To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated ...To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.展开更多
Objective: To investigate patients' perception of service quality at hospitals in nine Chinese cities and propose some measures for improvement. Methods: The ServQ ual scale method was used in a survey involving p...Objective: To investigate patients' perception of service quality at hospitals in nine Chinese cities and propose some measures for improvement. Methods: The ServQ ual scale method was used in a survey involving patients at out-patient and in-patient facilities in Shanghai, Chongqing, Chengdu, Nanning, Guilin and Laibin of Guangxi, Honghezhou of Yunnan, Wulumuqi of Xinjiang and Zhongshan of Guangdong. The data collected were entered and analyzed using SPSS 20.0. Statistical analyses included descriptive statistics, factor analyses, reliability analyses, product-moment correlations, independent-sample t-tests, One-way ANOVA and regression analyses. Results: The Kaiser-Meyer-Olkin value for the factor analysis of the scale was 0.979. The Cronbach's α for the reliability analysis was 0.978. All the Pearson correlation coei cients were positive and statistically signii cant. Visitors to out-patient facilities reported more positive perception tacilities on tangibles(t = 4.168, P(t = 1.979, P <han visitors to in-patient f 0.05). Patients of 60 years of age and above reported mor< 0.001) and reliability e positive perception th<an those between 40 and 49 on reliability(F = 3.311, P = 0.010), assurances(F = 2.751, P 0.05) and empathy(F = 4.009, P = 0.003). For the i ve dimensions of the scale, patients in Laibin, Guangxi reported the most positive perceived service quality, followed by patients in Shanghai. On the other hand, patients in Chongqing and Nanning and Guilin of Guangxi reported relatively poor perceptions of service quality. Standardized regression coei cients showed statistically significant(P < 0.001) positive values for all Serv Qual dimensions. Empathy(β = 0.267) and reliability(β uality. = 0.239) most strongly predicted perception of service qConclusions: Chinese patients perceived service quality as satisfactory. Hospitals in various regions of China should enhance their awareness and ability to serve their patients.展开更多
With rapid advancement of Cloud computing and networking technologies, a wide spectrum of Cloud services have been developed by various providers and utilized by numerous organizations as indispensable ingredients of ...With rapid advancement of Cloud computing and networking technologies, a wide spectrum of Cloud services have been developed by various providers and utilized by numerous organizations as indispensable ingredients of their information systems. Cloud service performance has a significant impact on performance of the future information infrastructure. Thorough evaluation on Cloud service performance is crucial and beneficial to both service providers and consumers; thus forming an active research area. Some key technologies for Cloud computing, such as virtualization and the Service-Oriented Architecture （SOA）, bring in special challenges to service performance evaluation. A tremendous amount of effort has been put by the research community to address these challenges and exciting progress has been made. Among the work on Cloud performance analysis, evaluation approaches developed with a system modeling perspective play an important role. However, related works have been reported in different sections of the literature; thus lacking a big picture that shows the latest status of this area. The objectives of this article is to present a survey that reflects the state of the art of Cloud service performance evaluation from the system modeling perspective. This articles also examines open issues and challenges to the surveyed evaluation approaches and identifies possible opportunities for future research in this important field.展开更多
Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward o...Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward operation, have not been able to approach the limit of the max-flow min-cut throughput wherein sources transmitting information over bottleneck links have to compete for access to these links. With Network Coding, multiple sources are now able to transmit packets over bottleneck links simultaneously, achieving the max-flow min-cut through-put and increasing network capacity. While the majority of the contemporary literature has focused on the performance of Network Coding from a capacity perspective, the aim of this research has taken a new direction focusing on two Quality of Service metrics, e.g., Packet Delivery Ratio (PDR) and Latency, in conjunction with Network Coding protocols in Mobile Ad Hoc Networks (MANETs). Simulations are performed on static and mobile environments to determine a Quality of Service baseline comparison between Network Coding protocols and traditional ad hoc routing protocols. The results show that the Random Linear Network Coding protocol has the lowest Latency and Dynamic Source Routing protocol has the highest PDR in the static scenarios, and show that the Random Linear Network Coding protocol has the best cumulative performance for both PDR and Latency in the mobile scenarios.展开更多
基金The National Natural Science Foundation of China(No60673054,90412012)
文摘To achieve high quality of service （QoS） on computational grids, the QoS-aware job scheduling is investigated for a hierarchical decentralized grid architecture that consists of multilevel schedulers. An integrated QoS-aware job dispatching policy is proposed, which correlates priorities of incoming jobs used for job selecting at the local scheduler of the grid node with the job dispatching policies at the global scheduler for computational grids. The stochastic high-level Petri net （SHLPN） model of a two-level hierarchy computational grid architecture is presented, and a model refinement is made to reduce the complexity of the model solution. A performance analysis technique based on the SHLPN is proposed to investigate the QoS-aware job scheduling policy. Numerical results show that the QoS-aware job dispatching policy outperforms the QoS-unaware job dispatching policy in balancing the high-priority jobs, and thus enables priority-based QoS.
基金Supported by the 12th Five-Year Infectious Disease Research Project:the Use and Optimization of the Standard Regimen for Diagnosis and Treatment of Tuberculosis in HIV/AIDS Patients in China(No.2012ZX10001-003)the 12th Five-Year Major Science and Technology Project on Discovery of Major New Drugs:Construction of a Technology Platform for Clinical Evaluation of AntiHIV Drugs(No.2012ZX09303013)+2 种基金the National 863 Project"Study the Key Technology of Personnel Protection and Lab Tracking of pathogenic microorganism"(2014AA021403)the year 2014 Key research project of the party of the education and health of Shanghai(201420)Scientific research in hospital construction project of Chinese Medical Doctor Assoclation
文摘Objective: To investigate patients' perception of service quality at hospitals in nine Chinese cities and propose some measures for improvement. Methods: The ServQ ual scale method was used in a survey involving patients at out-patient and in-patient facilities in Shanghai, Chongqing, Chengdu, Nanning, Guilin and Laibin of Guangxi, Honghezhou of Yunnan, Wulumuqi of Xinjiang and Zhongshan of Guangdong. The data collected were entered and analyzed using SPSS 20.0. Statistical analyses included descriptive statistics, factor analyses, reliability analyses, product-moment correlations, independent-sample t-tests, One-way ANOVA and regression analyses. Results: The Kaiser-Meyer-Olkin value for the factor analysis of the scale was 0.979. The Cronbach's α for the reliability analysis was 0.978. All the Pearson correlation coei cients were positive and statistically signii cant. Visitors to out-patient facilities reported more positive perception tacilities on tangibles(t = 4.168, P(t = 1.979, P <han visitors to in-patient f 0.05). Patients of 60 years of age and above reported mor< 0.001) and reliability e positive perception th<an those between 40 and 49 on reliability(F = 3.311, P = 0.010), assurances(F = 2.751, P 0.05) and empathy(F = 4.009, P = 0.003). For the i ve dimensions of the scale, patients in Laibin, Guangxi reported the most positive perceived service quality, followed by patients in Shanghai. On the other hand, patients in Chongqing and Nanning and Guilin of Guangxi reported relatively poor perceptions of service quality. Standardized regression coei cients showed statistically significant(P < 0.001) positive values for all Serv Qual dimensions. Empathy(β = 0.267) and reliability(β uality. = 0.239) most strongly predicted perception of service qConclusions: Chinese patients perceived service quality as satisfactory. Hospitals in various regions of China should enhance their awareness and ability to serve their patients.
文摘With rapid advancement of Cloud computing and networking technologies, a wide spectrum of Cloud services have been developed by various providers and utilized by numerous organizations as indispensable ingredients of their information systems. Cloud service performance has a significant impact on performance of the future information infrastructure. Thorough evaluation on Cloud service performance is crucial and beneficial to both service providers and consumers; thus forming an active research area. Some key technologies for Cloud computing, such as virtualization and the Service-Oriented Architecture （SOA）, bring in special challenges to service performance evaluation. A tremendous amount of effort has been put by the research community to address these challenges and exciting progress has been made. Among the work on Cloud performance analysis, evaluation approaches developed with a system modeling perspective play an important role. However, related works have been reported in different sections of the literature; thus lacking a big picture that shows the latest status of this area. The objectives of this article is to present a survey that reflects the state of the art of Cloud service performance evaluation from the system modeling perspective. This articles also examines open issues and challenges to the surveyed evaluation approaches and identifies possible opportunities for future research in this important field.
文摘Network Coding is a relatively new forwarding paradigm where intermediate nodes perform a store, code, and forward operation on incoming packets. Traditional forwarding approaches, which employed a store and forward operation, have not been able to approach the limit of the max-flow min-cut throughput wherein sources transmitting information over bottleneck links have to compete for access to these links. With Network Coding, multiple sources are now able to transmit packets over bottleneck links simultaneously, achieving the max-flow min-cut through-put and increasing network capacity. While the majority of the contemporary literature has focused on the performance of Network Coding from a capacity perspective, the aim of this research has taken a new direction focusing on two Quality of Service metrics, e.g., Packet Delivery Ratio (PDR) and Latency, in conjunction with Network Coding protocols in Mobile Ad Hoc Networks (MANETs). Simulations are performed on static and mobile environments to determine a Quality of Service baseline comparison between Network Coding protocols and traditional ad hoc routing protocols. The results show that the Random Linear Network Coding protocol has the lowest Latency and Dynamic Source Routing protocol has the highest PDR in the static scenarios, and show that the Random Linear Network Coding protocol has the best cumulative performance for both PDR and Latency in the mobile scenarios.
