As a promising solution to tackle the network heterogeneity in multicasting, layered multicast protocols such as Receiver-driven layered multicast (RLM) and Layered video multicast with retransmission (LVMR) have been proposed. This paper considers fairness as well as transmission load in the layered multicasting. Lexicographically fair bandwidth allocation among multicast receivers is considered under the constraint of minimum bandwidth requirement and the link capacity of the network. The problem of transmission load in the layer multicasting due to various user requirements is also examined by minimizing the number of layers.The bandwidth allocation is formulated as a nonlinear integer programming problem. A dual objective tabu search is proposed to solve the fairness and transmission load problem in multicast networks. Outstanding performance is obtained by the proposed tabu search. When the fairness objective is considered, the solution gap from the optimal solution is less than 2% in problems with 50 virtual sessions. The complexity of the dual objective largely depends on the weighting factor of the two objectives. Even in tough cases the proposed tabu search provides excellent solution the gap of which is within 6% from the optimal solution.

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This paper promotes the general paradigm that a composite's internal structure can be micro-tailored to achieve a multifunctional physical response through the use of the Field Aided Micro Tailoring (FAiMTa) technique. The FAiMTa technique relies on curing a polymer composite while in its liquid state in the presence of an electric field. The particles within the composite align themselves in the direction of the electric field and create an orthotropic composite structure. This technology can lead to composite materials having a micro-tailored structure mimicking biological systems. As an initial step towards this goal, uniformly orthotropic composites, which are prepared by the FAiMTa technique, are mechanically characterized. Two epoxy based systems are considered: a composite having micro-sized graphite particles whereas the other has micro-sized aluminum particles. Mechanical tests show the change of material properties according to direction of the particle alignment within the composite. Optical microscopy also confirms the created orthotropic microstructure. The next step in development of FAiMTa technique is the reduction of stress concentration near a geometric discontinuity by properly orienting particulate structures within the composite. Our ongoing efforts toward optimization of the composites are briefly outlined.

Overlay multicast makes use of the Internet as a low level infrastructure to provide multicast service to end hosts. The strategy of overlay multicast slides over most of the basic deployment issues associated with IP multicast, such as end-to-end reliability, flow and congestion control, and assignment of an unique address for each multicasting group.Since each multicast member is responsible for forwarding multicast packets, overlay multicast protocols suffer from multicast node failures. To cope with node failures in the overlay multicast networks, the employment of multicast service nodes (MSNs) is considered which allows relatively high processing performance to cover the disconnected nodes. We are interested in minimizing the cost of both the MSNs and additional links when a node failure occurs.Overlay multicast tree rearrangement to connect multicast members is discussed and formulated as a binary integer programming problem. The tree rearrangement problem is solved by a heuristic based on the Lagrangean relaxation. The performance of the proposed algorithm is investigated by carrying out experiments in 50 and 100 node problems. The employment of MSNs is illustrated to be dependent on the end-to-end delay bound in overlay networks and the degree constraint of member nodes.1

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