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Scattering for Focusing Combined Power-type NLS

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Acta Mathematica Sinica,English Series 2014年第5期30卷 805-826页

作者： Jian xie Department of Mathematics Hangzhou Normal University

We consider the scattering of Cauchy problem for the focusing combined power-type Schroodinger equation. In the spirit of concentration-compactness method, we will show that, H1 solution will scatter under some condit... 详细信息

关键词： Nonlinear Schroodinger equation scattering concentration-compactness method

Synergistic modification of the tribological properties of polytetrafluoroethylene with polyimide and boron nitride

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Friction 2021年第6期9卷 1474-1491页

作者： Chaojie xie Kejian WANG College of Mechanical and Electrical Engineering Beijing University of Chemical TechnologyBeijing 100029China

Polytetrafluoroethylene(PTFE)blended with polyimide(PI)and filled with boron nitride(BN)is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction(COF).The characterizations show that BN and PI at different levels,improve the hardness,dynamic thermo-mechanical modulus,thermal conductivity,and tribological properties of *** boosts the dispersion and bonding of BN in *** dry sliding friction of a block-on-ring tribometer,the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80%of those of pure PTFE,respectively,as the wear mechanism transition from being adhesive to partially *** occurs only when the additives BN and PI induce a synergistic effect,that is,at concentrations that are not higher than ca.10 wt%and 15 wt%,*** obvious agglomeration at high percentages of added PI and severe conditions(400 N and 400 rpm)induce strong adhesive *** variations in the tensile properties,hardness,crystallization,and microstructure of the composites correspond to different *** multiple parameters of the plots of wear and friction are transformed into their contour *** mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.

关键词： wear mechanism coefficient of friction(COF) transition map polytetrafluoroethylene(PTFE) polyimide(PI) boron nitride(BN)

Turbulence Statistics of Thermo-Buoyancy Supercritical Fuel Flow in a Regenerative Cooling Channel

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Journal of Thermal Science 2024年第1期33卷 126-137页

作者： SUN Feng xie Gongnan School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Department of Thermal Engineering Tsinghua UniversityBeijing 100084China

Active regenerative cooling with supercritical hydrocarbon fuel is considered as the most promising thermal protection *** existence of buoyancy force would lead to strongly anisotropic flow and thermal transport *** is closely related to the cooling performance of the *** elucidate the mechanisms of turbulent transport,the large eddy simulation(LES) was performed to assess turbulence statistics within different turbulence *** results indicated that the buoyancy and inertial force together dominated the change of turbulent ***,the spatial thermal buoyancy effect significantly suppressed the vertical velocity *** is due to the laminar motion caused by the buoyancy force,thereby weakening the thermal *** the statistics of velocity fluctuation,it was found that the buoyancy force and inertial force greatly weaken the vertical and streamwise velocity fluctuation,*** the statistics of thermal transport,the results pointed out that the near-wall heat transport characteristics need to be paid more *** thickness of the temperature mixing boundary layer led to the attenuation of vertical heat flux,which inhibited vertical temperature diffusion and predisposed to extreme conditions of heat transfer *** results can enhance the academic understanding of the heat transfer mechanism of supercritical fluids,and give guidance for further applications of thermal protection.

关键词： active regenerative cooling large eddy simulation(LES) buoyancy force turbulence statistics

Robust resource allocation for NOMA-assisted heterogeneous networks

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Digital Communications and Networks 2022年第2期8卷 208-214页

作者： Hao xie Yongjun Xu School of Communication and Information Engineering Chongqing University of Posts and TelecommunicationsChongqing400065China

As a promising technology to improve spectrum efficiency and transmission coverage,Heterogeneous Network(HetNet)has attracted the attention of many scholars in recent ***,with the introduction of the Non-Orthogonal Multiple Access(NOMA)technology,the NOMA-assisted HetNet cannot only improve the system capacity but also allow more users to utilize the same frequency band resource,which makes the NOMA-assisted HetNet a hot ***,traditional resource allocation schemes assume that base stations can exactly estimate direct link gains and cross-tier link gains,which is impractical for practical HetNets due to the impact of channel delays and random *** further improve energy utilization and system robustness,in this paper,we investigate a robust resource allocation problem to maximize the total Energy Efficiency(EE)of Small-Cell Users(SCUs)in NOMA-assisted HetNets under imperfect channel state *** considering bounded channel uncertainties,the robust resource optimization problem is formulated as a mixed-integer and nonlinear programming problem under the constraints of the cross-tier interference power of macrocell users,the maximum transmit power of small base station,the Resource Block(RB)assignment,and the quality of service requirement of each *** original problem is converted into an equivalent convex optimization problem by using Dinkelbach's method and the successive convex approximation method.A robust Dinkelbach-based iteration algorithm is designed by jointly optimizing the transmit power and the RB *** results verify that the proposed algorithm has better EE and robustness than the existing algorithms.

关键词： Heterogeneous network Imperfect channel state information Non-orthogonal multiple access Robust resource allocation Energy efficiency maximization

Consensus Analysis of Fractional Multi-Agent Systems with Delayed Distributed PI Controller

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Journal of Systems Science & Complexity 2023年第1期36卷 205-221页

作者： xie Yingkang MA Qian School of Automation Nanjing University of Science and TechnologyNanjing 210094China

The consensus problem for fractional multi-agent systems(MASs)with time delay is *** distributed fractional proportional-integral(PI)-type controller is designed so that the consensus of the proposed systems is ***,explicit condition to determine the crossing directions is *** results show that with the increase of time delay,the closed-loop system has two different dynamic characteristics:From consensus to nonconsensus and consensus ***,delay margin within which consensus of MASs will always hold is *** results should provide useful guidelines in the consensus analysis and in the analytical design of the distributed controllers.

关键词： Consensus switching crossing direction fractional multi-agent systems fractional PI controller time delay

Entropy-based guidance and predictive modelling of pedestrians’visual attention in urban environment

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Building Simulation 2024年第10期17卷 1659-1674页

作者： Qixu xie Li Zhang Department of Architecture School of ArchitectureTsinghua UniversityBeijing 100084China Urban Ergonomics Lab School of ArchitectureTsinghua UniversityBeijing 100084China

Selective visual attention determines what pedestrians notice and ignore in urban *** consistency exists between different individuals’visual attention,designers can modify design by underlining mechanisms to better meet user ***,the mechanism of pedestrians’visual attention remains poorly understood,and it is challenging to forecast which position will attract pedestrians more in urban *** address this gap,we employed 360°video and immersive virtual reality to simulate walking scenarios and record eye movement in 138 *** findings reveal a remarkable consistency in fixation distribution across individuals,exceeding both chance and orientation *** driver of this consistency emerges as a strategy of information maximization,with participants tending to fixate areas of higher local ***,we built the first eye movement dataset for panorama videos of diverse urban walking scenes,and developed a predictive model to forecast pedestrians’visual attention by supervised deep *** predictive model aids designers in better understanding how pedestrians will visually interact with the urban environment during the design phase.

关键词： visual attention pedestrian eye-tracking local entropy deep learning urban ergonomics

High-temperature electrocatalysis and key materials in solid oxide electrolysis cells

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Journal of Energy Chemistry 2021年第3期30卷 736-745页

作者： Lingting Ye Kui xie Key Laboratory of Optoelectronic Materials Chemistry and Physics Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002FujianChina Key Laboratory of Design&Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002FujianChina

Solid oxide electrolysis cells(SOECs)can convert electricity to chemicals with high efficiency at ~600-900℃,and have attracted widespread attention in renewable energy conversion and *** operate in the inverse mode of solid oxide fuel cells(SOFCs)and therefore inherit most of the advantages of SOFC materials and energy conversion ***,the external bias that drives the electrochemical process will strongly change the chemical environments in both in the cathode and anode,therefore necessitating careful reconsideration of key materials and electrocatalysis *** importantly,SOECs provide a unique advantage of electrothermal catalysis,especially in converting stable low-carbon alkanes such as methane to ethylene with high ***,we review the state-of-the-art of SOEC research progress in electrothermal catalysis and key materials and provide a future perspective.

关键词： Electrocatalysis Solid oxide electrolysis cell Cathode Anode Electrolyte

Multi-algorithm Fusion Framework for Energy Prediction of Energy Harvesting IoT Node and Implementation

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Chinese Journal of Electronics 2020年第5期29卷 952-958页

作者： LI Xiangyu xie Nijie Institute of Microelectronics Tsinghua University Beijing National Research Center for Information Science and Technology

Accurate harvested energy prediction of the energy harvesting Internet-of-things(IoT) nodes is the basis of the proper power management and should be lowoverhead. A new multi-algorithm fusion framework, which merges results of multiple prediction algorithms to achieve a higher accuracy, has been proposed. A three-algorithm fusion solar radiation predictor was implemented. The experiments using the real solar radiation data show that it improves the percentage prediction error by 10%–26% for different prediction intervals. Its complexity is low enough to run on the embedded systems in real-time.

关键词： Energy harvesting Energy prediction Multi-algorithm fusion Internet-of-things

A self-adaptive grey forecasting model and its application

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Journal of Systems Engineering and Electronics 2022年第3期33卷 665-673页

作者： TANG Xiaozhong xie Naiming College of Economics and Management Nanjing University of Aeronautics and AstronauticsNanjing 211106China Department of Industry and Finance Huangshan Vocational and Technical CollegeHuangshan 245000China

GM(1,1)models have been widely used in various fields due to their high performance in time series ***,some hypotheses of the existing GM(1,1)model family may reduce their prediction performance in some *** solve this problem,this paper proposes a self-adaptive GM(1,1)model,termed as SAGM(1,1)model,which aims to solve the defects of the existing GM(1,1)model family by deleting their modeling ***,a novel multi-parameter simultaneous optimization scheme based on firefly algorithm is proposed,the proposed multi-parameter optimization scheme adopts machine learning ideas,takes all adjustable parameters of SAGM(1,1)model as input variables,and trains it with firefly *** Sobol’sensitivity indices are applied to study global sensitivity of SAGM(1,1)model parameters,which provides an important reference for model parameter ***,forecasting capability of SAGM(1,1)model is illustrated by Anhui electricity consumption *** show that prediction accuracy of SAGM(1,1)model is significantly better than other models,and it is shown that the proposed approach enhances the prediction performance of GM(1,1)model significantly.

关键词： grey forecasting model GM(1,1)model firefly algo-rithm Sobol’sensitivity indices electricity consumption prediction