Travelling-wave analysis of generalized multiconductor systems

The behaviour of multiconductor systems is analysed from a fundamental travelling-wave point of view. Generalized wave parameters are derived for a two-port multiconductor system from which image and iterative parameters follow as special cases. The relationship of these to short-circuit parameters is also given.     

Electromagnetic transients in nonuniform untransposed three-phase transmission lines

In this paper a mathematical analysis is given, based on the modal technique, for transient calculations in nonuniform transmission lines. The untransposition and earth effects are included. A general formula for the voltage transform is deduced. Sequential pole switching is considered. The proposed method is applied to a typical 500 kV transmission line. The results obtained in this study are compared with similar results calculated by other investigators.     

A modal interpretation of wave propagation in non-homogeneous multiconductor systems

A generalized interpretation of the phenomenon of wave propagation in non-homogeneous multiconductor systems is given by introducing the concent of component waves. It is shown that the familiar analysis of homogeneous systems is only a particular case of the generalized approach developed in this paper.     

铁路10KV自闭/贯通线路单相接地故障定位方案研究

铁路配电网采用自动闭塞和电力贯通线路(简称自闭/贯通线)为铁路系统调度集中、大站电气集中连锁、自动闭塞、驼峰信号等Ⅰ级负荷供电.由于线路自身特点,自闭/贯通线路故障率高,且查找困难.针对故障点的定位问题,采用"S注入法"进行了单相接地故障仿真.建立了基于母线佣电压互感器二次侧注入信号电流,在故障点前后检测特定频率信号电流及零序特点来实现故障定位的模型,通过实验仿真,验证了定位方案的可行性.     

Non-negativity test of multidimensional Hermitian matrices

Arguments are advanced to point out that simplification analogous to that in the computational test for positive definiteness of multidimensional Hermitian matrices is not possible when the Hermitian matrix is to be tested for non-negative definiteness.     

Binary matrices with specified properties

The binary matrices A which are circulant with one or more of the following properties: (1) A is symmetric, i.e. A = A^T, (2) A is orthogonal, i.e. AA^T = I (mod 2), (3) A has low multiplicative order, i.e. A^m = I, occur often in communication, control and network theory problems. In this paper we construct a number of such matrices. The results are based on the theory of power-residues modulo an odd prime p, and the fact that the algebra of all p × p circulant matrices is isomorphic to the algebra of polynomials modulo (x^p?1).     

Ultrasonic delay lines

This paper deals with the experimental aspects of ultrasonic delay lines in liquid media and is a sequel to a previous paper treating the general theory of such devices.Delay devices employing ultrasonic propagation through liquids have proved satisfactory for delay times of the order of 3 milliseconds or less. Such devices can be made broadband and give excellent reproduction of pulse shape. The design considerations for such devices are discussed and illustrated by actual examples.     

Negative dielectrophoretic capture of bacterial spores in food matrices

A microfluidic device with planar square electrodes is developed for capturing particles from high conductivity media using negative dielectrophoresis (n-DEP). Specifically, Bacillus subtilis and Clostridium sporogenes spores, and polystyrene particles are tested in NaCl solution (0.05 and 0.225 S∕m), apple juice (0.225 S∕m), and milk (0.525 S∕m). Depending on the conductivity of the medium, the Joule heating produces electrothermal flow (ETF), which continuously circulates and transports the particles to the DEP capture sites. Combination of the ETF and n-DEP results in different particle capture efficiencies as a function of the conductivity. Utilizing 20 μm height DEP chambers, “almost complete” and rapid particle capture from lower conductivity (0.05 S∕m) medium is observed. Using DEP chambers above 150 μm in height, the onset of a global fluid motion for high conductivity media is observed. This motion enhances particle capture on the electrodes at the center of the DEP chamber. The n-DEP electrodes are designed to have well defined electric field minima, enabling sample concentration at 1000 distinct locations within the chip. The electrode design also facilitates integration of immunoassay and other surface sensors onto the particle capture sites for rapid detection of target micro-organisms in the future.     

Asynchronous synchronization of complex networks with switched adjacent matrices

This note analyzes the synchronization problem for a class of complex networks. The considered network topology, symbolized by adjacent matrices, is assumed to be time-varying and subjected to a Markov process. When designing controllers to synchronize the network, we consider the asynchronous phenomenon occurred between the mode of the adjacent matrices and that of the controllers. A properly defined stochastic process, which is related to the Markov process by a conditional probability is then introduced to indicate the controller mode. Base on this connection, a sufficient condition is derived by using Lyapunov–Krasoviskii theorem to ensure the global synchronization of the considered complex network with a predefined noise attenuation level. The design scheme is presented by solving a series of LMIs. A numerical example is finally provided to verify the effectiveness of the proposed method.     

Topological evaluation of feedback matrices in multiple-loop feedback amplifiers

Topological formulas for the evaluation of the elements of the return difference and the null return difference matrices of a multiple-loop feedback amplifier are presented. They are expressed in terms of the directed-tree and directed-two-tree admittance products in the associated digraph. In the situation where the controlling parameters of all the controlled sources are chosen as the elements of interest, the associated digraph is simply the graph representing the feedback amplifier after the independent source and controlled sources have been removed. The significance of the present approach is that it not only provides a short-cut for the evaluation of the feedback matrices, but also gives an insight into the behavior of the feedback amplifier under consideration.