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Journal of Systems Science & Complexity 2019年第3期32卷 888-906页

作者： QIN Yaling YUE Dequan School of Economics and Management Yanshan University Qinhuangdao 066004 China LiRen College Yanshan University Qinhuangdao 066004 China College of Science Yanshan University Qinhuangdao 066004 China

This paper considers a production inventory system with service time and product returns, dependent on the characteristics of online shopping beliaviors. The customers arrive according to a Poisson process, in which the arriving customer requires an item in the inventory, as well as a server service that the service time is exponentially distributed. Moreover, there is one production facility to produce items according to (s, S) policy, and the production time also follows an exponential (listribution. In the beginning, the stationary joint distribution is obtained in the product form for the queue length and the on-hand inventory level. Additionally, the resulting distribution is applied to derive some performance measures, which can be adopted to numerically calculate the optimal (s, S) policy. Finally, numerical analyses are processed to investigate the effects of some system parameters on the performance measures. The numerical results clearly indicate that the product return rate has a significantly monotonic effect on the optimal policy and optimal cost.

关键词： Online shopping production inventory return service time (s, S) policy

Dynamic behavior of new cutting subgrade structure of expensive soil under train loads coupling with service environment

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Journal of Central South University 2017年第4期24卷 875-890页

作者： QIU Ming-ming YANG Guo-lin SHEN Quan YANG Xiao WANG Gang LIN Yu-liang School of Civil Engineering Central South University Department of Civil Engineering Monash University

Expansive soil is sensitive to dry and wet environment change. And the volume deformation and inflation pressure of expansive soil may induce to cause the deformation failure of roadbed or many other adverse effects. Aimed at a high-speed railway engineering practice in the newly built Yun-Gui high-speed railway expansive soil section in China, indoor vibration test on a full-scaled new cutting subgrade model is carried out. Based on the established track-subgrade-foundation of expansive soil system dynamic model test platform, dynamic behavior of new cutting subgrade structure under train loads coupling with extreme service environment(dry, raining, and groundwater level rising) is analyzed comparatively. The results show that the subgrade dynamic response is significantly influenced by service conditions and the dynamic response of subgrade gradually becomes stable with the increasing vibration times under various service environment conditions. The vertical dynamic soil stress is related with the depth in an approximate exponential function, and the curves of vertical dynamic soil stress present a "Z" shape distribution along transverse distance. The peak value of dynamic soil stress appears below the rail, and it increases more obviously near the roadbed surface. However, the peak value of dynamic soil stress is little affected outside 5.0 m of center line. The vibration velocity and acceleration are in a quadratic curve with an increase in depth, and the raining and groundwater level rising increase both the vibration velocity and the acceleration. The vertical deformations at different depths are differently affected by service environment in roadbed. The deformation of roadbed increases sharply when the water gets in the foundation of expansive soil, and more than 60% of the total deformation of roadbed occurs in expansive soil foundation. The laid waterproofing and drainage structure layer, which weakens the dynamic stress and improves the track regularity,

关键词： high-speed railway full-scale model testing dynamic response expansive soil service environment new subgrade structure

Vehicle-to-grid service development logic and management formulation

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Journal of Modern Power Systems and Clean Energy 2019年第4期7卷 935-947页

作者： Lefeng SHI Tong LV Yandi WANG School of Economics and Management Chongqing Normal UniversityChongqing 401331China School of Electrical Engineering Shandong UniversityJinan 250061China

Vehicle-to-grid(V2G)is regarded as the effective way to reconcile contradictions between an electric power system and electric vehicles(EVs).A lot of research has been carried out to affect this,often based on different technical and trade model *** value of theresearch is dependent on how reasonable the assumptions it makes *** paper presents a framework for analyzing V2G service development from a coevolutionary perspective in which the interactive relation between the diffusion of EVs and the upgrade of the distribution grid system is considered.A V2G service development logic and its management formulation are put ***,the motivations and contradictions of developing V2G services are *** a development phase division of the V2G services is proposed in view of the coevolution relation between the grid upgrade and the development of the ***,taking into account the characteristics of each phase,the physical trade structures and corresponding management hierarchies,management relations as well as management measures,are *** paper provides a new perspective of V2G service development,answers the core question on how to make the V2G vision come true in synergy with the development of EVs,and gives some advice on future V2G management paradigms.

关键词： Electric vehicle Vehicle-to-grid service Smart grid Aggregator

A field-based service management and discovery method in multiple clouds context

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Frontiers of Computer Science 2019年第5期13卷 976-995页

作者： Shuai ZHANG Xinjun MAO Fu HOU Peini LIU College of Computer National University of Defense Technology Changsha 410073 China National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

In diverse and self-governed multiple clouds context, the service management and discovery are greatly challenged by the dynamic and evolving features of services. How to manage the features of cloud services and support accurate and efficient service discovery has becomean open problem in the area of cloud computing. This paper proposes a field model of multiple cloud services and corresponding service discovery method to address the issue. Different from existing researches, our approach is inspired by Bohr atom model. We use the abstraction of energy level and jumping mechanism to describe services status and variations, and thereby to support the service demarcation and discovery. The contributions of this paper are threefold. First, we propose the abstraction of service energy level to represent the status of services, and service jumping mechanism to investigate the dynamic and evolving features as the variations and re-demarcation of cloud services according to their energy levels. Second, we present user acceptable service region to describe the services satisfying users' requests and corresponding service discovery method, which can significantly decrease services search scope and improve the speed and precision of service discovery. Third, a series of algorithms are designed to implement the generation of field model, user acceptable service regions, service jumping mechanism, and user-oriented service discovery. We have conducted an extensive experiments on QWS dataset to validate and evaluate our proposed models and algorithms. The results show that field model can well support the representation of dynamic and evolving aspects of services in multiple clouds context and the algorithms can improve the accuracy and efficiency of service discovery.

关键词： service field service energy level service jumping service management service discovery multiple clouds

Mean-field Macro Computation in Large-scale Cloud service Systems with Resource Management and Job Scheduling

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Journal of Systems Science and Systems Engineering 2019年第2期28卷 238-261页

作者： Feifei Yang Yanping Jiang Quanlin Li School of Business Administration Northeastern University Shenyang 110167 China School of Economics and Management Beijing University of Technology Beijing 100124 China

service computing is an emerging and distributed computing mode in cloud service systems, and has become an interesting research direction for both academia and industry. Note that the cloud service systems always display new characteristics, such as stochasticity, large scale, loose coupling, concurrency non-homogeneity and heterogeneity;thus their load balancing investigation has been more interesting, difficult and challenging until now. By using resource management and job scheduling, this paper proposes an integrated, real-time and dynamic control mechanism for large-scale cloud service systems and their load balancing through combining supermarket models with not only work stealing models but also scheduling of public reserved resource. To this end, this paper provides a novel stochastic model with weak interactions by means of nonlinear Markov processes. To overcome theoretical difficulties growing out of the state explosion in high-dimensional stochastic systems, this paper applies the mean-field theory to develop a macro computational technique in terms of an infinite-dimensional system of mean-field equations. Furthermore, this paper proves the asymptotic independence of the large-scale cloud service system, and show how to compute the fixed point by virtue of an infinite-dimensional system of nonlinear equations. Based on the fixed point, this paper provides effective numerical computation for performance analysis of this system under a high approximate precision. Therefore, we hope that the methodology and results given in this paper can be applicable to the study of more general large-scale cloud service systems.

关键词： Large-scale cloud service system resource management job scheduling supermarket model work stealing model scheduling of public reserved resource

Extracting commuter-specific destination hotspots from trip destination data-comparing the boro taxi service with Citi Bike in NYC

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Geo-Spatial Information Science 2020年第2期23卷 141-152页

作者： Andreas Keler Jukka M.Krisp Linfang Ding Department of Civil Geo and Environmental EngineeringTechnical University of MunichMunichGermany Applied Geoinformatics Institute of GeographyUniversity of Augsburg(UniA)AugsburgGermany The KRDB Research Centre for Knowledge and Data Free University of Bozen-BolzanoBozen-BolzanoItaly Department of Cartography Technical University of MunichMunichGermany

Taxi trajectories from urban environments allow inferring various information about the transport service qualities and commuter *** is possible to associate starting and end points of taxi trips with requirements of individual groups of people and even social *** research shows that due to service restrictions,boro taxis have typical customer destination locations on selected Saturdays:many drop-off clusters appear near the restricted zone,where it is not allowed to pick up customers and only few drop-off clusters appear at complicated *** crossings imply recent infrastructural *** want to follow up on these results and add one additional group of commuters:Citi Bike *** selected Saturdays in June 2015,we want to compare the destinations of boro taxi and Citi Bike *** is challenging due to manifold differences between active mobility and motorized road users,and,due to the fact that station-based bike sharing services are restricted to *** and end points of trips,as well as the volumes in between rely on specific numbers of bike sharing ***,we introduce a novel spatiotemporal assigning procedure for areas of influence around static bike sharing stations for extending available computational methods.

关键词： Urban transportation spatial analysis mobility patterns boro taxis vehicle fleets bicycle-sharing service

Review of service Restoration for Distribution Networks

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Journal of Modern Power Systems and Clean Energy 2020年第1期8卷 1-14页

作者： Feifan Shen Qiuwei Wu Yusheng Xue Center for Electric Power and Energy Department of Electrical EngineeringTechnical University of DenmarkLyngbyDenmark State Grid Electric Power Research Institute NanjingChina

With the rapid deployment of the advanced metering infrastructure(AMI)and distribution automation(DA),selfhealing has become a key factor to enhance the resilience of distribution *** a permanent fault occurrence,the distribution network operator(DNO)implements the selfhealing scheme to locate and isolate the fault and to restore power supply to out-of-service *** an essential component of self-healing,service restoration has attracted considerable *** paper mainly reviews the service restoration approaches of distribution networks,which requires communication *** service restoration approaches can be classified as centralized,distributed,and hierarchical approaches according to the communication *** these approaches,different techniques are used to obtain service restoration solutions,including heuristic rules,expert systems,metaheuristic algorithms,graph theory,mathematical programming,and multi-agent ***,future research areas of service restoration for distribution networks are discussed.

关键词： Distribution networks fault detection fault isolation service restoration self-healing scheme

An effective method for service components selection based on micro-canonical annealing considering dependability assurance

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Frontiers of Computer Science 2019年第2期13卷 264-279页

作者： Shichen ZOU Junyu LIN Huiqiang WANG Hongwu LV Guangsheng FENG College of Computer Science and Technology Harbin Engineering University Harbin 150001 China Institute of Information Engineering Chinese Academy of Sciences Beijing 100093 China Department of Electrical and Computer Engineering University of Victoria Victoria V8W 3P6 Canada

Distributed virtualization changes the pattern of building software systems. However, it brings some problems on dependability assurance owing to the complex social relationships and interactions between service components. The best way to solve the problems in a distributed virtualized environment is dependable service components selection. Dependable service components selection can be modeled as finding a dependable service path, which is a multiconstrained optimal path problem. In this paper, a service components selection method that searches for the dependable service path in a distributed virtualized environment is proposed from the perspective of dependability assurance. The concept of Quality of Dependability is introduced to describe and constrain software system dependability during dynamic composition. Then, we model the dependable service components selection as a multiconstrained optimal path problem, and apply the Adaptive Bonus-Penalty Microcanonical Annealing algorithm to find the optimal dependable service path. The experimental results show that the proposed algorithm has high search success rate and quick converges.

关键词： service components selection dependability assurance distributed virtualization microcanonical annealing

Evaluation of increasing service life of epoxy zinc-rich coating on 3 wt.%Ni-advanced low-alloy steel in marine atmospheric environment

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Journal of Iron and Steel Research International 2022年第4期29卷 698-706页

作者： Sheng-rong Wang Jian-wei Yang Jian-ping Cao Shan Jiang Fei-fan Xu Shougang Research Institute of Technology of Shougang Group Co. Ltd.Beijing 100043China Beijing Key Laboratory of Green Recyclable Process for Iron&Steel Production Technology Beijing 100043China

The addition of Ni element into steel to prolong the service life of coated steel was investigated in marine atmospheric environment by laboratory simulated accelerated *** scanning electron microscope and electron probe microanalysis combined with electrochemical impedance spectroscopy were used to characterize coated steel properties and examined the anti-corrosion *** results showed that 3 wt.%Ni-advanced steel(3Ni steel)substrate obviously delayed the failure time of coating compared to carbon steel,therefore prolonging the service life of coating on the steel.X-ray diffraction patterns for the corrosion products under the scratched coating on 3Ni steel exhibited that FeNi_(2)O_(4) and Fe_(2)O_(3) occurred in the corrosion product of 3Ni *** was also found that Ni element enriched in the product layer through analyzing the appearance and composition of corrosion products by electron probe *** ions were blocked out of product by the enrichment of Ni element in rust layer.

关键词： 3wt.% Ni-advanced low-alloy steel Coating failure service life Corrosion product Marine atmosphere

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Frontiers of Computer Science 2019年第2期13卷 231-246页

作者： Min GAO Bin LING Linda YANG Junhao WEN Qingyu XIONG Shun LI Key Laboratory of Dependable service Computing in Cyber Physical Society (Chongqing University) Ministry of Education Chongqing 400044 China School of Software Engineering Chongqing University Chongqing 400044 China School of Engineering University of Portsmouth Portsmouth PO1 3 AH UK

Collaborative filtering (CF) is a technique commonly used for personalized recommendation and Web service quality-of-service (QoS) prediction. However, CF is vulnerable to shilling attackers who inject fake user profiles into the system. In this paper, we first present the shilling attack problem on CF-based QoS recommender systems for Web services. Then, a robust CF recommendation approach is proposed from a user similarity perspective to enhance the resistance of the recommender systems to the shilling attack. In the approach, the generally used similarity measures are analyzed, and the DegSim (the degree of similarities with top k neighbors) with those measures is selected for grouping and weighting the users. Then, the weights are used to calculate the service similarities/differences and predictions. We analyzed and evaluated our algorithms using WS-DREAM and Movielens datasets. The experimental results demonstrate that shilling attacks influence the prediction of QoS values, and our proposed features and algorithms achieve a higher degree of robustness against shilling attacks than the typical CF algorithms.

关键词： collaborative filtering service recommendation system robustness shilling attack