NUMERICAL STUDY OF FLOW AND HEAT TRANSFER IN AN INCLINED RECTANGULAR FIN GROOVE

Flow and heat transfer are numerically studied in a rectangular fin groove when the fin base is heated with contsant temperature. Rayleigh number, inclination , aspect ratio, thick ness and conductivity of the fin are systematically changed to examine their effects. Five flow patterns are found, local and average characteristics are given, and the mechanism of heat transfer is discussed. The results can be used as a reference for fin designs.     

土壤溶质运移—双曲型偏微分方程数值解及条件

我国北方沉积平原盐渍化土壤中的溶质运移过程,土壤吸附作用与不动水体的影响不允忽视,本文针对盐渍化土壤溶质动态模型—双曲型偏微分控制方程,给出在考虑土壤吸附作用与不动水体影响下的(1)Bresler 对时间导数取高次近似的差分法;(2)二次迎风隐式差分法;()特征—有限元法等3种数值解法及比较研究与应用条件,可供灌区土壤溶质动态监测与预报模似应用。     

Numerical Simulation of Laminar Mixed Convection Heat Transfer in Vertical Narrow Rrectangular Channels

Using N-S function, and transforming the gravity item to temperature and differential pressure related items, the authors simulate the mixed convection heat transfer in vertical narrow rectangular channels. The results reveal that intense chimney effect exists in cross-section of the whole field and nearby the wall of the channel, When flow is laminar, the velocity of main flow will be decreased, disturbing nearby the heating wall is strengthened, and the convection heat transfer of vertical narrow rectangular channel is enhanced. It also can destroy the uniformity of the heat transfer coefficient distribution. Considering the reliability of equipment, this kind of convection pattern only can be used in low heat flux. The buoyancy-influencing model putted forward can predict mixed convection heat transfer, and also can be used to simulate the turbulent mixed-convection heat transfer problem.     

一种考虑剪切变形影响的矩形板弯曲单元

用单位宽纵横向条带法构造了矩形板弯曲单元的位移模式，并假定横向剪切应变在单元内线性变化，由此推导出了一个具有２０个自由度的矩形板弯曲单元计算殂式，此方法满足了单元边界Ｃ＾１连续条件，克服了“剪切自锁”，可用于大型板系结构的计算。     

MapGIS明码文件的获取和在坐标转换中的应用研究

MapGIS是我国自主研发的大型地理信息系统软件平台,具有数字制图、空间分析、数据库管理功能,而且MapGIS还支持二次开发。MapGIS有两种数据格式,分别是加密数据文件和明码文件。明码文件可以通过MapGIS平台打开编辑,还可以通过txt、word等文件格式打开、浏览、编辑,这样为MapGIS数据文件的修改提供了多种途径。首先介绍了MapGIS中明码文件的基本特点,并列出了点、线、区、网文件的明码文件的逻辑结构和结构里面包含的信息;然后,重点介绍如何利用点、线、面、区加密文件获取明码文件和将明码文件转换成点、线、面、区加密文件,以及如何利用明码文件在坐标转换中实现平面直角坐标转经纬度坐标。     

基于概率的单点腐蚀管道极限内压分析

为了研究单点腐蚀海底管道的极限内压,评估管道的剩余强度,保证管道安全运行,基于前人的研究成果,提出了简化的无限长腐蚀管道极限内压计算公式,并验证了公式的准确性。同时,通过修正将简化的无限长腐蚀管道极限内压公式扩展应用到单点矩形腐蚀管道,并利用以往试验数据对扩展公式进行了验证。结合概率方法,在工程常用的95％保证率下对单点矩形腐蚀管道极限内压进行分析,提出上下边界值。结果表明：所提出的简化公式可以很好地对无限长腐蚀管道极限内压进行预测,同时扩展公式对试验结果的拟合较好,而基于概率得到的上下边界值可以作为单点腐蚀管道极限内压控制的阈值。研究成果具有重要的工程参考价值。（图5,表1,参18）     

Experimental Study on Plannar Representative Connections Used in Obliquely Crossing Lattice of One Super Highrise Building

One Super Highrise Building is adopted to a new structural pattern of a reinforced concrete core tube enclosed by an outer lattice tube made of obliquely crossing concrete filled rectangular steel tubular columns.In order to understand the stress state of plannar representative connections used in obliquely crossing lattice and verify the rationality of the details,two 1:3 scale models were respectively applied symmetrical and asymmetrical axial force,and experiment processes were numerical simulated by ABAQUS.The results indicate that the connections are validated to meet the design requirement of the building,with sufficient loading capacity.     

直角坐标红花采摘机器人的设计与试验

针对红花采摘仍以人工采摘为主、采摘效率低下、费时费力等问题,结合红花物理生长特性及红花种植模式设计了一种直角坐标红花采摘机器人.对直角坐标采摘系统进行参数计算,确定直角坐标采摘系统X轴总长为900 mm,Y轴总长为700 mm,Z轴的行程范围为698 mm.由静力学仿真试验可知:在采摘过程中应用普通碳钢应变最小为6.5...     

Modelling the effect of crop and weed on herbicide efficacy in wheat

Recommended field application rates of herbicides have to give effective weed control in every situation and are, thus, often higher than that required for specific fields. An understanding of the interaction between crop:weed competition and herbicide dose may, in many cases, allow herbicide application rates to be reduced, important both environmentally and economically. We have developed a model of the interaction between crop:weed competition and herbicide dose, using an empirical model of the relationship between crop yield and weed biomass (related to weed density), and an empirical model of the relationship between weed biomass and herbicide dose. The combined model predicts crop yield, given herbicide dose and weed biomass at an interim assessment date. These crop yield loss predictions may be used to quantify the herbicide dose required to restrict yield loss to a given percentage. Parameters of the model were estimated and the model tested, using results from experiments, which used cultivated oats ( Avena sativa ) or oilseed rape ( Brassica napus ) as model weeds in a crop of winter wheat ( Triticum aestivum ).For the crop:weed:herbicide combinations investigated there was little increase in crop yield for herbicide dose rates above 20% of recommended field rates, in broad agreement with the model predictions. There may still be potential for further reduction below this level on economic grounds; the model could be used to estimate the `break-even' herbicide dose.     

新型方钢管混凝土柱-钢梁节点的试验与非线性有限元分析

介绍了新型方钢管混凝土柱与钢梁节点在低周反复荷载作用下的试验结果,分析了内填混凝土、加劲肋长度和梁柱相对尺寸等对节点抗震性能的影响.试验结果表明:各试件实测滞回曲线比较饱满,具有良好的耗能性能.运用ANSYS8.0对各节点试件在低周反复荷载作用下的滞回性能进行非线性模拟计算,分析内填混凝土、加劲肋长度等因素对节点受力性能的影响,结果表明:内填混凝土和加劲肋长度对节点受力性能的影响较大,有限元所得的骨架曲线与实测曲线吻合较好.