PhD. thesis is deals about sekond order ARC filters for cascade synthezis of Active filters. Here are presented new configurations of second order filters with current conveyors usable for higher frequencies and new second order filters with current conveyors usable for electrical tunable filters. In PhD. Thesis are presented schematics and equations for new sekond order filters. There are presented also practical realizations of these filters and basic measure results.

The diploma thesis deals with dynamic analysis of cable-stayed steel pedestrian footbridge. The dynamic response of pedestrian-induced vibration was studied. The response of structure exeeded standard acceptance limit. Due to the effect of installed Tuned Mass Damper was studied. Motion equations of single and two degree of freedom model were solved in program MATLAB and the results were compared with numeric model in ANSYS.

El capítulo I presenta una introducción y aspectos generales en base a los antecedentes, realidad problemática, formulación del problema; así como la definición de la hipótesis y los objetivos concluyentes. El capítulo II se realiza el estado del arte basándose en los fundamentos teóricos más importantes en base a la eficiencia de los AMS sometidos a fuerzas o movimientos armónicos en la base; así también describe generalidades en base a la clasificación general de los sistemas de protección sísmica, fundamentos del AMS, y resumen de trabajos relevantes sobre aplicaciones en edificios y otras obras de ingeniería civil. El capítulo III, IV y V se refieren al comportamiento de estructuras sin AMS frente a acciones sísmicas. En particular se analizan las edificaciones existentes reales de 7, 10 y 20 niveles en base al análisis computacional. El capítulo VI presenta los parámetros de diseño de un AMS para tres aplicaciones de edificios reales de 7, 10 y 20 niveles, concluyendo con la determinación de las características óptimas para la construcción y los efectos generados por estas. Finalmente, en el capítulo VII se presentan las principales conclusiones y recomendaciones basadas en la investigación realizada. / Chapter I presents an introduction and general aspects based on the background, problematic reality, formulation of the problem, as well as the definition of the hypothesis and the conclusive objectives. Chapter II the state of the art is made based on the most important theoretical foundations based on the efficiency of the AMS subjected to forces or harmonic movements in the base; it also describes generalities based on the general classification of seismic protection systems, foundations of the AMS, and summary of relevant works on applications in buildings and other civil engineering works. Chapter III, IV and V refers to the behavior of structures without AMS against seismic actions. In particular, the real existing buildings of 7, 10, and 20 levels are analyzed based on the computational analysis. Chapter VI presents the design parameters of an AMS for three applications of real buildings of 7, 10 and 20 levels, concluding with the determination of the optimal characteristics for the construction and the effects generated by these. Finally, Chapter VI presents the main conclusions and recommendations based on the research carried out. / Tesis

Eftersom samhället blir allt mer datadrivet revolutionerar användningen av AI och maskininlärning sättet företag fungerar och utvecklas på. Denna studie utforskar användningen av AI, Big Data och Natural Language Processing (NLP) för att förbättra affärsverksamhet och intelligens i företag. Huvudsyftet med denna avhandling är att undersöka om den nuvarande klassificeringsprocessen hos värdorganisationen kan upprätthållas med minskade driftskostnader, särskilt lägre moln-GPU-kostnader. Detta har potential att förbättra klassificeringsmetoden, förbättra produkten som företaget erbjuder sina kunder på grund av ökad klassificeringsnoggrannhet och stärka deras värdeerbjudande. Vidare utvärderas tre tillvägagångssätt mot varandra och implementationerna visar utvecklingen inom området. Modellerna som jämförs i denna studie inkluderar traditionella maskininlärningsmetoder som Support Vector Machine (SVM) och Logistisk Regression, tillsammans med state-of-the-art transformermodeller som BERT, både Pre-Trained och Fine-Tuned. Artikeln visar att det finns en avvägning mellan prestanda och kostnad vilket illustrerar problemet som många företag, som Valu8, står inför när de utvärderar vilket tillvägagångssätt de ska implementera. Denna avvägning diskuteras och analyseras sedan mer detaljerat för att utforska möjliga kompromisser från varje perspektiv i ett försök att hitta en balanserad lösning som kombinerar prestandaeffektivitet och kostnadseffektivitet. / As society is becoming more data-driven, Artificial Intelligence (AI) and Machine Learning are revolutionizing how companies operate and evolve. This study explores the use of AI, Big Data, and Natural Language Processing (NLP) in improving business operations and intelligence in enterprises. The primary objective of this thesis is to examine if the current classification process at the host company can be maintained with reduced operating costs, specifically lower cloud GPU costs. This can improve the classification method, enhance the product the company offers its customers due to increased classification accuracy, and strengthen its value proposition. Furthermore, three approaches are evaluated against each other, and the implementations showcase the evolution within the field. The models compared in this study include traditional machine learning methods such as Support Vector Machine (SVM) and Logistic Regression, alongside state-of-the-art transformer models like BERT, both Pre-Trained and Fine-Tuned. The paper shows a trade-off between performance and cost, showcasing the problem many companies like Valu8 stand before when evaluating which approach to implement. This trade-off is discussed and analyzed in further detail to explore possible compromises from each perspective to strike a balanced solution that combines performance efficiency and cost-effectiveness.

Metamaterials are typically described as materials with ’unusual’ wave propagation properties. Originally developed for electromagnetic waves, these materials have also spread into the field of acoustic wave guiding and cloaking, with the most relevant of these ’unusual’ properties, being the so called band-gap phenomenon. A band-gap signifies a frequency region where elastic waves cannot propagate through the material, which in principle, could be used to protect buildings from earthquakes. Based on this, two relevant concepts have been proposed in the field of seismic engineering, namely: metabarriers, and metamaterial-based foundations. This thesis deals with the development of the Metafoundation, a metamaterial-based foundation system for the seismic protection of fuel storage tanks against excessive base shear and pipeline rupture. Note that storage tanks have proven to be highly sensitive to earthquakes, can trigger sever economic and environmental consequences in case of failure and were therefore chosen as a superstructure for this study. Furthermore, when tanks are protected with traditional base isolation systems, the resulting horizontal displacements, during seismic action, may become excessively large and subsequently damage connected pipelines. A novel system to protect both, tank and pipeline, could significantly augment the overall safety of industrial plants. With the tank as the primary structure of interest in mind, the Metafoundation was conceived as a locally resonant metamaterial with a band gap encompassing the tanks critical eigenfrequency. The initial design comprised a continuous concrete matrix with embedded resonators and rubber inclusions, which was later reinvented to be a column based structure with steel springs for resonator suspension. After investigating the band-gap phenomenon, a parametric study of the system specifications showed that the horizontal stiffness of the overall foundation is crucial to its functionality, while the superstructure turned out to be non-negligible when tuning the resonators. Furthermore, storage tanks are commonly connected to pipeline system, which can be damaged by the interaction between tank and pipeline during seismic events. Due to the complex and nonlinear response of pipeline systems, the coupled tank-pipeline behaviour becomes increasingly difficult to represent through numerical models, which lead to the experimental study of a foundation-tank-pipeline setup. Under the aid of a hybrid simulation, only the pipeline needed to be represented via a physical substructure, while both tank and Metafoundation were modelled as numerical substrucutres and coupled to the pipeline. The results showed that the foundation can effectively reduce the stresses in the tank and, at the same time, limit the displacements imposed on the pipeline. Leading up on this, an optimization algorithm was developed in the frequency domain, under the consideration of superstructure and ground motion spectrum. The advantages of optimizing in the frequency domain were on the one hand the reduction of computational effort, and on the other hand the consideration of the stochastic nature of the earthquake. Based on this, two different performance indices, investigating interstory drifts and energy dissipation, revealed that neither superstructure nor ground motion can be disregarded when designing a metamaterial-based foundation. Moreover, a 4 m tall optimized foundation, designed to remain elastic when verified with a response spectrum analysis at a return period of 2475 years (according to NTC 2018), reduced the tanks base shear on average by 30%. These results indicated that the foundation was feasible and functional in terms of construction practices and dynamic response, yet unpractical from an economic point of view. In order to tackle the issue of reducing the uneconomic system size, a negative stiffness mechanism was invented and implemented into the foundation as a periodic structure. This mechanism, based on a local instability, amplified the metamaterial like properties and thereby enhanced the overall system performance. Note that due to the considered instability, the device exerted a nonlinear force-displacement relationship, which had the interesting effect of reducing the band-gap instead of increasing it. Furthermore, time history analyses demonstrated that with 50% of the maximum admissible negative stiffness, the foundation could be reduced to 1/3 of its original size, while maintaining its performance. Last but not least, a study on wire ropes as resonator suspension was conducted. Their nonlinear behaviour was approximated with the Bouc Wen model, subsequently linearized by means of stochastic techniques and finally optimized with the algorithm developed earlier. The conclusion was that wire ropes could be used as a more realistic suspension mechanism, while maintaining the high damping values required by the optimized foundation layouts. In sum, a metamaterial-based foundation system is developed and studied herein, with the main findings being: (i) a structure of this type is feasible under common construction practices; (ii) the shear stiffness of the system has a fundamental impact on its functionality; (iii) the superstructure cannot be neglected when studying metamaterial-based foundations; (iv) the complete coupled system can be tuned with an optimization algorithm based on calculations in the frequency domain; (v) an experimental study suggests that the system could be advantageous to connected pipelines; (vi) wire ropes may serve as resonator suspension; and (vii) a novel negative stiffness mechanism can effectively improve the system performance.

The goal of this thesis is to develop nontraditional strategies to provide motion control for different engineering applications. We focus our attention on three topics: 1) roll reduction of ships in a seaway; 2) response reduction of buildings under seismic excitations; 3) new training strategies and neural-network configurations. The first topic of this research is based on a multidisciplinary simulation, which includes ship-motion simulation by means of a numerical model called LAMP, the modeling of fins and computation of the hydrodynamic forces produced by them, and a neural-network/fuzzy-logic controller. LAMP is based on a source-panel method to model the flowfield around the ship, whereas the fins are modeled by a general unsteady vortex-lattice method. The ship is considered to be a rigid body and the complete equations of motion are integrated numerically in the time domain. The motion of the ship and the complete flowfield are calculated simultaneously and interactively. The neural-network/fuzzy-logic controller can be progressively trained. The second topic is the development of a neural-network-based approach for the control of seismic structural response. To this end, a two-dimensional linear model and a hysteretic model of a multistory building are used. To control the response of the structure a tuned mass damper is located on the roof of the building. Such devices provide a good passive reduction. Once the mass damper is properly tuned, active control is added to improve the already efficient passive controller. This is achieved by means of a neural network. As part of the last topic, two new flexible and expeditious training strategies are developed to train the neural-network and fuzzy-logic controllers for both naval and civil engineering applications. The first strategy is based on a load-matching procedure, which seeks to adjust the controller in order to counteract the loads (forces and moments) which generate the motion that is to be reduced. A second training strategy provides training by means of an adaptive gradient search. This technique provides a wide flexibility in defining the parameters to be optimized. Also a novel neural-network approach called modal neural network is designed as a suitable controller for multiple-input multiple output control systems (MIMO). / Ph. D.

Doctoral thesis called Vibrations of slender bridge structures deals with comparison of constructions’ responses at different load model of pedestrians. Specifically, in practice commonly used model, where there are the effects of pedestrians replaced by forces acting in a certain place on the bridge and other model, which takes into account the load of pedestrians moving along the deck. Calculations of responses are performed by finite element method in program ANSYS. To obtain extreme values of responses It is used parametric calculation using the program OptiSlang. At first responses on the simplified constructions are evaluated for load of two pedestrians, as well as the responses on real bridges for load of two pedestrians and four pairs of pedestrians. Responses are also evaluated in terms of pedestrian’s comfort during use structures and analyzed for what groups of pedestrians are criteria still met and for which it is necessary to consider about use of devices to reduce vibration. Possible applications and design process of the vibration dampers are shown on different configurations on the bridges.

This master thesis deals with the dynamic analysis of a footbridge. Computational model of the footbridge was created using ANSYS software. The model was subjected to dynamic wind load in longitudal and lateral direction. Furthermore pedestrian load in lateral direction was analyzed. Afterwards, due to unsatisfactory response to the pedestrian laod, a tuned mass damper was introduced to reduce the vibration. This lead to decrease in the vibration to a satisfactory levels, as is shown in the analyses of the model.

Master’s thesis deals with the issue of electronic filtering circuits with arbitrary frequency characteristics. First part of the thesis describes theoretical basis. Second part explores the possibilities of design procedures for filters with arbitrary frequency characteristics. Design procedures are demonstrated on examples accordingly to the presented methods, including their circuit implementation and computer simulation to verify the correctness of theoretical assumptions. Thesis also explores the possibilities of tuning circuit structures and electronic setting for characteristics using controllable active elements.

Thesis deals with the modeling of pedestrian excitation of structures and obtaining the corresponding dynamic response of the structure. The trend of modern slender structures places more emphasis on the accuracy of modeling pedestrian dynamic excitation, which is difficult because of the intelligent behavior of pedestrians and the biological nature of the modeled pedestrian. First part of the thesis deals with traditional models of pedestrian excitation, based on application of pedestrian ground force to the model of construction. Models are explored on a model of slender footbridge for many different excitation variants in order to explore the specifics of the force excitation application and the structure response calculation. In second part of the thesis biomechanical pedestrian models are developed, including inertial forces, to calculate the pedestrian interaction with the structure. Parametric studies carried out on simplified structural models research the influence of design parameters of biomechanical models on dynamic response. The aim is to obtain a more accurate model of the pedestrian-construction system for refinement of the design of structures. The design of a tuned mass dampers for the reduction of pedestrian induced vibrations is also explored. Tuned mass dampers are devoted to parametric studies that deal with the influence of design parameters of the damper on the efficiency and design requirements of the device. The aim is to explore the design parameters and their influence on the efficient and economical design of the device. In the thesis were developed two biomechanical models, a simple biomechanical model with one vertical degree of freedom and a bipedal model of a human walking. Models have proven a certain degree of interaction when exciting light footbridges by one pedestrian. Bipedal model then also brought a partial insight into the mechanics of walking and the causes of pedestrian contact forces.