地震折射波的虚拟射线理论及其应用     

焦湘恒  王修田 《中国海洋大学学报(自然科学版)》1987,(2)

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。  相似文献   

Action of Cnoidal Waves on Vertical Walls     

Qiu Dahong  Zang Jun  Jia Ying Academician of the Chinese Academy of Sciences  Professor  the State Key Laboratory of Coastal  Offshore Engineering 《中国海洋工程》1996,(2)

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  相似文献   

斜坡提砌石护面厚度的计算     

张怀慧  李玉成 《海洋工程》2002,20(2):14-18

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  相似文献   

随机载荷下的疲劳损伤计算公式     

伍义生 《海洋工程》1994,(1)

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。  相似文献   

长江口泥沙絮凝静水沉降动力学模式的试验研究   总被引：10，自引：1，他引：10  

关许为  陈英祖 《海洋工程》1995,(1)

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。  相似文献   

高斯投影公式的机助推导     

殷海峰  白征东  程伯辉 《测绘科学》2008,33(2):7-9

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。  相似文献   

About the specification of erosion flux for soft stratified cohesive sediments     

Georges Chapalain  Y. Peter Sheng  André T. Temperville 《Mathematical Geology》1994,26(6):651-676

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.  相似文献   

Global height datum unification: a new approach in gravity potential space     

A. A. Ardalan  A. Safari 《Journal of Geodesy》2005,79(9):512-523

The problem of “global height datum unification” is solved in the gravity potential space based on: (1) high-resolution local gravity field modeling, (2) geocentric coordinates of the reference benchmark, and (3) a known value of the geoid’s potential. The high-resolution local gravity field model is derived based on a solution of the fixed-free two-boundary-value problem of the Earth’s gravity field using (a) potential difference values (from precise leveling), (b) modulus of the gravity vector (from gravimetry), (c) astronomical longitude and latitude (from geodetic astronomy and/or combination of (GNSS) Global Navigation Satellite System observations with total station measurements), (d) and satellite altimetry. Knowing the height of the reference benchmark in the national height system and its geocentric GNSS coordinates, and using the derived high-resolution local gravity field model, the gravity potential value of the zero point of the height system is computed. The difference between the derived gravity potential value of the zero point of the height system and the geoid’s potential value is computed. This potential difference gives the offset of the zero point of the height system from geoid in the “potential space”, which is transferred into “geometry space” using the transformation formula derived in this paper. The method was applied to the computation of the offset of the zero point of the Iranian height datum from the geoid’s potential value W ₀=62636855.8 m²/s². According to the geometry space computations, the height datum of Iran is 0.09 m below the geoid.  相似文献   

打桩挤土的现场试验研究及土体位移的计算公式   总被引：3，自引：1，他引：3  

王兴龙  陈磊  窦丹若 《岩土力学》2003,(Z2)

打桩挤土使周围土体发生位移,对周围其他桩及附近原有建筑物和基础设施产生破坏。本文通过典型工程打桩过程中的监测数据,运用小孔扩张理论结合回归分析方法导出了计算土体位移量的经验公式。运用该公式可定量预估挤土程度,防止意外事故的发生。  相似文献   

垂线偏差时间变化的精度估计   总被引：3，自引：0，他引：3  

丁行斌  李正心 《测绘学院学报》2003,20(1):10-13

对于利用Vening-Meinesz微分公式计算垂线偏差随时间变化的测定精度进行了初步估计。通过对地形改正项的影响、代表误差的影响、远区域重力异常的影响等3种主要误差的分析和实际估计，论证了它们对计算结果的综合影响不超过0.01″，比铅垂线的时间变化0.1″要高一个量级。因此认为重力方法在实践中是可行的。  相似文献