Materials Science Forum Vols. 626-627

Abstract: Cell formation, which involves grouping similar parts into part families and the corresponding machines into machine cells, is one of the key research issues for designing cellular manufacturing system. In this paper, a mathematical model which targets at maximizing the machine utilization and similarity of the part groups is built. A heuristic algorithm based on clustering analysis is proposed. An example is employed to illustrate the benefit of the approach and the results suggest that the proposed approach is feasible.

Abstract: This study explored the application of DSP real-time operating system BIOS to the software design of virtual terminal of tractors. In accordance with the functional requirements for the virtual terminal specified in ISO11783, the hardware system for the virtual terminal controller was developed, and the method of establishing DSP/BIOS configuration files, including the configuration of various parameters used in DSP/BIOS as well as the configuration of other DSP/BIOS modules needed, is studied. This study also explained the software program frame and the program design flow for the virtual terminal. The introduction of real-time operating system enabled the virtual terminal to be operated and controlled more easily and to run more smoothly.

Abstract: In order to minimize makespan for job-shop scheduling problem (JSP), an improved adaptive genetic algorithm (IAGA) based on hormone modulation mechanism is proposed. This algorithm has characteristics with avoiding overcoming premature phenomenon and slow evolution. The proposed IAGA algorithm is applied to dynamic job-shop scheduling problem (DJSP) and the satisfied result is obtained. By employing the proposed IAGA, machines can be used more efficiently, which means that tasks can be allocated appropriately, production efficiency can be improved, and the production cycle can be shortened efficiently. Therefore it embodies good adaptation to the DJSP (rush order, machine malfunction, and so on).

Abstract: Based on heterogeneous numerical control systems in the workshop layer, architecture of networked communication is established to meet the requirement of networked manufacturing. It realizes the integration and information interaction between shop floor equipment and upper layer application systems by integrating the information of the equipment layer with the workshop application layer. Networked communication mechanism of the architecture was constructed. Furthermore, information integration, i.e., integration of applied equipment, integration within enterprise based on Common Object Request Broker Architecture (CORBA), and integration between enterprises based on web Services, is also discussed in detail. Experiment demonstrates that the proposed system helps the information integration both within and between enterprises in the networked manufacturing system.

Abstract: The plan scheduling is an important part for forming a dynamic alliance on the ASP platform. In order to solve this problem, in the first place, a scheduling model of multi-objectives and multi-enterprise has been developed. The scheduling objectives of this model considered the enterprise credibility, production tasks, production process and the relationship between them. Secondly, a bi-level quantum evolutionary algorithm is provided for this model. One level is the coding of processes that determines the sequence of process. The other level is the coding of bidding enterprise that chooses each procedure of bidding enterprise. This scheduling approach in an ASP platform realizing dynamic alliance production scheduling system has been applied actually. And the approach can get faster convergence and better characteristics.

Abstract: Because of the dynamic and uncertain conditions of a real manufacturing system, many unforeseen events (e.g., machine breakdown, job revision, urgent jobs arrival, etc.) may lead to numerous schedule disruptions during schedule execution. In this paper, we present a new mixed technique that combines a proactive approach with a reactive approach to deal with scheduling problem under uncertainty. In the proactive phase, we build a robust baseline schedule that minimizes the schedules distance defined as the sum of the absolute deviations between the baseline and expected schedules. The robust baseline schedule contains some built-in flexibility in order to minimize the need of complex search procedures for the reactive scheduling approach. Based on the real-time manufacturing information getting online from the manufacturing execution system (MES), we then develop a reactive scheduling procedure to quickly revise the disrupted schedule when unexpected events occurring. The proposed framework integrated proactive and reactive approach is applied to molds production management system. The experimental results show that this mixed technique is more efficient than another technique when the duration of operation is uncertain.

Abstract: In this paper, a new digital signal processing method for ultrasonic time-of-flight diffraction (TOFD) estimation is presented. This method is based on wavelet analysis using the Morlet mother wavelet and the least mean squares (LMS) filter. It is designed to remove noise and identify the echo starting point of the ultrasonic signal reflected from the tip of a crack. Both simulated data and experimental data obtained from a steel plate with a crack are used to demonstrate the performance of the proposed method. This method is especially useful when the properties of the ultrasonic crack signal are unknown and the noise is heavy.

Abstract: Intense competition drives the need for dynamic integration of dispersed and heterogeneous manufacturing services. This paper proposes a kind of semantic-based service integration architecture for networked manufacturing. A unique property of this architecture is that it provides the unified interface encapsulation approach and semantic analyzing method to realize dynamic and loose coupling integration. Some key technologies are introduced to demonstrate how the proposed integration architecture can be used to establish a collaborative environment, wherein manufacturing services are semantic modeled, semantic analyzed, and dynamically integrated on-demand.

Abstract: This study is pointed to a computer table with five degree of freedom. The table position could be adjusted freely. The height of the tabletop also could be moved freely. The finite element analysis software ANSYS was used to analysis the strength and rigidity of the computer table. From the analysis results, it can be found that the strength and rigidity were fit in with the specification requirement with a safety factor of 1.20. From the modal analysis results, it also found that the stability of the computer was confirmed to the users.