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This is the peer reviewed version of the following article: Diez, P. [et al.]. Nonlinear dimensionality reduction for parametric problems: a kernel proper orthogonal decomposition. "International journal for numerical methods in engineering", 30 Desembre 2021, vol. 122, núm. 24, p. 7306-7327, which has been published in final form at DOI: 10.1002/nme.6831. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Reduced-order models are essential tools to deal with parametric problems in the context of optimization, uncertainty quantification, or control and inverse problems. The set of parametric solutions lies in a low-dimensional manifold (with dimension equal to the number of independent parameters) embedded in a large-dimensional space (dimension equal to the number of degrees of freedom of the full-order discrete model). A posteriori model reduction is based on constructing a basis from a family of snapshots (solutions of the full-order model computed offline), and then use this new basis to solve the subsequent instances online. Proper orthogonal decomposition (POD) reduces the problem into a linear subspace of lower dimension, eliminating redundancies in the family of snapshots. The strategy proposed here is to use a nonlinear dimensionality reduction technique, namely, the kernel principal component analysis (kPCA), in order to find a nonlinear manifold, with an expected much lower dimension, and to solve the problem in this low-dimensional manifold. Guided by this paradigm, the methodology devised here introduces different novel ideas, namely, 1) characterizing the nonlinear manifold using local tangent spaces, where the reduced-order problem is linear and based on the neighboring snapshots, 2) the approximation space is enriched with the cross-products of the snapshots, introducing a quadratic description, 3) the kernel for kPCA is defined ad hoc, based on physical considerations, and 4) the iterations in the reduced-dimensional space are performed using an algorithm based on a Delaunay tessellation of the cloud of snapshots in the reduced space. The resulting computational strategy is performing outstandingly in the numerical tests, alleviating many of the problems associated with POD and improving the numerical accuracy. Generalitat de Catalunya, 2017-SGR-1278; Ministerio de Ciencia e Innovación, CEX2018-000797-S; PID2020-113463RB-C32; PID2020-113463RB-C33

This paper analyzes the behavior of a miniature 3D wind sensor designed for Mars atmosphere. The sensor is a spherical structure of 10 mm diameter divided in four sectors. By setting all the sectors to constant temperature, above that of the air, the 3D wind velocity vector can be measured. Two sets of experiments have been performed. First, an experimental campaign made under typical Mars conditions at the Aarhus Wind Tunnel Simulator is presented. The results demonstrate that both wind speed and angle can be efficiently measured, using a simple inverse algorithm. The effect of sudden wind changes is also analyzed and fast response times in the range of 0.7 s are obtained. The second set of experiments is focused on analyzing the performance of the sensor under extreme Martian wind conditions, reaching and going beyond the Dust Devil scale. To this purpose, both high-fidelity numerical simulations of fluid dynamics and heat transfer and experiments with the sensor have been performed. The results of the experiments, made for winds in the Reynolds number 1000&ndash, 2000 range, which represent 65&ndash, 130 m/s of wind speed under typical Mars conditions, further confirm the simulation predictions and show that it will be possible to successfully measure wind speed and direction even under these extreme regimes.

El punt de partida d'aquest projecte ha estat un robot fet amb Lego, que disposa de dos rodes mogudes per motors individuals, un braç articulat amb 2 graus de llibertat i una mà que pot agafar objectes lleugers. La finalitat del projecte ha estat desenvolupar una electrònica de control per tal de donar-li una mobilitat i percepció del entorn bàsica així com alguns moviments automàtics. The starting point of the project is a robot made with Lego, which has two wheels moved by two stepper motors, an arm with two movements and a hand able to take light objects. The finality of the project has been to develop the control electronics to give it mobility and environment perception and some automatic movement. El punto de partida de este proyecto ha sido un robot hecho con Lego, que dispone de dos ruedas movidas por motores individuales, un brazo articulado con 2 grados de libertad y una mano que puede coger objetos ligeros. La finalidad del proyecto ha sido desarrollar una electrónica de control para darle una movilidad y percepción del entorno básica así como algunos movimientos automáticos.

A new modification to the Chua oscillator is proposed.Bifurcation diagrams, Poincare map and the Lyapunov exponents are presented.An application to secure communications is presented.A synchronization scheme based on the modified oscillator is proposed.System simulations are performed for analysis. In this paper, a new modified Chua oscillator is introduced. The original Chua oscillator is well known for its simple implementation and mathematical modeling. A modification of the oscillator is proposed in order to facilitate the synchronization and the encryption and decryption scheme. The modification consists in changing the nonlinear term of the original oscillator to a smooth and bounded nonlinear function. A bifurcation diagram, a Poincare map and the Lyapunov exponents are presented as proofs of chaoticity of the newly modified oscillator. An application to secure communications is proposed in which two channels are used. Numerical simulations are performed in order to analyze the communication system.

In this paper an LPV non-integer order control model of an irrigation canal is derived from system identification experiments. This model is experimentally obtained by using the described LPV fractional identification procedure. This procedure consists on the identification of a non-linear order model in each operation point of the canal. The global LPV model is obtained by the polynomial interpolation of the parameters of the local models. The validation results show that fractional models are more accurate than integer models. Therefore the fractional models have an important role to play in management and efficient use of water resources.

L'objectiu d'aquest treball de final de carrera és implementar una aplicació sobre un node de xarxa sense fils equipat amb un microcontrolador, una ràdio i un conjunt de sensors, emprant el llenguatge nesC sobre el sistema operatiu TinyOS. Aquesta proposta consisteix en un sistema domòtic que detecti si un habitacle està ocupat i permeti controlar-ne la temperatura i el nivell de il·luminació per tal de que es mantenguin dins uns valors establerts que poden ser modificats per l'usuari. El objetivo de este trabajo de final de carrera es implementar una aplicación sobre un nodo de red inalámbrica equipado con un microcontrolador, una radio y un conjunto de sensores, empleando el lenguaje nesC sobre el sistema operativo TinyOS. Esta propuesta consiste en un sistema domótico que detecte si un habitáculo está ocupado y permita controlar la temperatura y el nivel de iluminación para que se mantengan dentro de unos valores establecidos que pueden ser modificados por el usuario. This final degree project aims to implement an application on a wireless network equipped with a microcontroller, a radio and a set of sensors, using the language nesC on TinyOS operating system.

This paper presents the schedulability analysis for control messages when networked control loops, built on top of the controller area network (CAN), are dynamically allocating bandwidth in terms of their controlled plants' dynamics. The bandwidth allocation policy is theoretically described by an optimization problem and practically solved by the distributed bitwise arbitration of CAN messages when message identifiers, i.e., priorities, reflect control applications demands. This poses the problem of assessing whether the set of real-time messages will meet their deadlines regardless of run-time priority changes. This is solved by a schedulability analysis based on recent results on worst-case response time techniques for real-time CAN applications. The analysis ends up with the schedulability test for this type of applications.

El desalineamiento temporal es la incorrespondencia de dos señales debido a una distorsión en el eje temporal. La Detección y Diagnóstico de Fallas (Fault Detection and Diagnosis-FDD) permite la detección, el diagnóstico y la corrección de fallos en un proceso. La metodología usada en FDD está dividida en dos categorías: técnicas basadas en modelos y no basadas en modelos. Esta tesis doctoral trata sobre el estudio del efecto del desalineamiento temporal en FDD. Nuestra atención se enfoca en el análisis y el diseño de sistemas FDD en caso de problemas de comunicación de datos, como retardos y pérdidas. Se proponen dos técnicas para reducir estos problemas: una basada en programación dinámica y la otra en optimización. Los métodos propuestos han sido validados sobre diferentes sistemas dinámicos: control de posición de un motor de corriente continua, una planta de laboratorio y un problema de sistemas eléctricos conocido como hueco de tensión., Time misalignment is the unmatching of two signals due to a distortion in the time axis. Fault Detection and Diagnosis (FDD) deals with the timely detection, diagnosis and correction of abnormal conditions of faults in a process. The methodology used in FDD is clearly dependent on the process and the sort of available information and it is divided in two categories: model-based and non-model based techniques. This doctoral dissertation deals with the study of time misalignments effects when performing FDD. Our attention is focused on the analysis and design of FDD systems in case of data communication problems, such as delays and dropouts. Techniques based on dynamic programming and optimization are proposed to deal with these problems. Numerical validation of the proposed methods is performed on different dynamic systems: a control position for a DC motor, a laboratory plant and an electrical system problem known as voltage sag.

En este artículo se considera el control en modo de deslizamiento (SMC1) de un generador de inducción doblemente alimentado (DFIG) que suministra a una carga RL aislada, en un sistema de generación de velocidadvariable/frecuencia-constante (VSCF). Para el control del DFIG parece conveniente utilizar una técnica robusta, debido a la existencia de variaciones en sus parámetros, causadas por razones como cambios en la temperatura de los devanados, histéresis y saturación. Por ello es que se ha considerado el SMC. Éste tiene varias características atractivas, como reducción de orden, robustez, rechazo a perturbaciones y, en ocasiones, implementación sencilla. En este trabajo, algunas ideas de SMC, que han sido usadas por Utkin y colaboradores para el control de par/velocidad del motor de inducción jaula de ardilla, se aplican para diseñar dos familias de controladores para regular la amplitud y la frecuencia del voltaje generado por el DFIG. También, se incluyen los primeros resultados de simulación.

We consider the topology of the set of conditioned invariant subspaces of an observable pair $(C,A)$ of a fixed dimension. By fixing the observability indices of the restricted system, a stratification by finitely many smooth manifolds is obtained, termed Brunovsky strata. It is shown that each Brunovsky stratum is homotopy equivalent to a generalized flag manifold. From this description an effective formula for the Betti numbers of the Brunovsky strata can be derived.

This paper presents the desired current references in order to minimize the torque ripple for a Switched Reluctance Motor. From the torque equation, and using switch on and switch off angles, the desired current waveforms are obtained. Simulations validates the study and are compared with the constant current references case

Open-flow canals are large distributed systems characterized by non-linear, time-varying and dependent with the operating point behavior. These systems can be suitably represented for control by linear parameter varying (LPV) models. In this paper, two ways of obtaining an LPV model for a single reach open canal are proposed and compared: an LPV integrator delay zero (IDZ) model based on hydraulic laws and an LPV model based on identification techniques. The first approach is a white-box modeling approach while the latter is a grey-box methodology using experimental data. Finally, they will be applied and compared in a test-bench canal.

Proper Generalized Decomposition (PGD) is devised as a computational method to solve high-dimensionalboundary value problems(where many dimensions are associated with the space of parameters defining the problem). The PGD philosophy consists in providing a separated representation of the multidimensional solution using agreedy approachcombined with an alternated directions scheme to obtain the successive rank-one terms. This paper presents an algorithmic approach to high-dimensional tensorseparation based on solving theLeast Squares approximationin a separable format of multidimensional tensor using PGD. This strategy is usually embedded in a standard PGD code in order to compress the solution (reduce the number of terms and optimize the available storage capacity), but it stands also as an alternative and highly competitive method for tensor separation.

This paper presents a preliminary approach to networked control systems (NCS) that relies on an event-driven control method based on Lyapunov sampling. The goal is to study and develop approaches for NCS capable of offering controllers with low bandwidth demands. The paper starts by presenting the theoretical framework required for applying Lyapunov sampling to a set of closed-loop systems that share a serial bus line. The discussion permits identifying which requirements must be fulfilled in order to guarantee overall stability. In addition, the feasibility of the theoretical framework in terms of implementation requires to address problems caused by the implicit distributed architecture of the NCS. In particular, an efficient implementation approach is described for the CAN network. Simulation results illustrate the operation and benefits of the presented approach.

Affine connection control systems are mechanical control systems that model a wide range of real systems such as robotic legs, hovercrafts, planar rigid bodies, rolling pennies, snakeboards and so on. In 1997 the accessibility and a particular notion of controllability was intrinsically described by A. D. Lewis and R. Murray at points of zero velocity. Here, we present a novel generalization of the description of accessibility algebra for those systems at some points with nonzero velocity as long as the affine connection restricts to the distribution given by the symmetric closure. The results are used to describe the accessibility algebra of different mechanical control systems.

This work presents a new technique to securely transmit and retrieve a message signal via chaotic systems. In our system, a two-valued message signal modulates the frequency of a Duffing oscillator sinusoidal term. An observer is used in the receiver side to retrieve the sinusoidal signal that contains the message and a novel frequency estimator is then used to reproduce an approximated estimation of the message signal. The performance of the system is analyzed by means of numerical simulations performed in Matlab.

Probe-based technologies are proliferating as a means of inferring traffic states. Technological companies are interested in traffic data for computing the best routes in a traffic-aware manner and they also provide real-time traffic information with certain temporal accuracy. This paper analyses and evaluates how data provided by a fleet of probe cars can be used to develop a navigation service and how the penetration rate of this service affects a set of city-scale KPIs (Key Performance Indicators) and driver KPIs. The case study adopts a model-driven approach in which microscopic simulation emulates real-size fleets of probe vehicles that provide positions and speed data. What is noteworthy about the modelling behaviour is that drivers are segmented according to their knowledge of network conditions for selected trips: experts, regular drivers, and tourists. The paper presents and discusses the modelling approach and the results obtained from an experimental Barcelona CBD model designed to evaluate the penetration rates of probe vehicles and route guidance. An analysis of the simulation experiments reveals remarkable links among city-scale KPIs, which—from a multivariate point of view—is a novelty. A simulation-based framework for results analysis and visualization is also introduced in order to simplify the simulation results analysis and easily visualize OD paths for driver segments. Throughout this work, the authors have benefited from the support of inLab FIB team at UPC and the suggestions of Jaume Barceló (Emeritus Professor at UPC). This research was funded by Spanish R+D Programs, TRA2016-76914-C3-1-P, and by Secretaria d’Universitats-i-Recerca-Generalitat de Catalunya, 2017-SGR-1749.

Disseny i control d'una cavitat òptica d'alta finesa per l'atropament i "cooling" d'objectes [ANGLÈS] In this project you will find a proposal of design and its implementation of a high-finesse cavity and its real-time electronic control in order to have an starting point for developing a cavity for trapping and cooling a living organism. [CASTELLÀ] En este proyecto se presenta una propuesta de disseño y su implementación de una cavidad láser de alta "finesse" y su control electrónico en tiempo real para tener un punto de partida para una cavidad donde se quiere conseguir la superposición quántica de un organismo vivo. [CATALÀ] En aquest projecte es presenta una proposta de disseny i la seva implementació d'una cavitat làser d'alta finesse i el seu control electrònic a temps real per tenir un punt de partida per una cavitat on es vol aconseguir la superposició quàntica d'organismes vius.

Implementación de un sistema de control distribuido con protocolos de comunicaciones de campo para una planta piloto. [ANGLÈS] The field of control systems and particularly the industrial instrumentation has undergone a major transformation in recent years, due to changes in the technologies of microelectronics, processors and communications. This has led to a strong expansion in industrial instrumentation so that today includes fields where none was incorporated. This project implements a distributed control system with modern and advanced instrumentation that uses all kinds of industrial communication protocols for inclusion in a pilot plant research. The first part of this project is an introductory overview of the different architectures of control systems and communications protocols in the field of industrial processes. This introduction will allow us to understand more easily control system specifications that have been set and the proposed solution, which is based on the distributed control system I/A Series ® from Foxboro. The next phase of the project is to implement physically the distributed control system I/A Series ® in accordance with specifications, mounting of all components and modules and performing all necessary interconnections. This part includes the installation of all programs and software needed. Then, we program all I/O of each and every one of the fieldbus used and designing a user environment that can be configurable for different research applications in the pilot plant. The final part of the project involves the installation and implementation of the distributed control system. We conclude with performance testing and validation and with a training course to end users. [CASTELLÀ]El campo de los sistemas de control y muy especialmente la instrumentación industrial han sufrido una transformación muy importante en estos últimos años, debido fundamentalmente a los cambios producidos en las tecnologías de la microelectrónica, de los procesadores y de las comunicaciones. Esto ha provocado una fuerte expansión de la instrumentación industrial de manera que a día de hoy abarca campos donde antes no se incorporaba. En este proyecto se implementa un sistema de control distribuido con instrumentación moderna y avanzada que utiliza todo tipo de protocolos de comunicaciones industriales para su incorporación en una planta piloto de investigación. En la primera parte de este proyecto se hace un resumen introductorio de las distintas arquitecturas de los sistemas de control y protocolos de comunicaciones en el ámbito de los procesos industriales. Esta introducción nos permitirá comprender con mayor facilidad las especificaciones del sistema de control que se han fijado y la solución propuesta, que está basada en el sistema de control distribuido I/A Series® de la marca Foxboro. En la siguiente fase del proyecto se implementa físicamente el sistema de control distribuido I/A Series® de acuerdo con las especificaciones, montando todos los componentes y módulos y realizando todas las interconexiones necesarias. Esta parte incluye la instalación de todos los programas y software necesario. Seguidamente se programan las E/S de todos y cada uno de los buses de campo utilizados y se diseña un entorno de usuario que pueda ser configurable para las distintas aplicaciones de investigación en la planta piloto. La parte final del proyecto consiste en la instalación y puesta en marcha del sistema de control distribuido. Se concluye con pruebas de funcionamiento y validación y con un curso de formación a los usuarios finales. [CATALÀ] El camp dels sistemes de control i molt especialment la instrumentació industrial han sofert una transformació molt important en aquests últims anys, degut fonamentalment als canvis produïts en les tecnologies de la microelectrònica, dels processadors i de les comunicacions. Això ha provocat una forta expansió de la instrumentació industrial de manera que a dia d'avui abasta camps on abans no s'incorporava. En aquest projecte s'implementa un sistema de control distribuït amb instrumentació moderna i avançada que utilitza tota mena de protocols de comunicacions industrials per a incorporar en una planta pilot d'investigació. A la primera part d'aquest projecte es fa un resum introductori de les diferents arquitectures dels sistemes de control i protocols de comunicacions en l'àmbit dels processos industrials. Aquesta introducció ens permetrà comprendre amb més facilitat les especificacions del sistema de control que s'han fixat i la solució proposada, que està basada en el sistema de control distribuït I/A Series ® de la marca Foxboro. En la següent fase del projecte s'implementa físicament el sistema de control distribuït I/A Series ® d'acord amb les especificacions, muntant tots els components i mòduls i realitzant totes les interconnexions necessàries. Aquesta part inclou la instal?lació de tots els programes i software necessari. Seguidament es programen les E/S de tots i cada un dels busos de camp utilitzats i es dissenya una interfície d'usuari que pugui ser configurable per a les diferents aplicacions de recerca a la planta pilot. La part final del projecte consisteix en la instal?lació i posada en marxa del sistema de control distribuït. Es conclou amb proves de funcionament i validació i amb un curs de formació als usuaris finals.

International audience; In this paper, an approach to design an Admissible Model Matching (AMM) Fault Tolerant Control (FTC) based on Linear Parameter Varying (LPV) fault representation is proposed. The main contribution of this approach is to consider the fault as a scheduling variable that allows the controller reconfiguration online. The fault is expressed as a change in the system dynamics (in particular, in the model parameters). The suggested strategy is an active technique that requires the fault to be detected, isolated and estimated by the FDI scheme. In case the fault estimation is not available, a passive strategy based on a single AMM FTC controller could be designed. The FTC controller is designed using LMI regional pole placement. The effectiveness and performances of the method have been illustrated in simulation considering a thermal hydraulic system.

This paper proposes a fault detection method for hysteretic base-isolation systems. One of the key contributions of this work is a Lyapunov-based restoring force observer that leads to the design of a robust fault detection scheme. The different fault types considered are stiffness and damping variations in the system. The proposed fault estimation method provides a direct estimate of the size and severity of the fault, which can be important in many civil engineering applications. A design procedure is described, and nonlinear simulation results are presented to demonstrate the applicability of the proposed method.

New sustainable mobility concepts and smart resilient ideas are arising every day. However, there is not an easy way to bring these ideas into reality, or to test how good they are as mobility solutions. Virtual Mobility Lab offers the opportunity to evaluate the impact of new mobility concepts before taking them to the real world. In this work, a multimodal macroscopic traffic simulation model of the Barcelona Metropolitan Area is developed, including both public and private transport network. This paper explains the remarkable features developed for this model, such as the network hierarchy and the multimodal public network interchangers, allowing demand to exchange between public transportation modes along their origin-destination paths.

En l’actualitat, els sistemes de control per a circuits de calderes, radiadors i aigua calenta sanitària tenen un inconvenient a l’hora d’instal·lar-los. Aquests sistemes de control, anomenats centraletes de regulació, estan dissenyats per a realitzar el control de diferents configuracions d’instal·lació, les quals incorporen diferents tipus de circuits. Cada centraleta pot fer-se càrrec d’una certa configuració de circuits i no és capaç d’adaptar-se a la instal·lació existent. Això provoca que s’hagin d’afegir més centraletes per a poder controlar aquests circuits, provocant la possibilitat de tenir centraletes amb circuits desconnectats, encarint innecessàriament la instal·lació. A l’hora de voler ampliar-la ens trobem amb el mateix problema o amb el de tenir que canviar les centraletes ja instal·lades, encarint la reforma. El propòsit d’aquest projecte ha estat dissenyar una centraleta de control modular i escalable que pugui evitar aquests dos problemes, afegint o millorant la flexibilitat i els costos d’instal·lació. Els mòduls de control d’aquesta centraleta es poden instal·lar de forma distribuïda per tota la instal·lació controlant individualment cada circuit. Els mòduls reporten el seu estat, i el del circuit, cap a un node que els gestiona, a través d’un bus de comunicacions. Això ens permet estalviar materials d’instal·lació i reduir encara més els costos del projecte. El resultat del sistema dissenyat canvia el sentit de la paraula centraleta, al convertir-se en un conjunt de mòduls que treballen de forma individual (descentralitzada). Aquesta soluciona els problemes detectats i ens permet fer una instal·lació més fàcil i econòmica, proporcionant una solució molt competitiva a l’hora d’introduir-la al mercat.

Records from 1,228 consecutively admitted patients (74.5% male) to an inpatient detoxification unit in Barcelona between 1993 and 2006 were examined to determine factors associated with discharge against medical advice (AMA). 21.5% of admissions were discharged AMA. In multiple logistic regression and compared with patients who were medically discharged, those discharged AMA were younger, more likely to be dependent on heroin, other opiates, cocaine or psychostimulants, or to be experiencing reduction or elimination methadone maintenance therapy [reference category: alcohol]. The provision of assistance to clinicians in identifying the patients who are most at risk of leaving inpatient detoxification AMA will enhance their ability to motivate such patients to stay in treatment.

In this paper, we present a method to control limit cycles in smooth planar systems making use of the theory of nonsmooth bifurcations. By designing an appropriate switching controller, the occurrence of a corner-collision bifurcation is induced on the system and the amplitude and stability properties of the target limit cycle are controlled. The technique is illustrated through a representative example.

Given an observable system (C,A)€ K^(mxn)X K^(nxn)with K=R or C, the set of (C,A)-invariant subspaces having the restricted system fixed observability indices is a smooth manifold embedded on the corresponding Grassmannian. We obtain an explicit parametrization of it by means of an atlas of corresponding charts. As an application we obtain the set of maximal dimensional outputs making solvable a generic Disturbance Decoupling Problem.

Martech 2009 Third Marine Technology Workshop, 19-20 november 2009, Vilanova i la Geltrú, Barcelona.-- 2 pages, 3 figures, In this paper is described the system that controls the connected devices in a subsea observatory. The control system is constantly monitoring the internal and external components of the observatory detecting operating faults and acting automatically in consequence, The project OBSEA is being founded from the Spanish Ministry of Education and Science (MEC) with the projects “Interoperabilidad en redes de sensores marinos y ambientales” CTM2008-04517/MAR and “Prototipo preliminar de Observatorio Submarino Expandible Cableado” EMSO CAC-2007-09

We consider a doubly-fed induction machine –controlled through the rotor voltage and connected to a variable local load- that acts as an energy-switching device between a local prime mover (a flywheel) and the electrical power network. The control objective is to optimally regulate the power flow which is achieved commuting between two different steady-state regimes. We first show that zero dynamics of the system is only marginally stable complicating its control via feedback linearization. Instead, we apply the energy-based Interconnection and Damping Assignment Passivity-Based Control technique that does not require stable invertibility. It is shown that the partial differential equation that appears in this method can be obviated fixing the desired closed-loop total energy and adding new terms to the interconnection structure. Furthermore, to obtain a globally defined control law we introduce a state-dependent damping term that has the nice interpretation of effectively decoupling the electrical and mechanical parts of the system. This results in a globally asymptotically stabilizing controller parameterized by two degrees of freedom, which can be used to implement the power management policy. An indirect adaptive scheme for the rotor and stator resistances is also introduced. The controller is simulated and shown to work satisfactorily for various realistic load changes.

L’objectiu del treball realitzat consisteix en la comparació de dos dels programae comercials de mètodes numérics més utilitzats fins el moment, FLAC i PLAXIS, per al cas particular de l’anàlisi de tensió-deformació de la construcció de preses de terra, i del problema de fluxe. Las diferències en la seva estructura interna –FLAC és un programa basat en diferències finites, que utilitza el métode de solución explícita, mentre que PLAXIS está basat en elementos finits, que utiliza el métode de solució implícita-, com en la filosofía i antecedents amb el que foren creats, fan que la comparació no sigui evident

"Remote Monitorization and supervision of airfields and heliports: Equipment and terminal systems" attempt to introduce, through three different levels, the minimum equipment needed to implement a remote control tower. The present project is developed because of the economic lost cause by little airports a heliports, considering that up to now their maintenance have not been profitable enough due to the lack of air traffic. To avoid the loss of this centers and at the same time reduce and optimize their costs, it is suggested (or we suggest) the idea of placing a remote control tower in the university center of Castelldefels (EETAC). The already mentioned tower should be in charge of centralizing (centralize US) the whole air traffic of Cataluña, with the exception of the big airports such as Barcelona, El Prat. This way, it would not be necessary neither to build a remote control tower in each of the centers nor to maintain air traffic controllers in different towers simultaneously, because the same job would be performed just from one location. To that end, the project is divided in three distinguish parts depending on the wished communication quality (as the project moves forward the quality and quantity of the data transmitted increases). At the same time, each one of the chapters is divided into two parts. Within them it can be found the needed equipment in the remote control tower and the elements that must be installed in the on the same flight Center in order to receive and transmit data so that afterwards could be analyzed. All the equipment entered during the project accomplishes the minimum requirements to successfully fulfil the communication between the center and the tower, even though, alternative equipment with the same technical characteristics can be select.