重金属锌污染砂的交流电阻率特性试验

为研究交流电阻率法检测重金属锌污染的可行性,通过对不同的锌污染砂试样进行电阻率测试,分析了电流频率、含水量、孔隙比、锌污染含量等对砂电阻率的影响,建立了影响锌污染砂交流电阻率的经验公式。结果表明,电阻率随电流频率的增加先急速降低,当电流频率增加到50 kHz时,电阻率逐渐趋于稳定;以锌含量50 mg/kg为界,锌含量越低,电阻率对电流频率的变化越敏感;电阻率随含水量的增加而减小,含水量越低,电阻率变化越快;电阻率随孔隙比的增加而增大,增幅较缓;电阻率随锌含量的增大而急速减小,当锌含量高于250 mg/kg后,电阻率逐渐趋于稳定;砂电阻率与锌污染含量间呈现高度相关的幂函数关系,得出了包含饱和度、孔隙率、锌污染含量的砂交流电阻率关系公式。     

OPTIMAL ACTIVE POWER ADJUSTMEMT OF LARGE HYBRID AC/DC SYSTEMS AFTER OUTAGE CONTINGENCIES WITH THE APPLICATION IN RELIABILITY EVALUATION

An optimal active power adjustment model is deve in this paper for hybrid AC/DC systems after outage contingencies. The objective of the model is to minimize the rejection of load when some elements are out of service, with adjustment strategy approaching practical system operation. A large number of outage contingencies are simulated when the Monte-Carlo Method is emyloyed to evaluate the system reliability, requiring fast calculation of each simulation. The model and computer method proposed in this paper satisfy such a requirment because of the application of concentric relaxation, recursive branch constraint treatment in linear programming and a direct method for B-1 matrix modification. This paper is concerned with the simplified steady state conditions of the system based on DC load-flow, which implies the reliability indices calculated are the measures about static loss of load. The results for a 14-bus hybrid AC/DC system are given.     

The Study of Mix Coefficient of the Stopcock Wind in Metro with Safety Door

Through study of the rule of the air current between the metro stations which had installed the safety door system and the tunnel, this text established a physics model and a mathematics model, gained the mix coefficient which can marks the degree of the influence stopcock wind in metro inflict to the heat environment, exerting reasonable assumption and simplification, making use of the CFD imitation, adopting tracer air. The text elected three kinds of safety door system with different height to simulate and compare, gained the exact value of the mix coefficient, and simulated the energy consumption of subway air conditioning in different height of safety door by the mix coefficient.     

Fast modeling of the motor broadband equivalent circuit model

This paper proposes a modeling method of the motor broadband equivalent circuit model. The impedance amplitude-frequency characteristics of the motor terminal through measuring are obtained. The impedance amplitude-frequency characteristics are devided into several regions based on its first resonant point information,and the motor broadband circuit topology is developed with each region equaling a resonance unit. The RLC parameters of resonance unit are extracted through frequency and corresponding impedance of the any non-resonant and resonant point in each unit. This proposed method is used to build DC and AC motor broadband equivalent circuit model. Their impedance amplitude-frequency characteristics are simulated by the Saber software. The measurement results and the simulation result of references are compared. The DC motor simulation results coincide with the measurement results in 0.1~50 MHz,and the AC motor is in 0.1~40 MHz. The results show that the motor broadband circuit model is reliable and feasible.     

鸡传染性法氏囊病病毒单克隆抗体的应用

通过中和试验证明，Ｂ３４腹水单克隆抗体中和ＩＢＤＶ ＣＡ株和中和效价高达１：４２００００。经１０倍稀释后，能等量中和含毒量为１０＾６．６２５ＴＣＩＤ５０／ｍｌ的ＩＢＤＶ ＣＡ株细胞毒。利用Ｂ３４腹水单克隆抗体建立了ＭＡｂ－ＡＣ－ＥＬＩＳＡ，可用于测定ＩＢＤＶ ＣＡ株细胞的病毒含量，与ＴＣＩＤ５０之间的相关系数为０．９４。     

Modeling and Simulation of the Doubly Fed Generatorwith the Matrix AC-AC Converter as an Exciter

According to the space vector modulation method of the AC DC AC converter,the switch control scheme of the matrix AC AC converter is deduced,and the model of a three phase matrix AC AC converter is constructed. According to the mathematic model of the doubly fed generator and the excitation control principle based on dynamical synchronous reference frame,the simulation model of the generator and excitation controller are established,then the modeling and simulation of the doubly fed generator system with the matrix AC AC converter as an exciter are implemented.The steady state and transient characteristics of the system are simulated,the harmonics of the EMF and stator?rotor current are researched.     

直链淀粉含量不同的稻米淀粉结构、糊化特性研究

选用直链淀粉含量不同的4个水稻品种,研究其淀粉体结构和糊化特性。发现不同品种的淀粉体结构、糊化特性随直链淀粉含量的不同呈现一定的变化规律。直链淀粉含量从3.43%至21.65%,其晶体类型为A型,相对结晶度呈下降趋势,消减值表现为升高趋势,相对结晶度和消减值与直链淀粉含量分别呈显著负相关和极显著正相关(r=－0.964*, r=0.997**),消减值与结晶度呈显著负相关（r=－0.960*）。米粒的背部和腹部间淀粉体大小和排列有所不同,糯性或低直链淀粉含量与非糯性或高直链淀粉稻米的胚乳结构存在差异,淀粉体排列以糯稻较紧,粳稻次之,籼稻最松。淀粉的相对结晶度可能与胚乳中淀粉体的形状和紧密程度有关。     

大功率拖拉机传动系试验技术研究

针对大功率拖拉机传动系室内试验的特点和难点,提出了可行的解决方案。基于NI LabVIEW虚拟仪器平台建立了传动系仿真试验系统,找到了实现差速器"电轴"连锁的控制方法,并通过试验进行了技术验证。     

新大管道杂散电流干扰影响研究

针对新大管道受到来自轻轨铁路及交流高压线路等杂散电流的干扰可能导致的腐蚀穿孔问题,进行了研究分析,并对其主要干扰源相关数据进行了测试分析,采取了有针对性的排流防护措施。实践表明,管道保护电位达到正常值,直流排流保护效果满足相关标准要求。     

主轴交流伺服系统稳定性控制策略研究

基于交流电机矢量控制理论,结合某加工中心主轴交流伺服系统,给出了该伺服系统基于传函的控制框图。应用Matlab语言与simulink仿真工具,对不同伺服参数配置下的加工中心主轴动态性能进行了数值计算和动态仿真,得到了这些参数对主轴交流伺服系统稳定性的影响规律,进行了主轴交流伺服系统稳定性控制策略的初步研究。