A THEORETICAL ANALYSIS OF THE SPURIOUS SIDEBANDS AT THE OUTPUT OF A NEW PLL

Based on the introduction to a new type of PLL for digital frequency synthesis, this paper describes on detail the suppression of the specific spurious signals occurring at the output of the phase detector of the PLL. The result shows that the output sideband-to-carrier ratio is satisfactory.     

A TIME AND FREQUENCY DOMAIN METHOD FOR IDENTIFICATION OF PHYSICAL PARAMETERS

In this paper, a-method using the complex modal theory to identify physical parameters of system with viscous damping is discussed. A procedure is present to calculate the mass, clamping, and stiffness matrices from the measured data in time and frequency domains. The double least squares approach is used to identify modal parameters. In identification of physical parameters, the data of different measured point is used in calculation for more accurate results.     

A NEW APPROACH OF LOAD FREQUENCY DECENTRALIZED CONTROL-OPTIMIZATION OF WEIGHT MATRIX Q

As the optimization and coordination of weight matrix Q and feedback gain matrix K are taken into account, the dynamic performance of the decentralized controller designed by this method is as good as that of the optimal controller. This method can be used in the strong or weak coupled systems, and various controllers can be designed according to the demand. An example is given to prove the validity and advantage of this method.     

A NEW IDEA FOR PROTECTING ROCK AROUND UNDERGROUND EXCAVATION-STUDIES OF SOFTENING SURROUNDING ROCK METHOD

This paper advances a new idea for protecting rock around underground excavation, based on the analyese of movements of surrounding rock,then studies the sloting in surrounding rock-a kind of softening technique for surrounding rock by means of BEM and modle tests. It is proved that this method is useful and effective.     

A NEW PWM METHOD-AVERAGE VALUE PWM

In this paper, a new PWM method-average value PWM is presented. This method has been compared with other PWM methods and realized by using a micro - processor-controlled GTR inverter. Some experimental results and discussions for them have been given.     

A NEW METHOD FOR DESIGN OF PSS PARAMETERS

The eigenvalue sensitivity methods is very useful not only in analysis of electric power system stability but also in design of the controllers. In this paper a new optimal method is proposed to design the parameters of PSS. Using this method the PSS is designed for a single machine-infinite bus system, and the results of digital simulation show that this method is very effective and useful.     

测定小麦种子饱满度的新方法

通过测定55个小麦品种最大鲜籽粒体积 V_D 和成熟时晒干籽粒最大吸涨体积 V_S,经回归分析得理论最大鲜籽粒体积 V_D=0.0952+1.05268V_S,由 V_D 与V_S比值的均数得 V_D=1.0540V_S。在实验室里测定出 V_S,代入上述任一公式,均可获     

A NEW METHOD FOR AMELIORATING INDOOR THERMAL ENVIRONMENT BY DEHUMIDIFYING

The climate in the region of the Yangtze River is sultry in summer and wet and cold in winter. The conventional building measures are shading in summer and insulating in winter,which have heen gotten some effects. Becasue the sultry,wet and cold sensation still affect, the indoor thermal environment can not get an ideal improvement. This paper shows that the new method by dehumidifying is the most effective and the most economic.     

FREQUENCY CALCULATION OF SPACE FRAME STRUCTURE BY A WAVEFRONT AND AN ITERATED POWER METHOD

In this paper,the frequency of space frame structure is obtained by a wavefront and an iterated power method.The computer internal storage is greatly saved.The solution so obtalned is quite in agreement with the finite solution.     

新型农户专用粮仓储粮品质变化研究

采用PVC软体仓作为新型农户专用仓,小麦在10个月储存期内水分含量变化≤0.6%,与原始水分无显著差异。小麦容重损失率均值为1.96%,干容重损失率均值2.1%,虫蚀粒率≤0.3%,霉变粒率≤0.1%,面筋吸水率变化率均值9.4%,平均储粮损失率为0.506%,干物质平均损失率为0.318%。由此可见PVC仓具有良好的防潮、防鼠、密闭、隔热等性能,能够有效地减少农户储粮过程中由粮食生虫、发热霉变、鼠咬等因素引起的储粮损失,起到减损保质的效果。     

A SFG METHOD FOR RELIABILITY EVALUATION OF HVDC SYSTEMS

Steady-state probability, frequency and duration are the three main indices in reliability evaluation of the HVDC systems. Generally, they are solved by numerical methods. Their topolgical formulaes are derived by using the basic theory of ccates graph and considering conditions for some particularity of state-space in this paper. A set of generalised formulaes can be applied to obtain these indices expression about reliability parameters of components. Finally,an example is given to illustrate and verify this method.     

关于储藏期内小麦储存品质指标检测频次的研究

结合每年3月份和9月份品质检测,选择5个不同储藏年限的小麦仓房在同一年内两次测定其储存品质指标,通过横向比较,探究其品质变化快慢与检测频次的关系;另选择同一收获年度的2个仓房跟踪测定其5年内小麦储存品质指标,通过纵向比较,探究其品质变化与检测频次的关系;并提出合理的检测频次,以期保证掌握储备粮品质变化的同时能降低储粮成本,节约资源。     

DECENTRALIZED LOAD FREQUENCY CONTROL OF HYDROTHERMAL POWER SYSTEM

The decentralized load frequency control (LFC) of hydrothermal power system is designed with overlapping information set. The conflicts among the generation regulation constraint (GRC) ,the process of reheat steam turbines,the governor dead-band effects,and the dynamic response of LFC have been coordinated.     

THE REAL RESISTIVE MODEL FOR FREQUENCY -DOMAIN ANALYSIS

A new model for frequency - domain analysis - the real resistive model which is based on Complex Network Theory is proposed in this paper. The network equations formed with the new model without contain complex numbers because there are only sources and resirtive elements in the model. A CAA algorithm for frequency analysis by using the new model is also given. It is shown that the trouble with the complex operation in the traditional algorithm has been avoided. The algorithm presented in this paper is simple and convenient,hence it is easy to popularize.     

LOAD FREQUENCY CONTROL USING DECOMPOSED DISCRETE MODELS

Decomposed discrete models, can be used to design load frequency' controllers in multi-area power systems.Considering the exchanging real power in tie-lines as a measurable disturbance, the multi-area power system is decomposed into several subsystems.On the basis of generalized minimum variance control principles, an expanded control rule is induced. Using discrete models, the proposed method greatly decreases the number of varialles in be measured and simplifies the control system. The method is illustrated with a two-area power system example and its simulation Jesuits.     

THE FREQUENCY DOMAIN DISCRIMINATIONS OF SEVERAL VIBRATIONS ON THE TURBOGENERATOR

The frequency spectrum analyses of several vibration on No. 4 Unit in a power plant are made and the experience of the future failure diagnosis on turbogenerator is collected in this paper.     

A NEW METHOD FOR DETERMINING THE INITIAL CONDITIONS OF NETWORKS WITH DEGENERATE CUT-SETS

This paper suggests a new method for determing theinitial condittons of networks with degenerate cut-sets,which is strictlybased on the physical relationship between currents and magnetic fieldcorresponding witth them.This method first sets up a reasonable magne-tic network for solution,and then finds out the transfer linkages byexciting sources in this network,so that the initial conditions can befinally determined.Consequently,this method is simple,normalizable,having clear and correct physical concept,and advantageous to solvingcomplex networks.     

射频识别技术在粮食供应链体系中的应用研究

将射频识别技术应用于粮食供应链系统中,力求实现供应链体系运行的快速与高效.介绍了射频识别技术的基本原理及特点,在此基础上构建了粮食供应链管理系统的系统模型,并给出了粮食供应链管理系统的系统架构,以及基于射频识别技术的实现过程,最后对现存的问题和相应对策进行了概述.     

A NEW METHOD FOR THE STATIC MEASUREMENT AND CALCULATION OF PARAMETERS OF SYNCHRONOUS MACHINES

This paper presents and improved static measurement method for the parameter measurement and calculation of synchronous. By four static-tests of this method all the parameters in the d-axis equivalent circuits of synchronous machines can be determined, and transient and subtransient parameters are calculated. Testing results proves that this method is available in indusirail testing.