This paper presents an object oriented Petri net (OOPN) schema to model the dynamic behaviors of a flexible manufacturing cells (FMCs). The OOPN paradigm incorporates the characteristics of a Petri net and OOP. It in...This paper presents an object oriented Petri net (OOPN) schema to model the dynamic behaviors of a flexible manufacturing cells (FMCs). The OOPN paradigm incorporates the characteristics of a Petri net and OOP. It increases the maintainability and reusability of objects in Petri net modeling, thus it has more powerful modeling and analysis abilities.展开更多
Due to the development of advanced manufacturing technology and the introduction of Smart Manufacturing notion in the field of modern industrial production, welding flexible manufacturing using robot technology has b...Due to the development of advanced manufacturing technology and the introduction of Smart Manufacturing notion in the field of modern industrial production, welding flexible manufacturing using robot technology has become the inevitable developing direction on welding automation. Based on a new intelligent arc welding flexible manufacturing cell (WFMC), its system structure and control policies are studied in this paper. Aiming at the different information flows among every subsystem and central monitoring computer in this WFMC, Petri net theory is introduced into the process of welding manufacturing. A discrete control model of WFMC has been constructed, in which the system's status is regarded as place and the control process is regarded as transition. Moreover, grounded on automation Petri net principle, the judging and utilizing of information obtained from welding sensors are imported into Petri net structure, which extends the traditional Petri net concepts. The control model and policies researched in this paper have established foundation for further intelligent real time control on welding flexible manufacturing cell and system.展开更多
In few years only, the efficiency record of perovskite solar cells（PSCs） has raised quickly from 3.8% to over 22%. This emerging photovoltaic technology has primarily shown its great potential of industrialization. ...In few years only, the efficiency record of perovskite solar cells（PSCs） has raised quickly from 3.8% to over 22%. This emerging photovoltaic technology has primarily shown its great potential of industrialization. Flexible PSCs are thought to be one of the most priority options for mass production, related to the intrinsic advantage of perovskite thin films which could be deposited by facile solution processes at low temperature. Flexible PSCs have at least four advantages in comparison to the rigid counterpart：（1） it can generate higher power output at lighter weight,（2） it is easily portable,（3） it can be easily attached to architectures or textiles with diverse shapes, and（4） it is compatible with roll-to-roll fabrication in a large scale. In this review, we have summarized recent development of the key materials and technologies applied in flexible PSCs. The key materials including flexible substrates, transparent and conductive electrodes, and interfacial materials; some key technologies about roll-to-roll manufacture, encapsulation technology have been overviewed. Finally, a prospect on possible application directions of flexible PSCs has been discussed.展开更多
In this paper, steady-state behaviors for a large class of flexible manufacturing cells are considered under two types of schedules, i.e., simple schedule and composite schedule. It is shown that each composite schedu...In this paper, steady-state behaviors for a large class of flexible manufacturing cells are considered under two types of schedules, i.e., simple schedule and composite schedule. It is shown that each composite schedule can be obtained by composition of simple ones. A systematic approach to modeling and analysis of schedules is proposed cycle times of timed petri net models of schedules are derived. A example of three-machine cell is given.展开更多
The initial and significant step in the design of a cellular manufacturing system is cell formation (CF).CF problem is proposed in this paper as a decision problem that determines to manufacture specified types of par...The initial and significant step in the design of a cellular manufacturing system is cell formation (CF).CF problem is proposed in this paper as a decision problem that determines to manufacture specified types of part in a manufacturing plant which machines and their associated parts are grouped together to form cell in a way that a concerned objective is optimized. For describing CF problem clearly,this paper firstly presents a review of cell formation problem from the view points of objective function.The CF problems are classified into three categories,which are cost oriented,flexibility oriented and grouping efficiency oriented CF problems.Then,the paper presents a comprehensive conceptual mathematical formulation describing the general cost problem and a decision variable for comprehensive describing routing flexibility and two trade-off questions in grouping efficiency issues.Finally,based on the review and discussion,the paper proposes five directions for future research in the CF field.展开更多
文摘This paper presents an object oriented Petri net (OOPN) schema to model the dynamic behaviors of a flexible manufacturing cells (FMCs). The OOPN paradigm incorporates the characteristics of a Petri net and OOP. It increases the maintainability and reusability of objects in Petri net modeling, thus it has more powerful modeling and analysis abilities.
基金SupportedbyNationalNaturalScienceFoundationofChina (No .5 96 35 16 0 )Pre ResearchingKeyProjectoNationalDefenseTechnology
文摘Due to the development of advanced manufacturing technology and the introduction of Smart Manufacturing notion in the field of modern industrial production, welding flexible manufacturing using robot technology has become the inevitable developing direction on welding automation. Based on a new intelligent arc welding flexible manufacturing cell (WFMC), its system structure and control policies are studied in this paper. Aiming at the different information flows among every subsystem and central monitoring computer in this WFMC, Petri net theory is introduced into the process of welding manufacturing. A discrete control model of WFMC has been constructed, in which the system's status is regarded as place and the control process is regarded as transition. Moreover, grounded on automation Petri net principle, the judging and utilizing of information obtained from welding sensors are imported into Petri net structure, which extends the traditional Petri net concepts. The control model and policies researched in this paper have established foundation for further intelligent real time control on welding flexible manufacturing cell and system.
基金financially supported by the National Natural Science Foundation of China(51672094,51661135023)the National Key R&D Program of China(2016YFC0205002)+1 种基金the Selfdetermined and Innovative Research Funds of HUST(2016JCTD111)the open research funds of Engineering Research Center of Nano-Geo Materials of Ministry of Education,China University of Geosciences(NGM2017KF013)
文摘In few years only, the efficiency record of perovskite solar cells（PSCs） has raised quickly from 3.8% to over 22%. This emerging photovoltaic technology has primarily shown its great potential of industrialization. Flexible PSCs are thought to be one of the most priority options for mass production, related to the intrinsic advantage of perovskite thin films which could be deposited by facile solution processes at low temperature. Flexible PSCs have at least four advantages in comparison to the rigid counterpart：（1） it can generate higher power output at lighter weight,（2） it is easily portable,（3） it can be easily attached to architectures or textiles with diverse shapes, and（4） it is compatible with roll-to-roll fabrication in a large scale. In this review, we have summarized recent development of the key materials and technologies applied in flexible PSCs. The key materials including flexible substrates, transparent and conductive electrodes, and interfacial materials; some key technologies about roll-to-roll manufacture, encapsulation technology have been overviewed. Finally, a prospect on possible application directions of flexible PSCs has been discussed.
文摘In this paper, steady-state behaviors for a large class of flexible manufacturing cells are considered under two types of schedules, i.e., simple schedule and composite schedule. It is shown that each composite schedule can be obtained by composition of simple ones. A systematic approach to modeling and analysis of schedules is proposed cycle times of timed petri net models of schedules are derived. A example of three-machine cell is given.
基金Supported by the Natural Science Foundation of China(70471028)New Century Excellent Talents(NCET-04-0280)Key Scientific Research Program(104064)of Ministry of Education of China
文摘The initial and significant step in the design of a cellular manufacturing system is cell formation (CF).CF problem is proposed in this paper as a decision problem that determines to manufacture specified types of part in a manufacturing plant which machines and their associated parts are grouped together to form cell in a way that a concerned objective is optimized. For describing CF problem clearly,this paper firstly presents a review of cell formation problem from the view points of objective function.The CF problems are classified into three categories,which are cost oriented,flexibility oriented and grouping efficiency oriented CF problems.Then,the paper presents a comprehensive conceptual mathematical formulation describing the general cost problem and a decision variable for comprehensive describing routing flexibility and two trade-off questions in grouping efficiency issues.Finally,based on the review and discussion,the paper proposes five directions for future research in the CF field.
