Search results for "Operations Research"
showing 10 items of 1297 documents
Assessment of data availability influence on integrated urban drainage modelling uncertainty
2009
In urban water quality management, several models are connected and integrated for analysing the fate of pollutants from the sources in the urban catchment to the final recipient; classical problems connected with the selection and calibration of parameters are amplified by the complexity of the modelling approach increasing their uncertainty. The present paper aims at studying the influence of reductions in available data on the modelling response uncertainty with respect to the different integrated modelling outputs (both considering quantity and quality variables). At this scope, a parsimonious integrated home-made model has been used allowing for analysing the combinative effect of data…
Control points deployment in an Intelligent Transportation System for monitoring inter-urban network roadway
2022
Abstract The constant evolution of transportation systems and traffic in developing countries is nowadays confronted with a problem of road safety and therefore of a high accident rate, especially in the context of inter-urban road transport. In this work, we propose a communication architecture for an Intelligent Transport System (ITS) to provide surveillance in an inter-urban transport network in the context of developing countries. We introduce two types of control points: Relay Control Points (RCP) and Treatment Control Points (TrCP). We also designed two multi-objective models for the deployment of these points. In order to ensure good coverage, to minimize the cost of installation and…
Heuristics for a Real-World Mail Delivery Problem
2011
We are solving a mail delivery problem by combining exact and heuristic methods. The problem is a tactical routing problem as routes for all postpersons have to be planned in advance for a period of several months. As for many other routing problems, the task is to construct a set of feasible routes serving each customer exactly once at minimum cost. Four different modes (car, moped, bicycle, and walking) are available, but not all customers are accessible by all modes. Thus, the problem is characterized by three interdependent decisions: the clustering of customers into districts, the choice of a mode for each district, and the routing of the postperson through its district. We present a t…
Job seeker's spatial equilibrium in a fuzzy mathematical framework
1990
This paper incorporates complex behavior in a job seeking strategy model. Since the state of information is imperfect, a job seeker faces an imprecise labor market. His behavior is fuzzy and variable. It is shown how this complex behavior can be described by fuzzy subsets theory and bifurcation analysis. The latter examines the discontinuous phenomena. Then it is proved that a job seeker’s fuzzy equilibrium with a spatial constraint exists.
New development opportunities for the craft brewing segment: the case study of a micro-malthouse
2017
In Italy in the past few years, the number of small breweries penetrating the craft beer sector has grown exponentially. Craft producers intend to give a strong added value and a local character to their production in different ways. One of these is the use of malt derived from small batches of local cereals and pseudo cereals. The aim of this study is the assessment of investment profitability, through a cost-benefit analysis (CBA), for a compact and a modular micro-malting plant in Sicily (Southern Italy). The CBA for a micro-malthouse was carried out considering both installation and operating costs. Net present value (NPV), discounted benefit-cost ratio (DBCR) and internal rate of retur…
Pricing and infrastructure fees in shaping cooperation in a model of high-speed rail and airline competition
2020
Abstract This paper studies the effects of cooperation in a hub-and-spoke network with high-speed rail and airline competition. The distinctive elements of our analysis are the consideration of: (i) per-passenger airport and rail infrastructure fees; (ii) mixed bundling pricing by partners, and (iii) an airline duopoly in the international market. We show that partners fix the cheapest bundle price of the combined trip, that non-allied operators respond by decreasing the prices per link, and that connecting traffic increases. Per-passenger fees significantly affect the price differences following cooperation. An empirical application confirms that it is privately profitable and that welfare…
The CINHEKS Research Design: Taking Stock and Moving Forward
2016
Comparative research design, at its best, in an international project focused on a complex topic, is a dynamic, iterative and on-going process. In the CINHEKS study this proved to be the case, both by design and in several ways our team did not, nor could not, anticipate. The tensions between purposeful planning, inevitable setbacks and serendipity turned out to be one of the most interesting aspects of CINHEKS and the purpose of this chapter is to take a step back, well outside methodological convention, to holistically and critically reflect on the lessons learned during the planning and execution of the CINHEKS comparative study. This chapter is an analysis of our efforts regarding the c…
An Urbanistic Project Based on General Systems Theory
1991
This paper intends to be an outline of the Urbanistic Development Planning of the Valencian Community in Spain to be performed during the years 1991 to 1993, The following are considered as objectives of the Planning: – Quality of Life improvement, – protection of Nature, – rational management of natural resources, – rational use of land; all based on social demand. The territory and the mechanism of intervention is considered as a system whose elements can be grouped as: – uses of land, – infrastructure, equipment, services, – objectives, – intervention and management. The Planning proposes itself to be: integral, strategic, prospective, programmed, controllable and participative, A simula…
A New Dynamic Model for Anticipatory Adaptive Control of Airline Seat Reservation via Order Statistics of Cumulative Customer Demand
2017
This paper deals with dynamic anticipatory adaptive control of airline seat reservation for the stochastic customer demand that occurs over time T before the flight is scheduled to depart. It is assumed that time T is divided into m periods, namely a full fare period and m−1 discounted fare periods. The fare structure is given. An airplane has a seat capacity of U. For the sake of simplicity, but without loss of generality, we consider (for illustration) the case of nonstop flight with two fare classes (business and economy). The proposed policies of the airline seat inventory control are based on the use of order statistics of cumulative customer demand, which have such properties as bivar…
On the Bullwhip Avoidance Phase: supply chain collaboration and order smoothing
2009
This paper provides an assessment of the impact of collaboration and smoothing replenishment rules on supply chain operational performance and customer service level. Three supply chain configurations (i.e. Traditional, Information Exchange and Synchronised) in which orders are generated by smoothing (S, R) inventory control policies are studied for different proportional controllers. A supply chain stress test is performed through a sudden and intense change in demand. A structured and extended supply chain assessment framework is adopted. The main conclusions of this paper are the following. (i) The impact of Supply Chain Collaboration on overall supply chain performance is greater than t…