Sample records for joint time-frequency domain

  1. Joint time/frequency-domain inversion of reflection data for seabed geoacoustic profiles and uncertainties.

    PubMed

    Dettmer, Jan; Dosso, Stan E; Holland, Charles W

    2008-03-01

    This paper develops a joint time/frequency-domain inversion for high-resolution single-bounce reflection data, with the potential to resolve fine-scale profiles of sediment velocity, density, and attenuation over small seafloor footprints (approximately 100 m). The approach utilizes sequential Bayesian inversion of time- and frequency-domain reflection data, employing ray-tracing inversion for reflection travel times and a layer-packet stripping method for spherical-wave reflection-coefficient inversion. Posterior credibility intervals from the travel-time inversion are passed on as prior information to the reflection-coefficient inversion. Within the reflection-coefficient inversion, parameter information is passed from one layer packet inversion to the next in terms of marginal probability distributions rotated into principal components, providing an efficient approach to (partially) account for multi-dimensional parameter correlations with one-dimensional, numerical distributions. Quantitative geoacoustic parameter uncertainties are provided by a nonlinear Gibbs sampling approach employing full data error covariance estimation (including nonstationary effects) and accounting for possible biases in travel-time picks. Posterior examination of data residuals shows the importance of including data covariance estimates in the inversion. The joint inversion is applied to data collected on the Malta Plateau during the SCARAB98 experiment. PMID:18345819

  2. Joint Time-Frequency Spectrum Sensing for Cognitive Radio

    E-print Network

    Paris-Sud XI, Université de

    Joint Time-Frequency Spectrum Sensing for Cognitive Radio Wael Guib`ene and Aawatif Hayar EURECOM-frequency plane. Index Terms--Cognitive radio, sensing algorithm, Wigner Ville distribution , algebraic detector, joint time frequency detection. I. INTRODUCTION Cognitive Radio (CR) as introduced by Mitola [1

  3. Joint Time-Frequency Analysis of Ultra Wideband Radar Signals

    Microsoft Academic Search

    Hoi-Shun Lui; Nicholas V. Z. Shuley

    The time variant nature of an Ultra-Wideband (UWB) radar signal scattered from a radar target is well described throughout the literature. To study the behaviour of these transient signals, Joint Time-Frequency (TF) analysis is considered. Various Time-Frequency Distributions (TFDs) have been developed in the signal processing area over the last twenty years but little work has been done in a

  4. Joint time-frequency analysis of ultrashort soliton propagation in nonlinear optical fibers

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Azaña, J.

    2006-09-01

    In this work, the problem of propagation of ultrashort optical solitons through a non-linear optical fiber is investigated in the joint Time-Frequency (TF) domain using optimized representations [i.e. Wigner-Ville (WV) Distribution or WV-Spectrograms with reduced cross-term interferences]. Based on these optimized representations, complete numerical simulations for nonlinear propagation of solitons were carried out. In particular we have analyzed the evolution of second and third order solitons and soliton interaction in optical fibers using joint TF representations.

  5. UNDERDETERMINED BLIND SEPARATION OF AUDIO SOURCES IN TIME FREQUENCY DOMAIN

    Microsoft Academic Search

    K. Abed-Meraim; Y. Grenier

    This paper considers the blind separation of audio sources in the underdetermined case, where we have more sources than sensors. A recent algorithm applies time-frequency distri bu- tions (TFDs) to this problem and gives good separation per- formance in the case where sources are disjoint in the time- frequency (TF) plane. However, in the non-disjoint case, the reconstruction of the

  6. Time-frequency-domain analysis: one-dimensional phantom studies

    Microsoft Academic Search

    D. Nicholas

    1982-01-01

    Two methods have been adopted to date for investigating the interference effects resulting from the scattering of ultrasound by soft mammalian tissues; one involves the conversion of time-domain signals into the frequency-domain, where the broad spectral characteristics of a short acoustic pulse are utilised, whilst the other varies the orientation of the specimen with reference to the incident beam and

  7. Bubble Pulse Cancelation in the Time-Frequency Domain Using Warping Operators

    NASA Astrophysics Data System (ADS)

    Niu, Hai-Qiang; Zhang, Ren-He; Li, Zheng-Lin; Guo, Yong-Gang; He, Li

    2013-08-01

    The received shock waves produced by explosive charges are often polluted by bubble pulses in underwater acoustic experiments. A method based on warping operators is proposed to cancel the bubble pulses in the time-frequency domain. This is applied to the explosive data collected during the Yellow Sea experiment in November 2000. The original received signal is first transformed into a warped signal by warping operators. Then, the warped signal is analyzed in the time-frequency domain. Due to the different features between the shock waves and the bubble pulses in the time-frequency domain for the warped signal, the bubble pulses can be easily filtered out. Furthermore, the shock waves in the original time domain can be retrieved by the inverse warping transformation. The autocorrelation functions and the time-frequency representation show that the bubble pulses can be canceled effectively.

  8. Comparison of pulse and SFCW GPR in time, frequency and wavelet domain

    NASA Astrophysics Data System (ADS)

    De Pue, Jan; Van De Vijver, Ellen; Cornelis, Wim; Van Meirvenne, Marc

    2014-05-01

    Ground penetrating radar (GPR) systems operating in the time- or frequency domain are two fundamentally different concepts, pursuing the same objective: non-invasive characterization of the subsurface. The aim of this study is to compare the performance of these two GPR systems in the time, frequency and wavelet domain. The time domain GPR investigated is the Utilityscan DF. This is a ground coupled GPR with a digital dual-frequency antenna (300 and 800 MHz). The Geoscope GS3F and VX1213 antenna array from 3DRadar is the frequency domain GPR used in this comparison. It is an air coupled stepped frequency continuous wave (SFCW) GPR with a frequency bandwidth from 200 MHz to 3000 MHz. Using data from several test sites of various soil types, the data is evaluated in the time domain, the frequency domain and the wavelet domain. Each of these domains contains specific information regarding the data quality. Presenting the data in the time domain, allows visualizing the subsurface reflections. This makes it visible how strong the data is affected by internal interference, ringing and other noise. To compensate for the attenuation of the signal in time, automatic gain control is applied. The maximum of this gain function indicates the time where the signal is attenuated completely and noise becomes more dominant, corresponding with the maximal penetration depth of the different GPR systems. In the frequency domain, the data allows to investigate which frequencies contain most valuable information and which ones are affected by noise. Finally, by performing a wavelet transformation the data is transformed to the time-frequency domain. Due to frequency dependent attenuation of electromagnetic signals in the soil, low frequencies will be more dominant in deeper layers, and high frequencies will not be present anymore. This is determining for the range resolution of the data throughout the traveltime of the signal. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  9. Automatic de-noising of knee-joint vibration signals using adaptive time-frequency representations.

    PubMed

    Krishnan, S; Rangayyan, R M

    2000-01-01

    A novel de-noising method for improving the signal-to-noise ratio of knee-joint vibration signals (also known as vibro-arthrographic (VAG) signals) is proposed. The de-noising methods considered are based on signal decomposition techniques, such as wavelets, wavelet packets and the matching pursuit (MP) method. Performance evaluation with synthetic signals simulated with the characteristics expected of VAG signals indicates good de-noising results with the MP method. Statistical pattern classification of non-stationary signal features extracted from time-frequency distributions of 37 (19 normal and 18 abnormal) MP method-de-noised VAG signals shows a sensitivity of 83.3%, a specificity of 84.2% and an overall accuracy of 83.8%. PMID:10829383

  10. Joint Time/Frequency Analysis and Design of Spiral Antennas and Arrays for Ultra-Wideband Applications

    NASA Astrophysics Data System (ADS)

    Elmansouri, Mohamed Ali

    Ultra-wideband (UWB) systems transmit and receive extremely short pulses, permitting the corresponding antennas to distort their shape. Thus the design of an antenna for a UWB system plays an important role for the reliability and quality of communication. A UWB antenna design coalesces both the determination of conventional frequency domain parameters and the analysis of time domain response into a single overarching system requirement. While the former is needed to ensure system's sensitivity, the later is critical to minimize pulse distortion. Well-designed spiral antennas are known for their almost frequency independent characteristics; thus they are viable candidates for UWB systems from the frequency-domain side. However, due to their fundamental principles of operation, they are dispersive and arguments were made they should not be used for pulsed UWB applications (time-domain side). The presented research unequivocally proves that spiral antennas and various derivatives thereof, including arrays, can be excellent candidates for multi-functional time/frequency domain systems. A complete framework for joint frequency and time domain characterization of planar spiral antennas in UWB communication systems is developed first. By utilizing theory, simulations, and experiments, all essential to the analysis frameworks, the various hypotheses are comprehensively treated and relevant conclusions are established. The dispersion and pulse distortion of the conventional spiral antennas are characterized in the radiation and system modes and conclusions regarding the effects of geometrical parameters such as number of arms, mode of operations, etc., on time- and frequency-domain performance are derived for the first time. A method based on controlling the spiral's growth rate and input pulse shape is demonstrated as an effective approach to reduce the pulse distortion. Theoretical pre-distortion compensation method based on a frequency-dependent delay removal technique is employed and performance enhancement of spiral antennas as pulse radiators is successfully demonstrated. A novel spiral antenna topology, named combined power spiral, is derived from first principles to have simultaneously excellent time- and frequency-domain performances without any auxiliary hardware and/or pre-distortion compensation. The role of the reflective cavity backing on the performance of spiral antennas in time and frequency domains is investigated in order to achieve an efficient unidirectional UWB radiation. Resistively-loaded cavity-backed spirals are designed as a compromise for achieving simultaneously good time and frequency domain performances while maintaining high efficiency over the most of operating bandwidth. The lens loading approach is used as a way to further improve the spiral's gain and reduce the amplitude distortion associated with a typical communication channel. UWB spiral arrays based on the derived good time/frequency two- and four-arm spiral antennas are developed and analyzed in time and frequency domains. Multi-mode capabilities of four-arm spirals are used to engineer a dual-circularly polarized array embodiment. To make these arrays practically more desirable, novel feeding scheme which significantly reduces the beamformer complexity is proposed. Time and frequency scanning capabilities and the advantages of the proposed arrays for UWB communications are also discussed. The results of this thesis can pave the way for the use of spiral antennas in many non-traditional, for spiral antennas, applications across commercial and military sectors.

  11. UWB micro-doppler radar for human gait analysis using joint range-time-frequency representation

    NASA Astrophysics Data System (ADS)

    Wang, Yazhou; Fathy, Aly E.

    2013-05-01

    In this paper, we present a novel, standalone ultra wideband (UWB) micro-Doppler radar sensor that goes beyond simple range or micro-Doppler detection to combined range-time-Doppler frequency analysis. Moreover, it can monitor more than one human object in both line-of-sight (LOS) and through wall scenarios, thus have full human objects tracking capabilities. The unique radar design is based on narrow pulse transceiver, high speed data acquisition module, and wideband antenna array. For advanced radar post-data processing, joint range-time-frequency representation has been performed. Characteristics of human walking activity have been analyzed using the radar sensor by precisely tracking the radar object and acquiring range-time-Doppler information simultaneously. The UWB micro-Doppler radar prototype is capable of detecting Doppler frequency range from -180 Hz to +180 Hz, which allows a maximum target velocity of 9 m/s. The developed radar sensor can also be extended for many other applications, such as respiration and heartbeat detection of trapped survivors under building debris.

  12. Iterative Receiver in Time-Frequency Domain for Shallow Water Acoustic Channel

    NASA Astrophysics Data System (ADS)

    Zhao, Liang; Ge, Jianhua

    2012-03-01

    Inter-symbol interference (ISI) caused by multi-path propagation, especially in shallow water channel, degrades the performance of underwater acoustic (UWA) communication systems. In this paper, we combine soft minimum mean squared error (MMSE) equalization and the serially concatenated trellis coded modulation (SCTCM) decoding to develop an iterative receiver in time-frequency domain (TFD) for underwater acoustic point to point communications. Based on sound speed profile (SSP) measured in the lake and finite-element ray (FER) tracing method (Bellhop), the shallow water channel is constructed to evaluate the performance of the proposed iterative receiver. The results suggest that the proposed iterative receiver can reduce the calculation complexity of the equalizer and obtain better performance using less receiving elements.

  13. Time-frequency-domain dispersion measurement in rare earth doped large effective mode area multicore fibers

    NASA Astrophysics Data System (ADS)

    Baselt, T.; Taudt, Ch.; Hartmann, P.

    2014-03-01

    Ytterbium doped multicore fibers have been recently employed in the field of high power and Quasi-Gaussian beam lasers to design truly single-mode multicore fiber lasers. The special design of these fibers offers low bending loss even for compact high power lasers and amplifiers. Moreover, the Multi-core fiber amplifier possesses a large effective mode area which results in a significant decrease of the related nonlinear effects. In the paper, modal resolved group-velocity dispersion measurements in active multicore fibers are performed using time-frequency-domain white-light interferometry. A Mach-Zehnder-type interferometer with dual-channel detection in the spectral range from 0.4 ?m up to 1.7 ?m and a home-made supercontinuum source are used. Temporally resolved spectrograms recorded at distinct delay positions enable the detection of interference fringes for the equalizationwavelength. The group-velocity dispersion can be derived by applying a Sellmeier polynomial fit to the wavelength dependent differential group delay function. The dispersion parameters for several LMA fibers are investigated over a broad spectral range of about 1.3 ?m.

  14. Polarization studies in the UWB radar target response using joint Time-Frequency analysis

    Microsoft Academic Search

    Hoi-Shun Lui; Faisal Aldhubaib; Nicholas V. Z. Shuley

    2007-01-01

    The polarization dependent nature of ultra wideband (UWB) scattering from a radar target is studied using time-frequency (TF) analysis. The UWB frequency responses of the target under linear and circular polarization incidence are studied. The results demonstrate that the Q-factor of the resonant peaks vary as the incident polarization changes, indicating that different layer SEM poles are extracted for different

  15. 160-Gb/s Orthogonal Time-Frequency Domain Multiplexed QPSK for Ultra-High-spectral-Efficient Transmission

    E-print Network

    Kolner, Brian H.

    spectral efficiency up to log2(n) [b/s/Hz]. In this paper, we demonstrate 2-b/s/Hz, 160-Gb/s (Single-Pol. 8160-Gb/s Orthogonal Time-Frequency Domain Multiplexed QPSK for Ultra), which inherits the advantages of high-speed OTDM and high-spectral-efficient OFDM. Single- Pol., 2-b/s/Hz

  16. Joint discrepancy evaluation of an existing steel bridge using time-frequency and wavelet-based approach

    NASA Astrophysics Data System (ADS)

    Walia, Suresh Kumar; Patel, Raj Kumar; Vinayak, Hemant Kumar; Parti, Raman

    2013-12-01

    The objective of this study is to bring out the errors introduced during construction which are overlooked during the physical verification of the bridge. Such errors can be pointed out if the symmetry of the structure is challenged. This paper thus presents the study of downstream and upstream truss of newly constructed steel bridge using time-frequency and wavelet-based approach. The variation in the behavior of truss joints of bridge with variation in the vehicle speed has been worked out to determine their flexibility. The testing on the steel bridge was carried out with the same instrument setup on both the upstream and downstream trusses of the bridge at two different speeds with the same moving vehicle. The nodal flexibility investigation is carried out using power spectral density, short-time Fourier transform, and wavelet packet transform with respect to both the trusses and speed. The results obtained have shown that the joints of both upstream and downstream trusses of the bridge behave in a different manner even if designed for the same loading due to constructional variations and vehicle movement, in spite of the fact that the analytical models present a simplistic model for analysis and design. The difficulty of modal parameter extraction of the particular bridge under study increased with the increase in speed due to decreased excitation time.

  17. Methods of EEG signal features extraction using linear analysis in frequency and time-frequency domains.

    PubMed

    Al-Fahoum, Amjed S; Al-Fraihat, Ausilah A

    2014-01-01

    Technically, a feature represents a distinguishing property, a recognizable measurement, and a functional component obtained from a section of a pattern. Extracted features are meant to minimize the loss of important information embedded in the signal. In addition, they also simplify the amount of resources needed to describe a huge set of data accurately. This is necessary to minimize the complexity of implementation, to reduce the cost of information processing, and to cancel the potential need to compress the information. More recently, a variety of methods have been widely used to extract the features from EEG signals, among these methods are time frequency distributions (TFD), fast fourier transform (FFT), eigenvector methods (EM), wavelet transform (WT), and auto regressive method (ARM), and so on. In general, the analysis of EEG signal has been the subject of several studies, because of its ability to yield an objective mode of recording brain stimulation which is widely used in brain-computer interface researches with application in medical diagnosis and rehabilitation engineering. The purposes of this paper, therefore, shall be discussing some conventional methods of EEG feature extraction methods, comparing their performances for specific task, and finally, recommending the most suitable method for feature extraction based on performance. PMID:24967316

  18. Methods of EEG Signal Features Extraction Using Linear Analysis in Frequency and Time-Frequency Domains

    PubMed Central

    Al-Fahoum, Amjed S.; Al-Fraihat, Ausilah A.

    2014-01-01

    Technically, a feature represents a distinguishing property, a recognizable measurement, and a functional component obtained from a section of a pattern. Extracted features are meant to minimize the loss of important information embedded in the signal. In addition, they also simplify the amount of resources needed to describe a huge set of data accurately. This is necessary to minimize the complexity of implementation, to reduce the cost of information processing, and to cancel the potential need to compress the information. More recently, a variety of methods have been widely used to extract the features from EEG signals, among these methods are time frequency distributions (TFD), fast fourier transform (FFT), eigenvector methods (EM), wavelet transform (WT), and auto regressive method (ARM), and so on. In general, the analysis of EEG signal has been the subject of several studies, because of its ability to yield an objective mode of recording brain stimulation which is widely used in brain-computer interface researches with application in medical diagnosis and rehabilitation engineering. The purposes of this paper, therefore, shall be discussing some conventional methods of EEG feature extraction methods, comparing their performances for specific task, and finally, recommending the most suitable method for feature extraction based on performance. PMID:24967316

  19. Deriving Lifetime Maps in the Time/Frequency Domain of Coherent Structures in the Turbulent Boundary Layer

    NASA Technical Reports Server (NTRS)

    Palumbo, Dan

    2008-01-01

    The lifetimes of coherent structures are derived from data correlated over a 3 sensor array sampling streamwise sidewall pressure at high Reynolds number (> 10(exp 8)). The data were acquired at subsonic, transonic and supersonic speeds aboard a Tupolev Tu-144. The lifetimes are computed from a variant of the correlation length termed the lifelength. Characteristic lifelengths are estimated by fitting a Gaussian distribution to the sensors cross spectra and are shown to compare favorably with Efimtsov s prediction of correlation space scales. Lifelength distributions are computed in the time/frequency domain using an interval correlation technique on the continuous wavelet transform of the original time data. The median values of the lifelength distributions are found to be very close to the frequency averaged result. The interval correlation technique is shown to allow the retrieval and inspection of the original time data of each event in the lifelength distributions, thus providing a means to locate and study the nature of the coherent structure in the turbulent boundary layer. The lifelength data are converted to lifetimes using the convection velocity. The lifetime of events in the time/frequency domain are displayed in Lifetime Maps. The primary purpose of the paper is to validate these new analysis techniques so that they can be used with confidence to further characterize the behavior of coherent structures in the turbulent boundary layer.

  20. Narrow-Band Short-Time Frequency-Domain Blind Signal Separation of Passive Sonar Signals

    Microsoft Academic Search

    Natanael N. De Moura; Eduardo F. Simas Filho; José Manoel De Seixas

    2009-01-01

    Sonar systems are very important for several military and civil navy applications. Passive sonar signals are susceptible to\\u000a cross-interference from underwater acoustic sources (targets) present at different directions. In this work, a frequency-domain\\u000a blind source separation procedure is proposed aiming at reducing cross-interferences, which may arise from adjacent signal\\u000a source directions. As a consequence, target detection and classification may both

  1. Experimental research on anti-vibration interferometry based on time-frequency-domain analysis

    NASA Astrophysics Data System (ADS)

    Hu, Yao; Hao, Qun; Zhang, Fanghua; Tian, Yuhan

    2013-10-01

    Phase-shifting interferometry is a non-contact precision precise measuring method for optical surface, but it is highly sensitive to external vibrations. A time-and-frequency-domain (TFD) anti-noise phase-shifting interferometry is proposed to eliminate the effect of vibrations and improve the precision of measurement. According to simulations and preliminary experiments, active phase-shifting speed as well as interferogram capture speed should be increased to improve the anti-vibration capability of the TFD method. In this paper, a fast phase-shifting approach based on PZT actuator and interferogram detection with high-speed camera is proposed. Preliminary experimental results are given to demonstrate the approach.

  2. An enhanced algorithm for knee joint sound classification using feature extraction based on time-frequency analysis.

    PubMed

    Kim, Keo Sik; Seo, Jeong Hwan; Kang, Jin U; Song, Chul Gyu

    2009-05-01

    Vibroarthrographic (VAG) signals, generated by human knee movement, are non-stationary and multi-component in nature and their time-frequency distribution (TFD) provides a powerful means to analyze such signals. The objective of this paper is to improve the classification accuracy of the features, obtained from the TFD of normal and abnormal VAG signals, using segmentation by the dynamic time warping (DTW) and denoising algorithm by the singular value decomposition (SVD). VAG and knee angle signals, recorded simultaneously during one flexion and one extension of the knee, were segmented and normalized at 0.5 Hz by the DTW method. Also, the noise within the TFD of the segmented VAG signals was reduced by the SVD algorithm, and a back-propagation neural network (BPNN) was used to classify the normal and abnormal VAG signals. The characteristic parameters of VAG signals consist of the energy, energy spread, frequency and frequency spread parameter extracted by the TFD. A total of 1408 segments (normal 1031, abnormal 377) were used for training and evaluating the BPNN. As a result, the average classification accuracy was 91.4 (standard deviation +/-1.7) %. The proposed method showed good potential for the non-invasive diagnosis and monitoring of joint disorders such as osteoarthritis. PMID:19217685

  3. Joint multi-mode dispersion extraction in Fourier and space time domains

    E-print Network

    Bose, Sandip; Valero, Henri-Pierre

    2013-01-01

    In this paper we present a novel broadband approach for the extraction of dispersion curves of multiple time frequency overlapped dispersive modes such as in borehole acoustic data. The new approach works jointly in the Fourier and space time domains and, in contrast to existing space time approaches that mainly work for time frequency separated signals, efficiently handles multiple signals with significant time frequency overlap. The proposed method begins by exploiting the slowness (phase and group) and time location estimates based on frequency-wavenumber (f-k) domain sparsity penalized broadband dispersion extraction method as presented in \\cite{AeronTSP2011}. In this context we first present a Cramer Rao Bound (CRB) analysis for slowness estimation in the (f-k) domain and show that for the f-k domain broadband processing, group slowness estimates have more variance than the phase slowness estimates and time location estimates. In order to improve the group slowness estimates we exploit the time compactne...

  4. Theoretical background for continental- and global-scale full-waveform inversion in the time-frequency domain

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas; Kennett, Brian L. N.; Igel, Heiner; Bunge, Hans-Peter

    2008-11-01

    We propose a new approach to full seismic waveform inversion on continental and global scales. This is based on the time-frequency transform of both data and synthetic seismograms with the use of time- and frequency-dependent phase and envelope misfits. These misfits allow us to provide a complete quantification of the differences between data and synthetics while separating phase and amplitude information. The result is an efficient exploitation of waveform information that is robust and quasi-linearly related to Earth's structure. Thus, the phase and envelope misfits are usable for continental- and global-scale tomography, that is, in a scenario where the seismic wavefield is spatially undersampled and where a 3-D reference model is usually unavailable. Body waves, surface waves and interfering phases are naturally included in the analysis. We discuss and illustrate technical details of phase measurements such as the treatment of phase jumps and instability in the case of small amplitudes. The Fréchet kernels for phase and envelope misfits can be expressed in terms of their corresponding adjoint wavefields and the forward wavefield. The adjoint wavefields are uniquely determined by their respective adjoint-source time functions. We derive the adjoint-source time functions for phase and envelope misfits. The adjoint sources can be expressed as inverse time-frequency transforms of a weighted phase difference or a weighted envelope difference. In a comparative study, we establish connections between the phase and envelope misfits and the following widely used measures of seismic waveform differences: (1) cross-correlation time-shifts; (2) relative rms amplitude differences; (3) generalized seismological data functionals and (4) the L2 distance between data and synthetics used in time-domain full-waveform inversion. We illustrate the computation of Fréchet kernels for phase and envelope misfits with data from an event in the West Irian region of Indonesia, recorded on the Australian continent. The synthetic seismograms are computed for a heterogeneous 3-D velocity model of the Australian upper mantle, with a spectral-element method. The examples include P body waves, Rayleigh waves and S waves, interfering with higher-mode surface waves. All the kernels differ from the more familar kernels for cross-correlation time-shifts or relative rms amplitude differences. The differences arise from interference effects, 3-D Earth's structure and waveform dissimilarities that are due to waveform dispersion in the heterogeneous Earth.

  5. Characterization by a time-frequency method of classical waves propagation in one-dimensional lattice : effects of the dispersion

    E-print Network

    Paris-Sud XI, Université de

    -Frequency Representations (TFR) of sig- nals. Joint time-frequency representations combine time and frequency-domain analysis by displaying a signal as a function defined over the time frequency plane. These representations localized in the resonators, we present Time-Frequency pictures given by acoustic pulses and frequency

  6. Comparison of air-launched and ground-coupled configurations of SFCW GPR in time, frequency and wavelet domain

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; De Pue, Jan; Cornelis, Wim; Van Meirvenne, Marc

    2015-04-01

    A stepped frequency continuous wave (SFCW) ground penetrating radar (GPR) system produces waveforms consisting of a sequence of sine waves with linearly increasing frequency. By adopting a wide frequency bandwidth, SFCW GPR systems offer an optimal resolution at each achievable measurement depth. Furthermore, these systems anticipate an improved penetration depth and signal-to-noise ratio (SNR) as compared to time-domain impulse GPRs, because energy is focused in one single frequency at a time and the phase and amplitude of the reflected signal is recorded for each discrete frequency step. However, the search for the optimal practical implementation of SFCW GPR technology to fulfil these theoretical advantages is still ongoing. In this study we compare the performance of a SFCW GPR system for air-launched and ground-coupled antenna configurations. The first is represented by a 3d-Radar Geoscope GS3F system operated with a V1213 antenna array. This array contains 7 transmitting and 7 receiving antennae resulting in 13 measurement channels at a spacing of 0.075 m and providing a total scan width of 0.975 m. The ground-coupled configuration is represented by 3d-Radar's latest-generation SFCW system, GeoScope Mk IV, operated with a DXG1212 antenna array. With 6 transmitting and 5 receiving antennae this array provides 12 measurement channels and an effective scan width of 0.9 m. Both systems were tested on several sites representative of various application environments, including a test site with different road specimens (Belgian Road Research Centre) and two test areas in different agricultural fields in Flanders, Belgium. For each test, data acquisition was performed using the full available frequency bandwidth of the systems (50 to 3000 MHz). Other acquisition parameters such as the frequency step and dwell time were varied in different tests. Analyzing the data of the different tests in time, frequency and wavelet domain allows to evaluate different performance aspects of the air-launched and ground-coupled configurations such as acquisition speed, measurement resolution, SNR and penetration depth. Based on this analysis, we highlight the advantages and disadvantages of the different SFCW GPR configurations in different application environments. The authors thank Colette Grégoire and Carl Van Geem of the Belgian Road Research Centre for the collaboration on the road test site. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar".

  7. Hybrid Time-Frequency Domain Eigenmode Propagation Analysis of Optical Waveguides Based on the Method of Lines

    Microsoft Academic Search

    Johannes Gerdes

    2007-01-01

    In this paper a novel combination of time domain and frequency domain analysis of optical waveguides using the method of lines and the discrete Fourier transform is presented. The hybrid algorithm is applied to propagation analysis in multimode optical waveguides. In extension of the existing method of lines analysis in the literature the algorithm allows the inclusion of time dependent

  8. High Order Statistics and Time-Frequency Domain to Classify Heart Sounds for Subjects under Cardiac Stress Test

    PubMed Central

    Moukadem, Ali; Schmidt, Samuel; Dieterlen, Alain

    2015-01-01

    This paper considers the problem of classification of the first and the second heart sounds (S1 and S2) under cardiac stress test. The main objective is to classify these sounds without electrocardiogram (ECG) reference and without taking into consideration the systolic and the diastolic time intervals criterion which can become problematic and useless in several real life settings as severe tachycardia and tachyarrhythmia or in the case of subjects being under cardiac stress activity. First, the heart sounds are segmented by using a modified time-frequency based envelope. Then, to distinguish between the first and the second heart sounds, new features, named ?opt, ?, and ?, based on high order statistics and energy concentration measures of the Stockwell transform (S-transform) are proposed in this study. A study of the variation of the high frequency content of S1 and S2 over the HR (heart rate) is also discussed. The proposed features are validated on a database that contains 2636 S1 and S2 sounds corresponding to 62 heart signals and 8 subjects under cardiac stress test collected from healthy subjects. Results and comparisons with existing methods in the literature show a large superiority for our proposed features.

  9. Research on the key parameters influencing the anti-vibration capability of time-frequency-domain interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Fanghua; Hao, Qun; Hu, Yao; Zhu, Qiudong

    2012-11-01

    This paper introduces a time-and-frequency-domain (TFD) anti-noise phase-shifting interferometry, and designs an experimental system to test the anti-vibration ability of this method. In the system, a plane mirror is measured under the external vibrations simulated by the standard mirror propelled by PZT. During the measurement, each of the key parameters is assigned different values. By analyzing the testing results, the law of the parameters' influence on system anti-vibration capability can be obtained. According to the law, the optimization parameters can be determined so that the system has the maximum anti- vibration capability.

  10. Time-frequency distributions - A review

    Microsoft Academic Search

    Leon Cohen

    1989-01-01

    A review and tutorial of the fundamental ideas and methods of joint time-frequency distributions is presented. The objective of the field is to describe how the spectral content of a signal changes in time and to develop the physical and mathematical ideas needed to understand what a time-varying spectrum is. The basic goal is to devise a distribution that represents

  11. Applications of (Wigner-Type) Time-Frequency Distributions to Sonar and Radar Signal Analysis

    Microsoft Academic Search

    Guillermo C. Gaunaurd; Hans C. Strifors

    2003-01-01

    Wigner-type distributions have shown their effectiveness in classification\\u000aproblems of sonar and radar. We present an overview of applications where\\u000aresonance features in echoes scattered from targets insonified or illuminated\\u000awith short pulses are studied in the joint time-frequency domain. We first show\\u000athe acoustic case of an elastic shell with a few filler materials submerged in\\u000awater and insonified

  12. Nesting High-resolution Multi-layer Photosynthesis Approaches in Current Forest Productivity Models: A Cost-Benefit Analysis in the Time-Frequency Domain

    NASA Astrophysics Data System (ADS)

    Siqueira, M.; Katul, G.; Sampson, D. A.; Stoy, P.; Juang, J.; Oren, R.

    2004-12-01

    Ecosystem processes relevant to carbon transfer and storage are known to vary over many time and space scales. In the time domain, processes ranging from seconds, such as turbulent transport, to seasons, such as plant phenology, affect assimilation and respiration, which in turn, control carbon allocation over time scales of days to years. These inter-related processes contribute to the forest development (often measured in years to decades) and long-term carbon sequestration. To date, no single model captures the entire spectrum of variability of these processes; rather, a modular approach is adopted in which the forcing and response variables are mechanistically coupled over an inherent or assumed time scale that is then integrated to longer time scales. The effect of such modular parameterization of the "fast" processes and their cross-scale interaction with the slowly varying processes on long-term carbon sequestration remains a subject of investigation. We address this problem in two ways. First, we perform a multi-model inter-comparison in the time and frequency domains to assess how different parameterizations of photosynthesis and water vapor fluxes in forest growth models (e.g. BGC, SECRETS, PnET and 3PG) reproduce the observed spectrum of these two fluxes from hours to years. These models were chosen because they significantly vary in complexity and integration time step, thereby "filtering" the flux spectrum differently. Next, we explore the consequences of this filtering on cross-scale information flow using a newly proposed nested scheme that employs multi-species allocation routines with assimilation calculated with CANVEG. CANVEG is a multi-layer and multi-species model that resolves the entire canopy microclimate and uses a dynamic leaf area density as an input. The analysis is done in a cost-benefit fashion evaluating the gain in predictive skills of long-term carbon sequestration as result of extra model complexity and added parameterizations. As a case study, we use multi-year CO2 and water vapor flux measurement from a Pine Plantation at the Duke Forest Ameriflux site.

  13. A Bayesian Nonparametric Model for Joint Relation Integration and Domain Dazhuo Li, Fahim Mohammad, Eric Rouchka

    E-print Network

    Rouchka, Eric

    to infer structures over entity types and predict relationships among elements of these types. HoweverA Bayesian Nonparametric Model for Joint Relation Integration and Domain Clustering Dazhuo Li a challenging task. We present a Bayesian nonparametric model for joint relation and domain clustering

  14. BLIND SOURCE SEPARATION BASED ON SPACE-TIME-FREQUENCY DIVERSITY

    Microsoft Academic Search

    Scott Rickard; Radu Balan; Justinian Rosca

    We investigate the assumption that sources have disjoint support in the time domain, time-frequency domain, or frequency domain. We call such signals disjoint orthogonal. The class of signals that ap- proximately satisfies this assumption includes many synthetic sig- nals, music and speech, as well as some biological signals. We measure the disjoint orthogonality of the benchmark signals in the ICALAB

  15. Comparison of optimization-algorithm based feature extraction from time data or time-frequency data for target recognition purposes

    NASA Astrophysics Data System (ADS)

    Strifors, H. C.; Abrahamson, S.; Andersson, T.; Gaunaurd, G. C.

    2006-05-01

    Ultra-wideband ground penetrating radar (GPR) systems have proved useful for extracting and displaying information for target recognition purposes. Target signatures whether in the time, frequency, or joint time-frequency domains, will substantially depend on the target's burial conditions such as the type of soil, burial depth, and the soil's moisture content. That dependence can be utilized for target recognition purposes as we have demonstrated previously. The signature template of each target was computed in the time-frequency domain from the returned echo when the target was buried at a known depth in the soil with a known moisture content. Then, for any returned echo the relative difference between the similarly computed target signature and a selected signature template was computed. A global optimization method together with our (approximate) target translation method (TTM) that signature difference, chosen as object function, was minimized by adjusting the depth and moisture content, now taken to be unknown parameters. The template that gave the smallest value of the minimized object function for the returned echo was taken as target classification and the corresponding values of the depth and moisture parameters as estimates of the target's burial conditions. This optimization technique can also be applied to time-series data, avoiding the need for time-frequency analysis. It is then of interest to evaluate the relative merits of time data and time-frequency data for target recognition. Such a comparison is here preformed using signals returned from dummy mines buried underground. The results of the analysis serve to assess the intrinsic worth of data in the time domain and in the time-frequency domain for identifying subsurface targets using a GPR. The targets are buried in a test field at the Swedish Explosive Ordnance Disposal and Demining Center (SWEDEC) at Eksjo, Sweden.

  16. Applications of time-frequency signature analysis to target identification

    Microsoft Academic Search

    Guillermo C. Gaunaurd; Hans C. Strifors

    1999-01-01

    The overlapping subjects of target identification, inverse scattering and active classification have many applications that differ depending on specific sensors. Many useful techniques for these relevant subjects have been developed in the frequency and the time domains. A more recent approach views the target signatures in the combined or coupled time-frequency domain. For either ultra-wideband (UWB) projectors, or UWB processing

  17. TIME-FREQUENCY-PHASE COHERENCE GENERAL FRAMEWORK FOR SIGNAL ANALYSIS IN PASSIVE CONTEXT

    E-print Network

    Paris-Sud XI, Université de

    TIME-FREQUENCY-PHASE COHERENCE ­ GENERAL FRAMEWORK FOR SIGNAL ANALYSIS IN PASSIVE CONTEXT CORNEL-stationary. Their analysis in the time-frequency domain is well adapted so that it offers appropriated structures which of an appropriate time-frequency representation space is a complex problem, mainly related to the lack of a priori

  18. Time-Frequency localization of Multiband signals

    E-print Network

    Lakey, Joseph D.

    Time-Frequency localization of Multiband signals FFT, Norbert Wiener Center, February 20, 2009 Joe Lakey (w Scott Izu)1 February 20, 2009 Joe Lakey (w Scott Izu) Time-frequency multiband #12;Time and frequency localization Fourier transform: f () = R f (t) e-2it dt Joe Lakey (w Scott Izu) Time-frequency

  19. Time-Frequency localization of Multiband signals

    E-print Network

    Lakey, Joseph D.

    Time-Frequency localization of Multiband signals University of Arkansas, November 7, 2008 Joe Lakey (w Scott Izu)1 November 3, 2008 Joe Lakey (w Scott Izu) Time-frequency multiband #12;Time and frequency localization Fourier transform: f () = R f (t) e-2it dt Joe Lakey (w Scott Izu) Time-frequency

  20. Wave propagation across non-linear rock joints based on time-domain recursive method

    NASA Astrophysics Data System (ADS)

    Li, J. C.

    2013-05-01

    Studying wave propagation across joints is crucial in geophysics, mining and underground construction. Limited analyses are available for oblique incidence across non-linear joints. In this paper, the time-domain recursive method (TDRM) proposed by Li et al. is extended to analyse wave propagation across a set of non-linear joints. The Barton-Bandis model (B-B model) and the Coulomb-slip model are adopted to describe the non-linear normal and shear properties of the joints, respectively. With the displacement discontinuity model and the time shifting function, the wave propagation equation is established for incident longitudinal-(P-) or transverse-(S-)wave across the joints with arbitrary impinging angles. Comparison between the results from the TDRM and the existing methods is carried out for two specific cases to verify the derived wave propagation equation. The effects of some parameters, such as the incident angle, the joint spacing, the amplitude of incidence and the joint maximum allowable normal closure, on wave propagation are discussed.

  1. Blind Criterion and Oracle Bound for Instantaneous Audio Source Separation using Adaptive Time-Frequency Representations

    Microsoft Academic Search

    Emmanuel Vincent; Remi Gribonval

    2007-01-01

    The separation of multichannel audio mixtures is often addressed by the masking approach, which consists of representing the mixture signal in the time-frequency domain and associating each time-frequency bin with a small number of active sources. Adaptive time-frequency representations can increase the disjointness of the sources compared to fixed representations. However their use has not been conclusive so far. In

  2. Radar scattering: a time-frequency perspective

    Microsoft Academic Search

    H. N. Kritikos

    1997-01-01

    Time-frequency analysis is used to study electromagnetic scattering from canonical objects leading to the detection, localization and extraction of response features that result from the object's physical attributes. The time-frequency analysis techniques are motivated by signal representation in phase space, and are formulated using the Bargman transform. Bargman transform techniques allow the phase space to be parametrically represented in terms

  3. Joint Optimization of the Frequency-domain and Time-domain Transformations in Deriving

    E-print Network

    Mak, Brian Kan-Wing

    the optimization problem. The framework allows extension to other optimization costs as well. Index Terms-- low. Their derivation may be generalized as a frequency-domain transformation of the log filter-bank energies (FBEs derivative. The MFCC extraction procedure may be generalized as two transformations or filtering on the time

  4. Removing Components from a Time-Frequency Representation Monika Dorfler, Peter Balazs and Florent Jaillet

    E-print Network

    Feichtinger, Hans Georg

    Jaillet Acoustics Research Institute, A-1040 Vienna, Austria March 17, 2009 Introduction Time of removing certain components with approx- imately disjoint support in the time-frequency domain. For example. Such approaches are used in Computational Auditory Scene Analysis by the name of Time-Frequency masks. However

  5. TIME-FREQUENCY MODELING OF SHALLOW WATER ENVIRONMENTS: RIGID VS. FLUID SEABED

    E-print Network

    Nehorai, Arye

    -frequency analysis, dispersive chan- nels, time-frequency mode separation, underwater acoustic communications, time phenomena. Then a frequency-domain matched filter receiver is designed to obtain time-dispersion diversityTIME-FREQUENCY MODELING OF SHALLOW WATER ENVIRONMENTS: RIGID VS. FLUID SEABED Jun Zhang , Bertrand

  6. Benchmarking flexible adaptive time-frequency transforms for underdetermined audio source separation

    Microsoft Academic Search

    Andrew Nesbit; Emmanuel Vincent; Mark D. Plumbley

    2009-01-01

    We have implemented several fast and flexible adaptive lapped orthogonal transform (LOT) schemes for underdetermined audio source separation. This is generally addressed by time-frequency masking, requiring the sources to be disjoint in the time-frequency domain. We have already shown that disjointness can be increased via adaptive dyadic LOTs. By taking inspiration from the windowing schemes used in many audio coding

  7. Brain connectivity study of joint attention using frequency-domain optical imaging technique

    NASA Astrophysics Data System (ADS)

    Chaudhary, Ujwal; Zhu, Banghe; Godavarty, Anuradha

    2010-02-01

    Autism is a socio-communication brain development disorder. It is marked by degeneration in the ability to respond to joint attention skill task, from as early as 12 to 18 months of age. This trait is used to distinguish autistic from nonautistic populations. In this study, diffuse optical imaging is being used to study brain connectivity for the first time in response to joint attention experience in normal adults. The prefrontal region of the brain was non-invasively imaged using a frequency-domain based optical imager. The imaging studies were performed on 11 normal right-handed adults and optical measurements were acquired in response to joint-attention based video clips. While the intensity-based optical data provides information about the hemodynamic response of the underlying neural process, the time-dependent phase-based optical data has the potential to explicate the directional information on the activation of the brain. Thus brain connectivity studies are performed by computing covariance/correlations between spatial units using this frequency-domain based optical measurements. The preliminary results indicate that the extent of synchrony and directional variation in the pattern of activation varies in the left and right frontal cortex. The results have significant implication for research in neural pathways associated with autism that can be mapped using diffuse optical imaging tools in the future.

  8. Missing Data Imputation for Time-Frequency Representations of Audio Signals

    Microsoft Academic Search

    Paris Smaragdis; Bhiksha Raj; Madhusudana Shashanka

    With the recent attention towards audio processing in the time-frequency domain we increasingly encounter the problem of missing\\u000a data within that representation. In this paper we present an approach that allows us to recover missing values in the time-frequency\\u000a domain of audio signals. The presented approach is able to deal with real-world polyphonic signals by operating seamlessly\\u000a even in the

  9. Intelligent Joint Fault Diagnosis of Industrial Robots

    NASA Astrophysics Data System (ADS)

    Pan, M.-C.; Van Brussel, H.; Sas, P.

    1998-07-01

    The dynamic behaviour of high-performance mechanical systems such as robots is strongly influenced by the characteristics of the link joints. Joint backlash as a result of wear due to severe stress imposed on the transmission system degrades the robot performance. This paper presents a systematic methodology to diagnose the joint-backlash of a robot by monitoring its vibration response during normal operations. To indicate the reversal of motion of a robot link, and to characterise the spectral patterns of vibration signatures, non-stationary time-frequency analysis algorithms have been employed, which illustrate the signature in a simultaneous time-frequency plane. Significant features are extracted from time domain analysis (probability density moments), and from time-frequency domain analysis (local energy calculations). Artificial neural networks are used as tools for pattern recognition. Experimental results show that the proposed techniques can analyse single-joint backlash quantitatively. Moreover, the described methods also allow to single out backlash in the individual joints in case of multiple-joint backlash.

  10. Time-frequency analysis of chaotic systems

    E-print Network

    C. Chandre; S. Wiggins; T. Uzer

    2002-09-06

    We describe a method for analyzing the phase space structures of Hamiltonian systems. This method is based on a time-frequency decomposition of a trajectory using wavelets. The ridges of the time-frequency landscape of a trajectory, also called instantaneous frequencies, enable us to analyze the phase space structures. In particular, this method detects resonance trappings and transitions and allows a characterization of the notion of weak and strong chaos. We illustrate the method with the trajectories of the standard map and the hydrogen atom in crossed magnetic and elliptically polarized microwave fields.

  11. Extraction of time-frequency target features

    Microsoft Academic Search

    Tobias G. Oesterlein; Chensong He; Jorge E. Quijano; Richard L. Campbell Jr; Lisa M. Zurk; Martin Siderius

    2010-01-01

    Physics-based detection algorithms can improve discrimination of sonar targets from competing bottom reverberation, but are vulnerable to environmental uncertainties. Recent research in the underwater community has identified an environmentally robust time-frequency signature for improved target discrimination. Application of this “invariant” requires processing algorithms to identify striations in a spectrogram and to quantify the associated track certainty. In this paper, two

  12. Generalized time-frequency distributions and applications

    Microsoft Academic Search

    Messaoud BENIDIR; Abdelaziz OULDALI

    A decomposition of the derivatives of or- derof a polynomial ?(t )i s proposed in terms of ?(t ? t0) ,... , ?(t ? tn). This result allows us to intro- duce generalized time-frequency distributions for study- ing polynomial phase signals with constant amplitude in order to determine the degree and the coefficients of the corresponding phase. Relationships between these

  13. Time-Frequency Reassignment for Music Analysis

    Microsoft Academic Search

    Stephen W. Hainsworth; Patrick J. Wolfe

    2001-01-01

    Time-frequency reassignment may be viewed as a refinement of the short-time Fourier transform, in which phase informa- tion is used to reduce the smearing of energy associated with the standard spectrogram. However, even given the percepti- bly clearer visual representation yielded by the reassignment method in the case of musical signals, the task remains of ex- tracting useful information from

  14. Blood flow measurement and slow flow detection in retinal vessels with Joint Spectral and Time domain method in ultrahigh speed OCT

    E-print Network

    Gorczynska, I.

    We present an application of the Joint Spectral and Time domain OCT (STdOCT) method for detection of wide range of flows in the retinal vessels. We utilized spectral/Fourier domain OCT (SOCT) technique for development of ...

  15. Simultaneous denoising and preserving of seismic signals by multiscale time-frequency peak filtering

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Li, Yue; Lin, Hongbo; Yang, Baojun

    2015-06-01

    Time frequency peak filtering has been successfully applied to eliminate pervasive random noise in the time-frequency domain. The linearity of the signal is crucial for denoising in the time frequency peak filtering method. We usually apply pseudo Wigner-Ville distribution to make the signal locally linear in time. However, there is a pair of contradiction in window length selection for pseudo Wigner-Ville distribution. If we choose a short window length for pseudo Wigner-Ville distribution in the time frequency peak filtering, it leads to good preservation for signals, but the denoising performance is relatively poor. So the contradiction between the signal preservation and noise attenuation cannot be solved by a fixed window length. In this paper, we present a multiscale time frequency peak filtering to solve this problem. In the novel method, we adopt a Laplacian pyramid to decompose the seismic data into multiple scale components. These components have different frequencies. Then a short window length can be chosen for signal-dominant scale to preserve the signal and a long window length is applied to noise-dominant scale by the time frequency peak filtering to suppress more noise. We test the performance of our proposed method on both synthetic and real seismic data. Tests demonstrate that the multiscale time frequency peak filtering based on Laplacian pyramid can eliminate the random noise more effectively and preserve events of interest better than the conventional time frequency peak filtering.

  16. Underdetermined Blind Separation of Audio Sources from the Time-Frequency Representation of their Convolutive Mixtures

    Microsoft Academic Search

    Abdeldjalil Aïssa-El-Bey; Karim Abed-Meraim; Yves Grenier

    2007-01-01

    This paper considers the blind separation of nonstationary sources in the underdetermined convolutive mixture case. We introduce two methods based on the sparsity assumption of the sources in the time-frequency (TF) domain. The first one assumes that the sources are disjoint in the TF domain; i.e. there is at most one source signal present at a given point in the

  17. Radon transformation of time-frequency distributions for analysis of multicomponent signals

    Microsoft Academic Search

    John C. Wood; Daniel T. Barry

    1994-01-01

    The Radon transform of a time-frequency distribution produces local areas of signal concentration that facilitate interpretation of multicomponent signals. The Radon-Wigner transform can be efficiently implemented with dechirping in the time domain, however, only half of the possible projections through the time-frequency plane can be realized because of aliasing. We show here that the frequency dual to dechirping exists, so

  18. Maximum likelihood approach for blind audio source separation using time-frequency Gaussian source models

    Microsoft Academic Search

    C. Fevotte; J.-F. Cardoso

    2005-01-01

    In this paper we propose a simple time-frequency Gaussian model of audio signals that allows for separation of possibly underdetermined and noisy linear instantaneous mixtures. An efficient EM algorithm is proposed to estimate the mixing matrix, the noise covariance and covariances of the source t-f coefficients over a chosen frame\\/subband tiling of the time-frequency domain. Results are given on 4

  19. Time-frequency characterization and receiver waveform design for shallow water environments

    Microsoft Academic Search

    Jun Jason Zhang; Antonia Papandreou-Suppappola; Bertrand Gottin; Cornel Ioana

    2009-01-01

    We investigate a frequency-domain characterization of shallow water environments based on normal-mode models of acoustic mediums. The shallow water environment can be considered as a time-dispersive system whose time-varying impulse response can be expressed as a superposition of time-frequency components with dispersive characteristics. After studying the dispersive characteristics, a blind time-frequency processing technique is employed to separate the normal-mode components

  20. Joint Tomlinson-Harashima Precoding and Frequency-Domain Equalization for Broadband Single-Carrier Transmission

    NASA Astrophysics Data System (ADS)

    Takeda, Kazuki; Tomeba, Hiromichi; Adachi, Fumiyuki

    The performance of single-carrier (SC) transmission in a frequency-selective fading channel degrades due to a severe inter-symbol interference (ISI). Using frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can improve the bit error rate (BER) performance of SC transmission. However, the residual ISI after FDE limits the performance improvement. In this paper, we propose a joint use of Tomlinson-Harashima precoding (THP) and FDE to remove the residual ISI. An approximate conditional BER analysis is presented for the given channel condition. The achievable average BER performance is evaluated by Monte-Carlo numerical computation method using the derived conditional BER. The BER analysis is confirmed by computer simulation of the signal transmission.

  1. Time-frequency characterisation of paediatric heart sounds

    NASA Astrophysics Data System (ADS)

    Leung, Terence Sze-Tat

    1998-08-01

    The operation of the heart can be monitored by the sounds it emits. Structural defects or malfunction of the heart valves will cause additional abnormal sounds such as murmurs and ejection clicks. This thesis aims to characterise the heart sounds of three groups of children who either have an Atrial Septal Defect (ASD), a Ventricular Septal Defect (VSD), or are normal. Two aspects of heart sounds have been specifically investigated; the time-frequency analysis of systolic murmurs and the identification of splitting patterns in the second heart sound. The analysis is based on 42 paediatric heart sound recordings. Murmurs are sounds generated by turbulent flow of blood in the heart. They can be found in patients with both pathological and non-pathological conditions. The acoustic quality of the murmurs generated in each heart condition are different. The first aspect of this work is to characterise the three types of murmurs in the time- frequency domain. Modern time-frequency methods including, the Wigner-Ville Distribution, Smoothed Pseudo Wigner-Ville Distribution, Choi-Williams Distribution and spectrogram have been applied to characterise the murmurs. It was found that the three classes of murmurs exhibited different signatures in their time-frequency representations. By performing Discriminant Analysis, it was shown that spectral features extracted from the time- frequency representations can be used to distinguish between the three classes. The second aspect of the research is to identify splitting patterns in the second heart sound, which consists of two acoustic components due to the closure of the aortic valve and pulmonary valve. The aortic valve usually closes before the pulmonary valve, introducing a time delay known as 'split'. The split normally varies in duration over the respiratory cycle. In certain pathologies such as the ASD, the split becomes fixed over the respiration cycle. A technique based on adaptive signal decomposition is developed to measure the split and hence to identify the splitting pattern as either 'variable' or 'fixed'. This work has successfully characterised the murmurs and splitting patterns in the three groups of patients. Features extracted can be used for diagnostic purposes.

  2. TIME-FREQUENCY LEARNING MACHINES FOR NONSTATIONARITY DETECTION USING SURROGATES

    E-print Network

    Paris-Sud XI, Université de

    TIME-FREQUENCY LEARNING MACHINES FOR NONSTATIONARITY DETECTION USING SURROGATES Hassan Amoud, Paul and time- frequency analysis, called time-frequency learning machines. Based on one-class support vector machines, our approach uses entire time-frequency representations and does not re- quire arbitrary feature

  3. Determination of structural domain boundaries in jointed rock masses: An example from the Songta dam site, China

    NASA Astrophysics Data System (ADS)

    Li, Yanyan; Wang, Qing; Chen, Jianping; Han, Lili; Zhang, Wen; Ruan, Yunkai

    2014-12-01

    This paper presents an application of the Kolmogorov-Smirnov and Wilcoxon rank sum nonparametric statistical tests for identifying structural domain boundaries in jointed rock masses. In the method, the upper hemispherical surface is divided into 100 nearly equal-area windows. The similarity between two samples of joint orientations is measured by comparing the frequencies or the number of joint poles occurring in the windows. Over 2400 joints collected from 8 adjacent exploration tunnels at the Songta dam site in southwest China are used to demonstrate the method. By applying the technique to the study area, structural domain boundaries in the rock mass are determined. Our results suggest that the study area, with an area of approximately 17,850 m2, can be classified into four structural domains. However, the traditional method with the correlation coefficient fails to reveal the structural changes. Since the correlation coefficient is only a measure of strength of the linear relation between two samples, it has limitations in measuring the similarity between joint orientation distributions. A comparison between the proposed method and previous methods indicates that the new technique could provide more reliable results. Besides, the new method can be applied to structural populations with small sample sizes.

  4. Time-Frequency Analysis of the Dispersion of Lamb Modes

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Seale, Michael D.; Smith, Barry T.

    1999-01-01

    Accurate knowledge of the velocity dispersion of Lamb modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. Lamb mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the ability to characterize Lamb mode dispersion through a time-frequency analysis (the pseudo-Wigner-Ville distribution) was demonstrated. A major advantage of time-frequency methods is the ability to analyze acoustic signals containing multiple propagation modes, which overlap and superimpose in the time domain signal. By combining time-frequency analysis with a broadband acoustic excitation source, the dispersion of multiple Lamb modes over a wide frequency range can be determined from as little as a single measurement. In addition, the technique provides a direct measurement of the group velocity dispersion. The technique was first demonstrated in the analysis of a simulated waveform in an aluminum plate in which the Lamb mode dispersion was well known. Portions of the dispersion curves of the AO, A I , So, and S2 Lamb modes were obtained from this one waveform. The technique was also applied for the analysis of experimental waveforms from a unidirectional graphite/epoxy composite plate. Measurements were made both along and perpendicular to the fiber direction. In this case, the signals contained only the lowest order symmetric and antisymmetric modes. A least squares fit of the results from several source to detector distances was used. Theoretical dispersion curves were calculated and are shown to be in good agreement with experimental results.

  5. Time-Frequency Analysis of the Dispersion of Lamb Modes

    NASA Technical Reports Server (NTRS)

    Prosser, W. H.; Seale, Michael D.; Smith, Barry T.

    1999-01-01

    Accurate knowledge of the velocity dispersion of Lamb modes is important for ultrasonic nondestructive evaluation methods used in detecting and locating flaws in thin plates and in determining their elastic stiffness coefficients. Lamb mode dispersion is also important in the acoustic emission technique for accurately triangulating the location of emissions in thin plates. In this research, the ability to characterize Lamb mode dispersion through a time-frequency analysis (the pseudo Wigner-Ville distribution) was demonstrated. A major advantage of time-frequency methods is the ability to analyze acoustic signals containing multiple propagation modes, which overlap and superimpose in the time domain signal. By combining time-frequency analysis with a broadband acoustic excitation source, the dispersion of multiple Lamb modes over a wide frequency range can be determined from as little as a single measurement. In addition, the technique provides a direct measurement of the group velocity dispersion. The technique was first demonstrated in the analysis of a simulated waveform in an aluminum plate in which the Lamb mode dispersion was well known. Portions of the dispersion curves of the A(sub 0), A(sub 1), S(sub 0), and S(sub 2)Lamb modes were obtained from this one waveform. The technique was also applied for the analysis of experimental waveforms from a unidirectional graphite/epoxy composite plate. Measurements were made both along, and perpendicular to the fiber direction. In this case, the signals contained only the lowest order symmetric and antisymmetric modes. A least squares fit of the results from several source to detector distances was used. Theoretical dispersion curves were calculated and are shown to be in good agreement with experimental results.

  6. A time-frequency classifier for human gait recognition

    NASA Astrophysics Data System (ADS)

    Mobasseri, Bijan G.; Amin, Moeness G.

    2009-05-01

    Radar has established itself as an effective all-weather, day or night sensor. Radar signals can penetrate walls and provide information on moving targets. Recently, radar has been used as an effective biometric sensor for classification of gait. The return from a coherent radar system contains a frequency offset in the carrier frequency, known as the Doppler Effect. The movements of arms and legs give rise to micro Doppler which can be clearly detailed in the time-frequency domain using traditional or modern time-frequency signal representation. In this paper we propose a gait classifier based on subspace learning using principal components analysis(PCA). The training set consists of feature vectors defined as either time or frequency snapshots taken from the spectrogram of radar backscatter. We show that gait signature is captured effectively in feature vectors. Feature vectors are then used in training a minimum distance classifier based on Mahalanobis distance metric. Results show that gait classification with high accuracy and short observation window is achievable using the proposed classifier.

  7. Time-Frequency Analysis of Long Range Ultrasonic Signals

    NASA Astrophysics Data System (ADS)

    Thornicroft, Keith; Mares, Cristinel; Mudge, Peter

    2012-08-01

    Long range ultrasonic testing (LRUT) is a relatively new development within the non-destructive testing sector. Traditionally, conventional ultrasonic testing (UT) is performed at high frequencies, in the MHz range, and is capable of detecting small flaws within a range of millimetres; whereas long range ultrasonic inspection is carried out at lower frequencies, typically between 20 and 100kHz, and is capable of highlighting structural detail and discontinuities tens of metres from a test position. Conventional ultrasonic testing relies on the transmission of bulk waves, the velocities of which are independent of frequency and can usually be predicted easily if the elastic properties of the material under test are known. The dynamics of guided waves, however, are dependent upon frequency making the analysis of received data from a specimen complex. This paper will serve as an introduction to time-frequency representation and may allow a clearer understanding of the non-stationary raw signals produced by this inspection process. Currently, LRUT data are assessed in the time or distance domain using the amplitude vs. time 'A-Scan', therefore structural features and potential flaws are highlighted on a time-of-flight basis. However, as the data obtained are dynamic in time and frequency (non-stationary), time-frequency distributions could provide a mode identification or de-noising process to deal with the problem of coherent noise.

  8. Time-frequency Masking EECS 352: Machine Perception of

    E-print Network

    Pardo, Bryan

    Time-frequency Masking EECS 352: Machine Perception of Music & Audio Zafar Rafii, Winter 2014 1 #12;Real spectrogram time frequency · The Short-Time Fourier Transform (STFT) is a succession of local Fourier Transforms (FT) STFT STFT Zafar Rafii, Winter 2014 2 + j* Imaginary spectrogram time frequency

  9. Bit Error Rate Analysis of DS-CDMA with Joint Frequency-Domain Equalization and Antenna Diversity Combining

    Microsoft Academic Search

    Fumiyuki ADACHI; Kazuaki TAKEDA

    2004-01-01

    SUMMARY To improve the DS-CDMA signal transmission perfor- mance in a frequency-selective fading channel, the frequency-domain equalization (FDE) can be applied, in which simple one-tap equalization is carried out on each subcarrier component obtained by fast Fourier trans- form (FFT). Equalization weights for joint FDE and antenna diversity com- bining based on maximal ratio combining (MRC), zero-forcing (ZF), and minimum

  10. Bionic wavelet transform: a new time-frequency method based on an auditory model

    Microsoft Academic Search

    Jun Yao; Yuan-Ting Zhang

    2001-01-01

    A new adaptive wavelet transform, named bionic wavelet transform (BWT), is developed based on a model of the active auditory system. The most distinguishing characteristic of BWT is that its resolution in the time-frequency domain can be adaptively adjusted not only by the signal frequency but also by the signal instantaneous amplitude and its first-order differential. The automatically adjusted resolution,

  11. Time-frequency analysis of electric motors

    SciTech Connect

    Bentley, C.L.; Dunn, M.E.; Mattingly, J.K. [Univ. of Tennessee, Knoxville, TN (United States); Casada, D. [Oak Ridge National Lab., TN (United States)

    1995-12-31

    Physical signals such as the current of an electric motor become nonstationary as a consequence of degraded operation and broken parts. In this instance, their power spectral densities become time dependent, and time-frequency analysis techniques become the appropriate tools for signal analysis. The first among these techniques, generally called the short-time Fourier transform (STFT) method, is the Gabor transform 2 (GT) of a signal S(t), which decomposes the signal into time-local frequency modes: where the window function, {Phi}(t-{tau}), is a normalized Gaussian. Alternatively, one can decompose the signal into its multi-resolution representation at different levels of magnification. This representation is achieved by the continuous wavelet transform (CWT) where the function g(t) is a kernel of zero average belonging to a family of scaled and shifted wavelet kernels. The CWT can be interpreted as the action of a microscope that locates the signal by the shift parameter b and adjusts its magnification by changing the scale parameter a. The Fourier-transformed CWT, W,{sub g}(a, {omega}), acts as a filter that places the high-frequency content of a signal into the lower end of the scale spectrum and vice versa for the low frequencies. Signals from a motor in three different states were analyzed.

  12. Time-frequency detection of Gravitational Waves

    E-print Network

    Warren G. Anderson; R. Balasubramanian

    1999-05-21

    We present a time-frequency method to detect gravitational wave signals in interferometric data. This robust method can detect signals from poorly modeled and unmodeled sources. We evaluate the method on simulated data containing noise and signal components. The noise component approximates initial LIGO interferometer noise. The signal components have the time and frequency characteristics postulated by Flanagan and Hughes for binary black hole coalescence. The signals correspond to binaries with total masses between $45 M_\\odot$ to $70 M_\\odot$ and with (optimal filter) signal-to-noise ratios of 7 to 12. The method is implementable in real time, and achieves a coincident false alarm rate for two detectors $\\approx$ 1 per 475 years. At this false alarm rate, the single detector false dismissal rate for our signal model is as low as 5.3% at an SNR of 10. We expect to obtain similar or better detection rates with this method for any signal of similar power that satisfies certain adiabaticity criteria. Because optimal filtering requires knowledge of the signal waveform to high precision, we argue that this method is likely to detect signals that are undetectable by optimal filtering, which is at present the best developed detection method for transient sources of gravitational waves.

  13. Postural tachycardia syndrome: time frequency mapping

    NASA Technical Reports Server (NTRS)

    Novak, V.; Novak, P.; Opfer-Gehrking, T. L.; Low, P. A.

    1996-01-01

    Orthostatic tachycardia is common but its specificity remains uncertain. Our preliminary work suggested that using autonomic function testing in conjunction with time-frequency mapping (TFM), it might be possible to characterize a subset of the postural tachycardia syndrome (POTS), that is due to a restricted autonomic neuropathy. We describe 20 patients (17 women and 3 men, aged 14-43 years) with florid POTS and 20 controls (14 women and 6 men, aged 20-41 years). Autonomic failure was quantified by its distribution (cardiovagal, adrenergic and sudomotor) and severity, a symptom profile was generated, and spectral indices, based on modified Wigner distribution during rest and head-up tilt (80 degrees) were evaluated. During tilt-up POTS patients differed from controls by an excessive heart rate (> 130 bpm) (P < 0.001), and higher diastolic pressure (P < 0.01). During rest, cardiovagal oscillations (at respiratory frequencies [RF]) and slow rhythms at nonrespiratory frequencies (NONRF) (from 0.01 to 0.07 Hz) in R-R intervals (RRI) (P < 0.01) were reduced. Both RF and NONRF rhythms in RRI were further blunted with tilt-up (P < 0.001). Slow adrenergic vasomotor rhythms in blood pressure (BP) (approximately 0.07 Hz) surged with tilt-up and returned to normal levels afterwards. The index of sympatho-vagal balance (NONRF-Systolic BP (SBP)/RF-RRI) was dramatically increased in POTS (P < 0.001). Distal postganglionic sudomotor failure was observed, and impairment of the BP responses to the Valsalva maneuver (phase II) suggested peripheral adrenergic dysfunction. Persistent orthostatic dizziness, tiredness, gastrointestinal symptoms and palpitations were common in POTS patients. It is possible to identify a subset of POTS patients who have a length-dependent autonomic neuropathy, affecting the peripheral adrenergic and cardiovagal fibers, with relative preservation of cardiac adrenergic fibers.

  14. An improved time-frequency phase adjustment technique for ISAR

    Microsoft Academic Search

    Mengmeng Zhu; Junfeng Wang; Xingzhao Liu

    2007-01-01

    The time-frequency method is a promising phase adjustment technique for inverse synthetic aperture radar (ISAR). Usually, the time-frequency method estimates the translational Doppler frequency and thus the translational Doppler phase by detecting the peaks of the time-frequency representation at different times. Unfortunately, it has some defects, such as the sensitivity to noise and target scintillation, and the aliasing of the

  15. Progressive orthogonal tilings of the time-frequency plane

    NASA Astrophysics Data System (ADS)

    Sola, Manuel A.; Sallent-Ribes, Sebastia

    1994-09-01

    This paper proposes a fast splitting algorithm (FSA) for a signal that when combined with an optimally criterion defined in the frequency domain leads to coherent tilings of the time- frequency plane. For a given set of basis regions formed by allowed subsets of the signal and a cost function defined over this set, we find the minimum cost cover of the signal by means of a fast algorithm. We show how when an additive cost measure is defined over the subband decomposition induced by a given filter bank, the method admits a solution in the form of a progressive orthogonal tiling. When progressive conditions are verified this method can be modelled with simple structures such as trellis diagrams or ordinary Petri nets. The extension of this method to bidimensional signals and conditions for fast algorithms are also discussed. The set of partitions obtained by the double tree algorithm is included in those considered by the FSA, allowing the later better signal analysis. We also present two approaches that reduced properly the complexity of the FSA maintaining the improvements of the method. The first one is based in constraining the set of basis regions to those with dyadic support, while the second one bounds the maximum support of basis regions.

  16. Time-frequency analysis of heart rate time series

    Microsoft Academic Search

    V. P. S. Naidu; P. Mahalakshmi

    2004-01-01

    Time-frequency distribution techniques viz., STFT, WVD and CWT were studied using simulated HRTS data. It is concluded that CWT showed better performance in time-frequency representation. This technique is extended to compute the real HRTS. It is observed from the CWT spectrum that more power is concentrated in low frequency region in MI patients and vice versa in case of normal

  17. IMPROVED BLIND SEPARATIONS OF NONSTATIONARY SOURCES BASED ON SPATIAL TIME-FREQUENCY DISTRIBUTIONS

    Microsoft Academic Search

    Yimin Zhang; Moeness G. Amin; Alan R. Lindsey

    Blind source separation (BSS) based on spatial time-frequ-ency distributions (STFDs) provides improved performance over blind source separation methods based on second-order statistics, when dealing with signals that are localizable in the time-frequency (t-f) domain. In this paper, we intro-duce a simple method for autoterm and crossterm selec-tion, and propose the use of STFD matrices for both pre-whitening and mixing matrix

  18. Joint Entropy for Space and Spatial Frequency Domains Estimated from Psychometric Functions of Achromatic Discrimination

    PubMed Central

    Silveira, Vladímir de Aquino; Souza, Givago da Silva; Gomes, Bruno Duarte; Rodrigues, Anderson Raiol; Silveira, Luiz Carlos de Lima

    2014-01-01

    We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4? or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint entropy for these stimulus conditions when contrast was raised. PMID:24466158

  19. Comparative performance analysis of time-frequency distributions for spectroscopic optical coherence tomography.

    PubMed

    Xu, Chenyang; Kamalabadi, Farzad; Boppart, Stephen A

    2005-04-01

    The analysis of spectroscopic optical coherence tomography (SOCT) signals suffers the trade-off between time resolution and frequency resolution. Various joint time-frequency distributions (TFDs) can optimize this trade-off. Synthesized signals were generated and experimentally acquired data were obtained to compare and validate several different TFDs under different SOCT imaging schemes. Specific criteria were designed to quantify the TFD performance. We found that different SOCT imaging schemes require different optimal TFDs. Cohen's class TFDs generate the most compact time-frequency (TF) analysis, while linear TFDs offer the most reliable TF analysis. In both cases, if some prior information is known, model-based TF analysis can improve the performance. PMID:15813517

  20. Carbon financial markets: A time-frequency analysis of CO2 prices

    NASA Astrophysics Data System (ADS)

    Sousa, Rita; Aguiar-Conraria, Luís; Soares, Maria Joana

    2014-11-01

    We characterize the interrelation of CO2 prices with energy prices (electricity, gas and coal), and with economic activity. Previous studies have relied on time-domain techniques, such as Vector Auto-Regressions. In this study, we use multivariate wavelet analysis, which operates in the time-frequency domain. Wavelet analysis provides convenient tools to distinguish relations at particular frequencies and at particular time horizons. Our empirical approach has the potential to identify relations getting stronger and then disappearing over specific time intervals and frequencies. We are able to examine the coherency of these variables and lead-lag relations at different frequencies for the time periods in focus.

  1. Communication over Multipath Fading Channels: A Time-Frequency Perspective

    Microsoft Academic Search

    Akbar M. Sayeed; Behnaam Aazhang

    1997-01-01

    Dynamics of multipath fading have a major effect on the performance of mobilewireless communication systems. The inherently time-varying nature of the mobilewireless channel makes nonstationary signal processing techniques particularly attractivefor system design. Time-frequency representations are powerful tools for timevaryingsignal processing, and in this paper, we present a time-frequency view ofwireless communication over multipath channels. Our discussion is anchored on afundamental

  2. Blind source separation using higher order time-frequency representations

    Microsoft Academic Search

    Ziauddin M. Kamran; A. Rahim Leyman; Karim Abed-Meraim

    2000-01-01

    A novel blind separation approach using higher-order time-frequency distributions is presented. The concept of higher-order time-frequency distribution matrix is also introduced. It is devised to primarily separate sources with temporal nonstationary signal characteristics. So far, this problem has been solved using statistical information available on the source signals. In contrast to well known blind source separation approaches using second-order statistics

  3. Transmission Line Fault Detection Using Time-Frequency Analysis

    Microsoft Academic Search

    S. R. Samantaray; P. K. Dash; G. Panda

    2005-01-01

    A new approach for fault detection in power system network using time-frequency analysis is presented in this paper. The S-transform with complex window is used for generating frequency contours(S-contours), which distinguishes the faulted condition from no-fault. Here the fault current data for one cycle back and one cycle from the fault inception is processed through S-transform to generate time-frequency patterns

  4. A joint watermarking/encryption algorithm for verifying medical image integrity and authenticity in both encrypted and spatial domains.

    PubMed

    Bouslimi, D; Coatrieux, G; Roux, Ch

    2011-01-01

    In this paper, we propose a new joint watermarking/encryption algorithm for the purpose of verifying the reliability of medical images in both encrypted and spatial domains. It combines a substitutive watermarking algorithm, the quantization index modulation (QIM), with a block cipher algorithm, the Advanced Encryption Standard (AES), in CBC mode of operation. The proposed solution gives access to the outcomes of the image integrity and of its origins even though the image is stored encrypted. Experimental results achieved on 8 bits encoded Ultrasound images illustrate the overall performances of the proposed scheme. By making use of the AES block cipher in CBC mode, the proposed solution is compliant with or transparent to the DICOM standard. PMID:22256213

  5. A method for constructing orthonormal basis functions with good time-frequency localization

    NASA Astrophysics Data System (ADS)

    Gertner, Izidor

    2013-05-01

    In this paper we derive an explicit, single expression for a complex-valued, orthonormal basis well localized in time-frequency domain. We construct it from a single real function ?(x) which is a Gaussian divided by the square root of a Jacobi theta ?3 function. Then we simplify ?(x) to the form of inverse square root of a Jacobi theta ?3 function. We show that the shape of ?(x) can be changed from Gaussian-like to rectangular-like with a single parameter. The basis generating function ?(x) and its Fourier transform ? have exponential decay. We also show how to modify a standard I and Q processor to compute complex-valued time-frequency expansion coefficients.

  6. Comparison of Signals from Gravitational Wave Detectors with Instantaneous Time-Frequency Maps

    NASA Technical Reports Server (NTRS)

    Stroeer, A.; Blackburn, L.; Camp, J.

    2011-01-01

    Gravitational wave astronomy relies on the use of multiple detectors, so that coincident detections may distinguish real signals from instrumental artifacts, and also so that relative timing of signals can provide the sky position of sources. We show that the comparison of instantaneous time-frequency and time-amplitude maps provided by the Hilbert-Huang Transform (HHT) can be used effectively for relative signal timing of common signals, to discriminate between the case of identical coincident signals and random noise coincidences and to provide a classification of signals based on their time-frequency trajectories. The comparison is done with a X(sup 2) goodness-offit method which includes contributions from both the instantaneous amplitude and frequency components of the HHT to match two signals in the time domain. This approach naturally allows the analysis of waveforms with strong frequency modulation.

  7. Image hiding in Fourier domain by use of joint transform correlator architecture and holographic technique.

    PubMed

    Shi, Xiaoyan; Zhao, Daomu

    2011-02-10

    Based on joint transform correlator (JTC) architecture and holographic techniques, a new method for image hiding is presented. A hidden image encrypted by JTC architecture is embedded in the Fourier hologram of the host image. Inverse Fourier transform can be used to obtain the watermarked image, and JTC architecture is used to decode the hidden image from the watermarked hologram. Unlike other watermarking techniques, by prechoosing information, the noise added to the recovered hidden image by the host can be reduced. Unlike other watermarking systems based on double random-phase encoding, no conjugate key is used to recover the hidden image. Theoretical analyses have shown the system's feasibility. Computer simulations are presented to verify the system's validity and efficiency. Numerical simulations also show that the proposed system is robust enough to resist attacks, such as occlusion, noise, and filtering. PMID:21343999

  8. Speckle reduction by energy time-frequency filtering.

    PubMed

    Izquierdo, M A G; Hernández, M G; Anaya, J J; Martinez, O

    2004-04-01

    Structural noise is a very important limitation to the visibility of flaw echoes in ultrasonic testing and evaluation of highly scattering materials. In order to enhance the signal-to-noise ratio, different algorithms have been developed. One of these techniques is based on filtering the spectrum low band of the received echo to obtain a significant improvement of the defect visibility. Based on this idea, in this work a new time-frequency technique is presented. In this method, block-processing autoregressive techniques are used to estimate the instantaneous center frequency of the traveling wave. From this information, a time-frequency filter is designed tuned at half the estimated instantaneous center frequency. Experimental results and the comparison with the non-time-frequency filtering technique are also included, showing that the proposed method has an excellent performance on SNR enhancement. PMID:15047394

  9. Backscattering of transients by tilted truncated cylindrical shells: Time-frequency identification of ray contributions from measurements

    Microsoft Academic Search

    Scot F. Morse; Philip L. Marston

    2002-01-01

    Impulse backscattering measurements by a thick-walled finite cylindrical shell are examined in the time-frequency domain to identify and characterize individual ray contributions from generalized Lamb waves excited on the shell. Previous experiments and analysis in the frequency-aspect angle domain [S. F. Morse et al., J. Acoust. Soc. Am. 103, 785-794 (1998)] indicate that large backscattering enhancements occur in the midfrequency

  10. Electrocardiogram Signal and Linear Time-Frequency Transforms

    NASA Astrophysics Data System (ADS)

    Krishna, B. T.

    2014-12-01

    The diagnostic analysis of non-stationary multi component signals such as electrocardiogram (ECG) involves the use of time-frequency transforms. So, the application of time-frequency transforms to an ECG signal is an important problem of research. In this paper, initially, linear transforms like short time Fourier transform, continuous wavelet transforms, s-transform etc. are revisited. Then the application of these transforms to normal and abnormal ECG signals is illustrated. It has been observed that s-transform provides better time and frequency resolution compared to other linear transforms. The fractional Fourier transform provides rotation to the spectrogram representation.

  11. Improving electroencephalographic source localization of epileptogenic zones with time-frequency analysis.

    PubMed

    Cuspineda-Bravo, Elena R; Martínez-Montes, Eduardo; Farach-Fumero, Miguel; Machado-Curbelo, Calixto

    2015-04-01

    The combination of recently developed methods for electroencephalographic (EEG) space-time-frequency analysis can provide noninvasive functional neuroimages necessary for obtaining an accurate localization of the epileptogenic zone. The aim of this study was to determine if time-frequency (TF) analysis, followed by EEG source localization, would improve the detection and identification of epileptogenic and related activity. Seventeen patients with refractory frontal lobe epilepsy (FLE) were studied using video EEG recording. TF analysis identified the first epileptogenic EEG changes. Using the Bayesian model averaging (BMA) approach, we compared brain electromagnetic tomographic (BET) images, constructed from the TF domain, with BET images constructed from the time domain only. We determined if the localization identified by BET images was concordant with the localization from medical history and video EEG recording. TF analysis provided a clear display of subtle EEG features, including EEG lateralization, and more concordant and delimited epileptogenic zones, compared with time-domain source analysis. In conclusion, EEG TF analysis improves source localization. After a thorough validation, this methodology could become a useful noninvasive tool for localizing the epileptogenic zone in clinical practice. PMID:24879437

  12. Sound Morphing Strategies based on alterations of Time-Frequency

    E-print Network

    Paris-Sud XI, Université de

    Sound Morphing Strategies based on alterations of Time-Frequency representations by Gabor morphing is an important topic in signal processing of musical sounds and covers a wide variety to parametrize it for static morphing between two sounds. We then compare such an approach with standard and non

  13. Orthogonal time-frequency signaling over doubly dispersive channels

    Microsoft Academic Search

    Ke Liu; Tamer Kadous; Akbar M. Sayeed

    2004-01-01

    Abstract This paper develops a general signaling framework for communication over doubly dispersive fad - ing channels via an orthogonal short - time Fourier (STF) basis The STF basis is generated from a prototype pulse via time - frequency shifts The orthogonality between basis functions is destroyed at the receiver due to channel dispersion, resulting in interference between them It

  14. Linear and quadratic time-frequency signal representations

    Microsoft Academic Search

    F. Hlawatsch; G. F. Boudreaux-Bartels

    1992-01-01

    A tutorial review of both linear and quadratic representations is given. The linear representations discussed are the short-time Fourier transform and the wavelet transform. The discussion of quadratic representations concentrates on the Wigner distribution, the ambiguity function, smoothed versions of the Wigner distribution, and various classes of quadratic time-frequency representations. Examples of the application of these representations to typical problems

  15. Blind source separation based on time-frequency signal representations

    Microsoft Academic Search

    Adel Belouchrani; Moeness G. Amin

    1998-01-01

    Blind source separation consists of recovering a set of signals of which only instantaneous linear mixtures are observed. Thus far, this problem has been solved using statistical information available on the source signals. This paper introduces a new blind source separation approach exploiting the difference in the time-frequency (t-f) signatures of the sources to be separated. The approach is based

  16. CAD OF MICROWAVE OPTICAL SYSTEMS FOR TIME&FREQUENCY APPLICATIONS

    E-print Network

    Boyer, Edmond

    signal distribution in a system, taking benefit of the low losses of the optical fibers, on the devices biasing circuits, on the quality of the optical fiber and, above all, on the topology chosenCAD OF MICROWAVE OPTICAL SYSTEMS FOR TIME&FREQUENCY APPLICATIONS Houda Brahimi, LAAS-CNRS, Toulouse

  17. Time-frequency analysis of the glottal opening

    Microsoft Academic Search

    Wolfgang Wokurek

    1997-01-01

    Simultaneous recordings of the laryngograph signal and speech recorded in an non-reverberating environment are investigated for acoustic evidence of the glottal opening within the microphone signal. It is demonstrated that the high resolution time-frequency analysis of the microphone signal by the smoothed pseudo Wigner distribution (SPWD) shows responses of the vocal tract to both, the glottal closure and the glottal

  18. Maher Audio Enhancement via Time-Frequency Filtering AUDIO ENHANCEMENT

    E-print Network

    Maher, Robert C.

    Maher Audio Enhancement via Time-Frequency Filtering AUDIO ENHANCEMENT USING NONLINEAR TIME on a time-varying spectral representation of the noisy signal. The enhancement process adapts to the instantaneous signal behavior and alters the noisy signal so that the enhanced output signal is higher

  19. Time-frequency analysis of extreme-mass-ratio inspiral signals in mock LISA data

    E-print Network

    Jonathan R Gair; Ilya Mandel; Linqing Wen

    2007-10-27

    Extreme-mass-ratio inspirals (EMRIs) of ~ 1-10 solar-mass compact objects into ~ million solar-mass massive black holes can serve as excellent probes of strong-field general relativity. The Laser Interferometer Space Antenna (LISA) is expected to detect gravitational wave signals from apprxomiately one hundred EMRIs per year, but the data analysis of EMRI signals poses a unique set of challenges due to their long duration and the extensive parameter space of possible signals. One possible approach is to carry out a search for EMRI tracks in the time-frequency domain. We have applied a time-frequency search to the data from the Mock LISA Data Challenge (MLDC) with promising results. Our analysis used the Hierarchical Algorithm for Clusters and Ridges to identify tracks in the time-frequency spectrogram corresponding to EMRI sources. We then estimated the EMRI source parameters from these tracks. In these proceedings, we discuss the results of this analysis of the MLDC round 1.3 data.

  20. Time-frequency Wiener filtering for structural noise reduction.

    PubMed

    Izquierdo, M A G; Hernández, M G; Graullera, O; Ullate, L G

    2002-05-01

    In order to enhance the defect in relation to background noise of large grained materials different algorithms have been developed. Wiener filtering techniques have proved to be efficient for the SNR enhancement of ultrasonic signals coming from highly scattering materials. These processing algorithms are based on designing a filter that has large gain at frequencies where the SNR is high and low gain at frequencies where SNR is small. However, this technique does not consider two important ultrasonic effects: the finite-time duration of the flaw UT signal coming from a defect and the distortion of the frequency components of the traveling wave-front due to the dispersion. In this work, a time-frequency Wiener filter is proposed that takes into account these two characteristics. Experimental results are presented, showing that the proposed time-frequency algorithm has an excellent performance on SNR enhancement. PMID:12159944

  1. Computing Deblurred Time-Frequency Distributions Using Artificial Neural Networks

    Microsoft Academic Search

    Imran Shafi; Jamil Ahmad; Syed Ismail Shah; Faisal M. Kashif

    2008-01-01

    This paper presents an effective correlation vectored taxonomy algorithm to compute highly concentrated time-frequency distributions\\u000a (TFDs) using localized neural networks (LNNs). Spectrograms and pre-processed Wigner–Ville distributions of known signals\\u000a are vectorized and clustered as per the elbow criterion to constitute the training data for multiple artificial neural networks.\\u000a The best trained networks become part of the LNNs. Test TFDs of

  2. Time-frequency analysis and Harmonic Gaussian Functions

    E-print Network

    Tokiniaina Ranaivoson; Raoelina Andriambololona; Rakotoson Hanitriarivo

    2013-08-08

    A method for time-frequency analysis is given. The approach utilizes properties of Gaussian distribution, properties of Hermite polynomials and Fourier analysis. We begin by the definitions of a set of functions called harmonic Gaussian functions. Then these functions are used to define a set of transformations,noted T_n, which associate to a function {\\psi},of the time variable t, a set of functions {\\Psi}_n which depend on time, frequency and frequency (or time) standard deviation. Some properties of the transformations T_n and the functions {\\Psi}_n are given. It is proved in particular that the square of the modulus of each function {\\Psi}_n can be interpreted as a representation of the energy distribution of the signal, represented by the function {\\psi}, in the time-frequency plane for a given value of the frequency (or time) standard deviation. It is also shown that the function {\\psi}, can be recovered from the functions{\\Psi}_n.

  3. Time-Frequency Approach for Stochastic Signal Detection

    SciTech Connect

    Ghosh, Ripul; Akula, Aparna; Kumar, Satish; Sardana, H. K. [Academy of Scientific and Innovative Research (AcSIR), Central Scientific Instruments Organisation, Chandigarh - 160030 (India)

    2011-10-20

    The detection of events in a stochastic signal has been a subject of great interest. One of the oldest signal processing technique, Fourier Transform of a signal contains information regarding frequency content, but it cannot resolve the exact onset of changes in the frequency, all temporal information is contained in the phase of the transform. On the other hand, Spectrogram is better able to resolve temporal evolution of frequency content, but has a trade-off in time resolution versus frequency resolution in accordance with the uncertainty principle. Therefore, time-frequency representations are considered for energetic characterisation of the non-stationary signals. Wigner Ville Distribution (WVD) is the most prominent quadratic time-frequency signal representation and used for analysing frequency variations in signals.WVD allows for instantaneous frequency estimation at each data point, for a typical temporal resolution of fractions of a second. This paper through simulations describes the way time frequency models are applied for the detection of event in a stochastic signal.

  4. Detecting fixation on a target using time-frequency distributions of a retinal birefringence scanning signal

    PubMed Central

    2013-01-01

    Background The fovea, which is the most sensitive part of the retina, is known to have birefringent properties, i.e. it changes the polarization state of light upon reflection. Existing devices use this property to obtain information on the orientation of the fovea and the direction of gaze. Such devices employ specific frequency components that appear during moments of fixation on a target. To detect them, previous methods have used solely the power spectrum of the Fast Fourier Transform (FFT), which, unfortunately, is an integral method, and does not give information as to where exactly the events of interest occur. With very young patients who are not cooperative enough, this presents a problem, because central fixation may be present only during very short-lasting episodes, and can easily be missed by the FFT. Method This paper presents a method for detecting short-lasting moments of central fixation in existing devices for retinal birefringence scanning, with the goal of a reliable detection of eye alignment. Signal analysis is based on the Continuous Wavelet Transform (CWT), which reliably localizes such events in the time-frequency plane. Even though the characteristic frequencies are not always strongly expressed due to possible artifacts, simple topological analysis of the time-frequency distribution can detect fixation reliably. Results In all six subjects tested, the CWT allowed precise identification of both frequency components. Moreover, in four of these subjects, episodes of intermittent but definitely present central fixation were detectable, similar to those in Figure 4. A simple FFT is likely to treat them as borderline cases, or entirely miss them, depending on the thresholds used. Conclusion Joint time-frequency analysis is a powerful tool in the detection of eye alignment, even in a noisy environment. The method is applicable to similar situations, where short-lasting diagnostic events need to be detected in time series acquired by means of scanning some substrate along a specific path. PMID:23668264

  5. Time-frequency analysis of the bistatic acoustic scattering from a spherical elastic shell.

    PubMed

    Anderson, Shaun D; Sabra, Karim G; Zakharia, Manell E; Sessarego, Jean-Pierre

    2012-01-01

    The development of low-frequency sonar systems, using, for instance, a network of autonomous systems in unmanned vehicles, provides a practical means for bistatic measurements (i.e., when the source and receiver are widely separated) allowing for multiple viewpoints of the target of interest. Time-frequency analysis, in particular, Wigner-Ville analysis, takes advantage of the evolution time dependent aspect of the echo spectrum to differentiate a man-made target, such as an elastic spherical shell, from a natural object of the similar shape. A key energetic feature of fluid-loaded and thin spherical shell is the coincidence pattern, also referred to as the mid-frequency enhancement (MFE), that results from antisymmetric Lamb-waves propagating around the circumference of the shell. This article investigates numerically the bistatic variations of the MFE with respect to the monostatic configuration using the Wigner-Ville analysis. The observed time-frequency shifts of the MFE are modeled using a previously derived quantitative ray theory by Zhang et al. [J. Acoust. Soc. Am. 91, 1862-1874 (1993)] for spherical shell's scattering. Additionally, the advantage of an optimal array beamformer, based on joint time delays and frequency shifts is illustrated for enhancing the detection of the MFE recorded across a bistatic receiver array when compared to a conventional time-delay beamformer. PMID:22280581

  6. Vibration signal analysis using parameterized time-frequency method for features extraction of varying-speed rotary machinery

    NASA Astrophysics Data System (ADS)

    Yang, Y.; Dong, X. J.; Peng, Z. K.; Zhang, W. M.; Meng, G.

    2015-01-01

    In real application, when rotary machinery frequently involves variable-speed, unsteady load and defect, it will produce non-stationary vibration signal. Such signal can be characterized by mono- or multi-component frequency modulation (FM) and its internal instantaneous patterns are closely related to operation condition of the rotary machinery. For example, instantaneous frequency (IF) and instantaneous amplitude (IA) of a non-stationary signal are two important time-frequency features to be inspected. For vibration signal analysis of the rotary machinery, time-frequency analysis (TFA), known for analyzing the signal in the time and frequency domain simultaneously, has been accepted as a key signal processing tool. Particularly, parameterized TFA, among various TFAs, has shown great potential to investigate time-frequency features of non-stationary signals. It attracts more attention for improving time-frequency representation (TFR) with signal-dependent transform parameters. However, the parameter estimation and component separation are two problems to tackle with while using the parameterized TFA to extract time-frequency features from non-stationary vibration signal of varying-speed rotary machinery. In this paper, we propose a procedure for the parameterized TFA to analyze the non-stationary vibration signal of varying-speed rotary machinery. It basically includes four steps: initialization, estimation of transform parameter, component separation and parameterized TFA, as well as feature extraction. To demonstrate the effectiveness of the proposed method in analyzing mono- and multi-component signals, it is first used to analyze the vibration response of a laboratory rotor during a speed-up and run-down process, and then extract the instantaneous time-frequency signatures of a hydro-turbine rotor in a hydroelectric power station during a shut-down stage. In addition, the results are compared with several traditional TFAs and the proposed method outperforms others in accurate feature extraction, which is promising in applications of fault detection, system condition monitoring, parameter identification, etc.

  7. Faster learning algorithm convergence utilizing a combined time-frequency representation as basis

    NASA Astrophysics Data System (ADS)

    Hendriks, A. J.; Uys, Hermann; du Plessis, Anton; Steenkamp, Christine

    2013-10-01

    Light is capable of directly manipulating and probing molecular dynamics at its most fundamental level. One versatile approach to influencing such dynamics exploits temporally shaped femtosecond laser pulses. Oftentimes the control mechanisms necessary to induce a desired reaction cannot be determined theoretically a priori. However under certain circumstances these mechanisms can be extracted experimentally through trial and error. This can be implemented systematically by using an evolutionary learning algorithm (LA) with closed loop feedback. Most frequently, pulse shaping algorithms operate within either the time or frequency domain, however seldom both. This may influence the physical insight gained due to dependence on the search basis, as well as influence the speed the algorithm takes to converge. As an alternative to the Fourier domain basis, we make use of a combined time-frequency representation known as the von Neumann basis where we observe temporal and spectral effects at the same time. We report on the numerical and experimental results obtained using the Fourier, as well as the von Neumann basis to maximize the second harmonic generation (SHG) output in a non-linear crystal. We show that the von Neumann representation converges faster than the Fourier domain when compared to searches in the Fourier domain. We also show a reduced parameter space is required for the Fourier domain to converge efficiently, but not for von Neumann domain. Finally we show the highest SHG signal is not only a consequence of the shortest pulse, but that the pulse central frequency also plays a key role. Taken together these results suggest that the von Neumann basis can be used as a viable alternative to the Fourier domain with improved convergence time and potentially deeper physical insight.

  8. Detecting LISA sources using time-frequency techniques

    E-print Network

    Jonathan R Gair; Gareth Jones

    2007-03-06

    The planned Laser Interferometer Space Antenna (LISA) will detect gravitational wave signals from a wide range of sources. However, disentangling individual signals from the source-dominated data stream is a challenging problem and the focus of much current research. The problems are particularly acute for detection of extreme mass ratio inspirals (EMRIs), for which the instantaneous signal amplitude is an order of magnitude below the level of the instrumental noise, and the parameter space of possible signals is too large to permit fully-coherent matched filtering. One possible approach is to attempt to identify sources in a time-frequency spectrogram of the LISA data. This is a computationally cheap method that may be useful as a first stage in a hierarchical analysis. Initial results, evaluated using a significantly simplified model of the LISA data stream, suggest that time-frequency techniques might be able to detect the nearest few tens of EMRI events. In this proceedings article, we briefly outline the methods that have so far been applied to the problem, initial results and possible future directions for the research.

  9. The Application of Time-Frequency Methods to HUMS

    NASA Technical Reports Server (NTRS)

    Pryor, Anna H.; Mosher, Marianne; Lewicki, David G.; Norvig, Peter (Technical Monitor)

    2001-01-01

    This paper reports the study of four time-frequency transforms applied to vibration signals and presents a new metric for comparing them for fault detection. The four methods to be described and compared are the Short Time Frequency Transform (STFT), the Choi-Williams Distribution (WV-CW), the Continuous Wavelet Transform (CWT) and the Discrete Wavelet Transform (DWT). Vibration data of bevel gear tooth fatigue cracks, under a variety of operating load levels, are analyzed using these methods. The new metric for automatic fault detection is developed and can be produced from any systematic numerical representation of the vibration signals. This new metric reveals indications of gear damage with all of the methods on this data set. Analysis with the CWT detects mechanical problems with the test rig not found with the other transforms. The WV-CW and CWT use considerably more resources than the STFT and the DWT. More testing of the new metric is needed to determine its value for automatic fault detection and to develop methods of setting the threshold for the metric.

  10. Optimal GPR bandwidth for time-frequency landmine discrimination

    NASA Astrophysics Data System (ADS)

    Savelyev, Timofei G.; Sato, Motoyuki

    2005-06-01

    In this work we investigate which bandwidth of a ground penetrating radar (GPR) is optimal for time-frequency landmine discrimination. We extracted three time-frequency features of the early-time target response from the Wigner distribution. The features were found to be relatively invariant to target depth for a data acquired with a stepped-frequency ultra-wideband GPR. The frequency sweep was from 0.3 GHz up to 6 GHz. The features allowed discrimination of two different low-metal landmines from a mine-like stone. The results were visualized in the three-dimensional feature space where each point related to a certain target represents a certain GPR scenario. For a number of scenarios we obtained two separated clusters for the landmines and the stone respectively. Numerically the quality of target discrimination can be evaluated with the Mahalanobis distance which estimates the separation between such feature clusters accounting for their size. Here we use the Mahalanobis distance as a criterion of optimality for the GPR bandwidth. Having obtained good results for the large data bandwidth, we reduce it by digital filtering with a small step in changing the cut-off frequencies, then extract the features and compute the Mahalanobis distance between the landmines and the stone. Its maximal value defines the optimal GPR lower and upper frequencies.

  11. Joint annotation of chromatin state and chromatin conformation reveals relationships among domain types and identifies domains of cell-type-specific expression.

    PubMed

    Libbrecht, Maxwell W; Ay, Ferhat; Hoffman, Michael M; Gilbert, David M; Bilmes, Jeffrey A; Noble, William Stafford

    2015-04-01

    The genomic neighborhood of a gene influences its activity, a behavior that is attributable in part to domain-scale regulation. Previous genomic studies have identified many types of regulatory domains. However, due to the difficulty of integrating genomics data sets, the relationships among these domain types are poorly understood. Semi-automated genome annotation (SAGA) algorithms facilitate human interpretation of heterogeneous collections of genomics data by simultaneously partitioning the human genome and assigning labels to the resulting genomic segments. However, existing SAGA methods cannot integrate inherently pairwise chromatin conformation data. We developed a new computational method, called graph-based regularization (GBR), for expressing a pairwise prior that encourages certain pairs of genomic loci to receive the same label in a genome annotation. We used GBR to exploit chromatin conformation information during genome annotation by encouraging positions that are close in 3D to occupy the same type of domain. Using this approach, we produced a model of chromatin domains in eight human cell types, thereby revealing the relationships among known domain types. Through this model, we identified clusters of tightly regulated genes expressed in only a small number of cell types, which we term "specific expression domains." We found that domain boundaries marked by promoters and CTCF motifs are consistent between cell types even when domain activity changes. Finally, we showed that GBR can be used to transfer information from well-studied cell types to less well-characterized cell types during genome annotation, making it possible to produce high-quality annotations of the hundreds of cell types with limited available data. PMID:25677182

  12. Cross time-frequency analysis for combining information of several sources: application to estimation of spontaneous respiratory rate from photoplethysmography.

    PubMed

    Peláez-Coca, M D; Orini, M; Lázaro, J; Bailón, R; Gil, E

    2013-01-01

    A methodology that combines information from several nonstationary biological signals is presented. This methodology is based on time-frequency coherence, that quantifies the similarity of two signals in the time-frequency domain. A cross time-frequency analysis method, based on quadratic time-frequency distribution, has been used for combining information of several nonstationary biomedical signals. In order to evaluate this methodology, the respiratory rate from the photoplethysmographic (PPG) signal is estimated. The respiration provokes simultaneous changes in the pulse interval, amplitude, and width of the PPG signal. This suggests that the combination of information from these sources will improve the accuracy of the estimation of the respiratory rate. Another target of this paper is to implement an algorithm which provides a robust estimation. Therefore, respiratory rate was estimated only in those intervals where the features extracted from the PPG signals are linearly coupled. In 38 spontaneous breathing subjects, among which 7 were characterized by a respiratory rate lower than 0.15 Hz, this methodology provided accurate estimates, with the median error {0.00; 0.98}?mHz ({0.00; 0.31}%) and the interquartile range error {4.88; 6.59}?mHz ({1.60; 1.92}%). The estimation error of the presented methodology was largely lower than the estimation error obtained without combining different PPG features related to respiration. PMID:24363777

  13. Cross Time-Frequency Analysis for Combining Information of Several Sources: Application to Estimation of Spontaneous Respiratory Rate from Photoplethysmography

    PubMed Central

    Peláez-Coca, M. D.; Orini, M.; Lázaro, J.; Bailón, R.; Gil, E.

    2013-01-01

    A methodology that combines information from several nonstationary biological signals is presented. This methodology is based on time-frequency coherence, that quantifies the similarity of two signals in the time-frequency domain. A cross time-frequency analysis method, based on quadratic time-frequency distribution, has been used for combining information of several nonstationary biomedical signals. In order to evaluate this methodology, the respiratory rate from the photoplethysmographic (PPG) signal is estimated. The respiration provokes simultaneous changes in the pulse interval, amplitude, and width of the PPG signal. This suggests that the combination of information from these sources will improve the accuracy of the estimation of the respiratory rate. Another target of this paper is to implement an algorithm which provides a robust estimation. Therefore, respiratory rate was estimated only in those intervals where the features extracted from the PPG signals are linearly coupled. In 38 spontaneous breathing subjects, among which 7 were characterized by a respiratory rate lower than 0.15 Hz, this methodology provided accurate estimates, with the median error {0.00; 0.98}?mHz ({0.00; 0.31}%) and the interquartile range error {4.88; 6.59}?mHz ({1.60; 1.92}%). The estimation error of the presented methodology was largely lower than the estimation error obtained without combining different PPG features related to respiration. PMID:24363777

  14. Time-frequency analysis of synthetic aperture radar signals

    SciTech Connect

    Johnston, B.

    1996-08-01

    Synthetic aperture radar (SAR) has become an important tool for remote sensing of the environment. SAR is a set of digital signal processing algorithms that are used to focus the signal returned to the radar because radar systems in themselves cannot produce the high resolution images required in remote sensing applications. To reconstruct an image, several parameters must be estimated and the quality of output image depends on the degree of accuracy of these parameters. In this thesis, we derive the fundamental SAR algorithms and concentrate on the estimation of one of its critical parameters. We show that the common technique for estimating this particular parameter can sometimes lead to erroneous results and reduced quality images. We also employ time-frequency analysis techniques to examine variations in the radar signals caused by platform motion and show how these results can be used to improve output image quality.

  15. Time-Frequency Analysis Reveals Pairwise Interactions in Insect Swarms

    NASA Astrophysics Data System (ADS)

    Puckett, James G.; Ni, Rui; Ouellette, Nicholas T.

    2015-06-01

    The macroscopic emergent behavior of social animal groups is a classic example of dynamical self-organization, and is thought to arise from the local interactions between individuals. Determining these interactions from empirical data sets of real animal groups, however, is challenging. Using multicamera imaging and tracking, we studied the motion of individual flying midges in laboratory mating swarms. By performing a time-frequency analysis of the midge trajectories, we show that the midge behavior can be segmented into two distinct modes: one that is independent and composed of low-frequency maneuvers, and one that consists of higher-frequency nearly harmonic oscillations conducted in synchrony with another midge. We characterize these pairwise interactions, and make a hypothesis as to their biological function.

  16. A new time-frequency analysis method for gyro signal denoising

    NASA Astrophysics Data System (ADS)

    Lu, Yanhong; Xu, Yefeng

    2006-11-01

    Gyro output signal is a non-stationary and time-varied time series mixed with noise. A new time-frequency analysis method for gyro de-noising, the empirical mode decomposition (EMD), is introduced. The non-stationary hybrid gyro signal is studied adaptively in the domain of time and frequency. First the hybrid signal is decomposed into finite intrinsic mode functions (IMF), then their frequency characteristic and the relationship between these IMFs and different gyro errors are studied deeply. Follow that a certain number of IMFs are eliminated and EMD's filter bank characteristic is achieved. After the ring laser gyro signal is processed by EMD and wavelet, Allan variance approach is applied to evaluate five kinds of gyro noise. By the conclusion, the EMD method is obviously more efficacious than wavelet in eliminating various kind of noise.

  17. Joint Inversion of Body-Wave Arrival Times and Surface-Wave Dispersion Data in the Wavelet Domain Constrained by Sparsity Regularization

    NASA Astrophysics Data System (ADS)

    Zhang, H.; Fang, H.; Yao, H.; Maceira, M.; van der Hilst, R. D.

    2014-12-01

    Recently, Zhang et al. (2014, Pure and Appiled Geophysics) have developed a joint inversion code incorporating body-wave arrival times and surface-wave dispersion data. The joint inversion code was based on the regional-scale version of the double-difference tomography algorithm tomoDD. The surface-wave inversion part uses the propagator matrix solver in the algorithm DISPER80 (Saito, 1988) for forward calculation of dispersion curves from layered velocity models and the related sensitivities. The application of the joint inversion code to the SAFOD site in central California shows that the fault structure is better imaged in the new model, which is able to fit both the body-wave and surface-wave observations adequately. Here we present a new joint inversion method that solves the model in the wavelet domain constrained by sparsity regularization. Compared to the previous method, it has the following advantages: (1) The method is both data- and model-adaptive. For the velocity model, it can be represented by different wavelet coefficients at different scales, which are generally sparse. By constraining the model wavelet coefficients to be sparse, the inversion in the wavelet domain can inherently adapt to the data distribution so that the model has higher spatial resolution in the good data coverage zone. Fang and Zhang (2014, Geophysical Journal International) have showed the superior performance of the wavelet-based double-difference seismic tomography method compared to the conventional method. (2) For the surface wave inversion, the joint inversion code takes advantage of the recent development of direct inversion of surface wave dispersion data for 3-D variations of shear wave velocity without the intermediate step of phase or group velocity maps (Fang et al., 2014, Geophysical Journal International). A fast marching method is used to compute, at each period, surface wave traveltimes and ray paths between sources and receivers. We will test the new joint inversion code at the SAFOD site to compare its performance over the previous code. We will also select another fault zone such as the San Jacinto Fault Zone to better image its structure.

  18. Human Intracranial High Frequency Oscillations (HFOs) Detected by Automatic Time-Frequency Analysis

    PubMed Central

    Burnos, Sergey; Hilfiker, Peter; Sürücü, Oguzkan; Scholkmann, Felix; Krayenbühl, Niklaus; Grunwald, Thomas; Sarnthein, Johannes

    2014-01-01

    Objectives High frequency oscillations (HFOs) have been proposed as a new biomarker for epileptogenic tissue. The exact characteristics of clinically relevant HFOs and their detection are still to be defined. Methods We propose a new method for HFO detection, which we have applied to six patient iEEGs. In a first stage, events of interest (EoIs) in the iEEG were defined by thresholds of energy and duration. To recognize HFOs among the EoIs, in a second stage the iEEG was Stockwell-transformed into the time-frequency domain, and the instantaneous power spectrum was parameterized. The parameters were optimized for HFO detection in patient 1 and tested in patients 2–5. Channels were ranked by HFO rate and those with rate above half maximum constituted the HFO area. The seizure onset zone (SOZ) served as gold standard. Results The detector distinguished HFOs from artifacts and other EEG activity such as interictal epileptiform spikes. Computation took few minutes. We found HFOs with relevant power at frequencies also below the 80–500 Hz band, which is conventionally associated with HFOs. The HFO area overlapped with the SOZ with good specificity > 90% for five patients and one patient was re-operated. The performance of the detector was compared to two well-known detectors. Conclusions Compared to methods detecting energy changes in filtered signals, our second stage - analysis in the time-frequency domain - discards spurious detections caused by artifacts or sharp epileptic activity and improves the detection of HFOs. The fast computation and reasonable accuracy hold promise for the diagnostic value of the detector. PMID:24722663

  19. Nonlinear Time-Frequency Control Theory with Applications 

    E-print Network

    Liu, Mengkun 1978-

    2012-10-04

    Nonlinear control is an important subject drawing much attention. When a nonlinear system undergoes route-to-chaos, its response is naturally bounded in the time-domain while in the meantime becoming unstably broadband ...

  20. Time-Frequency Modeling and Detection of random non-stationary signals for Monitoring Purposes

    E-print Network

    Paris-Sud XI, Université de

    Time-Frequency Modeling and Detection of random non-stationary signals for Monitoring Purposes This paper deals with the modelization and detection of non-stationary random signals in the time-frequency space. A time-frequency random model of signal is derived from a given temporal model. The time model we

  1. TIME-FREQUENCY-PHASE TRACKING APPROACH : APPLICATION TO UNDERWATER SIGNALS IN A PASSIVE CONTEXT

    E-print Network

    Paris-Sud XI, Université de

    TIME-FREQUENCY-PHASE TRACKING APPROACH : APPLICATION TO UNDERWATER SIGNALS IN A PASSIVE CONTEXT of time-frequency representations deals with the analysis of the signal issued from natural environment of the information carried out by the natural signals. Taken into account the non-linear multi-component time-frequency

  2. Time-Frequency Jigsaw Puzzle: Adaptive multiwindow and multilayered Gabor expansions

    E-print Network

    Torrésani, Bruno

    1 Time-Frequency Jigsaw Puzzle: Adaptive multiwindow and multilayered Gabor expansions Florent, which adapt dynamically the windows to the signal's features in time-frequency space. The adaptation is based upon local time-frequency sparsity criteria, and also yields as by- product an expansion

  3. Trainees' Perceived Knowledge Gain Unrelated to the Training Domain: The Joint Action of Impression Management and Motives

    ERIC Educational Resources Information Center

    Chiaburu, Dan S.; Huang, Jason L.; Hutchins, Holly M.; Gardner, Richard G.

    2014-01-01

    Trainees' knowledge gains represent an important outcome in human resource development. In this research, we tested a model examining the joint influence of social desirability (impression management, self-deception) and motives (need for power, need for approval) on trainees' self-reported knowledge gain. We conducted a study with…

  4. A wavelet based time-frequency analysis of wave packet fractional revivals

    NASA Astrophysics Data System (ADS)

    Ghosh, Suranjana; Banerji, Jagannath

    2007-06-01

    We show that the time-frequency analysis of the autocorrelation function based on its wavelet transform [1], is a better tool to resolve fractional revivals [2] of a wave packet than the usual time domain analysis. We study the above for two different systems like a Rydberg atom [3] and a diatomic molecular system [4] and show that the present method can resolve fractional revivals of higher order than what can be achieved by the time domain analysis. This advantage is crucial in reconstructing the initial state of the wave packet when its coherent structure is short-lived and decays before it is fully revived. References: [1] R. M. Rao and A. S. Bopardikar, Wavelet Transforms: Introduction to Theory and Applications (ADDISON-WESLEY, 2000). [2] I. Sh. Averbukh and N. F. Perelman, Phys. Lett. A 139, 449 (1989); R. W. Robinett, Phys. Rep. 392, 1 (2004) and references therein; J. Banerji and S. Ghosh, J. Phys. B 39, 1113 (2006). [3] Z. D. Gaeta and C. R. Stroud, Jr., Phys. Rev. A 42, 6308 (1990). [4] S. Ghosh, A. Chiruvelli, J. Banerji and P. K. Panigrahi, Phys. Rev. A 70, 053813 (2006).

  5. Radar classification of landmines by time-frequency analysis

    NASA Astrophysics Data System (ADS)

    Wong, D.; Nguyen, L.; Gaunaurd, G.

    2007-04-01

    A flying platform illuminates a land mine field with mixtures of various landmines (i.e., buried, on the surface, plastic or metallic) and some "confusers", with an ultra-wideband (UWB) radar. The polarimetric echoes returned by the mine field are mapped into an overall synthetic aperture radar (SAR) image, which is then analyzed pixel-by-pixel by modern time-frequency (t-f) techniques. The t-f analysis of any echo from any of the individual scatterers in the mine field can be performed using a number of t-f distributions, which in turn generate two-dimensional plots of each such scatterer in t-f space. These plots are richer in information than those in the original SAR image, and they offer a larger variety of clues useful for the discrimination of each type of mine from the others or from the confusers. Several t-f distributions are employed in the study, and it is found that some are better than others for the present purpose of target detection and classification. From the images obtained we can conclude that the Pseudo-Wigner-Ville and the Choi-Williams distributions provide the best discrimination results. It is also found that the larger mines such as those denoted here as of "type-1" are the easiest to identify. Using the above-mentioned distributions it follows that the distinction between actual mines and clutter objects (or "confusers") becomes clearer, particularly when the latter objects are metallic. Numerous images generated in this study confirm the above conclusions.

  6. Naval Space Surveillance Center uses of time, frequency, and phase

    NASA Technical Reports Server (NTRS)

    Hayden, Carroll C.; Knowles, Stephen H.

    1992-01-01

    The Naval Space Surveillance Center (NAVSPASUR) is an operational naval command that has the mission of determining the location of all manmade objects in space and transmitting information on objects of interest to the fleet. NAVSPASUR operates a 217 MHz radar fence that has 9 transmitting and receiving stations deployed in a line across southern Continental United States (CONUS). This surveillance fence provides unalerted detection of satellites overflying CONUS. NAVSPASUR also maintains a space catalog of all orbiting space objects. NAVSPASUR plays an important role as operational alternate to the primary national Space Surveillance Center (SSC) and Space Defence Operations Center (SPADOC). In executing these responsibilities, NAVSPASUR needs precise and/or standardized time and frequency in a number of applications. These include maintenance of the radar fence references to specification, and coordination with other commands and agencies for data receipt and dissemination. Precise time and frequency must be maintained within each site to enable proper operation of the interferometry phasing technique used. Precise time-of-day clocking must exist between sites for proper intersite coordination. Phase may be considered a derivative of time and frequency. Its control within each transmitter or receiver site is of great importance to NAVSPASUR because of the operation of the sensor as an interferometer system, with source direction angles as the primary observable. Determination of the angular position of a satellite is directly dependent on the accuracy with which the differential phase between spaced subarrays can be measured at each receiver site. Various aspects of the NAVSPASUR are discussed with respect to time, frequency, and phase.

  7. Determination of embedded layer properties using adaptive time-frequency domain analysis

    Microsoft Academic Search

    L. Wang; B. Xie; S. I. Rokhlin

    2002-01-01

    A general model for determination of the complete set of acoustical and geometrical properties of an isotropic layer embedded between isotropic or anisotropic multilayered solids is developed. These properties include density, longitudinal and shear elastic moduli, layer thickness, and loss factors, simultaneously determined from two measurements, one at normal and one at oblique incidence. The inversion model is an extension

  8. Robust underdetermined blind audio source separation of sparse signals in the time-frequency domain

    Microsoft Academic Search

    Si Mohamed Aziz Sbai; Abdeldjalil Aissa-El-Bey; Dominique Pastor

    2011-01-01

    We address the problem of blind source separation in the underdetermined and instantaneous mixture case. The proposed method is based on an algorithm developed by Aissa-El-Bey and al.. This algorithm requires a good choice of the noise threshold and does not take into account the noise contribution in the inversion process. In order to overcome these drawbacks, this paper presents

  9. Experimental measure of arm stiffness during single reaching movements with a time-frequency analysis

    PubMed Central

    Pierobon, Alberto; DiZio, Paul; Lackner, James R.

    2013-01-01

    We tested an innovative method to estimate joint stiffness and damping during multijoint unfettered arm movements. The technique employs impulsive perturbations and a time-frequency analysis to estimate the arm's mechanical properties along a reaching trajectory. Each single impulsive perturbation provides a continuous estimation on a single-reach basis, making our method ideal to investigate motor adaptation in the presence of force fields and to study the control of movement in impaired individuals with limited kinematic repeatability. In contrast with previous dynamic stiffness studies, we found that stiffness varies during movement, achieving levels higher than during static postural control. High stiffness was associated with elevated reflexive activity. We observed a decrease in stiffness and a marked reduction in long-latency reflexes around the reaching movement velocity peak. This pattern could partly explain the difference between the high stiffness reported in postural studies and the low stiffness measured in dynamic estimation studies, where perturbations are typically applied near the peak velocity point. PMID:23945781

  10. An Improved Time-Frequency Analysis Method in Interference Detection for GNSS Receivers.

    PubMed

    Sun, Kewen; Jin, Tian; Yang, Dongkai

    2015-01-01

    In this paper, an improved joint time-frequency (TF) analysis method based on a reassigned smoothed pseudo Wigner-Ville distribution (RSPWVD) has been proposed in interference detection for Global Navigation Satellite System (GNSS) receivers. In the RSPWVD, the two-dimensional low-pass filtering smoothing function is introduced to eliminate the cross-terms present in the quadratic TF distribution, and at the same time, the reassignment method is adopted to improve the TF concentration properties of the auto-terms of the signal components. This proposed interference detection method is evaluated by experiments on GPS L1 signals in the disturbing scenarios compared to the state-of-the-art interference detection approaches. The analysis results show that the proposed interference detection technique effectively overcomes the cross-terms problem and also preserves good TF localization properties, which has been proven to be effective and valid to enhance the interference detection performance of the GNSS receivers, particularly in the jamming environments. PMID:25905704

  11. An Improved Time-Frequency Analysis Method in Interference Detection for GNSS Receivers

    PubMed Central

    Sun, Kewen; Jin, Tian; Yang, Dongkai

    2015-01-01

    In this paper, an improved joint time-frequency (TF) analysis method based on a reassigned smoothed pseudo Wigner–Ville distribution (RSPWVD) has been proposed in interference detection for Global Navigation Satellite System (GNSS) receivers. In the RSPWVD, the two-dimensional low-pass filtering smoothing function is introduced to eliminate the cross-terms present in the quadratic TF distribution, and at the same time, the reassignment method is adopted to improve the TF concentration properties of the auto-terms of the signal components. This proposed interference detection method is evaluated by experiments on GPS L1 signals in the disturbing scenarios compared to the state-of-the-art interference detection approaches. The analysis results show that the proposed interference detection technique effectively overcomes the cross-terms problem and also preserves good TF localization properties, which has been proven to be effective and valid to enhance the interference detection performance of the GNSS receivers, particularly in the jamming environments. PMID:25905704

  12. Time-Frequency Variability of Kuroshio Meanders in Tokara Strait

    NASA Astrophysics Data System (ADS)

    Nakamura, H.; Yamashiro, T.; Nishina, A.; Ichikawa, H.

    2006-12-01

    The Kuroshio path in the northern Okinawa Trough, Japan, located between the continental slope and Tokara Strait, exhibits meandering motions with largest displacements in the East China Sea; these motions have dominant periods in the broad range of 30-90 days. Understanding the dynamic nature of such meanders is crucial to predicting small and large meanders of the Kuroshio path off the south coast of Japan. Previous numerical simulations suggest that the Kuroshio path meanders in the northern Okinawa Trough become nonstationary in variance because of changes in background states of the Kuroshio in the northern Okinawa Trough, but a detailed analysis based on observed data has yet to be performed. The purpose of the present study is to provide a detailed description of the time-frequency variability of Kuroshio path meanders observed in Tokara Strait. Three Kuroshio indicators were subjected to wavelet analysis for the period 1984-2004: the Kuroshio Position Index (KPI) in Tokara Strait, Kuroshio Volume Transport (KVT) in Tokara Strait, and the basal current velocity of the Kuroshio on the continental slope in the northern Okinawa Trough. The 30-90 day variance of the KPI shows a season-fixed nature, with larger amplitudes in the period December-July. The amplitude of the variance in this phenomenon is also modulated by interannual variations, with small variance recorded during 1989-1992, large variance during 1993-1998, and a return to small variance from 1999-2003. This interannual variation is positively correlated with that of the KVT. The largest variance of the KPI during February-April precedes the largest volume transport in April-May by about 1 month, suggesting that eddy vorticity flux strengthens the mean current field. Previous numerical simulations reproduce the recirculation gyre as a cyclonic eddy in the area between the continental slope and Tokara Strait; this gyre is analogous to the northern recirculation gyre associated with the eastward jet. On the basis of data from a moored current-meter situated on the continental slope, the genesis of the 30-90 day meanders within Tokara Strait is ascribed to nonlinear energy transfer from 8-25 day meanders on the continental slope.

  13. Recurrent Dominant Mutations Affecting Two Adjacent Residues in the Motor Domain of the Monomeric Kinesin KIF22 Result in Skeletal Dysplasia and Joint Laxity

    PubMed Central

    Boyden, Eric D.; Campos-Xavier, A. Belinda; Kalamajski, Sebastian; Cameron, Trevor L.; Suarez, Philippe; Tanackovich, Goranka; Andria, Generoso; Ballhausen, Diana; Briggs, Michael D.; Hartley, Claire; Cohn, Daniel H.; Davidson, H. Rosemarie; Hall, Christine; Ikegawa, Shiro; Jouk, Pierre-Simon; König, Rainer; Megarbané, André; Nishimura, Gen; Lachman, Ralph S.; Mortier, Geert; Rimoin, David L.; Rogers, R. Curtis; Rossi, Massimiliano; Sawada, Hirotake; Scott, Richard; Unger, Sheila; Valadares, Eugenia Ribeiro; Bateman, John F.; Warman, Matthew L.; Superti-Furga, Andrea; Bonafé, Luisa

    2011-01-01

    Spondyloepimetaphyseal dysplasia with joint laxity, leptodactylic type (lepto-SEMDJL, aka SEMDJL, Hall type), is an autosomal dominant skeletal disorder that, in spite of being relatively common among skeletal dysplasias, has eluded molecular elucidation so far. We used whole-exome sequencing of five unrelated individuals with lepto-SEMDJL to identify mutations in KIF22 as the cause of this skeletal condition. Missense mutations affecting one of two adjacent amino acids in the motor domain of KIF22 were present in 20 familial cases from eight families and in 12 other sporadic cases. The skeletal and connective tissue phenotype produced by these specific mutations point to functions of KIF22 beyond those previously ascribed functions involving chromosome segregation. Although we have found Kif22 to be strongly upregulated at the growth plate, the precise pathogenetic mechanisms remain to be elucidated. PMID:22152678

  14. The Soil and Water Assessment Tool (SWAT) is a public domain model jointly developed by U.S. Department of Agriculture-Agricultural Research Service and Texas AgriLife Research,

    E-print Network

    The Soil and Water Assessment Tool (SWAT) is a public domain model jointly developed by U&M University System. SWAT is a river basin-scale model to simulate the quality and quantity of surface and land use patterns. http://swatmodel.tamu.edu/conferences/2013 2013 International SWAT Conference

  15. Analysis and design of modified window shapes for S-transform to improve time-frequency localization

    NASA Astrophysics Data System (ADS)

    Ma, Jianping; Jiang, Jin

    2015-06-01

    This paper deals with window design issues for modified S-transform (MST) to improve the performance of time-frequency analysis (TFA). After analyzing the drawbacks of existing window functions, a window design technique is proposed. The technique uses a sigmoid function to control the window width in frequency domain. By proper selection of certain tuning parameters of a sigmoid function, windows with different width profiles can be obtained for multi-component signals. It is also interesting to note that the MST algorithm can be considered as a special case of a generalized method that adds a tunable shaping function to the standard window in frequency domain to meet specific frequency localization needs. The proposed design technique has been validated on a physical vibration test system using signals with different characteristics. The results have demonstrated that the proposed MST algorithm has superior time-frequency localization capabilities over standard ST, as well as other classical TFA methods. Subsequently, the proposed MST algorithm is applied to vibration monitoring of pipes in a water supply process controlled by a diaphragm pump for fault detection purposes.

  16. Estimating the local viscoelastic properties from dispersive shear waves using time-frequency ridge analysis.

    PubMed

    Giannoula, Alexia; Cobbold, Richard S C; Bezerianos, Anastasios

    2013-02-01

    Modulated low-frequency shear waves can be non-invasively generated locally within a medium, by the oscillatory acoustic radiation force resulting from the interference of two focused quasi-CW ultrasound beams of slightly different frequencies. The propagation of such shear waves within a viscoelastic medium is known to be affected by the dispersive effects of viscosity. Specifically, a low-frequency (LF) spectral component was shown to arise with increased viscosities and higher modulation frequencies and appear as a 'slow' wave at the end of the shear waveform. In this paper, the shear dispersion characteristics are studied based on the Pseudo-Wigner-Ville distribution (PWVD) in the time-frequency domain. The ridges of the PWVD are then extracted and used to calculate the frequency-dependent shear speed, by identifying the LF dispersive component both in time and frequency. Using numerical simulations, it is shown that this way of estimating the shear dispersion is more efficient and robust than the conventional phase-delay Fourier method. Thus, more accurate estimates of the local shear modulus and viscosity of the propagating medium could be achieved. The effects of noise on the proposed method are also discussed. PMID:23106858

  17. Coherent electron-phonon interaction in Si observed in time-frequency space

    NASA Astrophysics Data System (ADS)

    Hase, Muneaki; Kitajima, Masahiro; Monia Constantinescu, Anca; Petek, Hrvoje

    2004-03-01

    Si is the most fundamental component of modern electronic devices such as integrated circuits (ICs). To date, only the incoherent population relaxation process of photogenerated carriers in Si have been studied by pump-probe methods. However, the direct observation of coherent electron-phonon interaction has not yet been reported for Si. Here we report on the ultrafast coherent electron-phonon interaction and subsequent generation of a coherent phonon in Si observed with 10 fs time resolution. The Electro-optic sampling method was employed to measure anisotropic reflectivity change ? R_eo/R. The light source was 406 nm light generated by frequency doubling a Ti:sapphire oscillator. The sample used was n-Si with doping level of ˜ 1 x 10^15cm-3, whereas the photoexcited carrier density was ˜ 4 x 10^19cm-3. ? R_eo/R exhibits complicated transient response of photoexcited carriers and the oscillatory part due to the coherent LO phonon. The time domain data were converted into a time-frequency chronogram using a continuos wavelet transform, revealing an antiresonance (or a dip) at 22 fs and 15.3 THz. We attribute this dip to the coupling of the coherent LO phonon and electron-hole pair continuum via impulsive Raman scattering process, as well as by direct electron-phonon interaction, leading to the Fano interference.

  18. Non-invasive baroreflex sensitivity assessment using wavelet transfer function-based time-frequency analysis.

    PubMed

    Keissar, K; Maestri, R; Pinna, G D; La Rovere, M T; Gilad, O

    2010-07-01

    A novel approach for the estimation of baroreflex sensitivity (BRS) is introduced based on time-frequency analysis of the transfer function (TF). The TF method (TF-BRS) is a well-established non-invasive technique which assumes stationarity. This condition is difficult to meet, especially in cardiac patients. In this study, the classical TF was replaced with a wavelet transfer function (WTF) and the classical coherence was replaced with wavelet transform coherence (WTC), adding the time domain as an additional degree of freedom with dynamic error estimation. Error analysis and comparison between WTF-BRS and TF-BRS were performed using simulated signals with known transfer function and added noise. Similar comparisons were performed for ECG and blood pressure signals, in the supine position, of 19 normal subjects, 44 patients with a history of previous myocardial infarction (MI) and 45 patients with chronic heart failure. This yielded an excellent linear association (R > 0.94, p < 0.001) for time-averaged WTF-BRS, validating the new method as consistent with a known method. The additional advantage of dynamic analysis of coherence and TF estimates was illustrated in two physiological examples of supine rest and change of posture showing the evolution of BRS synchronized with its error estimations and sympathovagal balance. PMID:20585147

  19. Local spatiotemporal time-frequency peak filtering method for seismic random noise reduction

    NASA Astrophysics Data System (ADS)

    Liu, Yanping; Dang, Bo; Li, Yue; Lin, Hongbo

    2014-12-01

    To achieve a higher level of seismic random noise suppression, the Radon transform has been adopted to implement spatiotemporal time-frequency peak filtering (TFPF) in our previous studies. Those studies involved performing TFPF in full-aperture Radon domain, including linear Radon and parabolic Radon. Although the superiority of this method to the conventional TFPF has been tested through processing on synthetic seismic models and field seismic data, there are still some limitations in the method. Both full-aperture linear Radon and parabolic Radon are applicable and effective for some relatively simple situations (e.g., curve reflection events with regular geometry) but inapplicable for complicated situations such as reflection events with irregular shapes, or interlaced events with quite different slope or curvature parameters. Therefore, a localized approach to the application of the Radon transform must be applied. It would serve the filter method better by adapting the transform to the local character of the data variations. In this article, we propose an idea that adopts the local Radon transform referred to as piecewise full-aperture Radon to realize spatiotemporal TFPF, called local spatiotemporal TFPF. Through experiments on synthetic seismic models and field seismic data, this study demonstrates the advantage of our method in seismic random noise reduction and reflection event recovery for relatively complicated situations of seismic data.

  20. Time-Frequency Characterization and Receiver Waveform Design for Shallow Water

    E-print Network

    Paris-Sud XI, Université de

    Time-Frequency Characterization and Receiver Waveform Design for Shallow Water Environments Jun be considered as a time-dispersive system whose time-varying impulse response can be expressed as a superposition of time-frequency components with dispersive characteristics. In this paper, we propose

  1. Application of Quasi-Orthogonal Space-Time-Frequency Codes in MB-OFDM UWB

    E-print Network

    Lübeck, Universität zu

    Application of Quasi-Orthogonal Space-Time-Frequency Codes in MB-OFDM UWB L. C. Tran and A. Mertins performance in recently pro- posed Space-Time-Frequency Coded Multiband OFDM Ultra- Wideband (STFC MB-OFDM UWB of the emerging technologies Multiband OFDM Ultra-Wideband (MB-OFDM UWB), Multiple Input Multiple Output (MIMO

  2. TIME-FREQUENCY ANALYSIS OF FOURIER INTEGRAL ELENA CORDERO, FABIO NICOLA AND LUIGI RODINO

    E-print Network

    Ceragioli, Francesca

    TIME-FREQUENCY ANALYSIS OF FOURIER INTEGRAL OPERATORS ELENA CORDERO, FABIO NICOLA AND LUIGI RODINO Abstract. We use time-frequency methods for the study of Fourier Integral operators (FIOs). In this paper. Indeed, similarly to the case of shearlets and curvelets frames, the matrix representation of a Fourier

  3. TIME-FREQUENCY-MODULATION REPRESENTATION OF STOCHASTIC SIGNALS Philip J.B. Jackson

    E-print Network

    Jackson, Philip JB

    TIME-FREQUENCY-MODULATION REPRESENTATION OF STOCHASTIC SIGNALS Philip J.B. Jackson Centre discrete signals with time- varying parameters, and extended to a 3D time-frequency- modulation modulation (AM) systems, the carrier signal is a sinusoid of much higher frequency than those

  4. Data driven time-frequency analysis based on empirical mode decomposition and adaptive optimal kernel

    Microsoft Academic Search

    Rongjun Lu; Bin Zhou; Wei Gao

    2010-01-01

    Hilbert-Huang transfer (HHT) and adaptive optimal kernel (AOK) are data driven time frequency analysis algorithm. But HHT is limited by Bedrosian theorem and AOK normally behaviors well only for single component signal. To resolve above problems, empirical mode decomposition (EMD), kernel part of HHT, and AOK are combined together to create a new time-frequency representation (TFR). So by this novel

  5. Time-frequency scaling transformation of the phonocardiogram based of the matching pursuit method

    Microsoft Academic Search

    Xuan Zhang; Louis-Gilles Durand; Lotfi Senhadji; Howard C. Lee; Jean-Louis Coatrieux

    1998-01-01

    A time-frequency scaling transformation based on the matching pursuit (MP) method is developed for the phonocardiogram (PCG). The MP method decomposes a signal into a series of time-frequency atoms by using an iterative process. The modification of the time scale of the PCG can be performed without perceptible change in its spectral characteristics. It is also possible to modify the

  6. Application of time–frequency analysis to somatosensory evoked potential for intraoperative spinal cord monitoring

    PubMed Central

    Hu, Y; Luk, K; Lu, W; Leong, J

    2003-01-01

    Objective: To investigate the improvement in the reliability of intraoperative spinal cord monitoring by applying time–frequency analysis to somatosensory evoked potentials (SEP). Methods: 34 patients undergoing scoliosis surgery were studied. SEP were recorded during different stages of scoliosis surgery. Averaged SEP signals were analysed intraoperatively by short time Fourier transform (STFT). The time–frequency characteristics of SEP were observed during surgery. The main peak in the time–frequency interpretation of SEP was measured in peak time, peak frequency, and peak power. The changes in these variables were compared with the changes in latency and amplitude during different surgical stages. Results: During different surgical stages, changes in peak times and peak powers were found to correlate with the changes in latency and amplitude, respectively. Peak time showed more variability than latency (p < 0.01), while peak power showed less variability than amplitude (p < 0.01). The peak frequency of SEP appeared to be unchanged during surgery. SEP signals were found to have specific time–frequency characteristics, with the time–frequency distribution of the signals being located in a particular time–frequency space. Conclusions: Time–frequency analysis of SEP waveforms reveals stable and easily identifiable characteristics. Peak power is recommended as a more reliable monitoring parameter than amplitude, while peak time monitoring was not superior to latency measurement. Applying time–frequency analysis to SEP can improve the reliability of intraoperative spinal cord monitoring. PMID:12486272

  7. Detection of epileptiform activity in EEG signals based on time-frequency and non-linear analysis.

    PubMed

    Gajic, Dragoljub; Djurovic, Zeljko; Gligorijevic, Jovan; Di Gennaro, Stefano; Savic-Gajic, Ivana

    2015-01-01

    We present a new technique for detection of epileptiform activity in EEG signals. After preprocessing of EEG signals we extract representative features in time, frequency and time-frequency domain as well as using non-linear analysis. The features are extracted in a few frequency sub-bands of clinical interest since these sub-bands showed much better discriminatory characteristics compared with the whole frequency band. Then we optimally reduce the dimension of feature space to two using scatter matrices. A decision about the presence of epileptiform activity in EEG signals is made by quadratic classifiers designed in the reduced two-dimensional feature space. The accuracy of the technique was tested on three sets of electroencephalographic (EEG) signals recorded at the University Hospital Bonn: surface EEG signals from healthy volunteers, intracranial EEG signals from the epilepsy patients during the seizure free interval from within the seizure focus and intracranial EEG signals of epileptic seizures also from within the seizure focus. An overall detection accuracy of 98.7% was achieved. PMID:25852534

  8. Estimation of respiratory rate from ECG, photoplethysmogram, and piezoelectric pulse transducer signals: a comparative study of time-frequency methods.

    PubMed

    Dash, Shishir; Shelley, Kirk H; Silverman, David G; Chon, Ki H

    2010-05-01

    We compare the performance of two different time-frequency-based breathing rate (BR) detection algorithms when used on three different physiological signals: the ECG, the photoplethysmogram (PPG), and the piezoelectric pulse transducer (PZO) signal. Studies carried out over the past have shown the existence of amplitude and/or FMs due to respiration in physiological signals, such as those mentioned. In a recent study, we analyzed the PPG signal and detected the FM and amplitude modulation effect that controlled breathing had on it, and inferred the rate of respiration using the time-frequency spectrum (TFS) (via a wavelet (WT) or complex demodulation (CDM) approach). We showed that such TFS BR detection methods were very accurate and consistently outperformed the exclusively time-domain autoregressive modeling (AR) method, especially in the real-time (data length of 1 min) case. We now explore the possibility of using these methods on the ECG and the finger PZO signal, of which only the former has been previously used with some success to derive BR. Testing performed on 15 healthy human subjects for a range of BR and two body positions showed that though the PPG signal gave the most consistently high performance, the ECG and PZO also proved to be reasonably accurate over longer time segments. Furthermore, the CDM approach was on average either better than or comparable to the WT method in terms of both accuracy and repeatability of the detection. PMID:20659821

  9. Analysis of transient signatures of arc faults in power distribution systems via time-frequency analysis

    NASA Astrophysics Data System (ADS)

    Crapse, Philip; Wang, Jing-Jiang; Shin, Yong-June; Dougal, Roger

    2006-08-01

    This paper draws on an innovative, signal processing-based method that jointly analyzes the time and frequency domains and uses that information to characterize and distinguish the deadly arc faults from the normal operational faults. This paper introduces a variety of new power quality assessment tools developed with the purpose of both detecting an arc fault faster than has yet been done and distinguishing the arc fault from other normal load operations via time-localized spectral characterization. Based on the time and frequency localization of the arc faults, the time varying impedances of the arc fault are modeled in terms of harmonic sources. The accomplishment of these objectives would lead to new, advanced smart arc fault circuit breakers and the modeling & simulation of arc fault phenomena.

  10. Advanced Time-Frequency Mutual Information Measures for Condition Based Maintenance of Helicopter Drive Trains

    E-print Network

    Almor, Amit

    Advanced Time-Frequency Mutual Information Measures for Condition Based Maintenance of Helicopter · Standard time based maintenance practices for Apache AH-64 helicopters can lead to failure in critical

  11. Adaptive Time-Frequency Decompositions with Matching Pursuits Geo rey Davis, Stephane Mallat, and Zhifeng Zhang

    E-print Network

    Davis, Geoff

    the coherent structures of a signal and describe an application to pattern extraction from noisy signals. 1 in section 6. The signal is decomposed into a selected set of time-frequency atoms, the dilations

  12. Packet acquisition for time-frequency hopped asynchronous random multiple access

    E-print Network

    Nguyen, Hoang

    Packet acquisition for a time-frequency hopped asynchronous random multiple access (RMA) system is investigated. A novel analytical approach to performance evaluation is provided, which enables the waveform designer to ...

  13. Joint swelling

    MedlinePLUS

    Swelling of a joint ... Joint swelling may occur along with joint pain . The swelling may cause the joint to appear larger or abnormally shaped. Joint swelling can cause pain or stiffness. After an ...

  14. Optimal detection using bilinear time-frequency and time-scale representations

    Microsoft Academic Search

    A. M. Sayeed; D. L. Jones

    1995-01-01

    Bilinear time-frequency representations (TFRs) and time-scale representations (TSRs) are potentially very useful for detecting a nonstationary signal in the presence of nonstationary noise or interference. As quadratic signal representations, they are promising for situations in which the optimal detector is a quadratic function of the observations. All existing time-frequency formulations of quadratic detection either implement classical optimal detectors equivalently in

  15. Block Diagonal Differential Space–Time–Frequency Codes for Four Transmit Antennas

    Microsoft Academic Search

    Yi Zhang; Can Zhang; Guo Fang Tu

    2009-01-01

    For Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system with four transmit antennas,\\u000a this paper presents a novel block diagonal differential space–time–frequency (DSTF) coded scheme with full diversity and rate\\u000a one. It overcomes the rate loss of the traditional differential orthogonal space–time–frequency coded scheme for four transmit\\u000a antennas. The coding and decoding method are described in detail. After analyzing

  16. Inhibition of synovitis and joint destruction by a new single domain antibody specific for cyclophilin A in two different mouse models of rheumatoid arthritis

    PubMed Central

    2013-01-01

    Introduction Cyclophilin A (CypA) is implicated in rheumatoid arthritis (RA) pathogenesis. We studied whether a novel anti-CypA single domain antibody (sdAb) treatment would modulate the severity of the disease in two different animal models of RA. Methods A novel sdAb, named sdAbA1, was screened from an immunized camel sdAb library and found to have a high binding affinity (KD?=?6.9?×?10-9 M) for CypA. The SCID-HuRAg model and the collagen-induced arthritis (CIA) in mice were used to evaluate the effects of sdAbA1 treatment on inflammation and joint destruction. For in vitro analysis, monocytes/macrophages were purified from synovial fluid and peripheral blood of patients with RA and were tested for the effect of anti-CypA sdAb on metalloproteinase (MMP) production. Human monocyte cell line THP-1 cells were selected and western blot analyses were performed to examine the potential signaling pathways. Results In the CIA model of RA, the sdAbA1 treatment resulted in a significant decrease in clinical symptoms as well as of joint damage (P <0.05). In the SCID-HuRAg model, treatment with anti-CypA antibody sdAbA1 significantly reduced cartilage erosion, inflammatory cell numbers and MMP-9 production in the implanted tissues (P <0.05). It also significantly reduced the levels of human inflammatory cytokines IL-6 and IL-8 in mouse serum (P <0.05). No toxic effects were observed in the two animal models. In vitro results showed that sdAbA1 could counteract CypA-dependent MMP-9 secretion and IL-8 production by interfering with the ERK-NF-?B pathway. Conclusions Blockade of CypA significantly inhibited synovitis and cartilage/bone erosion in the two tested animal models of RA. Our findings provide evidence that sdAbA1 may be a potential therapeutic agent for RA. PMID:24314202

  17. Time-frequency manifold for nonlinear feature extraction in machinery fault diagnosis

    NASA Astrophysics Data System (ADS)

    He, Qingbo

    2013-02-01

    Time-frequency feature is beneficial to representation of non-stationary signals for effective machinery fault diagnosis. The time-frequency distribution (TFD) is a major tool to reveal the synthetic time-frequency pattern. However, the TFD will also face noise corruption and dimensionality reduction issues in engineering applications. This paper proposes a novel nonlinear time-frequency feature based on a time-frequency manifold (TFM) technique. The new TFM feature is generated by mainly addressing manifold learning on the TFDs in a reconstructed phase space. It combines the non-stationary information and the nonlinear information of analyzed signals, and hence exhibits valuable properties. Specifically, the new feature is a quantitative low-dimensional representation, and reveals the intrinsic time-frequency pattern related to machinery health, which can effectively overcome the effects of noise and condition variance issues in sampling signals. The effectiveness and the merits of the proposed TFM feature are confirmed by case study on gear wear diagnosis, bearing defect identification and defect severity evaluation. Results show the value and potential of the new feature in machinery fault pattern representation and classification.

  18. Development of transient power quality indices based on time-frequency distribution

    NASA Astrophysics Data System (ADS)

    Shin, Yong-June; Crapse, Philip

    2005-08-01

    For an assessment of the power quality in power distribution systems, classical Fourier series-based power quality indices are normally employed. The classical Fourier series-based power quality indices assume the periodicity of the disturbance so that the applications are limited to the harmonics. Hence, it is necessary for us to redefine power quality indices for the "transient" disturbances. In this paper, development of time-frequency based power quality indices are discussed for an assessment of transient power quality. The time and frequency localized information of the transient disturbance signals will be utilized for a new definition of the transient power quality indices. As an example of time-frequency based power quality indices, new definition of transient telephone interference factor has been carefully derived and verified in comparison with traditional telephone interference factor. Time-frequency based power quality indices allow one to quantify the effects of transient disturbances by time and frequency localized information.

  19. Hypermobile joints

    MedlinePLUS

    ... hypermobile joints have an increased risk for joint dislocation and other problems. Extra care may be needed ... the joint? Is there any history of joint dislocation, difficulty walking, or difficulty using the arms? Further ...

  20. Differential Space-Time-Frequency Codes for MB-OFDM UWB with Dual Carrier Modulation

    E-print Network

    Lübeck, Universität zu

    - band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent division multiplexing ultra- wideband (MB-OFDM UWB) [1], multiple-input multiple- output (MIMO) and spaceDifferential Space-Time-Frequency Codes for MB-OFDM UWB with Dual Carrier Modulation L. C. Tran

  1. A Comparative Study of Time-Frequency Representations for Fault Detection in Wind Turbine

    E-print Network

    Paris-Sud XI, Université de

    A Comparative Study of Time-Frequency Representations for Fault Detection in Wind Turbine El of wind energy, minimization and prediction of maintenance operations in wind turbine is of key importance and the easiness of interpretation. Index Terms--Wind turbine, fault detection, broken-rotor bars, signal

  2. Underwater shell type target classification using time-frequency features of acoustic backscatter signals

    Microsoft Academic Search

    Saman S. Abeysekera

    1998-01-01

    An efficient technique for the computation of the form function of a thin elastic spherical shell target is proposed. Using the form function it is shown how various target identification parameters could be obtained. These target identification parameters are obtained from the time-frequency distribution of the target's acoustic backscatter signal

  3. The Continuous Wavelet Transform and Variable Resolution Time-Frequency Analysis

    Microsoft Academic Search

    A.-H. NAJMI; J. SADOWSKY; Amir-Homayoon Najmi

    1988-01-01

    W avelet transforms have recently emerged as a mathematical tool for multiresolution decomposition of signals. They have potential applications in many areas of signal processing that require variable time-frequency localization. The continuous wavelet transform is presented here, and its frequency resolution is derived analytically and shown to depend exclusively on one parameter that should be carefully selected in constructing a

  4. Phasor-Banks: Customizable Filter Banks for Robust Dynamic Time-Frequency Analysis

    E-print Network

    Stankoviæ, Aleksandar

    Phasor-Banks: Customizable Filter Banks for Robust Dynamic Time-Frequency Analysis Hanoch Lev, USA {levari,astankov}@ece.neu.edu Abstract-- The paper extends the concept of dynamic phasors to allow customizations that could benefit a num- ber of diverse applications. Connections between dynamic phasors and non

  5. Dynamic Mixtures of Splines: a Model for Saliency Grouping in the Time Frequency

    E-print Network

    Hastie, Trevor

    fitting algorithm. Keywords: curve fitting, EM algorithm, Kullback­Leibler distance, saliency extraction with a filter­bank of overlapping quasi­ constant filters (i.e. filters obtained by successive dilations in the time­frequency plane and very difficult to extract. The synchrosqueezed representation is a nonlinear

  6. Mechanical signature analysis using time-frequency signal processing: application to internal combustion engine knock detection

    Microsoft Academic Search

    B. Samimy; G. Rizzoni

    1996-01-01

    Signature analysis consists of the extraction of information from measured signal patterns. The work presented in this paper illustrates the use of time-frequency (TF) analysis methods for the purpose of mechanical signature analysis. Mechanical signature analysis is a mature and developed field; however, TF analysis methods are relatively new to the field of mechanical signal processing, having mostly been developed

  7. MONAURAL SOURCE SEPARATION FROM MUSICAL MIXTURES BASED ON TIME-FREQUENCY TIMBRE MODELS

    E-print Network

    Wichmann, Felix

    MONAURAL SOURCE SEPARATION FROM MUSICAL MIXTURES BASED ON TIME-FREQUENCY TIMBRE MODELS Juan Jos on generic source mod- els. To further improve separation, statistical models of the sources can be trained,sikora}@nue.tu-berlin.de ABSTRACT We present a system for source separation from monau- ral musical mixtures based on sinusoidal

  8. Adaptive noise cancelling and time-frequency techniques for rail surface defect detection

    NASA Astrophysics Data System (ADS)

    Liang, B.; Iwnicki, S.; Ball, A.; Young, A. E.

    2015-03-01

    Adaptive noise cancelling (ANC) is a technique which is very effective to remove additive noises from the contaminated signals. It has been widely used in the fields of telecommunication, radar and sonar signal processing. However it was seldom used for the surveillance and diagnosis of mechanical systems before late of 1990s. As a promising technique it has gradually been exploited for the purpose of condition monitoring and fault diagnosis. Time-frequency analysis is another useful tool for condition monitoring and fault diagnosis purpose as time-frequency analysis can keep both time and frequency information simultaneously. This paper presents an ANC and time-frequency application for railway wheel flat and rail surface defect detection. The experimental results from a scaled roller test rig show that this approach can significantly reduce unwanted interferences and extract the weak signals from strong background noises. The combination of ANC and time-frequency analysis may provide us one of useful tools for condition monitoring and fault diagnosis of railway vehicles.

  9. Damage Classification Structural Health Monitoring in Bolted Structures Using Time-frequency Techniques

    Microsoft Academic Search

    Debejyo Chakraborty; Narayan Kovvali; Jun Wei; Antonia Papandreou-Suppappola; Douglas Cochran; Aditi Chattopadhyay

    2009-01-01

    The analysis, detection, and classification of damage in complex bolted structures is an important component of structural health monitoring. In this article, an advanced signal processing and classification method is introduced based on time-frequency techniques. The time-varying signals collected from sensors are decomposed into linear combinations of highly localized Gaussian functions using the matching pursuit decomposition algorithm. These functions are

  10. Damage mechanisms identification of polymer based composite materials: time-frequency investigation of

    E-print Network

    Paris-Sud XI, Université de

    Damage mechanisms identification of polymer based composite materials: time-frequency investigation by means of AE in polymer composites prompted the possibility of correlating a specific damage mechanism to describe the damage behavior as a first step for in situ detection of structural damages in polymer based

  11. Damage detection in composite structures using Lamb wave analysis and time-frequency approach

    Microsoft Academic Search

    Yingtao Liu; Masoud Yekani Fard; Seung B. Kim; Aditi Chattopadhyay; Derek Doyle

    2011-01-01

    A methodology based on Lamb wave analysis and time-frequency signal processing has been developed for damage detection and structural health monitoring of composite structures. Because the Lamb wave signals are complex in nature, robust signal processing techniques are required to extract damage features. In this paper, Lamb wave mode conversion is used to detect the damage in composite structures. Matching

  12. Time–frequency analysis of multiple resonances in combustion engine signals

    Microsoft Academic Search

    LJubiša Stankovi?; Johann F Böhme

    1999-01-01

    This paper presents time–frequency analysis of multiple resonances in combustion chamber pressure signals and corresponding structure-born sound signals of the cylinder block of a combustion engine considering only one combustion cycle. Since the Wigner distribution proved itself as a good tool for these kinds of signals, the requirement which we imposed here was to produce a sum of the Wigner

  13. Digital ASIC Architectures : Realtime Time-Frequency Analysis and Radiation Hardening

    E-print Network

    Baudoin, Geneviève

    Digital ASIC Architectures : Realtime Time-Frequency Analysis and Radiation Hardening Lead: L needs of TFR analysis lead to the design of an application specific integrated circuit (ASIC on our cascadable prototype ASIC, manufactured in ST 130 process. This work was done while L. Noury

  14. Qualitative Analysis of the Time-Frequency Signature Induced by a Reflected L-Band Signal from Time Evolving Sea Surfaces

    E-print Network

    Coatanhay, Arnaud

    2013-01-01

    Passive remote sensing techniques have become more and more popular for detection and characterization purposes. The advantage of using the Global Navigation Satellite Systems (GNSS) are the well known signals emitted and the availability in most areas on Earth. In the present paper, L-Band signals (including GNSS signals) are considered for oceanographic purposes. The main interest in this contribution is the analysis of the signal reflected by an evolving sea surface using time-frequency transforms. The features which occur in this domain are examined in relation to the physical phenomena: interaction of the electromagnetic waves with the moving sea surface.

  15. Inverse synthetic aperture radar processing using parametric time-frequency estimators Phase I

    SciTech Connect

    Candy, J.V., LLNL

    1997-12-31

    This report summarizes the work performed for the Office of the Chief of Naval Research (ONR) during the period of 1 September 1997 through 31 December 1997. The primary objective of this research was aimed at developing an alternative time-frequency approach which is recursive-in-time to be applied to the Inverse Synthethic Aperture Radar (ISAR) imaging problem discussed subsequently. Our short term (Phase I) goals were to: 1. Develop an ISAR stepped-frequency waveform (SFWF) radar simulator based on a point scatterer vehicular target model incorporating both translational and rotational motion; 2. Develop a parametric, recursive-in-time approach to the ISAR target imaging problem; 3. Apply the standard time-frequency short-term Fourier transform (STFT) estimator, initially to a synthesized data set; and 4. Initiate the development of the recursive algorithm. We have achieved all of these goals during the Phase I of the project and plan to complete the overall development, application and comparison of the parametric approach to other time-frequency estimators (STFT, etc.) on our synthesized vehicular data sets during the next phase of funding. It should also be noted that we developed a batch minimum variance translational motion compensation (TMC) algorithm to estimate the radial components of target motion (see Section IV). This algorithm is easily extended to recursive solution and will probably become part of the overall recursive processing approach to solve the ISAR imaging problem. Our goals for the continued effort are to: 1. Develop and extend a complex, recursive-in-time, time- frequency parameter estimator based on the recursive prediction error method (RPEM) using the underlying Gauss- Newton algorithms. 2. Apply the complex RPEM algorithm to synthesized ISAR data using the above simulator. 3. Compare the performance of the proposed algorithm to standard time-frequency estimators applied to the same data sets.

  16. Quadratic Time-Frequency Analysis of Hydroacoustic Signals as Applied to Acoustic Emissions of Large Whales

    NASA Astrophysics Data System (ADS)

    Le Bras, Ronan; Victor, Sucic; Damir, Malnar; Götz, Bokelmann

    2014-05-01

    In order to enrich the set of attributes in setting up a large database of whale signals, as envisioned in the Baleakanta project, we investigate methods of time-frequency analysis. The purpose of establishing the database is to increase and refine knowledge of the emitted signal and of its propagation characteristics, leading to a better understanding of the animal migrations in a non-invasive manner and to characterize acoustic propagation in oceanic media. The higher resolution for signal extraction and a better separation from other signals and noise will be used for various purposes, including improved signal detection and individual animal identification. The quadratic class of time-frequency distributions (TFDs) is the most popular set of time-frequency tools for analysis and processing of non-stationary signals. Two best known and most studied members of this class are the spectrogram and the Wigner-Ville distribution. However, to be used efficiently, i.e. to have highly concentrated signal components while significantly suppressing interference and noise simultaneously, TFDs need to be optimized first. The optimization method used in this paper is based on the Cross-Wigner-Ville distribution, and unlike similar approaches it does not require prior information on the analysed signal. The method is applied to whale signals, which, just like the majority of other real-life signals, can generally be classified as multicomponent non-stationary signals, and hence time-frequency techniques are a natural choice for their representation, analysis, and processing. We present processed data from a set containing hundreds of individual calls. The TFD optimization method results into a high resolution time-frequency representation of the signals. It allows for a simple extraction of signal components from the TFD's dominant ridges. The local peaks of those ridges can then be used for the signal components instantaneous frequency estimation, which in turn can be used as one of the features in any subsequent classification of the whale signals.

  17. 20 CFR 1002.104 - Is the employee required to accommodate his or her employer's needs as to the timing, frequency...

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...concerns regarding the timing, frequency, or duration of uniformed...believes that the timing, frequency or duration of the service...concerns over the timing, frequency, or duration of the employee's...attention of the appropriate military authority. Regulations...

  18. 20 CFR 1002.104 - Is the employee required to accommodate his or her employer's needs as to the timing, frequency...

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...concerns regarding the timing, frequency, or duration of uniformed...believes that the timing, frequency or duration of the service...concerns over the timing, frequency, or duration of the employee's...attention of the appropriate military authority. Regulations...

  19. 20 CFR 1002.104 - Is the employee required to accommodate his or her employer's needs as to the timing, frequency...

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...concerns regarding the timing, frequency, or duration of uniformed...believes that the timing, frequency or duration of the service...concerns over the timing, frequency, or duration of the employee's...attention of the appropriate military authority. Regulations...

  20. 20 CFR 1002.104 - Is the employee required to accommodate his or her employer's needs as to the timing, frequency...

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...concerns regarding the timing, frequency, or duration of uniformed...believes that the timing, frequency or duration of the service...concerns over the timing, frequency, or duration of the employee's...attention of the appropriate military authority. Regulations...

  1. 20 CFR 1002.104 - Is the employee required to accommodate his or her employer's needs as to the timing, frequency...

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...concerns regarding the timing, frequency, or duration of uniformed...believes that the timing, frequency or duration of the service...concerns over the timing, frequency, or duration of the employee's...attention of the appropriate military authority. Regulations...

  2. Linear vs. bilinear time-frequency methods for interference mitigation in direct sequence spread spectrum communication systems

    Microsoft Academic Search

    D. Scott Roberts; Moeness G. Amin

    1995-01-01

    Time frequency signal representations have been examined for interference mitigation in spread spectrum (SS) communication systems. We implement a direct sequence spread spectrum (DS-SS) system with additive jamming and utilize two distinct time-frequency (t-f) methods to mitigate the interference, namely the shift-covariant class of time frequency distributions (TFD) and the Gabor (1946) transform. The TFD is a bilinear transform and

  3. Ecological prediction with nonlinear multivariate time-frequency functional data models

    USGS Publications Warehouse

    Yang, Wen-Hsi; Wikle, Christopher K.; Holan, Scott H.; Wildhaber, Mark L.

    2013-01-01

    Time-frequency analysis has become a fundamental component of many scientific inquiries. Due to improvements in technology, the amount of high-frequency signals that are collected for ecological and other scientific processes is increasing at a dramatic rate. In order to facilitate the use of these data in ecological prediction, we introduce a class of nonlinear multivariate time-frequency functional models that can identify important features of each signal as well as the interaction of signals corresponding to the response variable of interest. Our methodology is of independent interest and utilizes stochastic search variable selection to improve model selection and performs model averaging to enhance prediction. We illustrate the effectiveness of our approach through simulation and by application to predicting spawning success of shovelnose sturgeon in the Lower Missouri River.

  4. Ion collision crosssection measurements in quadrupole ion traps using a time-frequency analysis method.

    PubMed

    He, Muyi; Guo, Dan; Chen, Yu; Xiong, Xingchuang; Fang, Xiang; Xu, Wei

    2014-12-01

    In this study, a method for measuring ion collision crosssections (CCSs) was proposed through time-frequency analysis of ion trajectories in quadrupole ion traps. A linear ion trap with added high-order electric fields was designed and simulated. With the presence of high-order electric fields and ion-neutral collisions, ion secular motion frequency within the quadrupole ion trap will be a function of ion motion amplitude, thus a function of time and ion CCS. A direct relationship was then established between ion CCS and ion motion frequency with respect to time, which could be obtained through time-frequency analysis of ion trajectories (or ion motion induced image currents). To confirm the proposed theory, realistic ion trajectory simulations were performed, where the CCSs of bradykinin, angiotensin I and II, and ubiquitin ions were calculated from simulated ion trajectories. As an example, differentiation of isomeric ubiquitin ions was also demonstrated in the simulations. PMID:25319271

  5. Lifetime of Surface Features and Stellar Rotation: A Wavelet Time-Frequency Approach

    E-print Network

    Willie Soon; Peter Frick; Sallie Baliunas

    1998-11-07

    We explore subtle variations in disk-integrated measurements spanning $\\lsim$ 18 years of stellar surface magnetism by using a newly developed time-frequency gapped wavelet algorithm. We present results based on analysis of the Mount Wilson Ca II H and K emission fluxes in four, magnetically-active stars (HD 1835 [G2V], 82885 [G8IV-V], 149661 [K0V] and 190007 [K4V]) and sensitivity tests using artificial data. When the wavelet basis is appropriately modified (i.e., when the time-frequency resolution is optimized), the results are consistent with the existence of spatially localized and long-lived Ca II features (assumed here as activity regions that tend to recur in narrowly-confined latitude bands), especially in HD 1835 and 82885. This interpretation is based on the observed persistence of relatively localized Ca II wavelet power at a narrow range of rotational time scales, enduring as long as $\\gsim$ 10 years.

  6. Robustness of time frequency distribution based features for automated neonatal EEG seizure detection.

    PubMed

    Nagaraj, S B; Stevenson, N J; Marnane, W P; Boylan, G B; Lightbody, G

    2014-01-01

    In this paper we examined the robustness of a feature-set based on time-frequency distributions (TFDs) for neonatal EEG seizure detection. This feature-set was originally proposed in literature for neonatal seizure detection using a support vector machine (SVM). We tested the performance of this feature-set with a smoothed Wigner-Ville distribution and modified B distribution as the underlying TFDs. The seizure detection system using time-frequency signal and image processing features from the TFD of the EEG signal using modified B distribution was able to achieve a median receiver operator characteristic area of 0.96 (IQR 0.91-0.98) tested on a large clinical dataset of 826 h of EEG data from 18 full-term newborns with 1389 seizures. The mean AUC was 0.93. PMID:25570580

  7. Considering the influence of artificial environmental noise to study cough time-frequency features

    NASA Astrophysics Data System (ADS)

    Van Hirtum, A.; Berckmans, D.

    2003-09-01

    In general the study of the cough mechanism and sound in both animal and human is performed by eliciting coughing in a reproducible way by nebulization of an irritating substance. Due to ventilation the controlled evaporation-protocol causes artificial noises from a mechanical origin. The resulting environmental low-frequency noises complicate cough time-frequency features. In order to optimize the study of the cough-sound the research described in this paper attempts on the one hand to characterize and model the environmental noises and on the other hand to evaluate the influence of the noise on the time-frequency representation for the intended cough sounds by comparing different de-noising approaches. Free field acoustic sound is continuously registered during 30 min citric acid cough-challenges on individual Belgian Landrace piglets and during respiratory infection experiments, with a duration of about 10 days, where room-ventilation was present.

  8. Enhancing the capabilities of LIGO time-frequency plane searches through clustering

    Microsoft Academic Search

    Rubab Khan; Shourov Chatterji

    2009-01-01

    One class of gravitational wave signals LIGO is searching for consists of short duration bursts of unknown waveforms. Potential sources include core collapse supernovae, gamma ray burst progenitors and mergers of binary black holes or neutron stars. We present a density-based clustering algorithm to improve the performance of time-frequency searches for such gravitational-wave bursts when they are extended in time

  9. Novel cooperative communication schemes for Space-Time-Frequency Coded MB-OFDM UWB

    Microsoft Academic Search

    Le Chung Tran; A. Mertins; X. Huang; Eryk Dutkiewicz

    2009-01-01

    Cooperative communication has been intensively considered for general wireless and sensor networks. However, it has been almost untouched in space-time-frequency coded multi-band OFDM ultra-wideband (STFC MB-OFDM UWB) systems. This paper thus proposes two cross-layer designs for cooperative communication, namely simple cooperative communication scheme (SCCS) and advanced cooperative communication scheme (ACCS), in slow fading scenarios. In the former, nodes always cooperate

  10. Non-invasive baroreflex sensitivity assessment using wavelet transfer function-based time-frequency analysis

    Microsoft Academic Search

    K. Keissar; R. Maestri; G. D. Pinna; M. T. La Rovere; O. Gilad

    2010-01-01

    A novel approach for the estimation of baroreflex sensitivity (BRS) is introduced based on time-frequency analysis of the transfer function (TF). The TF method (TF-BRS) is a well-established non-invasive technique which assumes stationarity. This condition is difficult to meet, especially in cardiac patients. In this study, the classical TF was replaced with a wavelet transfer function (WTF) and the classical

  11. Source localization of non-stationary acoustic data using time-frequency analysis

    Microsoft Academic Search

    Jack Stoughton; William Edmonson

    2005-01-01

    An improvement in temporal locality of the generalized cross-correlation (GCC) for angle of arrival (AOA) estimation can be achieved by employing 2-D cross-correlation of infrasonic sensor data transformed to its time-frequency (TF) representation. Intermediate to the AOA evaluation is the time delay between pairs of sensors. The signal class of interest includes far field sources which are partially coherent across

  12. Space-Time-Frequency Code implementation in MB-OFDM UWB communications: Design criteria and performance

    Microsoft Academic Search

    Le Chung Tran; Alfred Mertins

    2009-01-01

    This paper proposes a general framework of space-time-frequency codes (STFCs) for multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wide band (UWB) communications systems. A great similarity between the STFC MB-OFDM UWB systems and conventional wireless complex orthogonal space-time block code (CO STBC) multiple-input multiple-output (MIMO) systems is discovered. This allows us to quantify the pairwise error probability (PEP) of the proposed

  13. Using time-frequency analysis to determine time-resolved detonation velocity with microwave interferometry.

    PubMed

    Kittell, David E; Mares, Jesus O; Son, Steven F

    2015-04-01

    Two time-frequency analysis methods based on the short-time Fourier transform (STFT) and continuous wavelet transform (CWT) were used to determine time-resolved detonation velocities with microwave interferometry (MI). The results were directly compared to well-established analysis techniques consisting of a peak-picking routine as well as a phase unwrapping method (i.e., quadrature analysis). The comparison is conducted on experimental data consisting of transient detonation phenomena observed in triaminotrinitrobenzene and ammonium nitrate-urea explosives, representing high and low quality MI signals, respectively. Time-frequency analysis proved much more capable of extracting useful and highly resolved velocity information from low quality signals than the phase unwrapping and peak-picking methods. Additionally, control of the time-frequency methods is mainly constrained to a single parameter which allows for a highly unbiased analysis method to extract velocity information. In contrast, the phase unwrapping technique introduces user based variability while the peak-picking technique does not achieve a highly resolved velocity result. Both STFT and CWT methods are proposed as improved additions to the analysis methods applied to MI detonation experiments, and may be useful in similar applications. PMID:25933878

  14. Continuous-Time, Frequency Translating, Bandpass Delta-Sigma Modulator Anurag Pulincherry, Mike Hufford*, Eric Naviasky*, Un-ku Moon

    E-print Network

    Moon, Un-Ku

    Continuous-Time, Frequency Translating, Bandpass Delta-Sigma Modulator Anurag Pulincherry, Mike of frequency-translating, bandpass delta-sigma modulator in continuous-time. The system level design of the continuous-time, frequency translating band- pass delta-sigma modulator is presented. The DAC jit- ter

  15. Long-term fatigue analysis of multi-planar tubular joints for jacket-type offshore wind turbine in time domain

    Microsoft Academic Search

    Wenbin Dong; Torgeir Moan; Zhen Gao

    2011-01-01

    Long-term fatigue analysis of welded multi-planar tubular joints for a fixed jacket offshore wind turbine designed for a North Sea site in a water depth of 70 m is performed. The dynamic response of the jacket support structure due to wind and wave loads is calculated by using a decoupled procedure with good accuracy (Gao et al., 2010). Hot-spot stresses

  16. Time-frequency analysis of the event-related potentials associated with the Stroop test.

    PubMed

    Ergen, Mehmet; Saban, Sara; Kirmizi-Alsan, Elif; Uslu, Atilla; Keskin-Ergen, Yasemin; Demiralp, Tamer

    2014-12-01

    Multiple executive processes are suggested to be engaged at Stroop test, and time-frequency analysis is acknowledged to improve the informative utility of EEG in cognitive brain research. We aimed to investigate event-related oscillations associated with the Stroop test. EEG data was collected from 23 healthy volunteers while they performed a computer version of Stroop test. Both evoked (phase-locked) and total (phase-locked+non-phase-locked) oscillatory responses in the EEG were analyzed by wavelet transform. Data from the congruent (color-word matching) and incongruent stimuli (color-word non-matching) conditions are compared. In the incongruent condition, N450 wave was more negative and amplitude of the late slow wave was more positive. In the time-frequency plane, the fronto-central total theta amplitude (300-700 ms) was larger in the incongruent condition. The evoked delta (250-600 ms) was larger in the congruent condition particularly over parieto-occipital regions. The larger frontal theta response in the incongruent condition was associated with the detection of interference and inhibition of the response to task-irrelevant features, while the larger evoked delta in the congruent condition was suggestive of the easier decision process owing to congruency between the physical attribute and the verbal meaning of the stimuli. Furthermore, in the incongruent condition, amplitude of the occipital total alpha in the very late phase (700-900 ms) was smaller. This prolonged desynchronization in the alpha band could be reflecting augmentation of attentional filters in visual modality for the next stimulus. These multiple findings on EEG time-frequency plane provide improved description of the overlapping processes in Stroop test. PMID:25135670

  17. Reassigned time-frequency peak filtering for seismic random noise attenuation

    NASA Astrophysics Data System (ADS)

    Lin, H.; Li, Y.; Ma, H.

    2012-12-01

    Seismic noise attenuation for the aim of improving signal-to-noise ratio (S/N) plays an important role in seismic data processing for detailed description of oil and gas reservoirs. In particular, strong seismic random noise, which is unpredictable and incoherent in space and time, always degrades the qualities of seismic exploration and much more difficult to be suppressed than coherent noise, since only its statistical properties can be used. It is a common problem in random noise attenuation to keep the signal with minimized distortion. Multi-direction, multi-scale and time-varying methods can be considered as appropriate for tracking the signal characteristics varying in time. In particular, time-frequency based methods might better recover the local characteristics of the non-stationary seismic signal, which is important to produce a satisfactory random noise attenuation result. Time-frequency peak filtering(TFPF), which has already proved to be a powerful tool for Gaussian random noise attenuation in linear signal, can be alternative tool for seismic random noise attenuation. Indeed, seismic noise sometimes may have an asymmetric Wigner-Ville spectrum(WVS) and the seismic signal is nonlinear in time, which might induce amplitude attenuation and residual random noise in the results. This work reports the preliminary results from an improved TFPF method planned to obtain more accurate estimation of the seismic signal by increasing the signal concentration of the time-frequency distribution(TFD) during TFPF. At the beginning the improved reassignment TFPF(RTFPF) encoded the seismic trace as an instantaneous frequency (IF) of the analytic signal generated by frequency modulation. After that the smooth pseudo Wigner-Ville distribution(SPWVD) of the coded analytic signal was computed. The separate frequency window of the SPWVD helps to smooth away the random oscillations introduced by the WVS of seismic noise and nonlinear signal component in the pseudo Wigner-Ville distribution (PWVD) used by conventional TFPF. Moreover, the time-frequency reassignment method is adopted with the aim to concentrate the SPWVD to the IF of the coded signal to obtain accurate filtering signal. The coordinates of the reassigned SPWVD are the center of the gravity of the TFD, which is the estimation of the IF. Subsequently, RTFPF took the peaks of the reassigned SPWVD over the frequency to obtain the filtering signal. The RTFPF were applied to the synthetic seismic data and a common-shot-point gather. The results were compared with the conventional TFPF using the PWVD. The preliminary results seem to be encouraged in random noise attenuation and precision of the signal when applying RTFPF. Example on a field seismic record.

  18. Time-frequency representation of a highly nonstationary signal via the modified Wigner distribution

    NASA Technical Reports Server (NTRS)

    Zoladz, T. F.; Jones, J. H.; Jong, J.

    1992-01-01

    A new signal analysis technique called the modified Wigner distribution (MWD) is presented. The new signal processing tool has been very successful in determining time frequency representations of highly non-stationary multicomponent signals in both simulations and trials involving actual Space Shuttle Main Engine (SSME) high frequency data. The MWD departs from the classic Wigner distribution (WD) in that it effectively eliminates the cross coupling among positive frequency components in a multiple component signal. This attribute of the MWD, which prevents the generation of 'phantom' spectral peaks, will undoubtedly increase the utility of the WD for real world signal analysis applications which more often than not involve multicomponent signals.

  19. Models of the Joint Structure of Domain-Related and Global Distress: Implications for the Reconciliation of Quality of Life and Mental Health Perspectives

    ERIC Educational Resources Information Center

    Magee, William; St-Arnaud, Sebastien

    2012-01-01

    Research on subjective wellbeing includes studies of both domain-related and global distress. The mental health literature, though, focuses almost exclusively on global distress. This seems to be partly due to a common belief that psychological distress, and the moods that comprise distress, necessarily lack referential content. However, if that…

  20. Applying matching pursuit decomposition time-frequency processing to UGS footstep classification

    NASA Astrophysics Data System (ADS)

    Larsen, Brett W.; Chung, Hugh; Dominguez, Alfonso; Sciacca, Jacob; Kovvali, Narayan; Papandreou-Suppappola, Antonia; Allee, David R.

    2013-06-01

    The challenge of rapid footstep detection and classification in remote locations has long been an important area of study for defense technology and national security. Also, as the military seeks to create effective and disposable unattended ground sensors (UGS), computational complexity and power consumption have become essential considerations in the development of classification techniques. In response to these issues, a research project at the Flexible Display Center at Arizona State University (ASU) has experimented with footstep classification using the matching pursuit decomposition (MPD) time-frequency analysis method. The MPD provides a parsimonious signal representation by iteratively selecting matched signal components from a pre-determined dictionary. The resulting time-frequency representation of the decomposed signal provides distinctive features for different types of footsteps, including footsteps during walking or running activities. The MPD features were used in a Bayesian classification method to successfully distinguish between the different activities. The computational cost of the iterative MPD algorithm was reduced, without significant loss in performance, using a modified MPD with a dictionary consisting of signals matched to cadence temporal gait patterns obtained from real seismic measurements. The classification results were demonstrated with real data from footsteps under various conditions recorded using a low-cost seismic sensor.

  1. Time-frequency analysis of CHAMP scalar and vector magnetic data

    NASA Astrophysics Data System (ADS)

    Balasis, G.; Maus, S.; Luehr, H.; Rother, M.

    2003-12-01

    Wavelet transforms began to be used in geophysics in the early 1980s for the analysis of seismic signals. The advantage of analyzing a signal with wavelets as the analyzing kernels, is that it enables one to study features of the signal locally with a detail matched to their scale. Owing to their unique time-frequency localization property, wavelet analysis is especially useful for signals that are non-stationary, have short-lived transient components, have features at different scales, or have singularities. Unfortunately, many studies using time-frequency analysis have suffered from an apparent lack of quantitative results. We have applied the continuous wavelet transform to analyze 3 years of Fluxgate and Overhauser magnetometer data of the CHAMP satellite mission. We have detected and classified not only artificial source noise (e.g. instrument problems and pre-processing errors) but also high frequency natural signals of external fields (e.g. F-region currents and pulsations). The results of this analysis will be used for: (a) consequent correction and flagging of the data, (b) derivation of a suitable (undisturbed) dataset for the purposes of crustal and main field modeling, and, (c) study of natural signals (e.g. F-region currents, pulsations) contained in the data.

  2. Time-frequency methods and voluntary ramped-frequency breathing: a powerful combination for exploration of human neurophysiological mechanisms

    PubMed Central

    Stankovski, Tomislav; Cooke, William H.; Rudas, László; Stefanovska, Aneta

    2013-01-01

    We experimentally altered the timing of respiratory motoneuron activity as a means to modulate and better understand otherwise hidden human central neural and hemodynamic oscillatory mechanisms. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, tidal carbon dioxide concentrations, and muscle sympathetic nerve activity in 13 healthy supine young men who gradually increased or decreased their breathing frequencies between 0.05 and 0.25 Hz over 9-min periods. We analyzed results with traditional time- and frequency-domain methods, and also with time-frequency methods (wavelet transform, wavelet phase coherence, and directional coupling). We determined statistical significance and identified frequency boundaries by comparing measurements with randomly generated surrogates. Our results support several major conclusions. First, respiration causally modulates both sympathetic (weakly) and vagal motoneuron (strongly) oscillations over a wide frequency range—one that extends well below the frequency of actual breaths. Second, breathing frequency broadly modulates vagal baroreflex gain, with peak gains registered in the low frequency range. Third, breathing frequency does not influence median levels of sympathetic or vagal activity over time. Fourth, phase relations between arterial pressure and sympathetic and vagal motoneurons are unaffected by breathing, and are therefore likely secondary to intrinsic responsiveness of these motoneurons to other synaptic inputs. Finally, breathing frequency does not affect phase coherence between diastolic pressure and muscle sympathetic oscillations, but it augments phase coherence between systolic pressure and R-R interval oscillations over a limited portion of the usual breathing frequency range. These results refine understanding of autonomic oscillatory processes and those physiological mechanisms known as the human respiratory gate. PMID:24114700

  3. Adaptive TimeFrequency Decompositions with Matching Pursuits Geoffrey Davis, St'ephane Mallat, and Zhifeng Zhang

    E-print Network

    Davis, Geoff

    the coherent structures of a signal and describe an application to pattern extraction from noisy signals. 1 in section 6. The signal is decomposed into a selected set of time­frequency atoms, the dilations

  4. TIME-FREQUENCY PARTITIONS FOR THE GELFAND TRIPLE (S0, L2 MONIKA DORFLER, HANS G. FEICHTINGER AND KARLHEINZ GROCHENIG

    E-print Network

    Feichtinger, Hans Georg

    , and these will be our subject here. As our main tool for time-frequency analysis we use the short-time Fourier transform by the Austrian science fund FWF, Projects P14485 and P15605. 1 #12;2 MONIKA D ¨ORFLER, HANS G. FEICHTINGER are defined by the short-time Fourier transform and determine the local time-frequency behavior, whereas

  5. Time-frequency dynamics of superluminal pulse transition to the subluminal regime.

    PubMed

    Dorrah, Ahmed H; Ramakrishnan, Abhinav; Mojahedi, Mo

    2015-03-01

    Spectral reshaping and nonuniform phase delay associated with an electromagnetic pulse propagating in a temporally dispersive medium may lead to interesting observations in which the group velocity becomes superluminal or even negative. In such cases, the finite bandwidth of the superluminal region implies the inevitable existence of a cutoff distance beyond which a superluminal pulse becomes subluminal. In this paper, we derive a closed-form analytic expression to estimate this cutoff distance in abnormal dispersive media with gain. Moreover, the method of steepest descent is used to track the time-frequency dynamics associated with the evolution of the center of mass of a superluminal pulse to the subluminal regime. This evolution takes place at longer propagation depths as a result of the subluminal components affecting the behavior of the pulse. Finally, the analysis presents the fundamental limitations of superluminal propagation in light of factors such as the medium depth, pulse width, and the medium dispersion strength. PMID:25871237

  6. Event-related EEG time-frequency PCA and the orienting reflex to auditory stimuli.

    PubMed

    Barry, Robert J; De Blasio, Frances M; Bernat, Edward M; Steiner, Genevieve Z

    2015-04-01

    We recently reported an auditory habituation series with counterbalanced indifferent and significant (counting) instructions. Time-frequency (t-f) analysis of electrooculogram-corrected EEG was used to explore event-related synchronization (ERS)/desynchronization (ERD) in four EEG bands using arbitrarily selected time epochs and traditional frequency ranges. ERS in delta, theta, and alpha, and subsequent ERD in theta, alpha, and beta, showed substantial decrement over trials, yet effects of stimulus significance (count vs. no-task) were minimal. Here, we used principal components analysis (PCA) of the t-f data to investigate the natural frequency and time combinations involved in such stimulus processing. We identified four ERS and four ERD t-f components: six showed decrement over trials, four showed count > no-task effects, and six showed Significance?×?Trial interactions. This increased sensitivity argues for the wider use of our data-driven t-f PCA approach. PMID:25353309

  7. Flutter of High-Speed Civil Transport Flexible Semispan Model: Time-Frequency Analysis

    NASA Technical Reports Server (NTRS)

    Chabalko, Christopher C.; Hajj, Muhammad R.; Silva, Walter A.

    2006-01-01

    Time/frequency analysis of fluctuations measured by pressure taps and strain gauges in the experimental studies of the flexible semispan model of a high-speed civil transport wing configuration is performed. The interest is in determining the coupling between the aerodynamic loads and structural motions that led to the hard flutter conditions and loss of the model. The results show that, away from the hard flutter point, the aerodynamic loads at all pressure taps near the wing tip and the structural motions contained the same frequency components. On the other hand, in the flow conditions leading to the hard flutter, the frequency content of the pressure fluctuations near the leading and trailing edges varied significantly. This led to contribution to the structural motions over two frequency ranges. The ratio of these ranges was near 2:1, which suggests the possibility of nonlinear structural coupling.

  8. Time-frequency analysis of band-limited EEG with BMFLC and Kalman filter for BCI applications

    PubMed Central

    2013-01-01

    Background Time-Frequency analysis of electroencephalogram (EEG) during different mental tasks received significant attention. As EEG is non-stationary, time-frequency analysis is essential to analyze brain states during different mental tasks. Further, the time-frequency information of EEG signal can be used as a feature for classification in brain-computer interface (BCI) applications. Methods To accurately model the EEG, band-limited multiple Fourier linear combiner (BMFLC), a linear combination of truncated multiple Fourier series models is employed. A state-space model for BMFLC in combination with Kalman filter/smoother is developed to obtain accurate adaptive estimation. By virtue of construction, BMFLC with Kalman filter/smoother provides accurate time-frequency decomposition of the bandlimited signal. Results The proposed method is computationally fast and is suitable for real-time BCI applications. To evaluate the proposed algorithm, a comparison with short-time Fourier transform (STFT) and continuous wavelet transform (CWT) for both synthesized and real EEG data is performed in this paper. The proposed method is applied to BCI Competition data IV for ERD detection in comparison with existing methods. Conclusions Results show that the proposed algorithm can provide optimal time-frequency resolution as compared to STFT and CWT. For ERD detection, BMFLC-KF outperforms STFT and BMFLC-KS in real-time applicability with low computational requirement. PMID:24274109

  9. Frequency Domain Load Calculation for Offshore Wind Turbines (TURBU Offshore)

    Microsoft Academic Search

    T. G. van Engelen

    The design of offshore wind turbines requires to assess a huge amount of different sea-states and wind conditions. Therefor the calculational efficiency of a comb ined time\\/frequency domain approach is attractive. This was the reason for the development of the frequency domain tool TURBU Offshore. In addition, such a tool is very feasible for parameter studies; the dynamics of large

  10. Analysis of concert hall acoustics via visualizations of time-frequency and spatiotemporal responses.

    PubMed

    Pätynen, Jukka; Tervo, Sakari; Lokki, Tapio

    2013-02-01

    Acousticians and other practitioners alike often describe acoustic conditions in performance spaces with standard objective parameters. Apart from a few exceptions, the parameters are calculated by integrating the sound energy of the impulse responses over time; this makes them inadequate for researching the acoustics in detail, especially in the early part of the room impulse response. This paper proposes a method based on time-frequency and spatiotemporal presentations to overcome the lack of detail in the standard analysis. In brief, the proposed methods visualize the cumulative development of the sound field as a function of frequency or direction by forward-integrating the energy in the impulse response in short time frames. Analysis on the measurements from six concert halls concentrates particularly on interpreting the results in light of the seat dip effect. Earlier research has concluded that the seat dip effect is reduced by reflection from low overhead surfaces. In contrast, the current results indicate that the seat dip attenuation in the frequency response is corrected the best when the hall provides most lateral reflections. These findings suggest that the proposed analysis is suitable for explaining concert hall acoustics in detail. PMID:23363103

  11. Acoustic emission source location in plates using wavelet analysis and cross time frequency spectrum.

    PubMed

    Mostafapour, A; Davoodi, S; Ghareaghaji, M

    2014-12-01

    In this study, the theories of wavelet transform and cross-time frequency spectrum (CTFS) are used to locate AE source with frequency-varying wave velocity in plate-type structures. A rectangular array of four sensors is installed on the plate. When an impact is generated by an artificial AE source such as Hsu-Nielsen method of pencil lead breaking (PLB) at any position of the plate, the AE signals will be detected by four sensors at different times. By wavelet packet decomposition, a packet of signals with frequency range of 0.125-0.25MHz is selected. The CTFS is calculated by the short-time Fourier transform of the cross-correlation between considered packets captured by AE sensors. The time delay is calculated when the CTFS reaches the maximum value and the corresponding frequency is extracted per this maximum value. The resulting frequency is used to calculate the group velocity of wave velocity in combination with dispersive curve. The resulted locating error shows the high precision of proposed algorithm. PMID:25063341

  12. Time-Frequency Analysis of Transient-Evoked Otoacoustic Emissions in Children exposed to Carboplatin Chemotherapy

    PubMed Central

    Bhagat, Shaum; Bass, Johnnie; Qaddoumi, Ibrahim; Brennan, Rachel; Wilson, Matthew; Wu, Jianrong; Galindo, Carlos-Rodriguez; Paglialonga, Alessia; Tognola, Gabriella

    2013-01-01

    The aims of this study were to characterize and quantify time-frequency changes in transient-evoked otoacoustic emissions (TEOAEs) recorded in children diagnosed with retinoblastoma who were receiving carboplatin chemotherapy. A signal processing technique, the wavelet transform (WT), was used to analyze TEOAE waveforms in narrow-band frequency components. Ten children (aged 3–72 months) diagnosed with unilateral or bilateral retinoblastoma were enrolled in the study. TEOAEs were acquired from the children with linear sequences of 70 dB peSPL clicks. After WT analysis, TEOAE energy, latency, and normalized energy in the narrow-band frequency components were compared before and during carboplatin (average dose 1693 mg/m2) chemotherapy treatment. On a group basis, no significant differences (p>0.05) in pre- and post-carboplatin TEOAE energy, latency, or normalized energy were observed. There were decreases in normalized energy on an individual basis in 10/18 ears in the sample. Exposure to carboplatin chemotherapy did not cause significant changes in TEOAE energy, latency, and normalized energy during treatment. However, long-term monitoring of hearing with measurements of TEOAEs is warranted given the risks of delayed hearing loss in some children receiving carboplatin chemotherapy. PMID:23147804

  13. Time-Frequency Analysis of Rocket Nozzle Wall Pressures During Start-up Transients

    NASA Technical Reports Server (NTRS)

    Baars, Woutijn J.; Tinney, Charles E.; Ruf, Joseph H.

    2011-01-01

    Surveys of the fluctuating wall pressure were conducted on a sub-scale, thrust- optimized parabolic nozzle in order to develop a physical intuition for its Fourier-azimuthal mode behavior during fixed and transient start-up conditions. These unsteady signatures are driven by shock wave turbulent boundary layer interactions which depend on the nozzle pressure ratio and nozzle geometry. The focus however, is on the degree of similarity between the spectral footprints of these modes obtained from transient start-ups as opposed to a sequence of fixed nozzle pressure ratio conditions. For the latter, statistically converged spectra are computed using conventional Fourier analyses techniques, whereas the former are investigated by way of time-frequency analysis. The findings suggest that at low nozzle pressure ratios -- where the flow resides in a Free Shock Separation state -- strong spectral similarities occur between fixed and transient conditions. Conversely, at higher nozzle pressure ratios -- where the flow resides in Restricted Shock Separation -- stark differences are observed between the fixed and transient conditions and depends greatly on the ramping rate of the transient period. And so, it appears that an understanding of the dynamics during transient start-up conditions cannot be furnished by a way of fixed flow analysis.

  14. Effects of mobile phone exposure on time frequency fine structure of transiently evoked otoacoustic emissions.

    PubMed

    Paglialonga, Alessia; Tognola, Gabriella; Parazzini, Marta; Lutman, Mark E; Bell, Steven L; Thuroczy, Gyorgy; Ravazzani, Paolo

    2007-10-01

    Mobile phones have become very commonly used worldwide within a short period of time. To date there is only limited knowledge about interaction between electromagnetic fields (EMFs) emitted by mobile phones and the auditory function. Moreover, there is widespread concern that there may be potential for harm. The aim of this study was to assess potential subtle changes in cochlear function by measuring the temporal and spectral fine structure of transiently evoked otoacoustic emissions (TEOAE) in normal hearing subjects after exposure to EMFs emitted by Global System for Mobile Communication (GSM) mobile phones. TEOAEs were recorded in 27 healthy young adults before and after 10 min of real or sham exposure in a double-blind design. TEOAE data were analyzed both globally (broadband analysis) and using the Wavelet Transform (analysis of the time-frequency fine structure). The broadband analysis revealed no significant effect on TEOAEs related to exposure, confirming results of previous studies; in addition, no significant change was detected in the analysis of the elementary wavelet components, suggesting that the temporal and spectral fine structure of TEOAEs is not affected by 10 min exposure to low-intensity EMFs emitted by GSM mobile phones. PMID:17902853

  15. Cardiorespiratory Dynamic Response to Mental Stress: A Multivariate Time-Frequency Analysis

    PubMed Central

    Orini, Michele; Van Huffel, Sabine

    2013-01-01

    Mental stress is a growing problem in our society. In order to deal with this, it is important to understand the underlying stress mechanisms. In this study, we aim to determine how the cardiorespiratory interactions are affected by mental arithmetic stress and attention. We conduct cross time-frequency (TF) analyses to assess the cardiorespiratory coupling. In addition, we introduce partial TF spectra to separate variations in the RR interval series that are linearly related to respiration from RR interval variations (RRV) that are not related to respiration. The performance of partial spectra is evaluated in two simulation studies. Time-varying parameters, such as instantaneous powers and frequencies, are derived from the computed spectra. Statistical analysis is carried out continuously in time to evaluate the dynamic response to mental stress and attention. The results show an increased heart and respiratory rate during stress and attention, compared to a resting condition. Also a fast reduction in vagal activity is noted. The partial TF analysis reveals a faster reduction of RRV power related to (3?s) than unrelated to (30?s) respiration, demonstrating that the autonomic response to mental stress is driven by mechanisms characterized by different temporal scales. PMID:24386006

  16. Optical phase noise from atmospheric fluctuations and its impact on optical time-frequency transfer

    NASA Astrophysics Data System (ADS)

    Sinclair, L. C.; Giorgetta, F. R.; Swann, W. C.; Baumann, E.; Coddington, I.; Newbury, N. R.

    2014-02-01

    The time of flight for a laser beam through the atmosphere will fluctuate as the path-averaged index of refraction varies with atmospheric turbulence, air temperature, and pressure. We measure these fluctuations by transmitting optical pulses from a frequency comb across a 2-km horizontal path and detecting variations in their time of flight through linear optical sampling. This technique is capable of continuous measurements, with femtosecond resolution, over time scales of many hours despite turbulence-induced signal fading. The power spectral density for the time of flight, or equivalently for the optical phase, follows a simple power-law response of ?f-2.3 measured down to Fourier frequencies, f, of 100 ?Hz. There is no evidence of a roll-off at low frequencies associated with an outer scale for turbulence. Both of these results depart from the predictions of turbulence theory, but are consistent with some other results in the literature. We discuss the implications for the stability and accuracy of one-way optical time-frequency transfer.

  17. Estimating the number of components of a multicomponent nonstationary signal using the short-term time-frequency Rényi entropy

    NASA Astrophysics Data System (ADS)

    Sucic, Victor; Saulig, Nicoletta; Boashash, Boualem

    2011-12-01

    The time-frequency Rényi entropy provides a measure of complexity of a nonstationary multicomponent signal in the time-frequency plane. When the complexity of a signal corresponds to the number of its components, then this information is measured as the Rényi entropy of the time-frequency distribution (TFD) of the signal. This article presents a solution to the problem of detecting the number of components that are present in short-time interval of the signal TFD, using the short-term Rényi entropy. The method is automatic and it does not require a prior information about the signal. The algorithm is applied on both synthetic and real data, using a quadratic separable kernel TFD. The results confirm that the short-term Rényi entropy can be an effective tool for estimating the local number of components present in the signal. The key aspect of selecting a suitable TFD is also discussed.

  18. Kernel design for time-frequency signal analysis using the Radon transform

    Microsoft Academic Search

    B. Ristic; B. Boashash

    1993-01-01

    The authors present a kernel design technique based on using the Radon transform of the modulus of the ambiguity function of the signal for determination of angles and distances of radially distributed contents of the autoterms in the ambiguity domain. The proposed kernel effectively reduces the cross-terms and noise for linear FM signals. The result is a tool for high-resolution

  19. Enhancing Visualization with Real-Time Frequency-based Transfer Functions

    E-print Network

    and visualization of 3D data. Frequency-based transfer functions offer the possibility to discriminate signals and MRI data, physics data as well as synthetic seismic data. The interactive design of complex filters.1 In geology, the study of 3D seismic data in the frequency domain2 is of particular importance

  20. Adaptive multicarrier modulation: a convenient framework for time-frequency processing in wireless communications

    Microsoft Academic Search

    THOMAS KELLER; LAJOS HANZO

    2000-01-01

    A historical perspective of orthogonal frequency-division multiplexing (OFDM) is given with reference to its literature. Its advantages and disadvantages are reviewed, and its performance is characterized over highly dispersive channels. The effects of both time- and frequency-domain synchronization errors are quantified, and a range of solutions proposed in the recent literature are reviewed. One of the main objectives of this

  1. Non-identical smoothing operators for estimating time-frequency interdependence in electrophysiological recordings

    NASA Astrophysics Data System (ADS)

    Mehrkanoon, Saeid; Breakspear, Michael; Daffertshofer, Andreas; Boonstra, Tjeerd W.

    2013-12-01

    Synchronization of neural activity from distant parts of the brain is crucial for the coordination of cognitive activities. Because neural synchronization varies both in time and frequency, time-frequency (T-F) coherence is commonly employed to assess interdependences in electrophysiological recordings. T-F coherence entails smoothing the cross and power spectra to ensure statistical consistency of the estimate, which reduces its T-F resolution. This trade-off has been described in detail when the cross and power spectra are smoothed using identical smoothing operators, which may yield spurious coherent frequencies. In this article, we examine the use of non-identical smoothing operators for the estimation of T-F interdependence, i.e., phase synchronization is characterized by phase locking between signals captured by the cross spectrum and we may hence improve the trade-off by selectively smoothing the auto spectra. We first show that the frequency marginal density of the present estimate is bound within [0,1] when using non-identical smoothing operators. An analytic calculation of the bias and variance of present estimators is performed and compared with the bias and variance of standard T-F coherence using Monte Carlo simulations. We then test the use of non-identical smoothing operators on simulated data, whose T-F properties are known through construction. Finally, we analyze empirical data from eyes-closed surface electroencephalography recorded in human subjects to investigate alpha-band synchronization. These analyses show that selectively smoothing the auto spectra reduces the bias of the estimator and may improve the detection of T-F interdependence in electrophysiological data at high temporal resolution.

  2. Astrophysically motivated time frequency clustering for burst gravitational wave search: application to TAMA300 data

    NASA Astrophysics Data System (ADS)

    Honda, Ryota; Yamagishi, Shougo; Kanda, Nobuyuki; TAMA Collaboration

    2008-09-01

    We have developed a method of 'time frequency (TF) clustering' to find burst gravitational waves for TAMA data analysis. The TF clustering method on the sonogram (spectrogram) shows some characteristics of short-duration signals. Burst gravitational waveforms from stellar-core collapse of supernovae that are predicted by Dimmelmeier et al [1, 2] (DFM waveforms) have short durations on the order of 10 ms and have a large spike and ringing tail in time series. On the other hand, typical detector instrumental noise transients of the same timescale have different waveforms as like as simpler spikes. Since the numerically predicted waveforms may not be reliable given conditions and model dependency, using one search algorithm is not robust to differentiate gravitational waves from instrumental noises. Our proposal for performing the separation is to compare many parameters of the cluster that represent the signal waveform. This approach will be useful for cases when the difference between gravitational waves and noise is not clear for one parameter. We employ TF clustering to represent the waveform characteristics. We calculated the parameters of each respective cluster, such as the magnitude and the Nth momentum around the center of a power distribution of the cluster. Using these parameters, we can efficiently identify some predicted gravitational waveforms and can exclude the TAMA detector's typical unstable spike-like noises due to the instruments. Our selection criteria for TF cluster shape parameters achieved an average efficiency of roughly 50% for injected DFM waveforms of h_rss\\sim 2 \\times 10^{-20}\\; {Hz^{-1/2}} (source distance of 350 pc) with false alarm rate of ~1 Hz. In addition, the false alarm rate for larger noises, such as SNR > 100, is improved 10-fold by applying the selection criteria for TF cluster parameters.

  3. A comparative study on hydrocarbon detection using three EMD-based time-frequency analysis methods

    NASA Astrophysics Data System (ADS)

    Xue, Ya-juan; Cao, Jun-xing; Tian, Ren-fei

    2013-02-01

    Due to strong heterogeneity of marine carbonate reservoir, seismic signals become more complex, thus, it is very difficult for hydrocarbon detection. In hydrocarbon reservoir, there usually exist some changes in seismic wave energy and frequency. In their instantaneous spectrums there often exist such phenomena that show the characteristics of attenuation of high frequency energy and enhancement of low-frequency energy. The three EMD-based time-frequency analysis methods' instantaneous spectra all have certain oil and gas detection capability. In this paper, we introduced the Normalized Hilbert Transform (NHT) and a new method named the HU method for hydrocarbon detection. The model results in the Jingbian Gas Field which is located in the eastern Ordos Basin, China, show that NHT and HU methods can be adopted. They also detect the gas-bearing reservoir efficiently as the HHT method does. The three EMD-based methods, that is, the Hilbert-Huang transformation (HHT) and NHT and HU methods, were respectively applied to analyze the seismic data from the Jingbian Gas Field. Firstly, the seismic signals were decomposed into a finite number of intrinsic mode functions (IMFs) by empirical mode decomposition (EMD) method. The second IMF signal (IMF2) of the original seismic section better indicates the distribution of the reservoir. Information on hydrocarbon-bearing reservoir is mainly in IMF2. Secondly, the HHT, NHT and HU methods were respectively used to obtain different frequency division sections from IMF2. Hydrocarbon detection was realized from the energy distribution of the different frequency division sections with these three EMD-based methods. The practical application results show that the three EMD-based methods can all be employed to hydrocarbon detection. Frequency division section of IMF2 using NHT method was better for the seismic data from the Jingbian Gas Field than when using the HHT method and HU method.

  4. Seismic random noise attenuation and signal-preserving by multiple directional time-frequency peak filtering

    NASA Astrophysics Data System (ADS)

    Zhang, Chao; Li, Yue; Lin, Hong-bo; Yang, Bao-jun

    2015-01-01

    Time-frequency peak filtering (TFPF) is an effective method for seismic random noise attenuation. The linearity of the signal has a significant influence on the accuracy of the TFPF method. The higher the linearity of the signal to be filtered is, the better the denoising result is. With this in mind, and taking the lateral coherence of reflected events into account, we do TFPF along the reflected events to improve the degree of linearity and enhance the continuity of these events. The key factor to realize this idea is to find the traces of the reflected events. However, the traces of the events are too hard to obtain in the complicated field seismic data. In this paper, we propose a Multiple Directional TFPF (MD-TFPF), in which the filtering is performed in certain direction components of the seismic data. These components are obtained by a directional filter bank. In each direction component, we do TFPF along these decomposed reflected events (the local direction of the events) instead of the channel direction. The final result is achieved by adding up the filtering results of all decomposition directions of seismic data. In this way, filtering along the reflected events is implemented without accurately finding the directions. The effectiveness of the proposed method is tested on synthetic and field seismic data. The experimental results demonstrate that MD-TFPF can more effectively eliminate random noise and enhance the continuity of the reflected events with better preservation than the conventional TFPF, curvelet denoising method and F-X deconvolution method.

  5. The Benefits of Using Time-Frequency Analysis with Synthetic Aperture Focusing Technique

    SciTech Connect

    Albright, Austin P [ORNL; Clayton, Dwight A [ORNL

    2015-01-01

    Improvements in detection and resolution are always desired and needed. There are various instruments available for the inspection of concrete structures that can be used with confidence for detecting different defects. However, more often than not that confidence is heavily dependent on the experience of the operator rather than the clear, objective discernibility of the output of the instrument. The challenge of objective discernment is amplified when the concrete structures contain multiple layers of reinforcement, are of significant thickness, or both, such as concrete structures in nuclear power plants. We seek to improve and extend the usefulness of results produced using the synthetic aperture focusing technique (SAFT) on data collected from thick, complex concrete structures. A secondary goal is to improve existing SAFT results, with regards to repeatedly and objectively identifying defects and/or internal structure of concrete structures. Towards these goals, we are applying the time-frequency technique of wavelet packet decomposition and reconstruction using a mother wavelet that possesses the exact reconstruction property. However, instead of analyzing the coefficients of each decomposition node, we select and reconstruct specific nodes based on the frequency band it contains to produce a frequency band specific time-series representation. SAFT is then applied to these frequency specific reconstructions allowing SAFT to be used to visualize the reflectivity of a frequency band and that band s interaction with the contents of the concrete structure. We apply our technique to data sets collected using a commercial, ultrasonic linear array (MIRA) from two 1.5m x 2m x 25cm concrete test specimens. One specimen contains multiple layers of rebar. The other contains honeycomb, crack, and rebar bonding defect analogs. This approach opens up a multitude of possibilities for improved detection, readability, and overall improved objectivity. We will focus on improved defect/reinforcement isolation in thick and multilayered reinforcement environments. Additionally, the ability to empirically explore the possibility of a frequency-band-defect-type relationship or sensitivity becomes available.

  6. Vibration analysis of rotating machinery using time-frequency analysis and wavelet techniques

    NASA Astrophysics Data System (ADS)

    Al-Badour, F.; Sunar, M.; Cheded, L.

    2011-08-01

    Time-frequency analysis, including the wavelet transform, is one of the new and powerful tools in the important field of structural health monitoring, using vibration analysis. Commonly-used signal analysis techniques, based on spectral approaches such as the fast Fourier transform, are powerful in diagnosing a variety of vibration-related problems in rotating machinery. Although these techniques provide powerful diagnostic tools in stationary conditions, they fail to do so in several practical cases involving non-stationary data, which could result either from fast operational conditions, such as the fast start-up of an electrical motor, or from the presence of a fault causing a discontinuity in the vibration signal being monitored. Although the short-time Fourier transform compensates well for the loss of time information incurred by the fast Fourier transform, it fails to successfully resolve fast-changing signals (such as transient signals) resulting from non-stationary environments. To mitigate this situation, wavelet transform tools are considered in this paper as they are superior to both the fast and short-time Fourier transforms in effectively analyzing non-stationary signals. These wavelet tools are applied here, with a suitable choice of a mother wavelet function, to a vibration monitoring system to accurately detect and localize faults occurring in this system. Two cases producing non-stationary signals are considered: stator-to-blade rubbing, and fast start-up and coast-down of a rotor. Two powerful wavelet techniques, namely the continuous wavelet and wavelet packet transforms, are used for the analysis of the monitored vibration signals. In addition, a novel algorithm is proposed and implemented here, which combines these two techniques and the idea of windowing a signal into a number of shaft revolutions to localize faults.

  7. An adaptive statistical time-frequency method for detection of broken bars and bearing faults in motors using stator current

    Microsoft Academic Search

    B. Yazici; G. B. Kliman

    1999-01-01

    It is well known that motor current is a nonstationary signal, the properties of which vary with respect to the time-varying normal operating conditions of the motor. As a result, Fourier analysis makes it difficult to recognize fault conditions from the normal operating conditions of the motor. Time-frequency analysis, on the other hand, unambiguously represents the motor current which makes

  8. 862 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 12, NO. 2, FEBRUARY 2013 Unitary Differential Space-Time-Frequency Codes

    E-print Network

    Lübeck, Universität zu

    , namely multi-band orthogonal frequency division multiplexing ultra-wideband (MB-OFDM UWB) [3], [4 Differential Space-Time-Frequency Codes for MB-OFDM UWB Wireless Communications L. C. Tran, Member, IEEE, A-input multiple-output (MIMO), multi- band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband

  9. 978-1-4244-4522-6/09/$25.00 2009 IEEE ISCIT 20091161 Unitary Differential Space-Time-Frequency Codes

    E-print Network

    Lübeck, Universität zu

    multiplexing (MB-OFDM) ultra-wideband (UWB) system, coherent detection where the channel state information (CSI multiplexing ultra-wideband (MB-OFDM UWB) [1], multiple-input multiple-output (MIMO), and space-Time-Frequency Codes for MB-OFDM UWB L. C. Tran University of Wollongong Wollongong, Australia A. Mertins University

  10. IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 46, NO. 7, JULY 1999 861 Multiple Window Time-Frequency Distribution

    E-print Network

    Haykin, Simon

    and variance. In this paper, we describe the application of MW-TFA techniques to electroencephalogram (EEG-- Electroencephalogram (EEG), Hermite func- tions, multiple window (MW), Slepian sequences, spectrogram, time-frequency analysis (TFA). I. INTRODUCTION ELECTROENCEPHALOGRAM (EEG) is the summed electrical activity of very large

  11. Identification of Damaged Wheat Kernels and Cracked-Shell Hazelnuts with Impact Acoustics Time-Frequency Patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new adaptive time-frequency (t-f) analysis and classification procedure is applied to impact acoustic signals for detecting hazelnuts with cracked shells and three types of damaged wheat kernels. Kernels were dropped onto a steel plate, and the resulting impact acoustic signals were recorded with ...

  12. Improved robust features for speech recognition by integrating time-frequency principal components (TFPC) and histogram equalization (HEQ)

    Microsoft Academic Search

    Shang-nien Tsai; Lin-shan Lee

    2003-01-01

    Robustness for speech recognition technologies with respect to adverse environments has been a key issue for real applications. Time-frequency principal components (TFPC) features have been shown to be a set of powerful data-driven features under matched circumstances, while histogram equalization (HEQ) has been proposed as an efficient feature transformation approach to reduce the mismatch between training and testing conditions. It

  13. An application of morphologic filters to remove non-linear distortions from time-frequency representations of acoustic signals

    Microsoft Academic Search

    G. G. Soledad; N. O. Valery

    Time-frequency representations have been of great interest when analyzing and classifying acoustic signals. The use of transformation techniques as selective as possible is a useful tool to obtain accurate information for such type of studies. The Wigner-Ville distribution has high time and frequency selectivity as well as meeting some interesting mathematical properties. However interference terms ap- pear, due to the

  14. Adaptive signal processing and higher order time- frequency analysis for acoustic and vibration signatures in condition monitoring

    Microsoft Academic Search

    Sang-Kwon Lee

    1997-01-01

    This thesis is concerned with the development of a useful engineering technique to detect and analyse faults in rotating machinery. The methods developed are based on the advanced signal processing such as the adaptive signal processing and higher-order time frequency methods. The two-stage Adaptive Line Enhancer (ALE), using adaptive signal processing, has been developed for increasing the Signal to Noise

  15. Target ranging and the role of time-frequency structure of synthetic echoes in big brown bats, Eptesicus fuscus

    Microsoft Academic Search

    Annemarie Surlykke

    1992-01-01

    Echolocating bats judge the distance to a target on basis of the delay between the emitted cry and the returning echo. In a phantom echo set-up it was investigated how changes in the time-frequency structure of synthetic echoes affect ranging accuracy of big brown bats, Eptesicus fuscus.

  16. Optimization of high-order harmonic generation by genetic algorithm and wavelet time-frequency analysis of quantum dipole emission

    E-print Network

    Chu, Shih-I

    Optimization of high-order harmonic generation by genetic algorithm and wavelet time-frequency analysis of quantum dipole emission Xi Chu and Shih-I Chu Department of Chemistry, University of Kansas-dimensional quantum study of the coherent control of high-order harmonic generation HHG processes in intense pulsed

  17. Classification of the intention to generate a shoulder versus elbow torque by means of a time frequency synthesized spatial patterns BCI algorithm

    NASA Astrophysics Data System (ADS)

    Deng, Jie; Yao, Jun; Dewald, Julius P. A.

    2005-12-01

    In this paper, we attempt to determine a subject's intention of generating torque at the shoulder or elbow, two neighboring joints, using scalp electroencephalogram signals from 163 electrodes for a brain-computer interface (BCI) application. To achieve this goal, we have applied a time-frequency synthesized spatial patterns (TFSP) BCI algorithm with a presorting procedure. Using this method, we were able to achieve an average recognition rate of 89% in four healthy subjects, which is comparable to the highest rates reported in the literature but now for tasks with much closer spatial representations on the motor cortex. This result demonstrates, for the first time, that the TFSP BCI method can be applied to separate intentions between generating static shoulder versus elbow torque. Furthermore, in this study, the potential application of this BCI algorithm for brain-injured patients was tested in one chronic hemiparetic stroke subject. A recognition rate of 76% was obtained, suggesting that this BCI method can provide a potential control signal for neural prostheses or other movement coordination improving devices for patients following brain injury.

  18. Study of the time-frequency characteristics of continuous gravity data sequence

    NASA Astrophysics Data System (ADS)

    Weimin, X.; Shi, C.; Lei, S.; Hongyan, L.

    2013-12-01

    The continuous gravity measurements contained much valuable signal which was maybe caused by internal and external change of the Earth, which offered abundant information to study activities of the Earth. In the past decades, researchers mostly focused on discussing the relationship between the gravity variation and geodynamical processes. Here we studied the temporal variation of the gravity field through the continuous gravity records. Our goal was to detect certain geophysical signal on the order of a few tens of micro-Gal from the gravity data sequence. The gravity data sequences were recorded by the Scintrex g-Phone relative gravimeters those were located at the numerous observation stations of mainland China which had well-controlled observation systems. We presented a two-step procedure to study the signal of gravity variation. Firstly, we developed a Linear Similarity filtering technique which could reduce the drift of gravity instrument effectively by using two relative gravimeters at the same station by the reason of the short-term liner drift feature of gravimeters. Based on the method above, we gained non-tidal gravity variation more accurate that contained much geophysical signal which was associated with geodynamical phenomena. Secondly, we employed the time-frequency analysis techniques to analyze the feature of different temporal variation signal and tried to find some periodic and non-periodic characteristics of the continuous gravity data sequence. Moreover, we compared the results to the mobile repeated gravity measurements on ground and acquired the spatial and temporal gravity variation at last. We also expected to find some anomaly signal related to the activities of tectogenesis and fault movement prior to the destructive earthquakes from the continuous gravity data sequence. Acknowledgment: We acknowledge the financial support of the Basic Scientific Research Foundation of Institute of Geophysics CEA (DQJB12B20, DQJB12C03 and DQJB12B14), the Scientific and Technological Support Foundation of CEA (2012BAK19B01-05-02) and the National Natural Science Foundation of China (41104046).

  19. Time-frequency analysis of non-stationary fusion plasma signals using an improved Hilbert-Huang transform

    SciTech Connect

    Liu, Yangqing, E-mail: liuyq05@gmail.com; Tan, Yi; Xie, Huiqiao; Wang, Wenhao; Gao, Zhe [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2014-07-15

    An improved Hilbert-Huang transform method is developed to the time-frequency analysis of non-stationary signals in tokamak plasmas. Maximal overlap discrete wavelet packet transform rather than wavelet packet transform is proposed as a preprocessor to decompose a signal into various narrow-band components. Then, a correlation coefficient based selection method is utilized to eliminate the irrelevant intrinsic mode functions obtained from empirical mode decomposition of those narrow-band components. Subsequently, a time varying vector autoregressive moving average model instead of Hilbert spectral analysis is performed to compute the Hilbert spectrum, i.e., a three-dimensional time-frequency distribution of the signal. The feasibility and effectiveness of the improved Hilbert-Huang transform method is demonstrated by analyzing a non-stationary simulated signal and actual experimental signals in fusion plasmas.

  20. Auditory morphing based on an elastic perceptual distance metric in an interference-free time-frequency representation

    Microsoft Academic Search

    Hideki Kawaharat; Hisami Matsui

    2003-01-01

    An elastic spectral distance measure based on a F0 adaptive pitch synchronous spectral estimation and selective elimination of periodicity interferences, that was developed for a high-quality speech modification procedure STRAIGHT [1], is introduced to provide a basis for auditory morphing. The proposed measure is implemented on a low dimensional piecewise bilinear time-frequency mapping between the target and the original speech

  1. Definitions of non-stationary vibration power for time-frequency analysis and computational algorithms based upon harmonic wavelet transform

    NASA Astrophysics Data System (ADS)

    Heo, YongHwa; Kim, Kwang-joon

    2015-02-01

    While the vibration power for a set of harmonic force and velocity signals is well defined and known, it is not as popular yet for a set of stationary random force and velocity processes, although it can be found in some literatures. In this paper, the definition of the vibration power for a set of non-stationary random force and velocity signals will be derived for the purpose of a time-frequency analysis based on the definitions of the vibration power for the harmonic and stationary random signals. The non-stationary vibration power, defined as the short-time average of the product of the force and velocity over a given frequency range of interest, can be calculated by three methods: the Wigner-Ville distribution, the short-time Fourier transform, and the harmonic wavelet transform. The latter method is selected in this paper because band-pass filtering can be done without phase distortions, and the frequency ranges can be chosen very flexibly for the time-frequency analysis. Three algorithms for the time-frequency analysis of the non-stationary vibration power using the harmonic wavelet transform are discussed. The first is an algorithm for computation according to the full definition, while the others are approximate. Noting that the force and velocity decomposed into frequency ranges of interest by the harmonic wavelet transform are constructed with coefficients and basis functions, for the second algorithm, it is suggested to prepare a table of time integrals of the product of the basis functions in advance, which are independent of the signals under analysis. How to prepare and utilize the integral table are presented. The third algorithm is based on an evolutionary spectrum. Applications of the algorithms to the time-frequency analysis of the vibration power transmitted from an excitation source to a receiver structure in a simple mechanical system consisting of a cantilever beam and a reaction wheel are presented for illustration.

  2. Performance of time-frequency representation techniques to measure blood flow turbulence with pulsed-wave Doppler ultrasound

    Microsoft Academic Search

    Guy Cloutier; Danmin Chen; Louis-Gilles Durand

    2001-01-01

    The current processing performed by commercial instruments to obtain the time-frequency representation (TFR) of pulsed-wave Doppler signals may not be adequate to characterize turbulent flow motions. The assessment of the intensity of turbulence is of high clinical importance and measuring high-frequency (small-scale) flow motions, using Doppler ultrasound (US), is a difficult problem that has been studied very little. The objective

  3. PERFORMANCE OF TIME-FREQUENCY REPRESENTATION TECHNIQUES TO MEASURE BLOOD FLOW TURBULENCE WITH PULSED-WAVE DOPPLER ULTRASOUND

    Microsoft Academic Search

    GUY CLOUTIER; DANMIN CHEN; LOUIS-GILLES DURAND

    2001-01-01

    The current processing performed by commercial instruments to obtain the time-frequency repre- sentation (TFR) of pulsed-wave Doppler signals may not be adequate to characterize turbulent flow motions. The assessment of the intensity of turbulence is of high clinical importance and measuring high-frequency (small- scale) flow motions, using Doppler ultrasound (US), is a difficult problem that has been studied very little.

  4. Joint Projects / Joint Seminars October 2013

    E-print Network

    Fuchs, Clemens

    Joint Projects / Joint Seminars October 2013 Information Sheet Bilateral Programs (MoU) ­ Joint Projects (JP) / Joint Seminars (JS) FWF has signed bilateral agreements ­ so called "Memorandums of Understanding" (MoU) ­ with several international partner organisations. These agreements usually aim at jointly

  5. Joint space and workspace analysis of a two-DOF closed-chain manipulator

    E-print Network

    Paris-Sud XI, Université de

    Joint space and workspace analysis of a two-DOF closed-chain manipulator Damien Chablat Institut de aspects, i.e. the maximal singularity-free domains in the Cartesian product of the joint space. These singular configu- rations divide the joint space and the workspace in several not connected domains

  6. Two-dimensional-vibrational spectroscopy: Development and testing of a two-dimensional ultrafast Raman spectrometer with Time-Frequency Detection

    NASA Astrophysics Data System (ADS)

    Urbanek, Diana Camila

    The major emphasis of this dissertation will be given toward the theoretical tools necessary to acquire high resolution femtosecond Raman spectra from broadband femtosecond pulses. The theory of simultaneous Time-Frequency Detection (TFD) will be discussed and demonstrated to be a robust technique to acquire the vibrational coherence information. Finally, two experimental cases that demonstrate the feasibility of femtosecond TFD-CARS for acetonitrile and nitrobenzene will be presented. In the introductory first chapter, the motivation and fundamentals for developing 2D-vibrational spectroscopy using femtosecond Raman detection is presented. For coherent Raman spectroscopies, common femtosecond pulses often lie in an intermediate regime: their bandwidth is too wide for measurements in the frequency domain, but their temporal width is too broad for homodyne measurements in the time domain. A recent paper [Phys. Rev. Lett. 97 , 267401 (2006)] showed that complete Raman spectra can be recovered from intermediate length pulses by using simultaneous time and frequency detection (TFD). Heterodyne detection and a phase-stable local oscillator at the anti-Stokes frequency are not needed with TFD. Phase-control, pulse shaping or pulses of widely differing duration are not required. To demonstrate the TFD method, a high resolution Raman spectrum of nitrobenzene obtained from 60 fs pulses is discussed theoretically and experimentally in the second chapter. In the third chapter model calculations illustrate how information on the Raman spectrum is smoothly transferred from the frequency domain to the time domain as the pulse width shortens. When data is collected in both dimensions, the Raman spectrum is completely determined to high resolution, regardless of the probe pulse width. The TFD method is tested on experimental CARS data from acetonitrile in the fourth chapter. Compared to theoretical models, experimental data are complicated by noise and incomplete knowledge of the pulse structure. Despite these complications, most of the information in the Raman spectrum is recovered from the data; weak transitions are detected and natural-linewidth resolution is achieved across an 800 cm-1 spectral range. However, circumstances in which experimental limitations result in missed features or ambiguities in the recovered spectrum are also identified. These results suggest where improvements in measurement and data analysis can be made.

  7. An improvement of mass estimation capability in loose parts monitoring by using time-frequency analysis

    SciTech Connect

    Yoon, D. B.; Park, J. H.; Choi, Y. C. [Dept. of Mechanical Engineering, KAERI, 150 Duckjin-dong, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of); Sohn, C. H. [Samchang Enterprise Co., Ltd., 168-9 Shinjung-dong, Nam-gu, Ulsan, 680-010 (Korea, Republic of); Park, O. K. [Yonggwang Nuclear Power Div., KHNP Co., Ltd., 514 Kyenm-ri Hongnong-eup, Yonggwang-gun, Jeonnam (Korea, Republic of)

    2006-07-01

    Two typical methods have been widely used for estimating an impact mass of loose parts. One is a center frequency method and the other is a FR (Frequency Ratio) method These techniques can be successfully applied when the signal has a high signal-to-noise ratio. Actually, the measured response signals obtained from the sensors contain a background noise, and reflected waves, etc. Therefore, in a noisy environment, the conventional methods using one dimensional power spectra may fail to estimate the impact mass. In order to enhance the mass estimation capability for a loose paris monitoring, a smoothed Wigner-Ville distribution is proposed. It uses an asymmetric window in the ambiguity function domain to effectively eliminate a noise component. Experiments were carried out to verify the validity of the proposed method. The results show that even in a noisy environment, the smoothed Wigner-Ville distribution can provide a more reliable means for estimating the impact mass. It is expected that the proposed method can be used to enhance the accuracy of the mass estimation for loose parts. (authors)

  8. The Time-Frequency Signatures of Advanced Seismic Signals Generated by Debris Flows

    NASA Astrophysics Data System (ADS)

    Chu, C. R.; Huang, C. J.; Lin, C. R.; Wang, C. C.; Kuo, B. Y.; Yin, H. Y.

    2014-12-01

    The seismic monitoring is expected to reveal the process of debris flow from the initial area to alluvial fan, because other field monitoring techniques, such as the video camera and the ultrasonic sensor, are limited by detection range. For this reason, seismic approaches have been used as the detection system of debris flows over the past few decades. The analysis of the signatures of the seismic signals in time and frequency domain can be used to identify the different phases of debris flow. This study dedicates to investigate the different stages of seismic signals due to debris flow, including the advanced signal, the main front, and the decaying tail. Moreover, the characteristics of the advanced signals forward to the approach of main front were discussed for the warning purpose. This study presents a permanent system, composed by two seismometers, deployed along the bank of Ai-Yu-Zi Creek in Nantou County, which is one of the active streams with debris flow in Taiwan. The three axes seismometer with frequency response of 7 sec - 200 Hz was developed by the Institute of Earth Sciences (IES), Academia Sinica for the purpose to detect debris flow. The original idea of replacing the geophone system with the seismometer technique was for catching the advanced signals propagating from the upper reach of the stream before debris flow arrival because of the high sensitivity. Besides, the low frequency seismic waves could be also early detected because of the low attenuation. However, for avoiding other unnecessary ambient vibrations, the sensitivity of seismometer should be lower than the general seismometer for detecting teleseism. Three debris flows with different mean velocities were detected in 2013 and 2014. The typical triangular shape was obviously demonstrated in time series data and the spectrograms of the seismic signals from three events. The frequency analysis showed that enormous debris flow bearing huge boulders would induce low frequency seismic waves. Owing to the less attenuation of low frequency waves, advanced signals mainly ranged between 2 and 10 Hz were detected in several minutes prior to the arrival of the main surge of a debris flow. As the results, the prior time of the advanced signals could be used not only to extend the warning time, but also to identify the initial location of a developing debris flow.

  9. Joint assembly

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2010-01-01

    A joint assembly is provided which includes a drive assembly and a swivel mechanism. The drive assembly features a motor operatively associated with a plurality of drive shafts for driving auxiliary elements, and a plurality of swivel shafts for pivoting the drive assembly. The swivel mechanism engages the swivel shafts and has a fixable element that may be attached to a foundation. The swivel mechanism is adapted to cooperate with the swivel shafts to pivot the drive assembly with at least two degrees of freedom relative to the foundation. The joint assembly allows for all components to remain encased in a tight, compact, and sealed package, making it ideal for space, exploratory, and commercial applications.

  10. A new time-frequency method to reveal quatum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform

    E-print Network

    Sheu, Yae-lin; Hsu, Liang-Yan; Wu, Hau-tieng; Li, Peng-Cheng; Chu, Shih-I

    2014-11-26

    ? d?, (5) where ?,? > 0, h(t) = 1? ? e?t 2 and A?, f (t) ? #8; ? ? R+ : #14; Vf (t, ?) #14; > ? . Note that the threshold ? is to avoid numerical instability when computing Eq. (4). ? also serves as a threshold when noise exists.26 The main idea...AIP ADVANCES 4, 117138 (2014) A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform Yae-lin Sheu,1 Liang-Yan Hsu,2,a Hau-tieng Wu,3,b Peng-Cheng Li,1,4 and Shih-I Chu1,5,c 1...

  11. Under-Determined Reverberant Audio Source Separation Using Local Observed Covariance and Auditory-Motivated Time-Frequency Representation

    Microsoft Academic Search

    Ngoc Q. K. Duong; Emmanuel Vincent; Rémi Gribonval

    2010-01-01

    \\u000a We consider the local Gaussian modeling framework for under-determined convolutive audio source separation, where the spatial\\u000a image of each source is modeled as a zero-mean Gaussian variable with full-rank time- and frequency-dependent covariance.\\u000a We investigate two methods to improve the accuracy of parameter estimation, based on the use of local observed covariance\\u000a and auditory-motivated time-frequency representation. We derive an iterative

  12. WW domains

    Microsoft Academic Search

    Olivier Staub; Daniela Rotin

    1996-01-01

    WW domains are recently described protein–protein interaction modules; they bind to proline-rich sequences that usually also contain a tyrosine. These domains have been detected in several unrelated proteins, often alongside other domains. Recent studies suggest that WW domains in specific proteins may play a role in diseases such as hypertension or muscular dystrophy.

  13. A novel approach to predict sudden cardiac death (SCD) using nonlinear and time-frequency analyses from HRV signals.

    PubMed

    Ebrahimzadeh, Elias; Pooyan, Mohammad; Bijar, Ahmad

    2014-01-01

    Investigations show that millions of people all around the world die as the result of sudden cardiac death (SCD). These deaths can be reduced by using medical equipment, such as defibrillators, after detection. We need to propose suitable ways to assist doctors to predict sudden cardiac death with a high level of accuracy. To do this, Linear, Time-Frequency (TF) and Nonlinear features have been extracted from HRV of ECG signal. Finally, healthy people and people at risk of SCD are classified by k-Nearest Neighbor (k-NN) and Multilayer Perceptron Neural Network (MLP). To evaluate, we have compared the classification rates for both separate and combined Nonlinear and TF features. The results show that HRV signals have special features in the vicinity of the occurrence of SCD that have the ability to distinguish between patients prone to SCD and normal people. We found that the combination of Time-Frequency and Nonlinear features have a better ability to achieve higher accuracy. The experimental results show that the combination of features can predict SCD by the accuracy of 99.73%, 96.52%, 90.37% and 83.96% for the first, second, third and forth one-minute intervals, respectively, before SCD occurrence. PMID:24504331

  14. Joint Commission on rock properties

    NASA Astrophysics Data System (ADS)

    A joint commission on Rock Properties for Petroleum Engineers (RPPE) has been established by the International Society of Rock Mechanics and the Society of Petroleum Engineers to set up data banks on the properties of sedimentary rocks encountered during drilling. Computer-based data banks of complete rock properties will be organized for sandstones (GRESA), shales (ARSHA) and carbonates (CARCA). The commission hopes to access data sources from members of the commission, private companies and the public domain.

  15. TIME-FREQUENCY ANALYSIS OF THE SUPERORBITAL MODULATION OF THE X-RAY BINARY SMC X-1 USING THE HILBERT-HUANG TRANSFORM

    SciTech Connect

    Hu, Chin-Ping; Chou, Yi; Yang, Ting-Chang; Su, Yi-Hao [Graduate Institute of Astronomy, National Central University, Jhongli 32001, Taiwan (China); Wu, Ming-Chya, E-mail: m929011@astro.ncu.edu.tw, E-mail: yichou@astro.ncu.edu.tw [Research Center for Adaptive Data Analysis, National Central University, Jhongli 32001, Taiwan (China)

    2011-10-20

    The high-mass X-ray binary SMC X-1 exhibits a superorbital modulation with a dramatically varying period ranging between {approx}40 days and {approx}60 days. This research studies the time-frequency properties of the superorbital modulation of SMC X-1 based on the observations made by the All-Sky Monitor (ASM) onboard the Rossi X-ray Timing Explorer (RXTE). We analyzed the entire ASM database collected since 1996. The Hilbert-Huang transform (HHT), developed for non-stationary and nonlinear time-series analysis, was adopted to derive the instantaneous superorbital frequency. The resultant Hilbert spectrum is consistent with the dynamic power spectrum as it shows more detailed information in both the time and frequency domains. The RXTE observations show that the superorbital modulation period was mostly between {approx}50 days and {approx}65 days, whereas it changed to {approx}45 days around MJD 50,800 and MJD 54,000. Our analysis further indicates that the instantaneous frequency changed to a timescale of hundreds of days between {approx}MJD 51,500 and {approx}MJD 53,500. Based on the instantaneous phase defined by HHT, we folded the ASM light curve to derive a superorbital profile, from which an asymmetric feature and a low state with barely any X-ray emissions (lasting for {approx}0.3 cycles) were observed. We also calculated the correlation between the mean period and the amplitude of the superorbital modulation. The result is similar to the recently discovered relationship between the superorbital cycle length and the mean X-ray flux for Her X-1.

  16. The hyperbolic class of quadratic time-frequency representations. II. Subclasses, intersection with the affine and power classes, regularity, and unitarity

    Microsoft Academic Search

    Franz Hlawatsch; Antonia Papandreou-Suppappola; G. Faye Boudreaux-Bartels

    1997-01-01

    For pt.I see ibid., vol.41, p.3425-444 (1993). Part I introduced the hyperbolic class (HC) of quadratic\\/bilinear time-frequency representations (QTFRs). The present paper defines and studies four subclasses of the HC: (1) The focalized-kernel subclass of the HC is related to a time-frequency concentration property of QTFRs. It is analogous to the localized-kernel subclass of the affine QTFR class. (2) The

  17. Stochastic simulation of human pulmonary blood flow and transit time frequency distribution based on anatomic and elasticity data.

    PubMed

    Huang, Wei; Shi, Jun; Yen, R T

    2012-12-01

    The objective of our study was to develop a computing program for computing the transit time frequency distributions of red blood cell in human pulmonary circulation, based on our anatomic and elasticity data of blood vessels in human lung. A stochastic simulation model was introduced to simulate blood flow in human pulmonary circulation. In the stochastic simulation model, the connectivity data of pulmonary blood vessels in human lung was converted into a probability matrix. Based on this model, the transit time of red blood cell in human pulmonary circulation and the output blood pressure were studied. Additionally, the stochastic simulation model can be used to predict the changes of blood flow in human pulmonary circulation with the advantage of the lower computing cost and the higher flexibility. In conclusion, a stochastic simulation approach was introduced to simulate the blood flow in the hierarchical structure of a pulmonary circulation system, and to calculate the transit time distributions and the blood pressure outputs. PMID:23724431

  18. High-order harmonic generation by chirped and self-guided femtosecond laser pulses. II. Time-frequency analysis

    SciTech Connect

    Tosa, V. [Department of Physics, KAIST, Yuseong-gu, Daejeon, 305-701 (Korea, Republic of); National Institute for R and D of Isotopic and Molecular Technologies, Cluj-Napoca (Romania); Kim, H.T.; Kim, I.J.; Nam, C.H. [Department of Physics, KAIST, Yuseong-gu, Daejeon, 305-701(Korea, Republic of)

    2005-06-15

    We present a time-dependent analysis of high-order harmonics generated by a self-guided femtosecond laser pulse propagating through a long gas jet. A three-dimensional model is used to calculate the harmonic fields generated by laser pulses, which only differ by the sign of their initial chirp. The time-frequency distributions of the single-atom dipole and harmonic field reveal the dynamics of harmonic generation in the cutoff. A time-dependent phase-matching calculation was performed, taking into account the self-phase modulation of the laser field. Good phase matching holds for only few optical cycles, being dependent on the electron trajectory. When the cutoff trajectory is phase matched, emitted harmonics are locked in phase and the emission intensity is maximized.

  19. Set Domains

    Microsoft Academic Search

    Reinhold Heckmann; Bundesrepublik Deutschland

    1990-01-01

    Set domains are intended to give semantics to a data type of sets together with a wide range ofuseful set operations. The classical power domain constructions are shown to be inappropriatefor this purpose. Lower and upper domain do not support quantification, whereas Plotkin'sdomain does not contain the empty set. This is an immense defect, since the empty set is notonly

  20. Joint x-ray

    MedlinePLUS

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  1. Joint Aspiration (Arthrocentesis)

    MedlinePLUS

    ... the joint. It is usually due to a bacterial infection in the joint. Joint aspiration helps to diagnose ... at the time of the test. If a bacterial infection such as septic arthritis is suspected, a culture ...

  2. Joint Instability and Osteoarthritis

    PubMed Central

    Blalock, Darryl; Miller, Andrew; Tilley, Michael; Wang, Jinxi

    2015-01-01

    Joint instability creates a clinical and economic burden in the health care system. Injuries and disorders that directly damage the joint structure or lead to joint instability are highly associated with osteoarthritis (OA). Thus, understanding the physiology of joint stability and the mechanisms of joint instability-induced OA is of clinical significance. The first section of this review discusses the structure and function of major joint tissues, including periarticular muscles, which play a significant role in joint stability. Because the knee, ankle, and shoulder joints demonstrate a high incidence of ligament injury and joint instability, the second section summarizes the mechanisms of ligament injury-associated joint instability of these joints. The final section highlights the recent advances in the understanding of the mechanical and biological mechanisms of joint instability-induced OA. These advances may lead to new opportunities for clinical intervention in the prevention and early treatment of OA. PMID:25741184

  3. Joint services electronics program

    NASA Astrophysics Data System (ADS)

    Peters, Leon, Jr.

    1992-11-01

    The report represents the fifteenth annual summary of The Ohio State University Joint Services Electronics Program (JSEP). The transfer of the compact range identification technology initiated under JSEP support for time domain studies continues to make large advances. We are also assisting Rockwell (Tulsa) to update their RCS facilities. This work is on a subcontract to the ESL from the Air Force. This has lead to involvement in the study of Ultra Wide Band radar systems. The research activities devoted to the Generalized Ray and Gaussian Beams continues. Our JSEP research continues to be expanded by external funding. This program is being expanded by use of such funds which are more focussed on the requirements of the sponsors which includes both the Air Force and the Navy. Our JSEP research continues to focus on electromagnetic related topics. There are four major electromagnetics areas that were pursued in the past year. The Diffraction Studies Work Unit has initiated research on a time domain version of the Uniform Theory of Diffraction. A second topic under the Diffraction Studies Work Unit involves further extensions of the generalized resistive boundary condition and the generalized impedance boundary condition. These have been applied to scattering from a chiral slab. A third topic of interest is the diffraction from a corner. A fourth task involves the reflection/diffraction of a Gaussian beam. This represents an approach to replace the usual ray optics solution for very complex geometries where the versatile ray optics solution becomes cumbersome.

  4. 2066 IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 55, NO. 5, MAY 2007 Discrete Time-Frequency Characterizations of

    E-print Network

    Nehorai, Arye

    discrete characterization, we investigate acoustic transmission over shallow water environments numerical results, we demonstrate that the discrete dispersive model can lead to a joint multi- path-dispersion diversity that we achieve by properly designing the transmitted waveform and the reception scheme to match

  5. Wavelets, period-doubling, and time-frequency localization with application to organization of convection over the tropical western Pacific

    NASA Technical Reports Server (NTRS)

    Weng, Hengyi; Lau, K.-M.

    1994-01-01

    In this paper, preliminary results in using orthogonal and continuous wavelet transform (WT) to identify period doubling and time-frequency localization in both synthetic and real data are presented. First, the Haar WT is applied to synthetic time series derived from a simple nonlinear dynamical system- a first-order quadratic difference equation. Second, the complex Morlet WT is used to study the time-frequency localization of tropical convection based on a high-resolution Japanese Geostationary Meteorological Satellite infrared (IR) radiance dataset. The Haar WT of the synthetic time series indicates the presence and distinct separation of multiple frequencies in a period-doubling sequence. The period-doubling process generates a multiplicity of intermediate frequencies, which are manifested in the nonuniformity in time with respect to the phase of oscillations in the lower frequencies. Wavelet transform also enables the detection of extremely weak signals in high-order subharmonics resulting from the period-doubling bifurcations. These signals are either undetected or considered statistically insignificant by traditional Fourier analysis. The Morlet WT of the IR radiance dataset indicates the presence of multiple timescales, which are localized in both frequency and time. There are two regimes in the variation of IR radiance, corresponding to the wet and dry periods. Multiple timescales, ranging from semidiurnal, diurnal, synoptic, to intraseasonal with embedding structures, are active in the wet regime. In particular, synoptic variability is more prominent during the wet phase of an intensive intraseasonal cycle. These are not only consistent with, but also show more details than, previous findings by using other techniques. The phase-locking relationships among the oscillations with different time-scales suggest that both synoptic and intraseasonal variations may be mixed oscillations due to the interaction of self-excited oscillations in the tropical atmosphere and external forcings such as annual and diurnal solar radiation variations. Both examples show that WT is a powerful tool for analysis of phenomena involving multiscale interactions that exhibit localization in both frequency and time. A discussion on the caveats in the use of WT in geophysical data analysis is also presented.

  6. Localizations of the derived category of a valuation domain

    E-print Network

    Localizations of the derived category of a valuation domain Jan St'ovícek (joint with Pavel Príhoda St'ovícek (Charles University) Localizations, valuation domains May 18, 2012 1 / 22 #12;Outline 1 Valuation domains 2 A hierarchy of triangulated localizations 3 Examples 4 About the proof Jan St

  7. The joint intersection probability

    Microsoft Academic Search

    Y. H. Hatzor; A. Feintuch

    2005-01-01

    In this paper a practical method to apply block theory is presented. Block theory provides the removable joint pyramids from a given free surface regardless of the number of joints in any joint intersection. While robust, the application of the theory in real practice is hampered by the large outcome space of possibly removable joint pyramids consisting of k mutually

  8. T wave alternans evaluation using adaptive time-frequency signal analysis and non-negative matrix factorization.

    PubMed

    Ghoraani, Behnaz; Krishnan, Sridhar; Selvaraj, Raja J; Chauhan, Vijay S

    2011-07-01

    Each year 400,000 North Americans die from sudden cardiac death (SCD). Identifying those patients at risk of SCD remains a formidable challenge. T wave alternans (TWA) evaluation is emerging as an important tool to risk stratify patients with heart diseases. TWA is a heart rate dependent phenomenon that manifests on the surface electrocardiogram (ECG) as a change in the shape or amplitude of the T wave every second heart beat. The presence of large magnitude TWA often presages lethal ventricular arrhythmias. Because the TWA signal is typically in the microvolt range, accurate detection algorithms are required to control for confounding noise and changing physiological conditions (i.e. data nonstationarity). In this study, we address the limitations of two common TWA estimation methods, spectral method (SM) and modified moving average (MMA). To overcome their limitations, we propose a modified TWA quantification framework, called Adaptive SM, that uses non-linear time-frequency distribution (TFD). In order to increase the robustness of TWA detection in ambulatory ECGs, we also propose a new technique, called non-negative matrix factorization (NMF)-Adaptive SM. We present the analytical background of these methods, and evaluate their accuracy in detecting synthetic TWA signal in simulated and real-world ambulatory ECG recordings under conditions of noise and data non-stationarity. The results of the numerical simulations support the effectiveness of the proposed approaches for TWA analysis, which may ultimately improve SCD risk assessment. PMID:21333581

  9. Time-frequency analysis of heart rate variability during the cold pressor test using a time-varying autoregressive model.

    PubMed

    Peng, Rong-Chao; Yan, Wen-Rong; Zhou, Xiao-Lin; Zhang, Ning-Ling; Lin, Wan-Hua; Zhang, Yuan-Ting

    2015-03-01

    Heart rate variability is a useful clinical tool for autonomic function assessment and cardiovascular disease diagnosis. To investigate the dynamic changes of sympathetic and parasympathetic activities during the cold pressor test, we used a time-varying autoregressive model for the time-frequency analysis of heart rate variability in 101 healthy subjects. We found that there were two sympathetic peaks (or two parasympathetic valleys) when the abrupt changes of temperature (ACT) occurred at the beginning and the end of the cold stimulus and that the sympathetic and parasympathetic activities returned to normal in about the last 2?min of the cold stimulus. These findings suggested that the ACT rather than the low temperature was the major cause of the sympathetic excitation and parasympathetic withdrawal. We also found that the onsets of the sympathetic peaks were 4-26?s prior to the ACT and the returns to normal were 54-57?s after the ACT, which could be interpreted as the feedforward and adaptation of the autonomic regulation process in the human body, respectively. These results might be helpful for understanding the regulatory mechanisms of the autonomic system and its effects on the cardiovascular system. PMID:25656926

  10. Brain dynamics in the comprehension of action-related language. A time-frequency analysis of mu rhythms.

    PubMed

    Moreno, Iván; de Vega, Manuel; León, Inmaculada; Bastiaansen, Marcel; Glen Lewis, Ashley; Magyari, Lilla

    2015-04-01

    EEG mu rhythms (8-13 Hz) recorded at fronto-central electrodes are generally considered as markers of motor cortical activity in humans, because they are modulated when participants perform an action, when they observe another's action or even when they imagine performing an action. In this study, we analyzed the time-frequency (TF) modulation of mu rhythms while participants read action language ("You will cut the strawberry cake"), abstract language ("You will doubt the patient's argument"), and perceptive language ("You will notice the bright day"). The results indicated that mu suppression at fronto-central sites is associated with action language rather than with abstract or perceptive language. Also, the largest difference between conditions occurred quite late in the sentence, while reading the first noun, (contrast Action vs. Abstract), or the second noun following the action verb (contrast Action vs. Perceptive). This suggests that motor activation is associated with the integration of words across the sentence beyond the lexical processing of the action verb. Source reconstruction localized mu suppression associated with action sentences in premotor cortex (BA 6). The present study suggests (1) that the understanding of action language activates motor networks in the human brain, and (2) that this activation occurs online based on semantic integration across multiple words in the sentence. PMID:25583610

  11. Time-frequency characteristics and dynamics of sleep spindles in WAG/Rij rats with absence epilepsy.

    PubMed

    Sitnikova, Evgenia; Hramov, Alexander E; Grubov, Vadim; Koronovsky, Alexey A

    2014-01-16

    In rat models of absence epilepsy, epileptic spike-wave discharges appeared in EEG spontaneously, and the incidence of epileptic activity increases with age. Spike-wave discharges and sleep spindles are known to share common thalamo-cortical mechanism, suggesting that absence seizures might affect some intrinsic properties of sleep spindles. This paper examines time-frequency EEG characteristics of anterior sleep spindles in non-epileptic Wistar and epileptic WAG/Rij rats at the age of 7 and 9 months. Considering non-stationary features of sleep spindles, EEG analysis was performed using Morlet-based continuous wavelet transform. It was found, first, that the average frequency of sleep spindles in non-epileptic Wistar rats was higher than in WAG/Rij (13.2 vs 11.2 Hz). Second, the instantaneous frequency ascended during a spindle event in Wistar rats, but it was constant in WAG/Rij. Third, in WAG/Rij rats, the number and duration of epileptic discharges increased in a period between 7 and 9 months of age, but duration and mean value of intra-spindle frequency did not change. In general, age-dependent aggravation of absence seizures in WAG/Rij rats did not affect EEG properties of sleep spindles; it was suggested that pro-epileptic changes in thalamo-cortical network in WAG/Rij rats might prevent dynamic changes of sleep spindles that were detected in Wistar. PMID:24231550

  12. Phase information of time-frequency transforms as a key feature for classification of atrial fibrillation episodes.

    PubMed

    Ortigosa, Nuria; Fernández, Carmen; Galbis, Antonio; Cano, Óscar

    2015-03-01

    Patients suffering from atrial fibrillation can be classified into different subtypes, according to the temporal pattern of the arrhythmia and its recurrence. Nowadays, clinicians cannot differentiate a priori between the different subtypes, and patient classification is done afterwards, when its clinical course is available. In this paper we present a comparison of classification performances when differentiating paroxysmal and persistent atrial fibrillation episodes by means of support vector machines. We analyze short surface electrocardiogram recordings by extracting modulus and phase features from several time-frequency transforms: short-time Fourier transform, Wigner-Ville, Choi-Williams, Stockwell transform, and general Fourier-family transform. Overall, accuracy higher than 81% is obtained when classifying phase information features of real test ECGs from a heterogeneous cohort of patients (in terms of progression of the arrhythmia and antiarrhythmic treatment) recorded in a tertiary center. Therefore, phase features can facilitate the clinicians' choice of the most appropriate treatment for each patient by means of a non-invasive technique (the surface ECG). PMID:25652101

  13. Timing, Frequency and Environmental Conditions Associated with Mainstem–Tributary Movement by a Lowland River Fish, Golden Perch (Macquaria ambigua)

    PubMed Central

    Koster, Wayne M.; Dawson, David R.; O’Mahony, Damien J.; Moloney, Paul D.; Crook, David A.

    2014-01-01

    Tributary and mainstem connections represent important links for the movement of fish and other biota throughout river networks. We investigated the timing, frequency and environmental conditions associated with movements by adult golden perch (Macquaria ambigua) between the mainstem of the mid-Murray River and a tributary, the Goulburn River, in south-eastern Australia, using acoustic telemetry over four years (2007–2011). Fish were tagged and released in autumn 2007–2009 in the mid-Murray (n?=?42) and lower Goulburn (n?=?37) rivers within 3–6 km of the mid-Murray-lower Goulburn junction. 38% of tagged fish undertook mainstem–tributary movements, characterised mostly by temporary occupation followed by return of fish to the original capture river. Approximately 10% of tagged fish exhibited longer-term shifts between the mainstem and tributary. Movement of fish from the tributary into the mainstem occurred primarily during the spawning season and in some years coincided with the presence of golden perch eggs/larvae in drift samples in the mainstem. Many of the tributary-to-mainstem movements occurred during or soon after changes in flow. The movements of fish from the mainstem into the tributary were irregular and did not appear to be associated with spawning. The findings show that golden perch moved freely across the mainstem–tributary interface. This demonstrates the need to consider the spatial, behavioural and demographic interdependencies of aquatic fauna across geographic management units such as rivers. PMID:24788137

  14. Individual time-dependent spectral boundaries for improved accuracy in time-frequency analysis of heart rate variability.

    PubMed

    Goren, Yael; Davrath, Linda R; Pinhas, Itzhak; Toledo, Eran; Akselrod, Solange

    2006-01-01

    Heart rate variability (HRV) is a major noninvasive technique for evaluating the autonomic nervous system (ANS). Use of time-frequency approach to analyze HRV allows investigating the ANS behavior from the power integrals, as a function of time, in both steady-state and non steady-state. Power integrals are examined mainly in the low-frequency and the high-frequency bands. Traditionally, constant boundaries are chosen to determine the frequency bands of interest. However, these ranges are individual, and can be strongly affected by physiologic conditions (body position, breathing frequency). In order to determine the dynamic boundaries of the frequency bands more accurately, especially during autonomic challenges, we developed an algorithm for the detection of individual time-dependent spectral boundaries (ITSB). The ITSB was tested on recordings from a series of standard autonomic maneuvers with rest periods between them, and the response to stand was compared to the known physiological response. A major advantage of the ITSB is the ability to reliably define the mid-frequency range, which provides the potential to investigate the physiologic importance of this range. PMID:16402601

  15. Recognition of speech in noise after application of time-frequency masks: Dependence on frequency and threshold parameters

    PubMed Central

    Sinex, Donal G.

    2013-01-01

    Binary time-frequency (TF) masks can be applied to separate speech from noise. Previous studies have shown that with appropriate parameters, ideal TF masks can extract highly intelligible speech even at very low speech-to-noise ratios (SNRs). Two psychophysical experiments provided additional information about the dependence of intelligibility on the frequency resolution and threshold criteria that define the ideal TF mask. Listeners identified AzBio Sentences in noise, before and after application of TF masks. Masks generated with 8 or 16 frequency bands per octave supported nearly-perfect identification. Word recognition accuracy was slightly lower and more variable with 4 bands per octave. When TF masks were generated with a local threshold criterion of 0?dB SNR, the mean speech reception threshold was ?9.5?dB SNR, compared to ?5.7?dB for unprocessed sentences in noise. Speech reception thresholds decreased by about 1?dB per dB of additional decrease in the local threshold criterion. Information reported here about the dependence of speech intelligibility on frequency and level parameters has relevance for the development of non-ideal TF masks for clinical applications such as speech processing for hearing aids. PMID:23556604

  16. Temporal Features of Spike Trains in the Moth Antennal Lobe Revealed by a Comparative Time-Frequency Analysis

    PubMed Central

    Capurro, Alberto; Baroni, Fabiano; Kuebler, Linda S.; Kárpáti, Zsolt; Dekker, Teun; Lei, Hong; Hansson, Bill S.; Pearce, Timothy C.; Olsson, Shannon B.

    2014-01-01

    The discrimination of complex sensory stimuli in a noisy environment is an immense computational task. Sensory systems often encode stimulus features in a spatiotemporal fashion through the complex firing patterns of individual neurons. To identify these temporal features, we have developed an analysis that allows the comparison of statistically significant features of spike trains localized over multiple scales of time-frequency resolution. Our approach provides an original way to utilize the discrete wavelet transform to process instantaneous rate functions derived from spike trains, and select relevant wavelet coefficients through statistical analysis. Our method uncovered localized features within olfactory projection neuron (PN) responses in the moth antennal lobe coding for the presence of an odor mixture and the concentration of single component odorants, but not for compound identities. We found that odor mixtures evoked earlier responses in biphasic response type PNs compared to single components, which led to differences in the instantaneous firing rate functions with their signal power spread across multiple frequency bands (ranging from 0 to 45.71 Hz) during a time window immediately preceding behavioral response latencies observed in insects. Odor concentrations were coded in excited response type PNs both in low frequency band differences (2.86 to 5.71 Hz) during the stimulus and in the odor trace after stimulus offset in low (0 to 2.86 Hz) and high (22.86 to 45.71 Hz) frequency bands. These high frequency differences in both types of PNs could have particular relevance for recruiting cellular activity in higher brain centers such as mushroom body Kenyon cells. In contrast, neurons in the specialized pheromone-responsive area of the moth antennal lobe exhibited few stimulus-dependent differences in temporal response features. These results provide interesting insights on early insect olfactory processing and introduce a novel comparative approach for spike train analysis applicable to a variety of neuronal data sets. PMID:24465391

  17. Rate-Distortion Allocation for Time-Frequency Dependent Audio Coding Ricky Der1 Peter Kabal1 Wai-Yip Chan2

    E-print Network

    Kabal, Peter

    into over- lapping frames, and a linear transform is applied to give a time- frequency representation of the signal. For each frame, a set of quantizers q = {qi} acting upon transform coefficients x = {xi a standard transform audio coder, operating in the con- strained distortion mode. An input file is segmented

  18. Interval Polyhedra Domain Applications

    E-print Network

    Miné, Antoine

    Motivation Interval Polyhedra Domain Applications Interval Polyhedra: An Abstract Domain to Infer. Cousot The Interval Polyhedra Abstract Domain p. 1 / 25 #12;Motivation Interval Polyhedra Domain Applications Overview Motivation Interval polyhedra domain Applications of interval polyhedra domain Conclusion

  19. Towards achieving cross domain information sharing in a SOA-enabled environment using MILS and MLS technologies

    Microsoft Academic Search

    L. Sauer; M. Maschino; J. Morrow; M. Mayhew

    2009-01-01

    Many Programs of Record are using Service Oriented Architecture (SOA) approaches and supporting technologies to realize net-centricity requirements. Furthermore, emerging solutions offer data sharing across adjacent security enclaves for these programs, including Cross Domain Joint Battlespace Infosphere (XJBI) by AFRL, Cross Domain Web Services Gateway by DISA, and the Cross Domain Collaborative Information Environment and Collaboration Gateway by the Joint

  20. Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Arch & Chord Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie & Diagonal Brace Joint Detail; Chord, Panel Post, Tie & Crossbracing Joint Detail - Dunlapsville Covered Bridge, Spanning East Fork Whitewater River, Dunlapsville, Union County, IN

  1. Temporomandibular Joint Dysfunction

    MedlinePLUS

    The temporomandibular joint (TMJ) connects your jaw to the side of your head. When it works well, it enables you to ... For people with TMJ dysfunction, problems with the joint and muscles around it may cause Pain that ...

  2. Fractional Fourier domain communication system: System structure and signal modeling

    Microsoft Academic Search

    Yonggang Chi; Shengyu Zhang; Jun Shi

    2011-01-01

    In Transform Domain Communication System (TDCS), the traditional methods of spectrum sensing and interference mitigation have some unavoidable shortcomings in the non-stationary scenarios. On this consideration, fractional Fourier transform is introduced into TDCS to obtain a better performance in processing the non-stationary signals, like linear chirp signals. By rotating a certain angle in time-frequency plane, chirp signal will concentrate in

  3. Sacroiliac joint pain - aftercare

    MedlinePLUS

    The sacroiliac joint (SIJ) is a term used to describe the place where the sacrum and the iliac bones join. The ... The main purpose of the joint is to connect the spine and the pelvis. As a result, there is very little movement at the sacroiliac joint. Listed ...

  4. Stochastic Chemical Reactions in Micro-domains

    Microsoft Academic Search

    D. Holcman; Z. Schuss

    2004-01-01

    Traditional chemical kinetics may be inappropriate to describe chemical\\u000areactions in micro-domains involving only a small number of substrate and\\u000areactant molecules. Starting with the stochastic dynamics of the molecules, we\\u000aderive a master-diffusion equation for the joint probability density of a\\u000amobile reactant and the number of bound substrate in a confined domain. We use\\u000athe equation to calculate

  5. Identification of post-myocardial infarction patients prone to ventricular tachycardia using time–frequency analysis of QRS and ST segments

    Microsoft Academic Search

    J.-P. Couderc; P. Chevalier; J. Fayn; P. Rubel; P. Touboul

    2000-01-01

    Background Late potentials (LPs) in the terminal portion of the QRS complex are commonly sought to identify post-myocardial infarction patients prone to ventricular tachyarrthythmias (VT) or sudden death. More recent time–frequency signal processing tools have been shown to provide new parameters for the quantification of LPs and abnormal activities buried within the QRS complex.Methods and Results The study population comprised

  6. Development of a time–frequency approach to quantify railroad ballast fouling condition using ultra-wide band ground-penetrating radar data

    Microsoft Academic Search

    Imad L. Al-Qadi; Wei Xie; Douglas L. Jones; Roger Roberts

    2010-01-01

    This paper discusses the use of ground-penetrating radar (GPR) to assess railroad track substructure conditions. An ultra-wide band (UWB) GPR system, having a centre frequency at or higher than 2 GHz, can be used to detect the scattering pattern and to predict air void volume in railroad ballast. A time–frequency technique was implemented to characterise the signal in time and frequency

  7. A methodology for time-frequency image processing applied to the classification of non-stationary multichannel signals using instantaneous frequency descriptors with application to newborn EEG signals

    NASA Astrophysics Data System (ADS)

    Boashash, Boualem; Boubchir, Larbi; Azemi, Ghasem

    2012-12-01

    This article presents a general methodology for processing non-stationary signals for the purpose of classification and localization. The methodology combines methods adapted from three complementary areas: time-frequency signal analysis, multichannel signal analysis and image processing. The latter three combine in a new methodology referred to as multichannel time-frequency image processing which is applied to the problem of classifying electroencephalogram (EEG) abnormalities in both adults and newborns. A combination of signal related features and image related features are used by merging key instantaneous frequency descriptors which characterize the signal non-stationarities. The results obtained show that, firstly, the features based on time-frequency image processing techniques such as image segmentation, improve the performance of EEG abnormalities detection in the classification systems based on multi-SVM and neural network classifiers. Secondly, these discriminating features are able to better detect the correlation between newborn EEG signals in a multichannel-based newborn EEG seizure detection for the purpose of localizing EEG abnormalities on the scalp.

  8. New matrix decomposition based on transforming the basis sets of the singular value decomposition yields principal features for time-frequency distributions

    NASA Astrophysics Data System (ADS)

    Groutage, Dale; Bennink, David

    2000-11-01

    We present a matrix decomposition that can be used to derive features from processes that are described by discrete-time, time- frequency representations. These include, among others, electrocardiograms, brain wave signals, seismic signals, vibration and shock signals, speech signals for voice recognition, and acoustic transient signals. The new decomposition is based on a transformation of the basis vectors of the singular value decomposition (SVD) which we call transformed singular value decomposition or TSVD. The transformed basis vectors are obtained by forming linear combinations of the original SVD basis vectors in a way such that the means of the transformed vectors are extrema of each other. The TSVD basis vectors are used to identify concentrations of energy density in the discrete-time, time- frequency representation by time and frequency descriptors. That is, descriptors such as the location in time, the spread in time, the location in frequency and the spread in frequency for each principal concentration of energy density can be obtained from the TSVD terms in the matrix decomposition series. Several examples are presented which illustrate the application of the new matrix decomposition for deriving principal time and frequency features from the discrete-time, time-frequency representations of nonstationary processes. Two of the examples illustrate how the derived time and frequency features can be used to classify individual short duration transient signals into respective classes, that is,: (1) automatically classify sonar signals as belonging to one of ten classes, and (2) automatically classify heartbeat signals as belonging to one of two people.

  9. Anomaly detection in the maritime domain

    Microsoft Academic Search

    Jean Roy

    2008-01-01

    Defence R&D Canada is developing a Collaborative Knowledge Exploitation Framework (CKEF) to support the analysts in efficiently managing and exploiting relevant knowledge assets to achieve maritime domain awareness in joint operations centres of the Canadian Forces. While developing the CKEF, anomaly detection has been clearly recognized as an important aspect requiring R&D. An activity has thus been undertaken to implement,

  10. Mechanics of Suture Joints

    NASA Astrophysics Data System (ADS)

    Li, Yaning; Song, Juha; Ortiz, Christine; Boyce, Mary; Ortiz group/DMSE/MIT Team; Boyce group/ME/MIT Team

    2011-03-01

    Biological sutures are joints which connect two stiff skeletal or skeletal-like components. These joints possess a wavy geometry with a thin organic layer providing adhesion. Examples of biological sutures include mammalian skulls, the pelvic assembly of the armored fish Gasterosteus aculeatus (the three-spined stickleback), and the suture joints in the shell of the red-eared slider turtle. Biological sutures allow for movement and compliance, control stress concentrations, transmit loads, reduce fatigue stress and absorb energy. In this investigation, the mechanics of the role of suture geometry in providing a naturally optimized joint is explored. In particular, analytical and numerical micromechanical models of the suture joint are constructed. The anisotropic mechanical stiffness and strength are studied as a function of suture wavelength, amplitude and the material properties of the skeletal and organic components, revealing key insights into the optimized nature of these ubiquitous natural joints.

  11. See What I See, Do as I Do: Promoting Joint Attention and Imitation in Preschoolers with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    Warreyn, Petra; Roeyers, Herbert

    2014-01-01

    Since imitation and joint attention are both important abilities for young children and since children with autism spectrum disorder show a range of problems in these domains, imitation and joint attention are important targets for intervention. In this study, we examined the possibility of promoting imitation and joint attention by means of a…

  12. Domain transfer via cross-domain analogy

    Microsoft Academic Search

    Matthew Klenk; Kenneth D. Forbus

    2009-01-01

    Analogical learning has long been seen as a powerful way of extending the reach of one’s knowledge. We present the domain transfer via analogy (DTA) method for learning new domain theories via cross-domain analogy. Our model uses analogies between pairs of textbook example problems, or worked solutions, to create a domain mapping between a familiar and a new domain. This

  13. Characterize scientific domain and domain context

    Microsoft Academic Search

    Jinsong Zhang; Chun Guo; Xiaozhong Liu

    2012-01-01

    Domain knowledge map construction as an important method can describe the significant characters of a selected domain. In this research, we will address three problems for knowledge graph generation. Firstly, this paper will construct domain (core journals and conference proceedings) knowledge and domain context (domain citation) knowledge graphs, and propose a novel method to integrate those graphs. Secondly, two different

  14. Adaptive beam-domain processing for space-based radars

    Microsoft Academic Search

    Yuhong Zhang; Abdelhak Hajjari; Lawrence Adzima; Braham Himed

    2004-01-01

    This paper discusses beam-domain space-time adaptive processing (STAP) algorithms for a low-Earth-orbit (LEO) space-based radar (SBR). The performance of the subarray-based joint-domain-localized (JDL) algorithm is first examined for various processor parameters. Then, a combined beam-domain STAP algorithm approach that combines JDL with difference (?) beams is presented. It is shown that the combined JDL-? algorithms offer less system complexity and

  15. Campylobacter Prosthetic Joint Infection

    PubMed Central

    Vasoo, Shawn; Schwab, Jeramy J.; Cunningham, Scott A.; Robinson, Trisha J.; Cass, Joseph R.; Berbari, Elie F.; Walker, Randall C.; Osmon, Douglas R.

    2014-01-01

    A 75-year-old man was diagnosed with probable Campylobacter jejuni prosthetic knee infection after a diarrheal illness. Joint aspirate and operative cultures were negative, but PCR of prosthesis sonicate fluid was positive, as was stool culture. Nineteen additional cases of Campylobacter prosthetic joint infection reported in the literature are reviewed. PMID:24523462

  16. Joint Newspaper Operating Agreements.

    ERIC Educational Resources Information Center

    Parsons, Marie

    The number of competing daily newspapers in American cities has dwindled until only about 50 cities boast two papers. Of the newspapers in those cities, 23 now maintain separate editorial operations but have joint printing, advertising, and circulation departments. The concept of joint operation is 50 years old, dating from the Depression years…

  17. Compound solder joints

    NASA Technical Reports Server (NTRS)

    Batista, R. I.; Simonson, R. B.

    1976-01-01

    Joining technique prevents contamination, may be used to join dissimilar metal tubes, minimizes fluid and gas entrapment, expedites repairs, and can yield joints having leakage rates less than 0.000001 standard cubic cm He/min. Components of joint are solder sleeve, two solder rings, Teflon sleeve, and tubing to be joined.

  18. Acromioclavicular joint disease.

    PubMed

    Mcdonald, Scott; Hopper, Melanie A

    2015-07-01

    The acromioclavicular joint is an important component of the shoulder girdle experiencing significant loading during normal activities of daily living. The joint is frequently subjected to trauma and as a synovial articulation can become involved in rheumatoid arthritis and the seronegative arthropathies. PMID:26021590

  19. Monitoring groundwater-surface water interaction using time-series and time-frequency analysis of transient three-dimensional electrical resistivity changes

    USGS Publications Warehouse

    Johnson, Timothy C.; Slater, Lee D.; Ntarlagiannis, Dimitris; Day-Lewis, Frederick D.; Elwaseif, Mehrez

    2012-01-01

    Time-lapse resistivity imaging is increasingly used to monitor hydrologic processes. Compared to conventional hydrologic measurements, surface time-lapse resistivity provides superior spatial coverage in two or three dimensions, potentially high-resolution information in time, and information in the absence of wells. However, interpretation of time-lapse electrical tomograms is complicated by the ever-increasing size and complexity of long-term, three-dimensional (3-D) time series conductivity data sets. Here we use 3-D surface time-lapse electrical imaging to monitor subsurface electrical conductivity variations associated with stage-driven groundwater-surface water interactions along a stretch of the Columbia River adjacent to the Hanford 300 near Richland, Washington, USA. We reduce the resulting 3-D conductivity time series using both time-series and time-frequency analyses to isolate a paleochannel causing enhanced groundwater-surface water interactions. Correlation analysis on the time-lapse imaging results concisely represents enhanced groundwater-surface water interactions within the paleochannel, and provides information concerning groundwater flow velocities. Time-frequency analysis using the Stockwell (S) transform provides additional information by identifying the stage periodicities driving groundwater-surface water interactions due to upstream dam operations, and identifying segments in time-frequency space when these interactions are most active. These results provide new insight into the distribution and timing of river water intrusion into the Hanford 300 Area, which has a governing influence on the behavior of a uranium plume left over from historical nuclear fuel processing operations.

  20. Monitoring groundwater-surface water interaction using time-series and time-frequency analysis of transient three-dimensional electrical resistivity changes

    SciTech Connect

    Johnson, Timothy C.; Slater, Lee; Ntarlagiannis, Dimitrios; Day-Lewis, Frederick D.; Elwaseif, Mehrez

    2012-08-22

    Time-lapse resistivity imaging is increasingly used to monitor hydrologic processes. Compared to conventional hydrologic measurements, surface time-lapse resistivity provides (1) superior spatial coverage in two or three dimensions, (2) potentially high-resolution information in time, and (3) information in the absence of wells. However, interpretation of time-lapse electrical tomograms is complicated by the ever increasing size and complexity of long-term, three-dimensional time-series conductivity datasets. Here, we use three-dimensional (3D) surface time-lapse electrical imaging to monitor subsurface electrical conductivity variations associated with stage-driven groundwater/surface-water interaction along a stretch of the Columbia River adjacent to the Hanford 300 Area, Hanford WA, USA. We reduce the resulting 3D conductivity time series using both correlation and time-frequency analysis to isolate a paleochannel causing enhanced groundwater/river-water interaction. Correlation analysis on the time-lapse imaging results concisely represents enhanced ground water/surface-water interaction within the paleochannel, and provides information concerning groundwater flow velocities. Time-frequency analysis using the Stockwell (S) Transform provides additional information by 1) identifying the stage periodicities driving ground water/river-water interaction due to upstream dam operations, 2) identifying segments in time-frequency space when these interactions are most active. These results provide new insight into the distribution and timing of river water intrusion into the Hanford 300 area, which has a governing influence on the behavior of a uranium plume left over from historical nuclear fuel processing operations.

  1. JOINT ELECTRICAL & COMPUTER ENGINEERING AND

    E-print Network

    JOINT ELECTRICAL & COMPUTER ENGINEERING AND PHYSICS COLLOQUIUM "Speckle Statistics, Coherence confirmation of the increase in the well- defined polarization state of the output radiation. In the joint

  2. Domain boundary engineering

    Microsoft Academic Search

    Ekhard Salje; Huali Zhang

    2009-01-01

    We review the idea that domain boundaries, rather than domains, can carry information and act as memory devices. Domains are bulk objects; their large response to changing external fields is related to their change in volume, which implies the movement of domain boundaries. In many cases, the design of ‘optimal’ domain structures corresponds to ‘optimal’ domain boundaries with parameters such

  3. DMBC: Domain Names & Web Hosting Domain Names

    E-print Network

    Stowell, Michael

    DMBC: Domain Names & Web Hosting Domain Names Top Level Domains · .com · .net · .org · .edu · .gov.9% of the web-viewing audience is used to typing in. Chances are, a visitor will type in ".com" even if you tell and simple · Try to avoid dashes or underscores in the domain name unless there is no other option Web

  4. Common time-frequency analysis of local field potential and pyramidal cell activity in seizure-like events of the rat hippocampus

    NASA Astrophysics Data System (ADS)

    Cotic, M.; Chiu, A. W. L.; Jahromi, S. S.; Carlen, P. L.; Bardakjian, B. L.

    2011-08-01

    To study cell-field dynamics, physiologists simultaneously record local field potentials and the activity of individual cells from animals performing cognitive tasks, during various brain states or under pathological conditions. However, apart from spike shape and spike timing analyses, few studies have focused on elucidating the common time-frequency structure of local field activity relative to surrounding cells across different periods of phenomena. We have used two algorithms, multi-window time frequency analysis and wavelet phase coherence (WPC), to study common intracellular-extracellular (I-E) spectral features in spontaneous seizure-like events (SLEs) from rat hippocampal slices in a low magnesium epilepsy model. Both algorithms were applied to 'pairs' of simultaneously observed I-E signals from slices in the CA1 hippocampal region. Analyses were performed over a frequency range of 1-100 Hz. I-E spectral commonality varied in frequency and time. Higher commonality was observed from 1 to 15 Hz, and lower commonality was observed in the 15-100 Hz frequency range. WPC was lower in the non-SLE region compared to SLE activity; however, there was no statistical difference in the 30-45 Hz band between SLE and non-SLE modes. This work provides evidence of strong commonality in various frequency bands of I-E SLEs in the rat hippocampus, not only during SLEs but also immediately before and after.

  5. Event-Related EEG Time-Frequency Analysis: An Overview of Measures and An Analysis of Early Gamma Band Phase Locking in Schizophrenia

    PubMed Central

    Roach, Brian J.; Mathalon, Daniel H.

    2008-01-01

    An increasing number of schizophrenia studies have been examining electroencephalography (EEG) data using time-frequency analysis, documenting illness-related abnormalities in neuronal oscillations and their synchronization, particularly in the gamma band. In this article, we review common methods of spectral decomposition of EEG, time-frequency analyses, types of measures that separately quantify magnitude and phase information from the EEG, and the influence of parameter choices on the analysis results. We then compare the degree of phase locking (ie, phase-locking factor) of the gamma band (36–50 Hz) response evoked about 50 milliseconds following the presentation of standard tones in 22 healthy controls and 21 medicated patients with schizophrenia. These tones were presented as part of an auditory oddball task performed by subjects while EEG was recorded from their scalps. The results showed prominent gamma band phase locking at frontal electrodes between 20 and 60 milliseconds following tone onset in healthy controls that was significantly reduced in patients with schizophrenia (P?=?.03). The finding suggests that the early-evoked gamma band response to auditory stimuli is deficiently synchronized in schizophrenia. We discuss the results in terms of pathophysiological mechanisms compromising event-related gamma phase synchrony in schizophrenia and further attempt to reconcile this finding with prior studies that failed to find this effect. PMID:18684772

  6. Compliant Joints For Robots

    NASA Technical Reports Server (NTRS)

    Kerley, James J., Jr.

    1990-01-01

    Compliant joints devised to accommodate misalignments of tools and/or workpieces with respect to robotic manipulators. Has characteristics and appearance of both universal-joint and cable-spring-type flexible shaft coupling. Compliance derived from elastic properties of short pieces of cable. Compliance of joint determined by lengths, distances between, relative orientations, thickness of strands, number of strands, material, amount of pretwist, and number of short pieces of cable. Worm-drive mechanism used to adjust lengths to vary compliance as needed during operation.

  7. Design of FIR beamformer with frequency invariant patterns via jointly optimizing spatial and frequency responses

    Microsoft Academic Search

    Shefeng Yan; Yuanliang Ma

    2005-01-01

    An approach to the optimal design of FIR broadband beamformer with frequency invariant patterns via joint optimizing the spatial and frequency responses is proposed. The beam responses are jointly optimized to satisfy some spatial and frequency domain specifications by designing a bank of FIR filters corresponding to the input channels. It minimizes the maximum error between the designed beam patterns

  8. Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Panel Post & Diagonal Brace Joint Detail; Crossbracing Center Joint Detail; Chord, Panel Post, Tie Bar, & Diagonal Brace Joint Detail; Chord, Tie Bar, & Crossbracing Joint Detail - Medora Bridge, Spanning East Fork of White River at State Route 235, Medora, Jackson County, IN

  9. Joint fluid Gram stain

    MedlinePLUS

    Gram stain of joint fluid ... result means no bacteria are present on the Gram stain. Note: Normal value ranges may vary slightly ... Abnormal results mean bacteria were seen on the Gram stain. This may be a sign of a ...

  10. Damage detection of truss bridge joints using Artificial Neural Networks

    Microsoft Academic Search

    M. Mehrjoo; N. Khaji; H. Moharrami; A. Bahreininejad

    2008-01-01

    Recent developments in Artificial Neural Networks (ANNs) have opened up new possibilities in the domain of inverse problems. For inverse problems like structural identification of large structures (such as bridges) where in situ measured data are expected to be imprecise and often incomplete, ANNs may hold greater promise. This study presents a method for estimating the damage intensities of joints

  11. Noninfectious joint disease in cattle.

    PubMed

    Nichols, Sylvain; Lardé, Hélène

    2014-03-01

    Osteochondrosis causes variable degrees of joint effusion and lameness. Arthroscopic debridement of the lesions provides the best long-term outcome. Articular fracture or joint instability following collateral ligament rupture causes severe joint effusion and lameness. Internal fixation combined with external coaptation is the treatment of choice. Degenerative joint disease in young animals has a guarded prognosis. Arthroscopy combined with medical therapy may slow down the disease process. Degenerative joint disease involving the distal interphalangeal joint has a good prognosis following joint resection. PMID:24534666

  12. Supergravity domain walls

    Microsoft Academic Search

    Mirjam Cvetiÿc; Harald H. Soleng

    1997-01-01

    We review the status of domain walls in N = 1 supergravity theories for the vacuum domain walls as well as dilatonic domain walls. We concentrate on a systematic analysis of the nature of the space-time in these domain wall backgrounds and the special role that supersymmetry is playing in determining the nature of such configurations. Isotropic vacuum domain walls

  13. Analysis of time-variant quadratic phase couplings in the tracé alternant EEG by recursive estimation of 3rd-order time-frequency distributions.

    PubMed

    Helbig, Marko; Schwab, Karin; Leistritz, Lutz; Eiselt, Michael; Witte, Herbert

    2006-10-15

    The quantification of transient quadratic phase couplings (QPC) by means of time-variant bispectral analysis is a useful approach to explain several interrelations between signal components. A generalized recursive estimation approach for 3rd-order time-frequency distributions (3rd-order TFD) is introduced. Based on 3rd-order TFD, time-variant estimations of biamplitude (BA), bicoherence (BC) and phase bicoherence (PBC) can be derived. Different smoothing windows and local moment functions for an optimization of the estimation properties are investigated and compared. The methods are applied to signal simulations and EEG signals, and it can be shown that the new time-variant bispectral analysis results in a reliable quantification of QPC in the tracé alternant EEG of healthy neonates. PMID:16737739

  14. Time, Frequency and Physical Measurement.

    ERIC Educational Resources Information Center

    Hellwig, Helmut; And Others

    1978-01-01

    Describes several developments in atomic clocks and frequency standards pointing out the feasibility and practicality in adopting a unified standard of time and frequency to replace other base standards of length, mass, and temperature. (GA)

  15. New Joint Sealants. Criteria, Design and Materials.

    ERIC Educational Resources Information Center

    Building Research Inst., Inc., Washington, DC.

    Contents include--(1) sealing concrete joints, (2) sealing glass and metal joints, (3) metal and glass joint sealants from a fabricator's viewpoint, (4) a theory of adhesion for joint sealants, (5) geometry of simple joint seals under strain, (6) joint sealant specifications from a manufacturer's viewpoint, (7) joint sealant requirements from an…

  16. Joint for deployable structures

    NASA Technical Reports Server (NTRS)

    Craighead, N. D., II; Preliasco, R. J.; Hult, T. D. (inventors)

    1985-01-01

    A joint is described for connecting a pair of beams to pivot them between positions in alignment or beside one another, which is of light weight and which operates in a controlled manner. The joint includes a pair of fittings and at least one center link having opposite ends pivotally connected to opposite fittings and having axes that pass through centerplates of the fittings. A control link having opposite ends pivotally connected to the different fittings controls their relative orientations, and a toggle assemly holds the fittings in the deployed configuration wherein they are aligned. The fittings have stops that lie on one side of the centerplane opposite the toggle assembly.

  17. Beamspace-Domain Multichannel Nonnegative Matrix Factorization for Audio Source Separation

    Microsoft Academic Search

    Seokjin Lee; Sang Ha Park; Koeng-Mo Sung

    2012-01-01

    In this letter, we develop a multichannel blind source separation algorithm based on a beamspace transform and the multichannel nonnegative matrix factorization (NMF) method. The conventional multichannel NMF algorithm performs well with multichannel mixing data, but there is still room for enhancement in multichannel real-world recording data. In this letter, we consider a beamspace-time-frequency domain data model for multichannel NMF

  18. Stability analysis of steady states for surface diffusion equation in a bounded domain

    E-print Network

    Ishii, Hitoshi

    . . Stability analysis of steady states for surface diffusion equation in a bounded domain Yoshihito Kohsaka (Muroran Institute of Technology) joint work with H. Garcke and K. Ito Mathematical diffusion 30 July, 2010 1 / 19 #12;Model ¢¡¤£¦¥ §©¨ ¡£¦¥ §¨ ¨ ¢¡£ ¥¤£ §¦£ ¨© ¨© ¨¥© Along

  19. Joints in a Cornstarch Analog

    NSDL National Science Digital Library

    Juliet Crider

    Joints are very important to problems in applied geology (fluid flow, slope stability), but three-dimensional exposures of simple joint sets are not readily accessible from my campus. I developed this exercise based on the experiments of Miller (2001) to give students hands-on practice describing and interpreting joints. For the exercise, I prepare a cornstarch-water mixture a few days in advance and pour it into plastic petri dishes. I add a "flaw" to each dish (typically a small pebble). As the cornstarch dries, vertical joints develop. In class, each group of 3-4 students is provided a petri dish of desiccated cornstarch. Students are asked to draw a map of the joints, paying particular attention to intersection angles. (The joints curve to intersect at 90 degrees.) They determine relative ages of the joints using abutting relationships. (Typically 3-6 generations of joints.) Students next dissect the sample and describe the surface textures of the larger joints and the location of the flaw. The cornstarch produces beautiful plumose structure (hackles). Students then interpret the joint propagation direction from the surface textures, and note the origin of the joint. (Typically, a first- or second-generation joint initiates at the flaw.) Students discuss the role of flaws in the initiation of joints in their groups.

  20. Heterogeneous domain adaptation and classification by exploiting the correlation subspace.

    PubMed

    Yeh, Yi-Ren; Huang, Chun-Hao; Wang, Yu-Chiang Frank

    2014-05-01

    We present a novel domain adaptation approach for solving cross-domain pattern recognition problems, i.e., the data or features to be processed and recognized are collected from different domains of interest. Inspired by canonical correlation analysis (CCA), we utilize the derived correlation subspace as a joint representation for associating data across different domains, and we advance reduced kernel techniques for kernel CCA (KCCA) if nonlinear correlation subspace are desirable. Such techniques not only makes KCCA computationally more efficient, potential over-fitting problems can be alleviated as well. Instead of directly performing recognition in the derived CCA subspace (as prior CCA-based domain adaptation methods did), we advocate the exploitation of domain transfer ability in this subspace, in which each dimension has a unique capability in associating cross-domain data. In particular, we propose a novel support vector machine (SVM) with a correlation regularizer, named correlation-transfer SVM, which incorporates the domain adaptation ability into classifier design for cross-domain recognition. We show that our proposed domain adaptation and classification approach can be successfully applied to a variety of cross-domain recognition tasks such as cross-view action recognition, handwritten digit recognition with different features, and image-to-text or text-to-image classification. From our empirical results, we verify that our proposed method outperforms state-of-the-art domain adaptation approaches in terms of recognition performance. PMID:24710401

  1. Clad metal joint closure

    SciTech Connect

    Siebert, O.W.

    1985-04-09

    A plasma arc spray overlay of cladding metals is used over joints between clad metal pieces to provide a continuous cladding metal surface. The technique permits applying an overlay of a high melting point cladding metal to a cladding metal surface without excessive heating of the backing metal.

  2. CARTILAGE, BONES, AND JOINTS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cartilage is a special type of connective tissue that is of extreme importance in embryonic development, serving as the model upon which true bone is later formed. Cartilage also persists in adult animals, primarily as articular cartilage which cushions the interface between adjacent bones or joint...

  3. Joint publication: Department of

    E-print Network

    Watson, Craig A.

    century. The first law to protect consumers was passed in 1906, and Charles Dadant is credited with getJoint publication: Florida Department of Agriculture & Consumer Services University of Florida Florida Department of Agriculture & Consumer Services 1911 SW 34 Street PO Box 147100 Gainesville, FL

  4. Dolphin Skeleton (Gliding Joint)

    NSDL National Science Digital Library

    Ketan Patel (California State University, Fullerton; )

    2007-07-14

    The dolphin is built to be sleek. Its body is made of almost entirely backbone (a gliding joint) which makes it very flexible under water. The ribs protect the inner organs of the dolphin and the tail beats from side to side, thrusting the animal forward.

  5. Joint Honours AFRICAN STUDIES

    E-print Network

    Miall, Chris

    : The Joint Honours African Studies degree programme at Birmingham is broad, combining arts and social Office - Retail management - Aid work with Save the Children - Probation work - Welfare rights worker - Computer programmer - NGO work in Kurdistan - Work with adults who have learning disabilities - Research

  6. Joint Institute Marine and Atmospheric

    E-print Network

    Hawai'i at Manoa, University of

    Joint Institute for Marine and Atmospheric Research NATIONALOCEA NIC AND ATMOSPHERIC ADMINISTRATION Contribution 00-328 #12;ii This research is funded by Cooperative Agreement Number NA67RJ0154 between the Joint

  7. Making Abstract Domains Condensing

    Microsoft Academic Search

    Roberto Giacobazzi; Francesco Ranzato; Francesca Scozzari

    2002-01-01

    In this paper we show that reversible analysis of logic languages by abstract interpretation can be performed without loss of precision by systematically refining abstract domains. The idea is to include semantic structures into abstract domains in such a way that the refined abstract domain becomes rich enough to allow approximate bottom-up and top-down semantics to agree. These domains are

  8. Cellular Pressure-Actuated Joint

    NASA Technical Reports Server (NTRS)

    McGuire, John R.

    2003-01-01

    A modification of a pressure-actuated joint has been proposed to improve its pressure actuation in such a manner as to reduce the potential for leakage of the pressurizing fluid. The specific joint for which the modification is proposed is a field joint in a reusable solid-fuel rocket motor (RSRM), in which the pressurizing fluid is a mixture of hot combustion gases. The proposed modification could also be applicable to other pressure-actuated joints of similar configuration.

  9. Domains and domain walls in multiferroics

    NASA Astrophysics Data System (ADS)

    Matzen, Sylvia; Fusil, Stéphane

    2015-03-01

    Multiferroics are gathering solid-state matter in which several types of orders are simultaneously allowed, as ferroelectricity, ferromagnetism (or antiferromagnetism), ferroelasticity, or ferrotoroidicity. Among all, the ferroelectric/ferromagnetic couple is the most intensively studied because of potential applications in novel low-power magnetoelectric devices. Switching of one order thanks to the other necessarily proceeds via the nucleation and growth of coupled domains. This review is an introduction to the basics of ferroelectric/ferromagnetic domain formation and to the recent microscopy techniques devoted to domains imaging, providing new insights into the archetypal multiferroic domain morphologies. Some relevant examples are also given to illustrate some of the unexpected properties of domain walls, as well as the way these domain walls can be manipulated altogether thanks to various types of magnetoelectric coupling.

  10. Phase 1 Program Joint Report

    NASA Technical Reports Server (NTRS)

    Nield, George C. (Editor); Vorobiev, Pavel Mikhailovich (Editor)

    1999-01-01

    This report consists of inputs from each of the Phase I Program Joint Working Groups. The Working Groups were tasked to describe the organizational structure and work processes that they used during the program, joint accomplishments, lessons learned, and applications to the International Space Station Program. This report is a top-level joint reference document that contains information of interest to both countries.

  11. Joint Communiqu Progress against the

    E-print Network

    1 Joint Communiqué Progress against the Joint Statement of Cooperation between Kalimantan Timur the Joint Statement of Cooperation of 16 September 2010 designed to develop closer ties between Kalimantan the following areas: Livestock Following the 2010 Livestock Workshop held in Balikpapan, a Kalimantan Timur

  12. Joint Seminar UNIVERSITY OF GEORGIA

    E-print Network

    Wang, Lily

    Joint Seminar UNIVERSITY OF GEORGIA DEPARTMENT OF STATISTICS DEPARTMENT OF EPIDEMIOLOGY longitudinal covariates are involved in the modeling of the survival data. A joint likelihood approach has been data. However, in the presence of left truncation, there are additional challenges for the joint

  13. JOINT PERFORMANCE Guide for Optimum

    E-print Network

    July 2012 JOINT PERFORMANCE Guide for Optimum of Concrete Pavements #12; #12;Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2. Report Date Guide for Optimum Joint Performance of Concrete Pavements July 2012 6. Performing

  14. Sub-Nyquist field trial using time frequency packed DP-QPSK super-channel within fixed ITU-T grid.

    PubMed

    Potì, L; Meloni, G; Berrettini, G; Fresi, F; Foggi, T; Secondini, M; Giorgi, L; Cavaliere, F; Hackett, S; Petronio, A; Nibbs, P; Forgan, R; Leong, A; Masciulli, R; Pfander, C

    2015-06-15

    Sub-Nyquist time frequency packing technique was demonstrated for the first time in a super-channel field trial transmission over long-haul distances. The technique allows a limited spectral occupancy even with low order modulation formats. The transmission was successfully performed on a deployed Australian link between Sydney and Melbourne which included 995 km of uncompensated SMF with coexistent traffic. 40 and 100 Gb/s co-propagating channels were transmitted together with the super-channel in a 50 GHz ITU-T grid without additional penalty. The super-channel consisted of eight sub-channels with low-level modulation format, i.e. DP-QPSK, guaranteeing better OSNR robustness and reduced complexity with respect to higher order formats. At the receiver side, coherent detection was used together with iterative maximum-a-posteriori (MAP) detection and decoding. A 975 Gb/s DP-QPSK super-channel was successfully transmitted between Sydney and Melbourne within four 50GHz WSS channels (200 GHz). A maximum potential SE of 5.58 bit/s/Hz was achieved with an OSNR = 15.8 dB, comparable to the OSNR of the installed 100 Gb/s channels. The system reliability was proven through long term measurements. In addition, by closing the link in a loop back configuration, a potential SE?d product of 9254 bit/s/Hz·km was achieved. PMID:26193592

  15. Sub-Nyquist Field Trial Using Time Frequency Packed DP-QPSK Super-Channel Within Fixed ITU-T Grid

    E-print Network

    Potì, L; Berrettini, G; Fresi, F; Foggi, T; Secondini, M; Giorgi, L; Cavaliere, F; Hackett, S; Petronio, A; Nibbs, P; Forgan, R; Leong, A; Masciulli, R; Pfander, C

    2015-01-01

    Sub-Nyquist time frequency packing technique was demonstrated for the first time in a super channel field trial transmission over long-haul distances. The technique allows a limited spectral occupancy even with low order modulation formats. The transmission was successfully performed on a deployed Australian link between Sydney and Melbourne which included 995 km of uncompensated SMF with coexistent traffic. 40 and 100 Gb/s co-propagating channels were transmitted together with the super-channel in a 50 GHz ITU-T grid without additional penalty. The super-channel consisted of eight sub-channels with low-level modulation format, i.e. DP-QPSK, guaranteeing better OSNR robustness and reduced complexity with respect to higher order formats. At the receiver side, coherent detection was used together with iterative maximum-a-posteriori (MAP) detection and decoding. A 975 Gb/s DP-QPSK super-channel was successfully transmitted between Sydney and Melbourne within four 50GHz WSS channels (200 GHz). A maximum potential...

  16. Is auditory discrimination mature by middle childhood? A study using time-frequency analysis of mismatch responses from 7 years to adulthood

    PubMed Central

    Bishop, Dorothy VM; Hardiman, Mervyn J; Barry, Johanna G

    2011-01-01

    Behavioural and electrophysiological studies give differing impressions of when auditory discrimination is mature. Ability to discriminate frequency and speech contrasts reaches adult levels only around 12 years of age, yet an electrophysiological index of auditory discrimination, the mismatch negativity (MMN), is reported to be as large in children as in adults. Auditory ERPs were measured in 30 children (7 to 12 years), 23 teenagers (13 to 16 years) and 32 adults (35 to 56 years) in an oddball paradigm with tone or syllable stimuli. For each stimulus type, a standard stimulus (1000 Hz tone or syllable [ba]) occurred on 70% of trials, and one of two deviants (1030 or 1200 Hz tone, or syllables [da] or [bi]) equiprobably on the remaining trials. For the traditional MMN interval of 100–250 ms post-onset, size of mismatch responses increased with age, whereas the opposite trend was seen for an interval from 300 to 550 ms post-onset, corresponding to the late discriminative negativity (LDN). Time-frequency analysis of single trials revealed that the MMN resulted from phase-synchronization of oscillations in the theta (4–7 Hz) range, with greater synchronization in adults than children. Furthermore, the amount of synchronization was significantly correlated with frequency discrimination threshold. These results show that neurophysiological processes underlying auditory discrimination continue to develop through childhood and adolescence. Previous reports of adult-like MMN amplitudes in children may be artefactual results of using peak measurements when comparing groups that differ in variance. PMID:22213909

  17. Surface Wave Dispersion Analysis Using Time-Frequency Filtering and an Interactive Normal Move Out (NMO) Tool with Uncorrelated Garner Valley Vibroseis Data

    NASA Astrophysics Data System (ADS)

    Lord, N. E.; Wang, H. F.; Fratta, D.; Lancelle, C.; Baldwin, J. A.; Nigbor, R. L.; Chalari, A.; Castongia, E.

    2014-12-01

    Frequency swept seismic sources (vibroseis) recorded by seismic arrays can be used to directly measure the surface wave apparent velocity as a function of frequency. Time-frequency filtering (TFF) passes only a narrow frequency band centered on the time varying frequency of the seismic source. This greatly improves the quality of the uncorrelated seismic data by removing noise outside of the narrow band filter. Sources of noise include traffic, harmonics generated by the seismic source and the propagating seismic waves. TFF also allows the separate analysis of the source fundamental frequency and each harmonic. The filtered data is used with an interactive normal move out (NMO) tool to adjust the time and apparent velocity parameters to extract a surface wave dispersion curve. This technique was used on the vibroseis data collected in the September 2013 seismic experiment conducted at the NEES@UCSB Garner Valley field site. Three vibroseis sources were used: a 45 KN shear shaker, a 450 N portable mass shaker, and a 26 KN vibroseis truck. They were recorded by two lines of 1 and 3 component accelerometers and geophones, and a Distributed Acoustic Sensor (Silixa-iDAS™) system connected to 762 m of trenched fiber optical cable in a larger rectangular area.

  18. Ridge extraction from the time-frequency representation (TFR) of signals based on an image processing approach: application to the analysis of uterine electromyogram AR TFR.

    PubMed

    Terrien, Jérémy; Marque, Catherine; Germain, Guy

    2008-05-01

    Time-frequency representations (TFRs) of signals are increasingly being used in biomedical research. Analysis of such representations is sometimes difficult, however, and is often reduced to the extraction of ridges, or local energy maxima. In this paper, we describe a new ridge extraction method based on the image processing technique of active contours or snakes. We have tested our method on several synthetic signals and for the analysis of uterine electromyogram or electrohysterogram (EHG) recorded during gestation in monkeys. We have also evaluated a postprocessing algorithm that is especially suited for EHG analysis. Parameters are evaluated on real EHG signals in different gestational periods. The presented method gives good results when applied to synthetic as well as EHG signals. We have been able to obtain smaller ridge extraction errors when compared to two other methods specially developed for EHG. The gradient vector flow (GVF) snake method, or GVF-snake method, appears to be a good ridge extraction tool, which could be used on TFR of mono or multicomponent signals with good results. PMID:18440895

  19. When holding your horses meets the deer in the headlights: time-frequency characteristics of global and selective stopping under conditions of proactive and reactive control.

    PubMed

    Lavallee, Christina F; Meemken, Marie T; Herrmann, Christoph S; Huster, Rene J

    2014-01-01

    The ability to inhibit unwanted thoughts or actions is crucial for successful functioning in daily life; however, this ability is often impaired in a number of psychiatric disorders. Despite the relevance of inhibition in everyday situations, current models of inhibition are rather simplistic and provide little generalizability especially in the face of clinical disorders. Thus, given the importance of inhibition for proper cognitive functioning, the need for a paradigm, which incorporates factors that will subsequently improve the current model for understanding inhibition, is of high demand. A popular paradigm used to assess motor inhibition, the stop-signal paradigm, can be modified to further advance the current conceptual model of inhibitory control and thus provide a basis for better understanding different facets of inhibition. Namely, in this study, we have developed a novel version of the stop-signal task to assess how preparation (that is, whether reactive or proactive) and selectivity of the stopping behavior effect well-known time-frequency characteristics associated with successful inhibition and concomitant behavioral measures. With this innovative paradigm, we demonstrate that the selective nature of the stopping task modulates theta and motoric beta activity and we further provide the first account of delta activity as an electrophysiological feature sensitive to both manipulations of selectivity and preparatory control. PMID:25540615

  20. 47 CFR 76.912 - Joint certification.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...912 Joint certification. (a) Franchising authorities may apply for joint...data collection, and ratemaking. Franchising authorities jointly certified to regulate...independent rate decisions. (b) Franchising authorities may apply for joint...

  1. 47 CFR 76.912 - Joint certification.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...912 Joint certification. (a) Franchising authorities may apply for joint...data collection, and ratemaking. Franchising authorities jointly certified to regulate...independent rate decisions. (b) Franchising authorities may apply for joint...

  2. Joint Degrees & Promotion towards European Students

    E-print Network

    Di Pillo, Gianni

    Joint Degrees & Promotion towards European Students 26 June 2014 MATTEA CAPELLI & ALESSANDRA GALLERANO INTERNATIONAL OFFICE #12;Joint Degrees and Promotion towards European students Joint degrees guidelines and template for agreements Support to student participation Promotion of Joint Degrees towards

  3. Joint attention studies in normal and autistic children using NIRS

    NASA Astrophysics Data System (ADS)

    Chaudhary, Ujwal; Hall, Michael; Gutierrez, Anibal; Messinger, Daniel; Rey, Gustavo; Godavarty, Anuradha

    2011-03-01

    Autism is a socio-communication brain development disorder. It is marked by degeneration in the ability to respond to joint attention skill task, from as early as 12 to 18 months of age. This trait is used to distinguish autistic from nonautistic. In this study Near infrared spectroscopy (NIRS) is being applied for the first time to study the difference in activation and connectivity in the frontal cortex of typically developing (TD) and autistic children between 4-8 years of age in response to joint attention task. The optical measurements are acquired in real time from frontal cortex using Imagent (ISS Inc.) - a frequency domain based NIRS system in response to video clips which engenders a feeling of joint attention experience in the subjects. A block design consisting of 5 blocks of following sequence 30 sec joint attention clip (J), 30 sec non-joint attention clip (NJ) and 30 sec rest condition is used. Preliminary results from TD child shows difference in brain activation (in terms of oxy-hemoglobin, HbO) during joint attention interaction compared to the nonjoint interaction and rest. Similar activation study did not reveal significant differences in HbO across the stimuli in, unlike in an autistic child. Extensive studies are carried out to validate the initial observations from both brain activation as well as connectivity analysis. The result has significant implication for research in neural pathways associated with autism that can be mapped using NIRS.

  4. Achieving joint benefits from joint implementation

    SciTech Connect

    Moomaw, W.R. [Tufts Univ., Medford, MA (United States)

    1995-11-01

    Joint Implementation (JI) appears to have been born with Applied Energy Services Guatemala project in 1988. That project, to plant 52 million trees, protect existing forests from cutting and fire, and enhance rural development, is being implemented by CARE Guatemala to offset 120 per cent of the emissions of a small coal burning power plant that has been built in Connecticut. Since that time, several utilities and governments have initiated additional projects. Not all of these necessarily consist of tree planting in other countries, but may consist of energy efficiency or energy conservation programs designed to reduce carbon emissions by at least as much as the additional releases from a new facility. All JI projects share the characteristic of linking the release of greenhouse gases in an industrial country with an offset that reduces or absorbs a comparable amount in another country. The emitter in the industrial country is willing to pay for the reduction elsewhere because costs are less than they would be at home.

  5. Laboratory characterization of rock joints

    SciTech Connect

    Hsiung, S.M.; Kana, D.D.; Ahola, M.P.; Chowdhury, A.H.; Ghosh, A. [Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses

    1994-05-01

    A laboratory characterization of the Apache Leap tuff joints under cyclic pseudostatic and dynamic loads has been undertaken to obtain a better understanding of dynamic joint shear behavior and to generate a complete data set that can be used for validation of existing rock-joint models. Study has indicated that available methods for determining joint roughness coefficient (JRC) significantly underestimate the roughness coefficient of the Apache Leap tuff joints, that will lead to an underestimation of the joint shear strength. The results of the direct shear tests have indicated that both under cyclic pseudostatic and dynamic loadings the joint resistance upon reverse shearing is smaller than that of forward shearing and the joint dilation resulting from forward shearing recovers during reverse shearing. Within the range of variation of shearing velocity used in these tests, the shearing velocity effect on rock-joint behavior seems to be minor, and no noticeable effect on the peak joint shear strength and the joint shear strength for the reverse shearing is observed.

  6. Collective and joint intention

    Microsoft Academic Search

    Raimo Tuomela; Joint Intentions

    2000-01-01

    The paper discussed and analyzes collective and joint intentions of various strength. Thus there are subjectively shared collective\\u000a intentions and intersubjectively shared collective intentions as well as collective intentions which are objectively and intersubjectively\\u000a shared. The distinction between collective and private intentions is considered from several points of view. Especially, it\\u000a is emphasized that collective intentions in the full sense

  7. Joint measurements and Bell inequalities

    E-print Network

    Wonmin Son; Erika Andersson; Stephem M. Barnett; M. S. Kim

    2005-09-20

    Joint quantum measurements of non-commuting observables are possible, if one accepts an increase in the measured variances. A necessary condition for a joint measurement to be possible is that a joint probability distribution exists for the measurement. This fact suggests that there may be a link with Bell inequalities, as these will be satisfied if and only if a joint probability distribution for all involved observables exists. We investigate the connections between Bell inequalities and conditions for joint quantum measurements to be possible. Mermin's inequality for the three-particle Greenberger-Horne-Zeilinger state turns out to be equivalent to the condition for a joint measurement on two out of the three quantum systems to exist. Gisin's Bell inequality for three co-planar measurement directions, meanwhile, is shown to be less strict than the condition for the corresponding joint measurement.

  8. Time-frequency analysis of neonatal cranial ultrasonic movies for selective detection of pulsatile tissues by avoiding probe-motion artifact

    NASA Astrophysics Data System (ADS)

    Fukuzawa, Masayuki; Tabata, Yuki; Izuwaki, Yusuke; Nakamori, Nobuyuki; Kitsunezuka, Yoshiki

    2015-03-01

    In order to detect the pulsatile tissues in neonatal cranial ultrasonic movies by avoiding probe-motion artifact, a time-frequency analysis has been performed in several movie fragments at typical three scenes: (a) a brain-lost, (b) a brain-captured and probe-stabilized, and (c) a brain-captured and probe-swayed ones. The pulsatile tissue, which is a key point of pediatric diagnosis, had successfully detected with an algorithm based on Fourier transform but it had required us to extract the probe-stabilized scene manually by visual observation of the movie. A spatial mean square of echo intensity Etot and a total AC power Ptot over a fan-shape of field of view were evaluated according to a power spectrum of a time-variation of 64 samples of echo intensity at each pixel in each movie fragment split from actual B-mode ultrasonic movies taken at coronal sections of a neonate. The results revealed that (1) significant low Etot was found at the brain-lost scene rather than that at the other scenes, and (2) lower Ptot was found at the probe-stabilized scene rather than the probe-swayed ones. This fact strongly suggests that the Etot and Ptot are promising features for automatic extraction of probe-stabilized scenes. It must lead to detect the pulsatile tissues selectively by avoiding probe-motion artifact and to realize systematic analysis of the whole of our extensive movie archives, which is useful not only for retrospective study of ischemic diseases but also for bedside diagnosis to stabilize the freehand ultrasonic probe.

  9. One hundred ways to process time, frequency, rate and scale in the central auditory system: a pattern-recognition meta-analysis

    PubMed Central

    Hemery, Edgar; Aucouturier, Jean-Julien

    2015-01-01

    The mammalian auditory system extracts features from the acoustic environment based on the responses of spatially distributed sets of neurons in the subcortical and cortical auditory structures. The characteristic responses of these neurons (linearly approximated by their spectro-temporal receptive fields, or STRFs) suggest that auditory representations are formed, as early as in the inferior colliculi, on the basis of a time, frequency, rate (temporal modulations) and scale (spectral modulations) analysis of sound. However, how these four dimensions are integrated and processed in subsequent neural networks remains unclear. In this work, we present a new methodology to generate computational insights into the functional organization of such processes. We first propose a systematic framework to explore more than a hundred different computational strategies proposed in the literature to process the output of a generic STRF model. We then evaluate these strategies on their ability to compute perceptual distances between pairs of environmental sounds. Finally, we conduct a meta-analysis of the dataset of all these algorithms' accuracies to examine whether certain combinations of dimensions and certain ways to treat such dimensions are, on the whole, more computationally effective than others. We present an application of this methodology to a dataset of ten environmental sound categories, in which the analysis reveals that (1) models are most effective when they organize STRF data into frequency groupings—which is consistent with the known tonotopic organization of receptive fields in auditory structures -, and that (2) models that treat STRF data as time series are no more effective than models that rely only on summary statistics along time—which corroborates recent experimental evidence on texture discrimination by summary statistics.

  10. A Design Pattern for Asynchronous Web Services in Secure, Cross-Domain Information Sharing

    Microsoft Academic Search

    Robert Dourandish; Nina Zumel; Michael Manno

    2007-01-01

    Cross-domain information sharing is the cornerstone of joint operations. This is particularly true in the context of intelligence activities, where raw data must be collected, distributed, analyzed, validated, and annotated before any usable information product can be created. A significant barrier to rapid, efficient, and effective data distribution and analysis is the tiered, multi-domain access paradigm employed by the DOD

  11. Interpolation function for approximating knee joint behavior in human gait

    NASA Astrophysics Data System (ADS)

    Toth-Ta?c?u, Mirela; Pater, Flavius; Stoia, Dan Ioan

    2013-10-01

    Starting from the importance of analyzing the kinematic data of the lower limb in gait movement, especially the angular variation of the knee joint, the paper propose an approximation function that can be used for processing the correlation among a multitude of knee cycles. The approximation of the raw knee data was done by Lagrange polynomial interpolation on a signal acquired using Zebris Gait Analysis System. The signal used in approximation belongs to a typical subject extracted from a lot of ten investigated subjects, but the function domain of definition belongs to the entire group. The study of the knee joint kinematics plays an important role in understanding the kinematics of the gait, this articulation having the largest range of motion in whole joints, in gait. The study does not propose to find an approximation function for the adduction-abduction movement of the knee, this being considered a residual movement comparing to the flexion-extension.

  12. Concrete Domains Gilles Kahn

    E-print Network

    Plotkin, Gordon

    Concrete Domains Gilles Kahn INRIA ­ Sophia Antipolis Gordon D. Plotkin University of Edinburgh May called concrete domains. The purpose of this theory is to find a satisfactory framework for the notions

  13. Time-Frequency Analysis of Rocket Nozzle Wall Pressures during Start-up Transients This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-print Network

    Tinney, Charles E.

    Time-Frequency Analysis of Rocket Nozzle Wall Pressures during Start-up Transients This article has-up Transients Woutijn J. Baars1, Charles E. Tinney1 and Joseph H. Ruf2 1 The University of Texas at Austin fixed and transient start-up conditions. These unsteady signatures are driven by shock wave turbulent

  14. On representations for joint moments using a joint coordinate system.

    PubMed

    O'Reilly, Oliver M; Sena, Mark P; Feeley, Brian T; Lotz, Jeffrey C

    2013-11-01

    In studies of the biomechanics of joints, the representation of moments using the joint coordinate system has been discussed by several authors. The primary purpose of this technical brief is to emphasize that there are two distinct, albeit related, representations for moment vectors using the joint coordinate system. These distinct representations are illuminated by exploring connections between the Euler and dual Euler bases, the "nonorthogonal projections" presented in a recent paper by Desroches et al. (2010, "Expression of Joint Moment in the Joint Coordinate System," ASME J. Biomech. Eng., 132(11), p. 11450) and seminal works by Grood and Suntay (Grood and Suntay, 1983, "A Joint Coordinate System for the Clinical Description of Three-Dimensional Motions: Application to the Knee," ASME J. Biomech. Eng., 105(2), pp. 136-144) and Fujie et al. (1996, "Forces and Moment in Six-DOF at the Human Knee Joint: Mathematical Description for Control," Journal of Biomechanics, 29(12), pp. 1577-1585) on the knee joint. It is also shown how the representation using the dual Euler basis leads to straightforward definition of joint stiffnesses. PMID:24008987

  15. Causal Learning Across Domains

    Microsoft Academic Search

    Laura E. Schulz; Alison Gopnik

    2004-01-01

    Five studies investigated (a) children's ability to use the dependent and independent probabilities of events to make causal inferences and (b) the interaction between such inferences and domain-specific knowledge. In Experiment 1, preschoolers used patterns of dependence and independence to make accurate causal inferences in the domains of biology and psychology. Experiment 2 replicated the results in the domain of

  16. Posttraumatic Temporomandibular Joint Disorders

    PubMed Central

    Giannakopoulos, Helen E.; Quinn, Peter D.; Granquist, Eric; Chou, Joli C.

    2009-01-01

    The temporomandibular joint (TMJ) has many essential functions. None of its components are exempt from injury. Facial asymmetry, malocclusion, disturbances in growth, osteoarthritis, and ankylosis can manifest as complications from trauma to the TMJ. The goals of initial treatment include achievement of pretraumatic function, restoration of facial symmetry, and resolution of pain. These same objectives hold true for late repairs and reconstruction of the TMJ apparatus. Treatment is demanding, and with opposing approaches. The following article explores various treatment options for problems presenting as a result of a history of trauma to the TMJ. PMID:22110802

  17. Joint bone radiobiology workshop

    SciTech Connect

    Tomich, P.A. (ed.)

    1991-01-01

    The Joint Bone Radiobiology Workshop was held on July 12--13, 1991 in Toronto, Canada. This document contains the papers presented at the meeting. The five sections were: Dose-effects, Endogenous Cofactors, Tumorigenesis, New Methods and Medical Implications. The papers covered risk assessment, tissue distribution of radionuclides, lifetime studies, biological half-lifes, the influence of age at time of exposure, tumor induction by different radionuclides, microscopic localization of radionuclides, and nuclear medicine issues including tissue distribution in the skeleton and bone marrow transplantation. (MHB)

  18. Patellofemoral Joint Disorders

    PubMed Central

    Stalker, Robert

    1987-01-01

    Knee pain is a common presenting complaint by athletes and the general population. Disorders of the patellofemoral joint are responsible for most of these disorders. Abnormal patellar tracking is thought to be the principal cause. Patellar tracking is influenced by a number of dynamic and static factors. These can be assessed with a careful history and physical examination. A treatment program can be designed to alter the precipitating factors. Lower-extremity malalignment, principally hyperpronation of the foot, is believed to be a major cause of abnormal patellar tracking. Conservative treatment programs have had successful results, and less emphasis is now being placed on surgical procedures. PMID:21263850

  19. Temporomandibular Joint Disorders

    NSDL National Science Digital Library

    Patient Education Institute

    This patient education program explains temporomandibular joint disorders (TMJ). It reviews the anatomy of the jaw, plus symptoms, causes, diagnosis, and treatment options for TMJ disorders. This resource is a MedlinePlus Interactive Health Tutorial from the National Library of Medicine, designed and developed by the Patient Education Institute. NOTE: This tutorial requires a special Flash plug-in, version 4 or above. If you do not have Flash, you will be prompted to obtain a free download of the software before you start the tutorial. You will also need an Acrobat Reader, available as a free download, in order to view the Reference Summary.

  20. Bladder operated robotic joint

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A. (inventor)

    1993-01-01

    This invention is a robotic joint which is operated by inflatable bladders and which can be used in applications where it is desired to move or hold an object. A support block supports an elongated plate to which is pivotally attached a finger. A tension strip passes over a lever attached to the finger and is attached at its ends to the support block on opposite sides of the plate. Bladders positioned between the plate and the tension strip on opposite sides of the plate can be inflated by pumps to pivot the finger, with one of the bladders being inflated while the other is being deflated.

  1. Metal to ceramic sealed joint

    DOEpatents

    Lasecki, John V. (Livonia, MI); Novak, Robert F. (Farmington Hills, MI); McBride, James R. (Ypsilanti, MI)

    1991-01-01

    A metal to ceramic sealed joint which can withstand wide variations in temperature and maintain a good seal is provided for use in a device adapted to withstand thermal cycling from about 20 to about 1000 degrees C. The sealed joint includes a metal member, a ceramic member having an end portion, and an active metal braze forming a joint to seal the metal member to the ceramic member. The joint is positioned remote from the end portion of the ceramic member to avoid stresses at the ends or edges of the ceramic member. The sealed joint is particularly suited for use to form sealed metal to ceramic joints in a thermoelectric generator such as a sodium heat engine where a solid ceramic electrolyte is joined to metal parts in the system.

  2. Strength of Welded Aircraft Joints

    NASA Technical Reports Server (NTRS)

    Brueggeman, W C

    1937-01-01

    This investigation is a continuation of work started in 1928 and described in NACA-TR-348 which shows that the insertion of gusset plates was the most satisfactory way of strengthening a joint. Additional tests of the present series show that joints of this type could be improved by cutting out the portion of the plate between the intersecting tubes. T and lattice joints in thin-walled tubing 1 1/2 by 0.020 inch have somewhat lower strengths than joints in tubing of greater wall thickness because of failure by local buckling. In welding the thin-walled tubing, the recently developed "carburizing flux" process was found to be the only method capable of producing joints free from cracks. The "magnetic powder" inspection was used to detect cracks in the joints and flaws in the tubing.

  3. OIG targets contractual joint ventures.

    PubMed

    O'Hare, Patrick K

    2003-09-01

    A recent OIG Special Advisory Bulletin raises questions for providers involved in joint ventures. The Bulletin describes several characteristics that the OIG views as potentially suspect, including a referral stream controlled by the provider initiating the joint venture and the use of a wholly owned subsidiary of the provider to bill and collect for services. According to the OIG, profits paid by the subsidiary to the provider owner in such "suspect contractual joint ventures" could constitute illegal remuneration for referrals. PMID:14503145

  4. Detailed FDTD analysis of electromagnetic fields penetrating narrow slots and lapped joints in thick conducting screens

    Microsoft Academic Search

    Allen Taflove; Fady Harfoush; Korada R. Umashankar; Benjamin Beker; Kane S. Yee

    1988-01-01

    The physics of electromagnetic-wave transmission through narrow slots and tapped joints in thick conducting screens is examined in detail by applying numerical models to compute both field distributions within the slots and joints, and fields transmitted to the shadow region. The modeling tools used is the finite-difference time-domain (FD-TD) method, using a Faraday's-law contour integral approach to modify the basic

  5. Joint custody: solution or illusion?

    PubMed

    Benedek, E P; Benedek, R S

    1979-12-01

    Although the phrase "joint custody" is in popular use, the concept lacks standard definitin; parents who express interest in this form of disposition have widely differing objectives and expectations. The authors discuss the need for determining the primary objectives of the parties involved and for exploring the potential for achieving these through joint custody as well as through other alternatives. They examine the benefits of joint custody as well as the risks engendered by this type of arrangement and make a number of specific recommendations. They conclude that joint custody should be considered and explored, together with other available alternatives, and awarded only in appropriate cases. PMID:507203

  6. Biofluid lubrication for artificial joints 

    E-print Network

    Pendelton, Alice Mae

    2009-05-15

    This research investigated biofluid lubrication related to artificial joints using tribological and rheological approaches. Biofluids studied here represent two categories of fluids, base fluids and nanostructured biofluids. ...

  7. Metacarpophalangeal joint arthroscopy: indications revisited.

    PubMed

    Choi, Alexander K Y; Chow, Esther C S; Ho, P C; Chow, Y Y

    2011-08-01

    Arthroscopic surgery has become the gold standard for the diagnosis and treatment of major joint disorders. With advancement in arthroscopic technique, arthroscopy has become feasible in most human joints, even those as small as the finger joints. The metacarpophalangeal joint (MCPJ) can become spacious with simple traction, the intra-articular anatomy is simple, and its major structures can be easily visualized and identified. However, MCPJ arthroscopy has never been popular. This article describes our experience with MCPJ arthroscopy and seeks to establish its role in clinical practice. PMID:21871361

  8. Rotary Joint for Heat Transfer

    NASA Technical Reports Server (NTRS)

    Shauback, R.

    1986-01-01

    Rotary joint exchanges heat between two heat pipes - one rotating and one stationary. Joint accommodates varying heat loads with little temperature drop across interface. According to concept, heat pipe enters center of disklike stationary section of joint. There, wicks in central artery of heat pipe separate into multiple strands that lead to concentric channels on rotaryinterface side of stationary disk. Thin layer of liquid sodium/potassium alloy carries heat from one member of rotary joint to other. Liquid conducts heat efficiently while permitting relative motion between members. Polypropylene rings contain liquid without interfering with rotation.

  9. Jointly Sponsored Research Program

    SciTech Connect

    Everett A. Sondreal; John G. Hendrikson; Thomas A. Erickson

    2009-03-31

    U.S. Department of Energy (DOE) Cooperative Agreement DE-FC26-98FT40321 funded through the Office of Fossil Energy and administered at the National Energy Technology Laboratory (NETL) supported the performance of a Jointly Sponsored Research Program (JSRP) at the Energy & Environmental Research Center (EERC) with a minimum 50% nonfederal cost share to assist industry in commercializing and effectively applying highly efficient, nonpolluting energy systems that meet the nation's requirements for clean fuels, chemicals, and electricity in the 21st century. The EERC in partnership with its nonfederal partners jointly performed 131 JSRP projects for which the total DOE cost share was $22,716,634 (38%) and the nonfederal share was $36,776,573 (62%). Summaries of these projects are presented in this report for six program areas: (1) resource characterization and waste management, (2) air quality assessment and control, (3) advanced power systems, (4) advanced fuel forms, (5) value-added coproducts, and (6) advanced materials. The work performed under this agreement addressed DOE goals for reductions in CO{sub 2} emissions through efficiency, capture, and sequestration; near-zero emissions from highly efficient coal-fired power plants; environmental control capabilities for SO{sub 2}, NO{sub x}, fine respirable particulate (PM{sub 2.5}), and mercury; alternative transportation fuels including liquid synfuels and hydrogen; and synergistic integration of fossil and renewable resources.

  10. Glenohumeral Joint Injections

    PubMed Central

    Gross, Christopher; Dhawan, Aman; Harwood, Daniel; Gochanour, Eric; Romeo, Anthony

    2013-01-01

    Context: Intra-articular injections into the glenohumeral joint are commonly performed by musculoskeletal providers, including orthopaedic surgeons, family medicine physicians, rheumatologists, and physician assistants. Despite their frequent use, there is little guidance for injectable treatments to the glenohumeral joint for conditions such as osteoarthritis, adhesive capsulitis, and rheumatoid arthritis. Evidence Acquisition: We performed a comprehensive review of the available literature on glenohumeral injections to help clarify the current evidence-based practice and identify deficits in our understanding. We searched MEDLINE (1948 to December 2011 [week 1]) and EMBASE (1980 to 2011 [week 49]) using various permutations of intra-articular injections AND (corticosteroid OR hyaluronic acid) and (adhesive capsulitis OR arthritis). Results: We identified 1 and 7 studies that investigated intra-articular corticosteroid injections for the treatment of osteoarthritis and adhesive capsulitis, respectively. Two and 3 studies investigated the use of hyaluronic acid in osteoarthritis and adhesive capsulitis, respectively. One study compared corticosteroids and hyaluronic acid injections in the treatment of osteoarthritis, and another discussed adhesive capsulitis. Conclusion: Based on existing studies and their level of evidence, there is only expert opinion to guide corticosteroid injection for osteoarthritis as well as hyaluronic acid injection for osteoarthritis and adhesive capsulitis. PMID:24427384

  11. Joint collaborative technology experiment

    NASA Astrophysics Data System (ADS)

    Wills, Michael; Ciccimaro, Donny; Yee, See; Denewiler, Thomas; Stroumtsos, Nicholas; Messamore, John; Brown, Rodney; Skibba, Brian; Clapp, Daniel; Wit, Jeff; Shirts, Randy J.; Dion, Gary N.; Anselmo, Gary S.

    2009-05-01

    Use of unmanned systems is rapidly growing within the military and civilian sectors in a variety of roles including reconnaissance, surveillance, explosive ordinance disposal (EOD), and force-protection and perimeter security. As utilization of these systems grows at an ever increasing rate, the need for unmanned systems teaming and inter-system collaboration becomes apparent. Collaboration provides a means of enhancing individual system capabilities through relevant data exchange that contributes to cooperative behaviors between systems and enables new capabilities not possible if the systems operate independently. A collaborative networked approach to development holds the promise of adding mission capability while simultaneously reducing the workload of system operators. The Joint Collaborative Technology Experiment (JCTE) joins individual technology development efforts within the Air Force, Navy, and Army to demonstrate the potential benefits of interoperable multiple system collaboration in a force-protection application. JCTE participants are the Air Force Research Laboratory, Materials and Manufacturing Directorate, Airbase Technologies Division, Force Protection Branch (AFRL/RXQF); the Army Aviation and Missile Research, Development, and Engineering Center Software Engineering Directorate (AMRDEC SED); and the Space and Naval Warfare Systems Center - Pacific (SSC Pacific) Unmanned Systems Branch operating with funding provided by the Joint Ground Robotics Enterprise (JGRE). This paper will describe the efforts to date in system development by the three partner organizations, development of collaborative behaviors and experimentation in the force-protection application, results and lessons learned at a technical demonstration, simulation results, and a path forward for future work.

  12. Topological Domain Theory 

    E-print Network

    Battenfeld, Ingo

    2008-01-01

    This thesis presents Topological Domain Theory as a powerful and flexible framework for denotational semantics. Topological Domain Theory models a wide range of type constructions and can interpret many computational features. Furthermore, it has...We begin by describing the categories of Topological Domain Theory, and their categorical structure. In particular, we recover the basic constructions of domain theory, such as products, function spaces, fixed points and recursive types, in the context of Topological Domain Theory....As a central contribution, we give a detailed account of how computational effects can be modelled in Topological Domain Theory. Following recent work of Plotkin and Power, who proposed to construct effect monads via free algebra functors, this is done by showing that free algebras for a large class of parametrised equational theories exist in Topological Domain Theory. These parametrised equational theories are expressive enough to generate most of the standard examples of effect monads. Moreover, the free algebras in Topological Domain Theory are obtained by an explicit inductive construction, using only basic topological and set-theoretical principles....We also give a comparison of Topological and Classical Domain Theory. The category of omega-continuous dcpos embeds into Topological Domain Theory, and we prove that this embedding preserves the basic domain-theoretic constructions in most cases. We show that the classical powerdomain constructions on omega-continuous dcpos, including the probabilistic powerdomain, can be recovered in Topological Domain Theory....Finally, we give a synthetic account of Topological Domain Theory. We show that Topological Domain Theory is a specific model of Synthetic Domain Theory in the realizability topos over Scott's graph model. We give internal characterisations of the categories of Topological Domain Theory in this realizability topos, and prove the corresponding categories to be internally complete and weakly small. This enables us to show that Topological Domain Theory can model the polymorphic lambda-calculus, and to obtain a richer collection of free algebras than those constructed earlier....In summary, this thesis shows that Topological Domain Theory supports a wide range of semantic constructions, including the standard domain-theoretic constructions, computational effects and polymorphism, all within a single setting....

  13. Joint Interdisciplinary Earth Science Information Center

    NASA Technical Reports Server (NTRS)

    Kafatos, Menas

    2004-01-01

    The report spans the three year period beginning in June of 2001 and ending June of 2004. Joint Interdisciplinary Earth Science Information Center's (JIESIC) primary purpose has been to carry out research in support of the Global Change Data Center and other Earth science laboratories at Goddard involved in Earth science, remote sensing and applications data and information services. The purpose is to extend the usage of NASA Earth Observing System data, microwave data and other Earth observing data. JIESIC projects fall within the following categories: research and development; STW and WW prototyping; science data, information products and services; and science algorithm support. JIESIC facilitates extending the utility of NASA's Earth System Enterprise (ESE) data, information products and services to better meet the science data and information needs of a number of science and applications user communities, including domain users such as discipline Earth scientists, interdisciplinary Earth scientists, Earth science applications users and educators.

  14. Space Domain Awareness for Manned GEO Servicing

    NASA Astrophysics Data System (ADS)

    Blake, T.

    2010-09-01

    The Defense Advanced Research Projects Agency (DARPA) is embarking on a joint program to service spacecraft in Geosynchronous (GEO) Orbit. This ambitious program, known as R5 (Rendezvous, Refuel, Refurbish, Repair, and Reposition), will develop the technologies required to extend the life of billions of dollars of invested in building, launching and operating GEO spacecraft. Inherent in the R5 program, is the need for high quality awareness of the space domain at GEO. Servicing non-operational spacecraft in GEO will require enhanced debris detect/track and space weather monitoring for crew safety, as well as high resolution characterization of the spacecraft to understand the status of the spacecraft to manifest the repair mission. This paper will briefly describe the GEO space domain sensor and data processing requirements to support the R5 program and outline DARPA’s program plans to develop these capabilities. Distribution Statement A (Approved for Public Release, Distribution Unlimited). DISTAR case 15410.

  15. Stochastic Chemical Reactions in Micro-domains

    E-print Network

    D. Holcman; Z. Schuss

    2004-12-25

    Traditional chemical kinetics may be inappropriate to describe chemical reactions in micro-domains involving only a small number of substrate and reactant molecules. Starting with the stochastic dynamics of the molecules, we derive a master-diffusion equation for the joint probability density of a mobile reactant and the number of bound substrate in a confined domain. We use the equation to calculate the fluctuations in the number of bound substrate molecules as a function of initial reactant distribution. A second model is presented based on a Markov description of the binding and unbinding and on the mean first passage time of a molecule to a small portion of the boundary. These models can be used for the description of noise due to gating of ionic channels by random binding and unbinding of ligands in biological sensor cells, such as olfactory cilia, photo-receptors, hair cells in the cochlea.

  16. Active joints for microrobot limbs

    Microsoft Academic Search

    M. Elwenspoek; L. Smith; B. Hok

    1992-01-01

    In this contribution we propose an electrostatic actuator for active joints. The active joint consists of two plates, one of which is a bilayer and bent by the bimorph effect. The plates are clamped to each other at one edge. A voltage between the plates leads to a very large field at the clamp where the plates are in intimate

  17. Joint strength in RCS frames 

    E-print Network

    Kirby, Cynthia Dawn

    1998-01-01

    for the addition of a RC slab, cover plates, and band plates. Results indicated that the addition of a reinforced concrete slab compositely connected to the steel beams framing into a typical RCS joints as defined by the ASCE guidelines (1994), improved the joint...

  18. Robotic joint experiments under ultravacuum

    NASA Technical Reports Server (NTRS)

    Borrien, A.; Petitjean, L.

    1988-01-01

    First, various aspects of a robotic joint development program, including gearbox technology, electromechanical components, lubrication, and test results, are discussed. Secondly, a test prototype of the joint allowing simulation of robotic arm dynamic effects is presented. This prototype is tested under vacuum with different types of motors and sensors to characterize the functional parameters: angular position error, mechanical backlash, gearbox efficiency, and lifetime.

  19. International Joint Commission

    NSDL National Science Digital Library

    The International Joint Commission was created by Canada and the United States "because they recognized that each country is affected by the other's actions in lake and river systems along the border. The two countries cooperate to manage these waters wisely and to protect them for the benefit of today's citizens and future generations." Visitors to the site can read about great lakes water quality issues, great lakes exports, water levels, news releases, publications, view maps, and much more. One of the latest publications available on the site includes the proceeding from a workshop entitled Addressing Atmospheric Mercury: Science and Policy. This extensive site is well organized and written, giving anyone living near or interested in the great lakes a good source for timely and important information.

  20. Smart material joint band

    NASA Astrophysics Data System (ADS)

    Tucchio, Michael A.; Stoodt, Robert A.; Livsey, Robert A.

    1993-12-01

    The present invention relates to an improved connector for joining two tubular members together. The connector is formed by a plurality of longitudinally extending fingers extending from an end of one of the tubular members and at least one locking groove in the other of the tubular members for receiving the fingers. The connector further includes a circumferentially extending wire member which is received in a notch in a head portion of each of the plurality of fingers. The wire member is preferably formed from a shape memory alloy and has an original circumference less than the circumference of a circle formed by the notches in the head portions of the fingers. The connector includes apertures through which electric wires may be connected to the shape memory alloy ring member so as to cause the shape memory alloy ring member to return to its original shape and allow release of the joint connection.

  1. Smart material joint band

    NASA Astrophysics Data System (ADS)

    Tucchio, Michael A.; Stoodt, Robert A.; Livsey, Robert A.

    1994-11-01

    The present invention relates to an improved connector for joining two tubular members together. The connector is formed by a plurality of longitudinally extending fingers extending from an end of one of tubular members and at least one locking groove in the other of the tubular members for receiving the fingers. The connector further includes a circumferentially extending wire member which is received in a notch in a head portion of each of the plurality of fingers. The wire member is preferably formed from a shape memory alloy and has an original circumference less than the circumference of a circle formed by the notches in a head portions of the fingers. The connector includes apertures through which electric wires may be connected to the shape memory alloy ring member so as to cause the shape memory alloy ring member to return to its original shape and allow release of the joint connection.

  2. Arthritis at the shoulder joint.

    PubMed

    Sankaye, Prashant; Ostlere, Simon

    2015-07-01

    The shoulder is a complex joint with numerous structures contributing to mobility and stability. Shoulder pain is a common clinical complaint that may be due to a wide spectrum of disorders including rotator cuff disease, instability, and arthropathy. Primary osteoarthritis of the shoulder joint is uncommon because it is a non-weight-bearing joint. Significant osteoarthritis of the glenohumeral joint is unusual in the absence of trauma, and the detection of advanced degenerative changes in patients without a known history of trauma should alert the clinician to search for other disorders. This article reviews the pathogenesis, clinical manifestations, and key imaging findings of the common categories of the arthritis affecting the glenohumeral joint. PMID:26021591

  3. Method of forming a joint

    DOEpatents

    Butt, Darryl Paul; Cutler, Raymond Ashton; Rynders, Steven Walton; Carolan, Michael Francis

    2006-08-22

    A method of joining at least two sintered bodies to form a composite structure, including providing a first multicomponent metallic oxide having a perovskitic or fluorite crystal structure; providing a second sintered body including a second multicomponent metallic oxide having a crystal structure of the same type as the first; and providing at an interface a joint material containing at least one metal oxide containing at least one metal identically contained in at least one of the first and second multicomponent metallic oxides. The joint material is free of cations of Si, Ge, Sn, Pb, P and Te and has a melting point below the sintering temperatures of both sintered bodies. The joint material is heated to a temperature above the melting point of the metal oxide(s) and below the sintering temperatures of the sintered bodies to form the joint. Structures containing such joints are also disclosed.

  4. Domains and Naive Theories

    PubMed Central

    Gelman, Susan A.; Noles, Nicholaus S.

    2013-01-01

    Human cognition entails domain-specific cognitive processes that influence memory, attention, categorization, problem-solving, reasoning, and knowledge organization. This review examines domain-specific causal theories, which are of particular interest for permitting an examination of how knowledge structures change over time. We first describe the properties of commonsense theories, and how commonsense theories differ from scientific theories, illustrating with children’s classification of biological and non-biological kinds. We next consider the implications of domain-specificity for broader issues regarding cognitive development and conceptual change. We then examine the extent to which domain-specific theories interact, and how people reconcile competing causal frameworks. Future directions for research include examining how different content domains interact, the nature of theory change, the role of context (including culture, language, and social interaction) in inducing different frameworks, and the neural bases for domain-specific reasoning. PMID:24187603

  5. 12 CFR 347.107 - Joint ventures.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...2010-01-01 2010-01-01 false Joint ventures. 347.107 Section 347.107...REGULATIONS AND STATEMENTS OF GENERAL POLICY INTERNATIONAL BANKING § 347.107 Joint ventures. (a) Joint ventures. If a bank, directly or...

  6. 29 CFR 791.2 - Joint employment.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Joint employment. 791.2 Section 791...INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS JOINT EMPLOYMENT RELATIONSHIP UNDER FAIR LABOR STANDARDS ACT OF 1938 § 791.2 Joint employment. (a) A single...

  7. 29 CFR 791.2 - Joint employment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Joint employment. 791.2 Section 791...INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS JOINT EMPLOYMENT RELATIONSHIP UNDER FAIR LABOR STANDARDS ACT OF 1938 § 791.2 Joint employment. (a) A single...

  8. 29 CFR 791.2 - Joint employment.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Joint employment. 791.2 Section 791...INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS JOINT EMPLOYMENT RELATIONSHIP UNDER FAIR LABOR STANDARDS ACT OF 1938 § 791.2 Joint employment. (a) A single...

  9. Ferroelectric domain wall injection.

    PubMed

    Whyte, Jonathan R; McQuaid, Raymond G P; Sharma, Pankaj; Canalias, Carlota; Scott, James F; Gruverman, Alexei; Gregg, J Marty

    2014-01-15

    Ferroelectric domain wall injection has been demonstrated by engineering of the local electric field, using focused ion beam milled defects in thin single crystal lamellae of KTiOPO4 (KTP). The electric field distribution (top) displays localized field hot-spots, which correlate with nucleation events (bottom). Designed local field variations can also dictate subsequent domain wall mobility, demonstrating a new paradigm in ferroelectric domain wall control. PMID:24136810

  10. Development of cryogenic rotatable heat transfer joints

    NASA Astrophysics Data System (ADS)

    Sadunas, J. A.; Backovsky, Z. F.; Wilson, D. E.

    1992-07-01

    A summary of cryogenic rotatable heat transfer joint technology development, at Rockwell International Space Division, is presented. Starting with the flight qualified radiative joint on the RM-20B IR sensor of the early 70's, leading to rotatable heat pipe joint, gas conductive joints, rolling-contact-conductance joints, and the more recent work on development and evaluation of cryogenic rotatable seals and mechanical interfaces. Potential applications, joint design optimization, heat transfer, seal leakage and torque test data are presented.

  11. Domain Transfer via Analogy 1 Running head: DOMAIN TRANSFER VIA CROSS-DOMAIN ANALOGY

    E-print Network

    Bustamante, Fabián E.

    Domain Transfer via Analogy 1 Running head: DOMAIN TRANSFER VIA CROSS-DOMAIN ANALOGY Domain Transfer via Cross-Domain Analogy Matthew Klenk and Ken Forbus Qualitative Reasoning Group, Northwestern theories via cross-domain analogy. Our model uses analogies between pairs of textbook example problems

  12. Joint numerical ranges, quantum maps, and joint numerical shadows

    E-print Network

    Eugene Gutkin; Karol Zyczkowski

    2012-10-12

    We associate with k hermitian N\\times N matrices a probability measure on R^k. It is supported on the joint numerical range of the k-tuple of matrices. We call this measure the joint numerical shadow of these matrices. Let k=2. A pair of hermitian N\\times N matrices defines a complex N\\times N matrix. The joint numerical range and the joint numerical shadow of the pair of hermitian matrices coincide with the numerical range and the numerical shadow, respectively, of this complex matrix. We study relationships between the dynamics of quantum maps on the set of quantum states, on one hand, and the numerical ranges, on the other hand. In particular, we show that under the identity resolution assumption on Kraus operators defining the quantum map, the dynamics shrinks numerical ranges.

  13. Domain wall filters

    E-print Network

    Oliver Baer; Rajamani Narayanan; Herbert Neuberger; Oliver Witzel

    2007-03-14

    We propose using the extra dimension separating the domain walls carrying lattice quarks of opposite handedness to gradually filter out the ultraviolet fluctuations of the gauge fields that are felt by the fermionic excitations living in the bulk. This generalization of the homogeneous domain wall construction has some theoretical features that seem nontrivial.

  14. Domain Walls on Singularities

    E-print Network

    Edi Halyo

    2009-10-28

    We describe domain walls that live on $A_2$ and $A_3$ singularities. The walls are BPS if the singularity is resolved and non--BPS if it is deformed and fibered. We show that these domain walls may interpolate between vacua that support monopoles and/or vortices.

  15. The Octagon Abstract Domain

    Microsoft Academic Search

    Antoine Min

    2001-01-01

    This article presents a new numerical abstract domain for static analysis by abstract interpretation. It extends a former numerical abstract domain based on Dierence-Bound Matrices and allows us to represent in- variants of the form ( x y c), where x and y are program variables and c is a real constant. We focus on giving an ecien t representation

  16. The Perceptual Domain.

    ERIC Educational Resources Information Center

    Hooker, Ellen Z.

    For purposes of allied health education applicability, the perceptual domain was examined in terms of (1) its own taxonomy and (2) its relationship to taxonomies in the cognitive, affective, and psychomotor domains. All these taxonomies are hierarchical in style; perception involves extraction of information from presenting stimuli and there is…

  17. Models for jointed rock structures

    NASA Astrophysics Data System (ADS)

    Heuze, F. E.; Barbour, T. G.

    1981-03-01

    Models for axisymmetric interfaces found in shaft and footing designs, and for the dilatant effects of rock joints, as encountered in underground caverns and reinforced rock slopes are presented. The models were incorporated into a finite element program, and test case analyses were performed. Use of the models can lead to safer estimates of footing settlements and shaft lining stresses, as well as to more economical design of rock reinforcement. Because the dilatant joint provides a refined estimate of joint opening and closing, it can be applied to the analysis of hard rock hydraulics, in which the flow is very sensitive to fracture aperture.

  18. Cholesterol Domains Enhance Transfection

    PubMed Central

    Betker, Jamie L.; Kullberg, Max; Gomez, Joe; Anchordoquy, Thomas J.

    2014-01-01

    The formation of cholesterol domains in lipoplexes has been associated with enhanced serum stability and transfection rates both in cell culture and in vivo. This study utilizes the ability of saturated phosphatidylcholines to promote the formation of cholesterol domains at much lower cholesterol contents than have been utilized in previous work. The results show that lipoplexes with identical cholesterol and cationic lipid contents exhibit significantly improved transfection efficiencies when a domain is present, consistent with previous work. In addition, studies assessing transfection rates in the absence of serum demonstrate that the ability of domains to enhance transfection is not dependent on interactions with serum proteins. Consistent with this hypothesis, characterization of the adsorbed proteins composing the corona of these lipoplex formulations did not reveal a correlation between transfection and the adsorption of a specific protein. Finally, we show that the interaction with serum proteins can promote domain formation in some formulations, and thereby result in enhanced transfection only after serum exposure. PMID:23557286

  19. Arthritis: joints inflamed.

    PubMed

    Casey, Georgina

    2015-06-01

    ARTHRITIS IS a generic term for inflammatory joint disease. There are various forms of arthritis, including osteoarthritis, rheumatoid arthritis and spondyloarthritis. Arthritis can be a chronic debilitating condition or a transient effect of bacterial or viral infections. As a chronic condition, arthritis can cause loss of quality of life, disability and, with rheumatoid disease, early death. The economic burden of arthritis, in terms of management and loss of productivity due to disability, is high and set to increase with the ageing population. Recent advances in our understanding of the causes and progression of a number of forms of arthritis have raised hopes of better management and possible remission. Pharmacotherapy has moved from symptom management to addressing underlying disease processes. However, therapies that prevent or cure arthritis remain elusive. Current care for people with arthritis relies on a multidisciplinary approach and substantial pharmacological intervention. Nurses have a key role to play in guiding patients through treatment, ensuring they receive optimal therapy to reduce the impact of arthritis and its management on their lives. PMID:26168559

  20. Acromioclavicular joint cyst formation.

    PubMed

    Hiller, Andrew D; Miller, Joshua D; Zeller, John L

    2010-03-01

    Acromioclavicular joint (ACJ) cysts are an uncommon and unusual sequela associated with shoulder pathophysiology. The majority of literature on ACJ cysts consists of individual case reports with no definitive literature review currently available. In addition to a comprehensive literature review, four clinical cases are presented in this report. First described by Craig (1984), a total of 41 cases have been previously reported in the literature. Of these cases, five occurred with the rotator cuff musculature intact. The remaining 36 cases of ACJ cysts occurred in patients with a complete tear/avulsion of the rotator cuff. Previous attempts at compiling a complete record of all reported cases have combined several distinct conditions into a single category. This article presents two distinct etiologies for the pathogenesis of ACJ cyst formation. In the presence of an intact rotator cuff, a Type 1 cyst can form superficially and be limited to the ACJ. Following a massive or traumatic tear of the rotator cuff, mechanical instability of the humeral head can cause a deterioration of the inferior acromioclavicular capsule (cuff tear arthropathy) and an overproduction of synovial fluid. Overtime, a "geyser" of fluid can form between the glenohumeral and the ACJ, forming a Type 2 cyst. This differentiation and categorization is essential for appropriate classification and treatment. PMID:20069645

  1. Osteochondral Lesions of Major Joints

    PubMed Central

    Durur-Subasi, Irmak; Durur-Karakaya, Afak; Yildirim, Omer Selim

    2015-01-01

    This paper provides information about osteochondral lesions (OCL) and example cases of OCL occurring in major joints, some of which are rarely seen. This simple tutorial is presented in question and answer format. PMID:26180500

  2. MISR JOINT_AS Data

    Atmospheric Science Data Center

    2014-07-21

    ... reported on various geographic grids depending on the data product. Parameters from multiple orbits are combined to make complete ... The Joint Aerosol product provides a monthly global statistical summary of MISR Level 2 aerosol optical depth retrievals on a 5 ...

  3. The complexity of joint computation

    E-print Network

    Drucker, Andrew Donald

    2012-01-01

    Joint computation is the ubiquitous scenario in which a computer is presented with not one, but many computational tasks to perform. A fundamental question arises: when can we cleverly combine computations, to perform them ...

  4. Towards automatization of domain modeling

    Microsoft Academic Search

    Iris Reinhartz-Berger

    2010-01-01

    A domain model, which captures the common knowledge and the possible variability allowed among applications in a domain, may assist in the creation of other valid applications in that domain. However, to create such domain models is not a trivial task: it requires expertise in the domain, reaching a very high level of abstraction, and providing flexible, yet formal, artifacts.

  5. Joint probabilities and quantum cognition

    NASA Astrophysics Data System (ADS)

    de Barros, J. Acacio

    2012-12-01

    In this paper we discuss the existence of joint probability distributions for quantumlike response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.

  6. Joint probabilities and quantum cognition

    SciTech Connect

    Acacio de Barros, J. [Liberal Studies, 1600 Holloway Ave., San Francisco State University, San Francisco, CA 94132 (United States)

    2012-12-18

    In this paper we discuss the existence of joint probability distributions for quantumlike response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.

  7. Blood-Induced Joint Damage

    PubMed Central

    Roosendaal, Goris; Jansen, Nathalie W.D.; Lafeber, Floris P.J.G.; Mastbergen, Simon C.

    2013-01-01

    Objective: Four days of blood exposure leads to irreversible cartilage damage in vitro. In contrast, intermittent intra-articular blood injections twice a week during 4 weeks (mimicking micro-bleeds) in a canine model resulted in transient damage only. In this study, it was evaluated whether acute joint bleeds are more harmful than micro-bleeds in a canine model of knee arthropathy. Design: Seven dogs received 4 sequential daily intra-articular blood injections twice in 2 weeks (mimicking 2 acute 4-day joint bleeds). Seven other dogs received the same blood load but in a total of 8 injections intermittently over the 4-week period with at least 1 day in between (mimicking micro-bleeds over the same timespan). Contralateral knees served as controls. Ten weeks after the last injection cartilage matrix turnover and synovial inflammation were evaluated. Results: Only after the acute joint bleeds the release of newly formed and total (resident) cartilage matrix glycosaminoglycans were increased (P = 0.04 and P = 0.01, respectively). Furthermore, in animals with the acute joint bleeds cartilage glycosaminoglycan content was decreased (P = 0.01) and not in animals with micro-bleeds. Mild synovial inflammation was observed in both groups (both P < 0.0001) but was not different between groups. Conclusions: In contrast to micro-bleeds, 2 acute joint bleeds lead to prolonged cartilage damage independent of the level of synovial inflammation. This model suggests that micro-bleeds are less devastating than acute joint bleeds with respect to joint damage, which might be of relevance to treatment of joint bleeds in clinical practice.

  8. Joint probabilities and quantum cognition

    E-print Network

    de Barros, J Acacio

    2012-01-01

    In this paper we discuss the existence of joint probability distributions for quantum-like response computations in the brain. We do so by focusing on a contextual neural-oscillator model shown to reproduce the main features of behavioral stimulus-response theory. We then exhibit a simple example of contextual random variables not having a joint probability distribution, and describe how such variables can be obtained from neural oscillators, but not from a quantum observable algebra.

  9. Stability of domain structures in multi-domain proteins

    PubMed Central

    Bhaskara, Ramachandra M.; Srinivasan, Narayanaswamy

    2011-01-01

    Multi-domain proteins have many advantages with respect to stability and folding inside cells. Here we attempt to understand the intricate relationship between the domain-domain interactions and the stability of domains in isolation. We provide quantitative treatment and proof for prevailing intuitive ideas on the strategies employed by nature to stabilize otherwise unstable domains. We find that domains incapable of independent stability are stabilized by favourable interactions with tethered domains in the multi-domain context. Stability of such folds to exist independently is optimized by evolution. Specific residue mutations in the sites equivalent to inter-domain interface enhance the overall solvation, thereby stabilizing these domain folds independently. A few naturally occurring variants at these sites alter communication between domains and affect stability leading to disease manifestation. Our analysis provides safe guidelines for mutagenesis which have attractive applications in obtaining stable fragments and domain constructs essential for structural studies by crystallography and NMR. PMID:22355559

  10. Supporting the joint warfighter by development, training, and fielding of man-portable UGVs

    Microsoft Academic Search

    Kenneth A. Ebert; Benjamin V. Stratton

    2005-01-01

    The Robotic Systems Pool (RSP), sponsored by the Joint Robotics Program (JRP), is an inventory of small robotic systems, payloads, and components intended to expedite the development and integration of technology into effective, supportable, fielded robotic assets. The RSP loans systems to multiple users including the military, first-responders, research organizations, and academia. These users provide feedback in their specific domain,

  11. 5, 163185, 2008 Joint effect of the

    E-print Network

    Paris-Sud XI, Université de

    investigated. Joint effect of the WPWP and EPWP on ENSO was examined based on a joint effect index, which by the WPWP and EPWP on ENSO, and the joint effect of both warm pools must be considered. A joint index of 1 global climate abnormity and serious drought or flood, and cold calamity in many regions of the world

  12. Acromioclavicular joint reconstruction: complications and innovations.

    PubMed

    Brand, Jefferson C; Lubowitz, James H; Provencher, Matthew T; Rossi, Michael J

    2015-05-01

    Minimally invasive anatomic reconstruction of the acromioclavicular joint is a technically challenging procedure. The repair must be sufficiently strong and reconstitute the joint as closely as possible. This includes restoration of both superior-inferior stability, and the often overlooked anterior-posterior stability, of the acromioclavicular joint. There is no gold standard treatment for acromioclavicular joint separation. PMID:25953219

  13. Degenerative joint disease in captive waterfowl

    Microsoft Academic Search

    L. A. Degernes; P. S. Lynch; H. L. Shivaprasad

    2011-01-01

    A retrospective study was conducted to evaluate degenerative joint disease (DJD) in captive waterfowl that died or were euthanized at Fresno's Chaffee Zoo in Fresno, California, USA from 2001 to 2005. Of these, 16 out of 33 birds (48%) had DJD in one or both stifle (femoral–tibiotarsal joint; n = 13), hock (tibiotarsal–tarsometatarsal joint; n = 4), or toe joints

  14. Young Children's Understanding of Joint Commitments

    ERIC Educational Resources Information Center

    Grafenhain, Maria; Behne, Tanya; Carpenter, Malinda; Tomasello, Michael

    2009-01-01

    When adults make a joint commitment to act together, they feel an obligation to their partner. In 2 studies, the authors investigated whether young children also understand joint commitments to act together. In the first study, when an adult orchestrated with the child a joint commitment to play a game together and then broke off from their joint

  15. 7 CFR 97.14 - Joint applicants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Agriculture 3 2012-01-01 2012-01-01 false Joint applicants. 97.14 Section 97.14 Agriculture...VARIETY AND PROTECTION The Application § 97.14 Joint applicants. (a) Joint owners shall file a joint application by...

  16. Joint Press Release TWELFTH ITER NEGOTIATION MEETING

    E-print Network

    Joint Press Release TWELFTH ITER NEGOTIATION MEETING Jeju, Korea, 6 December th 2005 Delegations on an Agreement on the joint implementation of the ITER international fusion energy project. This was the first/6/05 1:21 PMDraft Joint News Release Page 1 of 2http://www.iter.org/N_12_Joint_Press_Release.htm #12

  17. 7 CFR 97.14 - Joint applicants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Agriculture 3 2014-01-01 2014-01-01 false Joint applicants. 97.14 Section 97.14 Agriculture...VARIETY AND PROTECTION The Application § 97.14 Joint applicants. (a) Joint owners shall file a joint application by...

  18. 7 CFR 97.14 - Joint applicants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...Agriculture 3 2011-01-01 2011-01-01 false Joint applicants. 97.14 Section 97.14 Agriculture...VARIETY AND PROTECTION The Application § 97.14 Joint applicants. (a) Joint owners shall file a joint application by...

  19. 7 CFR 97.14 - Joint applicants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Agriculture 3 2013-01-01 2013-01-01 false Joint applicants. 97.14 Section 97.14 Agriculture...VARIETY AND PROTECTION The Application § 97.14 Joint applicants. (a) Joint owners shall file a joint application by...

  20. Supersymmetric Domain Walls

    E-print Network

    Eric A. Bergshoeff; Axel Kleinschmidt; Fabio Riccioni

    2012-06-25

    We classify the half-supersymmetric "domain walls", i.e. branes of codimension one, in toroidally compactified IIA/IIB string theory and show to which gauged supergravity theory each of these domain walls belong. We use as input the requirement of supersymmetric Wess-Zumino terms, the properties of the E11 Kac-Moody algebra and the embedding tensor formalism. We show that the number of half-supersymmetric domain walls is a multiple of the number of corresponding central charges in the supersymmetry algebra, where the multiplicity is related to the degeneracy of the BPS conditions.

  1. A Domain-Specific Modelling Approach for Autonomic Network Management

    Microsoft Academic Search

    Brian Pickering; Miguel A. Fernández; Antonio Castillo; Erhan Mengusoglu

    2008-01-01

    This paper describes IBM’s and Telefónica’s joint work in progress in the field of Domain-Specific Modelling applied to Autonomic\\u000a Network Management in the context of the European IST FP6 project MODELPLEX. In modelling edge-of-network devices which act\\u000a as service access points from consumers to the telephone network, we have introduced a dynamic aspect to the network topology\\u000a which affects the

  2. Twist-joints and double twist-joints in RNA structure

    PubMed Central

    Boutorine, Yury I.; Steinberg, Sergey V.

    2012-01-01

    Analysis of available RNA crystal structures has allowed us to identify a new family of RNA arrangements that we call double twist-joints, or DTJs. Each DTJ is composed of a double helix that contains two bulges incorporated into different strands and separated from each other by 2 or 3 bp. At each bulge, the double helix is over-twisted, while the unpaired nucleotides of both bulges form a complex network of stacking and hydrogen-bonding with nucleotides of helical regions. In total, we identified 14 DTJ cases, which can be combined in three groups based on common structural characteristics. One DTJ is found in a functional center of the ribosome, another DTJ mediates binding of the pre-tRNA to the RNase P, and two more DTJs form the sensing domains in the glycine riboswitch. PMID:23060425

  3. How joint is the joint attention of apes and human infants? Malinda Carpenter

    E-print Network

    Carpenter, M.alinda

    How joint is the joint attention of apes and human infants? Malinda Carpenter Josep Call Department In press, Agency and joint attention, H.S. Terrace & J. Metcalfe (Eds.). New York: Oxford University Press. #12;The jointness of joint attention 2 Abstract In this chapter we first argue (following Tomasello

  4. Joint services electronics program

    NASA Astrophysics Data System (ADS)

    Peters, Leon, Jr.

    1993-11-01

    The transfer of the compact range and target identification technology initiated under JSEP support for time domain studies continues to make large advances. The installation of a large compact reflector and a modern radar of our design has been completed for ASD at Wright Patterson Air Force Base. This system will have all of the sensitivity of the Mini Range reported last year and yet has a 14 ft quiet (or target) zone. The reflector includes all the most updated features of the ESL design. Dr. Brian Kent of ASD has expressed complete satisfaction with its performance. It is the range we would like to have, but can never afford. A large even more advanced compact range is currently being designed for NASA, Langley which is specifically being focused for measurements as low as 300 MHz. This new range will fit in a room 40 ft x 40 ft x 80 ft instead of the previously required 120 ft x 120 ft x 360 ft. The cost savings in this care are enormous. Our JSEP research continues to focus on electromagnetic related topics.

  5. Visualizing Knowledge Domains.

    ERIC Educational Resources Information Center

    Borner, Katy; Chen, Chaomei; Boyack, Kevin W.

    2003-01-01

    Reviews visualization techniques for scientific disciplines and information retrieval and classification. Highlights include historical background of scientometrics, bibliometrics, and citation analysis; map generation; process flow of visualizing knowledge domains; measures and similarity calculations; vector space model; factor analysis;…

  6. An analysis of a joint shear model for jointed media with orthogonal joint sets; Yucca Mountain Site Characterization Project

    SciTech Connect

    Koteras, J.R.

    1991-10-01

    This report describes a joint shear model used in conjunction with a computational model for jointed media with orthogonal joint sets. The joint shear model allows nonlinear behavior for both joint sets. Because nonlinear behavior is allowed for both joint sets, a great many cases must be considered to fully describe the joint shear behavior of the jointed medium. An extensive set of equations is required to describe the joint shear stress and slip displacements that can occur for all the various cases. This report examines possible methods for simplifying this set of equations so that the model can be implemented efficiently form a computational standpoint. The shear model must be examined carefully to obtain a computationally efficient implementation that does not lead to numerical problems. The application to fractures in rock is discussed. 5 refs., 4 figs.

  7. Eigenvalue sensitivity analysis of planar frames with variable joint and support locations

    NASA Technical Reports Server (NTRS)

    Chuang, Ching H.; Hou, Gene J. W.

    1991-01-01

    Two sensitivity equations are derived in this study based upon the continuum approach for eigenvalue sensitivity analysis of planar frame structures with variable joint and support locations. A variational form of an eigenvalue equation is first derived in which all of the quantities are expressed in the local coordinate system attached to each member. Material derivative of this variational equation is then sought to account for changes in member's length and orientation resulting form the perturbation of joint and support locations. Finally, eigenvalue sensitivity equations are formulated in either domain quantities (by the domain method) or boundary quantities (by the boundary method). It is concluded that the sensitivity equation derived by the boundary method is more efficient in computation but less accurate than that of the domain method. Nevertheless, both of them in terms of computational efficiency are superior to the conventional direct differentiation method and the finite difference method.

  8. Time and frequency domain responses of the mechanomyogram and electromyogram during isometric ramp contractions: A comparison of the short-time Fourier and continuous wavelet transforms

    Microsoft Academic Search

    Eric D. Ryan; Joel T. Cramer; Alison D. Egan; Michael J. Hartman; Trent J. Herda

    2008-01-01

    The purposes of this study were to examine the mechanomyographic (MMG) and electromyographic (EMG) time and frequency domain responses of the vastus lateralis (VL) and rectus femoris (RF) muscles during isometric ramp contractions and compare the time–frequency of the MMG and EMG signals generated by the short-time Fourier transform (STFT) and continuous wavelet transform (CWT). Nineteen healthy subjects (mean±SD age=24±4

  9. Time and frequency-domain spreading assisted MC DS-CDMA using interference rejection spreading codes for quasi-synchronous communications

    Microsoft Academic Search

    Hua Wei; Lie-Liang Yang; Lajos Hanzo

    2004-01-01

    In this contribution, we considered a time-frequency (TF)-domain spreading aided MC DS-CDMA system, which employed so-called generalized orthogonal spreading codes exhibiting an interference free window (IFW). Provided that the propagation delay differences of the different users are within this IFW, no multiuser interference is inflicted, and hence a near-single-user performance may be attained without invoking a multiuser detector. As an

  10. Unsharp measurements and joint measurability

    E-print Network

    H. S. Karthik; A. R. Usha Devi; A. K. Rajagopal

    2015-05-16

    We give an overview of joint unsharp measurements of non-commuting observables using positive operator valued measures (POVMs). We exemplify the role played by joint measurability of POVMs in entropic uncertainty relation for Alice's pair of non-commuting observables in the presence of Bob's entangled quantum memory. We show that Bob should record the outcomes of incompatible (non-jointly measurable) POVMs in his quantum memory so as to beat the entropic uncertainty bound. In other words, in addition to the presence of entangled Alice-Bob state, implementing incompatible POVMs at Bob's end is necessary to beat the uncertainty bound and hence, predict the outcomes of non-commuting observables with improved precision. We also explore the implications of joint measurability to {\\em validate} a moment matrix constructed from average pairwise correlations of three dichotomic non-commuting qubit observables. We prove that a classically acceptable moment matrix -- which ascertains the existence of a legitimate joint probability distribution for the outcomes of all the three dichotomic observables -- could be realized if and only if compatible POVMs are employed.

  11. Strength of welded copper joints

    SciTech Connect

    Kuzyukova, A.N.; Fedorenko, M.I.; Kovalenko, N.I.; Zelik, E.I.

    1983-07-01

    A coefficient of the strength of welded joints in structures of copper and its alloys made by manual arc welding are known. At the Severedonetsk Branch of the Institute of Chemical Engineering the strength coefficients were determined for welded joints made of MZR (phosphorous-deoxydized) copper produced by manual argonarc welding. Optimum welding regimes were selected, and specimens of strips tested for tensile strength. Metallographic investigations showed significant grain growth in the zone of thermal influence. The results of mechanical tests are given. The results are verified by the fabrication of nine models. All the models ruptured in the zone of thermal influence, confirming results that the zone of thermal influence was the weak point in the welded joints in copper.

  12. PROTCOM:searchabledatabaseofproteincomplexes enhanced with domain-domain structures

    Microsoft Academic Search

    Petras J. Kundrotas; Emil Alexov

    The database of protein complexes (PROTCOM) is a compilation of known 3D structures of protein- protein complexes enriched with artificially created domain-domain structures using the available ent- ries in the Protein Data Bank. The domain-domain structures are generated by parsing single chain structures into loosely connected domains and are important features of the database. The data- base (http:\\/\\/www.ces.clemson.edu\\/compbio\\/protcom) could be

  13. Domain adduced state tying for cross-domain acoustic modelling

    Microsoft Academic Search

    Rita Singh; Bhiksha Raj; Richard M. Stern

    1999-01-01

    In situations when automatic speech recognition (ASR) sys- tems are rapidly deployed for a new task, the availability of within-domain training data may be limited. In such cases one needs to build the ASR system from other, possibly out-of-domain databases. We refer to the process of building ASR systems for one task domain using data from other domains as cross-domain

  14. Joint service EOD robotics program

    NASA Astrophysics Data System (ADS)

    Hacker, Kurt; Brezina, Byron; DeBolt, Chris

    2006-05-01

    Within the military, the Explosive Ordnance Disposal (EOD) community has been an early adopter of robotic capabilities. The Joint Service EOD (JSEOD) Program is in the process of fielding its third generation of robotic systems to the EOD technicians. Robots have been an invaluable asset to the EOD technician, and they have been critical to operations in Iraq as we prosecute the IED problem. This paper provides a brief history of past EOD robotic systems, a description of currently fielded and supported systems, and the future of robotic programs within the Joint Service EOD community.

  15. [Divorce and joint physical custody].

    PubMed

    Golse, B

    2014-04-01

    This work first recalls the definition of joint physical custody, as well as the current legal procedure for obtaining it, its practical implementation, the financial implications for parents, and finally some statistics. Some psychological and psychopathological reflections on the impact of divorce on children are then presented before considering the question of joint physically custody with regard to attachment theory and depending on the age of the child (a great caution seems to be required before three years). The article concludes with a brief discussion of parental alienation syndrome. PMID:24630624

  16. Domain Representability of Metric Spaces

    Microsoft Academic Search

    Jens Blanck

    1997-01-01

    We show that metric spaces and continuous functions between them are domain representable using the category of Scott-Ershov domains. A notion of effectivity for metric spaces is thereby inherited from effective domain theory. It is shown that a separable metric space with an effective metric can be represented by an effective domain. For a class of spaces, including the Euclidean

  17. Atomic Pseudo-Valuation Domains

    E-print Network

    Stines, Elijah

    2012-01-01

    Pseudo-valuation domains have been studied since their introduction in 1978 by Hedstrom and Houston. Related objects, boundary valuation domains, were introduced by Maney in 2004. Here, it is shown that the class of atomic pseudo-valuation domains coincides with the class of boundary valuation domains. It is also shown that power series rings and generalized power series rings give examples of pseudo-valuation domains whose congruence lattices can be characterized. The paper also introduces, and makes use of, a sufficient condition on the group of divisibility of a domain to guarantee that it is a pseudo-valuation domain.

  18. The Application of Auto-Disturbance Rejection Control Optimized by Least Squares Support Vector Machines Method and Time-Frequency Representation in Voltage Source Converter-High Voltage Direct Current System

    PubMed Central

    Gao, Zhong-Ke

    2015-01-01

    In order to improve the performance of voltage source converter-high voltage direct current (VSC-HVDC) system, we propose an improved auto-disturbance rejection control (ADRC) method based on least squares support vector machines (LSSVM) in the rectifier side. Firstly, we deduce the high frequency transient mathematical model of VSC-HVDC system. Then we investigate the ADRC and LSSVM principles. We ignore the tracking differentiator in the ADRC controller aiming to improve the system dynamic response speed. On this basis, we derive the mathematical model of ADRC controller optimized by LSSVM for direct current voltage loop. Finally we carry out simulations to verify the feasibility and effectiveness of our proposed control method. In addition, we employ the time-frequency representation methods, i.e., Wigner-Ville distribution (WVD) and adaptive optimal kernel (AOK) time-frequency representation, to demonstrate our proposed method performs better than the traditional method from the perspective of energy distribution in time and frequency plane. PMID:26098556

  19. Department of Defense Joint Robotics Program

    NASA Astrophysics Data System (ADS)

    Toscano, Michael

    2000-07-01

    The objective of the Joint Robotics Program (JRP) is to conduct research, development, acquisition and fielding within the domain of unmanned ground vehicle systems for a wide range of military applications. The program is structured to field first generation systems, mature promising technologies and then upgrade capabilities by means of an evolutionary strategy. In the near term, acquisition programs emphasize teleoperation over diverse terrain, more autonomous functioning for structured environments, and extensive opportunities for users to operate UGV's. Autonomous mobility in unstructured environments i sthe main thrust of the JRP technology base. Recently, the Demo III program held a highly successful demonstration of autonomous mobility at Aberdeen Proving Ground, MD. Other successes with prototypical countermine systems in Bosnia, as well as soldiers' and Marines' experimentation with reconnaissance unmanned ground vehicles (UGVs) continue to engender requirements in other areas. Users are developing requirements for UGGVs that convoy with manned vehicles; carry and deliver supplies; carry and employ weapons; can be carried in a backpack and conduct reconnaissance inside multi-story buildings. The overall progress of the JRP is reflected in the fact that Services have identified procurement funding to buy UGVs. The author will update the conference on the considerable progress of the JRP, which is preparing to provide our Armed Forces with a lead-ahead capability for the 21st Century.

  20. Joint service EOD robotics program

    Microsoft Academic Search

    Kurt Hacker; Byron Brezina; Chris DeBolt

    2006-01-01

    Within the military, the Explosive Ordnance Disposal (EOD) community has been an early adopter of robotic capabilities. The Joint Service EOD (JSEOD) Program is in the process of fielding its third generation of robotic systems to the EOD technicians. Robots have been an invaluable asset to the EOD technician, and they have been critical to operations in Iraq as we

  1. OBSERVATION DIRECT DES JOINTS INTERGRANULAIRES.

    E-print Network

    Boyer, Edmond

    OF INTERFACES D. A. SMITH Department of Metallurgy, University of Oxford, Parks Road, Oxford, England. RCsum6 interfaciales conservent I'ordre dans les joints et leurs propriCtCs peuvent contrbler les processus qui se transmission electron microscopy. Interfacial dislocations conserve the order at boundaries and their behaviour

  2. [Metabolic bone and joint diseases].

    PubMed

    Endo, Itsuro

    2014-10-01

    Metabolic bone and joint diseases in adults include osteomalacia, rheumatoid arthritis, gouty arthritis. Recently, the newest molecular biology procedures and the clinical observation studies can produce good results for understanding of these diseases. From this perspective, the author introduced updated information of the pathophysiology, the latest diagnostic criteria and the therapy of these diseases. PMID:25509803

  3. Space station rotary joint mechanisms

    NASA Technical Reports Server (NTRS)

    Driskill, Glen W.

    1986-01-01

    The mechanism which will be used on the space station to position the solar arrays and radiator panels for Sun pointing and Sun avoidance is described. The unique design features will be demonstrated on advanced development models of two of the joints being fabricated under contract to NASA-MSFC.

  4. [Fetal bone and joint disorders].

    PubMed

    Jakobovits, Akos

    2008-12-21

    The article discusses the physiology and pathology of fetal bone and joint development and functions. The bones provide static support for the body. The skull and the bones of spinal column encase the central and part of the peripheral nervous system. The ribs and the sternum shield the heart and the lungs, while the bones of the pelvis protect the intraabdominal organs. Pathological changes of these bony structures may impair the functions of the respective systems or internal organs. Movements of the bones are brought about by muscles. The deriving motions are facilitated by joints. Bony anomalies of the extremities limit their effective functions. Apart from skeletal and joint abnormalities, akinesia may also be caused by neurological, muscular and skin diseases that secondarily affect the functions of bones and joints. Such pathological changes may lead to various degrees of physical disability and even to death. Some of the mentioned anomalies are recognizable in utero by ultrasound. The diagnosis may serve as medical indication for abortion in those instances when the identified abnormality is incompatible with independent life. PMID:19073454

  5. Offered jointly with International Business

    E-print Network

    Offered jointly with Master in International Business #12;.02 Welcome to Barcelona Welcome to UPF where business, culture and social life drive the community. Barcelona has one of the world's highest. Master in International Business #12;ESCI, Escola Superior de Comerç Internacional www.esci.upf.edu .03

  6. JD MADR Joint Degree Description

    E-print Network

    Berdichevsky, Victor

    ) are considered equivalent to two core MADR courses, DR 7220 (Neutral Intervention) and DR 7210 (Negotiation (Alternative Dispute Resolution) are equivalent, to the core MADR courses of DR 7210 (Negotiation), DR 7220. Sample Schedule For JD/MADR Joint Degree YEAR 1: Fall Semester Total Cr. JD Cr. MADR Cr. LEX 6100 - Civil

  7. Plating To Reinforce Welded Joints

    NASA Technical Reports Server (NTRS)

    Otousa, J. E.

    1982-01-01

    Electrodeposition used to strengthen welded joints gouged, nicked, or suffered other mechanical damage. Plating cell, typically of acrylic plastic such as poly (Methylmetacrylate), is assembled around part to be plated. Areas not to be plated are masked with plater's tape. Weld area is plated in standard nickel-plating process.

  8. Methods of jointing ceramic pipes

    Microsoft Academic Search

    I. I. Arkhipov; Z. O. Nemchenok

    1975-01-01

    In Czechoslovakia the ceramic pipes are jointed with the help of rubber sealing rings. The rings have a reinforced core and two internal flaps. In the cuff of the ring a steel reinforcement is pressed which hinders its deformation during mounting. The ring has a conical shape and when installed in the neck of a pipe, it clamps by itself.

  9. The Joint Gravity Model 3

    Microsoft Academic Search

    B. D. Tapley; M. M. Watkins; J. C. Ries; G. W. Davis; R. J. Eanes; S. R. Poole; H. J. Rim; B. E. Schutz; C. K. Shum; R. S. Nerem; F. J. Lerch; J. A. Marshall; S. M. Klosko; N. K. Pavlis; R. G. Williamson

    1996-01-01

    An improved Earth geopotential model, complete to spherical harmonic degree and order 70, has been determined by combining the Joint Gravity Model 1 (JGM 1) geopotential coefficients, and their associated error covariance, with new information from SLR, DORIS, and GPS tracking of TOPEX\\/Poseidon, laser tracking of LAGEOS 1, LAGEOS 2, and Stella, and additional DORIS tracking of SPOT 2. The

  10. Chicken Skeleton - Gliding Joint (Skull)

    NSDL National Science Digital Library

    Ketan Patel (California State University, Fullerton; Student, Biological Sciences)

    2007-07-28

    The chicken uses its beak to pick up small pieces of food from the ground. The gliding joint at the base of the skull allows the chicken to move its head in different directions. It can also defend itself by pecking.

  11. Sea Lion Skeleton (Gliding Joint)

    NSDL National Science Digital Library

    Ketan Patel (California State University, Fullerton; Student, B)

    2007-07-14

    Sea lions are vertebrates with both backbones and ribs. The backbone is a gliding joint, allowing the animal to be flexible, while the ribs main function is to protect it's inner organs. The short tail helps to balance the animal while walking on land.

  12. Joint measurements and Svetlichny's inequality

    E-print Network

    Yang Xiang; Wei Ren

    2010-12-27

    We prove that the Svetlichny's inequality can be derived from the existence of joint measurements and the principle of no-signaling. Then we show that, on the basis of quantum measurement assumption, it would imply the breach of causality if the magnitude of violation of Svetlichny's inequality exceeds quantum bound.

  13. Tests on riveted joints in sheet duralumin

    NASA Technical Reports Server (NTRS)

    Rettew, H F; Thumin, G

    1923-01-01

    In making tension tests, the slippage of the joints was noted at three points across each joint. In addition, stress strain curves were obtained for plain tension specimens, and a chemical analysis was made of the sheet.

  14. Joint Disorders - Multiple Languages: MedlinePlus

    MedlinePLUS

    ... ?????????? ?????? ??????? - ??????? Bilingual PDF Health Information Translations Bosnian (Bosanski) Home Care After Total Joint Replacement ... zamjene zgloba - Bosanski (Bosnian) Bilingual PDF Health Information Translations Chinese - Simplified (????) Home Care After Total Joint ...

  15. 30 CFR 36.24 - Engine joints.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...OF MINING PRODUCTS APPROVAL REQUIREMENTS FOR PERMISSIBLE MOBILE DIESEL-POWERED TRANSPORTATION EQUIPMENT Construction and Design Requirements § 36.24 Engine joints. (a) Cylinder head. The joint between the cylinder...

  16. 30 CFR 36.24 - Engine joints.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...OF MINING PRODUCTS APPROVAL REQUIREMENTS FOR PERMISSIBLE MOBILE DIESEL-POWERED TRANSPORTATION EQUIPMENT Construction and Design Requirements § 36.24 Engine joints. (a) Cylinder head. The joint between the cylinder...

  17. Shear-Joint Capability Versus Bolt Clearance

    NASA Technical Reports Server (NTRS)

    Lee, H. M.

    1994-01-01

    NASA Technical Memorandum presents theoretical study of relationships between load-bearing capabilities of shear joints that comprise plates clamped together by multiple bolts and clearances between bolts and boltholes in those joints.

  18. A method for classifying underground targets and simultaneously estimating their burial conditions

    Microsoft Academic Search

    H. C. Strifors; T. Andersson; D. Axelsson; G. C. Gaunaurd

    2005-01-01

    Ultra-wideband ground penetrating radar (GPR) systems are useful for extracting and displaying information for target recognition purposes. The frequency content of projected signals is designed to match the size and type of prospective targets and environments. Target signatures whether in the time, frequency, or joint time-frequency domains, will substantially depend on the target's burial conditions such as the type of

  19. Observation of ferrotoroidic domains.

    PubMed

    Van Aken, Bas B; Rivera, Jean-Pierre; Schmid, Hans; Fiebig, Manfred

    2007-10-11

    Domains are of unparalleled technological importance as they are used for information storage and for electronic, magnetic and optical switches. They are an essential property of any ferroic material. Three forms of ferroic order are widely known: ferromagnetism, a spontaneous magnetization; ferroelectricity, a spontaneous polarization; and ferroelasticity, a spontaneous strain. It is currently debated whether to include an ordered arrangement of magnetic vortices as a fourth form of ferroic order, termed ferrotoroidicity. Although there are reasons to expect this form of order from the point of view of thermodynamics, a crucial hallmark of the ferroic state--that is, ferrotoroidic domains--has not hitherto been observed. Here ferrotoroidic domains are spatially resolved by optical second harmonic generation in LiCoPO4, where they coexist with independent antiferromagnetic domains. Their space- and time-asymmetric nature relates ferrotoroidics to multiferroics with magnetoelectric phase control and to other systems in which space and time asymmetry leads to possibilities for future applications. PMID:17928856

  20. Time-domain imaging

    NASA Technical Reports Server (NTRS)

    Tolliver, C. L.

    1989-01-01

    The quest for the highest resolution microwave imaging and principle of time-domain imaging has been the primary motivation for recent developments in time-domain techniques. With the present technology, fast time varying signals can now be measured and recorded both in magnitude and in-phase. It has also enhanced our ability to extract relevant details concerning the scattering object. In the past, the interface of object geometry or shape for scattered signals has received substantial attention in radar technology. Various scattering theories were proposed to develop analytical solutions to this problem. Furthermore, the random inversion, frequency swept holography, and the synthetic radar imaging, have two things in common: (1) the physical optic far-field approximation, and (2) the utilization of channels as an extra physical dimension, were also advanced. Despite the inherent vectorial nature of electromagnetic waves, these scalar treatments have brought forth some promising results in practice with notable examples in subsurface and structure sounding. The development of time-domain techniques are studied through the theoretical aspects as well as experimental verification. The use of time-domain imaging for space robotic vision applications has been suggested.

  1. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc (Davis, CA); Doi, Roy (Davis, CA)

    1998-01-01

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production thereof. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques.

  2. Cellulose binding domain proteins

    DOEpatents

    Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

    1998-11-17

    A cellulose binding domain (CBD) having a high affinity for crystalline cellulose and chitin is disclosed, along with methods for the molecular cloning and recombinant production. Fusion products comprising the CBD and a second protein are likewise described. A wide range of applications are contemplated for both the CBD and the fusion products, including drug delivery, affinity separations, and diagnostic techniques. 16 figs.

  3. Metaprogramming Domain Specific Metaprograms

    Microsoft Academic Search

    Tristan Cazenave

    1999-01-01

    When a metaprogram automatically creates rules, some c reated rules are useless because they can never apply. Some metarules, that we call impossibility metarules, are used to remove useless rules. Some of these metarules are general and apply to any generated program. Some are domain specific metarules. In this paper, we show how dynamic metaprogramming can b e used to

  4. Capacity prediction of welded timber joints

    Microsoft Academic Search

    Till Vallée; Thomas Tannert; Christelle Ganne-Chedville

    Linear vibration welding of timber structural elements provides new opportunities to potentially achieve structural joints.\\u000a This paper investigates to which extent welded joints can be considered for load-bearing structural joints. On the basis of\\u000a a series of experimental and numerical investigations on a series of welded single-lap joints, failure modes were identified,\\u000a and the associated failure criterion was quantified. A

  5. Dynamic measurement of inside strain distributions in adhesively bonded joints by embedded fiber Bragg grating sensor

    NASA Astrophysics Data System (ADS)

    Murayama, Hideaki; Ning, Xiaoguang; Kageyama, Kazuro; Wada, Daichi; Igawa, Hirotaka

    2014-05-01

    Long-length fiber Bragg grating (FBG) with the length of about 100 mm was embedded onto the surface of a carbon fiber reinforced plastics (CFRP) substrate and two CFRP adherends were joined by adhesive to form an adhesive bonded single-lap joint. The joint was subjected to 0.5 Hz cyclic tensile load and longitudinal strain distributions along FBG were measured at 5 Hz by the fiber-optic distributed sensing system based on optical frequency domain reflectometry (OFDR). We could successfully monitor the strain distributions accurately with high spatial resolution of around 1 mm.

  6. Biomechanical considerations in patellofemoral joint rehabilitation

    Microsoft Academic Search

    Lisa A. Steinkamp; Michael F. Dillingham; Mark D. Markel; Jennifer A. Hill; Kenton R. Kaufman

    1993-01-01

    Patellofemoral joint biomechanics during leg press and leg extension exercises were compared in 20 normal subjects (10 men, 10 women) aged 18 to 45 years. Knee moment, patellofemoral joint reaction force, and patellofemoral joint stress were calculated for each subject at four knee flexion angles (0°, 30°, 60°, and 90°) during leg press and leg extension exercises.All three parameters (knee

  7. of Concrete Pavements Joint PerformanCe

    E-print Network

    practitioners under- stand how to optimize concrete pavement joint perfor- mance through the identificationof Concrete Pavements Joint PerformanCe interim Guide for optimum JUNE 2012 #12;#12;Interim Guide for Optimum Joint Performance of Concrete Pavements i Technical Report Documentation Page 1. Report No. 2

  8. New insights in critical solder joint location

    Microsoft Academic Search

    Mitul Modi; Carolyn McCormick; Norman Armendariz

    2005-01-01

    Current numerical modeling approaches to assess BGA solder joint thermal mechanical fatigue, typically identify the max DNP (distance from neutral point) solder joint as the first to fail. An experimental and numerical analysis has shown that critical solder joints can be located interior to the max DNP location. In this work, FCBGA packages were subjected to accelerated thermal cycling stress.

  9. Translational stiffness of the replaced shoulder joint

    Microsoft Academic Search

    R. Oosterom; J. L. Herder; W. ?wi?szkowski; H. E. N. Bersee

    2003-01-01

    Results after a total shoulder arthroplasty in rheumatoid patients are poor, indicated by loosening of especially the glenoid component, bad joint functionality and the possibility of a joint dislocation. The failure mechanisms behind this are multiple, including patient, surgical and design factors. These results must be improved. At present, the optimal geometrical prosthesis component design, focused on joint conformity and

  10. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...MINIMUM FEDERAL SAFETY STANDARDS Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...than 3°. (b) A miter joint on steel pipe to be operated at a...

  11. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...MINIMUM FEDERAL SAFETY STANDARDS Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...than 3°. (b) A miter joint on steel pipe to be operated at a...

  12. 49 CFR 192.233 - Miter joints.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...MINIMUM FEDERAL SAFETY STANDARDS Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...than 3°. (b) A miter joint on steel pipe to be operated at a...

  13. Joints in deployable space truss structures

    NASA Technical Reports Server (NTRS)

    Rhodes, M.

    1988-01-01

    Since the response of deployable structural concepts being considered for the Large Deployable Reflector (LDR) backup structure will be dominated by the response of joints, the joint characteristics are significant. An overview is given of the research activities at LaRC on the static behavior of joints for deployable space truss structures. Since a pin-clevis-type joint will be utilized in deployable structures, an experimental research program to characterize the joint parameters which affect stiffness was conducted. An experimental research program was conducted on a second type of joint, referred to as a near-center latch joint. It was used in the center of members on the deployable truss structure for the Control of Flexible Structures (COFS) flight experiment. The test results of the near-center latch joint and the member with the joints indicated that the stiffness of the near-center joint is linear and stiffer than the stiffness of the total member, and that non-linearities in the stiffness characteristics of the total member were due to bending introduced at the ends of the member. The resulting data indicates that stiff linear folding joints can be designed and that bending load paths should be avoided whenever possible. In summary, for deployable structures, special attention to the joint and the structure design is required to minimize the undesirable structural non-linearities.

  14. Stabilization for chronic sternoclavicular joint instability.

    PubMed

    Lee, Sang-Uk; Park, Il-Jung; Kim, Young-Du; Kim, Yoon-Chung; Jeong, Changhoon

    2010-12-01

    We present a surgical reconstruction technique for chronic unstable sternoclavicular (SC) joint utilizing the tendon of sternocleidomastoid (SCM) muscle and additional augmentation utilizing the palmaris longus free tendon graft to secure the medial end of the clavicle to the first rib. This double stabilization procedure may strengthen the SC joint fixation for the chronic SC joint instability. PMID:20852846

  15. Navigating Joint Projects in Telephone Conversations

    ERIC Educational Resources Information Center

    Bangerter, Adrian; Clark, Herbert H.; Katz, Anna R.

    2004-01-01

    Conversation coordinates joint activities and the joint projects that compose them. Participants coordinate (1) vertical transitions on entering and exiting joint projects; and (2) horizontal transitions in continuing within them. Transitions are coordinated using project markers such as uh-huh, yeah, right, and okay. In the authors' proposal,…

  16. The frictional properties of joints in rock

    Microsoft Academic Search

    J. C. Jaeger

    1959-01-01

    Summary The conditions for sliding over artificial joint surfaces have been studied experimentally by cutting rock cylinders at various angles to their axes and studying slip over these surfaces in a triaxial testing apparatus. The types of joint used were: (i) filled with plaster to simulate a soft joint filling, (ii) bare surfaces ground approximately flat, and (iii) natural surfaces

  17. Septic arthritis of the acromioclavicular joint

    Microsoft Academic Search

    A. Blankstein; J. L. Amsallem; E. Rubinstein; H. Horoszowski; I. Farin

    1985-01-01

    A patient with isolated pyogenous arthritis of the acromioclavicular joint (A-C joint) caused by Streptococcus viridans is described. The patient had no underlying disease. Minor trauma preceded shortly the development of the septic process. The patient was treated successfully with surgical drainage and antibiotics. To our knowledge this is the first case report of septic arthritis of the A-C joint

  18. Evaluation and Treatment of Acromioclavicular Joint Injuries

    Microsoft Academic Search

    Augustus D. Mazzocca; Robert A. Arciero; James Bicos

    2007-01-01

    Acromioclavicular joint injuries and, more specifically, separations are commonplace both in general practice and during athletic participation. This article reviews the traditional classification as well as the clinical evaluation of patients with acute and chronic acromioclavicular joint separations. It also highlights many recent advances, principally in the anatomy and biomechanics of the acromioclavicular joint ligamentous complex. The concept of increases

  19. 32 CFR 536.54 - Joint tortfeasors.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Defense 3 2012-07-01 2009-07-01 true Joint tortfeasors. 536.54 Section 536.54 National...Investigation and Processing of Claims § 536.54 Joint tortfeasors. When joint tortfeasors are liable, it is DA policy to...

  20. Joint News Release ELEVENTH ITER NEGOTIATIONS MEETING

    E-print Network

    Joint News Release ELEVENTH ITER NEGOTIATIONS MEETING CHENGDU , CHINA, 24OCTOBER 2005 Delegations of America met in CHENGDU on 24October 2005 to continue their work to reach agreement on the joint the project and its procurements, and the continuing joint drafting of the agreement on establishing

  1. 32 CFR 536.54 - Joint tortfeasors.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Defense 3 2013-07-01 2013-07-01 false Joint tortfeasors. 536.54 Section 536.54 National...Investigation and Processing of Claims § 536.54 Joint tortfeasors. When joint tortfeasors are liable, it is DA policy to...

  2. 29 CFR 570.115 - Joint applicability.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Joint applicability. 570.115 Section 570...Labor Standards Act of 1938, as Amended Joint and Separate Applicability of Sections 12(a) and 12(c) § 570.115 Joint applicability. The child labor...

  3. 32 CFR 536.54 - Joint tortfeasors.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Defense 3 2014-07-01 2014-07-01 false Joint tortfeasors. 536.54 Section 536.54 National...Investigation and Processing of Claims § 536.54 Joint tortfeasors. When joint tortfeasors are liable, it is DA policy to...

  4. 7 CFR 1956.110 - Joint debtors.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...2012-01-01 2012-01-01 false Joint debtors. 1956.110 Section 1956.110...Settlement-Community and Business Programs § 1956.110 Joint debtors. Settlements may not be approved for one joint debtor unless approved for all...

  5. 7 CFR 1956.110 - Joint debtors.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...2014-01-01 2014-01-01 false Joint debtors. 1956.110 Section 1956.110...Settlement-Community and Business Programs § 1956.110 Joint debtors. Settlements may not be approved for one joint debtor unless approved for all...

  6. 7 CFR 1956.110 - Joint debtors.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 2010-01-01 2009-01-01 true Joint debtors. 1956.110 Section 1956.110...Settlement-Community and Business Programs § 1956.110 Joint debtors. Settlements may not be approved for one joint debtor unless approved for all...

  7. JOINT DEGREE PROGRAMS DEFINITION AND POLICY

    E-print Network

    Omiecinski, Curtis

    1 JOINT DEGREE PROGRAMS DEFINITION AND POLICY: Within the fields of medicine and law, dual training for such complementary training can be demonstrated, the creation of a formal "Joint" degree program in which students or MD) offered at Penn State may be warranted. Such Joint degree programs enhance the educational

  8. Joint action: bodies and minds moving together

    E-print Network

    Richardson, Daniel C.

    Joint action: bodies and minds moving together Natalie Sebanz1 , Harold Bekkering2 and Gu¨ nther as individuals and as a species. Progress in understanding the cognitive and neural processes involved in joint perception and action in social context. In this article we outline how studies on joint attention, action

  9. Joint Seminar -Risk Management Institute and

    E-print Network

    Chaudhuri, Sanjay

    Joint Seminar - Risk Management Institute and Department of Finance Details of Seminar Date: 4 affine jump-diffusion models in capturing the joint dynamics of stock and option prices. We develop all the models we consider. Risk Management Institute Joint Seminar #12;

  10. Joint Kernel Learning for Supervised Image Segmentation

    E-print Network

    Yoo, Chang D.

    Joint Kernel Learning for Supervised Image Segmentation Jongmin Kim, Youngjoo Seo, Sanghyuk Park al- gorithm based on joint-kernelized structured prediction. In the proposed algorithm, correlation for struc- tured prediction were generally chosen to be linear with the model pa- rameter and joint feature

  11. 7 CFR 1956.110 - Joint debtors.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...2013-01-01 2013-01-01 false Joint debtors. 1956.110 Section 1956.110...Settlement-Community and Business Programs § 1956.110 Joint debtors. Settlements may not be approved for one joint debtor unless approved for all...

  12. Joint Invariant Signatures Peter J. Olver

    E-print Network

    Olver, Peter

    Joint Invariant Signatures Peter J. Olver School of Mathematics University of Minnesota Minneapolis­Carlo Rota Abstract. A new, algorithmic theory of moving frames is applied to classify joint invariants and joint differential invariants of transformation groups. Equivalence and sym- metry properties

  13. 29 CFR 570.115 - Joint applicability.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Joint applicability. 570.115 Section 570...Labor Standards Act of 1938, as Amended Joint and Separate Applicability of Sections 12(a) and 12(c) § 570.115 Joint applicability. The child labor...

  14. 7 CFR 1956.110 - Joint debtors.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...2011-01-01 2011-01-01 false Joint debtors. 1956.110 Section 1956.110...Settlement-Community and Business Programs § 1956.110 Joint debtors. Settlements may not be approved for one joint debtor unless approved for all...

  15. 29 CFR 570.115 - Joint applicability.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Joint applicability. 570.115 Section 570...Labor Standards Act of 1938, as Amended Joint and Separate Applicability of Sections 12(a) and 12(c) § 570.115 Joint applicability. The child labor...

  16. 38 CFR 4.66 - Sacroiliac joint.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...sharpening of the margins of the joint. Disability is manifest from...palpation and percussion over these joints, loss of normal quickness...flexion and extension of the hip. Traumatism is a rare cause...objective evidence of damage to the joint, and history of trauma...

  17. 38 CFR 4.66 - Sacroiliac joint.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...sharpening of the margins of the joint. Disability is manifest from...palpation and percussion over these joints, loss of normal quickness...flexion and extension of the hip. Traumatism is a rare cause...objective evidence of damage to the joint, and history of trauma...

  18. Tensile Strength of Single Lap Joint and Scarf Joint between CFRP and Carbon Steel

    Microsoft Academic Search

    Chiaki Sato; Kozo Ikegami

    1992-01-01

    The strength of single lap joints and scarf joints between carbon cloth laminated plastics (CFRP) and carbon steel bonded with epoxy resin was investigated both analytically and experimentally. The stress and strain distributions under tensile loads of the joints were analyzed by applying the elastic finite element method.The strength of the joints was predicted by applying the strength law of

  19. Evaluation of the Effect of Mega MSM on Improving Joint Function in Populations Experiencing Joint Degeneration

    PubMed Central

    Xu, Gang; Zhou, Tian; Gu, Yaqin; Wang, Qinping; Shariff, Mina; Gu, Pingping; Nguyen, Tuong; Shi, Rong; Rao, Jianyu

    2015-01-01

    Joint degeneration has become a commonplace problem in aging populations. The main clinical manifestations include joint pain, joint stiffness and joint swelling with functional disorder. Mega MSM is a nutritional supplement that may provide potential relief for joint problems associated with joint degeneration. The current experiment performed was a 12-week, randomized, double-blind, controlled study conducted on populations in China experiencing joint degeneration. The objective of the study was to determine whether the daily use of Mega MSM capsules could improve joint function, relieve symptoms of joint degeneration and improve the quality of life in aging populations. A total of 100 male and female participants over 50 years old who had at least one of the related symptoms of joint degeneration (joint pain, joint stiffness, joint swelling, difficulty walking, difficulty getting up from bed and difficulty going down stairs) were recruited and their symptoms of joint degeneration before and after the intervention were recorded. In this study, Mega MSM shows positive effects in improving joint function, relieving symptoms associated with joint degeneration and improving the quality of life in aging populations. PMID:26199577

  20. 26 CFR 1.6015-1 - Relief from joint and several liability on a joint return.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Relief from joint and several liability on a joint return. 1.6015-1 Section 1.6015-1...Returns Or Statements § 1.6015-1 Relief from joint and several liability on a joint return....