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Customer Joining Behavior and Regulation Strategy in Visible Multi-Server Queues with Synchronous Vacations of Partial Servers

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Journal of Systems Science & Complexity 2024年第3期37卷 1209-1232页

作者： sun wei WANG Hao XIE Xumeng LI Shiyong School of Economics and Management Yanshan UniversityQinhuangdao 066004China

This paper studies customer joining behavior and system regulation strategy in nonexhaustive visible M/M/m queues with synchronous vacations of a part of the *** this part of the servers are idle,they take multiple vacations simultaneously(vacation period).Until there are customers waiting in the queue,they are reactivated and all servers are busy or idle(busy period).The authors call this part of the servers as“partial servers”.In view of the fully visible queue and the almost visible queue,the authors obtain customers’equilibrium joining threshold strategies and their socially optimal joining threshold strategies,respectively,and observe that customer joining behavior in equilibrium generally makes the system overcrowded,which makes the equilibrium social welfare lower than the optimal social *** regulation,interestingly,for optimizing social welfare,the system manager hopes not only customers arriving in vacation period pay attention to the number of partial servers,but also customers arriving in busy period should care about it rather than ***,arranging more servers for vacation does not necessarily lead to the decrease of social welfare on condition that the number of partial servers is close to *** for the information advantage of the fully visible case,it is not obvious for increasing social welfare and even unfavorable to servers’profit unless the number of partial servers is big ***,given the different composition of social welfare,there exists the optimal number of partial servers and the optimal arrival rate of customers for maximizing social welfare.

关键词： Customer behavior non-exhaustive service partial servers regulation strategy synchronous vacations visible queue

Non-Convex Optimization of Resource Allocation in Fog Computing Using Successive Approximation

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Journal of Systems Science & Complexity 2024年第2期37卷 805-840页

作者： LI Shiyong LIU Huan LI Wenzhe sun wei School of Economics and Management Yanshan UniversityQinhuangdao 066000China

Fog computing can deliver low delay and advanced IT services to end users with substantially reduced energy ***,with soaring demands for resource service and the limited capability of fog nodes,how to allocate and manage fog computing resources properly and stably has become the ***,the paper investigates the utility optimization-based resource allocation problem between fog nodes and end users in fog *** authors first introduce four types of utility functions due to the diverse tasks executed by end users and build the resource allocation model aiming at utility ***,for only the elastic tasks,the convex optimization method is applied to obtain the optimal results;for the elastic and inelastic tasks,with the assistance of Jensen’s inequality,the primal non-convex model is approximated to a sequence of equivalent convex optimization problems using successive approximation ***,a two-layer algorithm is proposed that globally converges to an optimal solution of the original ***,numerical simulation results demonstrate its superior performance and *** with other works,the authors emphasize the analysis for non-convex optimization problems and the diversity of tasks in fog computing resource allocation.

关键词： Fog computing non-convex optimization optimal resource allocation successive approximation method utility function

A Two-stage Service-oriented Task Offloading Framework with Edge-cloud Collaboration:A Game Theory Approach

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Journal of Systems Science and Systems Engineering 2024年第5期33卷 521-551页

作者： Shiyong Li Wenzhe Li Huan Liu wei sun School of Economics and Management Yanshan UniversityQinhuangdao 066004

With the fast development of Mobile Internet,data traffic generated by end devices is anticipated to witness substantial growth in the future ***,processing tasks locally will cause latency due to the limited resources of the end ***-cloud collaboration,an effective solution for latency-sensitive applications,is attracting greater attention from both industry and *** combines the advantages of the cloud center with abundant computing resources and edge nodes with low-latency *** this paper,we propose a two-stage task offloading framework with edge-cloud collaboration to assist end devices processing latency-sensitive tasks either on the edge servers or in the cloud *** for homogeneous task offloading,in the first stage,the competitive end devices offload tasks to the edge *** formulate the selfish task offloading problem among end devices as a potential *** the second stage,the edge nodes request resources from the cloud center to process end devices tasks due to their limited ***,we consider the heterogeneous task offloading problem and use intelligent optimization algorithm to obtain the optimal offloading *** results show that the service prices of edge nodes influence the decisions and task offloading costs of end *** also verify the intelligent optimization algorithm can achieve optimal performance with low complexity and fast convergence.

关键词： Edge-cloud collaboration task offloading potential game simulation annealing algorithm

Utilizing N-hydroxy-9-octadecenamide as a collector in flotation separation of bastnaesite and fluorite

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Journal of Rare Earths 2024年第8期42卷 1620-1628,I0008页

作者： Zhihao Guo Sultan Ahmed Khoso Mengjie Tian wei sun School of Minerals Processing and Bioengineering Central South UniversityChangsha410083China State Key Laboratory of Mineral Processing Beijing102600China Hubei Key Laboratory for Efficient Utilization and Agglomeration of Metallurgic Mineral Resources Wuhan430081China Key Laboratoryof Hunan Province for Cleanand Efficient Utilization of Strategic Calcium-containing Mineral Resources Central South UniversityChangsha410083China Department of Mining Engineering Mehran University of Engineering&TechnologyJamshoro76062Pakistan

Bastnaesite((Ce,La,Pr,Nd)CO_(3)F) is a significant light rare earth mineral found in nature,known for its fine-grained *** is commonly employed for the recovery of fine-grained bastnaesite *** serve as an essential flotation reagent that enhance the surface hydrophobicity of target minerals.A novel collector,N-hydroxy-9-octadecenamide(N-OH-9-ODA),was synthesised in this study.N-OH-9-ODA exhibits superior selectivity compared to the traditional collector oleic acid in the flotation separation of bastnaesite and *** experimental and co mputational results indicate that N-OH-9-ODA exhibits superior selectivity due to its higher adsorption affinity for bastnaesite surface compared to fluorite *** zeta potential and the binding energies of the Ce 3d peaks in the X-ray photoelectron spectrum(XPS) of bastnaesite surface exhibit significant ***,fluorite surface demonstrates minimal alterations in its zeta potential and the binding energies of the Ca 2p peaks in its XPS after its interaction with N-OH-9-ODA.

关键词： Bastnaesite Collector Hydroxamic acids N-hydroxy-9-octadecenamide Oleic acid Rare earths

Reduced-order modeling and vibration transfer analysis of a fluid-delivering branch pipeline that consider fluid–solid interactions

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Frontiers of Mechanical Engineering 2024年第2期19卷 75-97页

作者： Wenhao JI Hongwei MA wei sun Yinhang CAO School of Mechanical Engineering and Automation Northeastern UniversityShenyang 110819China Key Laboratory of Vibration and Control of Aero-Propulsion Systems(Ministry of Education) Northeastern UniversityShenyang 110819China College of Power and Energy Engineering Harbin Engineering UniversityHarbin 150001China

The efficient dynamic modeling and vibration transfer analysis of a fluid-delivering branch pipeline(FDBP)are essential for analyzing vibration coupling effects and implementing vibration reduction ***,this study proposes a reduced-order dynamic modeling method suitable for FDBPs and then analyzes the vibration transfer *** the modeling method,the finite element method and absorbing transfer matrix method(ATMM)are integrated,considering the fluid–structure coupling effect and fluid *** dual-domain dynamic substructure method is developed to perform the reduced-order modeling of FDBP,and ATMM is adopted to reduce the matrix order when solving fluid ***,the modeling method is validated by experiments on an H-shaped branch ***,transient and steady-state vibration transfer analyses of FDBP are performed,and the effects of branch locations on natural characteristics and vibration transfer behavior are *** show that transient vibration transfer represents the transfer and conversion of the kinematic,strain,and damping energies,while steady-state vibration transfer characteristics are related to the vibration *** addition,multiple-order mode exchanges are triggered when branch locations vary in frequency-shift regions,and the mode-exchange regions are also the transformation ones for vibration transfer patterns.

关键词： fluid-delivering branch pipeline vibration transfer analysis reduced-order modeling fluid-solid interactions finite element method absorbing transfer matrix method

Natural marmatite photocatalyst for treatment of mineral processing wastewater to help zero wastewater discharge

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Journal of Environmental Sciences 2024年第8期142卷 83-91页

作者： Meirong Wu wei sun Xiangsong Meng Jianhua Kang Yue Yang School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083China Key Laboratory of Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral Resources Central South UniversityChangsha 410083China

Mineral processing wastewater(MPW)with large discharge and high toxicity affects environmental safety,and the realizing zero discharge of MPW is of great significance for reducing environmental pollution,saving water resources,and promoting the sustainable development of the mining *** this study,we reported natural marmatite(NM)as a low-cost and efficient photocatalyst for the treatment of MPW to help zero wastewater *** photocatalytic activity of NM was evaluated by the removal of total organic carbon(TOC)from MPW under visible-light illumination,and the optimal degradation conditions were *** showed that superoxide free radicals(^(·)O_(2)^(-))were the dominant active species responsible for organic pollutants degradation,and 74.25%TOC removal was obtained after 120 min reaction under the optimum treatment ***,the wastewater treated by NM photocatalysis can be reused in the flotation system without adverse impact on the product *** on these findings,a model of zero wastewater discharge for flotation with the help of photocatalytic treatment was established,it indicated that the water of the whole system can be balanced without affecting the ore dressing index,which showed that visible light-driven photocatalyst has a promising application prospect in the treatment and recycling of industrial wastewater.

关键词： Natural mineral Photocatalysis Industrial wastewater Wastewater recycling Water balance

Exploring changes of precipitation extremes under climate change through global variable-resolution modeling

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Science Bulletin 2024年第2期69卷 237-247页

作者： wei sun Jian Li Rucong Yu Nina Li Yi Zhang State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China Institute of Tibetan Plateau Meteorology China Meteorological AdministrationChengdu 610072China Department of Atmospheric Science Yunnan UniversityKunming 650091China National Meteorological Center China Meteorological AdministrationBeijing 100081China 2035 Future Laboratory PIESAT Information Technology Co.Ltd.Beijing 100105China

Understanding the responses of precipitation extremes to global climate change remains limited owing to their poor representations in models and complicated interactions with multi-scale *** we take the record-breaking precipitation over China in 2021 as an example,and study its changes under three different climate scenarios through a developed pseudo-global-warming(PGW)experimental framework with 60-3 km variable-resolution global ensemble *** to the present climate,the precipitation extreme under a warmer(cooler)climate increased(decreased)in intensity,coverage,and total amount at a range of 24.3%-37.8%(18.7%-56.1%).With the help of the proposed PGW experimental framework,we further reveal the impacts of the multi-scale system interactions in climate change on the precipitation *** the warmer climate,large-scale water vapor transport converged from double typhoons and the subtropical high marched into central China,enhancing the convective energy and instability on the leading edge of the transport *** a result,the mesoscale convective system(Mcs)that directly contributed to the precipitation extreme became stronger than that in the present *** the contrary,the cooler climate displayed opposite changing characteristics relative to the warmer climate,ranging from the large-scale systems to local environments and to the *** summary,our study provides a promising approach to scientifically assess the response of precipitation extremes to climate change,making it feasible to perform ensemble simulations while investigating the multi-scale system interactions over the globe.

关键词： Precipitation extreme Climate change Pseudo-global-warming experiment Variable-resolution modeling Multi-scale system interaction

Ultralow friction PTFE/PEEK heterolayer:A new solid lubrication approach toward simplicity

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Friction 2024年第1期12卷 120-135页

作者： wei sun Jiaxin YE Qingrui SONG Yi FENG Xiaojun LIU School of Materials Science and Engineering Hefei University of TechnologyHefei 230009China Institute of Tribology School of Mechanical EngineeringHefei University of TechnologyHefei 230009China

Tribological applications of polytetrafluoroethylene(PTFE)are often limited by technological complexity to overcome its poor wear ***,a PTFE/polyetheretherketone(PEEK)heterolayer(HL)was proposed and evaluated as a new solid lubrication ***-on-disk tribometry found the lowest friction coefficient(μ)of 0.031 and ultralow wear for the PEEK/HL under typical *** friction coefficient of the HL surpasses those of the state-of-the-art polymeric coatings/composites by at least 200%,and approaches that of highly lubricated *** investigations revealed multi-length physical and chemical heterogeneity of the HL that best facilitates a tribofilm with high subsurface stability and surface *** technological simplicity and robustness of the HL’s high lubricity make it a promising new type of solid lubrication toward greater reliability and longevity.

关键词： ultralow friction anti-wear polytetrafluoroethylene(PTFE) heterolayer(HL)

Engineering vascularized organotypic tissues via module assembly

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International Journal of Extreme Manufacturing 2024年第1期6卷 155-175页

作者： Zhenzhen Zhou Changru Liu Yuting Guo Yuan Pang wei sun Biomanufacturing Center Department of Mechanical EngineeringTsinghua UniversityHaidian DistrictBeijing 100084People’s Republic of China Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Beijing 100084People’s Republic of China Key Laboratory for Advanced Materials Processing Technology Ministry of EducationBeijing 100084People’s Republic of China Department of Mechanical Engineering Drexel UniversityPhiladelphiaPA 19104United States of America

Adequate vascularization is a critical determinant for the successful construction and clinical implementation of complex organotypic tissue models. Currently, low cell and vessel density and insufficient vascular maturation make vascularized organotypic tissue construction difficult,greatly limiting its use in tissue engineering and regenerative medicine. To address these limitations, recent studies have adopted pre-vascularized microtissue assembly for the rapid generation of functional tissue analogs with dense vascular networks and high cell density. In this article, we summarize the development of module assembly-based vascularized organotypic tissue construction and its application in tissue repair and regeneration, organ-scale tissue biomanufacturing, as well as advanced tissue modeling.

关键词： vascularized organotypic tissue module assembly regenerative medicine tissue engineering