General Phasor Diagram and Power-angle Characteristic Equations of Extra High Voltage Long Distance Transmission Line

Installing compensation equipments is a good manner to improve line transmission capacity and maintain power system stability in the extra high voltage(EHV) long distance transmission line.It is of benefit to analysis and control by describing the effect of compensation equipment correctly.At present,for predigesting analysis or increasing real-time calculating speed,concentrated parameter circuit model is widely used to analyze 500 kV EHV long distance transmission line which may cause bigger error.So it is necessary to get a more reasonable model.On the basic of voltage and current distributed equations of even distributed long distance line,this paper deduces phasor diagram and power-angle character equations of uncompensated long line.Then the authors analyze the effect of compensators and define two characteristic parameters,namely,equivalent impedance x_(eq) and voltage coefficient K_V.Any compensating states of EHV long distance transmission line,example installing the compensators in the line or not or which type of compensators,is described by the general phasor diagram and power-angle characteristic equations.Furthermore,increment calculation(equations) of two characteristic parameters is presented by the compensator parameters which may make the concepts clear and predigests analysis easily.     

高压静电场杀菌效果研究

利用自行研制的直流高压静电场装置针对大肠杆菌进行了杀菌实验研究,结果表明,电压、处理时间是影响电场杀菌作用的主要因素.在极板间距D=3 cm,电压20 kV,处理时间45 min的务件下,大肠杆菌的致死率达到98.7%.     

高压静电技术在食品加工中的应用

介绍了高压静电场技术在食品加工中的作用机理。阐述了静电场技术在食品保鲜、干燥、杀菌、解冻和催陈等方面的应用。     

Analyze the Present Status in the Calculation Methods of Lightning Protection Performance for Transmission Line

Lightning is the main reason that endangers transmission line working safety and reliabilty today. The theory and characteristic of methods that not only estimate the lightning performance for back strike such as standard method, traveling wave method, Monte Carlo technique, treeing fault method, EMTP and so on but also for the shielding failure such as standard method, EGM, leader progression model and so on are summarized. The criterion of flashover for insulators is referred simply, furthermore, it gives the opinion that the development of research for the future.     

Computerized Simulation of the Transmission Line in High-speed PCB

With the rapid development in logic circuit,the effect of transmission line in PCB becomes a confined factor.In the design of high-speed PCB,the factors which affect the integrity of signal can be found by computerized simulation of the transmission line,simultaneously the signal quality could be optimized.The capacitance matrices of transmission line in high-speed PCB have been computed with this method that is the total charge Green's functions with method of matrix,then the time-domain model is built.Connected to IBIS model of the I/O buffer these models can be used in computerized simulation of the transmission line.The result of simulation is equal with the result produced by EDA software-Specctraquest of cadence Co.and the efficiency of simulation is advanced.     

Lightning Protection Performance of Transmission Line with High Tower and Great Span

This paper studies lightning protection performance of transmission line with high tower and great span, and puts forward the lightning shielding model of transmission line with high tower and great span. The model simulates the developing process of lightning downward leader, and take the effect of upward leader to downward leader into account. Moreover, the model consider backward lightning , that is even downward leader have developed lower than transmission line, Which will be occur lightning line. Aim at a certain sea transmission line with great span, its lightning performance is calculated with regular method, EGM and the model. The results have been analysed and compared. Because of thinking over backward lightning , the model can be used for calculating lightning shield performance of all kinds of transmission lines.     

Model and Numerical Analysis of Radiation Field Created by Lightning Overvoltage Wave on Transmission Lines

The radiation field created by the transmission line stroked by lightning far from the lightning channel has been analyzed by the FDTD method.The authors we establish the calculation model and FDTD calculation method of transmission line,and discusses the import of lightning excitation source.The simulation of lightning stroked on a single transmission line in free space or stroked on three-phase high voltage transmission lines in actual environments has been done,and gives the distribution of transient radiation field around the transmission lines when lightning overvoltage wave transmits along the transmission line.The simulation result shows that: the effect of the transient radiation field caused by lightning over voltage wave done with environment is obvious,and the high frequency component of transient radiation field may disturb or do harm to the electronic facility or communication facility around the transmission lines.     

高压静电场处理对草莓保鲜品质的影响

为探究高压静电场（High voltage electrostatic field,HVEF）处理对草莓贮藏过程中品质的影响,将草莓置于高压静电冰箱,分析其在贮藏过程（0～15 d）中VC、可溶性糖、可滴定酸含量及感官品质等指标的变化。结果表明：HVEF处理能有效延缓草莓在贮藏过程中可滴定酸含量的上升以及可溶性糖和VC含量的下降,减少草莓的腐烂损耗。贮藏12 d时,HVEF组草莓的好果率为97.33%,CK组为89.33%;贮藏15 d时,HVEF组草莓的VC含量显著高于CK组（P<0.05）。因此,该高压静电场处理能够有效抑制草莓的品质劣变,延长其保鲜期。     

高压静电场处理对鲜核桃保鲜效果的影响

以"中林1号"鲜核桃为试材,采用-100 k V/m高压静电场对其分别处理1.0、1.5、2.0、2.5 h,并辅以0.03 mm厚聚乙烯(PE)保鲜袋包装,于(0±1)℃下贮藏,研究不同时间的高压静电场处理对鲜核桃的保鲜效果。结果表明,贮前采用高压静电场处理1.5 h可延缓鲜核桃呼吸高峰的出现,降低呼吸峰值,提高鲜核桃青皮SOD活性,抑制POD和PPO活性,减少鲜核桃青皮中总酚的损失,降低腐烂指数,延长保鲜期,具有较好的保鲜效果。     

高压静电处理对大豆种子的影响及机理研究

用场强为EN=1×N/(kV/cm),N=0,1,2,…10的电场处理大豆种子20 min,研究种子形态指标和外渗率随电场强度的变化情况,根据具体的实验数据,从物理学角度对实验过程中可能存在的机理进行了深入的分析.     

高压静电技术在食品保鲜与加工中的研究进展

介绍了高压静电场技术对食品的作用机理。阐述了静电场技术在食品保鲜、干燥、杀菌和解冻等方面的研究现状。     

Analysis on the Lightning Protection Performance of 500 kV Double-circuit Transmission Line

Using double-circuit transmission line is the developing tide for main 500 kV configuration to reduce line holding ground, so analyzing it's lightning protection performance is important to extend double-circuit transmission line in ultra high voltage network. The lightning protection performance of 500 kV double-circuit transmission line is studied with EMTP and EGM. The statistical method is applied to analyzing the lightning protection performance of back stroke by considering the randomness of working voltage's phase when lightning stroked the top tower. The result is that the line lightning protection level is different when the working voltage of conductor is different. It also improved the EGM by considering the effect of wind speed when analyzing the lightning protection performance of shielding failure. Furthermore, the results are given that wind speed has effects on the protection angle and the rate of shielding failure by using the program to calculate it.     

Numerical Simulation of Dynamic Response of Suspension Insulator String

Finite element method is applied to analyze the windage of suspension insulator strings under dynamic wind loads. The dynamic response of a suspension insulator string of 500 kV high voltage transmission line is numerically simulated with ABAQUS software, and results demonstrate that the windage angle of suspension insulator string is larger than that calculated by the conventional design code, which might be one of the main reasons of the frequently happened windage flashover accidents.     

高压静电场处理对蔬菜种子萌发期抗盐碱的试验研究

利用高压静电场,对茄子和刺青瓜种子进行处理,然后置于不同盐碱条件下萌发,采用U5(54)均匀设计,安排多因素多水平试验,测定了蔬菜种子的发芽势、发芽率及其SOD、VC、MDA等生化指标,建立了相应的数学模型,发现经过高压静电场处理后,种子萌发期抗盐碱能力减弱,生理生化指标也发生相应变化.     

Force Analysis on Meshing Surface and Stress Research of the Cone Roller Enveloping Worm Gearing Transmission

By using the finite element elastic contact analysis method combined with the I-DEAS engineering analysis software, this paper studies the strength of the cone roller enveloping worm gearing,which is a new type of worm gearing transmission,on SUN-4 working station. It also analyzes loading distribution among meshing gears, the contact force distribution along the contact line ,the bending stress distribution and the contact stress distribution of the cone roller enveloping worm gearing with three-tooth meshing instantaneously. Besides,it provides the theoretic basis in the further researches for the new type of worm gearing transmission.     

Nominal electric field calculation at the ground level of UHV DC transmission lines based on radial basis function method

Nominal electric field at ground level is one of the important factors for the design of transmission lines. FEM meets two big challenges in electromagnetic field computation. One comes from the mesh generation, which is a big difficulty especially in complex geometry. The other is the long time calculation. So the radial basis function method is introduced to calculate the nominal electric field at the ground level of UHVDC transmission lines. Not only the definition and ideas, but also the detailed implementation procedure of radial basis function method are presented. Computer programs are developed to simulate the model and the influences of conductor configuration on nominal electric field intensity are analyzed. Examples of calculation show that the results are accorded with those available literatures, and agreed satisfactorily with analytic solutions of the coaxial cable model. The height of the polar lines and conductor inter-spacing has a remarkable influence on ground nominal electric field intensity while the sub-conductor radius and number of sub-conductors have little influence.     

高速逆流色谱技术在天然产物研究中的应用进展

高速逆流色谱是液-液分配色谱,与传统固-液分配色谱相比,其具有固定相成本低、易回收、分离过程灵活、高效等优点,近年来被广泛应用于天然产物研究中.本文总结归纳了高速逆流色谱的两相溶剂体系、分离洗脱方式的选择和应用方法,分析阐述了高速逆流色谱技术在天然产物研究中的应用实例,为天然产物功效成分的进一步深入研究提供可靠的技术参考.     

Application of Coordinate Difference Method in Safe Monitor of High Slope with Total Station Actively

The most common used method for safe monitor of high slope is to set a fixed observation point to monitor the transformation. But in urban area, due to restriction of the site and telecommunication conditions the transformation of high slope may have an impact to the fixed point and the result and the result we take from the point may be not correct. To avoid the impact and improve the accuracy, in this paper, a coordinate difference method to monitor the transformation of high slope with Total station actively is put forward and the principle, error analyses of this method are described and its application in safe monitor of high slope is introduced.     

浅析信息化教学模式在高职园艺专业教学中的应用

信息技术的高速发展使得教育手段和教学模式发生了重大变化,信息化教学模式的应用为教育质量提升创造了更多可能。基于高职院校园艺技术专业课程教学模式改革,探索信息化手段在教学过程的应用,以期能够改善园艺专业教学效果、提升学生的行业自信感,并推动信息化教学模式在其他专业教育中的应用。