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Traffic prediction enabled dynamic access points switching for energy saving in dense networks

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Digital Communications and Networks 2023年第4期9卷 1023-1031页

作者： Yuchao Zhu shaowei wang School of Electronic Science and Engineering Nanjing UniversityNanjing210000China

To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service ***,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed *** this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the ***,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the *** results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.

关键词： Access points switching on/off Energy-saving Green network Long short-term memory Traffic prediction

Thermal instability of a viscoelastic fluid in a fluid-porous system with a plane Poiseuille flow

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Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1631-1650页

作者： Chen YIN Chunwu wang shaowei wang College of Science Nanjing University of Aeronautics and AstronauticsNanjing 210016China Department of Engineering Mechanics School of Civil EngineeringShandong UniversityJinan 250061China

The thermal convection of a Jeffreys fluid subjected to a plane Poiseuille flow in a fluid-porous system composed of a fluid layer and a porous layer is studied in the paper.A linear stability analysis and a Chebyshevτ-QZ algorithm are employed to solve the thermal mixed *** the case in a single layer,the neutral curves of the two-layer system may be bi-modal in the proper depth ratio of the two *** find that the longitudinal rolls(LRs)only depend on the depth *** the existence of the shear flow,the effects of the depth ratio,the Reynolds number,the Prandtl number,the stress relaxation,and strain retardation times on the transverse rolls(TRs)are also ***,the thermal instability of the viscoelastic fluid is found to be more unstable than that of the Newtonian fluid in a two-layer *** contrast to the case for Newtonian fluids,the TRs rather than the LRs may be the preferred mode for the viscoelastic fluids in some cases.

关键词： viscoelastic fluid thermal convection Poiseuille flow fluid-porous system

Observed displacement data-based identification method of deformation time-varying effect of high concrete dams

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Science China(Technological Sciences) 2018年第6期61卷 906-915页

作者： wang shaowei GU ChongShi BAO TengFei l School of Environmental and Safety Engineering Changzhou University Changzhou 213164 China State Key Laboratory of Hydrology-Water Resources andHydraulic Engineering Hohai University Nanjing 210098 China

The long-term safety of high concrete dams has become the focus and central issues of public attention. Deformation is an actual comprehensive reflection of concrete dams. Especially the deformation time-varying effect, is a key index for evaluating the structural behavior, health status, and their evolution of a concrete dam in long-term service. In this paper, causing factors of the deformation time-varying effect of concrete dams were analyzed, and the time-varying effect was divided into two parts, which are the inherent time-varying effect and the time-varying effect caused by the change of dam structural performance. Then, based on the observed dam displacement and the wavelet multi-resolution analysis, causal models for identifying the later deformation time-varying effect and the identification process were proposed. Finally, the efficiency and rationality of the proposed method were verified by two actual concrete dams with runoff reservoir and regulatory reservoir.

关键词： high concrete dam deformation time-varying effect causing analysis identification method

Numerical Study of Heat Transfer Characteristic for Subcooled Falling Film outside the Shaped Tubes under Rolling Motion

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Journal of Thermal Science 2023年第3期32卷 922-932页

作者： HAN Hui wang Junqi wang shaowei LI Yuxing Provincial Key Laboratory of Oil and Gas Storage and Transportation Safety in Shandong Province China University of Petroleum(Huadong)Qingdao 266580China

The heat transfer performance of spiral wound heat exchanger used in the floating liquefied natural gas(FLNG)may be significantly affected by the sloshing *** this paper,a three-dimensional numerical model combined with the dynamic mesh technology is conducted to study subcooled falling film heat transfer under static and sloshing *** three-dimensional velocity distribution of the liquid film on the shell side is *** effects of cross-section shape of heat exchange tubes,Reynolds numbers and sloshing parameters on heat transfer characteristics are *** results indicate that the heat transfer performance of the egg-shaped tube is superior to that of the elliptical and circular tube under both static and sloshing conditions due to significant heat transfer improvement in the lower half of the *** heat transfer coefficients of three different kinds of tubes decrease under sloshing *** the rolling amplitude is 6°,the average heat transfer coefficients of the circular tube,elliptical tube and egg-shaped tube are reduced by 2.1%,3.7%and 4.9%*** the current sloshing parameters,increasing the rolling amplitude,the heat transfer coefficients of three different tubes are slightly increased,while the sloshing period has little effect on heat *** egg-shaped tube and elliptical tube are greatly affected by sloshing motion at the low Reynolds number,while the effect is relatively small at the high Reynolds number.

关键词： falling film flow sloshing condition spiral wound heat exchanger floating liquefied natural gas

Toward intelligent wireless communications:Deep learning-based physical layer technologies

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Digital Communications and Networks 2021年第4期7卷 589-597页

作者： Siqi Liu Tianyu wang shaowei wang School of Electronic Science and Engineering Nanjing UniversityNanjingJiangsu210023China

Advanced technologies are required in future mobile wireless networks to support services with highly diverse requirements in terms of high data rate and reliability,low latency,and massive *** Learning(DL),one of the most exciting developments in machine learning and big data,has recently shown great potential in the study of wireless *** this article,we provide a literature review on the applications of DL in the physical ***,we analyze the limitations of existing signal processing techniques in terms of model accuracy,global optimality,and computational ***,we provide a brief review of classical DL ***,we discuss recent DL-based physical layer technologies,including both DL-based signal processing modules and end-to-end *** neural networks are used to replace a single or several conventional functional modules,whereas the objective of the latter is to replace the entire transceiver ***,we discuss the open issues and research directions of the DL-based physical layer in terms of model complexity,data quality,data representation,and algorithm reliability.

关键词： Data-driven Deep learning Physical layer Wireless communications

Machine Learning for 5G and Beyond:From ModelBased to Data-Driven Mobile Wireless Networks

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China Communications 2019年第1期16卷 165-175页

作者： Tianyu wang shaowei wang Zhi-Hua Zhou National Key Laboratory for Novel Software Technology Nanjing University School of Electronic Science and Engineering Nanjing University

During the past few decades,mobile wireless communications have experienced four generations of technological revolution,namely from 1 G to 4 G,and the deployment of the latest 5 G networks is expected to take place in *** fundamental question is how we can push forward the development of mobile wireless communications while it has become an extremely complex and sophisticated *** believe that the answer lies in the huge volumes of data produced by the network itself,and machine learning may become a key to exploit such *** this paper,we elaborate why the conventional model-based paradigm,which has been widely proved useful in pre-5 G networks,can be less efficient or even less practical in the future 5 G and beyond mobile ***,we explain how the data-driven paradigm,using state-of-the-art machine learning techniques,can become a promising *** last,we provide a typical use case of the data-driven paradigm,i.e.,proactive load balancing,in which online learning is utilized to adjust cell configurations in advance to avoid burst congestion caused by rapid traffic changes.

关键词： mobile wireless networks data-driven paradigm machine learning

Mobility-driven user-centric AP clustering in mobile edge computing-based ultra-dense networks

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Digital Communications and Networks 2020年第2期6卷 210-216页

作者： Shuxin He Tianyu wang shaowei wang School of Electronic Science and Engineering Nanjing UniversityNanjing210000China National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China

ultra-Dense Network(UDN)has been envisioned as a promising technology to provide high-quality wireless connectivity in dense urban areas,in which the density of Access Points(APs)is increased up to the point where it is comparable with or surpasses the density of active mobile *** order to mitigate inter-AP interference and improve spectrum efficiency,APs in UDNs are usually clustered into multiple groups to serve different mobile users,***,as the number of APs increases,the computational capability within an AP group has become the bottleneck of AP *** this paper,we first propose a novel UDN architecture based on Mobile Edge Computing(MEC),in which each MEC server is associated with a user-centric AP cluster to act as a mobile *** addition,in the context of MEC-based UDN,we leverage mobility prediction techniques to achieve a dynamic AP clustering scheme,in which the cluster structure can automatically adapt to the dynamic distribution of user traffic in a specific *** results show that the proposed scheme can highly increase the average user throughput compared with the baseline algorithm using max-SINR user association and equal bandwidth allocation,while it guarantees at the same time low transmission delay.

关键词： AP clustering Dynamic user traffic Mobile edge computing Mobility-driven ultra-dense Networks

Numerical study on the hydrodynamics of agglomerates at intermediate Reynolds numbers

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Chinese Journal of Chemical Engineering 2020年第6期28卷 1533-1541页

作者： Huanpeng Liu shaowei wang Chenyu Yang Taiping Chen School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The flow pattern and hydrodynamics of a heterogeneous permeable agglomerate in a uniform upward flow at intermediate Reynolds numbers(1–40)are analyzed from three-dimensional(3 D)computational fluid dynamics *** from the homogeneous or stepwise-varying permeability models used in previous papers,a continuously radially varying permeability model is used in the present *** effects of two dimensionless parameters,the Reynolds number and the permeability ratio,on the flow field and the hydrodynamics were investigated in *** results reveal that unlike the solid sphere,a small recirculating wake initially forms inside the *** critical Reynolds number for the formation of the recirculating wake is lower than that of the solid sphere and it decreases with the increase of permeability ratio.A correlation of drag coefficient as a function of the Reynolds number and permeability ratio is *** of drag coefficients obtained by different permeability models show that at intermediate Reynolds numbers(1–40),the effect of radially varying permeability on the drag coefficient must be considered.

关键词： Agglomerate Permeability Reynolds number Drag coefficient

Numerical solution of oscillatory flow of Maxwell fluid in a rectangular straight duct

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Applied Mathematics and Mechanics(English Edition) 2019年第11期40卷 1647-1656页

作者： Xuyang SUN shaowei wang Moli ZHAO Qiangyong ZHANG Department of Engineering Mechanics School of Civil Engineering Shandong University

A numerical analysis is presented for the oscillatory flow of Maxwell fluid in a rectangular straight duct subjected to a simple harmonic periodic pressure *** numerical solutions are obtained by a finite difference scheme *** stability of this finite difference scheme method is *** distributions of the velocity and phase difference are given numerically and *** effects of the Reynolds number,relaxation time,and aspect ratio of the cross section on the oscillatory flow are *** results show that when the relaxation time of the Maxwell model and the Reynolds number increase,the resonance phenomena for the distributions of the velocity and phase difference enhance.

关键词： Maxwell fluid oscillatory flow finite difference method rectangular duct