集中荷载作用下R.C.双向受弯约束梁斜截面抗剪强度的计算

在13根集中荷载作用下钢筋砼双向受弯约束梁斜截面抗剪试验研究的基础上，采用等效梭形截面法，将双向受弯约束梁转化为单向受弯约束梁，并推出集中荷载作用下钢筋混凝土双向受弯约束梁斜截面抗剪强度的计算方法．     

Microforms in Gravel Bed Rivers: Formation, Disintegration, and Effects on Bedload Transport

This research aims to advance current knowledge on cluster formation and evolution by tackling some of the aspects associated with cluster microtopography and the effects of clusters on bedload transport. The specific objectives of the study are (1) to identify the bed shear stress range in which clusters form and disintegrate, (2) to quantitatively describe the spacing characteristics and orientation of clusters with respect to flow characteristics, (3) to quantify the effects clusters have on the mean bedload rate, and (4) to assess the effects of clusters on the pulsating nature of bedload. In order to meet the objectives of this study, two main experimental scenarios, namely, Test Series A and B (20 experiments overall) are considered in a laboratory flume under well-controlled conditions. Series A tests are performed to address objectives (1) and (2) while Series B is designed to meet objectives (3) and (4). Results show that cluster microforms develop in uniform sediment at 1.25 to 2 times the Shields parameter of an individual particle and start disintegrating at about 2.25 times the Shields parameter. It is found that during an unsteady flow event, effects of clusters on bedload transport rate can be classified in three different phases: a sink phase where clusters absorb incoming sediment, a neutral phase where clusters do not affect bedload, and a source phase where clusters release particles. Clusters also increase the magnitude of the fluctuations in bedload transport rate, showing that clusters amplify the unsteady nature of bedload transport. A fourth-order autoregressive, autoregressive integrated moving average model is employed to describe the time series of bedload and provide a predictive formula for predicting bedload at different periods. Finally, a change-point analysis enhanced with a binary segmentation procedure is performed to identify the abrupt changes in the bedload statistic characteristics due to the effects of clusters and detect the different phases in bedload time series using probability theory. The analysis verifies the experimental findings that three phases are detected in the bedload rate time series structure, namely, sink, neutral, and source.     

ТДГ3．15万kVA主变压器经济运行分析

根据电力变压器功率损耗的分析，找到ТДГ3．15万kVA2台主变压器的功率损耗与负荷率β的函数关系，并对该2台主变压器的经济运行进行了探讨，计算出了经济运行点。     

包钢连铸结晶器液位控制系统中控制器的设计应用

本文采用FUZZY－PID复合式自适应控制器来满足冶金连铸系统中对结晶器液位控制的要求，由于在长时间的连续铸钢过程中，塞棒头部受钢水的冲刷和腐蚀，使得塞棒头部为形较大，导致塞棒位置与钢水流量的特性关系发生较大变化，而这种变化无法用确定的数学关系式来描述，用常规PID控制器不能对此变化进行有效调节。本文采用模糊控制器对此变化作出反映，通过模糊控制运算结果来调节PID控制器的放大系数Kp始终在理想的范围内，从而使控制系统达到对结晶器液位控制的要求。     

线阵CCD在安瓶三径在线自动检测分选系统中的应用

阐述了用线阵CCD检测系统通过变速扫描实现安瓶三径在线检测与控制的应用研究。文中用变速扫描方案，使在满足系统测量精度和高速的条件下，大大降低了对线阵CCD器件和扫描伺服系统性能的要求，使系统更具有实用价值。     

Repair of notched beam under dynamic load using piezoelectric patch

In this paper, the repair of a cracked beam under an external dynamic load employing the electro-mechanical characteristic of piezoelectric material to induce a local moment is presented. Conceptually, an external voltage is applied to actuate a piezoelectric patch bonded on the beam to effect closure of a crack so that the singularity at the crack tip under dynamic load may be decreased. Globally, this has the effect of altering the resonant frequency of the cracked beam towards that of the healthy beam, which is the criterion used for the repair. To demonstrate the repair methodology, a cantilever beam is used as an illustration, where the repair moment coefficient and the voltage required are mathematically derived. The relationship between repair moment coefficient, crack parameters and length of piezoelectric patch is investigated. The difference between the proposed repair criterion and an earlier published criterion for cracked beam under static load is also shown. A numerical example is used to study the effectiveness of the proposed repair methodology and its results are compared with those from 3-D finite element analyses using ABAQUS 6.4 as one means of verification.     

钻孔嵌岩灌注桩承载特性试验研究

钻孔嵌岩灌注桩已成为高层建筑较常用的基础形式之一．在南昌地区某工程中，通过对钻孔灌注桩进行静载试验，分析研究了钻孔嵌岩灌注桩的承载特性和荷载传递机理，对此类桩的侧摩阻力与端阻力的问题进行了探讨。     

不同轮压分布形式对半刚性路面结构力学响应的有限元分析

针对轮胎接地形状的不规则性和轮压分布的不均匀性,运用三维有限元方法分析了轮压在圆形均匀分布、矩形均匀分布和矩形非均匀分布3种轮载作用形式下半刚性路面结构的力学响应.计算表明,轮压作用于路面的形状和非均匀性均对沥青路面的力学响应有显著的影响,尤其是超载时,圆形均布假设和矩形均布假设均不能正确反应半刚性结构层内部的剪切指标,只有矩形非均布假设能够很好地反应.研究提出,欠载及标准轴载时,可以采用圆形均布假设进行路面结构力学响应的分析;超载时,鉴于剪切指标对轮压非均匀性分布的敏感性,建议采用矩形非均匀分布荷载形式进行路面结构力学响应的分析及模拟仿真.     

k-ary n-cube网络中跨区域适应性路由算法

针对k-ary,n-cube网络,提出一种无死锁、元活锁、负载均衡的跨区域路由算法(Quadrant Crossing Routing,QCR).算法按照分组源目的节点相对位置将网络划分路由区域,并给予这些区域不同的权重,同时设定跨区域规则,允许分组根据网络负载状态跨区域路由,这样就使得网络的流量分布更均衡.网络的负载程度由输出端口等待分组请求的时间间隔的大小决定.最后,利用OPNET对所提算法在不同流量模式下进行仿真.结果表明:相比已有的同类算法,如维序路由算法(Dimension Order Routing,DOR),Duato及GAL等,QCR表现出较好的时延、吞吐性能.     

WEB应用系统性能测试的实现

对WEB应用系统进行合理的性能测试是保证系统质量的一个重要过程。以某远程教学系统为案例,借助于测试工具Load Runner,从负载反应层面对系统性能进行验证,并对测试结果进行分析,以保证系统的合理优化。