37291002
Subdivision Depth Computation for Extra-Ordinary Catmull-Clark Subdivision Surface Patches
A second order forward differences based subdivision depth computation technique for extra-ordinary Catmull-Clark subdivision surface (CCSS) patches is presented. The new technique improves a previous technique in that the computation of the subdivision depth is based on the patch's curvature distribution, instead of its dimension. Hence, with the new technique, no excessive subdivision is needed for extra-ordinary CCSS patches to meet the precision requirement and, consequently, one can make trimming, finite element mesh generation, boolean operations, and tessellation of CCSSs more efficient.
7377259
Matrix Based Subdivision Depth Computation for Extra-Ordinary Catmull-Clark Subdivision Surface Patches
A new subdivision depth computation technique for extra-ordinary Catmull-Clark subdivision surface (CCSS) patches is presented. The new technique improves a previous technique by using a matrix representation of the second order norm in the computation process. This enables us to get a more precise estimate of the rate of convergence of the second order norm of an extra-ordinary CCSS patch and, consequently, a more precise subdivision depth for a given error tolerance.
5646533
A 0-1 LP Model for the Integration and Consolidation of Air Cargo Shipments
This paper addresses the problem of determining the optimal integrations and consolidations of air cargo shipments. A freight forwarder arranges for the execution of many jobs (shipments) on behalf of several clients. Each job consists of a number of sequential activities, such as pickup, truck transportation, warehousing, and air transportation. Each activity can be performed by a number of processing units, such as trucking companies, warehouses, and airlines. If a number of consecutive activities of a job are integrated, i.e., performed by the same processing unit, then it typically costs less. If a number of similar activities of different jobs are consolidated, i.e., performed by the same processing unit, then it also typically costs less. Given a number of jobs and processing units, the sets of activities that can be integrated and consolidated, and the associated costs, the decision problem is to determine which processing unit should perform each activity of each job to minimize the total cost. This problem of assigning shipment activities to processing units is formulated as a linear 0--1 program. Principal properties of the model are established. Exploiting the special structure of this model, we design a solution procedure that includes heuristics and a branch-and-bound algorithm.
17872919
Extremal search of decision policies for scalable distributed applications
The ongoing trend of constructing open, scalable distributed systems such as peer-to-peer (P2P) systems demands for effective tools to manage the interactions between constituent entities (or nodes). One such tool is through imposing decision policies at the network level. However very few techniques are available to allow computers autonomously identify good policies with limited human intervention. In this paper, we propose an Extremal Programming (EP) algorithm to achieve automatic policy identification. The algorithm is inspired by recent advances in understanding far from equilibrium phenomena in terms of self-organized criticality (SOC). The effectiveness of EP is evaluated through a P2P application called location-aware video streaming (LAVS). The simulation studies in LAVS demonstrate that with EP, the fast and effective sharing of video streams is achieved.
8202363
Coordinated Services Provision in Peer-to-Peer Environments
In recent years, inspired by the emerging Web services standard and peer-to-peer technology, a new federated service providing (FSP) system paradigm has attracted increasing research interests. Many existing systems have either explicitly or implicitly followed this paradigm. Instead of exchanging files, peers in FSP systems share their computation resources in order to offer domain-specific services. In this paper, we focused on the coordination problem of how to self-organize the service group structures in response to the varying service demand. We presented our solution in the form of a coordination mechanism, which includes a labor-market model, a recruiting protocol, and a policy-driven decision architecture. Peers make their service providing decisions based on their local policies, which can be added, removed, or modified by users. A general methodology is introduced in this paper to facilitate policy design. Specifically, a heuristic inspired by the extremal optimization technique is utilized to handle potential inconsistencies among policies. A stimulus-response mechanism was further applied to make the decision process adjustable. Experiments under five application scenarios verified our ideas and demonstrated the effectiveness of our coordination mechanism.
6983597
A Comparative Study of Parallel Prefix Adders in FPGA Implementation of EAC
Several regular parallel trees have been proposed over the years to optimize logic depth, area, fan-out and in- terconnect count for logic circuits. In this paper, we propose a comparative study of different parallel prefix trees used in the design of a new end-around carry (EAC) adder targeting FPGA technology. This new adder is based on the fast 128-bit binary floating-point EAC adder which has been implemented in the IBM POWER6 microprocessor's fused multiply-add unit. The parallel prefix tree implemented on the IBM's EAC adder is a Kogge-Stone tree which has been chosen for its high performance and its low power consumption. Our comparative study highlights the main performance differences among fourteen different architecture configurations when targeting an FPGA EAC adder design. We focus on the area requirements and the critical path delay of these designs. Our experimental results show that there is one architecture configuration with the lower area requirement and the higher performance.
30040964
Agent-Mediated Genetic Super-Scheduling in Grid Environments
Super-scheduling in a dynamic grid environment is a very challenging issue that remains to be solved before a grid can be deployed and effectively utilized. In this paper we investigate a paradigm based on genetic algorithms (GA) to efficiently solve the scheduling problem. This GA paradigm is architecturally combined with the multiagent system (MAS) paradigm to form a flexible super-scheduling system. A three-layered scheduling architecture is presented and the corresponding realization of a multiagent-based system is described. The experiment shows that the better scheduling results are obtained for the adopted metrics of flow time and job stretch.