Search results for "Operations Research"
showing 10 items of 1297 documents
Demand Sharing Inaccuracies in Supply Chains: A Simulation Study
2018
We investigate two main sources of information inaccuracies (i.e., errors and delays) in demand information sharing along the supply chain (SC). Firstly, we perform a systematic literature review on inaccuracy in demand information sharing and its impact on supply chain dynamics. Secondly, we model several SC settings using system dynamics and assess the impact of such information inaccuracies on SC performance. More specifically, we study the impact of four factors (i.e., demand error, demand delay, demand variability, and average lead times) using three SC dynamic performance indicators (i.e., bullwhip effect, inventory variability, and average inventory). The results suggest that demand …
Advanced Control and Optimization with Applications to Complex Automotive Systems
2014
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://10.1155/2014/183580
A Probabilistic Analysis to Quantify the Effect of March 11, 2004, Attacks in Madrid on the March 14 Elections in Spain: A Dynamic Modelling Approach
2015
[EN] The bomb attacks in Madrid three days before the general elections of March 14, 2004, and their possible influence on the victory of PSOE (Spanish Workers Socialist Party), defeating PP (Popular Party), have been a matter of study from several points of view (i.e., sociological, political, or statistical). In this paper, we present a dynamic model based on a system of differential equations such that it, using data from Spanish CIS (National Center of Sociological Research), describes the evolution of voting intention of the Spanish people over time. Using this model, we conclude that the probability is very low that the PSOE would have won had the attack not happened.Moreover, after t…
Multiple criteria assessment of methods for forecasting building thermal energy demand
2020
Abstract Nowadays worldwide directives have focused the attention on improving energy efficiency in the building sector. The research of models able to predict the energy consumption from the first design and energy planning phase is conducted to improve building sustainability. Use of traditional forecasting tools for building thermal energy demand tends to encounter difficulties relevant to the amount of data required, implementation of the models, computational costs and inability to generalize the output. Therefore, many studies focused on the research and development of alternative resolution methods, but the choice of the most convenient is not clear and simple. Single comparison of s…
Unbiased sensitivity analysis and pruning techniques in neural networks for surface ozone modelling
2005
Abstract This paper presents the use of artificial neural networks (ANNs) for surface ozone modelling. Due to the usual non-linear nature of problems in ecology, the use of ANNs has proven to be a common practice in this field. Nevertheless, few efforts have been made to acquire knowledge about the problems by analysing the useful, but often complex, input–output mapping performed by these models. In fact, researchers are not only interested in accurate methods but also in understandable models. In the present paper, we propose a methodology to extract the governing rules of trained ANN which, in turn, yields simplified models by using unbiased sensitivity and pruning techniques. Our propos…
Human factor policy testing in the sequencing of manual mixed model assembly lines
2004
In this paper the human resource management in manual mixed model assembly U-lines is considered. The objective is to minimise the total conveyor stoppage time to achieve the full efficiency of the line. A model, that includes effects of the human resource, was developed in order to evaluate human factor policies impact on the optimal solution of this line sequencing problem. Different human resource management policies are introduced to cope with the particular layout of the proposed line. Several examples have been proposed to investigate the effects of line dimensions on the proposed management policies. The examples have been solved through a genetic algorithm. The obtained results conf…
Introduction to the Special Section on Temporal Change Observation for Bio-Geophysical Parameters
2011
The nine papers in this special section are contributions from the AgriSAR-2006 Campaign Workshop, held at ESA-ESTEC, Noordwijk, The Netherlands, in October 2008.
IWAL–An Interactive Weather Analysis Laboratory
2015
Abstract Complementary key elements of meteorological education are the provision of a thorough theoretical understanding of the physical laws governing atmospheric motions, and the hands-on investigation and visualization of specific weather systems. However, the latter task is technically challenging, because specific skills must be acquired for flexibly handling meteorological data. Some examples are superimposing satellite pictures and reanalysis fields, producing an isentropic potential vorticity (PV) map, and visualizing a vertical section across a flow feature of interest. Although learning these technical issues has its own merits, it can distract students from investigating the com…
Using continuous user authentication to detect masqueraders
2003
Nowadays computer and network intrusions have become more common and more complicated, challenging the intrusion detection systems. Also, network traffic has been constantly increasing. As a consequence, the amount of data to be processed by an intrusion detection system has been growing, making it difficult to efficiently detect intrusions online. Proposes an approach for continuous user authentication based on the user’s behaviour, aiming at development of an efficient and portable anomaly intrusion detection system. A prototype of a host‐based intrusion detection system was built. It detects masqueraders by comparing the current user behaviour with his/her stored behavioural model. The m…
Analysis of the authors’ rights collection frontier using PCA-MDEA: an application to the Valencia region
2002
The aim of this paper is to estimate the authors’ rights collection frontier within the collection zones into which the Valencia Region (Spain) has been divided. To be more exact, a nonparametric frontier technique (Modified Data Envelopment Analysis, MDEA) and the Principal Components Analysis (PCA) are jointly employed to map out an initial approach to the potential authors’ rights collection within this region (as divided into collection zones). The analysis has been carried out both jointly and by majority sectors (performing, musical, and audio-visual arts). Publicaciones Econcult: Área de Investigación en Economía de la Cultura y Turismo. Universitat de València