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In this paper, we present solution algorithms for the cycle hub location problem (CHLP), which seeks to locate p hub facilities that are connected by means of a cycle, and to assign non-hub nodes to hubs so as to minimize the total cost of routing flows through the network. This problem is useful in modeling applications in transportation and telecommunications systems, where large setup costs on the links and reliability requirements make cycle topologies a prominent network architecture. We present a branch-and-cut algorithm that uses a flow-based formulation and two families of mixed-dicut inequalities as a lower bounding procedure at nodes of the enumeration tree. We also introduce a metaheuristic based on greedy randomized adaptive search procedure to obtain initial upper bounds for the exact algorithm and to obtain feasible solutions for large-scale instances of the CHLP. Numerical results on a set of benchmark instances with up to 100 nodes and 8 hubs confirm the efficiency of the proposed solution algorithms. [ABSTRACT FROM AUTHOR]

This paper presents a connection between two real-time models: a deadline-based model and a latency-based model. The importance of the latency-based model is proved through a result showing that two deadlines, instead of a latency constraint, over-constrain the real-time applications. Moreover, we give a deadline-marking algorithm based on the relation between deadlines and latency constraints. This algorithm provides non-preemptive feasible schedules for systems with precedence constraints and deadlines, or more complex systems with deadlines and latencies. This is the first step toward non-preemptive schedulability for distributed architectures (without over-constraining the system) like, for example, the automotive applications using protocols such as Controller Area Network (CAN). [ABSTRACT FROM AUTHOR]

A tabu search algorithm for a cyclic job shop problem with blocking is presented. Operations are blocking if they must stay on a machine after finishing when the next machine is occupied by another job. During this stay the machine is blocked for other jobs. For this problem traditional tabu search moves often lead to infeasible solutions. Recovering procedures are developed which construct nearby feasible solutions. Computational results are presented for the approach. [ABSTRACT FROM AUTHOR]