The Comparative Numerical Experiments of Frequency Features for Earthquake Responds in Liquefiable Field and Elastic Field

2011 ◽  
Vol 90-93 ◽  
pp. 1531-1538
Author(s):  
Jian Ping He ◽  
Wei Zhong Chen
Keyword(s):  
High Frequency ◽  
Essential Feature ◽  
Underground Structure ◽  
Free Field ◽  
Soil Layer ◽  
Low Frequency ◽  
Elastic Field ◽  
Acceleration Response ◽  
Acceleration Amplification ◽  
Frequency Features

The natural frequency characteristics of field has the remarkable influence to the field acceleration response. This paper realized the free field liquefaction numerical simulation experiment based on the Finn model, simultaneously performed the elastic field acceleration response comparative experiment, and has studied the acceleration response frequency features question of liquefiable field. The results indicated that, the acceleration response essential feature of liquefaction field is low-frequency amplification, high frequency reduction. The low-frequency amplification effect is higher than the high frequency reduction effect obviously. The acceleration is amplified in early time and is weakened in later period during the liquefaction process. The acceleration amplification in liquefiable field is remarkable for inputting low frequency waves, the acceleration response is 13 times to input value. Elastic fields also have “low-frequency amplification, high-frequency deflation features”, However, this feature of elastic field is not significant as liquefiable field. At the lower position of liquefiable field acceleration amplification is the largest, at the surface of elastic field acceleration amplification is maximum. The underground structure seismic design in liquefiable field was carried on as in the conventional elastic field, then caused the underground structure to be at the dangerous condition. Researching results will provide a theoretical and experimental basis for the dynamic analysis of underground structures passing through liquefaction soil layer.

Sensitivity to Interaural Temporal Disparities of Low- and High-Frequency Neurons in the Superior Olivary Complex. I. Heterogeneity of Responses

1997 ◽  
Vol 78 (3) ◽  
pp. 1222-1236 ◽  
Author(s):  
Ranjan Batra ◽  
Shigeyuki Kuwada ◽  
Douglas C. Fitzpatrick
Keyword(s):  
Fine Structure ◽  
High Frequency ◽  
Complex I ◽  
General Trend ◽  
Free Field ◽  
Low Frequency ◽  
Superior Olivary Complex ◽  
Field Range ◽  
Multiple Units ◽  
Additional Phase

Batra, Ranjan, Shigeyuki Kuwada, and Douglas C. Fitzpatrick. Sensitivity to interaural temporal disparities of low- and high-frequency neurons in the superior olivary complex. I. Heterogeneity of responses. J. Neurophysiol. 78: 1222–1236, 1997. Interaural temporal disparities (ITDs) are a cue for localization of sounds along the azimuth. Listeners can detect ITDs in the fine structure of low-frequency sounds and also in the envelopes of high-frequency sounds. Sensitivity to ITDs originates in the main nuclei of the superior olivary complex (SOC), the medial and lateral superior olives (MSO and LSO, respectively). This sensitivity is believed to arise from bilateral excitation converging on neurons of the MSO and ipsilateral excitation converging with contralateral inhibition on neurons of the LSO. Here we investigate whether the sensitivity of neurons in the SOC to ITDs can be adequately explained by one of these two mechanisms. Single and multiple units ( n = 124) were studied extracellularly in the SOC of unanesthetized rabbits. We found units that were sensitive to ITDs in the fine structure of low-frequency (<2 kHz) tones and also units that were sensitive to ITDs in the envelopes of sinusoidally amplitude-modulated high-frequency tones. For both categories there were “peak-type” units that discharged maximally at a particular ITD across frequencies or modulation frequencies. These units were consistent with an MSO-type mechanism. There were also “trough-type” units that discharged minimally at a particular ITD. These units were consistent with an LSO-type mechanism. There was a general trend for peak-type units to be located in the vicinity of the MSO and for trough-type units to be located in the vicinity of the LSO. Units of both types appeared to encode ITDs within the estimated free-field range of the rabbit (±300 μs). Many units had varying degrees of irregularities in their responses, which manifested themselves in one of two ways. First, for some units there was no ITD at which the response was consistently maximal or minimal across frequencies. Instead there was an ITD at which the unit consistently responded at some intermediate level. Second, a unit could display considerable jitter from frequency to frequency in the ITD at which it responded maximally or minimally. Units with irregular responses had properties that were continuous with those of other units. They therefore appeared to be variants of peak- and trough-type units. The irregular responses could be modeled by assuming additional phase-locked inputs to a neuron in the MSO or LSO. The function of irregularities may be to shift the ITD sensitivity of a neuron without requiring changes in the anatomic delays of its inputs.

Dynamic Textures Retrieval Using the Integrated Wavelet-Based Surfacelet Transform

2012 ◽  
Vol 263-266 ◽  
pp. 227-230
Author(s):  
Zhi Yong An ◽  
Pei Qiang Liu ◽  
Hai Lan Jiang
Keyword(s):  
High Frequency ◽  
Local Binary Pattern ◽  
Texture Feature ◽  
Low Frequency ◽  
Dynamic Texture ◽  
Directional Filter ◽  
Spatial Features ◽  
Surfacelet Transform ◽  
The Mean ◽  
Frequency Features

To reduce the redundancy, a new integrated wavelet-based surfacelet transform(WBST) is proposed. The integrated WBST is constructed by combining the integrated 3D non-redundant wavelet with nonsubsampled directional filter banks. For 3D non-redundant wavelet transform, there are seven high frequency sub-bands and one high frequency sub-bands. Therefore, we design the integrated scheme with three high frequency sub-bands. In order to get the texture-spatial features, 3D local binary pattern (3D LBP) is used to describe the dynamic texture feature of low frequency sub-band. The mean and standard deviation of coefficients in each sub bands can be used as the high frequency features. Experiments show that the proposed algorithm using the integrated WBST outperforms the 3D WT.

scholarly journals An Unconstrained Face Recognition Method Based on Siamese Networks

2021 ◽  
Author(s):  
Song CunLi ◽  
Shouyong Ji
Keyword(s):  
Neural Network ◽  
Face Recognition ◽  
Network Model ◽  
High Frequency ◽  
Recognition Accuracy ◽  
Recognition Rate ◽  
Low Frequency ◽  
Image Features ◽  
Frequency Features ◽  
Frequency Feature

Abstract It is aimed at the low accuracy and low efficiency of face recognition under unlimited conditions.In this paper, a Siamese neural Network model SN-LF (Siamese Network based on LBP and Frequency Feature perception) is designed based on the Local Binary Pattern (LBP) and the Frequency sensing model.Based on Siamese neural networks, the network adopts circular LBP algorithm and frequency feature perception to realize face recognition under unrestricted conditions.The LBP algorithm can eliminate the influence of light on the image and provide directional input to the network model at the same time.Frequency feature sensing divides the image features into low frequency features and high frequency features. The low frequency features are compressed in the Siamese neural network to increase the recognition efficiency of the network. At the same time, information is exchanged with the high frequency features, so that the target noise data can be eliminated while the feature data is retained.In this way, the recognition rate of the network is maintained, and the computing speed of the network is improved.Simulation experiments are carried out on standard face dataset CASIA-Webface and Yale-B, and compared with other network models. The experimental results show that the proposed SN-LF network structure can improve the recognition accuracy of the algorithm, and achieve a good recognition accuracy.

scholarly journals Nonlinear Behaviour of Concrete Buttress Dams under High-Frequency Excitations Taking into Account Topographical Amplifications

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Roghayeh Abbasiverki ◽  
Richard Malm ◽  
Anders Ansell ◽  
Erik Nordström
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
High Frequency ◽  
Free Field ◽  
Low Frequency ◽  
Nonlinear Behaviour ◽  
One Dimensional ◽  
Field Modelling ◽  
Stream Direction ◽  
Modelling Approach

Concrete buttress dams could potentially be susceptible to high-frequency vibrations, especially in the cross-stream direction, due to their slender design. Previous studies have mainly focused on low-frequency vibrations in stream direction using a simplified foundation model with the massless method, which does not consider topographic amplifications. This paper therefore investigates the nonlinear behaviour of concrete buttress dams subjected to high-frequency excitations, considering cross-stream vibrations. For comparison, the effect of low-frequency excitations is also investigated. The influence of the irregular topography of the foundation surface on the amplification of seismic waves at the foundation surface and thus in the dam is considered by a rigorous method based on the domain-reduction method using the direct finite element method. The sensitivity of the calculated response of the dam to the free-field modelling approach is investigated by comparing the result with analyses using an analytical method based on one-dimensional wave propagation theory and a massless approach. Available deconvolution software is based on the one-dimensional shear wave propagation to transform the earthquake motion from the foundation surface to the corresponding input motion at depth. Here, a new deconvolution method for both shear and pressure wave propagation is developed based on an iterative time-domain procedure using a one-dimensional finite element column. The examples presented showed that topographic amplifications of high-frequency excitations have a significant impact on the response of this type of dam. Cross-stream vibrations reduced the safety of the dam due to the opening of the joints and the increasing stresses. The foundation modelling approach had a significant impact on the calculated response of the dam. The massless method produced unreliable results, especially for high-frequency excitations. The free-field modelling with the analytical method led to unreliable joint openings. It is therefore recommended to use an accurate approach for foundation modelling, especially in cases where nonlinearity is considered.

scholarly journals Multiscale Convolutional Neural Networks with Attention for Plant Species Recognition

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xianfeng Wang ◽  
Chuanlei Zhang ◽  
Shanwen Zhang
Keyword(s):  
Neural Network ◽  
Plant Species ◽  
High Frequency ◽  
Species Recognition ◽  
Low Frequency ◽  
Plant Leaf ◽  
Network Training ◽  
Feature Based ◽  
The Rich ◽  
Frequency Features

Plant species recognition is a critical step in protecting plant diversity. Leaf-based plant species recognition research is important and challenging due to the large within-class difference and between-class similarity of leaves and the rich inconsistent leaves with different sizes, colors, shapes, textures, and venations. Most existing plant leaf recognition methods typically normalize all leaf images to the same size and then recognize them at one scale, which results in unsatisfactory performances. A novel multiscale convolutional neural network with attention (AMSCNN) model is constructed for plant species recognition. In AMSCNN, multiscale convolution is used to learn the low-frequency and high-frequency features of the input images, and an attention mechanism is utilized to capture rich contextual relationships for better feature extraction and improving network training. Extensive experiments on the plant leaf dataset demonstrate the remarkable performance of AMSCNN compared with the hand-crafted feature-based methods and deep-neural network-based methods. The maximum accuracy attained along with AMSCNN is 95.28%.

Lost data reconstruction for structural health monitoring using deep convolutional generative adversarial networks

2020 ◽  
pp. 147592172095922
Author(s):  
Xiaoming Lei ◽  
Limin Sun ◽  
Ye Xia
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
High Frequency ◽  
Low Frequency ◽  
Measured Data ◽  
Data Loss ◽  
Generative Adversarial Network ◽  
Structural Health ◽  
Adversarial Network ◽  
Frequency Features

In the application of structural health monitoring, the measured data might be temporarily or permanently lost due to sensor fault or transmission failure. The measured data with a high data loss ratio undermine its ability for modal identifications and structural condition evaluations. To reconstruct the lost data in the field of structural health monitoring, this study proposes a deep convolutional generative adversarial network which includes a generator with encoder–decoder structure and an adversarial discriminator. The proposed generative adversarial network model needs to understand the content of the complete signals, as well as produce realistic hypotheses for the lost signals. Given the data stably measured before the occurrence of data loss, the generator is trained to extract the features maintained in the data set and reconstruct lost signals using the responses of the remaining functional sensors alone. The discriminator feeds back the distinguished results to the generator to improve its reconstruction accuracy. When training the model, the reconstruction loss and the adversarial loss are employed to better handle the low-frequency features and high-frequency features of the signals. The effectiveness and efficiency of the proposed method are validated by two case studies. As the number of training epoch increases, the reconstructed signals learn the features from low-frequency to high-frequency, and the amplitude of the reconstructed signals gradually increases. It can be seen that the final reconstruction signals match well with the real signals in the time domain and frequency domain. To further demonstrate the applicability of the reconstructed signals in data analysis, the reconstructed acceleration data are used to accurately identify the modal parameters in the numerical case, and the vehicle-induced responses are precisely decomposed from the reconstructed strain data in the field case. Finally, the reconstruction capacity is also investigated with the different numbers of the faulted strain gauges.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Sign in / Sign up

Export Citation Format

Share Document