YUEFEI XU - Academia.edu (original) (raw)
Papers by YUEFEI XU
Applied Mathematics and Computation, 2007
The completion time or makespan estimation of a set of jobs in batch process industries is studie... more The completion time or makespan estimation of a set of jobs in batch process industries is studied; Because jobs interact with each other at the level of shop floor, five interaction variables are defined and an indication of their influence on the makespan is experimentally investigated. A back-propagation network (BPN) model combined with genetic algorithms (GAs) to makespan estimation is proposed. GAs are adopted in the BPN to determine the parameters of BPN and to improve the accuracy of makespan estimation. Previously, there have been no appropriate rules to determine these parameters, 1000 training instances were used for training and evaluating the performance of the model. The study shows that combine GA with NN approach is more effective and accurate in estimating makespan than the BPN model by using trial and error.
In this paper, we consider the resource selection problem with due date constraint in production ... more In this paper, we consider the resource selection problem with due date constraint in production planning and control where the subtasks form a precedence network. We prove that this problem is NP-complete. Thus this problem cannot have any polynomial time solution algorithm at present. We establish a nonlinear integer-programming model for this problem, and prove the monotonicity properties of the objective function and constraint function in the model. Basing on our observations, we construct a Branch & Bound method to solve the problem. The test results show that this algorithm is effective.
This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing... more This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing systems (HMS). The concept of dynamic virtual clustering is extended to the control process of a holarchy or holonic organization. A task-oriented clustering mechanism and a corresponding optimization algorithm are presented as an efficient approach to the holonic control in the HMS d omain. The mediator-based dynamic virtual clustering mechanism is presented firstly. Then a negotiation strategy based on the Contract Net protocol is proposed for cooperative action among holons. Finally, a genetic algorithm-based optimization algorithm f or task allocation is described to support the optimum organization of a holarchy. This approach is illustrated through an example.
The system architecture for a holonic PLC (HPLC) is presented and the multi-level reconfiguration... more The system architecture for a holonic PLC (HPLC) is presented and the multi-level reconfiguration control mechanism for a function block (FB)-based PLC is detailed. Based on IEC-1499 FB model concepts, the concurrent process mechanism for FB configuration control and FB process control is put forward. In the presented approach, the dynamic reconfiguration control of the HPLC is handled at three control levels: function, component, and task control. Separating configuration control at the component level from task level facilitates a code-based component maintenance and task state transition process. It can carry out on-the-fly control for the HPLC by means of task level operation and smooth state transition cooperating with associated class maintenance under the limited capability of object oriented class dynamic configuration
This paper outlines a concurrent function block model to control the run-time reconfiguration pro... more This paper outlines a concurrent function block model to control the run-time reconfiguration process of a holonic controller. A multiagent-based concurrent execution mechanism to support run-time adaptability of the IEC 61499 basic and composite function block types is proposed. In this model, each function block contains control execution (CE) and execution control (EC) agents. In the basic function block, event-triggered CE agents are concerned with function block algorithms, while the EC agent manages and controls' the run-time configuration process of the function block itself. As well, the execution states of the function block can be switched between various states at runtime by the EC agent (e.g., running, configuring, etc.). Runtime reconfiguration of composite function blocks is accomplished using hierarchical finite state-machines with a multiple concurrency model
Recent ESL/EFL literature has frequently reported that Asian (especially East Asian) students of ... more Recent ESL/EFL literature has frequently reported that Asian (especially East Asian) students of English as a second/foreign language are reticent and passive learners. Cultural attributes of Asian societies are often cited as the main causes for such alleged behaviour of reticence and passivity. Based on counter evidence against these allegations, this article argues that it is a dangerous over-generalisation to say Asian students are reticent and passive learners. Results from existing research show that many Asian students do have a strong desire to participate in classroom activities. The article also argues that if some Asian students are indeed observed to be quieter than expected in certain circumstances, the causes are situation speci®c rather than culturally pre-set. These situation-speci®c causes could be the dierences between teaching methodologies and the lack of required foreign language pro®ciency. Interpretations based on cultural attributes should not be considered as an easier diagnosis for all problems arising in ESL/EFL practices. #
Applied Mathematics and Computation, 2007
The completion time or makespan estimation of a set of jobs in batch process industries is studie... more The completion time or makespan estimation of a set of jobs in batch process industries is studied; Because jobs interact with each other at the level of shop floor, five interaction variables are defined and an indication of their influence on the makespan is experimentally investigated. A back-propagation network (BPN) model combined with genetic algorithms (GAs) to makespan estimation is proposed. GAs are adopted in the BPN to determine the parameters of BPN and to improve the accuracy of makespan estimation. Previously, there have been no appropriate rules to determine these parameters, 1000 training instances were used for training and evaluating the performance of the model. The study shows that combine GA with NN approach is more effective and accurate in estimating makespan than the BPN model by using trial and error.
In this paper, we consider the resource selection problem with due date constraint in production ... more In this paper, we consider the resource selection problem with due date constraint in production planning and control where the subtasks form a precedence network. We prove that this problem is NP-complete. Thus this problem cannot have any polynomial time solution algorithm at present. We establish a nonlinear integer-programming model for this problem, and prove the monotonicity properties of the objective function and constraint function in the model. Basing on our observations, we construct a Branch & Bound method to solve the problem. The test results show that this algorithm is effective.
This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing... more This paper focuses on the dynamic re-configuration and task optimization of holonic manufacturing systems (HMS). The concept of dynamic virtual clustering is extended to the control process of a holarchy or holonic organization. A task-oriented clustering mechanism and a corresponding optimization algorithm are presented as an efficient approach to the holonic control in the HMS d omain. The mediator-based dynamic virtual clustering mechanism is presented firstly. Then a negotiation strategy based on the Contract Net protocol is proposed for cooperative action among holons. Finally, a genetic algorithm-based optimization algorithm f or task allocation is described to support the optimum organization of a holarchy. This approach is illustrated through an example.
The system architecture for a holonic PLC (HPLC) is presented and the multi-level reconfiguration... more The system architecture for a holonic PLC (HPLC) is presented and the multi-level reconfiguration control mechanism for a function block (FB)-based PLC is detailed. Based on IEC-1499 FB model concepts, the concurrent process mechanism for FB configuration control and FB process control is put forward. In the presented approach, the dynamic reconfiguration control of the HPLC is handled at three control levels: function, component, and task control. Separating configuration control at the component level from task level facilitates a code-based component maintenance and task state transition process. It can carry out on-the-fly control for the HPLC by means of task level operation and smooth state transition cooperating with associated class maintenance under the limited capability of object oriented class dynamic configuration
This paper outlines a concurrent function block model to control the run-time reconfiguration pro... more This paper outlines a concurrent function block model to control the run-time reconfiguration process of a holonic controller. A multiagent-based concurrent execution mechanism to support run-time adaptability of the IEC 61499 basic and composite function block types is proposed. In this model, each function block contains control execution (CE) and execution control (EC) agents. In the basic function block, event-triggered CE agents are concerned with function block algorithms, while the EC agent manages and controls' the run-time configuration process of the function block itself. As well, the execution states of the function block can be switched between various states at runtime by the EC agent (e.g., running, configuring, etc.). Runtime reconfiguration of composite function blocks is accomplished using hierarchical finite state-machines with a multiple concurrency model
Recent ESL/EFL literature has frequently reported that Asian (especially East Asian) students of ... more Recent ESL/EFL literature has frequently reported that Asian (especially East Asian) students of English as a second/foreign language are reticent and passive learners. Cultural attributes of Asian societies are often cited as the main causes for such alleged behaviour of reticence and passivity. Based on counter evidence against these allegations, this article argues that it is a dangerous over-generalisation to say Asian students are reticent and passive learners. Results from existing research show that many Asian students do have a strong desire to participate in classroom activities. The article also argues that if some Asian students are indeed observed to be quieter than expected in certain circumstances, the causes are situation speci®c rather than culturally pre-set. These situation-speci®c causes could be the dierences between teaching methodologies and the lack of required foreign language pro®ciency. Interpretations based on cultural attributes should not be considered as an easier diagnosis for all problems arising in ESL/EFL practices. #