Search results for "Operations Research"
showing 10 items of 1297 documents
Unravelling the rationalities of childhood cycling promotion
2022
Decrease of children’s independent mobility (CIM) has worried academics, policymakers, educators and other professionals for decades. Research and policy often emphasise that promoting children’s physically active and independent transport modes as cycling is important to achieve better public health, solve environmental challenges and increase related economic benefits. Yet, cycling promotion is not a neutral process and all promotion efforts are derived from latent notions of ‘cyclists’ and ‘cycling’. This paper discusses different rationalities of childhood cycling promotion and the representations of ‘children’ as independent ‘cyclists’ they entail. We argue that in order to efficiently…
Data-Driven Interactive Multiobjective Optimization Using a Cluster-Based Surrogate in a Discrete Decision Space
2019
In this paper, a clustering based surrogate is proposed to be used in offline data-driven multiobjective optimization to reduce the size of the optimization problem in the decision space. The surrogate is combined with an interactive multiobjective optimization approach and it is applied to forest management planning with promising results. peerReviewed
A decomposition approach for multidimensional knapsacks with family-split penalties
2022
The optimization of Multidimensional Knapsacks with Family-Split Penalties has been introduced in the literature as a variant of the more classical Multidimensional Knapsack and Multi-Knapsack problems. This problem deals with a set of items partitioned in families, and when a single item is picked to maximize the utility, then all items in its family must be picked. Items from the same family can be assigned to different knapsacks, and in this situation split penalties are paid. This problem arises in real applications in various fields. This paper proposes a new exact and fast algorithm based on a specific Combinatorial Benders Cuts scheme. An extensive experimental campaign computational…
Canonical correlation in multivariate time series analysis
1997
We analyze a class o f state space identification algorithms for time series, based on canonical correlation analysis in the ligth of recent results on stochastic systems theory calle d « subspace methods » .These can be describe as covariance estimation followed b y stochastic realization .The methods offer the major advantage o f converting the nonlinear parameter estimation phase in traditional V A R M A models identification in to the solution o f Riccati equation but introduce at the same time some no n trivial mathematical problem s related to positivity. The states o f the forward -backward innovations representation have an interpretation : Instrumental Variables estimators .
Experimental Research on Technological Parameters Optimization of Natural Gases
2015
The paper contains a modeling application with the help of factorial experiments of influence variations of some parameters of natural gases over the hourly flow delivered towards population. In order to completely and correctly draft the experiment we followed and highlighted the objective functions of the process to be analyzed, and then there were identified the factors that influence the objective function to be analyzed. In the end the experimental data was processed and solutions were proposed.
“To Own, or not to Own?” A multilevel analysis of intellectual property right policies' on academic entrepreneurship
2017
The political environment around universities has led them to create an infrastructure to manage academic inventions. While some consider that the advantages of a university entrepreneurial structure outweigh any potential negative effects, others question their detrimental effect on academic scientists’ entrepreneurial behavior. However, this debate remains unresolved as none of these two views have been fully empirically supported. Using multilevel models for a population of 2230 professors in 27 universities in Canada (82 individuals per unit on average), we test the effect of three features of institutional intellectual property right policy characteristics, namely, property rights (own…
Scatter search for an uncapacitated p-hub median problem
2015
Scatter search is a population-based method that has been shown to yield high-quality outcomes for combinatorial optimization problems. It uses strategies for combining solution vectors that have proved effective in a variety of problem settings. In this paper, we present a scatter search implementation for an NP -hard variant of the classic p-hub median problem. Specifically, we tackle the uncapacitated r-allocation p-hub median problem, which consists of minimizing the cost of transporting the traffics between nodes of a network through special facilities that act as transshipment points. This problem has a significant number of applications in practice, such as the design of transportati…
A hybrid evolution strategy for the open vehicle routing problem
2010
This paper presents a hybrid evolution strategy (ES) for solving the open vehicle routing problem (OVRP), which is a well-known combinatorial optimization problem that addresses the service of a set of customers using a homogeneous fleet of non-depot returning capacitated vehicles. The objective is to minimize the fleet size and the distance traveled. The proposed solution method manipulates a population of @m individuals using a (@m+@l)-ES; at each generation, a new intermediate population of @l offspring is produced via mutation, using arcs extracted from parent individuals. The selection and combination of arcs is dictated by a vector of strategy parameters. A multi-parent recombination …
A Population-Based Approach to the Resource-Constrained Project Scheduling Problem
2004
We present a population-based approach to the RCPSP. The procedure has two phases. The first phase handles the initial construction of a population of schedules and these are then evolved until high quality solutions are obtained. The evolution of the population is driven by the alternative application of an efficient improving procedure for locally improving the use of resources, and a mechanism for combining schedules that blends scatter search and path relinking characteristics. The objective of the second phase is to explore in depth those vicinities near the high quality schedules. Computational experiments on the standard j120 set, generated using ProGen, show that our algorithm produ…
Food Security Is None Of Your Business? Food Supply Chain Management In Support Of A Sustainable Food System
2017
Food security is the principal outcome of any given food system and it can be defined in terms of a sustainable food system where the core goal is to feed everyone sustainably, equitably and healthily. A sustainable food system addresses needs for availability, affordability and accessibility, is diverse, ecologically-sound and resilient, and builds the capabilities and skills necessary for future generations. This paper identifies the essential elements of food supply chain management in support of a sustainable food system, which ultimately enhances food security. The existing food supply chain and food system literature is synthesized in order to study the correspondence between public i…