1,721,320 research outputs found
Energy saving in case of intermittent production by retrofitting service plants systems through inverter technology: a feasibility study
Full text linkMany production machines have high energy consumption due to the large number of electrical motors used to rotate equipment, such as tools, fans and pumps. Moreover, in different industrial sectors production is not continuous but intermittent, where working times alternate with idle times. During idle times continuous switch off is not always possible due to technical limitations, and if it is possible, it can cause higher energy consumption due to peak current at the start-up of the electrical motors. The purpose of this paper is to introduce the possibility of managing intermittent production using inverter technology. The inverter provides power control by managing the frequency and voltage of the power supplied to the alternating current motors. The study analyses the potential energy consumption reduction as a function of the production parameters (number of daily stops, average working time, etc.) and develops a feasibility analysis, its related investment cost and its potential energy consumption reduction. As a result, the proposed feasibility study defines the set of production parameters and the types of equipment for which this technology is suitable, bringing rapid investment payback. The proposed feasibility analysis is validated by an industrial case study related to a tannery spray plan
Energy saving in operations management through variable-speed drive technology: environmental versus economic convenience
No full textCO2 emissions are mainly due to electricity generation. The
percentage of electrical energy used within industry rises up to 70% in
industrialised countries and electrical motors use the greatest part. Due to the
high degree of flexibility required in production systems, the classical on-off
control system causes large energy losses due to mismatches between the
output power of fixed-speed motors and the mechanical power demands of the
electromechanical system. Variable-speed drive (VSD) systems, developed
through the inverter-fed alternating current technology, are identified as the
motor system technology with the most significant energy-saving potential. The
purpose of this paper is to analyse and compare both the economic and the
environmental benefits related to the potential retrofitting of existing
production systems managed using the traditional on-off control according to
different variable typologies: the flexibility requirement variables, the
production system variables and the variables related to the specific country
considered. As a result, the paper identifies the relation between the two
economic and environmental objectives according to the analysed variables.
Two company cases are reported in order to demonstrate both the economic
and the environmental benefits of applying the VSD technology to existing
production systems
Analytical and Numerical Modeling of AS/RS Cycle Time in Class-Based Storage Warehousing
No full textThis work presents an analytical model for the computation of travel time for Automated Storage and Retrieval Systems (AS/RS) with a three (ABC) class based storage in a rectangular in time warehouse. In particular, the authors provide a method for the analytical closed form evaluation of the expected mean travel time for the single/dual command cycles in the configuration with the input/output located in the bottom/left corner of the warehouse and varying the ABC curve.
A numerical simulation analysis adopting a numerical modeling has been developed, in order to validate the proposed model accordingly with a multi scenario analysis. The performance of the system obtained by the adoption of the proposed analytical travel time models under different configurations of the warehousing system (shape and dimension of the classes, ABC curve), have been evaluated and discussed
A new approach to the automatic analysis and control of material handling systems: Integrated Layout Flow Analysis (ILFA)
No full textIn the majority of small and medium sized enterprises (SEMs), the direct costs of material handling cannot be clearly measured. There are several reasons for this, including the large number of product types, complexity of their production cycle, and continuous change in markets. Therefore, production managers require flexible tools to create a suitable material handling system model which explicitly and rapidly calculates the indices required as these are traditionally neglected or laboriously approximated, (i.e., time and cost in material flow inside the factory, storage area requirements, and MH utilization percentage). This paper proposes an integrated approach to analyzing and controlling material handling operations in an industrial manufacturing plant from a “full quantitative” point of view. The model presented unites quite different fields of research into a unique methodology. This material handling model rapidly and automatically provides production managers with extensive and significant information. As a result, integrated layout flow analysis interrelates systematic layout planning with operational research algorithms and visual interactive simulation, using a complete software platform to implement them. This integrated layout flow analysis approach focuses on determining the space requirement for manufacturing department buffers, the transportation system requirements, the performance indices, and the time and cost of material flows spent in the layout and in MH traffic jams
La gestione efficiente del materiale ospedaliero: il Just-In-Time ed il Kanban
No full textIl Settore Ospedaliero è stato ed è tuttora in continua trasformazione dal punto di vista della gestione delle risorse ad esso dedicate. L’evoluzione della politica italiana in tema di Sanità ha subito un grosso impulso con il D.Lgs. 502 del dicembre ’92 che ha portato alla cosiddetta aziendalizzazione degli Ospedali pubblici costringendo i gruppi dirigenti delle Aziende Ospedaliere a prestare maggiore attenzione alle modalità d’impiego delle proprie risorse. Gli investimenti in materiali di consumo e la loro gestione pesano notevolmente sul bilancio aziendale e da questa osservazione è nata l’esigenza di implementare nuovi sistemi di gestione delle scorte.
In tale contesto si inserisce la sperimentazione che questo lavoro vuole presentare: la ricerca che viene proposta riguarda la progettazione e la sperimentazione di un innovativo modello di riapprovvigionamento automatico di prodotti nei reparti ospedalieri basato sulla logica Just in Time. La prototipazione è stata sviluppata in alcuni reparti dell’Azienda Ospedaliera di Padova rappresentativi per le varie categorie e significativi per tipo di attività e mole di consumi. I risultati ottenuti sono eccellenti, in quanto, a fronte di modesti investimenti limitati all'introduzione di un sistema di armadi modulari e di carrelli "intelligenti", sono diminuiti sensibilmente la varietà ed i volumi di prodotti mantenuti in reparto, le quantità di farmaci scaduti, gli errori nelle ordinazioni ed i prelievi ingiustificati. Infine, si assiste da parte del personale ospedaliero, ad un importante alleggerimento delle attività amministrative di reparto, a favore dell’attività di assistenza ai pazienti
Hierarchical approach for paced mixed-model assembly line balancing and sequencing with jolly operators
No full textIn order to increase flexibility and reduce costs, several companies adopt mixed-model assembly lines whose output
products are variations of the same basic model with specific and distinctive attributes. Unfortunately, such attributes
typically lead to variations in the task process times. In the case of un-paced buffered assembly lines, these variations
are smoothed by buffers with consequences in terms of work-in-progress, costs, space utilisation and lower productivity
control. To face such weaknesses, some companies adopt paced un-buffered assembly lines where the cycle time is
controlled by the continuous/synchronous moving of the products from the first to the last assembly station. In such
contexts, the possibility of assembling different models with different assembly times can be managed through the use
of supplementary flexible workforce. This article introduces an innovative balancing and sequencing hierarchical
approach for paced mixed-model assembly lines using supplementary flexible workforce called ‘jolly operators’. The
goals are to minimise the number of jolly operators and to limit the occurrence of work-overloads, which typically result
in out-of-the-line assembly completion. The proposed approach is preliminary validated and applied to a case study from
an Italian company assembling industrial air-dryers
Logistics Reengineering Process in a Warehouse/Order Fulfillment System: A Case Study
No full textThe logistics reengineering process (LRP) is a useful industrial engineering and management technique for achieving significant improvements in operational efficiencies for products quality services in a warehouse/order fulfillment system. In warehousing systems the picking process usually has a significant
impact on logistic performance, customer service levels and costs, hence improvement activities are attractive and important. This chapter presents the application of an LRP process in an Italian distribution company, which is a distributor of home furnishings and health care products. In particular, the proposed optimization process is focused on the Order Fulfillment Process (OFP). The main aim of this chapter is to present a methodology to make an effective analysis of an OFP system and, mainly, to present the results, opportunities and criticalities arising from its application. The benefits are significant both in terms of traveled distance savings and manpower usage reduction. These results demonstrate that ‘‘soft’’ reengineering improvements can significantly affect processes, procedures, rules and strategies, can reduce logistics costs and improve customer service levels without introducing ‘‘hard’’ improvements and system modifications, e.g. new equipment, personnel, and machinery
Kanban Number Optimisation in a Supermarket Warehouse Feeding a Mixed-Model Assembly System
No full textFollowing just-in-time principles, a growing number of manufacturers are adopting the so-called
supermarket concept. Supermarkets are decentralised storage areas scattered throughout the shopfloor that
serve as an intermediate store for parts required by nearby assembly lines. From these stores, a certain
number of handling operators deliver parts from the supermarket to, and collect empty bins from, assembly
stations. Finally, they return to the supermarket and are refilled for their next tours. The assembly stations in
such supermarket/multiple mixed-model assembly line systems are typically refilled through the constant
replacement of the consumed parts pulled by the kanban system. The aims of this paper are (i) to highlight
how the supermarket/multi-mixed assembly line system presents specific attributes that prohibit the simple
application of well-known kanban dimensioning formulations and (ii) to provide an innovative procedure to
optimally set all decision variables related to such a feeding system
New city logistics paradigm: From the "Last Mile" to the "Last 50 Miles" sustainable distribution
Full text linkThe distribution of goods in urban areas, together with private traffic flows, are
among the main sources of energy consumption, air pollution and noise. As a consequence,
in the 2000s, several EU cities started to implement logistical solutions for the sustainable
city. In this context, this study addresses the implementation of a new eco-logistic system,
which serves multiple adjacent cities by using electric vehicles to deliver goods of any type
within their urban areas. This paper describes the results of a project developed in the
province of Vicenza (northern Italy) and covering the main cities (Bassano del Grappa,
Thiene, Schio and Valdagno) in the foothills (the so-called Pedemontana Veneta zone).
The eco-logistic system aims to cover the last 50 miles of distribution (typical area of an
Italian province) with a centralised platform that performs green deliveries with electric
vehicles from/to the downtown areas. A preliminary and extensive “on field” analysis by
means of door-to-door questionnaires was conducted to identify the performance required
by the eco-logistic system. Therefore, the design of such a distribution system is performed
to assess and define the conditions that make this solution profitable from both the
economic and the environmental perspective
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