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1

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

PubMed

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

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

2008-03-01

2

Diagnostics and Prognostics of Electric Cables in Nuclear Power Plants via Joint Time-Frequency Domain Reflectometry  

Microsoft Academic Search

Defective cables in the electric power systems of nuclear power plants can cause a component to fail, resulting in potential safety concerns. Due to this problem, a non-destructive, non-intrusive condition assessment technique is highly desirable. Joint time-frequency domain reflectometry (JTFDR) is proposed and verified to be effective for cross-linked polyethylene (XLPE) cable, which serves critical instrumentation and control operations in

Jingjiang Wang; Philip Crapse; Yong-June Shin; R. Dougal

2008-01-01

3

Joint Time-Frequency Spectrum Sensing for Cognitive Radio  

E-print Network

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

Paris-Sud XI, Université de

4

Joint time-frequency analysis of electromagnetic backscattered data  

NASA Astrophysics Data System (ADS)

The application of joint time-frequency techniques for the analysis of electromagnetic backscattered data is reviewed. In the joint time-frequency features space, discrete time events such as scattering centers, discrete frequency events such as target resonances, and dispersive mechanisms due to surface waves and guided modes can be simultaneously displayed. We discuss the various joints time-frequency representations including the short-time Fourier transform, wavelet transform, Wigner-Ville distribution, windowed super-resolution algorithms and the adaptive spectrogram. Emphasis is placed on how these algorithms can be used to represent with good resolution the scattering phenomenology in electromagnetic data. We highlight and application of joint time-frequency processing for radar image enhancement and feature extraction. It is shown that by applying joint time-frequency processing to the conventional inverse synthetic aperture radar imagery, it is possible to remove non-point scattering features in the image, leading to a cleaned image containing only physically meaningful point scatterers. The extracted frequency-dependent mechanisms can be displaced in an alternative feature space to facilitate target identification.

Ling, Hao

1998-03-01

5

Detection and characterization of cultural noise sources in magnetotelluric data: individual and joint analysis of the polarization attributes of the electric and magnetic field time-series in the time-frequency domain  

NASA Astrophysics Data System (ADS)

Magnetotelluric (MT) method is a passive electromagnetic technique, which is currently used to characterize sites for the geological storage of CO2. These later ones are usually located nearby industrialized, urban or farming areas, where man-made electromagnetic (EM) signals contaminate the MT data. The identification and characterization of the artificial EM sources which generate the so-called "cultural noise" is an important challenge to obtain the most reliable results with the MT method. The polarization attributes of an EM signal (tilt angle, ellipticity and phase difference between its orthogonal components) are related to the character of its source. In a previous work (Escalas et al. 2011), we proposed a method to distinguish natural signal from cultural noise in the raw MT data. It is based on the polarization analysis of the MT time-series in the time-frequency domain, using a wavelet scheme. We developed an algorithm to implement the method, and was tested with both synthetic and field data. In 2010, we carried out a controlled-source electromagnetic (CSEM) experiment in the Hontomín site (the Research Laboratory on Geological Storage of CO2 in Spain). MT time-series were contaminated at different frequencies with the signal emitted by a controlled artificial EM source: two electric dipoles (1 km long, arranged in North-South and East-West directions). The analysis with our algorithm of the electric field time-series acquired in this experiment was successful: the polarization attributes of both the natural and artificial signal were obtained in the time-frequency domain, highlighting their differences. The processing of the magnetic field time-series acquired in the Hontomín experiment has been done in the present work. This new analysis of the polarization attributes of the magnetic field data has provided additional information to detect the contribution of the artificial source in the measured data. Moreover, the joint analysis of the polarization attributes of the electric and magnetic field has been crucial to fully characterize the properties and the location of the noise source. Escalas, M., Queralt, P., Ledo, J., Marcuello, A., 2011. Identification of cultural noise sources in magnetotelluric data: estimating polarization attributes in the time-frequency domain using wavelet analysis. Geophysical Research Abstracts Vol. 13, EGU2011-6085. EGU General Assembly 2011.

Escalas, M.; Queralt, P.; Ledo, J.; Marcuello, A.

2012-04-01

6

Characterization of Cardio signals by time-frequency domain analysis  

E-print Network

Long term behavior of nonlinear deterministic continuous time signals can be studied in terms of their reconstructed attractors. Reconstructed attractors of a continuous signal are meant to be topologically equivalent representations of the dynamics of the unknown dynamical system which generates the signal. Sometimes, geometry of the attractor or its complexity may give important information on the system of interest. However, if the trajectories of the attractor behave as if they are not coming from continuous system or there exists many spike like structures on the path of the system trajectories, then there is no way to characterize the shape of the attractor. In this article, the traditional attractor reconstruction method is first used for two types of ECG signals: Normal healthy persons (NHP) and Congestive Heart failure patients (CHFP). As common in such a framework, the reconstructed attractors are not at all well formed and hence it is not possible to adequately characterize their geometrical features. Thus, we incorporate frequency domain information to the given time signals. This is done by transforming the signals to a time frequency domain by means of suitable Wavelet transforms (WT). The transformed signal concerns two non homogeneous variables and is still quite difficult to use to reconstruct some dynamics out of it. By applying a suitable mapping, this signal is further converted into integer domain and a new type of 3D plot, called integer lag plot, which characterizes and distinguishes the ECG signals of NHP and CHFP, is finally obtained.

Sayan Mukherjee; Sanjay Kumar Palit; Santo Banerjee; MRK Ariffin; Lamberto Rondoni; Dilip Kumar Bhattacharya

2014-09-04

7

Estimation of modal parameters using bilinear joint time frequency distributions  

NASA Astrophysics Data System (ADS)

In this paper, a new method is proposed for modal parameter estimation using time-frequency representations. Smoothed Pseudo Wigner-Ville distribution which is a member of the Cohen's class distributions is used to decouple vibration modes completely in order to study each mode separately. This distribution reduces cross-terms which are troublesome in Wigner-Ville distribution and retains the resolution as well. The method was applied to highly damped systems, and results were superior to those obtained via other conventional methods.

Roshan-Ghias, A.; Shamsollahi, M. B.; Mobed, M.; Behzad, M.

2007-07-01

8

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

9

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

PubMed

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. PMID:25462948

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

2014-10-17

10

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

11

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

12

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

13

Maximum likelihood estimator of operational modal analysis for linear time-varying structures in time-frequency domain  

NASA Astrophysics Data System (ADS)

This paper investigates the problem of modal parameter estimation of time-varying structures under unknown excitation. A time-frequency-domain maximum likelihood estimator of modal parameters for linear time-varying structures is presented by adapting the frequency-domain maximum likelihood estimator to the time-frequency domain. The proposed estimator is parametric, that is, the linear time-varying structures are represented by a time-dependent common-denominator model. To adapt the existing frequency-domain estimator for time-invariant structures to the time-frequency methods for time-varying cases, an orthogonal polynomial and z-domain mapping hybrid basis function is presented, which has the advantageous numerical condition and with which it is convenient to calculate the modal parameters. A series of numerical examples have evaluated and illustrated the performance of the proposed maximum likelihood estimator, and a group of laboratory experiments has further validated the proposed estimator.

Zhou, Si-Da; Heylen, Ward; Sas, Paul; Liu, Li

2014-05-01

14

Design and Modeling of Novel Multiband/Wideband Antennas for RFID Tags and Readers Using Time-/Frequency-Domain Simulators  

E-print Network

. INTRODUCTION The recent advances in cost-effective low-power electronics and packaging have enabled the RFID such as security, logistics, automotive and pharmaceutical. Index Terms - RFID, Time/Frequency-domain simulators. I data are contact-free transferred to a local querying system (reader or interrogator) from a remote

Tentzeris, Manos

15

EMG burst presence probability: A joint time-frequency representation of muscle activity and its application to onset detection.  

PubMed

The purpose of this study was to quantify muscle activity in the time-frequency domain, therefore providing an alternative tool to measure muscle activity. This paper presents a novel method to measure muscle activity by utilizing EMG burst presence probability (EBPP) in the time-frequency domain. The EMG signal is grouped into several Mel-scale subbands, and the logarithmic power sequence is extracted from each subband. Each log-power sequence can be regarded as a dynamic process that transits between the states of EMG burst and non-burst. The hidden Markov model (HMM) was employed to elaborate this dynamic process since HMM is intrinsically advantageous in modeling the temporal correlation of EMG burst/non-burst presence. The EBPP was eventually yielded by HMM based on the criterion of maximum likelihood. Our approach achieved comparable performance with the Bonato method. PMID:25748222

Liu, Jie; Ying, Dongwen; Rymer, William Zev

2015-04-13

16

Measurement of load impedance in power cables using wavelet-transform-based time-frequency domain reflectometry  

NASA Astrophysics Data System (ADS)

In this paper, wavelet-transform-based time-frequency domain reflectometry (WTFDR) is proposed for load impedance measurement. In order to measure the load impedance, the energy of the measured signal in the time-frequency domain, the phase difference between the reference signal and the reflected signal, the characteristic impedance, and the attenuation factor of the measured cable must all be known. Since the complex wavelet transform is composed of real and imaginary parts, the phase difference is easily obtained using the ratio of the real coefficient to the imaginary coefficient. In addition, the wavelet energy denotes the sum of the square of the modulus of the wavelet transform and describes the energy of the measured signal in the time and frequency domains. To accurately determine the characteristic impedance and attenuation factors, the power cable should be estimated as a coaxial cable. Using WTFDR with the complex mother wavelet and the estimated power cable, the load impedance can be obtained simply and accurately. Finally, real experiments for the evaluation of various load impedances are carried out to confirm the effectiveness and accuracy of the proposed method compared to the conventional time-frequency domain reflectometry.

Lee, Sin Ho; Park, Jin Bae; Choi, Yoon Ho

2013-09-01

17

Adaptive extraction of emotion-related EEG segments using multidimensional directed information in time-frequency domain.  

PubMed

Emotion discrimination from electroencephalogram (EEG) has gained attention the last decade as a user-friendly and effective approach to EEG-based emotion recognition (EEG-ER) systems. Nevertheless, challenging issues regarding the emotion elicitation procedure, especially its effectiveness, raise. In this work, a novel method, which not only evaluates the degree of emotion elicitation but localizes the emotion information in the time-frequency domain, as well, is proposed. The latter, incorporates multidimensional directed information at the time-frequency EEG representation, extracted using empirical mode decomposition, and introduces an asymmetry index for adaptive emotion-related EEG segment selection. Experimental results derived from 16 subjects visually stimulated with pictures from the valence/arousal space drawn from the International Affective Picture System database, justify the effectiveness of the proposed approach and its potential contribution to the enhancement of EEG-ER systems. PMID:21096088

Petrantonakis, Panagiotis C; Hadjileontiadis, Leontios J

2010-01-01

18

Adaptive time-frequency analysis of knee joint vibroarthrographic signals for noninvasive screening of articular cartilage pathology.  

PubMed

Vibroarthrographic (VAG) signals emitted by human knee joints are nonstationary and multicomponent in nature; time-frequency distributions (TFD's) provide powerful means to analyze such signals. The objective of this paper is to construct adaptive TFD's of VAG signals suitable for feature extraction. An adaptive TFD was constructed by minimum cross-entropy optimization of the TFD obtained by the matching pursuit decomposition algorithm. Parameters of VAG signals such as energy, energy spread, frequency, and frequency spread were extracted from their adaptive TFD's. The parameters carry information about the combined TF dynamics of the signals. The mean and standard deviation of the parameters were computed, and each VAG signal was represented by a set of just six features. Statistical pattern classification experiments based on logistic regression analysis of the parameters showed an overall normal/abnormal screening accuracy of 68.9% with 90 VAG signals (51 normals and 39 abnormals), and a higher accuracy of 77.5% with a database of 71 signals with 51 normals and 20 abnormals of a specific type of patellofemoral disorder. The proposed method of VAG signal analysis is independent of joint angle and clinical information, and shows good potential for noninvasive diagnosis and monitoring of patellofemoral disorders such as chondromalacia patella. PMID:10833852

Krishnan, S; Rangayyan, R M; Bell, G D; Frank, C B

2000-06-01

19

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

NASA Technical Reports Server (NTRS)

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

Palumbo, Dan

2008-01-01

20

Measuring multi-joint stiffness during single movements: numerical validation of a novel time-frequency approach.  

PubMed

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

21

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

22

Association between P3 Event-Related Potential Amplitude and Externalizing Disorders: A Time Domain and Time Frequency Investigation of 29-Year-Old Adults  

PubMed Central

This study determined whether time-domain P3 amplitude and time-frequency principal component (TF-PC) reductions are present in adulthood (age 29) when participants have largely passed through the age of heaviest substance misuse. Participants were assessed from age 17 through 29 for lifetime externalizing (EXT) disorders. EEG comparisons from three topographic regions were examined for P3 amplitude and TF-PCs at delta and theta frequency ranges. Significant P3 amplitude reductions were found in those with EXT for both regional and site-Pz analyses, with stronger effects observed the greater the EXT comorbidity. Reductions were also observed in all eight TF-PCs extracted, with a delta component yielding frontal effects not apparent in the time-domain. Overall, results suggest that these brain measures continue, at age 29, to provide effective indices of EXT that potentially tap a neural substrate related to behavioral disinhibition. PMID:23614581

Yoon, Henry H.; Malone, Stephen M.; Burwell, Scott J.; Bernat, Edward M.; Iacono, William G.

2013-01-01

23

Prediction of extreme responses of floating structures using a hybrid time\\/frequency domain coupled analysis approach  

Microsoft Academic Search

The dynamic analysis of a deepwater floating system has many complexities, which include the dynamic coupling between the platform and the moorings\\/risers, coupling between the first-order wave frequency (WF) and second-order low-frequency (LF) motions, hydrodynamic\\/geometric nonlinearities and non-Gaussian response statistics. These complexities can be automatically captured in a fully coupled time domain analysis, but at the expense of an enormous

Y. M. Low

2008-01-01

24

JOINT DOMAIN LOCALIZEDPROCESSINGUSING MEASURED SPATIAL STEERINGVECTORS*  

E-print Network

and possibly inhomogeneous interference in real time. Space-time adaptive processing (STAP) techniques promise in angle-Doppler space. As such, adaptive processing may be performed in a localized processing region in the space-time domain to the angle-Doppler domain. However, the JDL algorithm depends on the assumption

Adve, Raviraj

25

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

26

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

27

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

E-print Network

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

Paris-Sud XI, Université de

28

Spatial averaging of time-frequency distributions  

Microsoft Academic Search

This paper presents a novel approach based on time-frequency distributions (TFDs) for separating signals received by a multiple antenna array. This approach provides a significant improvement in performance over the previously introduced spatial time-frequency distributions, specifically for signals with close time-frequency signatures. In this approach, spatial averaging of the time-frequency distributions of the sensor data is performed to eliminate the

Yimin Zhang; Moeness G. Amin

1999-01-01

29

Time-Frequency localization of Multiband signals  

E-print Network

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

Lakey, Joseph D.

30

Time-Frequency localization of Multiband signals  

E-print Network

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

Lakey, Joseph D.

31

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

32

Time frequency analysis and parametric approximation of room impulse responses  

Microsoft Academic Search

Rooms are modeled as linear time invariant systems, where the acoustic transmission characteristics between a specific source receiver pair are described by the room impulse response (RIR). A recursive realization of the short time Fourier transform is employed to decompose the RIR in the time frequency domain, where the different subband signals are approximated by parametric models. The pole-zero models,

J. C. Sarris; G. E. Cambourakis

2003-01-01

33

Applications of time-frequency analysis for aging aircraft component diagnostics and prognostics  

NASA Astrophysics Data System (ADS)

The classical time-frequency distributions represent time- and frequency-localized energy. However, it is not an easy task to analyze multiple signals that have been simultaneously collected. In this paper, a new concept of non-parametric detection and classification of the signals is proposed using the mutual information measures in the time-frequency domain. The time-frequency-based self and mutual information is defined in terms of cross time-frequency distribution. Based on the time-frequency mutual information theory, this paper presents applications of the proposed technique to real-world vibration data. The baseline and misaligned experimental settings are quantitatively distinguished by the proposed technique.

Cho, Kwangik; Coats, David; Abrams, John; Goodman, Nicholas; Shin, Yong-June; Bayoumi, Abdel E.

2008-08-01

34

Characterization of coding domains by optimally implementing optimal trade-off (OT) filters in the joint transform correlator  

Microsoft Academic Search

We propose to characterize various coding domains for the joint transform correlator. To achieve that, optimal trade- off filters have ben computed and then optimally constrained to given coding domains with an algorithm we have developed. Then, these coding domains have been evaluated in relation to the trade-offs they achieve.

Laurent Bigue; Michel Fraces; Pierre Ambs

1996-01-01

35

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.

36

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

37

Joints  

NSDL National Science Digital Library

Hinge joints move only in one direction, ball-and-socket joints are free to rotate in all directions, and gliding joints are able to move forward, backward, and side to side, but do not rotate freely.

Olivia Worland (Purdue University; Biological Sciences)

2008-06-06

38

Computer-aided classification of rheumatoid arthritis in finger joints using frequency domain optical tomography  

NASA Astrophysics Data System (ADS)

Novel methods that can help in the diagnosis and monitoring of joint disease are essential for efficient use of novel arthritis therapies that are currently emerging. Building on previous studies that involved continuous wave imaging systems we present here first clinical data obtained with a new frequency-domain imaging system. Three-dimensional tomographic data sets of absorption and scattering coefficients were generated for 107 fingers. The data were analyzed using ANOVA, MANOVA, Discriminant Analysis DA, and a machine-learning algorithm that is based on self-organizing mapping (SOM) for clustering data in 2-dimensional parameter spaces. Overall we found that the SOM algorithm outperforms the more traditional analysis methods in terms of correctly classifying finger joints. Using SOM, healthy and affected joints can now be separated with a sensitivity of 0.97 and specificity of 0.91. Furthermore, preliminary results suggest that if a combination of multiple image properties is used, statistical significant differences can be found between RA-affected finger joints that show different clinical features (e.g. effusion, synovitis or erosion).

Klose, C. D.; Kim, H. K.; Netz, U.; Blaschke, S.; Zwaka, P. A.; Mueller, G. A.; Beuthan, J.; Hielscher, A. H.

2009-02-01

39

Time-frequency transforms: a new approach to first heart sound frequency dynamics  

Microsoft Academic Search

The binomial joint time-frequency transform is used to test the hypothesis that first heart sound frequency rises during the isovolumic contraction period. Cardiac vibrations were recorded from eight open-chest dogs using an ultralight accelerometer cemented directly to the epicardium of the anterior left ventricle. Three characteristic time-frequency spectral patterns were evident in the animals investigated: (1) a frequency component that

John C. Wood; Andrew J. Buda; Daniel T. Barry

1992-01-01

40

Postural tachycardia syndrome: time frequency mapping  

Microsoft Academic Search

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

Vera Novak; Peter Novak; Tonette L Opfer-Gehrking; Phillip A Low

1996-01-01

41

Time-frequency MUSIC: an array signal processing method based on time-frequency signal representations  

NASA Astrophysics Data System (ADS)

The concept of spatial time-frequency distribution (STFD) has been recently introduced and applied to solve the problem of blind source separation for nonstationary signals. In this paper, we propose to apply this same concept to solve the problem of the direction of arrival (DOA) estimation. A new method for the estimation of the signal subspace and noise subspace based on time-frequency signal representations is introduced. The proposed approach consists of the join block- diagonalization (JBD) of a combined set of spatial time frequency distribution matrices. Once the signal and the noise subspaces are estimated, any subspace based approach can be applied for DOA estimation. Herein, we propose to use the MUSIC algorithm. Performance comparison of the proposed approach with the classical MUSIC method is provided. The influence of the time-frequency kernels on the performance of the newly proposed Time-Frequency MUSIC (TF-MUSIC) is evaluated numerically.

Amin, Moeness G.; Belouchrani, Adel

1998-10-01

42

Time-Frequency Analysis as Probabilistic Inference  

E-print Network

of the probabilistic model is the prior distribution on X, . This defines the values of X that are compatible with the time-frequency model. For instance, if each sequence represents an amplitude modulated narrowband carrier signal, then it might be reasonable... recovers a target signal with minimal squared error, rejecting stationary interference of known spectral density. In our case, the target signal is the th component , while the interference is the mixture of the other components and noise. Wiener...

Turner, Richard E.

2014-11-06

43

Reducing noise in the time-frequency representation using sparsity promoting kernel design  

NASA Astrophysics Data System (ADS)

Missing samples in the time domain introduce noise-like artifacts in the ambiguity domain due to their de facto zero values assumed by the bilinear transform. These artifacts clutter the dual domain of the time-frequency signal representation and obscures the time-frequency signature of single and multicomponent signals. In order to suppress the artifacts influence, we formulate a problem based on the sparsity aware kernel. The proposed kernel design is more robust to the artifacts caused by the missing samples.

Jokanovi?, Branka; Amin, Moeness G.; Zhang, Yimin D.

2014-05-01

44

A Method for Ventricular Late Potentials Detection Using Time-Frequency Representation and Wavelet Denoising  

PubMed Central

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

45

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

46

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.

47

Nonlinear optical security system based on a joint transform correlator in the Fresnel domain.  

PubMed

A new optical security system for image encryption based on a nonlinear joint transform correlator (JTC) in the Fresnel domain (FrD) is proposed. The proposal of the encryption process is a lensless optical system that produces a real encrypted image and is a simplified version of some previous JTC-based encryption systems. We use a random complex mask as the key in the nonlinear system for the purpose of increasing the security of the encrypted image. In order to retrieve the primary image in the decryption process, a nonlinear operation has to be introduced in the encrypted function. The optical decryption process is implemented through the Fresnel transform and the fractional Fourier transform. The security system proposed in this paper preserves the shift-invariance property of the JTC-based encryption system in the Fourier domain, with respect to the lateral displacement of the key random mask in the decryption process. This system shows an improved resistance to chosen-plaintext and known-plaintext attacks, as they have been proposed in the cryptanalysis of the JTC encrypting system. Numerical simulations show the validity of this new optical security system. PMID:24663426

Vilardy, Juan M; Millán, María S; Pérez-Cabré, Elisabet

2014-03-10

48

Moving-target imaging based on space-time-frequency signal processing for SAR system  

NASA Astrophysics Data System (ADS)

A method for moving-target imaging in dual-channel SAR system based on space-time-frequency signal processing is studied. In space-time domain, adaptive sliding-window processing method is applied to get high output signal to noise ratio by dual-channel clutter suppression. In time-frequency domain, modified discrete Chirp-Fourier transformation is applied to get Doppler modulation frequency parameters. Range migration is solved by Keystone transformation. Azimuth velocity accuracy is improved by phase compensation. Parameter decoupling is solved by channel phase deviation. A lot of simulation experiments verify the validity of the proposed method.

Huang, Yao; Huang, Shijun

2013-03-01

49

Physics based modeling for time-frequency damage classification  

NASA Astrophysics Data System (ADS)

We have recently proposed a method for classifying waveforms from healthy and damaged structures in a structural health monitoring framework. This method is based on the use of hidden Markov models with preselected feature vectors obtained from the time-frequency based matching pursuit decomposition. In order to investigate the performance of the classifier for different signal-to-noise ratios (SNR), we simulate the response of a lug joint sample with different crack lengths using finite element modeling (FEM). Unlike experimental noisy data, the modeled data is noise free. As a result, different levels of noise can be added to the modeled data in order to obtain the true performance of the classifier under additive white Gaussian noise. We use the finite element package ABAQUS to simulate a lug joint sample with different crack lengths and piezoelectric sensor signals. A mesoscale internal state variable damage model defines the progressive damage and is incorporated in the macroscale model. We furthermore use a hybrid method (boundary element-finite element method) to model wave reflection as well as mode conversion of the Lamb waves from the free edges and scattering of the waves from the internal defects. The hybrid method simplifies the modeling problem and provides better performance in the analysis of high stress gradient problems.

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

2008-03-01

50

Enhanced joint spectral and time domain optical coherence tomography for quantitative flow velocity measurement  

NASA Astrophysics Data System (ADS)

Recently, a new method called joint spectral and time domain optical coherence tomography (STdOCT) for flow velocity measurement in spectral domain OCT (SD OCT) was presented. This method analyzes the detected timeresolved interference fringe spectra by using a two-dimensional fast Fourier transformation (2D FFT) to determine directly the Doppler frequency shift instead of calculating the phase difference at each depth position of adjacent A-scans. There, it was found that STdOCT is more robust for measurements with low signal to noise ratio than the classic phase-resolved Doppler OCT (DOCT) making it attractive first for imaging fast flow velocities at which a strong Doppler angle dependent signal damping occurs due to interference fringe washout and second for investigating large blood vessels with a big diameter and a highly damped signal of blood with increasing depth due to strong scattering and absorption in the near-infrared wavelength range. In the present study, we would like to introduce an enhanced algorithm for STdOCT permitting a more precise flow velocity measurement in comparison to the conventional STdOCT. The new method determines the amplitude of the broadened Doppler frequency shift by calculating the center of gravity via the complex analytical signal as a result of the second FFT instead of detecting the maximum intensity signal. Furthermore, the comparison with phase-resolved DOCT was done experimentally by using a flow phantom consisting of a 1% Intralipid emulsion and a 320 ?m glass capillary. As a result, the enhanced STdOCT and DOCT processed data are completely equivalent.

Walther, Julia; Koch, Edmund

2011-06-01

51

Time-frequency Masking EECS 352: Machine Perception of  

E-print Network

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

Pardo, Bryan

52

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.

53

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

54

Joint Frequency-Domain Differential Detection and Equalization for 2Dimensional Spread\\/Chip-Interleaved DS-CDMA Uplink Transmissions  

Microsoft Academic Search

The multiple-access interference (MAI) limits the performance of the DS-CDMA uplink transmission. 2 dimensional (2D) spread\\/chip-interleaved DS-CDMA is an MAI-free system, where single-user coherent frequency- domain equalization (FDE) can be used instead of complicated multiuser detection (MUD). However, coherent FDE needs channel estimation. Pilot-assisted channel estimation is not reliable in a fast fading environment. In this paper, we apply joint

Le Liu; Fumiyuki Adachi

2006-01-01

55

Blind separation of speech mixtures via time-frequency masking  

Microsoft Academic Search

Binary time-frequency masks are powerful tools for the separation of sources from a single mixture. Perfect demixing via binary time-frequency masks is possible provided the time-frequency representations of the sources do not overlap: a condition we call W-disjoint orthogonality. We introduce here the concept of approximate W-disjoint orthogonality and present experimental results demonstrating the level of approximate W-disjoint orthogonality of

O. Yilmaz; Scott Rickard

2004-01-01

56

Measuring time-Frequency information content using the Rényi entropies  

Microsoft Academic Search

The generalized entropies of Rényi inspire new measures for estimating signal information and complexity in the time-frequency plane. When applied to a time-frequency representation (TFR) from Cohen's class or the affine class, the Rényi entropies conform closely to the notion of complexity that we use when visually inspecting time-frequency images. These measures possess several additional interesting and useful proper- ties,

Richard G. Baraniuk; Patrick Flandrin; Augustus J. E. M. Janssen; Olivier J. J. Michel

2001-01-01

57

Identification of structural-borne noise components by the use of time-frequency filtering  

NASA Technical Reports Server (NTRS)

In this paper it is shown that a time-frequency analysis of a structural impulse response may be used to identify the wave types carrying significant energy through a structure. The identification of various wave types is possible since each is characterized by its own dispersion relation, with the result that each wave type may be associated with characteristic features in the time-frequency domain representation of an impulse response. In the work described here, the Wigner Distribution has been used to obtain appropriate time-frequency representations of impulse responses. Practical aspects of the calculation of the Wigner Distribution are discussed briefly and examples of its application to the analysis of structural impulse responses are given. Additionally, filtering techniques are described that can be used both to detect the presence of and to quantify the energy carried by both nondispersive and dispersive waves.

Wahl, T. J.; Bolton, J. S.

1990-01-01

58

Time-frequency beamforming for nondestructive evaluations of plate using ultrasonic Lamb wave  

NASA Astrophysics Data System (ADS)

The objective of this study is to detect structural defect locations in a plate by exciting the plate with a specific ultrasonic Lamb wave and recording reflective wave signals using a piezoelectric transducer array. For the purpose of eliminating the effects of the direct excitation signals as well as the boundary-reflected wave signals, it is proposed to improve a conventional MUSIC beamforming procedure by processing the measured signals in the time-frequency domain. In addition, a normalized, damped, cylindrical 2-D steering vector is proposed to increase the spatial resolution of time-frequency MUSIC power results. A cross-shaped array is selected to further improve the spatial resolution and to avoid mirrored virtual image effects. Here, it is experimentally demonstrated that the proposed time-frequency MUSIC beamforming procedure can be used to identify structural defect locations on an aluminum plate by distinguishing the defect-induced waves from the excitation-generated and boundary-reflected waves.

Han, Je-Heon; Kim, Yong-Joe

2015-03-01

59

Nonlinear Time-Frequency Control Theory with Applications  

E-print Network

, the novel theory has its philosophical basis established in the simultaneous time-frequency control, on-line system identification, and feedforward adaptive control. It adopts multi-rate control, hence enabling control over nonstationary, nonlinear response...

Liu, Mengkun 1978-

2012-10-04

60

Transmission Line Fault Detection Using Time-Frequency Analysis  

Microsoft Academic Search

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

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

2005-01-01

61

Preamble-based frequency-domain joint CFO and STO estimation for OQAM-based filter bank multicarrier  

NASA Astrophysics Data System (ADS)

Filter bank multicarrier systems, similarly to orthogonal frequency division multiplexing (OFDM), are very sensitive to carrier frequency offset (CFO) and symbol timing offset (STO). In this paper, a low-complexity preamble-based joint CFO and STO technique is presented. It is based on a relatively long preamble in order to improve the CFO estimation performance as well as avoid interference coming from the data following this preamble. After CFO and STO correction, the preamble can be reused to estimate the channel. Unlike most current techniques, the CFO and STO estimation occurs in the frequency domain. This allows for a low-complexity estimation with respect to time-domain techniques and, as will be shown by simulations, provide even better performance in a reasonable range. The drawback however is that the estimation range is shorter. Specifically, for large STOs (and to a smaller extent large CFOs), the performance decreases below time-domain estimations. Two versions of the STO estimation technique will be presented, the second one being an approximation of the first one, making it less complex yet also less precise. The performance is assessed by means of computer simulations, testing for both large and small STOs, and compared with existing techniques.

Caekenberghe, Stijn Van; Bourdoux, André; der Perre, Liesbet Van; Louveaux, Jérôme

2014-12-01

62

Estimation of the power spectral density in nonstationary cardiovascular time series: assessing the role of the time-frequency representations (TFR).  

PubMed

Spectral analysis of cardiovascular series has been proposed as a noninvasive tool for investigating the autonomic control of the cardiovascular system. The analysis of such series during autonomic tests requires high resolution estimators that are capable to track the transients of the tests. A comparative evaluation has been made among classical (FFT based), autoregressive (both block and sequential mode) and time-frequency representation (TFR) based power spectral estimators. The evaluation has been performed on artificial data that have typical patterns of the nonstationary series. The results documented the superiority of the TFR approach when a sharp time resolution is required. Moreover, the test on a RR-like series has shown that the smoothing operation is effective for rejecting TFR cross-terms when a simple, two-three components series is concerned. Finally, the preliminary application of the selected methods to real RR interval time series obtained during some autonomic tests has shown that the TFR are capable to correctly represent the transient of the series in the joint time-frequency domain. PMID:8567005

Pola, S; Macerata, A; Emdin, M; Marchesi, C

1996-01-01

63

Joint synchronization and calibration of multi-channel transform-domain charge sampling receivers  

E-print Network

-channel wideband receiver that is based on Frequency-domain (FD) sampling, a special case of TD sampling. To achieve high dynamic ranges in these receivers, it is critical that the digital post processing block matches the analog RF front end accurately...

Kotte Prakasam, Pradeep

2010-07-14

64

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

65

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

66

[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

67

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

68

Time-Frequency Masking for Speech Separation and Its Potential for Hearing Aid Design  

PubMed Central

A new approach to the separation of speech from speech-in-noise mixtures is the use of time-frequency (T-F) masking. Originated in the field of computational auditory scene analysis, T-F masking performs separation in the time-frequency domain. This article introduces the T-F masking concept and reviews T-F masking algorithms that separate target speech from either monaural or binaural mixtures, as well as microphone-array recordings. The review emphasizes techniques that are promising for hearing aid design. This article also surveys recent studies that evaluate the perceptual effects of T-F masking techniques, particularly their effectiveness in improving human speech recognition in noise. An assessment is made of the potential benefits of T-F masking methods for the hearing impaired in light of the processing constraints of hearing aids. Finally, several issues pertinent to T-F masking are discussed. PMID:18974204

Wang, DeLiang

2008-01-01

69

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

70

A real-time weighted-eigenvector MUSIC method for time-frequency analysis of electrogastrogram slow wave  

Microsoft Academic Search

The surface electrogastrogram (EGG) records the electrical slow wave of the stomach noninvasively, whose frequency is a useful clinical indicator of the state of gastric motility. Estimators based on the periodogram method are widely adopted to obtain this parameter. But they are with a poor frequency domain resolution when the data window is short in time-frequency analysis, and have not

Shujia Qin; Lei Miao; Ning Xi; Yuechao Wang; Chunmin Yang

2010-01-01

71

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

72

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

73

Time-frequency analysis of the glottal opening  

Microsoft Academic Search

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

Wolfgang Wokurek

1997-01-01

74

Predicting sleep apnoea syndrome from heart period: a time-frequency wavelet analysis.  

PubMed

Heart rate fluctuations are a typical finding during obstructive sleep apnoea, characterised by bradycardia during the apnoeic phase and tachycardia at the restoration of ventilation. In this study, a time-frequency domain analysis of the nocturnal heart rate variability (HRV) was evaluated as the single diagnostic marker for obstructive sleep apnoea syndrome (OSAS). The predictive accuracy of time-frequency HRV variables (wavelet (Wv) decomposition parameters from level 2 (Wv2) to level 256 (Wv256)) obtained from nocturnal electrocardiogram Holter monitoring were analysed in 147 consecutive patients aged 53.8+/-11.2 yrs referred for possible OSAS. OSAS was diagnosed in 66 patients (44.9%) according to an apnoea/hypopnoea index > or = 10. Using receiver-operating characteristic curves analysis, the most powerful predictor variable was Wv32 (W 0.758, p<0.0001), followed by Wv16 (W 0.729, p<0.0001) and Wv64 (W 0.700, p<0.0001). Classification and Regression Trees methodology generated a decision tree for OSAS prediction including all levels of Wv coefficients, from Wv2 to Wv256 with a sensitivity reaching 92.4% and a specificity of 90.1% (percentage of agreement 91.2%) with this nonparametric analysis. Time-frequency parameters calculated using wavelet transform and extracted from the nocturnal heart period analysis appeared as powerful tools for obstructive sleep apnoea syndrome diagnosis. PMID:14680082

Roche, F; Pichot, V; Sforza, E; Court-Fortune, I; Duverney, D; Costes, F; Garet, M; Barthélémy, J C

2003-12-01

75

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

E-print Network

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

Jonathan R Gair; Ilya Mandel; Linqing Wen

2007-10-27

76

High-resolution geoacoustic inversion in shallow water: a joint time- and frequency-domain technique  

PubMed

High-resolution geoacoustic data are required for accurate predictions of acoustic propagation and scattering in shallow water. Since direct measurement of geoacoustic data is difficult, time-consuming, and expensive, inversion of acoustic data is a promising alternative. However, the main problem encountered in geoacoustic inversion is the problem of uniqueness, i.e., many diverse geoacoustic models can be made to fit the same data set. A key, and perhaps unique, aspect of this approach is the combination of data analysis in both the space-time and the space-frequency domains. This combination attempts to ameliorate the uniqueness problem by exploiting as much independent data as possible. In order to meet the stringent requirements of high spatial resolution and uniqueness, an entire method has been developed including a new measurement technique, processing/analysis technique, and inversion strategy. These techniques are described and then illustrated with a shallow-water data set. Sound-speed gradients in the upper few meters of the sub-bottom appear to be much higher (one order of magnitude) than generally assumed. And, although often ignored, a large density gradient was observed in the top layer that played an acoustically significant role. PMID:10738782

Holland; Osler

2000-03-01

77

Signal representation in the time-frequency plane  

NASA Astrophysics Data System (ADS)

Time-frequency analysis of a signal is discussed. It is shown that the information used in a communication signal does not characterize a given signal, but rather an equivalence class of signals. The need to represent this class by a single element leads to the introduction of the analytical signal. The element obtained, called the useful part of the signal, provides a general framework for the measurement and makes it possible to confirm the results of Gabor (1946) and Ville (1948). Time-frequency representations are introduced as a new way of expressing the useful part of a signal. It is shown that all of the acceptable representations necessarily belong to a general form proposed by Escudie and Grea in 1976. The adding of constraints then isolates Ville's representation within this class. Properties that are useful when applying Ville's representation are listed, and examples of the practical use of the latter are given.

Bertrand, P.

78

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

79

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

80

Time-frequency quantum process tomography of parametric down-conversion  

E-print Network

Parametric down-conversion (PDC) is the established standard for the practical generation of a multiplicity of quantum optical states. These include two-mode squeezed vacuum, heralded non-Gaussian states and entangled photon pairs. Detailed theoretical studies provide insight into the time-frequency (TF) structure of PDC, which are governed by the complex-valued joint spectral amplitude (JSA) function. However in experiments, the TF structure of PDC is mostly characterised by intensity measurementsthat forbid access to the important phase of the JSA. In this paper, we present an amplitude-sensitive quantum process tomography technique that combines methods from ultrafast optics and classical three-wave mixing. Our approach facilitates a direct and phase-sensitive time-frequency tomography of PDC with high spectral resolution and excellent signal-to-noise ratio. This is important for all quantum optical applications, which rely on engineered parametric processes and base on minute knowledge of the quantum wave-function for the generation of tailored photonic quantum states.

Malte Avenhaus; Benjamin Brecht; Kaisa Laiho; Christine Silberhorn

2014-06-17

81

A time-frequency algorithm for noisy BSS model  

NASA Astrophysics Data System (ADS)

In most practical blind source separation (BSS) applications, the observations contain additive source noise that limits the performances of most existing BSS algorithms. In this paper, we propose a new BSS approach exploiting the difference in the time-frequency (t-f) signatures of these sources to be separated. The approach uses smooth pseudo Wigner-Ville distribution (SPWVD) to obtain t-f distribution, then localizes the signal energy by Hough transform and selects a set of spatial t-f points based on the dominant eigenvalue of SPWVD of observations. Finally, numerical performance simulations are provided highlighting its effectiveness.

Guo, Jing; Zeng, Xiao-Ping

2011-10-01

82

Degraded time-frequency acuity to time-reversed notes.  

PubMed

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

83

Time-frequency discriminant analysis of MEG signals.  

PubMed

This paper introduces a novel statistical method that can identify relevant time-frequency features in brain signals to distinguish between groups. The feature of interest is the spectrum which characterizes the distribution of a given signal's variance (or power) across frequency oscillations. Brain signals are generally nonstationary in that the distribution of the signals' power across frequency changes over time. The classical Fourier analysis is not formally suitable for time series signals with time-varying spectra. This paper utilizes the SLEX (Smooth Localized Complex EXponentials) basis function to capture the transient features of brain signals. The SLEX basis consists of a set of localized orthogonal Fourier-like waveforms with a built-in mechanism for representing localized spectral features. The best basis is first chosen that maximizes group dissimilarity in the time-varying spectra. However, not all spectral features extracted from the best basis may be useful for discrimination and classification purpose. A thresholding scheme is further developed to remove irrelevant features from the best basis to improve accuracy for classification. In simulations the proposed SLEX-thresholding discriminant method was able to consistently identify the most discriminant time-frequency features and was able to correctly classify signals at a high rate. The method was then applied to magnetoencephalographic data from a standard paired-click paradigm. Discrimination between individuals with schizophrenia and a healthy comparison group confirmed the utility of the method. PMID:18158254

Ho, Moon-ho Ringo; Ombao, Hernando; Edgar, J Christopher; Cañive, Jose M; Miller, Gregory A

2008-03-01

84

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

85

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

86

Time-Frequency Methods for Structural Health Monitoring †  

PubMed Central

Detection of early warning signals for the imminent failure of large and complex engineered structures is a daunting challenge with many open research questions. In this paper we report on novel ways to perform Structural Health Monitoring (SHM) of flood protection systems (levees, earthen dikes and concrete dams) using sensor data. We present a robust data-driven anomaly detection method that combines time-frequency feature extraction, using wavelet analysis and phase shift, with one-sided classification techniques to identify the onset of failure anomalies in real-time sensor measurements. The methodology has been successfully tested at three operational levees. We detected a dam leakage in the retaining dam (Germany) and “strange” behaviour of sensors installed in a Boston levee (UK) and a Rhine levee (Germany). PMID:24625740

Pyayt, Alexander L.; Kozionov, Alexey P.; Mokhov, Ilya I.; Lang, Bernhard; Meijer, Robert J.; Krzhizhanovskaya, Valeria V.; Sloot, Peter M. A.

2014-01-01

87

Time-frequency analysis of synthetic aperture radar signals  

SciTech Connect

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

Johnston, B.

1996-08-01

88

Multiple linear regression to estimate time-frequency electrophysiological responses in single trials.  

PubMed

Transient sensory, motor or cognitive event elicit not only phase-locked event-related potentials (ERPs) in the ongoing electroencephalogram (EEG), but also induce non-phase-locked modulations of ongoing EEG oscillations. These modulations can be detected when single-trial waveforms are analysed in the time-frequency domain, and consist in stimulus-induced decreases (event-related desynchronization, ERD) or increases (event-related synchronization, ERS) of synchrony in the activity of the underlying neuronal populations. ERD and ERS reflect changes in the parameters that control oscillations in neuronal networks and, depending on the frequency at which they occur, represent neuronal mechanisms involved in cortical activation, inhibition and binding. ERD and ERS are commonly estimated by averaging the time-frequency decomposition of single trials. However, their trial-to-trial variability that can reflect physiologically-important information is lost by across-trial averaging. Here, we aim to (1) develop novel approaches to explore single-trial parameters (including latency, frequency and magnitude) of ERP/ERD/ERS; (2) disclose the relationship between estimated single-trial parameters and other experimental factors (e.g., perceived intensity). We found that (1) stimulus-elicited ERP/ERD/ERS can be correctly separated using principal component analysis (PCA) decomposition with Varimax rotation on the single-trial time-frequency distributions; (2) time-frequency multiple linear regression with dispersion term (TF-MLRd) enhances the signal-to-noise ratio of ERP/ERD/ERS in single trials, and provides an unbiased estimation of their latency, frequency, and magnitude at single-trial level; (3) these estimates can be meaningfully correlated with each other and with other experimental factors at single-trial level (e.g., perceived stimulus intensity and ERP magnitude). The methods described in this article allow exploring fully non-phase-locked stimulus-induced cortical oscillations, obtaining single-trial estimate of response latency, frequency, and magnitude. This permits within-subject statistical comparisons, correlation with pre-stimulus features, and integration of simultaneously-recorded EEG and fMRI. PMID:25665966

Hu, L; Zhang, Z G; Mouraux, A; Iannetti, G D

2015-05-01

89

Temperature gradient sensor based on a long-fiber Bragg grating and time-frequency analysis.  

PubMed

A photonic sensor based on a 10-cm-long fiber Bragg grating (FBG) is presented and experimentally validated that is dedicated to detect the presence and the position of a temperature gradient. The system is based on the measurement of the central frequency distribution of the grating based on time-frequency domain analysis. A short optical pulse, having duration much shorter than the transit time along the grating, is coupled into the FBG, and the back-reflected pulse is scanned by means of an oscilloscope. A spatial resolution of 1 mm, given by half the input pulse duration, is achieved. The proposed sensor is based on a simple configuration and presents a sensing range of 10 cm, which could be further enhanced by fabricating a longer grating. PMID:25360970

Ricchiuti, A L; Barrera, D; Nonaka, K; Sales, S

2014-10-01

90

Wind turbine gearbox health monitoring using time-frequency features from multiple sensors  

NASA Astrophysics Data System (ADS)

As wind energy plays an increasingly important role in the US and world electricity supply, maintenance of wind turbines emerges as a critical issue. Because of the remote nature of wind turbines, autonomous and robust health monitoring techniques are necessary. Detecting faults in complex systems such as wind turbine gearboxes remains challenging, even with the recently significant advancement of sensing and signal processing technologies. In this paper, we collect time domain signals from a gearbox test bed on which either a healthy or a faulty gear is installed. Then a harmonic wavelet based method is used to extract time-frequency features. We also develop a speed profile masking technique to account for tachometer readings and gear meshing relationship. Features from multiple sources are then fused together through a statistical weighting approach based on principal component analysis. Using the fused timefrequency features, we demonstrate that different gear faults can be effectively identified through a simple decision making algorithm.

Lu, Y.; Tang, J.

2011-04-01

91

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

92

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

93

Analysis and synthesis of room reverberation based on a statistical time-frequency model  

Microsoft Academic Search

This paper reviews a statistical time-frequency model of late reverberation decays, and describes an associated analysis procedure for deriving the time-frequency envelope of the reverberation from a measured impulse response, based on the notion of \\

Jean-Marc Jot; Laurent Cerveau; Olivier Warusfel

1997-01-01

94

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

95

Assessment of the flow velocity of blood cells in a microfluidic device using joint spectral and time domain optical coherence tomography.  

PubMed

Although Doppler optical coherence tomography techniques have enabled the imaging of blood flow in mid-sized vessels in biological tissues, the generation of velocity maps of capillary networks remains a challenge. To better understand the origin and information content of the Doppler signal from small vessels and limitations of such measurements, we used joint spectral and time domain optical coherence tomography to monitor the flow in a model, semitransparent microchannel device. The results obtained for Intralipid, whole blood, as well as separated red blood cells indicate that the technique is suitable to record velocity profiles in vitro, in a range of microchannel configurations. PMID:24104312

Bukowska, Danuta M; Derzsi, Ladislav; Tamborski, Szymon; Szkulmowski, Maciej; Garstecki, Piotr; Wojtkowski, Maciej

2013-10-01

96

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

97

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

E-print Network

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

Torrésani, Bruno

98

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

E-print Network

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

Paris-Sud XI, Université de

99

Time frequency analysis of sound from a maneuvering rotorcraft  

NASA Astrophysics Data System (ADS)

The acoustic signatures produced by a full-scale, Bell 430 helicopter during steady-level-flight and transient roll-right maneuvers are analyzed by way of time-frequency analysis. The roll-right maneuvers comprise both a medium and a fast roll rate. Data are acquired using a single ground based microphone that are analyzed by way of the Morlet wavelet transform to extract the spectral properties and sound pressure levels as functions of time. The findings show that during maneuvering operations of the helicopter, both the overall sound pressure level and the blade-vortex interaction sound pressure level are greatest when the roll rate of the vehicle is at its maximum. The reduced inflow in the region of the rotor disk where blade-vortex interaction noise originates is determined to be the cause of the increase in noise. A local decrease in inflow reduces the miss distance of the tip vortex and thereby increases the BVI noise signature. Blade loading and advance ratios are also investigated as possible mechanisms for increased sound production, but are shown to be fairly constant throughout the maneuvers.

Stephenson, James H.; Tinney, Charles E.; Greenwood, Eric; Watts, Michael E.

2014-10-01

100

Specific arrangement of alpha-helical coiled coils in the core domain of the bacterial flagellar hook for the universal joint function.  

PubMed

The bacterial flagellar hook is a short, highly curved tubular structure connecting the rotary motor to the filament acting as a helical propeller. The bending flexibility of the hook allows it to work as a universal joint. A partial atomic model of the hook revealed a sliding intersubunit domain interaction along the protofilament to produce bending flexibility. However, it remained unclear how the tightly packed inner core domains can still permit axial extension and compression. We report advances in cryoEM image analysis for high-resolution, high-throughput structural analysis and a density map of the hook that reveals most of the secondary structures, including the terminal alpha helices forming a coiled coil. The orientations and axial packing interactions of these two alpha helices are distinctly different from those of the filament, allowing them to have a room for axial compression and extension for bending flexibility without impairing the mechanical stability of the hook. PMID:19913483

Fujii, Takashi; Kato, Takayuki; Namba, Keiichi

2009-11-11

101

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

102

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

103

Sparse component analysis using time-frequency representations for operational modal analysis.  

PubMed

Sparse component analysis (SCA) has been widely used for blind source separation(BSS) for many years. Recently, SCA has been applied to operational modal analysis (OMA), which is also known as output-only modal identification. This paper considers the sparsity of sources' time-frequency (TF) representation and proposes a new TF-domain SCA under the OMA framework. First, the measurements from the sensors are transformed to the TF domain to get a sparse representation. Then, single-source-points (SSPs) are detected to better reveal the hyperlines which correspond to the columns of the mixing matrix. The K-hyperline clustering algorithm is used to identify the direction vectors of the hyperlines and then the mixing matrix is calculated. Finally, basis pursuit de-noising technique is used to recover the modal responses, from which the modal parameters are computed. The proposed method is valid even if the number of active modes exceed the number of sensors. Numerical simulation and experimental verification demonstrate the good performance of the proposed method. PMID:25789492

Qin, Shaoqian; Guo, Jie; Zhu, Changan

2015-01-01

104

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

PubMed Central

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

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

2013-01-01

105

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

106

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

107

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

108

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 of the laboratory tests, including CRP and blood culture, have high predictive accuracy. Heart rate variability (HRV. The objective of this study was to determine if analysis of time-frequency correlations between the heart rate

Paris-Sud XI, Université de

109

Time-frequency spectral estimation of multichannel EEG using the Auto-SLEX method  

Microsoft Academic Search

In this paper, we apply a new time-frequency spectral estimation method for multichannel data to epileptiform electroencephalography (EEG). The method is based on the smooth localized complex exponentials (SLEX) functions which are time-frequency localized versions of the Fourier functions and, hence, are ideal for analyzing nonstationary signals whose spectral properties evolve over time. The SLEX functions are simultaneously orthogonal and

Stephen D. Cranstoun; Hernando C. Ombao; R. von Sachs; Wensheng Guo; B. Litt

2002-01-01

110

Time-Frequency Characterization and Receiver Waveform Design for Shallow Water  

E-print Network

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

Paris-Sud XI, Université de

111

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

112

Time-frequency multipliers for sound synthesis Philipe Depallea,b, Richard Kronland-Martinetb and Bruno Torresanic  

E-print Network

be optimized to morph a given sound into another one, at a very high sound quality. Keywords: Time-frequencyTime-frequency multipliers for sound synthesis Philipe Depallea,b, Richard Kronland analysis, time-frequency multipliers, LTV systems, sound synthesis 1. INTRODUCTION Time-frequency analysis

Paris-Sud XI, Université de

113

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

E-print Network

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 2D 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 is 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.

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

2014-11-21

114

Continuous-variable quantum computing in optical time-frequency modes using quantum memories.  

PubMed

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. PMID:25302876

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

2014-09-26

115

Time-Frequency Distribution Analyses of Ku-Band Radar Doppler Echo Signals  

NASA Astrophysics Data System (ADS)

Real radar echo signals of a pedestrian, vehicle and group of helicopters are analyzed in order to maximize signal energy around central Doppler frequency in time-frequency plane. An optimization, preserving this concentration, is suggested based on three well-known concentration measures. Various window functions and time-frequency distributions were optimization inputs. Conducted experiments on an analytic and three real signals have shown that energy concentration significantly depends on used time-frequency distribution and window function, for all three used criteria.

Bujakovi?, Dimitrije; Andri?, Milenko; Bondžuli?, Boban; Mitrovi?, Sr?an; Simi?, Slobodan

2015-03-01

116

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...

117

Packet acquisition for time-frequency hopped asynchronous random multiple access  

E-print Network

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

Nguyen, Hoang

118

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

E-print Network

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

Almor, Amit

119

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

PubMed Central

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

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

2015-01-01

120

Detection of leak acoustic signal in buried gas pipe based on the time–frequency analysis  

Microsoft Academic Search

A time–frequency technique for locating leaks in buried gas distribution pipes involves the use of the cross-correlation on two measured acoustic signals on either side of a leak. This technique can be problematic for locating leaks in steel pipes, as the acoustic signals in these pipes are generally narrow-band and low frequency. The effectiveness of the time–frequency technique for detecting

Min-Soo Kim; Sang-Kwon Lee

2009-01-01

121

Time-Frequency Analysis of the Delta Modulation and PWM Control for the Asynchronous Motors  

Microsoft Academic Search

This work presents some considerations on a control method for a three-phase asynchronous motor and a time-frequency analysis of the proposed system. The control method uses the delta modulation principle to generate the command signals for a full bridge power inverter that drives three phase asynchronous motor. The time-frequency analysis can bring more new information that could be used to

Daniel N. Trip; Comelia Gordan; M. I. Gordan; A. Schiop; R. Reiz

2005-01-01

122

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

Microsoft Academic Search

Abstractó We describe a new adaptive family of multiwindow Gabor expansions, which adapt dynamically the windows to the signal’s features in time-frequency space. The adaptation is based upon local time-frequency sparsity criteria, and also yields as by- product an expansion of the signal into layers corresponding to different windows. As an illustration, we show that using simply two different windows

Florent Jaillet; Bruno Torr

123

Phase and amplitude analysis in time–frequency space—application to voluntary finger movement  

Microsoft Academic Search

Two methods operating in time–frequency space were applied to analysis of EEG activity accompanying voluntary finger movements. The first one, based on matching pursuit approach provided high-resolution distributions of power in time–frequency space. The phenomena of event related desynchronization (ERD) and synchronization (ERS) were investigated without the need of band-pass filtering. Time evolution of ?- and ?-components was observed in

J. Ginter; K. J. Blinowska; M. Kami?ski; P. J. Durka

2001-01-01

124

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

PubMed Central

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

2013-01-01

125

High speed sound sources localization using bilinear time-frequency transformation  

Microsoft Academic Search

This paper proposes a new method to locate high speed moving sound sources based on a bilinear time-frequency transformation. A microphone array, used as a directional sensor, is optimised in order to focus on the linear part of the frequency modulation due to the Doppler effect. Simulations are carried out to quantify the accuracy of the localizations. A comparison is

F. Poisson; J. C. Valiere; P. Herzog

1998-01-01

126

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

127

Heart rate variability characterization: time-frequency representation and nonlinear analysis  

Microsoft Academic Search

Time-frequency representation (TFR) and complexity measures based on the correlation dimension are applied to the characterization of the Heart Rate Variability, (HRV). For this study 117 subjects are analyzed from the IDEAL database, 53 patients with idiopathic dilated cardiomyopathy (IDC); 64 normal subjects (NRM). IDC patients are classified by means of their ejection fraction. The RR series are analyzed during

M. Vallverdu; F. Claria; R. Carvajal; P. Martinez; J. L. Alonso; W. Zareba; X. Vinolas; A. Bayes de Luna; P. Caminal

1999-01-01

128

Data-driven design and complexity control of time–frequency detectors  

Microsoft Academic Search

In this paper, we introduce a method of designing optimal time–frequency detectors from training samples, which is potentially of great benefit when few a priori information on the nonstationary signal to be detected is available. However, achieving good performance with data-driven detectors requires matching their complexity to the available amount of training samples: receivers with a too large number of

Cédric Richard; Régis Lengellé

1999-01-01

129

Analysis of Cardio-respiratory Dynamics during Mental Stress using (Partial) Time-Frequency Spectra  

E-print Network

to conduct a combined analysis of the cardio-respiratory system. In this study, we will perform cross timeAnalysis of Cardio-respiratory Dynamics during Mental Stress using (Partial) Time-Frequency Spectra Engineering, ESAT - STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, KU Leuven

130

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

131

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

132

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

E-print Network

Damage mechanisms identification of polymer based composite materials: time-frequency investigation by means of AE in polymer composites prompted the possibility of correlating a specific damage mechanism- ical behavior,their damage mechanisms still require a better understanding. Several studies [1, 2

Paris-Sud XI, Université de

133

Enhanced Performance by Time-Frequency-Phase Feature for EEG-Based BCI Systems  

PubMed Central

We introduce a new motor parameter imagery paradigm using clench speed and clench force motor imagery. The time-frequency-phase features are extracted from mu rhythm and beta rhythms, and the features are optimized using three process methods: no-scaled feature using “MIFS” feature selection criterion, scaled feature using “MIFS” feature selection criterion, and scaled feature using “mRMR” feature selection criterion. Support vector machines (SVMs) and extreme learning machines (ELMs) are compared for classification between clench speed and clench force motor imagery using the optimized feature. Our results show that no significant difference in the classification rate between SVMs and ELMs is found. The scaled feature combinations can get higher classification accuracy than the no-scaled feature combinations at significant level of 0.01, and the “mRMR” feature selection criterion can get higher classification rate than the “MIFS” feature selection criterion at significant level of 0.01. The time-frequency-phase feature can improve the classification rate by about 20% more than the time-frequency feature, and the best classification rate between clench speed motor imagery and clench force motor imagery is 92%. In conclusion, the motor parameter imagery paradigm has the potential to increase the direct control commands for BCI control and the time-frequency-phase feature has the ability to improve BCI classification accuracy. PMID:25045733

Xu, Baolei; Fu, Yunfa; Shi, Gang; Yin, Xuxian; Wang, Zhidong; Li, Hongyi; Jiang, Changhao

2014-01-01

134

Time-frequency analysis of sensor data for detection of structural damage in instrumented structures  

Microsoft Academic Search

An experimental time-frequency analysis framework is developed for monitoring the occurrence and location of structural damage in instrumented structures such as bridges. We make available a software package written in Matlab that provides assistance in assessing the condition of the structural system with excellent visualization tools and interaction with the user. Data were obtained from an actual experimental bridge, instrumented

A. Karasaridis; M. Maalej; S. Pantazopoulou; D. Hatzinakos

1997-01-01

135

Time Frequency Analysis of Dolphin Clicks Reveals Fine Temporal Structure1  

E-print Network

Time Frequency Analysis of Dolphin Clicks Reveals Fine Temporal Structure1 Judah Jacobson2 Maryam Saleh3 Nathan Intrator4 Introduction One of the most effective ways for a dolphin to perceive its capability is ideal for life in an aquatic environment. Dolphin sound emissions can be classified into two

Intrator, Nathan

136

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

SciTech Connect

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

Candy, J.V., LLNL

1997-12-31

137

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

138

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

Code of Federal Regulations, 2014 CFR

...employer's needs as to the timing, frequency or duration of service? 1002.104...employer's needs as to the timing, frequency or duration of service? No. The...interests or concerns regarding the timing, frequency, or duration of uniformed...

2014-04-01

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

2015-03-01

142

Ecological prediction with nonlinear multivariate time-frequency functional data models  

USGS Publications Warehouse

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

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

2013-01-01

143

Coded Space-Time-Frequency OFDM over IEEE 802.11 Fading Channels  

Microsoft Academic Search

In this paper we present 4 transmit and 1 receive (4Tx:1Rx) antenna system of coded space-time-frequency in conjunction with orthogonal frequency division multiplexing (coded STF-OFDM). We concatenate STF block code with channel coding namely convolutional code of rate 1\\/2 with length 5 to combat channel impairment. We compare our coded STF scheme with ST-OFDM and SF-OFDM over IEEE 802.11 multipath

N. K. Noordin; B. M. Ali; S. S. Jamuar; M. B. Ismail

2005-01-01

144

A Novel Layered Space-Time-Frequency Architecture with Convolutional Coding  

Microsoft Academic Search

For orthogonal frequency division multiplexing (OFDM) multiple-input multiple-output (MIMO) multiplexing in high speed wireless transmission under broadband fading channel, a novel coded layered space-time-frequency (LSTF) architecture is proposed, which can achieve the available spatial, temporal and frequency diversity, and make the system implementation easy for high data rate transmission. In this novel architecture, each independently coded layer is threaded in

Yuanliang Huang; Jiangzhou Wang; Kenichi Higuchi

2007-01-01

145

Space-time-frequency coded-OFDM employing adaptive multiple antenna selection over WLAN fading channels  

Microsoft Academic Search

In this paper we present an adaptive multiple antenna selection (AdMAS) employing a maximum of 4 transmit (4 Tx) and 1 receive (1 Rx) antenna in conjunction with coded space-time-frequency (STF) orthogonal frequency division multiplexing (OFDM) over wireless local area network (WLAN) IEEE 802.11 channels. Our coded STF-OFDM is a product of 4-QAM STF block code which has been concatenated

N. K. Noordin; Borhanuddin M. Ali; S. S. Jamuar; M. B. Ismail

2005-01-01

146

A real-time implementable subclass of quadratic time-frequency representations  

Microsoft Academic Search

One of the major obstacles for quadratic time-frequency representations to be used in real (finite)-time applications is the computational complexity. In this paper, a real (finite)-time implementable subclass of Cohen's (1966) class of distributions (CCD) is defined using windowing techniques. The kernel function for each member in this subclass can be characterized by a necessary and sufficient real(finite)-time implementable condition

Dongsheng Wu; Joel M. Morris

1994-01-01

147

A novel distance protection scheme using time-frequency analysis and pattern recognition approach  

Microsoft Academic Search

This paper presents a new approach for distance protection of transmission lines using time-frequency analysis. The proposed technique consists of preprocessing the fault current signal samples using hyperbolic S-transform to yield the change in energy and standard deviation at the appropriate window variation. From these two features, a decision of fault or no-fault on any phase or multiple phases of

P. K. Dash; S. R. Samantaray

2007-01-01

148

Rate-Maximizing Adaptation in Multiantenna OFDM Systems With Space-Time-Frequency Coding  

Microsoft Academic Search

In this paper, we first propose a space-time-frequency (STF) coding method for multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) transmission over frequency-selective fading channels and then, based on channel mean feedback model, we develop an adaptive MIMO-OFDM transmitter by applying an adaptive energy and bit loading scheme across OFDM subcarriers. Under the constraints of fixed transmit-energy and prescribed error performance,

Mahdi Golparvar Roozbahani; Babak H. Khalaj

2006-01-01

149

Alias-free generalized discrete-time time-frequency distributions  

Microsoft Academic Search

A definition of generalized discrete-time time-frequency distribution that utilizes all of the outer product terms from a data sequence, so that one can avoid aliasing, is introduced. The new approach provides (1) proper implementation of the discrete-time spectrogram, (2) correct evaluation of the instantaneous frequency of the underlying continuous-time signal, and (3) correct frequency marginal. The formulation provides a unified

Jechang Jeong; William J. Williams

1992-01-01

150

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

151

Time\\/frequency mapping of the heart rate, blood pressure and respiratory signals  

Microsoft Academic Search

The discrete Wigner distribution (DWD) was implemented for the time\\/frequency mapping of variations of R-R interval, blood\\u000a pressure and respiratory signals. The smoothed cross-DWD was defined and the modified algorithm for the smoothed auto- and\\u000a cross-DWD was proposed. Spurious cross-terms were suppressed using a smoothing data window and a Gauss frequency window. The\\u000a DWD is easy to implement using the

P. Novak; V. Novak

1993-01-01

152

Dating a tropical ice core by time-frequency analysis of ion concentration depth profiles  

NASA Astrophysics Data System (ADS)

Ice core dating is a key parameter for the interpretation of the ice archives. However, the relationship between ice depth and ice age generally cannot be easily established and requires the combination of numerous investigations and/or modelling efforts. This paper presents a new approach to ice core dating based on time-frequency analysis of chemical profiles at a site where seasonal patterns may be significantly distorted by sporadic events of regional importance, specifically at the summit area of Nevado Illimani (6350 m a.s.l.), located in the eastern Bolivian Andes (16°37' S, 67°46' W). We used ion concentration depth profiles collected along a 100 m deep ice core. The results of Fourier time-frequency and wavelet transforms were first compared. Both methods were applied to a nitrate concentration depth profile. The resulting chronologies were checked by comparison with the multi-proxy year-by-year dating published by de Angelis et al. (2003) and with volcanic tie points. With this first experiment, we demonstrated the efficiency of Fourier time-frequency analysis when tracking the nitrate natural variability. In addition, we were able to show spectrum aliasing due to under-sampling below 70 m. In this article, we propose a method of de-aliasing which significantly improves the core dating in comparison with annual layer manual counting. Fourier time-frequency analysis was applied to concentration depth profiles of seven other ions, providing information on the suitability of each of them for the dating of tropical Andean ice cores.

Gay, M.; De Angelis, M.; Lacoume, J.-L.

2014-09-01

153

Time-frequency analysis of heart rate variability signals in patients with autonomic dysfunction  

Microsoft Academic Search

An imbalance in the autonomic nervous system has been suspected in patients with coronary artery disease during episodes of silent ischemia. Frequency analysis of the beat-to-beat heart rate variability (HRV) signals reveals a signature of autonomic regulation of the heart. We performed time-frequency analysis of HRV records containing silent ischemic episodes. In 14 out of 17 (82%) HRV data sets

M. V. Kamath; T. Bentley; R. Spaziani; G. Tougas; E. L. Fallen; N. McCartney; J. Runions; A. R. M. Upton

1996-01-01

154

Performance comparison of time-frequency distributions for ultrasonic nondestructive testing  

Microsoft Academic Search

In the nondestructive testing of materials ultrasonic backscattered echoes often exhibit critical time and frequency information. The time-frequency (t-f) analysis of ultrasonic signals instantaneously reveals the frequency and time of arrival of target echoes which help to characterize the target. But varying results are obtained by applying different t-f algorithms to ultrasonic signals. Performance evaluation of t-f algorithms for ultrasonic

M. A. Malik; J. Saniie

1996-01-01

155

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

156

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

E-print Network

Wavelet Transform (CWT) and the Short-Time Fourier Transform (STFT) to perform time-frequency analyses Time Frequency and Kolmogorov-Smirnov Methods Kobby Essien Kobby.Essien@alum.dartmouth.org Student of the Short-Time Fourier Transform and the Continuous Wavelet Transform together with amino acid

157

Quantification and visualization of event-related changes in oscillatory brain activity in the time–frequency domain  

Microsoft Academic Search

In this chapter we review the traditional approach for ERD\\/ERS quantification and a more recent approach based on wavelet transform. In particular, we address the visualization of these phenomena and the validation of the results through statistical significance testing. Furthermore, we report on preprocessing using independent component analysis (ICA) and introduce a novel ERD\\/ERS maximization method.

Bernhard Graimann; Gert Pfurtscheller

2006-01-01

158

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

159

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

160

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 (300-700 ms) was larger in the incongruent condition. The evoked delta (250-600 ms) was larger in the congruent condition particularly over parieto-occipital regions. The larger frontal theta response in the incongruent condition was associated with the detection of interference and inhibition of the response to task-irrelevant features, while the larger evoked delta in the congruent condition was suggestive of the easier decision process owing to congruency between the physical attribute and the verbal meaning of the stimuli. Furthermore, in the incongruent condition, amplitude of the occipital total alpha in the very late phase (700-900 ms) was smaller. This prolonged desynchronization in the alpha band could be reflecting augmentation of attentional filters in visual modality for the next stimulus. These multiple findings on EEG time-frequency plane provide improved description of the overlapping processes in Stroop test. PMID:25135670

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

2014-12-01

161

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

162

Audio source separation with multiple microphones on time-frequency representations  

NASA Astrophysics Data System (ADS)

This paper presents various source separation methods that utilize multiple microphones. We classify them into two classes. Methods that fall into the first class apply independent component analysis (ICA) or Gaussian mixture model (GMM) to frequency bin-wise observations, and then solve the permutation problem to reconstruct separated signals. The second type of method extends non-negative matrix factorization (NMF) to a multimicrophone situation, in which NMF bases are clustered according to their spatial properties. We have a unified understanding that all methods analyze a time-frequency representation with an additional microphone axis.

Sawada, Hiroshi

2013-05-01

163

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

164

A Time-Frequency Functional Model for Locally Stationary Time Series Data  

PubMed Central

Unlike traditional time series analysis that focuses on one long time series, in many biomedical experiments, it is common to collect multiple time series and focus on how the design covariates impact the patterns of stochastic variation over time. In this article, we propose a time-frequency functional model for a family of time series indexed by a set of covariates. This model can be used to compare groups of time series in terms of the patterns of stochastic variation and to estimate the covariate effects. We focus our development on locally stationary time series and propose the covariate-indexed locally stationary setting, which include stationary processes as special cases. We use smoothing spline ANOVA models for the time-frequency coefficients. A two-stage procedure is introduced for estimation. To reduce the computational demand, we develop an equivalent state space model to the proposed model with an efficient algorithm. We also propose a new simulation method to generate replicated time series from their design spectra. An epileptic intracranial electroencephalogram (IEEG) dataset is analyzed for illustration. PMID:20228961

Qin, Li; Guo, Wensheng; Litt, Brian

2009-01-01

165

Time-frequency analysis in optical coherence tomography for technical objects examination  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) is one of the most advanced optical measurement techniques for complex structure visualization. The advantages of OCT have been used for surface and subsurface defect detection in composite materials, polymers, ceramics, non-metallic protective coatings, and many more. Our research activity has been focused on timefrequency spectroscopic analysis in OCT. It is based on time resolved spectral analysis of the backscattered optical signal delivered by the OCT. The time-frequency method gives spectral characteristic of optical radiation backscattered or backreflected from the particular points inside the tested device. This provides more information about the sample, which are useful for further analysis. Nowadays, the applications of spectroscopic analysis for composite layers characterization or tissue recognition have been reported. During our studies we have found new applications of spectroscopic analysis. We have used this method for thickness estimation of thin films, which are under the resolution of OCT. Also, we have combined the spectroscopic analysis with polarization sensitive OCT (PS-OCT). This approach enables to obtain a multiorder retardation value directly and may become a breakthrough in PS-OCT measurements of highly birefringent media. In this work, we present the time-frequency spectroscopic algorithms and their applications for OCT. Also, the theoretical simulations and measurement validation of this method are shown.

StrÄ kowski, Marcin R.; Kraszewski, Maciej; Trojanowski, Micha?; Pluci?ski, Jerzy

2014-05-01

166

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

167

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

168

Time-frequency analysis of movement-related spectral power in EEG during repetitive movements: a comparison of methods  

PubMed Central

During dynamic voluntary movements, power in the ?-and ?-bands resulting from synchronized neuronal activity is modulated in a manner that is time-locked to movement onset. These signals can be readily recorded from the scalp surface using electroencephalography. Abnormalities in the magnitude and timing of these oscillations are present in a wide variety of movement disorders including Parkinson’s disease and dystonia. Most studies have examined movement-related oscillations in the context of single discrete movements, yet marked impairments are often seen during the performance of repetitive movements. For this reason, there is considerable need for analysis methods that can resolve the modulation of these oscillations in both the frequency and time domains. Presently, there is little consensus on which is the most appropriate method for this purpose. In this paper, a comparison of commonly used time-frequency methods is presented for the analysis of movement-related power in the ?-and ?-bands during repetitive movements. The same principles hold, however, for any form of repetitive or rhythmic input-output processes in the brain. In particular, methods based on band-pass filtering, the short-time Fourier transform (STFT), continuous wavelet transform and reduced interference distributions are discussed. The relative merits and limitations in terms of spectral or temporal resolution of each method are shown with the use of simulated and experimental data. It is shown that the STFT provides the best compromise between spectral and temporal resolution and thus is the most appropriate approach for the analysis and interpretation of repetitive movement-related oscillations in health and disease. (250 words) PMID:19909774

MacKinnon, Colum D.

2009-01-01

169

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

PubMed

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

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

2015-04-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

171

Enhanced sonar array target localization using time-frequency interference phenomena  

NASA Astrophysics Data System (ADS)

The ability of traditional active sonar processing methods to detect targets is often limited by clutter and reverberation from ocean environments. Similarly, multipath arrivals from radiating sources such as ships and submarines are received at sensors in passive sonar systems. Reverberation and multipath signals introduce constructive and destructive interference patterns in received spectrograms in both active and passive sonar applications that vary with target range and frequency. The characterization and use of interference phenomena can provide insights into environmental parameters and target movement in conjunction with standard processing methods including spectrograms and array beamforming. This thesis focuses on utilizing the time-frequency interference structure of moving targets captured on sonar arrays to enhance the resolution and abilities of conventional sonar methods to detect and localize targets. Physics-based methods for interference-based beamforming and target depth separation are presented with application of these methods shown using broadband simulated array data.

Shibley, Jordan Almon

172

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

173

Application of time-frequency representations to classification of vibration signals of electric motors  

NASA Astrophysics Data System (ADS)

Examination of advantages and disadvantages of some not commonly used time-frequency representations of vibration signals has been the aim of the paper. The study has been mainly devoted to Wigner-Ville decomposition as well as instantaneous amplitude and frequency. These representations have been examined from the pattern recognition point of view. The Wigner-Ville decomposition was compared with short time Fourier transform taking into account its classification power. In the case of instantaneous amplitude and frequency representation a new method of feature extraction followed by classification using optimal neural classifier has been proposed. Results have been illustrated using a data set of signals measured by a laser vibrometer. They proved that the method proposed in the paper could be used for very fast classification based on vibration signals measured in transient state.

Grabowski, D.

2004-06-01

174

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

175

Time-frequency characteristics based motion estimation and imaging for high speed spinning targets via narrowband waveforms  

Microsoft Academic Search

This paper focuses on the motion parameters estimation and inversed synthetic aperture radar (ISAR) imaging for the high-speed\\u000a spinning targets via the time-frequency characteristics. Assuming that the translational motion is compensated with the available\\u000a motion compensation techniques, then the residual part of translational motion and the spinning motion are estimated with\\u000a high precision based on the time-frequency characteristics. Combining with

Lei Zhang; YaChao Li; Yan Liu; MengDao Xing; Zheng Bao

2010-01-01

176

On the statistical significance of event-related EEG desynchronization and synchronization in the time-frequency plane  

Microsoft Academic Search

We propose and discuss a complete framework for estimating significant changes in the average time-frequency density of energy of event-related signals. Addressed issues include estimation of time-frequency energy density (matching pursuit and spectrogram), choice of resampling statistics to test the hypothesis of change in one small region (resel), and correction for multiplicity (false discovery rate). We present estimation of the

Piotr J. Durka; J. Zygierewicz; H. Klekowicz; J. Ginter; K. J. Blinowska

2004-01-01

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 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

179

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

PubMed

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

Pätynen, Jukka; Tervo, Sakari; Lokki, Tapio

2013-02-01

180

Identification of intestinal pacemaker frequency through time-frequency ridge analysis of surface EEnG.  

PubMed

The non-invasive monitoring of the frequency of intestinal pacemaker activity (slow wave, SW) has an important diagnostic value. However the presence of noise, physiological interferences and spurious peaks of the spectral estimators can yield to misidentification of SW frequency when using conventional dominant frequency detection method. In this paper, two methods of ridge extraction from the time-frequency distribution of human surface electroenterogram (EEnG) are proposed for the identification and tracking of SW frequency in 13 recording sessions of 120 minutes in 13 healthy volunteers. The minimum average distance method, that includes of information of previous and subsequent windows of analysis, yields the best results in terms of providing ridges that are longer, with less interruptions and with more stable frequency values which better suit the ubiquity and rhythmicity characteristics of the intestinal SW. This technique permits to reduce misinterpretations of intestinal SW frequency which can be of great importance in diagnostic applications of EEnG. PMID:25570456

Garcia-Casado, J; Ye-Lin, Y; Avalos-Gallardo, E G; Zena-Gimenez, V; Prats-Boluda, G

2014-01-01

181

Continuous Time-Frequency Transform for Unevenly Sampled Time Series and Significance Testing  

NASA Astrophysics Data System (ADS)

Spectral analysis is a common approach for the interpretation of climate time series. In particular, the continuous wavelet transform and the Gabor transform are generally well-suited for non-stationary, multi-periodic and highly noisy data. The purpose of this contribution is to propose a rigorous framework to estimate the significance of wavelet spectra given unevenly sampled data. To this end, we expand the theory developed by G. Foster [1], originally targeted for astronomical data, as follows: (i) Define the model: Significance testing is always based on a model, that needs to be properly defined. (ii) Define the parametric hypotheses H0 (null case) and H1 (alternative case), and attempt to find an appropriate statistical summary. The idea is to obtain a well-known distribution under H0, allowing an analytical approach and avoiding most of Monte-Carlo simulations which can be expensive in time. We also discuss the choice to be done for the analysis function of the time-frequency transform. Indeed, Morlet wavelet is often chosen, but it is not always the best option. Some examples of paleoclimate time series analysis will be given. Finally, we investigate whether considering the interpolated data to get a constant time step and using the traditional tools may lead to significant errors. Reference: [1] G. Foster. Wavelets for period analysis of unevenly sampled time series. The Astronomical Journal, 112(4):1709-1729, 1996.

Lenoir, Guillaume; Crucifix, Michel

2014-05-01

182

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

183

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

184

Time-frequency composition of mosquito flight tones obtained using Hilbert spectral analysis.  

PubMed

Techniques for estimating temporal variation in the frequency content of acoustic tones based on short-time fast Fourier transforms are fundamentally limited by an inherent time-frequency trade-off. This paper presents an alternative methodology, based on Hilbert spectral analysis, which is not affected by this weakness, and applies it to the accurate estimation of mosquito wing beat frequencies. Mosquitoes are known to communicate with one another via the sounds generated by their flapping wings. Active frequency modulation between pairs of mosquitoes is thought to take place as a precursor to courtship. Studying the acoustically-based interactions of mosquitoes therefore relies on an accurate representation of flight frequency as a time-evolving property, yet conventional Fourier spectrograms are unable to capture the rapid modulations in frequency that mosquito flight tones exhibit. The algorithms introduced in this paper are able to automatically detect and extract fully temporally resolved frequency information from audio recordings. Application of the technique to experimental recordings of single tethered mosquitoes in flight reveals corroboration with previous reported findings. The advantages of the method for animal communication studies are discussed, with particular attention given to its potential utility for studying pairwise mosquito interactions. PMID:25324097

Aldersley, Andrew; Champneys, Alan; Homer, Martin; Robert, Daniel

2014-10-01

185

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

186

Relation between deep bioluminescence and oceanographic variables: A statistical analysis using time-frequency decompositions  

NASA Astrophysics Data System (ADS)

We consider the statistical analysis of a 1.7-year high-frequency sampled time series, between 2009 and 2010, recorded at the ANTARES observatory in the deep NW Mediterranean Sea (2475 m depth). The objective was to estimate relationships between bioluminescence and environmental time series (temperature, salinity and current speed). As this entire dataset is characterized by non-linearity and non-stationarity, two time-frequency decomposition methods (wavelet and Hilbert-Huang) were used. These mathematical methods are dedicated to the analysis of a signal at various time and frequencies scales. This work propose some statistical tools dedicated to the study of relationships between two time series. Our study highlights three events of high bioluminescence activity in March 2009, December 2009 and March 2010. We demonstrate that the two events occurring in March 2009 and 2010 are correlated to the arrival of newly formed deep water masses at frequencies of approximately 4.8×10-7 (period of 24.1 days). In contrast, the event in December 2009 is only correlated with current speed at frequencies of approximately 1.9×10-6 (period of 6.0 days). The use of both wavelet and Hilbert-Huang transformations has proven to be successful for the analysis of multivariate time series. These methods are well-suited in a context of the increasing number of long time series recorded in oceanography.

Martini, S.; Nerini, D.; Tamburini, C.

2014-09-01

187

Pulse transformation and time-frequency filtering with electromagnetically induced transparency  

NASA Astrophysics Data System (ADS)

A simple analytical solution for the propagation of a weak Gaussian pulse in a dense absorptive medium with electromagnetically induced transparency is found. This solution is applied to the analysis of three regimes: (1) and (2) the pulse spectrum is narrower than the transparency window [which is narrow (1) or wide (2) with respect to the width of the absorption line] and (3) the pulse spectrum is broader than the transparency window. It is shown that the pulse maintains its area in all three regimes and maintains its Gaussian shape but narrows in spectrum in regime 1. In regime 2, the pulse begins to distort after a certain distance. In regime 3, the pulse is split into two parts. One part is an adiabatic part with a spectrum defined by the effective width of the transparency window for a thick medium and the other is an oscillating nonadiabatic part of short duration. The adiabatic part propagates slowly and the nonadiabatic part propagates with a velocity close to the speed of light. Thus in regime 3, the medium acts as a time-frequency filter, separating the narrow and wide spectrum components of the pulse in time at the output of the absorber.

Shakhmuratov, R. N.; Odeurs, J.

2005-01-01

188

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

189

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

190

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

191

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

192

[Time-frequency analysis of ventricular fibrillation and the effects of amiodarone].  

PubMed

This study is to quantify time-varying dominant frequencies in electrocardiogram (ECG) during the ventricular fibrillation (VF). Orthogonal ECG (sagittal, x; transverse, y; and longitudinal, z) and the transvenous two-leads defibrillation systems were set in 19 dogs. Time-frequency analysis was used to assess changes in the dominant frequency within ECG recorded in dogs during trials of 10-30 s of VF. In 4 additional dogs, the dominant frequencies were compared during 10 s of VF before and after administration of amiodarone. Results showed that in the 427 trials of 10 s VF and 335 trials of 30 s VF, average variation in the dominant frequency was considerable, between +/- 12%-18%. The frequencies orthogonal ECG during 10 s VF were distributed symmetrically above and below the mean frequency like a normal distribution. In the 79 trials with administration of amiodarone during 10 s VF in all three ECG, the mean frequencies decreased from 6.5 (x), 7.4 (y) and 7.0 Hz (z) to 6.1, 6.4 and 6.3 Hz (P < 0.01), respectively, and the variation in dominant frequencies decreased from 1.18, 1.38 and 1.19 to 0.98, 1.11 and 1.02 Hz (P < 0.05) respectively. The results confirmed that the frequencies of 10-30 s VF in ECG vary considerably and continuously, and amiodarone decreases this variation. PMID:17333890

Wang, Ke; Deng, Xiaoyan; Xu, Zaipin; Li, Shugang; Liu, Yan; Guo, Ran; Patwardhan, Abhijit; Leonelli, Fabio

2007-02-01

193

Toward an EEG-based recognition of music liking using time-frequency analysis.  

PubMed

Affective phenomena, as reflected through brain activity, could constitute an effective index for the detection of music preference. In this vein, this paper focuses on the discrimination between subjects' electroencephalogram (EEG) responses to self-assessed liked or disliked music, acquired during an experimental procedure, by evaluating different feature extraction approaches and classifiers to this end. Feature extraction is based on time-frequency (TF) analysis by implementing three TF techniques, i.e., spectrogram, Zhao-Atlas-Marks distribution and Hilbert-Huang spectrum (HHS). Feature estimation also accounts for physiological parameters that relate to EEG frequency bands, reference states, time intervals, and hemispheric asymmetries. Classification is performed by employing four classifiers, i.e., support vector machines, k-nearest neighbors (k -NN), quadratic and Mahalanobis distance-based discriminant analyses. According to the experimental results across nine subjects, best classification accuracy {86.52 (±0.76)%} was achieved using k-NN and HHS-based feature vectors ( FVs) representing a bilateral average activity, referred to a resting period, in ? (13-30 Hz) and ? (30-49 Hz) bands. Activity in these bands may point to a connection between music preference and emotional arousal phenomena. Furthermore, HHS-based FVs were found to be robust against noise corruption. The outcomes of this study provide early evidence and pave the way for the development of a generalized brain computer interface for music preference recognition. PMID:23033323

Hadjidimitriou, Stelios K; Hadjileontiadis, Leontios J

2012-12-01

194

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

195

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

196

Time-Frequency Analysis of Shadow Bands During Recent Solar Eclipses  

NASA Astrophysics Data System (ADS)

The atmospheric phenomenon of shadow bands sometimes visible during total solar eclipses as grey ripples moving over the ground a few minutes before and after the totality was subjected to detailed data analysis Scintillation theory as explanation for this phenomenon given by Codona J L 1986 was tested during three solar eclipses A time-frequency analysis was carried out for three different colour ranges red blue green defined by the CANON Hi8 video camera system as well as for a radio wavelength of 3 cm The geometrically rectified pictures of a white screen with bands carefully oriented north-south were Fourier-analyzed for the considered colour-ranges yielding a catalogue of intensity contour-plots in the two-dimensional spatial frequency-space These stacked contour-plots represent the time-evolution of the shadow bands in the three colour ranges During the solar eclipse of August 11 th 1999 a wavelength of the phenomenon of 20 cm before totality and 25 cm after totality was determined from an Austrian observation point Bad Fischau A similar experimental setup during the eclipse of June 21 st 2001 in Lusaka Sambia resulted in a detectable wavelength of 5 cm before and 10 cm after totality obviously depending on the different altitudes of the scintillation-band producing turbulence layers For the first time an airborne experiment was performed which used three SHARP BS1R 6EL 100W universal LNB commercial satellite receivers together with modified LNB satellite finders The signals were recorded with three 3890 DT USB

Firneis, M. G.; Marx, P. C.; Leitner, J. J.

197

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

NASA Astrophysics Data System (ADS)

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

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

2008-09-01

198

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

199

Single-trial time-frequency analysis of electrocortical signals: baseline correction and beyond.  

PubMed

Event-related desynchronization (ERD) and synchronization (ERS) of electrocortical signals (e.g., electroencephalogram [EEG] and magnetoencephalogram) reflect important aspects of sensory, motor, and cognitive cortical processing. The detection of ERD and ERS relies on time-frequency decomposition of single-trial electrocortical signals, to identify significant stimulus-induced changes in power within specific frequency bands. Typically, these changes are quantified by expressing post-stimulus EEG power as a percentage of change relative to pre-stimulus EEG power. However, expressing post-stimulus EEG power relative to pre-stimulus EEG power entails two important and surprisingly neglected issues. First, it can introduce a significant bias in the estimation of ERD/ERS magnitude. Second, it confuses the contribution of pre- and post-stimulus EEG power. Taking the human electrocortical responses elicited by transient nociceptive stimuli as an example, we demonstrate that expressing ERD/ERS as the average percentage of change calculated at single-trial level introduces a positive bias, resulting in an overestimation of ERS and an underestimation of ERD. This bias can be avoided using a single-trial baseline subtraction approach. Furthermore, given that the variability in ERD/ERS is not only dependent on the variability in post-stimulus power but also on the variability in pre-stimulus power, an estimation of the respective contribution of pre- and post-stimulus EEG variability is needed. This can be achieved using a multivariate linear regression (MVLR) model, which could be optimally estimated using partial least square (PLS) regression, to dissect and quantify the relationship between behavioral variables and pre- and post-stimulus EEG activities. In summary, combining single-trial baseline subtraction approach with PLS regression can be used to achieve a correct detection and quantification of ERD/ERS. PMID:24084069

Hu, L; Xiao, P; Zhang, Z G; Mouraux, A; Iannetti, G D

2014-01-01

200

The time-frequency representation of the ERPs of face processing.  

PubMed

In ERP studies of face processing, N170 and VPP were considered to reflect the structural encoding of faces in many researches. However, whether the VPP is the positive counterpart of the N170 from the same brain source is still a matter of debate. In present study, in order to address the debate we studied the oscillatory activities of event-related potentials (ERPs) during face processing. We recorded the ERPs in response to upright and inverted faces, and analyzed the time-frequency representation (TFR) by using the Smoothed Pseudo Wigner-Ville Distribution (SPWVD). The TFR of ERPs suggests that the oscillations at occipito-temporal sites (T5/T6) where the N170 was observed, were centralized in a higher frequency band (4-10 Hz) while the oscillations at the fronto-central site (Cz) with salient VPP, were more centralized in a lower frequency range(0-5 Hz). Therefore, we concluded that the face-sensitive N170 and VPP, associated with 'the structural encoding' stage of the face processing in Bruce & Young's model, reflect the activities from two different sources. Furthermore, different oscillatory activities were obtained at different face processing stages: 0-10 Hz oscillations around 100-200 ms post-stimulus are involved in face encoding processing, 0-4 Hz oscillations around 300-400 ms post-stimulus are involved in the later face identification and the enhanced activities in response to the inverted faces indicate a higher number of synchronous neuronal populations. PMID:19163617

Tang, Yingying; Liu, Dan; Li, Yingjie; Qiu, Yihong; Zhu, Yisheng

2008-01-01

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

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 ...

203

Abstract--We introduce an adaptive space time frequency analysis to extract and classify subject specific brain oscillations  

E-print Network

specific ERD and ERS patterns. Extracted time-frequency features are processed by principal component, Turkey, (e-mail: arica@cu.edu.tr). and desynchronization (ERD) [1]. The ERD and ERS patterns occur have shown that the ERD and ERS in alpha (7-13Hz) and beta (14-32Hz) bands caused by the MI, as well

Minnesota, University of

204

Modulation domain infrared target models  

Microsoft Academic Search

We compute joint AM-FM models that characterize infrared targets and backgrounds in the modulation domain. We consider spatially localized structures within an IR image as sums of nonstationary, quasi-sinusoidal functions admitting locally narrowband amplitude and frequency modulations. By quantitatively estimating the modulations that dominate the signal spectrum on a spatially local basis, we obtain a new modulation domain feature vector

Joseph P. Havlicek; Chuong T. Nguyen; Mark Yeary

2006-01-01

205

Compliant joint  

NASA Technical Reports Server (NTRS)

A compliant joint is provided for prosthetic and robotic devices which permits rotation in three different planes. The joint provides for the controlled use of cable under motion. Perpendicular outer mounting frames are joined by swaged cables that interlock at a center block. Ball bearings allow for the free rotation of the second mounting frame relative to the first mounting frame within a predetermined angular rotation that is controlled by two stop devices. The cables allow for compliance at the stops and the cables allow for compliance in six degrees of freedom enabling the duplication or simulation of the rotational movement and flexibility of a natural hip or knee joint, as well as the simulation of a joint designed for a specific robotic component for predetermined design parameters.

Eklund, Wayne D. (inventor); Kerley, James J. (inventor)

1990-01-01

206

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

SciTech Connect

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

2014-07-15

207

Time-frequency theta and delta measures index separable components of feedback processing in a gambling task.  

PubMed

Previous work using gambling tasks indicate that the feedback negativity (FN) reflects primary or salient stimulus attributes (often gain vs. loss), whereas the feedback-P300 appears sensitive to secondary stimulus information. A recent time-frequency approach has characterized separable theta (3-7?Hz) and delta (0-3?Hz) feedback processes, independently sensitive to primary feedback attributes, specifically loss and gain outcomes, respectively. The current study extends this time-frequency work to evaluate both primary and secondary (relative outcome and outcome magnitude) feedback attributes. Consistent with previous reports, theta indexed an initial, lower-level response sensitive to the primary (most salient) feedback attributes (specifically losses), while delta was sensitive to both primary attributes (specifically gains) and assessed secondary stimulus features. PMID:25581491

Bernat, Edward M; Nelson, Lindsay D; Baskin-Sommers, Arielle R

2015-05-01

208

Short-Time Frequency Measurement of Narrow-Band Random Signals in the Presence of Wide-Band Noise  

Microsoft Academic Search

In certain applications it is necessary to measure the center frequency of a symmetrical power spectrum in the shortest possible time. Two instrumentations for short-time frequency measurement, the autocorrelator and the frequency discriminator, are examined for their ability to accomplish this task. The analysis compares the performance of the two systems and indicates the effect of such factors as signal-to-noise

Peter M. Schultheiss; Conrad A. Wogrin; Felix Zweig

1954-01-01

209

Time–Frequency and Autoregressive Techniques for Prognostication of Shock-Impact Reliability of Implantable Biological Electronic Systems  

Microsoft Academic Search

In this paper, autoregressive and time-frequency-based techniques have been investigated to predict and monitor the damage in implantable biological electronics such as pacemakers and defibrillators. The approach focuses is on the pre-failure space and methodologies for quantification of failure in electronic equipment subjected to shock and vibration loads using the dynamic response of the electronic equipment. Presented methodologies are applicable

Pradeep Lall; Prashant Gupta; Manish Kulkarni; James Hofmeister

2010-01-01

210

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

211

Joint chondrolysis.  

PubMed

Although the disease was first described in the hip, reports of chondrolysis in nearly all diarthrodial joints have since emerged with considerable variations in the literature.Despite speculation among clinicians and researchers about the implicit causal pathways and etiologic contributors associated with chondrolysis, definitive answers remain elusive.The term chondrolysis has been applied to varied levels of joint cartilage destruction from focal chondral defects to diffuse cartilage loss, revealing a lack of consistency in the application of diagnostic criteria to guide differential disease classification.Differentiating between the various potential etiologies associated with chondrolysis provides opportunities for the prevention of the disease. PMID:22048100

Provencher, Matthew T; Navaie, Maryam; Solomon, Daniel J; Smith, Jessica C; Romeo, Anthony A; Cole, Brian J

2011-11-01

212

Reasoning about Joint Administration of Access Policies for Coalition  

E-print Network

, applications, services Diverse membership Multiple, autonomous domains of security policy administration liabilities or punt implementation to the application layer (w/o a solution) We enforce joint-action via for administration of jointly owned resources minimize trust liabilities #12;Joint Ownership of Coalition Resources

Gligor, Virgil D.

213

Hip joint replacement  

MedlinePLUS

... made joint. The artificial joint is called a prosthesis . ... thromboembolic disease in patients undergoing elective hip and ... joint arthroplasties: current concepts of patient outcomes after ...

214

Time-Frequency Transform Techniques Applied to Ultra-wideband Ground-Penetrating Radar  

NASA Astrophysics Data System (ADS)

Background Recently, Dauvignac et al [1] utilized a ground penetrating radar unit consisting of an exponentially tapered slot antenna (ETSA) of the Vivaldi type, connected to an Agilent vector network analyzer to obtain a densely-sampled profile in the anti-blast tunnel of LSBB (Low-Noise inter-Disciplinary Underground Science & Technology Laboratory) located in Rustrel, France. The frequency data, from 150 MHz to 2 GHz, was inverse Fourier-transformed to obtain the time dependent data. Simultaneously, the same profile was obtained using a RAMAC 500 MHz ground-penetrating radar unit. Initial comparison of both data sets was done in the time-domain. Data obtained from the ETSA will be inverted using a constrained least squares algorithm, in order that the depth-dependent permittivity can be inferred. As a quality control, the RAMAC data will also be inverted. The resulting permittivity profiles obtained in both inversions will be used to image water content over a depth of several meters. Proposed Research It is well-known, qualitatively in the ground penetrating radar literature that high frequencies appear at early times, but generally are attenuated at later times, essentially due to the skin effect. However, a signal-processing verification of this well-known result is needed. We propose to use the Stockwell or S transform [2] to determine the temporal location of frequencies in both of the foregoing datasets. The S transform, a short-time Fourier transform with a frequency-dependent window, will be described and applied to synthetic data. Then the application of the S transform to the RAMAC and ETSA data will be presented, after each data set has undergone the same pre-processing. The S transform is completely linear and preserves the phase of the data, which allows for easy interpretation of the operations of filtering, due to the linear inverse of the forward S transform. Thus the S transform is ideal for comparing the temporal distribution of frequency in these two datasets. BIBLIOGRAPHY [1] DAUVIGNAC J.-Y., N. FORTINO, G. SENECHAL, A. CRESP, M. YEDLIN, S. GAFFET, D. ROUSSET, and C. PICHOT, "Ultra-Wideband GPR Imaging of the Vaucluse Karst Aquifer", American Geophysical Union, Fall Meeting 2008, Abstract #NS51A-08. [2] STOCKWELL R. G., L. MANSINHA, R. P. LOWE, "Localization of the complex spectrum: the S transform", IEEE Transactions on Signal Processing, vol.44, n°4, pp 998-1001, April 1996.

Yedlin, M.; Cresp, A.; Dauviganc, J. Y.; Gaffet, S.; Sénéchal, G.; Fortino, N.; Pichot, C.; Aliferis, I.

2009-04-01

215

Joint assembly  

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

216

Experimental validation of a signal-based approach for structural earthquake damage detection using fractal dimension of time frequency feature  

NASA Astrophysics Data System (ADS)

This article extends a signal-based approach formerly proposed by the authors, which utilizes the fractal dimension of time frequency feature (FDTFF) of displacements, for earthquake damage detection of moment resist frame (MRF), and validates the approach with shaking table tests. The time frequency feature (TFF) of the relative displacement at measured story is defined as the real part of the coefficients of the analytical wavelet transform. The fractal dimension (FD) is to quantify the TFF within the fundamental frequency band using box counting method. It is verified that the FDTFFs at all stories of the linear MRF are identical with the help of static condensation method and modal superposition principle, while the FDTFFs at the stories with localized nonlinearities due to damage will be different from those at the stories without nonlinearities using the reverse-path methodology. By comparing the FDTFFs of displacements at measured stories in a structure, the damage-induced nonlinearity of the structure under strong ground motion can be detected and localized. Finally shaking table experiments on a 1:8 scale sixteen-story three-bay steel MRF with added frictional dampers, which generate local nonlinearities, are conducted to validate the approach.

Tao, Dongwang; Mao, Chenxi; Zhang, Dongyu; Li, Hui

2014-12-01

217

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

218

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.

219

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

220

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

E-print Network

T)), where n = 60 is the pulse length measured in optical cycles (T = 2?/?0), ?0 ? 0.0428278 in atomic units (a.u.) corresponds to laser wavelength 1064 nm, and E0 ? 0.0169 in a.u. corresponds to the laser intensity of I0 = 1013 W/cm2. Figure 1(b) presents...AIP ADVANCES 4, 117138 (2014) A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform Yae-lin Sheu,1 Liang-Yan Hsu,2,a Hau-tieng Wu,3,b Peng-Cheng Li,1,4 and Shih-I Chu1,5,c 1...

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

2014-11-26

221

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

222

A time-frequency analysis of the dynamics of cortical networks of sleep spindles from MEG-EEG recordings  

PubMed Central

Sleep spindles are a hallmark of NREM sleep. They result from a widespread thalamo-cortical loop and involve synchronous cortical networks that are still poorly understood. We investigated whether brain activity during spindles can be characterized by specific patterns of functional connectivity among cortical generators. For that purpose, we developed a wavelet-based approach aimed at imaging the synchronous oscillatory cortical networks from simultaneous MEG-EEG recordings. First, we detected spindles on the EEG and extracted the corresponding frequency-locked MEG activity under the form of an analytic ridge signal in the time-frequency plane (Zerouali et al., 2013). Secondly, we performed source reconstruction of the ridge signal within the Maximum Entropy on the Mean framework (Amblard et al., 2004), yielding a robust estimate of the cortical sources producing observed oscillations. Lastly, we quantified functional connectivity among cortical sources using phase-locking values. The main innovations of this methodology are (1) to reveal the dynamic behavior of functional networks resolved in the time-frequency plane and (2) to characterize functional connectivity among MEG sources through phase interactions. We showed, for the first time, that the switch from fast to slow oscillatory mode during sleep spindles is required for the emergence of specific patterns of connectivity. Moreover, we show that earlier synchrony during spindles was associated with mainly intra-hemispheric connectivity whereas later synchrony was associated with global long-range connectivity. We propose that our methodology can be a valuable tool for studying the connectivity underlying neural processes involving sleep spindles, such as memory, plasticity or aging. PMID:25389381

Zerouali, Younes; Lina, Jean-Marc; Sekerovic, Zoran; Godbout, Jonathan; Dube, Jonathan; Jolicoeur, Pierre; Carrier, Julie

2014-01-01

223

Joint Instability and Osteoarthritis  

PubMed Central

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

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

2015-01-01

224

Concrete Domains   

E-print Network

This paper introduces the theory of a particular kind of computation domains called concrete domains. The purpose of this theory is to find a satisfactory framework for the notions of coroutine computation and sequentiality ...

Kahn, Gilles; Plotkin, Gordon

1993-01-01

225

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

NASA Technical Reports Server (NTRS)

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

Weng, Hengyi; Lau, K.-M.

1994-01-01

226

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

PubMed

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

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

2015-03-01

227

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

PubMed

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

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

2015-04-01

228

Auditory and Nociceptive Stimuli Responses in the Electroencephalogram. A Non-linear Measures and Time-frequency Representation Based Analysis.  

PubMed

Introduction: This article is part of the Focus Theme of Methods of Information in Medicine on "Biosignal Interpretation: Advanced Methods for Neural Signals and Images". Objectives: An efficient way to investigate the neural basis of nociceptive responses is the analysis of the event-related brain potentials (ERPs). The main objective of this work was to study how adaptation and fatigue affect the ERPs to stimuli of different modalities, by characterizing the responses to infrequent and frequent stimulation in different recording periods. Methods: In this work, series of averaged EEG epochs recorded after thermal, electrical and auditory stimulation were analyzed with time-frequency representation and non-linear measures as spectral entropy and auto-mutual information function. The study was performed by considering the traditional EEG frequency bands. Results: The defined measures presented a statistical significance p-value

Melia, U; Vallverdú, M; Clariá, F; Valls-Solé, J; Caminal, P

2014-05-01

229

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

PubMed Central

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

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

2014-01-01

230

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

PubMed

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

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

2015-03-01

231

Time-frequency analysis of short-lasting modulation of EEG induced by TMS during wake, sleep deprivation and sleep  

PubMed Central

The occurrence of dynamic changes in spontaneous electroencephalogram (EEG) rhythms in the awake state or sleep is highly variable. These rhythms can be externally modulated during transcranial magnetic stimulation (TMS) with a perturbation method to trigger oscillatory brain activity. EEG-TMS co-registration was performed during standard wake, during wake after sleep deprivation and in sleep in six healthy subjects. Dynamic changes in the regional neural oscillatory activity of the cortical areas were characterized using time-frequency analysis based on the wavelet method, and the modulation of induced oscillations were related to different vigilance states. A reciprocal synchronizing/desynchronizing effect on slow and fast oscillatory activity was observed in response to focal TMS after sleep deprivation and sleep. We observed a sleep-related slight desynchronization of alpha mainly over the frontal areas, and a widespread increase in theta synchronization. These findings could be interpreted as proof of the interference external brain stimulation can exert on the cortex, and how this could be modulated by the vigilance state. Potential clinical applications may include evaluation of hyperexcitable states such as epilepsy or disturbed states of consciousness such as minimal consciousness. PMID:24302903

Manganotti, Paolo; Formaggio, Emanuela; Del Felice, Alessandra; Storti, Silvia F.; Zamboni, Alessandro; Bertoldo, Alessandra; Fiaschi, Antonio; Toffolo, Gianna M.

2013-01-01

232

Proprioception and joint stability  

Microsoft Academic Search

In the present paper the current clinical knowledge about proprioception is given for the shoulder, knee, ankle, elbow and the radiocarpal joint. Proprioceptive capabilities are decreased after joint injuries such as ACL or meniscus tears, shoulder dislocation, ankle sprain and in joints with degenerative joint disease. Some surgical procedures seem to restore the proprioceptive abilities; others do not. Elastic knee

J. Jerosch; M. Prymka

1996-01-01

233

Joint Infection (Beyond the Basics)  

MedlinePLUS

... Infection of an artificial joint is known as prosthetic joint infection. GONOCOCCAL JOINT INFECTION Gonococcal joint infection ... cases, it is not possible to replace the prosthetic joint, and surgery to fuse the bones is ...

234

Decoding a bistable percept with integrated time-frequency representation of single-trial local field potential  

NASA Astrophysics Data System (ADS)

Bistable perception emerges when a stimulus under continuous view is perceived as the alternation of two mutually exclusive states. Such a stimulus provides a unique opportunity for understanding the neural basis of visual perception because it dissociates the perception from the visual input. In this paper we analyze the dynamic activity of local field potential (LFP), simultaneously collected from multiple channels in the middle temporal (MT) visual cortex of a macaque monkey, for decoding its bistable structure-from-motion (SFM) perception. Based on the observation that the discriminative information of neuronal population activity evolves and accumulates over time, we propose to select features from the integrated time-frequency representation of LFP using a relaxation (RELAX) algorithm and a sequential forward selection (SFS) algorithm with maximizing the Mahalanobis distance as the criterion function. The integrated-spectrogram based feature selection is much more robust and can achieve significantly better features than the instantaneous-spectrogram based feature selection. We exploit the support vector machines (SVM) classifier and the linear discriminant analysis (LDA) classifier based on the selected features to decode the reported perception on a single trial basis. Our results demonstrate the excellent performance of the integrated-spectrogram based feature selection and suggest that the features in the gamma frequency band (30-100 Hz) of LFP within specific temporal windows carry the most discriminative information for decoding bistable perception. The proposed integrated-spectrogram based feature selection approach may have potential for a myriad of applications involving multivariable time series such as brain-computer interfaces (BCI).

Wang, Zhisong; Logothetis, Nikos K.; Liang, Hualou

2008-12-01

235

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

236

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

237

Heart Rate Variability Analysis of Ischemic and Heart Rate Related ST-segment Deviation Episodes Based on Time-frequency Method  

Microsoft Academic Search

ST-segment deviation is the routine method for the diagnosis of coronary heart diseases. However, other phenomena, such as heart rate changes and a posture change can cause similar manifestations in the ST segment, lowing the sensitivity and specificity of the detection. In this study, a different method, based on time-frequency analysis of heart rate variability, was proposed to evaluate the

Wang Xing; Xu Liang; Sun Zhongwei; Yang Zibin; Peng Yi

2007-01-01

238

Butt Joint Tool Commissioning  

SciTech Connect

ITER Central Solenoid uses butt joints for connecting the pancakes in the CS module. The principles of the butt joining of the CICC were developed by the JAPT during CSMC project. The difference between the CSMC butt joint and the CS butt joint is that the CS butt joint is an in-line joint, while the CSMC is a double joint through a hairpin jumper. The CS butt joint has to carry the hoop load. The straight length of the joint is only 320 mm, and the vacuum chamber around the joint has to have a split in the clamp shell. These requirements are challenging. Fig.1 presents a CSMC joint, and Fig.2 shows a CS butt joint. The butt joint procedure was verified and demonstrated. The tool is capable of achieving all specified parameters. The vacuum in the end was a little higher than the target, which is not critical and readily correctable. We consider, tentatively that the procedure is established. Unexpectedly, we discover significant temperature nonuniformity in the joint cross section, which is not formally a violation of the specs, but is a point of concern. All testing parameters are recorded for QA purposes. We plan to modify the butt joining tool to improve its convenience of operation and provide all features necessary for production of butt joints by qualified personnel.

Martovetsky, N N

2007-12-06

239

Risk Management Institute Joint Seminar Joint Seminar -  

E-print Network

around their use of leverage. Research on optimal leverage in the money management industry, howeverRisk Management Institute Joint Seminar Joint Seminar - Risk Management Institute And Department A (S14, #03-10) Speaker Prof. Wang Hefei University of Illinois, Chicago Title Leverage Management

Chaudhuri, Sanjay

240

Interval Polyhedra Domain Applications  

E-print Network

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

Miné, Antoine

241

Kalman filter methods for real-time frequency and mode number estimation of MHD activity in tokamak plasmas  

NASA Astrophysics Data System (ADS)

Magnetohydrodynamic (MHD) activity in magnetically confined fusion experiments is often associated with detrimental effects such as increased radial transport and consequent loss of confinement. In particular, the (2,1) neoclassical tearing mode (NTM), when proceeding to mode-locking, is a potentially disruptive instability hence with the potential to compromise the mechanical integrity of the machine. It is therefore quite significant to be able to characterize in real-time the most virulent and performance limiting instabilities such that adequate mitigation or complete stabilization using feedback control methods are employed during the plasma discharge. This work proposes a Kalman filter (KF) based mechanism for providing, in real-time, the amplitude and phase evolution of instabilities within a predefined set of mode numbers. The method relies on two KF implementations: a non-linear KF isolating the non-stationary dominant signal component of a sensor measurement and subsequently a linear KF which projects the former, for a collection of sensors, onto a predefined set of mode numbers. A basic overview of algorithms commonly used for real-time mode number analysis is also presented along with applications of the proposed algorithm to recently recorded data of the Joint European Torus (JET) tokamak.

Alves, D.; Coelho, R.; JET EFDA contributors, the

2013-10-01

242

Grouping Separated Frequency Components by Estimating Propagation Model Parameters in Frequency-Domain Blind Source Separation  

Microsoft Academic Search

This paper proposes a new formulation and optimization procedure for grouping frequency components in frequency-domain blind source separation (BSS). We adopt two separation techniques, independent component analysis (ICA) and time-frequency (T-F) masking, for the frequency-domain BSS. With ICA, grouping the frequency components corresponds to aligning the permutation ambiguity of the ICA solution in each frequency bin. With T-F masking, grouping

Hiroshi Sawada; Shoko Araki; Ryo Mukai; Shoji Makino

2007-01-01

243

Temporomandibular joint dislocation.  

PubMed

Dislocation of the temporomandibular joint is one of many pathophysiologic joint conditions that the oral and maxillofacial surgeon is challenged with managing. Managing a dislocated joint will inevitably be the challenge of most surgeons or physicians, whether in private or academic practice. Accordingly, this article addresses the pathophysiology associated with dislocation, in addition to treatment strategies aimed at managing acute, chronic, and recurrent dislocation. PMID:25483448

Liddell, Aaron; Perez, Daniel E

2015-02-01

244

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

SciTech Connect

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

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

2012-08-22

245

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

USGS Publications Warehouse

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

2012-01-01

246

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

247

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

248

Campylobacter Prosthetic Joint Infection  

PubMed Central

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

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

2014-01-01

249

Behavior of jointed pipelines  

Microsoft Academic Search

Experimental data on the axial, bending and torsional behavior of ductile cast iron pipes with rubber gasket joints is presented. Analytical expressions are provided which predict the resistance mechanisms and behavior of the joints. The bending mechanism is found to be quite different from the axial and torsional mechanism. By repeating the tests in a specially designed soil box, the

Singhal

1984-01-01

250

Wedge Joints for Trusses  

NASA Technical Reports Server (NTRS)

Structure assembled rapidly with simple hand tools. Proposed locking wedge joints enable rapid assembly of lightweight beams, towers, scaffolds, and other truss-type structures. Lightweight structure assembled from tubular struts joined at nodes by wedge pins fitting into mating slots. Joint assembled rapidly by seating wedge pin in V-shaped slots and deforming end of strut until primary pawl engages it.

Wood, Kenneth E.

1987-01-01

251

Strategies for joint appointments.  

PubMed

The structure and policies governing joint appointments discussed above, are developed primarily through cooperation and collaboration between nursing service and education institutions. The joint appointee participates in the process of negotiation of salary, benefits and role responsibilities and exploration of the implications of the appointment for personal career development. Implementation and maintenance of the appointment requires the collaborative efforts of the joint appointee with both contracting agencies. Factors influencing the functioning of joint appointees have been identified and strategies to facilitate functioning presented. The joint appointee must be independent in thought and action yet adaptable to work within the boundaries of two social systems with differing values and expectations. Nursing management, peers and students can provide the support needed to overcome the frustrations and to achieve the rewards inherent in successful implementation of an exciting and innovative role. PMID:3852805

Royle, J; Crooks, D L

1985-01-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

253

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

PubMed

To study cell-field dynamics, physiologists simultaneously record local field potentials and the activity of individual cells from animals performing cognitive tasks, during various brain states or under pathological conditions. However, apart from spike shape and spike timing analyses, few studies have focused on elucidating the common time-frequency structure of local field activity relative to surrounding cells across different periods of phenomena. We have used two algorithms, multi-window time frequency analysis and wavelet phase coherence (WPC), to study common intracellular-extracellular (I-E) spectral features in spontaneous seizure-like events (SLEs) from rat hippocampal slices in a low magnesium epilepsy model. Both algorithms were applied to 'pairs' of simultaneously observed I-E signals from slices in the CA1 hippocampal region. Analyses were performed over a frequency range of 1-100 Hz. I-E spectral commonality varied in frequency and time. Higher commonality was observed from 1 to 15 Hz, and lower commonality was observed in the 15-100 Hz frequency range. WPC was lower in the non-SLE region compared to SLE activity; however, there was no statistical difference in the 30-45 Hz band between SLE and non-SLE modes. This work provides evidence of strong commonality in various frequency bands of I-E SLEs in the rat hippocampus, not only during SLEs but also immediately before and after. PMID:21712570

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

2011-08-01

254

[Age-related changes in time-frequency structure of sleep spindles in EEG in rats with genetic predisposition to absence epilepsy (Wag/Rij)].  

PubMed

It is known that sleep spindles are produced by thalamo-cortical system spontaneously during the slow-wave sleep; pathological processes in thalamo-cortical network might cause absence epilepsy. The aim of this study was to examine age-dependent changes in time-frequency structure of sleep spindles in parallel to a progressive increase in amount of absence seizures in WAG/Rij rat model. EEG was consistently recorded at the age of 5, 7 and 9 months by means of epidural electrodes implanted in the frontal cortex. Continuous wavelet transform was used for automatic identification and further time-frequency analysis of sleep spindles in EEG. It was found that the mean duration of epileptic discharges and total duration of epileptic activity increased with age, whereas the length of sleep spindles decreased. Mean frequency of oscillations within a spindle was used as a criterion for dividing sleep spindles in three categories: "slow" (9.3 Hz), "tr ansitional" (11.4 Hz) and "fast" (13.5 Hz). "Slow" and "transitional" spindles in 5-months animals displayed an increase in frequency from the beginning towards the end. It was shown that the higher incidence of epilepsy corresponded to the lower duration of sleep spindles (all types). Mean frequency of "transitional" and "fast" spindles was higher in rats with more intensive epileptic discharges. In general, high epileptic activity in WAG/Rij rats corresponded to the most substantial changes within "transitional" spindles, whereas changes within slow and fast spindles were moderate. PMID:23530451

Sitnikova, E Iu; Grubov, V V; Khramov, A E; Koronovski?, A A

2012-01-01

255

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

256

BUILDING MODEL ANALYSIS APPLICATIONS WITH THE JOINT UNIVERSAL PARAMETER IDENTIFICATION AND EVALUATION OF RELIABILITY (JUPITER) API  

EPA Science Inventory

The open-source, public domain JUPITER (Joint Universal Parameter IdenTification and Evaluation of Reliability) API (Application Programming Interface) provides conventions and Fortran-90 modules to develop applications (computer programs) for analyzing process models. The input ...

257

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

258

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

259

Culture - joint fluid  

MedlinePLUS

Joint fluid culture ... fungi, or viruses grow. This is called a culture. If such microorganisms are detected, other tests may ... is no special preparation needed for the lab culture. For information on preparing for the removal of ...

260

Healthy Joints Matter  

MedlinePLUS

... caused by a buildup of uric acid (YOOR-ic acid) crystals in the joints, most commonly in ... form of arthritis called psoriatic (sore-ee-AT-ic) arthritis. Rheumatoid arthritis (ROO-muh-toid ar-THRY- ...

261

Optimization of bonded joints  

NASA Technical Reports Server (NTRS)

A procedure for minimizing the elastic shear stress concentration in adhesive lap joints is presented. The proposed method is based upon tapering the adherends to achieve smooth stiffness transitions and uniform shear stresses. Both single and double lap splices are considered, but numerical examples are restricted to the case of double lap joints. Nonisotropic materials and nonoptimum design limitations, such as minimum and maximum thickness adherends, load-line eccentricity, and peel stresses are treated, and typical results are presented.

Ojalvo, I. U.

1983-01-01

262

Joint Contact Stress  

PubMed Central

A joint's normal mechanical history contributes to the maintenance of articular cartilage and underlying bone. Loading facilitates the flow of nutrients into cartilage and waste products away, and additionally provides the mechanical signals essential for normal cell and tissue maintenance. Deleteriously low or high contact stresses have been presumed to result in joint deterioration, and particular aspects of the mechanical environment may facilitate repair of damaged cartilage. For decades, investigators have explored static joint contact stresses (under some more or less arbitrary condition) as a surrogate of the relevant mechanical history. Contact stresses have been estimated in vitro in many joints and in a number of species, although only rarely in vivo. Despite a number of widely varying techniques (and spatial resolutions) to measure these contact stresses, reported ranges of static peak normal stresses are relatively similar from joint to joint across species, and in the range of 0.5 to 5.0 MPa. This suggests vertebrate diarthrodial joints have evolved to achieve similar mechanical design criteria. Available evidence also suggests some disorders of cartilage deterioration are associated with somewhat higher peak pressures ranging from 1-20 MPa, but overlapping the range of normal pressures. Some evidence and considerable logic suggests static contact stresses per se do not predict cartilage responses, but rather temporal aspects of the contact stress history. Static contact stresses may therefore not be a reasonable surrogate for biomechanical studies. Rather, temporal and spatial aspects of the loading history undoubtedly induce beneficial and deleterious biological responses. Finally, since all articular cartilage experiences similar stresses, the concept of a "weight-bearing" versus a "non-weight-bearing" joint seems flawed, and should be abandoned. PMID:16089079

Brand, Richard A

2005-01-01

263

Joint hypermobility syndrome pain  

Microsoft Academic Search

Joint hypermobility syndrome (JHS) was initially defined as the occurrence of musculoskeletal symptoms in the presence of\\u000a joint laxity and hypermobility in otherwise healthy individuals. It is now perceived as a commonly overlooked, underdiagnosed,\\u000a multifaceted, and multisystemic heritable disorder of connective tissue (HDCT), which shares many of the phenotypic features\\u000a of other HDCTs such as Marfan syndrome and Ehlers-Danlos syndrome.

Rodney Grahame

2009-01-01

264

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

265

A method for updating joint parameters in medium-frequency vibrations  

E-print Network

analyzes the effectiveness of the approach in identifying a joint's stiffness and damping. RÃ?SUMÃ?. Les. KEYWORDS: medium frequency, joints, damping, updating, VTCR, inverse problem, domain de- composition frequencies present major difficulties because of their high modal density and their high sensitivity

266

Time, Frequency and Physical Measurement.  

ERIC Educational Resources Information Center

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

Hellwig, Helmut; And Others

1978-01-01

267

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

268

Acromioclavicular Joint Injuries  

PubMed Central

Objective: To discuss the anatomy and biomechanics of the acromioclavicular (AC) joint, along with the clinical evaluation and treatment of an athlete with an AC joint injury. Data Sources: I searched MEDLINE from 1970 through 1999 under the key words “acromioclavicular joint,” “clavicle,” “acromioclavicular separation,” and “acromioclavicular dislocation.” Knowledge base was an additional source. Data Synthesis: AC joint injury is common in athletes and a source of significant morbidity, particularly for athletes in overhead sports. Because this injury can masquerade as other shoulder conditions, the examiner must understand the anatomy and biomechanics of the shoulder in order to perform a systematic clinical evaluation and identify the injury. Conclusions/Recommendations: Careful attention to the clinical evaluation allows the clinician to categorize the athlete's AC joint injury and institute appropriate treatment in a timely fashion, thus permitting the athlete to return to sport as quickly and safely as possible. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7. PMID:16558638

Beim, Gloria M.

2000-01-01

269

Distal radioulnar joint injuries  

PubMed Central

Distal radioulnar joint is a trochoid joint relatively new in evolution. Along with proximal radioulnar joint, forearm bones and interosseous membrane, it allows pronosupination and load transmission across the wrist. Injuries around distal radioulnar joint are not uncommon, and are usually associated with distal radius fractures,fractures of the ulnar styloid and with the eponymous Galeazzi or Essex_Lopresti fractures. The injury can be purely involving the soft tissue especially the triangular fibrocartilage or the radioulnar ligaments. The patients usually present with ulnar sided wrist pain, features of instability, or restriction of rotation. Difficulty in carrying loads in the hand is a major constraint for these patients. Thorough clinical examination to localize point of tenderness and appropriate provocative tests help in diagnosis. Radiology and MRI are extremely useful, while arthroscopy is the gold standard for evaluation. The treatment protocols are continuously evolving and range from conservative, arthroscopic to open surgical methods. Isolated dislocation are uncommon. Basal fractures of the ulnar styloid tend to make the joint unstable and may require operative intervention. Chronic instability requires reconstruction of the stabilizing ligaments to avoid onset of arthritis. Prosthetic replacement in arthritis is gaining acceptance in the management of arthritis. PMID:23162140

Thomas, Binu P; Sreekanth, Raveendran

2012-01-01

270

Robotic Bladder Joint  

NASA Technical Reports Server (NTRS)

Reliable, lightweight robotic joint suitable for variety of applications, actuated hydraulically, without need for heavy mechanical cylinders or gears on joint itself. Includes two members; first member rotates about pin at end of second member. Includes cam, over which tension line stretched. Ends of tension line anchored at end of second member opposite end that holds pin. Bladder placed on each side of second member, squeezed between second member and tension line. Pressures and/or amounts of fluid in bladders controlled by use of conventional equipment like pumps, valves, and reservoirs. Bladder on one side inflated more than on other side; greater inflation on one side causes greater stretching of tension line on that side. Greater tension pulls on cam, turning first member toward that side. Angle of joint controlled by controlling differential inflation of two bladders.

Robertson, Glen A.

1995-01-01

271

Quick acting gimbal joint  

NASA Technical Reports Server (NTRS)

The present invention relates to an adjustable linkage assembly for selectively retaining the position of one member pivotable with respect to another member. More specifically, the invention relates to a linkage assembly commonly referred to as a gimbal joint, and particularly to a quick release or quick acting gimbal joint. The assembly is relatively simple in construction, compact in size, and has superior locking strength in any selected position. The device can be quickly and easily actuated, without separate tooling, by inexperienced personnel or by computer controlled equipment. It also is designed to prevent inadvertent actuation.

Wood, William B. (inventor); Krch, Gary D. (inventor)

1993-01-01

272

Joint for deployable structures  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

273

Prosthetic Joint Infection  

PubMed Central

SUMMARY Prosthetic joint infection (PJI) is a tremendous burden for individual patients as well as the global health care industry. While a small minority of joint arthroplasties will become infected, appropriate recognition and management are critical to preserve or restore adequate function and prevent excess morbidity. In this review, we describe the reported risk factors for and clinical manifestations of PJI. We discuss the pathogenesis of PJI and the numerous microorganisms that can cause this devastating infection. The recently proposed consensus definitions of PJI and approaches to accurate diagnosis are reviewed in detail. An overview of the treatment and prevention of this challenging condition is provided. PMID:24696437

Tande, Aaron J.

2014-01-01

274

Prosthetic joint infection.  

PubMed

Prosthetic joint infection (PJI) is a tremendous burden for individual patients as well as the global health care industry. While a small minority of joint arthroplasties will become infected, appropriate recognition and management are critical to preserve or restore adequate function and prevent excess morbidity. In this review, we describe the reported risk factors for and clinical manifestations of PJI. We discuss the pathogenesis of PJI and the numerous microorganisms that can cause this devastating infection. The recently proposed consensus definitions of PJI and approaches to accurate diagnosis are reviewed in detail. An overview of the treatment and prevention of this challenging condition is provided. PMID:24696437

Tande, Aaron J; Patel, Robin

2014-04-01

275

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.

276

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

277

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

278

Time-frequency characterization of electrocorticographic recordings of epileptic patients using frequency-entropy similarity: a comparison to other bi-variate measures.  

PubMed

Expert evaluation of electrocorticographic (ECoG) recordings forms the linchpin of seizure onset zone localization in the evaluation of epileptic patients for surgical resection. Numerous methods have been developed to analyze these complex recordings, including uni-variate (characterizing single channels), bi-variate (comparing channel pairs) and multivariate measures. Developing reliable algorithms may be helpful in clinical tasks such as localization of epileptogenic zones and seizure anticipation, as well as enabling better understanding of neuronal function and dynamics. Recently we have developed the frequency-entropy (F-E) similarity measure, and have tested its capability in mapping the epileptogenic zones. The F-E similarity measure compares time-frequency characterizations of two recordings. In this study, we examine the method's principles and utility and compare it to previously described bi-variate correspondence measures such as correlation, coherence, mean phase coherence and spectral comparison methods. Specially designed synthetic signals were used for illuminating theoretical differences between the measures. Intracranial recordings of four epileptic patients were then used for the measures' comparative analysis by creating a mean inter-electrode matrix for each of the correspondence measures and comparing the structure of these matrices during the inter-ictal and ictal periods. We found that the F-E similarity measure is able to discover spectral and temporal features in data which are hidden for the other measures and are important for foci localization. PMID:20969891

Gazit, T; Doron, I; Sagher, O; Kohrman, M H; Towle, V L; Teicher, M; Ben-Jacob, E

2011-01-15

279

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

280

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

281

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.

Juliet Crider

282

CARTILAGE, BONES, AND JOINTS  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

283

Evolving flexible joint morphologies  

Microsoft Academic Search

Transferring virtual robotic designs into physical robots has become possible with the development of 3D printers. Accurately simulating the performance of real robots in a virtual environment requires modeling a variety of conditions, including the physical composition of the robots themselves. In this paper, we investigate how modeling material flexibility through the use of a passive joint affects the resulting

Jared M. Moore; Philip K. McKinley

2012-01-01

284

Biologics — beyond the joints  

Microsoft Academic Search

Biologics including tumor necrosis factor ? (TNF-?), interleukin-6 receptor (IL-6R), T and B cell inhibitors are very effective therapeutic agents for the treatment of arthritides. These compounds effectively improve articular symptoms and inhibit joint damage. In this respect, there are no major differences in the efficacy of the available biologics. However, many arthritis patients also exert extra-articular features, systemic manifestations

Zoltán Szekanecz; Sándor Szántó; Zoltán Szabó; Andrea Váncsa; Szilvia Szamosi; Nóra Bodnár; Gabriella Szücs

2010-01-01

285

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

286

LARP Joint IR studies  

E-print Network

LARP initiated Joint IR Studies (JIRS) in October 2007 (FY2008) to coordinate efforts related to the LHC Phase I and II upgrades previously situated either in Accelerator Systems or in Magnet Systems. This note outlines JIRS goals, main directions and milestones.

Zlobin, A V

2008-01-01

287

Dual-Eccentric Clevis Joint  

NASA Technical Reports Server (NTRS)

Redesigned clevis joint incorporates dual mating eccentric cylindrical bushings to accommodate dimensional tolerances. Eliminates need for combination of oppositely threaded collar and bushing and makes overall joint hardware fit within available space.

Fairbank, Diana L.; Sertich, John J.

1996-01-01

288

Determination of Parachute Joint Factors using Seam and Joint Testing  

NASA Technical Reports Server (NTRS)

This paper details the methodology for determining the joint factor for all parachute components. This method has been successfully implemented on the Capsule Parachute Assembly System (CPAS) for the NASA Orion crew module for use in determining the margin of safety for each component under peak loads. Also discussed are concepts behind the joint factor and what drives the loss of material strength at joints. The joint factor is defined as a "loss in joint strength...relative to the basic material strength" that occurs when "textiles are connected to each other or to metals." During the CPAS engineering development phase, a conservative joint factor of 0.80 was assumed for each parachute component. In order to refine this factor and eliminate excess conservatism, a seam and joint testing program was implemented as part of the structural validation. This method split each of the parachute structural joints into discrete tensile tests designed to duplicate the loading of each joint. Breaking strength data collected from destructive pull testing was then used to calculate the joint factor in the form of an efficiency. Joint efficiency is the percentage of the base material strength that remains after degradation due to sewing or interaction with other components; it is used interchangeably with joint factor in this paper. Parachute materials vary in type-mainly cord, tape, webbing, and cloth -which require different test fixtures and joint sample construction methods. This paper defines guidelines for designing and testing samples based on materials and test goals. Using the test methodology and analysis approach detailed in this paper, the minimum joint factor for each parachute component can be formulated. The joint factors can then be used to calculate the design factor and margin of safety for that component, a critical part of the design verification process.

Mollmann, Catherine

2015-01-01

289

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

290

Cellular Pressure-Actuated Joint  

NASA Technical Reports Server (NTRS)

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

McGuire, John R.

2003-01-01

291

Joint Seminar Risk Management Institute &  

E-print Network

Joint Seminar Risk Management Institute & Department of Mathematics Details of Seminar Date empirical phenomena of the negative variance risk premium and implied volatility smirk if market into account. This is a joint work with Eric C. Chang and Huimin Zhao. Risk Management Institute Joint Seminar

Chaudhuri, Sanjay

292

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

293

Phase 1 Program Joint Report  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

294

Economical Joint for Truss Structures  

NASA Technical Reports Server (NTRS)

Mass-produced flat parts easily assembled. Joint for three-dimensional truss made of simple die-cutplates and inexpensive fasteners. Each truss joint consists of two identical interlocking plates bolted, welded, or glued together. Truss struts bolted to joint through holes in plate. Alternatively, ends of struts forked so that they slip over plates and fastened to them by bolts or pins.

Moore, Carleton J.

1987-01-01

295

The Challenges of Joint Attention  

Microsoft Academic Search

This paper discusses the concept of joint at- tention and the dierent skills underlying its development. We argue that joint attention is much more than gaze following or simul- taneous looking because it implies a shared intentional relation to the world. The current state-of-the-art in robotic and computational models of the dierent prerequisites of joint attention is discussed in relation

Frederic Kaplan; Verena V. Hafner

2004-01-01

296

Heterogeneous domain adaptation and classification by exploiting the correlation subspace.  

PubMed

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

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

2014-05-01

297

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

298

49 CFR 213.121 - Rail joints.  

Code of Federal Regulations, 2014 CFR

...Transportation 4 2014-10-01 2014-10-01 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...

2014-10-01

299

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

300

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

301

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

302

Improved high-temperature gimbal joint  

NASA Technical Reports Server (NTRS)

Development and characteristics of bellows gimbal joint for reduction of thermal stress effects are discussed. Reactions of designed joint to changes in temperature are described. Illustrations of conventional gimbal joint and improved gimbal joint are provided.

Winemiller, J. R.; Yee, S. T.; Neal, B. H.

1972-01-01

303

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2014 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2014-01-01

304

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2012 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2012-01-01

305

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2010 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2010-01-01

306

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2010 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2010-01-01

307

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2012 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2012-01-01

308

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2011 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2011-01-01

309

14 CFR 29.935 - Shafting joints.  

Code of Federal Regulations, 2013 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 29.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2013-01-01

310

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2013 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2013-01-01

311

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2011 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2011-01-01

312

14 CFR 27.935 - Shafting joints.  

Code of Federal Regulations, 2014 CFR

...ROTORCRAFT Powerplant Rotor Drive System § 27.935 Shafting joints. Each universal joint, slip joint, and other shafting joints whose lubrication is necessary for operation must have provision for...

2014-01-01

313

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

314

Formation of tough composite joints  

SciTech Connect

Joints which exhibit tough fracture behavior were formed in a composite with a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. In composites with BN coatings fibers were aligned uniaxially, while composites with Si{sub 3}N{sub 4}-coated fibers had a 0/90{degree} architecture. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure have been proposed. Joints with a simple overlap geometry (only a few fingers) would have to be very long in order to prevent brittle failure. Typical failure in these joints is caused by a crack propagating along the interfaces between the joint fingers. Joints of the same overall length, but with geometry changed to be symmetric about the joint centerline and with an extra shear surface exhibited tough fractures accompanied with extensive fiber pullout. The initial matrix cracking of these joints was relatively low because cracks propagated easily through the ends of the fingers. Joints with an optimized stepped sawtooth geometry produced composite-like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength from 9 to 25 MPa, by changing the fiber coating, increased matrix cracking and ultimate strength of the composite significantly. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints will permit building of structures containing joints with only a minor reduction of design stresses.

Brun, M.K. [GE Corporate Research and Development, Schenectady, NY (United States)

1997-05-01

315

Preliminary bolted-joint data  

NASA Technical Reports Server (NTRS)

Bolted-joint strength and failure modes for advanced graphite/polyimide composite laminates at 116K (-250 F), room temperature, and 589K (600 F) were determined to provide preliminary design data. The bolted-joint test setup for the low and elevated temperature tests is described. Test results are reported on a quasi-isotropic laminate of Celion 6000/PMR-15. Single bolt, double lap shear specimens were tested to obtain maximum joint strength and failure mode. The effect of joint geometry and temperature on joint strength and failure mode is presented.

Wichorek, G. R.

1979-01-01

316

Domain specific embedded compilers  

Microsoft Academic Search

Domain-specific embedded languages (DSELs) expressedin higher-order, typed (HOT) languages providea composable framework for domain-specific abstractions.Such a framework is of greater utilitythan a collection of stand-alone domain-specificlanguages. Usually, embedded domain specific languagesare build on top of a set of domain specificprimitive functions that are ultimately implementedusing some form of foreign function call.We sketch a general design pattern for embedding...

Daan Leijen; Erik Meijer

1999-01-01

317

Domain size distributions can predict domain boundaries  

Microsoft Academic Search

Motivation: The sizes of protein domains observed in the 3D-structure database follow a surprisingly narrow distribution. Structural domains are furthermore formed from a single-chain continuous segment in over 80% of instances. These observations imply that some choices of domain boundaries on an otherwise uncharacterized sequence are more likely than others, based solely on the size and segment number of predicted

S. J. Wheelan; Aron Marchler-bauer; Stephen H. Bryant

2000-01-01

318

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

319

Formation of tough composite joints  

SciTech Connect

Joints that exhibited tough fracture behavior were formed in a Si/SiC matrix reinforced with Textron SCS-6 fibers with either boron nitride or silicon nitride fiber coatings. Lapped joints (joints with overlapping fingers) were necessary to obtain tough behavior. Geometrical requirements necessary to avoid brittle joint failure were proposed. Joints with a simple overlap geometry (only a few fingers) had to be very long in order to prevent brittle failure. Joints with an optimized stepped sawtooth geometry produced composite-like failures with the stress/strain curves containing an elastic region followed by a region of rising stress with an increase of strain. Increasing the fiber/matrix interfacial strength, by changing the fiber coating, significantly increased matrix cracking and ultimate strength of the joints. The best joints had matrix cracking stress and ultimate strength of 138 and 240 MPa, respectively. Joint failure was preceded by multiple matrix cracking in the entire composite. The high strength of the joints should permit building of structures containing joints with only a minor reduction of design stresses.

Brun, M.K. [GE Corporate Research and Development, Schenectady, NY (United States)

1998-12-01

320

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

321

Mapping Joint Action.  

ERIC Educational Resources Information Center

The flow diagrams in this document provide cognitive maps to aid in synthesizing diverse areas of knowledge in a special brand of field theory. A model is presented which highlights the domains of structural functionalism (with concepts of cultural, personal and societal systems) and symbolic interactionism (with the concepts of self, sentiments…

Slawski, Carl

322

Temporomandibular Joint Disorders  

NSDL National Science Digital Library

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

Patient Education Institute

323

Bladder operated robotic joint  

NASA Technical Reports Server (NTRS)

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

Robertson, Glen A. (inventor)

1993-01-01

324

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

325

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

326

Proximal interphalangeal joint sprains.  

PubMed

We report the first series of proximal interphalangeal joint sprains and reviewed 50 sprains in 48 patients. The majority of patients were males injured at work. The radial collateral ligament was injured about twice as often as the ulnar ligaments. The little finger was injured significantly less than the others. Proximal interphalangeal joint sprains can be diagnosed by the following: pain localized to the injured ligament, swelling greatest at the site of the injured ligament, tenderness greatest at the site of the injured ligament, pain at the site of the injured ligament during lateral stress, and/or mild lateral instability on radiographs or physical examination during stress testing. All patients required several different splints for treatment; in decreasing frequency, we used immobilizing, coupling, dynamic proximal interphalangeal flexion, dynamic proximal interphalangeal and distal interphalangeal flexion, and dynamic proximal interphalangeal extension splints. The mean active range of motion before treatment was 70 degrees and after treatment was 95 degrees. Significantly more patients had loss of full extension than had loss of full flexion. Forty-six percent of the patients had no pain after treatment, 46 percent had mild pain, 8 percent had moderate pain, and none had severe pain. Patients treated within 4 weeks of their injury (group 1) gained significantly greater range of motion (35 degrees) than those treated between 5 and 14 weeks after their injury (10 degrees) (group 2).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6739583

Wray, R C; Young, V L; Holtman, B

1984-07-01

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

Disorders of the sacroiliac joint.  

PubMed

Controversies have surrounded the sacroiliac joint. The sacroiliac joint (SIJ) is a considerably complex and strong joint with limited mobility, mechanically serving as a force transducer and a shock absorber. Anatomical changes are seen in the SIJ throughout an individual's lifetime. The ligamentous system associated with the SIJ serves to enhance stability and offer proprioceptive feedback in context with the rich plexus of articular receptors. Stability in the SIJ is related to form and force closure. Movement in the SIJ is 3-D about an axis outside of the joint. The functional examination of the SIJ is related to a clinical triad. PMID:17134467

Sizer, Phillip S; Phelps, Valerie; Thompsen, Kirk

2002-03-01

329

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

330

Domains for Denotational Semantics  

Microsoft Academic Search

The purpose of the theory of domains is to give models for spaces on which to define computable functions. The kinds of spaces needed for denotational sematics involve not only spaces of higher type (e.g. function spaces) but also spaces defined recursively (e.g. reflexive domains). Also required are many special domain constructs (or functors) in order to create the desired

Dana S. Scott

1982-01-01

331

The ACT domain family.  

PubMed

A novel ligand-binding domain, named the 'ACT domain', was recently identified by a PSI-BLAST search. The archetypical ACT domain is the C-terminal regulatory domain of 3-phosphoglycerate dehydrogenase (3PGDH), which folds with a ferredoxin-like betaalphabetabetaalphabeta topology. A pair of ACT domains form an eight-stranded antiparallel sheet with two molecules of the allosteric inhibitor serine bound in the interface. The ACT domain is found in a variety of contexts and is proposed to be a conserved regulatory ligand binding fold. Rat phenylalanine hydroxylase has a regulatory domain with a similar fold, but different ligand-binding mode. Putative ACT domains in some proteins of unknown structure (e.g. acetohydroxyacid synthase regulatory subunits) may also fold like the 3PGDH regulatory domain. The regulatory domain of threonine deaminase, although not a member of the ACT sequence family, is similar in structure to the paired 3PGDH regulatory domains. Repeats of ACT-like domains can create nonequivalent ligand-binding sites with the potential for complex regulatory patterns. The structures and mechanisms of such systems have only begun to be examined. PMID:11751050

Chipman, D M; Shaanan, B

2001-12-01

332

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

333

Joint Interdisciplinary Earth Science Information Center  

NASA Technical Reports Server (NTRS)

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

Kafatos, Menas

2004-01-01

334

Smart material joint band  

NASA Astrophysics Data System (ADS)

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

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

1994-11-01

335

Smart material joint band  

NASA Astrophysics Data System (ADS)

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

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

1993-12-01

336

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

337

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.

338

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

339

Slip joint connector  

NASA Technical Reports Server (NTRS)

A slip joint connector for joining first and second structural elements together is presented. The connector has a first body member attachable to the first structural element and a second body member attachable to the second structural element. The first body member has a male protuberance including a conical portion and the second body member has a conical receptacle for cooperatively receiving the conical portion of the protuberance. The protuberance includes a bridging portion for spacing the conical portion from the remainder of the first body member and the second body member has a well communicating with the conical receptacle for receiving the bridging portion. The conical male portion internally carries a nut while the second body member may receive a bolt through the receptacle to be threadedly received by the nut to secure the first and second body members tightly together.

Thomas, Frank P. (inventor)

1994-01-01

340

Foreign Fishery Developments Japanese Joint  

E-print Network

the Japanese investment of $98.2 million (66.9 percent). In 1981, the capital value of these joint ven- tures in Central and South America was $51.5 million, which is 73 percent more than in 1980. The Japanese in of joint ven- tures with Japanese participation in Asia and Oceania was $55.9 million, which is 13 percent

341

Industrial robots with seven joints  

Microsoft Academic Search

In a physical 3-dimensional free space at most six degrees of freedom can be independent, i.e. three for position and three for orientation. Intuitively robots with six joints are adequate to execute any tasks. However, in reality, constraints often exist under the complex environment so that six joints are not quite enough for the robots. An insertion of an additional

J. Y. S. Luh; Y. L. Gu

1985-01-01

342

[Arthroscopy of the metacarpophalangeal joints].  

PubMed

With the advancements in arthroscopic technique, arthroscopy has become feasible in most human joints, even those as small as the finger joints. The metacarpophalangeal joints are very well suited for arthroscopy and arthroscopic therapy. Good results have been reported on arthroscopic synovectomy of the metacarpophalangeal joints in rheumatoid arthritis. Osteochondral lesions in degenerative arthritis, loose bodies and foreign bodies can well be treated. Arthroscopic arthrolysis for capsular contracture and treatment of post-traumatic lesions have been performed successfully. The arthroscopic assistance in the treatment of intraarticular fractures and the capsular shrinkage for instability have been described. However, metacarpophalangeal joint arthroscopy has not been popularised up to now and its role in clinical practice remains to be established. Existing indications will be discussed with respect to our own experience. PMID:25290276

Borisch, N

2014-10-01

343

Method of forming a joint  

DOEpatents

A method of joining at least two sintered bodies to form a composite structure, including providing a first multicomponent metallic oxide having a perovskitic or fluorite crystal structure; providing a second sintered body including a second multicomponent metallic oxide having a crystal structure of the same type as the first; and providing at an interface a joint material containing at least one metal oxide containing at least one metal identically contained in at least one of the first and second multicomponent metallic oxides. The joint material is free of cations of Si, Ge, Sn, Pb, P and Te and has a melting point below the sintering temperatures of both sintered bodies. The joint material is heated to a temperature above the melting point of the metal oxide(s) and below the sintering temperatures of the sintered bodies to form the joint. Structures containing such joints are also disclosed.

Butt, Darryl Paul; Cutler, Raymond Ashton; Rynders, Steven Walton; Carolan, Michael Francis

2006-08-22

344

Non-destructive evaluation of metal-to-metal adhesive joints using vibration analysis: experimental results  

NASA Astrophysics Data System (ADS)

Vibration based non-destructive evaluation shows promise for damage detection in metal-to-metal adhesive joints. This research investigates an experimental technique to diagnose damage in single-lap adhesive joints subject to cyclical tensile loading. Vibration analysis reveals that damage can be correlated with changes in identified modal damping ratios. Constant amplitude forcing functions are employed to eliminate amplitude-dependent nonlinearities in the dynamic response profiles. Damping estimates obtained from time-domain analyses correlate well with damage magnitudes. Finite element modal analysis of the lap joints supports the experimental results.

Pandurangan, Pradeep; Buckner, Gregory D.

2006-03-01

345

Restructuring speech representations using a pitch-adaptive time-frequency smoothing and an instantaneous-frequency-based F0 extraction: Possible role of a repetitive structure in sounds  

Microsoft Academic Search

A set of simple new procedures has been developed to enable the real-time manipulation of speech parame- ters. The proposed method uses pitch-adaptive spec- tral analysis combined with a surface reconstruction method in the time-frequency region, and an excita- tion source design based on group delay manipulation. It also consists of a fundamental frequency (F0) ex- traction method using instantaneous

Hideki Kawahara; Ikuyo Masuda-katsuse; Alain De Cheveigné

1999-01-01

346

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

347

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

348

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

349

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

350

30 CFR 36.24 - Engine joints.  

Code of Federal Regulations, 2010 CFR

...Requirements § 36.24 Engine joints. (a) Cylinder head. The joint between the cylinder head...engine shall be fitted with a metal or metal-clad gasket satisfactory...change in alignment. This joint shall provide an...

2010-07-01

351

30 CFR 36.24 - Engine joints.  

Code of Federal Regulations, 2011 CFR

...Requirements § 36.24 Engine joints. (a) Cylinder head. The joint between the cylinder head...engine shall be fitted with a metal or metal-clad gasket satisfactory...change in alignment. This joint shall provide an...

2011-07-01

352

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

353

Stochastic Chemical Reactions in Micro-domains  

E-print Network

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

D. Holcman; Z. Schuss

2004-12-25

354

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

355

Ferroelectric domain wall injection.  

PubMed

Ferroelectric domain wall injection has been demonstrated by engineering of the local electric field, using focused ion beam milled defects in thin single crystal lamellae of KTiOPO4 (KTP). The electric field distribution (top) displays localized field hot-spots, which correlate with nucleation events (bottom). Designed local field variations can also dictate subsequent domain wall mobility, demonstrating a new paradigm in ferroelectric domain wall control. PMID:24136810

Whyte, Jonathan R; McQuaid, Raymond G P; Sharma, Pankaj; Canalias, Carlota; Scott, James F; Gruverman, Alexei; Gregg, J Marty

2014-01-15

356

Structural domains and their potential impact on recharge to intermontane-basin aquifers  

USGS Publications Warehouse

Variations in the structures exposed in structural domains associated with faults can affect the amount of ground-water recharge to fractured rock aquifers supplying intermontane-basin aquifers. In the south-western Franklin Mountains, El Paso, Texas, an outcrop of the Ordovician Scenic Drive Formation exposes a group of structures including faults, joints, and folds associated with a left-lateral fault striking N74??E and dipping 81??NW. Slip along this fault has produced a structural domain with extensional structures (normal faults and joints) and a domain with contractional structures (folds and joints). These extensional and contractional domains occur on opposite sides of the fault. Properties of fractures within the different structural domains can influence ground-water recharge and migration. For example, the domain with extensional structures contains nearly vertical joints that extend from the soil-bedrock interface to normal faults and along which precipitation can infiltrate. Since the left-lateral fault is approximately normal to the trend of the Franklin Mountains, this fault may be a conduit for ground-water flow from the mountains to the basin. The domain with contractional structures is limited in extent, and the fractures in this domain are poorly connected. Therefore, surface infiltration in this domain is reduced, and may not contribute as much to ground-water migration. Structural domains that are analogous to this outcrop and cover larger areas can be found throughout the Franklin Mountains. Understanding the variations between structural domains can aid in siting water-supply wells and determining contaminant transport in fractured rock.

Ohlmacher, G.C.

1999-01-01

357

Learning and Domain Adaptation  

NASA Astrophysics Data System (ADS)

Domain adaptation is a fundamental learning problem where one wishes to use labeled data from one or several source domains to learn a hypothesis performing well on a different, yet related, domain for which no labeled data is available. This generalization across domains is a very significant challenge for many machine learning applications and arises in a variety of natural settings, including NLP tasks (document classification, sentiment analysis, etc.), speech recognition (speakers and noise or environment adaptation) and face recognition (different lighting conditions, different population composition).

Mansour, Yishay

358

Compliant Prosthetic Or Robotic Joint  

NASA Technical Reports Server (NTRS)

Rotation partly free and partly restrained by resilience and damping. Joint includes U-shaped x- and y-axis frames joined by cables that cross in at center piece. The y-axis frame rotates about y-axis on roller bearing within predetermined angular range. The y-axis frame rotates slightly farther when arm strikes stop, because cables can twist. This mimics compliant resistance of knee joint reaching limit of its forward or backward motion. Used in prosthetic device to replace diseased or damage human joint, or in robot linkage to limit movement and cushion overloads.

Kerley, James J.; Eklund, Wayne D.

1989-01-01

359

Acromioclavicular joint cyst formation.  

PubMed

Acromioclavicular joint (ACJ) cysts are an uncommon and unusual sequela associated with shoulder pathophysiology. The majority of literature on ACJ cysts consists of individual case reports with no definitive literature review currently available. In addition to a comprehensive literature review, four clinical cases are presented in this report. First described by Craig (1984), a total of 41 cases have been previously reported in the literature. Of these cases, five occurred with the rotator cuff musculature intact. The remaining 36 cases of ACJ cysts occurred in patients with a complete tear/avulsion of the rotator cuff. Previous attempts at compiling a complete record of all reported cases have combined several distinct conditions into a single category. This article presents two distinct etiologies for the pathogenesis of ACJ cyst formation. In the presence of an intact rotator cuff, a Type 1 cyst can form superficially and be limited to the ACJ. Following a massive or traumatic tear of the rotator cuff, mechanical instability of the humeral head can cause a deterioration of the inferior acromioclavicular capsule (cuff tear arthropathy) and an overproduction of synovial fluid. Overtime, a "geyser" of fluid can form between the glenohumeral and the ACJ, forming a Type 2 cyst. This differentiation and categorization is essential for appropriate classification and treatment. PMID:20069645

Hiller, Andrew D; Miller, Joshua D; Zeller, John L

2010-03-01

360

Visualizing domain wall and reverse domain superconductivity.  

PubMed

In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application. PMID:25164004

Iavarone, M; Moore, S A; Fedor, J; Ciocys, S T; Karapetrov, G; Pearson, J; Novosad, V; Bader, S D

2014-01-01

361

Visualizing domain wall and reverse domain superconductivity  

PubMed Central

In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application. PMID:25164004

Iavarone, M.; Moore, S. A.; Fedor, J.; Ciocys, S. T.; Karapetrov, G.; Pearson, J.; Novosad, V.; Bader, S. D.

2014-01-01

362

Non-linear joint dynamics and controls of jointed flexible structures with active and viscoelastic joint actuators  

Microsoft Academic Search

Studies on joint dominated flexible space structures have attracted much interest recently due to the rapid developments in large deployable space systems. This paper describes a study of the non-linear structural dynamics of jointed flexible structures with initial joint clearance and subjected to external excitations. Methods of using viscoelastic and active vibration control technologies, joint actuators, to reduce dynamic contact

H. S. Tzou

1990-01-01

363

Campus/Industry Joint Ventures.  

ERIC Educational Resources Information Center

Opportunities for joint economic ventures of colleges and industry are discussed, and a variety of ventures undertaken by Duke University are outlined, including a health club, hotel, and office building. Tax and financing considerations are noted. (MSE)

McDonald, Eugene J.

1985-01-01

364

Coupled behavior of rock joints  

SciTech Connect

The behavior of rock joints under various coupled processes is reviewed under four broad categories: hydromechanical processes, thermohydromechanical processes, hydromechanical-chemical processes, and thermomechanical-hydrochemical processes. The state-of-the-art and possible directions of further research in these coupled processes are discussed. Rock joint behaviors considered include not only dilation, closure, shear and joint propagation, but also changes in flow permeability and chemical sorption and retardation capabilities. These properties are of critical concern in practical considerations of the rock mass as a medium to store and isolate chemical and radioactive wastes. Investigations of coupled processes in two-fracture systems and multi-fracture systems are pointed out as interesting areas for future research. The need to consider coupled processes in borehole testing procedures involving rock joints is emphasized. 70 refs., 12 figs.

Tsang, Chin-Fu.

1990-02-01

365

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

366

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

367

Domain wall filters  

SciTech Connect

We propose using the extra dimension separating the domain walls carrying lattice quarks of opposite handedness to gradually filter out the ultraviolet fluctuations of the gauge fields that are felt by the fermionic excitations living in the bulk. This generalization of the homogeneous domain wall construction has some theoretical features that seem nontrivial.

Oliver Baer; Rajamani Narayanan; Herbert Neuberger; Oliver Witzel

2007-03-15

368

Causal Learning Across Domains  

ERIC Educational Resources Information Center

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

Schulz, Laura E.; Gopnik, Alison

2004-01-01

369

Modeling Protein Domain Function  

ERIC Educational Resources Information Center

This simple but effective laboratory exercise helps students understand the concept of protein domain function. They use foam beads, Styrofoam craft balls, and pipe cleaners to explore how domains within protein active sites interact to form a functional protein. The activity allows students to gain content mastery and an understanding of the…

Baker, William P.; Jones, Carleton "Buck"; Hull, Elizabeth

2007-01-01

370

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

371

Protein Domain Histochemistry (PDH)  

PubMed Central

Specialized protein domains bind to posttranslational modifications (PTMs) of proteins, such as phosphorylation or glycosylation. When such PTM-binding protein domains are used as analytical tools, the functional states of cells and tissues can be determined with high precision. Here, we describe the use of recombinant CLEC10A (CD301), a human glycoreceptor of the C-type lectin family, for the detection of ligands in sections from formalin-fixed, paraffin-embedded normal and cancerous mammary tissues. A construct, in which part of the carbohydrate recognition domain (CRD) was deleted, was used as a negative control. In comparison to normal mammary glands, a pronounced staining of tumor tissues was observed. Because the construct with the truncated CRD did not show any tissue staining, the binding of the wild-type glycoreceptor can be attributed to its carbohydrate recognition domain. To distinguish our novel approach from immunohistochemistry, we propose the designation “protein domain histochemistry” (PDH). PMID:23275449

Nollau, Peter; Wolters-Eisfeld, Gerrit; Mortezai, Naghmeh; Kurze, Anna-Katharina; Klampe, Birgit; Debus, Annegret; Bockhorn, Maximilian; Niendorf, Axel

2013-01-01

372

Model Fusion and Joint Inversion  

NASA Astrophysics Data System (ADS)

Inverse problems are inherently non-unique, and regularization is needed to obtain stable and reasonable solutions. The regularization adds information to the problem and determines which solution, out of the infinitely many, is obtained. In this paper, we review and discuss the case when a priori information exists in the form of either known structure or in the form of another inverse problem for a different property. The challenge is to include such information in the inversion process. To use existing known structure, we review the concept of model fusion, where we build a regularization functional that fuses the inverted model to a known one. The fusion is achieved by four different techniques. Joint inversion of two data sets is achieved by using iterative data fusion. The paper discusses four different methods for joint inversion. We discuss the use of correspondence maps or the petrophysics of the rocks, as well as structure. In particular, we suggest to further stabilize the well-known gradient cross product and suggest a new technique, Joint Total Variation, to solve the problem. The Joint Total Variation is a convex functional for joint inversion and, as such, has favorable optimization properties. We experiment with the techniques on the DC resistivity problem and the borehole tomography and show how model fusion and joint inversion can significantly improve over existing techniques.

Haber, Eldad; Holtzman Gazit, Michal

2013-09-01

373

Frequency-domain sensitivity analysis for small imaging domains using the equation of radiative transfer  

NASA Astrophysics Data System (ADS)

Optical tomography of small imaging domains holds great promise as the signal-to-noise ratio is usually high, and the achievable spatial resolution is much better than in large imaging domains. Emerging applications range from the imaging of joint diseases in human fingers to monitoring tumor growth or brain activity in small animals. In these cases, the diameter of the tissue under investigation is typically smaller than 3 cm, and the optical path length is only a few scattering mean-free paths. It is well known that under these conditions the widely applied diffusion approximation to the equation of radiative transfer (ERT) is of limited applicability. To accurately model light propagation in these small domains, the ERT has to be solved directly. We use the frequency-domain ERT to perform a sensitivity study for small imaging domains. We found optimal source-modulation frequencies for which variations in optical properties, size, and location of a tissue inhomogeneity lead to maximal changes in the amplitude and phase of the measured signal. These results will be useful in the design of experiments and optical tomographic imaging systems that probe small tissue volumes.

Gu, Xuejun; Ren, Kui; Hielscher, Andreas H.

2007-04-01

374

Interface failure in lead free solder joints  

Microsoft Academic Search

The phenomenon of interface failure in lead free solder joints was explored using solder joint array tensile testing. The effects of pad metallization, solder alloy, reflow conditions, and post reflow thermal aging were quantified. The joint strength ranged from 5 to 115MPa. The joint ductility dropped to zero in some cases. The interface microstructure and failure mode were characterized for

Robert Darveaux; Corey Reichman; Nokibul Islam

2006-01-01

375

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

376

49 CFR 213.351 - Rail joints.  

Code of Federal Regulations, 2014 CFR

...Transportation 4 2014-10-01 2014-10-01 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...

2014-10-01

377

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

378

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

379

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

380

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

381

Blur-resistant joint 1D and 2D barcode localization for smartphones  

E-print Network

Blur-resistant joint 1D and 2D barcode localization for smartphones Gábor Sörös Institute@inf.ethz.ch ABSTRACT With the proliferation of built-in cameras barcode scanning on smartphones has become widespread in both consumer and enterprise domains. To avoid making the user precisely align the barcode

382

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

383

Simulation-Based Joint Estimation of Body Deformation and Elasticity Parameters for Medical  

E-print Network

1 Simulation-Based Joint Estimation of Body Deformation and Elasticity Parameters for Medical Image-based simulation. Index Terms--Elasticity reconstruction, Physically-based sim- ulation, Non-rigid image elasticity model solved with the finite element method (FEM) [5], where the domain of the image is subdivided

North Carolina at Chapel Hill, University of

384

Disorders of the distal radioulnar joint.  

PubMed

The distal radioulnar joint is responsible for stable forearm rotation. Injury to this joint can occur following a variety of mechanisms, including wrist fractures, ligamentous damage, or degenerative wear. Accurate diagnosis requires a clear understanding of the anatomy and mechanics of the ulnar aspect of the wrist. Injuries can be divided into three major categories for diagnostic purposes, and these include pain without joint instability, pain with joint instability, and joint arthritis. New advancements in imaging and surgical technique can allow for earlier detection of injuries, potentially preserving joint function. In this article, the authors review the pertinent anatomy, biomechanics, and major abnormality involving the distal radioulnar joint. PMID:25285686

Houdek, Matthew T; Wagner, Eric R; Moran, Steven L; Berger, Richard A

2015-01-01

385

Design of Redundant Drive Joint with adjustable stiffness and damping mechanism to improve joint admittance  

Microsoft Academic Search

Improving admittance of robotic joints is the key issue for making rehabilitation robots safe. This paper describes a design of redundant drive joint (RD-Joint) which allows greater flexibility in the design of robotic mechanisms. The design strategy of the RD-joint employs a systematic approach which consists of 1) adopting a redundant joint mechanism with internal kinematical redundancy to reduce effective

Yosuke Ikegami; Kiyoshi Nagai; Rui C. V. Loureiro; William S. Harwin

2009-01-01

386

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

387

Strength evaluation of socket joints  

NASA Technical Reports Server (NTRS)

This report documents the development of a set of equations that can be used to provide a relatively simple solution for identifying the strength of socket joints and for most cases avoid the need of more lengthy analyses. The analytical approach was verified by comparison of the contact load distributions to results obtained from a finite element analysis. The contacting surfaces for the specific joint in this analysis are in the shape of frustrums of a cone and are representative of the tapered surfaces in the socket-type joints used to join segments of model support systems for wind tunnels. The results are in the form of equations that can be used to determine the contact loads and stresses in the joint from the given geometry and externally applied loads. Equations were determined to define the bending moments and stresses along the length of the joints based on strength and materials principles. The results have also been programmed for a personal computer and a copy of the program is included.

Rash, Larry C.

1994-01-01

388

Sectional domain specific languages  

Microsoft Academic Search

Nowadays, many problems are solved by using a domain specific language (DSL), i.e., a programming language tailored to work on a particular application domain. Normally, a new DSL is designed and implemented from scratch requiring a long time-to-market due to implementation and testing issues. Whereas when the DSL simply extends another language it is realized as a source-to-source transformation or

Walter Cazzola; Ivan Speziale

2009-01-01

389

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

390

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

391

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

392

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. PMID:25684928

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

2015-01-01

393

Just how versatile are domains?  

PubMed Central

Background Creating new protein domain arrangements is a frequent mechanism of evolutionary innovation. While some domains always form the same combinations, others form many different arrangements. This ability, which is often referred to as versatility or promiscuity of domains, its a random evolutionary model in which a domain's promiscuity is based on its relative frequency of domains. Results We show that there is a clear relationship across genomes between the promiscuity of a given domain and its frequency. However, the strength of this relationship differs for different domains. We thus redefine domain promiscuity by defining a new index, DV I ("domain versatility index"), which eliminates the effect of domain frequency. We explore links between a domain's versatility, when unlinked from abundance, and its biological properties. Conclusion Our results indicate that domains occurring as single domain proteins and domains appearing frequently at protein termini have a higher DV I. This is consistent with previous observations that the evolution of domain re-arrangements is primarily driven by fusion of pre-existing arrangements and single domains as well as loss of domains at protein termini. Furthermore, we studied the link between domain age, defined as the first appearance of a domain in the species tree, and the DV I. Contrary to previous studies based on domain promiscuity, it seems as if the DV I is age independent. Finally, we find that contrary to previously reported findings, versatility is lower in Eukaryotes. In summary, our measure of domain versatility indicates that a random attachment process is sufficient to explain the observed distribution of domain arrangements and that several views on domain promiscuity need to be revised. PMID:18854028

2008-01-01

394

Rothia prosthetic knee joint infection.  

PubMed

Rothia species - Gram-positive pleomorphic bacteria that are part of the normal oral and respiratory flora - are commonly associated with dental cavities and periodontal disease although systemic infections have been described. We describe a 53-year-old female with rheumatoid arthritis complicated by prosthetic knee joint infection due to Rothia species, which was successfully treated by surgical removal of prosthesis and prolonged antimicrobial therapy. The issue of antibiotic prophylaxis before dental procedures among patients with prosthetic joint replacements is discussed. PMID:23357608

Trivedi, Manish N; Malhotra, Prashant

2013-01-25

395

[Divorce and joint physical custody].  

PubMed

This work first recalls the definition of joint physical custody, as well as the current legal procedure for obtaining it, its practical implementation, the financial implications for parents, and finally some statistics. Some psychological and psychopathological reflections on the impact of divorce on children are then presented before considering the question of joint physically custody with regard to attachment theory and depending on the age of the child (a great caution seems to be required before three years). The article concludes with a brief discussion of parental alienation syndrome. PMID:24630624

Golse, B

2014-04-01

396

Pathogenesis of Degenerative Joint Disease in the Human Temporomandibular Joint  

Microsoft Academic Search

The wide range of disease prevalences reported in epidemiological studies of temporomandibular degenerative joint disease reflects the fact that diagnoses are frequently guided by the presence or absence of non-specific signs and symptoms. Treatment is aimed at alleviating the disease symptoms rather than being guided by an understanding of the underlying disease processes. Much of our current understanding of disease

Christine L. Haskin; Stephen B. Milam; Ivan L. Cameron

1995-01-01

397

General joint hypermobility and temporomandibular joint derangement in adolescents  

Microsoft Academic Search

Joint mobility was assessed in each member of an epidemiological sample of 96 girls and 97 boys, 17 years old, and graded by means of the hypermobility score of Beighton et al. Twenty two per cent of the girls and 3% of the boys could perform five or more of the nine manoeuvres. The prevalence of symptoms and signs of

L Westling; A Mattiasson

1992-01-01

398

Domains in Ferroelectric Nanostructures  

NASA Astrophysics Data System (ADS)

Ferroelectric materials have great potential in influencing the future of small scale electronics. At a basic level, this is because ferroelectric surfaces are charged, and so interact strongly with charge-carrying metals and semiconductors - the building blocks for all electronic systems. Since the electrical polarity of the ferroelectric can be reversed, surfaces can both attract and repel charges in nearby materials, and can thereby exert complete control over both charge distribution and movement. It should be no surprise, therefore, that microelectronics industries have already looked very seriously at harnessing ferroelectric materials in a variety of applications, from solid state memory chips (FeRAMs) to field effect transistors (FeFETs). In all such applications, switching the direction of the polarity of the ferroelectric is a key aspect of functional behavior. The mechanism for switching involves the field-induced nucleation and growth of domains. Domain coarsening, through domain wall propagation, eventually causes the entire ferroelectric to switch its polar direction. It is thus the existence and behavior of domains that determine the switching response, and ultimately the performance of the ferroelectric device. A major issue, associated with the integration of ferroelectrics into microelectronic devices, has been that the fundamental properties associated with ferroelectrics, when in bulk form, appear to change quite dramatically and unpredictably when at the nanoscale: new modes of behaviour, and different functional characteristics from those seen in bulk appear. For domains, in particular, the proximity of surfaces and boundaries have a dramatic effect: surface tension and depolarizing fields both serve to increase the equilibrium density of domains, such that minor changes in scale or morphology can have major ramifications for domain redistribution. Given the importance of domains in dictating the overall switching characteristics of a device, the need to fully understand how size and morphology affect domain behaviour in small scale ferroelectrics is obvious. In this talk, observations from a programme of study examining domains in meso and nano-scale BaTiO3 shapes, that have been cut directly from bulk single crystal using focused ion beam milling, will be presented. In general, the equilibrium static domain configurations that occur appear to be the result of a simultaneous desire to minimize both the macroscopic strain and depolarizing fields developed on cooling through the Curie Temperature. While such governing factors might be obvious, the specific patterns that result as a function of morphology are often non-intuitive, and a series of images of domains in nanodots, rods and wires will be presented and rationalised. In addition, the nature in which morphological factors influence domain dynamics during switching will be discussed, with particular focus on axial switching in nanowires, and the manner in which local surface perturbations (such as notches and antinotches) affect domain wall propagation. In collaboration with Alina Schilling, Li-Wu Chang, Mark McMillen, Raymond McQuaid, and Leo McGilly, Queen's University Belfast; Gustau Catalan, Universitat Autonoma de Barcelona; and James Scott, University of Cambridge.

Gregg, Marty

2010-03-01

399

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

400

In vivo estimation of the short-range stiffness of cross-bridges from joint rotation.  

PubMed

Short-range stiffness (SRS) is a mechanical property of muscles that is characterized by a disproportionally high stiffness within a short length range during both lengthening and shortening movements. SRS is attributed to the cross-bridges and is beneficial for stabilizing a joint during, e.g., postural conditions. Thus far, SRS has been estimated mainly on isolated mammalian muscles. In this study we presented a method to estimate SRS in vivo in the human wrist joint. SRS was estimated at joint level in the angular domain (Nm/rad) for both flexion and extension rotations of the human wrist in nine healthy subjects. Wrist rotations of 0.15rad at 3rad/s were imposed at eight levels of voluntary contraction ranging from 0 to 2.1Nm by means of a single axis manipulator. Flexion and extension SRS of the wrist joint was estimated consistently and accurately using a dynamic nonlinear model that was fitted onto the recorded wrist torque. SRS increased monotonically with torque in a way consistent with previous studies on isolated muscles. It is concluded that in vivo measurement of joint SRS represents the population of coupled cross-bridges in wrist flexor and extensor muscles. In its current form, the presented technique can be used for clinical applications in many neurological and muscular diseases where altered joint torque and (dissociated) joint stiffness are important clinical parameters. PMID:20541761

van Eesbeek, Stijn; de Groot, Jurriaan H; van der Helm, Frans C T; de Vlugt, Erwin

2010-09-17

401

Flexible joints for thrust vector control  

NASA Technical Reports Server (NTRS)

Flexible joints have been used to achieve thrust vector control over a wide range of sizes of nozzles and have been demonstrated successfully in bench tests and static firings, and are operational on two motors. From these many joints the problems of flexible joints have been defined as establishment of the movable nozzle envelope, definition of the actuation power requirements, definition of the mechanical properties of joint materials, adhesive bonding, test methods, and quality control. These data and problem solutions are contained in a large number of reports. Data relating to joint configuration, design requirements, materials selection, joint design, structural analysis, manufacture, and testing are summarized.

Woodberry, R. F. H.

1975-01-01

402

Provocative sacroiliac joint maneuvers and sacroiliac joint block are unreliable for diagnosing sacroiliac joint pain.  

PubMed

Mapping studies of pain elicited by injections into the sacroiliac joints (SIJs) suggest that sacroiliac joint syndrome (SIJS) may manifest as low back pain, sciatica, or trochanteric pain. Neither patient-reported symptoms nor provocative SIJ maneuvers are sensitive or specific for SIJS when SIJ block is used as the diagnostic gold standard. This has led to increasing diagnostic use of SIJ block, a procedure in which an anesthetic is injected into the joint under arthrographic guidance. However, several arguments cast doubt on the validity of SIJ block as a diagnostic gold standard. Thus, the effects of two consecutive blocks are identical in only 60% of cases, and the anesthetic diffuses out of the joint in 61% of cases, often coming into contact with the sheaths of the adjacent nerve trunks or roots, including the lumbosacral trunk (which may contribute to pain in the groin or thigh) and the L5 and S1 nerve roots. These data partly explain the limited specificity of SIJ block for the diagnosis of SIJS and the discordance between the pain elicited by the arthrography injection and the response to the block. The limitations of provocative maneuvers and SIJ blocks may stem in part from a contribution of extraarticular ligaments to the genesis of pain believed to originate within the SIJs. These ligaments include the expansion of the iliolumbar ligaments, the dorsal and ventral sacroiliac ligaments, the sacrospinous ligaments, and the sacrotuberous ligaments (sacroiliac joint lato-sensu). They play a role in locking or in allowing motion of the SIJs. Glucocorticoids may diffuse better than anesthetics within these ligaments. Furthermore, joint fusion may result in ligament unloading. PMID:16461204

Berthelot, Jean-Marie; Labat, Jean-Jacques; Le Goff, Benoît; Gouin, François; Maugars, Yves

2006-01-01

403

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

404

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

405

Trends in biological joint resurfacing  

PubMed Central

The treatment of osteochondral lesions and osteoarthritis remains an ongoing clinical challenge in orthopaedics. This review examines the current research in the fields of cartilage regeneration, osteochondral defect treatment, and biological joint resurfacing, and reports on the results of clinical and pre-clinical studies. We also report on novel treatment strategies and discuss their potential promise or pitfalls. Current focus involves the use of a scaffold providing mechanical support with the addition of chondrocytes or mesenchymal stem cells (MSCs), or the use of cell homing to differentiate the organism’s own endogenous cell sources into cartilage. This method is usually performed with scaffolds that have been coated with a chemotactic agent or with structures that support the sustained release of growth factors or other chondroinductive agents. We also discuss unique methods and designs for cell homing and scaffold production, and improvements in biological joint resurfacing. There have been a number of exciting new studies and techniques developed that aim to repair or restore osteochondral lesions and to treat larger defects or the entire articular surface. The concept of a biological total joint replacement appears to have much potential. Cite this article: Bone Joint Res 2013;2:193–9. PMID:24043640

Myers, K. R.; Sgaglione, N. A.; Grande, D. A.

2013-01-01

406

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

407

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

408

Joint strength in RCS frames  

E-print Network

As part of a National Science Foundation (NSF) program ics. on composite and hybrid systems at Texas A&M University, the objective of this thesis is to investigate the joint strength in reinforced column-steel beam (RCS) special moment frames...

Kirby, Cynthia Dawn

1998-01-01

409

Authority, Deontics and Joint Intentions  

Microsoft Academic Search

Many agents are fielded within environments requiring modeling traditional organizational structures such as military hierarchies and corporations, with their associated authority relationships and a strong form of responsibility associated with subordinate agents. Addressing the needs above, we have developed an integrated semantic framework for modeling and operationalizing authority relationships and deontic operators based upon joint intention theory. This allows us

Marcus J. Huber; Sanjeev Kumar; Sean A. Lisse; David Mcgee

2007-01-01

410

Chicken Skeleton - Gliding Joint (Skull)  

NSDL National Science Digital Library

The chicken uses its beak to pick up small pieces of food from the ground. The gliding joint at the base of the skull allows the chicken to move its head in different directions. It can also defend itself by pecking.

Ketan Patel (California State University, Fullerton; Student, Biological Sciences)

2007-07-28

411

Building a joint information system  

Microsoft Academic Search

This paper discusses how a joint information system can be developed. The implementation was carried out in a project, doing final definitions and specifications, producing the information system and taking it into pilot use. The environment of the new collaborative information system is in the university world where student mobility is increasing. Student mobility means that students are enabled to

Raija Halonen

412

Knee joint replacement - series (image)  

MedlinePLUS

... joint. It contains the distal end of the femur (the femoral condyles) and the proximal end of the tibia (the tibial plateau). The femoral condyles usually glide smoothly on the tibial plateau. This allows the lower leg to move smoothly and painlessly.

413

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

414

Trapped Modes in CESR Sliding Joints  

NASA Astrophysics Data System (ADS)

Trapped modes in the sliding joints in CESR may eventually set a limit on the currents in the machine. To detect these modes, experiments were performed where pairs of bunches of positrons were run through at various spacings. It was hoped that constructive and destructive interference of wake fields would produce varying amounts of heating. Data taking was time consuming, and insufficient numbers of data points could be taken to fit to the wake fields. To help solve this, the frequency of the mode was measured on the bench. A single trapped mode and its profile were observed. The trapped mode has a frequency of 3.59 GHz, just below the TM cutoff. The mode was used to predict a shunt impedance of 4.9 ohms. The corresponding loss factor is slightly higher than the total loss factor found in previous time domain measurements /footnoteBilling, Mike. Higher power Mode Loss Limitations for Beam Currents in CESR. CBN 84-15 (1984). The program ZAP/footnoteZisman, Michael, Swapan Chattopadhyay, and Joseph Bisognano. was used to predict an instability threshold of about 2.1 A.

Anderson, Edwin; Rogers, Joseph

1997-05-01

415

An Empirical Study of Automated Dictionary Construction for Information Extraction in Three Domains  

Microsoft Academic Search

this paper, we describe experiments with AutoSlog intwo additional domains: joint ventures and microelectronics. Wecompare the performance of AutoSlog across the three domains,discuss the lessons learned about the generality of this approach,and present results from two experiments which demonstrate thatnovice users can generate effective dictionaries using AutoSlog.1 IntroductionPortability is a crucial concern for researchers in knowledge-based naturallanguage processing (NLP)....

Ellen Riloff

1996-01-01

416

Joint Disorders - Multiple Languages: MedlinePlus  

MedlinePLUS

... JavaScript. Joint Disorders - Multiple Languages Arabic (???????) Bosnian (Bosanski) Chinese - Simplified (????) Chinese - Traditional (????) French (français) ... ??????? - ??????? Bilingual PDF Health Information Translations Bosnian (Bosanski) Home Care After Total Joint Replacement Ku?na njega ...

417

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2014 CFR

...weight-bearing are related considerations. For the purpose of rating disability from arthritis, the shoulder, elbow, wrist, hip, knee, and ankle are considered major joints; multiple involvements of the interphalangeal, metacarpal and carpal joints of the...

2014-07-01

418

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2011 CFR

...weight-bearing are related considerations. For the purpose of rating disability from arthritis, the shoulder, elbow, wrist, hip, knee, and ankle are considered major joints; multiple involvements of the interphalangeal, metacarpal and carpal joints of the...

2011-07-01

419

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2013 CFR

...weight-bearing are related considerations. For the purpose of rating disability from arthritis, the shoulder, elbow, wrist, hip, knee, and ankle are considered major joints; multiple involvements of the interphalangeal, metacarpal and carpal joints of the...

2013-07-01

420

38 CFR 4.45 - The joints.  

Code of Federal Regulations, 2010 CFR

...movement than normal (from flail joint, resections, nonunion of fracture, relaxation of ligaments, etc.). (c) Weakened movement...arthritis, the shoulder, elbow, wrist, hip, knee, and ankle are considered major joints; multiple involvements of the...

2010-07-01

421

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2014 CFR

...Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. (a) A carline jointly owned and/or produced by more...

2014-10-01

422

49 CFR 583.15 - Joint ownership.  

Code of Federal Regulations, 2012 CFR

...Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) AUTOMOBILE PARTS CONTENT LABELING § 583.15 Joint ownership. (a) A carline jointly owned and/or produced by more...

2012-10-01

423

United States Bone and Joint Decade  

MedlinePLUS

... Press Releases Scientific/Professional Journals Welcome to the United States Bone and Joint Initiative! Primary tabs View (active ... industry, have come together as part of the United States Bone and Joint Initiative (USBJI) to improve prevention ...

424

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

425

Signals: Tinkering with Domains  

NSDL National Science Digital Library

Evolution reuses established modules. At the level of cell signaling, protein domains are used in many contexts to transfer different messages. A frequently occurring binding domain uses a structural scaffold to allow for sequence variation at critical sites without compromising structural stability. Even random mutations have a high chance of conferring a novel function, and only a small fraction of available sequence space is actually explored. Accordingly, current lab techniques allow us to infer evolutionary routes, exploring the possible and the attainable in terms of complex structure-function relationships.

Erich Bornberg-Bauer (University of Munster; Institute for Evolution and Biodiversity REV)

2010-09-14

426

Unsupervised Spatial Event Detection in Targeted Domains with Applications to Civil Unrest Modeling  

PubMed Central

Twitter has become a popular data source as a surrogate for monitoring and detecting events. Targeted domains such as crime, election, and social unrest require the creation of algorithms capable of detecting events pertinent to these domains. Due to the unstructured language, short-length messages, dynamics, and heterogeneity typical of Twitter data streams, it is technically difficult and labor-intensive to develop and maintain supervised learning systems. We present a novel unsupervised approach for detecting spatial events in targeted domains and illustrate this approach using one specific domain, viz. civil unrest modeling. Given a targeted domain, we propose a dynamic query expansion algorithm to iteratively expand domain-related terms, and generate a tweet homogeneous graph. An anomaly identification method is utilized to detect spatial events over this graph by jointly maximizing local modularity and spatial scan statistics. Extensive experiments conducted in 10 Latin American countries demonstrate the effectiveness of the proposed approach. PMID:25350136

Zhao, Liang; Chen, Feng; Dai, Jing; Hua, Ting; Lu, Chang-Tien; Ramakrishnan, Naren

2014-01-01

427

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

428

78 FR 14620 - Joint Development: Proposed Circular  

Federal Register 2010, 2011, 2012, 2013, 2014

...FTA-2013-0013] Joint Development: Proposed Circular...the docket and on its web site proposed guidance...circular, on joint development. This circular provides...when pursuing a joint development project. This following...be found on FTA's Web site at...

2013-03-06

429

49 CFR 234.233 - Rail joints.  

Code of Federal Regulations, 2014 CFR

... 4 2014-10-01 2014-10-01 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...

2014-10-01

430

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

431

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

432

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

433

A Deformable Slider Joint for Multibody Applications  

Microsoft Academic Search

This paper presents the implementation of a deformable slider joint in the framework of a multibody simulation environment. A slider joint constrains the motion of a rigid body point along a line: a deformable slider joint allows the constrained point to move along a series of deformable beams, switching from one to the other without encountering serious numerical discontinuities. The

Stefania Gualdi; Marco Morandini; Pierangelo Masarati

434

Behavior of jointed ductile iron pipelines  

Microsoft Academic Search

Experimental data on the axial, bending, and torsional behavior of a pipeline joint demonstrated, in particular, the relationship between the load and the deflection behavior of a rubber gasketed joint in a ductile cast iron pipe. These results, along with analytical expressions, are especially useful in predicting the earthquake behavior of buried pipelines with flexible joints.

Singhal

1984-01-01

435

22 CFR 228.34 - Joint ventures.  

Code of Federal Regulations, 2010 CFR

... 1 2010-04-01 2010-04-01 false Joint ventures. 228.34 Section 228.34 Foreign Relations...of Services for USAID Financing § 228.34 Joint ventures. A joint venture or unincorporated association is eligible only...

2010-04-01

436

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

437

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

438

38 CFR 4.66 - Sacroiliac joint.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Sacroiliac joint. 4.66 Section 4.66 Pensions...Musculoskeletal System § 4.66 Sacroiliac joint. The common cause of disability...manner. The lumbosacral and sacroiliac joints should be considered as one...

2011-07-01

439

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

440

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

441

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

442

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

443

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

444

49 CFR 178.345-4 - Joints.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Joints. 178.345-4 Section 178...Transportation § 178.345-4 Joints. (a) All joints between the cargo tank shell...rings, and bulkheads must be welded in conformance with Section...

2011-10-01

445

49 CFR 178.345-4 - Joints.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Joints. 178.345-4 Section 178...Transportation § 178.345-4 Joints. (a) All joints between the cargo tank shell...attaching rings, and bulkheads must be welded in conformance with Section...

2010-10-01

446

Evaluation and Treatment of Acromioclavicular Joint Injuries  

Microsoft Academic Search

Acromioclavicular joint injuries and, more specifically, separations are commonplace both in general practice and during athletic participation. This article reviews the traditional classification as well as the clinical evaluation of patients with acute and chronic acromioclavicular joint separations. It also highlights many recent advances, principally in the anatomy and biomechanics of the acromioclavicular joint ligamentous complex. The concept of increases

Augustus D. Mazzocca; Robert A. Arciero; James Bicos

2007-01-01

447

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

448

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

449

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

450

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 that abut these same Alleghanian joints. Field evidence shows that concretions functioned as sti inclusions

Engelder, Terry

451

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

452

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

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 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....

2010-04-01

453

Time-Frequency Analysis May 25, 2012  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.5 The Fragility of Fourier Transform Methods Curvelets 49 6.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 6.2 Frequency-Based Curvelet Construction

Grohs, Philipp

454

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

455

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

456

Degenerative joint disease of the acromioclavicular joint: a review.  

PubMed

Osteoarthritis of the acromioclavicular (AC) joint is a common condition causing anterior or superior shoulder pain, especially with overhead and cross-body activities. This most commonly occurs in middle-aged individuals because of degeneration to the fibrocartilaginous disk that cushions the articulations. Diagnosis relies on history, physical examination, imaging, and diagnostic local anesthetic injection. Diagnosis can be challenging given the lack of specificity with positive physical examination findings and the variable nature of AC joint pain. Of note, symptomatic AC osteoarthritis must be differentiated from instability and subtle instability, which may have similar symptoms. Although plain radiographs can reveal degeneration, diagnosis cannot be based on this alone because similar radiographic findings can be seen in asymptomatic individuals. Nonoperative therapy can provide symptomatic relief, whereas patients with persistent symptoms can be considered for resection arthroplasty by open or arthroscopic technique. Both techniques have proven to provide predictable pain relief; however, each has its own unique set of potential complications that may be minimized with an improved understanding of the anatomical and biomechanical characteristics of the joint along with meticulous surgical technique. PMID:23649008

Mall, Nathan A; Foley, Emily; Chalmers, Peter N; Cole, Brian J; Romeo, Anthony A; Bach, Bernard R

2013-11-01

457

Cellulose binding domain proteins  

SciTech Connect

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

458

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

459

Antiferromagnetic domain walls  

Microsoft Academic Search

Antiferromagnetic domain walls are shown to exhibit a nonvanishing total magnetic moment. This result is established numerically for a discrete spin system, as well as analytically within a suitable continuum approximation that leads to the nonlinear sigma model extended to include anisotropy. The moment is due to certain parity-breaking terms that are implicit in arguments pertaining to the Haldane gap

N. Papanicolaou

1995-01-01

460

Dynamic measurement of inside strain distributions in adhesively bonded joints by embedded fiber Bragg grating sensor  

NASA Astrophysics Data System (ADS)

Long-length fiber Bragg grating (FBG) with the length of about 100 mm was embedded onto the surface of a carbon fiber reinforced plastics (CFRP) substrate and two CFRP adherends were joined by adhesive to form an adhesive bonded single-lap joint. The joint was subjected to 0.5 Hz cyclic tensile load and longitudinal strain distributions along FBG were measured at 5 Hz by the fiber-optic distributed sensing system based on optical frequency domain reflectometry (OFDR). We could successfully monitor the strain distributions accurately with high spatial resolution of around 1 mm.

Murayama, Hideaki; Ning, Xiaoguang; Kageyama, Kazuro; Wada, Daichi; Igawa, Hirotaka

2014-05-01

461

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

462

44 CFR 150.5 - Joint Public Safety Awards Board.  

Code of Federal Regulations, 2010 CFR

... 2010-10-01 2010-10-01 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...

2010-10-01

463

Interrogating domain-domain interactions with parsimony based approaches  

PubMed Central

Background The identification and characterization of interacting domain pairs is an important step towards understanding protein interactions. In the last few years, several methods to predict domain interactions have been proposed. Understanding the power and the limitations of these methods is key to the development of improved approaches and better understanding of the nature of these interactions. Results Building on the previously published Parsimonious Explanation method (PE) to predict domain-domain interactions, we introduced a new Generalized Parsimonious Explanation (GPE) method, which (i) adjusts the granularity of the domain definition to the granularity of the input data set and (ii) permits domain interactions to have different costs. This allowed for preferential selection of the so-called "co-occurring domains" as possible mediators of interactions between proteins. The performance of both variants of the parsimony method are competitive to the performance of the top algorithms for this problem even though parsimony methods use less information than some of the other methods. We also examined possible enrichment of co-occurring domains and homo-domains among domain interactions mediating the interaction of proteins in the network. The corresponding study was performed by surveying domain interactions predicted by the GPE method as well as by using a combinatorial counting approach independent of any prediction method. Our findings indicate that, while there is a considerable propensity towards these special domain pairs among predicted domain interactions, this overrepresentation is significantly lower than in the iPfam dataset. Conclusion The Generalized Parsimonious Explanation approach provides a new means to predict and study domain-domain interactions. We showed that, under the assumption that all protein interactions in the network are mediated by domain interactions, there exists a significant deviation of the properties of domain interactions mediating interactions in the network from that of iPfam data. PMID:18366803

Guimarães, Katia S; Przytycka, Teresa M

2008-01-01

464

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

465

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''.

R, Woolley

2005-10-07

466

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

467

Joint stabilizing projects in defense  

SciTech Connect

Joint defensive projects could increase stability and decrease the alert rates of strategic forces. Areas include the defense of the US, Commonwealth of Independent States (CIS), and their allies against third world threats; protection against each other's accidental or unauthorized launches; and defense against intentional attacks. The most promising area appears to be defining interfaces for the handover of satellite warning and trajectory information, which applies to most phases of theater defense and mutual protection. 19 refs.

Canavan, G.H.; Browne, J.C.; Joseph, R.J.

1992-06-01

468

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

469

Space Suit Joint Torque Testing  

NASA Technical Reports Server (NTRS)

In 2009 and early 2010, a test was performed to quantify the torque required to manipulate joints in several existing operational and prototype space suits in an effort to develop joint torque requirements appropriate for a new Constellation Program space suit system. The same test method was levied on the Constellation space suit contractors to verify that their suit design meets the requirements. However, because the original test was set up and conducted by a single test operator there was some question as to whether this method was repeatable enough to be considered a standard verification method for Constellation or other future space suits. In order to validate the method itself, a representative subset of the previous test was repeated, using the same information that would be available to space suit contractors, but set up and conducted by someone not familiar with the previous test. The resultant data was compared using graphical and statistical analysis and a variance in torque values for some of the tested joints was apparent. Potential variables that could have affected the data were identified and re-testing was conducted in an attempt to eliminate these variables. The results of the retest will be used to determine if further testing and modification is necessary before the method can be validated.

Valish, Dana J.

2011-01-01

470

The Joint Damping Experiment (JDX)  

NASA Technical Reports Server (NTRS)

The Joint Damping Experiment (JDX), flown on the Shuttle STS-69 Mission, is designed to measure the influence of gravity on the structural damping of a high precision three bay truss. Principal objectives are: (1) Measure vibration damping of a small-scale, pinjointed truss to determine how pin gaps give rise to gravity-dependent damping rates; (2) Evaluate the applicability of ground and low-g aircraft tests for predicting on-orbit behavior; and (3) Evaluate the ability of current nonlinear finite element codes to model the dynamic behavior of the truss. Damping of the truss was inferred from 'Twang' tests that involve plucking the truss structure and recording the decay of the oscillations. Results are summarized as follows. (1) Damping, rates can change by a factor of 3 to 8 through changing the truss orientation; (2) The addition of a few pinned joints to a truss structure can increase the damping by a factor as high as 30; (3) Damping is amplitude dependent; (4) As gravity induced preloads become large (truss long axis perpendicular to gravity vector) the damping is similar to non-pinjointed truss; (5) Impacting in joints drives higher modes in structure; (6) The torsion mode disappears if gravity induced preloads are low.

Folkman, Steven L.; Bingham, Jeff G.; Crookston, Jess R.; Dutson, Joseph D.; Ferney, Brook D.; Ferney, Greg D.; Rowsell, Edwin A.

1997-01-01

471

Mechanical flexible joint design document  

NASA Technical Reports Server (NTRS)

The purpose of this report is to document the status of the Mechanical Flexible Joint (MFJ) Design Subtask with the intent of halting work on the design. Recommendations for future work is included in the case that the task is to be resumed. The MFJ is designed to eliminate two failure points from the current flex joint configuration, the inner 'tripod configuration' and the outer containment jacket. The MFJ will also be designed to flex 13.5 degrees and have three degrees of freedom. By having three degrees of freedom, the MFJ will allow the Low Pressure Fuel Duct to twist and remove the necessity to angulate the full 11 degrees currently required. The current flex joints are very labor intensive and very costly and a simple alternative is being sought. The MFJ is designed with a greater angular displacement, with three degrees of freedom, to reside in the same overall envelope, to meet weight constraints of the current bellows, to be compatible with cryogenic fuel and oxidizers, and also to be man-rated.

Daily, Vic

1993-01-01

472

Experimental simulation of joint morphology  

NASA Astrophysics Data System (ADS)

Desiccation experiments with starch-water mixtures whose dimensions and thickness are several centimeters produce a broad spectrum of tensile cracks. Their properties are remarkably similar to those of joints in rocks. This note concentrates on crack morphology in the form of plumose structures and fringe zones. Moreover, rupture velocity is determined from videos. After an initial, dynamic rupture phase with velocities of about 100 mm/s, which is restricted to a thin, strongly dried surface layer, the main rupture through the specimen is quasi-static with velocities of 10 mm/min and less. This phase is driven by the low supply of strain energy due to the ongoing desiccation. Quasi-static rupture produces plumose topographies, which range from simple to complex. From the similarity of plumose topography on joints in marine sedimentary rocks, it is hypothesized that these joints are generated by quasi-static rupture in an early stage of subsidence, compaction and diagenesis of water-bearing sediments. Rupture propagation in the fringe zone of cracks in starch, where topography is stronger than on the main crack, was slower than over the main crack. The same applies probably to fringe zones along bedding planes in sediments.

Müller, Gerhard

2001-01-01

473

Bayesian tree-structured image modeling using wavelet-domain hidden Markov models  

Microsoft Academic Search

Wavelet-domain hidden Markov models have proven to be useful tools for statistical signal and image processing. The hidden Markov tree (HMT) model captures the key features of the joint probability density of the wavelet coefficients of real-world data. One potential drawback to the HMT framework is the need for computationally expensive iterative training to fit an HMT model to a

Justin K. Romberg; Hyeokho Choi; Richard G. Baraniuk

2001-01-01

474

Single-carrier frequency-domain equalization for STBC transmission system based on multiple blocks modulation  

Microsoft Academic Search

A block modulated (BM) algorithm is proposed for STBC block transmission system combined with single carrier frequency domain equalization (SC-FDE) with two transmit antennas and one receive antenna, and the system redundancy caused by cyclic prefix (CP) is evidently reduced. At the transmitter, multiple blocks are jointly modulated and framed together, so one single CP is shared by the multiple

Jieling Wang; Hong Yang; Kechu Yi

2009-01-01

475

Domain Specific Search Engines  

Microsoft Academic Search

This Chapter discusses the advantages and limitations of domain specific search engine technology for the development of tourism web portals. The case example outlined here focuses on www.visiteuropeancities.info - the European Cities Tour- ism Portal, the B2C site offered by European Cities Tourism, a pan-European as- sociation of currently 90 European city tourism boards representing more than 30 European countries.

Karl W. Wöber

476

Domain wall oscillators  

NASA Astrophysics Data System (ADS)

Domain wall (DW) oscillators have recently acquired a huge amount of research interest, due to their promising easy tunability along with the miniature single-layered structure. The output frequency control of DW oscillator through magnetic field and current has been studied in detail; but, there are issues yet to be addressed. Here, we propose several designs of DW oscillators and try to address some issues of control, output frequency and input power.

Ghosh, Bahniman; Solanki, Gaurav

2015-01-01

477

Domain wall oscillators  

NASA Astrophysics Data System (ADS)

Domain wall (DW) oscillators have recently acquired a huge amount of research interest, due to their promising easy tunability along with the miniature single-layered structure. The output frequency control of DW oscillator through magnetic field and current has been studied in detail; but, there are issues yet to be addressed. Here, we propose several designs of DW oscillators and try to address some issues of control, output frequency and input power.

Ghosh, Bahniman; Solanki, Gaurav

2014-09-01

478

Special polyhedra for Reinhardt domains  

E-print Network

We show that every bounded hyperconvex Reinhardt domain can be approximated by special polynomial polyhedra defined by homogeneous polynomial mappings. This is achieved by means of approximation of the pluricomplex Green function of the domain with pole at the origin.

Rashkovskii, Alexander

2011-01-01

479

User-defined subroutine for implementation of special finite elements in ABAQUS for the analysis of adhesive joints  

Microsoft Academic Search

A user-defined subroutine has been developed to implement special 2-D and 3-D layered continuum elements in the commercial finite element program ABAQUS. These elements are specially configured to accurately predict interface stresses in adhesively bonded joints and are formulated using the hybrid stress technique to explicitly enforce stress equilibrium throughout the element domain and stress continuity conditions at layer interfaces.

Erik Saether; Kristen Weight

1994-01-01

480

Biotribology of artificial hip joints.  

PubMed

Hip arthroplasty can be considered one of the major successes of orthopedic surgery, with more than 350000 replacements performed every year in the United States with a constantly increasing rate. The main limitations to the lifespan of these devices are due to tribological aspects, in particular the wear of mating surfaces, which implies a loss of matter and modification of surface geometry. However, wear is a complex phenomenon, also involving lubrication and friction. The present paper deals with the tribological performance of hip implants and is organized in to three main sections. Firstly, the basic elements of tribology are presented, from contact mechanics of ball-in-socket joints to ultra high molecular weight polyethylene wear laws. Some fundamental equations are also reported, with the aim of providing the reader with some simple tools for tribological investigations. In the second section, the focus moves to artificial hip joints, defining materials and geometrical properties and discussing their friction, lubrication and wear characteristics. In particular, the features of different couplings, from metal-on-plastic to metal-on-metal and ceramic-on-ceramic, are discussed as well as the role of the head radius and clearance. How friction, lubrication and wear are interconnected and most of all how they are specific for each loading and kinematic condition is highlighted. Thus, the significant differences in patients and their lifestyles account for the high dispersion of clinical data. Furthermore, such consideration has raised a new discussion on the most suitable in vitro tests for hip implants as simplified gait cycles can be too far from effective implant working conditions. In the third section, the trends of hip implants in the years from 2003 to 2012 provided by the National Joint Registry of England, Wales and Northern Ireland are summarized and commented on in a discussion. PMID:25621213

Di Puccio, Francesca; Mattei, Lorenza

2015-01-18

481

Biotribology of artificial hip joints  

PubMed Central

Hip arthroplasty can be considered one of the major successes of orthopedic surgery, with more than 350000 replacements performed every year in the United States with a constantly increasing rate. The main limitations to the lifespan of these devices are due to tribological aspects, in particular the wear of mating surfaces, which implies a loss of matter and modification of surface geometry. However, wear is a complex phenomenon, also involving lubrication and friction. The present paper deals with the tribological performance of hip implants and is organized in to three main sections. Firstly, the basic elements of tribology are presented, from contact mechanics of ball-in-socket joints to ultra high molecular weight polyethylene wear laws. Some fundamental equations are also reported, with the aim of providing the reader with some simple tools for tribological investigations. In the second section, the focus moves to artificial hip joints, defining materials and geometrical properties and discussing their friction, lubrication and wear characteristics. In particular, the features of different couplings, from metal-on-plastic to metal-on-metal and ceramic-on-ceramic, are discussed as well as the role of the head radius and clearance. How friction, lubrication and wear are interconnected and most of all how they are specific for each loading and kinematic condition is highlighted. Thus, the significant differences in patients and their lifestyles account for the high dispersion of clinical data. Furthermore, such consideration has raised a new discussion on the most suitable in vitro tests for hip implants as simplified gait cycles can be too far from effective implant working conditions. In the third section, the trends of hip implants in the years from 2003 to 2012 provided by the National Joint Registry of England, Wales and Northern Ireland are summarized and commented on in a discussion. PMID:25621213

Di Puccio, Francesca; Mattei, Lorenza

2015-01-01

482

Semiconstrained Distal Radioulnar Joint Prosthesis  

PubMed Central

Distal radioulnar joint (DRUJ) problems can occur as a result of joint instability, abutment, or incongruity. The DRUJ is a weight-bearing joint; the ulnar head is frequently excised either totally or partially, and in some cases it is fused, because of degenerative, rheumatoid, or posttraumatic arthritis. Articles about these procedures report the ability to pronate and supinate, but they rarely discuss grip strength, and even less do they address lifting capacity. We report the long term results of the first 35 patients who underwent total DRUJ arthroplasty with the Aptis DRUJ prosthesis after 5 years follow-up. Surgical indications were all causes of dysfunctional DRUJ (degenerative, posttraumatic, autoimmune, congenital). We recorded data for patient demographics, range of motion (ROM), strength, and lifting capacity of the operated and of the nonoperated extremity. Pain and functional assessments were also recorded. The Aptis DRUJ prosthesis, a bipolar self-stabilizing DRUJ endoprosthesis that restores forearm function, consists of a semiconstained and modular implant designed to replace the function of the ulnar head, the sigmoid notch of the radius, and the triangular fibrocartilage ligaments. The surgical technique is presented in detail. The majority of the patients regained adequate ROM and improved their strength and lifting capacity to the operated side. Pain and activities of daily living were improved. Twelve patients experienced complications, most commonly being extensor carpi ulnaris (ECU) tendinitis, ectopic bone formation, bone resorption with stem loosening, low-grade infection, and need for ball replacement. The Aptis total DRUJ replacement prosthesis is an alternative to salvage procedures that enables a full range of motion as well as the ability to grip and lift weights encountered in daily living activities. PMID:24436788

Savvidou, Christiana; Murphy, Erin; Mailhot, Emilie; Jacob, Shushan; Scheker, Luis R.

2013-01-01

483

Joint Center for Artificial Photosynthesis  

ScienceCinema

The Joint Center for Artificial Photosynthesis (JCAP) is the nation's largest research program dedicated to the development of an artificial solar-fuel generation technology. Established in 2010 as a U.S. Department of Energy (DOE) Energy Innovation Hub, JCAP aims to find a cost-effective method to produce fuels using only sunlight, water, and carbon dioxide as inputs. JCAP brings together more than 140 top scientists and researchers from the California Institute of Technology and its lead partner, Berkeley Lab, along with collaborators from the SLAC National Accelerator Laboratory, and the University of California campuses at Irvine and San Diego.

Koval, Carl; Lee, Kenny; Houle, Frances; Lewis, Nate

2013-12-19

484

Joint Center for Artificial Photosynthesis  

SciTech Connect

The Joint Center for Artificial Photosynthesis (JCAP) is the nation's largest research program dedicated to the development of an artificial solar-fuel generation technology. Established in 2010 as a U.S. Department of Energy (DOE) Energy Innovation Hub, JCAP aims to find a cost-effective method to produce fuels using only sunlight, water, and carbon dioxide as inputs. JCAP brings together more than 140 top scientists and researchers from the California Institute of Technology and its lead partner, Berkeley Lab, along with collaborators from the SLAC National Accelerator Laboratory, and the University of California campuses at Irvine and San Diego.

Koval, Carl; Lee, Kenny; Houle, Frances; Lewis, Nate

2013-12-10

485

Space nuclear system expansion joints  

NASA Technical Reports Server (NTRS)

The engineering, design, and fabrication status of the expansion joint unit (EJU) to be employed in the NaK primary coolant piping loop of the 5-kwe Reactor thermoelectric system are described. Four EJU's are needed in the NaK primary coolant piping loop. The four EJU's which will be identical, utilize bellows as the flexing member, are hermetically sealed, and provide double containment. The bellows are of a nested-formed design, and are to be constructed of 1-ply thickness of 0.010-in. Inconel 718. The EJU's provide a minimum piping load margin of safety of +0.22.

Whitaker, W. D.; Shimazki, T. T.

1973-01-01

486

Automatic locking knee brace joint  

NASA Technical Reports Server (NTRS)

This invention is an apparatus for controlling the pivotal movement of a knee brace comprising a tang-and-clevis joint that has been uniquely modified. Both the tang and the clevis have a set of teeth that, when engaged, can lock the tang and the clevis together. In addition, the tang is biased away from the clevis. Consequently, when there is no axial force (i.e., body weight) on the tang, the tang is free to pivot within the clevis. However, when an axial force is exerted on the tang, the tang is pushed into the clevis, both sets of teeth engage, and the tang and the clevis lock together.

Weddendorf, Bruce (inventor)

1995-01-01

487

Fellows Celebrated at Joint Assembly  

NASA Astrophysics Data System (ADS)

The 2009 AGU Fellows were presented at the recent Joint Assembly in Toronto, Ontario, Canada. At a formal ceremony on 26 May 2009, AGU President Timothy L. Grove 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. AGU Fellows are scientists who have attained “acknowledged eminence in the geophysical sciences.” Election to AGU Fellowship is a very high recognition by one's peers. The number of Fellows elected may not exceed 0.1% of the membership in any given year.

2009-06-01

488

Management of temporomandibular joint ankylosis.  

PubMed

Temporomandibular joint (TMJ) ankylosis is a pathologic condition where the mandible is fused to the fossa by bony or fibrotic tissues. This interferes with mastication, speech, oral hygiene, and normal life activities, and can be potentially life threatening when struggling to acquire an airway in an emergency. Trauma is the most common cause of TMJ ankylosis, followed by infection. Diagnosis of TMJ ankylosis is usually made by clinical examination and imaging studies. The management goal in TMJ ankylosis is to increase the patient's mandibular function, correct associated facial deformity, decrease pain, and prevent reankylosis. PMID:25483442

Movahed, Reza; Mercuri, Louis G

2015-02-01

489