Rafael Lopez

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This paper is dedicated to a study of different extensions of the classical knapsack problem to the case when different elements of the problem formulation are subject to a degree of uncertainty described by random variables. This brings the knapsack problem into the realm of stochastic programming. Two different model formulations are proposed, based on(More)
This paper is dedicated to a study of different extensions of the classical knapsack problem to the case when different elements of the problem formulation are subject to a degree of uncertainty described by random variables. This brings the knapsack problem into the realm of stochastic programming. Four different model formulations are proposed, based on(More)
A Web Information Retrieval course is quite appealing to Computer Science students and is quite challenging from the teacher's perspective, due to the limited knowledge of IR and Web IR of the students. In this paper we present our experience teaching a mainly practical Web IR course in order to exploit the programming skills of the common Computer Science(More)
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Today, most data is unstructured and much of it is in text form. Over 90% of the data that exists today has been created in the last 2 years alone. This creates enormous issues for organisation's. While there is a wealth of information online in websites, news, social media, reports, articles, an organisation needs to be able to effectively mine, analyse(More)
In this paper, a detection strategy based on variable neighborhood search (VNS) and semidefinite relaxation of the CDMA maximum likelihood (ML) is investigated. The VNS method provides a good method for solving the ML problem while keeping the integer constraints. A SDP relaxation is used as an efficient way to generate an initial solution in a limited(More)
Reconstruction of an image (or shape or wavefront) from measurements of the derivatives of the image in two orthogonal directions is a common problem. We demonstrate how a particular reconstructor, commonly referred to as the Fried algorithm, can be used with megapixel derivative images to recover the original image. Large datasets are handled by breaking(More)
In in vitro true dry matter degradability (IVTDMD), in situ dry matter degradability, and neutral detergent fiber degradability, both in vitro (IVNDFD) and in situ (ISNDFD) techniques were used with crossbred goats to determine dry matter and neutral detergent fiber (NDF) ruminal degradability in eight forages and four industrial byproducts. Total(More)
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