Distributed passive actuation schemes for seismic protection of multibuilding systems

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—(i) is based on an effective matrix formulation of the damped multibuilding system; (ii) follows an H8 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.Peer ReviewedPostprint (published version

Application of Tuned Mass Dampers for Structural Vibration Control: A State-of-the-art Review

Given the burgeoning demand for construction of structures and high-rise buildings, controlling the structural vibrations under earthquake and other external dynamic forces seems more important than ever. Vibration control devices can be classified into passive, active and hybrid control systems. The technologies commonly adopted to control vibration, reduce damage, and generally improve the structural performance, include, but not limited to, damping, vibration isolation, control of excitation forces, vibration absorber. Tuned Mass Dampers (TMDs) have become a popular tool for protecting structures from unpredictable vibrations because of their relatively simple principles, their relatively easy performance optimization as shown in numerous recent successful applications. This paper presents a critical review of active, passive, semi-active and hybrid control systems of TMD used for preserving structures against forces induced by earthquake or wind, and provides a comparison of their efficiency, and comparative advantages and disadvantages. Despite the importance and recent advancement in this field, previous review studies have only focused on either passive or active TMDs. Hence this review covers the theoretical background of all types of TMDs and discusses the structural, analytical, practical differences and the economic aspects of their application in structural control. Moreover, this study identifies and highlights a range of knowledge gaps in the existing studies within this area of research. Among these research gaps, we identified that the current practices in determining the principle natural frequency of TMDs needs improvement. Furthermore, there is an increasing need for more complex methods of analysis for both TMD and structures that consider their nonlinear behavior as this can significantly improve the prediction of structural response and in turn, the optimization of TMDs

Форсированное управление движением мобильного робота

Objectives. The increase of the efficiency of a separate transport mobile robot in a warehouse due to optimal regulation of the speed of its movement. It is required to control the position, speed, acceleration and direction of movement of the mobile robot at each moment of time along a known route. A method for forced control of the movement of a transport mobile robot was proposed. A control block for various motion maneuvers was developed in Simulink environment, which calculates the distance to the nearest turning point or stop and then by constructed cyclogram the corresponding speed at each moment of time is determined. The proposed control unit can be used in practice for the tasks of optimal movement of transport robots in predetermined area.Methods. The method of the theory of optimal control according to the criterion of maximum speed, the wave algorithm for finding the shortest path, the method of finite automata for relay control of the acceleration of movement are used.Results. Based on the proposed method of forced control of the movement of a transport mobile robot in the Simulink environment, a maneuver control system was developed that provides the minimum travel time for each segment of the path. Maneuvers mean the rectilinear movement of the robot, as well as its turn on the spot, in two modes: with and without reaching maximum speed. The technique is based on the assumption that the movement of the transport robot is uniformly accelerated. A side result of the developed control system is that when it is scaled to a group of robots, it becomes possible to predict the time and place of their potential collisions, in order to subsequently take into account a group of robots for effective control.Conclusion. The developed control system can be used to control a real transport mobile robot equipped with a servo drive in solving the problems of transporting goods around the warehouse.Цели. Требуется повысить эффективность работы отдельного транспортного мобильного робота на складе за счет оптимизации регулирования скорости его передвижения. Для этого необходимо регулировать положение, скорость, ускорение и направление движения мобильного робота в каждый момент времени по известному маршруту. Предложена методика форсированного управления движением транспортного мобильного робота. На ее основе в среде Simulink разработан блок управления различными маневрами движений робота, который вычисляет его расстояние до ближайшей точки поворота или останова и на основании построенной циклограммы определяет соответствующую скорость в каждый момент времени. Блок управления может быть использован в практических приложениях, требующих оптимального управления движением транспортных роботов по заранее известной местности.Методы. Применяется метод теории оптимального управления по критерию максимального быстродействия, волновой алгоритм для поиска кратчайшего пути и метод конечных автоматов для релейного управления ускорением движения.Результаты. На основе предложенной методики форсированного управления движением транспортного мобильного робота в среде Simulink разработана система управления маневрами, обеспечивающая минимальное время прохождения на каждом отрезке пути. Под маневрами подразумеваются прямолинейное движение робота, а также его разворот на месте в двух режимах: с выходом на максимальную скорость и без выхода. Методика строится на предположении, что движение транспортного робота равноускоренное. Дополнительным результатом разработанной системы управления является то, что при ее масштабировании на группу роботов появляется возможность спрогнозировать время и место их потенциальных столкновений (коллизий), чтобы впоследствии учитывать это для эффективного управления уже группой роботов.Заключение. Разработанная система может быть использована для управления реальным транспортным мобильным роботом, оснащенным сервоприводом, при решении задач перевозки грузов по складу

Measurements, Models, Systems and Design

531 s.

Instationary modal Analysis for Impulse-type stimulated structures

In order to determine modal parameters, classical experimental modal analysis can be used in engineering application. This method finds a system frequency response function using fast Fourier Transform (FFT). The Fourier Transform is one type of global data analysis method. The frequency resolution is equal to the reciprocal of the total sample time. So applying the FFT is not suitable for any transient signal to reveal local characteristics. However, in modern manufacturing industries, processing forces are rapidly changing. The dynamic behavior may vary rapidly in a short time due to variations in the machining parameters and changes in boundary conditions. These nonlinear and non-stationary dynamic parameters are not constant during machining operations identification using FFT. In this research, an innovative transient signal analysis approach has been developed, which is based on an application of the least squares estimation. The proposed method provides transient information with high resolution and to identify the time-varying modal parameters during machining. Least squares estimation can be augmented with a sliding-window operation (SWLSE) to reveal the actual system dynamic behavior at any moment. The accuracy of this method depends on the window size, the noise ratio and the sampling rate etc. The estimation accuracy of modal parameters is discussed in this work. To examine the efficiency of the SWLSE method experimental tests are performed on a laboratory beam system and the results are compared with the classical experimental modal analysis (CEMA) method. The laboratory beam system is designed and assembled that the stiffness and damping ratio of the structure can be adjusted. Additionally, the proposed method is applied to the identification of the actual modal parameters of machine tools during machining operations. In another application, the proposed method provides also the process varied damping information in a process monitoring

Generalized Force Approach to Point-to-Point Ionospheric Ray Tracing and Systematic Identification of High and Low Rays

Post-print (lokagerð höfundar)A variant of the direct optimization method for point-to-point ionospheric ray tracing is presented. The method is well suited for applications where the launch direction of the radio wave ray is unknown, but the position of the receiver is specified instead. Iterative transformation of a candidate path to the sought-for ray is guided by a generalized force, where the definition of the force depends on the ray type. For high rays, the negative gradient of the optical path functional is used. For low rays, the transformation of the gradient is applied, converting the neighbourhood of a saddle point to that of a local minimum. Knowledge about the character of the rays is used to establish a scheme for systematic identification of all relevant rays between given points, without the need to provide an accurate initial estimate for each solution. Various applications of the method to isotropic ionosphere demonstrate its ability to resolve complex ray configurations including three-dimensional propagation and multi-path propagation where rays are close in the launch direction. Results of the application of the method to ray tracing between Khabarovsk and Tory show good quantitative agreement with the measured oblique ionograms.Icelandic Research Fund (Grant No. 184949-052)Peer Reviewe