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Admission Control Based on QoS for Third Generation Broadband Mobile Communication Systems
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作者 侯春萍 常倩 +1 位作者 曹达仲 范仲方 《Transactions of Tianjin University》 EI CAS 2002年第2期110-113,共4页
In this paper, a novel admission scheme is proposed which provides high degrees of quality of service (QoS) guarantees for multimedia traffic carried in mobile networks. The proposed scheme combines the admission cont... In this paper, a novel admission scheme is proposed which provides high degrees of quality of service (QoS) guarantees for multimedia traffic carried in mobile networks. The proposed scheme combines the admission control and bandwidth reservation to guarantee QoS requirements. It considers both local information and remote information to determine whether to accept or reject a connection. In order to embody the characteristics of the algorithms proposed in the article, two traditional algorithms of admission control are used for comparison. In the end of the paper the simulation analyses are given and the results show that the proposed algorithm can adjust the bandwidth according to the current status of networks and decrease the probability of connections forcibly dropped. The most important thing is that the algorithm is based on the multimedia communications and can guarantee the QoS of real time connections through decreasing the bandwidth of non real time connections. 展开更多
关键词 broadband mobile networks admission control quality of service guarantee
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Determination of Energy Interchanged on the Tie Lines- Some Practical Issues 被引量:1
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作者 Zeljko Modric Zoran Kovac Kresimir Fekete 《Journal of Energy and Power Engineering》 2014年第5期948-956,共9页
The quality of methods for determining energy transits on the tie lines (lines that connect two neighboring power system) can have significant impact on business activity of the TSOs (transmission system operators... The quality of methods for determining energy transits on the tie lines (lines that connect two neighboring power system) can have significant impact on business activity of the TSOs (transmission system operators). Existing law regulation is not enough precise regarding definition of methods for metering energy transits (energy interchanged between neighboring TSOs). This paper analyses disadvantages of method for line losses metering with electric meters and suggests introduction of the measured value corrections. 展开更多
关键词 Billing point metering set metering point metering error energy transit.
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The Impact of Automation in Service Industries" An Empirical Study
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作者 M. Eva Diz-Comesana Nuria Rodriguez-Lopez 《Chinese Business Review》 2014年第3期162-178,共17页
Academic research into service industries has explored the characteristics of interpersonal interactions between employees and customers, but there are few studies addressing the issues of consumer interaction with te... Academic research into service industries has explored the characteristics of interpersonal interactions between employees and customers, but there are few studies addressing the issues of consumer interaction with technology and its influence on the objectives and results of the operations subsystem. This study examines the elements of the service encounter, and the changes automation originates in them and their relationships. The paper also examines changes in the elements and results of the operations subsystem, as a result of automation. We propose that the customer's relationship with employees and/or technology and automated systems for the service impact the objectives and results of the operations subsystem, all of which could have an effect on the company's competitive position. The empirical study is focused on four industries, namely, toll motorways, car parks, carwash and video/DVD rental companies, in an attempt to identify objectives that lead companies to implement automated processes affecting the customer's relationship with the company. The hypotheses generated are contrasted with a structural equation modelling. The results confirm that the customer's relationship with employees and automated systems for the service impacts the objectives and results of the operations subsystem. Also, the results show how automation can enable firms simultaneously to achieve acceptable levels of flexibility and productivity, two dimensions that have traditionally been considered opposites. 展开更多
关键词 service encounter AUTOMATION technology operations subsystem objectives elements of service delivery COST time reduction FLEXIBILITY
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A Deadlock-Avoidance Dispatching Method for Multiple-Load AGVs Based Transportation System 被引量:2
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作者 XIAO Haining WU Xing +1 位作者 ZOU Ting ZHAI Jingjing 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2021年第1期181-192,共12页
In recent years,multiple-load automatic guided vehicle(AGV)is increasingly used in the logistics transportation fields,owing to the advantages of smaller fleet size and fewer occurrences of traffic congestion.However,... In recent years,multiple-load automatic guided vehicle(AGV)is increasingly used in the logistics transportation fields,owing to the advantages of smaller fleet size and fewer occurrences of traffic congestion.However,one main challenge lies in the deadlock-avoidance for the dispatching process of a multiple-load AGV system.To prevent the system from falling into a deadlock,a strategy of keeping the number of jobs in the system(NJIS)at a low level is adopted in most existing literatures.It is noteworthy that a low-level NJIS will make the processing machine easier to be starved,thereby reducing the system efficiency unavoidably.The motivation of the paper is to develop a deadlock-avoidance dispatching method for a multiple-load AGV system operating at a high NJIS level.Firstly,the deadlock-avoidance dispatching method is devised by incorporating a deadlock-avoidance strategy into a dispatching procedure that contains four sub-problems.In this strategy,critical tasks are recognized according to the status of workstation buffers,and then temporarily forbidden to avoid potential deadlocks.Secondly,three multiattribute dispatching rules are designed for system efficiency,where both the traveling distance and the buffer status are taken into account.Finally,a simulation system is developed to evaluate the performance of the proposed deadlock-avoidance strategy and dispatching rules at different NJIS levels.The experimental results demonstrate that our deadlock-avoidance dispatching method can improve the system efficiency at a high NJIS level and the adaptability to various system settings,while still avoiding potential deadlocks. 展开更多
关键词 automatic guided vehicle(AGV)dispatching deadlock avoidance multiple-load AGV system critical tasks multi-attribute rules
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Volunteer Activities in Time of Disaster in Japan's Highly Information-Oriented Society
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作者 Kayoko Yamamoto 《Journal of Earth Science and Engineering》 2013年第3期190-202,共13页
This study aims to clarify the characteristics of volunteer activities in times of disaster, while taking into account the influence of the orientation towards information intensity, which is an important feature of c... This study aims to clarify the characteristics of volunteer activities in times of disaster, while taking into account the influence of the orientation towards information intensity, which is an important feature of contemporary Japanese society, and focusing on the volunteer activities for recovery and reconstruction in the disaster-stricken areas of the Great East Japan Earthquake. In modern Japanese society, because volunteer activities are being conducted in a variety of forms, those who wish to volunteer can participate in volunteer activities that suit their own situation. Further, in a highly information-oriented society such as modern Japan, many kinds of information systems can be used to conduct a variety of volunteer activities. Also, know-how concerning the introduction and methods of volunteer activity and recruitment for participants in volunteer activities are introduced using various information media, and there are many volunteer activities to choose from. Therefore, it is possible that through the diversification of volunteer activities, many people become involved in volunteer activities on a long-term basis, using ways of doing so that are possible for themselves. 展开更多
关键词 Volunteer activity DISASTER highly information-oriented society information systems GIS (geographic information systems) Great East Japan Earthquake.
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Collegiate athletes'mental health services utilization:A systematic review of conceptualizations,operationalizations,facilitators,and barriers
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作者 Jennifer J.Moreland Kathryn A.Coxe Jingzhen Yang 《Journal of Sport and Health Science》 SCIE 2018年第1期58-69,共12页
Background: While mental health among collegiate athletes is receiving increased attention, research on factors surrounding collegiate athletes' decision to seek mental health services is limited. The goal of the ... Background: While mental health among collegiate athletes is receiving increased attention, research on factors surrounding collegiate athletes' decision to seek mental health services is limited. The goal of the present review was to analyze and synthesize the current literature concerning collegiate athletes' utilization of mental health services, including the facilitators of and barriers to use of these services.Methods: The analysis was guided and organized using a socio-ecological framework, which considered the unique context in which collegiate athletes study and perform. A total of 21 articles, published between 2005 and 2016, which concern U.S. collegiate athletes' mental health services utilization(MHSU) were selected and included for the final analysis. Conceptualizations and operationalizations of MHSU were compared and contrasted. Facilitators of and barriers to athletes MHSU were examined and summarized while appropriately considering the proximity of each factor(facilitator or barrier) to the athletes.Results: Results showed variations in conceptualizations and operationalizations of MHSU in the articles analyzed, which made interpretation and cross comparison difficult. Collegiate athletes are willing to utilize mental health services, but gender, perceived stigma, peer norms—for athletes and coaches—plus service availability impact their MHSU.Conclusion: Key stakeholders, administrators, and public health officials should partner to eliminate MHSU barriers, support facilitators, and generally empower collegiate athletes to actively manage their mental health. 展开更多
关键词 College athlete Mental health Mental health services NCAA PSYCHOLOGY Sport psychology Systematic review
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Lightweight SOA-Based Twin-Engine Architecture for Enterprise Systems in Fixed and Mobile Environments 被引量:1
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作者 Tongguang Zhang Shuai Zhao +3 位作者 Budan Wu Maurizio Farina Bo Cheng Junliang Chen 《China Communications》 SCIE CSCD 2016年第9期183-194,共12页
Mobile devices as a popular computing platform for enterprise systems have enabled certain tasks to be executed out of office.However,the work may be interrupted due to the server shutdown or network disconnection whe... Mobile devices as a popular computing platform for enterprise systems have enabled certain tasks to be executed out of office.However,the work may be interrupted due to the server shutdown or network disconnection when employees access traditional single-engine Business Process Management System.To overcome this defect,we present a lightweight twin-engine architecture based on Service Oriented Architecture(SOA).In this paper,we discuss in detail the design and implementation of the architecture,and present a trigger mechanism to activate engines according to the states of hybrid environments since it is critical for the two types of engines to cooperate closely in hybrid environments with fixed and mobile computing resources.The experimental results validate the usability of the architecture. 展开更多
关键词 TWIN-ENGINE SOA enterprise system mobile environment
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Development of the Interurban Service with the Use of Alternative Commercial Road Trains
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《Journal of Civil Engineering and Architecture》 2012年第1期12-25,共14页
The main task of this paper is to review the principal aspects in organization of interurban long haul service with the use of road trains on the basis of the "district" traffic system. The goal of the paper is to d... The main task of this paper is to review the principal aspects in organization of interurban long haul service with the use of road trains on the basis of the "district" traffic system. The goal of the paper is to determine the most effective methods of trucking operations in order to highlight the regularities that characterize these methods. The paper describes practicable methods of freight flow analysis, some factors and parameters concerning movement of motor-vehicle trains and original route schedules as well. Of special interest is the obtained algorithm of economically effective trucking operations of motor-vehicle trains on the route. 展开更多
关键词 Through system district system truck (hybrid) tractor detachable semi-trailer route section (district).
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Organizational dynamics of an information system: case study from the forestry sector
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作者 Rajiv Kumar Garg Jitendra Kumar Das Mohit Gera 《Journal of Forestry Research》 SCIE CAS CSCD 2007年第1期1-10,共10页
The Forest Department in the State of Uttar Pradesh, India developed Forest Management Information System (FMIS) for achieving organizational goals of improved financial and human resource management, improvement in t... The Forest Department in the State of Uttar Pradesh, India developed Forest Management Information System (FMIS) for achieving organizational goals of improved financial and human resource management, improvement in the management of forests and wildlife, and for achieving responsive administration. This paper, based on field research, presents an assessment of the dynamics of FMIS in organizational context for a better understanding of such systems in forestry organizations. The paper also investigates the success of FMIS in assisting decision makers in achieving organizational goals. Based on the knowledge developed during the course of the study, key learning elements have been highlighted for the benefit of the stakeholders in information systems in forest sector. 展开更多
关键词 Business process reengineering Culture change Human resource Information system Socio-economic profile Strategic management
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A platform for communicating construction material information between e-commerce systems
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作者 Stephen C W Kong 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2004年第5期541-547,共7页
E-commerce systems for construction material procurement are becoming increasingly important in Hong Kong. These E-commerce systems are non-interoperable and create problems for the buyers who use these systems to pur... E-commerce systems for construction material procurement are becoming increasingly important in Hong Kong. These E-commerce systems are non-interoperable and create problems for the buyers who use these systems to purchase construction materials. This paper presents the mobile agent-based approach and Web services-based approach for enabling interoperation of these systems in the E-Union environment. 展开更多
关键词 E-COMMERCE mobile agent Web services distributed computing construction material
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Approach to Enterprise Application Integration with Web Services
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作者 林春梅 金鑫 +1 位作者 何跃 陈家训 《Journal of Donghua University(English Edition)》 EI CAS 2004年第4期143-148,共6页
Enterprise Application Integration (EAI) would be linking diverse systems and applications across the enterprise to enable the enterprise IT systems to adapt to the dynamic business environment and automate any busine... Enterprise Application Integration (EAI) would be linking diverse systems and applications across the enterprise to enable the enterprise IT systems to adapt to the dynamic business environment and automate any business practices. Whereas, with traditional EAI solution, it is difficult to efficiently link the different proprietary applications and data sources, and difficult to enable the system to rapidly identify and respond to changes in the dynamic business environment. In order to solve these problems, this paper uses the Web Services technology for EAI. This paper discusses the traditional EAI technologies and the bottlenecks for applications integration, also elaborates the Web Services technology and the advantages suited for applications integration. Therefore, the model of EAI with Web Services (EAIWS) is proposed to efficiently implement the integration of diverse applications and systems within or between the enterprises. With EAIWS, this paper provides an example to show how the application system works. This paper also discusses the advantages of EAIWS. 展开更多
关键词 EAI Web Services Integration.
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A Survey Study of City Community Athletic Service Network in Jiangsu Province, China
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作者 Liu jun Changsheng 《International Journal of Technology Management》 2015年第7期147-150,共4页
Introduction: Community athletic network service system,one of sub-systems of social security and social service, is the inevitable direction of social development in China in the future. Therefore, the research that... Introduction: Community athletic network service system,one of sub-systems of social security and social service, is the inevitable direction of social development in China in the future. Therefore, the research that how to establish the system matching our National City Community Service Network is the urgent issue to be settled down for the construction of the city community athletic service network. The construction of the city community athletic service network in Jiangsu provides a good way for the citizens to promote the level and quality of their lives with the help of the sports. Methods: Based on the literal data method, this paper studies the present city community athletic service network and the main factors which affect the construction of athletic service network and related problems by the following methods i.e. questionnaire survey, interview and observable methods and mathematical statistics method etc. Results: 1 .The main factors which affect citizens who join sports include shortage of athletic stations,, narrowly publicizing science knowledge of keeping healthy, the bad athletic circumstances and shortage of professional instructions. 2. Construction of Jiangsu urban community fitness service network mainly include: physical activity guidance; create a personal exercise files; the body after exercise monitoring; exercise prescription; knowledge of health promotion; post-exercise nutrition deployment; rehabilitation medical. 3.Governments play a leading role in Jiangsu city community service network. Conclusion: Physical fitness of urban community service organization management network should be based on City Community Service Center as the main sports, fitness, form a District Sports Council, the Community Sports Association, the neighborhood offices co-ordination between the management system. Community Sports College should become an important support network of health services, power, give full play to advantages of college sports professionals to enhance the community service network all aspects of sports, fitness, the construction and management. 展开更多
关键词 COMMUNITY Spots and Fitness Network Service BUILDING
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Airport Passenger Personalized Service System in Era of Big Data
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作者 CHEN Jianjun ZHANG Xu 《International English Education Research》 2016年第6期20-22,共3页
With the continuous growth of civil aviation passenger traffic, airlines and airports must constantly improve the level of operation and management, in order to meet the high quality and the high level of passenger de... With the continuous growth of civil aviation passenger traffic, airlines and airports must constantly improve the level of operation and management, in order to meet the high quality and the high level of passenger demand for personalized service. This paper puts forward that the airport passenger personalized service system in the era of big data, which can achieve high precision indoor and outdoor positioning seamless switch through using the integration of GPS and Beacon technology. Personalized service client for mobile intelligent terminal was developed to provide more convenient, efficient, dynamic and personalized airport information service for airport passenger. 展开更多
关键词 Airport. Passenger Beacon. Personalized Service
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地下装载机主要零部件的最新发展 被引量:6
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作者 高梦熊 王 森 赵秉镇 《矿山机械》 北大核心 2002年第6期21-23,共3页
最近几年国内外地下装载机主要零部件出现了许多新品种、新结构、新材料和新技术,下面分别介绍之。
关键词 动务系统 柴油机 净化系统 系统 变速箱 液压系统 地下装载机 零部件
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Dynamic Simulation of Carbon Sequestration by Pinus sylvestris var. mongolica 被引量:2
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作者 裴厦 谢高地 +4 位作者 张昌顺 刘春兰 李士美 张彩霞 陈龙 《Journal of Resources and Ecology》 CSCD 2015年第1期37-43,共7页
Based on the functional process of carbon sequestration of forest, we categorize carbon sequestration in two parts: carbon capture and carbon storage. Here,Pinus sylvestris var.mongolica was used to simulate the dyna... Based on the functional process of carbon sequestration of forest, we categorize carbon sequestration in two parts: carbon capture and carbon storage. Here,Pinus sylvestris var.mongolica was used to simulate the dynamic changing process of carbon sequestration of forest in a century using tree growth formula and the cost of carbon capture and sequestration. We found that the total carbon captured and stored by 100-year-old P. sylvestris var.mongolica are both 966 kg C tree^-1. On the assumption that the current year is the planting year, the present total carbon sequestration value (capital value) of 100-year-old P. sylvesrtis var.mongolica is 54.78 USD tree^-1 at the discount rate of 3%, with the present total carbon capture value of 18.92 USD tree^-1 and carbon storage value of 35.86 USD tree^-1. The dynamic process of the annual value of carbon capture is ilustrated by an upside-down U shape curve, while that of carbon storage service folows an S shape curve. The combination of the dynamic processes of carbon capture value and carbon storage value represent the changing process of carbon sequestration value, which appears to be an S shape curve. 展开更多
关键词 ecosystem service carbon sequestration value dynamic changes Pinus sylvestris var.mongolica long time scale
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Numerical modeling of regional groundwater flow in the Heihe River Basin,China:Advances and new insights 被引量:9
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作者 YAO YingYing ZHENG ChunMiao +2 位作者 TIAN Yong LIU Jie ZHENG Yi 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第1期3-15,共13页
Numerical groundwater modeling is an effective tool to guide water resources management and explore complex groundwater-dependent ecosystems in arid regions.In the Heihe River Basin(HRB),China’s second largest inland... Numerical groundwater modeling is an effective tool to guide water resources management and explore complex groundwater-dependent ecosystems in arid regions.In the Heihe River Basin(HRB),China’s second largest inland river basin located in arid northwest China,a series of groundwater flow models have been developed for those purposes over the past 20 years.These models have elucidated the characteristics of groundwater flow systems and provided the scientific basis for a more sustainable management of groundwater resources and ecosystem services.The first part of this paper presents an overview of previous groundwater modeling studies and key lessons learned based on seven different groundwater models in the middle and lower HRB at sub-basin scales.The second part reviews the rationale for development of a regional basin-scale groundwater flow model that unifies previous sub-basin models.In addition,this paper discusses the opportunities and challenges in developing a regional groundwater flow model in an arid river basin such as the HRB. 展开更多
关键词 Heihe River Basin groundwater flow modeling regional hydrogeology sustainable groundwater management ecohy-drology
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Analyzing the service availability of mobile cloud computing systems by fluid-flow approximation 被引量:2
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作者 Hong-wu LV Jun-yu LIN Hui-qiang WANG Guang-sheng FENG Mo ZHOU 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2015年第7期553-567,共15页
Mobile cloud computing (MCC) has become a promising technique to deal with computation- or data-intensive tasks. It overcomes the limited processing power, poor storage capacity, and short battery life of mobile dev... Mobile cloud computing (MCC) has become a promising technique to deal with computation- or data-intensive tasks. It overcomes the limited processing power, poor storage capacity, and short battery life of mobile devices. Providing continuous and on-demand services, MCC argues that the service must be available for users at anytime and anywhere. However, at present, the service availability of MCC is usually measured by some certain metrics of a real-world system, and the results do not have broad representation since different systems have different load levels, different deployments, and many other random factors. Meanwhile, for large-scale and complex types of services in MCC systems, simulation-based methods (such as Monte- Carlo simulation) may be costly and the traditional state-based methods always suffer from the problem of state-space explosion. In this paper, to overcome these shortcomings, fluid-flow approximation, a breakthrough to avoid state-space explosion, is adopted to analyze the service availability of MCC. Four critical metrics, including response time of service, minimum sensing time of devices, minimum number of nodes chosen, and action throughput, are def'med to estimate the availability by solving a group of ordinary differential equations even before the MCC system is fully deployed. Experimental results show that our method costs less time in analyzing the service availability of MCC than the Markov- or simulation-based methods. 展开更多
关键词 Service availability Mobile cloud computing Fluid-flow approximation Ordinary differential equations
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Delimiting Ecological Space and Simulating Spatial-temporal Changes in Its Ecosystem Service Functions based on a Dynamic Perspective: A Case Study on Qionglai City of Sichuan Province, China 被引量:1
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作者 OU Dinghua WU Nengjun +6 位作者 LI Yuanxi MA Qing ZHENG Siyuan LI Shiqi YU Dongrui TANG Haolun GAO Xuesong 《Journal of Resources and Ecology》 CSCD 2022年第6期1128-1142,共15页
Delimiting ecological space scientifically and making reasonable predictions of the spatial-temporal trend of changes in the dominant ecosystem service functions(ESFs) are the basis of constructing an ecological prote... Delimiting ecological space scientifically and making reasonable predictions of the spatial-temporal trend of changes in the dominant ecosystem service functions(ESFs) are the basis of constructing an ecological protection pattern of territorial space, which has important theoretical significance and application value. At present, most research on the identification, functional partitioning and pattern reconstruction of ecological space refers to the current ESFs and their structural information, which ignores the spatial-temporal dynamic nature of the comprehensive and dominant ESFs, and does not seriously consider the change simulation in the dominant ESFs of the future ecological space. This affects the rationality of constructing an ecological space protection pattern to some extent. In this study, we propose an ecological space delimitation method based on the dynamic change characteristics of the ESFs, realize the identification of the ecological space range in Qionglai City and solve the problem of ignoring the spatial-temporal changes of ESFs in current research. On this basis, we also apply the Markov-CA model to integrate the spatial-temporal change characteristics of the dominant ESFs, successfully realize the simulation of the spatial-temporal changes in the dominant ESFs in Qionglai City’s ecological space in 2025, find a suitable method for simulating ecological spatial-temporal changes and also provide a basis for constructing a reasonable ecological space protection pattern. This study finds that the comprehensive quantity of ESF and its annual rate of change in Qionglai City show obvious dynamics, which confirms the necessity of considering the dynamic characteristics of ESFs when identifying ecological space. The areas of ecological space in Qionglai city represent 98307 ha by using the ecological space identification method proposed in this study, which is consistent with the ecological spatial distribution in the local ecological civilization construction plan. This confirms the reliability of the ecological space identification method based on the dynamic characteristics of the ESFs. The results also show that the dominant ESFs in Qionglai City represented strong non-stationary characteristics during 2003–2019,which showed that we should fully consider the influence of the dynamics in the dominant ESFs on the future ESF pattern during the process of constructing the ecological spatial protection pattern. The Markov-CA model realized the simulation of spatial-temporal changes in the dominant ESFs with a high precision Kappa coefficient of above 0.95, which illustrated the feasibility of using this model to simulate the future dominant ESF spatial pattern. The simulation results showed that the dominant ESFs in Qionglai will still undergo mutual conversions during 2019–2025 due to the effect of the their non-stationary nature. The ecological space will still maintain the three dominant ESFs of primary product production, climate regulation and hydrological regulation in 2025, but their areas will change to 32793 ha, 52490 ha and 13024 ha, respectively. This study can serve as a scientific reference for the delimitation of the ecological conservation redline, ecological function regionalization and the construction of an ecological spatial protection pattern. 展开更多
关键词 ecological space dominant ecosystem service functions(ESFs) dynamicity spatial-temporal change simulation Markov-CA model
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Identification of Key Ecosystem Services That Can Be Delivered by Water or Wind from Zhangjiakou-Chengde Region to Beijing 被引量:1
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作者 LI Qingxu ZHANG Biao +1 位作者 XIE Gaodi WANG Shuang 《Journal of Resources and Ecology》 CSCD 2018年第6期632-641,共10页
Rapid urbanization causing serious air pollution and ecological risks in the Beijing–Tianjin–Hebei region in North China has attracted worldwide attention. This study estimates the key ecosystem services of land cov... Rapid urbanization causing serious air pollution and ecological risks in the Beijing–Tianjin–Hebei region in North China has attracted worldwide attention. This study estimates the key ecosystem services of land covers in Zhangjiakou and Chengde, and analyzes their main contributions and the effects of ecosystem service flows to Beijing. Results indicated that the total economic value of key ecosystem services in the Zhangjiakou–Chengde region was CNY 189.5 billion in 2013, and that these services were generated mainly from the forestlands, grasslands, and farmlands of Chengde and the eastern region of Zhangjiakou. However, nearly half of land covers provided low ecosystem service values and thus should be enhanced. In addition, approximately 21% of key ecosystem services were delivered from the Zhangjiakou–Chengde region into Beijing, and the flow feasibilities of ecosystem services delivered by water and wind reached 34% and 12%, respectively. Chicheng, Zhuolu, Chongli, Huailai, Xuanhua and Guyuan counties contributed 61% of the ecosystem services flowing into Beijing, and each service showed high regional relationships with Beijing(flow index ≥ 40%). Thus, these services should be prioritized in terms of ecological compensation funds and policies from Beijing. 展开更多
关键词 key ecosystem service supply and flow land cover Beijing-Tianjin-Hebei region Zhangjiakou-Chengde region
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Weight control in design of space nuclear reactor system 被引量:1
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作者 WANG SanBing HE ChaoHui 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第10期2594-2598,共5页
Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system (SNR... Space nuclear power system is the key technology for deep space exploration missions in the future, especially for space base building-up. This paper evaluates several typical latest space nuclear reactor system (SNRS) designs, and finds that most of their weights are heavier than necessary. From the point of weight-control, the SA4 design is the best but its design is more complex than others. A newly designed SNRS, based on the SAFE400 model, uses annular fuel and has better performance, with a fuel mass lower than that of the SAFE400 prototype by 18.75%. Meanwhile, different from former opinions, the delay neutron fractions of SNRS are not constant and change with the different SNRS designs. Therefore, designs of SNRS not to count the delayed neutron fracture or directly to consider it as 0.00677 are not appropriate. 展开更多
关键词 RTG SNRs power density SAFE400 MCNPX
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