Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and...Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper.展开更多
In order to improve the efficiency of operating rooms,reduce the costs for hospitals and improve the level of service qualities, a scheduling method was developed based on an estimation of distribution algorithm（ EDA...In order to improve the efficiency of operating rooms,reduce the costs for hospitals and improve the level of service qualities, a scheduling method was developed based on an estimation of distribution algorithm（ EDA）. First, a scheduling problem domain is described. Based on assignment constraints and resource capacity constraints, the mathematical programming models are set up with an objective function to minimize the system makespan. On the basis of the descriptions mentioned above, a solution policy of generating feasible scheduling solutions is established. Combined with the specific constraints of operating theatres, the EDA-based algorithm is put forward to solve scheduling problems. Finally, simulation experiments are designed to evaluate the scheduling method. The orthogonal table is chosen to determine the parameters in the proposed method. Then the genetic algorithm and the particle swarm optimization algorithm are chosen for comparison with the EDA-based algorithm, and the results indicate that the proposed method can decrease the makespan of the surgical system regardless of the size of operations. Moreover, the computation time of the EDA-based algorithm is only approximately 5 s when solving the large scale problems, which means that the proposed algorithm is suitable for carrying out an on-line scheduling optimization of the patients.展开更多
Coupled thermo-mechanical model was used to investigate the effects of the pin diameter, the shoulder diameter and the in conical angle on the heat generations, the material deformations and the energy histories in fr...Coupled thermo-mechanical model was used to investigate the effects of the pin diameter, the shoulder diameter and the in conical angle on the heat generations, the material deformations and the energy histories in friction stir welding（FSW） of AA2024-T3 alloy. Results indicate that the shoulder-plate contact area takes more important contribution to the heat generation than the pin-plate contact area. The increase of the shoulder diameter or the decrease of the pin diameter can lead to the increase of the welding temperature in FSW, but the change of shoulder size is more important. Compared to the cases in FSW of AA6061-T6, the input power is obviously increased in FSW of AA2024-T3 and the ratio of the plastic dissipation to the friction dissipation becomes decreased.展开更多
Purpose: The primary aim of this study was to develop an assessment of the fundamental, combined, and complex movement skills required to support childhood physical literacy. The secondary aim was to establish the fea...Purpose: The primary aim of this study was to develop an assessment of the fundamental, combined, and complex movement skills required to support childhood physical literacy. The secondary aim was to establish the feasibility, objectivity, and reliability evidence for the assessment.Methods: An expert advisory group recommended a course format for the assessment that would require children to complete a series of dynamic movement skills. Criterion-referenced skill performance and completion time were the recommended forms of evaluation. Children, 8–12 years of age, self-reported their age and gender and then completed the study assessments while attending local schools or day camps. Face validity was previously established through a Delphi expert(n = 19, 21% female) review process. Convergent validity was evaluated by age and gender associations with assessment performance. Inter-and intra-rater(n = 53, 34% female) objectivity and test–retest(n = 60, 47% female) reliability were assessed through repeated test administration.Results: Median total score was 21 of 28 points(range 5–28). Median completion time was 17 s. Total scores were feasible for all 995 children who self-reported age and gender. Total score did not differ between inside and outside environments(95% confidence interval(CI) of difference:-0.7 to 0.6;p = 0.91) or with/without footwear(95%CI of difference:-2.5 to 1.9; p = 0.77). Older age(p < 0.001, η2= 0.15) and male gender(p < 0.001, η2= 0.02)were associated with a higher total score. Inter-rater objectivity evidence was excellent(intraclass correlation coefficient(ICC) = 0.99) for completion time and substantial for skill score(ICC = 0.69) for 104 attempts by 53 children(34% female). Intra-rater objectivity was moderate(ICC = 0.52) for skill score and excellent for completion time(ICC = 0.99). Reliability was excellent for completion time over a short(2–4 days; ICC = 0.84) or long(8–14days; ICC = 0.82) interval. Skill score reliability was moderate(ICC = 0.46) over a short interval, and substantial(ICC = 0.74) over a long interval.Conclusion: The Canadian Agility and Movement Skill Assessment is a feasible measure of selected fundamental, complex and combined movement skills, which are an important building block for childhood physical literacy. Moderate-to-excellent objectivity was demonstrated for children 8–12 years of age. Test–retest reliability has been established over an interval of at least 1 week. The time and skill scores can be accurately estimated by 1 trained examiner.展开更多
Patients with advanced hepatocellular carcinoma(HCC) showing portal vein tumor thrombosis(PVTT) have an extremely poor prognosis. According to treatment guidelines, the only option for HCC patients with PVTT is sorafe...Patients with advanced hepatocellular carcinoma(HCC) showing portal vein tumor thrombosis(PVTT) have an extremely poor prognosis. According to treatment guidelines, the only option for HCC patients with PVTT is sorafenib chemotherapy. However, in Asia, various treatments have been attempted and possible prolongation of overall survival has been repeatedly reported. We herein report the first case of a patient with an initially unresectable advanced HCC with PVTT who underwent curative hepatectomy after sorafenib and transcatheter arterial chemoembolization(TACE) showing complete histological response. Two months after induction with sorafenib, a significant decrease in serum alpha-fetoprotein level was observed and computed tomography imaging showed a significant decrease in tumor size. Because of remaining PVTT, TACE and curative resection were performed. The combination of sorafenib and TACE may be an effective treatment for HCC patients with PVTT.展开更多
The problem of simultaneous scheduling of machines and vehicles in flexible manufacturing system (FMS) was addressed.A spreadsheet based genetic algorithm (GA) approach was presented to solve the problem.A domain inde...The problem of simultaneous scheduling of machines and vehicles in flexible manufacturing system (FMS) was addressed.A spreadsheet based genetic algorithm (GA) approach was presented to solve the problem.A domain independent general purpose GA was used,which was an add-in to the spreadsheet software.An adaptation of the propritary GA software was demonstrated to the problem of minimizing the total completion time or makespan for simultaneous scheduling of machines and vehicles in flexible manufacturing systems.Computational results are presented for a benchmark with 82 test problems,which have been constructed by other researchers.The achieved results are comparable to the previous approaches.The proposed approach can be also applied to other problems or objective functions without changing the GA routine or the spreadsheet model.展开更多
The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficie...The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficiency and surface.Based on theoretical and experimental research,the law of material removal was explored and a new process variable based material removal model(PVMR)was proposed.The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z(y i)where the magnetorheological finishing process parameters are considered since they are easy to control and adjust.So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing.展开更多
This paper presents a novel approach to structure determination of linear systems along with the choice of system orders and parameters. AutoRegressive （AR）, Moving Average （MA） or AutoRegressive-Moving Average （...This paper presents a novel approach to structure determination of linear systems along with the choice of system orders and parameters. AutoRegressive （AR）, Moving Average （MA） or AutoRegressive-Moving Average （ARMA） model structure can be extracted blindly from the Third Order Cumulants （TOC） of the system output ts, where the unknown system is driven by an unobservable stationary independent identically distributed （i.i.d.） non-Gaussian signal. By means of the system order recursion, whether the system has an AR structure or has AR part of an ARMA structure is firstly investigated. MA features in the TOC domain is then applied as a threshold to decide if the system is an MA model or has MA part of an ARMA model. Numerical simulations illustrate the generality of the proposed blind structure identification methodology that may serve as a guideline for blind, linear system modeling.展开更多
文摘Pooling,unpooling/specialization,and discretionary task completion are typical operational strategies in queueing systems that arise in healthcare,call centers,and online sales.These strategies may have advantages and disadvantages in different operational environments.This paper uses the M/M/1 and M/M/2 queues to study the impact of pooling,specialization,and discretionary task completion on the average queue length.Closed-form solutions for the average M/M/2 queue length are derived.Computational examples illustrate how the average queue length changes with the strength of pooling,specialization,and discretionary task completion.Finally,several conjectures are made in the paper.
基金The National Natural Science Foundation of China(No.61273035,71471135)
文摘In order to improve the efficiency of operating rooms,reduce the costs for hospitals and improve the level of service qualities, a scheduling method was developed based on an estimation of distribution algorithm（ EDA）. First, a scheduling problem domain is described. Based on assignment constraints and resource capacity constraints, the mathematical programming models are set up with an objective function to minimize the system makespan. On the basis of the descriptions mentioned above, a solution policy of generating feasible scheduling solutions is established. Combined with the specific constraints of operating theatres, the EDA-based algorithm is put forward to solve scheduling problems. Finally, simulation experiments are designed to evaluate the scheduling method. The orthogonal table is chosen to determine the parameters in the proposed method. Then the genetic algorithm and the particle swarm optimization algorithm are chosen for comparison with the EDA-based algorithm, and the results indicate that the proposed method can decrease the makespan of the surgical system regardless of the size of operations. Moreover, the computation time of the EDA-based algorithm is only approximately 5 s when solving the large scale problems, which means that the proposed algorithm is suitable for carrying out an on-line scheduling optimization of the patients.
基金Project(NCET-12-0075)supported by the Program for New Century Excellent Talents in University,ChinaProject supported by the Fundamental Research Funds for the Central Universities,China+2 种基金Projects(11172057,11232003)supported by the National Natural Science Foundation of ChinaProject(2011CB013401)supported by the National Basic Research Program of ChinaProject(2012AA050901)supported by the National High-Tech Research and Development Program of China
文摘Coupled thermo-mechanical model was used to investigate the effects of the pin diameter, the shoulder diameter and the in conical angle on the heat generations, the material deformations and the energy histories in friction stir welding（FSW） of AA2024-T3 alloy. Results indicate that the shoulder-plate contact area takes more important contribution to the heat generation than the pin-plate contact area. The increase of the shoulder diameter or the decrease of the pin diameter can lead to the increase of the welding temperature in FSW, but the change of shoulder size is more important. Compared to the cases in FSW of AA6061-T6, the input power is obviously increased in FSW of AA2024-T3 and the ratio of the plastic dissipation to the friction dissipation becomes decreased.
基金funded by a grant from the Canadian Institutes of Health Research awarded to Dr. Meghann Lloyd and Dr. Mark Tremblay (IHD 94356)
文摘Purpose: The primary aim of this study was to develop an assessment of the fundamental, combined, and complex movement skills required to support childhood physical literacy. The secondary aim was to establish the feasibility, objectivity, and reliability evidence for the assessment.Methods: An expert advisory group recommended a course format for the assessment that would require children to complete a series of dynamic movement skills. Criterion-referenced skill performance and completion time were the recommended forms of evaluation. Children, 8–12 years of age, self-reported their age and gender and then completed the study assessments while attending local schools or day camps. Face validity was previously established through a Delphi expert(n = 19, 21% female) review process. Convergent validity was evaluated by age and gender associations with assessment performance. Inter-and intra-rater(n = 53, 34% female) objectivity and test–retest(n = 60, 47% female) reliability were assessed through repeated test administration.Results: Median total score was 21 of 28 points(range 5–28). Median completion time was 17 s. Total scores were feasible for all 995 children who self-reported age and gender. Total score did not differ between inside and outside environments(95% confidence interval(CI) of difference:-0.7 to 0.6;p = 0.91) or with/without footwear(95%CI of difference:-2.5 to 1.9; p = 0.77). Older age(p < 0.001, η2= 0.15) and male gender(p < 0.001, η2= 0.02)were associated with a higher total score. Inter-rater objectivity evidence was excellent(intraclass correlation coefficient(ICC) = 0.99) for completion time and substantial for skill score(ICC = 0.69) for 104 attempts by 53 children(34% female). Intra-rater objectivity was moderate(ICC = 0.52) for skill score and excellent for completion time(ICC = 0.99). Reliability was excellent for completion time over a short(2–4 days; ICC = 0.84) or long(8–14days; ICC = 0.82) interval. Skill score reliability was moderate(ICC = 0.46) over a short interval, and substantial(ICC = 0.74) over a long interval.Conclusion: The Canadian Agility and Movement Skill Assessment is a feasible measure of selected fundamental, complex and combined movement skills, which are an important building block for childhood physical literacy. Moderate-to-excellent objectivity was demonstrated for children 8–12 years of age. Test–retest reliability has been established over an interval of at least 1 week. The time and skill scores can be accurately estimated by 1 trained examiner.
文摘Patients with advanced hepatocellular carcinoma(HCC) showing portal vein tumor thrombosis(PVTT) have an extremely poor prognosis. According to treatment guidelines, the only option for HCC patients with PVTT is sorafenib chemotherapy. However, in Asia, various treatments have been attempted and possible prolongation of overall survival has been repeatedly reported. We herein report the first case of a patient with an initially unresectable advanced HCC with PVTT who underwent curative hepatectomy after sorafenib and transcatheter arterial chemoembolization(TACE) showing complete histological response. Two months after induction with sorafenib, a significant decrease in serum alpha-fetoprotein level was observed and computed tomography imaging showed a significant decrease in tumor size. Because of remaining PVTT, TACE and curative resection were performed. The combination of sorafenib and TACE may be an effective treatment for HCC patients with PVTT.
文摘The problem of simultaneous scheduling of machines and vehicles in flexible manufacturing system (FMS) was addressed.A spreadsheet based genetic algorithm (GA) approach was presented to solve the problem.A domain independent general purpose GA was used,which was an add-in to the spreadsheet software.An adaptation of the propritary GA software was demonstrated to the problem of minimizing the total completion time or makespan for simultaneous scheduling of machines and vehicles in flexible manufacturing systems.Computational results are presented for a benchmark with 82 test problems,which have been constructed by other researchers.The achieved results are comparable to the previous approaches.The proposed approach can be also applied to other problems or objective functions without changing the GA routine or the spreadsheet model.
基金National Science and Technology Major Project,China(No.2009ZX04001-101)National Program on Key Basic Research Project(973Program)(No.2009CB724400)Shanghai Leading Academic Discipline Project,China(No.B602)
文摘The controllable key factors in magnetorheological finishing device were studied to determine their influence on efficiency of magnetorheological finishing(MRF)and surface of MRF,as well as interaction between efficiency and surface.Based on theoretical and experimental research,the law of material removal was explored and a new process variable based material removal model(PVMR)was proposed.The experimental findings demonstrate that PVMR reveals the law of the material removal with introduction of three concepts and makes a material removal function z(y i)where the magnetorheological finishing process parameters are considered since they are easy to control and adjust.So the material function of this model is quadratic curve function which is readily suitable for stability and online control magnetorheological finishing.
基金Supported by the National Natural Science Foundation of China (No.60575006).
文摘This paper presents a novel approach to structure determination of linear systems along with the choice of system orders and parameters. AutoRegressive （AR）, Moving Average （MA） or AutoRegressive-Moving Average （ARMA） model structure can be extracted blindly from the Third Order Cumulants （TOC） of the system output ts, where the unknown system is driven by an unobservable stationary independent identically distributed （i.i.d.） non-Gaussian signal. By means of the system order recursion, whether the system has an AR structure or has AR part of an ARMA structure is firstly investigated. MA features in the TOC domain is then applied as a threshold to decide if the system is an MA model or has MA part of an ARMA model. Numerical simulations illustrate the generality of the proposed blind structure identification methodology that may serve as a guideline for blind, linear system modeling.
