变电站一次设备喷涂PRTV用量的分析

对国网宁夏电力检修公司宁安运维站近2年来一次设备喷涂PRTV用量的统计数据进行分析整理,得出各类一次设备按照标准要求喷涂PRTV时的用量估算值,并针对现存作业中存在的问题,提出相应解决方案。     

Complexity of families of learning algorithms and estimation of the nonrandomness of extraction of empirical regularities

The paper presents a general approach to the evaluation of the complexity of classes of algorithms, so-called pVCD-method. To develop this method, all the examined families of models of empiric generalization were restricted to classes implementable on computers and, wider, by examining their partially recursive representations. Within the framework of the algorithmic approach, the concept of Kolmogorov’ complexity of algorithms for the recognition of properties or the extraction of regularities is proposed. The method proposed to evaluate the nonrandomness of the extraction of empirical regularities is based on this concept.     

Analysis of microdensitometric data in terms of probability of cleavage of DNA

Computer-aided analysis of autoradiographic films of DNA fragments is presented. The Powell least-squares procedure is used for optimization of parameters for components of complex densitometric curves. Since each densitometric spectrum may be divided for several non-overlapped blocks of bands, there is no upper limit on the number of parameters which must be optimized. Eight shapes for the component bands are utilized: symmetric and asymmetric Gauss and Cauchy functions, direct, symmetric and asymmetric product of Gauss function and inverse of Cauchy function, and log-normal function. The probability of DNA cleavage is calculated with correction for multiple cuts. The methods presented was applied to detailed analysis of densitometric spectra of a 21-bp DNA restriction fragment and allowed for direct correlation between structural microheterogeneity of DNA and the resulting cutting pattern. This method should facilitate the analysis of densitometric data from antibiotic-induced cleavage of DNA and footprinting experiments.     

Modifications of the method of variation of parameters

In spite of being a classical method for solving differential equations, the method of variation of parameters continues having a great interest in theoretical and practical applications, as in astrodynamics. In this paper we analyse this method providing some modifications and generalised theoretical results. Finally, we present an application to the determination of the ephemeris of an artificial satellite, showing the benefits of the method of variation of parameters for this kind of problems.     

机车空调逆变电源设计

本文讨论的是机车空调逆变电源系统的设计与研究。该电源系统主要是由DC/DC的BOOST升压部分和DC/AC三相逆变部分两部分组成。DC/DC部分所得直流电压通过DC/AC部分逆变成三相交流电,供给空调机组工作。同时,为使电源系统能更可靠的运行,也设计了相应的故障检测、保护等辅助电路。     

风电机组电动变桨距控制系统的优化研究

由于风速的随机性、不稳定性及气动效应的影响,使得风力发电机组变桨距控制系统具有非线性、参数时变性、强耦合等特点,难于实现高精度控制,导致风电机组输出电能质量较差。为了改善系统在恒功率输出运行区域内的动态性能,分析了风电机组变桨距控制系统的现状,建立了整个风电机组模型,提出了优化的变桨距控制策略,并设计了基于模糊控制的变桨距控制器。仿真结果表明,独立变桨距控制技术的控制效果比统一变桨距好,实现了风力机各叶片的优化独立变桨距控制,优化了风力发电系统在超过额定风速时的恒功率控制,具有抗干扰能力强、控制精度高的特点。     

发热量测定仪系统设计

本文介绍了发热量测定仪的结构、工作原理、硬件系统功能,阐述了应用铂电阻进行高精度温度测量的方法,系统用AT89C52单片机作为处理和控制芯片,该发热量测定仪性能符合水泥企业应用要求。     

计算机辅助课表编排技术的研究

讨论了几种实用的计算机辅助课表编排技术及在实际编排中的应用。应用分析表明，采用分批与或图搜索和分批优化的匈牙利算法相结合的方法，在计算机辅助课表编排中是行之有效的。     

联合收割机脱粒滚筒恒速智能控制器设计

研究了轴流式联合收割机的控制问题,给出了联合收割机脱粒滚筒的数学模型,介绍了基于模式识别的智能控制原理,建立了联合收割机脱粒滚筒恒速控制模型,设计了基于模式识别的智能恒速控制器.应用Matlab/Simulink进行了控制器仿真,其结果表明,将基于模式识别的智能控制应用于联合收割机脱粒滚筒的恒速控制,其过渡过程平稳、响应速度快、无超调、无振荡并且无稳态误差.     

Stability properties of equilibria of classes of cooperativesystems

This note deals with the constant control problem for homogeneous cooperative and irreducible systems. These systems serve as models for positive systems. A necessary and sufficient condition for global asymptotic stability of the zero solution of this class of systems is known. Adding a constant control allows to shift the equilibrium point from zero to a point in the first orthant. We prove that for every nontrivial nonnegative control vector a unique nontrivial equilibrium point is achieved which is globally asymptotically stable if the zero solution of the uncontrolled system is globally asymptotically stable. In addition a converse result is provided. Finally a stability result for a particular class of Kolmogorov systems is established. We compare our main results to those in the literature     

An estimate of numbers of terms of semicycles of delay difference equations

In this paper, we study the semicycles of oscillatory solutions of the delay difference equation y_n+1 − y_n + p_ny_n-k = 0, where p_n is a sequence of nonnegative real numbers and k is a positive integer. Upper bound of numbers of terms of semicycles are determined in the case when

Our results improve and complement known results in literature.     

Features of estimation of the main key performance indicators of work of production of technological type. I. Complex of key indicators and feature of estimation of qualitative indexes of production flows

The structure of a complex of key performance indicators of work of production of technological type is considered. Features of determination of the qualitative indexes of work of production entering a complex and an error of their estimates are analyzed.     

石油钻井泵阀体高频淬火温度的自动控制

针对石油钻井泵阀体高频淬火工艺要求，选用红外测温传感器测量石油钻井泵阀体的淬火温度，采用8031单片机自动控制温度，并可随时打印温度值，工件计数值，该系统控制精度高，抗干扰能力强，运行效果良好。     

支持向量机多类目标分类器的结构简化研究

由于支持向量机(SVM)在模式识别和回归分析中有着独特优势，因此成为近来研究的热点，其优势主要体现在处理非线性和高维数据问题方面。最初的SVM特别适合解决两类目标分类问题，而对于多类目标分类，则需将其转化为多个两类目标分类问题，相应地即可构造多个两类目标子分类器，但由于这种情况导致了分类器结构的过于复杂，从而导致判决速度的降低。为了快速地进行分类．提出了一种简化结构的多类目标分类器，其不仅使得子分类器数目大大减少，而且使分类速度明显提高；同时对其分类精度和复杂度进行了对比分析。实验结果证明。该分类器是有效的。     

Complexity of approximation of 3-edge-coloring of graphs

The problem to find a 4-edge-coloring of a 3-regular graph is solvable in polynomial time but an analogous problem for 3-edge-coloring is NP-hard. To make the gap more precise, we study complexity of approximation algorithms for invariants measuring how far is a 3-regular graph from having a 3-edge-coloring. We show that it is an NP-hard problem to approximate such invariants with an error O(n1−ε), where n denotes the order of the graph and 0<ε<1 is a constant.     

机械臂绝对定位精度测量

提出了用激光跟踪仪标定机械臂的D-H参数、测量机械臂绝对位姿以及对机械臂的绝对定位精度进行分析的方法;用激光跟踪仪测量机械臂各个关节单独运动时得到的一系列离散点,就可确定机械臂各个关节的轴线,由此建立机械臂的D-H坐标系,并对D-H参数进行标定;然后,给出了由6D激光头位姿确定机械臂末端位姿的方法;最后,推出了由测量位姿值与命令位姿值相比较,得到机械臂绝对定位的位置和姿态偏差的方法;这些方法可以有效、迅速地完成对机械臂绝对定位精度的测量.     

Correctness of Algebraic Extensions of Models of Classification Algorithms

The binary representation of each classification from a subset of a space of admissible classifications is considered. A metric in a unit cube is introduced, and a correct algebra of classification algorithms is constructed. The correctness and completeness of a model of classification algorithms are proved. An example of construction of a complete model for a classification problem is considered.     

微悬臂梁横向弹性系数标定技术

微悬臂梁是新型力学传感器的关键部件,其性能决定力学测试结果的准确度。为了定量研究微悬臂梁与样品表面间的相互作用力,须对微悬臂梁的力学性能进行表征。提出了一种新的微悬臂梁横向弹性系数标定方案:采用精密天平和光杠杆分别测得微悬臂梁的横向扭转力和扭转量,进而可得到微悬臂梁的横向弹性系数。对3种型号的微悬臂梁进行了横向弹性系数的实际标定,结果表明:均方差均小于5%,重复性良好,且与有限元仿真值一致。     

Compensation of Distortions of Polarization Characteristics of Ring Resonators

The reasons of occurrence of polarization mode distortions and methods of their compensation are investigated. It is demonstrated that sensitivity of lasers with ring resonator to magnetic field may be reduced, if effect of induced polarization anisotropy to be compensated by means of installation of a mirror in resonator in certain position, which complies with the minimum ellipticity angle.     

VB在光学原理教学中的应用

在介绍VB语言的特点并分析目前光学原理课程教学现代化过程中所存在问题的基础上，通过教学仿真实例阐述了VB应用于光学原理教学中的可操作性和必要性。将Ⅷ和光学原理教学有机地结合起来，能帮助学生建立直观的物理图像，更好地理解物理概念．能激发学生的研究兴趣，有助于学生科学素质的提高。