物流系统规划-仿真集成化技术研究

通过对物流系统规划与仿真模型的分析，归纳出系统规划模型与系统仿真模型的共有属性和关系，采用集成化的技术，建立集成化规划一仿真系统模型，并通过Solidworks和Flexsim研究实现其集成化，并在相关课题中获得成功应用，突破了现有软件在规划与仿真之间数据共享的壁垒。     

Agglomeration in an innovative and differentiated industry with heterogeneous knowledge spillovers

This paper introduces an agent-based simulation model to study the technological development, the economic performance of firms and the evolution of agglomerations in a differentiated industry. The analysis is based on the interaction and behavior of firms, which might share knowledge but at the same time are competitors on the goods markets. Firms do not only compete with quantities they can also introduce process and product innovations. The level of knowledge of a firm describes the capabilities to perform innovations. Knowledge can be accumulated by investing in R&D and by knowledge spillover, which depend on geographical and technological proximity. Simulation runs show that there is an incentive to agglomerate in young industries and that geographical proximity enhances innovation, especially the number of product innovations.      

村镇连锁经营配送系统关键技术问题分析

论文充分考虑村镇连锁经营配送系统的影响因素．对村镇连锁经营配送系统中的配送中心规划仿真技术和城乡双向物流问题进行深入的技术分析．同时提出了典型的村镇连锁经营管理与配送决策模型。     

Testing equality of variances in the analysis of repeated measurements

The problem of comparing the precisions of two instruments using repeated measurements can be cast as an extension of the Pitman-Morgan problem of testing equality of variances of a bivariate normal distribution. Hawkins (1981) decomposes the hypothesis of equal variances in this model into two subhypotheses for which simple tests exist. For the overall hypothesis he proposes to combine the tests of the subhypotheses using Fisher's method and empirically compares the component tests and their combination with the likelihood ratio test. In this paper an attempt is made to resolve some discrepancies and puzzling conclusions in Hawkins's study and to propose simple modifications.
The new tests are compared to the tests discussed by Hawkins and to each other both in terms of the finite sample power (estimated by Monte Carlo simulation) and theoretically in terms of asymptotic relative efficiencies.     

基于Petri网的物流分拣系统的建模与仿真

阐述了面向对象着色Petri网理论，并将它应用于物流分拣系统的建模，在分析该系统的基础上，建立了系统的面向对象着色Petri网模型，并借助AutoMod仿真软件对分拣系统进行了3D仿真。     

基于Repast平台的城市交通系统仿真建模研究

提出了采用基于Agent的仿真建模方法为研究人员提供了城市交通系统研究新的思路，Repast平台则可以支持研究人员对复杂适应系统快速地建模。介绍了Repast仿真平台的结构、主要类库及建模步骤，并结合城市交通系统中提供交通信息服务的实例，简要阐述了使用Repast仿真平台对城市交通系统进行建模的过程。     

The Bioeconomics of Marine Sanctuaries

Consider an offshore fishing grounds of size K. Suppose the grounds has been overfished to the point that net revenue has been driven to zero and the fishery is in open access equilibrium at (X, Y). A marine sanctuary, where fishing is prohibited, is then created. Suppose the marine sanctuary is of size K₂ and that fishing is allowed on a smaller grounds, now of size K₁, where K₁ + K₂ = K. In the first, deterministic, model, the present value of net revenue from the grounds-sanctuary system is maximized subject to migration (diffusion) of fish from the sanctuary to the grounds. The size of the sanctuary is varied, the system is re-optimized, and the populations levels, harvest, and value of the fishery is compared to the 'no-sanctuary' optimum, and the open access equilibrium. In the deterministic model, a marine sanctuary reduces the present value of the fishery relative to the 'ideal' of optimal management of the original grounds. In the second model net growth is subject to stochastic fluctuation. Simulation demonstrates the ability of a marine sanctuary to reduce the variation in biomass on the fishing grounds. Variance reduction in fishable biomass is examined for different-sized sanctuaries when net growth on the grounds and in the sanctuary fluctuate independently and when they are perfectly correlated. For the stochastic model of this paper, sanctuaries ranging in size from 60 to 40% of the original grounds (0.6 K₂/K 0.4) had the ability to lower variation in fishable biomass compared to the no sanctuary case. For a sanctuary equal to or greater than 70% of the original grounds (K₂ 0.7K), net revenue would be nonpositive and there would be no incentive to fish.     

Time diversification and security preferences: A stochastic dominance analysis

We use stochastic dominance to test whether investor should prefer riskier securities as the investment horizon lengthens. Return distributions for stocks, bonds, and U.S. Treasury bills are generated for holding periods of one to 25 years by simulation. For each holding period, stochastic dominance tests are run to establish preferences between the alternative security classes. Contrary to previous mean-variance based studies, we find no evidence that high-risk securities (stocks) dominate low-risk securities (bonds, Treasury bills) as the investment horizon lengthens. However, we do find that corporate bonds systematically dominate government bonds.     

博弈模型的扩展分析

偷逃税行为最现实的原因是纳税人和征税人之间的信息不对称。因此,其治理可从内外两个方面入手:"内"是在内部建立激励机制;"外"是通过制度的重新设计和调整,增强对纳税行为的控制和约束,堵塞纳税人的寻租途径。     

Assessing the Least Squares Monte-Carlo Approach to American Option Valuation

A detailed analysis of the Least Squares Monte-Carlo (LSM) approach to American option valuation suggested in Longstaff and Schwartz (2001) is performed. We compare the specification of the cross-sectional regressions with Laguerre polynomials used in Longstaff and Schwartz (2001) with alternative specifications and show that some of these have numerically better properties. Furthermore, each of these specifications leads to a trade-off between the time used to calculate a price and the precision of that price. Comparing the method-specific trade-offs reveals that a modified specification using ordinary monomials is preferred over the specification based on Laguerre polynomials. Next, we generalize the pricing problem by considering options on multiple assets and we show that the LSM method can be implemented easily for dimensions as high as ten or more. Furthermore, we show that the LSM method is computationally more efficient than existing numerical methods. In particular, when the number of assets is high, say five, Finite Difference methods are infeasible, and we show that our modified LSM method is superior to the Binomial Model.