Project Scheduling with Flexible Resources: Is there a good optimization model?

10 mayo, 2021
12:00 pm

Título:  Project Scheduling with Flexible Resources: Is there a good optimization model?

Ponente: Francisco Saldanha-da-Gama (University of Lisbon)

Organizador: Javier Alcaraz

Fecha: Lunes 10 de mayo de 2021 a las 12:00 horas.

Lugar:  Online.

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Abstract: A project scheduling problem is defined by a set of activities, their precedence relations, and the corresponding execution times. The goal is to sequence and schedule the activities so that some performance measure of interest is optimized. Often, specific resources that exist in a limited amount are required to execute the activities. This extension of the problem is called the Resource-Constrained Project Scheduling Problem (RCPSP). One assumption in the RCPSP is that each resource has one specific function. However, in many situations (e.g. when human resources are involved), a resource masters several skills and thus can contribute in different ways to the execution of an activity. This extension leads to the so-called multi-skill resource constrained project scheduling problem (MS-RCPSP). This is a problem emerging for instance in consulting companies that have to allocate multi-skilled teams to different projects. Software development companies also face this problem when people with different capabilities are to be combined in different teams to contribute to the development of several products. The organization of evaluation teams is another example in which one may face a MS-RCPSP. In this case, multi-skilled teams are to be organized to visit departments, organizations or institutions and write an assessment report.

In the simplest setting of the MS-RCPSP, each activity requires several units of each skill. Additionally, each resource has several skills but can contribute with at most one skill-unit to each activity. Moreover, the allocation of each resource to some activity should last for the entire duration of the activity. The resources are assumed to be renewable, which means that after being used in some activity they can be assigned to another one (without overlap). The goal is to find a sequence and scheduling for the activities together with allocation of the resources to them so that the makespan is minimized.

In this seminar the state-of-the-art in the topic is discussed namely, the possibility of modeling mathematically this class of problems. Different modeling frameworks are discussed highlighting their advantages and disadvantages. In particular, the models are compared theoretically in terms of the linear programming relaxation since the use of such bounds is often the only way to assess the quality of heuristic solutions developed for the problem.

On the axiomatic approach to sharing the revenues from broadcasting sports leagues

4 mayo, 2021
12:00 pm

Título:  On the axiomatic approach to sharing the revenues from broadcasting sports leagues

Ponente: Juan de Dios Moreno Ternero (Universidad Pablo Olavide)

Organizador: Joaquín Sánchez

Fecha: Martes 4 de mayo de 2021 a las 12:00 horas.

Lugar:  Online.

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Abstract: We take the axiomatic approach to uncover the structure of the revenue-sharing problem from broadcasting sports leagues. Our starting point is to explore the implications of three basic axioms: additivity, order preservation and weak upper bound. We show that the combination of these axioms characterizes a large family of rules, which is made of compromises between the uniform rule and concede-and-divide, such as the one represented by the equal-split rule. The members of the family are fully ranked according to the Lorenz dominance criterion, and the structure of the family guarantees the existence of a majority voting equilibrium. Strengthening some of the previous axioms, or adding new ones, we provide additional characterizations within the family. Weakening some of those axioms, we also characterize several families encompassing the original one.

Medición de la eficiencia de servicios públicos y la importancia del contexto no controlable. Alternativas metodológicas y aplicaciones prácticas

26 abril, 2021
12:00 pm

Título:  Medición de la eficiencia de servicios públicos y la importancia del contexto no controlable. Alternativas metodológicas y aplicaciones prácticas Ponente: Cristina Polo (Universidad de Extremadura) Organizador: Lidia Ortiz Fecha: Lunes 26 de abril de 2021 a las 12:00 horas. Lugar:  Online.

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Abstract: La medición de la eficiencia en los diversos ámbitos de la economía pública ha suscitado gran interés durante las últimas décadas. Las técnicas más utilizadas en la literatura para estimar el desempeño de las unidades productivas han sido claramente los modelos de frontera no paramétricos tales como el DEA, el FDH o, más recientemente, sus versiones de fronteras parciales robustas (orden-m, orden-α). Sin embargo, no siempre se tiene en cuenta el efecto que pueden producir sobre los niveles de eficiencia aquellas variables que pueden influir en el proceso de producción y ser responsables de las diferencias en el rendimiento de las unidades, pero que escapan completamente al control del gestor. El tratamiento de las llamadas variables exógenas o ambientales (Z) en la estimación de la eficiencia ha sido uno de los temas más controvertidos en el cauce convergente entre economía aplicada e investigación operativa. En este seminario se presentan dos de las alternativas metodológicas desarrolladas más recientemente en la literatura que permiten incorporar estas variables Z al proceso productivo y analizar su efecto sobre la eficiencia: el modelo condicional y el modelo StoNEZD. Estos enfoques conllevan una serie de ventajas e inconvenientes que también serán expuestos, así como las posibles extensiones para su aplicación en determinadas circunstancias (datos de panel, presencia de outputs no deseables, etc.). Para finalizar, la utilidad de cada técnica se ilustrará con una aplicación empírica.

Explicit PV modelling & model-based applications in PV systems

19 abril, 2021
12:00 pm

Título:  Explicit PV modelling & model-based applications in PV systems

Ponente: Efstratios Batzelis (Imperial College London)

Organizador: Javier Toledo Melero

Fecha: Lunes 19 de abril de 2021 a las 12:00 horas.

Lugar:  Online.

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Abstract: The solar photovoltaic (PV) technology has lately faced remarkable growth worldwide and remains central in many countries’ strategic plan for decarbonization of the energy sector. This talk will first look into the modelling aspects of the PV generator, discussing models of explicit formulation to calculate the current-voltage characteristic, to determine the maximum power point (MPP) and to extract the model parameters. The second part of the talk will demonstrate real-time applications of these models in PV systems towards a more “grid-friendly” profile, i.e. to be more supportive of the electric grid during disturbances and allow higher levels of solar integration. It is shown how an embedded algorithm into the microcontroller of the PV inverter can make good use of these models to provide power reserves and estimate the MPP power from a curtailed power level.

Short Bio: Dr Efstratios (Stratis) Batzelis is an expert in photovoltaic systems modelling, control and integration. He is a Lecturer (Assistant Professor) at the University of Southampton (UK) and a Royal Academy of Engineering Research Fellow working on solar integration challenges in developing countries. Prior to this post, he held an EU Marie-Curie fellowship at Imperial College London (UK) on more grid-friendly PV systems in 2017-2019, and he received his PhD degree from the National Technical University of Athens (Greece) in 2016. Dr Batzelis’s research on PV systems has received about £1.6M funding and has been published in about 35 journal and conference papers. He is a Senior IEE member and currently serves as an associate Editor in IEEE Transactions on Sustainable Energy. His research interests include renewable energy technologies and distributed generation, especially solar photovoltaics, power converters control and power system stability.

Seminario Joaquín Sánchez Soriano

13 abril, 2021
12:00 pm

Título:  Los problemas de atribución y sus aplicaciones desde la perspectiva de la teoría de juegos.

Ponente: Joaquín Sánchez Soriano

Organizador: CIO

Fecha: Martes 13 de abril de 2021 a las 12:00 horas.

Lugar:  Online.

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Abstract: Un problema de atribución consiste simplemente en determinar cuál es la relevancia de una serie de factores para la consecución de un objetivo particular. Aunque la formulación del problema parece sencilla, no lo es tanto, y por ello existe toda una literatura sobre este problema en muy diversos campos. Por ejemplo, este tipo de problemas tiene una especial relevancia en muchos campos como el marketing, tanto tradicional como online; la salud pública; la gestión; las ciencias de la computación; la evaluación del desempeño; el reparto de costes/beneficios o la asignación de recursos, entre otros. En este seminario revisaremos algunas de las aplicaciones más relevantes de estos problemas desde la perspectiva de la teoría de juegos. Finalizamos con una aplicación más detallada de la teoría de juegos al problema de atribución de relevancia a factores de riesgo en el desenlace fatal de una enfermedad, aplicando los resultados teóricos al caso de la COVID-19.