As a new variant of vehicle routing problem( VRP),a finished vehicle routing problem with time windows in finished vehicle logistics( FVRPTW) is modeled and solved. An optimization model for FVRPTW is presented with t...As a new variant of vehicle routing problem( VRP),a finished vehicle routing problem with time windows in finished vehicle logistics( FVRPTW) is modeled and solved. An optimization model for FVRPTW is presented with the objective of scheduling multiple transport routes considering loading constraints along with time penalty function to minimize the total cost. Then a genetic algorithm( GA) is developed. The specific encoding and genetic operators for FVRPTW are devised.Especially,in order to accelerate its convergence,an improved termination condition is given. Finally,a case study is used to evaluate the effectiveness of the proposed algorithm and a series of experiments are conducted over a set of finished vehicle routing problems. The results demonstrate that the proposed approach has superior performance and satisfies users in practice. Contributions of the study are the modeling and solving of a complex FVRPTW in logistics industry.展开更多
With the challenge of great growing of transport diversity for the automobile enterprises, the heterogeneous vehicle routing problem with multiple depots, multiple types of finished vehicles and multiple types of tran...With the challenge of great growing of transport diversity for the automobile enterprises, the heterogeneous vehicle routing problem with multiple depots, multiple types of finished vehicles and multiple types of transport vehicles in finished vehicle logistics(HVRPMD) is modelled and solved. A multi-objective optimization model for HVRPMD is presented considering loading constraints to minimize the total cost and minimize the number of transport vehicles. Then a hybrid heuristic algorithm based on genetic algorithm and particle swarm optimization(GA-PSO) is developed. Moreover, a case study is used to evaluate the effectiveness of this algorithm. By comparing the GA-PSO algorithm with the traditional GA algorithm, the simulation results demonstrate the proposed GA-PSO algorithm is able to better support the HVRPMD problem in practice. Contributions of the paper are the modelling and solving of a complex HVRPMD in logistics industry.展开更多
We sought to estimate the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden (FVL) mutation without a personal history of thromboembolism, and to evaluate the impact of maternal...We sought to estimate the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden (FVL) mutation without a personal history of thromboembolism, and to evaluate the impact of maternal and fetal FVL mutation carriage or other thrombophilias on the risk of adverse outcomes. Methods: Women with a singleton pregnancy and no history of thromboembolism were recruited at 13 clinical centers before 14 weeks of gestation from April 2000 to August 2001. Each was tested for the FVL mutation, as was the resultant conceptus after delivery or after miscarriage, when available. The incidence of thromboembolism (primary outcome), and of other adverse outcomes, was compared between FVL mutation carriers and noncarriers. We also compared adverse outcomes in a secondary nested carrier-control analysis of FVL mutation and other coagulation abnormalities. In this secondary analysis, we defined carriers as women having one or more of the following traits: carrier for FVL mutation, protein C deficiency, protein S deficiency, antithrombin Hl deficiency, activated protein C resistance, or lupus anticoagulant-positive, heterozygous for prothrombin G20210A or homozygous for the 5,10 methylenetetrahydrofolate reductase mutations. Carriers of the FVL mutation alone (with or without activated protein C resistance) were compared with those having one or more other coagulation abnormalities and with controls with no coagulation abnormality. Results: One hundred thirty-four FVL mutation carriers were identified among 4,885 graviclas (2.7% ), with both FVL mutation status and pregnancy outcomes available. No thromboembolic events occurred among the FVL mutation carriers (0% , 95% confidence interval 0- 2.7% ). Three pulmonary emboli and one deep venous thrombosis occurred (0.08% , 95% , confidence interval 0.02- 0.21% ), all occurring in FVL mutation noncarriers. In the nested carrier-control analysis (n = 339), no differences in adverse pregnancy outcomes were observed between FVL mutation carriers, carriers of other coagulation disorders, and controls. Maternal FVL mutation carriage was not associated with increased pregnancy loss, preeclampsia, placental abruption, or small for gestational age births. However, fetal FVL mutation carriage was associated with more frequent preeclampsia among African-American (15.0% ) and Hispanic (12.5% ) women than white women (2.6% , P=.04), adjusted odds ratio 2.4 (95% confidence interval 1.0- 5.2, P = .05). Conclusion: Among women with no history of thromboembolism, maternal heterozygous carriage of the FVL mutation is associated with a low risk of venous thromboembolism in pregnancy. Neither universal screening for the FVL mutation, nor treatment of low-risk carriers during pregnancy is indicated.展开更多
基金Supported by the National Natural Science Foundation of China(No.51565036)
文摘As a new variant of vehicle routing problem( VRP),a finished vehicle routing problem with time windows in finished vehicle logistics( FVRPTW) is modeled and solved. An optimization model for FVRPTW is presented with the objective of scheduling multiple transport routes considering loading constraints along with time penalty function to minimize the total cost. Then a genetic algorithm( GA) is developed. The specific encoding and genetic operators for FVRPTW are devised.Especially,in order to accelerate its convergence,an improved termination condition is given. Finally,a case study is used to evaluate the effectiveness of the proposed algorithm and a series of experiments are conducted over a set of finished vehicle routing problems. The results demonstrate that the proposed approach has superior performance and satisfies users in practice. Contributions of the study are the modeling and solving of a complex FVRPTW in logistics industry.
基金Supported by the National Natural Science Foundation of China(No.51565036)。
文摘With the challenge of great growing of transport diversity for the automobile enterprises, the heterogeneous vehicle routing problem with multiple depots, multiple types of finished vehicles and multiple types of transport vehicles in finished vehicle logistics(HVRPMD) is modelled and solved. A multi-objective optimization model for HVRPMD is presented considering loading constraints to minimize the total cost and minimize the number of transport vehicles. Then a hybrid heuristic algorithm based on genetic algorithm and particle swarm optimization(GA-PSO) is developed. Moreover, a case study is used to evaluate the effectiveness of this algorithm. By comparing the GA-PSO algorithm with the traditional GA algorithm, the simulation results demonstrate the proposed GA-PSO algorithm is able to better support the HVRPMD problem in practice. Contributions of the paper are the modelling and solving of a complex HVRPMD in logistics industry.
文摘We sought to estimate the frequency of pregnancy-related thromboembolic events among carriers of the factor V Leiden (FVL) mutation without a personal history of thromboembolism, and to evaluate the impact of maternal and fetal FVL mutation carriage or other thrombophilias on the risk of adverse outcomes. Methods: Women with a singleton pregnancy and no history of thromboembolism were recruited at 13 clinical centers before 14 weeks of gestation from April 2000 to August 2001. Each was tested for the FVL mutation, as was the resultant conceptus after delivery or after miscarriage, when available. The incidence of thromboembolism (primary outcome), and of other adverse outcomes, was compared between FVL mutation carriers and noncarriers. We also compared adverse outcomes in a secondary nested carrier-control analysis of FVL mutation and other coagulation abnormalities. In this secondary analysis, we defined carriers as women having one or more of the following traits: carrier for FVL mutation, protein C deficiency, protein S deficiency, antithrombin Hl deficiency, activated protein C resistance, or lupus anticoagulant-positive, heterozygous for prothrombin G20210A or homozygous for the 5,10 methylenetetrahydrofolate reductase mutations. Carriers of the FVL mutation alone (with or without activated protein C resistance) were compared with those having one or more other coagulation abnormalities and with controls with no coagulation abnormality. Results: One hundred thirty-four FVL mutation carriers were identified among 4,885 graviclas (2.7% ), with both FVL mutation status and pregnancy outcomes available. No thromboembolic events occurred among the FVL mutation carriers (0% , 95% confidence interval 0- 2.7% ). Three pulmonary emboli and one deep venous thrombosis occurred (0.08% , 95% , confidence interval 0.02- 0.21% ), all occurring in FVL mutation noncarriers. In the nested carrier-control analysis (n = 339), no differences in adverse pregnancy outcomes were observed between FVL mutation carriers, carriers of other coagulation disorders, and controls. Maternal FVL mutation carriage was not associated with increased pregnancy loss, preeclampsia, placental abruption, or small for gestational age births. However, fetal FVL mutation carriage was associated with more frequent preeclampsia among African-American (15.0% ) and Hispanic (12.5% ) women than white women (2.6% , P=.04), adjusted odds ratio 2.4 (95% confidence interval 1.0- 5.2, P = .05). Conclusion: Among women with no history of thromboembolism, maternal heterozygous carriage of the FVL mutation is associated with a low risk of venous thromboembolism in pregnancy. Neither universal screening for the FVL mutation, nor treatment of low-risk carriers during pregnancy is indicated.
