Let π be a nonidling fully collaborative policy. Under any fully collaborative policy, our model is equivalent to one where the service requirements of successive customers at station j ∈ {1, . . . , N} are independent and identically distributed (i.i.d.) with mean 1 αjγj , service rates of collaborating servers are additive, and the service rates depend only on servers, i.e., μij = μi for all ...

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Data intensive computing, in the Web environment, motivates the distributed designs of Web server systems (Web clusters) because of their scalability and cost-effectiveness instead of one Web server with high performance. The task assignment policy, in such systems, focuses on the manner of assigning the tasks that reach these systems (e.g. the case of intensive requests that reach the distribu...

We consider the problem of optimal routing of arriving packets into N servers having no waiting room. Packets that are routed to a busy server are lost. We consider two problems where the objective is to maximize the expected throughput (or equivalently, minimize the loss rate). We assume that the controller has no information on the state of the server. We establish the optimality of the so ca...

Modern service systems, like cloud computing platforms or data center environments, commonly face a high degree of heterogeneity. This heterogeneity is not only caused by different server speeds but also, binding task-server relations that must be taken into account when assigning incoming tasks. Unfortunately, there are hardly any theoretical performance guarantees as these systems do fall wit...

We study the dynamic power optimization problem in data centers. We formulate and solve the following offline problem: in which slot which server has to be assigned to which job; and in which slot which server has to be switched ON or OFF so that the total power is optimal for some time horizon. We show that the offline problem is a new version of generalized assignment problem including new co...

Information about the secondary and tertiary structure of a protein sequence can greatly assist biologists in the generation and testing of hypotheses, as well as design of experiments. The PROTINFO server enables users to submit a protein sequence and request a prediction of the three-dimensional (tertiary) structure based on comparative modeling, fold generation and de novo methods developed ...