检索结果-南通市图书馆

Dynamic analysis and identification of unbalance and misalignment in a rigid rotor with two offset discs levitated by active magnetic bearings:a novel trial misalignment approach

引用

Propulsion and Power Research 2021年第1期10卷 58-82页

作者： Prabhat Kumar Rajiv Tiwari Department of Mechanical Engineering Indian Institute of Technology GuwahatiGuwahatiAssam781039India

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries,transport vehicles,and in several other *** vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous ***,there is a need for perceiving the dynamic nature and identifying the faults for the safe,smooth and effective operation of *** paper proposes a novel trial misalignment approach to estimate the misalignment with a similar concept as the trial unbalance in the rotor *** magnetic bearing(AMB)misalignment with the rotor has been investigated with residual misalignment and additional trial misalignment *** trial misalignments are provided in addition to the unknown misalignments of the residual misalignment *** the execution of this methodology,the dynamic model of a four-degree-of-freedom unbalanced and misaligned rigid rotor with two offset discs supported by two active magnetic bearings has been mathematically *** offset discs result in the gyroscopic effect at high rotor *** of motion of the rotor-AMB system have been derived and solved to generate the time domain rotor displacement and controlling current responses at AMB positions.A fast fourier transform technique has been utilized to convert the time domain responses into the frequency domain for estimation of unbalance eccentricities and phases together with force-displacement and forcecurrent stiffnesses of misaligned AMBs as well as AMB's constant forces using the developed identification *** values of AMB's parameters for both residual and additional trial misalignment cases are evaluated to estimate the four unknown *** of the algorithm has also been carried out at multiple spin speeds against measurement signal noise in rotor responses and bias errors in rotor system parameters to check its effectiveness

关键词： Misalignment Unbalance Active magnetic bearing Gyroscopic moment fast fourier transform Identification

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

MPFFT：An Auto-Tuning FFT Library for OpenCL GPUs

引用

Journal of Computer Science & Technology 2013年第1期28卷 90-105页

作者： Yan Li Yun-Quan Zhang Yi-Qun Liu Guo-Ping Long Hai-Peng Jia Institute of Software Chinese Academy of Sciences Beijing 100190 China Graduate University of Chinese Academy of Sciences Beijing 100049 China School of Information Science and Engineering Ocean University of China Qingdao 266000 China

fourier methods have revolutionized many fields of science and engineering, such as astronomy, medical imaging, seismology and spectroscopy, and the fast fourier transform （FFT） is a computationally efficient method of generating a fourier transform. The emerging class of high performance computing architectures, such as GPU, seeks to achieve much higher performance and efficiency by exposing a hierarchy of distinct memories to software. However, the complexity of GPU programming poses a significant challenge to developers. In this paper, we propose an automatic performance tuning framework for FFT on various OpenCL GPUs, and implement a high performance library named MPFFT based on this framework. For power-of-two length FFTs, our library substantially outperforms the cIAmdFft library on AMD GPUs and achieves comparable performance as the CUFFT library on NVIDIA GPUs. Furthermore, our library also supports non-power-of-two size. For 3D non-power-of-two FFTs, our library delivers 1.5x to 28x faster than FFTYV with 4 threads and 20.01x average speedup over CUFFT 4.0 on Tesla C2050.

关键词： fast fourier transform GPU OpenCL auto-tuning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Spectral Analysis and Validation of Parietal Signals for Different Arm Movements

引用

Intelligent Automation & Soft Computing 2023年第6期36卷 2849-2863页

作者： Umashankar Ganesan A.Vimala Juliet R.Amala Jenith Joshi School of Electrical and Electronics Engineering Sathyabama Institute of Science and TechnologyChennai600119India School of Electronics and Instrumentation Engineering SRM Institute of Science and TechnologyChennai630203India Department of Biomedical and Mechanical Engineering School of EngineeringNational University of IrelandGalwayH91 CF50Ireland

Brain signal analysis plays a significant role in attaining data related to motor *** parietal region of the brain plays a vital role in muscular *** approach aims to demonstrate a unique technique to identify an ideal region of the human brain that generates signals responsible for muscular movements;perform statistical analysis to provide an absolute characterization of the signal and validate the obtained results using a prototype *** can enhance the practical implementation of these frequency extractions for future neuro-prosthetic applications and the characterization of neurological diseases like Parkinson’s disease(PD).To play out this handling method,electroencepha-logram(EEG)signals are gained while the subject is performing different wrist and elbow ***,the frontal brain signals and just the parietal signals are separated from the obtained EEG signal by utilizing a band pass ***,feature extraction is carried out using fast fourier transform(FFT).Subse-quently,the extraction process is done by Daubechies(db4)and Haar wavelet(db1)in MATLAB and classified using the Levenberg-Marquardt *** results of the frequency changes that occurred during various wrist move-ments in the parietal region are compared with the frequency changes that occurred in frontal EEG *** proposed algorithm also uses the deep learn-ing pattern analysis network to evaluate the matching sequence for each action that takes *** accuracy of 97.2%and maximum error range of 0.6684%are achieved during the *** of this research confirm that the Levenberg-Marquardt algorithm,along with the newly developed deep learn-ing hybrid PatternNet,provides a more accurate range of frequency changes than any other classifier used in previous works of *** on the analysis,the peak-to-peak value is used to define the threshold for the prototype arm,which performs all the intended degrees of freedom(DOF),verifying

关键词： Parietal EEG signals fast fourier transform Levenberg-Marquardt algorithm haar wavelet daubechies wavelet statistical analysis

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Method of Fundamental Solutions for Solving Exterior Axisymmetric Helmholtz Problems with High Wave-Number

引用

Advances in Applied Mathematics and Mechanics 2013年第4期5卷 477-493页

作者： Wen Chen Ji Lin C.S.Chen College of Engineering Mechanics Hohai UniversityNanjing 210098JiangsuChina Department of Mathematics University of Southern MississippiHattiesburgMS 39406USA

In this paper,we investigate the method of fundamental solutions(MFS)for solving exterior Helmholtz problems with high wave-number in axisymmetric *** the coefficientmatrix in the linear system resulting fromtheMFS approximation has a block circulant structure,it can be solved by the matrix decomposition algorithm and fast fourier transform for the fast computation of large-scale problems and meanwhile saving computer memory *** numerical examples are provided to demonstrate its applicability and efficacy in two and three dimensional domains.

关键词： Method of fundamental solutions exterior Helmholtz problem circulant matrix fast fourier transform axisymmetric domain

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frequency spectrum might act as communication code between retina and visual cortex Ⅰ

引用

International Journal of Ophthalmology(English edition) 2015年第6期8卷 1107-1111页

作者： Xu Yang Bo Gong Jian-Wei Lu Life Science School Fudan University Department of Chemical and Biological Engineering Institute of Bioengineering Zhejiang University Department of Ophthalmology Shanghai Tenth People's Hospital the Advanced Institute of Translational Medicine and School of Software Engineering Tongji University

AIM: To explore changes and possible communication relationship of local potential signals recorded simultaneously from retina and visual cortex I(V1).·METHODS: Fourteen C57BL/6J mice were measured with pattern electroretinogram(PERG) and pattern visually evoked potential(PVEP) and fast fourier transform has been used to analyze the frequency components of those signals.· RESULTS: The amplitude of PERG and PVEP was measured at about 36.7 μV and 112.5 μV respectively and the dominant frequency of PERG and PVEP, however,stay unchanged and both signals do not have second, or otherwise, harmonic generation.· CONCLUSION: The results suggested that retina encodes visual information in the way of frequency spectrum and then transfers it to primary visual *** primary visual cortex accepts and deciphers the input visual information coded from retina. Frequency spectrum may act as communication code between retina and V1.

关键词： pattern electroretinogram pattern visually evoked potential fast fourier transform retina visual cortex Ⅰ

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A novel dense spectrum correction algorithm for extracting vibration signals in internal combustion engine and its application

引用

Journal of Central South University 2012年第10期19卷 2810-2815页

作者：张志刚鄂加强张桂香 College of Mechanical and Vehicle Engineering Hunan University Department of Electron and Communication Engineering Changsha University

The algorithm of dense spectrum correction has been raised and proved based on the correction of discrete spectrum by fast fourier *** result of simulation shows that such algorithm has advantages of high accuracy and small amount of *** algorithm has been successfully applied to the analysis of vibration signals from internal combustion *** calculate discrete spectrum,fast fourier transform has been used to calculate the discrete spectrum by the signals acquired by the sensors on the oil pan,and the signal has been extracted from the mixed signals.

关键词： fast fourier transform discrete spectrum correction dense spectrum correction signal extracting

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

High-Accuracy Polishing Technique Using Dwell Time Adjustment

引用

Communications in Computational Physics 2006年第4期1卷 701-715页

作者： S.Satake K.Yamamoto S.Igarashi Department of Applied Electronics Tokyo University of Science2641 YamazakiNodaChiba 278-8510Japan

Two algorithms for dwell time adjustment are evaluated under the same polishing conditions that involve tool and work *** methods are based on Preston’s *** first method is a convolution algorithm based on the fast fourier *** second is an iterative method based on a constraint problem,extended from a one-dimensional formulation to address a two-dimensional *** methods are investigated for their computational cost,accuracy,and polishing *** convolution method has high accuracy and high *** constraint problem on the other hand is slow even when it requires larger memory and thus is more ***,unlike the other case a negative region in the polishing shape is not predicted ***,new techniques are devised by combining the two methods.

关键词： Polishing surface grinding dwell time convolution method fast fourier transform constraint problem

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Extraction of Signal Frequency in Laser Ranging of Space Target Based on FPGA

引用

Wuhan University Journal of Natural Sciences 2021年第3期26卷 215-226页

作者： YANG Haima JIN Yan ZHAO Xiao QIANG Jia LIU Jin JIANG Bin LIU Xin College of Optoelectronic Information and Computer Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Space Active Opto-Electronics Technology Chinese Academy of SciencesShanghai 200083China Shanghai Institute of Technical Physics Chinese Academy of SciencesShanghai 200083China College of Electronic and Electrical Engineering Shanghai University of Engineering ScienceShanghai 201620China

Aiming at the problems in a linear frequency modulation continuous wave(LFMCW)ranging lidar system,such as low signal-to-noise in echo beat frequency and difficult extraction of the signal frequency,a method with high-speed and high accuracy based on field programmable gate array(FPGA)is ***,the laser echo beat signal is sampled by high-speed analog to digital converter(ADC)and then processed in FPGA for data *** the signal is processed by the 8192-point FPGA will obtain the frequency spectrum and then apply the frequency spectrum to data processing and adaptive noise signal peak *** two steps realize the real-time and accurate extraction process of the target echo beat signal ***,the spectrum data is transmitted to the host computer and processed through the external data acquisition board for real-time spectrum *** results show that data preprocessing and spectrum data processing can effectively suppress DC bias and system modulation *** noise peak detection can accurately divide the threshold contour according to the dynamic noise of the system and realize the detection of target signal *** the sampling clock of the system is 100 MHz,the time needed for each calculation of the spectrum is 81.92μs,and the refresh rate of the spectrum reaches 12.2 kHz,which meets the real-time requirements of the system.

关键词： digital signal processing LFMCW ranging fast fourier transform FPGA

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Derivation of FFT numerical bounds of the effective properties ofcomposites and polycristals

引用

Theoretical & Applied Mechanics Letters 2021年第2期11卷 94-101页

作者： Minh-Tan Nguyen Quy-Dong To Vincent Monchiet Univ Gustave Eiffel Univ Paris Est CreteilCNRSMSME UMR 8208F-77454 Marne-la-VallÃl’eFrance

In this paper,we provide exact fast fourier transform(FFT)-based numerical bounds for the elastic prop-erties of composites having arbitrary *** bounds,an upper and a lower,are derivedby considering usual variational principles based on the strain and the stress *** bounds arecomputed by solving the Lippmann-Schwinger equation together with the shape coefficients which al-low an exact description of the microstructure of the *** coefficients are the exact fouriertransform of the characteristic functions of the *** this study,the geometry of the microstructureis approximated by polygonals(two-dimensional,2D objects)and by polyhedrons(three-dimensional,3Dobjects)for which exact expressions of the shape coefficients are *** applications are pre-sented in the paper showing the relevance of the *** the first benchmark example,we considerthe case of a composite with *** effective elastic coefficients ares derived and compared,consider-ing the exact shape coefficient of the circular inclusion and its approximation with a ***,thehomogenized elastic coefficients are derived for a composite reinforced by 2D flower-shaped inclusionsand with 3D toroidal-shaped ***,the method is applied to polycristals considering Voronoitessellations for which the description with polygonals and polyhedrons becomes *** comparisonwith the original FFT method of Moulinec and Suquet is provided in order to show the relevance of thesenumerical bounds.

关键词： Composites Homogenization fast fourier transform Numerical bounds

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Application of short-time fourier transform to high-rise frame structural-health monitoring based on change of inherent frequency over time

引用

Journal of Chongqing University 2017年第1期16卷 1-10页

作者：郭少霞 PEI Qiang The R&D Center of Civil Engineering Technology Dalian University Dalian 116622 P. R. China

The high-rise frame structure has become more and more widespread, like its damage from the complication of the environment. The traditional method of damage detection, which is only suitable for the stationary signal, does not apply to a high-rise frame structure because its damage signal is non-stationary. Thus, this paper presents an application of the short-time fourier transform(STFT) to damage detection of high-rise frame structures. Compared with the fast fourier transform, STFT is found to be able to express the frequency spectrum property of the time interval using the signal within this interval. Application of STFT to analyzing a Matlab model and the shaking table test with a twelve-story frame-structure model reveals that there is a positive correlation between the slope of the frequency versus time and the damage level. If the slope is equal to or greater than zero, the structure is not damaged. If the slope is smaller than zero, the structure is damaged, and the less the slope is, the more serious the damage is. The damage results from calculation based on the Matlab model are consistent with those from the shaking table test, demonstrating that STFT can be a reliable tool for the damage detection of high-rise frame structures.

关键词： short-time fourier transform fast fourier transform damage identification shaking table test time-frequency analysis

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：