Old and new from SOR

From the long history of Successive Over Relaxation (SOR) between the end of second world war and today three points are considered: (1) Classical results of Young and Varga are described. (2) It is shown how results on semiiterative methods can be used to derive these classical results in a unifying way and to compare SOR with other iterative methods. (3) In the last 15 years the application of SOR to compute the stationary distribution of a homogeneous Markov chain has been discussed. These results are reported, considering especially the term extended convergence introduced by Kontovasilis, Plemmons and Stewart.     

Optimal coordination of directional over-current relays using informative differential evolution algorithm

Growing interconnection in distribution system creates new problem for protection engineers. Particularly the design of overcurrent relay coordination in such system is an independent area of research. With the availability of new artificial based optimization algorithm relay coordination research gain a new momentum. Well established artificial based optimization algorithm such as genetic and particle swam optimization are successfully applied for such applications. This paper discusses the application of informative differential evolution algorithm with self adaptive re-clustering technique for selection of TDS and PSM for optimal coordination of directional overcurrent relays. Both continuous as well as discrete version of informative differential evolution algorithm are used for optimization of relay setting. Proper combination of backup relays for each primary relay are identified by using LINKNET graph theory approach. Coordination of directional overcurrent is developed for 9 bus and IEEE 30 bus distribution systems. The aim of problem is to minimize the total operating time of primary relays and eliminate the miscoordination among the primary and backup relay pairs. Discrete types of settings for electromechanical types of relay are also discussed in this paper. Moreover, the relay coordination problem is modified for providing optimal coordination time interval between 0.2 and 0.8 s among all primary and backup relays pairs. The results are compared with hybrid of genetic algorithm – nonlinear programming and sequential quadratic programming. Digsilient power factory software is used for verification of result.     

Over voltage in the multi-sectioned superconducting solenoid during quenching

Accurate analysis of over voltage in the superconducting solenoid during a quench is one of the basis for quench protection system design. Classical quench simulation methods can only give rough estimation of the over voltage within a magnet coil. In this paper, for multi-sectioned superconducting solenoid, based on the classical assumption of ellipsoidal normal zone, three-dimension temperature results are mapped to one-dimension along the wire, the temperature distribution along the wire and the resistances of each turn are obtained. The coil is treated as circuit comprised of turn resistances, turn self and mutual inductances. The turn resistive voltage, turn inductive voltage, and turn resultant voltage along the wire are calculated. As a result, the maximum internal voltages, the layer-to-layer voltages and the turn-to-turn voltages are better estimated. Utilizing this method, the over voltage in a small solenoid and a large solenoid during quenching have been studied. The result shows that this method can well improve the over voltage estimate, especially when the coil is larger.     

降低OFDM系统峰均比的可恢复限幅技术(英文)

针对正交频分复用系统中峰值平均功率比过高的问题,提出了一种基于限幅技术的改进算法.该算法对限幅后的信号进行标记,并将标记序列发送到接收端,从而使得接收端能够正确的解调出输入信号.此外,本文还将该改进算法应用于光载无线通信系统中.仿真结果表明,与传统限幅算法相比,改进算法能够明显降低系统的误码率,同时保证良好的抑制峰均比的性能.     

Multiple short pass glass capillary gas chromatography

A multiple repass system, utilizing an in-line switching valve and suitable for use with small-bore glass open tubular columns, is described. The advantages of the system, which include higher OPGV, large plate numbers and optimization of column “length”, are discussed.     

Electrochemical Oxidation of ds‐DNA on Polypyrrole Nanofiber Modified Pencil Graphite Electrode

Preparation of a polypyrrole nanofiber (PPyNF) modified pencil graphite (PG) electrode and its usage in the electrochemical DNA biosensors was investigated. The electrodes (PPyNF/PG1 and PPyNF/PG2) were prepared from a solution containing 0.1 M pyrrole, 0.1 M Na₂CO₃ and 0.1 M LiCIO₄ by using potentiostatic and potentiodynamic methods. PPyNF/PG2 electrodes which were prepared by potentiostatic procedure showed higher responses for the oxidation of ds‐DNA than the PPyNF/PG1 electrodes prepared by potentiodynamic methods. Immobilization of the ds‐DNA on PG and PPyNF/PG surfaces was performed at a constant potential, +0.5 V, for 300 s in 0.5 M ABS (pH 4.8) containing 15 μg mL^?1 ds‐DNA and 20 mM LiCIO₄. The oxidation peak potentials of the ds‐DNA bases, guanine and adenine, were shifted to more cathodic values by using PPyNF/PG electrodes. The oxidation signal of the guanine base of ds‐DNA was decreased in the presence of methylene blue.     

正交双路光纤电流互感器的信号处理方法

利用正交双路光纤传输光电流信号的处理方法,满足了光纤电流互感器在电力系统暂态保护应用中的实时处理要求.此方法可从正交双路光信号中直接提取两路电流信息,减小了光路传输不理想对电流测量值的影响.结合模数变换过采样技术和先进的数字信号处理技术,提高了系统对暂态故障的响应速度,改进了检测性能.实验表明,此方法在暂态信号的采集和实时处理方面,比现有方法的迟延小且精度高.     

Development of high-mobility tracked vehicles for over snow operations

This paper describes a detailed investigation into the effects of some of the major design features on the mobility of tracked vehicles over snow. The investigation was carried out using the latest version of an advanced computer simulation model, known as NTVPM, developed under the auspices of Vehicle Systems Development Corporation (VSDC), Ottawa, Ontario, Canada. Results show that the road wheel system configuration, initial track tension (i.e., the tension in the track system when the vehicle is stationary on a level, hard ground) and track width have significant effects on vehicle mobility over snow. On deep snow where the vehicle belly (hull) contacts the snow surface, the location of the centre of gravity (C.G.) of the sprung weight in the longitudinal direction has a noticeable effect on vehicle mobility, as it affects the attitude of the belly and the belly–snow interaction. Based on the investigation, a conceptual high-mobility tracked vehicle for over snow operations is discussed. Results of this study will provide the vehicle designer with guiding principles for the development of high-mobility tracked vehicles. It also demonstrates that NTVPM is a useful and effective tool for design and performance evaluation of tracked vehicles from a traction perspective.     

数字正交检测与过采样技术的结合

详细讨论了数字正交检测与过采样技术的结合问题.结果表明,通过同时改变采样频率和射频激发与参考的频率差,采集到的NMR数据经过一次数字滤波即可完成数字正交检测和过采样的数据处理过程.从而使得总的数据处理过程能够在大多数情况下在等待磁化矢量恢复的时间内完成.     

30GHz RF脉冲压缩器设计

为得到脉宽150ns，功率超过100MW的30GHz微波脉冲，采用MSLED-II原理设计了30GHz RF-脉冲压缩器。H-Hybrid，TE100口-TE10o模式转换器等器件都采用了新型设计，所有微波器件的设计充分考虑了高功率下的适用性，没有容易引起打火的调谐杆、容性膜片等部件。在微波器件的设计中用HFSS软件进行了详尽的模拟。加工并测试了H-Hybrid，且用在CERN的RF脉冲展宽器上。