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Search Results: 1 - 10 of 273588 matches for " 李涛 "
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双馈风机不同模型下系统阻尼特性对比分析
The Comparison Study of System Damping Characteristics in Different Models of Doubly Fed Induction Generators
 [PDF]

陆强,
Advances in Energy and Power Engineering (AEPE) , 2013, DOI: 10.12677/AEPE.2013.15027
Abstract:
本文首先介绍了双馈风机的详细模型,其详细模型包括电机部分的模型、转子侧换流器控制部分模型以及电网侧换流器控制部分模型。然后对双馈风机的详细模型进行不同程度的简化以对其进行降阶。其简化模型包括:1) 忽略电网侧变换器控制作用,即认为其控制为理想情况;2) (1)的基础上忽略转子磁链的暂态过程,即所谓的零轴模型;3) 忽略所有控制作用的负阻抗模型,即用一个恒定的阻抗代替双馈风机。最后以新英格兰1039节点系统为例,对比分析了双馈风机采用详细模型及不同简化模型时系统的阻尼特性。分析结果表明,相对于详细模型,双馈风机的不同的简化模型得到的振荡模态的误差不尽相同,模型越详细,误差越小;忽略网侧变换器与零轴模型这两种简化模型所得的结果偏差较小,可以在一定程度上代替详细模型对系统进行阻尼特性分析。
The detailed model of DFIG, which includes the model of turbine, the model of rotor side control (RSC) control and the model of grid side converter (GSC) control. Then the detailed modes are reduced to the different degree to get the reduced modes. The reduced models include three different kinds: neglecting the effect of GSC control, which means that the GSC control is an ideal one; neglecting the effect of rotor transient based on the former kind; neglecting all the dynamic effects of DFIG, which are equivalent to the negative impedance. At last, the 10-generator 39-bus New Englandsystem is studied to analyze the damping characteristics of detailed model and different reduced models. The results show that: different models have different deviations of the oscillation mode; the more reduced of the model, the bigger error of the result. To a degree, the reduced models of neglecting GSC control and the zero-axis model can be used to replace the detailed model to analyze the damping characteristics of system.
区域物流配送信息系统的构建
The Construction of Regional Logistics Information System
 [PDF]

徐剑,
E-Commerce Letters (ECL) , 2013, DOI: 10.12677/ECL.2013.23004
Abstract:

为了配合区域经济的快速发展、减少区域物流给企业带来的成本压力、增强区域和企业的竞争力、加强区域物流配送整合能力,本文从区域物流配送信息系统构建的角度出发,分析当前物流配送信息系统存在的问题,确定区域物流配送信息系统构建的目标、原则。同时结合物流配送信息系统的三个层次分析和功能,系统平台分析,给出区域物流配送信息系统构建的总体框架结构,为其高效物流配送提供信息支持。
In order to cope with the rapid development of the regional economy, reduce the company’s cost pressure brought by the regional logistics, enhance the regional and enterprise competitiveness, and strengthen the regional logistics integration capability, from the perspective of regional logistics information system construction, this paper analyzed the existing problems of logistics information system, confirmed the target and construction principles of regional logistics information system. Combining with the function and analysis of the three levels of logistics information system and system platform analysis, the overall frame structure of regional logistics distribution information system is given, and the information support for its efficient logistics and distribution is provided.

电涡流式传感器液面测量控制系统
Control System of Liquid Level Measurement Based on Eddy Current Sensor
 [PDF]

, 迟宗
Computer Science and Application (CSA) , 2016, DOI: 10.12677/CSA.2016.68056
Abstract: 随着微电子技术的不断发展,智能化程度的日益加深,以及国家相关政策支持力度的不断加大,其在测量领域发挥的作用也日见显著。在工业生产与日常生活中,经常需要进行液面高度测量,采用微电子技术作为控制系统具有小型化、低功耗、可靠性高的优点。文中介绍了一种电涡流式位移传感器,是一以单片机为核心的液面高度测量电子控制系统。本控制系统以单片机为核心,控制液面高度数据的采集、管理以及远程通讯,具有体积小、维护容易、可靠性高、实时测量并显示液面高度值、记录历史数据、远程传输等优点。本文综合应用了传感器、微控制器等领域的知识,详细介绍了液面高度测量电子控制系统的整体结构及控制方法。本文的研究实现了液面测量电子控制系统的小型化,智能化,并基于接触式测量方法进一步确保了测量的精准度,从而降低了测量装置的复杂性,节约了材料,具有重要的现实意义和显著的社会效益。
With the development of microelectronics technology, increasingly intelligent and relevant national policies and support growing, its role in the measurement region has become more significant. In industrial production and daily life, it is often necessary for liquid level measurement, of which microelectronic technology is adopted as the control system, having advantages of miniaturization, low power consumption, and high reliability. Eddy current type displacement sensor is introduced in this paper, based on the single chip microcomputer electronic control system of liquid height measurement. This system uses single-chip microcomputer as the core control system, and controls liquid level data collection, management, and telecommunications. Small size, easy maintenance, high reliability, real time measurement and displaying the liquid height value, recording historical data remote transmission and so on are advantages of this system. This paper comprehensively applies knowledge in the areas of sensors, micro-controller, and introduces in detail the overall structure and control methods of electronic control system of liquid height measurement. This study implements the miniaturization and intelligentization of electronic control system of liquid level measurement, and based on contact measuring method ensures the measurement accuracy, which can reduce the complexity of measuring devices, save material, having important practical significance and significant social benefits.
二阶半正椭圆微分方程径向正解的存在性
Existence of radial positive solutions of second-order semi-positone elliptic differential equations


- , 2017, DOI: 10.6040/j.issn.1671-9352.0.2016.485
Abstract: 摘要: 获得了二阶半正椭圆微分方程Δu+λg(|x|)f(u)=0, R1<|x| 2,在 Dirichlet和 Robin边界条件下径向正解的存在性, 其中g∈C([R 1,R 2],[0,+∞)), f∈C([0,+∞),R)。 主要结果的证明基于锥上的不动点定理。
Abstract: We consider the existence of radial positive solutions of second-order semi-positone elliptic differential equationΔu+λg(|x|)f(u)=0, R1<|x| 2,with Dirichlet and Robin boundary conditions, where g∈C([R1,R2],[0,+∞)), f∈C([0,+∞), R). The proof of the main results are based on the fixed point theorems in cones
非线性三点边值问题正解的存在性
Existence of positive solutions for nonlinear three-point boundary value problem


- , 2017,
Abstract: 本文研究了三点边值问题 \[ \begin{cases} u''-k^{2}u+a(t)f(u)=0,~~t\in(0,1),\u(0)=0,~~u(1)=\alpha u(\eta) \end{cases} \] 正解的存在性,~其中~$a\in C([0,1],[0,\infty)),~\eta\in(0,1),~\alpha\in\Big(0,\frac{\sinh(k)}{\sinh(k\eta)}\Big),~f\in C([0,\infty),[0,\infty))$.~主要结果的证明基于锥上的不动点定理.
In this paper,~we study the existence of positive solutions for second-order three-point boundary value problem \[ \begin{cases} u''-k^{2}u+a(t)f(u)=0,~~t\in(0,1),\u(0)=0,~~u(1)=\alpha u(\eta), \end{cases} \] where~$a\in C([0,1],[0,\infty)),~\eta\in(0,1),~\alpha\in\Big(0,\frac{\sinh(k)}{\sinh(k\eta)}\Big),~f\in C([0,\infty),[0,\infty))$.~The proof of the main result is based on fixed point theorem
稳态吊桥方程耦合系统正解的存在性
An existence result on positive solutions for a coupled system of steady state suspension bridge equations


- , 2017,
Abstract: 本文研究了二阶和四阶常微分方程耦合系统 \[ \begin{cases} &~u''''(t)=\lambda f(t,v(t)), \ \ \ \ \ t\in (0,1),\&-v''(t)=\lambda g(t,u(t)), \ \ \ \ \ t\in (0,1),\&~u(0)=u(1)=u''(0)=u''(1)=0,\&~v(0)=v(1)=0\\end{cases} \] 正解的存在性,~其中~$\lambda>0$~为参数,~$f,~g\in C([0,1]\times[0,\infty),~\mathbb{R})$.~当~$f,~g$~满足适当的条件时,~证明了~$\lambda$~充分大时,~一个正解的存在性结果,~主要结果的证明基于~Schauder~不动点定理. }
In this paper, we are concerned with the existence of positive solutions of a coupled system of second-order and fourth-order ordinary differential equations \[ \begin{cases} &~u''''(t)=\lambda f(t,v(t)), \ \ \ \ \ \ t\in (0,1),\&-v''(t)=\lambda g(t,u(t)), \ \ \ \ \ t\in (0,1),\&~u(0)=u(1)=u''(0)=u''(1)=0,\&~v(0)=v(1)=0,\\end{cases} \] where $\lambda$ is a positive parameter, $f,~g\in C([0,1]\times[0,\infty),~\mathbb{R})$. We prove the existence of a large positive solution for $\lambda$ large under suitable assumptions on $f$ and $g$. The proof of our main result is based upon the Schauder's fixed point theorem
DOS及Windows下大块内存管理

计算机系统应用 , 1997,
Abstract: 在编程过程中,特别是在图象处理中,我们常常遇到需要显示和处理大幅图象(大于64K)的情况下,这时简单的应用指针加减并不能正确完成此工作。下面分别在DOS和Windows下讨论几种处理方法。1.DOS下的几种处理方法我们知道,所谓逻辑地址就是程序员在编程中所用的地址,而物理
南京长江大桥公路引桥桥面整修设计

公路交通科技 , 1997,
Abstract: 介绍南京长江大桥公路引桥双曲拱桥桥面整修设计特点以及该桥采用的以乙烯-醋酸乙烯(EVA)和丁苯橡胶(SBR)为改性剂的改性沥青材料.
Idid:一种基于免疫的动态入侵检测模型

科学通报 , 2005, DOI: 10.1360/972005-62
Abstract: 提出了一种新的基于免疫的动态入侵检测模型(Idid),建立了入侵检测中有关自体、抗原的动态描述方法,提出了免疫细胞的动态耐受概念,并建立了成熟细胞的生命周期以及免疫记忆等的动态模型及其递推方程.解决了计算机免疫系统中自体、非自体的动态描述问题,并同时有效地克服了传统计算机免疫系统中成熟细胞生成效率较低等缺陷.对模型进行了仿真,对比实验表明这种新型的入侵检测模型较传统方法具有更好的适应性.
黄土地区桥梁挖井基础设计方法研究

岩石工程学报 , 1997,
Abstract: 本文介绍了1∶2比例尺的桥梁挖井基础现场模型试验以及采用有限元计算程序对基础-土体进行的空间力学分析。结果表明,在竖向偏心荷载作用下有限元计算结果与试验结果较为一致。本文还提出了“剪压比例系数”的概念,按刚性基础-弹性土体共同作用理论,推导了在竖向、水平荷载作用下桥梁挖井基础的力学计算公式,最后给出了工程设计实例。
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