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Hierarchical mobility prediction in the future heterogeneous networks for the tradeoff between accuracy and complexity

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The Journal of China Universities of Posts and Telecommunications 2019年第3期26卷 15-24页

作者： liu Zhenya li xi Ji Hong Zhang Heli Key Laboratory of Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

Mobility prediction is one of the promising technologies for improving quality of service(QoS) and network resource utilization. In future heterogeneous networks(HetNets), the network topology will become extremely complicated due to the widespread deployment of different types of small-cell base stations(SBSs). For this complex network topology, traditional mobility prediction methods may cost unacceptable overhead to maintain high prediction accuracy. This problem is studied in this paper, and the hierarchical mobility prediction scheme(HMPS) is proposed for the future HetNets. By dividing the entire process into two prediction stages with different granularity, the tradeoff between prediction accuracy and computational complexity is investigated. Before performing prediction of user mobility, some frequently visited locations are identified from the user’s trajectory, and each location represents an important geographic area(IGA). In the coarse-grained prediction phase, the next most possible location to be visited is predicted at the level of the possible geographic areas by using a second-order Markov chain with fallback. Then, the fine-grained prediction of user position is performed based on hidden Markov model(HMM) from temporal and spacial dimensions. Simulation results demonstrate that, compared with the existing prediction methods, the proposed HMPS can achieve a good compromise between prediction accuracy and complexity.

关键词： mobility prediction heterogeneous networks prediction accuracy and complexity Markov chain, HMM

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Utilizing partial least square and support vector machine for TBM penetration rate prediction in hard rock conditions

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Journal of Central South University 2015年第1期22卷 290-295页

作者：高栗李夕兵 School of Resources and Safety Engineering Central South University Changsha Environmental Protection Vocational College

Rate of penetration(ROP) of a tunnel boring machine(TBM) in a rock environment is generally a key parameter for the successful accomplishment of a tunneling project. The objectives of this work are to compare the accuracy of prediction models employing partial least squares(PLS) regression and support vector machine(SVM) regression technique for modeling the penetration rate of TBM. To develop the proposed models, the database that is composed of intact rock properties including uniaxial compressive strength(UCS), Brazilian tensile strength(BTS), and peak slope index(PSI), and also rock mass properties including distance between planes of weakness(DPW) and the alpha angle(α) are input as dependent variables and the measured ROP is chosen as an independent variable. Two hundred sets of data are collected from Queens Water Tunnel and Karaj-Tehran water transfer tunnel TBM project. The accuracy of the prediction models is measured by the coefficient of determination(R2) and root mean squares error(RMSE) between predicted and observed yield employing 10-fold cross-validation schemes. The R2 and RMSE of prediction are 0.8183 and 0.1807 for SVMR method, and 0.9999 and 0.0011 for PLS method, respectively. Comparison between the values of statistical parameters reveals the superiority of the PLSR model over SVMR one.

关键词： tunnel boring machine(TBM) performance prediction rate of penetration(ROP) support vector machine(SVM) partial least squares(PLS)

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Effects of arsenic on seed germination and physiological activities of wheat seedlings

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Journal of Environmental Sciences 2007年第6期19卷 725-732页

作者： li Chun-xi FENG Shu-li SHAO Yun JIANG li-na LU Xu-yang HOU xiao-li College of life Sciences Henan Normal University Xinxiang 453007 China

The effects of arsenic （As） were investigated on seed germination, root and shoot length and their biomass and some other factors to elucidate the toxicity of As. The results showed low concentrations of As （0-1 mg/kg） stimulated seed germination and the growth of root and shoot, however, these factors all decreased gradually at high concentrations of As （5-20 mg/kg）. The contents of O2^-, MDA, soluble protein and peroxidase （POD） activity all increased with increasing As concentrations. Soluble sugar content, ascorbate peroxidase （APX）, and superoxide dismutase （SOD） activities decreased at low concentrations of As, and increased at high concentrations of As. While acetylsalicylic acid （ASA） and chlorophyll contents, catalase （CAT） activity displayed increasing trend when the concentrations of As was lower than 1 mg/kg, and then decreasing trend. By polyacrylamide gel electrophoresis （PAGE）, As induced the expression of POD isozymes of wheat seedlings. As induced the expression of CAT isozymes but inhibited the expression of SOD isozymes of wheat seedlings at concentrations lower than 1 mg/kg. However, As inhibited the expression of CAT isozymes but induced the expression of SOD isozymes at concentrations higher than 5 mg/kg. The results indicated As could exert harmfulness in the early development stage of wheat at inappropriate concentrations.

关键词： arsenic wheat germination physiological activities

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NUMERICAL SIMULATION OF TOPOGRAPHY CHANGE IN RECLAIMED LAND ALONG COAST OF SOUTH CHINA SEA

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Journal of Hydrodynamics 2002年第1期14卷 87-92页

作者： li, xi Wang, Yi-Gang Sha, Shu-Ming Res. Inst. of Coastal and Ocean Eng. Hohai Univ. Nanjing 210029 China

A formula for total sediment transport rate was worked out based on field surveys and experiments, which could be used to predict the topography change under wave climate. The sediment transport and wave induced hydrodynamics were solved separately, which is more convenient to predict long-term beach evolution than solving a coupled equation. In applying the sediment transport equation to wave model, the topography change was considered to give a new bathymetry as input for the wave equations, which in return will give a time-dependent hydrodynamic environment. The wave transformation including wave breaking was simulated by solving Boussinesq-type wave equations, together with some verification and comparisons. The longshore currents due to eddy viscosity was simulated by the model under unidirectional waves, which have been applied in erosion control of reclaimed land by headland breakwaters. The topography is found in equilibrium by headland breakwaters and the equilibrium process is simulated with comparison to the engineering practice in the South China Sea.

关键词： Coastal zones Computer simulation Erosion Mathematical models Viscosity

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The Gevrey smoothing effect for the spatially inhomogeneous Boltzmann equations without cut-off

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Science China Mathematics 2022年第3期65卷 443-470页

作者： Hua Chen xin Hu Wei-xi li Jinpeng Zhan School of Mathematics and Statistics Wuhan UniversityWuhan 430072China Computational Science Hubei Key Laboratory Wuhan UniversityWuhan 430072China Department of Mathematics School of ScienceWuhan University of TechnologyWuhan 430070China

In this article we study the Gevrey regularization effect for the spatially inhomogeneous Boltzmann equation without angular *** equation is partially elliptic in the velocity direction and degenerates in the spatial *** consider the nonlinear Cauchy problem for the fluctuation around the Maxwellian distribution and prove that any solution with mild regularity will become smooth in the Gevrey class at positive time with the Gevrey index depending on the angular *** proof relies on the symbolic calculus for the collision operator and the global subelliptic estimate for the Cauchy problem of the linearized Boltzmann operator.

关键词： Boltzmann equation Gevrey regularity subelliptic estimate non cut-off symbolic calculus

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pH-sensitive KHA/CMC-Fe^(3+)@CS hydrogel loading and the drug release properties of riboflavin

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Particuology 2024年第3期86卷 13-23页

作者： Jie Song xi li Yuhua Niu lijun Chen Zhiqiang Wei Yidan li Youqian Wang Shaanxi University of Science&Technology Xi'an710021China

To improve drug utilization,reduce the drug administration frequency,increase the release time,and reduce the drug side effects in the human body,we prepared(KHA/CMC-Fe^(3+))@CS hydrogel spheres using green and natural potassium humate(KHA),carboxymethyl cellulose(CMC),and chitosan(CS)as raw materials and Fe3+as a crosslinking agent,and loaded them with riboflavin for drug sustainedrelease study using the drop ball *** tests with FTIR,SEM,TG,and X-ray diffractometer showed that the coordination among KHA,CMC,and Fe^(3+)formed a three-dimensional network structure,where cs was encapsulated on the surface of the hydrogel spheres via noncovalent bonding,resulting in good thermal *** stability,drug loading,swelling,and in vitro release of the(KHA/CMC-Fe^(3+))@CS hydrogel spheres were *** results showed that the hydrogel spheres were significantly pH-sensitive,with 11.16 g/g higher swelling in an alkaline environment(pH=7.4)than that in an acidic environment(pH=1.2).The swelling and drug release process of the hydrogel spheres were analyzed using mathematical models,concluding that the hydrogel swelling follows Schott second-order swelling kinetics,and the drug release mechanism was Fickian delivery mode.

关键词： Potassium humate Hydrogel spheres pH-sensitive Drugsustained-release Drug release model

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Effect of NPK Application on Yield,Nutrients and Water Utilization Under Sudangrass and Ryegrass Rotation Regime

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Agricultural Sciences in China 2010年第7期9卷 1026-1034页

作者： li Wen-xi LU Jian-wei CHEN Fang li xiao-kun College of Resources and Environment Huazhong Agricultural University Wuhan 430070 P.R.China Wuhan Botanical Garden Chinese Academy of Sciences Wuhan 430074 P.R.China

Sudangrass and ryegrass rotation is a new type of cropping system in Jianghan Plain,which develops very fast in recent ***,it is essential to work out the optimal nutrients and water management measures in this new *** effect of NPK fertilizer on yield of forage grass,nutrients and water utilization under sudangrass and ryegrass rotation was studied through continuous pot experiments for three *** results showed that NPK combination could significantly improve the yield of forage *** total yields during the periods of 2005-2006,2006-2007 and 2007-2008 were 1 690.0,2 091.3 and 1 770.7 g/pot,*** yields in PK treatment were 700.7,1 256.9 and 856.3% lower than those of NPK treatment,while the yields in NK treatment were 426.3,384.9 and 792.3% lower than those of NPK treatment,***,the yields in NP treatment were 15.9,4.4 and 10.6% lower than those of NPK treatment,*** NPK combination was found to improve the nutrients uptake,and the total N uptakes during the above periods were 10.0,14.8 and 10.6 times higher than that of PK treatment,respectively,and 3.7,1.8 and 5.1 times higher than those of NK treatment,respectively,but,were similar to NP *** total P uptakes were 4.6,6.8 and 5.3 times higher than those of PK treatment,and were 2.4,2.3 and 2.9 times higher than those of NK treatment,respectively,but were similar to NP *** total K uptakes were 5.2,8.4 and 4.9 times higher than that of PK treatment,3.9,2.3 and 3.9 times higher than those of NK treatment,and 80.9,57.4 and 200.5% higher than those of NP treatment,*** productivity for three years time periods were 16.5,16.1 and 16.2 kg m-3,and were 3.8,5.4 and 4.2 times higher than those of PK treatment,2.3,1.3 and 2.6 times higher than those of NK treatment,and were 16.4,8.8 and 22.4% higher than those of NP treatment,*** soil pH was decreased and soil organic matter was increased in all treatments with in

关键词： sudangrass and ryegrass rotation system NPK fertilizer nutrient uptake water productivity soil nutrition

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The Smallest Values of Algebraic Connectivity for Trees

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Acta Mathematica Sinica,English Series 2012年第10期28卷 2021-2032页

作者： Jian xi li Ji Ming GUO Wai Chee SHIU Department of Mathematics and Information Science Zhangzhou Normal University Department of Mathematics Hong Kong Baptist University，Kowloon Tong，Hong Kong，P．R．China Department of Applied Mathematics China University of Petroleum

The algebraic connectivity of a graph G is the second smallest eigenvalue of its Laplacian matrix. Let Fn be the set of all trees of order n. In this paper, we will provide the ordering of trees in 3n up to the last eight trees according to their smallest algebraic connectivities when n ≥ 13. This extends the result of Shao et al. [The ordering of trees and connected graphs by algebraic connectivity. linear Algebra Appl., 428, 1421-1438 （2008）].

关键词： Tree algebraic connectivity ordering

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In-plane Uniaxial Anisotropy and Magnetization Reversal Mechanism of FeCo Films by Strip Pattern

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Acta Metallurgica Sinica(English Letters) 2014年第6期27卷 1099-1104页

作者： Xuemeng Han Jinhua Ma Zhen Wang Yalu Zuo li xi Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education Lanzhou University

Strip-like Fe Co films were patterned by a traditional lithograph process from intrinsically isotropic continuous Fe Co films. The strip-patterned Fe Co film shows a strong in-plane uniaxial magnetic anisotropy with easy axis along the length direction of the strip. The angular dependences of remanence ratio, switching field, and coercivity indicate that the magnetization reversal mechanism of the strip-patterned Fe Co film is coherent rotation and domain wall depinning when the applied field is near the hard axis and easy axis, respectively. The consistency of the experimental hysteresis loops of the strip-patterned Fe Co film and calculated hysteresis loops with a simple in-plane uniaxial anisotropy model indicates that the strip-patterned Fe Co film behaves as a single domain. The absence of the domain wall and the strong in-plane anisotropy field make the strip-patterned Fe Co films have much potential for high-frequency application.

关键词： In-plane anisotropy Fe Co film Strip patterned Switching field

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Control design of 60kW PEMFC generation system for residential applications

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第9期14卷 679-685页

作者： Ying-ying ZHANG Ying ZHANG xi li Guang-yi CAO Shandong Provincial Key Laboratory of Ocean Environment Monitoring Technology Institute of Oceanographic Instrumentation Shandong Academy of Sciences Control Science and Engineering Department Key Laboratory of the Ministry of Education for Image Processing and Intelligent Control Huazhong University of Science and Technology Fuel Cell Institute Department of Automation Shanghai Jiao Tong University

This paper presented a control design methodology for a proton exchange membrane fuel cell (PEMFC) generation system for residential applications. The dynamic behavior of the generation system is complex in such applications. A comprehensive control design is very important for achieving a steady system operation and efficiency. The control strategy for a 60 kW generation system was proposed and tested based on the system dynamic model. A two-variable single neuron proportional-integral (PI) decoupling controller was developed for anode pressure and humidity by adjusting the hydrogen flow and water injection. A similar controller was developed for cathode pressure and humidity by adjusting the exhaust flow and water injection. The desired oxygen excess ratio was kept by a feedback controller based on the load current. An optimal seeking controller was used to trace the unique optimal power point. Two negative feedback controllers were used to provide AC power and a suitable voltage for residential loads by a power conditioning unit. Control simulation tests showed that 60 kW PEMFC generation system responded well for computer-simulated step changes in the load power demand. This control methodology for a 60 kW PEMFC generation system would be a competitive solution for system level designs such as parameter design, performance analysis, and online optimization.

关键词： Proton exchange membrane fuel cell (PEMFC) Generation system Control strategy decoupling control Optimalseeking control

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