Low-Microwave Loss Coplanar Waveguides Fabricated on High-Resistivity Silicon Substrate

Three kinds of coplanar waveguides （CPWs） are designed and fabricated on different silicon substrates---common low-resistivity silicon substrate （LRS）, LRS with a 3μm-thick silicon oxide interlayer, and high-resistivity silicon （HRS） substrate. The results show that the microwave loss of a CPW on LRS is too high to be used, but it can be greatly reduced by adding a thick interlayer of silicon oxide between the CPW transmission lines and the LRS.A CPW directly on HRS shows a loss lower than 2dB/cm in the range of 0-26GHz and the process is simple,so HRS is a more suitable CPW substrate.

Aging in EPDM used for outdoor insulation

The effect of accelerated weather aging an ethylene-propylene-diene monomer(EPDM) rubber used for outdoor insulation was studied by surface roughness measurement and X-ray photoelectron spectroscopy(xps). The surface roughness of EPDM rubber changed with aging time. The surface oxygen and aluminum content were found to increase and that of carbon, silicon and nitrogen to decrease with time. The detailed XPS analysis indicated that the concentration of carbon in C-C decreased and that of highly oxidized carbons in C-O, C=O and O=C-O increased with time, which was due to the oxidation of EPDM rubber polymer. The appearance of O=C-O on the surface of EPDM rubber was a signal that EPDM rubber became aged. The aging speed decreased with time. The aging mechanism is discussed also.

输电线巡检机器人越障机理与试验

分析超高压输电线路架空地线上的障碍物类型以及跨越这些障碍的过程。可以发现,巡检机器人采用双臂交替跨越障碍,越障过程简单。但是由于受巡检机器人自身重力偏矩的影响和手臂长度尺寸的限制,当单臂悬架在架空地线上时,导致巡检机器人本体倾斜,另一手臂完成脱线和上线任务变得十分困难,有时甚至造成越障失败。为了解决上述问题,提出质量调节的控制方法。该方法通过调节巡检机器人的质心,使巡检机器人的本体保持水平状态。为了验证质量调节控制方法的正确性,采用Lagrange方法建立巡检机器人动力学模型,通过仿真试验、实验室模拟实际架空地线试验以及超高压实际现场试验说明了提出方法的可行性。

超高压输电线路巡检机器人两种越障定位方法比较

将两种基于传感器信息的导线定位方法的特点和差异进行了分析和对比,得出方法Ⅱ的解算能力强于方法Ⅰ的解算能力,但由于方法Ⅱ的定位精度低于方法Ⅰ的定位精度,因此,选用方法Ⅰ进行野外作业。

输电线路巡检机器人越障控制研究

介绍了超高压输电线路巡检机器人越障控制方法。根据巡检作业任务的要求,采用遥控与局部自主控制相结合的方法,实现了巡检机器人沿线行走及跨越障碍的功能。采用基于单目摄像头定位和视觉伺服的方法,实现了巡检机器人的自主越障控制。实验结果表明,该机器人可沿线行走并自主跨越障碍,从而验证了控制系统设计的有效性与合理性。

超高压输电线路巡检机器人越障控制问题的研究

给出了一种超高压输电线路巡检机器人控制系统的设计与实现方法.根据机器人的作业任务,提出了基于传感器信息、约束信息以及动作反馈信息作为输入,产生式系统作为动作输出的越障控制方式.仿真结果表明此方法对于机器人的越障过程是有效的.

输电线路巡检机器人的机构、建模与实验研究

输电线路巡检机器人是一种特种作业机器人，具有广阔的输电线路巡检的应用背景，该项研究是机器人学研究领域的前沿课题之一，而越障机构又是巡检机器人的关键技术之一。本文在863课题《超高压输电线路巡检机器人》的资助下，系统地研究了输电线路巡检机器人的移动越障机构及其理论建模，目的是分析综合越障巡检机构，研制新型的越障巡检机构；通过结构优化减小能耗提高机器人巡检线路的实用性。 本文首先系统研究了巡检作业的典型工况，建立巡检目标障碍空间的数学模型，为巡检机器人的越障巡检机构研究与越障规划奠定基础。 第二、建立特殊工况下的设计原则，研究越障巡检机构的分析与综合方法。1、提出一种基于障碍空间分析的越障巡检机构综合方法，在分析多种越障机构的越障原理与越障性能的基础上，基于螺旋理论进行越障巡检机构的型综合与数综合，优化越障巡检机构的自由度与构型，并且设计两种新型越障巡检机构。2、用影响系数法，建立机器人运动学模型，探讨越障巡检机构的运动综合。3、提出线上操作的打滑稳定裕度与摆动稳定裕度，且给出相应的判据。在建立静力学与动力学模型、探讨越障巡检机构的动力性能、分析操作手夹持姿态的稳定性的基础上，拓展夹持稳定性量度，提出打滑裕度与摆动裕度。 第三、建立特殊风载荷工况下，结构参数受风向和风压影响的数学模型，得到不同风荷载的风压对尺寸参数的影响；由风载荷影响操作手夹持稳定性，从而影响行走轮包角参数，分析得到相应的行走轮外缘包络包角范围。根据风荷载阻力与尺寸参数的关系，基于最小能量理论采用积分有限元分析，对机器人的重要零件与部件进行了结构参数优化。 第四、根据环境模型制定越障流程；分析越障过程的三个难点：机构平衡、导线辨识与定位可知，导线定位是越障的关键；并就如何定位导线的越障关键问题，提出一种解析定位方法，对比搜索定位方法可知，解析定位方法优于搜索定位方法。 第五、通过实验验证越障原理、越障规划、定位方法、及系统性能等。在调试和考机合格的基础上，分别在实验环境下验证了线上行走巡检原理的有效性和连续越障的可行性；在野外现场实验验证了越障巡检机器人系统的原理可靠性与越障定位的有效性。

Characterisation of Passive Intermodulation in Passive RF Devices with X-parameter

A novel approach to the modelling of passive intermodulation (PIM) generation in passive components with distributed weak nonlinearities is outlined. Based upon the formalism of X-parameters, it provides a unified framework for co-design of antenna beamforming networks, filters, combiners, phase shifters and other passive and active devices containing nonlinearities at RF front-end. The effects of discontinuities and complex circuit layouts can be efficiently evaluated with the aid of the equivalent networks of the canonical nonlinear elements. The main concepts are illustrated by examples of numerical simulations of PIM generation in the transmission lines and comparison with the measurement results.

On Passive Intermodulation Test of Analog and Digital Systems

This paper presents initial results of evaluating suitability of the conventional two-tone CW passive intermodulation (PIM) test for characterization of modulated signal distortion by passive nonlinearities in base station antennas and RF front-end. A comprehensive analysis of analog and digitally modulated waveforms in the transmission lines with weak distributed nonlinearity has been performed using the harmonic balance analysis and X-parameters in Advanced Design System (ADS) simulator. The nonlinear distortion metrics used in the conventional two-tone CW PIM test have been compared with the respective spectral metrics applied to the modulated waveforms, such as adjacent channel power ratio (ACPR) and error vector magnitude (EVM). It is shown that the results of two-tone CW PIM tests are consistent with the metrics used for assessment of signal integrity of both analog and digitally modulated waveforms.

Using Modern Tools to Explain the Use of the Smith Chart

The concept of explaining the use of an old tool like the Smith chart, using modern tools like MATLAB [1] scripts in combination with e-learning facilities, is exemplified by two MATLAB scripts. These display, step by step, the graphical procedure that must be used to solve the double-stub impedance-matching problem. These two scripts correspond to two different possible ways to analyze this matching problem, and they are important for students to learn by themselves.

Proposta de um algoritmo eficiente para a localização de faltas por relé diferencial numérico para proteção de linhas de transmissão com compensação série controlada por tiristores (TCSC)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fractional order electromagnetics

The Maxwell equations constitute a formalism for the development of models describing electromagnetic phenomena. The four Maxwell laws have been adopted successfully in many applications and involve only the integer order differential calculus. Recently, a closer look for the cases of transmission lines, electrical motors and transformers, that reveal the so-called skin effect, motivated a new perspective towards the replacement of classical models by fractional-order mathematical descriptions. Bearing these facts in mind this paper addresses the concept of static fractional electric potential. The fractional potential was suggested some years ago. However, the idea was not fully explored and practical methods of implementation were not proposed. In this line of thought, this paper develops a new approximation algorithm for establishing the fractional order electrical potential and analyzes its characteristics.

Développement et utilisation de sources de plasma pour stériliser des instruments médicaux

Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

Development of a varactor -controlled dual-frequency reconfigurable microstrip antenna

A new design for a compact electronically reconffgurable singlefeed dual frequency dual-polarized operation of a square-microstrip antenna capable of achieving tunable frequency ratios in the range 1.1 to 1.37 is proposed and experimentally studied. Varactor diodes inlegruted with the arms of the hexagonal slot and embedded in the square patch are used to tune the operating frequencies by applying reverse-bias voltage. The design has the advantage of size reduction up to 73.21% and 49.86% for the two resonant frequencies, respectively, as compared to standard rectangular patches. The antenna offers good bandwidth of 5.74% and 5.36% for the two operating frequencies. A highly simplified tuning circuitry without any transmission lines adds to the compactness of the design

Development and Analysis of a Compact Dual-Band Coplanar Antenna

The coplanar wave guide is an attractive device in microwave integrated circuits due to its uniplanar nature, ease of fabrication and low production cost. Several attempts are already done to explore the radiating modes in coplanar wave guide transmission lines. Usually coplanar wave guides are excited by an SMA connector with its centre conductor connected to the exact middle of the centre strip and the outer ground conductor to the two ground strips. The mode excited on it is purely a bound mode. The E-field distribution in the two slots are out of phase and there for cancels at the far field. This thesis addresses an attempt to excite an in phase E-field distribution in the two slots of the co planar wave guide by employing a feed asymmetry, in order to get radiation from the two large slot discontinuities of the coplanar waveguide. The omni directional distribution of the radiating energy can be achieved by widening the centre strip.The first part of the thesis deals with the investigations on the resonance phenomena of conventional coplanar waveguides at higher frequency bands. Then an offset fed open circuited coplanar waveguide supporting resonance/radiation phenomena is analyzed. Finally, a novel compact co planar antenna geometry with dual band characteristics, suitable for mobile terminal applications is designed and characterized using the inferences from the above study.