电子式互感器在数字化变电站中的应用

本文就电子式互感器在数字化变电站中的应用进行了探讨,结合了具体的实例,通过对电子式互感器的工作原理进行分析,对比有源和无源两种类型的电子式互感器技术的优缺点,从而总结出有源电子式互感器优于无源电子式互感器,其具有较好的稳定性、抗震动以及受温度影响小等工程应用特性,还根据一些应用上的问题,提出了解决措施,以期能为电子式互感器更好地应用于数字化变电站中提供参考。     

Exponential l 2–l ∞ Control for Discrete-Time Switching Markov Jump Linear Systems

The problem of exponential l ₂–l _∞ control is considered in this paper for a class of discrete-time switching Markov jump linear systems. First, the definition of exponential l ₂–l _∞ mean square stability for discrete-time switching Markov jump linear systems is introduced. Then, by resorting to the average dwell time approach, the mean square exponential stability criteria are presented with an exponential l ₂–l _∞ performance index and a decay rate, and the corresponding controller is also designed. Finally, numerical and application examples are provided to demonstrate the effectiveness of the obtained results.     

分布式发电并网系统综述

随着分布式发电(Distributed Generation)应用的增加,越来越多的分布式发电正在接入电网,由此带来的并网问题日益重要:并网系统(包括硬件和软件)主要用来连接分布式发电和电网(通常是本地电网),本文主要讨论了分布式发电与电网之间的并网类型,并网系统的分类、功能、主要结构及采取的控制方法,并简要介绍了现有的分布式发电并网导则。     

P2P流量优化技术及标准化进展

文章综述了P2P流量优化的技术路线（P2P应用层优化和层间协同机制）,介绍了目前具有代表性的一些解决方案,如应用层优化方案IDMaps、Vivaldi、iPlan、OnO,层间协作方案P4P、Oracle、PPM和DDP,以及国内外标准化组织标准推进情况。     

ICI cancellation for OFDM communication systems in time-varying multipath fading channels

In orthogonal frequency division multiplexing (OFDM) systems, time-varying multipath fading leads to the loss of subcarrier orthogonality and the occurrence of intercarrier interference (ICI). In this study, an efficient ICI suppression with less noise enhancement for multicarrier equalization is presented by using a parallel canceling scheme via frequency-domain equalization techniques, with the assumption that the channel impulse response (CIR) varies linearly during a block period. In order to avoid performance deterioration due to unreliable initial estimations in the parallel cancellation scheme, a cost function with proper weighting factor is introduced to improve the performance of the proposed equalizer. The proposed equalizer consists of a set of prefilters and a set of ICI cancellation filters, with two stages to perform different functions to achieve minimum mean square error (MMSE) equalization. The prefilters compensate for the multiplicative distortion at the first stage, and the ICI cancellation filters remove the effects of ICI by a parallel cancellation scheme at the second stage. Finally, the performance of the proposed equalizer is analyzed and compared with that of other equalizers, indicating significant performance improvement.     

基于PXI平台的环境试验并行测试系统设计

为提高测试的通用化、自动化、智能化,缩短试验时间,节省试验成本,提出了一种基于面向仪器系统的PCI扩展(PCI Extensions for Instrumentation,PXI)平台的自动流程执行架构,以及柔性测试流程配置的环境试验并行测试系统,该并行测试系统在换流器等产品环境试验中得到了应用,并实践验证取得的效果良好。     

高校计算机公共机房管理研究

大学计算机实验室不仅是教育和实践的场所,还是学生学习知识的主要平台.为了提高教育质量,许多大学都建立了大型计算机实验室.由于规模大,它受硬件和软件故障或安全管理问题等多个因素的影响,并且发生的频率相对较高.良好的计算机实验室管理和维护可以为师生提供稳定的网络环境.文章旨在研究如何保持计算机在大学计算机实验室中运行,如何...     

A novel rate control algorithm for video coding based on fuzzy-PID controller

Rate control algorithms (RCAs) aim to achieve the best visual quality under the minimum bit rate and the limited buffer size. A self-parameter-tuning fuzzy-PID controller is proposed to reduce the deviation between the target buffer level and the current buffer fullness. Fuzzy logic is used to tune each parameter of the proportional-integral-derivative controller by selecting appropriate fuzzy rules through simulation in H.264/advanced video coding (AVC). To control the quality fluctuation between consecutive frames, a quality controller is adopted. The proposed RCA has been implemented in an H.264/AVC video codec, and our experimental results show that the proposed algorithm achieves smooth target bits while enabling better buffer control and visual quality.     

Interaction of Human Mesenchymal Stem Cells with Soft Nanocomposite Hydrogels Based on Polyethylene Glycol and Dendritic Polyglycerol

Keeping the stemness of human mesenchymal stem cells (hMSCs) and their adipocyte differentiation potential is critical for clinical use. However, these features are lost on traditional substrates. hMSCs have often been studied on stiff materials whereas culturing hMSCs in their native niche increases their potential. Herein, a patterned hydrogel nanocomposite with the stiffness of liver tissues is obtained without any molding process. To investigate hMSCs' mechanoresponse to the material, the RGD spacing units and the stiffness of the hydrogels are dually tuned via the linker length. This work suggests that hMSCs' locomotion is influenced by the nature of the hydrogel layer (bulk or thin film). Contrary to on bulk surfaces, cell traction occurs during cell spreading on thin films. In addition, hMSCs' spreading behavior varies from shorter to longer linker‐based hydrogels, where on both surfaces hMSCs maintains their stemness as well as their adipogenic differentiation potential with a higher number of adipocytes for nanocomposites with a longer polymer linker. Overall, this work addresses the need for a new alternative for hMSCs culture allowing the cells to differentiate exclusively into adipocytes. This material represents a cell‐responsive platform with a tissue‐mimicking architecture given by the mechanical and morphological properties of the hydrogel.     

Region-based image coding with multiple algorithms

The wide usage of small satellite imagery, especially its commercialization, makes data-based onboard compression not only meaningful but also necessary in order to solve the bottleneck between the huge volume of data generated onboard and the very limited downlink bandwidth. The authors propose a method that encodes different regions with different algorithms. The authors use three shape-adaptive image compression algorithms as the candidates. The first one is a JPEG-based algorithm, the second one is based on the object-based wavelet transform method proposed by Katata et al. (1997), and the third adopts Hilbert scanning of the regions of interest followed by one-dimensional (1-D) wavelet transform. The three algorithms are also applied to the full image so that one can compare their performance on a whole rectangular image. The authors use eight Landsat TM multispectral images and another 12 small satellite single-band images as their data set. The results show that these compression algorithms have significantly different performance for different regions