in this study, preparation of nano-sized gamma alumina with high specific surface area and high yield by thereaction between aluminum nitrate and sodium carbonate, without using any surfactant is reported. bohemite (aluminum oxyhydroxide) was prepared as a precursor by strict control of ph and reaction temperature. the gel produced was purified by washing followed by centrifugation. the specifi...

This article considers the problem of scheduling preemptive open shops to minimize total tardiness. The problem is known to be NP-hard. An efficient constructive heuristic is developed for solving large-sized problems. A branch-and-bound algorithm that incorporates a lower bound scheme based on the solution of an assignment problem as well as various dominance rules are presented for solving me...

The solution methods based on semidefinite programming (SDP) relaxations for sensor network localization (SNL) problems can not handle very large-sized SNL problems. We present a continuation method using the gradient descent method to efficiently solve large-sized SNL problems. We first formulate the problem as an unconstrained optimization problem and then apply the continuation on the distan...

We introduce a heuristic method for finding good, feasible solutions for multiproduct lot sizing problems with general assembly structures, multiple constrained resources, and nonzero setup costs and setup times. We evaluate the performance of this heuristic by comparing its solutions to optimal solutions of small randomly generated problems and to time-truncated Optimization Subroutine Library...

This paper considers the economic lot and delivery scheduling problem in a two-echelon supply chains, where a single supplier produces multiple components on a flexible flow line (FFL) and delivers them directly to an assembly facility (AF). The objective is to determine a cyclic schedule that minimizes the sum of transportation, setup and inventory holding costs per unit time without shortage....

the objective of this paper is to determine the efficiency of manufacturing companies in kenya over the period of 2009 to 2011 as well as suggesting appropriate policies to be employed by the manufacturing companies in kenya based on the findings of the study. three critical inputs variables (raw materials, staff expenses and plant and machinery) and two output variables (net sale and earnings ...

Small and medium-sized logistics companies are playing an increasingly important part in social life. We selected the data of small and medium-sized logistical companies in Beijing, Shanghai and Guangzhou, reformulated ordinal regression support vector machine method so that different input points could make different contributions to decide hyper plane, to analyze multi-classification of credi...

development of modern economy without private sector and high vigilance entrepreneurs is vital to identify opportunities and use of opportunities around the world. in this regard, identifying the influencing factors on emergence and development of entrepreneurship culture can be effective to promote entrepreneurship in our country. for this purpose, the main issue in this study is to identify t...

While the 1980s were focused on the solution of large sized ``easy'' knapsack problems (KPs), this decade has brought several new algorithms, which are able to solve ``hard'' large sized instances. We will give an overview of the recent techniques for solving hard KPs, with special emphasis on the addition of cardinality constraints, dynamic programming, and rudimentary divisibility. Computatio...