Solid waste planning under uncertainty using evolutionary simulation-optimization

A key aspect of effective public planning design is to minimize the impact of negative outcomes that can arise from the violation of pre-established system constraint criteria. These planning situations can be especially complicated when several components within the studied system are either unknown or contain considerable stochastic uncertainty. In this paper, the concept of outcome minimization through the use of penalty functions is combined with grey programming (GP) into an evolutionary simulation-optimization (ESO) procedure in order to solve solid waste management problems containing significant sources of uncertainty. By employing outcome minimization concurrently with GP and ESO, it can be shown that plans that meet, or come close to meeting, required system criteria can be efficiently created. The efficacy of the procedure is demonstrated through its application to a solid waste planning case from the Municipality of Hamilton-Wentworth in the Province of Ontario, Canada. Since ESO techniques can be adapted to a wide variety of problem types in which some or all of the system components are stochastic, the practicality of this approach can be adapted to many operational and strategic planning situations containing significant sources of uncertainty.     

Investment behavior under Knightian uncertainty – An evolutionary approach

The ‘as if ’ view of economic rationality defends the profit maximization hypothesis by pointing out that only those firms who act as if they maximize profits can survive in the long run. Recently, the problem of arriving at a logically consistent definition of rational behavior in games has shown that one must sometimes study explicitly the evolutionary processes that form the basis of this view. The purpose of this paper is to investigate the usefulness of genetic programming as a tool for generating hypotheses about rational behavior in situations where explicit maximization is not well defined. We use an investment decision problem with Knightian uncertainty as a borderline test case, and show that when the artificial agents receive the same information about the unknown probability distributions, they develop behavior rules as if they were expected utility maximizers with Bayesian learning rules.     

A note on multinomial maximum likelihood estimation under ordered restrictions and the EM algorithm

A frequently occurring problem is to find the maximum likelihood estimation (MLE) of p subject to p∈C (C⊂ P the probability vectors in R ^k ). The problem has been discussed by many authors and they mainly focused when p is restricted by linear constraints or log-linear constraints. In this paper, we construct the relationship between the the maximum likelihood estimation of p restricted by p∈C and EM algorithm and demonstrate that the maximum likelihood estimator can be computed through the EM algorithm (Dempster et al. in J R Stat Soc Ser B 39:1–38, 1997). Several examples are analyzed by the proposed method.     

Optimal capital accumulation under price uncertainty and costly reversibility

We consider the optimal capital accumulation policy of a competitive firm operating in the presence of decreasing returns to scale, price uncertainty, and costly reversibility of investment. We characterize the optimal accumulation policy and derive the value of the firm by focusing on the marginal investment decision and solving the associated optimal timing problem characterizing the option value of the associated opportunity to either disinvest or acquire a marginal unit of capacity. We also characterize the required exercise premia associated with the optimal policies and demonstrate that hysteresis prevails within this class of accumulation problems as well.     

动态环境对ABC的挑战及与TOC整合管理模式的构建

本文从ABC这种管理思想的前提假设出发,分析了动态环境对ABC的挑战。在此基础上,提出了ABC与制约理论(ThetheoryofConstraint,sTOC)相结合的新型管理模式。并将这种整合模式应用于常见的生产决策,将决策结果与ABC进行比较,以说明整合模式的应用及其优越性。     

Forecasting and uncertainty in the economic and business world

Forecasts are crucial for practically all economic and business decisions. However, there is a mounting body of empirical evidence showing that accurate forecasting in the economic and business world is usually not possible. In addition, there is huge uncertainty, as practically all economic and business activities are subject to events we are unable to predict. The fact that forecasts can be inaccurate creates a serious dilemma for decision and policy makers. On the one hand, accepting the limits of forecasting accuracy implies being unable to assess the correctness of decisions and the surrounding uncertainty. On the other hand, believing that accurate forecasts are possible means succumbing to the illusion of control and experiencing surprises, often with negative consequences. We believe that the time has come for a new attitude towards dealing with the future. In this article, we discuss the limited predictability in the economic and business environment. We also provide a framework that allows decision and policy makers to face the future — despite the inherent limitations of forecasting and the uncertainty, sometimes huge, surrounding most future-oriented decisions.     

Failure rate of the minimum and maximum of a multivariate normal distribution

It is well known that if the parent distribution has a nonnegative support and has increasing failure rate (IFR), then all the order statistics have IFR. The result is not necessarily true in the case of bivariate distributions with dependent structures. In this paper we consider a multivariate normal distribution and prove that, the distributions of the minimum and maximum retain the IFR property. Received: September 1999     

Devaluating projects and the investment–uncertainty relationship

Sarkar (2000. On the investment–uncertainty relationship in a real options model. Journal of Economic Dynamics and Control, 24, 219–225) analyzes the investment–uncertainty relationship in a real-options model demonstrating that the widely accepted conclusion that uncertainty harms investment can be reversed. Wong (2006. The effect of uncertainty on investment timing in a real options model. Journal of Economic Dynamics and Control, forthcoming) confirms this point showing that more uncertainty can reduce the expected time to exercise the investment option. This paper deals with such an issue and attempts to integrate both Sarkar's and Wong's analysis.For risk-neutral investors, we show that uncertainty can favor investment only if projects devaluate over time. This conclusion does not hold in a CAPM framework, where we demonstrate that the relationship uncertainty/investment can be positive (a) even when the investment threshold increases with uncertainty and (b) in the case of projects negatively correlated with the market portfolio.     

Tapping the supercomputer under your desk: Solving dynamic equilibrium models with graphics processors

This paper shows how to build algorithms that use graphics processing units (GPUs) installed in most modern computers to solve dynamic equilibrium models in economics. In particular, we rely on the compute unified device architecture (CUDA) of NVIDIA GPUs. We illustrate the power of the approach by solving a simple real business cycle model with value function iteration. We document improvements in speed of around 200 times and suggest that even further gains are likely.     

The political uncertainty and stock market behavior in emerging democracy: the case of Taiwan

This paper examines the congressional effect between the pre- and post-democratization on the stock market by the asymmetric Generalized Autoregressive Conditional Heterosce desticity (GARCH) model in the period 1984–2004. The results found that the congressional effect is negative effect on stock returns but volatility is not significant. However, the democratic effect on stock returns is negative and increased of volatility. Moreover, the congressional effect on stock market returns following democratization significantly exceeds that before democratization, but have no significant effect for the volatility in the same circumstances. These results provide evidences consistent with the contention of liberalization (Hayek, Am. Econ. Rev. 35, 519–530, Individualism and Economic order, The university of Chicago press, Chicago, London, 1945, 1948; Popper, The open society and its Enemies, Princeton university, NJ, 1950).     

云环境下采购模式及风险评估研究

提高采购效率对企业发展至关重要。云环境下采购凭借其多样性、随机性、海量性等特点能够最大限度地满足用户需求,但是也存在着一定的风险。文中首先根据云环境的特征建立云环境下的采购模式,然后构建了云环境下采购风险评价指标体系及评价模型,运用网络分析法（ANP）在各指标间构造两两判断矩阵,在此基础上应用Super Decisions软件进行风险评价,最终得到云环境下采购风险指标权重排序。这一研究为云环境下采购风险的评估提供了方法和手段。     

The contingency effects of environmental uncertainty on the relationship between supply chain integration and operational performance

This paper extends prior supply chain research by building and empirically testing a theoretical model of the contingency effects of environmental uncertainty (EU) on the relationships between three dimensions of supply chain integration and four dimensions of operational performance. Based on the contingency and organizational information processing theories, we argue that under a high EU, the associations between supplier/customer integration, and delivery and flexibility performance, and those between internal integration, and product quality and production cost, will be strengthened. These theoretical propositions are largely confirmed by multi-group and structural path analyses of survey responses collected from 151 of Thailand's automotive manufacturing plants. This paper contributes to operations management contingency research and provides theory-driven and empirically proven explanations for managers to differentiate the effects of internal and external integration efforts under different environmental conditions.     

线下路基及框构基坑开挖与防护技术

根据具体工程概况,文章分析了施工方案选择,对旧路基纵向边坡的稳定性进行了分析,并提出了线下路基土开挖与防护措施。     

我国体育政府网站现状与网站内容设计

广大体育政府机关面对信息化挑战及政府职能能转换的宏观环境,正积极推进体育政府上网工程建设。文章阐述了我国体育政府上网工程建设现状,分析了体育政府网站定位因素,并提出了体育政府网站内容设计的一些看法。     

电力施工企业在建项目设备物资管理中的风险及防范措施

设备物资管理是电力施工企业在建项目管理的重中之重,如何通过规范设备物资管理,防范风险,是每个电力施工企业设备物资管理人员经常思考的问题。本文通过深入细致地分析设备物资管理中存在的风险,有针对性地提出系列防范措施,进而达到规范设备物资管理的目的。     

The competitive firm under price uncertainty: the role of information and hedging

We study the impact of transparency in a commodity market on the decision problem of a competitive firm under price uncertainty and hedging opportunities. Market transparency is modeled by means of the informational content of publicly observable signals which are correlated with the random price. We find that the impact of more transparency on labor employment and production depends on the firm’s technology. In particular, more transparency may result in lower average output even though on average more labor has been used in the production process. We also analyze the link between market transparency and the welfare of the firm. We are grateful to two anonymous referees who made extremely useful comments and suggestions.     

浅谈送电线路横线路移杆施工技术

文章介绍了超高压送电线路施工中水泥杆整体移动的施工技术措施。     

消费者对电子商务环境下流通满意度的影响因素及实证研究

电子商务已经成为流通升级与创新的必然趋势之一。文中将产品不确定性和商家熟悉程度作为电子商务环境下消费者对流通过程满意度的影响因素,采用规范的实证方法研究其影响作用,以及商家的售后服务水平在这一影响作用中的调节作用。     

稳增长和调结构双重目标下的我国产业投资战略导向研究

本文基于投入产出理论,从稳增长和调结构的视角,将产业投资决策表现为产业投资依赖度、产业投资效率两个状态指标,从而使产业投资决策成为一个具备完全时间内容和空间意义的系统决策。通过变结构控制动态投入产出模型识别各产业对投资的依赖度,通过DEA(数据包络分析)模型识别各产业当前的投资效率,并通过BCG(波士顿矩阵)模型综合分析产业的外部投资环境依赖度和内部投资效率,进一步判断在投资环境发生变化时如何采取合适的产业投资战略。