Search results for "problems"
showing 10 items of 620 documents
Radiating and non-radiating sources in elasticity
2018
In this work, we study the inverse source problem of a fixed frequency for the Navier's equation. We investigate that nonradiating external forces. If the support of such a force has a convex or non-convex corner or edge on their boundary, the force must be vanishing there. The vanishing property at corners and edges holds also for sufficiently smooth transmission eigenfunctions in elasticity. The idea originates from the enclosure method: The energy identity and new type exponential solutions for the Navier's equation.
Mixed heuristic-non linear optimization of energy management for hydrogen storage-based multi carrier hubs
2014
In this paper, an heuristic and non-linear programming based algorithm to optimally operate an energy hub plant is proposed. The energy hub plant described in this work is the test system for the European INGRID research project. The Energy Management System defines the optimal energy flows dispatch in order to obtain the energy balance and the maximum profit for the owner of the plant. The problem is highly constrained and non-linear, for this reason the methodology cannot rely on Linear Programming (LP) methods. The Energy Management System manages two energy carriers, electricity and hydrogen, interfacing three distribution networks: the electricity, the hydrogen and the methane networks…
Time-Optimal Synthesis for Three Relevant Problems: The Brockett Integrator, the Grushin Plane and the Martinet Distribution
2015
We construct the time-optimal synthesis for 3 problems that are linear in the control and with polytopic constraints in the controls. Namely, the Brockett integrator, the Grushin plane, and the Martinet distribution. The main purpose is to illustrate the steps in solving an optimal control problem and in particular the use of second order conditions. The Grushin and the Martinet case are particularly important: the first is the prototype of a rank-varying distribution, the second of a non-equiregular structure.
Numerical studies of the melting process in the induction furnace with cold crucible
2008
PurposeAims to present recent activities in numerical modeling of cold crucible melting process.Design/methodology/approach3D numerical analysis was used for electromagnetic problem and 3D large eddy simulation (LES) method was applied for fluid flow modeling.FindingsThe comparative modeling shows, that higher H/D ratio of the melt is more efficient when total power consumption is considered, but this advantage is held back by higher heat losses through the crucible walls. Also, calculations reveal that lower frequencies, which are energetically less effective, provide better mixing of the melt.Originality/value3D electromagnetic model, which allows to take into account non‐symmetrical dist…
A GRASP algorithm for the container stowage slot planning problem
2016
This work presents a generalization of the Slot Planning Problem which raises when the liner shipping industry needs to plan the placement of containers within a vessel (stowage planning). State-of-the-art stowage planning relies on a heuristic decomposition where containers are first distributed in clusters along the vessel. For each of those clusters a specific position for each container must be found. Compared to previous studies, we have introduced two new features: the explicit handling of rolled out containers and the inclusion of separations rules for dangerous cargo. We present a novel integer programming formulation and a Greedy Randomized Adaptive Search Procedure (GRASP) to solv…
Una propuesta para trabajar la proporción desde el arte
2013
[EN] We present a proposal addressed to students of the first courses of ESO. Through these activities, pupils will work concepts related with proportionality. Our proposal is developed along art history, the students will acquire skills related with proportionality through the uses the artists have done throughout history. Through a route beginning in ancient Egypt and ending in today Athens, students will act as the artists, architects or even tour guides to deal with technical problems and solve them mathematically. Some of the activities have been already implemented in the project Estalmat CV (a mathematic stimulation program for talented students) and later adapted to a conventional c…
María Consuelo Reyna Periodista y empresaria en la Transición valenciana
2016
El pasado 31 de enero Las Provincias, el diario decano de Valencia, celebró su 150 aniversario. Los actos conmemorativos contaron con la asistencia del rey Felipe VI inaugurando la muestra ‘La huella de 150 valencianos en el 150 aniversario de Las Provincias’ y, sin embargo, faltó un personaje que ha dejado huella en su pasado de casi tres décadas, María Consuelo Reyna. Reyna, descendiente del fundador de Las Provincias y una de las primeras mujeres al frente de un medio, ha sido voz y testigo de la Transición desde la redacción. Destituida en 1999 por el Consejo integrado por las familias Reyna y Zarranz, la empresa pasa entonces a Vocento, y finaliza un largo ciclo, determinante en la rec…
La obligatoriedad de un servicio social y los deberes de solidaridad.
1996
Plantear los límites de actuación del Estado social es lo mismo que los límites en las exigencias de solidaridad. Los deberes jurídicos —y no sólo morales— de la solidaridad van más allá de las contribuciones económicas, alcanzando una contribución personal en términos de tiempo. El autor analiza la coincidencia de tres modelos: servicio civil, voluntariado y trabajadores sociales. El crecimiento de estos dos últimos como consecuencia del Estado asistencial invita a definir los papeles para impulsar el objetivo del Estado social a partir de la ciudadanía socialmente responsable. Índice: La solidaridad como principio jurídico. Solidaridad, Estado social de Derecho y ciudadanía. Los deberes d…
Análisis de los modelos matemáticos producidos durante la resolución de problemas de Fermi
2017
[EN] In this paper, we present an analysis of written productions of 16 year-old students while solving Estimation Problems involving Big Numbers (EPiBN). This kind of problems is a particular type of Fermi problems and allows us to introduce modelling processes in Secondary school classrooms. Our analysis supports on the characterization of mathematical models developed by students based on the model definition of Lesh and Harel. The results show that, through the analysis of EPiBN resolutions, differentiating aspects can be distinguished between the models produced by students without modelling experience of those produced by students with prior experience, especially in the concepts and …
On thermoeconomics of energy systems at variable load conditions: integrated optimization of plant design and operation
2007
Abstract Thermoeconomics has been assuming a growing role among the disciplines oriented to the analysis of energy systems, its different methodologies allowing solution of problems in the fields of cost accounting, plant design optimisation and diagnostic of malfunctions. However, the thermoeconomic methodologies as such are particularly appropriate to analyse large industrial systems at steady or quasi-steady operation, but they can be hardly applied to small to medium scale units operating in unsteady conditions to cover a variable energy demand. In this paper, the fundamentals of thermoeconomics for systems operated at variable load are discussed, examining the cost formation process an…