如何看待我国民营上市公司EVA与MVA的反差问题

通过对2001年EVA与MVA反差最大的20家民营企业的统计数据进行了相关分析与因子分析,提出使用第一主成分作为投机炒作的度量,弟二主成分反映了股本与业绩的背离程度,并对2001年EVA与MVA反差最大的20家企业进行分析并排序。     

Sexual Selection and Economic Positioning

Synopsis In their recent survey of Darwinian aesthetics, Grammer et al. (2003) note the surprising lack of a connection between studies related to human beauty and the theory of sexual selection. Understanding this missing link sheds new light on recent research that indicates positional concerns Pingle & Mitchell 2002, Solnick & Hemenway 1998, are important factors in the decision-making process. Integrating the theory of sexual selection into the decision framework found in economics makes it possible to explain why individuals are potentially willing to accept less, as long as it places them in a superior position relative to others.     

含水生植物河道曼宁糙率系数的试验研究

水生植物是河流生态系统的重要组成部分,但水生植物的存在使得水流阻力增加,河道行洪能力降低,开展含水生植物河道曼宁糙率系数的研究,对河流生态综合治理具有重要意义。本文基于对含淹没柔性水生植物水流的室内水槽系列试验和量纲分析理论,分析了植物挺立度、相对淹没高度及相对密植度对河道曼宁糙率的影响,给出了淹没状态下含柔性水生植物河道的通用等效曼宁糙率系数经验公式。     

一种采用电磁带隙结构地板的微带八木天线

提出了一种采用二维电磁带隙结构地板为反射器的微带八木天线。对所构造电磁带隙 结构的电磁传输特性进行了研究,通过HFSS仿真和优化,使所设计天线的谐振频率落在电磁 带隙地板阻带范围之内,有效地提高了天线的增益和阻抗带宽。实测结果表明,在23～ 2.75 GHz频率范围,所设计天线的回波损耗S11≤-10 dB,其阻抗相对带 宽为18%,最大辐射方向增益达10.1 dBi,而相同结构但采用普通金属地板为反射器的 对比天线,其阻抗相对带宽为12%,增益为8 dBi。研究结论对平面、高增益天 线的设计具有很好的参考价值。     

Minimal Entropy Martingale Measures of Jump Type Price Processes in Incomplete Assets Markets

We consider the incomplete assets market and assume that the market has no-arbitrage. Then there are many equivalent martingale measures associated with the market. Among them, a probability measure which minimizes the relative entropy with respect to the original probability measure P, has a special importance. Such a measure is called the minimal entropy martingale measure (MEMM). In a previous paper, we have proved the existence theorem of the MEMM for the price processes given in the form of the diffusion type stochastic differential equation. In this article we discuss the MEMM of the jump type price processes, or especially of the log Lévy processes, and we give the explicit form of MEMM.     

Experimental and theoretical study of density jumps on smooth and rough beds

Hydraulic jumps in density currents are technically referred to density jumps. These jumps significantly influence the dynamic and quality characteristics of the gravity currents. The density jump is studied theoretically and experimentally in this study by considering the bed roughness. Experiments were performed in a rectangular laboratory flume (0.4 m width; 0.9 m depth; 8.3 m length). Four rough beds comprised of closely packed gravel particles glued onto the horizontal part of the bed were examined. For both smooth and rough beds, a simple relationship was obtained for estimating the conjugate depth ratio as a function of the relative roughness and the upstream densimetric Froude number. The conjugate depth ratio was found to decrease with increasing relative roughness. The results also indicated that, if the entrainment ratio is specified, the minimum value of the upstream densimetric Froude number increases with increasing relative bed roughness. An equation for calculating the maximum possible value of the relative roughness was also determined. The spatial development of the density current for smooth beds was analysed in both super‐critical and sub‐critical flow regimes. Good similarity collapses of velocity and concentration profiles were obtained for the super‐critical section just upstream of the jump. The concentration distributions located just downstream of the jump, however, exhibited a large scattering of measured data, especially near the bed. It was found that this scattering decreases with the distance from the end of the jump. The results of the experimental runs also indicated that, at a distance about nine times the post‐jump current thickness from the end of the jump, the non‐dimensional vertical profile of mean velocity has a shape similar to that at the pre‐jump section. A new reliable relationship was also proposed for calculating the local velocity inside both the wall and jet regions.     

Link16数据链导航功能实现与改进

基于同步的相对导航与精确定位技术是Link16数据链运行的关键。针对国内文献对该 技术介绍较少的情况,分析了相对导航的基本原理,研究了利用往返计时报文实现精确同步 的方法和步骤,建立了相对导航解算方程以及相对栅格与地理栅格坐标之间的数据转换模型 ,最后提出了一种用GPS/IMU数据融合和卡尔曼滤波方法提高导航精度的方案。应用结果表 明,该方案能显著提高数据链的导航精度。     

水轮机固定导叶与活动导叶周向相对位置的优化计算

基于无粘－边界层选代的计算模型，以水轮机导水机构的水力损失为目标函数，对固定导叶与活动导叶的周向相对位置进行了优化计算．与有关实验结果的定性比较表明本文的计算结果是合理的．     

新股投资实证分析

本文以2002年7月初至2003年6月底一年间在沪市首次发行上市的56只新股为样本,运用灰色关联度分析方法对影响新股初始收益率的各因素进行了分析,并对初始收益率与新股短中期收益率关系进行了研究。     

深基坑中土层锚杆工作性状研究

Rock-Soil Anchorage is an important branch of geotechnical engineering. The basic Theory of stucture which depends on shearing strength of stratum around anchorage,or keeping the stabilisation of excav...