Motion-Based Design of Passive Damping Devices to Mitigate Wind-Induced Vibrations in Stay Cables

Wind action can induce large amplitude vibrations in the stay cables of bridges. To reduce the vibration level of these structural elements, different types of passive damping devices are usually installed. In this paper, a motion-based design method is proposed and implemented in order to achieve the optimum design of different passive damping devices for stay cables under wind action. According to this method, the design problem is transformed into an optimization problem. Thus, its main aim is to minimize the different terms of a multi-objective function, considering as design variables the characteristic parameters of each considered passive damping device. The multi-objective function is defined in terms of the scaled characteristic parameters, one single-function for each parameter, and an additional function that checks the compliance of the considered design criterion. Genetic algorithms are considered as a global optimization method. Three passive damping devices have been studied herein: viscous, elastomeric and friction dampers. As a benchmark structure, the Alamillo bridge (Seville, Spain), is considered in order to validate the performance of the proposed method. Finally, the parameters of the damping devices designed according to this proposal are successfully compared with the results provided by a conventional design method

Effect of Vinyl Flooring on the Modal Properties of a Steel Footbridge

Damping ratios associated with non structural elements play an important role in mitigating the pedestrian-induced vibrations of slender footbridges. In particular, this paper analyses the effect of vinyl flooring on the modal parameters of steel footbridges. Motivated by the unexpected high experimental damping ratios of the first vibration modes of a real footbridge, whose deck was covered by a vinyl flooring, this paper aims at assessing more accurately the experimental damping ratios generated by this non-structural element on steel footbridges. For this purpose, a laboratory footbridge was built and vinyl flooring was installed on it. Its numerical and experimental modal parameters without and with the vinyl flooring were determined. The operational modal analysis method was used to estimate experimentally the modal parameters of the structure. The damping ratios associated with the vinyl flooring were obtained via the substraction between the experimental damping ratios of the laboratory footbridge with and without the vinyl flooring. An average increase of the damping ratios of 2.069% was observed due to the vinyl flooring installed. According to this result, this type of pavement may be a useful tool to significantly increase the damping ratios of steel footbridges in order to reduce pedestrian-induced vibrationsMinisterio de Economía y Competitividad DPI2014-53947-RFondo Europeo de Desarrollo Regional DPI2014-53947-

A crowd-structure interaction model to analyze the lateral lock-in phenomenon on footbridges

In this paper a simplified biomechanical crowd-structure interaction model is proposed and validated in order to analyse the lateral lock-in phenomenon on real footbridges. The proposed crowd-structure interaction model is organized in three levels: (i) pedestrian-structure interaction; (ii) interaction among pedestrians in the crowd; and (iii) interaction between the crowd and the structure. To this end, first, the human-structure interaction of each pedestrian is modelled via a simplified two degrees of freedom system. Second, the interaction among pedestrians inside the crowd is simulated using a multi-agent model. The considered model simulates the movement of each pedestrian from the dynamic equilibrium of the different social forces that act on him/her. Finally, the crowd-structure interaction is achieved modifying the behaviour of the pedestrians depending on the comfort level experienced. For this purpose, the recommendations established by the French standards have been considered. The integration of the three levels in an overall model is achieved by the implementation of a predictive– corrective method. The performance of the proposed model is validated correlating the numerical and experimental dynamic response of the Pedro e Inês footbridge during the development of a lateral lock-in pedestrian test. As the first lateral natural frequency of the footbridge is inside the range that characterizes the walking pedestrian step frequency in lateral direction, numerical and experimental studies were performed to analyse its behaviour under pedestrian action. The agreement between the numerical and experimental results is adequate. However, further studies are recommended in order to generalize the proposed approach and facilitate its use during the design project of future footbridges.Ministerio de Ciencia DPI2014-53947-

Contribution of a pumped-storage hydropower plant to reduce the scheduling costs of an isolated power system with high wind power penetration

AbstractThe paper aims at demonstrating that the consideration of constant start-up costs and ramps of the thermal generating units for assessing the contribution of pumped-hydro energy storage to reduce the scheduling costs of hydrothermal power systems with high wind penetration, may yield unrealistic results. For this purpose, an isolated power system is used as a case study. The contribution of a pumped-storage hydropower plant to reduce the system scheduling costs is assessed in the paper by using a hydrothermal weekly unit commitment model. The model considers different start-up costs and ramps of the thermal generating units as a function of the start-up type. The effects of including pumped hydro energy storage in the system on the integration of wind energy, and on the start-ups and capacity factors of the thermal generating units are also evaluated. The results of the paper demonstrate that the consideration of constant start-up costs and ramps of the thermal generating units yields unrealistic results, and that the pumped-storage hydropower plant may help reduce the system scheduling costs by 2.5–11% and integrate wind power and may allow dispensing with some inflexible thermal generating units

Estimating robust optimum parameters of tuned mass dampers using multiobjective genetic algorithms

Congreso celebrado en la Escuela de Arquitectura de la Universidad de Sevilla desde el 24 hasta el 26 de junio de 2015.Tuned mass dampers (TMD) are a well-known control device widely used to control the vibratory problem originated by the pedestrian action on footbridges. The main purpose of this study is the robust multi-objective optimization design of a TMD using genetic algorithms to control the structural vibrations of a footbridge due to the pedestrian action. The performance of the TMD has been improved designing optimally its parameters, including, mass, stiffness and damping ratio using multiobjective genetic algorithms. Moreover, in order to take into account the uncertainties existing in the system, a robust design optimization procedure has been performed. As an example, a slender steel footbridge, modelled by 3-D frame elements, is used to assess numerically the performance and accuracy of the proposed method. The pedestrian action has been simulated by an equivalent harmonic force. The proposed approach is compared with the classical Den Hartog's proposal. This comparison shows that this approach is more effective than the classica l reported method and more feasible due to the smaller TMD parameters

Motion-Based Design of Passive Damping Systems to Reduce Wind-Induced Vibrations of Stay Cables under Uncertainty Conditions

Stay cables exhibit both great slenderness and low damping, which make them sensitive to resonant phenomena induced by the dynamic character of external actions. Furthermore, for these same reasons, their modal properties may vary significantly while in service due to the modification of the operational and environmental conditions. In order to cope with these two limitations, passive damping devices are usually installed at these structural systems. Robust design methods are thus mandatory in order to ensure the adequate behavior of the stay cables without compromising the budget of the passive control systems. To this end, a motion-based design method under uncertainty conditions is proposed and further implemented in this paper. In particular, the proposal focuses on the robust design of di erent passive damping devices when they are employed to control the response of stay cables under wind-induced vibrations. The proposed method transforms the design problem into a constrained multi-objective optimization problem, where the objective function is defined in terms of the characteristic parameters of the passive damping device, together with an inequality constraint aimed at guaranteeing the serviceability limit state of the structure. The performance of the proposed method was validated via its application to a benchmark structure with vibratory problems: The longest stay cable of the Alamillo bridge (Seville, Spain) was adopted for this purpose. Three di erent passive damping devices are considered herein, namely: (i) viscous; (ii) elastomeric; and (iii) frictions dampers. The results obtained by the proposed approach are analyzed and further compared with those provided by a conventional method adopted in the Standards. This comparison illustrates how the newly proposed method allows reduction of the cost of the three types of passive damping devices considered in this study without compromising the performance of the structure.Ministerio de Ciencia, Innovación y Universidades RT12018-099639-B-I00Universidad de Sevilla USE-17047-

Improving the efficiency of multicore systems through software and hardware cooperation

Increasing processors' clock frequency has traditionally been one of the largest drivers of performance improvements for computing systems. In the first half of the 2000s, however, it became clear that continuing to increase frequency was not a viable solution anymore. Power consumption and power density became prohibitively costly, and processor manufacturers moved to multicore designs. This new paradigm introduced multiple challenges not present in single-threaded processors. Applications running on multicore systems share different resources such as the cache hierarchy and the memory bus. Resource sharing occurs at much finer degree when cores support multithreading as well. In this case, applications share the processor¿s pipeline too. Running multiple applications on the same processor allows for better utilization of its resources¿which otherwise may just lie idle if an application does not use them. But sharing resources may create interferences between applications running on the system. While the degree of these interferences depends on the nature of the applications, it is typically desirable to reduce them in order to improve efficiency. Most currently available processors expose a set of sensors and actuators that software can use to monitor and control resource sharing among the applications running on a system. But it is typically up to end users to analyze their workloads of interest and to manually use the actuators provided by the processor. Because of this, in many cases the different mechanisms for controlling resource sharing are simply left unused. In this thesis we present different techniques that rely on software/hardware interaction to monitor and improve application interference¿and thus improve system efficiency. First we conduct a quantitative study showing the benefits of hardware/software cooperation on system efficiency. Then we narrow our focus on a given hardware knob: data prefetching. Specifically we develop and evaluate several adaptive solutions for improving the efficiency of hardware data prefetching on multicore systems. The impact of the solutions presented in this thesis, however, goes beyond the particular case of data prefetching. They serve as illustrative examples for developing software/hardware cooperation schemes that enable the efficient sharing of resources in multicore systems.L'increment de la freqüència dels processadors ha estat tradicionalment un dels majors responsables de la millora de rendiment dels sistemes de computació. Tanmateix, a la primera meitat del segle XXI es va fer evident que continuar incrementant la freqüència ja no era una solució viable. El consum de potència i la densitat de potència van esdevenir massa costosos, i els dissenyadors de processadors van adoptar dissenys "multicore". Aquest nou paradigma va introduir molts reptes que no eren presents als processadors "single-threaded". Les aplicacions que s'executen a processadors multicore comparteixen diferent recursos tal i com la jerarquia de "cache" i el bus de memòria. En processadors que suporten "multi-threading" encara comparteixen més recursos: en aquest cas les aplicacions també comparteixen els recursos del "pipeline". Executar diverses aplicacions en un processador permet una millor utilització dels seus recursos, que d'altra forma podrien no tenir cap utilitat si l'aplicació en execució no els utilitzés. Compartir recursos, però, pot crear interferències entre les aplicacions executant-se al sistema. Encara que el nivell d'aquestes interferències depèn de les aplicacions que s'executen conjuntament, normalment és desitjable reduir-les per tal de millorar la eficiència. Molts dels processadors actuals exposen un conjunt sensors i actuadors que el software pot utilitzar per supervisar i controlar la compartició de recursos entre les diferents aplicacions executant-se al sistema. En general és responsabilitat dels usuaris analitzar les aplicacions del seu interès i després configurar els actuadors de forma manual. Això suposa una dificultat afegida i per aquest motiu, en molts casos els diferents mecanismes per controlar com es comparteixen els recursos senzillament no es fan servir. En aquesta tesi, presentem diferents tècniques basades en la interacció del software i el hardware per supervisar i reduir la interferència entre aplicacions, i d'aquesta forma millorar la eficiència del sistema. Primer es presenta un estudi quantitatiu que mostra els beneficis de la cooperació entre software i hardware en la eficiència del sistema. Després el focus es centra en un actuador en concret: "data prefetching". En concret, desenvolupem i avaluem diferents solucions adaptatives per millorar la eficiència de hardware data prefetching a sistemes multicore. L'impacte de les solucions presentades a aquesta tesi, però, no es limiten a aquest cas concret. Al contrari, serveixen com exemples il·lustratius per desenvolupar tècniques de cooperació software i hardware que permetin compartir els recursos en sistemes multicore de forma eficient. La compartició de recursos en un processador és un factor crucial que afecta significativament a la seva eficiència. Però, altres nivells d'un sistema de computació també comparteixen recursos. En grans instal·lacions de computació com els "datacenters", les aplicacions també poden compartir altres recursos com la xarxa o l'emmagatzemament. Com a cas d'estudi considerem el disseny d'un sistema d'un sistema de comptabilitat d'energia basat en la cooperació entre el software i el hardware per a grans instal·lacions de computació. En aquest context, explorem diverses alternatives per als sensors i actuadors que es requereixen, així com també analitzem els diferents aspectes claus en el disseny d'un sistema d'aquestes característiques

Plan de empresa: 3GO Sports

Tras el parón provocado por la pandemia del Covid-19 el sector del deporte está experimentando un crecimiento acelerado. Paralelamente, se ha dado una inversión del “éxodo rural”, convirtiendo a las localidades rurales en organismos sociales más independientes de grandes municipios o ciudades vecinas. Es en este contexto donde el deporte rural adquiere relevancia como caldo de cultivo para el desarrollo de nuevos modelos de negocio. Si bien no podemos determinar la inversión total en infraestructura deportiva municipal que existe actualmente en forma de instalaciones deportivas en todo el territorio nacional, existen casi 80.000 instalaciones deportivas (Ministerio de Educación, Cultura y Deporte, 2022) y se estima que los ayuntamientos de grandes ciudades gastan en mantenimiento 24 millones de euros anuales (Eroski, 2019). Aunque estos datos no pueden extrapolarse al entorno rural, sí que es evidente que existe una inversión continuada en materia de infraestructura deportiva. Inversión que no necesariamente responde a una demanda concreta. Actualmente, la celebración de eventos para particulares se oferta prácticamente en su totalidad bajo demanda, es decir, existen empresas especializadas en la creación de eventos deportivos a gusto del consumidor. Su modelo de negocio se basa en la organización del evento y en la gestión de la infraestructura propia, o de la gestión para subcontratarla. Las empresas dedicadas a ofertar eventos se dedican en su mayoría a la celebración de carreras populares, o eventos concretos con un nombre definido, pero no proyectan una imagen de marca independiente del nombre del evento. En este contexto, surge el modelo de negocio de 3GO Sports, para apostar por un sector en crecimiento, con el objetivo de aprovechar una infraestructura existente en un entorno que actualmente se ve favorecido, pero que se enfrenta al llamado “reto demográfico”: despoblación, caída de la natalidad, sobrepoblación estacional.Grado en Comerci