检索结果-南通市图书馆

Regioselective aminohalogenation of β-nitrostyrenes using NCS and NBS as nitrogen/halogen sources

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

science china Chemistry 2010年第1期53卷 140-146页

作者： ZHI SanJun1,2,SUN Hao2,LIN Chen2,ZHANG GuangQian2,LI GuiGen4 & PAN Yi2,3 1 Department of Chemistry,Huaiyin normal university,Huai’an 221003,china 2 school of Chemistry and Chemical Engineering,nanjing university,nanjing 210093,china 3 State Key Lab of Coordination Chemistry,nanjing university,nanjing 210093,china 4 Department of Chemistry and Biochemistry,Texas Tech university,Lubbock,Texas 79409-1061,USA 1. Department of Chemistry Huaiyin Normal University Huai’an 221003 China2. School of Chemistry and Chemical Engineering Nanjing University Nanjing 210093 China4. Department of Chemistry and Biochemistry Texas Tech University Lubbock Texas 79409-1061 USA3. State Key Lab of Coordination Chemistry Nanjing University Nanjing 210093 China

Aminohalogenation reaction of β-nitrostyrenes with N-halosuccinimides(N-chloro and N-bromosuccinimides) has been successfully conducted by using nickel acetate as a catalyst in the presence of potassium carbonate and succinimide as *** reaction was easily performed at room temperature under nitrogen gas protection to give dihalorinaed haloamino products in good to excellent yields(60%-98%).The structure has been confirmed by X-ray crystal structure analysis.

关键词： aminohalogenation vicinal haloamines β-nitrostyrenes NBS NCS

Travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2011年第3期54卷 555-572页

作者： DENG ShengFu1, GUO BoLing2 & WANG TingChun2,3 1Department of mathematics, Zhanjiang normal university, Zhanjiang 524048, china 2Institute of Applied Physics and Computational mathematics, Beijing 100088, china 3 College of Math and Physics, nanjing university of Information science and Technology, nanjing 210044, china 1. Department of mathematics Zhanjiang Normal University Zhanjiang 524048 China2. Institute of Applied Physics and Computational Mathematics Beijing 100088 China3. College of Math and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The travelling wave solutions of a generalized Camassa-Holm-Degasperis-Procesi equation ut-uxxt + (1 + b)umux = buxuxx + uuxxx are considered where b > 1 and m are positive integers. The qualitative analysis methods of planar autonomous systems yield its phase portraits. Its soliton wave solutions, kink or antikink wave solutions, peakon wave solutions, compacton wave solutions, periodic wave solutions and periodic cusp wave solutions are obtained. Some numerical simulations of these solutions are also given.

关键词： homoclinic orbits heteroclinic orbits peakon wave solutions compacton wave solutions periodic cusp wave solutions

QoS routing based on mobile agent for LEO satellite IP networks

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2009年第6期16卷 57-63页

作者： RAO Yuan,WANG Ru-chuan College of computer,nanjing university of Posts and Telecommunications,nanjing 230001,china [a] College of computer nanjing university of Posts and Telecommunications nanjing 230001 china

Current quality of service（QoS） routing schemes for low earth orbit（LEO） satellites IP networks either neglect the varying population density or fail to guarantee end-to-end *** a remedy,QoS routing protocol based on mobile agent（QoSRP-MA） is ***-MA is a source-based routing *** connection requests arrive,QoS mobile agents are dispatched from ingress satellite to explore routes,which migrate using satellite routing *** arriving in egress satellite,QoS mobile agents migrate back towards ingress satellite to reserve *** construct satellite routing tables,load balancing routing algorithm based on mobile agent（LBRA-MA） is *** LBRP-MA,at regular intervals mobile agents launched on all satellites migrate autonomously to evaluate path cost and update routing ***,path cost between source and destination is evaluated considering satellite geographical position as well as inter-satellite link（ISL） ***,ISL congestion index is considered to update routing *** simulations on a Courier-like constellation,it shows that QoSRP-MA can achieve guaranteed end-to-end delay bound with higher throughput,lower connection failing ratio and signaling overhead compared to high performance satellite routing（HPSR） scheme.

关键词： QoS routing load balancing mobile agent satellite IP networks

△-tame quasi-hereditary algebras

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2007年第2期50卷 240-252页

作者： Yun-ge XU & Ying-bo ZHANG Faculty of mathematics and computer science, Hubei university, Wuhan 430062, china school of mathematics sciences, Beijing normal university, Beijing 100875, china Faculty of mathematics and computer science Hubei University Wuhan China school of mathematics sciences Beijing Normal University Beijing China

Let (K, M,H) be an upper triangular bimodule problem. Briistle and Hille showed that the opposite algebra A of the endomorphism algebra of a projective generator P of the matrices category of (K., M, H) is quasi-hereditary, and there is an equivalence between the category of△-good modules of A and Mat(K, M). In this note, based on the tame theorem for bimodule problems, we show that if the algebra A associated with an upper triangular bimodule problem is of△-tame representation type, then the category F(△) has the homogeneous property, i.e. almost all modules in F(△) are isomorphic to their Auslander-Reiten translations. Moreover, if (K, M,H)is an upper triangular bipartite bimodule problem, then A is of△-tame representation type if and only if F(△) is homogeneous.

关键词： bimodule problem quasi-hereditary algebra △-tameness homogeneity.

Distributed GEP query optimization on grid service

在线全文

学校读者我要写书评

暂无评论

The Journal of china Universities of Posts and Telecommunications 2010年第3期17卷 118-122,128页

作者： DENG Yong, WANG Ru-chuan College of computer, nanjing university of Posts and Telecommunications, nanjing 210003, china [a] College of computer Nanjing University of Posts Telecommunications Nanjing 210003 China

In order to better solve the problem of distributed query optimization, a query optimization algorithm on gene expression programming （GEP）（QO-GEP） is presented. On the basis of QO-GEP, distributed GEP query optimization on grid service （DGEPQO-GS） is proposed which combines grid service. Simulated experiments show that with the increment of the number of query relation, query time which QO-GEP carries out query decreases apparently. Meanwhile, with the increase of the number of grid nodes, the average querying success rate of DGEPQO-GS increases significantly.

关键词： gene expression programming distributed query grid service query relation

Alkali-silica Reactivity of Different Aggregates from Mineral and Textural Characteristics

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of Technology(Materials science) 2008年第6期23卷 901-906页

作者：莫祥银 Analysis and Testing Center & Jiangsu Key Laboratory of Biofunctional Materials Nanjing Normal University

To identify the aggregates causing the alkali-silica reaction, and the reactivity of rocks in different parts of china, the mineral and texture characteristics of some typical coarse ag gregates and the alkali reactivity of these aggregates were systematically investigated. On one hand, petrographic examination of aggregates, combined with X-ray diffraction analysis, chemical analysis, scanning electron microscopy, was conducted for analyzing their mineralogy and texture. It was found that not only mineral characteristics, but also their interior structure would affect their potential alkali-silica reactivity. Furthermore, the alkali-silica reactivity of aggregates is due to their mineral compositions, such as containing different alkali-reactive minerals, while, different stuctures of those aggregates with similar minerals affect their reactivity to some extent. There are some amount of micro-aperture and cracks across the quartz in the aggregate, which may become the natural accesses for Na^＋, K^＋, and OH^- ions to intrude in the mortar or concrete during the process of alkali-silica reaction. Alkali-silica reactivity of the aggregates was detected by the accelerated mortar bars test. It was revealed that all the aggregates tested were alkali-silica reactive and the results were also in accordance with their mineral and structure analysis.

关键词： petrographic examination of aggregates study of thin sections x-ray diffraction analysis chemical analysis scanning electron microscopy

Non-blocking message total ordering protocol

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12期51卷 1919-1934页

作者： WANG Yun & WANG JunLing school of computer science & Engineering, Southeast university Key Lab of computer Network & Information Integration, MOE, nanjing 210096, china 1. school of computer science & Engineering Southeast University Key Lab of computer Network & Information Integration MOE Nanjing 210096 China

Message total ordering is a critical part in active replication in order to maintain consistency among members in a fault tolerant group. The paper proposes a non-blocking message total ordering protocol （NBTOP） for distributed systems. Non-blocking property refers to that the members in a fault tolerant group keep on running independently without waiting for installing the same group view when a fault tolerant group evolves even when decision messages collide. NBTOP takes advantage of token ring as its logical control way. Members adopt re-requesting mechanism （RR） to obtain their lost decisions. Forward acknowledgement mechanism （FA） is put forth to solve decision collisions. The paper further proves that NBTOP satisfies the properties of total order, agreement, and termination. NBTOP is implemented, and its performance test is done. Comparing with the performance of Totem, the results show that NBTOP has a better total ordering delay. It manifests that non-blocking property helps to improve protocol efficiency.

关键词： total ordering protocol non-blocking active replication fault tolerance token ring

A note on the crossed product R(A, α) associated with PSL_2(R)

在线全文

学校读者我要写书评

暂无评论

science china mathematics 2008年第11期51卷 2081-2088页

作者： WU WenMing 1 school of Mathematical and computer science, Chongqing normal university, Chongqing 400047, china 2 Department of Mathematical science, Tsinghua university, Beijing 100084, china school of Mathematical and computer science Chongqing Normal University Chongqing China Department of Mathematical science Tsinghua University Beijing China

Given the hyperbolic measure dxdy/y2 on the upper half plane H, the rational actions of PSL2(R) on H induces a continuous unitary representation α of this group on the Hilbert space L2(H, dxdy/y2). Supposing that A = {Mf : f ∈ L∞(H, dxdy/y2)}, we show that the crossed product R(A,α) is of type I. In fact, the crossed product R(A,α) is *-isomorphic to the von Neumann algebra B(L2(P,ν))■LK, where LK is the abelian group von Neumann algebra generated by the left regular representation of K.

关键词： crossed product rational actions PSL2(R) von Neumann algebras

P2P traffic optimization

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

science china(Information sciences) 2012年第7期55卷 1475-1492页

作者： ZHANG GuoQiang 1,2 ,TANG MingDong 3 ,CHENG SuQi 2,4 ,ZHANG GuoQing 2 ,SONG HaiBin 5 ,CAO JiGuang 6 & YANG Jing 7 1 school of computer science and Technology,nanjing normal university,nanjing 210046,china 2 Institute of Computing Technology,Chinese Academy of sciences,Beijing 100190,china 3 school of computer science and Engineering,Hunan university of science and Technology,Xiangtan 411201,china 4 Graduate university of Chinese Academy of sciences,Beijing 100190,china 5 nanjing R&D Center,Huawei Technologies,nanjing 210012,china 6 china Academy of Telecommunication Research of MIIT,Beijing 100191,china 7 china Mobile Research Institute,Beijing 100053,china 1. school of computer science and Technology Nanjing Normal University Nanjing 210046 China2. Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China3. School of Computer Science and Engineering Hunan University of Science and Technology Xiangtan 411201 China4. Graduate University of Chinese Academy of Sciences Beijing 100190 China5. Nanjing R&D Center Huawei Technologies Nanjing 210012 China6. China Academy of Telecommunication Research of MIIT Beijing 100191 China7. China Mobile Research Institute Beijing 100053 China

Peer-to-peer (P2P) based content distribution systems have emerged as the main form for content distribution on the Internet,which can greatly reduce the distribution cost of content providers and improve the overall system ***,the mismatch between the overlay and underlay networks causes large volume of redundant traffic,which intensifies the tension between P2P content providers and ***,how to efficiently use network resources to reduce the traffic burden on the ISPs is crucial for the sustainable development of P2P *** paper surveys the state-of-art P2P traffic optimization technologies from three perspectives:P2P cache,locality-awareness and data *** details,comparison between these technologies and their applicabilities are presented,followed by a discussion of the issues that remain to be addressed and the direction of future content distribution research.

关键词： P2P traffic localization P2P traffic optimization P2P cache locality-awareness network coding content-centric network