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A Greedy Algorithm for Task Offloading in Mobile Edge Computing System

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China Communications 2018年第11期15卷 149-157页

作者： Feng Wei Sixuan Chen Weixia Zou key lab.of Universal Wireless Communications MOE Beijing University of Posts and Telecommunications state key lab.of millimeter waves Southeast University

Mobile edge computing （MEC） is a novel technique that can reduce mobiles＇ com- putational burden by tasks offioading, which emerges as a promising paradigm to provide computing capabilities in close proximity to mobile users. In this paper, we will study the scenario where multiple mobiles upload tasks to a MEC server in a sing cell, and allocating the limited server resources and wireless chan- nels between mobiles becomes a challenge. We formulate the optimization problem for the energy saved on mobiles with the tasks being dividable, and utilize a greedy choice to solve the problem. A Select Maximum Saved Energy First （SMSEF） algorithm is proposed to realize the solving process. We examined the saved energy at different number of nodes and channels, and the results show that the proposed scheme can effectively help mobiles to save energy in the MEC system.

关键词： mobile edge computing task off- loading greedy choice energy resource allo- cation

Hybrid Precoder and Combiner Design with Finite Resolution PSs for mmWave MIMO Systems

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China Communications 2019年第2期16卷 95-104页

作者： Ran Zhang Weixia Zou Ye Wang Mingyang Cui key lab.of Universal Wireless Communications MOEBeijing University of Posts and Telecommunications state key lab.of millimeter waves Southeast University

Hybrid precoding and combining have been considered as a promising technology, which can provide a compromise between hardware complexity and system performance in millimeter wave multiple-input multiple-output systems. However, most existing hybrid precoder and combiner designs generally assume that infinite resolution phase shifters(PSs) are used to produce the analog beamformers. In a practical scene, the design with accurate PSs can lead to high hardware cost and power consumption. In this paper, we investigate the hybrid precoder and combiner design with finite resolution PSs in millimeter wave systems. We employ alternate optimization as the main strategy to jointly design analog precoder and combiner. In addition, we propose a low complexity algorithm, where the analog beamformers are implemented only by finite resolution PSs to maximize spectral efficiency. Then, the digital precoder and combiner are designed based on the obtained analog beamformers to improve the spectral efficiency. Finally, simulation results and mathematical analysis show that the proposed algorithm with low-resolution PSs can achieve near-optimal performance and have low complexity.

关键词： millimeter wave multiple-input multiple-output finite resolution phase shifters hybrid precoding alternate optimization

On Multi-Frequency Channel Interference Alignment of 3 Channels and 4 Users

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China Communications 2016年第1期13卷 22-32页

作者： DU Guanglong ZOU Weixia ZHOU Zheng key lab.of Universal Wireless Communications MOEBeijing University of Posts and Telecommunications state key lab.of millimeter waves Southeast University

This paper explores the multi-frequency independent channel interference alignment(MFC-IA) system of 3 channels and4 users,and single data stream transmit,i.e.(3×3,1)~4 *** derive the analytic solution for(3×3,1)~4 MFC-IA *** on the analytic solution,an optimization problem is proposed aim at the optimal IA *** based on such a math model,we propose a simulated annealing(SA) algorithm to search optimal IA *** simulation results show that the simulated annealing IA algorithm has a better sum rate performance than iterative maximize signal to interference plus noise ratio(Max-SINR) *** result can be extended to single data stream multi-antenna IA system with 3 antennas and4 users.

关键词： communication and information system interference alignment multi-frequency channel analytic solution simulated annealing

Low Complexity Joint Hybrid Precoding for millimeter Wave MIMO Systems

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China Communications 2019年第2期16卷 49-58页

作者： Mingyang Cui Weixia Zou key lab.of Universal Wireless Communications MOEBeijing University of Posts and Telecommunications state key lab.of millimeter waves Southeast University

In millimeter wave(mmWave) multiple-input multiple-output(MIMO) systems, hybrid precoding has been widely used to overcome the severe propagation loss. In order to improve the spectrum efficiency with low complexity, we propose a joint hybrid precoding algorithm for single-user mmWave MIMO systems in this paper. By using the concept of equivalent channel, the proposed algorithm skillfully utilizes the idea of alternating optimization to complete the design of RF precoder and combiner. Then, the baseband precoder and combiner are computed by calculating the singular value decomposition of the equivalent channel. Simulation results demonstrate that the proposed algorithm can achieve satisfactory performance with quite low complexity. Moreover, we investigate the effects of quantization on the analog components and find that the proposed scheme is effective even with coarse quantization.

关键词： millimeter wave MIMO 5G joint hybrid precoding low complexity

A Geometric Model Simplification Strategy for CFD Simulation of the Cockpit Internal Environment

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Computer Modeling in Engineering & Sciences 2025年第2期142卷 1545-1564页

作者： Meng Zhao Jiaao Liu YudiLiu Zhengwei Long Tianjin key lab.of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityTianjin300072China Architectural Institute China Railway Design CorporationTianjin300308China Environmental Control Oxygen Department Shanghai Aircraft Design and Research InstituteCOMACShanghai201210China

Computational Fluids Dynamics(CFD)simulations are essential for optimizing the design of a cockpit’s internal environment,but the complex geometric models consume a significant amount of computational resources and *** simplification of geometric models may result in inaccurate calculations of physical *** address this issue,this study establishes a geometric model simplification strategy and successfully applies it to a *** implementation of the whole approach is divided into three steps,summarized in three methods,namely Sensitivity Analysis Method(SAM),Detail Suppression Method(DSM),and Evaluation Standards Method(ESM).Sensitivity analysis of the detailed features of the geometric model is performed using the adjoint *** details of the geometric model are suppressed based on the principle of curvature *** evaluation,the suppression degrees of detailed features with different sensitivity levels are *** results demonstrate that this strategy can be employed to achieve precise simplification standards,thereby avoiding excessive deviations caused by arbitrary simplification and reducing the significant costs associated with trial-and-error simplification.

关键词： CFD model simplification cockpit sensitivity analysis detail suppression

Integrated spoof plasmonic circuits

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Science Bulletin 2019年第12期64卷 843-855页

作者： Jingjing Zhang Hao-Chi Zhang Xin-Xin Gao Le-Peng Zhang Ling-Yun Niu Pei-Hang He Tie-Jun Cui state key laboratory of millimeter waves Southeast University

Using a metamaterial consisting of metals with subwavelength surface patterning, one can mimic surface plasmon polaritons(SPPs) and achieve surface waves with subwavelength confinement at microwave and terahertz frequencies, thus bringing most of the advantages associated with the optical SPPs to lower frequencies. Due to the properties of strong field confinement and high local field intensity, spoof SPPs have demonstrated the improved performance for data transmission and device miniaturization in an intensively integrated environment. The distinctive abilities, such as suppression of transmission loss and bending loss, and increase of signal integrity, make spoof SPPs a promising candidate for future generation of electronic circuits and electromagnetic systems. This article reviews the progress in spoof SPPs with a special focus on their applications in circuits from transmission lines to passive and active devices in microwave and terahertz regimes. The integration of versatile spoof SPP devices on a single platform,which is compatible with established electronic circuits, is also discussed.

关键词： Spoof surface plasmons Metamaterial Electromagnetic system Integrated circuits

Metal-organic polyhedra as dynamic cross-linker for recyclable mixed matrix membranes with promising dimension stability

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Science China Chemistry 2025年第2期68卷 705-713页

作者： Linjie Lan Mingxin Zhang Haiyan Xiao Wei Liu-Fu Yuyan Lai Jiadong Chen Jia-Fu Yin Panchao Yin state key laboratory of Luminescent Materials and Devices&South China Advanced Institute for Soft Matter Science and Technology Guangdong Basic Research Center of Excellence for Energy and Information Polymer MaterialsSouth China University of TechnologyGuangzhou 510641China state key laboratory of Marine Resource Utilization in South China Sea Hainan Provincial Key Lab of Fine ChemistrySchool of Chemical Engineering and TechnologyHainan UniversityHaikou 570228China

Mixed matrix membranes(MMMs)are designed by incorporating microporous inorganic fillers into polymer matrix for the integration of inorganics’excellent gas separation performance with polymers’promising ***,due to the complex interphase interaction,the prevention of long-term aging is still challenging and the poor processability/recyclability of MMMs hinders their extensive ***,a coordination assembly protocol is developed for the fabrication of MMMs with both excellent processability/recyclability upon thermal annealing and promising dimension stability even under high gas *** bearing isophthalic acid(IPA)as side chains are applied to coordinate with Cu^(2+)and the assembled 2.5 nm microporous metal-organic polyhedra(MOP),{Cu_(24)IPA_(24)},serves as multi-functional cross-linkers for the polymer network *** MOPs’well-defined microporosity grants MMMs the capability for O_(2)/N_(2) separation while their activated dynamics at high temperatures(>120℃)endows polymer networks with excellent *** contrast to conventional supramolecular units,the MOPs possess unique logarithmic ligand-exchange kinetics and they show nearly frozen bonding dynamics at room temperature,ensuring promising dimensional stability to overcome the long-term aging and high gas pressure *** work not only provides fundamental understanding of the unique relaxation dynamics of complex systems with intertwined dynamics of supramolecular bonds and polymer chains,but also paves new avenues for the fabrication of robust and recyclable MMMs and elastomers.

关键词： dynamic bonding metal-organic polyhedra mixed matrix membrane polymer recycling gas separation

Experimental Study on Geometry Characteristics of Turbulent Premixed Flames for Natural Gas/Air Mixtures

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Journal of Thermal Science 2025年第1期34卷 268-282页

作者： ZHENG Weilin WANG Qijiao XIAO Huahua CHEN Xiaoxiao XIE Fan ZENG Wen Liaoning key lab.of Advanced Test Technology for Aerospace Propulsion System Shenyang Aerospace UniversityShenyang 110136China state key laboratory of Fire Science University of science and Technology of ChinaHefei 230027China AVIC Shenyang Aircraft Design and Research Institute Shenyang 110035China

In this study,focusing on the geometry characteristics of spherical expanding flame,the turbulent premixed flames of natural gas/air mixtures were investigated in a fan-stirred turbulent *** effects of initial temperature(T=300-400 K),initial pressure(P=0.1-0.3 MPa),turbulence intensity(u'=1.0-2.7 m/s),oxygen volumetric percentage(φ(O_(2))=15%-21%)and carbon dioxide volumetric percentage(φ(CO_(2))=0-20%)were delved *** flame profile under the Cartesian coordinate system was derived from the schlieren images taken by the high-speed ***,from both macroscopic and microscopic perspectives,the influence of experimental conditions on the flame geometry characteristics was explored through flame front extraction,wavelet decomposition and network *** results demonstrate that for significant flame wrinkling,changes in species concentrations and turbulence intensity have more pronounced effects on the flame wrinkling *** wrinkling of the flame front maintains a certain degree of similarity,as evidenced by the locally concentrated distribution of the angles of the maximum fluctuation *** disturbance energy under large-scale(D6-D8)disturbances exhibits relatively high values with a similar trend,exerting a significant impact on the geometry characteristics of the flame *** peaks of correlation degree are scattered either with the decomposition scale or the development of flame radius,indicating no linear correlation between different detail ***,the probability distribution of node degrees in key wrinkled regions exhibits different trends with that of large-scale wrinkling and disturbance energy,especially with changes in initial *** occurs because the number of key wrinkles varies based on the perturbation's strength or the region's ***,an increase in the fluctuation frequency of the flame's local radius may not necessarily lead to an increase in the number of key folded regions.

关键词： geometry characteristics large-scale wrinkling wavelet decomposition network topology fan-stirred turbulent combustor

Microwave metamaterials

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National Science Review 2018年第2期5卷 134-136页

作者： Tie Jun Cui state key laboratory of millimeter waves Southeast University

Metamaterials are artificial structures with tailored meta-atoms at subwavelength scales to control electromagnetic waves at ***,metamaterials are described by effective medium parameters(*** of refraction,permittivity and permeability)due to the subwavelength nature of *** the meta-atom is comparable to the wavelength,the effective medium description

关键词： METAMATERIALS MICROwaves