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Power Flow Response Based Dynamic Topology Optimization of Bi-material Plate Structures 被引量:3
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作者 XUE Xiaoguang LI Guoxi +1 位作者 XIONG Yeping GONG Jingzhong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第3期620-628,共9页
Work on dynamic topology optimization of engineering structures for vibration suppression has mainly addressed the maximization of eigenfrequencies and gaps between consecutive eigenfrequencies of free vibration, mini... Work on dynamic topology optimization of engineering structures for vibration suppression has mainly addressed the maximization of eigenfrequencies and gaps between consecutive eigenfrequencies of free vibration, minimization of the dynamic compliance subject to forced vibration, and minimization of the structural frequency response. A dynamic topology optimization method of bi-material plate structures is presented based on power flow analysis. Topology optimization problems formulated directly with the design objective of minimizing the power flow response are dealt with. In comparison to the displacement or velocity response, the power flow response takes not only the amplitude of force and velocity into account, but also the phase relationship of the two vector quantities. The complex expression of power flow response is derived based on time-harmonic external mechanical loading and Rayleigh damping. The mathematical formulation of topology optimization is established based on power flow response and bi-material solid isotropic material with penalization(SIMP) model. Computational optimization procedure is developed by using adjoint design sensitivity analysis and the method of moving asymptotes(MMA). Several numerical examples are presented for bi-material plate structures with different loading frequencies, which verify the feasibility and effectiveness of this method. Additionally, optimum results between topological design of minimum power flow response and minimum dynamic compliance are compared, showing that the present method has strong adaptability for structural dynamic topology optimization problems. The proposed research provides a more accurate and effective approach for dynamic topology optimization of vibrating structures. 展开更多
关键词 dynamic topology optimization power flow response BI-MATERIAL plate structures
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A FAST SEARCH METHOD OF STEERED RESPONSE POWER WITH SMALL-APERTURE MICROPHONE ARRAY FOR SOUND SOURCE LOCALIZATION 被引量:1
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作者 Zhao Xiaoyan Tang Jie +1 位作者 Zhou Lin Wu Zhenyang 《Journal of Electronics(China)》 2013年第5期483-490,共8页
The Steered Response Power(SRP)method works well for sound source localization in noisy and reverberant environment.However,the large computation complexity limits its practical application.In this paper,a fast SRP se... The Steered Response Power(SRP)method works well for sound source localization in noisy and reverberant environment.However,the large computation complexity limits its practical application.In this paper,a fast SRP search method is proposed to reduce the computational complexity using small-aperture microphone array.The proposed method inspired by the SRP spatial spectrum includes two steps:first,the proposed method estimates the azimuth of the sound source roughly and determines whether the sound source is in far field or near field;then,different fine searching operations are performed according to the sound source being in far field or near field.Experiments both in simulation environments and real environments have been performed to compare the localization accuracy and computation complexity of the proposed method with those of the conventional SRP-PHAT algorithm.The results show that,the proposed method has a comparative accuracy with the conventional SRP algorithm,and achieves a reduction of 93.62%in computation complexity compared to the conventional SRP algorithm. 展开更多
关键词 Sound source localization Steered response power(SRP) Three-line method Smallaperture microphone array
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Parametric characteristic of the random vibration response of nonlinear systems 被引量:2
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作者 Xing-Jian Dong Zhi-Ke Peng +2 位作者 Wen-Ming Zhang Guang Meng Fu-Lei Chu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2013年第2期267-283,共17页
Volterra series is a powerful mathematical tool for nonlinear system analysis,and there is a wide range of nonlinear engineering systems and structures that can be represented by a Volterra series model.In the present... Volterra series is a powerful mathematical tool for nonlinear system analysis,and there is a wide range of nonlinear engineering systems and structures that can be represented by a Volterra series model.In the present study,the random vibration of nonlinear systems is investigated using Volterra series.Analytical expressions were derived for the calculation of the output power spectral density(PSD) and input-output cross-PSD for nonlinear systems subjected to Gaussian excitation.Based on these expressions,it was revealed that both the output PSD and the input-output crossPSD can be expressed as polynomial functions of the nonlinear characteristic parameters or the input intensity.Numerical studies were carried out to verify the theoretical analysis result and to demonstrate the effectiveness of the derived relationship.The results reached in this study are of significance to the analysis and design of the nonlinear engineering systems and structures which can be represented by a Volterra series model. 展开更多
关键词 Volterra series·Nonlinear system·Random vibration·power spectrum density·Generalized frequency response functions
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Research on a simulated 60 kW PEMFC cogeneration system for domestic application 被引量:3
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作者 张颖颖 余晴春 +1 位作者 曹广益 朱新坚 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第3期450-457,共8页
The electrical and thermal performances of a simulated 60 kW Proton Exchange Membrane Fuel Cell (PEMFC) cogeneration system are first analyzed and then strategies to make the system operation stable and efficient are ... The electrical and thermal performances of a simulated 60 kW Proton Exchange Membrane Fuel Cell (PEMFC) cogeneration system are first analyzed and then strategies to make the system operation stable and efficient are developed. The system configuration is described first, and then the power response and coordination strategy are presented on the basis of the electricity model. Two different thermal models are used to estimate the thermal performance of this cogeneration system, and heat management is discussed. Based on these system designs, the 60 kW PEMFC cogeneration system is analyzed in detail. The analysis results will be useful for further study and development of the system. 展开更多
关键词 Proton Exchange Membrane Fuel Cell (PEMFC) COGENERATION Coordination strategy power response Heat management
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Accelerated steered response power method for sound source localization via clustering search 被引量:5
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作者 ZHAO XiaoYan TANG Jie +1 位作者 ZHOU Lin WU ZhenYang 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2013年第7期1329-1338,共10页
The steered response power-phase transform (SRP-PHAT) sound source localization algorithm is robust in a real environment. However, the large computation complexity limits the practical application of SRP-PHAT. For a ... The steered response power-phase transform (SRP-PHAT) sound source localization algorithm is robust in a real environment. However, the large computation complexity limits the practical application of SRP-PHAT. For a microphone array, each location corresponds to a set of time differences of arrival (TDOAs), and this paper collects them into a TDOA vector. Since the TDOA vectors in the adjacent regions are similar, we present a fast algorithm based on clustering search to reduce the computation complexity of SRP-PHAT. In the training stage, the K-means or Iterative Self-Organizing Data Analysis Technique (ISODATA) clustering algorithm is used to find the centroid in each cluster with similar TDOA vectors. In the procedure of sound localization, the optimal cluster is found by comparing the steered response powers (SRPs) of all centroids. The SRPs of all candidate locations in the optimal cluster are compared to localize the sound source. Experiments both in simulation environments and real environments have been performed to compare the localization accuracy and computational load of the proposed method with those of the conventional SRP-PHAT algorithm. The results show that the proposed method is able to reduce the computational load drastically and maintains almost the same localization accuracy and robustness as those of the conventional SRP-PHAT algorithm. The difference in localization performance brought by different clustering algorithms used in the training stage is trivial. 展开更多
关键词 sound source localization microphone array steered response power clustering search
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Feed-Forward Active Noise Control System Using Microphone Array 被引量:4
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作者 Yang Li Lichuan Liu Sen M.Kuo 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2018年第5期946-952,共7页
Feedforward active noise control(ANC)system are widely used to reduce the wide-band noise in different application.In feedforward ANC systems,when the noise source is unknown,the misplacement of the reference micropho... Feedforward active noise control(ANC)system are widely used to reduce the wide-band noise in different application.In feedforward ANC systems,when the noise source is unknown,the misplacement of the reference microphone may violate the causality constraint.We present a performance analysis of the feedforward ANC system under a noncausal condition.The ANC system performance degrades when the degree of noncausality increases.This research applies the microphone array technique to feedforward ANC systems to solve the unknown noise source problem.The generalized cross-correlation(GCC)and steering response power(SRP)methods based on microphone array are used to estimate the noise source location.Then,the ANC system selects the proper reference microphone for a noise control algorithm.The simulation and experiment results show that the SRP method can estimate the noise source direction with 84%accuracy.The proposed microphone array integrated ANC system can dramatically improve the system performance. 展开更多
关键词 Active noise control CAUSALITY direction estimation generalized cross-correlation(GCC) microphone-array noise pollution noise source steering response power(SRP)
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Physics Insight of the Inertia of Power Systems and Methods to Provide Inertial Response 被引量:1
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作者 Yongzhang Huang Yuxuan Wang +2 位作者 Chenyang Li Haisen Zhao Qianyu Wu 《CSEE Journal of Power and Energy Systems》 SCIE EI CSCD 2022年第2期559-568,共10页
The growth of renewable energy reduces the moment of inertia for the synchronous AC grid,so the authors put forward two basic questions:1)What is the physics insight that a synchronous AC grid needs for mechanical ine... The growth of renewable energy reduces the moment of inertia for the synchronous AC grid,so the authors put forward two basic questions:1)What is the physics insight that a synchronous AC grid needs for mechanical inertia?2)How to provide inertial response for the power grid dominated with renewable energy?Based on Einstein’s special relativity and the Lorentz transformation,these papers illustrates that the nature of the inertia of the AC grid comes from the relativity of the electromagnetic field and motion,and from the strong coupling between them.According to their nature,the inertial response of the synchronous generator is self-proven.By contrast,the converter for the grid-connection of renewable energies used various algorithms in order to provide virtual inertia.But because algorithms do not rebuild the coupling between electromagnetic fields and motion,it is doubtful whether they can provide inertia and inertial responses.Therefore,the authors propose that there is a need to build extra electromagnetic fields and motion coupling for grids with high penetration rates of renewable energy.Therefore,a new grid-connection technology via Motor-Generator Pair(MGP)is discussed.The electromagnetic-motion coupling of the MGP is analyzed,and the results of simulation and experimental studies are also reported. 展开更多
关键词 Electromagnetic-motion coupling inertia response of power systems Lorentz transformation motorgenerator pair(MGP) power systems with high proportion of renewable energy
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Analysis on Pseudo Excitation of Random Vibration for Structure of Time Flight Counter 被引量:1
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作者 WU Qiong LI Dapeng 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第2期325-330,共6页
Traditional computing method is inefficient for getting key dynamical parameters of complicated structure.Pseudo Excitation Method(PEM)is an effective method for calculation of random vibration.Due to complicated an... Traditional computing method is inefficient for getting key dynamical parameters of complicated structure.Pseudo Excitation Method(PEM)is an effective method for calculation of random vibration.Due to complicated and coupling random vibration in rocket or shuttle launching,the new staging white noise mathematical model is deduced according to the practical launch environment.This deduced model is applied for PEM to calculate the specific structure of Time of Flight Counter(ToFC).The responses of power spectral density and the relevant dynamic characteristic parameters of ToFC are obtained in terms of the flight acceptance test level.Considering stiffness of fixture structure,the random vibration experiments are conducted in three directions to compare with the revised PEM.The experimental results show the structure can bear the random vibration caused by launch without any damage and key dynamical parameters of ToFC are obtained.The revised PEM is similar with random vibration experiment in dynamical parameters and responses are proved by comparative results.The maximum error is within 9%.The reasons of errors are analyzed to improve reliability of calculation.This research provides an effective method for solutions of computing dynamical characteristic parameters of complicated structure in the process of rocket or shuttle launching. 展开更多
关键词 pseudo excitation method power spectral density random processes dynamic response vibration
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Performance enhancement of CMOS terahertz detector by drain current
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作者 张行行 纪小丽 +3 位作者 廖轶明 彭静宇 朱晨昕 闫锋 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第9期491-495,共5页
In this paper, we study the effect of the drain current on terahertz detection for Si metal-oxide semiconductor fieldeffect transistors(MOSFETs) both theoretically and experimentally. The analytical model, which is ... In this paper, we study the effect of the drain current on terahertz detection for Si metal-oxide semiconductor fieldeffect transistors(MOSFETs) both theoretically and experimentally. The analytical model, which is based on the smallsignal equivalent circuit of MOSFETs, predicts the significant improvement of the voltage responsivity Rv with the bias current. The experiment on antennas integrated with MOSFETs agrees with the analytical model, but the Rv improvement is accompanied first by a decrease, then an increase of the low-noise equivalent power(NEP) with the applied current. We determine the tradeoff between the low-NEP and high-Rv for the current-biased detectors. As the best-case scenario, we obtained an improvement of about six times in Rv without the cost of a higher NEP. We conclude that the current supply scheme can provide high-quality signal amplification in practical CMOS terahertz detection. 展开更多
关键词 drain current CMOS terahertz detectors voltage responsivity noise equivalent power
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Application of piezoelectric transient response in transducer acoustic power measurement
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作者 ZENG Miao SHEN Yong +2 位作者 LI Fu YANG Zengtao WANG Hua 《Chinese Journal of Acoustics》 CSCD 2017年第1期18-28,共11页
To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectr... To explore a more convenient method for measuring the focused ultrasound power, a piezoelectric ceramic plate was used to receive ultrasonic signal directly. Due to an acoustic force acts on the surface of piezoelectric ceramic plate, the piezoelectric response was obtained by means of electromechanical analogy, which was composed of voltage response caused by forced vibration and high frequency attenuation response caused by natural vibration. The conversion relationship between output signal of piezoelectric ceramic plate and acoustic power of transducer was analyzed. The envelope of output piezoelectric signal was extracted in twice, and a voltage amplitude curve with sinusoidal distribution that could describe the changes of acoustic power was obtained. Under different drive voltage of transducer, the maximum peak voltage of envelope curve was found respectively. Their squared values were made a linear fitting with acoustic power measured by acoustic power meter, and then the proportional coefficient of theoretical relational expression was calibrated. The experimental results are in good agreement with the theory. The relative error between calibrated theoretical acoustic power and that measured by acoustic power meter was less than 8.7%. The paper can provide a guideline for measuring acoustic power of transducer by using piezoelectric signal. 展开更多
关键词 Application of piezoelectric transient response in transducer acoustic power measurement
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Narrowband PLC Channel Workbench to Emulate Transmission in Smart Grid
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作者 Ismail Aouichak Anouar Achouri +1 位作者 Jean-Charles Le Bunetel Yves Raingeaud 《Journal of Control Science and Engineering》 2016年第2期51-60,共10页
A real-time workbench able to reproduce the same behavior as an indoor network is in order. Such a tool will help researchers and industrials extend the smart grid technology indoors and have a better acknowledgment o... A real-time workbench able to reproduce the same behavior as an indoor network is in order. Such a tool will help researchers and industrials extend the smart grid technology indoors and have a better acknowledgment of Smart Grid systems interoperability. In order to develop such a tool many approaches should be studied to choose the most suitable one by comparing the models and the technologies. The considered hardware are the embedded systems and the selected approach is the statistical one. It appears that the FlR filter is the most pertinent approach. 展开更多
关键词 Embedded systems emulator power line transfer function modeling FIR (finite impulse response filters narrowbandPLC power line communication).
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China as a Responsible Power Amid the COVID-19 Crisis:Perceptions of Partners and Adversaries on Twitter
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作者 Maria Papageorgiou Daniella da Silva Nogueira de Melo 《Fudan Journal of the Humanities and Social Sciences》 2022年第2期159-188,共30页
The challenging COVID-19 context has questioned China’s role as a responsible power but also tested its relationship with other states.This study seeks to investigate‘How other actors have perceived China’s role as... The challenging COVID-19 context has questioned China’s role as a responsible power but also tested its relationship with other states.This study seeks to investigate‘How other actors have perceived China’s role as a responsible power amid the COVID-19 crisis’.To do so,we opt for a qualitative approach examining the official Twitter accounts of seven actors that hold different types of relationships with China,namely Brazil,EU,Japan,Iran,Pakistan,Russia,and the USA.We aim to identify the perceptions of these actors towards China as unfolding from January to June 2020,emphasising the empirical applicability of Twitter’s discourse.By adopting the concept of responsible power approached from a Role Theory perspective,this paper contributes to a more nuanced understanding of interstate relations and role perceptions.Our findings indicate that there have been variations in the responses and perceptions other states have expressed towards China while its framing as a responsible power differs significantly during the crisis and its landmark events. 展开更多
关键词 China COVID-19 TWITTER Role theory Responsible power
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Responsibilities of a Big Power
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《Beijing Review》 2007年第44期37-37,共1页
To present itself to the international community as a responsible country will help China’s peaceful development and promote the construction of a harmonious world.However,overly high expectations and excessive respo... To present itself to the international community as a responsible country will help China’s peaceful development and promote the construction of a harmonious world.However,overly high expectations and excessive responsibilities will undoubtedly add risks to China’s development efforts. Jiang Yong,Director of Economic Security Research Center of China Institutes of Contemporary International Relations,expounds on this issue in an article in Outlook Weekly. 展开更多
关键词 Responsibilities of a Big power
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