Wide-band White Noise Research Articles

A Joint State-Parameter Identification Algorithm of a Structure with Non-Diagonal Mass Matrix Based on UKF with Unknown Mass

Inaccurate mass estimates have been recognized as an important source of uncertainty in structural identification, especially for large-scale structures with old ages. Over the past decades, some identification algorithms for structural states and unknown parameters, including unknown mass, have been proposed by researchers. However, most of these identification algorithms are based on the simplified mechanical model of chain-like structures. For a chain-like structure, the mass matrix and its inverse matrix are diagonal matrices, which simplify the difficulty of identifying the structure with unknown mass. However, a structure with a non-diagonal mass matrix is not of such a simple characteristic. In this paper, an online joint state-parameter identification algorithm based on an Unscented Kalman filter (UKF) is proposed for a structure with a non-diagonal mass matrix under unknown mass using only partial acceleration measurements. The effectiveness of the proposed algorithm is verified by numerical examples of a beam excited by wide-band white noise excitation and a two-story one-span plane frame structure excited by filtered white noise excitation generated according to the Kanai–Tajimi power spectrum. The identification results show that the proposed algorithm can effectively identify the structural state, unknown stiffness, damping and mass parameters of the structures.

Constant-Beamwidth Kronecker Product Beamforming With Nonuniform Planar Arrays

In this paper, we address the problem of constant-beamwidth beamforming using nonuniform planar arrays. We propose two techniques for designing planar beamformers that can maintain different beamwidths in the XZ and YZ planes based on constant-beamwidth linear arrays. In the first technique, we utilize Kronecker product beamforming to find the weights, thus eliminating matrix inversion. The second technique provides a closed-form solution that allows for a tradeoff between white noise gain and directivity factor. The second technique is applicable even when only a subset of the sensors is used. Since our techniques are based on linear arrays, we also consider symmetric linear arrays. We present a method that determines where sensors should be placed to maximize the directivity and increase the frequency range over which the beamwidth remains constant, with a minimal number of sensors. Simulations demonstrate the advantages of the proposed design methods compared to the state-of-the-art. Specifically, our method yields a 1000-fold faster runtime than the competing method, while improving the wideband directivity factor by over 8 dB without compromising the wideband white noise gain in the simulated scenario.

Interaction of Background Noise and Auditory Hallucinations on Phonemic Mismatch Negativity (MMN) and P3a Processing in Schizophrenia.

Auditory hallucinations (AHs) are among the cardinal symptoms of schizophrenia (SZ). During the presence of AHs aberrant activity of auditory cortices have been observed, including hyperactivation during AHs alone and hypoactivation when AHs are accompanied by a concurrent external auditory competitor. Mismatch negativity (MMN) and P3a are common ERPs of interest within the study of SZ as they are robustly reduced in the chronic phase of the illness. The present study aimed to explore whether background noise altered the auditory MMN and P3a in those with SZ and treatment-resistant AHs.MethodsMMN and P3a were assessed in 12 hallucinating patients (HPs), 11 non-hallucinating patients (NPs) and 9 healthy controls (HCs) within an auditory oddball paradigm. Standard (P = 0.85) and deviant (P = 0.15) stimuli were presented during three noise conditions: silence (SL), traffic noise (TN), and wide-band white noise (WN).ResultsHPs showed significantly greater deficits in MMN amplitude relative to NPs in all background noise conditions, though predominantly at central electrodes. Conversely, both NPs and HPs exhibited significant deficits in P3a amplitude relative to HCs under the SL condition only.SignificanceThese findings suggest that the presence of AHs may specifically impair the MMN, while the P3a appears to be more generally impaired in SZ. That MMN amplitudes are specifically reduced for HPs during background noise conditions suggests HPs may have a harder time detecting changes in phonemic sounds during situations with external traffic or “real-world” noise compared to NPs.

DYNAMIC BEHAVIOR OF TWO ELASTICALLY CONNECTED NANOBEAMS UNDER A WHITE NOISE PROCESS

This paper investigates the almost-sure and moment stability of a double nanobeam system under stochastic compressive axial loading. By means of the Lyapunov exponent and the moment Lyapunov exponent method the stochastic stability of the nano system is analyzed for different system parameters under an axial load modeled as a wideband white noise process. The method of regular perturbation is used to determine the explicit asymptotic expressions for these exponents in the presence of small intensity noises.

Lower Rao–Cramer Boundary of Variances for Parameter Joint Estimates of Narrowband and Broadband Signals Mixture with White Noise

In this paper, we determine the joint estimates variance minimum of the signal parameters, a mixture of narrowband and wideband signals and white Gaussian noise that are presented as a complex total signal. An expression is obtained for calculating the Fisher matrix elements to establish the lower Rao–Cramer boundary. The dependences of the standard deviations (RMS) of the estimates on the signal-to-noise ratio, sample length, and on the initial signal parameters, such as the central frequencies of the signal components and the width of the broadband component, are presented. A comparison with the minimal standard deviations obtained for a signal model that includes only the broadband component is performed. Analysis of the results allows assessing the requirements that may be imposed on the developed algorithms for joint estimation of the mixture parameters of the considered signals depending on the set values of the sampling frequency and the sample size.

Experimental validation of the proposed extended Kalman filter with unknown inputs algorithm based on data fusion

The extended Kalman filter is a useful tool in the research of structural health monitoring and vibration control. However, the traditional extended Kalman filter approach is only applicable when the information of external inputs to structures is available. In recent years, some improved extended Kalman filter methods applied with unknown inputs have been proposed. The authors have proposed an extended Kalman filter with unknown inputs based on data fusion of partially measured displacement and acceleration responses. Compared with previous approaches, the drifts in the estimated structural displacements and unknown external inputs can be avoided. The feasibility of proposed extended Kalman filter with unknown inputs has been demonstrated by some numerical simulation examples. However, experimental validation of the proposed extended Kalman filter with unknown inputs has not been conducted. In this paper, an experiment is conducted to validate the effectiveness of the proposed approach. A five-story shear building model subjected to an unknown external excitation of wide-band white noise is conducted. Moreover, the data fusion of partially measured strain and acceleration responses from the building is adopted as it is difficult to accurately measure structural displacement in practice. Identified results show that the recently proposed extended Kalman filter with unknown inputs can be applied to identify structural parameters, structural states, and the unknown inputs in real time.

Measuring the effect of high-speed video data on the audio-visual speech recognition accuracy

Introduction: The effectiveness of modern automatic speech recognition systems in quiet acoustic conditions is quite high and reaches 90-95%. However, in noisy uncontrolled environment, acoustic signals are often distorted, which greatly reduces the resulting recognition accuracy. In adverse conditions, it seems appropriate to use the visual information about the speech, as it is not affected by the acoustic noise. At the moment, there are no studies which objectively reflect the dependence of visual speech recognition accuracy on the video frame rate, and there are no relevant audio-visual databases for model training. Purpose : Improving the reliability and accuracy of the automatic audio-visual Russian speech recognition system; collecting representative audio-visual database and developing an experimental setup. Methods : For audio-visual speech recognition, we used coupled hidden Markov model architectures. For parametric representation of audio and visual features, we used mel-frequency cepstral coefficients and principal component analysis-based pixel features. Results: In the experiments, we studied 5 different rates of video data: 25, 50, 100, 150, and 200 fps. Experiments have shown a positive effect from the use of a high-speed video camera: we achieved an absolute increase in accuracy of 1.48% for a bimodal system and 3.10% for a unimodal one, as compared to the standard recording speed of 25 fps. During the experiments, test data for all speakers were added with two types of noise: wide-band white noise and “babble noise”. Analysis shows that bimodal speech recognition exceeds unimodal in accuracy, especially for low SNR values <15 dB. At very low SNR values <5 dB, the acoustic information becomes non-informative, and the best results are achieved by a unimodal visual speech recognition system. Practical relevance : The use of a high-speed camera can improve the accuracy and robustness of a continuous audio-visual Russian speech recognition system.

Signal-Folding for Range-Enhanced Acquisition and Reconstruction

Signal-folding architecture with digital reconstruction reduces the signal amplitude at the input of an acquisition ADC and thus provides a larger effective system input range. Digital processing unfolds the signal after quantization. Three algorithms are investigated which operate with a maximum of four samples per realignment point and thus yield for a small potential hardware implementation and low computational load. A rigorous analysis of both the realignment error and the effect of wide band white noise is provided and confirmed by simulation and measurement. Noise in the folded signal must be carefully managed as it is integrated by realignment. It is found that quantization noise may dominate the system output noise and dynamic range. The approach is useful when large amplitude interference must be accommodated superimposed on a target signal and when the ADC resolution is high (typically $\geq$ 10 bit).

Analysis on Ranging and Velocity Measurement Performance of DS/FH Hybrid Spread Spectrum Signal

The measurement performance with the interference is presented with the new DS/FH hybrid spread spectrum signal system. The DS/FH system model is established. The change of the SNR ratio is obtained by analyzing the characteristics of three kinds of interference signal such as partial-band noise jamming (PBNJ), wide-band noise jamming (WBNJ) and additive white Gaussian noise (AWGN). Then the ranging and velocity measurement performance is got through the simulation.

Plasma diffusion in self-consistent fluctuations

The problem of particle diffusion in position space, as a consequence of electromagnetic fluctuations is addressed. Numerical results obtained with a self-consistent hybrid code are presented, and a method to calculate diffusion coefficient in the direction perpendicular to the mean magnetic field is proposed. The diffusion is estimated for two different types of fluctuations. The first type (resulting from an agyrotropic initial setting) is stationary, wide band white noise, and associated to Gaussian probability distribution function for the magnetic fluctuations. The second type (resulting from a Kelvin-Helmholtz instability) is non-stationary, with a power-law spectrum, and a non-Gaussian probability distribution function. The results of the study allow revisiting the question of loading particles of solar wind origin in the Earth magnetosphere.

Vertical vibration characteristics of seated human bodies and a biodynamic model with two degrees of freedom

Understanding the vibration characteristics of a seated human body is critical for evaluation and improvement of ride comfort of various passenger vehicles. There have been very little publications about the vibration characteristics of a seated Chinese human body. By using wide-band white noise excitations and a homemade seat sensor, vertical vibration tests were carried out on 28 volunteers. Apparent masses were obtained for each volunteer at a frequency range of 1–20 Hz for various excitation levels. A biodynamic model, which has two degrees of freedom in parallel and includes a frame mass, was chosen to describe the vertical vibration characteristics of the seated human body. The model parameters were identified by means of a Gauss-Newton method with an error function defined in terms of both real and imaginary parts of the apparent mass against frequency. Based on the averaged data of the mass-normalized apparent mass from experiments, the model parameters and corresponding modal parameters were obtained for seated Chinese people at ages of 20–25 with standard weight. The apparent masses predicted by the biodynamic model with identified parameters agree very well with those obtained from experiments. Statistical analysis demonstrates the influence of volunteer’s height and weight on the model parameters for a seated human body.

Spectrum sensing cognitive‐wave‐radio for interference identification in wireless communications

AbstractPhysical layer of cognitive‐wave‐radio receiver is investigated to identify interference signals, by spectrum sensing, in the presence of received QPSK data at 20 Mbps. The investigated cognitive‐wave‐radio receiver structure is based on existing wave radio physical layer (six‐port receiver interferometer) adapted for the receiver data active cancellation. For active cancellation of the received digital data, four outputs of the standard wave radio receiver are used in conjunction with three “single pole double throw” switches providing a single output of the “zero state time interval” for spectrum sensing of the interference signal. Two interference signals were tested: a 7‐dBm amplitude modulated interference and a wide band white noise with 0.01 mW/MHz. The microwave carrier of the QPSK signal is set at an amplitude of 16 dBm and a carrier frequency of 3.5 GHz. Once the interference signal spectrum is identified, the QPSK data are transmitted through the available channel. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:195–200, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25670

Feature Extraction for Crack Detection in Rain Conditions

The solution of the features selection problem is critical for robust detection of crack signals in noisy environment, varying from short-time impulses such as raindrops to the wide-band white Gaussian noise. In this paper, two novel feature selection methods were used to reduce an initial set of 90 features, 67 estimated in the time domain and 23 in the frequency domain, decreasing significantly the memory requirements and the computational complexity of a Radial-Basis-Function (RBF) cracks detector. The evaluation process is carried out in a database including of more than 6000 cracks, raindrops and simultaneous crack and raindrops signals. Additive white Gaussian noise is used to distort the real signals at −20 to 20 dB Signal to Noise Ratio (SNR). The experimental results show that the number of features can be reduced to approximately 25, without affecting the classification rate of cracks and raindrops in the noisy signals, if the SNR is better than 0 dB. In noise-free environment a classification rate of 91% for a single crack/raindrop event is achieved using only five features. A different set of five features reaches a rate of 85% at 10 dB SNR.

The role of low frequency components in median plane localization.

The high frequency components of an auditory stimulus are considered to be the primary contribution to median plane localization. However, a number of studies have demonstrated that the low frequency components of a stimulus are also important in median plane localization. Asano et al. concluded that important cues for front-back discrimination seem to exist in the frequency range below 2 kHz. In the present paper, localization tests were performed in order to examine the contribution of low frequency components to median plane localization. In these tests, the higher (above 4,800 Hz) and lower (below 4,800 Hz) frequency components, respectively, of a wide-band white noise were simultaneously presented from different directions so that the individual components provided different directional information. The results of these tests reveal that: (1) when the source is a wide-band signal, the higher frequency components are dominant in median plane localization, whereas the lower frequency components do not contribute significantly to the localization, and (2) important cues for front-back discrimination do not exist in the low frequency range.

Numerical analysis of dynamic stability under random excitation

It is well known that an elastic column subjected to a harmonically-varying axial force exhibits parametric resonance over a range of applied frequencies and amplitudes. In this paper, the effect of white noise on the dynamic stability properties of a model system is investigated. Because of the complex nature of the applied loads and the nonlinearity of the governing equilibrium equation, three different numerical integration procedures are considered for determining the response of the model structure, and the accuracy of each scheme is studied. Results from the numerical investigation show that the method of Successive Symmetric Quadratures provides greater accuracy than the conventional Newmark Method or Harmonic Acceleration Method for nonlinear dynamic systems under random excitation. Computation of the model response shows that band-limited low frequency noise can limit the maximum deformation of the model system relative to the unperturbed case. Wide-band white noise, however, was observed only to enhance the destabilizing effect of the applied loads.

Entrenamiento auditivo con ruido blanco de banda ancha: efectos sobre la discriminación verbal (ii)

AbstractThe auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band white modified noise. In a prospective study, we have assessed the modifications of the verbal reception threshold URV), the maximum discrimination (Dmax), and the discrimination coefficient (Kd) in a sample of 48 patients, who have followed a program of 15 auditory training with wide-band white noise sessions. The average improvements of the verbal discrimination variables expressed in percentage are 4.23% for the URV, a 9.04% for the kd, a 17.87% for the Dmax, and 4.32%, 10.05%, 13.04% for the binaural URV, Kd and Dmax respectively. From our results, it can be deduced that the auditory training with wide-band white noise improves the verbal discrimination measures. Not only it allows to reach the verbal reception threshold at a lower intensity, but also it moves the discrimination line towards the left. Furthermore, it increases the maximum discrimination both in binaural measurements and in those which consider all the ears.

Entrenamiento auditivo con ruido blanco de banda ancha

The auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band modified noise which we will call "K-noise". The auditory trainer GAES 100 KT is a voice amplifier device with earphone outlets. It incorporates a wide-band noise generator which produces a noise that is a mixture of all the audibles frequencies. Therefore, it estimulates all the sensory cells in the organ of Corti, but from 1000 Hz it has a progressive fall towards the high pitch of 6 db per octave. This device consists of a series of controls which make possible to apply both the noise and the phonetic materials -texts and words lists that the therapist´s voice presents- to either one of the ears or to both of them, in diffferent intensities and for different periods of time. In this first article of our study of the auditory training with wide-band white noise we will review the different methods of hearing training and present not only the basic concepts on auditory training, but also the systematic we have followed to apply it.

Entrenamiento auditivo con ruido blanco de banda ancha: Efectos sobre el reclutamiento (III)

The auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band white modified noise. In a prospective study, we have assessed the modifications of the recruitment coefficient in a sample of 48 patients who have followed a program of 15 auditory training with wide- band white noise sessions. The average improvement of the recruitment coefficient expressed in percentage is a 7.7498%, which comes up to 23.5249% in the case of a binaural recruitment coefficient. From our results, it can be deduced that the auditory training with wide-band white noise reduces the recruitment. That is to say, the decrease of the recruitment in high intensities both binaurally and in all ears.

Entrenamiento auditivo con ruido blanco de banda ancha: efectos sobre la algiacusia y los umbrales tonales (iv)

AbstractThe auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band white modified noise. In a prospective study, we have assessed the modifications of the total auditory threshold (UAt), the conversational auditory threshold (UAc), and the pain threshold (Ud) in a sample of 48 patients, who have followed a program of 15 auditory training with wide-band white noise sessions. The average improvements of the variables expressed in percentage are 0.78% for the UAt, 0.64% for the UAc, and 5.31% for the Ud. From our results, it can be deduced that the auditory training with wideband white noise does not modify the pure tone thresholds, but it moves the pain threshold towards higher intensities, enlarging the dinamic auditory field.

An integrated CMOS microluminometer for low-level luminescence sensing in the bioluminescent bioreporter integrated circuit

We report an integrated CMOS microluminometer for the detection of low-level bioluminescence in whole cell biosensing applications. This microluminometer is the microelectronic portion of the bioluminescent bioreporter integrated circuit (BBIC). This device uses the n-well/p-substrate junction of a standard bulk CMOS IC process to form the integrated photodetector. This photodetector uses a distributed electrode configuration that minimizes detector noise. Signal processing is accomplished with a current-to-frequency converter circuit that forms the causal portion of the matched filter for dc luminescence in wide-band white noise. Measurements show that luminescence can be detected from as few as 4×10 5 cells/ml.