• 제목/요약/키워드: optimization scheme

검색결과 1,157건 처리시간 0.027초

모바일 애드 혹 스트리밍 서비스를 위한 프록시 기반 캐싱 최적화 (Proxy-based Caching Optimization for Mobile Ad Hoc Streaming Services)

  • 이종득
    • 디지털융복합연구
    • /
    • 제10권4호
    • /
    • pp.207-215
    • /
    • 2012
  • 본 논문에서는 무선 모바일 애드 혹 네트워크상에서 스트리밍 미디어 서비스 향상을 위한 프록시 기반 캐싱 최적화 기법을 제안한다. 제안된 기법은 WLAN상에서 미디어 서버와 노드들 간의 통신을 위해 프록시를 사용하며, 프록시는 무선 엑세스 포인터 근처에 설치한다. 그리고 캐싱 최적화가 수행되도록 NFCO(non-full cache optimization)과 CFO(cache full optimization)기법을 제안한다. NFCO와 CFO는 프록시에서 스트리밍이 수행될 때 캐시의 성능을 최적화하기 위해 사용된다. 제안된 기법의 성능을 알아보기 위하여 본 논문에서는 제안된 기법과 서버-중심 스트리밍 기법, 그리고 전송율 왜곡 스트리밍 기법과의 성능을 비교 분석하였다. 그 결과 제안된 기법이 서버-중심 스트리밍 기법과 전송율 왜곡 스트리밍 기법에 비해서 최적화 성능이 우수함을 알게 되었다.

MOPSO-based Data Scheduling Scheme for P2P Streaming Systems

  • Liu, Pingshan;Fan, Yaqing;Xiong, Xiaoyi;Wen, Yimin;Lu, Dianjie
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • 제13권10호
    • /
    • pp.5013-5034
    • /
    • 2019
  • In the Peer-to-Peer (P2P) streaming systems, peers randomly form a network overlay to share video resources with a data scheduling scheme. A data scheduling scheme can have a great impact on system performance, which should achieve two optimal objectives at the same time ideally. The two optimization objectives are to improve the perceived video quality and maximize the network throughput, respectively. Maximizing network throughput means improving the utilization of peer's upload bandwidth. However, maximizing network throughput will result in a reduction in the perceived video quality, and vice versa. Therefore, to achieve the above two objects simultaneously, we proposed a new data scheduling scheme based on multi-objective particle swarm optimization data scheduling scheme, called MOPSO-DS scheme. To design the MOPSO-DS scheme, we first formulated the data scheduling optimization problem as a multi-objective optimization problem. Then, a multi-objective particle swarm optimization algorithm is proposed by encoding the neighbors of peers as the position vector of the particles. Through extensive simulations, we demonstrated the MOPSO-DS scheme could improve the system performance effectively.

Improved AP Deployment Optimization Scheme Based on Multi-objective Particle Swarm Optimization Algorithm

  • Kong, Zhengyu;Wu, Duanpo;Jin, Xinyu;Cen, Shuwei;Dong, Fang
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • 제15권4호
    • /
    • pp.1568-1589
    • /
    • 2021
  • Deployment of access point (AP) is a problem that must be considered in network planning. However, this problem is usually a NP-hard problem which is difficult to directly reach optimal solution. Thus, improved AP deployment optimization scheme based on swarm intelligence algorithm is proposed to research on this problem. First, the scheme estimates the number of APs. Second, the multi-objective particle swarm optimization (MOPSO) algorithm is used to optimize the location and transmit power of APs. Finally, the greedy algorithm is used to remove the redundant APs. Comparing with multi-objective whale swarm optimization algorithm (MOWOA), particle swarm optimization (PSO) and grey wolf optimization (GWO), the proposed deployment scheme can reduce AP's transmit power and improves energy efficiency under different numbers of users. From the experimental results, the proposed deployment scheme can reduce transmit power about 2%-7% and increase energy efficiency about 2%-25%, comparing with MOWOA. In addition, the proposed deployment scheme can reduce transmit power at most 50% and increase energy efficiency at most 200%, comparing with PSO and GWO.

Machine learning-enabled parameterization scheme for aerodynamic shape optimization of wind-sensitive structures: A-proof-of-concept study

  • Shaopeng Li;Brian M. Phillips;Zhaoshuo Jiang
    • Wind and Structures
    • /
    • 제39권3호
    • /
    • pp.175-190
    • /
    • 2024
  • Aerodynamic shape optimization is very useful for enhancing the performance of wind-sensitive structures. However, shape parameterization, as the first step in the pipeline of aerodynamic shape optimization, still heavily depends on empirical judgment. If not done properly, the resulting small design space may fail to cover many promising shapes, and hence hinder realizing the full potential of aerodynamic shape optimization. To this end, developing a novel shape parameterization scheme that can reflect real-world complexities while being simple enough for the subsequent optimization process is important. This study proposes a machine learning-based scheme that can automatically learn a low-dimensional latent representation of complex aerodynamic shapes for bluff-body wind-sensitive structures. The resulting latent representation (as design variables for aerodynamic shape optimization) is composed of both discrete and continuous variables, which are embedded in a hierarchy structure. In addition to being intuitive and interpretable, the mixed discrete and continuous variables with the hierarchy structure allow stakeholders to narrow the search space selectively based on their interests. As a proof-of-concept study, shape parameterization examples of tall building cross sections are used to demonstrate the promising features of the proposed scheme and guide future investigations on data-driven parameterization for aerodynamic shape optimization of wind-sensitive structures.

Opportunistic Reporting-based Sensing-Reporting-Throughput Optimization Scheme for Cooperative Cognitive Radio Networks

  • So, Jaewoo
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • 제11권3호
    • /
    • pp.1319-1335
    • /
    • 2017
  • This paper proposes an opportunistic reporting-based sensing-reporting-throughput optimization scheme that maximizes the spectral efficiency of secondary users (SUs) in cooperative cognitive radio networks with a soft combining rule. The performance of cooperative spectrum sensing depends on the sensing time, the reporting time of transmitting sensing results, and the fusion scheme. While longer sensing time and reporting time improve the sensing performance, this shortens the allowable data transmission time, which in turn degrades the spectral efficiency of SUs. The proposed scheme adopts an opportunistic reporting scheme to restrain the reporting overhead and it jointly controls the sensing-reporting overhead in order to increase the spectral efficiency of SUs. We show that there is a trade-off between the spectral efficiency of SUs and the overheads of cooperative spectrum sensing. The numerical results demonstrate that the proposed scheme significantly outperforms the conventional sensing-throughput optimization schemes when there are many SUs. Moreover, the numerical results show that the sensing-reporting time should be jointly optimized in order to maximize the spectral efficiency of SUs.

자동차 후드의 정강성을 고려한 위상 최적화 (Topology Optimization of a Vehicle's Hood Considering Static Stiffness)

  • 한석영;최상혁;박재용;황준성;김민수
    • 한국공작기계학회논문집
    • /
    • 제16권1호
    • /
    • pp.69-74
    • /
    • 2007
  • Topology optimization of the inner reinforcement for a vehicle's hood has been performed by evolutionary structural optimization(ESO) using a smoothing scheme. The purpose of this study is to obtain optimal topology of the inner reinforcement for a vehicle's hood considering the static stiffness of bending and torsion simultaneously. To do this, the multiobjective optimization technique was implemented. Optimal topologies were obtained by the ESO method. From several combinations of weighting factors, a Pareto-optimal solution was obtained. Also, a smoothing scheme was implemented to suppress the checkerboard pattern in the procedure of topology optimization. It is concluded that ESO method with a smoothing scheme is effectively applied to topology optimization of the inner reinforcement of a vehicle's hood considering the static stiffness of bending and torsion.

Inter-MAG이 고려된 PMIPv6 환경에서 전달자 정보를 이용한 경로 최적화 기법에 관한 연구 (A Study on Route Optimization Scheme using Correspondent Information for in the PMIPv6 considering Inter-MAG)

  • 최영현;박민우;엄정호;정태명
    • 디지털산업정보학회논문지
    • /
    • 제6권3호
    • /
    • pp.59-68
    • /
    • 2010
  • In the paper, we proposed the Using Correspondent Information for Route Optimization on PMIPv6 over Inter-MAG. Proxy Mobile IPv6 has the problem that a mobile node sends data packets through inefficient routing paths when communicating other mobile node. Route optimization schemes are proposed to solve the triangle routing problem that creates the shortest routing path by leaving the inefficient routing paths. We proposed Correspondent Information Route Optimization scheme to reduce signaling cost as compared with other route optimization scheme. We can reduce signaling cost of route optimization through the Correspondent Information message on basic PMIPv6 and hand-off environment.

A New Route Optimization Scheme for Network Mobility: Combining ORC Protocol with RRH and Using Quota Mechanism

  • Kong, Ruoshan;Feng, Jing;Gao, Ren;Zhou, Huaibei
    • Journal of Communications and Networks
    • /
    • 제14권1호
    • /
    • pp.91-103
    • /
    • 2012
  • Network mobility (NEMO) based on mobile IP version 6 has been proposed for networks that move as a whole. Route optimization is one of the most important topics in the field of NEMO. The current NEMO basic support protocol defines only the basic working mode for NEMO, and the route optimization problem is not mentioned. Some optimization schemes have been proposed in recent years, but they have limitations. A new NEMO route optimization scheme-involving a combination of the optimized route cache protocol (ORC) and reverse routing header (RRH) and the use of a quota mechanism for optimized sessions (OwR)-is proposed. This scheme focuses on balanced performance in different aspects. It combines the ORC and RRH schemes, and some improvements are made in the session selection mechanism to avoid blindness during route optimization. Simulation results for OwR show great similarity with those for ORC and RRH. Generally speaking, the OwR's performance is at least as good as that of the RRH, and besides, the OwR scheme is capable of setting up optimal routing for a certain number of sessions, so the performance can be improved and the cost of optimal routing in nested NEMO can be decreased.

근사 최적화 기법을 이용한 3차원 압출공정에서 플로우 가이드 형상의 최적 설계 (Design Optimization of Flow Guide by an Approximation Approach in Three-dimensional Extrusion Processes)

  • 이석렬;양동열
    • 한국소성가공학회:학술대회논문집
    • /
    • 한국소성가공학회 2004년도 춘계학술대회 논문집
    • /
    • pp.19-22
    • /
    • 2004
  • A scheme of shape optimization by new approximation approach is applied to design of a flow guide in three-dimensional extrusion processes. The optimization scheme is presented to reduce computation time fur the optimization process and applied to an H-section extrusion problem for verifying the efficiency and the usefulness. The object of optimization is to minimize the deviation of exit velocity and control points of a Bezier curve describing the shape of the flow guide are regarded as design variables. The effectiveness of the proposed scheme is then demonstrated through the applied example.

  • PDF

분산 메모리 시스템에서의 병렬 위상 최적설계 (Parallel Topology Optimization on Distributed Memory System)

  • 이기명;조선호
    • 한국전산구조공학회:학술대회논문집
    • /
    • 한국전산구조공학회 2006년도 정기 학술대회 논문집
    • /
    • pp.291-298
    • /
    • 2006
  • A parallelized topology design optimization method is developed on a distributed memory system. The parallelization is based on a domain decomposition method and a boundary communication scheme. For the finite element analysis of structural responses and design sensitivities, the PCG method based on a Krylov iterative scheme is employed. Also a parallelized optimization method of optimality criteria is used to solve large-scale topology optimization problems. Through several numerical examples, the developed method shows efficient and acceptable topology optimization results for the large-scale problems.

  • PDF