求解全局最优问题的多重点样本水平值估计的相对熵算法

研究有界闭箱约束下的全局最优化问题,利用相对熵及广义方差函数方程的最大根与全局最小值之间的等价关系,设计求解全局最优值的积分型水平值估计算法.对采用重点样本采样技巧产生的函数值按一定规则进行聚类,从而在各聚类中产生的若干新重点样本,结合相对熵算法,构造出多重点样本进行全局搜索的新算法.该算法的优点在于每次迭代选用当前较好的函数值信息,以达到随机搜索到更好的函数值信息.同时多重点样本可有利挖掘出更好的全局信息.一系列的数值实验表明该算法是非常有效的.     

围长至少是7的1-平面图是$(1,1,1,0)$-可染的

一个图称为是1-平面图的, 如果它可以画在一个平面上使得它的每条边最多交叉另外一条边.本文证明了围长大于等于7的1-平面图是$(1,1,1,0)$-可染的.     

青海省主导产业创新效率评价研究

运用数据包络分析法(DEA)对青海省主导产业创新效率进行评估,结果表明青海省主导产业创新效率存在规模效益不变、规模效益递增、规模效益递减三种不同类型,而且主导产业创新低效率同时存在投入冗余和产出不足.将青海省主导产业与全国同类产业部门创新效率对比发现青海省主导产业总体创新效率较低,也有部分产业创新效率略高于全国同类产业部门平均水平.进而分析影响青海省主导产业创新效率的区域因素,最后提出提升青海省主导产业创新效率的对策.     

MODELING THE EFFECTS OF WOOD AND NON‐WOOD BASED INDUSTRIES ON FORESTRY RESOURCES

Pollution due to the wood and non‐wood based industries is one of the main reasons for the depletion of forestry resources. On the onset of industrial era, the number of industries was less but now it has increased much due to rapid pace of development. Industrialization affects forestry resources in two ways: (i) using raw materials by wood based industries and cut down by non‐wood based industries and (ii) emitting pollutants by wood and non‐wood based industries. In view of this, in this paper, we have proposed and analyzed a mathematical model to assess the effects of wood and non‐wood based industries on the depletion of forestry resources. In the modeling process, it is assumed that wood and non‐wood based industries deplete the forestry resources directly, whereas pollutants emitted by both types of industries decrease the growth rate of forestry resources indirectly. The equilibria are obtained and their stability is discussed. The model analysis reveals that forestry resources decrease due to the growth in wood based industries but the overgrowth in non‐wood based industries and pollutants emitted by them in the environment adversely affect the forestry resources. Numerical simulation is provided to support analytical findings.     

国内非牛顿流体力学进展

非牛顿流体;;本构方程;;流变测量;;流动稳定性;;收缩流动;;聚合物加工;;石油工业;;生物流体力学     

无解的模糊关系方程的最优近似解

对无解的模糊关系方程给出了最优近似解的定义,证明了最优近似解的存在性,给出了求最优近似解的算法     

An evaluation of value based dispatching rules in a flow shop

Although investment in inventory has been of primary concern in job shops, little attention has been paid to using value-based dispatching rules in an effort to attain satisfactory on-time performance while reducing inventory investment. This paper compares performance based on both time and value measures of three usual time-based rules with six rules which directly incorporate value information in setting priorities. The results indicate that the value-based rules perform their intended function quite well with only slight sacrifice in on-time performance in light to moderately loaded shops. In addition, some of these values rules outperform the best time-based rules on both dimensions in heavily loaded shops.     

The design of colliery information and control systems

The paper is concerned with describing an investigation of information usage in the control of colliery operations. The premise of the work is that to make the most of new information retrieval technology currently being installed in collieries research in needed to provide compatible advances in methods of information usage. The approach adopted was to construct a continuous simulation model using system dynamics capable of providing a laboratory assessment of alternative managerial control policies based on alternative sources and levels of aggregation of information.The model developed represents a typical colliery situation composed of three working coal-faces and incorporating planning, production, development and manpower sectors. The face sectors transform coal reserves to mined coal output, under manpower constraints and geological shocks, and these are all interlinked by means of allocation policies for manpower and machine shifts.A range of policies for the exercise of control through these allocations are considered subject to a range of shocks. It is concluded that, although there are difficulties in designing single policies which are universally best, there are clear advantages associated with fully integrated colliery policies based on information inputs from all aspects of the operations.     

Protective inventories and bottlenecks in production systems

In this paper we study the allocation of safety stocks and safety times in multi-echelon production systems. We concentrate on the impact of demand uncertainty on the amount of safety stocks in the presence of capacity constraints. We describe how this problem can be viewed as a Markovian Decision Process. The form of the optimal policies is discussed and illustrated with examples.     

Latent variable modelling of price‐change in 295 manufacturing industries

In contrast to traditional regression analysis, latent variable modelling (LVM) can explicitly differentiate between measurement errors and other random disturbances in the specification and estimation of econometric models. This paper argues that LVM could be a promising approach to test economic theories because applied research in business and economics is based on statistical information, which is frequently inaccurately measured. Considering the theory of industry‐price determination, where the price variables involved are known to include a large measurement error, a latent variable, structural‐equations model is constructed and applied to data on 7381 product categories classified into 295 manufacturing industries of the USA economy. The obtained estimates, compared and evaluated against a traditional regression model fitted to the same data, show the advantages of the LVM analytical framework, which could lead a long drawn‐out conflict between empirical results and theory to a satisfactory reconciliation. Copyright © 2003 John Wiley & Sons, Ltd.