检索结果-南通市图书馆

Joint subcarrier and power allocation in uplink OFDMA systems based on stochastic game

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2010年第12期53卷 2557-2566页

作者： WU Dan 1,CAI YueMing 1,2 & SHENG YanMing 1 1 institute of Communications Engineering,pla university of {3. and technology,nanjing 210007,china 2 National Mobile Communications Research Laboratory,Southeast university,nanjing 210096,china 1. institute of Communications Engineering PLA University of Science and Technology Nanjing 210007 China2. National Mobile Communications Research Laboratory Southeast University Nanjing 210096 China

In uplink orthogonal frequency division multiplexing access(OFDMA) systems,efficient resource allocation can greatly improve system ***,in this paper,we present a game-theoretical approach to achieve a joint subcarrier and power allocation in a distributed ***,the subcarrier allocation problem is modeled as a multi-player discrete,stochastic and finite strategy game,where each of the subcarriers is viewed as a player to choose the most satisfying *** subcarriers of each user are allocated with equal *** the proposed game model,on the one hand,we exploit the support and programming methods to obtain the Nash equilibriums,and analyze their theoretical *** the other hand,we propose a lowcomplexity algorithm based on the linear reward-inaction(L R-I) algorithm to search for the Nash *** the relationship between the convergence results of this algorithm and the Nash equilibriums is *** simulation results demonstrate the effectiveness of the resource allocation game model and algorithm.

关键词： stochastic game OFDMA subcarrier allocation power allocation learning automata linear reward-inaction

Model tests on anomalous low friction and pendulum-type wave phenomena

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2009年第12期19卷 1805-1820页

作者： Hao Wu~*,Qin Fang,Yusheng Lu,Yadong Zhang,Jinchun Liu Engineering institute of Engineering Corps,pla university of {3. and technology,nanjing,Jiangsu 210007.china [a]Engineering institute of Engineering Corps PLA University of Science and Technology Nanjing Jiangsu 210007 China

The anomalous low friction(ALF) and pendulum-type wave(μwave) phenomena were two typical,nonlinear,geo-mechanical,and dynamic responses in deep-block rock mass discovered from in situ observations,which occurred from the movement of the geo-blocks under the impact of external pulses,such as deep confined explosion,earthquake,and rock *** the aim to confirm the existence of the above two phenomena and study the variation laws of them experimentally,laboratory tests on the granite and cement mortar continuum and blocks models were conducted on the self-independently developed multipurpose testing system,*** ALF phenomenon was realized under two loading schemes,the blocks model and working block were acted upon by the joint action of vertical impact and horizontal static force as well as the joint action of both vertical and horizontal impacts with different time *** revealed that the discrete time delays corresponding to the local maximums and minimums of the horizontal displacement amplitudes and residual horizontal displacements of the working block satisfied the canonical sequences with the multiple of 21/2,most of which satisfied the quantitative expression(21/2)~i△/***,the one-dimensional impact experiments were carried out on the blocks granite model,continuum, and blocks cement mortar models,*** on the comparison and analysis of the propagation properties(amplitudes and the Fourier spectrums of acceleration time histories of blocks) of the 1D stress wave in the above models,it is indicated that the fractures in rock mass have tremendous effect on the attenuation of acceleration amplitudes and high-frequency *** comparison of the model test data with the in situ measurement conclusions,the existence of theμwave was confirmed experimentally in the cement mortar blocks model with larger dimensions,and the frequencies corresponding to the local maximums of spectral density curves of three-directional accelera

关键词： Deep-block rock mass Block-hierarchical structure Anomalous low friction Pendulum-type wave Canonical sequence

Anisotropic thermal conductivity of magnetic fluids

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural science:Materials International 2009年第2期19卷 205-211页

作者： Xiaopeng Fang,Yimin Xuan,Qiang Li School of Power Engineering,nanjing university of science & {3.,nanjing 210094,china [a]School of Power Engineering Nanjing University of Science & Technology Nanjing 210094 China

Considering the forces acting on the particles and the motion of the particles,this study uses a numerical simulation to investigate the three-dimensional microstructure of the magnetic fluids in the presence of an external magnetic field. A method is proposed for predicting the anisotropic thermal conductivity of magnetic fluids. By introducing an anisotropic structure parameter which characterizes the non-uniform distribution of particles suspended in the magnetic fluids,the traditional Maxwell formula is modified and extended to calculate anisotropic thermal conductivity of the magnetic fluids. The results show that in the presence of an external magnetic field the magnetic nanoparticles form chainlike clusters along the direction of the external magnetic field,which leads to the fact that the thermal conduc-tivity of the magnetic fluid along the chain direction is bigger than that along other directions. The thermal conductivity of the magnetic fluids presents an anisotropic feature. With the increase of the magnetic field strength the chainlike clusters in the magnetic fluid appear to be more obvious,so that the anisotropic feature of heat conduction in the fluids becomes more evident.

关键词： Magnetic fluids Anisotropic thermal conductivity Maxwell formula

Dynamic damage and stress-strain relations of ultra-high performance cementitious composites subjected to repeated impact

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(Technological sciences) 2010年第6期53卷 1520-1525页

作者： LAI JianZhong1 & SUN Wei2 1 Department of Materials science and Engineering,nanjing university of science and technology,nanjing 210094,china 2 College of Materials science and Engineering,Southeast university,nanjing 211189,china 1. Department of Materials science and Engineering Nanjing University of Science and Technology Nanjing 210094 China2. College of Materials Science and Engineering Southeast University Nanjing 211189 China

Ultra-high performance cementitious composites (UHPCC) were prepared by replacing 60% of cement with ultra-fine industrial waste *** dynamic damage and compressive stress-strain relations of UHPCC were studied using split Hopkinson pressure bar (SHPB).The damage of UHPCC subjected to repeated impact was measured by the ultrasonic pulse velocity *** show that the dynamic damage of UHPCC increases linearly with impact times and the abilities of repeated impact resistance of UHPCC are improved with increasing fiber volume *** stress waves on impact were recorded and the average stress,strain and strain rate of UHPCC were calculated based on the wave propagation *** effects of strain rate,fibers volume fraction and impact times on the stress-strain relations of UHPCC were *** show that the peak stress and elastic modulus decrease while the strain rate and peak strain increase gradually with increasing impact times.

关键词： ultra-high performance cementitious composites (UHPCC) split Hopkinson pressure bar (SHPB) repeated impact damage stress-strain

Study on Tribological Properties of Irradiated Crosslinking UHMWPE Nano-Composite

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2009年第1期6卷 7-13页

作者： Lei Xiong, Dang-sheng Xiong, Jia-bo JinDepartment of Materials science and Engineering, nanjing university of science and technology, nanjing 210094, P. R. china [a]Department of Materials science and Engineering Nanjing University of Science and Technology Nanjing 210094 P. R. China

Ultra High Molecular Weight Polyethylene(UHMWPE)has been widely used as a bearing material for artificial joint replacement over forty *** is usually crosslinked by gamma rays irradiation before its implantation into human *** this study,UHMWPE and UHMWPE/nano-hydroxyapatite(n-HA)composite were prepared by vacuum hot-pressing *** prepared materials were irradiated by gamma rays in vacuum and molten heat treated in vacuum just after *** effect of filling n-HA with gamma irradiation on tribological properties of UHMWPE was investigated by using friction and wear experimental machine(model MM-200)under deionized water ***-morphology of worn surface was observed by metallographic *** angle and hardness of the materials were also *** results show that contact angle and hardness are changed by filling n-HA and gamma *** coefficient and wear rate under deionized water lubrication are reduced by filling *** friction coefficient is increased and wear rate is reduced significantly by gamma *** worn surface of unfilled material is mainly characterized as adhesive wear and abrasive wear,and that of n-HA filled material is mainly characterized as abrasive *** gamma irradiation,the degrees of adhesive and abrasive wear for unfilled material and abrasive wear of n-HA filled material are significantly *** and filled materials after irradiation are mainly shown as slight fatigue *** results indicate that UHMWPE and UHMWPE/n-HA irradiated at the dose of 150 kGy can be used as bearing materials in artificial joints for its excellent wear resistance compared to original UHMWPE.

关键词： tribological properties irradiated crosslinking UHMWPE n-HA artificial joints

Investigation on performance of a solar thermophotovoltaic system

在线全文

学校读者我要写书评

暂无评论

science china(Technological sciences) 2008年第12期51卷 2285-2294页

作者： CHEN Xue, XUAN YiMin & HAN YuGe School of Power Engineering, nanjing university of science & {3., nanjing 210094, china School of Power Engineering Nanjing University of Science & Technology Nanjing 210094 China

In the light of the thermo-electric conversion principle, a model for predicting the performance of a solar thermophotovoltaic system is presented. The temperature distributions of the emitter for different concentrator ratios are numerically computed and the influence of the concentrator ratio on the system performance is analyzed. Numerical results show that the emitter temperature and the system efficiency increase with increase of the concentrator ratio. The effects of some other factors such as the spectral filter, cell temperature, and the reflectivity of the top and bottom surfaces of the emitter on the conversion performance of the STPV system are discussed.

关键词： STPV emitter temperature system efficiency

Crystal structure and single crystal EPR of (NH_4)_2(15-crown-5)_3.Cu(mnt)_2] and (NH_4)_2(benzo-15-crown-5)_4[Cu(mnt)_2]·0.5H_2O

在线全文

学校读者我要写书评

暂无评论

science china Chemistry 2007年第5期50卷 607-613页

作者： SUI YunXia1, WEN LiLi2, ZHANG Huan3.& MENG QingJin2 1 Center of Modern Analysis, nanjing university, nanjing 210093.{3. 2 State Key Laboratory of Coordination Chemistry, Coordination Chemistry institute, nanjing university, nanjing 210093.{3. 3.Jiangnan institute of Computing technology, Wuxi 214083.{3. 1. Center of Modern Analysis Nanjing University Nanjing 210093 China 2. State Key Laboratory of Coordination Chemistry Coordination Chemistry Institute Nanjing University Nanjing 210093 China 3. Jiangnan institute of Computing technology Wuxi 214083 China

The X-ray crystal structures of (NH4)2(15-crown-5)3.Cu(mnt)2] (1) and(NH4)2(benzo-15-crown-5)4-[Cu(mnt)2] ident to 0.5H2O (2) were *** single crystals arecomposed of distinct structures of ammonium-crown ether supramolecular cation and [Cu(mnt)2]^(2-)*** triple-decker dication in complex 1 and a sandwich dimmer in complex 2 wereobserved.X-Band EPR studies on the single crystals of both complex 1 and complex 2 have been carriedout at room temperature,which revealed that complex 2 showed a perfect hyperfine structure of Cuwhereas that of complex 1 could not be *** principal values and direction cosines of theprincipal axes of the g and A tensors were computed by a least-squares fitting *** spindensity of Cu(ll) was estimated according to the principal values of the A tensors and compared wellwith the results calculated based on DFT method.

关键词： supramolecular cation, H-bonding interaction, EPR, g and A tensors, DFT

Research on Consistency of the Complex Interval Judgement Matrix in AHP

在线全文

学校读者我要写书评

暂无评论

Systems science and Systems Engineering 2000年第2期10卷 159-163页

作者： XU Ze\|shui pla university of science and technology, nanjing 210016, china

The weighted geometric mean method(WGMM) has been the most commonly used method in the analytic hierarchy process(AHP) for combining individual opinions to form a group opinion. In this paper, we study the consistency of the WGMM in group decision and prove that the weighted geometric mean complex interval judgement matrix (WGMIM) is of acceptable consistency under the condition that all interval matrices for the same decision\|making problem are of acceptable consistency. Thus, research on consistency of group decision in AHP is further developed and a theory basis for the application of the WGMM is also made.

关键词： the analytic hierarchy process(AHP) interval judgement matrix consistency

Communication network designing:Transmission capacity,cost and scalability

在线全文

学校读者我要写书评

暂无评论

science china(Information sciences) 2012年第11期55卷 2454-2465页

作者： ZHANG GuoQiang1,2,3.& ZHANG GuoQing1 1institute of Computing technology,Chinese Academy of sciences,Beijing 100190,{3. 2School of Computer science and technology,nanjing Normal university,nanjing 210046,{3. 3.rovincial Key Laboratory for Computer Information Processing technology,Soochow university,Suzhou 215000,{3. 1. institute of Computing technology Chinese Academy of Sciences Beijing 100190 China2. School of Computer Science and Technology Nanjing Normal University Nanjing 210046 China3. Provincial Key Laboratory for Computer Information Processing Technology Soochow University Suzhou 215000 China

Despite the growing number of works centering around the traffic dynamics on complex networks,these researches still have some common shortcomings,e.g.,too simple traffic flow model and lack of considerations for the designing cost and scalability *** paper builds on a more realistic traffic flow model,and offers a holistic view on the network designing *** addition to the extensively studied transmission capacity,this paper takes designing cost and scalability as two other designing objectives,and presents a quantitative study of how different designing choices independently and collectively influence these objectives by the introduction of a cartesian coordinate *** is shown that different kinds of network topologies display different shapes of achievable solution spaces and exhibit different abilities to achieve cost-effective and scalable *** particular,we find the philosophy underlying empirical network designing and engineering today fails to meet the cost-effective and scalable designing requirements,and propose a cost-effective and scalable designing scheme for BA-like networks,i.e.,the efficient routing combined with effective betweenness based link bandwidth *** addition,when designing a thoroughly new network from the beginning,we find that ER network is a good candidate to achieve cost-effective and scalable designing in most settings.

关键词： cost-effective communication network designing network transmission efficiency network topology traffic dynamics next generation network scalable network designing