Computing the finite-time expected discounted penalty function for a family of Lévy risk processes

Ever since the first introduction of the expected discounted penalty function (EDPF), it has been widely acknowledged that it contains information that is relevant from a risk management perspective. Expressions for the EDPF are now available for a wide range of models, in particular for a general class of Lévy risk processes. Yet, in order to capitalize on this potential for applications, these expressions must be computationally tractable enough as to allow for the evaluation of associated risk measures such as Value at Risk (VaR) or Conditional Value at Risk (CVaR). Most of the models studied so far offer few interesting examples for which computation of the associated EDPF can be carried out to the last instances where evaluation of risk measures is possible. Another drawback of existing examples is that the expressions are available for an infinite-time horizon EDPF only. Yet, realistic applications would require the computation of an EDPF over a finite-time horizon. In this paper we address these two issues by studying examples of risk processes for which numerical evaluation of the EDPF can be readily implemented. These examples are based on the recently introduced meromorphic processes, including the beta and theta families of Lévy processes, whose construction is tailor-made for computational ease. We provide expressions for the EDPF associated with these processes and we discuss in detail how a finite-time horizon EDPF can be computed for these families. We also provide numerical examples for different choices of parameters in order to illustrate how ruin-based risk measures can be computed for these families of Lévy risk processes.     

The moments of the Gompertz distribution and maximum likelihood estimation of its parameters

The Gompertz distribution is widely used to describe the distribution of adult deaths. Previous works concentrated on formulating approximate relationships to characterise it. However, using the generalised integro-exponential function, exact formulas can be derived for its moment-generating function and central moments. Based on the exact central moments, higher accuracy approximations can be defined for them. In demographic or actuarial applications, maximum likelihood estimation is often used to determine the parameters of the Gompertz distribution. By solving the maximum likelihood estimates analytically, the dimension of the optimisation problem can be reduced to one both in the case of discrete and continuous data. Monte Carlo experiments show that by ML estimation, higher accuracy estimates can be acquired than by the method of moments.     

UBD/MPD技术标准现状分析

针对欠平衡钻井(UBD)和控制压力钻井(MPD)的石油行业标准、IADC标准、API标准进行了综述,着重讨论了目前欠平衡钻井和控制压力的标准现状,探讨了以后我国石油行业可能建立控制压力标准所包含的主要内容。     

Reformulating Environmentally Constrained Traffic Equilibrium via a Smooth Gap Function

Various government laws have recently been enacted to alleviate the environmental deterioration of transportation systems. Environmental constraint is a valid means to explicitly reflect various environmental protection requirements imposed by the government. In this paper, we examine the environmentally constrained traffic equilibrium problem (EC-TEP), which is a fundamental tool for modeling and evaluating environmental protection requirements. Specifically, we provide an equivalent reformulation for the EC-TEP. The proposed reformulation adapts the concept of gap function to simultaneously reformulate the nonlinear complementarity conditions associated with the generalized user equilibrium conditions, environmental constraints, and conservation constraints as an equivalent unconstrained optimization problem. This gap function reformulation has two desirable features: (1) it can handle a general environmental constraint structure (linear or nonlinear; link-based or area-based) and a general link and route cost structure, enhancing the modeling adaptability and flexibility; (2) it is smooth and unconstrained, permitting a number of existing efficient algorithms for its solution. A gradient-based solution algorithm with a self-regulated averaging stepsize scheme is customized to solve the reformulated unconstrained optimization problem. Numerical examples are also provided to demonstrate the modeling flexibility of the proposed EC-TEP reformulation.     

中国商业银行规模经济实证分析——基于超越对数成本函数法

商业银行成本结构、规模经济的研究,是世界上商业银行研究的一个重要研究领域,国外有关的研究文献很多,而中国国内的这方面的研究才刚刚开始,相关的研究还很滞后。本文在前人研究的基础上,采用生产法确定银行的产出,利用超越对数成本函数法,选取14家中国商业银行(包括4家国有商业银行、10家股份制商业银行)1999-2003年的数据,对中国银行业的规模经济进行了实证检验,得出了区别于其他学者的一些结论,并指出了今后银行规模经济研究的主要方向。     

从有效需求看政府在提高居民购房能力中的作用

随着我国住房制度改革的推进,我国住房市场出现了城镇中等收入居民有强烈的购房欲望,然而又因为收入偏低而没有实际支付能力,即有效需求不足的局面。凯恩斯的消费函数具有普遍意义,就当前来说,居民对住房的消费尚属于其引致消费的一部分,政府应该通过增加中等收入居民的可支配收入来提高他们对住房的消费能力。而可支配收入的提高又有赖于税收杠杆,政府对国内居民发行公债和参与保险可以增加政府的转移支付能力,从而提高中等收入居民的可支配收入。     

基于港口的物流产业集群形成机理与政府作用研究

港口具备了物流产业集群形成的资源禀赋,基于港口的物流产业集群具有明显竞争优势,它是物流专业化水平不断提高的产物。要采用“自下而上”方式,切实加强和发挥政府在培育港口物流产业集群中的引导和扶持作用。     

政府参与农民合作经济组织发展的职能演变

农民合作经济组织与政府之间的关系对合作组织的发展有着至关重要的影响。政府参与是我国农民合作经济组织发展的必要条件,政府应依照农民合作经济组织发展的初期、成长期、成熟期三个阶段的特性来对自己的职能进行动态定位,以哺育、扶持、守夜人身份执行政府职能。     

旅游产品散论

目前学界对旅游产品的概念存在不少分歧,本文择取如下问题加以讨论:旅游产品是否包含媒介要素、是否是一种经历或体验、是否是商品、是否包含目的地出售的实物形态商品以及是否包含旅游资源.本文认为,媒介要素是旅游产品的必要组成部分,不能把旅游产品看作经历或体验,旅游产品是商品,旅游产品中不包含旅游地出售的旅游纪念品等实物形态商品,也不包括旅游资源.本文着重讨论了旅游资源与旅游产品的关系,提出旅游资源不是旅游产品或产品的一部分,而是、也仅仅是旅游产品生产要素中狭义的土地要素.     

我国通货膨胀过程的社会福利成本度量与经验分析

通过利用1994年至2006年之间的我国GDP、M1和名义利率的季度数据,采用协整检验和回归系数估计方法,获得我国长期货币需求函数,在此基础上对我国通货膨胀的社会福利成本进行了实证分析。实证结果表明,我国较高的通货膨胀率会带来比较大的福利成本,因此,当前通胀压力较大的时期,采取适当的宏观调控措施,将通货膨胀率控制在3%以下的低水平状态。