A branch and bound based heuristic for makespan minimization of washing operations in hospital sterilization services

In this paper, we address the problem of parallel batching of jobs on identical machines to minimize makespan. The problem is motivated from the washing step of hospital sterilization services where jobs have different sizes, different release dates and equal processing times. Machines can process more than one job at the same time as long as the total size of jobs in a batch does not exceed the machine capacity. We present a branch and bound based heuristic method and compare it to a linear model and two other heuristics from the literature. Computational experiments show that our method can find high quality solutions within short computation time.     

求线性比式和问题全局解的输出空间分枝定界算法

基于对p-1维输出空间进行剖分的思想,提出了一种求解线性比式和问题的分枝定界算法.通过一种两阶段转换方法得到原问题的一个等价问题,该问题的非凸性主要体现在新增加的p-1个非线性等式约束上.利用双线性函数的凹凸包络对这些非线性约束进行凸化,这就为等价问题构造了凸松弛子问题.将凸松弛子问题中的冗余约束去掉并进行等价转换,从而获得了一个比凸松弛子问题规模更小、约束更少的线性规划问题.证明了算法的理论收敛性和计算复杂性.数值实验表明该算法是有效可行的.     

A proof of Jones' conjecture

In this paper, we prove that Wright's equation $y^{\prime }(t)=?\alpha y(t?1)\{1+y(t)\}$ has a unique slowly oscillating periodic solution for parameter values $\alpha \in (\frac{\pi }{2},1.9]$, up to time translation. This result proves Jones' Conjecture formulated in 1962, that there is a unique slowly oscillating periodic orbit for all $\alpha >\frac{\pi }{2}$. Furthermore, there are no isolas of periodic solutions to Wright's equation; all periodic orbits arise from Hopf bifurcations.     

A Branch and Bound Algorithm for Solving Low Rank Linear Multiplicative and Fractional Programming Problems

This paper is concerned with a practical algorithm for solving low rank linear multiplicative programming problems and low rank linear fractional programming problems. The former is the minimization of the sum of the product of two linear functions while the latter is the minimization of the sum of linear fractional functions over a polytope. Both of these problems are nonconvex minimization problems with a lot of practical applications. We will show that these problems can be solved in an efficient manner by adapting a branch and bound algorithm proposed by Androulakis–Maranas–Floudas for nonconvex problems containing products of two variables. Computational experiments show that this algorithm performs much better than other reported algorithms for these class of problems.     

Solving sum-of-ratios fractional programs using efficient points

Constrained maximization of a sum of p1 ratios is a difficult nonconvex optimization problem (even if all functions involved are linear) with many applications in management sciences. In this paper, we first give a brief introductory survey of this problem. Then we propose a general branch-and-bound algorithm which uses rectangular partitions in the Euclidean space of dimension p. Theoretically, this algorithm is applicable under very general assumptions. Practically, we give an efficient implementation for fine fractions. Here the bounding procedures use dual constructions and the calculation of efficient points of a corresponding multiple-objective optimization problem. Finally, we present some promising numerical results     

A New Formulation and Computational Results for the Simple Cycle Problem

In this paper we propose a new formulation for the Simple Cycle Problem and conduct preliminary computational tests comparing it with a formulation that comes from the literature.     

中国科学院兰州分院ARP 建设与发展

ARP 是技术、是方法，更是一种新的重要管理思想。本文应用知识管理的相关理论，结合中国科学院兰州分院信息化建设的工作实际，就ARP 理念的塑造、人才的培养建设以及实践效益三方面进行了阐述并对ARP 在促进管理理念更新、优化管理环境方面的进一步发展与应用进行了探讨。