检索结果-内蒙古大学图书馆

Performance Analysis and Threshold Quantization of Transformer Differential Protection Under Sampled Value Packets Loss/Delay

引用

IEEE ACCESS 2019年 7卷 55698-55706页

作者： He, Ruiwen Peng, Hao Jiang, Qingyun Zhou, Lei Zhu, Jianxin Guangdong Univ Technol Sch Automat Dept Elect Engn Guangzhou 510006 Guangdong Peoples R China

The performance of the process network in the smart substation is particularly important for relaying functions implementation, and the transmission quality of sampled value packets is becoming the key constraint on protections because they carry practical parameters of the power system without repeated transmission. By means of phasor form and simulation, the model is built to analyze the operating characteristics of differential protection during the normal condition, external faults, and internal faults of the transformer, while packet loss/delay occurring at a different time and using different corrective measures. Considering the change of power equipment capacity, external fault types, starting points on wave and sampling frequency, the security boundaries are constructed for consecutive loss of sampled value packets. In addition, two indices are put forward to weigh the tolerance thresholds. Finally, the degree of dependability of differential protection due to the packet loss is further analyzed under the transformer internal faults.

关键词： Boundary analysis estimation algorithm packet loss sampled value (SV) transformer differential protection

来源：评论

学校读者我要写书评

暂无评论

Sigma point Kalman filter for bearing only tracking

引用

SIGNAL PROCESSING 2006年第12期86卷 3769-3777页

作者： Sadhu, S. Mondal, S. Srinivasan, M. Ghoshal, T. K. Jadavpur Univ Dept Elect Engn Kolkata 700032 W Bengal India Indian Inst Technol Dept Mech Engn Kharagpur 721302 W Bengal India

Relative merits of sigma point Kalman filters (SPKF), also known as unscented Kalman filters (UKF) vis-a-vis extended Kalman, filter (EKF) and iterated extended Kalman filter (IEKF) for a bearing-only target-tracking problem using rms error and robustness with respect to outlier initial conditions are explored. After establishing that the rms error performance obtainable by SPKF/UKF and IEKF for this fairly severe non-linear system is similar to those obtainable from other competing techniques, the relative robustness of IEKF, SPKF/UKF and EKF with respect to large initial condition uncertainty (a common occurrence for this class of tracking problems) is investigated. Using several versions of SPKF/UKF, it is shown that SPKF is about 20 times more robust compared to EKF. It is illustrated that the additional design freedom available with a scaled version of SPKF/UKF may be utilised for further improvement of the robustness. The main contribution of this paper is quantification of relative robustness of these non-linear filters. A simplified criterion is suggested and used for quantifying track loss and the relative occurrence of such track loss in batch Monte Carlo simulation has been used as a measure of (lack of) robustness. As the SPKF/UKF does not introduce substantial computational burden, when compared to EKF, it is argued that SPKF/UKF algorithm may become a strong candidate for on-board implementation. (c) 2006 Elsevier B.V. All rights reserved.

关键词： bearings-only tracking estimation algorithm extended Kalman filter unscented Kalman filter filtering techniques Monte Carlo simulation target tracking filters sigma point filters

来源：评论

学校读者我要写书评

暂无评论

A Multicomponent T₂ Relaxometry algorithm for Myelin Water Imaging of the Brain

引用

MAGNETIC RESONANCE IN MEDICINE 2016年第1期75卷 390-402页

作者： Bjork, Marcus Zachariah, Dave Kullberg, Joel Stoica, Petre Uppsala Univ Dept Informat Technol SE-75105 Uppsala Sweden Uppsala Univ Dept Radiol SE-75105 Uppsala Sweden

Purpose: Models based on a sum of damped exponentials occur in many applications, particularly in multicomponent T-2 relaxometry. The problem of estimating the relaxation parameters and the corresponding amplitudes is known to be difficult, especially as the number of components increases. In this article, the commonly used non-negative least squares spectrum approach is compared to a recently published estimation algorithm abbreviated as Exponential Analysis via System Identification using Steiglitz-McBride. Methods: The two algorithms are evaluated via simulation, and their performance is compared to a statistical benchmark on precision given by the Cramer-Rao bound. By applying the algorithms to an in vivo brain multi-echo spin-echo dataset, containing 32 images, estimates of the myelin water fraction are computed. Results: Exponential Analysis via System Identification using Steiglitz-McBride is shown to have superior performance when applied to simulated T-2 relaxation data. For the in vivo brain, Exponential Analysis via System Identification using Steiglitz-McBride gives an myelin water fraction map with a more concentrated distribution of myelin water and less noise, compared to non-negative least squares. Conclusion: The Exponential Analysis via System Identification using Steiglitz-McBride algorithm provides an efficient and user-parameter-free alternative to non-negative least squares for estimating the parameters of multiple relaxation components and gives a new way of estimating the spatial variations of myelin in the brain. (C) 2015 Wiley Periodicals, Inc.

关键词： multicomponent T-2 relaxometry estimation algorithm myelin water fraction in vivo brain

来源：评论

学校读者我要写书评

暂无评论

Concatenated fibre-wireless channel identification in a multiuser CDMA environment

引用

IET COMMUNICATIONS 2007年第5期1卷 937-944页

作者： Pinter, S. Z. Fernando, X. N. Ryerson Univ Dept Elect & Comp Engn Toronto ON M5B 2K3 Canada

Radio-over-fibre (ROF) has received increasing attention for its ability to enable broadband wireless access. This fibre-based wireless access scheme meets the demand for broadband service by integrating the high capacity of optical networks with the flexibility of radio networks (the optical and wireless channels are concatenated with one another). There are, however, impairments that come with this appealing technology. The nonlinear distortion of the optical link and the multipath dispersion of the wireless channel are two of the major factors. In order to limit the effects of these distortions, estimation, and subsequently equalisation, of the concatenated fibre-wireless channel needs to be done. An estimation algorithm for the fibre-wireless uplink in a multiuser code division multiple access (CDMA) environment is presented using pseudonoise training sequences. It has already been shown by Fernando et al. (2001) that identification of the fibre-wireless uplink is possible in a single user CDMA environment. However, the more difficult task of identification in a multiuser spread spectrum environment, which is more realistic, is shown. In the multiuser case, the cumulative effect of multiuser interference, multipath dispersion, nonlinear distortion and noise should all be handled together which makes it more challenging. Numerical evaluations of the developed algorithm show that a good estimation of both the linear and nonlinear systems is possible in the presence of 16 independent users and an signal-to-noise ratio (SNR) of 22 dB. The estimation accuracy increases with the length of the PN sequence.

关键词： multipath dispersion multiuser CDMA environment optical network multiuser spread spectrum environment code division multiple access nonlinear distortion optical link radio-over-fibre broadband networks optical fibre networks estimation algorithm broadband wireless access scheme wireless channels concatenated fibre-wireless channel identification channel estimation multiuser channels

来源：评论

学校读者我要写书评

暂无评论

Enhancing algorithmic base for discrete choice modelling

引用

KSCE JOURNAL OF CIVIL ENGINEERING 2013年第7期17卷 1798-1809页

作者： Roh, Hyuk-Jae Khan, Ata M. Minist Highways & Infrastruct Govt Saskatchewan Regina SK S4N 2G1 Canada Carleton Univ Dept Civil & Environm Engn Ottawa ON K1S 5B6 Canada

Frequently, discrete choice modelling process is constrained due to lack of information on alternative estimation methods and the inability of commercial software to enable comparative efficiency tests. Further, the underlying numerical operational procedures used in the software are not displayed to the user. This paper reports research on the comparative efficiency of four selected algorithms that are combined with the Maximum Likelihood method in computationally logical way for estimating the parameters of Multinomial Logit travel mode choice model. The algorithms were formulated and numerical experiments were designed for the comparison of their estimation performance in an access to airport mode choice case study. Also, the important factors of econometric model estimation, namely step size, convergence criterion, and initial guessing of the starting points are studied. The process used here can be applied to mixed logit or other discrete choice model formulations. The findings of this research are expected to enhance discrete choice modelling in transportation planning and will be useful to researchers who wish to develop computer code encompassing estimation algorithms of their choice.

关键词： discrete choice model mode choice model multinomial logit model estimation algorithm maximum likelihood method newton raphson steepest ascent BHHH BHHH-2

来源：评论

学校读者我要写书评

暂无评论

Receiver-aided predistortion of power amplifier non-linearities in cellular networks

引用

IET SCIENCE MEASUREMENT & TECHNOLOGY 2012年第3期6卷 168-175页

作者： Zeleny, J. Dehos, C. Rosson, P. Kaiser, A. CEA LETI F-38054 Grenoble France IEMN ISEN Dept F-59000 Bd Vauban France

In this study a novel scheme of predistortion of power amplifier non-linearities is developed and demonstrated. The originality of the proposed system architecture is that the estimation of non-linearities is carried out at the receiver, thanks to a training sequence, and sent back to the transmitter for predistortion. The proposed architecture achieves efficient compensation of power amplifier non-linearities on WiMAX and long-term evolution (LTE) standards without extra hardware. An evaluation of power consumption savings is carried out, considering digital consumption of the estimation algorithm at the receiver side and predistortion look up table refreshment at the transmitter side. The results show that the suggested architecture can be applied for high data rate systems at base stations, relay stations and mobile stations as well.

关键词： base stations power consumption savings relay stations receiver-aided predistortion estimation algorithm radio transmitters long-term evolution standards LTE standards Mobile radio systems WiMax power consumption radio receivers cellular networks mobile stations digital consumption high data rate systems power amplifiers WiMAX nonlinearities estimation transmitter power amplifier nonlinearities Long Term Evolution Amplifiers predistortion look training sequence

来源：评论

学校读者我要写书评

暂无评论

An extended Markov-switching model approach to latent heterogeneity in departmentalized manpower systems

引用

COMMUNICATIONS IN STATISTICS-THEORY AND METHODS 2024年第19期53卷 6957-6976页

作者： Ossai, Everestus O. Nduka, Uchenna C. Madukaife, Mbanefo S. Udom, Akaninyene U. Ugwu, Samson O. Univ Nigeria Dept Stat Nsukka Nigeria

In recent works in manpower planning interest has been awakened in modeling manpower systems in departmentalized framework. This, as a form of disaggregation, may solve the problem of observable heterogeneity but not latent heterogeneity;it rather opens up other aspects of latent heterogeneity hitherto unaccounted for in classical (non departmentalized) manpower models. In this article, a multinomial Markov-switching model is formulated for investigating latent heterogeneity in intra-departmental and interdepartmental transitions in departmentalized manpower systems. The formulation incorporates extensions of the mover-stayer principle resulting in several competing models. The best manpower model is chosen based on the optimum number of hidden states established by the use of Expectation-Maximization iterative algorithm for estimation of the model parameters and a search procedure for assessing model performance against one another. The illustration establishes the usefulness of the model formulation in highlighting hidden disparities in personnel transitions in a departmentalized manpower system and in avoiding wrong model specification.

关键词： Markov-switching model departmentalized manpower latent heterogeneity estimation algorithm optimum state Manpower planning Latent heterogeneity in departmentalized manpower systems Markov processes Extended Markov-switching model approach

来源：评论

学校读者我要写书评

暂无评论

A Filtering Based Multi-innovation Extended Stochastic Gradient algorithm for Multivariable Control Systems

引用

INTERNATIONAL JOURNAL OF CONTROL AUTOMATION AND SYSTEMS 2017年第3期15卷 1189-1197页

作者： Pan, Jian Jiang, Xiao Wan, Xiangkui Ding, Wenfang Hubei Univ Technol Sch Elect & Elect Engn Wuhan 430068 Peoples R China

For a multivariable system with moving average noise (i.e., a multivariable controlled autoregressive moving average system), this paper proposes a filtering based extended stochastic gradient (ESG) algorithm and a filtering based multi-innovation ESG algorithm for improving the parameter estimation accuracy. The key is using the filtering technique and the multi-innovation identification theory. The proposed algorithms can identify the parameters of the system model and the noise model. The filtering based multi-innovation ESG algorithm can give more accurate parameter estimates. The numerical simulation results demonstrate that the proposed algorithms work well.

关键词： estimation algorithm filtering gradient search multi-innovation identification parameter estimation stochastic system

来源：评论

学校读者我要写书评

暂无评论

Ultra wideband indoor navigation system

引用

IET RADAR SONAR AND NAVIGATION 2012年第5期6卷 402-411页

作者： Segura, M. Mut, V. Sisterna, C. Natl Univ San Juan Automat Inst San Juan City Argentina Natl Univ San Juan Dept Elect San Juan City Argentina

Typical indoor environments contain multiple walls and obstacles consisting of different materials. As a result, current narrowband radio frequency (RF) indoor navigation systems cannot satisfy the challenging demands for most indoor applications. The RF ultra wideband (UWB) system is a promising technology for indoor localisation owing to its high bandwidth that permits mitigation of the multipath identification problem. This work proposes a novel UWB navigation system that permits accurate mobile robot (MR) navigation in indoor environments. The navigation system is composed of two sub-systems: the localisation system and the MR control system. The main contributions of this work are focused on estimation algorithm for localisation, digital implementation of transmitter and receiver and integration of both sub-systems that enable autonomous robot navigation. For sub-systems performance evaluation, statics and dynamics experiments were carried out which demonstrated that the proposed system reached an accuracy that outperforms traditional sensors technologies used in robot navigation, such as odometer and sonar.

关键词： autonomous robot navigation performance evaluation ultra wideband communication narrowband radiofrequency indoor navigation mobile robot navigation mobile robots indoor radio sonar navigation indoor localisation MR control system Radio links and equipment multipath identification problem Mobile robots estimation algorithm odometer ultra wideband indoor navigation system

来源：评论

学校读者我要写书评

暂无评论

Diffuse Initialization of Kalman Filter

引用

JOURNAL OF AUTOMATION AND INFORMATION SCIENCES 2011年第4期43卷 20-34页

作者： Skorokhod, B. A. Sevastopol Natl Tech Univ Sevastopol Ukraine

The behavior of Kalman filter is studied at interpretation of unknown initial conditions as the random variables having a covariance matrix proportional to large positive parameter. The developed approach allows one to express characteristics of the filter in an analytic form, to explain a phenomenon of divergence and propose a limiting estimation algorithm which is independent of large initial parameter leading to divergence. As the application there were considered two problems: filtering with a sliding window and a parameter estimation of separable regression. The received results are illustrated by example of training a radial basic neural network.

关键词： Kalman filter random variables covariance matrix estimation algorithm separable regression

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：