The optimal portfolio for the two-pillar mandatory pension system: the case of Poland

In the recent decade, there has been observed across the Central and Eastern European states the regulatory trend towards the increase of the non-financial (first) pension pillar size at the expense of the financial (second) pillar. It tends to question the consequences of this shift for the future retirement benefits. Applying the portfolio approach we address this issue by running a series of simulations to find out how to allocate pension contributions between both pillars in an optimal way. Our study contributes to the existing literature as follows. First, we do not perform the assessment of the predetermined regulatory solutions, but we look for an optimal one. Moreover, we allow our optimal rule to be time-varying, if necessary, which would be a true novelty in this research area. Second, we do not base our estimates on historical trends; rather, we apply the long-term economy’s projection to account for the society’s ageing impact, which is a crucially important factor for the solvency of the pension system. Adapting some of the simulation assumptions to fit the Polish case, our results confirm that current regulations underestimate the role of the capital pillar and the optimal allocation between both pillars should be time-varying.     

Consistency and optimality in a dynamic game of pollution control II: Monopoly

This paper continues a line of research begun in Batabyal (1995a). I model the interaction between a regulator and a monopolistic, polluting firm as a Stackelberg differential game in which the regulator leads. The firm creates pollution, which results in a stock externality. I analyze the intertemporal effects of alternate pollution control measures. The principal issue here concerns the dynamic inconsistency of the optimal solution. Inter alia, I compare the steady state levels of pollution under optimal and under dynamically consistent policies.     

上海市生态可持续发展评价研究

本文利用生态足迹法对上海市1985～2004年的生态足迹和生态承载力进行了研究，结果表明上海市入均生态足迹和生态承载力分别由1985年的1．9340hm^2、0．1582hm^2逐年增加至2004年的3．0459hm^2、0．5805hm^2，一而同期的入均生态赤字也由1．7958hm^2上升到2．6656hm^2。同时计算了万元GDP生态足迹，并预测了2010年的入均生态足迹和生态承载力。最后得出，上海市入口对自然资源的利用逐年增加，目前已超出了自然生态系统的生态承载力范围，现有的发展模式是不可持续的。     

Take a risk: Preferring prevention over control of biological invaders

Scientists have argued that invasive species can be managed most cost effectively with greater investments in prevention. Further, under ideas like the precautionary principle it is reasonable to expect that a cautious manager would use more prevention relative to control because it keeps more invaders out. Yet, this is not typically done. In many cases, private and public resources are invested primarily to control existing invaders rather than to prevent new invasions. Managers frequently wait until after invaders have arrived and then scramble to limit the damages. We believe these paradoxical decisions can be understood by recognizing the link between typical human preferences for risk bearing and the technology of risk reduction. We demonstrate quantitatively how managers perceived to be cautious or averse to risk tend to shy away from prevention relative to control. This counterintuitive result arises because control is a safer choice than prevention because its productivity is relatively less risky: it works to remove existing invaders from the system. In contrast, the productivity of prevention is more uncertain because prevention only reduces the chance of invasion, it does not eliminate it, and invasion may not occur even in the absence of prevention. Managers' averse to risk will inherently avoid as much uncertainty as possible, whether the source of uncertainty regards ecological outcomes or economic productivity. Implications for environmental decision making are clear. In invasive species management, if managers act as though they are risk averse, their caution can backfire when it leads to more control rather than prevention. The social consequences of this choice are a greater probability of future invasions and lower social welfare. Our results suggest that social welfare is highest when managers were willing to “take a risk” with prevention.     

固定资产动态折旧的分类模型与通用模型构建

文章参照固定资产静态折旧的几种典型模型,构建了直线动态折旧模型、折旧基数变化情况下的加速动态折旧模型、折旧率变化情况下的加速动态折旧模型,分别根据各种折旧模型各自折旧额的内在规律性进行建模,比较好地实现了从静态折旧模型向动态折旧模型的转化.在此基础上,本文试图去寻找各种动态折旧模型中各期折旧额的共同规律,进而建立起固定资产动态折旧的通用模型,以供企业根据自己的实际情况代入相应初始条件直接套用固定资产动态折旧的通用模型,方便地计算固定资产各期的动态折旧金额.     

芯钢管混凝土节点的芯管壁厚与节点承载力关系的数值分析

对一种已经通过试验研究的钢管混凝土结构的新型节点进行数值分析。这种节点将钢管混凝土柱的钢管在节点区间断,在节点区设置芯钢管,使梁中的纵筋在节点中直通、梁与节点区混凝土成为一体可靠的传递梁中的弯矩、剪力及轴力。本文利用数值分析弥补模型试验数量少的缺陷。选择不同芯钢管壁厚的节点模型进行非线性有限元分析,得出芯钢管壁厚对节点承载力的影响规律。分析结果表明芯钢管壁厚是影响节点承载力的主要因素之一。     

基于价值链的军事物流核心能力刍议

按照价值链管理的思想,可以把军事物流价值链分为物质价值链、采购价值链、知识价值链和信息价值链,依据对价值链的贡献,借助层次分析法等分析军事物流的能力要素,得出军事物流综合管理能力、整合能力、处理突发事件能力等三项基本核心能力,并对提升军事物流的核心能力提出了见解。     

物流市场供需的动态弹性分析

运用系统动力学的思想,通过对物流市场特点的分析,借助于动态弹性分析手段建立了物流市场供需的动态弹性模型。根据模型的结果模拟出了物流市场的供需趋势图,并借助于一个实例进行了具体运用,较准确的预测出物流市场的供需趋势,为决策提供了很好的支持。     

中铁行包公司基本生产设备配置的研究

在社会对小宗货物及高附加值小宗货物的快速运输需求日益增长的背景下,中铁行包公司作为铁路部门小宗货物快捷运输的主要负责系统,其运营好坏直接影响铁路在快运市场上的占有率,而基本生产设备的配置问题又直接关系到中铁行包公司能否满足日益增长的行包需求.本文提出设备配置理论,对设备的规划、配置、更新有着重要的意义.     

软件限时开发方法的研究与应用

限时开发是快速应用开发的最佳实践之一。文章介绍了限时开发的基本概念和优点以及适用的项目范围,通过一个进销存软件的开发实例说明如何成功地应用限时开发方法。