On the Water Depth in the Breach during a Partial Dam Break

Theoretical and experimental data which make it possible to find the flow-rate, momentum and energy of the fluid that enters the lower pool after a discontinuity breakdown (dam break) in a rectangular channel with an even bottom, a step (sharp downstream rise in the bottom), a shelf (sharp drop in the bottom), and a threshold on the bottom are presented.     

铝合金材料剪切断裂实验分析

金属材料受载作用发生断裂，断裂面形式有拉断，剪断和拉剪混合型，由于剪断过程中塑性变形较为复杂，问题的研究难度大，观点争论多，本文对LY12－M铝合金材料复合型平面应变载荷状态下的几种断裂试验结果作了分析，认为在II型，近II型时发生的剪切型断裂，启裂点在裂尖附近应力三维度取最大值处，剪断的开裂方向则与启裂点上最大剪应力方向有关，同时对LC9R超强铝合金作常规破坏试验，该材料在拉伸，扭转与压缩试验时均呈剪切断裂，断裂面沿最大剪应力方位，破坏剪应力随试件应力三维度的降低而增大，综合分析试验结果得到了一些有用的结论。     

DDA与FEM耦合法在分缝重力坝非线性分析中的应用

混凝土重力坝一般设有数条纵缝。纵缝使坝体的连续性遭到破坏，一般的有限单元法很难处理这样的不连续变形问题。本文首先阐述了DDA(Discontinuous Deformation Analysis)与FEM(Finite Element Method)耦合算法的原理，然后采用作者自行研制的DDA与FEM耦合法程序对一实际重力坝进行了详细的计算分析。重点讨论了纵缝的不同设置形式和缝宽大小对坝体变形和应力分布、坝底面接触应力分布以及坝基面应力分布的影响，为工程设计提供依据。     

残余应力对压力容器破坏模式的影响分析

破前漏(简称LBB)是压力容器、核电站设备结构设计与评价中的一个重要准则.表面裂纹准静态扩展的几何形貌变化规律的预测是破前漏(LBB)评判十分重要的课题之一.本文对特定焊接残余应力场加载作用下,含三维表面裂纹的压力容器模型,用有限元软件(ABAQUS)进行了表面裂纹准静态扩展模拟计算,得到在此残余应力场作用下应力强度因子沿裂纹前缘的分布规律.结合外载引起的应力强度因子,就可以判别裂纹的扩展形貌,从而判断结构是否满足LBB要求.     

Thermo-oxidative degradation of Nylon 1010 films: Colorimetric evaluation and its correlation with material properties

The thermo-oxidative aging behaviors of Nylon 1010 films were studied by various analytical methods, such as measuring the chromaticity, relative viscosity, carbonyl index, UV absorbance at 280 nm and elongation at break of the aged films. The thermo-oxidative aging plots of the results obtained via these various methods at different temperatures are subjected to the time-temperature superposition analysis, which are found to be well superposed. The b^* values are used as X axis and the other results, i.e., relative viscosity, carbonyl index, UV absorbance at 280 nm and elongation at break, are used as Y axis, respectively. The relationship between the b^* values and the other results is obtained, from which we can derive the changes of physical and chemical properties at different b^* values. Since the b^* values can be quickly determined by using a portable spectrophotometer, the on-line evaluation of the thermo-oxidative aging of Nylon 1010 can be realized.     

水平地震时斜面水坝受到的非线性动水压力的全过程的解析解

本文给出在非线性Ｒａｙｌｅｉｇｈ阻尼作用下，由水平地震激发的水库内动水压力变化全过程的解析解：在激发初期其幅值较小，可用小参数法使控制方程线性化，从而求得各阶渐近控制方程的解析解；当动水压力的幅值增大到小参数展开不适用时，用ｖａｎ ｄｅｒｐｏｌ法求得非线性控制方程的渐近解，从而显示了动水压力的幅值从有序变化到发生突然跳跃的多值性的非线性本质。     

龙井水库大坝的渗流和稳定分析

本文以龙井水库大坝为例,运用有限单元法对粘土心墙坝的渗流进行分析计算,同时运用瑞典圆弧滑动法和简化Bishop法对粘土心墙坝的坝体稳定进行分析计算,在此基础上对水库大坝进行了渗流安全评价和稳定性安全评价。     

淮河大堤老应段土体蠕变特性研究及工程应用

本文依据工程需要, 采取淮河大堤老应段的原状和扰动土样, 在室内对堤体及堤基土的剪切蠕变和拉伸蠕变特性进行了试验研究。粘土的蠕变剪切强度远低于瞬时剪切强度, Ｃ∞值仅是Ｃ值的４０％左右;相同含水条件下粘土的长时抗拉强度大于瞬时抗拉强度, 长时拉伸应变量远大于瞬时拉伸应变量, 约为２倍。     

A Dynamic Supplier Selection and Inventory Management Model for a Serial Supply Chain with a Novel Supplier Price Break Scheme and Flexible Time Periods

A new supplier price break and discount scheme taking into account order frequency and lead time is introduced and incorporated into an integrated inventory planning model for a serial supply chain that minimizes the overall incurred cost including procurement, inventory holding, production, and transportation. A mixed-integer linear programming (MILP) formulation is presented addressing this multi-period, multi-supplier, and multi-stage problem with predetermined time-varying demand for the case of a single product. Then, the length of the time period is considered as a variable. A new MILP formulation is derived when each period of the model is split into multiple sub-periods, and under certain conditions, it is proved that the optimal solution and objective value of the original model form a feasible solution and an upper bound for the derived model. In a numerical example, three scenarios of the derived model are solved where the number of sub-period is set to 2, 3, and 4. The results further show the decrease of the optimal objective value as the length of the time period is shortened. Sufficient evidence demonstrates that the length of the time period has a significant influence on supplier selection, lot sizing allocation, and inventory planning decisions. This poses the necessity of the selection of appropriate length of a time period, considering the trade-off between model complexity and cost savings.     

坝前淤泥土与新填坝体接触面抗剪强度试验研究及工程应用

坝前淤泥面与新填筑坝体接触面是"坝前淤泥面加坝"技术的薄弱环节。为了探究不同工况下淤泥坝基、新填筑坝体,以及淤泥土-新填土接触面的剪切强度特性,以宁夏南部山区西吉县南川水库坝前淤泥面加坝工程为研究对象,通过常规应变式直剪仪、改进常规应变式直剪仪分别进行剪切试验,分析了淤泥土含水率和压实度变化时,淤泥土、新填土、淤泥土-新填土接触界面的抗剪强度、黏聚力、内摩擦角的变化规律。试验结果表明:新填土抗剪强度最大,不同工况下淤泥土-新填土接触界面的抗剪强度介于淤泥土和新填土的抗剪强度之间;淤泥土含水率在12%~16%之间存在最优含水率,超过该含水率后,淤泥土及淤泥土-新填土接触界面之间的抗剪强度均显著降低;当淤泥土含水率从8%增加至12%、16%时,黏聚力减小8%左右后迅速减小至22%,具有明显的阶段性,而淤泥土-新填土接触界面的黏聚力呈现先增加后减小的趋势;当含水率相同时,随着压实度的增加,淤泥土、淤泥土-新填土接触面的黏聚力、内摩擦角总体呈增大趋势。最后根据试验结果对"坝前淤泥面加坝"工法的工程应用提出了相关建议。