Spark plasma sintering (SPS) is a sintering process that is capable of sintering hard worked powders in short times. This technique was used to fabricate bulk Cu and Cu-SiC nanocomposites. Pure Cu and mixed powders of Cu including 4 vol% of SiC nanoparticles were mechanically alloyed for 25 h and sintered at 750˚C under vacuum condition by SPS method. Microstructures of the materials were chara...

We consider the Submodular Welfare Problem where we have m items and n players with given utility functions wi : 2[m] → R+. The utility functions are assumed to be monotone and submodular. We want to find an allocation of disjoint sets of items (S1,S2, . . . ,Sn) maximizing ∑i wi(Si). A (1− 1/e)-approximation for this problem in the demand oracle model has been given by Dobzinski and Schapira [...

The design of mechanisms for building micro-tools can be viewed as a shape optimization problem with a peculiar objective function. We propose such an optimization method based on homogenization, which is called topology optimization. RÉSUMÉ. La conception optimale de mécanismes, destinés par exemple à la fabrication de micro-mécanismes peut-être envisagée comme un problème d’optimisation de fo...

Many inverse problems are formulated as optimization problems over certain appropriate input distributions. Recently, there has been a growing interest in understanding the computational hardness of these optimization problems, not only in the worst case, but in an average-complexity sense under this same input distribution. In this note, we are interested in studying another aspect of hardness...

This thesis tries to expand the frontiers of approximation algorithms, with respect to the range of optimization problems as well as mathematical tools for algorithms and hardness. We show tight approximabilities for various fundamental problems in combinatorial optimization. We organize these problems into three categories — new and applied constraint satisfaction problems (CSP), hypergraph co...

This paper deals with an anology of scheduling jobs on prarallel processors using Ant Colony Optimization where job values are given as a power function of the job execution times. We consider a scheduling problem in a machine of parallel processors with the objective of minimization of the total loss of job values is considered as criterion which reflects the minimization of waiting time of th...

Relative to the large literature on upper bounds on complexity of convex optimization, lesser attention has been paid to the fundamental hardness of these problems. Recent years have seen a surge in optimization methods tailored to sparse optimization problems. In this paper, we study the complexity of stochastic convex optimization in an oracle model of computation, when the objective is optim...

We study the parameterized complexity of cardinality constrained optimization problems, i.e. optimization problems that require their solutions to contain specified numbers of elements to optimize solution values. For this purpose, we consider around 20 such optimization problems, as well as their parametric duals, that deal with various fundamental relations among vertices and edges in graphs....

efforts to improve the quality of bakery products are increasing every day. several techniques were developed for this purpose. in this study the possibility of betterment and optimization of quality properties of dough and barbari bread with emphasis on process variables using rotatable response surface methodology were investigated. the independent process variables for baking process were do...