This paper examines the yard truck scheduling,the yard location assignment for discharging containers,and the quay crane scheduling in container terminals.Taking into account the practical situation,we paid special at...This paper examines the yard truck scheduling,the yard location assignment for discharging containers,and the quay crane scheduling in container terminals.Taking into account the practical situation,we paid special attention to the loading and discharging precedence relationships between containers in the quay crane operations.A Mixed Integer Program（MIP） model is constructed,and a two-stage heuristic algorithm is proposed.In the first stage an Ant Colony Optimization（ACO） algorithm is employed to generate the yard location assignment for discharging containers.In the second stage,the integration of the yard truck scheduling and the quay crane scheduling is a flexible job shop problem,and an efficient greedy algorithm and a local search algorithm are proposed. Extensive numerical experiments are conducted to test the performance of the proposed algorithms.展开更多
The BUAA-BWB remotely piloted vehicle （RPV） designed by our research team encountered an unexpected landing safety problem in flight tests. It has obviously affected further research project for blended-wing-body （...The BUAA-BWB remotely piloted vehicle （RPV） designed by our research team encountered an unexpected landing safety problem in flight tests. It has obviously affected further research project for blended-wing-body （BWB） aircraft configuration characteristics. Searching for a safety improvement is an urgent requirement in the development work of the RPV. In view of the vehicle characteristics, a new systemic method called system-theoretic process analysis （STPA） has been tentatively applied to the hazardous factor analysis of the RPV flight test. An uncontrolled system behavior ＂path sagging phenomenon＂ is identified by implementing a three degrees of freedom simulation based on wind tunnel test data and establishing landing safety system dynamics archetype. To obtain higher safety design effectiveness and considering safety design precedence, a longitudinal ＂belly-flap＂ control surface is innovatively introduced and designed to eliminate hazards in landing. Finally, flight tests show that the unsafe factor has been correctly identified and the landing safety has been efficiently improved.展开更多
Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassem...Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassembly sequence planning problems efficiently, a product disassembly hybrid graph model, which describes the connection, non-connection and precedence relationships between the product parts, is established based on the characteristic of disassembly. Farther, the optimization model is provided to optimize disassembly sequence. And the solution methodology based on the genetic/simulated annealing algorithm with binaxy-tree algorithm is given. Finally, an example is analyzed in detail, and the result shows that the model is correct and efficient.展开更多
An integrated approach to generation of precedence relations and precedencegraphs for assembly sequence planning is presented, which contains more assembly flexibility. Theapproach involves two stages. Based on the as...An integrated approach to generation of precedence relations and precedencegraphs for assembly sequence planning is presented, which contains more assembly flexibility. Theapproach involves two stages. Based on the assembly model, the components in the assembly can bedivided into partially constrained components and completely con-strained components in the firststage, and then geometric precedence relation for every component is generated automatically.According to the result of the first stage, the second stage determines and constructs allprecedence graphs. The algorithms of these two stages proposed are verified by two assemblyexamples.展开更多
The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional informat...The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid （GABA）. We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions： no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-arninobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect.展开更多
The γ-aminobutyric acid neurons（GABAergic neurons） in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this class...The γ-aminobutyric acid neurons（GABAergic neurons） in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this classification is associated with physiological function, the exact role for neurons with various firing patterns in acoustic processing remains poorly understood. In the present study, we analyzed characteristics of inferior colliculus neurons in vitro, and recorded responses to stimulation of the dorsal nucleus of the lateral lemniscus using the wholecell patch clamp technique. Seven inferior colliculus neurons were tested and were classified into two firing patterns： sustained-regular（n = 4） and sustained-adapting firing patterns（n = 3）. The majority of inferior colliculus neurons exhibited slight changes in response to stimulation and bicuculline. The responses of one neuron with a sustained-adapting firing pattern were suppressed after stimulation, but recovered to normal levels following application of the γ-aminobutyric acid receptor antagonist. One neuron with a sustained-regular pattern showed suppressed stimulation responses, which were not affected by bicuculline. Results suggest that GABAergic neurons in the inferior colliculus exhibit sustained-regular or sustained-adapting firing patterns. Additionally, GABAergic projections from the dorsal nucleus of the lateral lemniscus to the inferior colliculus are associated with sound localization. The different neuronal responses of various firing patterns suggest a role in sound localization. A better understanding of these mechanisms and functions will provide better clinical treatment paradigms for hearing deficiencies.展开更多
Forest grammar,a new type of high-dimensional grammar,is proposed in this paper,of which both the left and the right parts of every production are concatenations of tree structures.A classification of forest grammar i...Forest grammar,a new type of high-dimensional grammar,is proposed in this paper,of which both the left and the right parts of every production are concatenations of tree structures.A classification of forest grammar is studied,especially,a subclass of the forest grammar,i.e.the context-sensitive forest grammar,and one of its subclasses is defined,called the weak precedence forest grammar.展开更多
An improved heuristic is proposed for one-machine scheduling problem with delay constraints,thus an open problem raised by Wikum et al.is solved.The heuristic solves the corresponding unit-execution-time problem optim...An improved heuristic is proposed for one-machine scheduling problem with delay constraints,thus an open problem raised by Wikum et al.is solved.The heuristic solves the corresponding unit-execution-time problem optimally.展开更多
The syntactic parsing algorithm of weak precedence forest grammar has been introduced and the correctness and unambiguity of this algorithm have been proved. An example is given to the syntactic parsing procedure of w...The syntactic parsing algorithm of weak precedence forest grammar has been introduced and the correctness and unambiguity of this algorithm have been proved. An example is given to the syntactic parsing procedure of weak precedence forest grammar.展开更多
Assessment is an important part of learning process. It can be defined as the process of gathering information for the purpose of making judgments about a current state of affairs presumably for the purpose of enhanci...Assessment is an important part of learning process. It can be defined as the process of gathering information for the purpose of making judgments about a current state of affairs presumably for the purpose of enhancing future outcomes [1]. It determines whether or not the goals of education are being met. Typically, most assessment tools give a numerical score as the result of the assessment. This may not be enough to improve the student’s progress. In this paper we defined main problems in current assessment tools and proposed a new assessment model that uses notions in knowledge space theory to overcome the shortage of the current assessment models. The experiment result showed that this new prototype made the assessment process easier and more effective. However, assessment affects decisions about grades, instructional needs and curriculum. This is an important phase of the learning process being showed in this paper in knowledge states framework. Future research will focus on making the tool behave intelligently to improve students’ learning momentum.展开更多
Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(...Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(WfMS). To tackle this problem,a workflow scheduling approach is proposed based on timing workflow net(TWF-net) and genetic algorithm(GA). The workflow is modelled in a form of TWF-net in favour of process simulation and resource conflict checking. After simplifying and reconstructing the set of workflow instance,the conflict resolution problem is transformed into a resource-constrained project scheduling problem(RCPSP),which could be efficiently solved by a heuristic method,such as GA. Finally,problems of various sizes are utilized to test the performance of the proposed algorithm and to compare it with first-come-firstserved(FCFS) strategy. The evaluation demonstrates that the proposed method is an overwhelming and effective approach for scheduling the concurrent processes with precedence and resource constraints.展开更多
基金supported by the National Nature Science Foundation of China under grant no.71102011
文摘This paper examines the yard truck scheduling,the yard location assignment for discharging containers,and the quay crane scheduling in container terminals.Taking into account the practical situation,we paid special attention to the loading and discharging precedence relationships between containers in the quay crane operations.A Mixed Integer Program（MIP） model is constructed,and a two-stage heuristic algorithm is proposed.In the first stage an Ant Colony Optimization（ACO） algorithm is employed to generate the yard location assignment for discharging containers.In the second stage,the integration of the yard truck scheduling and the quay crane scheduling is a flexible job shop problem,and an efficient greedy algorithm and a local search algorithm are proposed. Extensive numerical experiments are conducted to test the performance of the proposed algorithms.
基金National Natural Science Foundation of China (60832012)National High-tech Research and Development Program of China (2006AA11Z219)+1 种基金supported by Cheung Kong Scholars Innovation Team of Aero-Engine Complex System Safety of Ministry of Education of the People’s Republic of China (IRT 0905)Beijing Key Laboratory on Safety of Integrated Aircraft and Propulsion Systems
文摘The BUAA-BWB remotely piloted vehicle （RPV） designed by our research team encountered an unexpected landing safety problem in flight tests. It has obviously affected further research project for blended-wing-body （BWB） aircraft configuration characteristics. Searching for a safety improvement is an urgent requirement in the development work of the RPV. In view of the vehicle characteristics, a new systemic method called system-theoretic process analysis （STPA） has been tentatively applied to the hazardous factor analysis of the RPV flight test. An uncontrolled system behavior ＂path sagging phenomenon＂ is identified by implementing a three degrees of freedom simulation based on wind tunnel test data and establishing landing safety system dynamics archetype. To obtain higher safety design effectiveness and considering safety design precedence, a longitudinal ＂belly-flap＂ control surface is innovatively introduced and designed to eliminate hazards in landing. Finally, flight tests show that the unsafe factor has been correctly identified and the landing safety has been efficiently improved.
基金supported by the National High Technology Research and Development Program of China(2006AA04Z427).
文摘Disassembly sequence planning （DSP） plays a significant role in maintenance planning of the aircraft. It is used during the design stage for the analysis of maintainability of the aircraft. To solve product disassembly sequence planning problems efficiently, a product disassembly hybrid graph model, which describes the connection, non-connection and precedence relationships between the product parts, is established based on the characteristic of disassembly. Farther, the optimization model is provided to optimize disassembly sequence. And the solution methodology based on the genetic/simulated annealing algorithm with binaxy-tree algorithm is given. Finally, an example is analyzed in detail, and the result shows that the model is correct and efficient.
基金This project is supported by National Natural Science Foundation of China(No.59990470,No.59725514,No.59985004)and Robotics Laboratory,Chinese Academy of Sciences Foundation(No.RL200006)
文摘An integrated approach to generation of precedence relations and precedencegraphs for assembly sequence planning is presented, which contains more assembly flexibility. Theapproach involves two stages. Based on the assembly model, the components in the assembly can bedivided into partially constrained components and completely con-strained components in the firststage, and then geometric precedence relation for every component is generated automatically.According to the result of the first stage, the second stage determines and constructs allprecedence graphs. The algorithms of these two stages proposed are verified by two assemblyexamples.
基金supported by the National Natural Science Foundation of China,No.81271090 and the Beijing Natural Science Foundation,No.7112055
文摘The precedence effect is a prerequisite for faithful sound localization in a complex auditory environment, and is a physiological phenomenon in which the auditory system selectively suppresses the directional information from echoes. Here we investigated how neurons in the inferior colliculus respond to the paired sounds that produce precedence-effect illusions, and whether their firing behavior can be modulated through inhibition with gamma-aminobutyric acid （GABA）. We recorded extracellularly from 36 neurons in rat inferior colliculus under three conditions： no injection, injection with saline, and injection with gamma-aminobutyric acid. The paired sounds that produced precedence effects were two identical 4-ms noise bursts, which were delivered contralaterally or ipsilaterally to the recording site. The normalized neural responses were measured as a function of different inter-stimulus delays and half-maximal interstimulus delays were acquired. Neuronal responses to the lagging sounds were weak when the inter-stimulus delay was short, but increased gradually as the delay was lengthened. Saline injection produced no changes in neural responses, but after local gamma-arninobutyric acid application, responses to the lagging stimulus were suppressed. Application of gamma-aminobutyric acid affected the normalized response to lagging sounds, independently of whether they or the paired sounds were contralateral or ipsilateral to the recording site. These observations suggest that local inhibition by gamma-aminobutyric acid in the rat inferior colliculus shapes the neural responses to lagging sounds, and modulates the precedence effect.
基金supported by the National Natural Science Foundation of China,No.81271090
文摘The γ-aminobutyric acid neurons（GABAergic neurons） in the inferior colliculus are classified into various patterns based on their intrinsic electrical properties to a constant current injection. Although this classification is associated with physiological function, the exact role for neurons with various firing patterns in acoustic processing remains poorly understood. In the present study, we analyzed characteristics of inferior colliculus neurons in vitro, and recorded responses to stimulation of the dorsal nucleus of the lateral lemniscus using the wholecell patch clamp technique. Seven inferior colliculus neurons were tested and were classified into two firing patterns： sustained-regular（n = 4） and sustained-adapting firing patterns（n = 3）. The majority of inferior colliculus neurons exhibited slight changes in response to stimulation and bicuculline. The responses of one neuron with a sustained-adapting firing pattern were suppressed after stimulation, but recovered to normal levels following application of the γ-aminobutyric acid receptor antagonist. One neuron with a sustained-regular pattern showed suppressed stimulation responses, which were not affected by bicuculline. Results suggest that GABAergic neurons in the inferior colliculus exhibit sustained-regular or sustained-adapting firing patterns. Additionally, GABAergic projections from the dorsal nucleus of the lateral lemniscus to the inferior colliculus are associated with sound localization. The different neuronal responses of various firing patterns suggest a role in sound localization. A better understanding of these mechanisms and functions will provide better clinical treatment paradigms for hearing deficiencies.
基金Project supported by the National Natural Science Foundation of China
文摘Forest grammar,a new type of high-dimensional grammar,is proposed in this paper,of which both the left and the right parts of every production are concatenations of tree structures.A classification of forest grammar is studied,especially,a subclass of the forest grammar,i.e.the context-sensitive forest grammar,and one of its subclasses is defined,called the weak precedence forest grammar.
文摘An improved heuristic is proposed for one-machine scheduling problem with delay constraints,thus an open problem raised by Wikum et al.is solved.The heuristic solves the corresponding unit-execution-time problem optimally.
基金Project supported by the National Natural Science Foundation of China.
文摘The syntactic parsing algorithm of weak precedence forest grammar has been introduced and the correctness and unambiguity of this algorithm have been proved. An example is given to the syntactic parsing procedure of weak precedence forest grammar.
文摘Assessment is an important part of learning process. It can be defined as the process of gathering information for the purpose of making judgments about a current state of affairs presumably for the purpose of enhancing future outcomes [1]. It determines whether or not the goals of education are being met. Typically, most assessment tools give a numerical score as the result of the assessment. This may not be enough to improve the student’s progress. In this paper we defined main problems in current assessment tools and proposed a new assessment model that uses notions in knowledge space theory to overcome the shortage of the current assessment models. The experiment result showed that this new prototype made the assessment process easier and more effective. However, assessment affects decisions about grades, instructional needs and curriculum. This is an important phase of the learning process being showed in this paper in knowledge states framework. Future research will focus on making the tool behave intelligently to improve students’ learning momentum.
基金Supported by the Postdoctoral Science Foundation of China(No.2015M572022)the National Natural Science Foundation of China(No.51175304)
文摘Scarce resources,precedence and non-determined time-lag are three constraints commonly found in small and medium manufacturing enterprises(SMEs),which are deemed to block the application of workflow management system(WfMS). To tackle this problem,a workflow scheduling approach is proposed based on timing workflow net(TWF-net) and genetic algorithm(GA). The workflow is modelled in a form of TWF-net in favour of process simulation and resource conflict checking. After simplifying and reconstructing the set of workflow instance,the conflict resolution problem is transformed into a resource-constrained project scheduling problem(RCPSP),which could be efficiently solved by a heuristic method,such as GA. Finally,problems of various sizes are utilized to test the performance of the proposed algorithm and to compare it with first-come-firstserved(FCFS) strategy. The evaluation demonstrates that the proposed method is an overwhelming and effective approach for scheduling the concurrent processes with precedence and resource constraints.
