A Thermodynamic Criteria for Evaluation of Heat Exchanger Performance

The concept of loss rate of available energy was introduced for evaluating heat exchanger performance. At the same time, the general expression of loss rate of available energy was obtained for heat exchangers of several typical. And NL criteria was recommended for evaluation of the loss rate of available energy of heat exchanger. Then. the influences of inlet temperatures ratio, heat capacity ratio of fluids, the number of heat transfer units and flow patterns of heat exchanger on ,VL criteria were also discussed.     

The Control Strategy for the Excitation System of Asynchronized Turbogenerators

In this paper, the excitation principle and operating characteristics ofasynchronized turbogenerators are analyzed,and adaptive tracing iterative control strategy based on state identification is proposed. In order to apply this control scheme to practice engineering, some primary elements are analyzed and presented for constituting dual-channel automatic excitation control system of asynchronized turbogenerators. Finally, the paper presents the principle structure charts about excitation control system of asynchroized turbogenerators.     

直墙拱形巷道围岩应力场分析

为得出直墙拱形巷道围岩应力分布规律,应用复变函数弹性理论推导了直墙拱形巷道围岩应力分布的解析表达式。对直墙拱形巷道边界的围岩应力和巷道水平线方向的围岩应力分布规律进行分析,并考虑直墙拱形巷道断面高宽比和侧压系数对其影响规律。研究表明：在不同巷道断面高宽比、侧压系数下,直墙拱形巷道围岩应力集中区域主要集中在直墙底部底角处、拱形顶板中点附近和底板中部3个位置。不同巷道断面高宽比下,直墙拱形巷道沿水平线的应力分布规律基本相同。侧压系数大于1时,采用巷道断面高宽比小于1较有利于巷道稳定;侧压系数小于等于1时,采用巷道断面高宽比大于1较有利于巷道稳定。     

实用型荔枝虫害诊断专家系统设计方法研究 实用型荔枝虫害诊断专家系统设计方法研究

针对大型检索表为表示的专家知识体系，研究提出了一套可重用的、实用性强的系统设计方法，建立了荔枝虫害诊断专家系统（LDS）。经生产示范应用表明：实现了人机操作界面直观、明了，降低了客户端的专业要求，提高了系统的实用性。还对系统所构造的人机界面、知识存储结构设计和控制策略给出实践示例。     

The Monitoring Measurements and Country Rock Control of NATM in Tunnel of Express Road during Construction

In this paper the author' s study on the monitoring measurement technique of NATM,the regularity and conditions of the country rock deformation are analysed based on the site measurement data in the west section of Zhongliangshan tunnel. The regression analysis of measure data for different measure lines of vavious country rock is done by the use of self-compiled CRAP program. The stability criterion for various rockmass and optimum time for primary and permanent support are provided. The conclusion available could conduct the theoretical research of NATM deeply as well as tunnel design and construction.     

TRUST REGION METHOD FOR UNCONSTRAINED OPTIMIZATION

A new trust region algorithm is proposed for solving unconstrained optimization problems. According to the quadratic approximate model of the original optimization problem,the trust region algorithm uses directions,a convex combination of the quasi-newton direction and the steepest descent direction. This algorithm with new strategy is analyzed and the global and local quadratic convergent theorems are proved. At last,the implementation and computational results of the algorithm are demonstrated.     

水稻旱作的需水规律与土壤水分调控

为了研究水稻旱作的水分调控指标和节水效果，采用单阶段旱试验方法，设置13个试验处理，每个处理重复3次，得到了旱作水稻的需水特性和规律，土壤水分、耗水量和产量三者之间的相互关系，受旱对各阶段生长发育的影响，以及不同阶段、不同程度受旱对最终产量的影响等，并求得了旱作水稻各阶段受旱的水分敏感指（系）数和水分生产函数。结果表明：受旱对产量影响最大的阶段为拔节孕穗期，抽穗灌浆期次之，分蘖期适当的水分亏缺反而有利于旱作水稻的协作发育和产量提高。     

行星摆线针轮减速机构的动力学虚拟仿真

以UG、ADAMS等三维造型及运动学、动力学分析软件为平台，利用虚拟设计技术建立了行星摆线针轮减速机构的动力学虚拟样机模型。探讨了行星摆线针轮减速机物理约束机制的实现方法，建立了虚拟样机系统的力学模型，验证了样机的动态干涉情况，并对摆线针轮减速机构进行了动力学仿真分析，最后还进行了柱销与输出轴作用力的虚拟实验分析。仿真分析结果表明，提出的摆线针轮减速机虚拟样机建模正确，有较好的可靠性和实用价值。     

工程车辆自动变速控制系统仿真与试验

对液力机械传动工程车辆遇到高强度载荷效率下降的问题进行了研究，推导了新的换挡规律。按照预先设定的经济型换挡规律，利用推导出的不同挡位下换挡点的通用公式，可将变矩器的效率限定在某一理想范围内。获取对换挡离合器执行机构的控制来达到对离合器油压的控制目的，仿真结果表明其跟踪效果良好。通过台架试验，取得了满意的效果。     

合同解除制度的比较分析——以我国《合同法》与《联合国国际货物销售合同公约》为视角

合同解除制度是合同制度的重要内容。我国《合同法》和《联合国国际货物销售合同公约》对合同解除制度都有比较详细的规定。本文试从合同解除的条件、程序及后果等方面对两者的规定进行比较分析。