移动自组网中非完全信息节点风险评估

移动自组网是一种无中心、自组织以及多跳的无线网络,能否有效可靠地对通信节点进行风险评估是保障节点高质量通信的重要因素.当前基于可信度或是信誉的评估方法对评估样本都有特殊的要求,对评估对象提出种种假设,无法辨别间接样本的恶意推荐问题,在实际移动自组网中各个节点尤其是恶意节点对外暴漏的信息往往偏少,样本数量有限,无法明确判断其状态,大部分是非完全信息,从而导致评估结果缺乏客观性与可靠性.文中提出采用灰色系统理论描述通信节点非完全信息状态,根据灰类白化以及灰色聚类思想进行节点风险评估.方案针对自组网络通信需求对节点行为进行多关键属性划分,采用味集群方法收集原始样本,避免恶意推荐;将难以用数值精确刻画的关键属性以白化权函数量化,引入灰聚类的概念和计算方法,将实体的通信风险水平定义为实体关键属性值序列针对各评估灰类的聚类评估值,从而得到该实体通信风险水平的相对参考值.分析与实际计算表明该方法是一种适合移动自组网中非完全信息节点风险评估的有效方法.     

用水信用与风险管理系统

系统采用Oracle数据库作为开发平台,VB.net为开发工具研制而成。系统借鉴银行和电力企业信用等级评价的规则,结合水司水费收缴的历史纪录及各客户的实际情况,运用自动采集程序,从原有的营销系统和财务系统自动录入数据,再通过优化的模糊概率、神经网络程序,对用户进行交纳水费信用等级评定,建立客户交纳水费风险预警机制。     

Editorial

Abstract

Defining and measuring sustainability is a major challenge. This article argues these limitations need not stop us from trying to identify and value the possible impacts of what we are doing, or are thinking about doing, over time periods much longer than the lives of our investments, or even of the lives of those of us living today. Sustainability is a relative concept that must be applied in an environment undergoing multiple changes, changes that are occurring over different temporal and spatial scales. We depend on our water resource systems for our survival and welfare. Yet no one expects them to be restored to, or survive in, their most productive pristine states in the face of increasing development pressures for land in their watersheds and for water in their streams, rivers, lakes, and aquifers. A continuing task of water resource planners and managers is to identify the multiple impacts and tradeoffs resulting from what we who are living today may wish to do for ourselves and our immediate children and what we can only guess our yet-to-be-born descendants may wish us to do, or not do, for them in some distant future. This task must involve professionals from other disciplines in a context much broader than just water management. Once these impacts and tradeoffs are identified, it is then up to the political process to make choices when they are in conflict. All of us need to be a part of this decision-making process.     

Robust quantification of the exposure to operational risk: Bringing economic sense to economic capital

Operational risk is commonly analyzed in terms of the distribution of aggregate yearly losses. Risk measures can then be computed as statistics of this distribution that focus on the region of extreme losses. Assuming independence among the operational risk events and between the likelihood that they occur and their magnitude, separate models are made for the frequency and for the severity of the losses. These are then combined to estimate the distribution of aggregate losses. While the detailed form of the frequency distribution does not significantly affect the risk analysis, the choice of model for the severity often has a significant impact on operational risk measures. For heavy-tailed distributions these measures are dominated by extreme losses, whose probability cannot be reliably extrapolated from the available data. With limited empirical evidence, it is difficult to distinguish among alternative models that produce very different values of the risk measures. Furthermore, the estimates obtained can be unstable and overly sensitive to the presence or absence of single extreme events. Setting a bound on the maximum amount that can be lost in a single event reduces the dependence on the distributional assumptions and improves the robustness and stability of the risk measures, while preserving their sensitivity to changes in the risk profile. This bound should be determined by expert assessment on the basis of economic arguments and validated by the regulator, so that it can be used as a control parameter in the risk analysis.     

国债市场的流动性套利及其实证检验

提出了一种在保持一定流动性风险的情况下构建国债套利组合的方法,应用线性规划技术,将国债的持有期风险因素引入到约束条件中,进而求解出实现最大期初套利的国债投资组合。通过对我国上交所25种债券的实证检验,发现套利收益与组合的持有期风险成正比,与流动性指标成反比,这证明了在考虑债券流动性风险的情况下,进行债券套利操作不一定会带来可观的收益。     

浅析贝塔精确度与证券投资风险的关系

本文通过选取我国证劵市场上沪市的50只权重股,将所选样本数据分为两个时期,利用回归分析的方法,对股票不同时期历史贝塔的关联性做了实证研究。结果表明,较大投资组合的贝塔包含了较多的这一组合的未来贝塔信息,单个证劵贝塔关于未来贝塔的信息则要少得多;在预测未来贝塔的能力方面,组合的历史贝塔要比单个证劵的历史贝塔强一些。因此,在理论上,股票组合的投资风险低于单个股票的投资风险,这和我们实际操作过程中的风险分散分担机制也是一致的。     

我国企业保险体系的若干问题探析

本文总结并分析了我国企业保险体系中存在的若干问题，并结合我国经济体制改革的新形势，提出了如何解决这些问题，完善企业保险工作的构想。     

A contribution to the development of strategic control and planning instruments: An acquisition case study

The present paper is part of the efforts made by the authors in recent years to develop strategic control and planning instruments in corporations using OR‐techniques like system dynamics, control theory, and group multicriteria decision aid. A more general framework called ‘adaptive control methodology’ (ACM) combines all these techniques. It has been presented in several papers. The objective of the present analysis is to calibrate this instrument and to tune it to the corporate needs by analysing real‐world applications. More specifically, several case studies have been investigated in large multinational organisations in the food sector. An acquisition case has been used for the calibration purpose. It is analysed in the paper from the ACM perspective to provide additional material for revisiting and improving the methodology.     

石泉水库主汛期拦蓄洪尾超蓄运用的风险分析

针对水资源匮乏和汛期水库大量弃水的矛盾，提出了有效的解决途径——汛期通过适时拦蓄洪尾超蓄运用的方式来充分利用洪水资源。拦蓄洪尾超蓄运用存在一定的风险，本文就超蓄运用的风险因素进行了识别分析，并从水文频率分析角度提出了计算超蓄风险率的方法；通过对石泉水库不同超蓄水位的风险率进行计算，结合可接受风险率值，得出了该水库拦蓄洪尾超蓄运用的期望水位。     

高校内部控制存在的问题及对策

从内部控制的内部环境、风险评估、控制活动、信息与沟通、内部监督等五要素分析高校内部控制中存在的问题.针对问题提出了相应的对策,即加强内部环境的建设、构建科学的风险评估机制、强化内部控制活动、建立科学的信息与沟通系统、设立有效的内部监督制度.