低压电网中的无功补偿探究

无功补偿在低压电网中的配比及作用是维持电流顺畅的重要条件因素,也是提高电网工作效能的核心因子。供电过程中注意无功补偿的合理运用,可以获得最好的技术和经济效益。文章论述了低压电网中无功补偿的必要性和低压电网的无功补偿要求,以及低压集中补偿方法,降低能效值;中间同步或静止补偿,保持补偿的顺畅性;用户终端分散补偿,提高电压利用率等低压电网中无功补偿的方法。     

啁啾FBG和DCF对16×10Gb/s系统进行色散补偿的性能研究

对负色散光纤法和啁啾光纤光栅法实现色散补偿的两种方案进行了模拟研究 ,结论是 :(1 )对各信道完全色散补偿的前提下 ,入纤光功率较小时 ,啁啾光纤光栅色散补偿系统误码性能较好 ;入纤光功率较高时 ,用负色散补偿光纤进行色散补偿效果更好 ;(2 )适当的欠补偿比完全补偿效果好 ,入纤光功率一定时 ,用啁啾光纤光栅比用负色散补偿光纤进行欠补偿的效果好     

半主动天车升沉补偿试验平台设计与分析

半主动天车升沉补偿装置是一种实现浮式钻井平台升沉运动的节能高效装备，但其相关技术被国外厂商封锁且国内尚缺乏准确有效的试验支撑，为此建立了补偿作用下的四自由度钻柱纵向振动模型以揭示半主动天车升沉补偿机理，并以此为理论依据设计了半主动天车升沉补偿试验平台及其机械结构、液压系统和控制系统。该试验平台的主要设计参数包括补偿载荷、最大补偿行程以及最大补偿速度，从工况模拟能力、补偿缸载荷以及补偿效率这3个方面综合分析了平台的试验能力。结果表明：通过控制浮动天车位移可以明显降低升沉运动对钻压的不利影响；主、被动补偿缸分别承担了补偿过程中的动、静载荷；设计的试验平台不仅能模拟满足实际要求的补偿工况，而且在最大补偿工况下的补偿效率为93.14%，说明它具备良好的试验能力。研究成果为半主动天车升沉补偿技术的研究提供了可靠的理论和试验依据。     

低压电网功率因数的影响与其无功补偿方法

本文介绍电力系统中无功补偿的作用、原则，以及影响功率因数的因素、补偿方法、补偿容量的选择与无功补偿效益。     

无功补偿技术对低压电网功率因数的影响

1．前言无功补偿，就其概念而言早为人所知，它就是借助于无功补偿设备提供必要的无功功率，以提高系统的功率因数，降低能耗，改善电网电压质量。无功补偿的合理配置原则：从电力网无功功率消耗的基本状况可以看出，各级网络和输配电设备都要消耗一定数量的无功功率，尤以低压配电网所占比重最大。为了最大限度地减少无功功率的传输损耗，提高输配电设备的效率，无功补偿设备的配置，应按照“分级补偿，就地平衡”的原则，合理布局。（1）总体平衡与局部平衡相结合，以局部为主。（2）电力部门补偿与用户补偿相结合。（3扮散补偿与集中补偿相结合，以分散为主。集中补偿，是在变电所集中装设较大容量的补偿电容器。     

煤矿配电低压无功补偿技术应用研究

煤矿配电无功补偿对于提升供电体系的运用效率,提升功率因数具有重要意义。论文从低压配电网的无功补偿以及配电变压器的低压无功补偿两大角度出发探究了无功补偿技术的应用,并以武汉某电气所设计的补偿方案为例探究了煤矿配电低压无功补偿技术应用效果。     

黏弹性阻尼器温度软化效应补偿控制

提出新型黏弹性阻尼器温度软化效应的补偿与控制策略,通过控制试验检验智能控制器精度及温度软化效应补偿控制效果。据此研制出基于脉宽调制技术的温度补偿智能控制器,结果表明,智能控制器精度较高,所提出的温度补偿控制策略可以很好地补偿黏弹性阻尼器温度软化效应,控制器精度与补偿效果均能满足阻尼器实际工作要求。     

民用建筑工程配电无功补偿的分析与选择

本文根据民用建筑工程的用电特点，通过无功补偿的基本原理和补偿方式分析，阐述了民用建筑工程无功补偿选择分相电容补偿的理由与可行性。     

无功补偿技术对低压电网功率因数的影响

无功补偿技术对低压电网的功率因素有着重要的影响,基于此探讨无功补偿配置的原则、方法等技术范畴,对于提高低压电网功率因素、电能质量,和提高电网经济效益具有重要意义。电网中的电力变压器和异步电动机设备,及低压电网的频率、电压波动均是影响电网功率因数的关键。技术上选择采用随机补偿、人工补偿和跟踪补偿的技术方式,补偿容量的选择方法则有单负荷就地补偿和多负荷补偿容量的方式。     

无功就地补偿及其效益分析

本文介绍了就地补偿的原理，补偿容量的选择及使用场合，分析了就地补偿的效益，说明就地补偿是一项很好的节能措施。     

The Stiles–Crawford Effect: spot-size ratio departure in retinitis pigmentosa

The Stiles–Crawford effect of the first kind is the retina’s compensative response to loss of luminance efficiency for oblique stimulation manifested as the spot-size ratio departure from the perfect power coupling for a normal human eye. In a retinitis pigmentosa eye (RP), the normal cone photoreceptor morphology is affected due to foveal cone loss and disrupted cone mosaic spatial arrangement with reduction in directional sensitivity. We show that the flattened Stiles–Crawford function (SCF) in a RP eye is due to a different spot-size ratio departure profile, that is, for the same loss of luminance efficiency, a RP eye has a smaller departure from perfect power coupling compared to a normal eye. Again, the difference in spot-size ratio departure increases from the centre towards the periphery, having zero value for axial entry and maximum value for maximum peripheral entry indicating dispersal of photoreceptor alignment which prevents the retina to go for a bigger compensative response as it lacks both in number and appropriate cone morphology to tackle the loss of luminance efficiency for oblique stimulation. The slope of departure profile also testifies to the flattened SCF for a RP eye. Moreover, the discrepancy in spot-size ratio departure between a normal and a RP eye is shown to have a direct bearing on the Stiles–Crawford diminution of visibility.     

补偿式光纤F—P干涉仪的信号处理系统

本文提出并研制成补偿式光纤F-P干涉仪信号处理系统,提出了用来测量微小位移信号的三种方法及电路,即透射峰时间间隔测量法、光脉冲基波幅度测量法(精密整流法)、鉴相法。测试结果表明:时间间隔测量法,它的最大灵敏度达到0.26纳米/微秒;精密整流法,最大灵敏度为2.38纳米/伏特。     

车辆动态称重的速度补偿研究

研究了速度对车辆动态称重准确度的影响,并对车辆载重受力进行分析,导出速度与车辆轴重的数学表达式,利用机械动力学分析系统构建了动态称重有限元模型仿真称重过程,并对速度影响进行补偿。结果表明,基于机械动力学分析系统的有限元动态称重速度补偿模型正确可靠,20t载重汽车在8.33m/s情况下最大补偿量达到10%,大大提高了动态称重准确度。     

光电测量系统中的实时调平补偿方法

为了使测量设备快速进入测量状态,减小因倾斜带来的测量误差,结合工程实际应用,根据光学成像理论,利用水平倾角仪测量的角度值,建立了一个实时调平补偿的数学模型．根据不同的测量设备确定其补偿算法,可对测量设备在一定的倾角范围内倾斜时进行实时补偿,并进行了实验验证．实验结果表明,测量设备在倾角α=0．325°,β=0．896°倾斜情况下,经过实时补偿可将系统测量误差由0．126％提高到0．026％．     

A calorimeter for μW level optical power transfer standard

A calorimeter which can measure microwatt-level optical power has been developed for an optical power transfer standard. It can measure the optical power of a light beam and can be used with optical fiber simply by attaching an adapter. This calorimeter sensor uses a compensative absorber to reduce the influence of pressure fluctuation and temperature variation in the measurement room and an ultra-low-noise preamplifier. With this calorimeter, the standard deviation of the measured value is in the range of 0.02-0.4% in 20-mW to 10-μW optical power measurements. An error evaluation for an optical power level of 10 μW yielded a two-sigma (two standard deviation) total uncertainty of 0.9%     

基于轧件水平振动的轧机辊系振动补偿模型

考虑轧件水平振动对轧制力和摩擦力动态特性的影响,建立了一种基于轧件水平振动的轧机辊系振动补偿模型。根据广义耗散的Lagrange原理,分别沿轧制方向和垂直轧制方向建立动力学平衡方程。以某厂四辊板带轧机为例,仿真分析轧件水平振动速度和轧机辊系垂直振动位移随轧辊转速的变化规律,测试了5组不同转速下的轧制力数据;对模型补偿前后轧制力理论值与测试数据误差进行了对比。研究结果表明:补偿后的模型轧制力理论值与实测数据之间的误差大大减小。     

Calcul de résistance de structures planes en béton armé de fibres

Résumé Une méthode de calcul de structures armées de fibres est présentée. Les caractéristiques du matériau sont exprimées au moyen de relations matricielles, compte tenu de l'arrachement des fibres dans une matrice plane fissurée. La méthode par éléments finis permet de prévoir le comportement élastique et plastique, ainsi que la fissuration et la rupture. Les résultats de l'analyse générale sont comparés avec les résultats d'essais sur deux poutres en béton armé, l'une avec fibres et l'autre sans.

---

Summary This article treats about the strength behaviour of brittle construction materials, especially concrete, reinforced with steel fibres. The material characteristics are expressed by matrix relationships, which describe the elasto-plastic behaviour as well as the cracked behaviur of concrete reinforced with fibres. Those relationships permit to predict the bearing capacity of any structure in the elastic, the plastic and the cracked states. After cracking of the concrete, the fibres are pulled out while the adhesion and the attachment are resisting. The material laws are then incorporated in an analysis with the finite element method: the plane structure is subdivided in elements in which a proper account is taken of the variable material characteristics. When a crack appears in a finite element, the stress state alters and this change gives rise to compensative nodal forces. These forces alter again the stress state and new cracks can appear, so that an iterative scheme must be adopted for each load increment. The results of the general analysis are compared with results of tests on two reinforced concrete beams, one with and one without steel fibres. The analysis has the feature to predict the overall behaviour of fibre reinforcement for any complex structural shape at any load stage.

     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.