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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

The notion of Control in Complex Systems has started almost 60 years ago by Kalman. However, the results obtained were not sufficient for systems with complex topologies (Complex Networks) and non-linear dynamics. Thanks to many works and especially the one of Liu et.al. on 2011, the topic of Control in Complex networks has returned to the forefront and has been studied intensively during the last decade. Big progress has been made, but still there are many different aspects unsolved in the area. Different notions like structural controllability or required energy to control a network have been imported, but a unifying framework between Complex Systems and Control Theory is still missing, as non-linearity, complexity and dimensionality make it difficult and very often infeasible to extract general and unifying conclusions about this kind of systems. In this work we explore the dynamical properties of the Kuramoto model, focusing the theoretical analysis on the Star-Graph topology taking into consideration the original Kuramoto model, as well as a perturbed expansion of it. Then, a candidate control Lyapunov function is proposed and together with the rest of the theoretical results, is validated by performing various numerical simulations and deploying Model Predictive Control for the controlled cases.

© 2022 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Searching for achieving an ambitious reduction in greenhouse gas emissions, the EU has set as a goal a modal shift in freight transport of 30% by rail for the near future. In this context, it is vital to use modal choice models road versus rail to assess the shippers' acceptance of the actions promoting the use of rail. This paper develops a combined model for jointly evaluating modal split and railway freight ows, addressed to the case when a modal split based on a random utility model is available, and some of its coe -cients may present a non-negligible variability. To this end, after the initial deterministic formulation a robust counterpart of the model is developed. The model, formulated as a non-linear integer programming problem, is oriented to a multi-carrier environment and includes constraints to consider the interactions between the di erent types of ows on the railway network, allowing a good evaluation of the cost types of the carriers and the network capacity. An algorithmic solution based on the outer approximation method is shown to provide accurate solutions in a reasonable computational time for the robust and non-robust versions of the model. Examples centered on a section of the Trans-European Transport Network, the TEN-T Core network corridors, are reported to test the model's applicability. Results show that this model can be a helpful tool for analyzing the possible shippers' response to the di erent railway carriers' services competing with the road.

Treballs Finals de Grau en Estadística UB-UPC, Facultat d'Economia i Empresa (UB) i Facultat de Matemàtiques i Estadística (UPC), Curs: 2020-2021, Tutor: Ramón Alemany i Ernest Pons, El desenvolupament de noves tecnologies creix a un ritme exponencial, els casos en els quals un o varis ordinadors, poden substituir el treball humà són cada cop més freqüents. Històricament els oficis que les màquines podien substituir a l’humà es basaven únicament en tasques manuals i que col·loquialment parlant, requereixen poc recurs intel·lectual. L’ús de softwares automàtics per replicar càlculs complexos s’apliquen en incomptables sectors. Els bots de trading son un clar exemple de software que pot substituir el treball humà més manual i de càlcul per a poder automatitzar processos estratègics per a prendre decisions. En l’actualitat existeixen molts bots de trading operatius, reservats a un públic molt selecte i operant de forma privada. El trading ja de per si és una activitat molt arriscada, i si es barreja amb el món dels criptoactius parlar de risc és un eufemisme de la realitat. Els criptoactius sorgeixen fa 10 anys de mà de Satoshi Nakamoto, un geni de la criptografia que desenvolupa un mètode de pagament descentralitzat que més endavant resulta en el mercat més especulatiu de la historia. La implementació d’un bot en aquests mercats pot donar vertigen, però te tota una sèrie d’avantatges a les que cal parar l’atenció. El fàcil accés i el no requeriment d’un dipòsit ni volums mínims d’operació sumat a l’horari de negociació sense stop, permeten a qualsevol trader tant expert com amateur operar a qualsevol hora del dia i des de qualsevol dispositiu sense requerir grans capitals.

UPC is a technical university that only provides studies in the STEM (Science, Technology, Engineering and Mathematics) area. Currently, it is unlawful for universities and colleges to discriminate against students with disabilities (which includes those on the autistic spectrum disorder, ASD) by treating them less favorably. MEET-UP is a support program at the UPC designed to fulfill this legal duty. Rules and strategies have been designed at the UPC for making 'reasonable adjustments' so that students with ASD are not put at a substantial disadvantage and ensuring that ASD students can fully participate in all aspects of studying, including education and other benefits such as social activities and the use of student facilities and services. COVID-19 has affected many aspects of university and MEET-UP program has evolved to mitigate negative effects on ASD students. First of all, we wish to thank the students who enrolled in the MEET-UP pilot project for their courage and strength. We also wish to thank, the members of the local Autism Spectrum Association and the UPC staff for their invaluable help and commitment with the project.This research was funded by TRA2016-76914-C3-1-P Spanish R+D Programs and by Secretaria d’Universitats-i-RecercaGeneralitat de Catalunya- 2017-SGR- 1749.

Renewable and distributed energy sources, with photovoltaic in the first place, are leading the energy transition. However, they alone will hardly find the way to success in this challenge because of their intrinsic limitations, such as their dependency on weather condition and the unpredictability of their production. Demand Response services are considered crucial for the integration of renewable sources in the grid. This study presents a methodology to evaluate potential flexibility in commercial buildings by managing air conditioning and lighting systems of the site. The study proposes two different data-driven approaches to evaluate flexibility depending on the technology considered. For lighting systems, flexibility is evaluated using the XGBoost classification algorithm combined with a piecewise function. The thermal behavior of the building is modeled with a simplified RC equivalent state-space model. For both algorithms, preprocessing showed to be a critical part of the process, which is explained stage-by-stage in the paper. Results show that the lighting flexibility algorithm is very reliable, reaching an average error of less than 1 % during the months considered. The simplified thermal modeling proposed shows promising results, having less than 0.2 o C of RMSE error for the internal temperature forecast. In addition, results show the flexibility potentiality of the building, which is potentially able to shift up to 23 % of its power consumption during certain hours of the day. This opens huge opportunities for taking advantage from dynamic tariffs, increase self-consumption from renewable sources or participate in flexibility markets to reduce buildings' electricity bill and help renewable integration.

In vibration control of compound structures, inter-substructure damper (ISSD) systemsexploit the out-of-phase response of different substructures to dissipate the kinetic vibrationalenergy by means of inter-substructure damping links. For seismic protection of multistory buildings,distributed sets of interstory fluid viscous dampers (FVDs) are ISSD systems of particular interest.The connections between distributed FVD systems and decentralized static output-feedbackcontrol allow using advanced controller-design methodologies to obtain passive ISSD systemswith high-performance characteristics. A major issue of that approach is the computationaldifficulties associated to the numerical solution of optimization problems with structured bilinearmatrix inequality constraints. In this work, we present a novel iterative linear matrix inequalityprocedure that can be applied to obtain enhanced suboptimal solutions for that kind of optimizationproblems. To demonstrate the effectiveness of the proposed methodology, we design a system ofsupplementary interstory FVDs for the seismic protection of a five-story building by synthesizing adecentralized static velocity-feedback H&yen, controller. In the performance assessment, we compare thefrequency-domain and time-domain responses of the designed FVD system with the behavior of theoptimal static state-feedback H&yen, controller. The obtained results indicate that the proposed approachallows designing passive ISSD systems that are capable to match the level of performance attained byoptimal state-feedback active controllers.

En aquesta tesi proposem un nou sistema per localitzar d'objectes amb sensors tàctils per a robòtica de manipulació, que tracta, de forma explícita, la incertesa inherent al sentit del tacte. Amb aquesta fi, estimem la completa distribució de probabilitat de la posició de l'objecte. A més a més, donat el model 3D de l'objecte en qüestió, el nostre sistema no requereix una exploració prèvia de l'objecte amb el sensor, podent localizar-lo des del primer contacte. Donat un senyal provinent del sensor tàctil, dividim l'estimació de la distribució de probabilitat de la posició de l'objecte en dos passos. Primer, abans de tocar l'objecte, definim un conjunt dens de posicions de l'objecte respecte al sensor, simulem el senyal que esperaríem rebre del sensor si l'objecte fos tocat en aquestes posicions, i entrenem una funció de semblança entre aquests senyals. Segon, mentre l'objecte està sent manipulat, comparem el senyal provinent del sensor amb els senyals simulats prèviament, i les semblances entre aquests donen la distribució de probabilitat discreta a l'espai de posicions de l'objecte respecte al sensor. Estenem aquesta feina analitzant l'escenari on múltiples sensors tàctils toquen l'objecte a la vegada. Fusionem les distribucions de probabilitat provinents dels diferents sensors per obtenir una distribució millor. Presentem resultats quantitatius per quatre objectes. També mostrem una aplicació d'aquest sistema en un sistema més gran i presentem recerca en la qual estem treballant actualment en percepció activa. En esta tesis proponemos un nuevos sistema para localizar objetos con sensores táctiles para robótica de manipulación, que trata, de forma explícita, la incertidumbre inherente al sentido del tacto. Con este fin, estimamos la completa distribución de probabilidad de la posición del objeto. Además, dado el modelo 3D del objeto que cuestión, nuestro sistema no requiere una exploración previa del objeto con el sensor, pudiendo localizarlo desde el primer contacto. Dada una señal proveniente del sensor táctil, dividimos la estimación de la distribución de probabilidad de la posición del objeto en dos pasos. Primero, antes de tocar el objeto, definimos un conjunto denso de posiciones del objeto respecto al sensor, simulamos la señal que esperaríamos recibir del sensor si el objeto fuese tocado en estas posiciones, y entrenamos una función de semejanza entre estas señales. Segundo, mientras el objeto está siendo manipulado, comparamos la señal proveniente del sensor con las señales simuladas previamente, y las semejanzas entre estas dan la distribución de probabilidad discreta en el espacio de posiciones del objeto respecto al sensor. Extendemos este trabajo analizando el escenario donde múltiples sensores táctiles tocan el objeto al mismo tiempo. Fusionamos las distribuciones de probabilidad que vienen de los diferentes sensores para obtener una distribución mejor. Presentamos resultados cuantitativos para cuatro objetos. También mostramos una aplicación de este sistema en un sistema más grande y presentamos investigación en la que estamos trabajando actualmente en percepción activa. In this thesis we present an approach to object tactile localization for robotic manipulation which explicitly deals with the uncertainty to overcome the locality of tactile sensing. To that purpose, we estimate full probability distributions of object pose. Moreover, given a 3D model of the object in question, our framework localizes from the first touch, meaning no physical exploration of the object is needed beforehand. Given a signal from the tactile sensor, we divide the estimation of a probability distribution of object pose in two main steps. First, before touching the object, we sample a dense set of poses of the object with respect to the sensor, we simulate the signal the sensor would get when touching the object at these poses, and we train a similarity function between these signals. In the second part, while manipulating the object, we compare the signal coming from the sensor to the set of previously simulated ones, and the similarities between these give the discretized probability distribution over the possible poses of the object with respect to the sensor. We extend this work by analyzing the scenario where multiple tactile sensors are touching the object at the same time, by fusing the probability distributions coming from the individual sensors to get a better distribution. We present quantitative results for four objects. We also present the application of this approach in a larger system and an ongoing research direction towards tactile active perception. Outgoing

The classification of invariant subspaces is an open problem related to other important ones like the Carlson problem. Here we obtain a reduced form of these invariant subspaces as a new tool to tackle these problems. In particular, it allows us to prove quite easily partial results already known. The key point is assigning to each invariant subspace a marked one (its marked type) in order to partition the set of invariant subspaces in a finite number of subsets (the marked classes), each one containing only one marked subspace. Next, we parametrize (minimally) each marked class by means of the so-called PM reduced families, so that representatives of an invariant subspace (its PM reduced forms) appear in just one of these families.

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.

In this paper, we investigate the design of distributed damping systems (DDSs) for the overall seismic protection of multiple adjacent buildings. The considered DDSs contain interstory dampers implemented inside the buildings and also interbuilding damping links. The design objectives include mitigating the buildings seismic response by reducing the interstory-drift and story-acceleration peak-values and producing small interbuilding approachings to decrease the risk of interbuilding collisions. Designing high-performance DDS configurations requires determining convenient damper positions and computing proper values for the damper parameters. That allocation-tuning optimization problem can pose serious computational difficulties for large-scale multibuilding systems. The design methodology proposed in this work&mdash, (i) is based on an effective matrix formulation of the damped multibuilding system, (ii) follows an H &infin, approach to define an objective function with fast-evaluation characteristics, (iii) exploits the computational advantages of the current state-of-the-art genetic algorithm solvers, including the usage of hybrid discrete-continuous optimization and parallel computing, and (iv) allows setting actuation schemes of particular interest such as full-linked configurations or nonactuated buildings. To illustrate the main features of the presented methodology, we consider a system of five adjacent multistory buildings and design three full-linked DDS configurations with a different number of actuated buildings. The obtained results confirm the flexibility and effectiveness of the proposed design approach and demonstrate the high-performance characteristics of the devised DDS configurations.

Hysteresis is a special type of behavior found in many areas including magnetism, mechanics, bi-ology, economics, etc. One of the characteristics of hysteresis systems is that they are approximatelyrate independent for slow inputs. It is possible to express this characteristic in mathematical languageby decomposing hysteresis operators as the sum of a rate independent component and a nonhystereticcomponent which vanishes in steady state for slow inputs. This decomposition -calledcanonical decom-position- is possible for a class of hysteresis operators for which a continuous input leads to a continuousoutput and a continuous hysteresis loop. The canonical decomposition can be obtained using the conceptofcon uencewhich is an equation that continuous hysteresis operators should verify.On the other hand, hysteresis systems are causal which means that their output depends on the currentand/or previous values of the input but not on the future values of that input. Are the components ofthe canonical decomposition also causal? The answer is en general negative. The lack of causalityof these components means that they cannot be written in the form of differential equations, integro-differential equations, partial differential equations, partial integro-differential equations and many otheruseful structures.This paper proposes a new decomposition of hysteresis operators calledcausal canonical decompositionin which the rate independent component and the nonhysteretic component are both causal. The maintool to obtain the causal canonical decomposition is a new mathematical equation that we calluniformcon uence. Using this equation we show that the causal canonical decomposition is unique. The conceptsintroduced in the paper are applied to the hysteretic scalar semilinear Duhem model as a case study.

Static output-feedback (SOF) controllers are particularly interesting for vibration control of complex structures under a multiactuation scheme. In this chapter, we present a novel iterative linear matrix inequality computational procedure that allows designing high-performance SOF controllers for vibration control of multistory buildings equipped with a distributed set of interstory actuators. The effectiveness of the proposed methodology is illustrated by designing an SOF H-infinity controller for the seismic protection of a 20-story building equipped with a complete set of interstory actuators and a system of collocated interstory-velocity sensors. Numerical simulations of the building response using a near-fault impulsive-type seismic disturbance demonstrate the high-performance characteristics of the obtained SOF controller and its robustness against broadband seismic excitations. This work was partially supported by the Spanish Ministry of Economy and Competitiveness under Grant DPI2015-64170-R (MINECO/FEDER).

L’objectiu d’aquesta tesi és l’anàlisi i el control d’un sistema de Lur’e, és a dir, un sistema amb un camí directe lineal i invariant en el temps i amb una realimentació no lineal estàtica, amb restriccions de sector i de pendent en les seves no-linealitats. Aquesta descripció engloba una àmplia classe de sistemes que apareixen comunament en una àmplia gamma de disciplines d’enginyeria. L’enfocament d’aquest treball es basa en la teoria d’estabilitat de Lyapunov i utilitza desigualtats de matrius lineals per proposar criteris per a l’estabilitat absoluta del sistema i els guanys l2 i RMS, i desigualtats de matrius bilineals per proposar criteris per al seu control per realimentació d’estat i estimació d’estat. Aquest tipus de condicions, en particular les desigualtats de matrius lineals, són convenients de tractar computacionalment, ja que els problemes d’optimització a que donen lloc són convexos. S’obtenen resultats numèrics per a diversos exemples, els quals mostren una millora significativa respecte a les condicions anteriors de la literatura. El objetivo de esta tesis es el análisis y el control de un sistema de Lur’e, es decir, un sistema con un camino directo lineal e invariante en el tiempo y con una realimentación no lineal estática, con restricciones de sector y de pendiente en sus no-linealidades. Esta de- scripción engloba una amplia clase de sistemas que aparecen comúnmente en una amplia gama de disciplinas de ingeniería. El enfoque de este trabajo se basa en la teoría de estabilidad de Lyapunov y utiliza desigualdades de matrices lineales para proponer criterios para la estabil- idad absoluta del sistema y las ganancias l2 y RMS, y desigualdades de matrices bilineales para proponer criterios para su control por realimentación de estado y estimación de estado. Este tipo de condiciones, en particular las desigualdades de matrices lineales, son convenientes tratar computacionalmente, ya que los problemas de optimización a que dan lugar son con- vexos. Se obtienen resultados numéricos para varios ejemplos, los cuales muestran una mejora significativa respecto a las condiciones anteriores de la literatura. The aim of this thesis is to analyze and control a Lur’e system, i.e., a system with a linear time-invariant forward path and a nonlinear static feedback with sector and slope constraints on its nonlinearities. This description encompasses a broad class of systems that commonly arise in a wide range of engineering disciplines. The approach of this work is based on Lyapunov stability theory and uses linear matrix inequalities to propose criteria for the system’s absolute stability and l2- and RMS-gains, and bilinear matrix inequalities to propose criteria for state feedback control and state estimation. These types of conditions, in particular linear matrix inequalities, are conveniently treated computationally, as the optimization problems that they give rise to are convex. Numerical results are obtained for several examples, showing a significant improvement with respect to previous conditions in the literature. Outgoing

We tackle the obtaining of canonical forms for classifying linear control systems with regard to changes in the state variables. Although it was solved in the 1980s for controllable systems, it is still an open problem for the general case of multiparametric non-necessarily controllable systems. Here we obtain a general reduced form which is canonical for a class of systems which includes the cases already known (uniparametric systems, controllable systems)

Acute liver injury; Antidepressants; Case-control Lesió hepàtica aguda; Antidepressius; Control de casos Lesión hepática aguda; Antidepresivos; Control de casos Background Agomelatine is a melatonin receptor agonist and serotonin 5-HT2C receptor antagonist indicated for depression in adults. Hepatotoxic reactions like acute liver injury (ALI) are an identified risk in the European risk management plan for agomelatine. Hepatotoxic reactions have been reported for other antidepressants, but population studies quantifying these risks are scarce. Antidepressants are widely prescribed, and users often have risk factors for ALI (e.g. metabolic syndrome). Objective The goal was to estimate the risk of ALI associated with agomelatine and other antidepressants (fluoxetine, paroxetine, sertraline, escitalopram, mirtazapine, venlafaxine, duloxetine, and amitriptyline) when compared with citalopram in routine clinical practice. Method A nested case–control study was conducted using data sources in Denmark, Germany, Spain, and Sweden (study period 2009–2014). Three ALI endpoints were defined using International Classification of Diseases (ICD) codes: primary (specific codes) and secondary (all codes) endpoints used only hospital discharge codes; the tertiary endpoint included both inpatient and outpatient settings (all codes). Validation of endpoints was implemented. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for current use were estimated for each data source and combined. Results We evaluated 3,238,495 new antidepressant and 74,440 agomelatine users. For the primary endpoint, the OR for agomelatine versus citalopram was 0.48 (CI 0.13–1.71). Results were also

Hysteresis is a complex phenomenon that occurs in many areas of science and engineering. To model hysteresis, scientists combine first laws of physics with fictitious equations to obtain phenomenological models that aim to match the macroscopic behavior of hysteresis processes. In this paper we focus on a model of hysteresis that was proposed by the physicist P. Duhem starting from thermodynamical considerations. On the one hand, we strengthen the results obtained by the mathematician I. Babuška in relation with the existence and uniqueness of a global solutions and of a periodic solution when the input is periodic. On the other hand, we specialize into a specific form of the Duhem model proposed by Babuška. For Babuška’s model we determine the explicit analytic expression of the hysteresis loop. We apply our findings to dry friction modeling and to asymmetric hysteresis loop matching.

© 2020 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ Demand-side flexibility is a promising source of the energy system that might enhance renewable energy penetration and help to democratize the electricity sector. However, it is not clear what is the best strategy to adopt for Demand Aggregators, especially when flexibility is provided by residential and tertiary buildings. This study compares two Demand Aggregators strategies in the framework of the SABINA (H2020) and the REFER research projects and analyses the effect of CO2 prices on the Demand Aggregator business model. Results show that Demand Response activities reduce both the costs and the building CO2 emissions independently from the strategy adopted.

Distributed multi-actuator systems can provide effective solutions for mitigating the vibrational response of large structures. In this paper, we present a computational strategy to design inerter-based multi-actuation systems for the seismic protection of adjacent structures. The proposed approach allows considering both interstory and interbuilding Tuned Mass-Inerter Damper (TMID) actuators, and aims at simultaneously reducing the vibrational response of the individual buildings and avoiding the interbuilding impacts. The tuning procedure is based on an H8 cost-function and uses a constrained global-optimization solver to compute parameter configurations with high-performance characteristics. To illustrate the main features of this work, two different Tuned Inerter Damper (TID) multi-actuator schemes are considered for the seismic protection of a particular multi-story two-building system. A multi-actuator Tuned Mass Damper (TMD) system is also designed and is taken as a reference in the performance assessment. The obtained results demonstrate the flexibility and effectiveness of the proposed design methodology, and clearly show the superior performance and robustness of the TID actuation systems.

Rows of closely adjacent buildings with similar dynamic characteristics are common building arrangements in residential areas. In this paper, we present a vibration control strategy for the seismic protection of this kind of multibuilding systems. The proposed approach uses an advanced Linear Matrix Inequality (LMI) computational procedure to carry out the integrated design of distributed multiactuation schemes that combine interbuilding linking devices with interstory actuators implemented at different levels of the buildings. The controller designs are formulated as static output-feedback H-infinity control problems that include the interstory drifts, interbuilding approachings and control efforts as controlled-output variables. The advantages of the LMI computational procedure are also exploited to design a fully-decentralized velocity-feedback controller, which can define a passive control system with high-performance characteristics. The main ideas are presented by means of a system of three adjacent five-story identical buildings, and a proper set of numerical simulations are conducted to demonstrate the behavior of the different control configurations. The obtained results indicate that interstory-interbuilding multiactuation schemes can be used to design effective vibration control systems for adjacent buildings with similar dynamic characteristics. Specifically, this kind of control systems is able to mitigate the vibrational response of the individual buildings while maintaining reduced levels of pounding risk.

While optimization models play a key role in transportation analysis, the objective function to be optimized, however, cannot always be defined analytically. It is therefore necessary to resort to non-differentiable optimization methods that usually pivot on evaluating the objective function. Special cases of particular interest are those in Dynamic OD Estimation, which cannot evaluate the objective analytically and thus the formulation falls within the computational framework of Simulation-Optimization. SPSA is not limited to the inputs from conventional traffic counts and can be easily extended to account for the measurements of traffic variables supplied by emerging sensors exploiting Information and Communication Technologies (ICT). Numerical experiments have been conducted with a real network, and the results have been analyzed from two different perspectives: performance and solution quality. This allows understanding the behavior of the SPSA algorithm and new variants, which altogether contribute to the aim of adding ICT measures in the future. Their sensitivity to the initial values, the effect of bounding the variables and scaling techniques are going to be analyzed. This paper will report on the results of the numerical experiments, their analyses, conclusions and further research.

In this paper, we present an effective computational strategy to design high-performance decentralized controllers with partial local-state information for vibration control of large building structures. Specifically, the building dynamical model is first decomposed into a set of approximate low-dimensional decoupled subsystems subject to the action of generalized disturbances, which include the effect of external physical disturbances, modeling approximation errors and mechanical subsystem interactions. Next, using the approximate decoupled subsystems, an overall structured state-feedback controller is obtained by designing a proper set of independent local controllers. The proposed computational strategy is applied to obtain two structured control systems for the seismic protection of a 35-story building: (i) a fully decentralized velocity-feedback controller with 35 interstory actuators that can be passively implemented by a set of viscous dampers, and (ii) a decentralized velocity-feedback controller with 15 interstory actuators, which can be implemented with a reduced set of collocated sensors and a system of five independent short-range communication networks. To assess the performance of the obtained structured controllers, the corresponding frequency and time responses are investigated and compared with the responses produced by optimal full-state H8H8 controllers. Moreover, to evaluate the effectiveness of the computational procedure, both structured and full-state controllers are designed for a proper set of buildings with different number of stories and the corresponding computation times are recorded and compared. The obtained results show that the computational cost of the proposed design methodology is remarkably low and also indicate that, despite the severe information constraints, the synthesized structured controllers are practically optimal.

The main objective of this study was to introduce a survival model to contemplate two simultaneous accelerating factors affecting a food product's shelf life: temperature and illumination. A second objective was to consider the case where the same consumer tests different experimental conditions and thus his/her data are not independent. Sample data comprised 108 consumers who evaluated a lemon-flavored juice stored at 24 °C, 37 °C and 45 °C; under conditions of no-illumination and with illumination; with seven different storage times for each of the six experimental conditions. Aiming to estimate the storage time at which a consumer rejects a sample a model including an Arrhenius term for the temperature, a binomial response for illumination (with and without) and the interaction of both was developed. The model also considered that the same consumer tested different experimental conditions. Fil: Garitta, Lorena Garitta. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Langohr, Klaus. Universidad Politécnica de Catalunya; España Fil: Elizagoyen, Eliana Soledad. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentina Fil: Gugole Ottaviano, Maria Fernanda. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentina Fil: Gómez, Guadalupe. Universidad Politécnica de Catalunya; España Fil: Hough, Guillermo. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina

Large aeronautical structural parts present important distortions after machining. This problem is caused by the presence of residual stresses, which are developed during previous manufacturing steps (quenching). Before being put into service, the nominal geometry is restored by means of mechanical methods. This operation is called reshaping and exclusively depends on the skills of a well-trained and experienced operator. Moreover, this procedure is time consuming and nowadays, it is only based on a trial and error approach. Therefore, there is a need at industrial level to solve this problem with the support of numerical simulation tools. By using a simplification hypothesis, it was found that the springback phenomenon behaves linearly and it allows developing a strategy to implement reshaping at an industrial level. © 2018 Author(s).

The Monden Problem, also known as the Output Rate Variation Problem, is one of the original formulations for mixed-model assembly line-level scheduling problems in a just-in-time system. In this paper, we develop a new branch-and-bound procedure for the problem that uses several new and previously proposed lower and upper bounds. The algorithm also includes several dominance rules that leverage the symmetry in the problem as well as a new labelling procedure that avoids repeated exploration of previously examined partial solutions. The branching strategy exploits the capabilities of current multiprocessor computers by exploring the search tree in a parallel fashion. The algorithm has been tested on several sets of instances from the literature and is able to optimally solve problems that are double the size of those addressed by other procedures previously reported in the literature.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works A Stewart platform is a kind of parallel robot which can be used for a wide variety of technological and industrial applications. In this paper, a Stewart platform designed and assembled at the Universitat Polit`ecnica de Catalunya (UPC) by our research group is presented. The main objective is to overcome the enormous difficulties that arise when a real-time vision-based control of a fast moving object placed on these mechanisms is required. In addition, a description of its geometric characteristics, the calibration process, together with an illustrative experiment to demonstrate the good behavior of the platform is given.

Preprint Hysteresis is a special type of behavior encountered in physical systems: in a hysteretic system, when the input is periodic and varies slowly, the steady-state part of the output-versus-input graph becomes a loop called hysteresis loop. In the presence of perturbed inputs or noise, this hysteresis loop presents small lobes called minor loops that are located inside a larger curve called major loop. The study of minor loops is being increasingly popular since it leads to a quantification of the loss of energy due to the noise. The aim of the present paper is to give an explicit analytic expression of the minor loops of the LuGre and the Dahl models of dynamic dry friction.

The objective of this work is to present a practical demonstration of the relevant role that can be played by micro-sized wind turbines (µSWTs) in research and education. To this end, we have designed an experimental platform for active magnetic bearing vibration control of a rotary shaft, which provides an excellent illustration of the mechatronical multidomain approach and, at the same time, makes it possible to perform advanced full-scale experimental studies on fundamental aspects of µSWTs, such as vibration control, fault detection or health monitoring. The platform prototype has been designed following the principles of cost-efficiency and limited usage of resources, which can be critical factors for its practical application. To illustrate the effectiveness of the proposed approach, a simple vibration control strategy has been implemented using a low-cost digital microcontroller.

In this paper, we investigate the design and performance of static feedback controllers with partial-state information for the seismic protection of tall buildings equipped with incomplete multi-actuation systems. The proposed approach considers a partially instrumented multi-story building with an incomplete system of interstory force–actuation devices implemented on selected levels of the building, and an associated set of collocated sensors that measure the corresponding interstory drifts and interstory velocities. The main elements of the proposed controller design methodology are presented by means of a twenty-story building equipped with a system of ten interstory actuators arranged in three different layouts: concentrated, semi-distributed and fully-distributed. For these control configurations, partial-state controllers are designed following a static output-feedback H-infinity controller design approach, and the corresponding frequency and time responses are investigated. The obtained results clearly indicate that the proposed partial-state controllers are effective in mitigating the building seismic response. They also show that a suitable distribution of the instrumented stories is a relevant factor in the control system performance.

In this paper, a novel control strategy based on an adaptive Self-Recurrent Wavelet Neural Network (SRWNN) and a sliding mode controller/observer for a slider crank mechanism is proposed. The aim is to reduce the tracking error of the linear displacement of this mechanism while following a specified trajectory. The controller design consists of two parts. The first one is a sliding mode control strategy and the second part is an SRWNN controller. This controller is trained offline first, and then the SRWNN weights are updated online by the adaptive control law. Apart from the hybrid control strategy proposed in this paper, a velocity observer is implemented to replace the use of velocity sensors. The outcomes obtained in the numerical experiment section prove that the smallest tracking error is obtained for the linear and angular displacements in comparison with other strategies found in literature due to the uncertainty and disturbance rejection properties of the sliding mode and the self-recurrent wavelet neural network controllers.

Published version of an article in the journal: Modeling, Identification and Control. Also available from the publisher at: http://dx.doi.org/10.4173/mic.2014.3.4 Open Access In this paper, we present a novel two-step strategy for static output-feedback controller design. In the first step, an optimal state-feedback controller is obtained by means of a linear matrix inequality (LMI) formulation. In the second step, a transformation of the LMI variables is used to derive a suitable LMI formulation for the static output-feedback controller. This design strategy can be applied to a wide range of practical problems, including vibration control of large structures, control of oshore wind turbines, control of automotive suspensions, vehicle driving assistance and disturbance rejection. Moreover, it allows designing decentralized and semi-decentralized static output-feedback controllers by setting a suitable zerononzero structure on the LMI variables. To illustrate the application of the proposed methodology, two centralized static velocity-feedback H∞ controllers and two fully decentralized static velocity-feedback H∞ controllers are designed for the seismic protection of a five-story building.

The design of vibration control systems for the seismic protection of closely adjacent buildings is a complex and challenging problem. In this paper, we consider distributed multi-actuation schemes that combine interbuilding linking elements and interstory actuation devices. Using an advanced static output-feedback H 8 approach, active and passive vibration control systems are designed for a multi-story two-building structure equipped with a selected set of linked and unlinked actuation schemes. To validate the effectiveness of the obtained controllers, the corresponding frequency responses are investigated and a proper set of numerical simulations is conducted using the full scale North–South El Centro 1940 seismic record as ground acceleration disturbance. The observed results indicate that using combined interstory-interbuilding multi-actuation schemes is an effective means of mitigating the vibrational response of the individual buildings and, simultaneously, reducing the risk of interbuilding pounding. These results also point out that passive control systems with high-performance characteristics can be designed using damping elements.

Inerters are a novel type of mechanical actuation devices that are able to produce large inertial forces with a relatively small mass. Due to this property, inerters can provide an effective solution to the main drawbacks of tuned mass-dampers and, consequently, they are gaining an increasing relevance in the field of passive structural vibration control. In this paper, a computational design strategy for inerter-based vibration control schemes is presented. The proposed approach combines a computationally effective reduced-frequency H8 cost-function and a constrained global optimization solver to design different configurations of a shared tuned mass-inerter-damper system for the seismic protection of a multi-story two-building structure. To assess the effectiveness of the obtained configurations, the frequency characteristics and the seismic response of the interstory drifts and interbuilding approaches are investigated with positive results.

It is well known that, when a full rank observable pair (C,A) is slightly perturbed, the new observability indices k′ are majorized by the initial ones k, k≻k′. Conversely, any indices k′ majorized by k can be obtained by perturbing (C,A). The aim of this paper is the explicit construction of perturbations of (C,A) which have the desired indices k′ by means of a sequence of uniparametrical versal perturbations. Even more, using versal deformations we refine this construction in such a way that the perturbation has the maximum possible number of zeros and no parameters in the square part.

Given a general local differentiable family of pairs of matrices, we obtain a local differentiable family of feedbacks solving the pole assignment problem, that is to say, shifting the spectrum into a prefixed one. We point out that no additional hypothesis is needed. In fact, simple approaches work in particular cases (controllable pairs, constancy of the dimension of the controllable subspace, and so on). Here the general case is proved by means of Arnold’s techniques: the key point is to reduce the construction to a versal deformation of the central pair; in fact to a quite singular miniversal one for which the family of feedbacks can be explicitly constructed. As a direct application, a differentiable family of stabilizing feedbacks is obtained, provided that the central pair is stabilizable.

Specific algorithms, such as those involving the supremal of the invariant subspaces contained in a suitable subspace, are known to be able to test whether a disturbance decoupling problem (DDP) is solvable. Here, by reducing the system to its Molinari form, we obtain an alternative description of this supremal object and compute its dimension. Hence we have a general result for solving the decoupling provided that a Molinari basis is known. In particular, a necessary numerical condition for it is derived. The same technique is applied to the DDPS, that is, when stability of the decoupled closed loop system is required.

Given a controllable linear control system defined by a pair of constant matrices (A;B), the set of controllability subspaces is an stratified submanifold of the set of (A;B)-invariant subspaces. We parameterize each strata by means of coordinate charts. This parametrization has significant di®erences to that of (A;B) invariant subspaces, showing a more complex geometric structure.

Matrix pencils under the strict equivalence and matrix pairs under the state feedback equivalence are considered. It is known that a matrix pencil (or a matrix pair) smoothly dependent on parameters can be reduced locally to a special typically more simple form, called the versal deformation, by a smooth change of parameters and a strict equivalence (or feedback equivalence)transformation. We suggest an explicit recurrent procedure for finding the change of parameters and equivalence transformation in the reduction of a given family of matrix pencils (or matrix pairs) to the versal deformation. As an application, this procedure is applied to the analysis of the uncontrollability set in the space of parameters for a one-input linear dynamical system. Explicit formulae for a tangent plane to the uncontrollability set at its regular point and the perturbation of the uncontrollable mode are derived. A physical example is given and studied in detail.

Security and secrecy are some of the important concerns in the communications world. In the last years, several encryption techniques have been proposed in order to improve the secrecy of the information transmitted. Chaos-based encryption techniques are being widely studied as part of the problem because of the highly unpredictable and random-look nature of the chaotic signals. In this paper we propose a digital-based communication system that uses the logistic map which is a mathematically simple model that is chaotic under certain conditions.The input message signal is modulated using a simple Delta modulator and encrypted using a logistic map. The key signal is also encrypted using the same logistic map with different initial conditions. In the receiver side, the binary-coded message is decrypted using the encrypted key signal that is sent through one of the communication channels. The proposed scheme is experimentally tested using Arduino shields which are simple yet powerful development kits that allows for the implementation of the communication system for testing purposes.

We present a geometric approach to the classification of monogenic invariant subspaces, alternative to the classical algebraic one, which allows us to obtain several matricial canonical forms for each class. Some applications are derived: canonical coordinates of a vector with regard to an endomorphism, and a canonical form for uniparametric linear control systems, not necessarily controllable, with regard to linear changes of state variables. Moreover, the pointwise construction can be extended to differentiable families of changes of basis when differentiable families of equivalent monogenic subspaces are considered.

In this work, a coordinate change of state variables is performed for drift-less systems of dimension m+2 with 2 inputs using Goursat Normal Form. Then, we define a feedback law that will allow us to convert the original system into chained form. Later on, we find the flat outputs and define a new feedback law. Finally, numerical simulations are presented for a planar space robot, a mobile robot with a trailer and a N-trailer.

The compilation of results involving feedback linearization and the computation of flat outputs within the framework of exterior differential systems are the focus of our work.

The relation between original and expanded systems within the Inclusion Principle from the point of view of controllability–observability of both subsystems and composite systems is studied. It is proved that complementary matrices always exist ensuring that the subsystems and the overall expanded system are simultaneously controllable–observable. Two practically important large classes of complementary matrices are identified to offer results computationally attractive. First, the existence of complementary matrices ensuring controllability–observability of decoupled subsystems is proved. Then, using this result, the same property is proved for the composite expanded system.

Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2014/510236 Open Access We present a new design strategy that makes it possible to synthesize decentralized output-feedback controllers by solving two successive optimization problems with linear matrix inequality (LMI) constraints. In the initial LMI optimization problem, two auxiliary elements are computed: a standard state-feedback controller, which can be taken as a reference in the performance assessment, and a matrix that facilitates a proper definition of the main LMI optimization problem. Next, by solving the second optimization problem, the output-feedback controller is obtained. The proposed strategy extends recent results in static output-feedback control and can be applied to design complex passive-damping systems for vibrational control of large structures. More precisely, by taking advantages of the existing link between fully decentralized velocity-feedback controllers and passive linear dampers, advanced active feedback control strategies can be used to design complex passive-damping systems, which combine the simplicity and robustness of passive control systems with the efficiency of active feedback control. To demonstrate the effectiveness of the proposed approach, a passive-damping system for the seismic protection of a five-story building is designed with excellent results.

This paper presents a novel controller design strategy, which allows computing static output-feedback controllers by solving two successive linear matrix inequality (LMI) optimization problems. This strategy is conceptually simple, easy to implement, computationally efficient, and it can be potentially applied to a wide variety of control problems, in which effective state-feedback controllers can be synthesized by using standard LMI optimization tools. To illustrate the application of the new approach in the field of structural vibration control of large structures, a static velocity-feedback H1 controller for the seismic protection of a five-story building is designed with excellent results.

This paper provides a direct and practical presentation of a novel methodology for static output feedback controller design. The proposed design strategy has been successfully applied in the fields of control systems for seismic protection of large buildings and multi-building structures, control of offshore wind turbines, and active control of vehicle suspensions. The positive results obtained in these initial applications clearly indicate that this approach could be an effective tool in a large variety of control problems, for which an LMI formulation of the statefeedback version of the problem is available. The main objective of the paper is to facilitate a brief and friendly presentation of the main ideas involved in the new design methodology. To this end, a discrete-time static output-feedback H1 controller is designed for a simplified quarter-car suspension system. Numerical simulations indicate that the proposed controller exhibits a remarkably good behavior when compared with the corresponding statefeedback H1 controller.

Institut de Robòtica i Informàtica Industrial (CSIC-UPC) Mesurar la proximitat a les configuracions singulars dels manipuladors paral·lels pot ser útil per evitar el mal comportament que es dóna quan el manipulador es mou en un entorn d'una singularitat. Alguns dels índexos que s'han introduït fins ara que podrien resoldre aquest problema són poc adequats. En aquest projecte tecnològic s'introdueixen dos nous índexos que són una solució potencial per aquest problema: la distància a la recta polar i l'angle amb el pla singular. Primerament es respassaran alguns conceptes, relacionats amb la Grassmanniana de rectes de l'espai, sobre les configuracions singulars dels manipuladors que seran útils per a definir aquests índexos; a continuació es faran quatre simulacions comparant aquests dos nous índexos amb altres dos que es faran servir com a referència. Finalment s'evaluarà la bondat de totes les mesures a partir dels resultats obtinguts a les simulacions.. De manera anàloga com el projectiu dual parametritza els hiperplans, les rectes de l'espai es poden parametritzar mitjançant una varietat anomenada Grassmanniana. Via la immersió de Plücker, aquesta Grassmanniana es pot veure com una hipersuperfície quàdrica dintre d'un espai projectiu de dimensió 5. L'objectiu és estudiar, des del punt de vista algebraic, propietats geomètriques de la Grassmanniana, que ajuden a entendre les configuracions singulars dels robots paral.lels

In this paper, a new strategy to design static output-feedback controllers for a class of vehicle suspension systems is presented. A theoretical background on recent advances in output-feedback control is first provided, which makes possible an effective synthesis of static output-feedback controllers by solving a single linear matrix inequality optimization problem. Next, a simplified model of a quarter-car suspension system is proposed, taking the ride comfort, suspension stroke, road holding ability, and control effort as the main performance criteria in the vehicle suspension design. The new approach is then used to design a static output-feedbackH∞controller that only uses the suspension deflection and the sprung mass velocity as feedback information. Numerical simulations indicate that, despite the restricted feedback information, this static output-feedbackH∞controller exhibits an excellent behavior in terms of both frequency and time responses, when compared with the corresponding state-feedbackH∞controller.