Research on service capacity of widened intersection based on traffic simulation

Delay analysis method is adopted to study the service capacity of a widened intersection. Traffic simulation software VISSIM is used for microscopic simulation of a widened intersection so as to obtain a delay curve. The delay-volume model of a widened intersection is established based on traffic simulation. The suggested value of basic service capacity of the widened left-turn lane is given along with how to determine correction factors and practical service capacity.

Service delivery time guarantee decisions with consideration of the time and price sensitive customer

Based on the assumption that the customer is time and price sensitive and price is a piecewise function of the delivery time, a service delivery time guarantee decision model is proposed, and the existence of the optimal service delivery time guarantee L^＊ is proved. Furthermore, the impact of the correlation parameters on the optimal L^＊ is analyzed. It is revealed that if the optimal L^＊ is smaller than the industry level L0, the service provider with low cost should quote a shorter delivery time, and the service provider should increase the delivery time guarantee under the conditions of the decrease in customer time sensitivity or the increase in the difference of the customer reservation payment. When L^＊ 〉 L0, the service provider should quote a longer delivery time guarantee and should increase the delivery time guarantee and reduce the price under the conditions of the increase in the customer price sensitivity or the decrease in the mean customer reservation payment.

Semantic Social Service Organization Mechanism in Cyber Physical System

Cyber physical system(CPS)provides more powerful service by cyber and physical features through the wireless communication.As a kind of social organized network system,a fundamental question of CPS is to achieve service self-organization with its nodes autonomously working in both physical and cyber environments.To solve the problem,the social nature of nodes in CPS is firstly addressed,and then a formal social semantic descriptions is presented for physical environment,node service and task in order to make the nodes communicate automatically and physical environment sensibly.Further,the Horn clause is introduced to represent the reasoning rules of service organizing.Based on the match function,which is defined for measurement between semantics,the semantic aware measurement is presented to evaluate whether environment around a node can satisfy the task requirement or not.Moreover,the service capacity evaluation method for nodes is addressed to find out the competent service from both cyber and physical features of nodes.According to aforementioned two measurements,the task semantic decomposition algorithm and the organizing matrix are defined and the service self-organizing mechanism for CPS is proposed.Finally,examinations are given to further verify the efficiency and feasibility of the proposed mechanism.

我国疫苗可预防性疾病一级预防服务能力分析

目的 分析2019年我国31个省(自治区、直辖市)和东、中、西部疫苗可预防性疾病(vaccine preventable disease,VPD)一级预防服务能力水平、2004—2019年的变化趋势及其与发病率的关系,为提升预防服务能力,究善VPDs防控工作提供参考。方法 收集31个省(自治区、直辖市)2004—2019年所有涉及VPDs的法律法规和政策等公开文件,基于文本分析方法量化计算一级预防服务能力和变化趋势,并运用相关分析检验其与VPDs发病率的相关性。结果 2019年我国VPDs一级预防服务能力达到57.02%,与2004年相比增长61.44%,但健康教育、疾病和危险因素监测、危险因素控制或行为干预的服务可考核率仅为40.80%、29.98%、18.60%;东、中、西部地区VPDs一级预防服务能力分别为69.09%、52.15%、49.19%,东部服务覆盖程度与可考核程度均超过中、西部;我国层面的VPDs一级预防服务能力与发病率之间呈现负相关(r=-0.693,P<0.01)。结论 2004年以来我国VPDs一级预防服务能力具有提升,但是各地区之间能力存在差异,进一步提升VPDs预防服务能力需要“扩面”与“提质”兼顾。

Adaptive Optimal Capacity Perception and Control for Wireless Multi-Hop Networks

In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communicating nodes. In this paper, we present a state-based channel capacity perception scheme to provide statistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wireless multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capacity, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a network resource and forwards the data packet by taking into consideration the channel capacity deployments in multi-terminal or multi-hop mesh networks. Extensive computer simulations demonstrate that the proposed scheme can achieve better performance in terms of packet delivery ratio and network throughput compared to the existing capacity prediction schemes.

A virtual machine-based invasion detection system for the virtual computing environment

Under virtualization idea based on large-scale dismantling and sharing, the implementing of network interconnection of calculation components and storage components by loose coupling, which are tightly coupling in traditional server, achieves computing capacity, storage capacity and service capacity distri- bution according to need in application-level. Under the new server model, the segregation and protection of user space and system space as well as the security monitoring of virtual resources are the important factors of ultimate security guarantee. This article presents a large-scale and expansible distributed invasion detection system of virtual computing environment based on virtual machine. The system supports security monitoring management of global resources and provides uniform view of security attacks under virtual computing environment, thereby protecting the user applications and system security under capacity services domain.

Five Major Concerns about China’s Wind Power Development

Economic issue is the very focus of China's wind power development.Although all the security problems can be dealt with through technical measures,the compensation for supportive thermal power units and the subsidy from economically developed regions to resource-outputting regions would require a higher level of strategic considerations.The core purpose of developing wind energy is to reduce pollutant emissions,so planners should take into account the overall cost of all sides,without touching the bottom of social affordability.

Comparison of Gatekeeping and Non-gatekeeping Designs in a Service System with Delay-sensitive Customers

This paper is motivated by a concern in China's current medical practice in which patients can bypass the primary care and seek secondary care directly.We employ a queueing approach to examine two settings,i.e.the gatekeeping and non-gatekeeping settings,in a service system consisting of two types of service provider-one with basic skills(C-H),e.g.community hospital,and the other with advanced skills(AAA-H),e.g.specialist hospital.Customers are heterogeneous with respect to service requirement.The C-H can only serve customers with a complexity level of service requirement lower than the cure threshold,while the AAA-H can serve all customers.We aim to analyze the social planner's capacity decision for the C-H in both settings and assess the relative merit of each setting with respect to total social welfare,i.e.the sum of customer benefits net of customer delay costs and service providers7 operating costs.Our findings show that when the C-H's capacity is exogenous,the gatekeeper setting is preferable if the capacity of the C-H is in the intermediate range because customers'self-selection behavior gives rise to negative externality.When the C-H's capacity is optimized by the social planner,the non-gatekeeping setting is preferable if the capacity of the AAA-H is large or the cure threshold is high,because customers'self-selection behavior as well as the investment in the C-H's capacity can result in a better distribution of demand among the two service providers.The gatekeeping setting is preferable if the cure threshold is low because it is economical for the social planner to invest in a large capacity in the C-H to serve all customers.We also show numerically the conditions under which the two settings can achieve the first-best solution.

A Model of Grid Service Capacity

Computational grids （CGs） are large scale networks of geographically distributed aggregates of resource clusters that may be contributed by distinct organizations for the provision of computing services such as model simulation, compute cycle and data mining. Traditionally, the decision-making strategies underlying the grid management mechanisms rely on the physical view of the grid resource model. This entails the need for complex multi-dimensional search strategies and a considerable level of resource state information exchange between the grid management domains. In this paper we argue that with the adoption of service oriented grid architectures, a logical service-oriented view of the resource model provides a more appropriate level of abstraction to express the grid capacity to handle incoming service requests. In this respect, we propose a quantification model of the aggregated service capacity of the hosting environment that is updated based on the monitored state of the various environmental resources required by the hosted services. A comparative experimental validation of the model shows its performance towards enabling an adequate exploitation of provisioned services.

Why rapid urbanization can’t improve employment absorption capacity of service industry in China:reflections on innovating the model of interaction between service industry development and urbanization under economic transformation and upgrading

Mathematical models show that the urbanization process is an important factor affecting the transfer of labor among economic sectors.The regression results using time-series data since China’s reform and opening up show that there is significant positive correlation between urbanization and the service industry’s ability to create jobs.However,there is no Granger Causation between them.Therefore,China should shift from focusing on industry park construction to paying more attention to improving urban functions by increasing their employment density of urban services.

Free-riders Impact on Throughputs of Peer-to-peer File-sharing Systems

In a peer-to-peer file-sharing system, a free-rider is a node which downloads files from its peers but does not share files to other nodes. Analyzing the free-riders’ impact on system throughputs is essential in examining the performance of peer-to-peer file-sharing systems. We find that the free-riders’ impact largely depends on nodes behavior, including their online time and greed of downloading files. We extend an existing peer-to-peer system model and classify nodes according to their behavior. We focus on two peer-to-peer architectures: centralized indexing and distributed hash tables. We find that when the cooperators in a system are all greedy in downloading files, the system throughput has little room to increase while the cooperators throughput degrade badly with the increasing percent of greedy free-riders in the system. When all the cooperators are non-greedy with long average online time, the system throughput has much room to increase and the cooperators throughput degrade little with a high percent of greedy free-riders in the system. We also find that if a system can tolerate a high percent of greedy free-riders without suffering much throughput degradation, the system must contain some non-greedy cooperators that contribute great idle service capacity to the system.