This paper presents a new hybrid approach that combines Modified Priority List (MPL) with Charged System Search (CSS), termed MPL-CSS, to solve one of the most crucial power system’s operational optimization problems...This paper presents a new hybrid approach that combines Modified Priority List (MPL) with Charged System Search (CSS), termed MPL-CSS, to solve one of the most crucial power system’s operational optimization problems, known as unit commitment (UC) scheduling. The UC scheduling problem is a mixed-integer nonlinear problem, highly-dimensional and extremely constrained. Existing meta-heuristic UC solution methods have the problems of stopping at a local optimum and slow convergence when applied to large-scale, heavily-constrained UC applications. In the first step of the proposed method, initial hourly optimum solutions of UC are obtained by Modified Priority List (MPL);however, the obtained UC solution may still be possible to be further improved. Therefore, in the second step, the CSS is utilized to achieve higher quality solutions. The UC is formulated as mixed integer linear programming to ensure the tractability of the results. The proposed method is successfully applied to a popular test system up to 100 units generators for both 24-hr and 168-hr system. Computational results show that both solution cost and execution time are superior to those of published methods.展开更多
Based on the concept of multiplicative fuzzy consistent complementary judgement matrix, the mixed least square method （MLSM） for priority of complementary judgement matrix is proposed and proved. Then, the correspon...Based on the concept of multiplicative fuzzy consistent complementary judgement matrix, the mixed least square method （MLSM） for priority of complementary judgement matrix is proposed and proved. Then, the corresponding convergent iterative algorithm is given and its convergence is proved. Finally, some main properties of the developed priority method, such as rank preservation under strong condition, etc., ate introduced. The theoretical analyses show that the MLSM can sufficiently reflect the preference information of the decision maker, and is easy to realize on a computer.展开更多
Objective: There is no single study that has examined nursing research priorities in Vietnam. This study aimed to gain consensus from experts on the nursing research priorities in Vietnam.Methods: A three-round modifi...Objective: There is no single study that has examined nursing research priorities in Vietnam. This study aimed to gain consensus from experts on the nursing research priorities in Vietnam.Methods: A three-round modified Delphi study was used in this study. A focus group discussion among experts was conducted in round I to identify the nursing research priorities(n=23). Data in round I were analyzed using content analysis. In round Ⅱ, participants were invited to rate the importance of each nursing priority topic in a 5-point Likert scale questionnaire, which had a 74%(n=17) response rate. In round Ⅲ, the questionnaire was returned to the experts(n=17) until consensus was reached. Data from round Ⅱ and round Ⅲ were analyzed to produce mean score and final rank.Results: The top 12 research priority lists were identified, which included subthemes and areas of possible investigations. All priorities were classified into three groups in the rank order, namely:(i) nursing management and leadership, which included(1) nursing care quality,(2) management and leadership of nurse managers,(3) nursing image,(4) professional nurse competency, and(5) human resource management;(ii) nursing education, which included(1) knowledge-specific domain,(2) the linkage between education and practice, and(3) nurse teacher workforce;and(iii) nursing service, which included(1) adult nursing concern,(2) patient safety,(3) public health nursing concern, and(4) quality of life of patients and nurses.Conclusions: Consensus among experts was achiever, and the findings are considered as the basis of resources to the most essential research needs in Vietnam.展开更多
Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11...Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11 standard series to enhance access medium supporting QoS for multimedia applications. However, some applications such as variable bit rate (VBR) traffic address some challenges in the hybrid coordination function (HCF) nominated to provide QoS. This paper presents a novel priority queuing model to analyze a medium access in the HCF controlled channel access (HCCA) mode. This model makes use of a MAP (Markovian Arrival Process)/PH (Phase Type)/1 queue with two types of jobs which are suitable to support VBR traffic. Using a MAP for traffic arrival process and PH distribution for service process, the inclusion of vacation period makes our analysis very general and comprehensive to support various types of practical traffic streams. The proposed priority queuing model is very useful to evaluate and enhance the performance of the scheduler and the admission controller in the HCCA mechanism.展开更多
文摘This paper presents a new hybrid approach that combines Modified Priority List (MPL) with Charged System Search (CSS), termed MPL-CSS, to solve one of the most crucial power system’s operational optimization problems, known as unit commitment (UC) scheduling. The UC scheduling problem is a mixed-integer nonlinear problem, highly-dimensional and extremely constrained. Existing meta-heuristic UC solution methods have the problems of stopping at a local optimum and slow convergence when applied to large-scale, heavily-constrained UC applications. In the first step of the proposed method, initial hourly optimum solutions of UC are obtained by Modified Priority List (MPL);however, the obtained UC solution may still be possible to be further improved. Therefore, in the second step, the CSS is utilized to achieve higher quality solutions. The UC is formulated as mixed integer linear programming to ensure the tractability of the results. The proposed method is successfully applied to a popular test system up to 100 units generators for both 24-hr and 168-hr system. Computational results show that both solution cost and execution time are superior to those of published methods.
基金The Project of Shaanxi Provincial Natural Science Foundation of China (No.2004A05)the Project of Science and Research Foundation of Education Committee of Shaanxi Province (No.06JK324)
文摘Based on the concept of multiplicative fuzzy consistent complementary judgement matrix, the mixed least square method （MLSM） for priority of complementary judgement matrix is proposed and proved. Then, the corresponding convergent iterative algorithm is given and its convergence is proved. Finally, some main properties of the developed priority method, such as rank preservation under strong condition, etc., ate introduced. The theoretical analyses show that the MLSM can sufficiently reflect the preference information of the decision maker, and is easy to realize on a computer.
基金supported by ASEAN Studies Center of Chulalongkorn University,Bangkok,Thailand.The project name is International Nursing Networking and Collaborative Research beyond AEC 2015(No.15410170300040)
文摘Objective: There is no single study that has examined nursing research priorities in Vietnam. This study aimed to gain consensus from experts on the nursing research priorities in Vietnam.Methods: A three-round modified Delphi study was used in this study. A focus group discussion among experts was conducted in round I to identify the nursing research priorities(n=23). Data in round I were analyzed using content analysis. In round Ⅱ, participants were invited to rate the importance of each nursing priority topic in a 5-point Likert scale questionnaire, which had a 74%(n=17) response rate. In round Ⅲ, the questionnaire was returned to the experts(n=17) until consensus was reached. Data from round Ⅱ and round Ⅲ were analyzed to produce mean score and final rank.Results: The top 12 research priority lists were identified, which included subthemes and areas of possible investigations. All priorities were classified into three groups in the rank order, namely:(i) nursing management and leadership, which included(1) nursing care quality,(2) management and leadership of nurse managers,(3) nursing image,(4) professional nurse competency, and(5) human resource management;(ii) nursing education, which included(1) knowledge-specific domain,(2) the linkage between education and practice, and(3) nurse teacher workforce;and(iii) nursing service, which included(1) adult nursing concern,(2) patient safety,(3) public health nursing concern, and(4) quality of life of patients and nurses.Conclusions: Consensus among experts was achiever, and the findings are considered as the basis of resources to the most essential research needs in Vietnam.
文摘Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11 standard series to enhance access medium supporting QoS for multimedia applications. However, some applications such as variable bit rate (VBR) traffic address some challenges in the hybrid coordination function (HCF) nominated to provide QoS. This paper presents a novel priority queuing model to analyze a medium access in the HCF controlled channel access (HCCA) mode. This model makes use of a MAP (Markovian Arrival Process)/PH (Phase Type)/1 queue with two types of jobs which are suitable to support VBR traffic. Using a MAP for traffic arrival process and PH distribution for service process, the inclusion of vacation period makes our analysis very general and comprehensive to support various types of practical traffic streams. The proposed priority queuing model is very useful to evaluate and enhance the performance of the scheduler and the admission controller in the HCCA mechanism.
