空间刚架结构极限强度分析

本文用理想结构单元法对空间刚架结构进行了极限强度分析，理想结构单元法在于将结构分成最大可能的单元。以简单的形式归并几何非线性与材料非线性。按增量形式加载，直到达到极限强度。本文根据Ｒａｓｈｅｄ理论导出了对称的切向方程组，节省了存贮单元、改善了破坏准则的描述。算例结果与非线性有限单元法结果十分吻合。     

地震折射波的虚拟射线理论及其应用

本文提出了一种地震折射液的虚拟射线理论,根据该理论,只要已知地表层的速度,即可直接由折射波信息提取地震参数,从而可实现折射界面的反演。 文中通过实际介质模型的计算机实验结果,验证了该理论的正确性。     

Action of Cnoidal Waves on Vertical Walls

Based on the 2nd order cnoidal wave theory, the characters of shallow water standing waves and their action on vertical walls are studied in this paper. The theoretical expressions of the wave surface elevation in front of and the wave pressure on the vertical wall are obtained. In order to verify the theoretical results, model tests were made in the State Key Laboratory of Coastal and Offshore Engineering at DUT. For the wave surface elevation in front of the wall and the wave forces on the wall at the moment when the wave surface at the wall surface goes down to the bottom of the wave trough, the calculated results coincide quite well with the experimental results. For the wave forces on the wall at the moment when the wave surface at the wall surface goes up to the top of the wave crest, the theoretical expressions are modified by the experimental results. For the convenience of practical use, calculations are made for the wave conditions which usually occur in enginering practice by use of the inves     

斜坡提砌石护面厚度的计算

介绍了斜坡式防波堤砌石护面中的插砌条石和干砌块石在波浪作用下的力学图式及作用机理 ,重点给出考虑摩擦力作用时的砌石块体稳定厚度的计算公式 ,并结合工程实例验证了公式的适用性     

随机载荷下的疲劳损伤计算公式

本文推导了随机载荷下的疲劳损伤计算公式。数值计算结果表明：Ｐ．Ｈ．Ｗｉｒｓｃｈｉｎｇ给出的公式在宽带情况下与实际情况不符；Ｇ．Ｃｈａｕｄｈｕｒｙ给出的公式在窄带情况下与实际不符；本文绘出的公式不仅适合于窄带，也适合于具有各种不同带宽的宽带随机载荷。     

日本鳗鲡白仔鳗耳石中心部分的电镜扫描观察

对在１９９０年４月取自长江口的白仔鳗耳石进行扫描电镜观察,发现了耳石中心核及其外周的深暗凹槽生长轮之间存在着数个生长轮。     

长江口泥沙絮凝静水沉降动力学模式的试验研究

细颗粒泥沙在咸水中的絮凝沉降是河流泥沙向海输送过程中在河口区发生的重要现象，是河口拦门沙形成与发育的主要原因之一。本文根据室内模拟试验研究，提出长江口泥沙絮凝静水沉降的二级动力学模式，通过该式求得不同泥沙含量和盐度情况下絮凝沉降的衰减系数，半衰期和平均沉降速率等动力学参数，定量地分析泥沙含量和盐度对泥沙絮凝沉降过程的影响。     

高斯投影公式的机助推导

随着GPS应用的普及,高斯投影在测量中出现的机会越来越多。许多文献上都给出了推导过程,这个推导过程的运算量是非常大的,而且计算精度难于提高。经过研究,一种易于编程的递推公式被发现,虽然这个公式在计算量上没有减少,但是可以较好地解决精度问题。     

About the specification of erosion flux for soft stratified cohesive sediments

The present paper deals with the specification of bed erosion flux that accounts for the effects of sediment-induced stratification in the water column. Owing to difficulties in measuring the bed shear stress _b and the erosive shear strength _s, we suggest a series of methods that combine laboratory and numerical experiments. A simplified turbulent transport model that includes these effects helps to quantify _b and _s. Focusing on soft stratified beds, the present study considers erosion rate formulas of the form =_f exp {[T_b-T_s]} where is a model constant (=1 for Gularte's (1978) formula and =1/2 for Parchure's (1984) formula). First, the bed erosive strength profile _s(Z) is adjusted by forcing the turbulent transport model with measured erosion rates. Second, three procedures are suggested to determine the erosion rate formula coefficients _f and : a global procedure and two different layer-by-layer procedures. Each procedure is applied to an erosion experiment conducted in a rotating annular flume by Villaret and Paulic (1986). The use of the layer-by-layer procedure based on a least squares fitting technique provides a closer fit than the global procedure. The present study points out the complementarity of experimental and numerical approaches and also suggests possible improvements in laboratory test procedures.