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Multiuser subcarriers and bit allocation combining adaptive mapping for SC-FDMA system

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The Journal of China Universities of Posts and Telecommunications 2008年第3期15卷 41-46页

作者： ZHANG Yu-mei XIN Yu YANG da-cheng School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China Zhongxing Telecommunication Equipment Shenzhen 518004 China

In this article, a multiuser single carrier frequency division multiple access （SC-FDMA） system is considered, based on which an adaptive subcarrier and bit allocation algorithm is investigated. The algorithm has been used to achieve a subcarrier mapping mode in this system, which combines the advantages of single- and multi-carrier transmissions, such as, low peak to average power ratio, orthogonality of signals of different users, and low complexity. Simulation results show that it has a similar performance as that of the adaptive allocation algorithm in the orthogonal frequency division multiple （OFDM） system and the proposed mapping mode has a performance gain over the two existing mapping modes at the link level.

关键词： adaptive subcarrier and bit allocation SC-FDMA subcarrier mapping modes bit error ratio (BER)

Inter-domain traffic balancing with co-channel interference management in multi-domain heterogeneous network for LTE-A

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 68-88页

作者： LI Bo WANG Xi-yuan YANG da-cheng School of Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China School of Physics and Electrics Information Ningxia University Yinchuan 750021 China

Heterogeneous network （Het-Net） is part of the long-term evolution advanced （LTE-A） study item and represents cellular deployments with a mixture of cells of different overlapping coverage areas, e.g., a number of relay and pico cells overlaid by a macro cell in the same frequency. Traffic balancing and interference management are required in Het-Net design for LTE-A to maintain system performance. In this paper, we propose an inter-domain cooperative traffic balancing scheme focusing on reducing the effective resource cost and mitigating the co-channel interference in multi-domain Het-Net. We first set up the conception of multi-domain in Het-Net and incorporate the co-channel interference into the proposed traffic balancing scheme. Then we model the traffic balancing issue as a multi-domain traffic resource optimization problem for minimizing the effective resource cost. The detailed implementation for the proposed traffic balancing scheme is designed. In the numerical evaluation, the genetic algorithm （GA） as an optimization method is used to demonstrate that the total effective resource cost is significantly reduced through our proposed inter-domain traffic balancing scheme, comparing with the intra-domain traffic balancing scheme. The 43% of the resource cost is saved. In the system level simulation, the performance results of signal interference noise ratio （SINR） and throughput demonstrate that the proposed scheme has great advantages in interference management in Het-Net.

关键词： heterogeneous network (Het-Net) multi-domain traffic balancing co-channel interference effective resource cost

Noncollinear Magnetism Calculation of Iron Clusters with Spin-Orbit Coupling

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Chinese Physics Letters 2011年第3期28卷 199-202页

作者： cheng Zhi-da ZHU Jing TANG Zheng Beijing National Center for Electron Microscopy Lab of Advanced MaterialsDepartment of Materials Science and EngineeringTsinghua UniversityBeijing 100084 China Iron and Steel Research Institute Group Beijing 100081 Key Laboratory of Polar Materials and Devices(Ministry of Education) East China Normal UniversityShanghai 200241

We study iron clusters containing 2~13 atoms by ab initio calculations with both collinear and noncollinear magnetic ***-orbit coupling is only available in the noncollinear *** full structural relaxations,it is found that atom positions derived from the noncollinear method have better stability in all clusters,including those having coparallel spin *** energies of clusters calculated by the noncollinear method are also 17.3~19.8 meV/atom lower,which are too large to *** comparing the magnetic properties and electronic structures from the two methods,we believe that the difference has resulted from spin-orbit *** recommend reconsidering the importance of the noncollinear magnetic method with spin-orbit coupling in magnetic *** in transition metal clusters when atom positions and energy values are important for determining the crucial properties.

关键词： properties methods method

Theoretical Study of the Scattering Resonance State, Reaction Mechanism and Partial Potential Energy Surface of the F+CH4→HF+CH3 Reaction

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Chinese Chemical Letters 2006年第2期17卷 281-284页

作者： Qiang WANG Zheng Ting CAI da cheng FENG Institute of Theoretical Chemistry Shandong University Jinan 250100

The partial potential energy surface was constructed by ab initio method [QCISD（T）/6- 311＋＋G（2df,2pd）]for F＋CH4→HF＋CH3 reaction system. It not only explained the reaction mechanism brought forward by Diego Troya by means of quasiclassical trajectory （QCT） but also successfully validated Kopin Liu＇s experimental phenomena about the existence of the reactive resonance. The lifetime of the scattering resonance state was about 0.07 ps. All these were in agreement with the experiments.

关键词： The partial potential energy surface (PPES) asymmetrical heavy-light-heavy system dynamic Eyring lake the lifetime of the scattering resonance state.

Improving coarse frame synchronization by UE-UE interference for OFDMA-TDD systems

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The Journal of China Universities of Posts and Telecommunications 2008年第4期15卷 30-34页

作者： ZHU Yuan WANG Chun-ye YANG da-cheng Wireless Theory and Technology Laboratory Beijing University of Posts and Telecommunications Beijing 100876 China

This article studies the coarse flame synchronization of orthogonal frequency division multiplexing access-time division duplex （OFDMA-TDD） systems and proposes a new method to improve coarse frame synchronization performance. The new method utilizes the user equipment to user equipment （UE-UE） interference, which is usually considered as a specific challenge for time division duplex （TDD） and also as implicit frame boundary information to enhance coarse frame synchronization performance. Numerical results show the synchronization performance is imoroved bv the new method.

关键词： orthogonal frequency division multiplexing access time division duplex synchronization training symbol

Relative roles of resuspended particles and pore water in release of contaminants from sediment

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Water Science and Engineering 2014年第3期7卷 344-350页

作者： Hong-wei ZHU Peng-da cheng dao-zeng WANG Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and MechanicsShanghai University Key Laboratory of Waterway Dredging Technology Ministry of TransportNational Engineering Research Center of Dredging Technology and Equipment School of Mechatronical Engineering and Automation Shanghai University

Sediment layers containing contaminants play a significant role in environmental hydrodynamics. Experiments were conducted in order to characterize the relative roles of resuspended particles and pore water under different flow and sediment conditions. A conservative tracer （NaC1） and a reactive tracer （phosphate） were used as contaminants in the bottom sediment in a laboratory flume. The mixing between the overlying water and pore water occurred over a short time while the desorption of contaminants from fine-grained resuspended particles lasted a relatively long time. The effects of resuspended particles and pore water on the variations of release flux and concentration of contaminants in water with time under different hydrodynamic conditions were quantified. The results show that pore water dominated the initial release flux, which could be several orders of magnitude greater than the flux due to molecular diffusion. Flux contribution of desorption from sediment particles in the latter release could be equal to what was seen from pore water in the initial stage.

关键词： sediment resuspension resuspended particle pore water, release of contaminants release flux

Existence and Concentration of Bound States of a Class of Nonlinear Schrdinger Equations in R^2 with Potential Tending to Zero at Infinity

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Acta Mathematica Sinica,English Series 2012年第11期28卷 2243-2274页

作者： da cheng CUI Ji Hui ZHANG Ming Wen FEI School of Mathematics and Information Technology Nanjing Xiaozhuang University School of Mathematical Sciences Nanjing Normal University Academy of Mathematics and Systems Science China Academy of Science School of Mathematical and Computer Sciences Anhui Normal University

In this paper, we establish the existence and concentration of solutions of a class of non- linear SchrSdinger equation

关键词： Bound state nonlinear SchrSdinger equation Harnack inequality concentration-compact-ness

Dynamic traffic split scheme in an integrated LTE and HSDPA networks

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The Journal of China Universities of Posts and Telecommunications 2013年第5期20卷 1-8页

作者： YANG Rui-ming CHANG Yong-yu YANG da-cheng School of Information and Communication Engineering Beijing University of Posts and Telecommunications

In the future, the wireless communication networks can be visualized as the integration of different radio access technologies （RATs）, which are referred to as heterogeneous wireless networks （HWNs）. In this paper, the traffic split scheme in the HWNs integrating the long term evolution （LTE） and the high speed downlink packet access （HSDPA） networks is investigated. Assuming that the networks can support multi-homing access and the user can be served by both networks simultaneously, the traffic split problem is described as an optimization problem with the aim of maximizing the throughput. By solving the problem, the dynamic traffic split scheme is proposed. The split ratios in the scheme should be proportional to the transmission rates in theory, which are hard to be described in the closed forms. Then the adaptive algorithm is proposed to obtain the split ratios. Simulation results show that the scheme with the adaptive algorithm provides better performance than the scheme without it over the additive white Gaussian noise （AWGN） fading channel and Rayleigh fading channel.

关键词： HWNs multi-homing access traffic split common radio resource management (CRRM)

TOTAL PHOSPHORUS RELEASE FROM BOTTOM SEDIMENTS IN FLOWING WATER

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Journal of Hydrodynamics 2012年第4期24卷 589-594页

作者： ZHANG Kun cheng Peng-da ZHONG Bao-chang WANG dao-zeng Shanghai Institute of Applied Mathematics and Mechanics and Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai 200072China

In this paper, the bottom of the Dianshan Lake was selected as a test sample. The dynamic release of contaminated sediments into the overlying water column was experimentally investigated in an open water channel under different hydrodynamic conditions. The experimental results indicate that the Total Phosphorus （TP） release process can be divided into three stages： rapid release, slow release and equilibration release. In the initial release stage the measured TP concentration changes along the depth. The TP concentration near the sediment-water interface is higher than that near the water surface, but the TP concentration becomes uniform along the depth after 3 h. The dynamic release of re-suspension sediment pollutants is about 6 times higher than the static release of sediment-water interface. There are three main types of release mechanism： diffusion release, re-suspended pore water mixing release and re-suspended particles desorbing release.

关键词： Total Phosphorus (TP) concentration sediment re-suspension overlying-water release mechanism