Several issues concerning an analysis of large and sparse linear programming problems prior to solving them with an interior point based optimizer are addressed in this paper. Three types of presolve procedures are distinguished. Routines from the rst class repeatedly analyze an LP problem formulation: eliminate empty or singleton rows and columns, look for primal and dual forcing or dominated ...

Nowadays, the expansion of the cities is an inevitable necessity; increasing the dependence of the citizens on motor vehicles and, consequently, making development of the transportation networks a necessity rather than an option. Thus, increasing car ownership and car use has created many problems for the cities, such as increasing greenhouse gas emissions, environmental pollution, casualties o...

The development of clean and renewable energy materials as alternatives to fossil fuels is foreseen as a potential solution to the crucial problems of environmental pollution and energy shortages. Hydrogen is an ideal energy material for the future, and water splitting using solar/electrical energy is one way to generate hydrogen. Metal-organic frameworks (MOFs) are a class of porous materials ...

Stochastic volatility models lead to more realistic option prices than the Black-Scholes model which uses a constant volatility. Based on such models a two-dimensional parabolic partial differential equation can derived for option prices. Due to the early exercise possibility of American option contracts the arising pricing problems are free boundary problems. In this paper we consider the nume...

by shouldering the burden of a big chunk of global production, and giving shelter to half of the world’s population, currently cities play an important role in national economies. benefits of agglomeration in cities have played a major role in the process of economic development of different countries, however, the expansion of urbanization has produced some problems including environmental and...

research interests have been focused on the concept of penalizing jobs both for being early and for being tardy because not only of modern competitive industrial challenges of providing a variety of products at a very low cost by smoothing productions but also of its increasing and exciting computer applications. here, sequencing approaches of the mixed- model just-in-time production systems is...

Early experiments in migrating task images from one node in a metacomputing environment to another have shown, that it is possible to achieve almost maximum data throughput in LAN networks. With WAN-connected metacomputers however, the time spent in the task migration is not negligible. Here, alternative routing paths must be used concurrently to reduce the total migration time. We present a pr...