1,721,016 research outputs found
Les objectifs de qualité urbaine et de sécurité routière dans la planification de la mobilité: deux visions differèntes à travers le Plan urbain de trafic (PUT) de Brescia et le Plan de déplacements urbains (PDU) d’Aix-en-Provence
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Optimal sampling techniques in off-line quality control
No full textThis paper addresses the problem of quality control for manufacturing environments. The quality control station is placed in an off-line position, i.e. external to the item flow. This layout is mandatory when the station is unable (because of costs and times) to inspect the whole set of items produced. The aim of the present study is to describe and evaluate how the limited capacity of the quality control station affects the efficiency of the connected production system and how the service time of the inspection station may be profitably managed as a further variable of the quality inspection process. Optimal policies for both random and deterministic sampling techniques are determined and compared
Queuing Theory-Based Design Methods for the Definition of Power Requirements in Manufacturing Systems
Full text linkThe attention paid to energy consumption is growing steadily due to the costs associated with energy usage as well as the resulting environmental impacts. This work proposes an analytical method to assess the energy consumption and the power requirements of a productive system. By exploiting queuing theory, it is possible to achieve a probabilistic view of energy consumption. This method is useful to define the contractual power level and calculate the service level associated with it, so it is applicable as a decision-support tool during the design of productive systems when it is not possible to obtain field data (green-field design). Three different models characterised by an increasing degree of complexity were exploited. The three models share the feature of an infinite number of servers, while the increasing complexity is due to the introduction of batch arrivals and the variability of the size of the arrival lot. A connection is made between production variables and power used by machines to consider energy consumption. A numerical example shows the applicability of the method and highlights the different results obtained through the three models. In addition, analytical formulations are available for all three proposed models; thus, no simulation process is needed
Experiences and issues in evaluating tool requirements using genetic algorithms
No full textThis paper is concerned with the optimization of tool requirements in flexible manufacturing systems (FMSs). The main aim is to determine the best tool spectrum (i.e. the number of duplicates for each tool type to be provided) considering different layouts of the tool management area (tool rooms). The optimization method is based on the reciprocal interaction between a genetic algorithm (GA) and the simulation model of the FMS considered. Thus, the results proposed refer to the efficacy of the technique adopted and its practical application to tool management
Supply chain finance for ameliorating and deteriorating products: a systematic literature review
Full text linkAmeliorating and deteriorating products, or, more generally, items that change value over time, present a high sensitiveness to the surrounding environment (e.g., temperature, humidity, and light intensity). For this reason, they should be properly stored along the supply chain to guarantee the desired quality to the consumers. Specifically, ameliorating items face an increase in value if there are stored for longer periods, which can lead to higher selling price. At the same time, the costumers’ demand is sensitive to the price (i.e., the higher the selling price the lower the final demand), sensitiveness that is related to the quality of the products (i.e., lower sensitiveness for high-quality products). On the contrary, deteriorating items lose quality and value over time which result in revenue losses due to lost sales or reduced selling price. Since these products need to be properly stored (i.e., usually in temperature- and humidity-controlled warehouses) the holding costs, which comprise also the energy costs, may be particularly relevant impacting on the economic, environmental, and social sustainability of the supply chain. Furthermore, due to the recent economic crisis, companies (especially, small and medium enterprises) face payment difficulties of customers and high volatility of resources prices. This increases the risk of insolvency and on the other hand the financing needs. In this context, supply chain finance emerged as a mean for efficiency by coordinating the financial flow and providing a set of financial schemes aiming at optimizing accounts payable and receivable along the supply chain. The aim of the present study is thus to investigate through a systematic literature review the two main themes presented (i.e., inventory management models for products that change value over time, and financial techniques and strategies to support companies in inventory management) to understand if any financial technique has been studied for supporting the management of this class of products and to verify the existing literature gap
Reducing energy costs in IT infrastructure: The case study of the University of Brescia
No full textIn the next future, the IT (Information Technology) infrastructures will increase due to the development in manufacturing management. The “Manufacturing 4.0” program advises that the IT infrastructures will grow, maybe differently, in every company. Consequently, the IT infrastructure costs will increase considerably and the related
energy requirements and costs will increase, too. The aim of this paper is to apply an energy-economic analysis to evaluate the impact that the improvement of energy efficiency at the server rooms of the University of Brescia have had on the IT costs. To do that, an energy audit was performed before the IT improvement actions, as well as an energy audit after their implementations. At first, an economic analysis have shown the savings reached, based on the NPV (Net Present Value) and PBT (Pay Back Time) analyses. Successively, the PUE, Power Usage Effectiveness, has been evaluated, so as to appreciate the impact of the energy improvement actions on the performance of the server rooms. To make the PUE value comparable between the previews and the current configuration of server rooms of the University, a metric is provided. Finally, the DCIE, Data Centre Infrastructure Efficiency, is calculated and discussed
Ottimizzazione dell'utilizzo delle biomasse residuali di lavorazione nel settore del compensato di pioppo
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