检索结果-南通市图书馆

PAIDD:a hybrid P2P-based architecture for improving data distribution in social networks

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2014年第4期57卷 96-106页

作者： SHUANG Kai su sen State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

Rapid growth in social networks(SNs)presents a unique scalability challenge for SN operators because of the massive amounts of data distribution among large number of concurrent online users.A request from any user may trigger hundreds of server activities to generate a customized page and which has already become a huge *** on the theoretical model and analytical study considering realistic network scenarios,this article proposes a hybrid P2P-based architecture called *** fulfills effective data distribution primarily through P2P connectivity and social graph among users but with the help of central *** increase system efficiency,PAIDD performs optimized content prefetching based on social interactions among *** chooses interaction as the criteria because user’s interaction graph is measured to be much smaller than the social *** experiments confirm that PAIDD ensures satisfactory user experience without incurring extensive overhead on clients’*** importantly,PAIDD can effectively achieve one order of magnitude of load reduction at central servers.

关键词： social network data distribution PAIDD hybrid P2P-based interaction-oriented

Model of Forming-Accretion on Blast Furnace Copper Stave and Industrial Application

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第7期19卷 1-5页

作者： WU Tong CHENG su-sen School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

Copper staves have been equipped on nearly all of BF （blast furnaces） with volume over than 1000 m3 in China since their introduction from abroad about more than 10 years ago. Because of short application and lack of experience, phenomena of thickened or naked of copper stave happen occasionally which influence production severely. So it is important to study the model of forming-accretion on BF copper stave and realize real-time monitoring of forming-accretion on different copper staves. Therefore, mathematic model of calculating accretion thickness by heat flow of BF is proposed, and the calculated results indicate that accretion thickness could be kept at a reasonable range of around 50 mm by controlling heat flux around 22.0 kW/mz. The monitoring program based on the model was applied to a certain BF in China successfully, and it is found that slip of BF near the inner wall is one of most important reasons that cause fluctuation of accretion thickness. During the period of scheduled maintenance of the certain BF, the thickness of accretion measured through the static pressure holes is in good accordance with the value calculated by the monitoring program, so the results calculated by the monitoring program can be used to guide industrial production

关键词： blast furnace copper stave forming-accretion monitor industrial application

Cost-Aware Multi-Domain Virtual Data Center Embedding

在线全文

学校读者我要写书评

暂无评论

China Communications 2018年第12期15卷 190-207页

作者： Xiao Ma Zhongbao Zhang sen su State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications

Virtual data center is a new form of cloud computing concept applied to data center. As one of the most important challenges, virtual data center embedding problem has attracted much attention from researchers. In data centers, energy issue is very important for the reality that data center energy consumption has increased by dozens of times in the last decade. In this paper, we are concerned about the cost-aware multi-domain virtual data center embedding problem. In order to solve this problem, this paper first addresses the energy consumption model. The model includes the energy consumption model of the virtual machine node and the virtual switch node, to quantify the energy consumption in the virtual data center embedding process. Based on the energy consumption model above, this paper presents a heuristic algorithm for cost-aware multi-domain virtual data center embedding. The algorithm consists of two steps: inter-domain embedding and intra-domain embedding. Inter-domain virtual data center embedding refers to dividing virtual data center requests into several slices to select the appropriate single data center. Intra-domain virtual data center refers to embedding virtual data center requests in each data center. We first propose an inter-domain virtual data center embedding algorithm based on label propagation to select the appropriate single data center. We then propose a cost-aware virtual data center embedding algorithm to perform the intra-domain data center embedding. Extensive simulation results show that our proposed algorithm in this paper can effectively reduce the energy consumption while ensuring the success ratio of embedding.

关键词： virtual data center embedding multi-domain cost-aware label propagation

Hybrid QoS-aware semantic web service composition strategies

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2008年第11期51卷 1822-1840页

作者： YANG FangChun su sen LI Zhen State Key Lab of Networking & Switching Beijing University of Posts & Telecommunications Beijing100088 China

Hybrid QoS model which consists of certain and uncertain expressions has strong power of semantic QoS description. For solving the hybrid QoS-aware semantic web service composition problem, this paper presents an Uncertain Multi-attribute decision making based Composition algorithm （UMC）. The UMC includes two parts. First, UMC-Core can be used to synthetically evaluate the hybrid service quality information. Second, UMC-DH （Distributed and Heuristic framework for UMC） aims at enhancing the run-time performance of UMC when the problem space increases. The simulation results show that the UMC has lower execution cost, higher approximation ratio and success ratio than other similar approaches.

关键词： quality of service (QoS) semantic web service service composition theory of uncertainties multi-attribute decision making theory heuristic algorithm

Iterative selection algorithm for service composition in distributed environments

在线全文

学校读者我要写书评

暂无评论

Science in China(Series F) 2008年第11期51卷 1841-1856页

作者： su sen LI Fei YANG FangChun State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

In service oriented architecture （SOA）, service composition is a promising way to create new services. However, some technical challenges are hindering the application of service composition. One of the greatest challenges for composite service provider is to select a set of services to instantiate composite service with end- to-end quality of service （QoS） assurance across different autonomous networks and business regions. This paper presents an iterative service selection algorithm for quality driven service composition. The algorithm runs on a peer-to-peer （P2P） service execution environment--distributed intelligent service execution （DISE）, which provides scalable QoS registry, dynamic service selection and service execution services. The most significant feature of our iterative service selection algorithm is that it can work on a centralized QoS registry as well as cross decentralized ones. Network status is an optional factor in our QoS model and selection algorithm. The algorithm iteratively selects services following service execution order, so it can be applied either before service execution or at service run-time without any modification. We test our algorithm with a series of experiments on DISE. Experimental results illustrated its excellent selection and outstanding performance.

关键词： web service quality of service (QoS) service selection algorithm distributed QoS registry

GPSA:A Greedy Pull-based Scheduling Approach for P2P Live Streaming under Heterogeneous Environments

在线全文

学校读者我要写书评

暂无评论

China Communications 2010年第2期7卷 42-52页

作者： Chen Wei su sen Yang Fangchun Shuang Kai State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

Pull-based P2P live streaming is a promising solution for the large scale streaming systems, like PPStream, PPlive, due to its high scalability, low cost and high resilience. However, they usually suffer from bad delay performance. In this paper, we seek to improve the delay performance under ensuring video display quality stemming from chunk scheduling. And so we model Pull-based chunk scheduling problem as a multi-objective optimization problem to minimize the video delay and maximize video display quality in the environment of heterogeneous upload bandwidths, heterogeneous and dynamic propagation delays. Finally we put up with a greedy Pull-based scheduling approach(GPSA) to solve the optimization problem. The evaluation shows GPSA can outperform two classical chunk scheduling approaches and adapt to dynamic variance of propagation delays.

关键词： P2P live streaming pull-based scheduling heterogeneous environments delay performaDce

Monitoring Method for Blast Furnace Wall With Copper Staves

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2007年第4期14卷 1-5页

作者： CHENG su-sen QIAN Liang ZHAO Hong-bo School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China CCTEC Engineering Co Ltd Beijing 100081 China

A monitoring method that has been designed for the first time for blast furnace wall with copper staves manufactured in China was introduced. Combining the method of ＂inverse problem＂ and the concept ＂non-inverse problem＂, the monitoring program for blast furnace wall with copper staves has been realized, which can be used to calculate online the accretion thickness and temperature of hot surface of copper staves after obtaining the values of thermocouples of copper staves. The accretion state obtained in the actual investigation has proved that the result of the program is correct. The monitoring program shows that the accretion would easily fluctuate when the accretion layer is extremely thick or thin, thereby the stable and smooth operation of the blast furnace is hindered. By maintaining appropriate accretion thickness, both long campaigns and high productivity of the blast furnace can be achieved; furthermore, it can also optimize the operation of blast furnace and maximize its production. Approximately 30--50 mm in thickness of accretion layer is maintained on the wall of Shougang blast furnace 2, which can meet the requirement for obtaining both long campaign and high productivity.

关键词： blast furnace copper stave wall monitoring accretion long campaign high productivity

Characterization of shear stresses in nickel-based superalloy Mar-M247 when orthogonal machining with coated carbide tools

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2014年第3期21卷 862-869页

作者： CHEN Shao-hsien su sen-chieh JEHNG Wern-dare Department of Mechanical Engineering Chin-Yi University of Technology Department of Mechanical Engineering Chung Cheng University

Mar-M247 is a nickel-based alloy which is well known as difficult-to-machine material due to its characteristics of high strength, poor thermal diffusion and work hardening. Calculation of shear stress by an analytical force model to indicate the effect of coating material, cutting speed, feed rate on tool life and surface roughness was conducted experimentally. Cutting tests were performed using round inserts, with cutting speeds ranging from 50 to 300 rn/min, and feed rates from 0.1 to 0.4 mm/tooth, without using cooling liquids. The behavior of the TiN and TiCN layers using various cutting conditions was analyzed with orthogonal machining force model. Cutting results indicate that different coated tools, together with cutting variables, play a significant role in determining the machinability when milling Mar-M247.

关键词： Mar-M247 tool wear orthogonal machining shear stress

Heat Saturation Time of Solid Spherical Regenerator of HTAC

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2006年第2期13卷 10-13页

作者： LU Qing-heng CHENG su-sen YANG Tian-jun Metallurgy Engineering School University of Science and Technology Beijing Beijing 100083 China

In order to control the heat saturation time, the temperature field of the regenerators of high temperature air combustion （HTAC） technology after reheating furnace was studied. A one-dimensional unsteady mathematical model was established and discretized through finite difference method. The relationship between the heat saturation time and some factors was determined through the calculation of a program developed by language C. The heat saturation time decreases with the increase of heat convection coefficient, however, the increase of heat capacity, density and radius of regenerator all increase the heat saturation time approximately linearly.

关键词： solid spherical regenerator heat saturation time mathematical model