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The original publication is available at www.springerlink.com
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The Response Time Variability Problem (RTVP) is a combinatorial optimisation problem that occurs whenever products, clients or jobs need to be sequenced so as to minimise variability in the time between the instants at which they receive... more
The Response Time Variability Problem (RTVP) is a combinatorial optimisation problem that occurs whenever products, clients or jobs need to be sequenced so as to minimise variability in the time between the instants at which they receive the necessary resources. These situations can be generalized under the following framework. A sequence is built using n symbols (that represent products, clients, jobs, ...) where symbol i (i = 1,...,n) is to occur given number di of times in the sequence (that represent the number of times that symbol i has to receive the resource). In the RTVP, the optimal solution is the sequence that minimises variability in the distances between any two consecutive copies of the same symbol. In other words, the distance between any two consecutive copies of the same symbol should be as regular as possible (ideally, constant).
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The Response Time Variability Problem (RTVP) is a scheduling problem that has recently been defined in the literature. The RTVP has a broad range of real-life applications. For example, in the automobile industry it an be used to sequence... more
The Response Time Variability Problem (RTVP) is a scheduling problem that has recently been defined in the literature. The RTVP has a broad range of real-life applications. For example, in the automobile industry it an be used to sequence the models to be produced on a mixed-model assembly line. A previous study developed a position exchange heuristic to apply to certain greedy initial sequences for the RTVP. Some mathematical programming models (MILPs) have also been tested to solve it to optimality, but the practical limit to obtaining optimal solutions is 25 units to be scheduled. This paper aims to improve the best mathematical programming model developed thus far in order to solve larger instances up to 40 units to optimality. The contribution of this paper is threefold: i) larger instances can be solved to optimality; ii) the new optimal solution of the RTVP can be used to compare the results of heuristics procedures; and iii) the importance of modelling is demonstrated, as we...
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Para resolver un ejemplar concreto de un problema de optimización combinatoria determinado se pueden utilizar algoritmos heurísticos. Cuando se dispone de varios, se debería determinar cuál de todos es el procedimiento heurístico que... more
Para resolver un ejemplar concreto de un problema de optimización combinatoria determinado se pueden utilizar algoritmos heurísticos. Cuando se dispone de varios, se debería determinar cuál de todos es el procedimiento heurístico que proporciona la mejor solución posible para aplicarlo. Una posibilidad consiste en ejecutar todos los procedimientos heurísticos diseñados y conservar la mejor solución obtenida, pero, aunque dichos algoritmos de caracterizan por ser “rápidos”, en alguna ocasión, y en condiciones industriales, el tiempo de cálculo disponible es limitado lo cual imposibilita dicha estrategia de resolución. Se proponen técnicas estadísticas que, dado un ejemplar concreto de un problema de optimización combinatoria determinado, intentan identificar cuál es el algoritmo heurístico más adecuado para su resolución: se trata de identificar loa parámetros característicos de un problema y en que forma se relacionan con la mejor solución heurística, para, de esta forma, asociar, a...
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Since Clarke and Wright proposed their well-known savings algorithm for solving the Capacitated Vehicle Routing Problem, several enhancements to the original savings formula have been recently proposed, in the form of parameterisations.... more
Since Clarke and Wright proposed their well-known savings algorithm for solving the Capacitated Vehicle Routing Problem, several enhancements to the original savings formula have been recently proposed, in the form of parameterisations. In this paper we first propose to use Empirically Adjusted Greedy Heuristics to run these parameterized heuristics and we also consider the addition of new parameters. This approach is shown to improve the savings algorithms proposed in the literature. Moreover, we propose a new procedure which leads to even better solutions, based on what we call Iterative Empirically Adjusted Greedy Heuristics.
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En la primera parte se hace una introducción a las líneas de montaje, conceptos básicos y tipos de líneas; se presenta una clasificación de los problemas de equilibrado de líneas y un estado del arte de los métodos y enfoques usados para... more
En la primera parte se hace una introducción a las líneas de montaje, conceptos básicos y tipos de líneas; se presenta una clasificación de los problemas de equilibrado de líneas y un estado del arte de los métodos y enfoques usados para resolver este tipo de problemas, enfatizando en aquellos que contemplan aspectos alternativos; además también se hace una introducción al problema que se plantea en este trabajo. En la segunda parte, se realiza un análisis del estado del arte, en donde se compara el problema de equilibrado propuesto con otros problemas que consideran flexibilidad de rutas (rutas de montaje alternativas): la idea principal en esta parte es indagar, si hay alguno, los enfoques y procedimientos usados para resolver el problema propuesto. En la tercera parte, se presenta detalladamente el problema que se enfoca en este trabajo, en el que se considera, conjuntamente al proceso de equilibrado, el procedo de decisión acerca de la ruta de montaje. Finalmente se presentan la...
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ABSTRACT The development of cloud technologies allows the implementation of scalable, versatile, and customized systems, constructed on-demand. This allows more efficient use of computing resources, improving the revenue of the system and... more
ABSTRACT The development of cloud technologies allows the implementation of scalable, versatile, and customized systems, constructed on-demand. This allows more efficient use of computing resources, improving the revenue of the system and enhancing the Quality of Service (QoS) received by users while minimizing the power consumption of the machines. Several research works conclude that in order to efficiently manage a cloud-based infrastructure (meaning, deploy computing resources when needed without affecting negatively to the QoS perceived by users), accurate predictions on the load of machines should be made. Thanks to this, resources can be ready to use when users need them, and shutdown when they are not needed — thus reducing the power consumption and enhancing the revenue of the system. This paper presents algorithms to perform forecasts of the load of machines based on Exponential Smoothing (ES), so that the machines of the technological infrastructure of our University can be efficiently managed. Furthermore, algorithms to perform monitoring and provision of resources based on load forecasts are presented. The usefulness of these algorithms is illustrated by means of a use case based on the e-learning facilities of our University. This use case shows that thanks to the use of cloud technologies, enhanced with the developed algorithms for load forecasting and provision of resources, better use of resources and lower power consumption can be achieved, without affecting the QoS received by user.
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This work presents a new system for the automatic assessment of practical activities in the context of the EHEA. A subject focused on the configuration of network services has been chosen to implement the new automatic evaluation... more
This work presents a new system for the automatic assessment of practical activities in the context of the EHEA. A subject focused on the configuration of network services has been chosen to implement the new automatic evaluation platform. Unlike traditional platforms based on theoretical contents to evaluate the students' knowledge, the proposed system is able to immediately evaluate students' practical skills and, additionally, provide them with feedback about the correctness of their activities. Therefore, faculty can dynamically follow the students' progress in order to adjust the learning process to their needs. Since the UNED University serves a large number of students via a distance-learning methodology, the use of scalable assessment platforms within the students' learning process is crucial to keep it working efficiently. Automatic assessment systems are also of particular interest when practical activities are performed within higher engineering courses.
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ABSTRACT Thanks to the development of cloud technologies, the way how computing is understood has evolved from "computer guided" to "user guided" systems. That is, initially, computers had static... more
ABSTRACT Thanks to the development of cloud technologies, the way how computing is understood has evolved from "computer guided" to "user guided" systems. That is, initially, computers had static software features in which users sharing them had to "fit", but now there is a shift to dynamic systems in which it is the computer which has to fit into the users' needs. This allows more efficient use of computing resources, improving the revenue and enhancing the Quality of Service (QoS) received by users. In order to deploy computing resources when needed without affecting negatively to the QoS perceived by users, accurate predictions on the load of machines should be made. Thanks to this, resources can be ready to use when users need them, and shutdown when they are not needed. This reduces the power consumption and enhances the revenue of the system. This paper presents an algorithm to perform resource provisioning on the machines of the technological infrastructure of our University, so that they can be efficiently managed. This algorithm is based on load forecasts created using Exponential Smoothing.
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... April 4 - 6, 2010, Amman, Jordan Page 395 Page 5. / [6] M. Martínez and S. Bracho, Design of a microelectronic circuits course using interactive methods, in International Conference on Microelectronic Systems Educcation (MSE), 2005,... more
... April 4 - 6, 2010, Amman, Jordan Page 395 Page 5. / [6] M. Martínez and S. Bracho, Design of a microelectronic circuits course using interactive methods, in International Conference on Microelectronic Systems Educcation (MSE), 2005, pp. 2324. ...
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ABSTRACT This paper presents our work on the developement of an architecture for e-learning that is based on cloud computing. This includes the creation of virtualized environments to be used in the field of networks and communications,... more
ABSTRACT This paper presents our work on the developement of an architecture for e-learning that is based on cloud computing. This includes the creation of virtualized environments to be used in the field of networks and communications, and the development of techniques to predict the load of the technology infrastructures of the university. The main aim of this work is to improve the use of the resources of the technology infrastructure of the university and provide an easy to use environment for students.
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Research Interests: Information Systems, Computer Science, Computer Science Education, Distance Education, Active Learning, and 11 moreAdaptation, E Learning Management System, Cryptography, User eXperience, Control Systems, Open Source, Robustness, European Higher education Area, Point of View, User Requirements, and Application Software
ABSTRACT The development of cloud technologies allows the implementation of scalable, versatile, and customized systems, constructed on-demand. This allows more efficient use of computing resources, improving the revenue of the system and... more
ABSTRACT The development of cloud technologies allows the implementation of scalable, versatile, and customized systems, constructed on-demand. This allows more efficient use of computing resources, improving the revenue of the system and enhancing the Quality of Service (QoS) received by users while minimizing the power consumption of the machines. Several research works conclude that in order to efficiently manage a cloud-based infrastructure (meaning, deploy computing resources when needed without affecting negatively to the QoS perceived by users), accurate predictions on the load of machines should be made. Thanks to this, resources can be ready to use when users need them, and shutdown when they are not needed — thus reducing the power consumption and enhancing the revenue of the system. This paper presents algorithms to perform forecasts of the load of machines based on Exponential Smoothing (ES), so that the machines of the technological infrastructure of our University can be efficiently managed. Furthermore, algorithms to perform monitoring and provision of resources based on load forecasts are presented. The usefulness of these algorithms is illustrated by means of a use case based on the e-learning facilities of our University. This use case shows that thanks to the use of cloud technologies, enhanced with the developed algorithms for load forecasting and provision of resources, better use of resources and lower power consumption can be achieved, without affecting the QoS received by user.
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Page 1. dotLAB: Integrating Remote Labs in dotLRN Integration of Web Labs and Learning Management Systems Alberto Pesquera, Raúl Morales, Rafael Pastor Innovation and Technological Development Centre UNED - Spanish ...
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This work presents a new system for the automatic assessment of practical activities in the context of the EHEA. A subject focused on the configuration of network services has been chosen to implement the new automatic evaluation... more
This work presents a new system for the automatic assessment of practical activities in the context of the EHEA. A subject focused on the configuration of network services has been chosen to implement the new automatic evaluation platform. Unlike traditional platforms based on theoretical contents to evaluate the students' knowledge, the proposed system is able to immediately evaluate students' practical skills and, additionally, provide them with feedback about the correctness of their activities. Therefore, faculty can dynamically follow the students' progress in order to adjust the learning process to their needs. Since the UNED University serves a large number of students via a distance-learning methodology, the use of scalable assessment platforms within the students' learning process is crucial to keep it working efficiently. Automatic assessment systems are also of particular interest when practical activities are performed within higher engineering courses.
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The proliferation of remote laboratories in multiple disciplines of science has removed the cost and administration burdens that hinder the adoption of practical sessions in engineering education. Remote laboratories provide online... more
The proliferation of remote laboratories in multiple disciplines of science has removed the cost and administration burdens that hinder the adoption of practical sessions in engineering education. Remote laboratories provide online workbenches unconstrained by neither temporal nor geographical considerations and allow an interactive learning that maintains student attention. Recently, remote laboratories have been developed at multiple universities and adopted in
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ABSTRACT Thanks to the development of cloud technologies, the way how computing is understood has evolved from "computer guided" to "user guided" systems. That is, initially, computers had static... more
ABSTRACT Thanks to the development of cloud technologies, the way how computing is understood has evolved from "computer guided" to "user guided" systems. That is, initially, computers had static software features in which users sharing them had to "fit", but now there is a shift to dynamic systems in which it is the computer which has to fit into the users' needs. This allows more efficient use of computing resources, improving the revenue and enhancing the Quality of Service (QoS) received by users. In order to deploy computing resources when needed without affecting negatively to the QoS perceived by users, accurate predictions on the load of machines should be made. Thanks to this, resources can be ready to use when users need them, and shutdown when they are not needed. This reduces the power consumption and enhances the revenue of the system. This paper presents an algorithm to perform resource provisioning on the machines of the technological infrastructure of our University, so that they can be efficiently managed. This algorithm is based on load forecasts created using Exponential Smoothing.
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... April 4 - 6, 2010, Amman, Jordan Page 395 Page 5. / [6] M. Martínez and S. Bracho, Design of a microelectronic circuits course using interactive methods, in International Conference on Microelectronic Systems Educcation (MSE), 2005,... more
... April 4 - 6, 2010, Amman, Jordan Page 395 Page 5. / [6] M. Martínez and S. Bracho, Design of a microelectronic circuits course using interactive methods, in International Conference on Microelectronic Systems Educcation (MSE), 2005, pp. 2324. ...
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This paper describes the e-learning architecture of the National Spanish Distance Learning University of Spain (UNED). The UNED has more than 200,000 users of e-learning systems (most of them, students) so it needed an enterprise... more
This paper describes the e-learning architecture of the National Spanish Distance Learning University of Spain (UNED). The UNED has more than 200,000 users of e-learning systems (most of them, students) so it needed an enterprise architecture in order to ensure the performance of the virtual campus. The core of virtual campus is aLF (active learning framework) supported by dotLRN/OpenACS open source framework that provides the e-learning core services. aLF is was modified to support the EHEA learning model, based in activity curricula, providing full integration with the evaluation model of aLF and three new tools to focus on the student tasks planning.
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ABSTRACT This paper presents our work on the developement of an architecture for e-learning that is based on cloud computing. This includes the creation of virtualized environments to be used in the field of networks and communications,... more
ABSTRACT This paper presents our work on the developement of an architecture for e-learning that is based on cloud computing. This includes the creation of virtualized environments to be used in the field of networks and communications, and the development of techniques to predict the load of the technology infrastructures of the university. The main aim of this work is to improve the use of the resources of the technology infrastructure of the university and provide an easy to use environment for students.