不同分析方法在黑龙江省玉米联合体 试验中的应用及比较分析

为了给综合评价玉米新品种(系)提供依据和方法,本试验采用方差分析法、灰色关联度法、DTOPSIS法和同异分析法对2019年黑龙江省玉米联合体试验的15个品种(系)进行综合分析评价、优劣排序,并对4种分析方法进行了比较研究。结果表明:方差分析法与灰色关联度法和同异分析法的秩相关系数分别为0.829和0.661,相关达极显著水平,与DTOPSIS法显著相关(0.557),说明4种分析方法都能反映玉米品种的优劣表现;方差分析法较其他3种综合分析方法,分析产量单一性状,综合能力差;在离散程度越大说明分析方法越准确的区分度检验中,区分度由大到小依次为DTOPSIS法(0.6371)、灰色关联度法(0.2838)、同异分析法(0.2152)、方差分析法(0.0579),由此可以看出本试验条件下DTOPSIS法综合评价效果更适合用来评价玉米新品种。     

励磁功率单元主回路快速故障诊断策略

分析总结了发电机组励磁系统功率单元的故障类型和常见故障,通过Matlab仿真功率单元主回路故障类型,重点研究基于故障频谱分析的定量故障特征提取和故障分类,提出了一种快速针对功率单元主回路的故障诊断真值表法,最后通过实验平台验证故障类别,结果表明：该方法能够正确有效地诊断出功率单元主回路具体的故障晶闸管,为励磁系统功率单元故障诊断提供依据。     

土壤水分测定三种方法的比较

对气量失重法、气量体积法和烘干法3种土壤水分测定方法的测定结果进行比较。结果表明,气量体积法与烘干法测定结果相比有较大差异,气量失重法与烘干法测定结果基本吻合,并分析气量体积法和气量失重法测定结果产生偏差的原因。     

含电压逆变型分布式电源配电网的短路电流计算

分布式发电接入改变了配电网潮流和短路电流分布,其提供的短路电流将对电网保护和重合闸动作产生影响。文中通过研究电压控制逆变型分布式电源（ⅡDG）的故障响应特性,分析配电网不对称故障时ⅡDG三相平均功率与正负序网功率关系,建立计及电压型ⅡDG对称控制特征的短路计算序分量模型。根据ⅡDG与配电网正负序网络的交互作用,推导电压型ⅡDG的故障电流变化规律,提出计算含电压型ⅡDG配电网短路电流的对称分量迭代算法。在PSCAD/EMTDC仿真软件中建立电压型ⅡDG的电磁暂态模型,仿真验证了该方法的正确性。     

葡萄酒中农药残留的色谱分析法研究进展

概述了目前应用于研究检测葡萄酒中农药残留的色谱分析方法的研究进展，主要分析方法包括：气相色谱（GC）分析法、液相色谱（HPLC）分析法、气相色谱-质谱联用（GC/MS）分析法、液相色谱-质谱联用（HPLC/MS）分析法。并对目前葡萄酒农药残留的现状进行了分析。     

含旋转电机接口和逆变器接口的微网小信号稳定性分析

提出了一种包含了逆变器接口（voltage source inverter,VSI）、同步电机接口（synchronous generator,SG）的独立微网控制策略,并分析了其小信号稳定性。VSI接口和SG接口的分布式电源均采用下垂控制策略,二者之间无需实时通信,可实现负荷功率共享。建立了系统的小信号状态空间模型,主要包括：同步发电机及其控制器的小信号模型、逆变器及其控制器的小信号模型、电网络及负荷小信号模型。计算了下垂增益变化时的根轨迹,得到了系统主特征值随参数变化的根轨迹,计算了不同状态变量对特征值的参与因子。稳定性分析结果表明：当所有分布式电源采用下垂控制时,引入同步发电机接口的分布式电源,系统频率小信号稳定性大大增强。PSCAD时域仿真验证了特征值计算的正确性。     

矿用高压开关电器短路开断与关合试验电源

针对国内冲击发电机性能参数不足,以国外冲击发电机作为试验电源,建立基于直接试验法的矿用高压开关电器短路开断与关合试验系统,提出了一种新的技术解决方案。仿真试验结果表明,该方案满足综合性煤矿高压电气实验室建设项目技术指标和试验标准要求,为大容量开断与关合试验系统设计和建造提供一种技术思路。     

距离分析方法在小麦亲本选配中的应用研究

作者对距离分析方法在小麦亲本选配中的应用问题做了系统研究,本文是这一研究的总结报告。结果表明:1.遗传距离与杂种优势的关系受试验材料的影响。从聚类结果来看,在小麦育种中选择类间亲本进行杂交要优于类内亲本间的杂交。2.就性状选用方法而言,广义遗传力法要优于常规法和权重法。3.距离分析所反映的遗传差异不同于亲缘差     

品种稳定性参数和高稳系数在小麦区试中的应用及其分析

本文应用品种高稳系数法和回归系数座标分析法分析了1997—1998年度山西省南部冬小麦中水肥区试中11个参试品种(系)在10个区试点的高产稳产性,并对两种方法的分析结果进行了评价比较。结果表明,高稳系数法计算简便且分析容易,但用一个参数表达品种两方面的性状,不免会顾此失彼,所以高稳系数法较粗放,而回归系数座标分析法则是对参试品种的丰产性稳产性较详细准确的分析方法。缺点是回归系数计算及座标图的绘制较繁琐。所以在对区试结果不需详细分析时,用高稳系数法较简便容易;如需详细分析时,则用回归系数座标分析法较准确可靠。同时对几种品种稳定性参数的准确性进行了比较分析,结果表明品种间回归系数的大小能较准确地反映出品种间稳定性差异程度的大小,其对稳定性的代表性要准确于其它稳定性参数。     

镇村同治示范区的SWOT分析与规划对策——以湖南省常德市临澧县官亭乡为例

“镇村同治”是当前新形势下,按照城乡一体化的要求,从区域性中心镇入手,实行镇村同步规划、环境同步治理、产业同步发展、文明同步创建、推动新型城镇化与新型农村建设协同发展的整体性建设。将SWOT分析方法与示范区建设发展框架联系起来,形成针对示范区建设发展研究的SWOT分析框架和示范区建设发展定位的SWOT分析方法体系。以湖南省常德市临澧县官亭乡镇村同治示范区为例,分析影响该示范区的S、W、O、T各因素,提出示范区镇村同治规划的对策。     

A Method of Simulation of Squirrel-cage Motors with Rotor-rar and End-ring Faults

In this paper,a method used to simulate the squirrel-cage motors with rotor-barand end-ring faults is presented. In our analysis,the stator is still represented by three-phase windings,but each loop of the rotor is considered as a single-phase winding,so it is convenient to describethe situation of the motor with any number of broken rotor-bar and end-ring.Compared with othermethods,the method of this paper can be used to analyse both the steady-stats and the transient stateof cage motor with rotor faults.     

HIGH SPEED CALCULATIONS OF SHORT CIRCUIT FOR POWER SYSTEMS WITH VARIABLE STRUCTURES AND PARAMETERS

This paper presents a new method for digital simulation of equivalent circuit parameters and port currents of the short circuit fault port for each sequence networks in power systems with variable configuration and parameters. If the electric values for single-line-to-ground short ciruit are calculated in detail,the other faults at the same location can be rapidly obtained by using the proportional coefficients of the same sequence port current. In this method,the modifications of Z-bus or Y-bus matrices for each sequence network, and the repeated of calculations of the short circuit calculation have been completly avoided.     

A New Method of Piece-Wise Solution in Faulted Power Systems with Variable Configurations

A new model and its algorithm are presented in this paper to simulate calculating the electric values of short circuit fault in large-scale power systems with variable configurations. The method proposed herein reduces the computer storage requirements compared with the available approaches. And it completely avoids the modification computation of nodal impedance (or admittance) matrices of the original networks and the repeated calculations for each type of faults.     

Research of the winding ratio to prevent yarn overlapping

Unapt winding parameters may cause yarn overlapping with the problems of low yarn density, winding vibration, breaking and disorder when unwinding yarn and others. The yarn arrangement rules and its relationship with the winding ratio are analyzed using geometrical and mathematical methods. It is revealed that winding ratio is an important parameter to prevent yarn overlapping. When the winding ratio is proper, the yarn can be staggered regularly and yarn overlapping can be prevented effectively. A new method for the determination of the proper winding ratio is introduced. The alteration of yarn angle and interval and their effect for the determination of the winding ratio are discussed. The particular process of the method is given and an example is presented.     

Electromagnetic field models and their influences onthe temperature field of large hydro generator

To accurately analyze the loss and heat of large hydro generator,the finite element models of 2D steady state electromagnetic field,moving electromagnetic field and field circuit coupling are established respectively.As an example,the losses of the rotor iron and damper winding of a 36 MW tubular hydro generator are calculated.Furthermore,the influences of 3 different electromagnetic field models on the thermal sources and temperatures are analyzed by 3D finite element calculation of the temperature field.The results are compared with the test data and indicate that the precision of the field circuit coupling model is better.The losses of each damp bar are different and the heat of the damp bar at the lee side is larger than that at the windward with the full load.The maximal temperature of the rotor is located at the damper winding,instead of the field winding.The research is valuable for improving the calculation precision of the rotor losses and temperature field and enhancing the reliability of the hydro generator design and operation.     

Simulation on parallel conditions for small single phase synchronous generators

The controller of paralleling small single phase synchronous generators should restrict the dash currents in generators below a defined value when it switches on. A field-circuit coupling time-stepping finite element model of the parallel system is built. The computation program is written in APDL languages of ANSYS and the transient process of paralleling two single phase synchronous generators in various parallel parameters are studied. The value and variation of the dash currents in two generators when switch on at various differences of three parallel parameters are analyzed and the accurate parallel conditions are provided to the parallel controller.     

苹果品质近红外光谱无损检测技术研究进展

近红外光谱(NIRS)分析技术以其快速、无损、多组分同时测定及可在线分析等优势,近年来在苹果品质无损检测应用技术的研究方面取得了重要进展。本文介绍了NIRS分析技术的原理与特点,从苹果品质的定量与定性分析、在线检测及便携式检测等方面综述了国内外NIRS在苹果品质检测中应用的研究进展,并对其应用前景进行了展望。     

An improved dynamic model of transformer hotspot temperature based on top oil temperature

The winding hot spot temperature of the oil immersed power transformer is an important parameter. It has a great influence on the transformer insulation aging and a close relationship with the transformer top oil temperature. The changes of non linear thermal resistance, open circuit impedance, and oil viscosity and winding losses with temperature are also taken into account. An improved model added on the transformer top oil temperature to calculate transformer winding hot spot temperature by using the viscosity and loss correction factors is proposed. Model parameters are estimated by Levenberg Marquardt method. In the end, by comparing with the measured data tested under different conditions, the model shows good consistency under underload (90%), rated load (100%) and overload (110%) conditions respectively, and describes the temperature variation more accurately in the dynamic loading profiles.