerical results showed that the Laplace-domain waveform inversion
Application of Carbonate Reservoir using waveform inversion and reverse-time migration methods
Kim, W.; Kim, H.; Min, D.; Keehm, Y.
2011-12-01
Recent exploration targets of oil and gas resources are deeper and more complicated subsurface structures, and carbonate reservoirs have become one of the attractive and challenging targets in seismic exploration. To increase the rate of success in oil and gas exploration, it is required to delineate detailed subsurface structures. Accordingly, migration method is more important factor in seismic data processing for the delineation. Seismic migration method has a long history, and there have been developed lots of migration techniques. Among them, reverse-time migration is promising, because it can provide reliable images for the complicated model even in the case of significant velocity contrasts in the model. The reliability of seismic migration images is dependent on the subsurface velocity models, which can be extracted in several ways. These days, geophysicists try to obtain velocity models through seismic full waveform inversion. Since Lailly (1983) and Tarantola (1984) proposed that the adjoint state of wave equations can be used in waveform inversion, the back-propagation techniques used in reverse-time migration have been used in waveform inversion, which accelerated the development of waveform inversion. In this study, we applied acoustic waveform inversion and reverse-time migration methods to carbonate reservoir models with various reservoir thicknesses to examine the feasibility of the methods in delineating carbonate reservoir models. We first extracted subsurface material properties from acoustic waveform inversion, and then applied reverse-time migration using the inverted velocities as a background model. The waveform inversion in this study used back-propagation technique, and conjugate gradient method was used in optimization. The inversion was performed using the frequency-selection strategy. Finally waveform inversion results showed that carbonate reservoir models are clearly inverted by waveform inversion and migration images based on the
Kobayashi, Kazuyoshi; Imagama, Shiro; Ito, Zenya; Ando, Kei; Hida, Tetsuro; Ito, Kenyu; Tsushima, Mikito; Ishikawa, Yoshimoto; Matsumoto, Akiyuki; Nishida, Yoshihiro; Ishiguro, Naoki
2017-01-01
OBJECTIVE Corrective surgery for spinal deformities can lead to neurological complications. Several reports have described spinal cord monitoring in surgery for spinal deformity, but only a few have included patients younger than 20 years with adolescent idiopathic scoliosis (AIS). The goal of this study was to evaluate the characteristics of cases with intraoperative transcranial motor evoked potential (Tc-MEP) waveform deterioration during posterior corrective fusion for AIS. METHODS A prospective database was reviewed, comprising 68 patients with AIS who were treated with posterior corrective fusion in a prospective database. A total of 864 muscles in the lower extremities were chosen for monitoring, and acceptable baseline responses were obtained from 819 muscles (95%). Intraoperative Tc-MEP waveform deterioration was defined as a decrease in intraoperative amplitude of ≥ 70% of the control waveform. Age, Cobb angle, flexibility, operative time, estimated blood loss (EBL), intraoperative body temperature, blood pressure, number of levels fused, and correction rate were examined in patients with and without waveform deterioration. RESULTS The patients (3 males and 65 females) had an average age of 14.4 years (range 11-19 years). The mean Cobb angles before and after surgery were 52.9° and 11.9°, respectively, giving a correction rate of 77.4%. Fourteen patients (20%) exhibited an intraoperative waveform change, and these occurred during incision (14%), after screw fixation (7%), during the rotation maneuver (64%), during placement of the second rod after the rotation maneuver (7%), and after intervertebral compression (7%). Most waveform changes recovered after decreased correction or rest. No patient had a motor deficit postoperatively. In multivariate analysis, EBL (OR 1.001, p = 0.085) and number of levels fused (OR 1.535, p = 0.045) were associated with waveform deterioration. CONCLUSIONS Waveform deterioration commonly occurred during rotation maneuvers
On Optimal Truncated Biharmonic Current Waveforms for Class-F and Inverse Class-F Power Amplifiers
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Anamarija Juhas
2017-01-01
Full Text Available In this paper, two-parameter families of periodic current waveforms for class-F and inverse class-F power amplifiers (PAs are considered. These waveforms are obtained by truncating cosine waveforms composed of dc component and fundamental and either second (k=2 or third (k=3 harmonic. In each period, waveforms are truncated to become zero outside of a prescribed interval (so-called conduction angle. The considered families of waveforms include both discontinuous and continuous waveforms. Fourier series expansion of truncated waveform contains an infinite number of harmonics, although a number of harmonics may be missing. Taking into account common assumptions that for class-F PA the third (n=3 harmonic is missing in current waveform and for inverse class-F PA the second (n=2 harmonic is missing in current waveform, we consider the following four cases: (i n=k=3, (ii n=3, k=2, (iii n=k=2, and (iv n=2, k=3. We show that, in each of these cases, current waveform enabling maximal efficiency (optimal waveform of class-F and inverse class-F PA is continuous for all conduction angles of practical interest. Furthermore, we provide closed-form expressions for parameters of optimal current waveforms and maximal efficiency of class-F (inverse class-F PA in terms of conduction angle only. Two case studies of practical interest for PA design, involving suboptimal current waveforms, along with the results of nonlinear simulation of inverse class-F PA, are also presented.
Li, Wang; Niu, Zheng; Li, Jing; Chen, Hanyue; Gao, Shuai; Wu, Mingquan; Li, Dong
2016-05-02
Leaf area index (LAI) is a key parameter for the study of biogeochemical cycles in ecosystems. Remote sensing techniques have been widely used to estimate LAIs in a wide range of vegetation types. However, limited by the sensor detection capability, considerable fewer studies investigated the layered estimation of LAIs in the vertical direction, which can significantly affect the precision evaluation of vegetation biophysical and biochemical processes. This study tried to generate a kind of pseudo large footprint waveform from the small footprint full-waveform airborne LiDAR data by an aggregation approach. The layered distribution of canopy heights and LAIs were successfully retrieved based on the large footprint waveform data in an agricultural landscape of orchards with typical multi-layer vegetation covers. The Gaussian fitting was conducted on the normalized large footprint waveforms to identify the vertical positions for different vegetation layers. Then, the gap theory was applied to retrieve the layered LAIs. Statistically significant simple linear regression models were fitted between the LiDAR-retrieved and field-observed values for the canopy heights and LAIs in different layers. Satisfactory results were obtained with a root mean square error of 0.36 m for the overstorey canopy height (R2 = 0.82), 0.29 m for the understory canopy height (R2 = 0.76), 0.28 for overstorey LAI (R2 = 0.75), 0.40 for understory LAI (R2 = 0.64), and 0.38 for total LAI (R2 = 0.69), respectively. To conclude, estimating the layered LAIs in the multi-layer agriculture orchards from the pseudo large footprint waveforms is feasible and the estimation errors are acceptable, which will provide some new ideas and methods for the quantitative remote sensing with vegetation.
Local full-waveform inversion using distant data
Masson, Yder; Romanowicz, Barbara; Zhao Zheng, Allen
2014-05-01
Imaging remote objects in the deep Earth, such as, subducting slabs, mantle plumes, or large low shear velocity provinces and ultra low velocity zones is key for understanding Earth's structure and the geodynamical processes involved as it cools. In order to image these structures, we developed a strategy for performing regional-scale full-waveform inversions at arbitrary location inside the Earth [1]. Our approach is to confine wave propagation computations inside the region to be imaged. This local wavefield modeling is used in combination with wavefield extrapolation techniques in order to obtain synthetic seismograms at the surface of the Earth [2]. This allows us to evaluate a misfit functional and sensitivity kernels can then be computed locally using the adjoint state method [3]. The Green's functions needed for extrapolating the wavefield are computed once for all in a 3D reference Earth model using the spectral element software Specfem/3DGLOBE. We will present benchmark tests demonstrating that the proposed method allows us to image 3D localized structures - this without having to model wave propagation in the entire Earth at each iteration, which is prohibitively costly, thus improving the feasibility of accurate imaging of regional structures anywhere in the Earth using numerical methods. We will show that our method permits to account for additional data in regional inversions, that is to account for distant earthquakes that are located outside the region of the study - preliminary results for the tomography of the north American continent will be presented. [1] Masson, Yder, Paul Cupillard, Yann Capdeville, and Barbara Romanowicz. On the numerical im- plementation of time-reversal mirrors for tomographic imaging. Geophysical Journal International, 2013. [2] J. O. A. Robertsson, S. Ryan-Grigor, C. M. Sayers, and C. H. Chapman. A finite-difference injection approach to modeling seismic fluid flow monitoring. Geophysics, 65(3):896-906, 2000. [3] R
Full waveform ambient noise tomography of Mount Rainer
Flinders, A. F.; Shen, Y.
2014-12-01
Mount Rainier towers over the landscape of western Washington, ranking with Fuji-yama in Japan, Mt. Pinatubo in the Philippines, and Mt. Vesuvius in Italy, as one of the great stratovolcanoes of the world. Notwithstanding it's picturesque stature, Mt. Rainier is potentially the most devastating stratovolcano in North America, with more than 3.5 million people living beneath its shadow in the Seattle-Tacoma area. The primary hazard posed by the volcano is in the form of highly destructive volcanic debris flows (lahars). These lahars form when water and/or melted ice erode away and entrain preexisting volcanic sediment. At Mt. Rainier these flows are often initiated by sector collapse of the volcano's hydrothermally rotten flanks and compounded from Mt. Rainier's extensive snow and glacial ice coverage. It is therefore imperative to ascertain the extent of summit hydrothermal alteration within the volcano, and determine areas prone to collapse. Despite being one of the sixteen volcanoes globally designated by the International Association of Volcanology and Chemistry of the Earth's Interior as warranting detailed and focused study, Mt. Rainier remains enigmatic both in terms of shallow internal structure and the degree of summit hydrothermal alteration. We image this shallow internal structure and areas of possible summit alteration using ambient noise tomography. Our full waveform forward modeling includes high-resolution topography, allowing us to accurately account for the effects of topography on the propagation of short-period Rayleigh waves. Empirical Green's functions were extracted from 80 stations within 200 km of Mount Rainier and compared with synthetic greens functions over multiple frequency bands from 2-28 seconds. The preliminary model shows a broad (60 km wide) low shear-wave velocity anomaly in the mid-crust beneath the volcano. The mid-crust low-velocity body extends to the surface beneath the volcano summit in a narrow near-vertical conduit, the
Canopy Height Estimation by Characterizing Waveform LiDAR Geometry Based on Shape-Distance Metric
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Eric Ariel L. Salas
2016-11-01
Full Text Available There have been few approaches developed for the estimation of height using waveform LiDAR data. Unlike any existing methods, we illustrate how the new Moment Distance (MD framework can characterize the canopy height based on the geometry and return power of the LiDAR waveform without having to go through curve modeling processes. Our approach offers the possibilities of using the raw waveform data to capture vital information from the variety of complex waveform shapes in LiDAR. We assess the relationship of the MD metrics to the key waveform landmarks—such as locations of peaks, power of returns, canopy heights, and height metrics—using synthetic data and real Laser Vegetation Imaging Sensor (LVIS data. In order to verify the utility of the new approach, we use field measurements obtained through the DESDynI (Deformation, Ecosystem Structure and Dynamics of Ice campaign. Our results reveal that the MDI can capture temporal dynamics of canopy and segregate generations of stands based on curve shapes. The method satisfactorily estimates the canopy height using the synthetic (r2 = 0.40 and the LVIS dataset (r2 = 0.74. The MDI is also comparable with existing RH75 (relative height at 75% and RH50 (relative height at 50% height metrics. Furthermore, the MDI shows better correlations with ground-based measurements than relative height metrics. The MDI performs well at any type of waveform shape. This opens the possibility of looking more closely at single-peaked waveforms that usually carries complex extremes.
Oltean, Gabriel; Ivanciu, Laura-Nicoleta
2016-01-01
The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms), efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer), and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination). The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each parameter on the
Oltean, Gabriel; Ivanciu, Laura-Nicoleta
2016-01-01
The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms), efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer), and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination). The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each parameter on the
Estimating extracellular spike waveforms from CA1 pyramidal cells with multichannel electrodes.
Directory of Open Access Journals (Sweden)
Sturla Molden
Full Text Available Extracellular (EC recordings of action potentials from the intact brain are embedded in background voltage fluctuations known as the "local field potential" (LFP. In order to use EC spike recordings for studying biophysical properties of neurons, the spike waveforms must be separated from the LFP. Linear low-pass and high-pass filters are usually insufficient to separate spike waveforms from LFP, because they have overlapping frequency bands. Broad-band recordings of LFP and spikes were obtained with a 16-channel laminar electrode array (silicone probe. We developed an algorithm whereby local LFP signals from spike-containing channel were modeled using locally weighted polynomial regression analysis of adjoining channels without spikes. The modeled LFP signal was subtracted from the recording to estimate the embedded spike waveforms. We tested the method both on defined spike waveforms added to LFP recordings, and on in vivo-recorded extracellular spikes from hippocampal CA1 pyramidal cells in anaesthetized mice. We show that the algorithm can correctly extract the spike waveforms embedded in the LFP. In contrast, traditional high-pass filters failed to recover correct spike shapes, albeit produceing smaller standard errors. We found that high-pass RC or 2-pole Butterworth filters with cut-off frequencies below 12.5 Hz, are required to retrieve waveforms comparable to our method. The method was also compared to spike-triggered averages of the broad-band signal, and yielded waveforms with smaller standard errors and less distortion before and after the spike.
Directory of Open Access Journals (Sweden)
Gabriel Oltean
Full Text Available The design and verification of complex electronic systems, especially the analog and mixed-signal ones, prove to be extremely time consuming tasks, if only circuit-level simulations are involved. A significant amount of time can be saved if a cost effective solution is used for the extensive analysis of the system, under all conceivable conditions. This paper proposes a data-driven method to build fast to evaluate, but also accurate metamodels capable of generating not-yet simulated waveforms as a function of different combinations of the parameters of the system. The necessary data are obtained by early-stage simulation of an electronic control system from the automotive industry. The metamodel development is based on three key elements: a wavelet transform for waveform characterization, a genetic algorithm optimization to detect the optimal wavelet transform and to identify the most relevant decomposition coefficients, and an artificial neuronal network to derive the relevant coefficients of the wavelet transform for any new parameters combination. The resulted metamodels for three different waveform families are fully reliable. They satisfy the required key points: high accuracy (a maximum mean squared error of 7.1x10-5 for the unity-based normalized waveforms, efficiency (fully affordable computational effort for metamodel build-up: maximum 18 minutes on a general purpose computer, and simplicity (less than 1 second for running the metamodel, the user only provides the parameters combination. The metamodels can be used for very efficient generation of new waveforms, for any possible combination of dependent parameters, offering the possibility to explore the entire design space. A wide range of possibilities becomes achievable for the user, such as: all design corners can be analyzed, possible worst-case situations can be investigated, extreme values of waveforms can be discovered, sensitivity analyses can be performed (the influence of each
Extraction of Vegetation Biophysical Structure from Small-Footprint Full-Waveform Lidar Signals
Romanczyk, Paul
The National Ecological Observatory Network (NEON) is a continental scale environmental monitoring initiative tasked with characterizing and understanding ecological phenomenology over a 30-year time frame. To support this mission, NEON collects ground truth measurements, such as organism counts and characterization, carbon flux measurements, etc. To spatially upscale these plot-based measurements, NEON developed an airborne observation platform (AOP), with a high-resolution visible camera, next-generation AVIRIS imaging spectrometer, and a discrete and waveform digitizing light detection and ranging (lidar) system. While visible imaging, imaging spectroscopy, and discrete lidar are relatively mature technologies, our understanding of and associated algorithm development for small-footprint full-waveform lidar are still in early stages of development. This work has as its primary aim to extend small-footprint full-waveform lidar capabilities to assess vegetation biophysical structure. In order to fully exploit waveform lidar capabilities, high fidelity geometric and radio-metric truth data are needed. Forests are structurally and spectrally complex, which makes collecting the necessary truth challenging, if not impossible. We utilize the Digital Imaging and Remote Sensing Image Generation (DIRSIG) model, which provides an environment for radiometric simulations, in order to simulate waveform lidar signals. The first step of this research was to build a virtual forest stand based on Harvard Forest inventory data. This scene was used to assess the level of geometric fidelity necessary for small-footprint waveform lidar simulation in broadleaf forests. It was found that leaves have the largest influence on the backscattered signal and that there is little contribution to the signal from the leaf stems and twigs. From this knowledge, a number of additional realistic and abstract virtual "forest" scenes were created to aid studies assessing the ability of waveform lidar
Huang, Zhengkai; Wang, Haihong; Luo, Zhicai
2017-04-01
Due to the complex coastal topography and energetic ocean dynamics effect, the return echoes are contaminated while the satellite footprint approaches or leaves the coastline. Specular peaks are often induced in the trailing edges of contaminated waveforms, thus leading the error in the determination of the leading edge and associated track offset in the waveform retracking process. We propose an improved algorithm base on Tseng's modification method to decontaminated coastal (0-7 km from coastline) waveforms, thus improving both the utilization and precision of coastal sea surface height (SSH). Using the Envisat/Jason-2 SGDR data, the shortcoming of Tseng's method is pointed out and the novel algorithm is proposed by revising the strategy of selecting reference waveform and determining weight for removing outlier. The reference waveform of the decontaminated technology is closer to the real waveform of the offshore area, which avoids the over-modification problem of Tseng method. The sea-level measurements from tide gauge station and geoid height from EGM2008 model were used to validate the retracking strategy. Experimental results show that decontaminated waveform was more suitable than original and Tseng modified waveform and has uniform performance in both compare to the tide gauge and geoid. The retrieved altimetry data in the 0-1km and 1-7km coastal zone indicate that threshold retracker with decontaminated waveform have STD of 73.8cm and 33cm as compared with in situ gauge data,which correspond to 62.1% and 58% in precession compared to the unretracked altimetry measurements. The retracked SSHs are better in two coastal (0-1 km and 1-7km) zones, which have STD of 11.9cm and 22.7cm as compared with geoid height. Furthermore, the comparisons shows that the precision of decontaminated technology improve 0.3cm and 3.3cm than the best result of PISTACH product in coastal sea. This work is supported by the National Natural Science Foundation of China (Grant Nos
Changing the waveform of circadian rhythms: considerations for shift-work
Directory of Open Access Journals (Sweden)
Elizabeth M Harrison
2012-05-01
Full Text Available Circadian disruption in shift-work is common and has deleterious effects on health and performance. Current efforts to mitigate these harms reasonably focus on the phase of the circadian pacemaker, which unfortunately in humans, shifts slowly and often incompletely. Temporal reorganization of rhythmic waveform (i.e. the shape of its 24 h oscillation, rather than phase, however, may better match performance demands of shift-workers and can be quickly and feasibly implemented in animals. In fact, a bifurcated pacemaker waveform may permit stable entrainment of a bimodal sleep/wake rhythm promoting alertness in both night and daylight hours. Although bifurcation has yet to be formally assessed in humans, evidence of conserved properties of circadian organization and plasticity predict its occurrence: humans respond to conventional manipulations of waveform (e.g., photoperiodism; behaviorally, the sleep/wake rhythm is adaptable; and finally, the human circadian system likely derives from the same multiple cellular oscillators that permit waveform flexibility in the rodent pacemaker. In short, investigation into untried manipulations of waveform in humans to facilitate adjustment to challenging schedules is justified.
Gao, Bindong; Zhang, Fangzheng; Pan, Shilong
2017-01-01
Arbitrary waveform generation by a serial photonic digital-to-analog converter (PDAC) is demonstrated in this paper. To construct the PDAC, an intensity weighted, time and wavelength interleaved optical pulse train is first generated by phase modulation and fiber dispersion. Then, on-off keying modulation of the optical pulses is implemented according to the input serial digital bits. After proper dispersion compensation, a combined optical pulse is obtained with its total power proportional to the weighted sum of the input digital bits, and digital-to-analog conversion is achieved after optical-to-electronic conversion. By properly designing the input bits and using a low pass filter for signal smoothing, arbitrary waveforms can be generated. Performance of the PDAC is experimentally investigated by establishing a 2.5 GSa/s 4-bit PDAC. The established PDAC is found to have a good linear transfer function and the effective number of bits (ENOB) reaches as high as 3.49. Based on the constructed PDAC, generation of multiple waveforms including triangular, parabolic, square and sawtooth pulses are implemented with the generated waveforms very close to the ideal waveforms.
Electroreception in G carapo: detection of changes in waveform of the electrosensory signals.
Aguilera, Pedro A; Caputi, Angel A
2003-03-01
Electric fish evaluate the near environment by detecting changes in their self-generated electric organ discharge. To investigate impedance modulation of the self-generated electric field, this field was measured at the electrosensory fovea of Gymnotus carapo in the presence and absence of objects. Changes in local fields provoked by resistive objects were predicted by the change in total energy. Objects with capacitive impedance generated large variations in the relative importance of the different waveform components of the electric organ discharge. We tested the hypothesis that fish discriminate changes in waveform as well as increases in total energy using the novelty response, which is a behavioural response consisting of a transient acceleration of EOD frequency that can follow a change in object impedance. For resistive loads, the amplitude of novelty responses was well predicted by the increase in total energy. For complex loads, the amplitude of novelty responses was correlated not only with increases in total energy but also with waveform changes, consisting of reductions in the early slow negative wave and increases in the late sharp negative wave. The total energy and waveform effects appeared to be additive. These results indicate that G. carapo discriminates complex impedance based on an evaluation of different waveform parameters.
Tao, Kai; Grand, Stephen P.; Niu, Fenglin
2017-09-01
In seismic full-waveform inversion (FWI), the choice of misfit function determines what information in data is used and ultimately affects the resolution of the inverted images of the Earth's structure. Misfit functions based on traveltime have been successfully applied in global and regional tomographic studies. However, wave propagation through the upper mantle results in multiple phases arriving at a given receiver in a narrow time interval resulting in complicated waveforms that evolve with distance. To extract waveform information as well as traveltime, we use a misfit function based on the normalized correlation coefficient (CC). This misfit function is able to capture the waveform complexities in both phase and relative amplitude within the measurement window. It is also insensitive to absolute amplitude differences between modeled and recorded data, which avoids problems due to uncertainties in source magnitude, radiation pattern, receiver site effects or even miscalibrated instruments. These features make the misfit function based on normalized CC a good candidate to achieve high-resolution images of complex geological structures when interfering phases coexist in the measurement window, such as triplication waveforms. From synthetic tests, we show the advantages of this misfit function over the cross-correlation traveltime misfit function. Preliminary inversion of data from an earthquake in Northeast China images a sharper and stronger amplitude slab stagnant in the middle of the transition zone than FWI of cross-correlation traveltime.
A 6kV Arbitrary Waveform Generator for the Tevatron Lens
Pfeffer, H; 10.1088/1748-0221/6/11/P11003
2012-01-01
This paper reports on a 6 kV modulator built and installed at Fermilab to drive the electron gun anode for the Tevatron Electron Lens (TEL). The TEL was built with the intention of shifting the individual (anti)proton bunch tunes to even out the tune spread among all 36 bunches with the desire of improving Tevatron integrated luminosity. This modulator is essentially a 6 kV arbitrary waveform generator that enables the TEL to define the electron beam intensity on a bunch-by-bunch basis. A voltage waveform is constructed having a 7 {\\mu}s duration that corresponds to the tune shift requirements of a 12-bunch (anti)proton beam pulse train. This waveform is played out for any one or all three bunch trains in the Tevatron. The programmed waveform voltages transition to different levels at time intervals corresponding to the 395 ns bunch spacing. Thus, complex voltage waveforms can be played out at a sustained rate of 143 kHz over the full 6 kV output range. This paper describes the novel design of the inductive a...
"To-and-fro" waveform in the diagnosis of arterial pseudoaneurysms
Institute of Scientific and Technical Information of China (English)
Mustafa; Z; Mahmoud; Mohammed; Al-Saadi; Abdulwahab; Abuderman; Khalid; S; Alzimami; Mohammed; Alkhorayef; Babikir; Almagli; Abdelmoneim; Sulieman
2015-01-01
Medical ultrasound imaging with Doppler plays an essential role in the diagnosis of vascular disease. This study intended to review the clinical use of "to-and-fro" waveform at duplex Doppler ultrasonography(DDU) in the diagnosis of pseudoaneurysms in the arterial vessels of upper and lower extremities, abdominal aorta, carotid and vertebral arteries as well as to review our personal experiences of "to-and-fro" waveform at DDU also. After receiving institutional review board approval, an inclusive literature review was carried out in order to review the scientific foundation of "toand-fro" waveform at DDU and its clinical use in the diagnosis of pseudoaneurysms in various arterial vessels. Articles published in the English language between 2000 and 2013 were evaluated in this review study. Pseudoaneurysms in arterial vessels of the upper and lower extremities, abdominal aorta, carotid and vertebral arteries characterized by an extraluminal pattern of blood flow, which shows variable echogenicity, interval complexity, and "to-and-fro" flow pattern on color Doppler ultrasonography. In these arterial vessels, Duplex ultrasonography can demonstrate the degree of clotting, pseudoaneurysm communication, the blood flow patterns and velocities. Spectral Doppler applied to pseudoaneurysms lumen revealed systolic and diastolic turbulent blood flow with traditional "toand-fro" waveform in the communicating channel. Accurate diagnosis of pseudoaneurysm by spectral Doppler is based on the documentation of the "to-andfro" waveform. The size of pseudoaneurysm determines the appropriate treatment approach as surgical or conservative.
Doppler waveforms of the hepatic veins in children with diffuse fatty infiltration of the liver
Energy Technology Data Exchange (ETDEWEB)
Uzun, Hakan [Duzce University School of Medicine, Department of Pediatrics, Konuralp, Duzce 81620 (Turkey); Yazici, Burhan [Duzce University School of Medicine, Department of Radiology, Konuralp, Duzce 81620 (Turkey)], E-mail: dryazici@yahoo.com; Erdogmus, Besir [Duzce University School of Medicine, Department of Radiology, Konuralp, Duzce 81620 (Turkey); Kocabay, Kenan [Duzce University School of Medicine, Department of Pediatrics, Konuralp, Duzce 81620 (Turkey); Buyukkaya, Ramazan; Buyukkaya, Ayla; Yazgan, Omer [Duzce University School of Medicine, Department of Radiology, Konuralp, Duzce 81620 (Turkey)
2009-09-15
Objective: The aim of this study was to investigate the effect of fatty infiltration of the liver (FIL) on the Doppler waveform pattern in the hepatic veins of obese children. Methods: In this prospective study, 59 patients with diffuse FIL and 45 normal healthy children who served as control group underwent hepatic vein B-mod and duplex Doppler sonography. The Doppler sonography spectrum of the right hepatic vein was classified into three groups: triphasic waveform, biphasic waveform, and monophasic or flat waveform. Results: There was a statistically significant difference in the phasicity of hepatic venous flow between patients and control subjects (p < 0.001). The Doppler flow pattern in the right hepatic vein was triphasic in 28 (47.5%), biphasic in 28 (47.5%), and monophasic in 3 (5%) children with fatty liver, while it was triphasic in 43 (95.6%) and biphasic in 2 (4.4%) control subjects. There was an inverse correlation between the sonographic grade of fatty infiltration of the liver and the phasicity of hepatic venous flow (r = -0.479, p < 0.001). Conclusions: Abnormal right hepatic vein Doppler waveform, biphasic as well as monophasic, can be seen in healthy obese children with diffuse FIL.
Codesign of Beam Pattern and Sparse Frequency Waveforms for MIMO Radar
Directory of Open Access Journals (Sweden)
Chaoyun Mai
2015-01-01
Full Text Available Multiple-input multiple-output (MIMO radar takes the advantages of high degrees of freedom for beam pattern design and waveform optimization, because each antenna in centralized MIMO radar system can transmit different signal waveforms. When continuous band is divided into several pieces, sparse frequency radar waveforms play an important role due to the special pattern of the sparse spectrum. In this paper, we start from the covariance matrix of the transmitted waveform and extend the concept of sparse frequency design to the study of MIMO radar beam pattern. With this idea in mind, we first solve the problem of semidefinite constraint by optimization tools and get the desired covariance matrix of the ideal beam pattern. Then, we use the acquired covariance matrix and generalize the objective function by adding the constraint of both constant modulus of the signals and corresponding spectrum. Finally, we solve the objective function by the cyclic algorithm and obtain the sparse frequency MIMO radar waveforms with desired beam pattern. The simulation results verify the effectiveness of this method.
Optical arbitrary waveform generation based on multi-wavelength semiconductor fiber ring laser
Li, Peili; Ma, Xiaolu; Shi, Weihua; Xu, Enming
2017-09-01
A new scheme of generating optical arbitrary waveforms based on multi-wavelength semiconductor fiber ring laser (SFRL) is proposed. In this novel scheme, a wide and flat optical frequency comb (OFC) is provided directly by multi-wavelength SFRL, whose central frequency and comb spacing are tunable. OFC generation, de-multiplexing, amplitude and phase modulation, and multiplexing are implementing in an intensity and phase tunable comb filter, as induces the merits of high spectral coherence, satisfactory waveform control and low system loss. By using the mode couple theory and the transfer matrix method, the theoretical model of the scheme is established. The impacts of amplitude control, phase control, number of spectral line, and injection current of semiconductor optical amplifier (SOA) on the waveform similarity are studied using the theoretical model. The results show that, amplitude control and phase control error should be smaller than 1% and 0.64% respectively to achieve high similarity. The similarity of the waveform is improved with the increase of the number of spectral line. When the injection current of SOA is in a certain range, the optical arbitrary waveform reaches a high similarity.
Derzsi, Aranka; Bruneau, Bastien; Gibson, Andrew Robert; Johnson, Erik; O’Connell, Deborah; Gans, Timo; Booth, Jean-Paul; Donkó, Zoltán
2017-03-01
Low-pressure capacitively coupled radio frequency discharges operated in O2 and driven by tailored voltage waveforms are investigated experimentally and by means of kinetic simulations. Pulse-type (peaks/valleys) and sawtooth-type voltage waveforms that consist of up to four consecutive harmonics of the fundamental frequency are used to study the amplitude asymmetry effect as well as the slope asymmetry effect at different fundamental frequencies (5, 10, and 15 MHz) and at different pressures (50–700 mTorr). Values of the DC self-bias determined experimentally and spatio-temporal excitation rates derived from phase resolved optical emission spectroscopy measurements are compared with particle-in-cell/Monte Carlo collisions simulations. The spatio-temporal distributions of the excitation rate obtained from experiments are well reproduced by the simulations. Transitions of the discharge electron heating mode from the drift-ambipolar mode to the α-mode are induced by changing the number of consecutive harmonics included in the driving voltage waveform or by changing the gas pressure. Changing the number of harmonics in the waveform has a strong effect on the electronegativity of the discharge, on the generation of the DC self-bias and on the control of ion properties at the electrodes, both for pulse-type, as well as sawtooth-type driving voltage waveforms The effect of the surface quenching rate of oxygen singlet delta metastable molecules on the spatio-temporal excitation patterns is also investigated.
Variable Rate Characteristic Waveform Interpolation Speech Coder Based on Phonetic Classification
Institute of Scientific and Technical Information of China (English)
WANG Jing; KUANG Jing-ming; ZHAO Sheng-hui
2007-01-01
A variable-bit-rate characteristic waveform interpolation (VBR-CWI) speech codec with about 1.8kbit/s average bit rate which integrates phonetic classification into characteristic waveform (CW) decomposition is proposed.Each input frame is classified into one of 4 phonetic classes.Non-speech frames are represented with Bark-band noise model.The extracted CWs become rapidly evolving waveforms (REWs) or slowly evolving waveforms (SEWs) in the cases of unvoiced or stationary voiced frames respectively, while mixed voiced frames use the same CW decomposition as that in the conventional CWI.Experimental results show that the proposed codec can eliminate most buzzy and noisy artifacts existing in the fixed-bit-rate characteristic waveform interpolation (FBR-CWI) speech codec, the average bit rate can be much lower, and its reconstructed speech quality is much better than FS 1016 CELP at 4.8kbit/s and similar to G.723.1 ACELP at 5.3kbit/s.
Bergen, K.; Yoon, C. E.; OReilly, O. J.; Beroza, G. C.
2015-12-01
Recent improvements in computational efficiency for waveform correlation-based detections achieved by new methods such as Fingerprint and Similarity Thresholding (FAST) promise to allow large-scale blind search for similar waveforms in long-duration continuous seismic data. Waveform similarity search applied to datasets of months to years of continuous seismic data will identify significantly more events than traditional detection methods. With the anticipated increase in number of detections and associated increase in false positives, manual inspection of the detection results will become infeasible. This motivates the need for new approaches to process the output of similarity-based detection. We explore data mining techniques for improved detection post-processing. We approach this by considering similarity-detector output as a sparse similarity graph with candidate events as vertices and similarities as weighted edges. Image processing techniques are leveraged to define candidate events and combine results individually processed at multiple stations. Clustering and graph analysis methods are used to identify groups of similar waveforms and assign a confidence score to candidate detections. Anomaly detection and classification are applied to waveform data for additional false detection removal. A comparison of methods will be presented and their performance will be demonstrated on a suspected induced and non-induced earthquake sequence.
Leigh, Holly W.; Magruder, Lori A.
2016-10-01
This study examines the utility of cocollected, dual-wavelength, full-waveform lidar data to characterize vegetation and landscapes through the extraction of waveform features, such as total waveform energy, canopy energy distribution, and foliage penetration metrics. Assessments are performed using data collected in May 2014 over Monterey, California, using the Chiroptera dual-laser lidar mapping system from Airborne Hydrography AB. Both full-waveform and discrete return data were collected simultaneously at green (532 nm) and near-infrared (NIR) (1064 nm) wavelengths; however, the two channels are operated independently at different pulse repetition frequencies, thus measurements are not spatially coincident. A voxelization approach is employed to generate pseudowaveforms for each wavelength along vertical columns in a regularly spaced grid, such that spectral waveform properties can be evaluated independently of spatial variations resulting from instrumentation configuration and collection scenario. The pseudowaveforms are parameterized and extracted parameters are mapped to raster layers, which are then used as inputs to a random forest classifier to predict land cover classifications across the survey area. In comparison to independent classification results for the two wavelength channels, the combination of the NIR and green response provided an improvement in overall classification accuracy of up to 6%. This effort presents the methodology associated with the voxelization approach and the exploitation of the pseudowaveform features, while illustrating a potential utility for geospatial classification using multiple wavelengths.
Range determination for generating point clouds from airborne small footprint LiDAR waveforms.
Qin, Yuchu; Vu, Tuong Thuy; Ban, Yifang; Niu, Zheng
2012-11-05
This paper presents a range determination approach for generating point clouds from small footprint LiDAR waveforms. Waveform deformation over complex terrain area is simulated using convolution. Drift of the peak center position is analyzed to identify the first echo returned by the illuminated objects in the LiDAR footprint. An approximate start point of peak in the waveform is estimated and adopted as the indicator of range calculation; range correction method is proposed to correct pulse widening over complex terrain surface. The experiment was carried out on small footprint LiDAR waveform data acquired by RIEGL LMS-Q560. The results suggest that the proposed approach generates more points than standard commercial products; based on field measurements, a comparative analysis between the point clouds generated by the proposed approach and the commercial software GeocodeWF indicates that: 1). the proposed approach obtained more accurate tree heights; 2). smooth surface can be achieved with low standard deviation. In summary, the proposed approach provides a satisfactory solution for range determination in estimating 3D coordinate values of point clouds, especially for correcting range information of waveforms containing deformed peaks.
Wang, Kun; Matthews, Thomas; Anis, Fatima; Li, Cuiping; Duric, Neb; Anastasio, Mark A.
2016-01-01
Ultrasound computed tomography (USCT) holds great promise for improving the detection and management of breast cancer. Because they are based on the acoustic wave equation, waveform inversion-based reconstruction methods can produce images that possess improved spatial resolution properties over those produced by ray-based methods. However, waveform inversion methods are computationally demanding and have not been applied widely in USCT breast imaging. In this work, source encoding concepts are employed to develop an accelerated USCT reconstruction method that circumvents the large computational burden of conventional waveform inversion methods. This method, referred to as the waveform inversion with source encoding (WISE) method, encodes the measurement data using a random encoding vector and determines an estimate of the sound speed distribution by solving a stochastic optimization problem by use of a stochastic gradient descent algorithm. Both computer-simulation and experimental phantom studies are conducted to demonstrate the use of the WISE method. The results suggest that the WISE method maintains the high spatial resolution of waveform inversion methods while significantly reducing the computational burden. PMID:25768816
"To-and-fro" waveform in the diagnosis of arterial pseudoaneurysms.
Mahmoud, Mustafa Z; Al-Saadi, Mohammed; Abuderman, Abdulwahab; Alzimami, Khalid S; Alkhorayef, Mohammed; Almagli, Babikir; Sulieman, Abdelmoneim
2015-05-28
Medical ultrasound imaging with Doppler plays an essential role in the diagnosis of vascular disease. This study intended to review the clinical use of "to-and-fro" waveform at duplex Doppler ultrasonography (DDU) in the diagnosis of pseudoaneurysms in the arterial vessels of upper and lower extremities, abdominal aorta, carotid and vertebral arteries as well as to review our personal experiences of "to-and-fro" waveform at DDU also. After receiving institutional review board approval, an inclusive literature review was carried out in order to review the scientific foundation of "to-and-fro" waveform at DDU and its clinical use in the diagnosis of pseudoaneurysms in various arterial vessels. Articles published in the English language between 2000 and 2013 were evaluated in this review study. Pseudoaneurysms in arterial vessels of the upper and lower extremities, abdominal aorta, carotid and vertebral arteries characterized by an extraluminal pattern of blood flow, which shows variable echogenicity, interval complexity, and "to-and-fro" flow pattern on color Doppler ultrasonography. In these arterial vessels, Duplex ultrasonography can demonstrate the degree of clotting, pseudoaneurysm communication, the blood flow patterns and velocities. Spectral Doppler applied to pseudoaneurysms lumen revealed systolic and diastolic turbulent blood flow with traditional "to-and-fro" waveform in the communicating channel. Accurate diagnosis of pseudoaneurysm by spectral Doppler is based on the documentation of the "to-and-fro" waveform. The size of pseudoaneurysm determines the appropriate treatment approach as surgical or conservative.
Selamtzis, Andreas; Ternström, Sten
2016-12-08
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.
Changing the waveform of circadian rhythms: considerations for shift-work.
Harrison, Elizabeth M; Gorman, Michael R
2012-01-01
Circadian disruption in shift-work is common and has deleterious effects on health and performance. Current efforts to mitigate these harms reasonably focus on the phase of the circadian pacemaker, which unfortunately in humans, shifts slowly and often incompletely. Temporal reorganization of rhythmic waveform (i.e., the shape of its 24 h oscillation), rather than phase, however, may better match performance demands of shift-workers and can be quickly and feasibly implemented in animals. In fact, a bifurcated pacemaker waveform may permit stable entrainment of a bimodal sleep/wake rhythm promoting alertness in both night and daylight hours. Although bifurcation has yet to be formally assessed in humans, evidence of conserved properties of circadian organization and plasticity predict its occurrence: humans respond to conventional manipulations of waveform (e.g., photoperiodism); behaviorally, the sleep/wake rhythm is adaptable; and finally, the human circadian system likely derives from the same multiple cellular oscillators that permit waveform flexibility in the rodent pacemaker. In short, investigation into untried manipulations of waveform in humans to facilitate adjustment to challenging schedules is justified.
Styczynski, Grzegorz; Szmigielski, Cezary; Kaczynska, Anna; Kuch-Wocial, Agnieszka
2014-04-01
Visual interpretation of the Doppler waveform in the common femoral or distal external iliac artery (EIA) was reported to be useful in screening for proximal peripheral artery occlusive disease (PAOD) in patients with lower limb ischemia. Commonly patients with coronary artery disease (CAD) referred for echocardiography have coexistent arterial pathology. Therefore, we decided to study whether echocardiographic evaluation of the distal EIA flow can be useful for detection of PAOD in patients with CAD. We studied 150 consecutive patients (pts) with CAD referred for echocardiography. At the end of an echocardiographic examination, evaluation of the flow in the distal EIA with an echocardiographic probe was performed. The Doppler waveform was classified as normal-with early diastolic flow reversal or abnormal-without early diastolic flow reversal. Echocardiographic findings were compared in a blinded fashion with the results of the ankle brachial index measurements (ABI). Based on the ABI ≤ 0.9, peripheral artery disease was diagnosed in 54 pts (36%) and abnormal external iliac Doppler waveform was found in 27 pts (18%). Sensitivity of abnormal external iliac Doppler waveform in predicting PAOD was 48%, specificity 99%, positive predictive value (PPV) 96%, and negative predictive value 77%. Peripheral arterial occlusive disease is common in patients with CAD referred for echocardiographic study. Echocardiographic assessment of distal EIA Doppler waveform has low sensitivity, but high specificity and high PPV in the diagnosis of peripheral arterial occlusive disease.
Wang, Kun; Matthews, Thomas; Anis, Fatima; Li, Cuiping; Duric, Neb; Anastasio, Mark A
2015-03-01
Ultrasound computed tomography (USCT) holds great promise for improving the detection and management of breast cancer. Because they are based on the acoustic wave equation, waveform inversion-based reconstruction methods can produce images that possess improved spatial resolution properties over those produced by ray-based methods. However, waveform inversion methods are computationally demanding and have not been applied widely in USCT breast imaging. In this work, source encoding concepts are employed to develop an accelerated USCT reconstruction method that circumvents the large computational burden of conventional waveform inversion methods. This method, referred to as the waveform inversion with source encoding (WISE) method, encodes the measurement data using a random encoding vector and determines an estimate of the sound speed distribution by solving a stochastic optimization problem by use of a stochastic gradient descent algorithm. Both computer simulation and experimental phantom studies are conducted to demonstrate the use of the WISE method. The results suggest that the WISE method maintains the high spatial resolution of waveform inversion methods while significantly reducing the computational burden.
Amelard, Robert; Clausi, David A; Wong, Alexander
2016-12-01
Photoplethysmographic imaging is an optical solution for non-contact cardiovascular monitoring from a distance. This camera-based technology enables physiological monitoring in situations where contact-based devices may be problematic or infeasible, such as ambulatory, sleep, and multi-individual monitoring. However, automatically extracting the blood pulse waveform signal is challenging due to the unknown mixture of relevant (pulsatile) and irrelevant pixels in the scene. Here, we propose a signal fusion framework, FusionPPG, for extracting a blood pulse waveform signal with strong temporal fidelity from a scene without requiring anatomical priors. The extraction problem is posed as a Bayesian least squares fusion problem, and solved using a novel probabilistic pulsatility model that incorporates both physiologically derived spectral and spatial waveform priors to identify pulsatility characteristics in the scene. Evaluation was performed on a 24-participant sample with various ages (9-60 years) and body compositions (fat% 30.0 ± 7.9, muscle% 40.4 ± 5.3, BMI 25.5 ± 5.2 kg·m(-2)). Experimental results show stronger matching to the ground-truth blood pulse waveform signal compared to the FaceMeanPPG (p waveform via temporal analysis.
Bustos, Cesar; Sandeen, Ben; Chennakesavalu, Shriram; Littenberg, Tyson; Farr, Ben; Kalogera, Vassiliki
2016-01-01
Gravitational Waves (GWs) were predicted by Einstein's Theory of General Relativity as ripples in space-time that propagate outward from a source. Strong GW sources consist of compact binary systems such as Binary Neutron Stars (BNS) or Binary Black Holes (BBHs) that experience orbital shrinkage (inspiral) and eventual merger. Indirect evidence for the existence of GWs has been obtained through radio pulsar studies in BNS systems. A study of BBHs and other compact objects has limitations in the electromagnetic spectrum, therefore direct detections of GWs will open a new window into their nature. The effort targeting direct GWs detection is anchored on the development of a detector known as Advanced LIGO (Laser Interferometer Gravitational Wave Observation). Although detecting GW sources represents an anticipated breakthrough in physics, making GW astrophysics a reality critically relies on our ability to determine and measure the physical parameters associated with GW sources. We use Markov Chain Monte Carlo (MCMC) simulations on high-performance computing clusters for parameter estimation on high dimensional spaces (GW sources - 15 parameters). The quality of GW parameter estimation greatly depends on having the best possible knowledge of the expected waveform. Unfortunately, BBH GW production is very complex and our best waveforms are not valid across the full parameter space. With large-scale simulations we examine quantitatively the limitations of these waveforms in terms of extracting the astrophysical properties of BBH GW sources. We find that current waveforms are inadequate for BBH of unequal masses and demonstrate that improved waveforms are critically needed.
Directory of Open Access Journals (Sweden)
Wang Wen-qin
2015-02-01
Full Text Available The waveforms used in Multiple-Input Multiple-Output (MIMO Synthetic Aperture Radar (SAR should have a large time-bandwidth product and good ambiguity function performance. A scheme to design multiple orthogonal MIMO SAR Orthogonal Frequency Division Multiplexing (OFDM chirp waveforms by combinational sparse matrix and correlation optimization is proposed. First, the problem of MIMO SAR waveform design amounts to the associated design of hopping frequency and amplitudes. Then a iterative exhaustive search algorithm is adopted to optimally design the code matrix with the constraints minimizing the block correlation coefficient of sparse matrix and the sum of cross-correlation peaks. And the amplitudes matrix are adaptively designed by minimizing the cross-correlation peaks with the genetic algorithm. Additionally, the impacts of waveform number, hopping frequency interval and selectable frequency index are also analyzed. The simulation results verify the proposed scheme can design multiple orthogonal large time-bandwidth product OFDM chirp waveforms with low cross-correlation peak and sidelobes and it improves ambiguity performance.
Fast Evolution and Waveform Generator for Extreme-Mass-Ratio Inspirals in Equatorial-Circular Orbits
Han, Wen-Biao
2016-01-01
In this paper we discuss the development of a fast and accurate waveform model for the quasi-circular orbital evolution of extreme-mass-ratio-inspirals (EMRIs). This model simply employs the data of a few numerical Teukoulsky-based energy fluxes and waveforms to fit out a set of polynomials for the entire fluxes and waveforms. These obtained polynomials are accurate enough in the entire evolution domain, and much more accurate than the resummation post-Newtonian (PN) energy fluxes and waveforms, especially when the spin of a black hole becomes large. The dynamical equation we adopted for orbital revolution is the effective-one-body (EOB) formalism. Because of the simplified expressions, the efficiency of calculating the orbital evolution with our polynomials is also better than the traditional method which uses the resummed PN analytical fluxes. Our model should be useful in calculation of waveform templates of EMRIs for the gravitational wave detectors such as the evolved Laser Interferometer Space Antenna (...
Computational and methodological developments towards 3D full waveform inversion
Etienne, V.; Virieux, J.; Hu, G.; Jia, Y.; Operto, S.
2010-12-01
Full waveform inversion (FWI) is one of the most promising techniques for seismic imaging. It relies on a formalism taking into account every piece of information contained in the seismic data as opposed to more classical techniques such as travel time tomography. As a result, FWI is a high resolution imaging process able to reach a spatial accuracy equal to half a wavelength. FWI is based on a local optimization scheme and therefore the main limitation concerns the starting model which has to be closed enough to the real one in order to converge to the global minimum. Another counterpart of FWI is the required computational resources when considering models and frequencies of interest. The task becomes even more tremendous when one tends to perform the inversion using the elastic equation instead of using the acoustic approximation. This is the reason why until recently most studies were limited to 2D cases. In the last few years, due to the increase of the available computational power, FWI has focused a lot of interests and continuous efforts towards inversion of 3D models, leading to remarkable applications up to the continental scale. We investigate the computational burden induced by FWI in 3D elastic media and propose some strategic features leading to the reduction of the numerical cost while providing a great flexibility in the inversion parametrization. First, in order to release the memory requirements, we developed our FWI algorithm in the frequency domain and take benefit of the wave-number redundancy in the seismic data to process a quite reduced number of frequencies. To do so, we extract frequency solutions from time marching techniques which are efficient for 3D structures. Moreover, this frequency approach permits a multi-resolution strategy by proceeding from low to high frequencies: the final model at one frequency is used as the starting model for the next frequency. This procedure overcomes partially the non-linear behavior of the inversion
Benkler, Erik; Telle, Harald R.
2007-06-01
An improved phase-locked loop (PLL) for versatile synchronization of a sampling pulse train to an optical data stream is presented. It enables optical sampling of the true waveform of repetitive high bit-rate optical time division multiplexed (OTDM) data words such as pseudorandom bit sequences. Visualization of the true waveform can reveal details, which cause systematic bit errors. Such errors cannot be inferred from eye diagrams and require word-synchronous sampling. The programmable direct-digital-synthesis circuit used in our novel PLL approach allows flexible adaption of virtually any problem-specific synchronization scenario, including those required for waveform sampling, for jitter measurements by slope detection, and for classical eye-diagrams. Phase comparison of the PLL is performed at 10-GHz OTDM base clock rate, leading to a residual synchronization jitter of less than 70 fs.
Aligned spin neutron star-black hole mergers: a gravitational waveform amplitude model
Pannarale, Francesco; Kyutoku, Koutarou; Lackey, Benjamin D; Shibata, Masaru
2015-01-01
The gravitational radiation emitted during the merger of a black hole with a neutron star is rather similar to the radiation from the merger of two black holes when the neutron star is not tidally disrupted. When tidal disruption occurs, gravitational waveforms can be broadly classified in two groups, depending on the spatial extent of the disrupted material. Extending previous work by some of us, here we present a phenomenological model for the gravitational waveform amplitude in the frequency domain encompassing the three possible outcomes of the merger: no tidal disruption, "mild" and "strong" tidal disruption. The model is calibrated to 134 general-relativistic numerical simulations of binaries where the black hole spin is either aligned or antialigned with the orbital angular momentum. All simulations were produced using the SACRA code and piecewise polytropic neutron star equations of state. The present model can be used to determine when black-hole binary waveforms are sufficient for gravitational-wave...
Energy Technology Data Exchange (ETDEWEB)
Beleznai, Sz; Mihajlik, G; Richter, P [Department of Atomic Physics, Budapest University of Technology and Economics, 3-9.Muegyetem rkp., Budapest H-1111 (Hungary); Maros, I; Balazs, L, E-mail: beleznai@dept.phy.bme.h [GE Consumer and Industrial-Lighting, 77 Vaci ut, Budapest H-1344 (Hungary)
2010-01-13
The application of a high frequency ({approx}2.5 MHz) burst (amplitude-modulated sinusoidal) excitation voltage waveform is investigated for driving a fluorescent dielectric barrier discharge (DBD) light source. The excitation waveform presents a novel method for generating spatially stable homogeneous Xe DBD possessing a high conversion efficiency from electrical energy to VUV Xe{sub 2}{sup *} excimer radiation ({approx}172 nm), even at a significantly higher electrical energy deposition than realized by pulsed excitation. Simulation and experimental results predict discharge efficiencies around 60%. Lamp efficacy above 74 lm W{sup -1} has been achieved. VUV emission and loss mechanisms are investigated extensively and the performance of burst and pulsed waveforms is compared both theoretically and experimentally.
Beleznai, Sz; Mihajlik, G.; Maros, I.; Balázs, L.; Richter, P.
2010-01-01
The application of a high frequency (~2.5 MHz) burst (amplitude-modulated sinusoidal) excitation voltage waveform is investigated for driving a fluorescent dielectric barrier discharge (DBD) light source. The excitation waveform presents a novel method for generating spatially stable homogeneous Xe DBD possessing a high conversion efficiency from electrical energy to VUV Xe_{2}^{\\ast} excimer radiation (~172 nm), even at a significantly higher electrical energy deposition than realized by pulsed excitation. Simulation and experimental results predict discharge efficiencies around 60%. Lamp efficacy above 74 lm W-1 has been achieved. VUV emission and loss mechanisms are investigated extensively and the performance of burst and pulsed waveforms is compared both theoretically and experimentally.
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."
Waveform Retracking and Emulation Experiment Analysis of Synthetic Aperture Radar Altimeter
Directory of Open Access Journals (Sweden)
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.
Mishra, Chandra Kant; Iyer, Bala R
2015-01-01
We compute the instantaneous contributions to the spherical harmonic modes of gravitational waveforms from compact binary systems in general orbits up to the third post-Newtonian order. We further extend these results for compact binaries in quasi-elliptical orbits using the 3PN quasi-Keplerian representation of the conserved dynamics of compact binaries in eccentric orbits. Using the multipolar post-Minkowskian formalism, starting from the different mass and current type multipole moments, we compute the spin weighted spherical harmonic decomposition of the instantaneous part of the gravitational waveform. These are terms which are functions of the retarded time and do not depend on the history of the binary evolution. Together with the hereditary part, which depends on the binary's dynamical history, these waveforms form the basis for construction of accurate templates for the detection of gravitational wave signals from binaries moving in quasi-elliptical orbits.
Reduction of edge effect on disk electrodes by optimized current waveform.
Wang, Boshuo; Petrossians, Artin; Weiland, James D
2014-08-01
Rectangular pulses applied to disk electrodes result in high current density at the edges of the disk, which can lead to electrode corrosion and tissue damage. We explored a method for reducing current density and corrosion, by varying the leading edge of the current pulse. Finite-element modeling and mathematical analysis were used to predict an optimal waveform that reduces current density at the edge while also maintaining short pulse duration. An approximation of the optimized waveform was implemented experimentally and applied to platinum disk electrodes. Surface analysis using energy-dispersive spectroscopy showed significant reduction of corrosion on the periphery of these electrodes after pulsing, compared to those pulsed with the control rectangular waveform.
Waveform inversion with exponential damping using a deconvolution-based objective function
Choi, Yun Seok
2016-09-06
The lack of low frequency components in seismic data usually leads full waveform inversion into the local minima of its objective function. An exponential damping of the data, on the other hand, generates artificial low frequencies, which can be used to admit long wavelength updates for waveform inversion. Another feature of exponential damping is that the energy of each trace also exponentially decreases with source-receiver offset, where the leastsquare misfit function does not work well. Thus, we propose a deconvolution-based objective function for waveform inversion with an exponential damping. Since the deconvolution filter includes a division process, it can properly address the unbalanced energy levels of the individual traces of the damped wavefield. Numerical examples demonstrate that our proposed FWI based on the deconvolution filter can generate a convergent long wavelength structure from the artificial low frequency components coming from an exponential damping.
Waveform control method for mitigating harmonics of inverter systems with nonlinear load
DEFF Research Database (Denmark)
Wang, Haoran; Zhu, Guorong; Fu, Xiaobin;
2015-01-01
DC power systems connecting to single-phase DC/AC inverters with nonlinear loads will have their DC sources being injected with AC ripple currents containing a low-frequency component at twice the output voltage frequency of the inverter and also other current harmonics. Such a current may create...... instability in the DC power system, lower its efficiency, and shorten the lifetime of the DC source. This paper presents a general waveform control method that can mitigate the injection of the low-frequency ripple current by the single-phase DC/AC inverter into the DC source. It also discusses the inhibiting...... ability of the waveform control method on other coexisting harmonics, while the DC source delivers AC power to a nonlinear load. With the application of the waveform control, the average DC output power is supplied by the DC source, while the other harmonics pulsation power can be confined to the AC side...
Digital architecture for a piecewise-linear arbitrary-waveform generator
Indian Academy of Sciences (India)
VICTOR M JIMENEZ-FERNANDEZ; HECTOR VAZQUEZ-LEAL; PABLO S LUNA-LOZANO; J L VAZQUEZ-BELTRAN; G GARCIA-SANTIAGO; E VALDES-ORTEGA
2016-08-01
In this paper a digital architecture for generating piecewise-linear arbitrary waveforms is presented. The proposed design is able to generate a piecewise-linear periodic signal by only using a minimum number of input data (breakpoints). The generator circuit implements a hybrid scheme which takes advantage of two methods: the purely piecewise-linear interpolation and the lookup-table structure. From the piecewise-linear method exploits the characteristic of a reduced memory requirement as well as the capability of automatically construct a waveform by repetitive (iterative) function evaluations. From lookup-table makes use of the simplicity in hardware implementation and the higher processing speed. In order to verify the performance of thisproposal, three piecewise-linear waveforms have been successfully implemented in a ATMEGA32 microcontroller. Experimental results show a fast execution speed and a reduced memory demand in the proposed circuit realization.
Institute of Scientific and Technical Information of China (English)
WANG Fu-yun; ZHANG Xian-kang
2006-01-01
A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding (DSS) waveform data. General reflection and transmission synthetic seismogram algorithm, which is capable of calculating the response of thin alternating high and low velocity layers, is applied as a solution for forward modeling, and the genetic algorithm is used to find the optimal solution of the inverse problem. Numerical tests suggest that the method has the capability of resolving low-velocity layers, thin alternating high and low velocity layers, and noise suppression. Waveform inversion using P-wave records from Zeku, Xiahe and Lintao shots in the seismic wide-angle reflection/refraction survey along northeastern Qinghai-Xizang (Tibeteau) Plateau has revealed fine structures of the bottom of the upper crust and alternating layers in the middle/lower crust and topmost upper mantle.
Waveform inversion of lateral velocity variation from wavefield source location perturbation
Choi, Yun Seok
2013-09-22
It is challenge in waveform inversion to precisely define the deep part of the velocity model compared to the shallow part. The lateral velocity variation, or what referred to as the derivative of velocity with respect to the horizontal distance, with well log data can be used to update the deep part of the velocity model more precisely. We develop a waveform inversion algorithm to obtain the lateral velocity variation by inverting the wavefield variation associated with the lateral shot location perturbation. The gradient of the new waveform inversion algorithm is obtained by the adjoint-state method. Our inversion algorithm focuses on resolving the lateral changes of the velocity model with respect to a fixed reference vertical velocity profile given by a well log. We apply the method on a simple-dome model to highlight the methods potential.
On Ground Surface Extraction Using Full-Waveform Airborne Laser Scanner for Cim
Nakano, K.; Chikatsu, H.
2015-05-01
Satellite positioning systems such as GPS and GLONASS have created significant changes not only in terms of spatial information but also in the construction industry. It is possible to execute a suitable construction plan by using a computerized intelligent construction. Therefore, an accurate estimate of the amount of earthwork is important for operating heavy equipment, and measurement of ground surface with high accuracy is required. A full-waveform airborne laser scanner is expected to be capable of improving the accuracy of ground surface extraction for forested areas, in contrast to discrete airborne laser scanners, as technological innovation. For forested areas, fundamental studies for construction information management (CIM) were conducted to extract ground surface using full-waveform airborne laser scanners based on waveform information.
Real-Time Source Classification with an Waveform Parameter Filtering of Acoustic Emission Signals
Energy Technology Data Exchange (ETDEWEB)
Cho, Seung Hyun; Park, Jae Ha; Ahn, Bong Young [Chonnam National University, Gwangju (Korea, Republic of)
2011-04-15
The acoustic emission(AE) technique is a well established method to carry out structural health monitoring(SHM) of large structures. However, the real-time monitoring of the crack growth in the roller coaster support structures is not easy since the vehicle operation produces very large noise as well as crack growth. In this investigation, we present the waveform parameter filtering method to classify acoustic sources in real-time. This method filtrates only the AE hits by the target acoustic source as passing hits in a specific parameter band. According to various acoustic sources, the waveform parameters were measured and analyzed to verify the present filtering method. Also, the AE system employing the waveform parameter filter was manufactured and applied to the roller coaster support structure in an actual amusement park
ON GROUND SURFACE EXTRACTION USING FULL-WAVEFORM AIRBORNE LASER SCANNER FOR CIM
Directory of Open Access Journals (Sweden)
K. Nakano
2015-05-01
Full Text Available Satellite positioning systems such as GPS and GLONASS have created significant changes not only in terms of spatial information but also in the construction industry. It is possible to execute a suitable construction plan by using a computerized intelligent construction. Therefore, an accurate estimate of the amount of earthwork is important for operating heavy equipment, and measurement of ground surface with high accuracy is required. A full-waveform airborne laser scanner is expected to be capable of improving the accuracy of ground surface extraction for forested areas, in contrast to discrete airborne laser scanners, as technological innovation. For forested areas, fundamental studies for construction information management (CIM were conducted to extract ground surface using full-waveform airborne laser scanners based on waveform information.
A CLASS OF BAND-LIMITED CHIP WAVEFORMS FOR DS-CDMA SYSTEMS
Institute of Scientific and Technical Information of China (English)
Song Rongfang; Bi Guangguo; Xie Daxiong
2007-01-01
In Direct Sequence Code Division Multiple Access (DS-CDMA) systems, the chip waveform affects the implementation, system bandwidth, envelope uniformity, eye pattern and Multiple user Access Interference (MAI). In this paper, based on an elementary density function of a second order polynomial, a class of second order continuity pulses is proposed. From this class of pulses,we can find some members having faster decaying rate, bigger eye opening, more uniform envelope and stronger anti-MAI capability than the Nyquist waveform. The normalized-bandwidth-pulseshape-factor product, the decaying rate of the tail of the time waveform, the opening of the eye diagram, and the envelope uniformity of the second order continuity pulses are addressed in the paper that provide the basic information for the selection of the chip pulse for CDMA systems.
Hinder, Ian; Boyle, Michael; Etienne, Zachariah B; Healy, James; Johnson-McDaniel, Nathan K; Nagar, Alessandro; Nakano, Hiroyuki; Pan, Yi; Pfeiffer, Harald P; Pürrer, Michael; Reisswig, Christian; Scheel, Mark A; Sperhake, Ulrich; Szilágyi, Bela; Tichy, Wolfgang; Wardell, Barry; Zenginoglu, Anıl; Alic, Daniela; Bernuzzi, Sebastiano; Bode, Tanja; Brügmann, Bernd; Buchman, Luisa T; Campanelli, Manuela; Chu, Tony; Damour, Thibault; Grigsby, Jason D; Hannam, Mark; Haas, Roland; Hemberger, Daniel A; Husa, Sascha; Kidder, Lawrence E; Laguna, Pablo; London, Lionel; Lovelace, Geoffrey; Lousto, Carlos O; Marronetti, Pedro; Matzner, Richard A; Mösta, Philipp; Mroué, Abdul; Müller, Doreen; Mundim, Bruno C; Nerozzi, Andrea; Paschalidis, Vasileios; Pollney, Denis; Reifenberger, George; Rezzolla, Luciano; Shapiro, Stuart L; Shoemaker, Deirdre; Taracchini, Andrea; Taylor, Nicholas W; Teukolsky, Saul A; Thierfelder, Marcus; Witek, Helvi; Zlochower, Yosef
2014-01-01
The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a joint effort between members of the numerical relativity, analytical relativity and gravitational-wave data analysis communities. The goal of the NRAR collaboration is to produce numerical-relativity simulations of compact binaries and use them to develop accurate analytical templates for the LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and extracting astrophysical information from them. We describe the results of the first stage of the NRAR project, which focused on producing an initial set of numerical waveforms from binary black holes with moderate mass ratios and spins, as well as one non-spinning binary configuration which has a mass ratio of 10. All of the numerical waveforms are analysed in a uniform and consistent manner, with numerical errors evaluated using an analysis code created by members of the NRAR collaboration. We compare previously-calibrated, non-precessing analytical waveforms, notably the ...
Localized temporal variation of Earth's inner-core boundary from high-quality waveform doublets
Xin, Danhua
2016-04-01
The accurate determination of the topography of an Earth's internal boundary is difficult because of the possible trade-off with the velocity of the media above it. Here we use waveform-doublet method to map the ICB topography. A waveform doublet is a pair of earthquakes occurring at essentially the same spatial position and received by the same station with high similarity in their waveforms (Poupinet et al. 1984), which make the exact detection of the ICB topography possible. In this study, we used this method to detect temporal change of the ICB using doublets from the Western Pacific (WP) area to increase global coverage of the ICB. Compared with previous study using doublets from South Sandwich Islands (SSI) (Song and Dai, 2008), the new samples showed negligible temporal change of the ICB.
:,; Abbott, B P; Abbott, R; Abbott, T; Abernathy, M R; Accadia, T; Acernese, F; Ackley, K; Adams, C; Adams, T; Addesso, P; Adhikari, R X; Affeldt, C; Agathos, M; Aggarwal, N; Aguiar, O D; Ain, A; Ajith, P; Alemic, A; Allen, B; Allocca, A; Amariutei, D; Andersen, M; Anderson, R; Anderson, S B; Anderson, W G; Arai, K; Araya, M C; Arceneaux, C; Areeda, J; Aston, S M; Astone, P; Aufmuth, P; Aulbert, C; Austin, L; Aylott, B E; Babak, S; Baker, P T; Ballardin, G; Ballmer, S W; Barayoga, J C; Barbet, M; Barish, B C; Barker, D; Barone, F; Barr, B; Barsotti, L; Barsuglia, M; Barton, M A; Bartos, I; Bassiri, R; Basti, A; Batch, J C; Bauchrowitz, J; Bauer, Th S; Behnke, B; Bejger, M; Beker, M G; Belczynski, C; Bell, A S; Bell, C; Bergmann, G; Bersanetti, D; Bertolini, A; Betzwieser, J; Beyersdorf, P T; Bilenko, I A; Billingsley, G; Birch, J; Biscans, S; Bitossi, M; Bizouard, M A; Black, E; Blackburn, J K; Blackburn, L; Blair, D; Bloemen, S; Blom, M; Bock, O; Bodiya, T P; Boer, M; Bogaert, G; Bogan, C; Bond, C; Bondu, F; Bonelli, L; Bonnand, R; Bork, R; Born, M; Boschi, V; Bose, Sukanta; Bosi, L; Bradaschia, C; Brady, P R; Braginsky, V B; Branchesi, M; Brau, J E; Briant, T; Bridges, D O; Brillet, A; Brinkmann, M; Brisson, V; Brooks, A F; Brown, D A; Brown, D D; Brückner, F; Buchman, S; Bulik, T; Bulten, H J; Buonanno, A; Burman, R; Buskulic, D; Buy, C; Cadonati, L; Cagnoli, G; Bustillo, J Calderón; Calloni, E; Camp, J B; Campsie, P; Cannon, K C; Canuel, B; Cao, J; Capano, C D; Carbognani, F; Carbone, L; Caride, S; Castiglia, A; Caudill, S; Cavaglià, M; Cavalier, F; Cavalieri, R; Celerier, C; Cella, G; Cepeda, C; Cesarini, E; Chakraborty, R; Chalermsongsak, T; Chamberlin, S J; Chao, S; Charlton, P; Chassande-Mottin, E; Chen, X; Chen, Y; Chincarini, A; Chiummo, A; Cho, H S; Chow, J; Christensen, N; Chu, Q; Chua, S S Y; Chung, S; Ciani, G; Clara, F; Clark, J A; Cleva, F; Coccia, E; Cohadon, P -F; Colla, A; Collette, C; Colombini, M; Cominsky, L; Constancio, M; Conte, A; Cook, D; Corbitt, T R; Cordier, M; Cornish, N; Corpuz, A; Corsi, A; Costa, C A; Coughlin, M W; Coughlin, S; Coulon, J -P; Countryman, S; Couvares, P; Coward, D M; Cowart, M; Coyne, D C; Coyne, R; Craig, K; Creighton, J D E; Crowder, S G; Cumming, A; Cunningham, L; Cuoco, E; Dahl, K; Canton, T Dal; Damjanic, M; Danilishin, S L; D'Antonio, S; Danzmann, K; Dattilo, V; Daveloza, H; Davier, M; Davies, G S; Daw, E J; Day, R; Dayanga, T; Debreczeni, G; Degallaix, J; Deléglise, S; Del Pozzo, W; Denker, T; Dent, T; Dereli, H; Dergachev, V; De Rosa, R; DeRosa, R T; DeSalvo, R; Dhurandhar, S; Díaz, M; Di Fiore, L; Di Lieto, A; Di Palma, I; Di Virgilio, A; Donath, A; Donovan, F; Dooley, K L; Doravari, S; Dossa, S; Douglas, R; Downes, T P; Drago, M; Drever, R W P; Driggers, J C; Du, Z; Dwyer, S; Eberle, T; Edo, T; Edwards, M; Effler, A; Eggenstein, H; Ehrens, P; Eichholz, J; Eikenberry, S S; Endrőczi, G; Essick, R; Etzel, T; Evans, M; Evans, T; Factourovich, M; Fafone, V; Fairhurst, S; Fang, Q; Farinon, S; Farr, B; Farr, W M; 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Heptonstall, A W; Heurs, M; Hewitson, M; Hild, S; Hoak, D; Hodge, K A; Holt, K; Hooper, S; Hopkins, P; Hosken, D J; Hough, J; Howell, E J; Hu, Y; Hughey, B; Husa, S; Huttner, S H; Huynh, M; Huynh-Dinh, T; Ingram, D R; Inta, R; Isogai, T; Ivanov, A; Iyer, B R; Izumi, K; Jacobson, M; James, E; Jang, H; Jaranowski, P; Ji, Y; Jiménez-Forteza, F; Johnson, W W; Jones, D I; Jones, R; Jonker, R J G; Ju, L; K, Haris; Kalmus, P; Kalogera, V; Kandhasamy, S; Kang, G; Kanner, J B; Karlen, J; Kasprzack, M; Katsavounidis, E; Katzman, W; Kaufer, H; Kawabe, K; Kawazoe, F; Kéfélian, F; Keiser, G M; Keitel, D; Kelley, D B; Kells, W; Khalaidovski, A; Khalili, F Y; Khazanov, E A; Kim, C; Kim, K; Kim, N; Kim, N G; Kim, Y -M; King, E J; King, P J; Kinzel, D L; Kissel, J S; Klimenko, S; Kline, J; Koehlenbeck, S; Kokeyama, K; Kondrashov, V; Koranda, S; Korth, W Z; Kowalska, I; Kozak, D B; Kremin, A; Kringel, V; Krishnan, B; Królak, A; Kuehn, G; Kumar, A; Kumar, P; Kumar, R; Kuo, L; Kutynia, A; Kwee, P; Landry, M; 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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...
Influence of Asymmetrical Waveform on Low-Cycle Fatigue Life of Micro Solder Joint
Kanda, Yoshihiko; Kariya, Yoshiharu
2010-02-01
The effects of waveform symmetry on the low-cycle fatigue life of the Sn-3.0Ag-0.5Cu alloy have been investigated, using micro solder joint specimens with approximately the same volume of solder as is used in actual products. Focusing on crack initiation life, fatigue tests on Sn-Ag-Cu micro solder joints using asymmetrical triangular waveforms revealed no significant reduction in fatigue life. A slight reduction in fatigue life at low strain ranges caused by an increase in the fatigue ductility exponent, which is the result of a weakening microstructure due to loads applied at high temperature for long testing time, was observed. This was due to the fact that grain boundary damage, which has been reported in large-size specimens subjected to asymmetrical triangular waveforms, does not occur in Sn-Ag-Cu micro size solder joints with only a small number of crystal grain boundaries.
Power-Efficient Ultra-Wideband Waveform Design Considering Radio Channel Effects
Directory of Open Access Journals (Sweden)
Yipeng Liu
2011-04-01
Full Text Available This paper presents a power-efficient maskconstrained ultra-wideband (UWB waveform design with radio channel effects taken into consideration. Based on a finite impulse response (FIR filter, we develop a convex optimization model with respect to the autocorrelation of the filter coefficients to optimize the transmitted signal power spectrum, subject to a regulatory emission mask. To improve power efficiency, effects of transmitter radio frequency (RF components are included in the optimization of the transmitter-output waveform, and radio propagation effects are considered for obtaining the most efficient waveform at the receiver. Optimum coefficients of the FIR filter are obtained through spectral factorization of their autocorrelations. Simulation results show that the proposed method is able to maximize the transmitted UWB signal power under mask constraints set by regulatory authorities, while mitigating the power loss caused by channel attenuations.
Institute of Scientific and Technical Information of China (English)
Yang Lijun; Feng Shengqiang; Dong Tianshun; Li Huan
2007-01-01
A simulation model is introduced about the non-linearity process of short-circuiting transfer in CO2 arc welding for displaying the interaction between the inverter power source and welding arc under waveform control. In the simulation model, the feedback signals of current and voltage are taken respectively at the different phase in a short circuit periodic time and applied to the PWM(pulse width modulation) module in a model of inverter power source to control the output of power source. The simulation operation about the dynamic process of CO2 short-circuiting transfer welding is implemented on the founded simulation model with a peak arc current of 400 A and a peak voltage of 35 V, producing the dynamic arc waveforms which can embody the effect of inverter harmonic wave. The simulating waveforms are close to that of welding experiments.
Gravitational waveforms in scalar-tensor gravity at 2PN relative order
Sennett, Noah; Buonanno, Alessandra
2016-01-01
We compute the gravitational waveform from a binary system in scalar-tensor gravity at 2PN relative order. We restrict our calculation to non-spinning binary systems on quasi-circular orbits and compute the spin-weighted spherical modes of the radiation. The evolution of the phase of the waveform is computed in the time and frequency domains. The emission of dipolar radiation is the lowest-order dissipative process in scalar-tensor gravity. However, stringent constraints set by current astrophysical observations indicate that this effect is subdominant to quadrupolar radiation for most prospective gravitational-wave sources. We compute the waveform for systems whose inspiral is driven by: (a) dipolar radiation (e.g., binary pulsars or spontaneously scalarized systems) and (b) quadrupolar radiation (e.g., typical sources for space-based and ground-based detectors).
Kitov, Ivan; Turuntaev, Sergey; Konovalov, Alexei; Stepnov, Andrey
2016-04-01
Unusually long duration of seismic activity (more than 20 years) was observed in the aftershock area of the 1995 Neftegorsk, Sakhalin, Russia catastrophic earthquake (Ms=7.6). To study the phenomena, we have processed seismic data from 130 events occurred within that area as measured between 2006 and 2015. In order to improve the accuracy of relative location and magnitude estimation of these events we have applied new techniques based on waveform cross correlation. We use 7 three-component (3-C) seismic stations which detected most of these events. Three-component waveform templates were prepared for these stations from those events which had signals with SNR>5 at vertical channels. The events with 3 and more templates are used as master-events for waveform cross correlation. Overall, the re-estimated location and magnitudes demonstrate higher precisions and are used for the statistical analysis and numerical modelling of seismo-tectonic regime within the studied zone.
Amelard, Robert; Wong, Alexander
2016-01-01
Photoplethysmographic imaging is a camera-based solution for non-contact cardiovascular monitoring from a distance. This technology enables monitoring in situations where contact-based devices may be problematic or infeasible, such as ambulatory, sleep, and multi-individual monitoring. However, extracting the blood pulse waveform signal is challenging due to the unknown mixture of relevant (pulsatile) and irrelevant pixels in the scene. Here, we design and implement a signal fusion framework, FusionPPG, for extracting a blood pulse waveform signal with strong temporal fidelity from a scene without requiring anatomical priors (e.g., facial tracking). The extraction problem is posed as a Bayesian least squares fusion problem, and solved using a novel probabilistic pulsatility model that incorporates both physiologically derived spectral and spatial waveform priors to identify pulsatility characteristics in the scene. Experimental results show statistically significantly improvements compared to the FaceMeanPPG ...
Waveform sensitivity of electroreceptors in the pulse weakly electric fish Gymnotus omarorum.
Rodríguez-Cattaneo, Alejo; Aguilera, Pedro A; Caputi, Angel A
2017-02-15
As in most sensory systems electrosensory images in weakly electric fish are encoded in two parallel pathways, fast and slow. From the work on wave type electric fish these pathways are thought to encode the time and amplitude of electrosensory signals respectively. This article focuses on the primary afferents giving origin to the slow path of the pulse type weakly electric fish Gymnotus omarorum We found that burst duration coders respond with a high-frequency train of spikes to each electric organ discharge. They also show high sensitivity to phase-frequency distortions of the self-generated local electric field. We explored this sensitivity by manipulating the longitudinal impedance of a probe cylinder to modulate the stimulus waveform, while extracellularly recording isolated primary afferents. Resistive loads only affect the amplitude of the re-afferent signals without distorting the waveform. Capacitive loads cause large waveform distortions aside from amplitude changes. Stepping from a resistive to a capacitive load in such a way that the stimulus waveform was distorted, without changing its total energy, caused strong changes in latency, inter-spike interval and number of spikes of primary afferents responses. These burst parameters are well correlated suggesting that they may contribute synergistically in driving downstream neurons. This correlation also suggests that each receptor encodes a single parameter in the stimulus waveform. The finding of waveform distortion sensitivity is relevant because it may contribute to: a) enhance electroreceptive range in the peripheral "electrosensory field", b) a better identification of living preys at the "foveal electrosensory field" and c) to detect the presence and orientation of conspecifics. Our results also suggest a revision of the classical view of amplitude and time encoding by fast and slow pathways in pulse type electric fish.
Finite-fault analysis of the 2004 Parkfield, California, earthquake using Pnl waveforms
Mendoza, C.; Hartzell, S.
2008-01-01
We apply a kinematic finite-fault inversion scheme to Pnl displacement waveforms recorded at 14 regional stations (Δsingle Mw 5.0 aftershock. Slip is modeled on a rectangular fault subdivided into 2×2 km subfaults assuming a constant rupture velocity and a 0.5 sec rise time. A passband filter of 0.1–0.5 Hz is applied to both data and subfault responses prior to waveform inversion. The SGF inversions are performed such that the final seismic moment is consistent with the known magnitude (Mw 6.0) of the earthquake. For these runs, it is difficult to reproduce the entire Pnl waveform due to inaccuracies in the assumed crustal structure. Also, the misfit between observed and predicted vertical waveforms is similar in character for different rupture velocities, indicating that neither the rupture velocity nor the exact position of slip sources along the fault can be uniquely identified. The pattern of coseismic slip, however, compares well with independent source models derived using other data types, indicating that the SGF inversion procedure provides a general first-order estimate of the 2004 Parkfield rupture using the vertical Pnl records. The best-constrained slip model is obtained using the single-aftershock EGF approach. In this case, the waveforms are very well reproduced for both vertical and horizontal components, suggesting that the method provides a powerful tool for estimating the distribution of coseismic slip using the regional Pnl waveforms. The inferred slip model shows a localized patch of high slip (55 cm peak) near the hypocenter and a larger slip area (~50 cm peak) extending between 6 and 20 km to the northwest.
A seamless acquisition digital storage oscilloscope with three-dimensional waveform display.
Yang, Kuojun; Tian, Shulin; Zeng, Hao; Qiu, Lei; Guo, Lianping
2014-04-01
In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6,250,000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition.
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.
A seamless acquisition digital storage oscilloscope with three-dimensional waveform display
Energy Technology Data Exchange (ETDEWEB)
Yang, Kuojun, E-mail: kuojunyang@gmail.com; Guo, Lianping [School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu (China); School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore); Tian, Shulin; Zeng, Hao [School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu (China); Qiu, Lei [School of Electrical and Electronic Engineering, Nanyang Technological University (Singapore)
2014-04-15
In traditional digital storage oscilloscope (DSO), sampled data need to be processed after each acquisition. During data processing, the acquisition is stopped and oscilloscope is blind to the input signal. Thus, this duration is called dead time. With the rapid development of modern electronic systems, the effect of infrequent events becomes significant. To capture these occasional events in shorter time, dead time in traditional DSO that causes the loss of measured signal needs to be reduced or even eliminated. In this paper, a seamless acquisition oscilloscope without dead time is proposed. In this oscilloscope, three-dimensional waveform mapping (TWM) technique, which converts sampled data to displayed waveform, is proposed. With this technique, not only the process speed is improved, but also the probability information of waveform is displayed with different brightness. Thus, a three-dimensional waveform is shown to the user. To reduce processing time further, parallel TWM which processes several sampled points simultaneously, and dual-port random access memory based pipelining technique which can process one sampling point in one clock period are proposed. Furthermore, two DDR3 (Double-Data-Rate Three Synchronous Dynamic Random Access Memory) are used for storing sampled data alternately, thus the acquisition can continue during data processing. Therefore, the dead time of DSO is eliminated. In addition, a double-pulse test method is adopted to test the waveform capturing rate (WCR) of the oscilloscope and a combined pulse test method is employed to evaluate the oscilloscope's capture ability comprehensively. The experiment results show that the WCR of the designed oscilloscope is 6 250 000 wfms/s (waveforms per second), the highest value in all existing oscilloscopes. The testing results also prove that there is no dead time in our oscilloscope, thus realizing the seamless acquisition.
The effect of nonuniform motion on the Doppler spectrum of scattered continuous-wave waveforms
Gray, John E.; Addison, Stephen R.
2003-04-01
The Doppler effect is a widely treated phenomena in both radar and sonar for objects undergoing uniform motion. There are many different models (Censor has written a history of the subject) one can use to derive the Doppler effect. The treatment of non-uniform motion is not widely discussed in the literature of radar and sonar. Some authors argue it is negligible, while others refer to work dating back to Kelly in the early sixties. The treatment by Kelly, based on waveform analysis in acoustics, is difficult to justify in electromagnetism. Using the language of waveform analysis it is difficult to determine when approximations are justified by the physics of the waveform interaction and when they aren't. By returning to electromagnetic considerations in the derivation and subsequent analysis, issues associated with the correct physics and proper approximations become transparent. We present a straight forward analysis of the non-uniform Doppler effect based on the relativistic mirror (moving boundary) that is undergoing arbitrary motion. The resultant structure of the scattered waveform provides a simple representation of the effect of non-uniform motion on the scattered waveform that can be more easily analyzed. This work is a continuation of earlier work done by Censor, De Smedt, and Cooper. This analysis is independent of narrow-band assumptions so it is completely general. Non-uniform motion can produce two types of effects associated with the Doppler spectrum, a baseband line that isn't straight and micro-Doppler off of the baseband that produces complicated sideband behavior. Complicated baseband and micro-Doppler are illustrated by using the example of a particular waveform, the continuous wave (CW) which is analyzed for a number of examples of interest to the radar community. Application of this information is then discussed.
Okada, Kazunori; Kaga, Sanae; Mikami, Taisei; Masauzi, Nobuo; Abe, Ayumu; Nakabachi, Masahiro; Yokoyama, Shinobu; Nishino, Hisao; Ichikawa, Ayako; Nishida, Mutsumi; Murai, Daisuke; Hayashi, Taichi; Shimizu, Chikara; Iwano, Hiroyuki; Yamada, Satoshi; Tsutsui, Hiroyuki
2016-10-18
We analyzed the waveform of systolic strain and strain-rate curves to find a characteristic left ventricular (LV) myocardial contraction pattern in patients with hypertrophic cardiomyopathy (HCM), and evaluated the utility of these parameters for the differentiation of HCM and LV hypertrophy secondary to hypertension (HT). From global strain and strain-rate curves in the longitudinal and circumferential directions, the time from mitral valve closure to the peak strains (T-LS and T-CS, respectively) and the peak systolic strain rates (T-LSSR and T-CSSR, respectively) were measured in 34 patients with HCM, 30 patients with HT, and 25 control subjects. The systolic strain-rate waveform was classified into 3 patterns ("V", "W", and "√" pattern). In the HCM group, T-LS was prolonged, but T-LSSR was shortened; consequently, T-LSSR/T-LS ratio was distinctly lower than in the HT and control groups. The "√" pattern of longitudinal strain-rate waveform was more frequently seen in the HCM group (74 %) than in the control (4 %) and HT (20 %) groups. Similar but less distinct results were obtained in the circumferential direction. To differentiate HCM from HT, the sensitivity and specificity of the T-LSSR/T-LS ratio waveform were 85 and 63 %, and 74 and 80 %, respectively. In conclusion, in patients with HCM, a reduced T-LSSR/T-LS ratio and a characteristic "√"-shaped waveform of LV systolic strain rate was seen, especially in the longitudinal direction. The timing and waveform analyses of systolic strain rate may be useful to distinguish between HCM and HT.
Three-detector setup for PAL spectrometer based on DRS4 waveform digitizing board
Institute of Scientific and Technical Information of China (English)
安然; 丛龙翰; 叶邦角; 郭智荣; 陈祥磊; 代传波; 郭晓彬; 龚玉巍; 李清华; 任才; 刘艳芬; 郭俊清
2015-01-01
A digital three-detector positron lifetime spectrometer was developed. It consists of a DRS4 waveform digi-tizing board and three LaBr3 scintillation detectors coupled to XP2020Q photomultiplier tubes. DRS4 waveform digitizing allows data sampling at up to 5 GSPS with high amplitude resolution, with good time scale linearity and stability. In the triple-coincidence, the new system could reach a 195 ps time resolution, which is better than the conventional analog apparatus with the same detectors. This spectrometer can be applied to the other scintillation timing measurements with picoseconds accuracy.
Wu, Qi; Okabe, Yoji
2015-02-01
Fiber Bragg grating (FBG) demodulated by an erbium fiber laser (EFL) has been used for ultrasonic detection recently. However, due to the inherent relaxation oscillation (RO) of the EFL, the detected ultrasonic signals have large deformations, especially in the low-frequency range. We proposed a novel data processing method to reconstruct an actual ultrasonic waveform. The noise spectrum was smoothed first; the actual ultrasonic spectrum was then obtained by deconvolution in order to mitigate the influence of the RO of the EFL. We proved by experiment that this waveform reconstruction method has high precision, and demonstrated that the FBG sensor demodulated by the EFL will have large practical applications in nondestructive testing.
RADAR HRR PROFILING FOR GROUND MOVING TARGET USING PHASE-CODED AND HOPPED-FREQUENCY WAVEFORMS
Institute of Scientific and Technical Information of China (English)
Li Yan; Wang Changming
2007-01-01
To obtain the radar High Range Resolution (HRR) profile of the slowly moving ground target in strong clutter background, the Phase-Coded Hopped-Frequency (PCHF) waveform is proposed. By multiple-bursts coherent processing, the HRR profile synthesis, target velocity compensation and clutter compression can be accomplished simultaneously. The new waveform is shown to have good ability to suppress ground clutter and good Electronic Counter-CounterMeasures (ECCM) ability as well. The clutter compression performance of the proposed method is verified by the numerical results.
Signal waveform design to detect an underwater high-speed small target
Institute of Scientific and Technical Information of China (English)
YANG Chonglin; YAO Lan
2002-01-01
The problem of sonar signal waveform design to detect a high-speed small target in an underwater environment is discussed. From theoretical analysis, time-frequency hop signal is regarded as the most suitable signal waveform in this application. To get precise target parameter estimation ability, the signal should have high range-Doppler resolution performance.The results of signal analysis show that hop signal with frequency serial coding as Costas array has sharp ambiguity characteristic, so it can be used in an active sonar system to detect a high speed small target. A scheme of frequency coding is also presented.
Glenn Goddard TDRSS Waveform 1.1.3 On-Orbit Performance Report
Chelmins, David T.
2014-01-01
The objective of the Space Communications and Navigation (SCaN) Testbed is to study the development, testing, and operation of software defined radios (SDRs) and their associated appliations in the operational space environment to reduce cost and risk for future space missions. This report covers the results of on-orbit performance testing completed using the Glenn Goddard Tracking and Data Relay Satellite System (TDRSS) waveform version 1.1.3 in the ground and space environments. The Glenn Goddard TDRSS (GGT) waveform, operating on the SCaN Testbed Jet Propulsion Laboratory (JPL) SDR, is capable of a variety of data rates and frequencies, operating using Binary Phase Shift Keying (BPSK).
A signal denoising method for full-waveform LiDAR data
M.Azadbakht; Fraser, C.S.; Zhang, C.; Leach, J
2013-01-01
The lack of noise reduction methods resistant to waveform distortion can hamper correct and accurate decomposition in the processing of full-waveform LiDAR data. This paper evaluates a time-domain method for smoothing and reducing the noise level in such data. The Savitzky-Golay (S-G) approach approximates and smooths data by taking advantage of fitting a polynomial of degree d, using local least-squares. As a consequence of the integration of this method with the Singular Value Deco...
Microwave dynamic large signal waveform characterization of advanced InGaP HBT for power amplifiers
Institute of Scientific and Technical Information of China (English)
Zhao Lixin; Jin Zhi; Liu Xinyu
2009-01-01
In wireless mobile communications and wireless local area networks (WLAN), advanced lnGaP HBT with power amplifiers are key components. In this paper, the microwave large signal dynamic waveform characteristics of an advanced InGaP HBT are investigated experimentally for 5.8 GHz power amplifier applications. The microwave large signal waveform distortions at various input power levels, especially at large signal level, are investigated and the reasons are analyzed. The output power saturation is also explained. These analyses will be useful for power amplifier designs.