柔性制造系统检测监控系统的研究

根据柔性制造系统的实际需要，研制了一个ＦＭＳ运行状态检测监控系统，介绍了该系统的功能与结构，论述了系统与ＦＭＳ的集成方法，讨论了系统的工作流程及对ＦＭＳ故障的处理策略。     

FMS统一建模技术与方法

针对ＦＭＳ的组成结构及控制特点,提出了一种层次递阶的统一建模方法。以面向对象建模技术和方法为主线,通过消息传递驱动机制使各层递阶模型有机集成为统一的整体,并与实际系统中各个层次及其关系相对应,从而准确,方便地描术字ＦＭＳ的规划设计、调度控制、运行及仿真等各个过程。     

A method for comparing flexibility performance for the lifecycle of manufacturing systems under capacity planning constraints

The objective of this work is to describe a method for comparing the flexibility performance of manufacturing systems, in an uncertain environment, under lifecycle considerations and capacity planning constraints. The manufacturing systems costs are estimated over a time horizon and for a large variety of possible market scenarios. In order for the lifecycle cost values to be comparable among different systems, their values are calculated with the use of a special purpose algorithm. Statistical analysis of the estimated cost values is then employed for assessing the flexibility of each manufacturing system. The method is applied in an industrial case for checking, also from a flexibility point of view, the investment on a production system, using real life industrial data.     

A simulation analysis of factors influencing the flexibility of cellular manufacturing

The performance of cellular manufacturing (CM) systems in a variable demand and flexible workforce environment has been examined using simulation modelling. Discrepancies between academicians and practitioners’ findings with respect to flexibility and uneven machine utilization in CM systems are discussed. The views of two parties were incorporated in simulation models to rectify the existing discrepancies. While the results of this study confirm the previous findings of academicians regarding the deterioration of the performance of CM in a variable product mix situation, it appears that those results may be significantly influenced by considering a flexible workforce. The simulation results show that the practice of using flexible crossed-trained operators can improve the flexibility of CM in dealing with an unstable demand and can reduce load imbalance inherent in machine dedication in manufacturing cells.     

高级Petri网及FMS的动态建模和仿真

给出了一种柔性制造系统模型，它能模仿和跟踪车间中散件调度计划的执行过程。模型由一类新的高级Ｐｅｔｒｉ网组成，它定义了着色令牌，时化变迁和谓词变迁，抽象了物理对象的主要属性和它们间的基本关联。通过数据库描述令牌属性，规则库描述变迁，构成了一种结构紧凑，信息丰富，可反映多个工作进程的高级Ｐｅｔｒｉ网模型。     

Intelligent decision support system for the adaptive control of a flexible manufacturing system with machine and tool flexibility

This paper describes an intelligent decision support system (IDSS) for real time control of a flexible manufacturing system (FMS). The controller is capable of classifying symptoms in developing the control policies on FMSs with flexibility in operation assignment and scheduling of multi-purpose machining centres which have different tools with their own efficiency. The proposed system is implemented by coupling of rule-based IDSS, simulation block and centralised simulation optimiser for elicitation of shop floor control knowledge. This posteriori adaptive controller uses a new bilateral mechanism in simulation optimiser block for offline training of IDSS based on multi-performance criteria simulation optimisation. The proposed intelligent controller receives online information of the FMS current state and trigger appropriate control rule within real-time simulation data exchange. Finally the FMS intelligent controller is validated by a benchmark test problem. Application of this adaptive controller showed that it could be an effective approach for real time control of various flexible manufacturing systems.     

Isophote-based ruled surface approximation of free-form surfaces and its application in NC machining

This paper presents a method to approximate free-form surfaces using piecewise ruled surface and its application in five-axis NC machining. New concepts of isophote, iso-inclination curve and iso-inclination angle are introduced to facilitate the generation of the piecewise ruled surfaces. The resulting ruled surfaces are adaptive to the surface features, such as peaks and valleys. Adjusting the isoinclination angle controls the error of this approximation. The application of the isophote-based ruled surface approximation in five-axis NC machining is also studied. The tapered tools are suggested to cut the ruled surfaces. Methods for selecting appropriate tools and generating tool paths are presented. The present case studies show that the new approach may lead to the integration of rough, semi-finish and finish machining of free-form surfaces.     

Study on sub-cycling algorithm for flexible multi-body system: stability analysis and numerical examples

Numerical stability is an important issue for any integral procedure. Since sub-cycling algorithm has been presented by Belytschko et al. (Comput Methods Appl Mech Eng 17/18: 259–275, 1979), various kinds of these integral procedures were developed in later 20 years and their stability were widely studied. However, on how to apply the sub-cycling to flexible multi-body dynamics (FMD) is still a lack of investigation up to now. A particular sub-cycling algorithm for the FMD based on the central difference method was introduced in detail in part I (Miao et al. in Comp Mech doi: 10.1007/s00466-007-0183-9) of this paper. Adopting an integral approximation operator method, stability of the presented algorithm is transformed to a generalized eigenvalue problem in the paper and is discussed by solving the problem later. Numerical examples are performed to verify the availability and efficiency of the algorithm further.     

The robustness and efficiency of trimmed elemental estimation in regression analysis: a Monte Carlo simulation study

Mayo and Gray [Am Statist 51 (1997) 122] introduced the leverage-residual weighted elemental (LRWE) classification of regression estimators and proposed a new method of estimation called trimmed elemental estimation (TEE). In this article, we perform a simulation study of the efficiency of certain TEE estimators relative to ordinary least squares under normal errors and their robustness under various non-normal error distributions in the context of the simple linear regression model. Comparisons among these estimators are made on the basis of mean square error and percentiles of the absolute estimation errors in the simulations.     

Monte Carlo simulation analysis of the effects of different system performance levels on the importance of multi-state components

In the present paper, we consider some frequently used importance measures, in their generalized form proposed by the authors for application to multi-state systems constituted by multi-state components. To catch the dynamics of multi-state systems, Monte Carlo simulation has been utilized. A simulation approach has been presented which allows estimating of all the importance measures of the components at a given performance level in a single simulation, provided that the components are independent. The effects of different performance demands made on the system on the importance of its multi-state components have been examined with respect to a simple multi-state series–parallel system. The results have shown that a performance level of a component may be more critical for the achievement of a system performance and less critical for another.     

Effects of information transparency and cooperation on supply chain performance: a simulation study

This research explores the effect of information transparency and cooperation among the front nodes of supply chains. Although published works in the supply chain (SC) domain underline the need for information transparency and cooperation for competitiveness of firms, the majority among these are conceptual or empirical. As such, the domain requires fresh effort towards analytical and simulation based research for validation. In the present work, simulation is used as the research methodology. The simulation platform is developed in ARENA®, which is based on simulation language SIMAN. It has the capability to model multi-product, multi-echelon supply chains. Cooperation is depicted in the form of demand pooling and accelerated delivery of consignments from cooperating SC nodes, when stock-out contingency occurs at a particular node. The modelling also explores the effects of full, partial and zero level of information transparency on the SC performance. The simulation results suggest that these initiatives improve SC service time performance. It is also observed that more advantages from cooperation and information transparency are obtainable when the SC is leaner. The studies also highlight that such SC initiative that motivates local optimisation at the nodes is counter-productive to SC wide performance.     

Experiment and simulation on the performance of an autocascade refrigeration system using carbon dioxide as a refrigerant

The main purpose of this study is to investigate the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744/134a and R744/290. One of the advantages of this system is the possibility of keeping the highest pressure of the system within a limit by selecting the composition of a refrigerant mixture as compared to that in the vapor compression system using pure carbon dioxide. Performance test and simulation have been carried out for an autocascade refrigeration system by varying secondary fluid temperatures at evaporator and condenser inlets. Variations of mass flow rate of refrigerant, compressor power, refrigeration capacity, and coefficient of performance (COP) with respect to the mass fraction of R744 in R744/134a and R744/290 mixtures are presented at different operating conditions. Experimental results show similar trends with those from the simulation. As the composition of R744 in the refrigerant mixture increases, cooling capacity is enhanced, but COP tends to decrease while the system pressure rises.

Résumé

The main purpose of this study is to investigate the performance of an autocascade refrigeration system using zeotropic refrigerant mixtures of R744/134a and R744/290. One of the advantages of this system is the possibility in keeping the highest pressure of the system within a limit by selecting the composition of a refrigerant mixture as compared to that in the vapor compression system using pure carbon dioxide. Performance test and simulation have been carried out for an autocascade refrigeration system by varying secondary fluid temperatures at evaporator and condenser inlets. Variations of mass flow rate of refrigerant, compressor power, refrigeration capacity, and coefficient of performance (COP) with respect to the mass fraction of R744 in R744/134a and R744/290 mixtures are presented at different operating conditions. Experimental results show similar trends with those from the simulation. As the composition of R744 in the refrigerant mixture increases, cooling capacity is enhanced, but COP tends to decrease while the system pressure rises.     

SRMES: an expert system for performance analysis of small refrigerating machines

SRMES is a rule-based expert system designed for use in the refrigeration industry as an aid in diagnosing the most frequent malfunctions in small refrigerating machines of either the air- or water-cooled condenser type. Suitably expanded, it may cover other more complex types of refrigerating machine. The system could also be suitable for education and training. In the version described here, SRMES is intended to demonstrate that the use of expert system tools in the refrigeration industry may lead to higher efficiency and better performance. Although the version described in the paper has been optimized for off-line performance, its extension to on-line application may be justified by relevant experience gained through its practical operation. Particular attention is devoted in the paper to the development of the decision tree. It is shown that with computer hardware of limited capacity knowledge-based rules can be used to reach specific diagnoses of the performance of small refrigerating machines.     

Relative impact of different ERP forms on manufacturing organisations: an exploratory analysis of a global manufacturing survey

There are many types of enterprise resource planning (ERP) systems, ranging from very large and very functional vendor products such as those provided by SAP and Oracle, through in-house systems, and smaller vendor products. Thus, there is a substantial range of enterprise computing support available for manufacturing organisations and their manufacturing planning and control. The Global Manufacturing Research Group (GMRG) has collected a systematic survey of manufacturing organisations around the world, providing a picture of manufacturing operations. We have taken GMRG data and organised it around seven levels of ERP functionality, and analysed these data to determine effectiveness in terms of how ERP systems are used in global manufacturing firms, their role in accomplishing manufacturing planning and control, the relationship between ERP forms and data-management practices, the satisfaction firms have across ERP forms, and finally, relative perceived benefits and costs across ERP forms.     

The impacts of environmental performance and development of financing decisions on economic sustainable performance: from the view of renewable and clean energy industry

Clean Technologies and Environmental Policy - Developing green economy and mitigating environmental pollution have strategically important role in China's commitments against global climate...     

The effect of an electrical double layer on the voltammetric performance of nanoscale interdigitated electrodes: a simulation study

Finite-element based computational simulation is performed to investigate the effect of an electrical double layer (EDL) on the electrochemical processes of nanometer-scale interdigitated electrodes (nano-IDEs). Results show that the EDL structure will alter the voltammetric current response of nano-IDEs due to the expansion of the diffuse layer into the diffusion layer at the electrode surfaces and the overlap of the electrical fields of the neighboring electrodes. The EDL induced change in the voltammetric current response is more severe for nano-IDEs with a smaller electrode size and gap spacing, and the EDL effect is influenced by the compact layer thickness, the charge valence of the redox species, the electron transfer rate, and the absence of the supporting electrolyte.     

Effects of pre-strain applied at a polyethylene terephthalate substrate before the coating of TiO2 film on the coating film quality and optical performance

A mold was designed to create various strains in polyethylene terephthalate (PET) substrates before the deposition of TiO₂ film to simulate deposition process on a cylindrical drum. The residual stress of the PET substrate with TiO₂ film significantly increased with increasing strain, decreasing the radius of curvature. Compared to the as-received PET substrate, there was a noticeable increase in the surface roughness in the PET/TiO₂ specimens when a large strain was applied. The formation of voids or cavities in the TiO₂ layer significantly increased the roughness of the specimen. The mean cavity size and depth increased with increasing strain. For strains ≦ 4%, the specimen's hardness and Young's modulus factored by the voids/cavities increased with increasing surface roughness. The optical absorption increased with increasing surface roughness before becoming asymptotic to a constant value. The strain applied to the PET substrate before TiO₂ deposition greatly affects the optical reflection, transmittance, and absorption.     

Analysis and improvement of multi-product assembly systems: an application study at a furniture manufacturing plant

In this paper, we introduce an application study of modelling, analysis and continuous improvement of an assembly system at a furniture manufacturing plant using production systems engineering methods. Analytical models have been developed to characterise the assembly system making multiple products, and recursive procedures have been derived to evaluate line production rate. Lot size analysis is carried out, and bottleneck analysis methods are introduced to identify the bottlenecks, whose improvement can lead to the largest improvement in system performance. Such methods provide a quantitative tool for plant engineers and managers to operate and improve assembly line with high productivity, and are also applicable to other large-volume manufacturing systems.     

A decision support framework for global supply chain modelling: an assessment of the impact of demand,supply and lead-time uncertainties on performance

We developed a decision support framework for a global manufacturer of specialty chemicals to study the relative impact of demand, supply and lead-time uncertainties on cost and customer service performance. Our approach combines optimisation and simulation methodologies as follows: mathematical models provide optimal plans via a novel approach to the supply chain planning mechanism of the Company. Simulation models execute the supply chain plans so as to allow the examination of the outcomes under the various sources of uncertainty. The iterative use of optimisation and simulation methodologies allows the user the benefit of obtaining optimal solutions while revealing the impact of uncertainties on system performance. Our results indicate that demand uncertainty has the greatest negative impact on performance for the supply chain that we modelled in this study, emphasising the importance of effective forecasting. The relative importance of supply and lead-time uncertainties varies according to the performance measures. While our results are valid for the specific supply chain and the operating environment we modelled, our study emphasises the importance of the ability to model supply chains realistically to obtain valid and useful results.     

The impact of supply chain relationships and integration on innovative capabilities and manufacturing performance: the perspective of rapidly developing countries

The purpose of this research is to investigate the relationships between supply chain relationships/integration, innovative capabilities and manufacturing performance. The study adopts Institutional Theory and Resource-Based View Theory to assess relationships in 171 organisations drawn from three rapidly developing countries – Brazil, India and China. Data were collected using the International Manufacturing Strategy Survey (IMSS VI) and analysed using structural equation modelling. The study found that supply chain relationships and integration relate positively to both product and process innovative capabilities. The study also found that both product and process innovative capabilities relate positively to manufacturing performance. Furthermore, there was a positive relationship between product innovative capabilities and process innovative capabilities. The findings provide new insights into manufacturers in the three countries and show that the relationships they build with their customers have encouraged them to develop new innovative capabilities. These new capabilities, in turn, have enabled them to reap benefits of improved manufacturing performance.