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1

Separation of heart sound signal from noise in joint cycle frequency-time-frequency domains based on fuzzy detection.  

PubMed

Noise is generally unavoidable during recordings of heart sound signal. Therefore, noise reduction is one of the important preprocesses in the analysis of heart sound signal. This was achieved in joint cycle frequency-time-frequency domains in this study. Heart sound signal was decomposed into components (called atoms) characterized by time delay, frequency, amplitude, time width, and phase. It was discovered that atoms of heart sound signal congregate in the joint domains. On the other hand, atoms of noise were dispersed. The atoms of heart sound signal could, therefore, be separated from the atoms of noise based on fuzzy detection. In a practical experiment, heart sound signal was successfully separated from lung sounds and disturbances due to chest motion. Computer simulations for various clinical heart sound signals were also used to evaluate the performance of the proposed noise reduction. It was shown that heart sound signal can be reconstructed from simulated complex noise (perhaps non-Gaussian, nonstationary, and colored). The proposed noise reduction can recover variations in the both waveform and time delay of heart sound signal during the reconstruction. Correlation coefficient and normalized residue were used to indicate the closeness of the reconstructed and noise-free heart sound signal. Correlation coefficient may exceed 0.90 and normalized residue may be around 0.10 in 0-dB noise environment, even if the phonocardiogram signal covers only ten cardiac cycles. PMID:20542764

Tang, Hong; Li, Ting; Park, Yongwan; Qiu, Tianshuang

2010-10-01

2

Neural speech enhancement in the time-frequency domain  

Microsoft Academic Search

A pulsed neural network approach for the enhancement of speech is presented. It employs a recently introduced pulse-induced masking principle on a joint time-frequency representation of signals. Based on the notion of a spectro-temporal receptive field, the principle provides signal-dependent dictionary elements, which are integrated into an enhancement process in the time-frequency domain. Experiments on signals with different types of

Markus Volkmer

2003-01-01

3

Pressure transfer function in time and time-frequency domains  

Microsoft Academic Search

In this paper, we define a time-domain pressure transfer function calculated from SIWEH (smoothed instantaneous wave energy history) transforms, and a time-frequency domain pressure transfer function calculated from wavelet transforms, of synchronized wave and pressure data. It is our objective to study whether the time-domain pressure transfer function and the time-frequency domain pressure transfer function can provide new interpretation of

Min-Chih Huang; Cheng-Han Tsai

2008-01-01

4

Body waves separation in the time-frequency domain  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

5

Real time frequency domain fibreoptic temperature sensor using ruby crystals.  

PubMed

The excited state phosphorescence lifetime of ruby crystals is used to monitor temperature in the physiological range from 15 degrees to 45 degrees C with precision and accuracy less than 1 degree C, in real time. Precision of 0.1 degree C is attained with 3 min integration times. A 500 micron cubic ruby crystal bounded to the distal end of an optical fibre of similar core dimensions is excited with pulsed Ne-He laser light of about 9 microW average power. The instrument uses a sampler for data acquisition, and frequency domain methods for data fitting. The instrument amplifies the a.c. components of the detector output and band limits the signal to 800 Hz. The fundamental frequency of the excitation is set to 24.41 Hz to obtain 32 or less harmonics. This band-limited signal is sampled and averaged between 20 and 100 cycles to obtain temperature measurements in real time. The frequency domain representation of the data is obtained by employing fast Fourier transform algorithms. The phase delay and the modulation ratio, of each sampled harmonic, is then computed. Five to 32 values of the phase and modulation are averaged before computing the sensor lifetime. The technique is capable of measuring precise and accurate excited state lifetimes from subpicowatt luminescent signals in plastic optical fibres. A least squares fit yields the lifetimes of single exponentials. A component of zero lifetime is introduced to account for the backscatter excitation seen by the photodetector leaking through optical interference filters. The phosphorescence lifetimes measured reproducibly to about six parts in 1000, with a 2 s integration time, are used to monitor physiological temperature. Temperatures are computed employing empirical polynomials. The system drift is 3% over 5 h of continuous operation. The instrumentation and methods allow 2.7 s update times and 50 s full response times. PMID:8771039

Alcala, J R; Liao, S C; Zheng, J

1996-01-01

6

Visualization and analysis of modulated pulses in magnetic resonance by joint time-frequency representations  

NASA Astrophysics Data System (ADS)

We study the utility of joint time-frequency representations for the analysis of shaped or composite pulses for magnetic resonance. Such spectrograms are commonly used for the visualization of shaped laser pulses in optical spectroscopy. This intuitive representation provides additional insight compared to conventional approaches, which exclusively show either temporal or spectral information. We focus on the short-time Fourier transform, which provides not only amplitude but also phase information. The approach is illustrated for broadband inversion pulses, multiple quantum excitation and broadband heteronuclear decoupling. The physical interpretation and validity of the approach is discussed.

Köcher, S. S.; Heydenreich, T.; Glaser, S. J.

2014-12-01

7

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

NASA Astrophysics Data System (ADS)

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".

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

2014-05-01

8

Initialization method for speech separation algorithms that work in the time-frequency domain.  

PubMed

This article addresses the problem of the unsupervised separation of speech signals in realistic scenarios. An initialization procedure is proposed for independent component analysis (ICA) algorithms that work in the time-frequency domain and require the prewhitening of the observations. It is shown that the proposed method drastically reduces the permuted solutions in that domain and helps to reduce the execution time of the algorithms. Simulations confirm these advantages for several ICA instantaneous algorithms and the effectiveness of the proposed technique in emulated reverberant environments. PMID:20369978

Sarmiento, Auxiliadora; Durán-Díaz, Iván; Cruces, Sergio

2010-04-01

9

Distinction between harmonic and structural components in ambient excitation tests using the time-frequency domain decomposition technique  

NASA Astrophysics Data System (ADS)

The time-frequency domain decomposition technique has been proposed for modal identification in ambient vibration testing. In the presence of harmonic excitations, the modal identification process can provide not only structural modes but also non-structural ones relative to harmonic components. It is thus important to distinguish between them. In this study, by using the time-frequency domain decomposition technique, it is demonstrated that the distinction between non-structural harmonic components and those of the structural responses can be possible, and it is merged into the general procedure of the time-frequency domain decomposition method. This proposition is then verified by numerical examples and by a laboratory test.

Le, Thien-Phu; Argoul, Pierre

2015-02-01

10

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

NASA Astrophysics Data System (ADS)

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.

Wang, Yazhou; Fathy, Aly E.

2013-05-01

11

Multichannel EEG Brain Activity Pattern Analysis in Time-Frequency Domain with Nonnegative Matrix  

E-print Network

(NMF) post-processing section in brain computer interface (BCI) training paradigm is presented: EEG, time-frequency signal analysis, brain computer interface, empirical mode decomposition electrical brain activity to control devices or computers in form of brain computer interfaces (BCI

Cichocki, Andrzej

12

Extending a time\\/frequency domain hybrid method for riser fatigue analysis  

Microsoft Academic Search

Fully coupled time domain analysis of a floating system is rigorous but time-consuming, thus an efficient hybrid method was developed in a prior work. The method simulates the coupled slow-drift responses in the time domain and analyzes the wave-frequency dynamics in the frequency domain. The hybrid method was shown to compare well with time domain analysis in predicting the mean-square

Y. M. Low

2011-01-01

13

Time and Frequency Evolution of Precursor Fields in Dispersive Media using FDTD and Joint Time-Frequency Analysis  

E-print Network

media, including the temporal evolution of pulse harmonics. 1 Introduction Wave propagation signal. The Sommerfeld and Brillouin definition of the concept of wave velocity into such terms as phase, the time-frequency analysis provides an insightful description of broadband pulse propagation in dispersive

Mojahedi, Mohammad

14

IDENTIFICATION OF TEMPORAL SPECTRAL ATTRIBUTES OF SEISMIC RECORDS BY MEAN OF JOINT TIME-FREQUENCY SPECTRAL DECOMPOSITION  

NASA Astrophysics Data System (ADS)

The spectral characteristics of stationary time series data are generally portrayed with the aid of the classical power spectrum. This latter spectrum is usually calculated from the Fast Fourier Transform (FFT) of the time series data. Unfortunately, such approach provides no temporal information and is unsuitable for examining seismic records, which exhibit transient nonstationary behavior. A classical approach to obtaining the desired time-frequency information contained in a seismic record is to use a Short Time Fourier Transform (STFT), which gives rise to a spectrogram. The spectrogram indicates how the energy in the record is distributed over time and frequency. The uncertainty principle precludes to simultaneously obtaining arbitrary fine resolution in both time and frequency. In order to overcome various shortcomings associated with the STFT, a class, known as Cohen's class, of time-frequency energy distributions has been developed in recent years. This class includes the Wigner-Ville (WV), Choi-Williams (CW), and reduced interference distribution (RID). Each possesses certain advantages and disadvantages. The objective of this paper is to compare the performance of these state-of-the-art time-frequency distributions when applied to seismic records associated with seismic data collected from free-field stations, as well as vibrations recorded from a building at four different levels. Tradeoffs between time and frequency resolution, suppression of so-called interference terms, and methodologies to portray large dynamic range will be described in detail.

Huerta-Lopez, C. I.; Upegui-Botero, F. M.; Martínez-Cruzado, J. A.

2009-12-01

15

Measuring Multi-Joint Stiffness during Single Movements: Numerical Validation of a Novel Time-Frequency Approach  

PubMed Central

This study presents and validates a Time-Frequency technique for measuring 2-dimensional multijoint arm stiffness throughout a single planar movement as well as during static posture. It is proposed as an alternative to current regressive methods which require numerous repetitions to obtain average stiffness on a small segment of the hand trajectory. The method is based on the analysis of the reassigned spectrogram of the arm's response to impulsive perturbations and can estimate arm stiffness on a trial-by-trial basis. Analytic and empirical methods are first derived and tested through modal analysis on synthetic data. The technique's accuracy and robustness are assessed by modeling the estimation of stiffness time profiles changing at different rates and affected by different noise levels. Our method obtains results comparable with two well-known regressive techniques. We also test how the technique can identify the viscoelastic component of non-linear and higher than second order systems with a non-parametrical approach. The technique proposed here is very impervious to noise and can be used easily for both postural and movement tasks. Estimations of stiffness profiles are possible with only one perturbation, making our method a useful tool for estimating limb stiffness during motor learning and adaptation tasks, and for understanding the modulation of stiffness in individuals with neurodegenerative diseases. PMID:22448233

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

2012-01-01

16

A Novel Flexible Model for the Extraction of Features from Brain Signals in the Time-Frequency Domain  

PubMed Central

Electrophysiological signals such as the EEG, MEG, or LFPs have been extensively studied over the last decades, and elaborate signal processing algorithms have been developed for their analysis. Many of these methods are based on time-frequency decomposition to account for the signals' spectral properties while maintaining their temporal dynamics. However, the data typically exhibit intra- and interindividual variability. Existing algorithms often do not take into account this variability, for instance by using fixed frequency bands. This shortcoming has inspired us to develop a new robust and flexible method for time-frequency analysis and signal feature extraction using the novel smooth natural Gaussian extension (snaGe) model. The model is nonlinear, and its parameters are interpretable. We propose an algorithm to derive initial parameters based on dynamic programming for nonlinear fitting and describe an iterative refinement scheme to robustly fit high-order models. We further present distance functions to be able to compare different instances of our model. The method's functionality and robustness are demonstrated using simulated as well as real data. The snaGe model is a general tool allowing for a wide range of applications in biomedical data analysis. PMID:23401674

Heideklang, R.; Ivanova, G.

2013-01-01

17

Time-Frequency Data Reduction for Event Related Potentials: Combining Principal Component Analysis and Matching Pursuit  

PubMed Central

Joint time-frequency representations offer a rich representation of event related potentials (ERPs) that cannot be obtained through individual time or frequency domain analysis. This representation, however, comes at the expense of increased data volume and the difficulty of interpreting the resulting representations. Therefore, methods that can reduce the large amount of time-frequency data to experimentally relevant components are essential. In this paper, we present a method that reduces the large volume of ERP time-frequency data into a few significant time-frequency parameters. The proposed method is based on applying the widely-used matching pursuit (MP) approach, with a Gabor dictionary, to principal components extracted from the time-frequency domain. The proposed PCA-Gabor decomposition is compared with other time-frequency data reduction methods such as the time-frequency PCA approach alone and standard matching pursuit methods using a Gabor dictionary for both simulated and biological data. The results show that the proposed PCA-Gabor approach performs better than either the PCA alone or the standard MP data reduction methods, by using the smallest amount of ERP data variance to produce the strongest statistical separation between experimental conditions. PMID:20730031

Aviyente, Selin; Bernat, Edward M.; Malone, Stephen M.; Iacono, William G.

2010-01-01

18

Time-Frequency Data Reduction for Event Related Potentials: Combining Principal Component Analysis and Matching Pursuit.  

PubMed

Joint time-frequency representations offer a rich representation of event related potentials (ERPs) that cannot be obtained through individual time or frequency domain analysis. This representation, however, comes at the expense of increased data volume and the difficulty of interpreting the resulting representations. Therefore, methods that can reduce the large amount of time-frequency data to experimentally relevant components are essential. In this paper, we present a method that reduces the large volume of ERP time-frequency data into a few significant time-frequency parameters. The proposed method is based on applying the widely-used matching pursuit (MP) approach, with a Gabor dictionary, to principal components extracted from the time-frequency domain. The proposed PCA-Gabor decomposition is compared with other time-frequency data reduction methods such as the time-frequency PCA approach alone and standard matching pursuit methods using a Gabor dictionary for both simulated and biological data. The results show that the proposed PCA-Gabor approach performs better than either the PCA alone or the standard MP data reduction methods, by using the smallest amount of ERP data variance to produce the strongest statistical separation between experimental conditions. PMID:20730031

Aviyente, Selin; Bernat, Edward M; Malone, Stephen M; Iacono, William G

2010-01-01

19

Image compression via joint statistical characterization in the wavelet domain  

Microsoft Academic Search

We develop a statistical characterization of natural images in the wavelet transform domain. This characterization describes the joint statistics between pairs of subband coefficients at adja- cent spatial locations, orientations, and scales. We observe that the raw coefficients are nearly decorrelated, but their magnitudes are highly correlated. A linear magnitude predictor coupled with both multiplicative and additive uncertainties accounts for

Robert W. Buccigrossi; Eero P. Simoncelli

1999-01-01

20

Time-frequency filtering for classifying targets in nonstationary clutter  

NASA Astrophysics Data System (ADS)

Classifying underwater targets from their sonar backscatter is often complicated by induced or self-noise (i.e. clutter, reverberation) arising from the scattering of the sonar pulse from non-target objects. Because clutter is inherently nonstationary, and because the propagation environment can induce nonstationarities as well, in addition to any nonstationarities / time-varying spectral components of the target echo itself, a joint phase space approach to target classification has been explored. In this paper, we apply a previously developed minimum mean square time-frequency spectral estimation method to design a bank of time-frequency filters from training data to distinguish targets from clutter. The method is implemented in the ambiguity domain in order to reduce computational requirements. In this domain, the optimal filter (more commonly called a "kernel" in the time-frequency literature) multiples the ambiguity function of the received signal, and then the mean squared distance to each target class is computed. Simulations demonstrate that the class-specific optimal kernel better separates each target from the clutter and other targets, compared to a simple mean-squared distance measure with no kernel processing.

Gomatam, Vikram Thiruneermalai; Loughlin, Patrick

2014-06-01

21

Time-frequency distributions - A review  

Microsoft Academic Search

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

Leon Cohen

1989-01-01

22

Analysis of event related potentials using PCA and matching pursuit on the time-frequency plane.  

PubMed

Joint time-frequency representations offer a rich representation of event related potentials (ERPs) that cannot be obtained through individual time or frequency domain analysis. This rich representation, however, comes at the expense of increased data volume and the difficulty of interpreting the resulting representations. Therefore, methods that can reduce the large amount of time-frequency data to physiologically meaningful components are essential. The method presented in this paper extends principal component analysis to the time-frequency plane to reduce a large set of ERPs to a small number of significant components. These components are then characterized using a Gabor dictionary to offer a succinct parametrization of the ERP data. The results show that the principal component analysis is successful at extracting components that can be described as the superposition of a small number of Gabor logons, and that the resulting set of logons succinctly represent physiologically meaningful ERP events. PMID:17946116

Aviyente, Selin; Bernat, Edward M; Malone, Stephen M; Iacono, William G

2006-01-01

23

Perceptually motivated time-frequency analysis.  

PubMed

This paper describes the design of a bilinear time-frequency distribution which is a joint model of temporal and spectral masking. The distribution is used to generate temporally evolving excitation patterns of nonstationary signals and systems and is conceived as a tool for acousticians and engineers for perceptual time-frequency analysis. Distribution time and frequency resolutions are controlled by a separable kernel consisting of a set of low-pass time and frequency smoothing windows. These windows are designed by adapting existing psychoacoustic models of auditory resolution, rather than using mathematical window functions. Cross-term interference and windowing clutter are highly suppressed for the distribution, ensuring resolution accuracy over a dynamic range sufficient to encompass that of the auditory system (in excess of 100 dB). Application to the analysis of a synthetic and two real signals are included to demonstrate the approach. PMID:15704418

O'Donovan, Jonathan J; Furlong, Dermot J

2005-01-01

24

Sparse time-frequency representations  

PubMed Central

Auditory neurons preserve exquisite temporal information about sound features, but we do not know how the brain uses this information to process the rapidly changing sounds of the natural world. Simple arguments for effective use of temporal information led us to consider the reassignment class of time-frequency representations as a model of auditory processing. Reassigned time-frequency representations can track isolated simple signals with accuracy unlimited by the time-frequency uncertainty principle, but lack of a general theory has hampered their application to complex sounds. We describe the reassigned representations for white noise and show that even spectrally dense signals produce sparse reassignments: the representation collapses onto a thin set of lines arranged in a froth-like pattern. Preserving phase information allows reconstruction of the original signal. We define a notion of “consensus,” based on stability of reassignment to time-scale changes, which produces sharp spectral estimates for a wide class of complex mixed signals. As the only currently known class of time-frequency representations that is always “in focus” this methodology has general utility in signal analysis. It may also help explain the remarkable acuity of auditory perception. Many details of complex sounds that are virtually undetectable in standard sonograms are readily perceptible and visible in reassignment. PMID:16601097

Gardner, Timothy J.; Magnasco, Marcelo O.

2006-01-01

25

Application of sparse time-frequency decomposition to seismic data  

NASA Astrophysics Data System (ADS)

The Gabor and S transforms are frequently used in time-frequency decomposition methods. Constrained by the uncertainty principle, both transforms produce low-resolution time-frequency decomposition results in the time and frequency domains. To improve the resolution of the time-frequency decomposition results, we use the instantaneous frequency distribution function (IFDF) to express the seismic signal. When the instantaneous frequencies of the nonstationary signal satisfy the requirements of the uncertainty principle, the support of IFDF is just the support of the amplitude ridges in the signal obtained using the short-time Fourier transform. Based on this feature, we propose a new iteration algorithm to achieve the sparse time-frequency decomposition of the signal. The iteration algorithm uses the support of the amplitude ridges of the residual signal obtained with the short-time Fourier transform to update the time-frequency components of the signal. The summation of the updated time-frequency components in each iteration is the result of the sparse time-frequency decomposition. Numerical examples show that the proposed method improves the resolution of the time-frequency decomposition results and the accuracy of the analysis of the nonstationary signal. We also use the proposed method to attenuate the ground roll of field seismic data with good results.

Wang, Xiong-Wen; Wang, Hua-Zhong

2014-12-01

26

Time-frequency analysis of wind effects on structures  

Microsoft Academic Search

As many physical processes of interest to Civil Engineers manifest nonlinear and nonstationary features, their complete characterization may not be accomplished via Fourier transforms, necessitating a new analysis framework in the time-frequency domain. This paper overviews recent developments in wavelet-based analysis of a number of physical processes of relevance to the Civil Engineering community. It is shown that the dual

A. Kareem; T. Kijewski

2002-01-01

27

Audio classification from time-frequency texture  

E-print Network

Time-frequency representations of audio signals often resemble texture images. This paper derives a simple audio classification algorithm based on treating sound spectrograms as texture images. The algorithm is inspired ...

Slotine, Jean-Jacques E.

28

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

NASA Astrophysics Data System (ADS)

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.

Chaudhary, Ujwal; Zhu, Banghe; Godavarty, Anuradha

2010-02-01

29

Time-frequency analysis of chaotic systems  

E-print Network

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.

C. Chandre; S. Wiggins; T. Uzer

2002-09-06

30

A method for ventricular late potentials detection using time-frequency representation and wavelet denoising.  

PubMed

This study proposes a method for ventricular late potentials (VLPs) detection using time-frequency representation and wavelet denoising in high-resolution electrocardiography (HRECG). The analysis is performed both with the signal averaged electrocardiography (SAECG) and in real time. A comparison between the temporal and the time-frequency analysis is also reported. In the first analysis the standard parameters QRSd, LAS40, and RMS40 were used; in the second normalized energy in time-frequency domain was calculated. The algorithm was tested adding artificial VLPs to real ECGs. PMID:22957271

Gadaleta, Matteo; Giorgio, Agostino

2012-01-01

31

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

Microsoft Academic Search

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

John C. Wood; Daniel T. Barry

1994-01-01

32

Time-frequency characterisation of paediatric heart sounds  

NASA Astrophysics Data System (ADS)

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.

Leung, Terence Sze-Tat

1998-08-01

33

TIME-FREQUENCY LEARNING MACHINES FOR NONSTATIONARITY DETECTION USING SURROGATES  

E-print Network

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

Paris-Sud XI, Université de

34

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

E-print Network

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 ...

Gorczynska, I.

35

Discrimination of pathological voices using a time-frequency approach.  

PubMed

Acoustical measures of vocal function are routinely used in the assessments of disordered voice, and for monitoring the patient's progress over the course of voice therapy. Typically, acoustic measures are extracted from sustained vowel stimuli where short-term and long-term perturbations in fundamental frequency and intensity, and the level of "glottal noise" are used to characterize the vocal function. However, acoustic measures extracted from continuous speech samples may well be required for accurate prediction of abnormal voice quality that is relevant to the client's "real world" experience. In contrast with sustained vowel research, there is relatively sparse literature on the effectiveness of acoustic measures extracted from continuous speech samples. This is partially due to the challenge of segmenting the speech signal into voiced, unvoiced, and silence periods before features can be extracted for vocal function characterization. In this paper we propose a joint time-frequency approach for classifying pathological voices using continuous speech signals that obviates the need for such segmentation. The speech signals were decomposed using an adaptive time-frequency transform algorithm, and several features such as the octave max, octave mean, energy ratio, length ratio, and frequency ratio were extracted from the decomposition parameters and analyzed using statistical pattern classification techniques. Experiments with a database consisting of continuous speech samples from 51 normal and 161 pathological talkers yielded a classification accuracy of 93.4%. PMID:15759572

Umapathy, Karthikeyan; Krishnan, Sridhar; Parsa, Vijay; Jamieson, Donald G

2005-03-01

36

Time-Frequency Analysis of the Dispersion of Lamb Modes  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

37

Time-Frequency Analysis of the Dispersion of Lamb Modes  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

38

Hexagonal Multicarrier Modulation: A Robust Transmission Scheme for Time-Frequency Dispersive Channels  

Microsoft Academic Search

By regarding signal transmission as tiling of the time-frequency plane, we propose a multicarrier transmission scheme on hexagonal lattice, coined the term hexagonal multicarrier modulation. To optimally combat the impact of the propagation channels, the underlying lattice parameters and the pulse shape of modulation waveform are jointly optimized to adapt to the channel scattering function from a minimum energy perturbation

Fang-Ming Han; Xian-Da Zhang

2007-01-01

39

Microfluidics analysis of blood using joint spectral and time domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

Although the Doppler Optical Coherence Tomography techniques have already enabled imaging of blood flow in large vessels in biological tissues, the generation of velocity maps of the capillary network is still a challenge. Since several important physiological and pathological phenomena occur in the microcirculation, the possibility of flow imaging and velocity assessment in microcapillaries may be important for medical diagnostics. Understanding of the origin of the Doppler signal in capillary vessels and limitations of such measurements is essential for further development of Doppler OCT methods. In the OCT flow maps of a microcapillary network randomly varying Doppler signals are observed. To answer the question how accurate is the Doppler OCT flow measurement for blood motion in small vessels, we have investigated the possibility to obtain velocity profiles of blood in vitro in well controlled experimental configuration. We have used a rectangular microchannel (100 ?m wide, 40 ?m deep) as a microcapillary phantom. Imaging was performed with a Fourier domain OCT setup with a CMOS camera. Data analysis was performed using joint Spectral and Time Domain OCT method (STdOCT).

Bukowska, Danuta; Szkulmowski, Maciej; Gorczynska, Iwona; Kowalczyk, Andrzej; Wojtkowski, Maciej

2012-01-01

40

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

41

Time-Frequency Analysis of Long Range Ultrasonic Signals  

NASA Astrophysics Data System (ADS)

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.

Thornicroft, Keith; Mares, Cristinel; Mudge, Peter

2012-08-01

42

Time-frequency analysis of the endocavitarian signal in paroxysmal atrial fibrillation.  

PubMed

We apply the time-frequency analysis to the endocavitarian signal of patients suffering from paroxysmal atrial fibrillation. The time-frequency spectrum reveals the components of the endocavitarian signal. These components are located in the regions of the time-frequency domain that differ for in-rhythm and in-atrial fibrillation signals. By using experimental data, we perform a statistical study of these regions, and we obtain their average value. The difference in the shape of these regions is caused by the re-entry circuits that characterize atrial fibrillation. We propose a propagation model for atrial fibrillation based on the re-entry circuits, which explains the shape of the time-frequency spectrum. PMID:22875240

Pagana, Guido; Galleani, Lorenzo; Gross, Stefano; Roch, Massimo Ruo; Pastore, Erica; Poggio, Mauro; Quaranta, Greta

2012-10-01

43

Enabling time-frequency agility: wavelet packet modulation in practice  

NASA Astrophysics Data System (ADS)

We describe the implementation of a novel adaptive wireless communications waveform for interference avoidance (IA) in re-configurable logic devices. While other transform domain-based IA waveforms have been suggested, the wavelet packet modulation (WPM) system described here is unique in its multiplexing of complex quadrature amplitude modulation symbols onto orthogonal wavelet packets for unrivaled time-frequency agility. We examine the realization aspects of dynamically instantiating the transmit side inverse discrete wavelet packet transform (DWPT) and receive side DWPT filter bank structures, and the WPM symbol timing recovery, in Field Programmable Gate Array (FPGA) devices. This work applies Trenas' re-configurable wavelet packet transform (WPT) architecture to a wireless communications system, draws upon Jones' theoretical foundation for orthogonally multiplexed communications, and utilizes Lindsey's WPM supersymbol tuning and Kjeldsen's WPM symbol synchronization algorithms.

Kjeldsen, Erik H.; Lindsey, Alan R.

2003-11-01

44

Music: A time-frequency approach Gary W. Don  

E-print Network

Music: A time-frequency approach Gary W. Don Department of Music and Theatre Arts Universityx ) Corresponding author 1 #12;2 Music: A time-frequency approach Gabor transforms and scalograms are used for mathematically analysing music, identifying patterns in the time-frequency structure of music

Walker, James S.

45

Postural tachycardia syndrome: time frequency mapping  

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

46

Time-Frequency Characterization and Receiver Waveform Design for Shallow Water  

E-print Network

a frequency-domain characterization of the shallow water system based on the normal-mode model that treatsTime-Frequency Characterization and Receiver Waveform Design for Shallow Water Environments Jun, Student Member, IEEE, and Cornel Ioana, Member, IEEE Abstract The shallow water environment can

Paris-Sud XI, Université de

47

Denoising of ictal EEG data using semi-blind source separation methods based on time-frequency priors.  

PubMed

Removing muscle activity from ictal ElectroEncephaloGram (EEG) data is an essential preprocessing step in diagnosis and study of epileptic disorders. Indeed, at the very beginning of seizures, ictal EEG has a low amplitude and its morphology in the time domain is quite similar to muscular activity. Contrary to the time domain, ictal signals have specific characteristics in the time-frequency domain. In this paper, we use the time-frequency signature of ictal discharges as a priori information on the sources of interest. To extract the time-frequency signature of ictal sources, we use the Canonical Correlation Analysis (CCA) method. Then we propose two time-frequency based semi-blind source separation approaches, namely the Time-Frequency-Generalized EigenValue Decomposition (TF-GEVD) and the Time-Frequency-Denoising Source Separation (TF-DSS), for the denoising of ictal signals based on these time-frequency signatures. The performance of the proposed methods is compared with that of CCA and Independent Component Analysis (ICA) approaches for the denoising of simulated ictal EEGs and of real ictal data. The results show the superiority of the proposed methods in comparison with CCA and ICA. PMID:25095269

Hajipour Sardouie, Sepideh; Bagher Shamsollahi, Mohammad; Albera, Laurent; Merlet, Isabelle

2014-07-28

48

Minimum entropy approach to denoising time-frequency distributions  

NASA Astrophysics Data System (ADS)

Signals used in time-frequency analysis are usually corrupted by noise. Therefore, denoising the time-frequency representation is a necessity for producing readable time-frequency images. Denoising is defined as the operation of smoothing a noisy signal or image for producing a noise free representation. Linear smoothing of time-frequency distributions (TFDs) suppresses noise at the expense of considerable smearing of the signal components. For this reason, nonlinear denoising has been preferred. A common example to nonlinear denoising methods is the wavelet thresholding. In this paper, we introduce an entropy based approach to denoising time-frequency distributions. This new approach uses the spectrogram decomposition of time-frequency kernels proposed by Cunningham and Williams.In order to denoise the time-frequency distribution, we combine those spectrograms with smallest entropy values, thus ensuring that each spectrogram is well concentrated on the time-frequency plane and contains as little noise as possible. Renyi entropy is used as the measure to quantify the complexity of each spectrogram. The threshold for the number of spectrograms to combine is chosen adaptively based on the tradeoff between entropy and variance. The denoised time-frequency distributions for several signals are shown to demonstrate the effectiveness of the method. The improvement in performance is quantitatively evaluated.

Aviyente, Selin; Williams, William J.

2001-11-01

49

An application of multidimensional time-frequency analysis as a base for the unified watermarking approach.  

PubMed

A watermarking approach based on multidimensional time-frequency analysis is proposed. It represents a unified concept that can be used for different types of data such as audio, speech signals, images or video. Time-frequency analysis is employed for speech signals, while space/spatial-frequency analysis is used for images. Their combination is applied for video signals. Particularly, we focus on the 2-D case: space/spatial-frequency based image watermarking procedure that will be subsequently extended to video signal. A method that selects coefficients for watermarking by estimating the local frequency content is proposed. In order to provide watermark imperceptibility, the nonstationary filtering is used to model the watermark which corresponds to the host signal components. Furthermore, the watermark detection within the multidimensional time-frequency domain is proposed. The efficiency and robustness of the procedure in the presence of various attacks is proven experimentally. PMID:20172773

Stankovic, Srdjan; Orovic, Irena; Zaric, Nikola

2010-03-01

50

Spread spectrum interference suppression using adaptive time-frequency tilings  

Microsoft Academic Search

Interference suppression in spread spectrum communication systems is often essential for achieving maximum system performance. Existing interference suppression methods do not perform well for most types of nonstationary interference. We first consider interference suppression schemes based on adaptive orthogonal time-frequency decompositions, such as wavelet packet and arbitrary dyadic time-frequency tilings. These methods often reduce interference substantially, but their performance can

Brian S. Krongold; Michael L. Kramer; Kannan Ramchandran; Douglas L. Jones

1997-01-01

51

A mortise-tenon joint in the transmembrane domain modulates autotransporter assembly into bacterial outer membranes.  

PubMed

Bacterial autotransporters comprise a 12-stranded membrane-embedded ?-barrel domain, which must be folded in a process that entraps segments of an N-terminal passenger domain. This first stage of autotransporter folding determines whether subsequent translocation can deliver the N-terminal domain to its functional form on the bacterial cell surface. Here, paired glycine-aromatic 'mortise and tenon' motifs are shown to join neighbouring ?-strands in the C-terminal barrel domain, and mutations within these motifs slow the rate and extent of passenger domain translocation to the surface of bacterial cells. In line with this, biophysical studies of the autotransporter Pet show that the conserved residues significantly quicken completion of the folding reaction and promote stability of the autotransporter barrel domain. Comparative genomics demonstrate conservation of glycine-aromatic residue pairings through evolution as a previously unrecognized feature of all autotransporter proteins. PMID:24967730

Leyton, Denisse L; Johnson, Matthew D; Thapa, Rajiv; Huysmans, Gerard H M; Dunstan, Rhys A; Celik, Nermin; Shen, Hsin-Hui; Loo, Dorothy; Belousoff, Matthew J; Purcell, Anthony W; Henderson, Ian R; Beddoe, Travis; Rossjohn, Jamie; Martin, Lisandra L; Strugnell, Richard A; Lithgow, Trevor

2014-01-01

52

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

PubMed Central

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

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

2014-01-01

53

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

54

ERPWAVELAB a toolbox for multi-channel analysis of time-frequency transformed event related potentials.  

PubMed

The open source toolbox 'ERPWAVELAB' is developed for multi-channel time-frequency analysis of event related activity of EEG and MEG data. The toolbox provides tools for data analysis and visualization of the most commonly used measures of time-frequency transformed event related data as well as data decomposition through non-negative matrix and multi-way (tensor) factorization. The decompositions provided can accommodate additional dimensions like subjects, conditions or repeats and as such they are perfected for group analysis. Furthermore, the toolbox enables tracking of phase locked activity from one channel-time-frequency instance to another as well as tools for artifact rejection in the time-frequency domain. Several other features are highlighted. ERPWAVELAB can freely be downloaded from www.erpwavelab.org, requires EEGLAB [Delorme A, Makeig S. EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis. J Neurosci Meth 2004;134:9-21] and runs under MATLAB (The Mathworks, Inc.). PMID:17204335

Mørup, Morten; Hansen, Lars Kai; Arnfred, Sidse M

2007-04-15

55

Detailed Vibration Analysis of Pinion Gear with Time-Frequency Methods  

NASA Technical Reports Server (NTRS)

In this paper, the authors show a detailed analysis of the vibration signal from the destructive testing of a spiral bevel gear and pinion pair containing seeded faults. The vibration signal is analyzed in the time domain, frequency domain and with four time-frequency transforms: the Short Time Frequency Transform (STFT), the Wigner-Ville Distribution with the Choi-Williams kernel (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 and damage conditions, are analyzed using these methods. A new metric for automatic anomaly 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 time-frequency transforms, as well as time and frequency representations, on this data set. Analysis with the CWT detects changes in the signal at low torque levels 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 anomaly detection and to develop fault detection methods for the metric.

Mosher, Marianne; Pryor, Anna H.; Lewicki, David G.

2003-01-01

56

Character Recognition Method by Time-Frequency Analyses Using Writing Pressure  

NASA Astrophysics Data System (ADS)

With the development of information and communication technology, personal verification becomes more and more important. In the future ubiquitous society, the development of terminals handling personal information requires the personal verification technology. The signature is one of the personal verification methods; however, the number of characters is limited in the case of the signature and therefore false signature is used easily. Thus, personal identification is difficult from handwriting. This paper proposes a “haptic pen” that extracts the writing pressure, and shows a character recognition method by time-frequency analyses. Although the figures of characters written by different amanuenses are similar, the differences appear in the time-frequency domain. As a result, it is possible to use the proposed character recognition for personal identification more exactly. The experimental results showed the viability of the proposed method.

Watanabe, Tatsuhito; Katsura, Seiichiro

57

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

58

[The research on time-frequency detection method of respiratory component in ballistocardiogram signal].  

PubMed

Based on the fact that the respiratory component modulates the cardiac cycle component in the ballistocardiogram (BCG) signal, we propose a method that detects respiratory with time-frequency analysis for the sitting ballistocardiography system. Firstly, we demodulated the BCG signal by using the variable frequency complex demodulation (VFCDM) to obtain the output for different center frequency of interest. Then we calculated the instantaneous frequencies and the instantaneous amplitudes by the time-frequency representation. We reconstructed the time-domain waveform of respiratory at last. In order to verify the feasibility and accuracy of this method, we applied wavelet transform and nasal thermistor signal to compare qualitatively and quantitatively. The simulation results showed that the proposed method could detect the respiratory rate from BCG signal more accurately, which provided meaningful attempt for monitoring the multiple physiological parameters synchronously and unconsciously. PMID:22826926

Jiang, Fangfang; Wang, Xu; Yang, Dan

2012-06-01

59

Precision frequency synthesizing sources with excellent time/frequency performances  

NASA Technical Reports Server (NTRS)

Precision frequency synthesizing sources are needed in the time / frequency measuring system, atomic frequency standards, telemetry, communication, and radar systems. This kind of frequency synthesizing source possesses high frequency accuracy and excellent long term and short term frequency stability. Several precision frequency synthesizing sources developed by Beijing Institute of Radio Metrology and Measurement (BIRMM) which have been successfully applied to the time / frequency measuring system, atomic frequency standards system, and radar system are described. In addition, the working principle, implementation approach, and the main technical specifications of the frequency synthesizing sources are also given.

Zhou, Liren; Lin, Hai

1994-01-01

60

Electrocardiogram Signal and Linear Time-Frequency Transforms  

NASA Astrophysics Data System (ADS)

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.

Krishna, B. T.

2014-12-01

61

Relation of joint spectral and time domain optical coherence tomography (jSTdOCT) and phase-resolved Doppler OCT.  

PubMed

A variety of promising approaches for quantitative flow velocity measurement in OCT have been proposed in recent years. The question is: Which method gets the most precise flow velocity out of the interference signals detected. We have compared the promising joint spectral and time domain optical coherence tomography (jSTdOCT) and the commonly used phase-resolved Doppler OCT (DOCT) and describe the link between these two proven methods for OCT in the Fourier domain (FD OCT). First, we show that jSTdOCT can be significantly improved by calculating the center of gravity via an unbiased complex algorithm instead of detecting the maximum intensity signal of the broadened Doppler frequency spectrum. Secondly, we introduce a unified mathematical description for DOCT and jSTdOCT that differs only in one exponent and call it enhjSTdOCT. Third, we present that enhjSTdOCT has the potential to significantly reduce the noise of the velocity measurement by choosing an exponent depending on the transverse sample velocity component and the signal-to-noise ratio. EnhjSTdOCT is verified numerically and experimentally to find the optimal parameters for maximal velocity noise reduction. PMID:25321783

Walther, Julia; Koch, Edmund

2014-09-22

62

Subspace array processing using spatial time-frequency distributions: applications for denoising structural echoes of elastic targets.  

PubMed

Structural echoes of underwater elastic targets, used for detection and classification purposes, can be highly localized in the time-frequency domain and can be aspect-dependent. Hence such structural echoes recorded along a distributed (synthetic) aperture, e.g., using a moving receiver platform, would not meet the stationarity and multiple snapshots requirements of common subspace array processing methods used for denoising array data based on their estimated covariance matrix. To address this issue, this article introduces a subspace array processing method based on the space-time-frequency distribution (STFD) of single-snapshots of non-stationary signals. This STFD is obtained by computing Cohen's class time-frequency distributions between all pairwise combination of the recorded signals along an arbitrary aperture array. This STFD is interpreted as a generalized array covariance matrix which automatically accounts for the inherent coherence across the time-frequency plane of the received nonstationary echoes emanating from the same target. Hence, identifying the signal's subspace from the eigenstructure of this STFD provides a means for denoising these non-stationary structural echoes by spreading the clutter and noise power in the time-frequency domain; as demonstrated here numerically and experimentally using the structural echoes of a thin steel spherical shell measured along a synthetic aperture. PMID:24815264

Sabra, Karim G; Anderson, Shaun D

2014-05-01

63

SPEECH RECOGNITION WITH LOCALIZED TIME-FREQUENCY PATTERN DETECTORS  

E-print Network

SPEECH RECOGNITION WITH LOCALIZED TIME-FREQUENCY PATTERN DETECTORS Ken Schutte, James Glass MIT Computer Science and Arti cial Intelligence Laboratory 32 Vassar St., Cambridge, MA 02139, USA {kschutte,glass fea- tures, and more explicit modeling of temporal dynamics. Traditional ASR systems rely on frame

64

Linear and quadratic time-frequency signal representations  

Microsoft Academic Search

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

F. Hlawatsch; G. F. Boudreaux-Bartels

1992-01-01

65

A Note on Time–Frequency Analysis of Finger Tapping  

PubMed Central

Finger tapping involves 3 important features: time, spatial amplitude, and frequency. In classical analysis, investigators examine timing parameters; in spectral analysis, they examine frequency parameters. Both types of analysis are based on stationary tap information. The authors propose that time–frequency analysis is a useful tool for analyzing nonstationary finger tapping. They describe the method and give examples of frequency modulation, age difference, and speed transition that demonstrate additional insights one can gain by using this analysis. PMID:16436360

Liu, Wei; Forrester, Larry; Whitall, Jill

2008-01-01

66

Time-Frequency Approach for Stochastic Signal Detection  

SciTech Connect

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.

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

67

A discoidin domain receptor 1 knock-out mouse as a novel model for osteoarthritis of the temporomandibular joint.  

PubMed

Discoidin domain receptor 1 (DDR-1)-deficient mice exhibited a high incidence of osteoarthritis (OA) in the temporomandibular joint (TMJ) as early as 9 weeks of age. They showed typical histological signs of OA, including surface fissures, loss of proteoglycans, chondrocyte cluster formation, collagen type I upregulation, and atypical collagen fibril arrangements. Chondrocytes isolated from the TMJs of DDR-1-deficient mice maintained their osteoarthritic characteristics when placed in culture. They expressed high levels of runx-2 and collagen type I, as well as low levels of sox-9 and aggrecan. The expression of DDR-2, a key factor in OA, was increased. DDR-1-deficient chondrocytes from the TMJ were positively influenced towards chondrogenesis by a three-dimensional matrix combined with a runx-2 knockdown or stimulation with extracellular matrix components, such as nidogen-2. Therefore, the DDR-1 knock-out mouse can serve as a novel model for temporomandibular disorders, such as OA of the TMJ, and will help to develop new treatment options, particularly those involving tissue regeneration. PMID:23912900

Schminke, Boris; Muhammad, Hayat; Bode, Christa; Sadowski, Boguslawa; Gerter, Regina; Gersdorff, Nikolaus; Bürgers, Ralf; Monsonego-Ornan, Efrat; Rosen, Vicki; Miosge, Nicolai

2014-03-01

68

A time-frequency approach to estimate critical time intervals in postural control.  

PubMed

The critical time interval (CTI) is a parameter that has been used to distinguish open-loop from closed-loop control during upright stance. The aim of this study was to develop a new method to determine CTIs. The new approach, termed the intermittent critical time interval (ICTI) method, was motivated from evidence that upright standing is an intermittent rather than an asymptotic stability control process. For this ICTI method, center-of-pressure time series are first transformed to the time-frequency domain with a wavelet method. Subsequently, the CTI is assumed equal to the time span between two local maxima in the time-frequency domain within a distinct frequency band (i.e., 0.5-1.1 Hz). This new method may help facilitate better estimates of the transition time interval between open and closed-loop control during upright stance and can also be applied in future work such as in simulating postural control. In addition, this method can be used in future work to assess temporal changes in CTIs. PMID:25105745

Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

2015-11-01

69

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

PubMed Central

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

2013-01-01

70

Spatiotemporal and time-frequency analysis of functional near infrared spectroscopy brain signals using independent component analysis.  

PubMed

Functional near infrared spectroscopy (fNIRS) is a noninvasive method to capture brain activities according to the measurements of changes in both oxyhemoglobin and deoxyhemoglobin concentrations. However, fNIRS recordings are the hemodynamic signals that come from the latent neural sources that are spatially and temporally mixed across the brain. The purpose of this work is to extract the temporal and frequency characteristics as well as the spatial activation patterns in the brains using independent component analysis (ICA). In this study, the filtered fNIRS recordings were processed and the time-frequency and spatiotemporal domain independent components (ICs) were identified by ICA. We found that multiple task-related components can be separated by ICA in time-frequency domain, and distinct spatial patterns of brain activity can be derived from ICs that are well correlated with the specific neural events, such as finger tapping tasks. PMID:24150092

Yuan, Zhen

2013-10-01

71

Degraded Time-Frequency Acuity to Time-Reversed Notes  

PubMed Central

Time-reversal symmetry breaking is a key feature of many classes of natural sounds, originating in the physics of sound production. While attention has been paid to the response of the auditory system to “natural stimuli,” very few psychophysical tests have been performed. We conduct psychophysical measurements of time-frequency acuity for stylized representations of “natural”-like notes (sharp attack, long decay) and the time-reversed versions of these notes (long attack, sharp decay). Our results demonstrate significantly greater precision, arising from enhanced temporal acuity, for such sounds over their time-reversed versions, without a corresponding decrease in frequency acuity. These data inveigh against models of auditory processing that include tradeoffs between temporal and frequency acuity, at least in the range of notes tested and suggest the existence of statistical priors for notes with a sharp-attack and a long-decay. We are additionally able to calculate a minimal theoretical bound on the sophistication of the nonlinearities in auditory processing. We find that among the best studied classes of nonlinear time-frequency representations, only matching pursuit, spectral derivatives, and reassigned spectrograms are able to satisfy this criterion. PMID:23799012

Oppenheim, Jacob N.; Isakov, Pavel; Magnasco, Marcelo O.

2013-01-01

72

The Application of Time-Frequency Methods to HUMS  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

73

Time-frequency Analyses of AE Signals in YBCO Superconductors  

NASA Astrophysics Data System (ADS)

AE (Acoustic Emission) measurements are well known methods to detect mechanical signals from superconducting coil The mechanical signals could be generated by micro cracks of epoxy resins, the motion of superconductors and the thermal expansion of superconductors, which were generated before and/or after a quench. We have presented a time-frequency visualization of AE signals as a method to detect the quench. We can detect very small AE signals regardless of lectromagnetic noises and can find the time of the AE occurrence and the frequency bands of AE signals by using this method. Recently it has been presented that YBCO superconductors are delaminated and degraded by a transverse tensile stress. The delamination is accompanied with AE signals. Also, it is known that amplitudes and frequency bands of AE signals vary with causes of AE occurrence. In this paper, we present time-frequency analyses of AE signa s caused by the delamination of a YBCO superconductor and the micro of epoxy resins.

Nanato, N.; Takemoto, N.

74

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

75

Crosslinking EEG time-frequency decomposition and fMRI in error monitoring.  

PubMed

Recent studies implicate a common response monitoring system, being active during erroneous and correct responses. Converging evidence from time-frequency decompositions of the response-related ERP revealed that evoked theta activity at fronto-central electrode positions differentiates correct from erroneous responses in simple tasks, but also in more complex tasks. However, up to now it is unclear how different electrophysiological parameters of error processing, especially at the level of neural oscillations are related, or predictive for BOLD signal changes reflecting error processing at a functional-neuroanatomical level. The present study aims to provide crosslinks between time domain information, time-frequency information, MRI BOLD signal and behavioral parameters in a task examining error monitoring due to mistakes in a mental rotation task. The results show that BOLD signal changes reflecting error processing on a functional-neuroanatomical level are best predicted by evoked oscillations in the theta frequency band. Although the fMRI results in this study account for an involvement of the anterior cingulate cortex, middle frontal gyrus, and the Insula in error processing, the correlation of evoked oscillations and BOLD signal was restricted to a coupling of evoked theta and anterior cingulate cortex BOLD activity. The current results indicate that although there is a distributed functional-neuroanatomical network mediating error processing, only distinct parts of this network seem to modulate electrophysiological properties of error monitoring. PMID:23443964

Hoffmann, Sven; Labrenz, Franziska; Themann, Maria; Wascher, Edmund; Beste, Christian

2014-03-01

76

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

PubMed Central

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

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

2013-01-01

77

Measuring high-frequency wave propagation in railroad tracks by joint time–frequency analysis  

Microsoft Academic Search

The behavior of high-frequency elastic waves propagating in railroad tracks is relevant to the field of rail noise generation and long-range rail inspection. While a large amount of theoretical and numerical work exists to predict transient vibrations propagating in rails, obtaining experimental data has been particularly challenging due to the multimode and dispersive behavior of the waves.In this work a

F. Lanza di Scalea; J. McNamara

2004-01-01

78

APS/123-QED Joint Time-Frequency and FDTD Analysis of Precursor Fields in Dispersive Media  

E-print Network

pulse propagation in dispersive media. PACS numbers: 02.70.Bf,42.25.Fx,73.40.Gk I. INTRODUCTION Wave was to find the velocity at which the "signal" propagated. Their analysis led to the discov- ery of two wave) contains the lowest frequency components of the signal. Sommerfeld also found that the front of the pulse

79

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

PubMed Central

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

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

2014-01-01

80

Use of Time-Frequency Representations in the Analysis of Stock Market Data  

Microsoft Academic Search

ABSTRACT The analysis of economic\\/financial time series in the frequency domain,is a relatively underexplored area of the literature, particularly when the statistical properties of a time series are time-variant (evolutionary). In this case, the spectral content of the series varies as time progresses, rendering the conventional Fourier theory inadequate to fully describe the cyclical characteristics of the series. The joint

Gonul Turhan-Sayan; Serdar Sayan

2002-01-01

81

Concatenative Text-to-Speech Synthesis Based on Prototype Waveform Interpolation (A Time Frequency Approach)   

E-print Network

This paper presents some preliminary methods to apply the Time- Frequency Interpolation technique - TFI [3] to concatenative text-to-speech synthesis. The TFI technique described here is a pitch-synchronous time-frequency ...

Morais, Edmilson; Taylor, Paul; Violaro, Fabio

82

Optimizing time-frequency distributions for automatic classification  

NASA Astrophysics Data System (ADS)

An entirely new set of criteria for the design of kernels (generating functions) for time-frequency representations (TFRs) is presented. These criteria aim only to produce kernels (and thus, TFRs) which will enable more accurate classification. We refer to these kernels, which are optimized to discriminate among several classes of signals, as signal class dependent kernels, or simply class dependent kernels. The genesis of the class dependent kernel is to be found in the area of operator theory, which we use to establish a direct link between a discrete-time, discrete-frequency TFR and its corresponding discrete signal. We see that many similarities, but also some important differences, exist between the results of the continuous-time operator approach and our discrete one. The differences between the continuous representations and discrete ones may not be the simple sampling relationship which has often been assumed. From this work, we obtain a very concise, matrix-based expression for a discrete- time/discrete-frequency TFR which is simply the product of the kernel with another matrix. This simple expression opens up the possibility to optimize the kernel in a number of ways. We focus, of course, on optimizations most suitable for classification, and ultimately wind up with the class dependent kernel. When applied to simulated sonar transient signals, we find that our approach does a good job of discriminating within very similar classes of transients and is especially sensitive to differences in time variation across classes.

Atlas, Les E.; Droppo, J.; McLaughlin, Jack

1997-10-01

83

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

E-print Network

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

Paris-Sud XI, Université de

84

Binary and ratio time-frequency masks for robust speech recognition  

E-print Network

Binary and ratio time-frequency masks for robust speech recognition Soundararajan Srinivasan a. We estimate this ratio using a binaural processor and derive a ratio time-frequency mask. This mask-data recognizer, the same binaural processor is used to estimate an ideal binary time-frequency mask, which

Wang, DeLiang "Leon"

85

Determination of the Potential Benefit of Time-Frequency Gain Manipulation  

E-print Network

Determination of the Potential Benefit of Time-Frequency Gain Manipulation Michael C. Anzalone was to determine the maximum benefit provided by a time-frequency gain-manipulation algorithm for noise resolution of the gain manipulation. Design: NR was performed using time-frequency gain manipulation, wherein

Carney, Laurel H.

86

Time-frequency analyses of tide-gauge sensor data.  

PubMed

The real world phenomena being observed by sensors are generally non-stationary in nature. The classical linear techniques for analysis and modeling natural time-series observations are inefficient and should be replaced by non-linear techniques of whose theoretical aspects and performances are varied. In this manner adopting the most appropriate technique and strategy is essential in evaluating sensors' data. In this study, two different time-series analysis approaches, namely least squares spectral analysis (LSSA) and wavelet analysis (continuous wavelet transform, cross wavelet transform and wavelet coherence algorithms as extensions of wavelet analysis), are applied to sea-level observations recorded by tide-gauge sensors, and the advantages and drawbacks of these methods are reviewed. The analyses were carried out using sea-level observations recorded at the Antalya-II and Erdek tide-gauge stations of the Turkish National Sea-Level Monitoring System. In the analyses, the useful information hidden in the noisy signals was detected, and the common features between the two sea-level time series were clarified. The tide-gauge records have data gaps in time because of issues such as instrumental shortcomings and power outages. Concerning the difficulties of the time-frequency analysis of data with voids, the sea-level observations were preprocessed, and the missing parts were predicted using the neural network method prior to the analysis. In conclusion the merits and limitations of the techniques in evaluating non-stationary observations by means of tide-gauge sensors records were documented and an analysis strategy for the sequential sensors observations was presented. PMID:22163829

Erol, Serdar

2011-01-01

87

Time-Frequency Analyses of Tide-Gauge Sensor Data  

PubMed Central

The real world phenomena being observed by sensors are generally non-stationary in nature. The classical linear techniques for analysis and modeling natural time-series observations are inefficient and should be replaced by non-linear techniques of whose theoretical aspects and performances are varied. In this manner adopting the most appropriate technique and strategy is essential in evaluating sensors’ data. In this study, two different time-series analysis approaches, namely least squares spectral analysis (LSSA) and wavelet analysis (continuous wavelet transform, cross wavelet transform and wavelet coherence algorithms as extensions of wavelet analysis), are applied to sea-level observations recorded by tide-gauge sensors, and the advantages and drawbacks of these methods are reviewed. The analyses were carried out using sea-level observations recorded at the Antalya-II and Erdek tide-gauge stations of the Turkish National Sea-Level Monitoring System. In the analyses, the useful information hidden in the noisy signals was detected, and the common features between the two sea-level time series were clarified. The tide-gauge records have data gaps in time because of issues such as instrumental shortcomings and power outages. Concerning the difficulties of the time-frequency analysis of data with voids, the sea-level observations were preprocessed, and the missing parts were predicted using the neural network method prior to the analysis. In conclusion the merits and limitations of the techniques in evaluating non-stationary observations by means of tide-gauge sensors records were documented and an analysis strategy for the sequential sensors observations was presented. PMID:22163829

Erol, Serdar

2011-01-01

88

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

ERIC Educational Resources Information Center

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…

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

2014-01-01

89

Separating cognitive processes with principal components analysis of EEG time-frequency distributions  

NASA Astrophysics Data System (ADS)

Measurement of EEG event-related potential (ERP) data has been most commonly undertaken in the time-domain, which can be complicated to interpret when separable activity overlaps in time. When the overlapping activity has distinct frequency characteristics, however, time-frequency (TF) signal processing techniques can be useful. The current report utilized ERP data from a cognitive task producing typical feedback-related negativity (FRN) and P300 ERP components which overlap in time. TF transforms were computed using the binomial reduced interference distribution (RID), and the resulting TF activity was then characterized using principal components analysis (PCA). Consistent with previous work, results indicate that the FRN was more related to theta activity (3-7 Hz) and P300 more to delta activity (below 3 Hz). At the same time, both time-domain measures were shown to be mixtures of TF theta and delta activity, highlighting the difficulties with overlapping activity. The TF theta and delta measures, on the other hand, were largely independent from each other, but also independently indexed the feedback stimulus parameters investigated. Results support the view that TF decomposition can greatly improve separation of overlapping EEG/ERP activity relevant to cognitive models of performance monitoring.

Bernat, Edward M.; Nelson, Lindsay D.; Holroyd, Clay B.; Gehring, William J.; Patrick, Christopher J.

2008-08-01

90

TIME-FREQUENCY Analysis of a Suspension Bridge Based on GPS  

NASA Astrophysics Data System (ADS)

This paper describes the results obtained from full-scale measurements of Humen bridge, which is the second longest suspension bridge in China. A real-time kinematic (RTK) global positioning system (GPS) has been developed and installed on the Humen bridge for on-line monitoring of bridge deck movements. The field wind-induced vibration data were measured by this monitoring system. Three system identification techniques are then adopted in the modal analysis of the wind-induced vibration response: the time-frequency Wigner distribution (WD) technique, the frequency-domain fast Fourier transform (FFT) technique and the time-domain auto-regressive moving average vector (ARMAV) technique. The WD technique can recognize close modal coupling and non-stationary response. The FFT technique can on site verify the quality of the measurements, but its frequency resolution is low and damping estimates are unreliable. The ARMAV method allows for gaining high-frequency resolution. However, it is strictly related to the stationary hypothesis. It is a general conclusion that we can improve the quality of the analysis and get more precise characteristics of the signal by these three methods. In addition, the WD combined with ARMAV seems to be the best case in quantitative analysis of fast-changing vibration signals.

XU, L.; GUO, J. J.; JIANG, J. J.

2002-06-01

91

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

NASA Astrophysics Data System (ADS)

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).

Ghosh, Suranjana; Banerji, Jagannath

2007-06-01

92

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

PubMed

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

Piovesan, Davide; Pierobon, Alberto; DiZio, Paul; Lackner, James R

2013-11-01

93

The envelope order spectrum based on generalized demodulation time-frequency analysis and its application to gear fault diagnosis  

NASA Astrophysics Data System (ADS)

The generalized demodulation time-frequency analysis is a novel signal processing method, which is particularly suitable for the processing of multi-component amplitude-modulated and frequency-modulated (AM-FM) signals as it can decompose a multi-component signal into a set of single-component signals whose instantaneous frequencies own physical meaning. While fault occurs in gear, the vibration signals measured from gearbox would exactly display AM-FM characteristics. Therefore, targeting the modulation feature of gear vibration signal in run-ups and run-downs, a fault diagnosis method in which generalized demodulation time-frequency analysis and envelope order spectrum technique are combined is put forward and applied to the transient analysis of gear vibration signal. Firstly the multi-component vibration signal of gear is decomposed into some mono-component signals using the generalized demodulation time-frequency analysis approach; secondly the envelope analysis is performed to each single-component signal; thirdly each envelope signal is re-sampled in angle domain; finally the spectrum analysis is applied to each re-sampled signal and the corresponding envelope order spectrum can be obtained. Furthermore, the gear working condition can be identified according to the envelope order spectrum. The analysis results from the simulation and experimental signals show that the proposed algorithm was effective in gear fault diagnosis.

Cheng, Junsheng; Yang, Yu; Yu, Dejie

2010-02-01

94

Time-Frequency Mixed-Norm Estimates: Sparse M/EEG imaging with non-stationary source activations  

PubMed Central

Magnetoencephalography (MEG) and electroencephalography (EEG) allow functional brain imaging with high temporal resolution. While solving the inverse problem independently at every time point can give an image of the active brain at every millisecond, such a procedure does not capitalize on the temporal dynamics of the signal. Linear inverse methods (Minimum-norm, dSPM, sLORETA, beamformers) typically assume that the signal is stationary: regularization parameter and data covariance are independent of time and the time varying signal-to-noise ratio (SNR). Other recently proposed non-linear inverse solvers promoting focal activations estimate the sources in both space and time while also assuming stationary sources during a time interval. However such an hypothesis only holds for short time intervals. To overcome this limitation, we propose time-frequency mixed-norm estimates (TF-MxNE), which use time-frequency analysis to regularize the ill-posed inverse problem. This method makes use of structured sparse priors defined in the time-frequency domain, offering more accurate estimates by capturing the non-stationary and transient nature of brain signals. State-of-the-art convex optimization procedures based on proximal operators are employed, allowing the derivation of a fast estimation algorithm. The accuracy of the TF-MxNE is compared to recently proposed inverse solvers with help of simulations and by analyzing publicly available MEG datasets. PMID:23291276

Gramfort, A.; Strohmeier, D.; Haueisen, J.; Hämäläinen, M.; Kowalski, M.

2013-01-01

95

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

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

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

96

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

PubMed

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

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

2010-07-01

97

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

98

ON THE USE OF TIME-FREQUENCY WARPING OPERATORS FOR ANALYSIS OF MARINE-MAMMAL SIGNALS  

E-print Network

ON THE USE OF TIME-FREQUENCY WARPING OPERATORS FOR ANALYSIS OF MARINE-MAMMAL SIGNALS Cornel Ioana@ensieta.fr ABSTRACT Processing marine-mammal signals for passive oceanic acoustic tomography or species classification that the time- frequency structures of the marine-mammal signals are generally non-linear. This fact

Boyer, Edmond

99

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

E-print Network

TIME-FREQUENCY MODELING OF SHALLOW WATER ENVIRONMENTS: RIGID VS. FLUID SEABED Jun Zhang , Bertrand the ocean seabed is considered to be rigid, the ideal waveguide model can be used to model the shallow water the Pekeris model for shallow water environments. In Section 3, we present the time-frequency (TF

Paris-Sud XI, Université de

100

Speech intelligibility in background noise with ideal binary time-frequency masking  

E-print Network

Speech intelligibility in background noise with ideal binary time-frequency masking DeLiang Wanga 2009 Ideal binary time-frequency masking is a signal separation technique that retains mixture energy masking on speech intelligibility of both normal-hearing NH and hearing-impaired HI listeners in different

Wang, DeLiang "Leon"

101

Time-Frequency Analysis of Chemosensory Event-Related Potentials to Characterize the Cortical Representation of Odors in Humans  

PubMed Central

Background The recording of olfactory and trigeminal chemosensory event-related potentials (ERPs) has been proposed as an objective and non-invasive technique to study the cortical processing of odors in humans. Until now, the responses have been characterized mainly using across-trial averaging in the time domain. Unfortunately, chemosensory ERPs, in particular, olfactory ERPs, exhibit a relatively low signal-to-noise ratio. Hence, although the technique is increasingly used in basic research as well as in clinical practice to evaluate people suffering from olfactory disorders, its current clinical relevance remains very limited. Here, we used a time-frequency analysis based on the wavelet transform to reveal EEG responses that are not strictly phase-locked to onset of the chemosensory stimulus. We hypothesized that this approach would significantly enhance the signal-to-noise ratio of the EEG responses to chemosensory stimulation because, as compared to conventional time-domain averaging, (1) it is less sensitive to temporal jitter and (2) it can reveal non phase-locked EEG responses such as event-related synchronization and desynchronization. Methodology/Principal Findings EEG responses to selective trigeminal and olfactory stimulation were recorded in 11 normosmic subjects. A Morlet wavelet was used to characterize the elicited responses in the time-frequency domain. We found that this approach markedly improved the signal-to-noise ratio of the obtained EEG responses, in particular, following olfactory stimulation. Furthermore, the approach allowed characterizing non phase-locked components that could not be identified using conventional time-domain averaging. Conclusion/Significance By providing a more robust and complete view of how odors are represented in the human brain, our approach could constitute the basis for a robust tool to study olfaction, both for basic research and clinicians. PMID:22427997

Huart, Caroline; Legrain, Valéry; Hummel, Thomas; Rombaux, Philippe; Mouraux, André

2012-01-01

102

A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images  

PubMed Central

Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new framework for detection of glaucoma progression using 3D SD-OCT images. In contrast to previous works that the retinal nerve fiber layer (RNFL) thickness measurement provided by commercially available spectral-domain optical coherence tomograph, we consider the whole 3D volume for change detection. To integrate a priori knowledge and in particular the spatial voxel dependency in the change detection map, we propose the use of the Markov Random Field to handle a such dependency. To accommodate the presence of false positive detection, the estimated change detection map is then used to classify a 3D SDOCT image into the “non-progressing” and “progressing” glaucoma classes, based on a fuzzy logic classifier. We compared the diagnostic performance of the proposed framework to existing methods of progression detection. PMID:25606299

Belghith, Akram; Bowd, Christopher; Weinreb, Robert N.; Zangwill, Linda M.

2014-01-01

103

Continuous-Variable Quantum Computing in Optical Time-Frequency Modes Using Quantum Memories  

NASA Astrophysics Data System (ADS)

We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate, and measure two-dimensional cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories. Time-frequency encoding enables the scheme to be extremely compact, requiring a number of memories that are a linear function of only the number of different frequencies in which the computational state is encoded, independent of its temporal duration. We therefore show that quantum memories can be a powerful component for scalable photonic quantum information processing architectures.

Humphreys, Peter C.; Kolthammer, W. Steven; Nunn, Joshua; Barbieri, Marco; Datta, Animesh; Walmsley, Ian A.

2014-09-01

104

Adapted and adaptive linear time-frequency representations: a synthesis point of view  

E-print Network

1 Adapted and adaptive linear time-frequency representations: a synthesis point of view P. Balazs are implicitly used to synthesize sound. In general, a signal's existence starts with its synthesis. P. Balazs

Paris-Sud XI, Université de

105

Time-Frequency Analysis of Beach Bacteria Variations and its Implication for Recreational Water Quality Modeling  

EPA Science Inventory

This paper explores the potential of time-frequency wavelet analysis in resolving beach bacteria concentration and possible explanatory variables across multiple time scales with temporal information still preserved. The wavelet scalograms of E. coli concentrations and the explan...

106

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

PubMed

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

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

2010-05-01

107

Analysis of underwater mammal vocalisations using time–frequency-phase tracker  

Microsoft Academic Search

One of the most challenging applications of time–frequency representations deals with the analysis of the signal issued from natural environment. Recently, the interest for passive underwater context increased, basically due to the rich information carried out by the natural signals. Taken into account the non-linear multi-component time–frequency behaviour of such signals, their analysis is a challenging problem.In this context, the

Cornel Ioana; Cédric Gervaise; Yann Stéphan; Jerôme I. Mars

2010-01-01

108

Time-frequency analysis of position-dependent dynamics in a Motion System with ILC  

Microsoft Academic Search

This paper exploits high-resolution time-frequency analysis of servo error signals in the investigation of position-dependent dynamics in a motion system with iterative learning control. Based on the matching pursuit algorithm signals are decomposed with respect to a multiple complex dictionary of atoms. A high-resolution signal energy distribution is derived in the time-frequency plane, which does not include cross-terms, like Wigner

Bart Hennen; Iuliana Rotariu; Maarten Steinbuch

2007-01-01

109

Time–frequency analysis of spike-wave discharges using a modified wavelet transform  

Microsoft Academic Search

The continuous Morlet wavelet transform was used for the analysis of the time–frequency pattern of spike-wave discharges (SWD) as can be recorded in a genetic animal model of absence epilepsy (rats of the WAG\\/Rij strain). We developed a new wavelet transform that allows to obtain the time–frequency dynamics of the dominating rhythm during the discharges. SWD were analyzed pre- and

Daria Bosnyakova; Alexandra Gabova; Galina Kuznetsova; Yuri Obukhov; Inna Midzyanovskaya; Dmitrij Salonin; Clementina van Rijn; Anton Coenen; Leene Tuomisto; Gilles van Luijtelaar

2006-01-01

110

A TIME-FREQUENCY DIVISION MULTIPLEXING COMMUNICATIONS SYSTEM WITH HEXAGONAL LATTICE STRUCTURE  

Microsoft Academic Search

In this paper, we propose a time-frequency division multi- plexing (TFDM) communications system for multiple users which uses prolate spheroidal wave functions (PSWFs) as the transmission basis. A hexagonal time-frequency lattice pro- vides optimal packing of the data in a fixed time-bandwidth support. We show that when using chirp modulation created by fractional Fourier transform (FrFT) the resulting system is

Seda Senay; Lutfiye Durak; Luis F. Chaparro

2009-01-01

111

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

NASA Astrophysics Data System (ADS)

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.

He, Qingbo

2013-02-01

112

Muscle activation of patients suffering from asymmetric ankle osteoarthritis during isometric contractions and level walking - a time-frequency analysis.  

PubMed

Asymmetric osteoarthritis (OA) is a common type of OA in the ankle joint. OA also influences the muscles surrounding a joint, however, little is known about the muscle activation in asymmetric ankle OA. Therefore, the aim of this study was to characterize the patients' muscle activation during isometric ankle torque measurements and level walking. Surface electromyography (EMG) was measured of gastrocnemius medialis (GM) and lateralis (GL), soleus (SO), tibialis anterior (TA), and peroneus longus (PL) in 12 healthy subjects and 12 ankle OA patients. To obtain time and frequency components of the EMG power a wavelet transformation was performed. Furthermore, entropy was introduced to characterize the homogeneity of the wavelet patterns. Patients produced lower plantar- and dorsiflexion torques and their TA wavelet spectrum was shifted towards lower frequencies. While walking, the patients' muscles were active with a lower intensity and over a broader time-frequency region. In contrast to controls and varus OA patients, maximal GM activity of valgus OA patients lagged behind the activity of GL and SO. In both tasks, PL of the valgus patients contained more low frequency power. The results of this study will help to assess whether surgical interventions of ankle OA can reestablish the muscle activation patterns. PMID:22742975

Nüesch, Corina; Huber, Cora; Pagenstert, Geert; von Tscharner, Vinzenz; Valderrabano, Victor

2012-12-01

113

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 ...

114

Automatic classification of sleep stages based on the time-frequency image of EEG signals.  

PubMed

In this paper, a new method for automatic sleep stage classification based on time-frequency image (TFI) of electroencephalogram (EEG) signals is proposed. Automatic classification of sleep stages is an important part for diagnosis and treatment of sleep disorders. The smoothed pseudo Wigner-Ville distribution (SPWVD) based time-frequency representation (TFR) of EEG signal has been used to obtain the time-frequency image (TFI). The segmentation of TFI has been performed based on the frequency-bands of the rhythms of EEG signals. The features derived from the histogram of segmented TFI have been used as an input feature set to multiclass least squares support vector machines (MC-LS-SVM) together with the radial basis function (RBF), Mexican hat wavelet, and Morlet wavelet kernel functions for automatic classification of sleep stages from EEG signals. The experimental results are presented to show the effectiveness of the proposed method for classification of sleep stages from EEG signals. PMID:24008250

Bajaj, Varun; Pachori, Ram Bilas

2013-12-01

115

Automatic classification of time-frequency plots applied to the center-of-pressure rotational components.  

PubMed

Time-frequency plots are widely applied to the non-stationary analysis of signals. These plots may be difficult to interpret, particularly when large data sets have to be considered. The aim of this work is to propose an automatic procedure of feature selection and clustering to be applied to time-frequency plots. We focus on the application of this procedure to plots obtained from a non-stationary analysis of the center-of-pressure signals acquired in upright bipedal stance. From a data set of 168 time-frequency plots we obtained 5 different clusters, each characterized by a few distinctive features. We were able to interpret the results of the clustering relating them to the physiological mechanisms underlying postural sway. PMID:24110663

Chiaramello, E; Agostini, V; Balestra, G; Knaflitz, M

2013-01-01

116

From wavelets to adaptive approximations: time-frequency parametrization of EEG  

PubMed Central

This paper presents a summary of time-frequency analysis of the electrical activity of the brain (EEG). It covers in details two major steps: introduction of wavelets and adaptive approximations. Presented studies include time-frequency solutions to several standard research and clinical problems, encountered in analysis of evoked potentials, sleep EEG, epileptic activities, ERD/ERS and pharmaco-EEG. Based upon these results we conclude that the matching pursuit algorithm provides a unified parametrization of EEG, applicable in a variety of experimental and clinical setups. This conclusion is followed by a brief discussion of the current state of the mathematical and algorithmical aspects of adaptive time-frequency approximations of signals. PMID:12605721

Durka, Piotr J

2003-01-01

117

Detection of obstructive sleep apnea in ECG recordings using time-frequency distributions and dynamic features.  

PubMed

Detection of obstructive sleep apnea can be performed through heart rate variability analysis, since fluctuations of oxygen saturation in blood cause variations in the heart rate. Such variations in heart rate can be assessed by means of time-frequency analysis implemented with time-frequency distributions belonging to Cohen's class. In this work, dynamic features are extracted from time frequency distributions in order to detect obstructive sleep apnea from ECG signals recorded during sleep. Furthermore, it is applied a methodology to measure the relevance of each dynamic feature, before the implementation of k-nn classifier used to recognize the normal and pathologic signals. As a result, the proposed method can be applied as a simple diagnostic tool for OSA with a high accuracy (up to 92.67%) in one-minute intervals. PMID:19964393

Quiceno-Manrique, A F; Alonso-Hernández, J B; Travieso-González, C M; Ferrer-Ballester, M A; Castellanos-Domínguez, G

2009-01-01

118

Isolating the energetic component of speech-on-speech masking with ideal time-frequency segregation  

E-print Network

Isolating the energetic component of speech-on-speech masking with ideal time-frequency segregation of acoustically similar masker sounds. This study attempted to isolate the effects that energetic masking, defined suggest that energetic masking plays a relatively small role in the overall masking that occurs when

Wang, DeLiang "Leon"

119

Full diversity block diagonal codes for differential space-time-frequency coded OFDM  

Microsoft Academic Search

Focusing on orthogonal frequency division multiplexing (OFDM) transmissions over frequency selective Rayleigh fading channels, we consider full diversity block diagonal codes for differential space-time-frequency (DSTF) coded OFDM with no channel state information (CSI). Resorting to subcarrier grouping, we convert the system into a set of DSTF systems, within which DSTF coding is considered. Through pairwise error probability (PEP) analysis, the

Qian Ma; C. Tepedelenlioglu; Zhiqiang Liu

2003-01-01

120

Channel Estimation Based on Space-Time-Frequency Coded Training Sequence for Transmit Diversity System  

NASA Astrophysics Data System (ADS)

A novel transmit diversity scheme with space-time-frequency coded training sequence is proposed to perform channel estimation flexibly over doubly selective channel, which offers a trade-off between maximum delay spread and maximum Doppler spread. Simulation results are presented to verify the effectiveness of the proposed flexible channel estimation method under different propagation conditions.

Yang, Fang; Peng, Kewu; Wang, Jintao; Song, Jian; Yang, Zhixing

121

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

NASA Astrophysics Data System (ADS)

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.

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

2015-03-01

122

Feature extraction for murmur detection based on support vector regression of time-frequency representations  

Microsoft Academic Search

This paper presents a nonlinear approach for time-frequency representations (TFR) data analysis, based on a statistical learning methodology - support vector regression (SVR), that being a nonlinear framework, matches recent findings on the underlying dynamics of cardiac mechanic activity and phonocardiographic (PCG) recordings. The proposed methodology aims to model the estimated TFRs, and extract relevant features to perform classification between

J. Jaramillo-Garzon; A. Quiceno-Manrique; I. Godino-Llorente; C. G. Castellanos-Dominguez

2008-01-01

123

Automated segmentation of linear time-frequency representations of marine-mammal sounds.  

PubMed

Many marine mammals produce highly nonlinear frequency modulations. Determining the time-frequency support of these sounds offers various applications, which include recognition, localization, and density estimation. This study introduces a low parameterized automated spectrogram segmentation method that is based on a theoretical probabilistic framework. In the first step, the background noise in the spectrogram is fitted with a Chi-squared distribution and thresholded using a Neyman-Pearson approach. In the second step, the number of false detections in time-frequency regions is modeled as a binomial distribution, and then through a Neyman-Pearson strategy, the time-frequency bins are gathered into regions of interest. The proposed method is validated on real data of large sequences of whistles from common dolphins, collected in the Bay of Biscay (France). The proposed method is also compared with two alternative approaches: the first is smoothing and thresholding of the spectrogram; the second is thresholding of the spectrogram followed by the use of morphological operators to gather the time-frequency bins and to remove false positives. This method is shown to increase the probability of detection for the same probability of false alarms. PMID:23968052

Dadouchi, Florian; Gervaise, Cedric; Ioana, Cornel; Huillery, Julien; Mars, Jérôme I

2013-09-01

124

Vibration Sensor Data Denoising Using a Time-Frequency Manifold for Machinery Fault Diagnosis  

PubMed Central

Vibration sensor data from a mechanical system are often associated with important measurement information useful for machinery fault diagnosis. However, in practice the existence of background noise makes it difficult to identify the fault signature from the sensing data. This paper introduces the time-frequency manifold (TFM) concept into sensor data denoising and proposes a novel denoising method for reliable machinery fault diagnosis. The TFM signature reflects the intrinsic time-frequency structure of a non-stationary signal. The proposed method intends to realize data denoising by synthesizing the TFM using time-frequency synthesis and phase space reconstruction (PSR) synthesis. Due to the merits of the TFM in noise suppression and resolution enhancement, the denoised signal would have satisfactory denoising effects, as well as inherent time-frequency structure keeping. Moreover, this paper presents a clustering-based statistical parameter to evaluate the proposed method, and also presents a new diagnostic approach, called frequency probability time series (FPTS) spectral analysis, to show its effectiveness in fault diagnosis. The proposed TFM-based data denoising method has been employed to deal with a set of vibration sensor data from defective bearings, and the results verify that for machinery fault diagnosis the method is superior to two traditional denoising methods. PMID:24379045

He, Qingbo; Wang, Xiangxiang; Zhou, Qiang

2014-01-01

125

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

Microsoft Academic Search

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

B. Samimy; G. Rizzoni

1996-01-01

126

Time-Frequency Relationships between Heart Rate and Respiration: A Diagnosis Tool for Late  

E-print Network

Time-Frequency Relationships between Heart Rate and Respiration: A Diagnosis Tool for Late Onset in premature infants with proven sepsis. Besides this, respiration and its relations to HRV appear to be less and respiration amplitude may help for the diagnosis of infection in premature infants. An estimator of the linear

Paris-Sud XI, Université de

127

Autonomous Time-Frequency Morphological Feature Extraction Algorithm for LPI Radar Modulation Classification  

Microsoft Academic Search

An autonomous (no human operator intervention) feature extraction algorithm that can be used for classification of low probability of intercept (LPI) radar modulations using time-frequency (T-F) images is presented. The approach uses erosion and a new adaptive threshold binarization algorithm embedded within a recursive dilation process to autonomously determine the modulation energy centroid (radar's carrier frequency). The modulation is then

Eric R. Zilberman; Phillip E. Pace

2006-01-01

128

Time-frequency analysis in supervising data acquisition on the large industry plant  

Microsoft Academic Search

The paper presents both algorithm and experiences of using a computer system to diagnose possible malfunctions of data acquisition devices using, a computationally simple, signal processing method, that process time-frequency disturbances of the signals and their, analytically unknown, dependencies. Results of over two years of experiences with more and more matured system in real industrial circumstances are presented on the

M. Morawski

2004-01-01

129

Low-Complexity Space–Time–Frequency Scheduling for MIMO Systems With SDMA  

Microsoft Academic Search

In this paper, we propose a low-complexity fair scheduling algorithm for wireless multiuser MIMO communication systems in which users are multiplexed via time-, frequency-, and space-division multiple access (SDMA) schemes. In such systems, the transmission quality considerably degrades if users with spatially correlated channels are to be served at the same time and frequency. The approach presented here works with

Martin Fuchs; Giovanni Del Galdo; Martin Haardt

2007-01-01

130

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

E-print Network

TIME-FREQUENCY-MODULATION REPRESENTATION OF STOCHASTIC SIGNALS Philip J.B. Jackson Centre is modulated by a deterministic sig- nal, it is often useful to determine the signal's parameters. A method of estimating the modulation index m is presented for noise whose amplitude is modulated by a periodic signal

Jackson, Philip JB

131

Diversity in Shallow Water Environments Using Blind Time-Frequency Separation Techniques  

E-print Network

model for shallow water environments. II. SHALLOW WATER ENVIRONMENT MODELING The Perkeris model treatsDiversity in Shallow Water Environments Using Blind Time-Frequency Separation Techniques Bertrand-- The shallow water environment can be character- ized as a time-dispersive system whose time-varying impulse

Nehorai, Arye

132

Rapid inversion in shallow water with a single receiver using modal time-frequency pattern  

E-print Network

theory is the most suitable propagation model for shallow water (0-400 m) and low frequencies (0-200 HzRapid inversion in shallow water with a single receiver using modal time-frequency pattern broadband source [1] [2] [3]. This paper presents a new inversion scheme in shallow water. It requires

Paris-Sud XI, Université de

133

TIME-FREQUENCY BASED WAVEFORM AND RECEIVER DESIGN FOR SHALLOW WATER COMMUNICATIONS  

E-print Network

formulate our system model in shallow water. In Section 4, we use a matched signal transform to design the normal-mode model for shallow water environments following [5]. While normal modes are more commonly usedTIME-FREQUENCY BASED WAVEFORM AND RECEIVER DESIGN FOR SHALLOW WATER COMMUNICATIONS Jun Zhang

Nehorai, Arye

134

Diversity in Shallow Water Environments Using Blind Time-Frequency Separation Techniques  

E-print Network

model for shallow water environments. II. SHALLOW WATER ENVIRONMENT MODELING The Perkeris model treatsDiversity in Shallow Water Environments Using Blind Time-Frequency Separation Techniques Bertrand-lab.inpg.fr Abstract- The shallow water environment can be character- ized as a time-dispersive system whose time

Paris-Sud XI, Université de

135

ADAPTIVE TIME-FREQUENCY DETECTION AND FILTERING FOR IMAGING IN HEAVY CLUTTER  

E-print Network

ADAPTIVE TIME-FREQUENCY DETECTION AND FILTERING FOR IMAGING IN HEAVY CLUTTER L. BORCEA, G with extensive numerical simulations that this approach to detection and imaging works well in heavy clutter the detection and filtering algorithm presented here works well in general clutter it has been analyzed

Papanicolaou, George C.

136

[Study of hybrid time-frequency method and characterization of atrial fibrillation from surface ECG].  

PubMed

With the non-invasive analysis of time-frequency features and instantaneous frequency (IFs) of atrial fibrillation (AF) from surface ECG signals, some important information reflecting the dynamic behavior of atria with AF can be extracted. In this paper is proposed a hybrid time-frequency analysis method, which uses the respective advantages of Gabor expansion and quadratic Wigner distribution. Our study showed that the time-frequency representation of atrial fibrillation signals was formulated into the combinations of time-frequency atoms series. By controlling the trade-off of resolution and interference terms via Manhattan distance threshold, this method in combination with moment-based computation obtained more robust estimation of IFs. The comparative analysis of 10 pairs of non-terminating and terminating types of AF signals suggested that hybrid estimation of IFs can detect the reduction of a majority of the fibrillatory rate when AF will end. Meanwhile, this method decreases compute burden and is a more robust way relative to peak-based or spectrogram method. So, the proposed method would have prospective applications in clinical management of atrial fibrillation. PMID:19166187

Huang, Zhongchao; Zhao, Yuqian

2008-12-01

137

TIME-FREQUENCY SEGMENTATION OF BIRD SONG IN NOISY ACOUSTIC ENVIRONMENTS  

E-print Network

TIME-FREQUENCY SEGMENTATION OF BIRD SONG IN NOISY ACOUSTIC ENVIRONMENTS Lawrence Neal, Forrest-5501 ABSTRACT Recent work in machine learning considers the problem of identifying bird species from an audio recording. Most meth- ods require segmentation to isolate each syllable of bird call in input audio. Energy

Fern, Xiaoli Zhang

138

Cardiovascular response to acute stress in freely moving rats: Time-frequency analysis  

Microsoft Academic Search

Spectral analysis of cardiovascular series is an important tool for assessing the features of the autonomic control of the cardiovascular system. In this experiment Wistar rats ecquiped with intraarterial catheter for blood pressure (BP) recording were exposed to stress induced by blowing air. The problem of non stationary data was overcomed applying the Smoothed Pseudo Wigner Villle (SPWV) time-frequency distribution.

Tatjana Loncar-Turukalo; Dragana Bajic; Nina Japundzic-Zigon

2008-01-01

139

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

NASA Astrophysics Data System (ADS)

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.

Van Hirtum, A.; Berckmans, D.

2003-09-01

140

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

PubMed

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

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

2014-12-01

141

Kolmogorov-Smirnov like test for time-frequency Fourier spectrogram analysis in LISA Pathfinder  

NASA Astrophysics Data System (ADS)

A statistical procedure for the analysis of time-frequency noise maps is presented and applied to LISA Pathfinder mission synthetic data. The procedure is based on the Kolmogorov-Smirnov like test that is applied to the analysis of time-frequency noise maps produced with the spectrogram technique. The influence of the finite size windowing on the statistic of the test is calculated with a Monte Carlo simulation for 4 different windows type. Such calculation demonstrate that the test statistic is modified by the correlations introduced in the spectrum by the finite size of the window and by the correlations between different time bins originated by overlapping between windowed segments. The application of the test procedure to LISA Pathfinder data demonstrates the test capability of detecting non-stationary features in a noise time series that is simulating low frequency non-stationary noise in the system.

Ferraioli, Luigi; Armano, Michele; Audley, Heather; Congedo, Giuseppe; Diepholz, Ingo; Gibert, Ferran; Hewitson, Martin; Hueller, Mauro; Karnesis, Nikolaos; Korsakova, Natalia; Nofrarias, Miquel; Plagnol, Eric; Vitale, Stefano

2014-12-01

142

Time frequency power profile of QRS complex obtained with wavelet transform in spontaneously hypertensive rats.  

PubMed

We evaluated whether frequency analysis could detect the development of interstitial fibrosis in rats. SHR/Izm and age-matched WKY/Izm were used. Limb lead II electrocardiograms were recorded. Continuous wavelet transform (CWT) was applied for the time-frequency analysis. The integrated time-frequency power (ITFP) between QRS complexes was measured and compared between groups. The ITFP at low-frequency bands (?125Hz) was significantly higher in SHR/Izm. The percent change of ITFP showed the different patterns between groups. Prominent interstitial fibrosis with an increase in TIMP-1 mRNA expression was also observed in SHR/Izm. These results were partly reproduced in a computer simulation. PMID:22182969

Takano, Nami K; Tsutsumi, Takeshi; Suzuki, Hiroshi; Okamoto, Yoshiwo; Nakajima, Toshiaki

2012-02-01

143

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

Microsoft Academic Search

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

Le Chung Tran; Alfred Mertins

2009-01-01

144

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

Microsoft Academic Search

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

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

2010-01-01

145

IGS\\/BIPM pilot project: GPS carrier phase for time\\/frequency transfer and timescale formation  

Microsoft Academic Search

The development within the International GPS Service (IGS) of a suite of clock products, for both satellites and tracking receivers, offers some experiences which mirror the operations of the Bureau International des Poids et Mesures (BIPM) in its formation of TAI\\/UTC but some aspects differ markedly. The IGS relies exclusively on the carrier phase-based geodetic technique whereas BIPM time\\/frequency transfers

J. Ray; K. Senior

2003-01-01

146

IDENTIFICATION OF COUPLED NON-LINEAR MODES FROM FREE VIBRATION USING TIME-FREQUENCY REPRESENTATIONS  

Microsoft Academic Search

A new method based on time–frequency representations is presented for identifying the non-linear modal parameters of a multi-degree-of-freedom non-linear lightly damped mechanical system. The coupled non-linear modes are first introduced. It is shown that, by using the coupled non-linear modes, the free response can be expressed as a linear combination of frequency and amplitude modulated components. This suggests the use

S. Bellizzi; P. Guillemain; R. Kronland-Martinet

2001-01-01

147

Automatic Seizure Detection Based on Time-Frequency Analysis and Artificial Neural Networks  

PubMed Central

The recording of seizures is of primary interest in the evaluation of epileptic patients. Seizure is the phenomenon of rhythmicity discharge from either a local area or the whole brain and the individual behavior usually lasts from seconds to minutes. Since seizures, in general, occur infrequently and unpredictably, automatic detection of seizures during long-term electroencephalograph (EEG) recordings is highly recommended. As EEG signals are nonstationary, the conventional methods of frequency analysis are not successful for diagnostic purposes. This paper presents a method of analysis of EEG signals, which is based on time-frequency analysis. Initially, selected segments of the EEG signals are analyzed using time-frequency methods and several features are extracted for each segment, representing the energy distribution in the time-frequency plane. Then, those features are used as an input in an artificial neural network (ANN), which provides the final classification of the EEG segments concerning the existence of seizures or not. We used a publicly available dataset in order to evaluate our method and the evaluation results are very promising indicating overall accuracy from 97.72% to 100%. PMID:18301712

Tzallas, A. T.; Tsipouras, M. G.; Fotiadis, D. I.

2007-01-01

148

Wavelet based time-frequency comparison of centre of mass time series determined by DORIS, SLR and GNSS techniques  

NASA Astrophysics Data System (ADS)

Wavelet analyzes were applied to determine wide-band dominant oscillations in center of mass time series data obtained by DORIS, GNSS and SLR space geodetic techniques. The time frequency wavelet spectra computed for complex-valued time series reveal seasonal and subseasonal oscillations in these data. Oscillations in these time series usually have variable amplitudes and phases which entail change in the flattening and polarization of the elliptic oscillations in their projections onto XY, XZ and ZY planes of the terrestrial reference frame. The comparison of these center of mass time series using the corresponding Morlet wavelet transform coefficients enabled detection of common variations in the flattening and polarization of the relevant elliptic oscillations. Next, these time series were transformed into time-scale domain using the discrete wavelet transform based on the Shannon wavelet functions. Such a transformation enables computation of the semblance functions between the wavelet transform coefficients of the considered time series determined by different techniques. Assuming a fixed semblance threshold, e.g. 0.1, zero values were assigned to discrete wavelet transform coefficients for which the semblance was below this threshold. The common signals in the compared center of mass time series were then computed using the inverse discrete wavelet transform of the coefficients exceeding the assumed threshold level.

Kosek, W.; Popi?ski, W.; Wnek, A.; Zbylut, M.

2012-04-01

149

[A wavelet-based time-frequency modeling method and its application in analysis of local field potentials in olfactory bulb].  

PubMed

The study of neuronal activity with low frequency has shown an increasing interest for its greater stability and reliability recent years. One challenge in analyzing this kind of activity is to find similarities and differences between signals efficiently and effectively. The traditional analysis methods, such as short-time Fourier transform, are easily obscured by background noises and often involve a large number of parameters. Therefore, this paper introduces a novel time-frequency analysis method based on wavelet transformation and half-ellipsoid modeling to extract instantaneous frequency and instantaneous phase information. This method overcomes some shortcomings of conventional time-frequency analysis. In this method, wavelet transformation is used to provide high-level representations of raw signals, and parsimonious half-ellipsoid models are used to extract changes in time domain and frequency domain of neural recordings. The method was validated to local field potentials (LFPs) of olfactory bulb of anesthetized rats during three different odor stimuli. The results suggested that this method could detect odor-relevant features from olfactory signals with large variability. The Odors then were classified with support vector machine (SVM) algorithm and the classification accuracy reached 79.4%. PMID:25219219

Dong, Qi; Hu, Liang; Zhuang, Liujing; Zhou, Jun; Wang, Ping

2014-06-01

150

Signal analysis by means of time-frequency (Wigner-type) distributions -- Applications to sonar and radar echoes  

SciTech Connect

Time series data have been traditionally analyzed in either the time or the frequency domains. For signals with a time-varying frequency content, the combined time-frequency (TF) representations, based on the Cohen class of (generalized) Wigner distributions (WD`s) offer a powerful analysis tool. Using them, it is possible to: (1) trace the time-evolution of the resonance features usually present in a standard sonar cross section (SCS), or in a radar cross section (RCS) and (2) extract target information that may be difficult to even notice in an ordinary SCS or RCS. After a brief review of the fundamental properties of the WD, the authors discuss ways to reduce or suppress the cross term interference that appears in the WD of multicomponent systems. These points are illustrated with a variety of three-dimensional (3-D) plots of Wigner and pseudo-Wigner distributions (PWD), in which the strength of the distribution is depicted as the height of a Wigner surface with height scales measured by various color shades or pseudocolors. The authors also review studies they have made of the echoes returned by conducting or dielectric targets in the atmosphere, when they are illuminated by broadband radar pings. A TF domain analysis of these impulse radar returns demonstrates their superior informative content. These plots allow the identification of targets in an easier and clearer fashion than by the conventional RCS of narrowband systems. The authors show computed and measured plots of WD and PWD of various types of aircraft to illustrate the classification advantages of the approach at any aspect angle. They also show analogous results for metallic objects buried underground, in dielectric media, at various depths.

Gaunaurd, G. [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.] [Naval Surface Warfare Center, Silver Spring, MD (United States). Carderock Div.; Strifors, H.C. [National Defense Research Establishment, Stockholm (Sweden)] [National Defense Research Establishment, Stockholm (Sweden)

1996-09-01

151

Fast Broadband Macromodeling Technique of Sampled Time/Frequency Data using z-domain Vector-fitting Method  

E-print Network

the interconnect governing equations using ordinary differential equation. Several methods have been proposed of starting poles. In this paper, we propose a new method of approximating a rational function using a vector-fitting Method Yidnek S. Mekonnen and Jos´e E. Schutt-Ain´e Department of Electrical and Computer Engineering

Schutt-Ainé, José E.

152

Heart sound cancellation from lung sound recordings using adaptive threshold and 2D interpolation in time-frequency domain  

Microsoft Academic Search

During lung sound recordings, an incessant noise source occurs due to heart sounds. The heart sound interference on lung sounds is significant especially at low flow rates. In this paper a new heart noise (HN) cancellation method is presented. This algorithm uses an image processing technique to detect HN segments in the spectrogram of the recorded lung sound signal. Afterwards

M. T. Pourazad; Z. K. Mousavi; G. Thomas

2003-01-01

153

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

PubMed

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 (300-700ms) was larger in the incongruent condition. The evoked delta (250-600ms) 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 (700-900ms) 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

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

2014-12-01

154

Use of wavelet coherence to assess two-joint coordination during quiet upright stance.  

PubMed

Joint coordination plays a critical role in maintaining postural stability, yet there is limited existing work describing joint coordination patterns in the time-frequency domain. Here, two-joint coordination was examined during quiet upright stance. A wavelet coherence method was applied to quantify the coherence between ankle-trunk and ankle-head angles in the sagittal and frontal planes. Wavelet coherence results indicated intermittent joint coordination particularly for frequencies of 2.5-4.0Hz. Coherence results were further processed to estimate mean time intervals between coherence instances, coherence burst frequency, and the ratio of in-phase versus anti-phase behaviors. Time intervals between intermittent coherence were 1.3-1.5sec, coherence burst frequency was ~0.4Hz, and phase ratios were ~1.0. Intermittent "bursting" of postural muscles may account for the finding of intermittent coherence in the noted frequency band. Some age and/or gender differences in coherence were found, and may be related to comparable differences in postural control ability or strategies. Results from application of this new method support earlier evidence that kinematic coordination is achieved intermittently rather than continuously during quiet upright stance. This method may provide richer information regarding such coordination, and could be a useful approach in future studies. PMID:25073748

Zhang, Hongbo; Nussbaum, Maury A; Agnew, Michael J

2014-10-01

155

The application of time-frequency analysis to the air-coupled ultrasonic testing of concrete.  

PubMed

Air-coupled ultrasound has been used for the nondestructive evaluation of concrete, using broad bandwidth electrostatic transducers and chirp excitation. This paper investigates the benefits of using time-frequency analysis in such situations, for both waveform retrieval and imaging in the presence of low signal levels. The use of the short-term Fourier transform, the Wavelet transform, and the Wigner-Ville distribution all are considered, in which accurate tracking of the ultrasonic chirp signals is demonstrated. The Hough transform then is applied as a filter. An image of a steel reinforcement bar in concrete has been produced to illustrate this approach. PMID:16615581

Berriman, James R; Hutchins, David A; Neild, Adrian; Gan, Tat Hean; Purnell, Phil

2006-04-01

156

Time-frequency analysis of Transitory/Permanent frequency decrease in civil engineering structures during earthquakes  

E-print Network

The analysis of strong motion recordings in structures is crucial to understand the damaging process during earthquakes. A very precise time-frequency representation, the reassigned smoothed pseudo-Wigner-Ville method, allowed us to follow the variation of the Millikan Library (California) and the Grenoble City Hall building (France) resonance frequencies during earthquakes. Under strong motions, a quick frequency drop, attributed to damage of the soil-structure system, followed by a slower increase is found. However, in the case of weak earthquakes, we show that frequency variations come from the ground motion spectrum and cannot be interpreted in terms of change of the soil-structure system.

Michel, Clotaire

2008-01-01

157

Hip joints  

NSDL National Science Digital Library

The human hips are an example of a ball-and-socket joint. Ball-and-socket joints have the ability to rotate in a circular motion. The joint where the arm connects to the shoulder is also a type of ball-and-socket joint.

Connie Raab (National Institutes of Health;)

2006-05-17

158

Estimation of motion parameters by isolating scatterers using time-frequency filtering  

NASA Astrophysics Data System (ADS)

In SAR/ISAR imaging, estimation of motion parameters of moving objects is needed in order to compensate for translational motion that causes image blurring. Phase parameter estimation from signals corresponding to one scatterer buried in complex white Gaussian noise is a problem for which various successful techniques have been devised. For multicomponent signals, it is difficult to use these parametric methods. Isolating the signal's components in order to do the estimation can help. The authors have previously proposed the isolation of scatterers for instantaneous frequency estimation. This process allows not only the extraction of components but also the manipulation of each object separately. In this paper, we study the use of time-frequency filtering on parameter estimation for a complex exponential signal with polynomial phase modulation. Our study is limited to the use of the Discrete Polynomial- Phase Transform (DPT) of Peleg and Friedlander. Our approach is to simplify the problem of parameter estimation from multicomponent signals by isolating them and then performing the estimation on each one separately. The process of isolating components is also shown to be improved by applying superresolution in the computation of the time- frequency representation. We also formulate an approach using the DPT for motion parameter estimation on a signal model for stepped-frequency ISAR returns from a scatterer.

Liu, Ke; Thomas, Gabriel; Cabrera, Sergio D.

1997-07-01

159

Time-Frequency Modulation of ERD and EEG Coherence in Robot-Assisted Hand Performance.  

PubMed

A better understanding of cortical modifications related to movement preparation and execution after robot-assisted training could aid in refining rehabilitation therapy protocols for stroke patients. Electroencephalography (EEG) modifications of cortical activity in healthy subjects were evaluated using time-frequency event-related EEG and task-related coherence (TRCoh). Twenty-one channel EEG was recorded in eight subjects during protocols of active, passive, and imagined movements. The subjects performed robot-assisted tasks using the Bi-Manu-Track robot-assisted arm trainer. We applied time-frequency event-related synchronization/desynchronization (ERS/ERD) and TRCoh approaches to investigate where movement-related decreases in power were localized and to study the functional relationships between areas. Our results showed ERD of sensorimotor (SM) area over the contralateral side before the movement and bilateral ERD during execution of the movement. ERD during passive movements was similar in topography to that observed during voluntary movements, but without pre-movement components. No significant difference in time course ERD was observed among the three types of movement over the two SM areas. The TRCoh topography was similar for active and imagined movement; before passive movement, the frontal regions were uncoupled from the SM regions and did not contribute to task performance. This study suggests new perspectives for the evaluation of brain oscillatory activity and the neurological assessment of motor performance by means of quantitative EEG to better understand the planning and execution of movement. PMID:24838817

Formaggio, Emanuela; Storti, Silvia Francesca; Boscolo Galazzo, Ilaria; Gandolfi, Marialuisa; Geroin, Christian; Smania, Nicola; Fiaschi, Antonio; Manganotti, Paolo

2015-03-01

160

Automated detection of perinatal hypoxia using time-frequency-based heart rate variability features.  

PubMed

Perinatal hypoxia is a cause of cerebral injury in foetuses and neonates. Detection of foetal hypoxia during labour based on the pattern recognition of heart rate signals suffers from high observer variability and low specificity. We describe a new automated hypoxia detection method using time-frequency analysis of heart rate variability (HRV) signals. This approach uses features extracted from the instantaneous frequency and instantaneous amplitude of HRV signal components as well as features based on matrix decomposition of the signals' time-frequency distributions using singular value decomposition and non-negative matrix factorization. The classification between hypoxia and non-hypoxia data is performed using a support vector machine classifier. The proposed method is tested on a dataset obtained from a newborn piglet model with a controlled hypoxic insult. The chosen HRV features show strong performance compared to conventional spectral features and other existing methods of hypoxia detection with a sensitivity 93.3 %, specificity 98.3 % and accuracy 95.8 %. The high predictive value of this approach to detecting hypoxia is a substantial step towards developing a more accurate and reliable hypoxia detection method for use in human foetal monitoring. PMID:24272142

Dong, Shiying; Boashash, Boualem; Azemi, Ghasem; Lingwood, Barbara E; Colditz, Paul B

2014-02-01

161

Noise resistant time frequency analysis and application in fault diagnosis of rolling element bearings  

NASA Astrophysics Data System (ADS)

Rolling element bearings are frequently used in rotary machinery, but they are also fragile mechanical parts. Hence, exact condition monitoring and fault diagnosis for them plays an important role in ensuring machinery's reliable running. Timely diagnosis of early bearing faults is desirable, but the early fault signatures are easily submerged in noise. In this paper, Wigner-Ville spectrum based on cyclic spectral density (CSWVS for a brief notation) is studied, which is able to represent the cyclostationary signals while reducing the masking effect of additive stationary noise. Both simulations and experiments show that CSWVS is a noise resistant time frequency analysis technique for extracting bearing fault patterns, when bearing signals are under influences of random noise and gear vibrations. The 3-D feature of the CSWVS is proved useful in extracting bearing fault pattern from gearbox vibration signals, where bearing signals are affected by gear meshing vibration and noise. Besides, CSWVS utilizes the second order cyclostationary property of the vibration signals produced by bearing distributed fault, and clearly extracts its fault features, which cannot be extracted by envelope analysis. To quantitatively describe the extent of bearing fault, Renyi information encoded in the time frequency diagram of CSWVS is studied. It is shown to be a more sensitive index to reflect bearing performance degradation, compared with the spectral entropy (SE), squared envelope spectrum entropy (SESE) and Renyi informations for WVD, PWVD, especially when SNR is low.

Dong, Guangming; Chen, Jin

2012-11-01

162

The local maxima method for enhancement of time-frequency map and its application to local damage detection in rotating machines  

NASA Astrophysics Data System (ADS)

In this paper a new method of fault detection in rotating machinery is presented. It is based on a vibration time series analysis in time-frequency domain. A raw vibration signal is decomposed via the short-time Fourier transform (STFT). The time-frequency map is considered as matrix (M×N) with N sub-signals with length M. Each sub-signal is considered as a time series and might be interpreted as energy variation for narrow frequency bins. Each sub-signal is processed using a novel approach called the local maxima method. Basically, we search for local maxima because they should appear in the signal if local damage in bearings or gearbox exists. Finally, information for all sub-signals is combined in order to validate impulsive behavior of energy. Due to random character of the obtained time series, each maximum occurrence has to be checked for its significance. If there are time points for which the average number of local maxima for all sub-signals is significantly higher than for the other time instances, then location of these maxima is “weighted” as more important (at this time instance local maxima create for a set of ?f a pattern on the time-frequency map). This information, called vector of weights, is used for enhancement of spectrogram. When vector of weights is applied for spectrogram, non-informative energy is suppressed while informative features on spectrogram are enhanced. If the distribution of local maxima on spectrogram creates a pattern of wide-band cyclic energy growth, the machine is suspected of being damaged. For healthy condition, the vector of the average number of maxima for each time point should not have outliers, aggregation of information from all sub-signals is rather random and does not create any pattern. The method is illustrated by analysis of very noisy both real and simulated signals.

Obuchowski, Jakub; Wy?oma?ska, Agnieszka; Zimroz, Rados?aw

2014-06-01

163

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

PubMed

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

Stankovski, Tomislav; Cooke, William H; Rudas, László; Stefanovska, Aneta; Eckberg, Dwain L

2013-12-01

164

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

PubMed Central

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

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

2013-01-01

165

Demonstration of coherent time-frequency Schmidt mode selection using dispersion-engineered frequency conversion  

E-print Network

Time-frequency Schmidt (TFS) modes of ultrafast quantum states are naturally compatible with high bit-rate integrated quantum communication networks. Thus they offer an attractive alternative for the realization of high dimensional quantum optics. Here, we present a quantum pulse gate based on dispersion-engineered ultrafast frequency conversion in a nonlinear optical waveguide, which is a key element for harnessing the potential of TFS modes. We experimentally retrieve the modal spectral-temporal structure of our device and demonstrate a single-mode operation fidelity of 80\\%, which is limited by experimental shortcomings. In addition, we retrieve a conversion efficiency of 87.7\\% with a high signal-to-noise ratio of 8.8 when operating the quantum pulse gate at the single-photon level.

Benjamin Brecht; Andreas Eckstein; Raimund Ricken; Viktor Quiring; Hubertus Suche; Linda Sansoni; Christine Silberhorn

2014-09-16

166

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

167

Aesthetic appreciation: event-related field and time-frequency analyses  

PubMed Central

Improvements in neuroimaging methods have afforded significant advances in our knowledge of the cognitive and neural foundations of aesthetic appreciation. We used magnetoencephalography (MEG) to register brain activity while participants decided about the beauty of visual stimuli. The data were analyzed with event-related field (ERF) and Time-Frequency (TF) procedures. ERFs revealed no significant differences between brain activity related with stimuli rated as “beautiful” and “not beautiful.” TF analysis showed clear differences between both conditions 400 ms after stimulus onset. Oscillatory power was greater for stimuli rated as “beautiful” than those regarded as “not beautiful” in the four frequency bands (theta, alpha, beta, and gamma). These results are interpreted in the frame of synchronization studies. PMID:22287948

Munar, Enric; Nadal, Marcos; Castellanos, Nazareth P.; Flexas, Albert; Maestú, Fernando; Mirasso, Claudio; Cela-Conde, Camilo J.

2012-01-01

168

Demonstration of coherent time-frequency Schmidt mode selection using dispersion-engineered frequency conversion  

NASA Astrophysics Data System (ADS)

Time-frequency Schmidt (TFS) modes of ultrafast quantum states are naturally compatible with high-bit-rate integrated quantum communication networks. Thus they offer an attractive alternative for the realization of high-dimensional quantum optics. Here, we present a quantum pulse gate based on dispersion-engineered ultrafast frequency conversion in a nonlinear optical waveguide, which is a key element for harnessing the potential of TFS modes. We experimentally retrieve the modal spectral-temporal structure of our device and demonstrate a single-mode operation fidelity of 80%, which is limited by experimental shortcomings. In addition, we retrieve a conversion efficiency of 87.7% with a high signal-to-noise ratio of 8.8 when operating the quantum pulse gate at the single-photon level.

Brecht, Benjamin; Eckstein, Andreas; Ricken, Raimund; Quiring, Viktor; Suche, Hubertus; Sansoni, Linda; Silberhorn, Christine

2014-09-01

169

Time-frequency response spectrum of rotational ground motion and its application  

NASA Astrophysics Data System (ADS)

The rotational seismic motions are estimated from one station records of the 1999 Jiji (Chi-Chi), Taiwan, earthquake based on the theory of elastic plane wave propagation. The time-frequency response spectrum (TFRS) of the rotational motions is calculated and its characteristics are analyzed, then the TFRS is applied to analyze the damage mechanism of one twelve-storey frame concrete structure. The results show that one of the ground motion components can not reflect the characteristics of the seismic motions completely; the characteristics of each component, especially rotational motions, need to be studied. The damage line of the structure and TFRS of ground motion are important for seismic design, only the TFRS of input seismic wave is suitable, the structure design is reliable.

Che, Wei; Luo, Qifeng

2010-02-01

170

Adaptive time-frequency matrix features for T wave alternans analysis.  

PubMed

T wave alternans (TWA) has been associated with ventricular arrhythmias. Hence, TWA detection can risk stratify patients with heart disease who may experience sudden death from ventricular arhythmias. However, accurate TWA detection is technically challenging due to the low microvolt TWA signal and the confounding effect of biological noise such as movement, myopotentials or respiration. In this paper, we propose nonnegative matrix factorization (NMF)-Adaptive spectral method to increase the robustness of TWA detection in ambulatory electrocardiograms (ECGs). The proposed method applies a non-linear time-frequency (TF) analysis and NMF to the aligned ST-T waveforms. This method separates the TWA signal from the other non-desired ECG signal components, and detects TWA with high accuracy. The performance of our proposed method is validated in a clinical study using ECGs which confirms a TWA detection of 92% compared to 47% using the conventional spectral method. PMID:19965108

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

2009-01-01

171

A Full-Diversity Space-Time-Frequency Coded MIMO-OFDM System with Linear Decoding Complexity  

Microsoft Academic Search

Early research on space-time-frequency (STF) codes are aimed at achieving maximum frequency and spatial diversity only. Over a space-time-frequency selective fading channel, there is a possibility of achieving better performance if coding across spatial, temporal, and spectra dimensions is designed properly. To date, only two STF codes were proposed to achieve full diversity. The decoding complexity, however, of these codes

Chao-Cheng Tu

2006-01-01

172

The optimal selection of mother wavelet shape for the best time-frequency localization of the continuous wavelet transform  

Microsoft Academic Search

The continuous wavelet transform (CWT) has been utilized as an effective and powerful time-frequency analysis tool for identifying the rapidly-varying characteristics of some dispersive wave signals. Particularly, in the applications of continuous Gabor wavelet transform, its effectiveness is strongly influenced by the shape of the applied Gabor wavelet so the determination of an optimal shape tracing well the time-frequency evolution

Jin-Chul Hong; Yoon Young Kim

2003-01-01

173

Time-frequency analysis of fiber-optic temperature data on groundwater-surface water interactions  

NASA Astrophysics Data System (ADS)

Accurate characterization of the hydrogeological framework and groundwater-surface water interactions in particular, is crucial to understanding contaminant transport between aquifers and rivers. Fiber-optic distributed temperature sensing (FODTS) is a novel tool that offers unprecedented resolution for characterizing groundwater-surface water interaction. Time-frequency analysis of FODTS data provides a means to distinguish between a wide range of hydrologic processes at various scales. This work demonstrates the use of the S-Transform to analyze FODTS time series and synchronous river stage time series. Our study focused on improving understanding of the dynamics of groundwater-surface water interaction at the Hanford 300-Area Richland, WA. We used ~1.5 km long fiber optic cable to continuously monitor real time temperature variations along the hyporheic corridor at ~1 m spatial resolution and 5 minutes temporal resolution. It is generally recognized that contaminated groundwater discharge in Hanford site 300-Area is highly controlled by fluctuations in the Columbia River stage. Using S-Transform analysis of the temperature data along the river corridor we investigated in more detail the contributions of periodicity in the river stage to focused groundwater discharge. This time-frequency analysis of the DTS data uniquely identified areas of stage-controlled enhanced exchange along the hyporheic corridor. Dam operations upstream of the site were identified as a factor controlling stage fluctuations with relatively long periods (4 - 8 days). S-Transform analysis was used to map areas of high amplitude in these diagnostic periods indicative of stage-driven exchange along the river corridor.

Mwakanyamale, K. E.; Slater, L. D.; Day-Lewis, F. D.; Alwasif, M. H.; Ntarlagiannis, D.; Johnson, C. D.

2011-12-01

174

Intermediate Frequency Seismic Data De-noising by Radial Trace Time-Frequency Peak Filtering  

NASA Astrophysics Data System (ADS)

In seismic data processing, recognizing and tracking the seismic events from records with strong random noise is an especially crucial step for further interpretation and analysis. Time-frequency peak filtering(TFPF), a time-frequency based method, has achieved many good results in DaQing oil basin in China for its accuracy in non-stationary signal estimation without prior knowledge but low SNR. However, for intermediate dominant frequency(above 40Hz), TFPF would bring serious bias even when the time window ? decreases to 3. In another word, intermediate frequency preservation and the bias limitation of TFPF is a pair of contradiction, which cannot be solved by shortening ?. Taking both the unbiased TFPF condition and the adjacent channels' correlation into considered, this paper introduces the radial trace(RT)transform to obtain a frequency reduced input and thus decrease the TFPF bias. First decrease the intermediate frequencies along radial traces close to the reflection event direction. Then obtain a less-biased TFPF estimation with suitable ?. At last, recover the intermediate frequency with the inverse RT. Both synthetic and field data experiments prove its better performance in intermediate frequency seismic data de-noising. Fig1 extracts a single channel with dominant frequency of 45Hz from a 2D synthetic record. RT TFPF behaves better in random noise attenuation(e.g. solid circles), and meanwhile introduces less bias (e.g. dotted circle). RT TFPF attenuates more random noise between 0-30Hz and 70-120Hz, and preserves intermediate frequencies around 30-70Hz. To field data in Fig2, RT TFPF recovers some reflection events more clearly, and some events become more continuous and compact. A single channel before and after different TFPF. Different TFPF results of field data.

Wu, N.; Li, Y.; Huang, Y.; Xu, X.

2012-12-01

175

Recent advances in time-frequency analysis methods for machinery fault diagnosis: A review with application examples  

NASA Astrophysics Data System (ADS)

Nonstationary signal analysis is one of the main topics in the field of machinery fault diagnosis. Time-frequency analysis can identify the signal frequency components, reveals their time variant features, and is an effective tool to extract machinery health information contained in nonstationary signals. Various time-frequency analysis methods have been proposed and applied to machinery fault diagnosis. These include linear and bilinear time-frequency representations (e.g., wavelet transform, Cohen and affine class distributions), adaptive parametric time-frequency analysis (based on atomic decomposition and time-frequency auto-regressive moving average models), adaptive non-parametric time-frequency analysis (e.g., Hilbert-Huang transform, local mean decomposition, and energy separation), and time varying higher order spectra. This paper presents a systematic review of over 20 major such methods reported in more than 100 representative articles published since 1990. Their fundamental principles, advantages and disadvantages, and applications to fault diagnosis of machinery have been examined. Some examples have also been provided to illustrate their performance.

Feng, Zhipeng; Liang, Ming; Chu, Fulei

2013-07-01

176

Joint Disorders  

MedlinePLUS

A joint is where two or more bones come together, like the knee, hip, elbow, or shoulder. Joints can be damaged by many types of injuries or diseases, including Arthritis - inflammation of a joint. It causes pain, stiffness, and swelling. Over time, ...

177

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

PubMed Central

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

2013-01-01

178

Time-frequency model for echo-delay resolution in wideband biosonar  

NASA Astrophysics Data System (ADS)

A time/frequency model of the bat's auditory system was developed to examine the basis for the fine (~2 ?s) echo-delay resolution of big brown bats (Eptesicus fuscus), and its performance at resolving closely spaced FM sonar echoes in the bat's 20-100-kHz band at different signal-to-noise ratios was computed. The model uses parallel bandpass filters spaced over this band to generate envelopes that individually can have much lower bandwidth than the bat's ultrasonic sonar sounds and still achieve fine delay resolution. Because fine delay separations are inside the integration time of the model's filters (~250-300 ?s), resolving them means using interference patterns along the frequency dimension (spectral peaks and notches). The low bandwidth content of the filter outputs is suitable for relay of information to higher auditory areas that have intrinsically poor temporal response properties. If implemented in fully parallel analog-digital hardware, the model is computationally extremely efficient and would improve resolution in military and industrial sonar receivers.

Neretti, Nicola; Sanderson, Mark I.; Intrator, Nathan; Simmons, James A.

2003-04-01

179

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

PubMed

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

Mostafapour, A; Davoodi, S; Ghareaghaji, M

2014-12-01

180

Estimation of target vibration spectra from laser radar backscatter using time-frequency distributions  

NASA Astrophysics Data System (ADS)

A time-frequency distribution (TFD) signal processor, developed at the Applied Physics Laboratory, is currently under evaluation using simulated signals and actual laser vibration sensor (LVS) data that we collected on various ship targets. Preliminary results for one instantaneous frequency (IF) estimator implementation, the smoothed cross Wigner-Ville Distribution (XWVD), indicate 8 to 10 dB demodulation (CNR) advantage compared to a digital FM limiter-discriminator. A second approach, using the unsmoothed XWVD TFD, demonstrated a 3-5 dB advantage. Regarding spectral estimation, we are investigating performance of our reduced interference distribution (RID) implementation through comparison with the short-time Fourier transform (STFT). From the LVS data processed, indications are that a significant increase in spectral and temporal resolution exists using our RID approach. Our processor also provided improved detectability over the STFT for transient signals and short-lived sinusoids. Significant correlation between accepted acoustic lines and LVS-derived vibration lines are indicated. Details are presented that describe our signal simulation, the LVS measurements, and signal processing implementations along with assumptions based on measured speckle-induced amplitude modulation.

Cole, Timothy D.; El-Dinary, Ashruf S.

1993-10-01

181

Estimation of respiratory rate from photoplethysmogram data using time-frequency spectral estimation.  

PubMed

We present a new method that uses the pulse oximeter signal to estimate the respiratory rate. The method uses a recently developed time-frequency spectral estimation method, variable-frequency complex demodulation (VFCDM), to identify frequency modulation (FM) of the photoplethysmogram waveform. This FM has a measurable periodicity, which provides an estimate of the respiration period. We compared the performance of VFCDM to the continuous wavelet transform (CWT) and autoregressive (AR) model approaches. The CWT method also utilizes the respiratory sinus arrhythmia effect as represented by either FM or AM to estimate respiratory rates. Both CWT and AR model methods have been previously shown to provide reasonably good estimates of breathing rates that are in the normal range (12-26 breaths/min). However, to our knowledge, breathing rates higher than 26 breaths/min and the real-time performance of these algorithms are yet to be tested. Our analysis based on 15 healthy subjects reveals that the VFCDM method provides the best results in terms of accuracy (smaller median error), consistency (smaller interquartile range of the median value), and computational efficiency (less than 0.3 s on 1 min of data using a MATLAB implementation) to extract breathing rates that varied from 12-36 breaths/min. PMID:19369147

Chon, Ki H; Dash, Shishir; Ju, Kihwan

2009-08-01

182

Applying Time-Frequency Analysis to Assist Identification of Hydrogeological Structure of Groundwater Aquifers  

NASA Astrophysics Data System (ADS)

Due to global warming, climate change, and economic development, the stability of water supply is challenged using only surface water resources. Hence, groundwater becomes an important water resource for increasing water supply reliability. However, groundwater extraction many introduce damages such as land subsidence and seawater intrusion. To accurately evaluate the response of groundwater aquifers, correct hydrogeological structure is a key factor. In the past, the evaluation of the hydrogeological structure relies on subjective judgment which is arbitrarily made based on available information of core sampling record, fossils, geological dating, etc. This study develops a quantitative method to provide objective information for improving the judgment. This method uses observed groundwater water level and time-frequency analysis. Precisely, the signal strength of the groundwater level is evaluated using Fast Fourier Transform (FFT) which is done by a commercially available software named Visual Signal. Two signal frequencies, daily and annual frequency, are studied. This method is applied to Lanyang Plain in Taiwan. The groundwater level record of shallow wells is selected for the signal processing. Therefore, higher signal strength of an annual signal indicates higher recharge which is an indicator of unconfined aquifer. In the case of Lanyang Plain, the low signal strength area includes fan top area and scatter areas at fan central and fantail areas. This signal information along with core sampling information can provide a complete picture of the hydrogeological structure and characteristics for the studied area Ilan shallow water wells in different frequencies

shiuan, C. W.; Chang, L.

2013-12-01

183

Five-dimensional neuroimaging: Localization of the time-frequency dynamics of cortical activity  

PubMed Central

The spatiotemporal dynamics of cortical oscillations across human brain regions remain poorly understood because of a lack of adequately validated methods for reconstructing such activity from noninvasive electrophysiological data. In this paper, we present a novel adaptive spatial filtering algorithm optimized for robust source time-frequency reconstruction from magnetoencephalography (MEG) and electroencephalography (EEG) data. The efficacy of the method is demonstrated with simulated sources and is also applied to real MEG data from a self-paced finger movement task. The algorithm reliably reveals modulations both in the beta band (12–30 Hz) and high gamma band (65–90 Hz) in sensorimotor cortex. The performance is validated by both across-subjects statistical comparisons and by intracranial electrocorticography (ECoG) data from two epilepsy patients. Interestingly, we also reliably observed high frequency activity (30–300 Hz) in the cerebellum, though with variable locations and frequencies across subjects. The proposed algorithm is highly parallelizable and runs efficiently on modern high performance computing clusters. This method enables the ultimate promise of MEG and EEG for five-dimensional imaging of space, time, and frequency activity in the brain and renders it applicable for widespread studies of human cortical dynamics during cognition. PMID:18356081

Dalal, Sarang S.; Guggisberg, Adrian G.; Edwards, Erik; Sekihara, Kensuke; Findlay, Anne M.; Canolty, Ryan T.; Berger, Mitchel S.; Knight, Robert T.; Barbaro, Nicholas M.; Kirsch, Heidi E.; Nagarajan, Srikantan S.

2008-01-01

184

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

185

Tuning time-frequency methods for the detection of metered HF speech  

NASA Astrophysics Data System (ADS)

Speech is metered if the stresses occur at a nearly regular rate. Metered speech is common in poetry, and it can occur naturally in speech, if the speaker is spelling a word or reciting words or numbers from a list. In radio communications, the CQ request, call sign and other codes are frequently metered. In tactical communications and air traffic control, location, heading and identification codes may be metered. Moreover metering may be expected to survive even in HF communications, which are corrupted by noise, interference and mistuning. For this environment, speech recognition and conventional machine-based methods are not effective. We describe Time-Frequency methods which have been adapted successfully to the problem of mitigation of HF signal conditions and detection of metered speech. These methods are based on modeled time and frequency correlation properties of nearly harmonic functions. We derive these properties and demonstrate a performance gain over conventional correlation and spectral methods. Finally, in addressing the problem of HF single sideband (SSB) communications, the problems of carrier mistuning, interfering signals, such as manual Morse, and fast automatic gain control (AGC) must be addressed. We demonstrate simple methods which may be used to blindly mitigate mistuning and narrowband interference, and effectively invert the fast automatic gain function.

Nelson, Douglas J.; Smith, Lawrence H.

2002-12-01

186

Automated extraction and classification of time-frequency contours in humpback vocalizations.  

PubMed

A time-frequency contour extraction and classification algorithm was created to analyze humpback whale vocalizations. The algorithm automatically extracted contours of whale vocalization units by searching for gray-level discontinuities in the spectrogram images. The unit-to-unit similarity was quantified by cross-correlating the contour lines. A library of distinctive humpback units was then generated by applying an unsupervised, cluster-based learning algorithm. The purpose of this study was to provide a fast and automated feature selection tool to describe the vocal signatures of animal groups. This approach could benefit a variety of applications such as species description, identification, and evolution of song structures. The algorithm was tested on humpback whale song data recorded at various locations in Hawaii from 2002 to 2003. Results presented in this paper showed low probability of false alarm (0%-4%) under noisy environments with small boat vessels and snapping shrimp. The classification algorithm was tested on a controlled set of 30 units forming six unit types, and all the units were correctly classified. In a case study on humpback data collected in the Auau Chanel, Hawaii, in 2002, the algorithm extracted 951 units, which were classified into 12 distinctive types. PMID:23297903

Ou, Hui; Au, Whitlow W L; Zurk, Lisa M; Lammers, Marc O

2013-01-01

187

Phase retrieval and time-frequency methods in the measurement of ultrashort laser pulses  

SciTech Connect

Recently several techniques have become available to measure the time- (or frequency-) dependent intensity and phase of ultrashort laser pulses. One of these, Frequency-Resolved Optical Gating (FROG), is rigorous and has achieved single-laser-shot operation. FROG combines the concepts of time-frequency analysis in the form of spectrogram generation (in order to create a two-dimensional problem), and uses a phase-retrieval-based algorithm to invert the experimental data to yield the intensity and phase of the laboratory laser pulse. In FROG it is easy to generate a spectrogram of the unknown signal, and inversion of the spectrogram to recover the signal is the main goal. Because the temporal width of a femtosecond laser pulse is much shorter than anything achievable by electronics, FROG uses the pulse to measure itself. In FROG, the laser pulse is split into two replicas of itself by a partially reflecting beamsplitter, and the two replicas interact with each other in a medium with an instantaneous nonlinear-optical response. This interaction generates a signal field that is then frequency-resolved using a spectrometer. The spectrum of the signal field is measured for all relevant values of the temporal delay between the two pulses. Here, the authors employ FROG and FROG related techniques to measure the time-dependent intensity and phase of an ultrashort laser pulse.

DeLong, K.W.; Fittinghoff, D.N.; Ladera, C.L.; Trebino, R.

1995-02-01

188

Variability and Mode Lifetimes in K Giants: Time-frequency Analysis  

NASA Astrophysics Data System (ADS)

During the period 1999 - 2007, the WIRE spacecraft was the first space-based asteroseismology mission (Buzasi 2002, ASP Conf. Proc. 259, 616). Here we report on the final processing and analysis of WIRE observations of 23 K giant stars. Processing was extended beyond the basic pipeline (Bruntt & Buzasi 2006, Mem. Soc. Ast. Italiana 77, 278) to include filtering the time series based on a granulation and activity model fit in Fourier space. The resulting power spectra were analyzed in a consistent manner to locate the region of peak power and to determine the large separation, as well as to identify major peaks. In addition, we have introduced the use of time-frequency analysis to examine mode lifetimes and variability. Current space missions such as COROT and Kepler are making this a golden age for asteroseismology, and these would seem to have rendered the WIRE data set largely obsolete. However, these data can still serve as a testbed for analysis techniques. Even more significantly, since all WIRE targets were brighter than m = 5, ground-based followup can be performed in a way which is impossible for the much fainter targets of the newer missions.

Preston, Heather L.; Buzasi, D. L.

2010-01-01

189

Characterization of dynamic interactions between cardiovascular signals by time-frequency coherence.  

PubMed

An assessment of the dynamic interactions between cardiovascular signals can provide valuable information to improve the understanding of cardiovascular control. In this study, two methodologies for the characterization of time-frequency (TF) coherence between cardiovascular signals are described. The methodologies are based on the smoothed pseudo-Wigner-Ville distribution (SPWVD) and multitaper spectrogram (MTSP), and include the automatic assessment of the significance level of coherence estimates. The capability to correctly localize TF regions, where signals are locally coupled, is assessed using computer-generated data, and data from healthy volunteers. The SPWVD allows for the localization of these regions with higher accuracy (AC > 96.9% for SNR ? 5 dB) than the MTSP (AC > 84.4% for SNR ? 5 dB). In 14 healthy subjects, TF coherence analysis was used to describe the changes, which a tilt table test provokes in the cardiovascular control. Orthostatic stress provoked an increase in the coupling between R-R variability (RRV) and systolic arterial pressure variability; it did not provoke any significant changes in the coupling between RRV and respiration. In HF band, it decreased the strength of the coupling between RRV and pulse interval variability estimated from arterial pressure signal. PMID:22155936

Orini, Michele; Bailón, Raquel; Mainardi, Luca T; Laguna, Pablo; Flandrin, Patrick

2012-03-01

190

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

PubMed Central

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

Orini, Michele; Van Huffel, Sabine

2013-01-01

191

Time-frequency analysis of HRV data from locally anesthetized patients.  

PubMed

Spectral analysis of Heart Rate Variability (HRV) can be used for the assessment of cardiovascular autonomic control. In this study Smoothed-Pseudo Wigner-Ville Distribution (SPWVD) has been used to evaluate the effect of local anesthesia on HRV parameters in a group of fourteen patients undergoing brachial plexus block (local anesthesia) using the transarterial technique. Instead of using the fixed boundaries of the LF (0.04-0.15 Hz) and the HF (0.15-0.4 Hz) components, the center frequency and the standard deviation spectral extension was used to estimate the boundaries related to the two components of the HRV signal. The boundaries related to the HF component of the signal were estimated using the cross-spectrum between the HRV signal and the respiration signal. The LF component boundaries were estimated directly from the time-frequency representation of the HRV signal. The statistical analysis showed that the (LF)/HF amplitude ratio decreased within an hour of the application of the brachial plexus block compared to the values at the start of the procedure. These changes were observed in eleven of the fourteen patients included in this study. PMID:19963516

Shafqat, K; Pal, S K; Kumari, S; Kyriacou, P A

2009-01-01

192

Detection of transient, regional cardiac repolarization alternans by time-frequency analysis of synthetic electrograms.  

PubMed

Repolarization alternans (RA), originating at the cellular level, is thought to produce an arrhythmogenic substrate, and surface ECG T-wave alternans (TWA) is a marker of risk for sudden cardiac death. In this paper we study RA in the unipolar electrograms (EGM), which represent the electrical activity of the heart at the tissue level. We first describe a simple analytical model to study how RA, simulated as alternating variations of action potential duration, affects EGM-TWA, and then we propose a novel methodology based on time-frequency analysis to detect EGM-TWA which occurs intermittently in few consecutive beats. In a simulation study, we used a 257-node whole heart model to reproduce several patterns of RA. RA involved specific subsets of adjacent nodes (11, 65 and 257), exhibited different amplitudes (0.25, 0.5 and 1 ms) and lasted for 40 consecutive beats of a 80-beat-long test sequence. Results show a relationship between the spatial distribution of RA and EGM-TWA: the smaller the region where RA occurs, the higher the extent of EGM-TWA. With the proposed methodology, we localized those portions of myocardium which exhibited EGM-TWA with an accuracy higher than 90%. PMID:24110552

Orini, Michele; Hanson, Ben; Taggart, Peter; Lambiase, Pier

2013-01-01

193

Cardiorespiratory dynamic response to mental stress: a multivariate time-frequency analysis.  

PubMed

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

Widjaja, Devy; Orini, Michele; Vlemincx, Elke; Van Huffel, Sabine

2013-01-01

194

JOINT NOISE ADAPTIVE TRAINING FOR ROBUST AUTOMATIC SPEECH RECOGNITION Arun Narayanan and DeLiang Wang  

E-print Network

Pre-print JOINT NOISE ADAPTIVE TRAINING FOR ROBUST AUTOMATIC SPEECH RECOGNITION Arun Narayanan explore time-frequency masking to improve noise robust auto- matic speech recognition. Apart from its use separation as a supervised mask estimation problem, we develop a unified DNN framework that jointly improves

Wang, DeLiang "Leon"

195

The time-frequency structure of Jovian narrowband decametric radio emission as a probe of the ionosphere of Jupiter  

NASA Astrophysics Data System (ADS)

We consider the origin of the time-frequency structure of Jovian narrowband decametric radio emission as a consequence of propagation of radiation in the Jovian ionosphere with time varied parameters. Our laboratory and numerical experiments show that the time-frequency structure of dynamic spectra of an initially continuous signal can drastically vary as functions of the form of the magnetic field disturbance in the media where the radiation propagates. Structures similar to those observed in the real experiments, ranging from NB emission and quasiperiodic trains of S bursts to more complex structures, arise in the dynamic spectrum. Assuming the formation of the time-frequency structure of the Jovian narrowband decametric radio emission as a result of propagation of the radiation in the ionosphere and lower magnetosphere of the planet we can get the information about the conditions in the Jovian ionosphere and low magnetosphere.

Shaposhnikov, V.; Korobkov, S.; Gushchin, M.; Kostrov, A.; Rucker, H.; Litvinenko, G.

2012-09-01

196

On the quantification of heart rate variability spectral parameters using time-frequency and time-varying methods.  

PubMed

In the last decades, one of the main challenges in the study of heart rate variability (HRV) signals has been the quantification of the low-frequency (LF) and high-frequency (HF) components of the HRV spectrum during non-stationary events. At this regard, different time-frequency and time-varying approaches have been proposed with the aim to track the modification of the HRV spectra during ischaemic attacks, provocative stress testing, sleep or daily-life activities. The quantitative evaluation of power (and frequencies) of the LF and HF components has been approached in various ways depending on the selected time-frequency method. This paper is an excursus through the most common time-frequency/time-varying representation of the HRV signal with a special emphasis on the algorithms employed for the reliable quantification of the LF and HF parameters and their tracking. PMID:18936017

Mainardi, Luca T

2009-01-28

197

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

Microsoft Academic Search

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

B. Ristic; B. Boashash

1993-01-01

198

Time-frequency quasi-matched intelligence receiver to LPI radar signal  

Microsoft Academic Search

An intelligence receiver quasi-matched to the received LPI radar signals in time and frequency domain is presented. The architecture and prototype using FPGA and DSP are shown. The presented receiver works especially well when the received signals are complex and time-varying.

Deguo Zeng; Hao Cheng; Keyu Long; Xiaodong Zeng; Haiyan Gu; Xiaodong He; Bin Tang

2011-01-01

199

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

Microsoft Academic Search

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

THOMAS KELLER; LAJOS HANZO

2000-01-01

200

4D time-frequency representation for binaural speech signal processing  

NASA Astrophysics Data System (ADS)

Hearing is the ability to detect and process auditory information produced by the vibrating hair cilia residing in the corti of the ears to the auditory cortex of the brain via the auditory nerve. The primary and secondary corti of the brain interact with one another to distinguish and correlate the received information by distinguishing the varying spectrum of arriving frequencies. Binaural hearing is nature's way of employing the power inherent in working in pairs to process information, enhance sound perception, and reduce undesired noise. One ear might play a prominent role in sound recognition, while the other reinforces their perceived mutual information. Developing binaural hearing aid devices can be crucial in emulating the working powers of two ears and may be a step closer to significantly alleviating hearing loss of the inner ear. This can be accomplished by combining current speech research to already existing technologies such as RF communication between PDAs and Bluetooth. Ear Level Instrument (ELI) developed by Micro-tech Hearing Instruments and Starkey Laboratories is a good example of a digital bi-directional signal communicating between a PDA/mobile phone and Bluetooth. The agreement and disagreement of arriving auditory information to the Bluetooth device can be classified as sound and noise, respectively. Finding common features of arriving sound using a four coordinate system for sound analysis (four dimensional time-frequency representation), noise can be greatly reduced and hearing aids would become more efficient. Techniques developed by Szu within an Artificial Neural Network (ANN), Blind Source Separation (BSS), Adaptive Wavelets Transform (AWT), and Independent Component Analysis (ICA) hold many possibilities to the improvement of acoustic segmentation of phoneme, all of which will be discussed in this paper. Transmitted and perceived acoustic speech signal will improve, as the binaural hearing aid will emulate two ears in sound localization, speech understanding in noisy environment, and loudness differentiation.

Mikhael, Raed; Szu, Harold H.

2006-04-01

201

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

202

Using wavelets to decompose the time frequency effects of monetary policy  

NASA Astrophysics Data System (ADS)

Central banks have different objectives in the short and long run. Governments operate simultaneously at different timescales. Many economic processes are the result of the actions of several agents, who have different term objectives. Therefore, a macroeconomic time series is a combination of components operating on different frequencies. Several questions about economic time series are connected to the understanding of the behavior of key variables at different frequencies over time, but this type of information is difficult to uncover using pure time-domain or pure frequency-domain methods. To our knowledge, for the first time in an economic setup, we use cross-wavelet tools to show that the relation between monetary policy variables and macroeconomic variables has changed and evolved with time. These changes are not homogeneous across the different frequencies.

Aguiar-Conraria, Luís; Azevedo, Nuno; Soares, Maria Joana

2008-05-01

203

Moment tensor inversion of waveforms: a two-step time-frequency approach  

NASA Astrophysics Data System (ADS)

We present a moment tensor inversion of waveforms, which is more robust and yields more stable and more accurate results than standard approaches. The inversion is performed in two steps and combines inversions in time and frequency domains. First, the inversion for the source-time function is performed in the frequency domain using complex spectra. Second, the time-domain inversion for the moment tensor is performed using the source-time function calculated in the first step. In this way, we can consider a realistic, complex source-time function and still keep the final moment tensor inversion linear. Using numerical modelling, we compare the efficiency and accuracy of the proposed approach with standard waveform inversions. We study the sensitivity of the retrieved double-couple and non-double-couple components of the moment tensors to noise in the data, to inaccuracies of the location and of the velocity model, and to the type of the focal mechanism. Finally, the proposed moment tensor inversion is tested on real data observed in a complex 3-D inhomogeneous geological environment: a production blast and a rockburst in the Pyhäsalmi ore mine, Finland.

Vavry?uk, Václav; Kühn, Daniela

2012-09-01

204

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

Microsoft Academic Search

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.

Annemarie Surlykke

1992-01-01

205

The optimal selection of mother wavelet shape for the best time-frequency localization of the continuous wavelet transform  

NASA Astrophysics Data System (ADS)

The continuous wavelet transform (CWT) has been utilized as an effective and powerful time-frequency analysis tool for identifying the rapidly-varying characteristics of some dispersive wave signals. Particularly, in the applications of continuous Gabor wavelet transform, its effectiveness is strongly influenced by the shape of the applied Gabor wavelet so the determination of an optimal shape tracing well the time-frequency evolution of a given signal. Since the characteristics of signals are rarely known in advance, the determination of the optimal shape is usually difficult. The main objective of this work is to propose a method to determine the signal-dependent optimal shape of the Gabor wavelet for the best time-frequency localization. To find the optimal Gabor wavelet shape, the notion of the Shannon entropy which measures the extent of signal energy concentration in the time-frequency plane, is employed. To verify the validity of the present approach, a set of elastic bending wave signals generated by an impact in a solid cylinder are analyzed.

Hong, Jin-Chul; Kim, Yoon Young

2003-07-01

206

PHM for air craft power supply generators using real-time frequency estimation based on 3-line DFT  

Microsoft Academic Search

with the advancement of technology and incorporation of sophisticated systems in the aircrafts, the modern aircrafts are highly dependent on the reliable electrical power systems. Prognostic and Health Management (PHM) is the evolving field for fault diagnosis, failure prevention and cost cutting maintenance. In this paper, a real-time frequency estimation algorithm based on 3-line Discrete Fourier transform (DFT) is presented

Aamir Akhtar Siddiqui; Yuan Haibin; Yang QingHua; Yuan Haiwen

2011-01-01

207

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 ...

208

Ceramic joints  

DOEpatents

Butt joints between materials having different coefficients of thermal expansion are prepared having a reduced probability of failure of stress facture. This is accomplished by narrowing/tapering the material having the lower coefficient of thermal expansion in a direction away from the joint interface and not joining the narrow-tapered surface to the material having the higher coefficient of thermal expansion.

Miller, Bradley J. (Worcester, MA); Patten, Jr., Donald O. (Sterling, MA)

1991-01-01

209

Joint Multi-Pitch Detection Using Harmonic Envelope Estimation for Polyphonic Music Transcription  

Microsoft Academic Search

In this paper, a method for automatic transcrip- tion of music signals based on joint multiple-F0 estimation is proposed. As a time-frequency representation, the constant-Q resonator time-frequency image is employed, while a novel noise suppression technique based on pink noise assumption is applied in a preprocessing step. In the multiple-F0 estimation stage, the optimal tuning and inharmonicity parameters are computed

Emmanouil Benetos; Simon Dixon

2011-01-01

210

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

PubMed

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. PMID:25085135

Liu, Yangqing; Tan, Yi; Xie, Huiqiao; Wang, Wenhao; Gao, Zhe

2014-07-01

211

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

NASA Astrophysics Data System (ADS)

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.

Liu, Yangqing; Tan, Yi; Xie, Huiqiao; Wang, Wenhao; Gao, Zhe

2014-07-01

212

Signal Existence Verification (SEV) for GPS Low Received Power Signal Detection Using the Time-Frequency Approach  

PubMed Central

The detection of low received power of global positioning system (GPS) signals in the signal acquisition process is an important issue for GPS applications. Improving the miss-detection problem of low received power signal is crucial, especially for urban or indoor environments. This paper proposes a signal existence verification (SEV) process to detect and subsequently verify low received power GPS signals. The SEV process is based on the time-frequency representation of GPS signal, and it can capture the characteristic of GPS signal in the time-frequency plane to enhance the GPS signal acquisition performance. Several simulations and experiments are conducted to show the effectiveness of the proposed method for low received power signal detection. The contribution of this work is that the SEV process is an additional scheme to assist the GPS signal acquisition process in low received power signal detection, without changing the original signal acquisition or tracking algorithms. PMID:22399903

Jan, Shau-Shiun; Sun, Chih-Cheng

2010-01-01

213

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

NASA Astrophysics Data System (ADS)

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.

Heo, YongHwa; Kim, Kwang-joon

2015-02-01

214

Time-frequency analysis of phase coherence of solar wind turbulence  

NASA Astrophysics Data System (ADS)

Several observations in space plasmas have reported the presence of coherent structures at different plasma scales. Structure formation is believed to be a direct consequence of nonlinear interactions between plasma modes that depend strongly on the phase synchronization of those modes. Analysing directly Fourier phases is however very tricky due to their dependence on an arbitrary time origin and to their 2? periodicity (which makes the phases appear completely mixed/random, even when they are not!). A method, based on Surrogate data, has been developed recently to solve this problem and to allow one to systematically detect coherent structures in turbulent signals [Sahraoui, PRE, 2008]. This 1-D method, however, suffers the weakness that it can estimate the scale of the structures but only over the whole used time series. Here we present a new version of the method that makes a 2-D analysis of the time series, i.e., in the time and the scale (frequency) domains. This makes possible the estimation of the size of the structures and their localisation in time. After validating the new method on synthetic data, we will show applications to the Cluster data. In particular, we will present recent results on coherent structures at small/electron scales in the solar wind. A discussion of the consequence of such observations on theoretical modeling of solar wind turbulence (e.g., weak versus strong, intermittency) will be discussed.

Fauvarque, O.; Sahraoui, F.

2010-12-01

215

Effective implementation of time-frequency matched filter with adapted pre and postprocessing for data-dependent detection of newborn seizures.  

PubMed

Neonatal EEG seizures often manifest as nonstationary and multicomponent signals, necessitating analysis in the time-frequency (TF) domain. This paper presents a novel neonatal seizure detector based on effective implementation of the TF matched filter. In the detection process, the TF signatures of EEG seizure are extracted to construct the TF templates used by the matched filter. Matching pursuit (MP) decomposition and narrowband filtering are proposed for the reduction of artifacts prior to seizure detection. Geometrical correlation is used to consolidate the multichannel detections and to reduce the number of false detections due to remnant artifacts. A data-dependent threshold is defined for the classification of EEG. Using 30 newborn EEG records with seizures, the classification process yielded an overall detection accuracy of 92.4% with good detection rate (GDR) of 84.8% and false detection rate of 0.36FD/h. Better detection performance (accuracy >95%) was recorded for relatively long EEG records with short seizure events. PMID:23972955

Khlif, M S; Colditz, P B; Boashash, B

2013-12-01

216

Joint Projects / Joint Seminars October 2013  

E-print Network

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

Fuchs, Clemens

217

Joint Problems  

MedlinePLUS

... shoulder joint. About 30% of older people have tears in their rotator cuff muscles and tendons, but many have no symptoms. Carpal tunnel syndrome is pressure on a nerve in the wrist and may cause tingling, numbness and pain in the hand. It ... Updated: March 2012 Posted: March 2012

218

A continuous wavelet transform-based method for time-frequency analysis of artefact-corrected heart rate variability data.  

PubMed

Time-frequency analysis of heart rate variability (HRV) provides relevant clinical information. However, time-frequency analysis is very sensitive to artefacts. Artefacts that are present in heart rate recordings may be corrected, but this reduces the variability in the signal and therefore adversely affects the accuracy of calculated spectral estimates. To overcome this limitation of traditional techniques for time-frequency analysis, a new continuous wavelet transform (CWT)-based method was developed in which parts of the scalogram that have been affected by artefact correction are excluded from power calculations. The method was evaluated by simulating artefact correction on HRV data that were originally free of artefacts. Commonly used spectral HRV parameters were calculated by the developed method and by the short-time Fourier transform (STFT), which was used as a reference. Except for the powers in the very low-frequency and low-frequency (LF) bands, powers calculated by the STFT proved to be extremely sensitive to artefact correction. The CWT-based calculations in the high-frequency and very high-frequency bands corresponded well with their theoretical values. The standard deviations of these powers, however, increase with the number of corrected artefacts which is the result of the non-stationarity of the R-R interval series that were analysed. The powers calculated in the LF band turned out to be slightly sensitive to artefact correction, but the results were acceptable up to 20% artefact correction. Therefore, the CWT-based method provides a valuable alternative for the analysis of HRV data that cannot be guaranteed to be free of artefacts. PMID:21849721

Peters, C H L; Vullings, R; Rooijakkers, M J; Bergmans, J W M; Oei, S G; Wijn, P F F

2011-10-01

219

Estimation of multiple, time-varying motions using time-frequency representations and moving-objects segmentation.  

PubMed

We extend existing spatiotemporal approaches to handle time-varying motions estimation of multiple objects. It is shown that multiple, time-varying motions estimation is equivalent to the instantaneous frequency estimation of superpositioned FM sinusoids. Therefore, we apply established signal processing tools, such as time-frequency representations to show that for each time instant, the energy is concentrated along planes in the 3-D space: spatial frequencies-instantaneous frequency. Using fuzzy C-planes, we estimate indirectly the instantaneous velocities. Furthermore, adapting existing approaches to our problem, we attain the identification of the moving objects. The experimental results verify the effectiveness of our methodology. PMID:18482892

Alexiadis, Dimitrios S; Sergiadis, George D

2008-06-01

220

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

NASA Astrophysics Data System (ADS)

This study introduces a new adaptive time-frequency (TF) analysis technique, the synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an ab initio level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type of TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation.

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

2014-11-01

221

A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing Transform  

E-print Network

This study introduces a new adaptive time-frequency (TF) analysis technique, synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an {\\it ab initio} level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation.

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

2014-01-01

222

Analysis and processing of heart rate variability by time-frequency representation: quantification of the pedaling frequency modulation.  

PubMed

It has been shown that a pedaling frequency component can be extracted from the heart rate variability (HRV) signal using a time-varying filter. It is shown that this filter can be implemented directly in the time-frequency plane with different approaches. The need of resampling the data is also discussed with regard to the artifacts produced when the shanon condition is not fulfilled. In order to interpret the similar amplitude profiles of the pedaling component for untrained and trained subjects, an attempt for the model parameters setting is proposed. Consistent results on a large data set illustrate the feasibility of such processing. PMID:19963448

Meste, Olivier; Blain, Gregory; Bermon, Stephane

2009-01-01

223

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

E-print Network

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

Paris-Sud XI, Université de

224

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

PubMed

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

Ebrahimzadeh, Elias; Pooyan, Mohammad; Bijar, Ahmad

2014-01-01

225

A Novel Approach to Predict Sudden Cardiac Death (SCD) Using Nonlinear and Time-Frequency Analyses from HRV Signals  

PubMed Central

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

Ebrahimzadeh, Elias; Pooyan, Mohammad; Bijar, Ahmad

2014-01-01

226

Normal and hypoacoustic infant cry signal classification using time-frequency analysis and general regression neural network.  

PubMed

Crying is the most noticeable behavior of infancy. Infant cry signals can be used to identify physical or psychological status of an infant. Recently, acoustic analysis of infant cry signal has shown promising results and it has been proven to be an excellent tool to investigate the pathological status of an infant. This paper proposes short-time Fourier transform (STFT) based time-frequency analysis of infant cry signals. Few statistical features are derived from the time-frequency plot of infant cry signals and used as features to quantify infant cry signals. General Regression Neural Network (GRNN) is employed as a classifier for discriminating infant cry signals. Two classes of infant cry signals are considered such as normal cry signals and pathological cry signals from deaf infants. To prove the reliability of the proposed features, two neural network models such as Multilayer Perceptron (MLP) and Time-Delay Neural Network (TDNN) trained by scaled conjugate gradient algorithm are also used as classifiers. The experimental results show that the GRNN classifier gives very promising classification accuracy compared to MLP and TDNN and the proposed method can effectively classify normal and pathological infant cries. PMID:21824676

Hariharan, M; Sindhu, R; Yaacob, Sazali

2012-11-01

227

Affective Domain  

NSDL National Science Digital Library

The affective domain can significantly enhance, inhibit or even prevent student learning. The affective domain includes factors such as student motivation, attitudes, perceptions and values. Teachers can increase their effectiveness by considering the affective domain in planning courses, delivering lectures and activities, and assessing student learning. This module contains information and resources for incorporating the affective domain into teaching.

228

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

SciTech Connect

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.

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

229

Use of CROSS-TIME-FREQUENCY Estimators for Structural Identification in Non-Stationary Conditions and Under Unknown Excitation  

NASA Astrophysics Data System (ADS)

This paper introduces a new structural identification method for use in non-stationary conditions, which applies to structures and systems in normal serviceability conditions, under unknown excitation. The proposed method uses auto- and cross-time-frequency transforms of accelerometer signals recorded from the structure to identify the vibration modes. The transforms considered are those in Cohen's class which, in addition to possessing valuable properties for the analysis of mechanical signals, lend themselves to a clear interpretation in energy terms. This method enables modal parameters to be reliably estimated and an earlier technique proposed by the authors which was based on modal filters to be improved. It is further shown that the cross-correlation-based estimators are more effective than techniques based on auto-transformations, due to their noise-filtering properties. Finally, a method to refine the estimate of modal shapes, which avoids autocorrelation, is proposed. The accuracy of the procedure was assessed by means of numerical simulations.

BONATO, P.; CERAVOLO, R.; DE STEFANO, A.; MOLINARI, F.

2000-11-01

230

Dynamic assessment of spontaneous baroreflex sensitivity by means of time-frequency analysis using either RR or pulse interval variability.  

PubMed

In this study we propose a method to continuously assess the changes of spontaneous baroreflex sensitivity (BRS). Systolic arterial pressure and RR intervals are analyzed by time-frequency analysis to estimate their instantaneous powers as well as the time-course of their spectral coherence. The BRS estimated in classical frequency bands is compared to the BRS estimated in dynamic frequency bands centered on respiratory frequency. The possibility of obtaining reliable estimations of the BRS using the pulse interval from the pressure signal as a surrogate of the RR is considered. Results on a tilt table test database suggest that is possible to obtain reliable BRS estimates just from the analysis of the pressure signal, without the need of ECG recordings. PMID:21096388

Orini, Michele; Mainardi, Luca T; Gil, Eduardo; Laguna, Pablo; Bailon, Raquel

2010-01-01

231

Research on vibration response of a multi-faulted rotor system using LMD-based time-frequency representation  

NASA Astrophysics Data System (ADS)

Unbalance, fatigue crack and rotor-stator rub are the three common and important faults in a rotor-bearing system. They are originally interconnected each other, and their vibration behaviors do often show strong nonlinear and transient characteristic, especially when more than one of them coexist in the system. This article is aimed to study the vibration response of the rotor system in presence of multiple rotor faults such as unbalance, crack, and rotor-stator rub, using local mean decomposition-based time-frequency representation. Equations of motion of the multi-faulted Jeffcott rotor, including unbalance, crack, and rub, are presented. By solving the motion equations, steady-state vibration response is obtained in presence of multiple rotor faults. As a comparison, Hilbert-Huang transformation, based on empirical mode decomposition, is also applied to analyze the multi-faults data. By the study some diagnostic recommendations are derived.

Jiao, Weidong; Qian, Suxiang; Chang, Yongping; Yang, Shixi

2012-12-01

232

ERC Advanced Grants List PE domain (alphabetic order)  

E-print Network

chemical kinetic models for cleaner internal combustion engines PE8 227348 Prof. Berger André, Léon NSYS Nonlinear System Identification and Analysis in the Time, Frequency, and Spatio-Temporal Domains Katholieke Universiteit (Radboud University Organisation) NL LOFAR-AUGER From Black Holes to Ultra

Brandenburg, Axel

233

A multivariate time-frequency method to characterize the influence of respiration over heart period and arterial pressure  

NASA Astrophysics Data System (ADS)

Respiratory activity introduces oscillations both in arterial pressure and heart period, through mechanical and autonomic mechanisms. Respiration, arterial pressure, and heart period are, generally, non-stationary processes and the interactions between them are dynamic. In this study we present a methodology to robustly estimate the time course of cross spectral indices to characterize dynamic interactions between respiratory oscillations of heart period and blood pressure, as well as their interactions with respiratory activity. Time-frequency distributions belonging to Cohen's class are used to estimate time-frequency (TF) representations of coherence, partial coherence and phase difference. The characterization is based on the estimation of the time course of cross spectral indices estimated in specific TF regions around the respiratory frequency. We used this methodology to describe the interactions between respiration, heart period variability (HPV) and systolic arterial pressure variability (SAPV) during tilt table test with both spontaneous and controlled respiratory patterns. The effect of selective autonomic blockade was also studied. Results suggest the presence of common underling mechanisms of regulation between cardiovascular signals, whose interactions are time-varying. SAPV changes followed respiratory flow both in supine and standing positions and even after selective autonomic blockade. During head-up tilt, phase differences between respiration and SAPV increased. Phase differences between respiration and HPV were comparable to those between respiration and SAPV during supine position, and significantly increased during standing. As a result, respiratory oscillations in SAPV preceded respiratory oscillations in HPV during standing. Partial coherence was the most sensitive index to orthostatic stress. Phase difference estimates were consistent among spontaneous and controlled breathing patterns, whereas coherence was higher in spontaneous breathing. Parasympathetic blockade did not affect interactions between respiration and SAPV, reduced the coherence between SAPV and HPV and between respiration and HPV. Our results support the hypothesis that non-autonomic, possibly mechanically mediated, mechanisms also contributes to the respiratory oscillations in HPV. A small contribution of sympathetic activity on HPV-SAPV interactions around the respiratory frequency was also observed.

Orini, Michele; Bailón, Raquel; Laguna, Pablo; Mainardi, Luca T.; Barbieri, Riccardo

2012-12-01

234

Knee joint replacement  

MedlinePLUS

Knee joint replacement is surgery to replace a knee joint with a man-made joint. The artificial joint is called a prosthesis . ... cartilage and bone are removed from the knee joint. Man-made pieces are then placed in the ...

235

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 ...

236

JOINT SEMINAR FINAL REPORT  

E-print Network

JOINT SEMINAR FINAL REPORT Project number Name of applicant at FWF: __________________________________ Title of the Joint Seminar: ____________________________________________________ Name of the partner): ____________________________________________________ Name of applicant at partner organisation: _______________________ Date and place of Joint Seminar

Fuchs, Clemens

237

Temporomandibular Joint Disorder  

MedlinePLUS

... news feeds delivered directly to your desktop! more... Temporomandibular Joint Disorder Article Chapters Temporomandibular Joint Disorder What ... men. Updated: November 2008 Previous Next Related Articles: Temporomandibular Joint Disorder (TMD) Are You Biting Off More ...

238

Self-focusing Lamb waves based on the decomposition of the time-reversal operator using time-frequency representation  

NASA Astrophysics Data System (ADS)

Active ultrasonic arrays are very useful for structural health monitoring (SHM) of large plate-like structures. Large areas of a plate can be monitored from a fixed position but it normally requires precise information on material properties. Self-focusing methods can perform well without the exact knowledge of a medium and array parameters. In this paper a method for selective focusing of Lamb waves will be presented. The algorithm is an extension of the DORT method (French acronym for decomposition of time-reversal operator) where the continuous wavelet transform (CWT) is used for the time-frequency representation (TFR) of nonstationary signals instead of the discrete Fourier transform. The performance of the methods is compared and verified in the paper using both simulated and experimental data. It is shown that the extension of the DORT method with the use of TFR considerably improved its resolving ability. To experimentally evaluate the performance of the proposed method, a linear array of small piezoelectric transducers attached to an aluminum plate was used to obtain interelement responses, required for beam self-focusing on targets present in the plate. The array was used for the transmission of signals calculated with the DORT-CWT algorithm. To verify the self-focusing effect the backpropagated field generated in the experiment was sensed using laser scanning vibrometer.

Ambrozinski, Lukasz; Stepinski, Tadeusz; Packo, Pawel; Uhl, Tadeusz

2012-02-01

239

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

PubMed Central

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

Sinex, Donal G.

2013-01-01

240

Compressive sampling of swallowing accelerometry signals using time-frequency dictionaries based on modulated discrete prolate spheroidal sequences  

NASA Astrophysics Data System (ADS)

Monitoring physiological functions such as swallowing often generates large volumes of samples to be stored and processed, which can introduce computational constraints especially if remote monitoring is desired. In this article, we propose a compressive sensing (CS) algorithm to alleviate some of these issues while acquiring dual-axis swallowing accelerometry signals. The proposed CS approach uses a time-frequency dictionary where the members are modulated discrete prolate spheroidal sequences (MDPSS). These waveforms are obtained by modulation and variation of discrete prolate spheroidal sequences (DPSS) in order to reflect the time-varying nature of swallowing acclerometry signals. While the modulated bases permit one to represent the signal behavior accurately, the matching pursuit algorithm is adopted to iteratively decompose the signals into an expansion of the dictionary bases. To test the accuracy of the proposed scheme, we carried out several numerical experiments with synthetic test signals and dual-axis swallowing accelerometry signals. In both cases, the proposed CS approach based on the MDPSS yields more accurate representations than the CS approach based on DPSS. Specifically, we show that dual-axis swallowing accelerometry signals can be accurately reconstructed even when the sampling rate is reduced to half of the Nyquist rate. The results clearly indicate that the MDPSS are suitable bases for swallowing accelerometry signals.

Sejdi?, Ervin; Can, Azime; Chaparro, Luis F.; Steele, Catriona M.; Chau, Tom

2012-12-01

241

Feature extraction based on time-frequency and Independent Component Analysis for improvement of separation ability in Atrial Fibrillation detector.  

PubMed

Due to redundancy of over-dimensioned information, observed often in originally recorded biomedical signals, feature extraction and selection has become focus of much researches connected with biomedical signal processing and classification. Mixed new feature vector combined from time-frequency signal representation (obtained after wavelet transform) and Independent Component Analysis (ICA) applied for non-stationary signals is proposed as a preliminary stage in ECG waveform classification for patients with Atrial Fibrillation (AF). Discrete fast wavelet transform coefficients parameters including energy and entropy measures and components extracted as a result of FastICA algorithm implementation after optimization gave the best classifier performance of whole AF ECG classifier system. System was positively verified on the set of clinically classified ECG signals for control and atrial fibrillation (AF) disease patients taken from MITBIH data base. The measures of specificity and sensitivity computed for the set of 20 AF and 20 patients from control group divided into learning and verifying subsets were used to evaluate presented pattern recognition structure. Different types of wavelet basic functions for feature extraction stage and kernels for SVM classifier structure calculation were tested to find the best system architecture. Obtained results showed, that the ability of generalization and separation for enriched feature extraction based system increased, due to selectively choosing only the most representative features for analyzed AF detection problem. PMID:19163327

Kostka, Pawel S; Tkacz, Ewaryst J

2008-01-01

242

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

PubMed

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

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

2011-07-01

243

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

PubMed

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

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

2014-01-16

244

Spacesuit mobility joints  

NASA Technical Reports Server (NTRS)

Joints for use in interconnecting adjacent segments of an hermetically sealed spacesuit which have low torques, low leakage and a high degree of reliability are described. Each of the joints is a special purpose joint characterized by substantially constant volume and low torque characteristics. Linkages which restrain the joint from longitudinal distension and a flexible, substantially impermeable diaphragm of tubular configuration spanning the distance between pivotally supported annuli are featured. The diaphragms of selected joints include rolling convolutions for balancing the joints, while various joints include wedge-shaped sections which enhance the range of motion for the joints.

Vykukal, H. C. (inventor)

1978-01-01

245

Dartmouth College Computer Science Technical Report TR2002-431 Analysis of Protein Sequences Using Time Frequency and  

E-print Network

to interpret genomic data. In this two-fold study we explore techniques for locating critical amino acid of the Short-Time Fourier Transform and the Continuous Wavelet Transform together with amino acid hydrophobicity in locating important amino acid domains in proteins and also show that the Kolmogorov

246

Thickness Determination of a Plate with Varying Thickness Using AN Artificial Neural Network for Time-Frequency Representation of Lamb Waves  

NASA Astrophysics Data System (ADS)

Thickness estimation of a varying-thickness media is carried out using an algorithm acting as an artificial neural network for time-frequency representation (TFR) of Lamb waves. Dispersion curves are reconstructed using a self adjustable network multi-input fuzzy rules emulated network (MIFREN). The uncertainty in the time-frequency determination is compared with a typical spectrogram technique. The proposed algorithm is computationally less complex than others used in the past. Experimental results were obtained by exciting Lamb waves on an aluminum plate with varying thickness; these were compared with numerical estimations.

Treesatayapun, C.; Baltazar, A.; Balvantin, A.; Kim, J.-Y.

2009-03-01

247

A semi-automated algorithm for studying neuronal oscillatory patterns: a wavelet-based time frequency and coherence analysis.  

PubMed

In many experimental designs, animal observation is associated with local field potential (LFP) recordings in order to find correlations between behavior dynamics and neuronal activity. In such cases, relevant behaviors can occur at different times during free-running recordings and should be put together by the time of analysis. Here, we developed a MATLAB semi-automated toolbox to quantitatively analyze the temporal progression of brain oscillatory activity in multiple free-running LFP recordings obtained during spontaneous behaviors. The algorithm works by selecting LFP epochs at user-defined onset times (locked to behavior, drug injection time, etc.), calculates their time-frequency spectra, detects long-lasting oscillatory events and calculates linear coherence between pair of electrodes. As output, it generates several table-like text and tiff image files, besides group descriptive statistics. To test the algorithm, we recorded hippocampus and amygdala LFPs from rats in different behavioral states: awake (AW), sleep (SWS, slow-wave sleep and REMS, rapid-eye movement sleep) and tonic-clonic seizures. The results show that the software reliably detects all oscillatory events present in up to seven user-defined frequency bands including onset/offset time and duration. It also calculates the global spectral composition per epoch from each subject and the linear coherence (with confidence intervals) as a measure of spectral synchronization between brain regions. The output files provide an easy way to do within-subject as well as across-subject analysis. The routines will be freely available for downloading from our website http://www.neuroimago.usp.br/BPT/. PMID:17935790

Romcy-Pereira, Rodrigo N; de Araujo, Draulio B; Leite, João P; Garcia-Cairasco, Norberto

2008-01-30

248

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

PubMed Central

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

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

249

Temporal features of spike trains in the moth antennal lobe revealed by a comparative time-frequency analysis.  

PubMed

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

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

250

Assessment of the dynamic interactions between heart rate and arterial pressure by the cross time-frequency analysis.  

PubMed

In this study, a framework for the characterization of the dynamic interactions between RR variability (RRV) and systolic arterial pressure variability (SAPV) is proposed. The methodology accounts for the intrinsic non-stationarity of the cardiovascular system and includes the assessment of both the strength and the prevalent direction of local coupling. The smoothed pseudo-Wigner-Ville distribution (SPWVD) is used to estimate the time-frequency (TF) power, coherence, and phase-difference spectra with fine TF resolution. The interactions between the signals are quantified by time-varying indices, including the local coupling, phase differences, time delay, and baroreflex sensitivity (BRS). Every index is extracted from a specific TF region, localized by combining information from the different spectra. In 14 healthy subjects, a head-up tilt provoked an abrupt decrease in the cardiovascular coupling; a rapid change in the phase difference (from 0.37 ± 0.23 to -0.27 ± 0.22 rad) and time delay (from 0.26 ± 0.14 to -0.16 ± 0.16 s) in the high-frequency band; and a decrease in the BRS (from 23.72 ± 7.66 to 6.92 ± 2.51 ms mmHg(-1)). In the low-frequency range, during a head-up tilt, restoration of the baseline level of cardiovascular coupling took about 2 min and SAPV preceded RRV by about 0.85 s during the whole test. The analysis of the Eurobavar data set, which includes subjects with intact as well as impaired baroreflex, showed that the presented methodology represents an improved TF generalization of traditional time-invariant methodologies and can reveal dysfunctions in subjects with baroreflex impairment. Additionally, the results also suggest the use of non-stationary signal-processing techniques to analyze signals recorded under conditions that are usually supposed to be stationary. PMID:22354110

Orini, M; Laguna, P; Mainardi, L T; Bailón, R

2012-03-01

251

Joint ownership and alienability  

Microsoft Academic Search

Most legal traditions view individual ownership as paradigmatic. Yet most property is jointly owned. This paper analyzes how joint ownership affects alienability by focusing on two fundamental issues raised by joint ownership—the nature of the class of those who may benefit from a joint asset and the nature of the process for making decisions about such an asset. I identify

Clifford G. Holderness

2003-01-01

252

Effect of fatigue on the intra-cycle acceleration in front crawl swimming: A time-frequency analysis  

E-print Network

The present study analyzes the changes in acceleration produced by swimmers before and after fatiguing effort. The subjects (n=15) performed a 25-meter crawl series at maximum speed without fatigue, and a second series with fatigue. The data were registered with a synchronized system that consisted in a position transducer (1 kHz) and a video photogrametry (50Hz). The acceleration (ms-2) was obtained by the derivative analysis of the variation of the position with time. The amplitude in the time domain was calculated with the root mean square (RMS); while the peak power (PP), the peak power frequency (PPF) and the spectrum area (SA) was calculated in the frequency domain with Fourier analysis. On one hand, the results of the temporal domain show that the RMS change percentage between series was 67.5% (p<0.001). On the other hand, PP, PPF, and SA show significant changes (p<0.001). PP and SA were reduced by 63.1% and 59.5%, respectively. Our results show that the acceleration analysis of the swimmer with...

Tella, V; Gallach, J E; Benavent, J; Gonzalez, L M; Arellano, R

2008-01-01

253

Effect of fatigue on the intra-cycle acceleration in front crawl swimming: a time-frequency analysis.  

PubMed

The present study analyzes the changes in acceleration produced by swimmers before and after fatiguing effort. The subjects (n = 15) performed a 25-m crawl series at maximum speed without fatigue, and a second series with fatigue. The data were registered with a synchronized system that consisted of a position transducer (1 kHz) and a video photogrametry (50 Hz). The acceleration (ms(-2)) was obtained by the derivative analysis of the variation of the position with time. The amplitude in the time domain was calculated with the root mean square (RMS); while the peak power (PP), the peak power frequency (PPF) and the spectrum area (SA) were calculated in the frequency domain with Fourier analysis. On the one hand, the results of the temporal domain show that the RMS change percentage between series was 67.5% (p < 0.001). On the other hand, PP, PPF, and SA show significant changes (p < 0.001). PP and SA were reduced by 63.1% and 59.5%, respectively. Our results show that the acceleration analysis of the swimmer with Fourier analysis permits a more precise understanding of which propulsive forces contribute to the swimmer performance before and after fatigue appears. PMID:17714719

Tella, V; Toca-Herrera, J L; Gallach, J E; Benavent, J; González, L M; Arellano, R

2008-01-01

254

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 ...

255

Joint Aspiration (Arthrocentesis)  

MedlinePLUS

... JIA, formerly called rheumatoid arthritis, or JRA), systemic lupus erythematosus (SLE), and Lyme disease. Joint aspiration is ... Lyme Disease Risk Juvenile Idiopathic Arthritis Living With Lupus Bones, Muscles, and Joints Lyme Disease Arthritis Word! ...

256

Large displacement spherical joint  

DOEpatents

A new class of spherical joints has a very large accessible full cone angle, a property which is beneficial for a wide range of applications. Despite the large cone angles, these joints move freely without singularities.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2002-01-01

257

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

258

Interaural cross-correlation coefficient, apparent source width, and time/frequency characteristics of binaural running cross-correlation  

NASA Astrophysics Data System (ADS)

The interaural cross-correlation coefficient (IACC) descriptors attempt to characterize in a single number the binaural cross-correlation function at the expense of losing much detail in a manner similar to, but more problematic than, such descriptors as NC, STC, and NRC because much frequency- and rich time-domain information is lost. Recent computer simulations by Mason illuminated these problems and further stimulated the present study. Old binaural impulse recordings run through an analog computer algorithm (drawn from physiological modeling) were re-examined in an attempt to reveal trends and relationships that the current descriptors cannot. Issues of the time and frequency variance of the measured running coefficient are discussed in terms of apparent source width (ASW) for music in Troy Music Hall and simpler spaces.

Conant, David A.

2004-10-01

259

Modulation-domain Kalman filtering for single-channel speech enhancement  

E-print Network

Modulation-domain Kalman filtering for single-channel speech enhancement Stephen So , Kuldip K-domain Kalman filter (MDKF) and compare its performance with other time-domain and acoustic-domain speech changes of the mag- nitude spectrum for both speech and noise. Also, because the Kalman filter is a joint

260

Domain descriptions  

Microsoft Academic Search

Ideas about the meaning of descriptions, aimed at clarifying the relationship between a formal specification and the domain of the system to be specified, are introduced. Understanding of specifications must rest on explicit statements of what they are about and what they assert. The authors argue that current formal specification techniques are inadequate in this respect, and therefore cannot offer

Michael Jackson; P. Zave

1993-01-01

261

Mechanics of Suture Joints  

NASA Astrophysics Data System (ADS)

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.

Li, Yaning; Song, Juha; Ortiz, Christine; Boyce, Mary

2011-03-01

262

Sacroiliac joint pain.  

PubMed

The sacroiliac joint is a source of pain in the lower back and buttocks in approximately 15% of the population. Diagnosing sacroiliac joint-mediated pain is difficult because the presenting complaints are similar to those of other causes of back pain. Patients with sacroiliac joint-mediated pain rarely report pain above L5; most localize their pain to the area around the posterior superior iliac spine. Radiographic and laboratory tests primarily help exclude other sources of low back pain. Magnetic resonance imaging, computed tomography, and bone scans of the sacroiliac joint cannot reliably determine whether the joint is the source of the pain. Controlled analgesic injections of the sacroiliac joint are the most important tool in the diagnosis. Treatment modalities include medications, physical therapy, bracing, manual therapy, injections, radiofrequency denervation, and arthrodesis; however, no published prospective data compare the efficacy of these modalities. PMID:15473677

Dreyfuss, Paul; Dreyer, Susan J; Cole, Andrew; Mayo, Keith

2004-01-01

263

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

NASA Astrophysics Data System (ADS)

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.

Johnson, T. C.; Slater, L. D.; Ntarlagiannis, D.; Day-Lewis, F. D.; Elwaseif, M.

2012-07-01

264

Design of solder joints for self-aligned optoelectronic assemblies  

Microsoft Academic Search

Self-aligning soldering is the critical technology for precision optoelectronic assembly. The pre-assembly solder joint design can improve the final alignment accuracy. In this paper, a public domain software Surface Evolver is modified as a modeling tool for the design of solder joints for self-aligned assemblies. Furthermore, for convenient and efficient design, the results from the numerical model are nondimensionalized and

Wei Lin; Susan K. Patra; Y. C. Lee

1995-01-01

265

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

ERIC Educational Resources Information Center

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…

Warreyn, Petra; Roeyers, Herbert

2014-01-01

266

Investigation of joint disease  

Microsoft Academic Search

The role of nuclear medicine in the diagnosis and management of the major arthropathies is critically reviewed, with particular reference to osteoarthritis, rheumatoid and similar forms of arthritis, ankylosing spondylitis, non-specific back pain, gout, the neuropathic joint, avascular necrosis, infection and the consequences of prosthetic joint insertion. Attention is drawn both to practical applications and deficiencies in current techniques and

M. V. Merrick

1992-01-01

267

Joint Newspaper Operating Agreements.  

ERIC Educational Resources Information Center

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…

Parsons, Marie

268

MISR JOINT_AS Data  

Atmospheric Science Data Center

Joint Aerosol Product (JOINT_AS) The MISR Level 3 Products are global or regional ... field campaigns at daily and monthly time scales. The Joint Aerosol product provides a monthly global statistical summary of MISR ...

2014-07-21

269

JOINT APPENDICES 2005 BUILDING ENERGY  

E-print Network

JOINT APPENDICES CALIFORNIA ENERGY COMMISSION for the 2005 BUILDING ENERGY EFFICIENCY STANDARDS, Deputy Director ENERGY EFFICIENCY AND DEMAND ANALYSIS DIVISION #12;NOTICE This version of the 2005 Joint. #12;TABLE OF CONTENTS I. Joint Appendix I ­ Glossary ........................................... Pages

270

Joint Infection (Beyond the Basics)  

MedlinePLUS

... medications. Artificial joint infection symptoms — People who develop infections immediately after joint replacement surgery typically have pain, redness, and swelling at the joint or drainage from the wound. Those who develop infections later usually notice a ...

271

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

272

Pressure vessel flex joint  

NASA Technical Reports Server (NTRS)

An airtight, flexible joint is disclosed for the interfacing of two pressure vessels such as between the Space Station docking tunnel and the Space Shuttle Orbiter bulkhead adapter. The joint provides for flexibility while still retaining a structural link between the two vessels required due to the loading created by the internal/external pressure differential. The joint design provides for limiting the axial load carried across the joint to a specific value, a function returned in the Orbiter/Station tunnel interface. The flex joint comprises a floating structural segment which is permanently attached to one of the pressure vessels through the use of an inflatable seal. The geometric configuration of the joint causes the tension between the vessels created by the internal gas pressure to compress the inflatable seal. The inflation pressure of the seal is kept at a value above the internal/external pressure differential of the vessels in order to maintain a controlled distance between the floating segment and pressure vessel. The inflatable seal consists of either a hollow torus-shaped flexible bladder or two rolling convoluted diaphragm seals which may be reinforced by a system of straps or fabric anchored to the hard structures. The joint acts as a flexible link to allow both angular motion and lateral displacement while it still contains the internal pressure and holds the axial tension between the vessels.

Kahn, Jon B. (inventor)

1992-01-01

273

DMBC: Domain Names & Web Hosting Domain Names  

E-print Network

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

Stowell, Michael

274

Magnetic domains  

NASA Astrophysics Data System (ADS)

Recently a Nahm transform has been discovered for magnetic bags, which are conjectured to arise in the large n limit of magnetic monopoles of charge n. We interpret these ideas using string theory and present evidence for this conjecture. Our main result concerns the extension of the notion of bags and their Nahm transform to higher gauge theories and arbitrary domains. Bags in four dimensions conjecturally describe the large n limit of n self-dual strings. We show that the corresponding Basu-Harvey equation is the large n limit of an equation describing n M2-branes, and that it has a natural interpretation in loop space. We also formulate our Nahm equations using strong homotopy Lie algebras.

Harland, Derek; Palmer, Sam; Sämann, Christian

2012-10-01

275

First metatarsophalangeal joint arthrodesis.  

PubMed

Arthrodesis of the first metatarsophalangeal joint (MTPJ) is used primarily for end-stage hallux rigidus whereby pain, crepitus, and limitation of motion is noted at the joint. Arthrodesis at the first MTPJ also has it uses as a primary procedure for rheumatoid arthritis when severe deformity is present, as well as for salvage procedures for failed joint arthroplasties with or without implant, fractures with intra-articular extension, avascular necrosis, and infection management. A first MTPJ arthrodesis should provide stable fixation, attain suitable positioning for a reasonable gait, maintain adequate length, and create a stable platform for a plantigrade foot type. PMID:22243568

Rajczy, Robert M; McDonald, Patrick R; Shapiro, Howard S; Boc, Steven F

2012-01-01

276

Compliant Joints For Robots  

NASA Technical Reports Server (NTRS)

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.

Kerley, James J., Jr.

1990-01-01

277

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

278

Joint Special Operations University  

E-print Network

The Joint Special Operations University (JSOU) provides its publications to contribute toward expanding the body of knowledge about joint special operations. JSOU publications advance the insights and recommendations of national security professionals and the Special Operations Forces (SOF) students and leaders for consideration by the SOF community and defense leadership. JSOU is the educational component of the United States Special Operations Command (USSOCOM), MacDill Air Force Base, Florida. The JSOU mission is to educate SOF executive, senior, and intermediate leaders and selected other national and international security decision makers, both military and civilian, through teaching, outreach, and research in the science and art of joint special operations. JSOU provides education to the men and women of SOF and to those who enable the SOF mission in a joint and interagency environment. JSOU conducts research through its Strategic Studies Department where

Brian A. Maher; Ed. D; William S. Wildrick; U. S. Navy; Ret Resident; Senior Fellows; John B. Alexander; Roby C. Barrett, Ph.D.; Joseph D. Celeski; Chuck Cunningham

279

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 ...

280

Temporomandibular Joint Disorders  

MedlinePLUS Videos and Cool Tools

... jaw joint. TMJ disorders can cause headaches, ear pain, bite problems, clicking sounds, locked jaws, and other ... three main categories: Muscle Disorders These disorders include pain in the muscles that control jaw function, as ...

281

New plastic joints for plastic orthoses  

Microsoft Academic Search

Plastic joints for orthoses have more advantages than metal joints. They are lightweight, noiseless comfortable to use, rust proof, corrosion free, and radiolucent. Two types of plastic joints were developed by the authors, one for the ankle joint and the other for the knee joint, elbow joint or hip joint. Polypropylene was chosen as the joint material because of its

H. WATANABE; T. KUTSUNA; H. MORINAGA; T. OKABE

282

Hyperbolic times: frequency versus integrability  

Microsoft Academic Search

We consider dynamical systems on compact manifolds, which are local\\u000adiffeomorphisms outside an exceptional set (a compact submanifold). We are\\u000ainterested in analyzing the relation between the integrability (with respect to\\u000aLebesgue measure) of the first hyperbolic time map and the existence of\\u000apositive frequency of hyperbolic times. We show that some (strong)\\u000aintegrability of the first hyperbolic time map

Jose F Alves; VTOR ARAJO

2004-01-01

283

ROBUST VIDEO RESTORATION BY JOINT SPARSE AND LOW RANK MATRIX APPROXIMATION  

E-print Network

ROBUST VIDEO RESTORATION BY JOINT SPARSE AND LOW RANK MATRIX APPROXIMATION HUI JI, SIBIN HUANG, ZUOWEI SHEN, AND YUHONG XU Abstract. This paper presents a new video restoration scheme based domain, we formulate the video restoration problem as a joint sparse and low-rank matrix approximation

Shen, Zuowei

284

Bullet in Hip Joint  

PubMed Central

Recently, hip arthroscopy has become more popular in the diagnosis and extraction of intraarticular foreign bodies compared to open surgery. If a foreign object such as a bullet is not extracted from the hip joint, it may cause mechanical arthritis, infection and systemic lead toxicity. We present the arthroscopic excision of a bullet from the hip joint of a 33-year-old male patient who sustained a gunshot injury.

Kaya, Ibrahim; Ugras, Akin; Saglam, Necdet; Sungur, Ibrahim; Cetinus, Ercan

2013-01-01

285

Competing Research Joint Ventures  

Microsoft Academic Search

Research and development (R&D) competition among firms has recently been extended to R&D competition involving research joint ventures. It was previously shown that in an industry conducting cost-reducing R&D followed by competition in the product market, if all firms both fully share R&D information and coordinate investments to maximize joint profits, final products prices are lower, and firms' profits are

Morton I. Kamien; Israel Zang

1993-01-01

286

High pressure ceramic joint  

DOEpatents

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures. 4 figures.

Ward, M.E.; Harkins, B.D.

1993-11-30

287

High pressure ceramic joint  

DOEpatents

Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

Ward, Michael E. (Poway, CA); Harkins, Bruce D. (San Diego, CA)

1993-01-01

288

Use of high and low frequency dielectric measurements in the NDE of adhesively bonded composite joints  

NASA Astrophysics Data System (ADS)

Dielectric spectroscopy has been developed as a non-destructive technique for assessment of moisture content and structural integrity of adhesively bonded joints. Knowledge of these parameters is particularly crucial for the aerospace industry, since environmental degradation of adhesive joints presents a major limit on their utilization. High and low frequency measurements have been carried out on joints assembled from CFRP adherend, and a commercially available adhesive (AF 163-2K). The samples have been aged in deionised water at 75oC to chart the effect water ingress has on bond durability. In addition, some joints have been exposed to cryogenic temperatures to mimic the conditions joints experience whilst an aircraft is in flight. In this way it has been possible to determine the extent of degradation caused by freezing of water within the joint structure. Dielectric behaviour of the joints was studied in both the frequency and in the time domain. Frequency domain analysis allows the amount and effects of moisture ingress in the bondline to be assessed, whereas the time domain highlights the onset of joint defects with increasing exposure time. Mechanical testing of the joints has been carried out to enable correlation between changes in strength and failure mechanism due to moisture ingress, with changes in the dielectric data. In addition, dielectric studies of the neat adhesive have been undertaken, as have gravimetric and dynamic mechanical thermal analysis. These have helped reveal the effects of ageing upon the adhesive layer itself.

Pethrick, R. A.; Hayward, D.; McConnell, B. K.; Crane, R. L.

2005-05-01

289

Dissimilar metals joint evaluation  

NASA Technical Reports Server (NTRS)

Dissimilar metals tubular joints between 2219-T851 aluminum alloy and 304L stainless steel were fabricated and tested to evaluate bonding processes. Joints were fabricated by four processes: (1) inertia (friction) weldings, where the metals are spun and forced together to create the weld; (2) explosive welding, where the metals are impacted together at high velocity; (3) co-extrusion, where the metals are extruded in contact at high temperature to promote diffusion; and (4) swaging, where residual stresses in the metals after a stretching operation maintain forced contact in mutual shear areas. Fifteen joints of each type were prepared and evaluated in a 6.35 cm (2.50 in.) O.D. size, with 0.32 cm (0.13 in.) wall thickness, and 7.6 cm (3.0 in) total length. The joints were tested to evaluate their ability to withstand pressure cycle, thermal cycle, galvanic corrosion and burst tests. Leakage tests and other non-destructive test techniques were used to evaluate the behavior of the joints, and the microstructure of the bond areas was analyzed.

Wakefield, M. E.; Apodaca, L. E.

1974-01-01

290

Studying Eco Climatic Domains  

NSDL National Science Digital Library

Activity is a Project BudBurst/National Ecological Observatory Network (NEON) exploration of eco-climactic domains, as defined by NEON, by investigating characteristics of a specific domain and studying two representative plants in that domain.

Neon; Budburst, Project

291

New Joint Sealants. Criteria, Design and Materials.  

ERIC Educational Resources Information Center

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…

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

292

Time frequency analysis of laser Doppler flowmetry signals recorded in response to a progressive pressure applied locally on anaesthetized healthy rats  

NASA Astrophysics Data System (ADS)

The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal, in response to a local non-noxious pressure applied progressively on the skin of both healthy humans and rats. This phenomenon is not entirely understood yet. In the present work, a time-frequency analysis is applied to signals recorded on anaesthetized healthy rats, at rest and during a cutaneous pressure-induced vasodilation (PIV). The comparison, at rest and during PIV, of the scalogram relative energies and scalogram relative amplitudes in five bands, corresponding to five characteristic frequencies, shows an increased contribution for the endothelial related metabolic activity in PIV signals, till 400 s after the beginning of the progressive pressure application. The other subsystems (heart, respiration, myogenic and neurogenic activities) contribute relatively less during PIV than at rest. The differences are statistically significant for all the relative activities in the interval 0-200 s following the beginning of the pressure. These results and others obtained on patients, such as diabetics, could increase the understanding of some cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers.

Humeau, Anne; Koïtka, Audrey; Abraham, Pierre; Saumet, Jean-Louis; L'Huillier, Jean-Pierre

2004-03-01

293

Spatially variable stage-driven groundwater-surface water interaction inferred from time-frequency analysis of distributed temperature sensing data  

NASA Astrophysics Data System (ADS)

Characterization of groundwater-surface water exchange is essential for improving understanding of contaminant transport between aquifers and rivers. Fiber-optic distributed temperature sensing (FODTS) provides rich spatiotemporal datasets for quantitative and qualitative analysis of groundwater-surface water exchange. We demonstrate how time-frequency analysis of FODTS and synchronous river stage time series from the Columbia River adjacent to the Hanford 300-Area, Richland, Washington, provides spatial information on the strength of stage-driven exchange of uranium contaminated groundwater in response to subsurface heterogeneity. Although used in previous studies, the stage-temperature correlation coefficient proved an unreliable indicator of the stage-driven forcing on groundwater discharge in the presence of other factors influencing river water temperature. In contrast, S-transform analysis of the stage and FODTS data definitively identifies the spatial distribution of discharge zones and provided information on the dominant forcing periods (?2 d) of the complex dam operations driving stage fluctuations and hence groundwater-surface water exchange at the 300-Area.

Mwakanyamale, Kisa; Slater, Lee; Day-Lewis, Frederick; Elwaseif, Mehrez; Johnson, Carole

2012-03-01

294

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 Central

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

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

2014-01-01

295

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

E-print Network

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...

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

296

Mapping knowledge domains: Characterizing PNAS  

PubMed Central

A review of data mining and analysis techniques that can be used for the mapping of knowledge domains is given. Literature mapping techniques can be based on authors, documents, journals, words, and/or indicators. Most mapping questions are related to research assessment or to the structure and dynamics of disciplines or networks. Several mapping techniques are demonstrated on a data set comprising 20 years of papers published in PNAS. Data from a variety of sources are merged to provide unique indicators of the domain bounded by PNAS. By using funding source information and citation counts, it is shown that, on an aggregate basis, papers funded jointly by the U.S. Public Health Service (which includes the National Institutes of Health) and non-U.S. government sources outperform papers funded by other sources, including by the U.S. Public Health Service alone. Grant data from the National Institute on Aging show that, on average, papers from large grants are cited more than those from small grants, with performance increasing with grant amount. A map of the highest performing papers over the 20-year period was generated by using citation analysis. Changes and trends in the subjects of highest impact within the PNAS domain are described. Interactions between topics over the most recent 5-year period are also detailed. PMID:14963238

Boyack, Kevin W.

2004-01-01

297

Joints in a Cornstarch Analog  

NSDL National Science Digital Library

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.

Crider, Juliet

298

Hip joint replacement  

MedlinePLUS

... Jones CA. Total joint arthroplasties: current concepts of patient outcomes after surgery. Rheum Dis Clin North Am . 2007;33(1):71-86. Schmalzried TP. Metal-metal bearing surfaces in hip arthroplasty. Orthopedics . 2009;32. Lindstrom D, Sadr Azodi O, Wladis ...

299

Dolphin Skeleton (Gliding Joint)  

NSDL National Science Digital Library

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.

Ketan Patel (California State University, Fullerton;)

2007-07-14

300

Clad metal joint closure  

SciTech Connect

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.

Siebert, O.W.

1985-04-09

301

An uncertainty principle for real signals in the fractional Fourier transform domain  

Microsoft Academic Search

The fractional Fourier transform (FrFT) can be thought of as a generalization of the Fourier transform to rotate a signal representation by an arbitrary angle ? in the time-frequency plane. A lower bound on the uncertainty product of signal representations in two FrFT domains for real signals is obtained, and it is shown that a Gaussian signal achieves the lower

Sudarshan Shinde; Vikram M. Gadre

2001-01-01

302

Joint Institute Marine and Atmospheric  

E-print Network

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

Hawai'i at Manoa, University of

303

Joint Seminar UNIVERSITY OF GEORGIA  

E-print Network

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

Wang, Lily

304

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

305

Double slotted socket spherical joint  

DOEpatents

A new class of spherical joints is disclosed. These spherical joints are capable of extremely large angular displacements (full cone angles in excess of 270.degree.), while exhibiting no singularities or dead spots in their range of motion. These joints can improve or simplify a wide range of mechanical devices.

Bieg, Lothar F. (Albuquerque, NM); Benavides, Gilbert L. (Albuquerque, NM)

2001-05-22

306

Ideal time-frequency masking algorithms lead to different speech intelligibility and quality in normal-hearing and cochlear implant listeners.  

PubMed

Hearing impaired listeners using cochlear implants (CIs) suffer from a decrease in speech intelligibility (SI) in adverse listening conditions. Time-frequency masks are often applied to perform noise suppression in an attempt to increase SI. Two important masks are the so-called ideal binary mask (IBM) with its binary weights and the ideal Wiener filter (IWF) with its continuous weights. It is unclear which of the masks has the highest potential for SI and speech quality enhancement in CI users. In this study, both approaches for SI and quality enhancement were compared. The investigations were conducted in normal-hearing (NH) subjects listening to noise vocoder CI simulations and in CI users. The potential for SI improvement was assessed in a sentence recognition task with ideal mask estimates in multitalker babble and with an interfering talker. The robustness of the approaches was evaluated with simulated estimation errors. CI users assessed the speech quality in a preference rating. The IWF outperformed the IBM in NH listeners. In contrast, no significant difference was obtained in CI users. Estimation errors degraded SI in CI users for both approaches. In terms of quality, the IWF outperformed, slightly, the IBM processed signals. The outcomes of this study suggest that the mask pattern is not that crucial for CIs. Results of speech enhancement algorithms obtained with NH subjects listening to vocoded or normally processed stimuli do not translate to CI users. This outcome means that the effect of new strategies has to be quantified with the user group considered. PMID:25167542

Koning, Raphael; Madhu, Nilesh; Wouters, Jan

2015-01-01

307

Joint Degrees & Promotion towards European Students  

E-print Network

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

Di Pillo, Gianni

308

49 CFR 213.121 - Rail joints.  

Code of Federal Regulations, 2012 CFR

...Transportation 4 2012-10-01 2012-10-01 false Rail joints. 213.121 Section 213.121 Transportation...SAFETY STANDARDS Track Structure § 213.121 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2012-10-01

309

49 CFR 213.121 - Rail joints.  

Code of Federal Regulations, 2013 CFR

...Transportation 4 2013-10-01 2013-10-01 false Rail joints. 213.121 Section 213.121 Transportation...SAFETY STANDARDS Track Structure § 213.121 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2013-10-01

310

49 CFR 213.121 - Rail joints.  

Code of Federal Regulations, 2011 CFR

...Transportation 4 2011-10-01 2011-10-01 false Rail joints. 213.121 Section 213.121 Transportation...SAFETY STANDARDS Track Structure § 213.121 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2011-10-01

311

49 CFR 213.121 - Rail joints.  

Code of Federal Regulations, 2010 CFR

...Transportation 4 2010-10-01 2010-10-01 false Rail joints. 213.121 Section 213.121 Transportation...SAFETY STANDARDS Track Structure § 213.121 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2010-10-01

312

Finger Joint Injuries.  

PubMed

Finger joint dislocations and collateral ligament tears are common athletic hand injuries. Treatment of the athlete requires a focus on safe return to play and maximizing function. Certain dislocations, such as proximal interphalangeal and distal interphalangeal volar dislocations, may be associated with tendon injuries and must be treated accordingly. Treatment of other dislocations is ultimately determined by postreduction stability, with many dislocations amenable to nonoperative treatment (ie, immobilization followed by rehabilitation). Protective splinting does not necessarily preclude athletic participation. Minor bone involvement typically does not affect the treatment plan, but significant articular surface involvement may necessitate surgical repair or stabilization. Percutaneous and internal fixation are the mainstays of surgical treatment. Treatment options that do not minimize recovery or allow the patient to return to protected play, such as external fixation, are generally avoided during the season of play. Undertreated joint injuries and unrecognized ligament injuries can result in long term disability. PMID:25455398

Prucz, Roni B; Friedrich, Jeffrey B

2015-01-01

313

Prosthetic elbow joint  

NASA Technical Reports Server (NTRS)

An artificial, manually positionable elbow joint for use in an upper extremity, above-elbow, prosthetic is described. The prosthesis provides a locking feature that is easily controlled by the wearer. The instant elbow joint is very strong and durable enough to withstand the repeated heavy loadings encountered by a wearer who works in an industrial, construction, farming, or similar environment. The elbow joint of the present invention comprises a turntable, a frame, a forearm, and a locking assembly. The frame generally includes a housing for the locking assembly and two protruding ears. The forearm includes an elongated beam having a cup-shaped cylindrical member at one end and a locking wheel having a plurality of holes along a circular arc on its other end with a central bore for pivotal attachment to the protruding ears of the frame. The locking assembly includes a collar having a central opening with a plurality of internal grooves, a plurality of internal cam members each having a chamfered surface at one end and a V-shaped slot at its other end; an elongated locking pin having a crown wheel with cam surfaces and locking lugs secured thereto; two coiled compression springs; and a flexible filament attached to one end of the elongated locking pin and extending from the locking assembly for extending and retracting the locking pin into the holes in the locking wheel to permit selective adjustment of the forearm relative to the frame. In use, the turntable is affixed to the upper arm part of the prosthetic in the conventional manner, and the cup-shaped cylindrical member on one end of the forearm is affixed to the forearm piece of the prosthetic in the conventional manner. The elbow joint is easily adjusted and locked between maximum flex and extended positions.

Weddendorf, Bruce C. (inventor)

1994-01-01

314

Laboratory characterization of rock joints  

SciTech Connect

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.

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

315

Joint attention studies in normal and autistic children using NIRS  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

316

Joint measurements and Bell inequalities  

E-print Network

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.

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

2005-09-20

317

An intermediate complexity marine ecosystem model for the global domain  

Microsoft Academic Search

A new marine ecosystem model designed for the global domain is presented, and model output is compared with field data from nine different locations. Field data were collected as part of the international Joint Global Ocean Flux Study (JGOFS) program, and from historical time series stations. The field data include a wide variety of marine ecosystem types, including nitrogen- and

J. Keith Moore; Scott C. Doney; Joanie A. Kleypas; David M. Glover; Inez Y. Fung

2001-01-01

318

Joint Temporal Density Measurements for Two-Photon State Characterization  

E-print Network

We demonstrate a new technique for characterizing two-photon quantum states based on joint temporal correlation measurements using time resolved single photon detection by femtosecond upconversion. We measure for the first time the joint temporal density of a two-photon entangled state, showing clearly the time anti-correlation of the coincident-frequency entangled photon pair generated by ultrafast spontaneous parametric down-conversion under extended phase-matching conditions. The new technique enables us to manipulate the frequency entanglement by varying the down-conversion pump bandwidth to produce a nearly unentangled two-photon state that is expected to yield a heralded single-photon state with a purity of 0.88. The time-domain correlation technique complements existing frequency-domain measurement methods for a more complete characterization of photonic entanglement in quantum information processing.

Onur Kuzucu; Franco N. C. Wong; Sunao Kurimura; Sergey Tovstonog

2008-07-10

319

Steganalysis of JPEG Images with Joint Transform Features  

Microsoft Academic Search

\\u000a In this paper, a universal steganalysis scheme for JPEG images based upon joint transform features is presented. We first\\u000a analyzed two different transform domains (Discrete Cosine Transform and Discrete Wavelet Transform) separately, to extract\\u000a features for steganalysis. Then a combination of these two feature sets is constructed and employed for steganalysis. A Fisher\\u000a Linear Discriminant classifier is trained on features

Zohaib Khan; Atif Bin Mansoor

2009-01-01

320

Posttraumatic Temporomandibular Joint Disorders  

PubMed Central

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

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

2009-01-01

321

Osteoarthritis: The Peripheral Joints  

PubMed Central

Understanding of osteoarthritis has increased: the simplistic “wear and tear” concept no longer holds and this has positive clinical implications. A parallel development has taken place in treatment techniques: there is increasing expertise in the use of physical measures and in new orthopedic reconstructive surgical approaches to multiple joints. This gives the physician alternative approaches to the patient with painful and disabling osteoarthritis. The timing of these treatment options and some considerations which lead to orthopedic referral are considered in this general discussion. Imagesp285-aFig. 1Fig. 2Fig. 3 PMID:20469342

Robinson, Harold S.

1981-01-01

322

Metal to ceramic sealed joint  

DOEpatents

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. 11 figures.

Lasecki, J.V.; Novak, R.F.; McBride, J.R.

1991-08-27

323

Metal to ceramic sealed joint  

DOEpatents

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.

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

1991-01-01

324

Strength of Welded Aircraft Joints  

NASA Technical Reports Server (NTRS)

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.

Brueggeman, W C

1937-01-01

325

Early Developments in Joint Action  

PubMed Central

Joint action, critical to human social interaction and communication, has garnered increasing scholarly attention in many areas of inquiry, yet its development remains little explored. This paper reviews research on the growth of joint action over the first 2 years of life to show how children become progressively more able to engage deliberately, autonomously, and flexibly in joint action with adults and peers. It is suggested that a key mechanism underlying the dramatic changes in joint action over the second year of life is the ability to reflect consciously on oneself and one’s behavior and volition and correspondingly, on the behavior, goals, and intentions of others. PMID:23087769

Brownell, Celia A.

2012-01-01

326

Joint collaborative technology experiment  

NASA Astrophysics Data System (ADS)

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.

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

327

Jointly Sponsored Research Program  

SciTech Connect

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.

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

2009-03-31

328

Glenohumeral Joint Injections  

PubMed Central

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

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

2013-01-01

329

Joint torque sensory feedback in the control of a PUMA manipulator  

Microsoft Academic Search

The design of a joint torque sensor for a PUMA 500 and its characteristics are described. Using this sensor, a joint torque servomechanism is designed and implemented. A model of the actuator-transmission-load system, including flexibility, is developed and verified using both time- and frequency-domain techniques. Compensators based on this model are designed and tested. Experimental results obtained from pure torque

L. E. Pfeffer; O. Khatib; J. Hake

1989-01-01

330

Joint Information CenterJoint Information Center Deepwater Horizon Response  

E-print Network

and it is determined to be within the Deepwater Horizon Oil Spill Re- sponse area, a wildlife response team is notified when they see the birds that have been impacted by the Deepwa- ter Horizon/BP oil spill. WhileJoint Information CenterJoint Information Center Deepwater Horizon Response Incident Command Post

331

Joint shape morphogenesis precedes cavitation of the developing hip joint.  

PubMed

The biology and mechanobiology of joint cavitation have undergone extensive investigation, but we have almost no understanding of the development of joint shape. Joint morphogenesis, the development of shape, has been identified as the 'least understood aspect of joint formation' (2005, Birth Defects Res C Embryo Today 75, 237), despite the clinical relevance of shape morphogenesis to postnatal skeletal malformations such as developmental dysplasia of the hip. In this study, we characterise development of early hip joint shape in the embryonic chick using direct capture 3D imaging. Contrary to formerly held assumptions that cavitation precedes morphogenesis in joint development, we have found that the major anatomical features of the adult hip are present at Hamburger Hamilton (HH)32, a full day prior to cavitation of the joint at HH34. We also reveal that the pelvis undergoes significant changes in orientation with respect to the femur, despite the lack of a joint cavity between the rudiments. Furthermore, we have identified the appearance of the ischium and pubis several developmental stages earlier than was previously reported, illustrating the value and importance of direct capture 3D imaging. PMID:24266523

Nowlan, Niamh C; Sharpe, James

2014-04-01

332

Relationship between joint effusion, joint pain, and protein levels in joint lavage fluid of patients with internal derangement and osteoarthritis of the temporomandibular joint  

Microsoft Academic Search

Purpose: The purpose of this study was to investigate the relationship between the presence of joint effusion, joint pain, and protein levels in joint lavage fluid (JL) of patients with internal derangement (ID) and osteoarthritis (OA) of the temporomandibular joint (TMJ).Patients and Methods: Thirty-eight joints in 26 patients with ID and OA of the TMJ were studied. Magnetic resonance imaging

Tetsu Takahashi; Hirokazu Nagai; Hiroshi Seki; Masayuki Fukuda

1999-01-01

333

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.

2008-08-27

334

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.

335

Passive Ball Capture Joint  

NASA Technical Reports Server (NTRS)

A passive ball capture joint has a sleeve with a plurality of bores distributed about a circumference thereof and formed therethrough at an acute angle relative to the sleeve's longitudinal axis. A spring-loaded retainer is slidingly fitted in each bore and is biased such that, if allowed, will extend at least partially into the sleeve to retain a ball therein. A ring, rotatably mounted about the bores, has an interior wall defining a plurality of shaped races that bear against the spring-loaded retainers. A mechanized rotational force producer is coupled to the ring. The ring can be rotated from a first position (that presses the retainers into the sleeve to lock the ball in place) to a second position (that allows the retainers to springback out of the sleeve to release the ball).

Cloyd, Richard A. (Inventor); Bryan, Thomas C. (Inventor)

2003-01-01

336

Corynebacterium Prosthetic Joint Infection  

PubMed Central

Identification of Corynebacterium species may be challenging. Corynebacterium species are occasional causes of prosthetic joint infection (PJI), but few data are available on the subject. Based on the literature, C. amycolatum, C. aurimucosum, C. jeikeium, and C. striatum are the most common Corynebacterium species that cause PJI. We designed a rapid PCR assay to detect the most common human Corynebacterium species, with a specific focus on PJI. A polyphosphate kinase gene identified using whole-genome sequence was targeted. The assay differentiates the antibiotic-resistant species C. jeikeium and C. urealyticum from other species in a single assay. The assay was applied to a collection of human Corynebacterium isolates from multiple clinical sources, and clinically relevant species were detected. The assay was then tested on Corynebacterium isolates specifically associated with PJI; all were detected. We also describe the first case of C. simulans PJI. PMID:22337986

Cazanave, Charles; Greenwood-Quaintance, Kerryl E.; Hanssen, Arlen D.

2012-01-01

337

Exercise and the Knee Joint.  

ERIC Educational Resources Information Center

This report by the President's Council on Physical Fitness and Sports examines the effects of various forms of physical exercise on the knee joint which, because of its vulnerability, is especially subject to injury. Discussion centers around the physical characteristics of the joint, commonly used measurements for determining knee stability,…

Clarke, H. Harrison, Ed.

1976-01-01

338

Space Station alpha joint bearing  

NASA Technical Reports Server (NTRS)

Perhaps the most critical structural system aboard the Space Station is the Solar Alpha Rotary Joint which helps align the power generation system with the sun. The joint must provide structural support and controlled rotation to the outboard transverse booms as well as power and data transfer across the joint. The Solar Alpha Rotary Joint is composed of two transition sections and an integral, large diameter bearing. Alpha joint bearing design presents a particularly interesting problem because of its large size and need for high reliability, stiffness, and on orbit maintability. The discrete roller bearing developed is a novel refinement to cam follower technology. It offers thermal compensation and ease of on-orbit maintenance that are not found in conventional rolling element bearings. How the bearing design evolved is summarized. Driving requirements are reviewed, alternative concepts assessed, and the selected design is described.

Everman, Michael R.; Jones, P. Alan; Spencer, Porter A.

1987-01-01

339

Shock transmissibility of threaded joints  

SciTech Connect

Sandia National Laboratories (SNL) designs mechanical systems with threaded joints that must survive high shock environments. These mechanical systems include penetrators that must survive soil and rock penetration; drilling pipe strings that must survive rock-cutting, shock environments; and laydown weapons that must survive delivery impact shock. This paper summarizes an analytical study and an experimental evaluation of compressive, one-dimensional, shock transmission through a threaded joint in a split Hopkinson bar configuration. Thread geometries were scaled to simulate large diameter threaded joints with loadings parallel to the axis of the threads. Both strain and acceleration were evaluated with experimental measurements and analysis. Analytical results confirm the experimental conclusions that in this split Hopkinson bar configuration, the change in the one-dimensional shock wave by the threaded joint is localized to a length equal to a few diameters` length beyond the threaded joint.

Hansen, N.R.; Bateman, V.I.; Brown, F.A.

1996-12-31

340

Space Domain Awareness for Manned GEO Servicing  

NASA Astrophysics Data System (ADS)

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.

Blake, T.

2010-09-01

341

Domains and Naive Theories  

PubMed Central

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

Gelman, Susan A.; Noles, Nicholaus S.

2013-01-01

342

11 CFR 9034.8 - Joint fundraising.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 2012-01-01 false Joint fundraising. 9034.8 Section 9034...MATCHING FUND ENTITLEMENTS § 9034.8 Joint fundraising. (a) General...funds under this subchapter may engage in joint fundraising with other candidates,...

2012-01-01

343

11 CFR 9034.8 - Joint fundraising.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 2012-01-01 true Joint fundraising. 9034.8 Section 9034...MATCHING FUND ENTITLEMENTS § 9034.8 Joint fundraising. (a) General...funds under this subchapter may engage in joint fundraising with other candidates,...

2013-01-01

344

29 CFR 791.2 - Joint employment.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 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...

2010-07-01

345

29 CFR 791.2 - Joint employment.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

346

24 CFR 570.308 - Joint requests.  

Code of Federal Regulations, 2014 CFR

...Development 3 2014-04-01 2013-04-01 true Joint requests. 570.308 Section 570.308 Housing...BLOCK GRANTS Entitlement Grants § 570.308 Joint requests. (a) Joint requests and cooperation agreements....

2014-04-01

347

11 CFR 9034.8 - Joint fundraising.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 2014-01-01 false Joint fundraising. 9034.8 Section 9034...MATCHING FUND ENTITLEMENTS § 9034.8 Joint fundraising. (a) General...funds under this subchapter may engage in joint fundraising with other candidates,...

2014-01-01

348

29 CFR 791.2 - Joint employment.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

349

24 CFR 570.308 - Joint requests.  

Code of Federal Regulations, 2013 CFR

...Development 3 2013-04-01 2013-04-01 false Joint requests. 570.308 Section 570.308 Housing...BLOCK GRANTS Entitlement Grants § 570.308 Joint requests. (a) Joint requests and cooperation agreements....

2013-04-01

350

11 CFR 9034.8 - Joint fundraising.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 2011-01-01 false Joint fundraising. 9034.8 Section 9034...MATCHING FUND ENTITLEMENTS § 9034.8 Joint fundraising. (a) General...funds under this subchapter may engage in joint fundraising with other candidates,...

2011-01-01

351

29 CFR 791.2 - Joint employment.  

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

352

24 CFR 570.308 - Joint requests.  

Code of Federal Regulations, 2012 CFR

...Development 3 2012-04-01 2012-04-01 false Joint requests. 570.308 Section 570.308 Housing...BLOCK GRANTS Entitlement Grants § 570.308 Joint requests. (a) Joint requests and cooperation agreements....

2012-04-01

353

11 CFR 9034.8 - Joint fundraising.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Joint fundraising. 9034.8 Section 9034...MATCHING FUND ENTITLEMENTS § 9034.8 Joint fundraising. (a) General...funds under this subchapter may engage in joint fundraising with other candidates,...

2010-01-01

354

24 CFR 570.308 - Joint requests.  

Code of Federal Regulations, 2010 CFR

...Development 3 2010-04-01 2010-04-01 false Joint requests. 570.308 Section 570.308 Housing...BLOCK GRANTS Entitlement Grants § 570.308 Joint requests. (a) Joint requests and cooperation agreements....

2010-04-01

355

24 CFR 570.308 - Joint requests.  

Code of Federal Regulations, 2011 CFR

...Development 3 2011-04-01 2010-04-01 true Joint requests. 570.308 Section 570.308 Housing...BLOCK GRANTS Entitlement Grants § 570.308 Joint requests. (a) Joint requests and cooperation agreements....

2011-04-01

356

29 CFR 791.2 - Joint employment.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 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...

2011-07-01

357

22 CFR 228.34 - Joint ventures.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Joint ventures. 228.34 Section 228.34 Foreign Relations...Services for USAID Financing § 228.34 Joint ventures. A joint venture or unincorporated association is eligible only...

2011-04-01

358

22 CFR 228.34 - Joint ventures.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Joint ventures. 228.34 Section 228.34 Foreign Relations...Services for USAID Financing § 228.34 Joint ventures. A joint venture or unincorporated association is eligible only...

2010-04-01

359

Low frequency electromagnetic coupling through joints  

NASA Astrophysics Data System (ADS)

Low frequency (quasi-static) penetration through joints is investigated numerically for a uniform joint and for local electrical contact joints. Overlapped joints improve greatly the shielding effectiveness of loaded aperture in comparison to an aperture bonded by non-overlapped junctions. The uniform joint results lead to the same results as Casey's formalism while the local electrical contact joints results show that shielding effectiveness reached constant value.

Sternberg, Marc; Gobin, Vincent; Issac, Francois

360

Use of time-frequency analysis to investigate temporal patterns of cardiac autonomic response during head-up tilt in chronic fatigue syndrome.  

PubMed

Although a number of studies have reported alterations in cardiac autonomic nervous system function in chronic fatigue syndrome (CFS), the results are not consistent across studies. Reasons for these discrepancies include (1) the use of a heterogeneous patient sample that included those with orthostatic postural tachycardia (POTS), a condition with an autonomic changes, and (2) the use of frequency domain techniques which require a stationary signal and averaging data across relatively long epochs. To deal with these shortcomings, we used the smoothed pseudo-Wigner-Ville transform (SPWVT) to analyze heart rate variability (HRV) and blood pressure variability (BPV) during head-up tilt (HUT) by separating CFS patients into those with and without POTS. SPWVT has the advantage of providing instantaneous information about autonomic function under nonstable physiological conditions. We studied 18 CFS patients without POTS, eight CFS patients with POTS and 25 sedentary healthy controls during supine rest and during the first 10 min after HUT. While we found significant effects of postural change in both groups for all autonomic variables, there were significant group x time interactions between CFS without POTS and controls for only instant center frequency (ICF) within the low frequency region both from HRV (p=0.02) and from BPV (p=0.01). Although the physiological meaning of ICF still remains unknown, the data suggest that even CFS patients without POTS may have a subtle underlying disturbance in autonomic function. PMID:15296795

Yoshiuchi, Kazuhiro; Quigley, Karen S; Ohashi, Kyoko; Yamamoto, Yoshiharu; Natelson, Benjamin H

2004-06-30

361

Common Bolted Joint Analysis Tool  

NASA Technical Reports Server (NTRS)

Common Bolted Joint Analysis Tool (comBAT) is an Excel/VB-based bolted joint analysis/optimization program that lays out a systematic foundation for an inexperienced or seasoned analyst to determine fastener size, material, and assembly torque for a given design. Analysts are able to perform numerous what-if scenarios within minutes to arrive at an optimal solution. The program evaluates input design parameters, performs joint assembly checks, and steps through numerous calculations to arrive at several key margins of safety for each member in a joint. It also checks for joint gapping, provides fatigue calculations, and generates joint diagrams for a visual reference. Optimum fastener size and material, as well as correct torque, can then be provided. Analysis methodology, equations, and guidelines are provided throughout the solution sequence so that this program does not become a "black box:" for the analyst. There are built-in databases that reduce the legwork required by the analyst. Each step is clearly identified and results are provided in number format, as well as color-coded spelled-out words to draw user attention. The three key features of the software are robust technical content, innovative and user friendly I/O, and a large database. The program addresses every aspect of bolted joint analysis and proves to be an instructional tool at the same time. It saves analysis time, has intelligent messaging features, and catches operator errors in real time.

Imtiaz, Kauser

2011-01-01

362

Joint numerical ranges, quantum maps, and joint numerical shadows  

E-print Network

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.

Eugene Gutkin; Karol Zyczkowski

2012-07-05

363

Support vector domain description  

Microsoft Academic Search

This paper shows the use of a data domain description method, inspired by the support vector machine by Vapnik, called the support vector domain description (SVDD). This data description can be used for novelty or outlier de- tection. A spherically shaped decision boundary around a set of objects is constructed by a set of support vectors describing the sphere boundary.

David M. J. Tax; Robert P. W. Duin

1999-01-01

364

Protein structural domain identification  

Microsoft Academic Search

A simple method for the definition of protein structural domains is described that requires only a-carbon coordin- ate data. The basic method, which encodes no specific aspects of protein structure, captures the essence of most domains but does not give high enough priority to the integrity of b-sheet structure. This aspect was encouraged both by a bias toward attaining intact

William R. Taylor

1999-01-01

365

Domain Theory and Integration  

Microsoft Academic Search

We present a domain-theoretic framework for measure theory and integration of bounded real-valued functions with respect to bounded Borel measures on compact metric spaces. The set of normalised Borel measures of the metric space can be embedded into the maximal elements of the normalised probabilistic power domain of its upper space. Any bounded Borel measure on the compact metric space

Abbas Edalat

1995-01-01

366

Domain Theory and Integration  

Microsoft Academic Search

We present a domain-theoretic framework for measure theory and integration of bounded read-valued functions with respect to bounded Borel measures on compact metric spaces. The set of normalised Borel measures of the metric space can be embedded into the maximal elements of the normalised probabilistic power domain of its upper space. Any bounded Borel measure on the compact metric space

Abbas Edalat

1994-01-01

367

The complexity of joint computation  

E-print Network

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 ...

Drucker, Andrew Donald

2012-01-01

368

JOINT NOTICE OF PRIVACY PRACTICES  

E-print Network

JOINT NOTICE OF PRIVACY PRACTICES THIS NOTICE DESCRIBES HOW MEDICAL INFORMATION ABOUT YOU MAY disclosure of your immunization data to the Wisconsin Immunization Registry. A request for restriction should

369

A simple nonlinear joint model  

NASA Technical Reports Server (NTRS)

Hertzian contact theory is applied to a butt joint with specially mismatched bearing surfaces to devise a simple mathematical model of nonlinear axial force-displacement behavior in jointed members. Normalized tangent stiffness-force plots, for several values of a joint imperfection parameter, are presented for the sample case of solid structural members of circular section. The results illustrate the potential problem of high joint compliance at low axial-force levels, as well as the generally desirable stiffening and linearizing effects of preload. A nonlinear oscillator problem based on the static model is also formulated and solved to illustrate the effect of amplitude on natural frequency. As expected, natural frequency is low when amplitude is small. The results call attention to the important roles that tight tolerances and preload are expected to play in the design and fabrication of deployable and erectable truss-type space structures.

Fichter, W. B.

1986-01-01

370

A pain in the joints.  

PubMed

Arthralgia is a rare but recognised complication of meningococcal septicaemia. We report a case of a 29-year-old man presenting with a 24?h history of fever, joint swelling and subsequent development of a non-blanching, petechial rash. He was treated for probable meningococcal septicaemia and the causative pathogen was later identified as Neisseria meningitidis. He was treated with ceftriaxone and after 10?days the pain and swelling in his joints improved. PMID:25694633

Peters, Rosie; Virani, Farzana; Haddadin, Yazan; Baldowska, Helena

2015-01-01

371

Joint probabilities and quantum cognition  

E-print Network

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.

J. Acacio de Barros

2012-06-26

372

Joint probabilities and quantum cognition  

SciTech Connect

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.

Acacio de Barros, J. [Liberal Studies, 1600 Holloway Ave., San Francisco State University, San Francisco, CA 94132 (United States)

2012-12-18

373

Young Children's Understanding of Joint Commitments  

ERIC Educational Resources Information Center

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

Grafenhain, Maria; Behne, Tanya; Carpenter, Malinda; Tomasello, Michael

2009-01-01

374

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

375

7 CFR 97.14 - Joint applicants.  

Code of Federal Regulations, 2013 CFR

...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...

2013-01-01

376

7 CFR 97.14 - Joint applicants.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

377

7 CFR 97.14 - Joint applicants.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

378

7 CFR 97.14 - Joint applicants.  

Code of Federal Regulations, 2010 CFR

...Agriculture 3 2010-01-01 2010-01-01 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...

2010-01-01

379

7 CFR 97.14 - Joint applicants.  

Code of Federal Regulations, 2014 CFR

...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...

2014-01-01

380

SAMPLE Joint Venture Agreement [March 2010  

E-print Network

SAMPLE Joint Venture Agreement [March 2010] This Joint Venture Agreement (JVA) is entered and Technology (NIST) as a joint venture (JV) to conduct certain specified research; Whereas, the Parties wish _____________________________ to serve as the JV Administrator (Administrator) for the joint venture and wish to authorize

Magee, Joseph W.

381

49 CFR 213.351 - Rail joints.  

Code of Federal Regulations, 2011 CFR

...Transportation 4 2011-10-01 2011-10-01 false Rail joints. 213.351 Section 213.351 Transportation...Operations at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2011-10-01

382

49 CFR 213.351 - Rail joints.  

Code of Federal Regulations, 2012 CFR

...Transportation 4 2012-10-01 2012-10-01 false Rail joints. 213.351 Section 213.351 Transportation...Operations at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2012-10-01

383

49 CFR 213.351 - Rail joints.  

Code of Federal Regulations, 2010 CFR

...Transportation 4 2010-10-01 2010-10-01 false Rail joints. 213.351 Section 213.351 Transportation...Operations at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2010-10-01

384

49 CFR 213.351 - Rail joints.  

Code of Federal Regulations, 2013 CFR

...Transportation 4 2013-10-01 2013-10-01 false Rail joints. 213.351 Section 213.351 Transportation...Operations at Track Classes 6 and Higher § 213.351 Rail joints. (a) Each rail joint, insulated joint, and compromise...

2013-10-01

385

Partnering Across Borders: Negotiating Organizational Culture in a German-Japanese Joint Venture  

Microsoft Academic Search

This study expands theoretical research on negotiated culture by testing basic assumptions in the context of a German-Japanese joint venture. Data collected by semi-structured interviews are analyzed using textual analysis software to uncover key issues that became catalysts for negotiation. Results include a model of cultural negotiation linking organizational events with issue domains as points of departure for negotiations. Results

Mary Yoko Brannen; Jane E. Salk

2000-01-01

386

Joint T1 and Brain Fiber Log-Demons Registration Using Currents to Model Geometry  

E-print Network

Joint T1 and Brain Fiber Log-Demons Registration Using Currents to Model Geometry Viviana Siless1´on, Concepci´on, Chile Abstract. We present an extension of the diffeomorphic Geometric Demons algorithm which the superiority of the Log-domain Geometric Demons over their purely iconic counterparts. Keywords: Registration

Paris-Sud XI, Université de

387

Strongly Semicontinuous Domains and Semi-FS Domains  

PubMed Central

We are mainly concerned with some special kinds of semicontinuous domains and relationships between them. New concepts of strongly semicontinuous domains, meet semicontinuous domains and semi-FS domains are introduced. It is shown that a dcpo L is strongly semicontinuous if and only if L is semicontinuous and meet semicontinuous. It is proved that semi-FS domains are strongly semicontinuous. Some interpolation properties of semiway-below relations in (strongly) semicontinuous bc-domains are given. In terms of these properties, it is proved that strongly semicontinuous bc-domains, in particular strongly semicontinuous lattices, are all semi-FS domains. PMID:25215317

He, Qingyu; Xu, Luoshan

2014-01-01

388

How joint is the joint attention of apes and human infants? Malinda Carpenter  

E-print Network

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

Carpenter, M.alinda

389

Visualizing Knowledge Domains.  

ERIC Educational Resources Information Center

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;…

Borner, Katy; Chen, Chaomei; Boyack, Kevin W.

2003-01-01

390

Prosthetic Joint Infections in Elderly Patients  

Microsoft Academic Search

Although prosthetic joint infections (PJIs) occur in a small proportion of patients following total joint arthroplasty, they\\u000a have catastrophic consequences on morbidity and joint function and carry a high economic burden in the elderly patients.\\u000a \\u000a Clinical presentation of prosthetic joint infection is highly variable, and differentiating a painful joint arthroplasty secondary\\u000a to mechanical loosening from an indolent infection can be

Camelia E Marculescu; Elie F. Berbari; Douglas R. Osmon

391

Management of acromioclavicular joint injuries.  

PubMed

Acromioclavicular joint injuries are among the most common shoulder girdle injuries in athletes and most commonly result from a direct force to the acromion with the arm in an adducted position. Acromioclavicular joint injuries often present with associated injuries to the glenohumeral joint, including an increased incidence of superior labrum anterior posterior (SLAP) tears that may warrant further evaluation and treatment. Anteroposterior stability of the acromioclavicular joint is conferred by the capsule and acromioclavicular ligaments, of which the posterior and superior ligaments are the strongest. Superior-inferior stability is maintained by the coracoclavicular (conoid and trapezoid) ligaments. Type-I or type-II acromioclavicular joint injuries have been treated with sling immobilization, early shoulder motion, and physical therapy, with favorable outcomes. Return to activity can occur when normal shoulder motion and strength are obtained and the shoulder is asymptomatic as compared with the contralateral normal extremity. The management of type-III injuries remains controversial and is individualized. While a return to the previous level of functional activity with nonsurgical treatment has been documented in a number of case series, surgical reduction and coracoclavicular ligament reconstruction has been associated with a favorable outcome and can be considered in patients who place high functional demands on their shoulders or in athletes who participate in overhead sports. Surgical management is indicated for high-grade (?type IV) acromioclavicular joint injuries to achieve anatomic reduction of the acromioclavicular joint, reconstruction of the coracoclavicular ligaments, and repair of the deltotrapezial fascia. Outcomes after surgical reconstruction of the coracoclavicular ligaments have been satisfactory with regard to achieving pain relief and return to functional activities, but further improvements in the biomechanical strength of these constructs are necessary to avoid loss of reduction and creep with cyclic loading. PMID:24382728

Li, Xinning; Ma, Richard; Bedi, Asheesh; Dines, David M; Altchek, David W; Dines, Joshua S

2014-01-01

392

Psychomotor Domain Taxonomy  

NSDL National Science Digital Library

Pennsylvania State University's "Teaching and Learning with Technology" program presents an overview of Bloom's Psychomotor Domain Taxonomy, which is characterized by progressive levels of behaviors from observation to mastery of a physical skill. Definitions and examples are given of the four levels, along with behavioral verbs appropriate for the psychomotor domain. The site also features an extensive directory of links to ideas that will assist in the development of high-quality instruction.

Pennsylvania State University

393

Localization on Snowflake Domains  

E-print Network

The geometric features of the square and triadic Koch snowflake drums are compared using a position entropy defined on the grid points of the discretizations (pre-fractals) of the two domains. Weighted graphs using the geometric quantities are created and random walks on the two pre-fractals are performed. The aim is to understand if the existence of narrow channels in the domain may cause the `localization' of eigenfunctions.

Britta Daudert; Michel L. Lapidus

2006-09-28

394

An analysis of a joint shear model for jointed media with orthogonal joint sets; Yucca Mountain Site Characterization Project  

SciTech Connect

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.

Koteras, J.R.

1991-10-01

395

The effect of configuration parameters of time-frequency maps in the detection of intra-QRS electrical transients of the signal-averaged electrocardiogram: impact in clinical diagnostic performance.  

PubMed

Time-frequency maps of signal-averaged electrocardiogram based on a short time Fourier transform (STFT) technique analysis was employed to assess the presence of high frequency electrical transients (turbulence) and arrhythmia risk assessment. The optimal configuration set of STFT variables aiming at risk stratification for sustained monomorphic ventricular tachycardia (SMVT) is still undetermined. Different configuration variables, including analyzing time-window widths, starting positions, relative displacements, and zero-padding for STFT time-frequency maps constructions were combined on each analyzing averaged signal from 18 healthy controls and 18 subjects presenting inducible SMVT. Spectral turbulence analysis (STA) was, thus, carried out according to conventional procedures. The optimal configuration set of variables for STA was obtained by assessing the total diagnostic accuracy of all combinations of parameters. The optimal diagnostic performance was found at 86% total diagnostic accuracy as compared to 56% using previous defined normality thresholds (p=0.01). Present configuration set of variables is distinctive from previously defined set of variables and improves risk stratification. PMID:19428130

Benchimol-Barbosa, P R; Nasario-Junior, O; Nadal, J

2010-11-01

396

Technique and application for quantifying dynamic shoulder joint kinematics and glenohumeral joint contact patterns  

E-print Network

The shoulder (glenohumeral) joint has the greatest range of motion of all human joints; as a result, it is particularly vulnerable to dislocation and injury. The ability to accurately measure dynamic in-vivo joint kinematics ...

Massimini, Daniel Frank

2014-01-01

397

Using Domain Ontology as Domain Knowledge for Requirements Elicitation  

Microsoft Academic Search

Domain knowledge is one of crucial factors to get a great success in requirements elicitation of high quality, and only domain experts, not requirements analysts, have it. We pro- pose a new requirements elicitation method ORE (Ontology based Requirements Elicitation), where a domain ontology can be used as domain knowledge. In our method, a do- main ontology plays a role

Haruhiko Kaiya; Motoshi Saeki

2006-01-01

398

FRF based joint dynamics modeling and identification  

NASA Astrophysics Data System (ADS)

Complex structures, such as machine tools, are comprised of several substructures connected to each other through joints to form the assembled structures. Joints can have significant contributions on the behavior of the overall assembly and ignoring joint effects in the design stage may result in considerable deviations from the actual dynamic behavior. The identification of joint dynamics enables us to accurately predict overall assembled dynamics by mathematically combining substructure dynamics through the equilibrium and compatibility conditions at the joint. The essence of joint identification is the determination of the difference between the measured overall dynamics and the rigidly coupled substructure dynamics. In this study, we investigate the inverse receptance coupling (IRC) method and the point-mass joint model, which considers the joint as lumped mass, damping and stiffness elements. The dynamic properties of the joint are investigated using both methods through a finite element (FE) simulation and experimental tests. `100

Mehrpouya, Majid; Graham, Eldon; Park, Simon S.

2013-08-01

399

Joint measurability through Naimark's theorem  

E-print Network

We use Naimark's dilation theorem in order to characterize the joint measurability of two POVMs. Then, we analyze the joint measurability of two commutative POVMs $F_1$ and $F_2$ which are the smearing of two self-adjoint operators $A_1$ and $A_2$ respectively. We prove that the compatibility of $F_1$ and $F_2$ is connected to the existence of two compatible self-adjoint dilations $A_1^+$ and $A_2^+$ of $A_1$ and $A_2$ respectively. As a corollary we prove that each couple of self-adjoint operators can be dilated to a couple of compatible self-adjoint operators. Next, we analyze the joint measurability of the unsharp position and momentum observables and show that it provides a master example of the scheme we propose. Finally, we give a sufficient condition for the compatibility of two effects.

Roberto Beneduci

2014-04-05

400

Rheumatoid arthritis affecting temporomandibular joint  

PubMed Central

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune inflammatory disorder that is characterized by joint inflammation, erosive properties and symmetric multiple joint involvement. Temporomandibular joint (TMJ) is very rare to be affected in the early phase of the disease, thus posing diagnostic challenges for the dentist. Conventional radiographs fail to show the early lesions due to its limitations. More recently cone-beam computed tomography (CBCT) has been found to diagnose the early degenerative changes of TMJ and hence aid in the diagnosis of the lesions more accurately. Our case highlights the involvement of TMJ in RA and the role of advanced imaging (CBCT) in diagnosing the bony changes in the early phase of the disease.

Sodhi, Amandeep; Naik, Shobha; Pai, Anuradha; Anuradha, Ardra

2015-01-01

401

Joint attention and language evolution  

NASA Astrophysics Data System (ADS)

This study investigates how more advanced joint attentional mechanisms, rather than only shared attention between two agents and an object, can be implemented and how they influence the results of language games played by these agents. We present computer simulations with language games showing that adding constructs that mimic the three stages of joint attention identified in children's early development (checking attention, following attention, and directing attention) substantially increase the performance of agents in these language games. In particular, the rates of improved performance for the individual attentional mechanisms have the same ordering as that of the emergence of these mechanisms in infants' development. These results suggest that language evolution and joint attentional mechanisms have developed in a co-evolutionary way, and that the evolutionary emergence of the individual attentional mechanisms is ordered just like their developmental emergence.

Kwisthout, Johan; Vogt, Paul; Haselager, Pim; Dijkstra, Ton

2008-06-01

402

Mechanobiological simulations of prenatal joint morphogenesis.  

PubMed

Joint morphogenesis is the process in which prenatal joints acquire their reciprocal and interlocking shapes. Despite the clinical importance of the process, it remains unclear how joints acquire their shapes. In this study, we simulate 3D mechanobiological joint morphogenesis for which the effects of a range of movements (or lack of movement) and different initial joint shapes are explored. We propose that static hydrostatic compression inhibits cartilage growth while dynamic hydrostatic compression promotes cartilage growth. Both pre-cavitational (no muscle contractions) and post-cavitational (with muscle contractions) phases of joint development were simulated. Our results showed that for hinge type motion (planar motion from 45° to 120°) the proximal joint surface developed a convex profile in the posterior region and the distal joint surface developed a slightly concave profile. When 3D movements from 40° to -40° in two planes were applied, simulating a rotational movement, the proximal joint surface developed a concave profile whereas the distal joint surface rudiment acquire a rounded convex profile, showing an interlocking shape typical of a ball and socket joint. The significance of this research is that it provides new and important insights into normal and abnormal joint development, and contributes to our understanding of the mechanical factors driving very early joint morphogenesis. An enhanced understanding of how prenatal joints form is critical for developing strategies for early diagnosis and preventative treatments for congenital musculoskeletal abnormalities such as developmental dysplasia of the hip. PMID:24529755

Giorgi, Mario; Carriero, Alessandra; Shefelbine, Sandra J; Nowlan, Niamh C

2014-03-21

403

Long-term outcome of multiple joint procedures in haemophilia.  

PubMed

In elderly people with haemophilia (PWH), surgery of more than one joint of the lower extremities might be needed. Multiple joint procedures (MJP) were introduced in 1995, defined as any combination of Total Knee or Total Hip Arthroplasty or Ankle Arthrodesis during one in-hospital stay. The expectation is that by means of such procedures this specific population is able to physically function better for an extended period of time. Thus, they will participate in their society in an optimal way. In this study, we tried to describe an outcome after MJP, including pre- and post-operative pain and range of motion (ROM), and recommend measurement tools. 22 of 37 PWH who underwent MJP between 1995 and 2012 were available for assessment. Pain (WFH score) and range of motion were compared pre and postoperatively. Current outcome was described by VAS per joint, nocturnal and overall pain, MACTAR, Hemophilia Activity List, SF36, and EQ-5D. Mean age at surgery was 50, 3 years (SD 8, 3); mean follow-up 12 years (1-18 years). Pain (VAS) decreased post-surgery (Median 1 - 1, 5), but moderate pain remained. Extension of knees slightly increased, but both knee flexion and ankle plantar and dorsal flexion decreased. PWH reported the ability to stand longer but also pointed at specific problems, e.g. riding a bike (MACTAR). The HAL showed limited activities (functional domains), especially in the 'complex lower extremity' (22, 8/100). The SF36 and EQ-5D showed a mix of physical problems of our population, while experiencing moderate pain and reasonable physical functioning. This led us to the conclusion that adequate follow-up is needed: ROM of all joints, VAS of all joints as well as nocturnal and overall pain, HAL, SF36 and EQ5D. Performance based activities and participation need further attention. PMID:24533953

de Kleijn, P; Sluiter, D; Vogely, H Ch; Lindeman, E; Fischer, K

2014-03-01

404

Joint strength in RCS frames  

E-print Network

. 2 Specimen 2. . . . . . . 4. 5. 2. 3 Specimen 3 4. 5. 2. 4 Specimen 4, 4. 6 PREDICTED FAILURE MECHANISMS (CONTINUOUS BEAM DIRECTION) . . 4. 6. 1 ASCE Design Equations (ASCE 1994) 4 6, 1. 1 Joint Panel Shear 4. 6. 1. 2 Vertical Bearing . 4. 6... Vertical Bearing. 4. 6. 4 Beam Failure Mechanism. Page 4. 6. 5 Column Failure Mechanism 4. 6. 6 Predicted Failure Mechanisms 4. 7 JOINT STRENGTH PREDICTIONS (DISCONTINUOUS BEAM DIRECTION). 5. RESPONSE 5. 1 INTRODUCTION . . 5. 2. GENERAL BEHAVIOR 5...

Kirby, Cynthia Dawn

1998-01-01

405

Solder Joint Health Monitoring Testbed  

NASA Technical Reports Server (NTRS)

A method of monitoring the health of selected solder joints, called SJ-BIST, has been developed by Ridgetop Group Inc. under a Small Business Innovative Research (SBIR) contract. The primary goal of this research program is to test and validate this method in a flight environment using realistically seeded faults in selected solder joints. An additional objective is to gather environmental data for future development of physics-based and data-driven prognostics algorithms. A test board is being designed using a Xilinx FPGA. These boards will be tested both in flight and on the ground using a shaker table and an altitude chamber.

Delaney, Michael M.; Flynn, James G.; Browder, Mark E.

2009-01-01

406

Predicting domain-domain interactions using a parsimony approach  

PubMed Central

We propose a novel approach to predict domain-domain interactions from a protein-protein interaction network. In our method we apply a parsimony-driven explanation of the network, where the domain interactions are inferred using linear programming optimization, and false positives in the protein network are handled by a probabilistic construction. This method outperforms previous approaches by a considerable margin. The results indicate that the parsimony principle provides a correct approach for detecting domain-domain contacts. PMID:17094802

Guimarães, Katia S; Jothi, Raja; Zotenko, Elena; Przytycka, Teresa M

2006-01-01

407

First metatarsophalangeal joint range of motion : influence of ankle joint position and gastrocsoleus muscle stretching.  

E-print Network

??[Truncated abstract] First metatarsophalangeal joint (MTPJ1) motion is an important factor in normal weight transference during walking. Disruptions to normal range can influence joints both… (more)

North, Ian Graham

2008-01-01

408

Domain Representability of Metric Spaces  

Microsoft Academic Search

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

Jens Blanck

1997-01-01

409

Optimal domain decomposition strategies  

NASA Technical Reports Server (NTRS)

The primary interest of the authors is in the area of grid generation, in particular, optimal domain decomposition about realistic configurations. A grid generation procedure with optimal blocking strategies has been developed to generate multi-block grids for a circular-to-rectangular transition duct. The focus of this study is the domain decomposition which optimizes solution algorithm/block compatibility based on geometrical complexities as well as the physical characteristics of flow field. The progress realized in this study is summarized in this paper.

Yoon, Yonghyun; Soni, Bharat K.

1995-01-01

410

Coarsening of the Sn-Pb Solder Microstructure in Constitutive Model-Based Predictions of Solder Joint Thermal Mechanical Fatigue  

SciTech Connect

Thermal mechanical fatigue (TMF) is an important damage mechanism for solder joints exposed to cyclic temperature environments. Predicting the service reliability of solder joints exposed to such conditions requires two knowledge bases: first, the extent of fatigue damage incurred by the solder microstructure leading up to fatigue crack initiation, must be quantified in both time and space domains. Secondly, fatigue crack initiation and growth must be predicted since this metric determines, explicitly, the loss of solder joint functionality as it pertains to its mechanical fastening as well as electrical continuity roles. This paper will describe recent progress in a research effort to establish a microstructurally-based, constitutive model that predicts TMF deformation to 63Sn-37Pb solder in electronic solder joints up to the crack initiation step. The model is implemented using a finite element setting; therefore, the effects of both global and local thermal expansion mismatch conditions in the joint that would arise from temperature cycling.

Vianco, P.T.; Burchett, S.N.; Neilsen, M.K.; Rejent, J.A.; Frear, D.R.

1999-04-12

411

Plating To Reinforce Welded Joints  

NASA Technical Reports Server (NTRS)

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.

Otousa, J. E.

1982-01-01

412

Sea Lion Skeleton (Gliding Joint)  

NSDL National Science Digital Library

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.

Ketan Patel (California State University, Fullerton;Student, B)

2007-07-14

413

Joint measurements and Svetlichny's inequality  

E-print Network

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.

Yang Xiang; Wei Ren

2010-12-27

414

A JOINT PROGRAM OF Interactive  

E-print Network

TECHNOLOGY #12;Specialist areas in the multimedia sectors are growing rapidly in North America, Asia, imagination, fun and technology. The Interactive Multimedia and Design (IMD) program providesA JOINT PROGRAM OF Interactive Multimedia and Design www.bitdegree.ca BACHELOR OF INFORMATION

Dawson, Jeff W.

415

Space station rotary joint mechanisms  

NASA Technical Reports Server (NTRS)

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.

Driskill, Glen W.

1986-01-01

416

The Rationale for Joint Mobilization.  

ERIC Educational Resources Information Center

This paper presents an overview of the functions of connective tissue and the mechanisms of joint injury and contracture formation in relation to therapeutic exercise. The components of connective tissue operation are explained, including fibroblasts, macrophages, plasma cells, and collagen. An examination of the histology of connective tissue as…

Burkhardt, Sandy

417

Solders in Real Electronic Joints  

NASA Astrophysics Data System (ADS)

Undercooling and recalescence were studied using the differential scanning calorimetry (DSC) method on real electronic systems. Two solder pastes, Sn62.5Pb36.5Ag1 and Sn96.5Ag3Cu0.5, were used for preparation of electronic joints. Various combinations of these solders and soldering pads with different surface finishes such as Cu, Cu-Ni-Au, Cu-Sn, and Cu-Sn99Cu1 were used. During melting of both pastes, the Sn and Sn99Cu1 surface finishes immediately dissolved in the solder and the Cu surface coating was exposed to the melt. Therefore, practically the same undercooling was found for the Cu, Cu-Sn, and Cu-Sn99Cu1 coatings. The lowest undercooling was found for the Cu-Ni-Au surface finish for both solder pastes. If two separated electronic joints were made on the sample, two separate peaks were found in the DSC signal during solidification. In the sample with only one joint, only one exothermic peak was found. These findings were observed for all paste/surface finish combinations. These data were analyzed, showing that this effect is a consequence of undercooling and recalescence: Latent heat released during solidification of the joint increases the surrounding temperature and influences all the processes taking place.

Rudajevová, A.; Dušek, K.

2014-07-01

418

The Joint Gravity Model 3  

Microsoft Academic Search

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

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

419

Arthrodesis of the Trapeziometacarpal Joint  

Microsoft Academic Search

Over a 10-year period, 32 trapeziometacarpal (TM) joint fusions were performed in 29 patients, and reviewed. Pin fixation with tension band wiring was used in 14 cases, screws in eight cases, a plate in six cases, K-wires in three cases and staple fixation in one case. None was bone grafted. Splinting was applied for 4 to 5 weeks. There were

A. CHAMAY; F. PIAGET-MOREROD

1994-01-01

420

The Joint M requires 42  

E-print Network

Term, First Y se 0 Managerial Eco Financial Manag 11 Management 16 Production M Core Course (se g TermThe Joint M towards bo requires 42 Fall Term, Course AC 506 Ma MKT 518 M MGT 517 Or OM 506 Dec ST 509 Stati Summer: Fall Term, Course GBA 525 Bu MGT 542 M MBA Electiv MSCE Electi MSCE Core

Carver, Jeffrey C.

421

Cryopumping Field Joint Can Testing  

NASA Technical Reports Server (NTRS)

For long installations, vacuum jacketed piping often comes in 40 foot sections that are butt welded together in the field. A short can is then welded over the bare pipe connection to allow for insulation to be protected from the environment. Traditionally, the field joint is insulated with multilayer insulation and a vacuum is pulled on the can to minimize heat leak through the bare section and prevent frost from forming on the pipe section. The vacuum jacketed lines for the Ares I mobile launch platform were to be a combined 2000 feet long, with 60+ pipe sections and field joint cans. Historically, Kennedy Space Center has drilled a hole in the long sections to create a common vacuum with the field joint can to minimize maintenance on the vacuum jacketed piping. However, this effort looked at ways to use a passive system that didn't require a vacuum, but may cryopump to create its own vacuum. Various forms of aerogel, multilayer insulations, and combinations thereof were tested to determine the best method of insulating the field joint while minimizing maintenance and thermal losses.

Johnson, Wesley L.; Fesmire, James E.; Meneghelli, Barry E.

2011-01-01

422

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2013 CFR

...metatarsal and tarsal joints of the lower extremities, the cervical vertebrae, the dorsal vertebrae, and the lumbar vertebrae...be a group of minor joints, ratable on disturbance of lumbar spine...

2013-07-01

423

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2012 CFR

...metatarsal and tarsal joints of the lower extremities, the cervical vertebrae, the dorsal vertebrae, and the lumbar vertebrae...be a group of minor joints, ratable on disturbance of lumbar spine...

2012-07-01

424

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2014 CFR

...metatarsal and tarsal joints of the lower extremities, the cervical vertebrae, the dorsal vertebrae, and the lumbar vertebrae...be a group of minor joints, ratable on disturbance of lumbar spine...

2014-07-01

425

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2011 CFR

...metatarsal and tarsal joints of the lower extremities, the cervical vertebrae, the dorsal vertebrae, and the lumbar vertebrae...be a group of minor joints, ratable on disturbance of lumbar spine...

2011-07-01

426

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2010 CFR

...metatarsal and tarsal joints of the lower extremities, the cervical vertebrae, the dorsal vertebrae, and the lumbar vertebrae...be a group of minor joints, ratable on disturbance of lumbar spine...

2010-07-01

427

JOINT PROGRAM IN TRANSPORTATION UNIVERSITY OF TORONTO  

E-print Network

JOINT PROGRAM IN TRANSPORTATION UNIVERSITY OF TORONTO 2001 TRANSPORTATION TOMORROW SURVEY of Transportation, Ontario Additions in 1996 Regional Municipalities of Niagara, Waterloo Counties of Peterborough not to participate) #12;JOINT PROGRAM IN TRANSPORTATION UNIVERSITY OF TORONTO 2001 TRANSPORTATION TOMORROW SURVEY

Toronto, University of

428

Center Establishment, & Joint and Interdisciplinary Appointments  

E-print Network

and interdisciplinary appointments: A. Center Establishment and/or Search and Recruitment 1. Total funding, bothCenter Establishment, & Joint and Interdisciplinary Appointments: Best Practices and Required Agreements Given the increasing number of interdisciplinary centers, and corresponding joint and

Farritor, Shane

429

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. ...compliance with all the manufacturer requirements in this part with respect to the jointly owned carline....

2013-10-01

430

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2012 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. ...compliance with all the manufacturer requirements in this part with respect to the jointly owned carline....

2012-10-01

431

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2011 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. ...compliance with all the manufacturer requirements in this part with respect to the jointly owned carline....

2011-10-01

432

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2010 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. ...compliance with all the manufacturer requirements in this part with respect to the jointly owned carline....

2010-10-01

433

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2014 CFR

...ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. ...compliance with all the manufacturer requirements in this part with respect to the jointly owned carline....

2014-10-01

434

Cellulose binding domain proteins  

DOEpatents

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.

Shoseyov, Oded (Karmey Yosef, IL); Shpiegl, Itai (Rehovot, IL); Goldstein, Marc (Davis, CA); Doi, Roy (Davis, CA)

1998-01-01

435

Time-domain imaging  

NASA Technical Reports Server (NTRS)

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.

Tolliver, C. L.

1989-01-01

436

Cellulose binding domain proteins  

DOEpatents

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.

Shoseyov, O.; Shpiegl, I.; Goldstein, M.; Doi, R.

1998-11-17

437

Matching pursuits with time-frequency dictionaries  

Microsoft Academic Search

The authors introduce an algorithm, called matching pursuit, that decomposes any signal into a linear expansion of waveforms that are selected from a redundant dictionary of functions. These waveforms are chosen in order to best match the signal structures. Matching pursuits are general procedures to compute adaptive signal representations. With a dictionary of Gabor functions a matching pursuit defines an

Stephane G. Mallat; Zhifeng Zhang

1993-01-01

438

ECG Feature Extraction using Time Frequency Analysis  

NASA Astrophysics Data System (ADS)

The proposed algorithm is a novel method for the feature extraction of ECG beats based on Wavelet Transforms. A combination of two well-accepted methods, Pan Tompkins algorithm and Wavelet decomposition, this system is implemented with the help of MATLAB. The focus of this work is to implement the algorithm, which can extract the features of ECG beats with high accuracy. The performance of this system is evaluated in a pilot study using the MIT-BIH Arrhythmia database.

Nair, Mahesh A.

439

The frictional properties of joints in rock  

Microsoft Academic Search

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

J. C. Jaeger

1959-01-01

440

7 CFR 1956.110 - Joint debtors.  

Code of Federal Regulations, 2011 CFR

...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...

2011-01-01

441

Joint Seminar -Risk Management Institute and  

E-print Network

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;

Chaudhuri, Sanjay

442

7 CFR 1956.110 - Joint debtors.  

Code of Federal Regulations, 2010 CFR

... 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...

2010-01-01

443

29 CFR 570.115 - Joint applicability.  

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

444

17 CFR 300.105 - Joint accounts.  

Code of Federal Regulations, 2012 CFR

...Exchanges 3 2012-04-01 2012-04-01 false Joint accounts. 300.105 Section 300.105 Commodity...âseparateâ Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying...

2012-04-01

445

29 CFR 570.115 - Joint applicability.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

446

49 CFR 192.233 - Miter joints.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 false Miter joints. 192.233 Section 192.233 Transportation...Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...

2010-10-01

447

Joint Invariant Signatures Peter J. Olver  

E-print Network

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

Olver, Peter

448

Joint Structures Determined by Clustering Microearthquakes  

E-print Network

Joint Structures Determined by Clustering Microearthquakes Using Waveform Amplitude Ratios Adam Sciences and Geomechanics Abstracts Roff et al., Joint Structures (Running header) #12;2 Abstract A new of microearthquakes induced by the pressurization of a 3.5-km deep, jointed region of granitic rock. The relative

449

29 CFR 570.115 - Joint applicability.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

450

21 CFR 26.73 - Joint Committee.  

Code of Federal Regulations, 2011 CFR

...Drugs 1 2011-04-01 2011-04-01 false Joint Committee. 26.73 Section 26.73 Food and...COMMUNITY âFrameworkâ Provisions § 26.73 Joint Committee. (a) A Joint Committee consisting of representatives of...

2011-04-01

451

17 CFR 300.105 - Joint accounts.  

Code of Federal Regulations, 2013 CFR

...Exchanges 3 2013-04-01 2013-04-01 false Joint accounts. 300.105 Section 300.105 Commodity...âseparateâ Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying...

2013-04-01

452

7 CFR 1956.110 - Joint debtors.  

Code of Federal Regulations, 2014 CFR

...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...

2014-01-01

453

7 CFR 1956.110 - Joint debtors.  

Code of Federal Regulations, 2013 CFR

...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...

2013-01-01

454

32 CFR 536.54 - Joint tortfeasors.  

Code of Federal Regulations, 2012 CFR

...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...

2012-07-01

455

29 CFR 570.115 - Joint applicability.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 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...

2010-07-01

456

Joint Kernel Learning for Supervised Image Segmentation  

E-print Network

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

Yoo, Chang D.

457

32 CFR 536.54 - Joint tortfeasors.  

Code of Federal Regulations, 2014 CFR

...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...

2014-07-01

458

17 CFR 300.105 - Joint accounts.  

Code of Federal Regulations, 2014 CFR

...Exchanges 4 2014-04-01 2014-04-01 false Joint accounts. 300.105 Section 300.105 Commodity...âseparateâ Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying...

2014-04-01

459

JOINT DEGREE PROGRAMS DEFINITION AND POLICY  

E-print Network

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

Omiecinski, Curtis

460

17 CFR 300.105 - Joint accounts.  

Code of Federal Regulations, 2010 CFR

...Exchanges 3 2010-04-01 2010-04-01 false Joint accounts. 300.105 Section 300.105 Commodity...âseparateâ Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying...

2010-04-01

461

49 CFR 192.233 - Miter joints.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Miter joints. 192.233 Section 192.233 Transportation...Welding of Steel in Pipelines § 192.233 Miter joints. (a) A miter joint on steel pipe to be operated at a pressure...

2011-10-01

462

7 CFR 1956.110 - Joint debtors.  

Code of Federal Regulations, 2012 CFR

...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...

2012-01-01

463

32 CFR 536.54 - Joint tortfeasors.  

Code of Federal Regulations, 2013 CFR

...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...

2013-07-01

464

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

465

21 CFR 26.73 - Joint Committee.  

Code of Federal Regulations, 2013 CFR

...Drugs 1 2013-04-01 2013-04-01 false Joint Committee. 26.73 Section 26.73 Food and...COMMUNITY âFrameworkâ Provisions § 26.73 Joint Committee. (a) A Joint Committee consisting of representatives of...

2013-04-01

466

17 CFR 300.105 - Joint accounts.  

Code of Federal Regulations, 2011 CFR

...Exchanges 3 2011-04-01 2011-04-01 false Joint accounts. 300.105 Section 300.105 Commodity...âseparateâ Customers of Sipc Members § 300.105 Joint accounts. (a) A joint account shall be deemed to be a “qualifying...

2011-04-01

467

21 CFR 26.73 - Joint Committee.  

Code of Federal Regulations, 2014 CFR

...Drugs 1 2014-04-01 2014-04-01 false Joint Committee. 26.73 Section 26.73 Food and...COMMUNITY âFrameworkâ Provisions § 26.73 Joint Committee. (a) A Joint Committee consisting of representatives of...

2014-04-01

468

29 CFR 570.115 - Joint applicability.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 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...

2011-07-01

469

Radiofrequency sacroiliac joint denervation for sacroiliac syndrome  

Microsoft Academic Search

Background and Objectives: Radiofrequency (RF) denervation of the sacroiliac (SI) joint has been advocated for the treatment of sacroiliac syndrome, yet no clinical studies or case series support its use. Methods: We report the results of a consecutive series of 50 SI joint RF denervations performed in 33 patients with sacroiliac syndrome. All patients underwent diagnostic SI joint injections with

F. Michael Ferrante; Lawrence F. King; Elizabeth A. Roche; Philip S. Kim; Margaret Aranda; Leslie R. DeLaney; Issam A. Mardini; Andrew J. Mannes

2001-01-01

470

Distributed Compressed Sensing of Jointly Sparse Signals  

E-print Network

a second new model for jointly sparse signals that allows for joint recovery of multi- ple signals from-of-the-art compression algorithms employ a decorrelating transform such as an exact or approximate KarhunenDistributed Compressed Sensing of Jointly Sparse Signals Marco F. Duarte, Shriram Sarvotham, Dror

471

Joints in deployable space truss structures  

NASA Technical Reports Server (NTRS)

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.

Rhodes, M.

1988-01-01

472

Effects of joints in truss structures  

NASA Technical Reports Server (NTRS)

The response of truss-type structures for future space applications, such as Large Deployable Reflector (LDR), will be directly affected by joint performance. Some of the objectives of research at BAC were to characterize structural joints, establish analytical approaches that incorporate joint characteristics, and experimentally establish the validity of the analytical approaches. The test approach to characterize joints for both erectable and deployable-type structures was based upon a Force State Mapping Technique. The approach pictorially shows how the nonlinear joint results can be used for equivalent linear analysis. Testing of the Space Station joints developed at LaRC (a hinged joint at 2 Hz and a clevis joint at 2 Hz) successfully revealed the nonlinear characteristics of the joints. The Space Station joints were effectively linear when loaded to plus or minus 500 pounds with a corresponding displacement of about plus or minus 0.0015 inch. It was indicated that good linear joints exist which are compatible with errected structures, but that difficulty may be encountered if nonlinear-type joints are incorporated in the structure.

Ikegami, R.

1988-01-01

473

Navigating Joint Projects in Telephone Conversations  

ERIC Educational Resources Information Center

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,…

Bangerter, Adrian; Clark, Herbert H.; Katz, Anna R.

2004-01-01

474

Irish National Joint Registry: a concept  

Microsoft Academic Search

Despite the well-documented benefits, some countries have yet to agree on the establishment of a national joint register. A questionnaire study was under- taken to ascertain the opinions of the consultant orthopaedic surgeons and specialist registrars, regarding establishment of an Irish National Joint Register. The aim was to find out the possible reasons why a national joint register has not

K. O. Oduwole; M. B. Codd; F. Byrne; J. O’Byrne; P. J. Kenny

2008-01-01

475

49 CFR 234.233 - Rail joints.  

Code of Federal Regulations, 2013 CFR

... 4 2013-10-01 2013-10-01 false Rail joints. 234.233 Section 234.233 Transportation...Testing Maintenance Standards § 234.233 Rail joints. Each non-insulated rail joint located within the limits of a...

2013-10-01

476

49 CFR 234.233 - Rail joints.  

Code of Federal Regulations, 2010 CFR

... 4 2010-10-01 2010-10-01 false Rail joints. 234.233 Section 234.233 Transportation...Testing Maintenance Standards § 234.233 Rail joints. Each non-insulated rail joint located within the limits of a...

2010-10-01

477

49 CFR 234.233 - Rail joints.  

Code of Federal Regulations, 2011 CFR

... 4 2011-10-01 2011-10-01 false Rail joints. 234.233 Section 234.233 Transportation...Testing Maintenance Standards § 234.233 Rail joints. Each non-insulated rail joint located within the limits of a...

2011-10-01

478

Future joint warfare analysis model designs  

Microsoft Academic Search

The Joint Warfare System (JWARS) is a state-of-the-art simulation of joint warfare for analysis, to be developed as one component of the Joint Analytic Model Improvement Program recently approved by the Deputy Secretary of Defense. This paper describes the rationale, objectives, management, approach and status of JWARS.

William G. Lese Jr.; Jim Metzger

1995-01-01

479

Future joint warfare analysis model designs  

Microsoft Academic Search

The Joint Warfare System (JWARS) is a state-of-the-art simulation of joint warfare for analysis, to be developed as one component of the Joint Analytic Model Improvement Program recently approved by the Deputy Secretary of Defense. This paper describes the rationale, objectives, management, approach and status of JWARS

J. Metzger

1995-01-01

480

26 CFR 1.6015-1 - Relief from joint and several liability on a joint return.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 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....

2012-04-01

481

26 CFR 1.6015-1 - Relief from joint and several liability on a joint return.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 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....

2014-04-01

482

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 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....

2013-04-01

483

Joint interaction with embedded concretions: joint loading congurations inferred from propagation paths  

E-print Network

Joint interaction with embedded concretions: joint loading con®gurations inferred from propagation The interaction between propagating joints and embedded concretions in a Devonian black shale near Seneca Lake, NY, permits identi®cation of the loading con®gurations responsible for two joint sets of dierent ages striking

Engelder, Terry

484

26 CFR 1.6015-1 - Relief from joint and several liability on a joint return.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 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....

2011-04-01

485

Proximal Tibiofibular Joint Ganglion CystsExcision, Recurrence, and Joint Arthrodesis  

Microsoft Academic Search

Objective: Proximal tibiofibular joint proximal tibiofibular joint cysts are rare entities that can cause disability. Excision remains the traditional surgical treatment. Cyst recurrence has been a problem. This study reviews one of the largest series of patients with proximal tibiofibular joint cysts and evaluates the role of a new surgical option, proximal tibiofibular joint fusion.Methods: Thirteen patients were admitted to

Shana Miskovsky; Christopher Kaeding; Lawrence Weis

2004-01-01

486

Joint interaction with embedded concretions: joint loading configurations inferred from propagation paths  

Microsoft Academic Search

The interaction between propagating joints and embedded concretions in a Devonian black shale near Seneca Lake, NY, permits identification of the loading configurations responsible for two joint sets of different ages striking at nearly the same orientation. The earlier set consists of systematic joints cut by later Alleghanian joints of the Appalachian Plateau. The later set consists of non-systematic curving

David T. McConaughy; Terry Engelder

1999-01-01

487

Seismic response of rock joints and jointed rock mass  

SciTech Connect

Long-term stability of emplacement drifts and potential near-field fluid flow resulting from coupled effects are among the concerns for safe disposal of high-level nuclear waste (HLW). A number of factors can induce drift instability or change the near-field flow patterns. Repetitive seismic loads from earthquakes and thermal loads generated by the decay of emplaced waste are two significant factors. One of two key technical uncertainties (KTU) that can potentially pose a high risk of noncompliance with the performance objectives of 10 CFR Part 60 is the prediction of thermal-mechanical (including repetitive seismic load) effects on stability of emplacement drifts and the engineered barrier system. The second KTU of concern is the prediction of thermal-mechanical-hydrological (including repetitive seismic load) effects on the host rock surrounding the engineered barrier system. The Rock Mechanics research project being conducted at the Center for Nuclear Waste Regulatory Analyses (CNWRA) is intended to address certain specific technical issues associated with these two KTUs. This research project has two major components: (i) seismic response of rock joints and a jointed rock mass and (ii) coupled thermal-mechanical-hydrological (TMH) response of a jointed rock mass surrounding the engineered barrier system (EBS). This final report summarizes the research activities concerned with the repetitive seismic load aspect of both these KTUs.

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

1996-06-01

488

44 CFR 150.5 - Joint Public Safety Awards Board.  

Code of Federal Regulations, 2011 CFR

... 2011-10-01 2011-10-01 false Joint Public Safety Awards Board. 150.5 Section...AWARDS TO PUBLIC SAFETY OFFICERS § 150.5 Joint Public Safety Awards Board. (a) A Joint Public Safety Awards Board (Joint...

2011-10-01

489

44 CFR 150.5 - Joint Public Safety Awards Board.  

Code of Federal Regulations, 2013 CFR

... 2013-10-01 2013-10-01 false Joint Public Safety Awards Board. 150.5 Section...AWARDS TO PUBLIC SAFETY OFFICERS § 150.5 Joint Public Safety Awards Board. (a) A Joint Public Safety Awards Board (Joint...

2013-10-01

490

JOINT ATTENTION IN HUMANS AND ANIMALS Malinda Carpenter  

E-print Network

JOINT ATTENTION IN HUMANS AND ANIMALS Malinda Carpenter Max Planck Institute for Evolutionary of learning. Springer. Synonyms Coordinated Joint Engagement; Declarative Pointing; Declarative Showing; Triadic Looking; Referential Looking; Joint Visual Attention Definition Joint attention is typically

Carpenter, M.alinda

491

RATE-DISTORTION OPTIMAL DEPTH MAPS IN THE WAVELET DOMAIN FOR FREE-VIEWPOINT RENDERING  

E-print Network

RATE-DISTORTION OPTIMAL DEPTH MAPS IN THE WAVELET DOMAIN FOR FREE-VIEWPOINT RENDERING Matthieu of estimating and encoding depth maps from multiple views in the context of 3D-TV with free-viewpoint rendering for the joint es- timation and coding of the depth map using dynamic programming along the tree of wavelet

Do, Minh N.

492

Ultrasonic Probing Of Complexly Shaped Joints  

NASA Technical Reports Server (NTRS)

Technique developed involves use of ultrasonics to inspect first bond surfaces of solid-rocket-motor joints. By fitting pieces of insulating materials to mate exactly with complicated shapes of affected parts of insulation, complicated shapes redefined into simpler ones probed more easily. When technique used to insonify from insulation side, one readily detects difference between disbond and good bond. Same technique applied to field tang joints, field clevis joints, and aft-dome-to-fixed-nozzle-housing attachment points. Although developed for inspecting joints in solid rocket motors, also applicable to nondestructive evaluation of other complicated joints.

Madaras, Eric I.

1993-01-01

493

Analysis of NSTX TF Joint Voltage Measurements  

SciTech Connect

This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''.

Woolley R

2005-10-07

494

Sonography of the knee joint?  

PubMed Central

The aim of this article is to review the sonographic appearances of common disorders involving the knee joint. Ultrasound is a sensitive method for diagnosis of tendon injuries. Injured ligaments appear swollen with mixed echogenicity. Meniscal injuries and muscle tears can be easily diagnosed. Ultrasound shows synovial thickening and effusion in inflammatory arthropathy and erosions of the articular surface in degenerative arthritis. It can be used effectively in the detection of rheumatoid arthritic activity and for grading degenerative arthritis lesions. Cystic lesions, as well as benign and malignant soft-tissue masses, are clearly delineated. Ultrasound is a safe noninvasive imaging modality that can be used for diagnosis of different disorders involving the knee joint. PMID:23397073

Razek, A.A.K.A.; Fouda, N.S.; Elmetwaley, N.; Elbogdady, E.

2009-01-01

495

Ultrasonic Welding of Hybrid Joints  

NASA Astrophysics Data System (ADS)

A central research field of the Institute of Materials Science and Engineering at the University of Kaiserslautern (WKK), Germany, is the realization of innovative hybrid joints by ultrasonic metal welding. This article gives an overview of suitable ultrasonic welding systems as well as of essential machine and material parameters, which influence the quality of the welds. Besides the ultrasonic welding of dissimilar metals such as Al to Cu or Al to steels, the welds between newly developed materials like aluminum foam sandwiches or flat flexible cables also can be realized. Moreover, the joining of glass and ceramic to sheet metals is a point of interest at the WKK. By using the ultrasonic metal welding process, it is possible to realize metal/glass welds with tensile shear strengths of 50 MPa. For metal/ceramic joints, the shear strengths values up to 150 MPa were measured. Finally, selected results about the occurring bonding mechanisms will be discussed.

Wagner, Guntram; Balle, Frank; Eifler, Dietmar

2012-03-01

496

Natural Language of Application Domains versus Domain Specific Programming Languages  

E-print Network

as high-school algebra and natural language processing. To prevent the reader from being trappedNatural Language of Application Domains versus Domain Specific Programming Languages Cuong Bui problem-solving algorithms and express them in the natural language of the domain while IT experts develop

Rus, Teodor

497

Spring joint with overstrain sensor  

NASA Technical Reports Server (NTRS)

A flexible joint may include a conductive compression spring and a pair of non-conductive spring cages disposed at opposite ends of the compression spring to support the compression spring. A conductive member disposed inside the compression spring may extend between the pair of spring cages. One end of the conductive member may be fixed for movement with one of the spring cages and another end of the conductive member may be fixed for movement with the other of the spring cages.

Phelps, Peter M. (Inventor); Gaither, Bryan W. (Inventor)

2011-01-01

498

Metal-ceramic joint assembly  

DOEpatents

A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

Li, Jian (New Milford, CT)

2002-01-01

499

Fellows Celebrated at Joint Assembly  

NASA Astrophysics Data System (ADS)

The 2008 AGU Fellows were presented at the recent Joint Assembly in Fort Lauderdale, Fla. A formal ceremony was held on 29 May 2008, during which President Tim Killeen introduced each Fellow and read a brief statement of the achievements for which each had been selected. The presentations were followed by a reception for meeting attendees and a banquet at which family members and close colleagues further feted the honorees.

2008-07-01