吹塑机头螺旋芯棒的数控编程与加工

针对吹塑机头上螺旋槽的结构特点,介绍了一种数控加工工艺与编程方法,不仅提高了加工精度和质量,而且大大提高了生产效率,克服了加工中的实际难题,对同类零件的加工有一定借鉴作用。     

C语言和汇编语言混合编程方法

C语言是一种高级的面向过程的开发语言,汇编语言是一种低级的面向机器的编程语言。两者在程序设计开发方面各有优劣,目前两者的混合编程得到了广泛的应用。本文通过具体的实例,说明了混合编程的基本方法,为C语言应用开发人员提供方便。     

Disruption-driven supply chain (re)-planning and performance impact assessment with consideration of pro-active and recovery policies

In this study, an approach to re-planning the multi-stage supply chain (SC) subject to disruptions is developed. We analyze seven proactive SC structures, compute recovery policies to re-direct material flows in the case of two disruption scenarios, and assess the performance impact for both service level and costs with the help of a SC (re)planning model containing elements of system dynamics and linear programming. In the result, an explicit connection of performance impact assessment and SC plan reconfiguration issues with consideration of the duration of disruptions and the costs of recovery has been achieved.     

Handling uncertainty in Multi Regional Input-Output models by entropy maximization and fuzzy programming

Recently, great attention has been paid to the uncertainties associated with Multi Regional Input-Output (MRIO) models related to the available data sources. We propose a new method based on the entropy maximization principle and fuzzy optimization, which takes explicitly into account the uncertainty embedded in available information. It allows to estimate jointly the values of production level, the trade coefficients and the final demand values assuming the availability of incomplete and/or approximate data on some elements of trade coefficients and of final demand of goods. The model, applied to real scale problem, shows good estimation performances and robustness in different scenario.     

企业创新资源配置逆优化模型及其应用

创新资源的有效配置是促进企业创新发展的核心要素，然而，我国企业创新资源配置水平和效率普遍偏低，亟需构建科学的资源配置优化体系以应对企业快速增长的创新需求，由此，本文在对企业创新资源配置关键要素分析的基础上，构建了企业创新资源配置原始模型和逆优化模型，并结合X企业的实证研究对模型进行求解验证。结果表明：企业创新资源配置逆优化模型能够客观反映X企业的实际创新资源配置水平，通过模型的求解能够大幅优化企业创新资源配置的结果，同时为企业提供具体的优化建议。     

Joint optimization of strategic fleet planning and contract analysis in tramp shipping

Maritime transportation is one of the most capital-intensive industries. Fleet planning is vital but challenging to shipowners because the industry is extremely volatile. Relatively few papers have studied strategic fleet planning in tramp shipping, which is intertwined with contract analysis and different from that in industrial or liner shipping. This article develops a mixed-integer programming model, and it is the first of its kind that jointly optimizes strategic fleet planning and the selections of long-term and spot contracts in tramp shipping. The model can be used to determine the best mix of long-term and spot contracts for a given fleet and/or to find the optimal fleet size and mix for a set of contracts. It can be used as a basis for a fleet renewal programme, informing decisions on when to sell, whether to buy old or new ships, and when to charter in or out vessels. A numerical example is given to illustrate how to use the model to evaluate different operations strategies.     

物流企业多式联运的运输方案优化选择

针对物流企业多式联运运输方案的优化选择问题进行研究，考虑运输费用、时间窗等约束问题建立数学规划模型，并把问题转换为网络问题，根据网络特性采用动态规划方法进行求解。通过实例分析表明，算法可行、有效，优化方案可为决策者提供依据。     

MEAN–VARIANCE PORTFOLIO OPTIMIZATION WITH STATE‐DEPENDENT RISK AVERSION

The objective of this paper is to study the mean–variance portfolio optimization in continuous time. Since this problem is time inconsistent we attack it by placing the problem within a game theoretic framework and look for subgame perfect Nash equilibrium strategies. This particular problem has already been studied in Basak and Chabakauri where the authors assumed a constant risk aversion parameter. This assumption leads to an equilibrium control where the dollar amount invested in the risky asset is independent of current wealth, and we argue that this result is unrealistic from an economic point of view. In order to have a more realistic model we instead study the case when the risk aversion depends dynamically on current wealth. This is a substantially more complicated problem than the one with constant risk aversion but, using the general theory of time‐inconsistent control developed in Björk and Murgoci, we provide a fairly detailed analysis on the general case. In particular, when the risk aversion is inversely proportional to wealth, we provide an analytical solution where the equilibrium dollar amount invested in the risky asset is proportional to current wealth. The equilibrium for this model thus appears more reasonable than the one for the model with constant risk aversion.     

Efficiency in forest management: A multiobjective harvest scheduling model

This paper presents a new forest harvest scheduling model taking into account four conflicting objectives. The economic factor of timber production is considered and also aspects related to environmental protection. We also incorporate adjacency constraints to limit the maximum contiguous area where clear-cutting can be applied. The model proposed is applied to a timber production plantation in Cuba located in the region of Pinar del Río. One factor to be taken into account in Cuban plantations is that the forest has a highly unbalanced age distribution. Therefore, in addition to the classical objectives of forest planning, we have the objective of rebalancing age distribution by the end of the planning horizon. Explicitly, the four objectives considered in the model are: (a) obtaining a balance-aged forest; (b) minimizing the area with trees older than the rotation age; (c) maximizing the NPV of the forest over the planning horizon; and (d) maximizing total carbon sequestration over the whole planning horizon. The solution to the proposed model provides a set of efficient management plans that are of assistance in analysing the tradeoffs between the economic and ecological objectives. The model is also applied to randomly generated simulated forests to compare its performance in other contexts. As the problem is a multiobjective binary nonlinear model, a metaheuristic procedure is used in order to solve it.     

基于Copula函数的保险公司经济资本配置研究

经济资本的度量及配置是风险管理的核心内容。本文利用Copula函数构建保险公司总体风险的联合分布函数,结合TCE方法来度量保险公司经济资本,并利用动态规划方法对经济资本最优配置模型求解。最后结合中国人民财产保险股份有限公司的数据进行实证。通过研究发现,我国财险公司内部偿付能力状况较好,但险种结构有待优化。