• Current Project

  • Vehicle Routing

    We study the vehicle routing problem with skill sets. We are given a set of customers, a set of vehicles, and a skill set for each vehicle along with a skill requirement for each customer. A vehicle can serve a customer if the customer's skill requirement belongs to the skill set of the vehicle. The goal is to design a set of routes with minimum total cost, such that the route for each vehicle starts and ends at a depot, and the skill requirement for customer belongs to the skill set of the vehicle.

    Bobby Chan, Ehsan Iranmanesh, Kamyar Khodamoradi, Ramesh Krishnamurti, Arash Rafiey, and Vladyslav Sokol

  • Past Projects

  • Level of Repair Analysis for defense logistics support planning (LORA)

    A complex engineering system containing (perhaps thousands) of subsystem and components is given. For each subsystem and each component (each subsystem contains some components) there is a possible repair decisions. The goal is to determine an optimal provision of repair and maintenance facilities to minimize overall life-cycle costs (which is of interest in
    UK and US military). An earlier result [A combinatorial approach to level of repair analysis, European J. Oper. Res. 129 (2001) 242–251] developed certain branch-and-bound heuristics.
    We model the problem as a minimum cost homomorphism problem in bipartite graphs and show that the problem is indeed solvable in polynomial time.

    G. Gutin, Arash Rafiey, M. Tso, and A. Yeo

  • Coordinated scheduling problem with time window constraints

    We consider selecting and scheduling of several jobs on a single machine with strictly enforced time windows constraints on the start-times of each job. We demonstrate how to develop network-based algorithms to sustain the desired work in process (WIP) profile in a manufacturing environment. Short-term production targets are used to coordinate decentralized local schedulers and to make the objectives of specific areas in-line with the chain objectives (Designed and implemented an efficient algorithm in C++).

    P.Jula and Arash Rafiey

  • Computationally hard aggregation and voting rules

    The goal is to design new algorithms based on integer programming, and approximation techniques to find the winner(s) of computationally hard aggregation and ranking rules fast.

    Ehsan Iranmanesh and Ramesh Krishnamurti

  • The scheduling and b-matching Proble

    We consider the problem of scheduling the shifts for workers in a factory. We improve the current best known algorithm and design faster algorithms to solve this problem optimally.

    Binay Batacharya, Ehsan Iranmanesh and Ramesh Krishnamurti