检索结果-内蒙古大学图书馆

14th International Congress on Sound and Vibration 2007, ICSV 2007

作者： Boczar, Tomasz Lorenc, Marcin Zmarzly, Dariusz Opole University of Technology Faculty of Electrical Engineering Automatic Control and Computer Science Mikolajczyka 5 Opole 45-271 Poland

ISBN: (纸本)9781627480000

The subject matter of this paper refers to vibroacoustic measurements of high power transformers. The evaluation method of the transformer technical condition, based on the measurements of mechanical vibrations of its tub, is characterized. The elements of the measuring set-up, which were used during the registration of the signals coming from the core and winding vibrations of a given transformer unit, transferred by the tub, are presented. Based on the criterion values of the vibroacoustic parameters measured: root-mean-square value of the vibration acceleration and the vibration spectrum amplitude in the frequency range from 0 to 3000 Hz, the evaluation of the technical condition of the power appliance under study was carried out.

关键词： Power transformers

来源：评论

学校读者我要写书评

暂无评论

The result analysis of the sound intensity level generated by a high power transformer

The result analysis of the sound intensity level generated b...

引用

14th International Congress on Sound and Vibration 2007, ICSV 2007

作者： Boczar, Tomasz Lorenc, Marcin Zmarzly, Dariusz Opole University of Technology Faculty of Electrical Engineering Automatic Control and Computer Science Mikolajczyka 5 Opole 45-271 Poland

ISBN: (纸本)9781627480000

The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized. The measurements were taken in 29 points located around the transformer. The evaluation of noise was carried out based on the revised coefficient of the acoustic pressure level. The research work results presented enable the evaluation of the influence of the noise of the unit under study on its environment and make it easier to diagnose the degrees of wear of the fans installed in transformer coolers.

关键词： Power transformers

来源：评论

学校读者我要写书评

暂无评论

The application of electrokinetic zeta potential for determining electrostatic properties of dielectric liquid mixtures

The application of electrokinetic zeta potential for determi...

引用

3rd International Conference on Advances in Processing, Testing and Application of Dielectric Materials, APTADM 2007

作者： Zdanowski, Maciej Kedzia, Józef Technical University of Opole Faculty of Electrical Engineering Automatic Control and Computer Science Mikolajczyka 5 45-272 Opole Poland

The paper presents research results of electrokinetic zeta potential that exists in the electrical double layer on the border of the solid and liquid phases. For zeta potential examination, samples in the colloid form were used, the continuous (dispersing) phase of which was constituted by dielectric liquid mixtures formed on the base of simple hydrocarbons (hexane, cyclohexane, toluene), and the solid (dispersed) phase was constituted by materials in a disintegrated form (aluminum, copper, steatite, Al-70). The measurements were taken with Zetasizer 2000 - by Malvern Instruments (UK). Volume density of charge qw on the border of the solid and liquid phases, responsible for generation of electrostatic charges, was determined based on the measured zeta potential and physicochemical properties of the liquids under study.

关键词： Zeta potential

来源：评论

学校读者我要写书评

暂无评论

Wavelet analysis of the power transformer tub vibrations

Wavelet analysis of the power transformer tub vibrations

引用

14th International Congress on Sound and Vibration 2007, ICSV 2007

作者： Boczar, Tomasz Lorenc, Marcin Zmarzly, Dariusz Opole University of Technology Faculty of Electrical Engineering Automatic Control and Computer Science Mikolajczyka 5 Opole 45-271 Poland

ISBN: (纸本)9781627480000

The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power station. The research tests were carried out during a regular transformer operation in industrial conditions. The measurements were taken from the point of view of the evaluation of the influence of the vibrations registered on the analysis results of the acoustic emission signals generated by partial discharges that can occur in paper-oil insulation systems of power transformers. Moreover, the analyses carried out were supplemented with the research results obtained in laboratory conditions during the measurements taken in the high-voltage testing station of high-voltage power appliances. The influence of the loosened screws fastening the lid of the transformer tub on the time-frequency analysis results obtained of the vibrations registered was investigated. Moreover, the range of the research work carried out referred to the evaluation of the influence of the changes of the pressure force of the metal plates forming the transformer core on the vibration measurement results were obtained. In summary, the evaluation of usefulness was presented and the range of the time-frequency analysis application possibilities, and especially wavelet transforms, in diagnostics of power transformers using the acoustic methods was characterized.

关键词： Power transformers

来源：评论

学校读者我要写书评

暂无评论

Mutual interaction of pulses in three-conductor coupled lines

引用

Archives of electrical engineering 2007年第219-1期56卷 79-87页

作者： Tarczyński, Wieslaw Faculty of Electrical Engineering Automatic Control and Computer Science Opole University of Technology

This paper presents an analysis how the pulses in the long three-conductor coupled lines with common screen interact mutually. The interaction of pulses appears in those places of the line, where there is a change in characteristic impedance causing a change in reflection coefficient for pulses moving along the line. An exemplary analysis is conducted for a homogenous lossless line both at its starting and terminal point. The results of the analysis are analytical expressions describing quantitative interactions of pulses. The expressions are verified numerically and experimentally involving measurements of the real-life line. The mutual interaction of pulses can be useful in location of faults in electric power lines by means of the pulses method.

关键词： electric conductors

来源：评论

学校读者我要写书评

暂无评论

Calculation of core loss using the Jiles-Atherton model incorporated into magnetic field analysis

引用

Archives of electrical engineering 2007年第219-1期56卷 57-69页

作者： Jagiela, Mariusz Institute of Electromechanical Systems and Industrial Electronics Faculty of Electrical Engineering Automatic Control and Computer Science Opole University of Technology

The paper deals with the calculation of hysteresis power loss in cores of electromechanical converters. The analysis was carried out using the Jiles-Atherton model of ferromagnetic hysteresis incorporated into two-dimensional time-stepping finite element model. A vector hysteresis model was constructed by the vectorisation of a scalar model. The total power loss due to hysteresis was split into two component, one originating from the purely alternating magnetic field, and the second being a consequence of the local predomination of vector nature of magnetic field distribution. Two computational examples are presented showing the general applicability of the algorithm for determination of power loss distribution.

关键词： electric losses

来源：评论

学校读者我要写书评

暂无评论

Kernelized Fuzzy c-means Method in Fast Segmentation of Demyelination Plaques in Multiple Sclerosis

Kernelized Fuzzy c-means Method in Fast Segmentation of Demy...

引用

29th Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBS 2007), vol.14

作者： Jacek Kawa Ewa Pietka Faculty of Automatic Control Electronics and Computer Science Department of Biomedical Engineering Gliwic Silesian University of Technology Gliwice Poland

Fuzzy c-means method (FCM) is a popular tool for a fuzzy data processing. In the current study, a FCM-based method of fuzzy clustering in a kernel space has been implemented. First, a "kernel trick" is applied to the fuzzy c-means algorithm. Then, the new method is employed for a fast automated segmentation of demyelination plaques in Multiple Sclerosis (MS). The clusters in a Gaussian kernel space are analysed in the histogram context and used during the initial classification of the brain tissue. Received classification masks are then used to detect the region of interest, eliminate false positives and label MS lesions.

关键词： Multiple sclerosis Kernel Clustering algorithms Image segmentation Prototypes Partitioning algorithms Lesions Magnetic resonance imaging Fuzzy sets Data processing

来源：评论

学校读者我要写书评

暂无评论

DFT algorithm analysis in low-cost power quality measurement systems based on a DSP processor

DFT algorithm analysis in low-cost power quality measurement...

引用

International Conference on electrical Power Quality and Utilisation (EPQU)

作者： Miroslaw Szmajda Krzysztof Gorecki Janusz Mroczka Faculty of Electrical Engineering Automatic Control and Computer Science Opole University of Technology Opole Poland Faculty of Electronics Chair of Electronics and Photonics Metrology Technical University of Wrocław Wroclaw Poland

The application of power quality parameters measurement algorithms requires utilization of computational methods which transform the signal from the time- to the frequency-domain. Currently, the most frequently applied method is the fast Fourier transformation (FFT). Because of the amendment of the proper power quality standards, it is also necessary to consider of implementation discrete Fourier transformation (DFT) algorithms. Considering the number of computations, DFT is more complicated than FFT. This paper presents basic analog-to-digital conversion parameters, which are defined in the norms, the time duration analysis of DFT algorithms, considering described assumptions and comparing them to FFT. Codes created in C and assembler languages, as well as the Matlab/Simulink environment, were taken into account. The software including the aforementioned codes was implemented in a low-cost power quality measurement system based on the TMS320c6713 floating point DSP processor from Texas Instruments. In the software, a real time DSP/BIOS operation system was used. Multi thread programming in power quality measurement systems was presented, and an analysis of computational efficiencies of the systems based on the TMS320c6 713 DSP processors was performed.

关键词： Algorithm design and analysis Power quality Power measurement Digital signal processing Discrete Fourier transforms Frequency measurement Discrete transforms Frequency domain analysis Analog-digital conversion Assembly

来源：评论

学校读者我要写书评

暂无评论

Multi-agent based virtual learning environment. A socio-cultural approach

引用

WSEAS Transactions on Information science and Applications 2007年第1期4卷 30-35页

作者： Moisil, Ioana Pah, Iulian Barbat, Boldur Popa, Emil Marin Faculty of Engineering Computer Science and Automatic Control Dept. Lucian Blaga University of Sibiu Blvd. Victoriei No. 10 Sibiu Romania Faculty of Sciences - Economic Informatics Lucian Blaga University of Sibiu Blvd. Victoriei No. 10 Sibiu Romania Faculty of Sociology and Social Work Babes-Bolyai University of Cluj Napoca Cluj Napoca Romania

In our paper we are proposing a complex model of the student (learner) in a virtual educational environment, supported by a multi-agent system. The whole system is centered on the student and it mainly takes into account Vygotsky's socio-cultural theory that states that social interaction plays a fundamental role in the development of cognition. The model is part of a larger project - DANTE - Socio-Cultural Models implemented through multi-agent architecture for e-learning - that has as main objective the development of a student centred framework for the virtual educational universe that facilitates collaborative learning. The virtual educational world is inhabited by agents: human agents and artificial agents that interact. Agents can be mediating agents, semiotic agents or social agents;they can be intelligent software entities or simple ones, like interface agents.

关键词： Multi agent systems

来源：评论

学校读者我要写书评

暂无评论

Green's Function Estimation in Homogeneous and Scattering Medium for Time Reversal Signal Processing (TRSP) Communication

Green's Function Estimation in Homogeneous and Scattering Me...

引用

International Conference on Digital Telecommunications (ICDT)

作者： Quy Nguyen Dinh Woon-Seng Gan School of Control & Computer Engineering North China Electric Power University Beijing P. R. China Faculty of Science and Technology Sophia University Chiyoda-ku Tokyo JAPAN Graduate School of Information Sciences Tohoku University Aramaki-Aza Sendai Miyagi JAPAN

Time reversal signal processing (TRSP) is a new approach to mitigate the multiple path (multipath) interference in reverberation environment. TRSP has smaller computation resource than classical equalization since TRSP uses phase conjugation technique for compensating distortion. Thus, TRSP technique is applied in receiver for enhancing transmitted code information sequence in communication systems in a highly reverberant environment. The time reversal (TR) operation can be performed either on transmission or reception using estimated Green's function that is spatio-temporal channel response. Thus, Green's function estimation is the first step to set up TR communication. In this paper, Green's function estimation is proposed in homogeneous and scattering medium to establish the feasibility of TRSP in communication. The proposed system can estimate Green's function with minimal computation and better accuracy.

关键词： Green's function methods Signal processing Reverberation Matched filters Acoustic scattering Interference Phase distortion Adaptive signal processing Transmitters Communication channels

来源：评论

学校读者我要写书评

暂无评论

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

请选择保存的检索档案：

请选择收藏分类：

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

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

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：