This paper studies the effect of different lengths of pre-task planning time on the frequency and accuracy of self-repairs for Chinese intermediate and advanced English learners.The findings reveal that the increased ...This paper studies the effect of different lengths of pre-task planning time on the frequency and accuracy of self-repairs for Chinese intermediate and advanced English learners.The findings reveal that the increased pre-task planning time strongly improves fluency and accuracy of self-repairs for both lexical and syntactic errors in the advanced group,but enhanced fluency and accuracy are not witnessed in the intermediate group as planning time increases.The differences are mainly due to the fact that some intermediate learners are not well equipped with the appropriate way of preparation for oral presentation tasks since some write down their ideas in Chinese.Thus errors will increasingly emerge in the transfer.Besides,they usually give priority to accuracy while neglecting fluency.展开更多
This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time ...This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time of the astronauts properly. A domain model is developed by using the ontology theory to describe the concepts, constraints and relations of the planning domain formally, abstractly and normatively. A method based on time iteration is adopted to solve the short-term planning problem. Meanwhile, the resolving strategies are proposed to resolve different kinds of conflicts induced by the constraints of power, heat, resource, astronaut and relationship. The proposed approach is evaluated in a test case with fifteen missions, thirteen resources and three astronauts. The results show that the developed domain ontology model is reasonable, and the time iteration method using the proposed resolving strategies can successfully obtain the plan satisfying all considered constraints.展开更多
The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused ...The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service(QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation(P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation(O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation(A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite(DVB-RCS) system or IP onboard routing BSM system in the future.展开更多
In this paper, a manufacturing supply chain system composed by a single-product machine, a buffer and a stochastic demand is considered. A stochastic fluid model is adopted to describe the system and to take into acco...In this paper, a manufacturing supply chain system composed by a single-product machine, a buffer and a stochastic demand is considered. A stochastic fluid model is adopted to describe the system and to take into account stochastic delivery times. The objective of this paper is to evaluate the optimal buffer level used in hedging point policy taken into account planned delivery times, machine failures and random demands. This optimal buffer allows minimizing the sum of inventory, transportation, lost sales and late delivery costs. Infinitesimal perturbation analysis method is used for optimizing the proposed system. Using the stochastic fluid model, the trajectories of buffer level are studied and the infinitesimal perturbation analysis estimators are evaluated. These estimators are shown to be unbiased and then they are implanted in an optimization algorithm, which determines the optimal buffer level in the presence of planned delivery time. Also in this work, we discuss the advantage of the use of the infinitesimal perturbation analysis method comparing to classical simulation methods.展开更多
Vice president of China National Nonferrous Metals Industries Corporation Mr. WoTingshu said:"The output of 10 kinds of nonferrous metals amounted to 2.45 Mt." This factmean1s that the national plan for nonf...Vice president of China National Nonferrous Metals Industries Corporation Mr. WoTingshu said:"The output of 10 kinds of nonferrous metals amounted to 2.45 Mt." This factmean1s that the national plan for nonferrous metals production fulfiled earlier. The 10 kinds ofnonferrous metals are aluminium, magnesium, lead, zinc, copper, tin, nickel, antimony mercuryand titanium.展开更多
The state-space neural network and extended Kalman filter model is used to directly predict the optimal timing plan that corresponds to futuristic traffic conditions in real time with the purposes of avoiding the lagg...The state-space neural network and extended Kalman filter model is used to directly predict the optimal timing plan that corresponds to futuristic traffic conditions in real time with the purposes of avoiding the lagging of the signal timing plans to traffic conditions. Utilizing the traffic conditions in current and former intervals, the network topology of the state-space neural network （SSNN）, which is derived from the geometry of urban arterial routes, is used to predict the optimal timing plan corresponding to the traffic conditions in the next time interval. In order to improve the effectiveness of the SSNN, the extended Kalman filter （EKF） is proposed to train the SSNN instead of conventional approaches. Raw traffic data of the Guangzhou Road, Nanjing and the optimal signal timing plan generated by a multi-objective optimization genetic algorithm are applied to test the performance of the proposed model. The results indicate that compared with the SSNN and the BP neural network, the proposed model can closely match the optimal timing plans in futuristic states with higher efficiency.展开更多
This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits...This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.展开更多
This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging co...This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered： multi-level serial-production and assembly systems. For the serial production systems （one type of component at each level）, a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and se＇~eral numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.展开更多
China is among the first countries in the world in developing the science of urban planning,and has evolved her own unique system.Through investigating the structural features of the plan-ning system,the laws governin...China is among the first countries in the world in developing the science of urban planning,and has evolved her own unique system.Through investigating the structural features of the plan-ning system,the laws governing its development and the causes of the rise and fall of the ancientplanning system,this article attempts to propose some insights useful to the establishment and de-velopment of the modern city planning in China.展开更多
In this paper,the problem of time optimal feedrate generation under confined feedrate,axis accelerations,and axis tracking errors is considered.The main contribution is to reduce the tracking error constraint to const...In this paper,the problem of time optimal feedrate generation under confined feedrate,axis accelerations,and axis tracking errors is considered.The main contribution is to reduce the tracking error constraint to constraints about the axis velocities and accelerations,when the tracking error satisfies a second order linear ordinary differential equation.Based on this simplification on the tracking error,the original feedrate generation problem is reduced to a new form which can be efficiently solved with linear programming algorithms.Simulation results are used to validate the methods.展开更多
文摘This paper studies the effect of different lengths of pre-task planning time on the frequency and accuracy of self-repairs for Chinese intermediate and advanced English learners.The findings reveal that the increased pre-task planning time strongly improves fluency and accuracy of self-repairs for both lexical and syntactic errors in the advanced group,but enhanced fluency and accuracy are not witnessed in the intermediate group as planning time increases.The differences are mainly due to the fact that some intermediate learners are not well equipped with the appropriate way of preparation for oral presentation tasks since some write down their ideas in Chinese.Thus errors will increasingly emerge in the transfer.Besides,they usually give priority to accuracy while neglecting fluency.
基金supported by the National Natural Science Foundation of China(11402295)the Science Project of National University of Defense Technology(JC14-01-05)the Hunan Provincial Natural Science Foundation of China(2015JJ3020)
文摘This paper studies the problem of the space station short-term mission planning, which aims to allocate the executing time of missions effectively, schedule the corresponding resources reasonably and arrange the time of the astronauts properly. A domain model is developed by using the ontology theory to describe the concepts, constraints and relations of the planning domain formally, abstractly and normatively. A method based on time iteration is adopted to solve the short-term planning problem. Meanwhile, the resolving strategies are proposed to resolve different kinds of conflicts induced by the constraints of power, heat, resource, astronaut and relationship. The proposed approach is evaluated in a test case with fifteen missions, thirteen resources and three astronauts. The results show that the developed domain ontology model is reasonable, and the time iteration method using the proposed resolving strategies can successfully obtain the plan satisfying all considered constraints.
基金Supported by the National Natural Science Foundation ofChina (No. 60972061,60972062,and 61032004)the Na-tional High Technology Research and Development Program of China ("863" Program) (No. 2008AA12A204,2008AA12Z307)+1 种基金Natural Science Foundation of Jiangsu Province (BK2009060)the"Triple Three" High Level Talent Development Plan of Jiangsu Province
文摘The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service(QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation(P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation(O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation(A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite(DVB-RCS) system or IP onboard routing BSM system in the future.
文摘In this paper, a manufacturing supply chain system composed by a single-product machine, a buffer and a stochastic demand is considered. A stochastic fluid model is adopted to describe the system and to take into account stochastic delivery times. The objective of this paper is to evaluate the optimal buffer level used in hedging point policy taken into account planned delivery times, machine failures and random demands. This optimal buffer allows minimizing the sum of inventory, transportation, lost sales and late delivery costs. Infinitesimal perturbation analysis method is used for optimizing the proposed system. Using the stochastic fluid model, the trajectories of buffer level are studied and the infinitesimal perturbation analysis estimators are evaluated. These estimators are shown to be unbiased and then they are implanted in an optimization algorithm, which determines the optimal buffer level in the presence of planned delivery time. Also in this work, we discuss the advantage of the use of the infinitesimal perturbation analysis method comparing to classical simulation methods.
文摘Vice president of China National Nonferrous Metals Industries Corporation Mr. WoTingshu said:"The output of 10 kinds of nonferrous metals amounted to 2.45 Mt." This factmean1s that the national plan for nonferrous metals production fulfiled earlier. The 10 kinds ofnonferrous metals are aluminium, magnesium, lead, zinc, copper, tin, nickel, antimony mercuryand titanium.
基金The National Natural Science Foundation of China (No.50422283)the Soft Science Research Project of Ministry of Housing and Urban-Rural Development of China (No.2008-K5-14)
文摘The state-space neural network and extended Kalman filter model is used to directly predict the optimal timing plan that corresponds to futuristic traffic conditions in real time with the purposes of avoiding the lagging of the signal timing plans to traffic conditions. Utilizing the traffic conditions in current and former intervals, the network topology of the state-space neural network （SSNN）, which is derived from the geometry of urban arterial routes, is used to predict the optimal timing plan corresponding to the traffic conditions in the next time interval. In order to improve the effectiveness of the SSNN, the extended Kalman filter （EKF） is proposed to train the SSNN instead of conventional approaches. Raw traffic data of the Guangzhou Road, Nanjing and the optimal signal timing plan generated by a multi-objective optimization genetic algorithm are applied to test the performance of the proposed model. The results indicate that compared with the SSNN and the BP neural network, the proposed model can closely match the optimal timing plans in futuristic states with higher efficiency.
基金supported by the National Defense Foundation of China(No.403060103)
文摘This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle （UCAV） performing autonomous air-to-surface （A/S） attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem （RHC-OCP）. In particular, an approximate elliptic launch acceptable region （LAR） model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom （2-DOF） receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.
文摘This paper deals with the problem of planned lead time calculation in a Material Requirement Planning （MRP） environment under stochastic lead times. The objective is to minimize the sum of holding and backlogging costs. The proposed approach is based on discrete time inventory control where the decision variables are integer. Two types of systems are considered： multi-level serial-production and assembly systems. For the serial production systems （one type of component at each level）, a mathematical model is suggested. Then, it is proven that this model is equivalent to the well known discrete Newsboy Model. This directly provides the optimal values for the planned lead times. For multilevel assembly systems, a dedicated model is proposed and some properties of the decision variables and objective function are proven. These properties are used to calculate lower and upper limits on the decision variables and lower and upper bounds on the objective function. The obtained limits and bounds open the possibility to develop an efficient optimization algorithm using, for example, a Branch and Bound approach. The paper presents the proposed models in detail with corresponding proofs and se＇~eral numerical examples. Some advantages of the suggested models and perspectives of this research are discussed.
文摘China is among the first countries in the world in developing the science of urban planning,and has evolved her own unique system.Through investigating the structural features of the plan-ning system,the laws governing its development and the causes of the rise and fall of the ancientplanning system,this article attempts to propose some insights useful to the establishment and de-velopment of the modern city planning in China.
基金partially supported by a National Key Basic Research Project of China under Grant No.2011CB302400the Natural Science Foundation of China under Grant No.60821002
文摘In this paper,the problem of time optimal feedrate generation under confined feedrate,axis accelerations,and axis tracking errors is considered.The main contribution is to reduce the tracking error constraint to constraints about the axis velocities and accelerations,when the tracking error satisfies a second order linear ordinary differential equation.Based on this simplification on the tracking error,the original feedrate generation problem is reduced to a new form which can be efficiently solved with linear programming algorithms.Simulation results are used to validate the methods.
