Parameter identification of inertially stabilized platforms using current command design

Accurate parameter identification is essential when designing controllers for inertially stabilized platforms (ISPs). But traditional identification methods suffer from observation measurement noise and operating restrictions of ISPs. To address this issue, a novel identification method based on current command design and multilevel coordinate search (MCS) algorithm without any higher order measurement differentiations was proposed. The designed current commands were adopted to obtain parameter decoupled models with the platform operating under allowable conditions. MCS algorithm was employed to estimate the parameters based on parameter decoupled models. A comparison experiment between the proposed method and non-linear least square method was carried out and most of the relative errors of identified parameters obtained by the proposed method were below 10%. Simulation and experiment based on identified parameters were conducted. A velocity control structure was also developed with disturbance observer (DOB) for application in disturbance compensation control system of an ISP. Experimental results show that the control scheme based on the identified parameters with DOB has the best disturbance rejection performance. It reduces the peak to peak value (PPV) of velocity error integral to 0.8 mrad which is much smaller than the value (10 mrad) obtained by the single velocity controller without DOB. Compared with the control scheme based on sweep model with DOB compensation, the proposed control scheme improves the PPV of velocity error integral by 1.625 times.     

Smooth cutting pattern generation technique for membrane structures using geodesic line on subplane and spline interpolation

Practical techniques for smooth geodesic patterning of membrane structures were investigated, For the geodesic search, adjustment of the subplane of the extracted elements series was proposed, and various spline approximation methods were used to flatten the strip for the generation of a smooth pattern. This search approach is very simple, and the geodesic line could be easily attained by the proposed method without the need for a difficult computation method. Smooth cutting patterning can also be generated by spline approximation without the noise in discrete nodal information. Additionally, the geodesic cutting pattern saved about 21% of the required area for the catenary model due to the reduction of the curvature of the planar pattern seam line.     

浅析小电流接地系统暂态选线新方法

文章介绍了国内小电流接地系统故障选线方法的的发展简况,在分析小电流接地故障暂态特征的基础上对近几年提出的几种较新的基于暂态特征信息的选线方法进行了简单的评述,同时筒略说明了不足之处.文章最后提出了一种基于暂态能量函数的小电流接地选线方法,并有待于进一步研究.     

试论高职院校如何加强人文教育

随着我国高职院校的不断发展壮大,自身也暴露出了一些弊端,其一便是高职学生人文素养培养的缺失。人文素养既可以提高大学生的竞争力,也可适应当代社会对于人才的需求。但是大部分高职院校人文教育的现状堪忧,因此,本文针对这一问题提出了一些建议。     

民用电网谐波电流检测方法及仿真研究

针对民用电网中存在的电压不稳、三相不平衡和中线电流大等问题,在传统的ip-iq法基础上,采用对称分量法和零序电流分离法研究电流中的零序分量问题,并结合PI调节器建立数学模型对其谐波、基波负序和零序电流进行了实时检测。结果表明,该方法可准确地检测出电网电流中含有的谐波、基波负序和零序电流,且检测精度高、实时性好。     

河南省对外汉语专业本科生就业问题及对策探析

分析了影响对外汉语专业毕业生就业的各种因素,主张以积极的心态看待就业形势,正视存在的问题,加强专业建设,优化课程设置,落实实践环节,提升专业素质和求职技能,以提高对外汉语专业学生就业率和就业质量。     

浙江高等教育国际交流合作现状及发展研究

国际交流与合作是引进国外优质教育资源、促进高校自身发展的重要手段。近年来,浙江省高等教育在国际交流与合作方面呈现出一些的新趋势,如合作的制度化、区域多元化等。因此,对其现状及发展趋势进行研究,有助于更好地了解其发展脉络,为其进一步发展提供相关建设性建议。     

基于LJC-B型高压输电线路的污秽绝缘子泄漏电流遥测系统研究

污秽绝缘子的闪落是造成电力运行故障的一个原因．研制了一种遥测系统装置,对污秽绝缘子的泄漏电流进行实时监测,根据泄漏电流的大小,发出同级别的报警,提示电力人员做出反应．经过实例试验,表明该方法是有效的．     

并联型有源电力滤波器输出滤波器的阻尼控制

为了减少电感的使用量,针对三阶电感-电容-电感(LCL)系统容易出现谐振的问题,提出了基于电容电流反馈的有源阻尼控制策略.首先建立了有源滤波器输出LCL滤波的数学模型,推导了LCL系统在高次谐波下的传递函数,由根轨迹图分析出电容电流反馈系数的取值范围,结合系统的幅值裕度,从中优化得到合适的闭环参数,最后在MATLAB中建立了电力系统模型.仿真结果表明:采用电容电流反馈的有源阻尼控制策略得到电流的总谐波失真含量是3.72%,优于采用阻尼电阻控制策略的4.21%.该策略可以很好地对系统的谐波进行补偿,开关频率处纹波衰减率较为理想,系统的稳态和动态性能均满足求.     

The random walking method for the steady linear convectiondiffusion equation with axisymmetric disc boundary

In this article,the random walking method is used to solve the steady linear convection-diffusion equation(CDE)with disc boundary condition.The integral solution corresponding to the random walking method is deduced and the relationship between the diffusion coefficient of CDE and the intensity of the random diffusion motion is obtained.The random number generator for arbitrary axisymmetric disc boundary is deduced through the polynomial fitting and inverse transform sampling method.The proposed method is tested through two numerical cases.The results show that the random walking method can solve the steady linear CDE effectively.The influence of the parameters on the results is also studied.It is found that the error of the solution can be decreased by increasing the particle releasing rate and the total walking time.