海浪谱高阶谱矩的计算

分析了海浪谱高阶谱矩不存在的原因。在Ｇｌａｚｍａｎ研究结果的基础上计算了目前工程上常用的ＰＭ谱和ＪＯＮＳＷＡＰ谱的０阶到８阶的谱矩值,以方便实际工程的应用。     

Third order wave force on axisymmetric bodies

The third order triple-frequency wave load on fixed axisymmetric bodies by monochromatic waves is considered within the frame of potential theory. Waves are assumed to be weak non-linearity and a perturbation method is used to expand velocity potentials and wave loadings into series according to a wave steepness of kA. Integral equation method is used to compute velocity potentials up to second order in wave steepness. The third order triple-frequency wave loads are computed by an indirect method and an efficient method is applied to form the third order forcing term on the free surface quickly. The method can be used to compute third order triple-frequency surge force, heave force and pitch moment on any revolution bodies with vertical axes. The comparison with Malenica and Molin's results is made on surge force on a uniform cylinder, and comparison with experimental results is made on third order surge force, heave force and pitch moment on a truncated cylinder. More numerical computations are carried out for third order forces and moments on a uniform cylinder, truncated cylinders and a hemisphere.     

正交各向异性介质中地震记录的有限差分数值模拟

本文首先介绍了正交各向异性介质弹性波动方程的建立过程,然后讨论了高阶有限差分算法的实现原理、算法的稳定性和收敛性以及吸收边界条件的选取,并对正交各向异性介质作了正演模拟。通过波场快照、共炮点地震记录和ＶＳＰ模拟记录等正演分析,结果表明该算法在模拟各向异性介质中弹性波的传播是有效的     

大炮检距优化6次NMO校正

常规2次NMO动校是假定炮检距与深度比值小，并且射线为直线。计算的旅行时精度随着炮检距与深度比值的增加而大大降低，NMO校正能通过高次(4次、6次)项逼近得到改善。因此，在大炮检距情况下，若直接忽略高次项，则计算旅行时会产生很大误差。所以在大炮检距条件下进行2次NMO近似不利于速度分析、AVO研究和CMP道集动校叠加。笔者引入了一个更精确的旅行时近似计算，称为优化6次NMO动校方程式，因为截断误差较小，故其精确度高于泰勒6次展开式。通过模型和实际数据的试验，证明大炮检距优化6次NMO方程精度高，更具有实际应用意义。     

结构-地基动力相互作用的时域模型

结构-地基动力相互作用是结构地震响应分析及安全评估的一个非常重要课题。基于比例边界有限元法,提出了一种新颖的结构-地基动力相互作用的时域模型,即采用比例边界有限元子域模拟近场有限域部分,采用高阶透射边界模拟远场无限域部分。通过采用连分式展开和引入辅助变量,有限域的动力方程采用高阶的静力刚度矩阵和质量矩阵表示。高阶透射边界精确满足无限远处的辐射边界条件,具有全局精确、时间局部和收敛速度快等优点。它是基于改进的连分式法求解无限域动力刚度矩阵而建立的,在时域里表示为一阶常微分方程组。通过联立有限域和无限域的运动方程,建立了结构-地基相互作用的标准动力学方程,采用Newmark法可直接求解。3个算例结果表明,该算法在时域里比黏弹性边界更精确、有效。     

The Growth and Location of High Order Services in the Canadian Urban System, 1971–1991

In spite of the considerable economic importance of high order (intermediate demand) services, research on the growth and location of these activities has remained at a fairly aggregate level. The behavior of the individual elements of this group has rarely been documented in detail. In this paper, we seek to determine if individual high order service activities are becoming spatially more concentrated or dispersed across the Canadian urban system, and to determine if differential rates of growth may be observed by region and by urban size category. These issues are of considerable importance in the ongoing debate concerning the impact of the tertiarization of the economy on uneven spatial development. We examine the performance and location of 17 individual high order service activities over a set of 152 Canadian urban areas with populations greater than 10,000 inhabitants. Most of these activities are highly concentrated in a small number of very large urban areas, and their level of concentration declined only very slightly over the period 1971–1991. We conclude with an examination of the factors underlying the geographic concentration of high order services at the upper end of the urban hierarchy.     

河南省城市职能结构的有序推进

文章首先根据河南城市的产业结构和行业区位熵将河南城市进行职能类型的划分；然后对此进行分析并找出河南城市职能结构存在的问题；最后结合国际、国内形势提出了河南省城市职能结构有序推进的对策。     

Syracuse,sidewalks, and snow: the slippery realities of public space

This article addresses sidewalks as particular kinds of public spaces. Sidewalks of residential areas have been understudied; debates have tended to concentrate on pedestrian flows in commercial districts. By discussing the snowy sidewalks of Syracuse, New York, this article asks how sidewalks appear in law, and how responsibility for sidewalks is divided between governments and property owners. According to law and ordinances, sidewalks are responsibility of adjacent property owners. Unofficial monitoring has turned property owners’ sidewalk responsibilities away from questions of liability to questions of morality. Sidewalks evince a moral order, where questions concern not only pedestrian flows or laws, but also attitudes of others. A snowy sidewalk appears as a contested moral order, whose publicity is questionable because of the sidewalk’s reliance on private responsibility and policing. In the end, then, this article provides insights into how laws concerning public space are both maintained and questioned in everyday practices, and how the regulatory systems advance—or hinder—the publicity of public spaces like sidewalks.     

地勘企业内部控制监督机制探索

面对各式突出的市场经济秩序问题,迫切需要进一步强化地勘企业内部控制,借助内部控制的牵制机制,约束和控制企业内部发生的各种有悖于市场经济原则和精神的行为,通过各种治本式的监督检查,维持良好的市场经济秩序,提高地勘企业的市场竞争力。