1,721,110 research outputs found
Tecnica della scorta di sicurezza virtuale: applicazione al caso dei grandi elettrodomestici nella grande distribuzione organizzata
No full textLa scorta ricopre un ruolo strategico all’interno della gestione
dei sistemi produttivi, in primo luogo poiché è una variabile cri-
tica su cui si può agire per complementare la carenza di tempo
e capacità produttiva, in secondo luogo perché al mantenimen-
to di materiali a scorta è associato un costo, che auspicabilmen-
te dovrebbe essere ridotto. In contesti con grande aleatorietà
della domanda, gli alti livelli di scorta di sicurezza comportano
spesso un problema, che può essere efficacemente affrontato e
risolto con la tecnica della virtualizzazione della scorta di sicu-
rezza. In questo articolo viene presentata una applicazione
della tecnica della scorta di sicurezza virtuale a un caso nella
grande distribuzione organizzata
A model for R&D project management: how does the number of teams influence the project performance?
No full textDetermining the optimal number of team members in projects is a key factor in Project Management. The choices
related to projects’ team dimensions are usually based upon the Project Managers’ previous experience and it
presents itself with little structure, as it is believed that the structural approach does not take into account immaterial
aspects, such as creativity, which is difficult to measure and therefore hard to manage.
In such a context, the aim of this paper is to provide project managers with guidelines useful to determine the ideal
dimensions of a project team along the lines of a formal approach and it does so by considering how numerosity
may affect the effort of coordination and communication among members, production capacity and creative skills,
especially when the latter constitutes an essential factor, as in Research and Development (R&D) projects.
To this aim a model is put forward which presents itself quite straightforwardly from the mathematical point of view
and the results of which can be easily interpreted. An effort has been made to reduce to a minimum the number of
free parameters, which might arbitrarily characterize th functions utilized. Therefore, on the only free parameter a
Sensitivity Analysis has been conducted which has shown a certain robustness of the model, thus allowing to get to
interesting conclusions about the determination of the ideal dimensions of a project team engaged in Research and
Development activities
Revised MRP for reducing inventory level and smoothing order releases: a case in manufacturing industry
No full textAlthough material requirement planning (MRP) systems are widely used in manufacturing companies, they exhibit significant drawbacks. Rev MRP algorithm has been developed in order to reduce the system nervousness, generate a more regular pattern of order released and lower inventory levels. The aim of this paper is to test the Rev MRP algorithm on the case of one of the largest Italian manufacturing companies of home appliances. The company provided three sets of real data, referring to three different runs of their MRP. Results showed that the Rev MRP outperformed the company’s MRP smoothing the production order releases, eliminating overshoots and drastically reducing the inventory levels along the supply chain, even in case of frequent forecasts updates
Analyses on rapeseed yield in China based on the prediction of yield potential
No full textThe maximum yield growth range of per unit rapeseed yield in China is analyzed from three aspects including photosynthesis production potential of rapeseed, the changing trend of per unit rapeseed in the previous years and potential of distribution area agricultural crops. In the paper, the potential of using light, the external potential of historical yield evolution trend and AEZ (agricultural ecological zone) are applied to calculate the per unit yield potential of Chinese rapeseed. The results show that the maximum growth range of per unit yield in different stages was different. It can be reasonably predicted the future products according to the past yield of rapeseed and its growth rate. Any variety of rapeseed and planting technology higher than above the growth range can only be promoted in restricted area or has the statistical error. The results are of reference significance to sustainable production of Chinese rapeseed
Miglioramento di sicurezza e manutenibilità di macchine operatrici. Proposta di un modello per la verifica di conformità e performance
No full textUtilizzo di tecniche di simulazione per l’analisi delle prestazioni di risorse di produzione utilizzate in attività di customer support
No full textL’introduzione di nuovi sistemi software di gestione dati e simulazione di processo generano nelle realtà industriali in cui essi vengono introdotti una duplice difficoltà. Da un lato nasce la necessità di doversi interfacciare con strumenti nuovi dalle potenzialità ignote, dall’altro l’utilizzo di dati che questi sistemi richiedono crea la necessità di organizzarli in modo razionale e strutturato. Necessità che se da un lato rispondono a criticità che i nuovi strumenti introducono nel sistema dall’altro costituiscono un punto di forza in quanto rendono indispensabile una più approfondita conoscenza del processo, costituendo uno spunto importante per rilevare lo scostamento tra l’as is e il to be.
Il lavoro descritto nel seguente articolo è parte di un progetto che si pone come obiettivo l’analisi delle prestazioni di un sistema manifatturiero complesso operante su commessa nel comporto dell’industria aerospaziale. La complessità del sistema è determinata da fattori critici oggetto del presente studio. In particolare l’elevato numero di item che attraversano il sistema in esame ha reso necessario individuare e classificare, secondo opportuni criteri di peso, gli elementi che possono contemporaneamente essere presenti all’interno del centro. Secondo punto critico è il particolare sistema logistico di supporto al cliente realizzato dal centro. Esso è caratterizzato da un sistema di tipo custumer logistic support che prevede la riparazione degli item danneggiati, entro precisi orizzonti temporali stabiliti in fase di sottoscrizione del contratto di supporto logistico o, nei casi in cui l’item danneggiato sia di fondamentale importanza per l’apparato di cui è parte integrante, la sostituzione dello stesso fino all’effettiva riparazione. Una ulteriore complessità nasce dalla condivisione di risorse e skill tra l’area deputata alla produzione e quella dedicata alle riparazioni.
L’analisi effettuata si avvale dell’utilizzo di strumenti di business process management che vedono integrati motori di simulazione. L’approccio simulativo ha permesso da un lato di valutare l’impatto delle variazione del piano di produzione sul tempo medio di attraversamento degli item in riparazione, dall’altro di capire come una diversa allocazione delle risorse consente una migliore saturazione del centro nonchè le dinamiche di interazione degli item di riparazione con quelli di produzione
Estimating projects duration in uncertain environments: Monte Carlo simulations strike back
Full text linkPERT (Program Evaluation and Review Technique), developed in the 1950’s, represented the first attempt to
incorporate uncertainty in project scheduling. Despite some weaknesses, it is still widely used in project
management mostly thanks to the simplicity of its algorithm in operating on activity network diagrams. Today the
increasing complexity of projects requires new techniques and the increasing availability of computer power have
not brought project simulation into common usage as expected. Although several reviews assert that simulative
approach has already superseded PERT when coping with uncertain environment; the reason why it is not diffused
is that simulations require a too long computing time. In this paper we show through an algorithm and experimental
results that the computational time, historically the major drawback of Monte Carlo simulations, is definitely
minimum thanks also to the computational power available nowadays. We present results of an efficient program
made of few lines of code and able to compute the completion time of a network activity diagram with 100.000
activities and about 50.000.000 precedence constraints between them
Quality issues impacting production planning
Full text linkAmong the various problems affecting production processes, the unpredictability of quality factors is one of the main issues which concern manufacturing enterprises. In make-to-order or in perishable good
production systems, the gap between expected and real output quality increases product cost mainly in two different ways: through the costs of extra production or reworks due to the presence of non-compliant items
and through the costs originating from inefficient planning and the need of unscheduled machine changeovers. While the first are relatively easy to compute, even ex-ante, the latter are much more difficult to estimate because they depend on several planning variables such as lot size, sequencing, deliveries due dates, etc. This paper specifically addresses this problem in a make-to-order multi-product customized production system; here, the enterprise diversifies each production lot due to the fact that each order is based on the
customer specific requirements and it is unique (in example, packaging or textiles and apparel industry). In these contexts, using a rule-of-thumb in overestimating the input size may cause high costs because all the
excess production will generate little or no revenues on top of contributing to increasing wastes in general. On the other hand, the underestimation of the lots size is associated to the eventual need of launching a new, typically very small production order, thus a single product will bear twice the changeover costs. With little markups, it may happen that these extra costs can reduce profit to zero. Aim of this paper is to provide a critical analysis of the literature state-of-art while introducing some elements that can help the definition of lot-sizing policies considering poor quality costs
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