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Frame Length Dependency for Fundamental Frequency Extraction in Noisy Speech
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作者 Md. Saifur Rahman Any Chowdury +2 位作者 Nargis Parvin Arpita Saha Moinur Rahman 《Journal of Signal and Information Processing》 2024年第1期1-17,共17页
The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extrac... The fundamental frequency plays a significant part in understanding and perceiving the pitch of a sound. The pitch is a fundamental attribute employed in numerous speech-related works. For fundamental frequency extraction, several algorithms have been developed which one to use relies on the signal’s characteristics and the surrounding noise. Thus, the algorithm’s noise resistance becomes more critical than ever for precise fundamental frequency estimation. Nonetheless, numerous state-of-the-art algorithms face struggles in achieving satisfying outcomes when confronted with speech recordings that are noisy with low signal-to-noise ratio (SNR) values. Also, most of the recent techniques utilize different frame lengths for pitch extraction. From this point of view, This research considers different frame lengths on male and female speech signals for fundamental frequency extraction. Also, analyze the frame length dependency on the speech signal analytically to understand which frame length is more suitable and effective for male and female speech signals specifically. For the validation of our idea, we have utilized the conventional autocorrelation function (ACF), and state-of-the-art method BaNa. This study puts out a potent idea that will work better for speech processing applications in noisy speech. From experimental results, the proposed idea represents which frame length is more appropriate for male and female speech signals in noisy environments. 展开更多
关键词 Pitch Estimation fundamental frequency BaNa ACF Frame Length
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TOPOLOGY OPTIMIZATION OF TRUSS STRUCTURE WITH FUNDAMENTAL FREQUENCY AND FREQUENCY DOMAIN DYNAMIC RESPONSE CONSTRAINTS 被引量:8
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作者 Pan Jin Wang De-yu 《Acta Mechanica Solida Sinica》 SCIE EI 2006年第3期231-240,共10页
In this paper, adaptive genetic algorithm (AGA) is applied to topology optimization of truss structure with frequency domain excitations. The optimization constraints include fundamental frequency, displacement resp... In this paper, adaptive genetic algorithm (AGA) is applied to topology optimization of truss structure with frequency domain excitations. The optimization constraints include fundamental frequency, displacement responses under force excitations and acceleration responses under foundation acceleration excitations. The roulette wheel selection operator, adaptive crossover and mutation operators are used as genetic operators. Some heuristic strategies are put forward to direct the deletion of the extra bars and nodes on truss structures. Three examples demonstrate that the proposed method can yield the optimum structure form and the lightest weight of the given ground structure while satisfying dynamic response constraints. 展开更多
关键词 fundamental frequency dynamic response adaptive genetic algorithm topology optimization truss structure
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Conformal analysis of fundamental frequency of vibration of simple-supported elastic ellipse-plates with concentrated substance 被引量:2
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作者 齐红元 朱衡君 《Journal of Central South University》 SCIE EI CAS 2005年第S2期269-273,共5页
Aimed at calculating the fundamental frequency of vibration of special-shaped, simple-supported elastic plates, Conformal Mapping theory is applied, and the mathematical method of trigonometric interpolation with inte... Aimed at calculating the fundamental frequency of vibration of special-shaped, simple-supported elastic plates, Conformal Mapping theory is applied, and the mathematical method of trigonometric interpolation with interpolation points mutual iterative between odd and even sequences in boundary region is provided, as well as the conformal mapping function which can be described by real number region between complicated region and unit dish region is carried out. Furthermore, in the in-plane state of constant stress, vibrating function is completed by unit dish region method for simple-supported elastic plates with concentrated substance of complicated vibrating region, and the coefficient of fundamental frequency of the plate is analyzed. Meanwhile, taking simple-supported elastic ellipse-plates as an example, the effects on fundamental frequency caused by eccentric ratio, the coefficient of constant in-plane stress, as well as the concentrated substance mass and positions are analyzed respectively. 展开更多
关键词 vibration fundamental frequency mode conformal mapping method of trigonometric interpolation elastic simple-supported plates
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A simplified method for analyzing the fundamental frequency of monopile supported offshore wind turbine system design 被引量:2
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作者 Yang Chunbao Wang Rui Zhang Jianmin 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2018年第4期893-901,共9页
Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establish... Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand. 展开更多
关键词 offshore wind turbine system fundamental frequency analytical method rotational foundation flexibility
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Analytical Solutions to the Fundamental Frequency of Arbitrary Laminated Plates under Various Boundary Conditions 被引量:1
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作者 Yingqin Luo Ming Hong Yuan Liu 《Journal of Marine Science and Application》 CSCD 2015年第1期46-52,共7页
In recent years, as the composite laminated plates are widely used in engineering practice such as aerospace, marine and building engineering, the vibration problem of the composite laminated plates is becoming more a... In recent years, as the composite laminated plates are widely used in engineering practice such as aerospace, marine and building engineering, the vibration problem of the composite laminated plates is becoming more and more important. Frequency, especially the fundamental frequency, has been considered as an important factor in vibration problem. In this paper, a calculation method of the fundamental frequency of arbitrary laminated plates under various boundary conditions is proposed. The vibration differential equation of the laminated plates is established at the beginning of this paper and the frequency formulae of specialty orthotropic laminated plates under various boundary conditions and antisymmetric angle-ply laminated plates with simply-supported edges are investigated. They are proved to be correct. Simple algorithm of the fundamental frequency for multilayer antisymmetric and arbitrary laminated plates under various boundary conditions is studied by a series of typical examples. From the perspective of coupling, when the number of laminated plates layers N〉8-10, some coupling influence on the fundamental frequency can be neglected. It is reasonable to use specialty orthotropic laminated plates with the same thickness but less layers to calculate the corresponding fundamental frequency of laminated plates. Several examples are conducted to prove correctness of this conclusion. At the end of this paper, the influence of the selected number of layers of specialty orthotropic laminates on the fundamental frequency is investigated. The accuracy and complexity are determined by the number of layers. It is necessary to use proper number of layers of special orthotropic laminates with the same thickness to simulate the fundamental frequency in different boundary conditions. 展开更多
关键词 laminated plates arbitrary orientation analytical solutions fundamental frequency boundary conditions
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Mapping analysis of vibrating fundamental frequency for simple-supported elastic rectangle-plates with concentrated mass 被引量:1
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作者 齐红元 王爽心 朱衡君 《Journal of Central South University of Technology》 2007年第5期708-712,共5页
By conformal mapping theory, a trigonometric interpolation method between odd and even sequences in rectangle boundary region was provided, and the conformal mapping function of rectangle-plate with arc radius between... By conformal mapping theory, a trigonometric interpolation method between odd and even sequences in rectangle boundary region was provided, and the conformal mapping function of rectangle-plate with arc radius between complicated region and unite dish region was carried out. Aiming at calculating the vibrating fundamental frequency of special-shaped, elastic simple-supported rectangle-plates, in the in-plane state of constant stress, the vibration function of this complicated plate was depicted by unit dish region. The coefficient of ftmdamental frequency was calculated. Whilst, taking simple-supported elastic rectangle-plates with arc radius as an example, the effects on fundamental frequency caused by the concentrated mass and position, the ratio of the length to width of rectangle, as well as the coefficient of constant in-plane stress were analyzed respectively. 展开更多
关键词 conformal mapping elastic simple-supported plates vibration fundamental frequency mode method of trigonometric interpolation
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Dynamic quasi-continuum model for plate-type nano-materials and analysis of fundamental frequency
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作者 Chunxiao XIA Wenlong XU Guohua NIE 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第1期85-94,共10页
A dynamic quasi-continuum model is presented to analyze free vibration of plate-type cubic crystal nano-materials.According to the Hamilton principle,fundamental governing equations in terms of displacement components... A dynamic quasi-continuum model is presented to analyze free vibration of plate-type cubic crystal nano-materials.According to the Hamilton principle,fundamental governing equations in terms of displacement components and angles of rotations are given.As an application of the model,the cylindrical bending deformation of the structure fixed at two ends is analyzed,and a theoretical formula evaluating the fundamental frequency is obtained by using Galerkin's method.Meanwhile,the solution for the classical continuous plate model is also derived,and the size-dependent elastic modulus and Poisson's ratio are taken in computation.The frequencies corresponding to different atomic layers are numerically presented for the plate-type NaC l nano-materials.Furthermore,a molecular dynamics(MD)simulation is conducted with the code LAMMPS.The comparison shows that the present quasi-continuum model is valid,and it may be used as an alternative model,which reflects scale effects in analyzing dynamic behaviors of such plate-type nano-materials. 展开更多
关键词 plate-type nano-material quasi-continuum model SIZE-DEPENDENT fundamental frequency theoretical solution molecular dynamics(MD)simulation
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THE APPLICATION OF WEINSTEIN-CHIEN′S METHOD——THE UPPER AND LOWER LIMITS OF FUNDAMENTAL FREQUENCY OF RECTANGULAR PLATES WITH EDGES ARE THE MIXTURE OF SIMPLY SUPPORTED PORTIONS AND CLAMPED PORTIONS
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作者 陈政清 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 1984年第3期1399-1408,共10页
In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundam... In this paper, the method of relaxed boundary conditions is applied to rectangular plates with edges which are a sort of the mixture of simply supported portions and clamped portions, so that the lower limit of fundamental frequency of such plates is evaluated. A kind of polynomial satisfying the displacement boundary conditions is designed, os that it is enabled to evaluate the upper limit of fundamental frequency by Ritz' method. The practical calculation examples solved by these methods have given satisfactory results. At the end of this paper, it is pointed out that the socalled exact solution of such plates usually evaluated by the force superposition method is essentially a kind of lower limit of solution, if the truncated error of series which occurs in actual calculation is considered. 展开更多
关键词 THE UPPER AND LOWER LIMITS OF fundamental frequency OF RECTANGULAR PLATES WITH EDGES ARE THE MIXTURE OF SIMPLY SUPPORTED PORTIONS AND CLAMPED PORTIONS S METHOD THE APPLICATION OF WEINSTEIN-CHIEN
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Normalized estimation of fundamental frequency and measurement of harmonics/interharmonics
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作者 Zhaobi CHU Ming DING +1 位作者 Shaowu DU Xueping DONG 《控制理论与应用(英文版)》 EI CSCD 2013年第1期10-17,共8页
An adaptive notch filter is presented to estimate the fundamental frequency and measure both harmonics and interharmonics of an almost periodic signal with unknown time-variant fundamental frequency, which has the ro-... An adaptive notch filter is presented to estimate the fundamental frequency and measure both harmonics and interharmonics of an almost periodic signal with unknown time-variant fundamental frequency, which has the ro- bustness that the convergence speed is determined by neither amplitude nor frequency of fundamental component. The algorithm forms a one-dimensional slow adaptive integral manifold whose existence and stability are proved by averaging method and Lyapunov stability theorem. The local exponential stability and the ultimate boundedness of fundamental fre- quency estimation are proved. The local exponential stability makes sure that the fundamental frequency, the harmonic and interharmonic components can be all fast tracked. The principle for adjusting the parameters with their influences on tran- sient and steady-state performance is investigated and decreasing parameters can improve noise characteristic. The validity is verified by simulation results. 展开更多
关键词 Normalized fundamental frequency estimator Harmonic analysis Adaptive notch filter Stability analysis
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Estimating mean trabecular bone spacing based on the combination of Hilbert transform and fundamental frequency estimation
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作者 李颖 徐峰 +3 位作者 刘成成 许凯亮 他得安 王威琪 《Science Foundation in China》 CAS 2017年第3期57-71,共15页
Ultrasonic backscatter signals from cancellous bone are sensitive to the microstructure of trabecular bone,and thus enable the feasibility to extract microstructural information of trabecular bone.The mean trabecular ... Ultrasonic backscatter signals from cancellous bone are sensitive to the microstructure of trabecular bone,and thus enable the feasibility to extract microstructural information of trabecular bone.The mean trabecular bone spacing(MTBS)is an important parameter for characterizing bone microstructure.This paper proposes an MTBS estimation method based on the combination of Hilbert transform and fundamental frequency estimation(CHF). The CHF was verified with ultrasonic backscatter signals from simulations and in vitro measurements at a central frequency of 5MHz.The CHF method was compared with the simplified inverse filter tracking(SIFT)method,Simons' Quadratic Transformation(QT)method,Singular Spectrum Analysis(SSA)method,and Spectral Autocorrelation(SAC)method.Monte-Carlo simulations were performed by varying the MTBS,signal-to-noise ratio(SNR),standard deviation of regular spacing(SDRS),amplitude ratio of diffuse scattering to regular scattering(Ad)and frequency dependent attenuation(nBUA).The simulation results showed that the CHF method had a better performance in MTBS estimation under almost all the examination conditions except for SNR.The estimation percentage correct(EPC)was greater than 90% when the MTBS was in the range of 0.4to 1.4mm.In the in vitro measurements,the estimated EPC by the CHF method was91.25±7.81%(mean±standard deviation).A significant correlation was observed for the CHF-estimated MTBS and micro-computed tomography(μ-CT)-measured values(R^2=0.75,p<0.01).These results demonstrate that the CHF method is anti-interference for MTBS estimation and can be used to estimate trabecular bone spacing. 展开更多
关键词 Ultrasonic backscatter Mean trabecular bone spacing estimation Hilbert transform and fundamental frequency estimation Cancellous bone microstructure
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Fundamental Frequency Statistics for Young Male Speakers of Mandarin
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作者 Honglin Cao Yingjing Lei 《Journal of Forensic Science and Medicine》 2017年第4期217-222,共6页
In forensic speaker comparison(FSC),it is essential not only to evaluate the similarity between two(or more)samples,but also the typicality of the features in the relevant population.For the typicality,it is necessary... In forensic speaker comparison(FSC),it is essential not only to evaluate the similarity between two(or more)samples,but also the typicality of the features in the relevant population.For the typicality,it is necessary that the population statistics related to the phonetic parameters be available.This article presents the statistics for the fundamental frequency(F0)of 100 young Chinese male speakers producing both reading and spontaneous speech.Five descriptive statistics of long‑term F0,namely mean,median,mode,standard deviation(SD),and coefficient of variation(CV=SD/mean),are shown in histograms and scatter diagrams.Results show that the distributions of the five statistics are near normal.The findings are compared with the literature and discussed with respect to forensic phonetic implications.This article concludes that the results for the F0 statistics in the present study can be used in FSC casework as reference data on F0 for the young male Chinese population. 展开更多
关键词 Forensic speaker comparison fundamental frequency MANDARIN population statistics
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Reliability Based Optimization of Composite Laminates for Frequency Constraint 被引量:3
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作者 吴浩 燕瑛 刘玉佳 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2008年第4期320-327,共8页
The reliability based optimization (RBO) issue of composite laminates trader fundamental frequency constraint is studied. Considering the tmcertainties of material properties, the frequency constraint reliability of... The reliability based optimization (RBO) issue of composite laminates trader fundamental frequency constraint is studied. Considering the tmcertainties of material properties, the frequency constraint reliability of the structure is evaluated by the combination of response surface method (RSM) and finite element method. An optimization algorithm is developed based on the mechanism of laminate frequency characteristics, to optimize the laminate in terms of the ply amount and orientation angles. Numerical examples of composite laminates and cylindrical shell illustrate the advantages of the present optimization algorithm on the efficiency and applicability respects. The optimal solutions of RBO are obviously different from the deterministic optimization results, and the necessity of considering material property uncertainties in the composite structural frequency constraint optimization is revealed. 展开更多
关键词 fundamental frequency reliability based optimization (RBO) response surface method (RSM) basic random variable (BRV) failure probability deterministic optimization
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Microtremor-based analysis of the dynamic response characteristics of a site containing grouped earth fissures 被引量:1
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作者 Deng Yahong Xuan You +5 位作者 Mu Huandong Chang Jiang Cao Ge He Nainan Zhao Xunchang Sun Longfei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2023年第3期689-702,共14页
In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring poin... In this study,the Beibu earth fissure site in the northeastern part of Weihe Basin,which contains four nearly parallel earth fissures,was studied.A long straight microtremor measuring line,containing 49 measuring points across four earth fissures,was established to investigate the dynamic response of this site using Fourier spectrum,response acceleration spectrum,Arias intensity,and HVSR analyses.The main results are as follows:(1)The fundamental frequencies of 44 measuring points obtained from HVSR analysis are concentrated within 1.67 Hz-2.25 Hz,and the existence of the earth fissures has little effect on the fundamental frequency changes.(2)There is an amplification effect near a single earth fissure.The dynamic responses are large at the measuring points near the earth fissure,and the values decrease with increasing distance from the earth fissure.In areas between two adjacent earth fissures,these values decrease and are even lower than those in sites without amplification effects.(3)In this earth fissure site,the general area(or less affected area)and affected areas were delineated based on the amplification effect.In engineering applications,construction design should avoid these affected areas and existing structures should be reinforced to satisfy the seismic fortification requirements. 展开更多
关键词 earth fissure sites MICROTREMORS Fourier amplitude spectrum response spectrum arias intensity H/V spectral ratio fundamental frequency amplification effect
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The Efficacy of Deep Learning-Based Mixed Model for Speech Emotion Recognition 被引量:1
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作者 Mohammad Amaz Uddin Mohammad Salah Uddin Chowdury +2 位作者 Mayeen Uddin Khandaker Nissren Tamam Abdelmoneim Sulieman 《Computers, Materials & Continua》 SCIE EI 2023年第1期1709-1722,共14页
Human speech indirectly represents the mental state or emotion of others.The use of Artificial Intelligence(AI)-based techniques may bring revolution in this modern era by recognizing emotion from speech.In this study... Human speech indirectly represents the mental state or emotion of others.The use of Artificial Intelligence(AI)-based techniques may bring revolution in this modern era by recognizing emotion from speech.In this study,we introduced a robust method for emotion recognition from human speech using a well-performed preprocessing technique together with the deep learning-based mixed model consisting of Long Short-Term Memory(LSTM)and Convolutional Neural Network(CNN).About 2800 audio files were extracted from the Toronto emotional speech set(TESS)database for this study.A high pass and Savitzky Golay Filter have been used to obtain noise-free as well as smooth audio data.A total of seven types of emotions;Angry,Disgust,Fear,Happy,Neutral,Pleasant-surprise,and Sad were used in this study.Energy,Fundamental frequency,and Mel Frequency Cepstral Coefficient(MFCC)have been used to extract the emotion features,and these features resulted in 97.5%accuracy in the mixed LSTM+CNN model.This mixed model is found to be performed better than the usual state-of-the-art models in emotion recognition from speech.It also indicates that this mixed model could be effectively utilized in advanced research dealing with sound processing. 展开更多
关键词 Emotion recognition Savitzky Golay fundamental frequency MFCC neural networks
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Geometrical Dimensional Effect on Natural Frequency of Single Layer Graphene in Armchair Configuration
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作者 Harshad Patel 《Journal of Mechanical Engineering Research》 2021年第2期45-51,共7页
Graphene has remarkable strength,such as yield strength and elastic constant.The dynamic behaviour of graphene sheet is affected by geometrical variation in atomic arrangement.This paper introduced graphene with armch... Graphene has remarkable strength,such as yield strength and elastic constant.The dynamic behaviour of graphene sheet is affected by geometrical variation in atomic arrangement.This paper introduced graphene with armchair atomic structure for estimating fundamental natural frequencies.The presented analysis can be useful for the possible high frequency nanomechanical resonator systems.The analytical formulation,based on classical plate theory and continuum solid modelling based finite element method have been performed for estimation of fundamental natural frequencies of single layer graphene sheet(SGLS)with different boundary conditions.The free edge and clamped edge boundary conditions have been considered.For simplifying analytical formulations,Blevins approach for dynamic solution has been adopted and for validating analytical results.The finite element analysis of SLGS has been performed using ANSYS software.The effect of variation in geometrical parameters in terms of width and length of SLGS has been analysed for realization of ultra-high frequency based nanomechanical resonator systems. 展开更多
关键词 Single layer graphene sheet(SLGS) Size variation fundamental natural frequency Finite element analysis
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Experimental Mode and Vibration Comfort Analysis of High-Rise Glulam Building Floor Structure
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作者 Yuhang He Rongzhuo Zhang +1 位作者 Yifan Zhang Zheng Wang 《Journal of Renewable Materials》 SCIE EI 2023年第6期2729-2743,共15页
In order to better meet the objective requirements of the use safety of the high-rise glulam building floor structure and the living comfort of the residents,the transient excitation,environmental excitation and frequ... In order to better meet the objective requirements of the use safety of the high-rise glulam building floor structure and the living comfort of the residents,the transient excitation,environmental excitation and frequency spectrum identification methods were used to carry out experimental modal test in-site on the three rooms numbered A,B and C of the same glulam structural building.The three rooms have different functions,different floor sizes and different floor supporting structures.The research results have shown that the first-order bending frequency of the floor structure of Room A is 27.50 Hz,the transverse second-order bending frequency is 34.75 Hz,the longitudinal second-order bending frequency is 53.25 Hz,and the first-order torsional frequency is 56.25 Hz.The reinforced wooden beam at the bottom of the floor of Room A increases the transverse stiffness of the floor structure,but does not offset the anisotropy caused by the longitudinally installed glulam floors.The fundamental frequency values of the floor structures of the three rooms numbered A,B,and C are 27.5,13 and 18 Hz,respectively.This has a relatively high innovation and reference significance for integrating the theory of structural dynamic characteristics with the dynamic testing technology,improving the design level of high-rise glulam structure buildings,and improving the living comfort of residents. 展开更多
关键词 Glulam building wooden floor experimental mode vibration comfort fundamental frequency
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Emotion Recognition with Capsule Neural Network 被引量:1
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作者 Loan Trinh Van Quang H.Nguyen Thuy Dao Thi Le 《Computer Systems Science & Engineering》 SCIE EI 2022年第6期1083-1098,共16页
For human-machine communication to be as effective as human-tohuman communication, research on speech emotion recognition is essential.Among the models and the classifiers used to recognize emotions, neural networks... For human-machine communication to be as effective as human-tohuman communication, research on speech emotion recognition is essential.Among the models and the classifiers used to recognize emotions, neural networks appear to be promising due to the network’s ability to learn and the diversity in configuration. Following the convolutional neural network, a capsuleneural network (CapsNet) with inputs and outputs that are not scalar quantitiesbut vectors allows the network to determine the part-whole relationships thatare specific 6 for an object. This paper performs speech emotion recognition basedon CapsNet. The corpora for speech emotion recognition have been augmented byadding white noise and changing voices. The feature parameters of the recognition system input are mel spectrum images along with the characteristics of thesound source, vocal tract and prosody. For the German emotional corpus EMODB, the average accuracy score for 4 emotions, neutral, boredom, anger and happiness, is 99.69%. For Vietnamese emotional corpus BKEmo, this score is94.23% for 4 emotions, neutral, sadness, anger and happiness. The accuracy scoreis highest when combining all the above feature parameters, and this scoreincreases significantly when combining mel spectrum images with the featuresdirectly related to the fundamental frequency. 展开更多
关键词 Emotion recognition CapsNet data augmentation mel spectrum image fundamental frequency
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Multi-objective optimization of frequency and damping of vertical stabilizer skin structure placed with variable-angle tows 被引量:3
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作者 Lei ZU Xianzhao XIA +7 位作者 Qian ZHANG Guiming ZHANG Shijun CHEN Jianhui FU Lichuan ZHOU Huabi WANG Debao LI Liqing ZOU 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2023年第1期444-455,共12页
The vibration characteristics of composite vertical stabilizer skin structures play a critical role in damping effects designed for overcoming the air disturbances experienced by aircraft structural components during ... The vibration characteristics of composite vertical stabilizer skin structures play a critical role in damping effects designed for overcoming the air disturbances experienced by aircraft structural components during flight.The first-order fundamental frequencies and their corresponding damping characteristics of the vertical stabilizer skin structure tow-steered by automatic fiber placement technique were optimized with the parameterized trajectories and plies as design variables.Firstly,the vibration and damping numerical models were derived based on Kirchhoff laminate theory,the Rayleigh-Ritz method,and the Strain Energy Method.Then the optimization model was developed by adopting the self-adaptive Differential Evolution Multi-objective optimization algorithm and incorporating the solution method of Pareto Front.The constraints of this optimization model considered the experimentally obtained minimum turning radius of prepregs tow-steered in automatic fiber placement process obtained from experimental tests.Finally,the comparison of numerical simulation results was conducted for the optimized trajectories and the conventional straight trajectories under various boundary conditions,and the numerical results were partially validated through damping and frequency tests.The results indicate the vibration characteristics of the composite vertical stabilizer skin structure can be enhanced to a large extent by optimizing fiber trajectories,and the enhancement percentage is affected by the boundary conditions of the actual structure. 展开更多
关键词 DAMPING fundamental frequency Multi-objective optimiza-tion Variable-angle tow Vertical stabilizer skin Vibration properties
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Morphological Correlates of the Phonatory Organ in an Ultrasonically Phonating Frog
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作者 Rongchuan XIONG Bin WANG +1 位作者 Yuhan WU Jianping JIANG 《Asian Herpetological Research》 SCIE 2012年第3期240-251,共12页
The concave-eared torrent frog(Odorrana tormota) is the first species of tailless amphibian that was evidenced to phonate and detect ultrasounds. We employed anatomic and histological methods to examine the phonatory ... The concave-eared torrent frog(Odorrana tormota) is the first species of tailless amphibian that was evidenced to phonate and detect ultrasounds. We employed anatomic and histological methods to examine the phonatory organs, including the floor of the buccal cavity, vocal cords and glottis, of O. tormota and its sympatric species including O. graminea, O. schmackeri, and Amolops wuyiensis with different fundamental frequencies, and Pelophylax nigromaculatus as a control. Our results reveal that O. tormota possesses specialized phonatory organ structures, with thinner vocal cords modulated by a moderately stronger muscular mastoideus between the medial vocal cords and the lateral cricoid cartilages, and more elastic mouth floor to likely supply faster air stream which could make the vocal cords vibrate at higher frequencies, larger relative distance between the two muscles m. intermandibulares(RDMI), and higher nucleus density of m. intermandibularis(NDMI) and m. geniohyoideus(NDMG). The results of Pearson’s correlation tests between the mean values of the above measurements and the fundamental frequencies from the five species imply that all the specialized phonatory organ structures mentioned above might be favored by higher frequency of phonation of O. tormota. 展开更多
关键词 concave-eared torrent frog comparative anatomy ultrasonic phonation fundamental frequency
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Free Vibration Analysis of RC Box-Girder Bridges Using FEM
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作者 Preeti Agarwal Priyaranjan Pal Pradeep Kumar Mehta 《Sound & Vibration》 EI 2022年第2期105-125,共21页
The free vibration analysis of simply supported box-girder bridges is carried out using the finite element method.The fundamental frequency is determined in straight,skew,curved and skew-curved box-girder bridges.It i... The free vibration analysis of simply supported box-girder bridges is carried out using the finite element method.The fundamental frequency is determined in straight,skew,curved and skew-curved box-girder bridges.It is important to analyse the combined effect of skewness and curvature because skew-curved box-girder bridge behaviour cannot be predicted by simply adding the individual effects of skewness and curvature.At first,an existing model is considered to validate the present approach.A convergence study is carried out to decide the mesh size in the finite element method.An exhaustive parametric study is conducted to determine the fundamental frequency of box-girder bridges with varying skew angle,curve angle,span,span-depth ratio and cell number.The skew angle is varied from 0°to 60°,curve angle is varied from 0°to 60°,span is changed from 25 to 50 m,span-depth ratio is varied from 10 to 16,and single cell&double cell are used in the present study.A total of 420 bridge models are used for parametric study in the investigation.Mode shapes of the skew-curved bridge are also presented.The fundamental frequency of the skew-curved box-girder bridge is found to be more than the straight bridge,so,the skew-curved box-girder bridge is preferable.The present study may be useful in the design of box-girder bridges. 展开更多
关键词 fundamental frequency skew-curved box-girder bridge SINGLE-CELL double-cell curve angle skew angle FEM
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