As low-cost and highly autonomous ocean observation platforms,underwater gliders encounter risks during their launch and recovery,especially when coordinating multi-glider deployments.This work focuses on cooperative ...As low-cost and highly autonomous ocean observation platforms,underwater gliders encounter risks during their launch and recovery,especially when coordinating multi-glider deployments.This work focuses on cooperative path planning of an underwater glider fleet with simultaneous launch and recovery to enhance the autonomy of sampling and reduce deployment risks.Specifically,the gliders collaborate to achieve sampling considering the specified routines of interest.The overall paths to be planned are divided into four rectangular parts with the same starting point,and each glider is assigned a local sampling route.A clipped-oriented line-of-sight algorithm is proposed to ensure the coverage of the desired edges.The pitch angle of the glider is selected as the optimizing parameter to coordinate the overall progress considering the susceptibility of gliders to currents and the randomness of paths produced by complex navigational strategies.Therefore,a multi-actuation deep-Q network algorithm is proposed to ensure simultaneous launch and recovery.Simulation results demonstrate the acceptable effectiveness of the proposed method.展开更多
China,when measured by gross tonnage,has surpassed Greece to become the world’s largest ship-owning country,according to data from Clarkson Research.The data shows that China’s ship-owning fleet has currently reache...China,when measured by gross tonnage,has surpassed Greece to become the world’s largest ship-owning country,according to data from Clarkson Research.The data shows that China’s ship-owning fleet has currently reached a total tonnage of 249.2 million GT,accounting for a market share of 15.9%(about USD 180 billion in fleet value),which is slightly higher than Greece’s 240.0 million GT and market share of 15.8%(about USD 163 billion in fleet value).Japan ranks third with a fleet of 181 million GT,followed by South Korea and the United States,both at around 66 million GT.展开更多
Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving...Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet. Scheduling and routing of maintenance fleet is a non-linear optimization problem with high complexity and a number of constraints. A heuristic algorithm, Ant Colony Optimization (ACO), was modified as Multi-ACO to be used to find the optimal scheduling and routing of maintenance fleet. The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases. The suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.展开更多
Forty-five years is nearly half a century, but merely a fleeting moment in the long course of history. This year marks the 45th anniversary of China-Malaysia diplomatic relations. Over the years, the two countries hav...Forty-five years is nearly half a century, but merely a fleeting moment in the long course of history. This year marks the 45th anniversary of China-Malaysia diplomatic relations. Over the years, the two countries have witnessed tremendous changes and remained good friends and good partners. To commemorate this heart-warming occasion of friendship, artists from the two countries have worked together on songs, films and other art works to present special gifts for the people of the two countries.展开更多
This article introduces a fleet composition algorithm for a fleet of intermediate carriers, which should deliver a swarm of miniature unmanned aerial vehicles （mini-UAVs） to a mission area. The algorithm is based on...This article introduces a fleet composition algorithm for a fleet of intermediate carriers, which should deliver a swarm of miniature unmanned aerial vehicles （mini-UAVs） to a mission area. The algorithm is based on the sequential solution of several knapsack problems with various constraints. The algorithm allows both to form an initial set of required types of intermediate carriers, and to generate a fleet of intermediate carriers. The formation of a fleet of intermediate carriers to solve a suppression of enemy air defense （SEAD） problem is presented to illustrate the proposed algorithm.展开更多
A 0-1 integer programming model for weekly fleet assignment was put forward based on linear network and weekly flight scheduling in China. In this model, the objective function is to maximize the total profit of fleet...A 0-1 integer programming model for weekly fleet assignment was put forward based on linear network and weekly flight scheduling in China. In this model, the objective function is to maximize the total profit of fleet assignment, subject to the constraints of coverage, aircraft flow balance, fleet size, aircraft availability, aircraft usage, flight restriction, aircraft seat capacity, and stopover. Then the branch-and-bound algorithm based on special ordered set was applied to solve the model. At last, a real- wofld case study on an airline with 5 fleets, 48 aircrafts and 1 786 flight legs indicated that the profit increase was ￥ 1 591276 one week and the running time was no more than 4 rain, which shows that the model and algorithm are fairly good for domestic airline.展开更多
The area of operations management has had a substantial effect on the today’s air transportation management.Having moved with huge demand from management to obtain a competitive advantage in the market,the airlines a...The area of operations management has had a substantial effect on the today’s air transportation management.Having moved with huge demand from management to obtain a competitive advantage in the market,the airlines are utilizing advanced optimization techniques to develop decision support systems for operations management and control.In order to provide a service with high quality and low cost,airlines spend a tremendous amount of resources and effort to generate profitable and cost-effective fare classes,flight schedules,fleet plans,aircraft routes,crew scheduling,gate assignment,etc.In this paper,the techniques and operations management applications that are used in the air transportation industry are reviewed including demand forecasting,fleet assignment,aircraft routing,crew scheduling,runway scheduling problem and gate assignment.展开更多
The main objective of the study was to examine the influence of vehicle fleet management practices on service delivery in State-Owned Enterprises (SOEs) in Zimbabwe. The study adopted a pragmatism research philosophy ...The main objective of the study was to examine the influence of vehicle fleet management practices on service delivery in State-Owned Enterprises (SOEs) in Zimbabwe. The study adopted a pragmatism research philosophy together with a mixed method research paradigm. In addition, structured questionnaires were distributed to 344 respondents drawn from 86 SOEs. Stratified and purposive sampling was used. Descriptive statistics were calculated using Statistical Package for the Social Science (SPSS) version 20. Exploratory factor analysis (EFA) was done on all items of the study while research hypotheses were tested using Structural Equation Modelling (SEM) in AMOS version 21. The study concluded that vehicle maintenance, fuel management, driver management and vehicle replacement positively influence service delivery. In addition, the study also established that Information and Communication Technologies (ICTs) moderate the influence of vehicle fleet management practices on service delivery. The study recommended that there is need for regular driver training and vehicle programs encompassing electronic spares tracking.展开更多
The study was designed to investigatecytogenotoxic effects of occupationalexposure to N,N’-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) for 11 workers(2 male,9 female) exposed to MATDA for 4-8 years,with the ave...The study was designed to investigatecytogenotoxic effects of occupationalexposure to N,N’-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) for 11 workers(2 male,9 female) exposed to MATDA for 4-8 years,with the average level of 0.展开更多
基金supported by the National Natural Science Foundation of China(No.51909252)the Fundamental Research Funds for the Central Universities(No.202061004)This work is also partly supported by the China Scholar Council.
文摘As low-cost and highly autonomous ocean observation platforms,underwater gliders encounter risks during their launch and recovery,especially when coordinating multi-glider deployments.This work focuses on cooperative path planning of an underwater glider fleet with simultaneous launch and recovery to enhance the autonomy of sampling and reduce deployment risks.Specifically,the gliders collaborate to achieve sampling considering the specified routines of interest.The overall paths to be planned are divided into four rectangular parts with the same starting point,and each glider is assigned a local sampling route.A clipped-oriented line-of-sight algorithm is proposed to ensure the coverage of the desired edges.The pitch angle of the glider is selected as the optimizing parameter to coordinate the overall progress considering the susceptibility of gliders to currents and the randomness of paths produced by complex navigational strategies.Therefore,a multi-actuation deep-Q network algorithm is proposed to ensure simultaneous launch and recovery.Simulation results demonstrate the acceptable effectiveness of the proposed method.
文摘China,when measured by gross tonnage,has surpassed Greece to become the world’s largest ship-owning country,according to data from Clarkson Research.The data shows that China’s ship-owning fleet has currently reached a total tonnage of 249.2 million GT,accounting for a market share of 15.9%(about USD 180 billion in fleet value),which is slightly higher than Greece’s 240.0 million GT and market share of 15.8%(about USD 163 billion in fleet value).Japan ranks third with a fleet of 181 million GT,followed by South Korea and the United States,both at around 66 million GT.
文摘Reducing the operation and maintenance (O & M) cost is one of the potential actions that could reduce the cost of energy produced by offshore wind farms. This article attempts to reduce O & M cost by improving the utilization of the maintenance resources, specifically the efficient scheduling and routing of the maintenance fleet. Scheduling and routing of maintenance fleet is a non-linear optimization problem with high complexity and a number of constraints. A heuristic algorithm, Ant Colony Optimization (ACO), was modified as Multi-ACO to be used to find the optimal scheduling and routing of maintenance fleet. The numerical studies showed that the proposed methodology was effective and robust enough to find the optimal solution even if the number of offshore wind turbine increases. The suggested approaches are helpful to avoid a time-consuming process of manually planning the scheduling and routing with a presumably suboptimal outcome.
文摘Forty-five years is nearly half a century, but merely a fleeting moment in the long course of history. This year marks the 45th anniversary of China-Malaysia diplomatic relations. Over the years, the two countries have witnessed tremendous changes and remained good friends and good partners. To commemorate this heart-warming occasion of friendship, artists from the two countries have worked together on songs, films and other art works to present special gifts for the people of the two countries.
基金supported by the National Natural Science Foundation of China(60774064)the Aerospace Science Foundation (20085153015)
文摘This article introduces a fleet composition algorithm for a fleet of intermediate carriers, which should deliver a swarm of miniature unmanned aerial vehicles （mini-UAVs） to a mission area. The algorithm is based on the sequential solution of several knapsack problems with various constraints. The algorithm allows both to form an initial set of required types of intermediate carriers, and to generate a fleet of intermediate carriers. The formation of a fleet of intermediate carriers to solve a suppression of enemy air defense （SEAD） problem is presented to illustrate the proposed algorithm.
基金The National Natural Science Foundationof China (70473037)
文摘A 0-1 integer programming model for weekly fleet assignment was put forward based on linear network and weekly flight scheduling in China. In this model, the objective function is to maximize the total profit of fleet assignment, subject to the constraints of coverage, aircraft flow balance, fleet size, aircraft availability, aircraft usage, flight restriction, aircraft seat capacity, and stopover. Then the branch-and-bound algorithm based on special ordered set was applied to solve the model. At last, a real- wofld case study on an airline with 5 fleets, 48 aircrafts and 1 786 flight legs indicated that the profit increase was ￥ 1 591276 one week and the running time was no more than 4 rain, which shows that the model and algorithm are fairly good for domestic airline.
文摘The area of operations management has had a substantial effect on the today’s air transportation management.Having moved with huge demand from management to obtain a competitive advantage in the market,the airlines are utilizing advanced optimization techniques to develop decision support systems for operations management and control.In order to provide a service with high quality and low cost,airlines spend a tremendous amount of resources and effort to generate profitable and cost-effective fare classes,flight schedules,fleet plans,aircraft routes,crew scheduling,gate assignment,etc.In this paper,the techniques and operations management applications that are used in the air transportation industry are reviewed including demand forecasting,fleet assignment,aircraft routing,crew scheduling,runway scheduling problem and gate assignment.
文摘The main objective of the study was to examine the influence of vehicle fleet management practices on service delivery in State-Owned Enterprises (SOEs) in Zimbabwe. The study adopted a pragmatism research philosophy together with a mixed method research paradigm. In addition, structured questionnaires were distributed to 344 respondents drawn from 86 SOEs. Stratified and purposive sampling was used. Descriptive statistics were calculated using Statistical Package for the Social Science (SPSS) version 20. Exploratory factor analysis (EFA) was done on all items of the study while research hypotheses were tested using Structural Equation Modelling (SEM) in AMOS version 21. The study concluded that vehicle maintenance, fuel management, driver management and vehicle replacement positively influence service delivery. In addition, the study also established that Information and Communication Technologies (ICTs) moderate the influence of vehicle fleet management practices on service delivery. The study recommended that there is need for regular driver training and vehicle programs encompassing electronic spares tracking.
文摘The study was designed to investigatecytogenotoxic effects of occupationalexposure to N,N’-methylene-bis-(2-amino-1,3,4-thiadiazole) (MATDA) for 11 workers(2 male,9 female) exposed to MATDA for 4-8 years,with the average level of 0.
