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A novel small perturbation analytical model to investigate temperature control characteristics of spacecraft thermal systems in frequency domain 认领 引用
1
作者 Yuehang SUN Yunze LI +3 位作者 Yupeng ZHOU Ran WEI Hao DANG Xin ZHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2026年第2期100-114,共15页
This paper introduces a small perturbation frequency domain thermal analysis model based on the nonlinear dynamics model.The model can be applied to study the high-precision temperature control of thermal systems unde... This paper introduces a small perturbation frequency domain thermal analysis model based on the nonlinear dynamics model.The model can be applied to study the high-precision temperature control of thermal systems under low-frequency complex perturbations.The frequency domain characteristics of the space gravitational wave detection satellite are analyzed,and a multi-channel perturbation structure is established.The effects of three kinds of heat flow perturbations,including external heat flow,power generation power,and waste heat of electronic equipment,on the temperature through five transfer paths are investigated.It has been discovered that the waste heat from electronic equipment inside the satellite has the most noticeable effect on the temperature power spectral density of temperature-sensitive optical loads,serving as the primary factor influencing thermal stability.For complex noise signals,the small perturbation analysis method can decompose the different frequency components or ranges,reducing the problem to linearized analysis and simplifying complex calculations.The results indicate that the temperature power spectral density decreases as signal frequency increases,with low-frequency signals exerting a greater influence on temperature stability.The small perturbation analysis method is a novel and effective method for temperature control of space thermal systems,with high accuracy and stability. 展开更多
关键词 Frequency domain analysis Gravitational prospecting Perturbation techniques Power spectral density Temperature control
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Error Analysis in Frequency Domain for Linear Multipass Algorithms 认领 引用
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作者 费景高 《Journal of Systems Engineering and Electronics》 EI 2001年第4期77-84,共8页
Error analysis methods in frequency domain are developed in this paper for determining the characteristic root and transfer function errors when the linear multipass algorithms are used to solve linear differential eq... Error analysis methods in frequency domain are developed in this paper for determining the characteristic root and transfer function errors when the linear multipass algorithms are used to solve linear differential equations. The relation between the local truncation error in time domain and the error in frequency domain is established, which is the basis for developing the error estimation methods. The error estimation methods for the digital simulation model constructed by using the Runge-Kutta algorithms and the linear multistep predictor-corrector algorithms are also given. 展开更多
关键词 Algorithms Computer simulation Differential equations Error analysis Frequency domain analysis Runge Kutta methods
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Frequency domain based super-resolution method for mixed-resolution multi-view images 认领 引用
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作者 Zhizhong Fu Yawei Li +2 位作者 Yuan Li Lan Ding Keyu Long 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2016年第6期1303-1314,共12页
Super-resolution (SR) techniques, which are based on single or multi-frame low-resolution (LR) images, have been extensively investigated in the last two decades. Mixed-resolution multiview video format plays an impor... Super-resolution (SR) techniques, which are based on single or multi-frame low-resolution (LR) images, have been extensively investigated in the last two decades. Mixed-resolution multiview video format plays an important role in three-dimensional television (3DTV) coding scheme. Previous work considers multiview or multi-camera images and videos at the same resolution, which performs well under the planar model without or with little projection error among the videos captured by different cameras. In recent years, several researchers have discussed the SR problem in mixed-resolution multi-view video format, where the superresolved image is created using the up-sampled version of the LR image and the high frequency components extracted from the warped image in the adjacent high-resolution (HR) views. Unfortunately, the output HR images suffer from artifacts caused by depth error. To obtain the detailed texture and edge information from the HR image as much as possible, while preserving the structure of the LR image, a novel SR reconstruction algorithm is proposed. The algorithm is composed of three components: the structure term, the detail information term, and the regularization term. The first term preserves the structure similarity of the LR image; the second term extracts detailed information from the adjacent HR image; and the last term ensures the uniqueness of the solution. Experimental results show the effectiveness and robustness of the proposed algorithm, which achieves high performance both subjectively and objectively. © 2016 Beijing Institute of Aerospace Information. 展开更多
关键词 Cameras Edge detection Frequency domain analysis Image reconstruction Optical resolving power
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Parameter identification algorithm for fault location using one terminal data based on frequency domain 认领 引用
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作者 康小宁 索南加乐 《Journal of Pharmaceutical Analysis》 CAS 2007年第1期18-23,共6页
This paper presents a novel algorithm of fault location for transmission line.Solving the network spectrum equations for different frequencies the fault can be located accurately by this algorithm with one terminal da... This paper presents a novel algorithm of fault location for transmission line.Solving the network spectrum equations for different frequencies the fault can be located accurately by this algorithm with one terminal data of voltage and current,and the identified parameters,such as fault distance, fault resistance,and opposite terminal system resistance and inductance.The algorithm eliminates the influence of the opposite system impedance on the fault location accuracy,which causes the main error in traditional fault location methods using one terminal data.A method of calculating spectrum from sampled data is also proposed.EMTP simulations show the validity and higher accuracy of the fault location algorithm compared to the existing ones based on one terminal data. 展开更多
关键词 fault location parameter identification frequency domain analysis
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A Priority-aware Frequency Domain Polling MAC Protocol for OFDMA-based Networks in Cyber-physical Systems 认领 引用 被引量：1
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作者 Meng Zheng Junru Lin +1 位作者 Wei Liang Haibin Yu 《IEEE/CAA Journal of Automatica Sinica》 EI 2015年第4期412-421,共10页
Wireless networking in cyber-physical systems (CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and relia... Wireless networking in cyber-physical systems (CPSs) is characteristically different from traditional wireless systems due to the harsh radio frequency environment and applications that impose high real-time and reliability constraints. One of the fundamental considerations for enabling CPS networks is the medium access control protocol. To this end, this paper proposes a novel priority-aware frequency domain polling medium access control (MAC) protocol, which takes advantage of an orthogonal frequency-division multiple access (OFDMA) physical layer to achieve instantaneous priority-aware polling. Based on the polling result, the proposed work then optimizes the resource allocation of the OFDMA network to further improve the data reliability. Due to the non-polynomial-complete nature of the OFDMA resource allocation, we propose two heuristic rules, based on which an efficient solution algorithm to the OFDMA resource allocation problem is designed. Simulation results show that the reliability performance of CPS networks is significantly improved because of this work. © 2014 Chinese Association of Automation. 展开更多
关键词 Access control Embedded systems Frequency domain analysis Medium access control Network layers Orthogonal frequency division multiplexing Polynomials Real time systems Reliability Resource allocation Wireless networks
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A review on DFACS(II):Modeling and analysis of disturbances and noises 认领 引用 被引量：4
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作者 Chenglei YUE Bohan JIAO +12 位作者 Zhaohui DANG Xiaokui YUE Yonghe ZHANG Yuanqing XIA Li DUAN Qinglei HU Qifan LIU Pengcheng WANG Ming GUO Zhansheng DUAN Bing CUI Chu ZHANG Xiaodong SHAO 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2024年第5期120-147,共28页
This paper presents Part II of a review on DFACS,which specifically focuses on the modeling and analysis of disturbances and noises in DFACSs.In Part I,the system composition and dynamics model of the DFACS were prese... This paper presents Part II of a review on DFACS,which specifically focuses on the modeling and analysis of disturbances and noises in DFACSs.In Part I,the system composition and dynamics model of the DFACS were presented.In this paper,we discuss the effects of disturbance forces and noises on the system,and summarize various analysis and modeling methods for these interferences,including the integral method,frequency domain analysis method,and magnitude evaluation method.By analyzing the impact of disturbances and noises on the system,the paper also summarizes the system’s performance under slight interferences.Additionally,we highlight current research difficulties in the field of DFACS noise analysis.Overall,this paper provides valuable insights into the modeling and analysis of disturbances and noises in DFACSs,and identifies key areas for future research. 展开更多
关键词 Drag-free DFACS Disturbance Analysis Noise Analysis Frequency Domain Analysis Performance Evaluation
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Analysis and evaluation on pressure fluctuations in air dense medium fluidized bed 认领 引用 被引量：4
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作者 Sheng Cheng Duan Chenlong +2 位作者 Zhao Yuemin Dong Liang Luo Zhenfu 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2018年第3期461-467,共7页
Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and prop... Pressure fluctuations contribute to the instability of separation process in air dense medium fluidized bed, which provides a high motivation for further study of underlying mechanisms. Reasons for generation and propagation of pressure fluctuations in the air dense medium fluidized bed have been discussed.Drift rate and collision rate of particles were employed to deduce the correlation between voidage and pressure fluctuations. Simultaneously, a dynamic pressure fluctuation measuring and analysis system was established. Based on frequency domain analysis and wavelet analysis, collected signals were disassembled and analyzed. Results show gradually intensive motion of particles increases magnitudes of signal components with lower frequencies. As a result of violent particle motion, the magnitude of real pressure signal's frequency experienced an increase as air velocity increased moderately. Wavelet analysis keeps edge features of the real signal and eliminates the noise efficaciously. The frequency of denoised signal is closed to that of pressure signal identified in frequency domain analysis. 展开更多
关键词 Air dense medium fluidized bed Pressure fluctuations Frequency domain analysis Wavelet analysis Particle distribution function
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Transfer function analysis and implementation of active disturbance rejection control 认领 引用 被引量：11
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作者 Gernot Herbst 《Control Theory and Technology》 EI CSCD 2021年第1期19-34,共16页
To support the adoption of active disturbance rejeetion control(ADRC)in industrial practice,this article aims at improv-ing both understanding and implementation of ADRC using traditional means,in particular via trans... To support the adoption of active disturbance rejeetion control(ADRC)in industrial practice,this article aims at improv-ing both understanding and implementation of ADRC using traditional means,in particular via transfer functions and a frequency-domain view.First,to enable an immediate comparability with existing classical control solutions,a realizable transfer function implementation of continous-time linear ADRC is introduced.Second,a frequency-domain analysis of ADRC components,performance,parameter sensitivity,and tuning method is performed.Finally,an exact implementation of discrete-time ADRC using transfer functions is introduced for the first time,with special emphasis on practical aspects such as computational fficiency,low parameter footprint.and windup protection. 展开更多
关键词 Active disturbance rejection control(ADRC) Frequency domain analysis Digital implementation
Dynamic Response Analysis of Risers Subjected to Combined Wave and Current Loading 认领 引用
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作者 Nie, Wu Yu, Xiukun +1 位作者 Ma, Chunyan Li, Weiyang 《China Ocean Engineering》 SCIE EI 1993年第2期147-156,共10页
A dynamic response analysis in the frequency domain is presented for risers subjected to combined wave and current loading. Considering the effects of current, a modified wave spectrum is adopted to compute the linear... A dynamic response analysis in the frequency domain is presented for risers subjected to combined wave and current loading. Considering the effects of current, a modified wave spectrum is adopted to compute the linearized drag force. An additional drag force convolution term is added to the linearized drag force spectrum, therefore the error is reduced which arises from the truncation of higher order terms in the drag force auto-correlation function. An expression of linearized drag force spectrum is given taking the relative velocity into account. It is found that the additional term is a fold convolution integral. In this paper dynamic responses of risers are investigated, while the influence of floater motion on risers is considered. The results demonstrate that the accuracy of the present method reaches the degree required in time domain analysis. 展开更多
关键词 Drag Dynamic loads Dynamic response Frequency domain analysis Loads (forces) Ocean currents Spectrum analysis Time domain analysis Velocity Water waves
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Fractional Envelope Analysis for Rolling Element Bearing Weak Fault Feature Extraction 认领 引用 被引量：9
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作者 Jianhong Wang Liyan Qiao +1 位作者 Yongqiang Ye YangQuan Chen 《IEEE/CAA Journal of Automatica Sinica》 SCIE EI CSCD 2017年第2期353-360,共8页
The bearing weak fault feature extraction is crucial to mechanical fault diagnosis and machine condition monitoring. Envelope analysis based on Hilbert transform has been widely used in bearing fault feature extractio... The bearing weak fault feature extraction is crucial to mechanical fault diagnosis and machine condition monitoring. Envelope analysis based on Hilbert transform has been widely used in bearing fault feature extraction. A generalization of the Hilbert transform, the fractional Hilbert transform is defined in the frequency domain, it is based upon the modification of spatial filter with a fractional parameter, and it can be used to construct a new kind of fractional analytic signal. By performing spectrum analysis on the fractional envelope signal, the fractional envelope spectrum can be obtained. When weak faults occur in a bearing, some of the characteristic frequencies will clearly appear in the fractional envelope spectrum. These characteristic frequencies can be used for bearing weak fault feature extraction. The effectiveness of the proposed method is verified through simulation signal and experiment data. © 2017 Chinese Association of Automation. 展开更多
关键词 Bearings (machine parts) Condition monitoring Extraction Fault detection Feature extraction Frequency domain analysis Hilbert spaces Mathematical transformations Spectrum analysis
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Joint Angle Correction in Rheumatoid Arthritis and Its Reliability Analysis Based on Phase Dispersion Quantification 认领 引用
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作者 Yafei Ou Prasoon Ambalathankandy +2 位作者 Ryunosuke Furuya Tamotsu Kamishima Masayuki Ikebe 《Open Journal of Medical Imaging》 2022年第4期171-179,共9页
Background: Rheumatoid arthritis is a form of autoimmune disease characterized by synovitis that can ultimately cause joint deformities and impaired functioning. The cartilage destruction is one of the most important ... Background: Rheumatoid arthritis is a form of autoimmune disease characterized by synovitis that can ultimately cause joint deformities and impaired functioning. The cartilage destruction is one of the most important indicators for diagnosis and treatment of rheumatoid arthritis, and it is radiographically manifested as joint space narrowing. Issue: In the literature, the joint space narrowing progression between a baseline and its follow-up finger joint images can be quantified by using image registration algorithm. We found that the inconsistencies of joint angles may lead to characteristic mismatches and thus severely affect the accuracy of joint space narrowing quantifications. Methods: In this work, we introduce a rotation invariant phase only correlation in joint space narrowing quantification for the joint angle correction. Further, we propose a confidence index to quantify the quantification reliability of phase only correlation based on phase dispersion in phase difference spectrum. Conclusion: In our clinical experiments, the proposed quantification method can effectively overcome and manage the mismatch due to the inconsistency of joint angles. Additionally, the confidence index shows a high consistency with the joint space narrowing progression examinations manually done by a trained radiologist and one radiological technologist. 展开更多
关键词 Rheumatoid Arthritis Joint Space Narrowing Frequency Domain Analysis Radiology Computer-Aided Diagnosis Phase Dispersion
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Frequency domain based DC fault analysis for bipolar HVDC grids 认领 引用 被引量：13
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作者 Mian WANG Jef BEERTEN Dirk Van HERTEM 《Journal of Modern Power Systems and Clean Energy》 SCIE EI 2017年第4期548-559,共12页
This paper proposes a frequency domain based methodology to analyse the influence of High Voltage Direct Current(HVDC) configurations and system parameters on the travelling wave behaviour during a DC fault. The metho... This paper proposes a frequency domain based methodology to analyse the influence of High Voltage Direct Current(HVDC) configurations and system parameters on the travelling wave behaviour during a DC fault. The method allows us to gain deeper understanding of these influencing parameters. In the literature, the majority of DC protection algorithms essentially use thefirst travelling waves initiated by a DC fault for fault discrimination due to the stringent time constraint in DC grid protection. However, most protection algorithms up to now have been designed based on extensive time domain simulations using one specific test system. Therefore, general applicability or adaptability to different configurations and system changes is not by default ensured, and it is difficult to gain in-depth understanding of the influencing parameters through time domain simulations. In order to analyse the first travelling wave for meshed HVDC grids, voltage and current wave transfer functions with respect to the incident voltage wave are derived adopting Laplace domain based component models. The step responses obtained from the voltage transfer functions are validated by comparison against simulations using a detailed model implemented in PSCADTM. Then, the influences of system parameters such as the number of parallel branches, HVDC grid configurations and groundings on the first travelling wave are investigated by analysing the voltage and current transfer functions. 展开更多
关键词 HVDC grids DC grid protection Travelling wave Frequency domain analysis Transfer function
Design and analysis of an augmented reduced-order active disturbance rejection control for nonlinear uncertain system 认领 引用
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作者 Kaiwen LIU Sen CHEN +1 位作者 Zhi-Liang ZHAO Wenchao XUE 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2026年第2期338-347,共10页
This paper proposes an augmented reduced-order active disturbance rejection control(ARADRC)to address the control challenges in nonlinear systems with unknown disturbances.An augmented reduced-order extended state obs... This paper proposes an augmented reduced-order active disturbance rejection control(ARADRC)to address the control challenges in nonlinear systems with unknown disturbances.An augmented reduced-order extended state observer(ARESO)is constructed to estimate the unmeasured states,the total disturbance,and its derivatives.Compared to conventional ESOs,the proposed ARESO can enhance the estimation performance by actively estimating the derivatives of the total disturbance.In the time domain,by an inductive decoupling-based bound analysis method,this paper rigorously investigates the closed-loop transient performance without the prior assumption on the boundedness of derivatives of nonlinear uncertainties.In the frequency domain,a comparative analysis demonstrates the superiority of ARADRC in both disturbance estimation and rejection.Finally,the magnetic levitation experiments validate the effectiveness of the proposed method. 展开更多
关键词 active disturbance rejection control extended state observer transient performance frequency domain analysis
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Method of evaluation of a mirror surface figure based on frequency domain and its application for the Giant Steerable Science Mirror of the Thirty Meter Telescope 认领 引用 被引量：4
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作者 杨飞 刘国军 +1 位作者 安其昌 张学军 《Chinese Optics Letters》 SCIE EI CAS CSCD 2015年第4期31-36,共6页
We propose a sub-aperture stitching algorithm based on a frequency domain that can be denoted as a power spectral density （PSD）. Our algorithm is verified by the experimental data obtained from measuring a epl.23 m ... We propose a sub-aperture stitching algorithm based on a frequency domain that can be denoted as a power spectral density （PSD）. Our algorithm is verified by the experimental data obtained from measuring a epl.23 m mirror at the Changchun Institute of Optics, Fine Mechanics and Physics. Then, we apply it to the Great Steer- ing Science Mirror （GSSM） of the Thirty Meter Telescope （TMT） with the simulated data before the preliminary design phase, and obtain a more objective result on the frequency domain aberrations. Therefore, the sub-aperture stitching-based PSD is expected to be useful for specifying a large aperture mirror surface for mirror vendors. 展开更多
关键词 Algorithms Frequency domain analysis Optical telescopes Power spectral density Spectral density Telescopes
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All-fiber ring-cavity based frequency swept laser source for frequency domain OCT 认领 引用 被引量：3
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作者 陈明惠 丁志华 +4 位作者 徐磊 吴彤 王川 史国华 张雨东 《Chinese Optics Letters》 SCIE EI CAS 2010年第2期202-205,共4页
We develop a high-speed tunable, quasi-continuous-wave laser source for frequency domain （FD） optical coherence tomography （OCT）. The laser resonance is realized within a unidirectional all-fiber ring cavity consi... We develop a high-speed tunable, quasi-continuous-wave laser source for frequency domain （FD） optical coherence tomography （OCT）. The laser resonance is realized within a unidirectional all-fiber ring cavity consisting of a fiber coupler, two fiber isolators, a semiconductor optical amplifier （SOA）, and a fiber Fabry- Perot tunable filter （FFP-TF） for frequency tuning. Light output from the coupler is further amplified and spectral shaped by a booster SOA terminated at both ends with two isolators. The developed laser source provides up to 8000 sweeps per second over a full-width wavelength tuning range of 120 nm at center wavelength of 1320 nm with an average power of 9 mW, yielding an axial resolution of 13.6μm in air and a maximum sensitivity of about 112 dB for OCT imaging. The instantaneous linewidth is about 0.08 nm, enabling OCT imaging over an axial range of 3.4 mm in air. For optimization consideration based on this custom-built swept laser, experimental study on imaging quality relevant parameters of the swept laser with sine and ramp driving waveforms to the FFP-TF is conducted, and investigation of the swept laser on the cavity length is done. Implementing the laser source in our established swept source based OCT （SS-OCT） system, real-time structural imaging of biological tissue is demonstrated. 展开更多
关键词 Coherent light Fiber optics Fibers Frequency domain analysis Light amplifiers Optoelectronic devices Tomography Tuning
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Fractional Modeling and SOC Estimation of Lithium-ion Battery 认领 引用 被引量：5
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作者 Yan Ma Xiuwen Zhou +1 位作者 Bingsi Li Hong Chen 《IEEE/CAA Journal of Automatica Sinica》 EI 2016年第3期281-287,共7页
This paper proposes a state of charge (SOC) estimator of Lithium-ion battery based on a fractional order impedance spectra model. Firstly, a battery fractional order impedance model is derived on the grounds of the ch... This paper proposes a state of charge (SOC) estimator of Lithium-ion battery based on a fractional order impedance spectra model. Firstly, a battery fractional order impedance model is derived on the grounds of the characteristics of Warburg element and constant phase element (CPE) over a wide range of frequency domain. Secondly, a frequency fitting method and parameter identification algorithm based on output error are presented to identify parameters of the fractional order model of Lithium-ion battery. Finally, the fractional order Kalman filter approach is introduced to estimate the SOC of the lithium-ion battery based on the fractional order model. The simulation results show that the fractional-order model can ensure an acceptable accuracy of the SOC estimation, and the error of estimation reaches maximally up to 0.5% SOC. © 2014 Chinese Association of Automation. 展开更多
关键词 Algorithms Battery management systems Charging (batteries) Electric batteries Frequency domain analysis Ions Kalman filters Lithium Lithium alloys Secondary batteries Solid solutions
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A PMD-supported 100-Gb/s optical frequency-domain IM-DD transmission system 认领 引用 被引量：3
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作者 李蔚 乔耀军 +1 位作者 韩庆生 张欢 《Chinese Optics Letters》 SCIE EI CAS 2009年第8期679-682,共4页
A novel method for distortion-free optical pulse transmission is theoretically proposed and simulated, in which two time lenses formed by dispersion fibers and quadratic phase modulations are utilized. One is used as ... A novel method for distortion-free optical pulse transmission is theoretically proposed and simulated, in which two time lenses formed by dispersion fibers and quadratic phase modulations are utilized. One is used as an optical inverse Fourier transformation （OIFT） device to transform the initial time-domain data to frequency-domain one at the transmitter and the other as an optical Fourier transformation （OFT） device to recover the data at the receiver. By using the unchanged spectral envelope in linear optical fiber communication, the initial data can be recovered. Through simulations, a 10× 100 Gb/s intensity-modulated direct-detection （IM-DD） dense wavelength division multiplexing （DWDM） system over 20000 km transmission without the compensation for polarization mode dispersion （PMD） and dispersion slope is achieved, which can be used to upgrade the current 100Gb/s IM-DD system to a 100-Gb/s one directly. 展开更多
关键词 Dense wavelength division multiplexing Fiber optics Fourier analysis Frequency domain analysis Light transmission Multiplexing Multiplexing equipment Optical communication Optical fibers Optical materials Polarization mode dispersion
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Adaptive frequency domain pre-equalization for white-LED nonlinearity in OFDM-based visible light communication systems 认领 引用 被引量：2
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作者 张汝岐 李建锋 +1 位作者 黄治同 纪越峰 《Chinese Optics Letters》 SCIE EI CAS CSCD 2015年第7期101-104,共4页
In visible light communication, orthogonal frequency division multiplexing （OFDM） is an effective approach to improve the system speed. However, the nonlinearity of the light-emitting diode （LED） suppresses the tr... In visible light communication, orthogonal frequency division multiplexing （OFDM） is an effective approach to improve the system speed. However, the nonlinearity of the light-emitting diode （LED） suppresses the trans- mission performance. The low-frequency part of the transmitted signal from LED suffers more from nonlinearity. Therefore, a pre-equalization scheme which suppresses the low frequency part of the OFDM signal and enhances the high frequency part can decrease the impact of LED nonlinearity. The experimental results show that the bit-error rate performance is largely enhanced by the pre-compensation. 展开更多
关键词 Bit error rate Error compensation Frequency division multiplexing Frequency domain analysis Light Optical communication Orthogonal frequency division multiplexing Visible light communication
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MODAL PARAMETERS EXTRACTION WITH CROSS CORRELATION FUNCTION AND CROSS POWER SPECTRUM UNDER UNKNOWN EXCITATION 认领 引用 被引量：2
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作者 郑敏 申凡 +1 位作者 陈怀海 鲍明 《Chinese Journal of Aeronautics》 EI CAS 2000年第1期19-23,共5页
In most of real operational conditions only response data are measurable while the actual excitations are unknown, so modal parameter must be extracted only from responses. This paper gives a theoretical formulation f... In most of real operational conditions only response data are measurable while the actual excitations are unknown, so modal parameter must be extracted only from responses. This paper gives a theoretical formulation for the cross-correlation functions and cross-power spectra between the outputs under the assumption of white-noise excitation. It widens the field of modal analysis under ambient excitation because many classical methods by impulse response functions or frequency response functions can be used easily for modal analysis under unknown excitation. The Polyreference Complex Exponential method and Eigensystem Realization Algorithm using cross-correlation functions in time domain and Orthogonal Polynomial method using cross-power spectra in frequency domain are applied to a steel frame to extract modal parameters under operational conditions. The modal properties of the steel frame from these three methods are compared with those from frequency response functions analysis. The results show that the modal analysis method using cross-correlation functions or cross-power spectra presented in this paper can extract modal parameters efficiently under unknown excitation. 展开更多
关键词 Algorithms Correlation methods Dynamic response Eigenvalues and eigenfunctions Frequency domain analysis Functions Modal analysis Parameter estimation Structural frames Time domain analysis Vibrations (mechanical) White noise
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New data processing method for improving the measurement accuracy in FTP 认领 引用 被引量：2
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作者 田静 孙杰 +2 位作者 宁韩利 许中奇 杨明 《Optoelectronics Letters》 EI 2011年第1期69-73,共5页
During the 3D shape measurement,there are noises in the images that are obtained by the capture system.The traditional method,Fourier transform profilometry(FTP) technique,improves the accuracy only by the filtering m... During the 3D shape measurement,there are noises in the images that are obtained by the capture system.The traditional method,Fourier transform profilometry(FTP) technique,improves the accuracy only by the filtering method in the frequency domain.In this paper,the curve fitting method is used for the light field distribution calculation before the filtering process applied in the frequency domain by choosing a suitable filter window,and then the higher quality of the basic frequency component signal is got.This method can avoid the frequency overlapping caused by the noise,so the improvement of the measuring accuracy of FTP is realized. 展开更多
关键词 Curve fitting Data handling Fourier transforms Frequency domain analysis Profilometry Three dimensional
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