汽车和新型产业装备的应用于制造.doc

Scheduling of manufacturing systems under dual-resource constraints using genetic algorithmsOriginal Research ArticleJournal of Manufacturing SystemsScheduling belongs to the special class of NP-hard problems for which no polynomial time algorithm has been found. Therefore, a schedule that is the best possible near-optimal solution is often acceptable. This paper presents a scheduling approach, based on Genetic Algorithms (GAs), developed to address the scheduling problem in manufacturing systems constrained by both machines and workers. This genetic algorithm utilizes a new chromosome representation, which takes into account machine and worker assignments to jobs. A set of experiments for determining the best staffing level and machine and worker assignment to jobs was performed. A study was conducted using dispatching rules with various performance measures for two types of shop characteristics: (i) dual-resource (machines and workers) constrained, and (ii) single-resource constrained (machines only). An example is used for illustration and comparison. The resulting scheduling methodology is capable of determining the best staffing level and dispatching rules for the chosen performance measure in both single and dual-resource constrained shops. Decisions to adopt the prescribed staffing strategy to improve the primary performance measures such as mean flow time, mean tardiness, and mean waiting time must be balanced by managers against the potential increase in direct cost. The developed scheduling approach and formulation proved to be very useful for optimizing production performance under the realistic conditions imposed by both machine and worker availability constraints. Such a tool should be used to define a priori the best dispatching rules and schedules for a given set of production requirements and objectives.Microbial contamination of food refrigeration equipmentOriginal Research ArticleJournal of Food EngineeringRefrigeration systems in chilled rooms in 15 plants processing a variety of foods were studied. These included plants processing raw meat and salads, Chinese ready meals, dairy products, slicing and packing of cooked meats and catering establishments. An initial survey of total numbers of microbes at a total of 891 sites on evaporators, drip trays and chilled room walls was followed up with a more detailed examination of 336 sites with high counts, selecting for Listeria spp., coliforms, enterococci, Staphylococcus aureus and Bacillus cereus. Temperatures (particularly air on and air off, maximum and near defrost heaters) relative humidity, airflow, layout and cleaning regimes were surveyed. In general, no correlation could be found between any of the physical measurements and the numbers and types of bacteria detected. Maximum mean temperatures in the chilled rooms varied from 1 to +16.9 C and few chilled units were regularly cleaned. Twenty five percent of sites examined had more than 105 colony-forming units per cm2, although, very few pathogens or faecal indicator bacteria were detected. Listeria spp. were not found and coliforms were found only once, in low numbers. Low numbers of S. aureus or B. cereus were present in 9 of the 15 plants, B. cereus was found on evaporators and associated drip trays in two catering plants and two plants processing cooked meat. Enterococci and S. aureus were found most frequently in a raw red meat slaughterhouse (always in low numbers). In general, microbial contamination was lower in rooms where wrapped rather than unwrapped products were stored. The type of product also affected the degree of contamination, with raw red meat and poultry or dry ingredients giving highest counts, and raw vegetables and cooked products lowest. The work demonstrated that bacteria were present on evaporator cooling coils in all factory cold rooms visited. Although evaporator-cleaning procedures were carried out in some factories as part of routine maintenance these were not shown to be effective at maintaining low levels of bacteria on evaporators. To maintain evaporator hygiene it is suggested that more regular cleaning procedures, possibly by means of automated cleansing systems, should be considered.Article Outline1. Introduction2. Materials and methods 2.1. Physical measurements2.2. Microbiological sampling3. Results 3.1. Total viable counts (TVC)3.2. Specific bacteria3.3. Effect of temperature, relative humidity and air velocity3.4. Cleaning procedures4. DiscussionAcknowledgementsReferencesRDF production plants: I Design and costsOriginal Research ArticleApplied Thermal EngineeringMunicipal solid waste (MSW) management calls for the integration of different recovery, recycling and disposal technologies. Among these possible options, MSW may be treated in order to obtain a fuel to be sold to third party users or directly utilized to generate electricity provided it is of sufficient quality to be employed instead of traditional fuels. In this two-part paper the problem of producing refuse derived fuel (RDF) having a high heating value (LHV4000 kcal/kg) has been examined from a technical and economic viewpoint. In the first part article a technical assessment of production plants is carried out. Different production lines have been thus compared in terms of mass efficiency, heating value of produced RDF and treatment cost highlighting how the choice of process equipment affects the system performances. As a result the process plant configurations enabling to meet the required product specifications are identified. The influence of mixing a high calorific waste such as scrap tires with the stream of household waste, in the limits allowed by current regulation, has been also analyzed and found to be a prerequisite to meet the prescribed heating value target. Economic feasibility and financial risk of RDF production plants have been successively evaluated in the second part article over a capacity range of 25200 t/h considering also integrated facilities including compost production and/or electricity generation. The analysis has been carried out with reference to the current Italian market scenario even if it has a general applicability and its relevance is wider geographically.Fuzzy controls for maintenance scheduling in transportation systemsOriginal Research ArticleAutomaticaScheduling of periodic maintenance for transportation equipment can often be accomplished by controlling the utilization of individual vehicles. Because of many random effects and due to the complexity of most schedules it is virtually impossible to achieve a precise match between the prescribed and the actual utilization for each vehicle. Instead of asking the dispatcher to do the impossible, the approach described in this paper prescribes only fuzzy targets for vehicle utilization. A feedback loop adjusts the targets periodically based on the actual utilization. A second feedback loop monitors the general performance of the dispatcher and provides a basis for self-learning features of the system. Experimental results about the effectiveness of the fuzzy controls are reported.经典的运输管理算法Manufacturing lead-time rules: Customer retention versus tardiness costsOriginal Research ArticleEuropean Journal of Operational ResearchA systematic approach for product families formation in Reconfigurable Manufacturing SystemsOriginal Research ArticleRobotics and Computer-Integrated ManufacturingModeling and specifications of dynamic agents in fractal manufacturing systemsOriginal Research ArticleComputers in IndustryIterative methods for manufacturing systems of two stations in tandemOriginal Research ArticleApplied Mathematics LettersWaiting line model applications in manufacturingOriginal Research ArticleInternational Journal of Production EconomicsProduct mix variability with correlated demand in two-stage food manufacturing with intermediate storageOriginal Research ArticleInternational Journal of Production EconomicsA Unified Manufacturing Resource Model for representing CNC machining systemsOriginal Research ArticleRobotics and Computer-Integrated ManufacturingElectronic waste recycling: A review of U.S. infrastructure and technology optionsOriginal Research ArticleResources, Conservation and RecyclingExact analysis of the joint production quantity-quality of a two-station stable tandem manufacturing system with restricted capacityOriginal Research ArticleComputers & Mathematics with ApplicationsA critical review of syngas cleaning technologies fundamental limitations and practical problemsOriginal Research ArticlePowder TechnologyGraphical abstractA robust and completely reliable syngas cleaning technology has not been developed especially for gas cleaning over 600C to achieve higher efficiencies. This paper presents a brief summary of the current status, certain fundamental limitations and practical problems of the conventional gas cleaning technology. Recommendations are also made to overcome these fundamental limitations and practical problems.先进制造技术与绿色产业的发展Queueing theory in manufacturing systems analysis and design: A classification of models for production and transfer linesReview ArticleEuropean Journal of Operational ResearchIntegrating manufacturing and logistic systems along global supply chainsOriginal Research ArticleCIRP Journal of Manufacturing Science and TechnologyIn present manufacturing systems information concerning logistic capabilities and employment level are not appropriately utilised to determine most effective production plans. Therefore, cost and lead-time savings obtained with new global strategies might be impaired due to unbalanced and unstable integration of manufacturing and logistics. This paper proposes a framework for investigating interfaces between manufacturing and logistic systems along global supply chains. As first steps, a mathematical program of the integrated scheduling problem is developed and tested. Obtained results and the limited size of computationally manageable scenarios are both motivation and starting point for the development of forthcoming heuristics.Article Outline1. Introduction2. Global manufacturing chains3. Integration of production and logistics 3.1. Production and transport scheduling problem3.2. Collaborative planning4. Enabling collaboration5. Investigative framework 5.1. Adaptation of PTSP 5.1.1. Nomenclature: