40 GHz毫米波室内传播损耗分析

介绍了室内毫米波的传播特性,通过改变发射天线的位置实际测量了37.598GHz和40GHz毫米波在实验室内和走廊的接收功率,并对数据进行处理,得出毫米波室内视距条件下的基于衰减因子损耗模型的传播路径损耗因子n。分析两种频率的毫米波测量结果,对于室内基站位置的选择和无线终端的设计以及40GHzmm-ROF系统的室内覆盖提供依据。     

Numerical modelling of microwave detectors at high signal level

The relationship between microwave power absorbed by a detector diode and the resulting detected voltage at high signal level is investigated. Experimental data is obtained from a zero-biased diode mounted in a rectangular waveguide system operating at 9.5 GHz. The Alpa Industries Inc. 4561, 6724 and 6725 Schottky diodes and the M/A-COM 1N23 Point Contact diode with 1 kω and 106 kω loads are examined. The P–V relationships are analysed by solving a system of non-linear differential equations based on a lumped parameter model of the microwave system and diode.     

Method of moments modelling of cylindrical microwave integrated circuits interconnections

In this paper, a numerical technique suitable for characterizing a wide variety of interconnection configurations printed on cylindrical surfaces, is presented. The interconnection lines may have either finite or infinitesimal cross‐sections. To model cylindrical interfaces, suitable space‐domain integral equations are formulated to represent the potential on conductors and electric field at dielectric interfaces. The solution of the integral equations is then obtained numerically by applying the method of moments (MOM). The objective of this approach is to determine the capacitance matrix of cylindrical interconnection systems with different configurations. From the capacitance matrix, other quantities such as characteristic impedance, coupling coefficient and effective permittivity can be determined. The numerical technique described in this paper is implemented as a general computer program. Various circular cylindrical as well as elliptical cylindrical structures have been solved including microstrip lines and coplanar waveguide lines. The results obtained compare very well with other published data. Copyright © 2004 John Wiley & Sons, Ltd.     

Time domain global modelling of EM propagation in semiconductor using irregular grids

A two‐dimensional finite volume time domain (FVTD) method using a triangular grid is applied to the analysis of electromagnetic wave propagation in a semiconductor. Maxwell's equations form the basis of all electromagnetic phenomena in semiconductors and the drift‐diffusion model is employed to simulate charge transport phenomena in the semiconductor. The FVTD technique is employed to solve Maxwell's equations on an irregular grid and the finite box method is implemented on the same grid to solve the drift‐diffusion model for carrier concentration. The locations of unknowns have been chosen to allow linking coupled Maxwell's equations and transport equations in a seamless way. To achieve suitable accuracy and computational efficiency, using irregular grid topology allows a finer mesh in doped region and at junction, and a coarser mesh in substrate and insulting regions. The proposed scheme has been implemented and verified by characterizing electromagnetic wave propagation at microwave frequency in a semiconductor slab with arbitrary doping profile. Copyright © 2002 John Wiley & Sons, Ltd.     

Optimization of power‐efficient wireless mesh networks in outdoor and indoor environments in Japan

This paper proposes the optimization of power‐efficient wireless mesh networks in outdoor and indoor environments, particularly for gas metering in Japan. We investigate the effect on total power consumption by changing the output power and allocated frequency band of a gas metering system. From the simulation results, we show that these changes are effective in achieving low power consumption. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

GO/PI复合薄膜的制备及性能研究

利用改进Hummers法制备氧化石墨烯(GO),再通过溶液共混法制备氧化石墨烯/聚酰亚胺(GO/PI)复合薄膜,采用XRD、TMA、TGA等对其结构和性能进行表征.结果表明:相对于不添加GO的PI薄膜而言,当复合薄膜中的GO质量分数为0.2％时,复合薄膜的力学性能得到很大提升,其中拉伸强度提高了26.77％,断裂伸长率提高了76.47％,弹性模量基本不变.当GO质量分数为0.1％时,复合薄膜的T5、T10最大值分别为587.3℃、603.3℃,相对于未添加GO的PI薄膜分别提高了2.44％、1.69％.说明适量GO的加入可以显著增强复合薄膜的力学性能和热学性能.     

On the self-scheduling of a power producer in uncertain trading environments

This work presents a scenario-based approach to the self-scheduling problem of a price taker power producer in a DA market. It concentrates on three categories of uncertainty including price, forced outage and generation reallocation and analyses their effects on the producer revenue. To tackle the uncertainties a set of price scenarios are so generated that their means and covariance matrix are the same as the base-case scenario. Forced outage and generation reallocation of generator for each price scenario are appropriately modeled through a probabilistic methodology. In this work Downside Risk (DR) is employed as the risk measure which quantifies the downside violations from a specified target. A risk-constrained self-scheduling problem is therefore formulated and solved as a mixed integer linear programming problem. Numerical results for a case study are discussed.     

On stochastic modelling of linear circuits

In this paper, the deterministic modelling of linear circuits is replaced by stochastic modelling by including variance in the parameters (resistance, inductance and capacitance). Our method is based on results from the theory of stochastic differential equations. This method is general in the following sense. Any electrical circuit that consists of resistances, inductances and capacitances can be modelled by ordinary differential equations, in which the parameters of the differential operators are the functions of circuit elements. The deterministic ordinary differential equation can be converted into a stochastic differential equation by adding noise to the input potential source and to the circuit elements. The noise added in the potential source is assumed to be a white noise and that added in the parameters is assumed to be a correlated process because these parameters change very slowly with time and hence must be modelled as a correlated process. In this paper, we model a series RLC circuit by using the proposed method. The stochastic differential equation that describes the concentration of charge in the capacitor of a series RLC circuit is solved. Numerical simulations in MATLAB are obtained using the Euler–Maruyama method. Copyright © 2008 John Wiley & Sons, Ltd.     

Harmonic balance method applied to the numerical electrical physical modelling of two-terminal,non-linear microwave circuits in the frequency domain

A numerical frequence-domain modelling of two-terminal, non-linear microwave circuits is presented. It basically relies on a process allowing the solution of the frequency-domain curcuit harmonic balance equations while accounting for the semiconductor device by means of an accurate numerical macroscopic physical model. In its present state of development, the model allows the study of a single two-terminal device circuit operating in harmonic mode. Its capabilites are illustrated by means of the results of a study devoted to the optimization of the load curcuit configuration of a millimetre-wave avalanche diode frequency multiplier. The influence of the output load impedance level on the circuit output RF performance has been investigated for different input power levels in direct frequency multiplication mode and in the presence of additional circuit tunings at low harmonic rank idler frequencies.     

Framework for the simulation of wireless power transmission over ultra wide band links in multipath propagation environments in the vicinity of the human body

In this contribution, a modular framework for ultra wide band wireless power transmission in proximity of the human body is presented. The goal of this work is to simplify the study of wireless links by considering antenna models, including radiation characteristics when the antenna is deployed on the human body, and the power transferred over them in multipath, shadowed propagation environments, such as powering textile antenna systems completely integrated inside garments. To obtain this goal, antenna links are partitioned in black box models for all elementary building blocks, such as antenna transfer functions, propagation channels, active components and more, that can be recombined as one sees fit. The recombination allows for accurate simulation of intricate systems. For small examples, considerable speed and memory gains were observed (a factor 6.20 in time and 1.75 in memory), while for more elaborate examples, it is even impossible to simulate a reference solution. Copyright © 2015 John Wiley & Sons, Ltd.     

GO法在特高压直流输电可靠性研究中的应用

为探索特高压直流输电可靠性评估的新方法,首次将GO法引入到特高压直流输电的可靠性建模当中。结合特高压直流输电系统的实际工况,探讨了串联结构存在相关性时的等效模型算法,基于该算法开发了相应的GO程序,通过计算得到考虑元件相关性的情况下,系统中所有信号流的精确的可靠性参数。计算分析过程说明,可修复系统稳态可靠性的定量计算要比不可修复系统复杂得多。通过与不考虑元件相关性的情况下所得结果之间的对比,说明了发展可修复系统中GO法理论与算法的必要性与先进性。     

On influence of load modelling for undervoltage load sheddingstudies

This paper explores the influence of load models on decisions of undervoltage load shedding in power systems. A controlled load rejection can be used as an emergency countermeasure to avoid widespread blackout when system voltages are unstable. In this paper, dynamic simulations of a small power system using both static and dynamic load models are presented. When using a static load model, the system includes an explicit model of a transformer with load tap changer. The aim is to demonstrate how different load models influence the analysis and calculation of the amount of load needed to be shed to stabilise the system voltage     

基于连续体模型的电力系统机电扰动传播研究

连续体建模是一种研究大规模电力系统机电动态的新方法,面向复杂的大型电力系统,关注机电扰动在整个电力系统中的传播过程。基于描述机电波传播的非线性偏微分方程,在空间上进行差分处理,通过微分方程组体现了电力网络的拓扑连接关系,合理地处理了线路分支问题。同时,采用一种新的方法,将发电机转子的惯性按照Gauss函数连续地分布于与其相连接的线路上,体现了发电机在电力系统中的地理位置。最后,通过用连续体模型和传统模型的PSS/E动态仿真对改进的New England 10机39节点系统进行了扰动传播实验,研究了机电扰动在电力系统中的传播特性。2种方法在扰动传播时间上获得基本一致的结果。     

企业标准体系适宜性研究

本文通过对浙江省电力企业标准化工作现状的分析和研究,提出了对企业标准体系和其他管理体系进行有效整合的方法,为企业标准化人员更好地做好标准化工作提供参考.     

GO法在继电保护可靠性评估中的初步应用

基于状态概率公式推导的方法可以对系统进行精确的定量分析,但当系统中包含有共有信号时分析将变得十分复杂。针对该问题,探讨了一种新的定量计算方法,将一种新的可靠性分析方法——GO法引入到电力系统领域中,探讨了该方法在继电保护系统可靠性分析中的应用。结合所开发的GO程序,可十分方便快捷地对系统进行精确的定量与定性分析。基于故障树法对同一系统的分析结果验证了GO法在继电保护可靠性分析中的可用性与正确性。最后,通过对2种方法特点的比较,阐明了GO法的特点和优势。     

Computerized method for evaluating the suitability of trailingcables

A program to develop models for the enable computer calculation of conductor temperature rise versus time in trailing cables has been initiated. To date, a common model equation has been developed and parameters determined for two round trailing cables typically used on continuous miners, type G-GC, sizes 2/0 AWG and 4/0 AWG, rated 90°C. The resulting cable models have been tentatively confirmed in laboratory trials using repetitive four-level constant-current cycles and triangular currents in which the peak current varied on succeeding cycles. Model refinement and additional laboratory trials are projected using randomly varying current, simulating actual current conditions in mine trailing cables     

基于GO法的电气主接线可靠性评估

本文基于GO法的基本原理,建立了一种新的电气主接线可靠性评估模型—GO模型。根据GO法操作符及计算模型,建立了电气主接线可靠性计算的系统等效图和GO图。采用该模型对变电站电气主接线可靠性进行了分析和计算,取得了良好的计算结果。计算结果表明,该方法具有建模方便,指标完整,计算快捷的特点。