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We consider the problem of constructing an appropriate multivariate model to study counterparty credit risk in the credit rating migration problem. For this financial problem different multivariate Markov chain models were proposed. However, the Markovian assumption may be inappropriate for the study of the dynamics of credit ratings, which typically show non Markovian-like behavior. In this article, we develop a semi-Markov approach to study the counterparty credit risk by defining a new multivariate semi-Markov chain model. Methods are given for computing the transition probabilities, reliability functions and the price of a risky Credit Default Swap. 相似文献
243.
本文提出一种改进的多重尝试Metropolis算法,用于非线性动态随机一般均衡模型的贝叶斯参数估计和模型选择。多重尝试策略通过每次迭代抽取多个尝试点的方法来提高算法的混合速率,新方法中提出使用近似的方法提高计算速度,并通过接收概率调整偏差。数值实验表明新方法在相同的计算时间内具有更高的估计效率。最后,本文比较了具有不同货币政策设定的模型对中国经济数据的拟合效果,发现中国数据更加支持具有时变通胀目标的模型。 相似文献
244.
作为国际农业生物技术研发领域的新近发展——基冈利用限制技术(GURTs)自1998年首次被授予专利以来就引起各方面的强烈争议,特别是能够致使后代种子不育的所谓“终止子”技术,更是遭到国际社会特别是不发达国家的强烈谴责。首先从技术层面对GURTs进行了说明,然后重点从国际组织、各国政府及非政府组织对GURTs的态度和申请专利的情况对该技术的研发应用现状作了分析。最后从私人研发商对利润最大化的无止境追求与知识产权保护的“相对”不足、过高的知识产权保护执行成本和能获得超额利润的预期三方面对GURTs产生的内在原因做了深层次剖析。 相似文献
245.
The flowshop scheduling problem (FSP) has been widely studied in the literature and many techniques for its solution have been proposed. Some authors have concluded that genetic algorithms are not suitable for this hard, combinatorial problem unless hybridization is used. This work proposes new genetic algorithms for solving the permutation FSP that prove to be competitive when compared to many other well known algorithms. The optimization criterion considered is the minimization of the total completion time or makespan (Cmax). We show a robust genetic algorithm and a fast hybrid implementation. These algorithms use new genetic operators, advanced techniques like hybridization with local search and an efficient population initialization as well as a new generational scheme. A complete evaluation of the different parameters and operators of the algorithms by means of a Design of Experiments approach is also given. The algorithm's effectiveness is compared against 11 other methods, including genetic algorithms, tabu search, simulated annealing and other advanced and recent techniques. For the evaluations we use Taillard's well known standard benchmark. The results show that the proposed algorithms are very effective and at the same time are easy to implement. 相似文献
246.
The Construction of Optimal Imcomplete Block Designs When Observations Within a Block are Correlated
An algorithmic method is described for the construction of optimal incomplete block designs when a known correlation structure is assumed for observations from plots in the same block. The method is applicable to a wide class of designs and correlation structures. Some examples are given to illustrate the procedure. 相似文献
247.
The investment on facilities for manufacturing high-tech products requires a large amount of capital. Even though the demands of such products change dramatically, a company is forced to implement some make-to-stock policies apart from a regular make-to-order production, so that the capacity of expensive resources can be highly utilized. The inherent characteristics to be considered include finite budget for investing resources, lump demands of customers, long production horizon, many types of products to mix simultaneously, time value of capital and asset, technology innovation of resources, efficient usage of multiple-function machines, and limited capacity of resources. In addition to revenue gained from products and the salvage/assets of resources, a decision maker also needs to consider costs regarding inventory, backorder, and resource acquisition-related costs through procurement, renting, and transfer. This study thus focuses on the following issues: (i) how to decide on resources portfolio regarding the way and timing of acquisting resources, and (ii) how to allocate resources to various orders in each production period. The goal is to maximize the long-term profit. This study formulates the problem as a non-linear mixed integer mathematical programming model. A constraint programming-based genetic algorithm is developed. It has been demonstrated to solve the problem efficiently. 相似文献
248.
Social Work's Role in Prenatal Diagnosis and Genetic Services: Current Practice and Future Potential
AbstractAlthough the development of sophisticated technologies associated with prenatal testing processes have assisted in the practice of prenatal diagnosis, limited attention has been given to the complexities surrounding the decision-making processes for pregnant women following a poor or fatal diagnosis. An emerging international body of knowledge suggests that the process of having prenatal testing and then deciding on whether to continue a wanted pregnancy is often difficult and traumatic. In the last 50 years, social workers have played an invaluable role in the provision of holistic counselling and support for children and families in a range of areas and contexts. This paper highlights the unique contributions that social workers can bring to the field of prenatal testing. It emphasises the consideration of strengths and values inherent within social work practice that provides appropriate and timely support for women who have received a poor or fatal diagnosis following prenatal testing. 相似文献
249.
虚拟企业是新时代应对激烈竞争、迅速变化的市场环境的主要模式,合作伙伴选择是关系虚拟企业成败的关键环节,该过程非常重要又极其复杂。考虑到已有选择方案的效率低下和可操作性不理想,本文提出三阶段选择模型,并给出每阶段所采用的分析方法,目的是高效合理地获得合作伙伴多目标组合优化问题的最优解。 相似文献
250.