The design problems of the passive and activecontrol devices for the seismic-excitedstructures can be defined as some of the optimization problems that demand simple, accurate, and fast optimization algorithms. For this pur- pose, a newmodifiedTLBO algorithm, namely MTLBO, is proposed here. In the MTLBO, an extra term was added to the basic TLBO in the both teacher and learner phases. The performance of MTLBO was firstly validated for some unconstrained and constrained engineering bench- marks. To compare the efficiency of the MTLBO, some evolutionary optimization techniques such as PSO, DE, GA, and ABC along with their various variants were con- sidered. Considering the statistical results undertaken for assessing the performance and reliability of optimiza- tion algorithms, it was concluded that the MTLBO was able to give reliable and better results than other algo- rithms. Furthermore, it was found that the superiority of the MTLBO was evident for optimization problems with a large number of design variables. For some optimization problems, the MTLBO also resulted in the best solution with less function evaluation numbers and computational
Based on information collected at the 6 th International Post-SMiRT Conference Seminar on Seismic Isolation, Passive Energy Dissipation and ActiveControl of Vibrations of Structures, held at Cheju (Korea) in 1999 and more recent information that became available later to the authors, the state-of-the-art on the applications of SI and ED systems has been shortly reported and some remarks on the progress of R&D activities at word-wide level and design guidelines development have been made. It has been stressed that SI and ED technologies, which aim at ensuring the full integrity and operability of structures, are fully mature, as demonstrated by both the results of very numerous research projects and the excellent behavior of seismically isolated buildings and viaducts in violent earthquakes. It has been shown that, consequently, a wide extension of the use of these techniques is in progress, for both new constructions and retrofit of existing buildings.
Depending on their location certain civil structured facilities can be subjected to dynamic loads due to gusty wind fronts and/or strong ground motion associated with earthquake events of different intensity/severity during their life service. At high levels of intensity these naturally occurring dynamic loads may induce permanent structural damage and, in extreme cases, total structural failure/collapse. During the past three decades the incorporation of various devices such as base isolators, energy dissipation equipment (e.g. viscous dampers, friction dampers, etc.), and tuned-mass dampers (TMDs) has been considered by various researchers and has been applied in practice to passively control the vibratory motion of structures maintaining its amplitude below certain acceptable thresholds (Martelli & Forni, 2011; Spencer Jr, 2002; Soong & Dargush, 1999; Chang, 1999). Typically, such “non-conventional” means of mitigating the hazard posed to structures due to the action of winds and earthquakes are applied to protect critical civil infrastructure such as high-rise buildings, hospitals, and long-span (foot)bridges. Furthermore, the employment of such passive devices is commonly considered to upgrade/reinforce existing/historical structures to meet the contemporary safety criteria and to retrofit damaged structures in the aftermath of severe seismic events. These practical applications have sustained the important and active research field of passive vibration control for new and for existing/damaged structures. Admittedly, it is noted that improved structural performance can be achieved by usingactive/semi-activecontrol solutions relying on the integration of sensors, controllers and real-time data
The main reason for usingpassive energy dissipation devices in a structure is to limit the number of damaging deformations in structural components. Among the available varieties of passive energy dissipation devices, the metallic-hysteretic damper is one of the most effective and economical mechanisms for the dissipation of seismic energy input, which is obtained through the inelastic deformation of metallic material. Numerous metallic dampers have been proposed: TADAS , the honeycomb damper , the buckling- restrained brace (BRB) [11-14], and the slit damper [15-18]. These devices are mainly designed to be incorporated into the bracing system of structural frames. Other devices have been developed to be installed between beams and columns in a frame structure [19-21].
The most commonly seen application of the active noise control technique is the active noise cancelling (ANC) headphones (Fig. 1.3). The ANC headphones typically employ a reference microphone, mounted on the outer surface of the head- phone’s housing. The reference microphone picks up the ambient noise, and sends the noise signal to a processing unit, which generates the anti-noise signals and plays it through the headphone driver along with the music signal . In some designs, an additional error microphone is placed inside the ear cup to monitor the residual noise. It is also possible to use a feedback ANC structure, where the ref- erence microphone is omitted, one such design is detailed in . Noise cancelling headphones can yield reasonably good noise attenuation, partially due to the fact that the secondary loudspeaker and the error microphone are placed very close to the ear. According to , significant attenuation of sinusoidal noise signal can be achieved for frequencies up to 2 kHz. Another study on consumer ANC headphone performance  suggests that the noise reduction achievable by ANC headphones is typically between 10 − 25 dB, and the performance is highly dependant on the tightness of the wearing situation.
The idea of three-dimensional shape morphing was investigated, in the hope that the geometrical analysis could be extended to surfaces. Again initial and target morphing geometries were defined, and the actuation distribution with which to best effect the shape change sought. Discrete actuation was applied to replicate screw-actuators, the location and magnitude of which were assigned via optimisation decision variables. An optimiser-controlled NURBS curve was used to apply fixed boundary conditions around the perimeter of the morphing region. A two-stage optimisation process was employed: utilising a Monte Carlo search to initialise the problem, followed by a gradient-based refinement of the most promising regions of design space. The optimum configuration was seen to employ six actuators, and the bounding curve was shaped to provide the required bump width, but increased the length of the morphing region enabling a higher bump crest. Again a demonstration model was constructed, the displacements of which correlated well with the optimal FE model, validating the structural modelling applied during optimisation. The displacement-based objective provided optimal solutions, however a second objective function based on Gaussian curvature – a measure of how a surface is bent in two dimensions – was seen to perform badly. Comparison of the target Gaussian curvature distribution with that achieved by a typical optimiser iteration, showed that significant improvements in the Gaussian curvature objective function were impossible whilst respecting the material constraint. It follows that any change in Gaussian curvature will be difficult to achieve with a continuous shell structure such as an aircraft skin. The large in-plane strain that will always accompany a significant change in Gaussian curvature will exceed current material limitations. It is therefore sensible wherever possible to define morphs which are developable, and hence can exhibit large deformations with relatively small in-plane strains. In addition to allowing greater changes in aerodynamic performance, structural actuation will require less energy.
A difficult but important problem in optimalcontrol theory is the design of an optimal feedback control, i.e., the design of an optimalcontrol as function of the phase (state) coordinates [1,2]. This problem can be solved not often. We study here the autonomous nonlinear system of second order in general form. The con- straints imposed on the control input can depend on the phase (state) coordinates of the system. The goal of the control is to maximize or minimize one phase coordinate of the considered system while other takes a prescribed in advance value. In the literature, optimalcontrol problems for the systems of second order are most frequently associated with driving both phase coordinates to a prescribed in advance state. In this statement of the problem, the optimalcontrol feedback can be designed only for special kind of systems. In our statement of the problem, an optimalcontrol can be designed as function of the state coordinates for more general kind of the systems. The problem of maximization or minimization of the swing amplitude is considered explicitly as an example. Simulation results are presented.
system G(s) is functionally controllable if the normal rank of G(s), denoted r, is equal to the number of outputs, l, that is, if G(s) has full row rank. A system is functionally uncontrollable if r<l”. From a physical viewpoint, the functional uncontrollability of the specific system of this study is caused by the fact that the number of inputs (i.e., the yaw moment) is smaller than the number of outputs (i.e., yaw rate and sideslip angle). Even many of the papers including a sideslip term in their continuous yaw moment controller formulation are not clear regarding the actual benefit of the corresponding contribution. These elements would suggest the selection of control concept i). On the other hand, yaw rate control alone can be a risky option, as it could lead to vehicle instability in the case of incorrect or delayed tire-road friction coefficient estimation. Hence, in this paper control concept iii) is chosen. As sideslip estimation is simpler and faster than tire-road friction estimation [ 109 , 110 ], a control structure is proposed for continuous yaw rate control, capable of constraining sideslip angle when specified threshold values are reached. Integral sliding mode control (ISM) as a perturbation estimator is selected for its ease of implementation, computational efficiency (e.g., with respect to model predictive control), tunability (i.e., each control parameter provokes a predictable effect and can be modified during a vehicle testing session without significant off-line calculations), robustness (i.e., compensation of matched disturbances), lack of chattering (in comparison with first order sliding mode), and the fact that it represents a disturbance observer added to a more conventional and known controller.
The TLBO algorithm was evaluated and tested on the IEEE 30-bus test systems to solve the ORPD. Simulation results confirm the robustness and efficiency of the algorithm when compared with other metaheuristic algorithms and validated using PowerWorld. The simulation results show that TLBO method reduced the active power transmission line losses from 17.557MW to 16.1504MW (about 8.01% loss reduction). The simulation results show that the application of TLBO to ORPD is a good prediction model to obtain optimal values but the PowerWorld solution provides a realistic solution to solving the ORPD problem by showing areas where improvements need to be made and transmission lines that need to be corrected for overloading while keeping the control variables within their constraint limits. The simulation results from the PowerWorld shows a reduced active power transmission loss from 18.13MW to 16.27MW (about 10.26% loss reduction) for the same values used in the TLBO
With f values larger than unity, the damper travel is magnified. Magnifying the damper travel reduces the damper force. f values for upper, lower and reverse toggle arrangement has been formulated (Constantinou et al., 2001) and it has been concluded that practical range of f values are between 2.0-5.0. A single-storey frame with upper toggle configuration with f approximately 3.0 has been tested in experiments. Another approach to amplify damper travel includes the scissor-jack configuration (Slgaher and Constantinou, 2003). The toggle- damper-brace system generally requires braces which are stiff enough to elude compression buckling. A double upper-toggle-brace system has been proposed for low-rise structures which suffer from the soft-storey mechanism (Chan et al., 2012).
290 facilitate the operation of transmission lines closer to their maximum thermal limits and the control over the line impedances of a transmission system, the voltage magnitude, and the phase angle of buses. They also help in reducing the flow in heavily loaded lines, resulting in the increase in power flow transfer capability of the transmission systems, to enhance continuous control over the voltage profile and/ or to damp power system oscillations. The ability to control power rapidly can increase the stability margins as well as the damping of the power system, to minimize losses, reduced cost of production, to work within the thermal limits range, etc. FACTS devices provide control facilities, both in steady state power flow control and dynamic stability control. The optimal operation of the power system networks have been based on economic criterion. The shunt FACTS devices can be very helpful in the optimal operation of power system networks. Both the power system performance and the power system stability can be enhanced by utilizing FACTS devices. To a large extent, proper location of STATCOM device can make great enhancement to power system performance/voltage stability. VSC type STATCOM device has self-commutated DC to AC converters, using GTO thyristors, which can internally generate capacitive and inductive reactive power for transmission line compensation, without the use of capacitor or reactor banks. Thus, this leads to improve the security and stability of the power system.
One of the major issues with nonlinear observers is that most of them did not give a structural design methodology and if they do, then some of the conditions are very hard to meet. Secondly, most of them are designed for a particular class of systems, like the one that is used for comparison purposes, it is only applicable to the systems that have Lipschitz type nonlinearity and satisfies the globally Lipschitz conditions. The proposed observer is not restricted to any class of system as long as an invariant manifold exists and it also provides a structured design methodology. Robustness is a fundamental property, especially when the observer needs to be used in a closed loop control system because the performance of the controller depends on the estimated signals. A qualitative analysis has been performed based on the performance index defined in Section 6.6. It is shown that the proposed observer is robust to the parameter variation, measurement noise, different type of external disturbances and phase change in the excitation signal, whereas there is an increase in the error in all the scenarios for the observer based on Lipschitz type nonlinearity.
Abstract: Demand for green energy is in continuous growth. Wide band effi- cient wearable systems and antennas are crucial for energy harvesting weara- ble systems for medical and sport wearable sensors. Small harvesting antennas suffer from low efficiency. The efficiency of energy harvesting wearable sys- tems may be improved by usingactive wearable harvesting systems with low power consumption. Amplifiers may be connected to the wearable antenna feed line to increase the system dynamic range. Novel active wearable har- vesting systems are presented in this paper. Notch and Slot antennas are low profile and low cost and may be employed in energy harvesting wearable sys- tems. The wearable harvesting system components are assembled on the same PCB. The notch and slot antennas bandwidth is up to 100% for VSWR better than 3:1. The slot antenna gain is around 3 dBi with efficiency higher than 90%. The antennas electrical parameters were computed in vicinity of the human body. The active antenna gain is 24 ± 2.5 dB for frequencies from 200 MHz to 900 MHz. The active antenna gain is 12.5 ± 2.5 dB for frequencies from 1 GHz to 3 GHz. The active slot antenna Noise Figure is 0.5 ± 0.3 dB for frequencies from 200 MHz to 3.3 GHz.
The design of linear suspension controllers that emphasize either passenger comfort or suspension deflection. The controllers in this section are designed using linear H∞ synthesis . As is standard in the H∞ framework, the performance objectives are achieved via minimizing weighted transfer function norms. Weighting functions serve two purposes in the H∞ framework: They allow the direct comparison of different performance objectives with the same norm, and they allow for frequency information to be incorporated into the analysis. A block diagram of the H∞ controldesign interconnection for the active suspension problem is shown below. The quarter car model shown is used to designactive suspension control laws.
epidemic with high medical, economic and social costs [1-3]. Tight control of blood glucose levels has also been shown to reduce the mortality of diabetic, and non-diabetic, intensive care unit patients by up to 50% . Diabetic individuals monitor food intake and daily activity to maintain blood sugar levels at an adequate level. For ease of management, subjects are encouraged to stick to strict routines and diets to minimize manual monitoring and injections, reducing intervention and difficulty. This regime can lead to severe limitation of the subjects’ lifestyle, an “institutional” psychology, and the difficulty of consistently maintaining a strict daily regimen over several years.
The concept of FACTS (Flexible Alternating Current Transmission System) refers to a family of power electronics-based devices able to enhance AC system controllability and stability and to increase power transfer capability. FACTS devices, thanks to their speed and flexibility, are able to provide the transmission system with several advantages such as: transmission capacity enhancement, power flow control, transient stability improved, and power oscillation damping and voltage stability. This paper investigates modeling and analysis of Static Series Synchronous Compensator (SSSC) and performance of SSSC in power system. The ability of these FACTS devices for power flow control of normal/steady state condition is examined. The ability of FACTS device with AHP method using Teacher Learning Based Optimization (TLBO) method is also examined. This paper shows the Optimal Location of Static Series Synchronous Compensator (SSSC) in Transmission line usingTLBO based AHP method. The objective is to minimize the fuel cost of generation, voltage deviation, transmission losses and to determine the optimal value of control variables such as generator real power, generator voltage magnitudes, tap setting of the transformer and number of compensation devices and also maintain a reasonable system performance in terms of limits on generator real power and reactive power outputs, bus voltages and power flow of transmission lines. The proposed method is examined and implemented on IEEE 30-bus power system network.
several disadvantages such as flow of reactive power and difficulty in controlling both power flow and stability. Although the initial investment cost for HVDC transmission systems is high, its controllability allows the overcoming of these inherent limitations of AC transmission systems. The HVDC transmission systems also enhance the stability of the AC transmission systems they are connected to. They also allow interconnection of AC transmission systems with differing system frequencies. When interconnecting power systems, the short circuit capacity of the AC transmission systems will not increase. Moreover HVDC link is effective for frequency control and improves the stability of the system using fast load flow control. The importance of AC–DC transmission systems regarding improvement of stability has been subject to much research. In this paper, a methodology for the optimalactive power controller designusing the Gravitational Search Algorithm (GSA) is proposed to improve the transient stability of AC–DC transmission systems after faults. The proposed method is verified using computer simulation. The results show that the application of GSA tuned controller in AC–DC transmission systems will improve the transient stability.
Figure 2.8 displays these three components of a turbulence signal. From the perspective of ﬂow control, all of these three components can be manipulated by some kinds of control devices. Flow control with brute force techniques (for example a ﬂuidic vortex generator with a high control velocity ratio) usually have suﬃcient amplitude to directly modify the mean ﬂow structures represented by ϕ(x j ). However, for these control methods, the input control energy is usually similar to or even larger than the studied ﬂow. Therefore, the control eﬃciency is very low. More eﬀective approaches usually manipulate the phase averaged value ϕ(x ^ ^ j , t), which seek to leverage ﬂow properties/instabilities using small-amplitude perturbations (Cattafesta and Sheplak ). The above two control strategies are the conventional methods for active ﬂow control, which manipulate the large-scale coherent structures, consequently followed by altering the ﬁne scales through turbulence cascading. Direct manipulation of a random turbulence signal ϕ ′ (x j , t) is also possible. For example, an oscillating surface with micro magnitudes in the boundary layer is an example, which inﬂuences ﬂows at the smallest scales (within the sub-layer of a boundary layer). If the control eﬀect is obvious for this micro-manipulation, this control strategy will be of the highest eﬃciency as a result of the least input energy. However, as stated in Cattafesta and Sheplak , eﬀective small-amplitude forcing remains an elusive goal because of the lack of suﬃcient bandwidth and control authority of the actuators.
Over the past several decades, the concept of the tuned mass-damper (TMD) has been extensively used for passive vibration suppression of dynamically excited structural systems (Chang 1999; Hoang et al. 2008). In its classical form, the TMD comprises a mass attached to the structure whose vibration motion is to be controlled (primary structure) via optimally designed/”tuned” linear spring and viscous damper (dashpot) elements. The effectiveness of the TMD depends heavily on its inertia property. In this context, recently a generalization of the classical TMD has been proposed by the second author (Marian and Giaralis 2013; Marian and Giaralis 2014) incorporating an “inerter” device: the tuned mass-damper-inerter (TMDI) [shown in Figure 1]. The inerter is a two-terminal device developing a resisting force proportional to the relative acceleration of its terminals (Smith 2002). The underlying constant of proportionality (“inertance”) can be orders of magnitude larger than the physical mass of the inerter. In a number of studies (Marian and Giaralis 2013; Marian and Giaralis 2014; Giaralis and Petrini 2017) the TMDI has been shown to outperform the TMD, especially when smaller attached masses are examined. Beyond this mass amplification effect, an important aspect for TMDI
In this paper we rstly discuss a new inverse model for MR dampers which are represented using the normalized Bouc-Wen model , . Then, using this inverse model, we consider a hybrid seismiccontrol system for building structures, which combines a set of passive base isolators with a semi-activecontrol system. Because the force gener- ated in the MR dampers is dependent on the local responses of the structural system, the desired control force cannot always be produced by the devices. Only the control voltage can be directly controlled to increase or decrease the force produced by the devices. The desired control force is based on an active controller presented in  which has shown sufcient compatibility with the inherent characteristics of MR dampers. In general, in the semi-activecontrol strategies presented in the literature, for instance , , , , they managed a single MR damper per oor or, in the case of multiple MR dampers, they receive the same command voltage. In this work, a new practical method has also been dened to compute the command voltage of each MR damper independently according to the desired control force. The management of these MR dampers is based on a hierarchical strategy: we rst compare the total damping force generated in the MR dampers with respect to the desired control force and then we decide what dampers need to apply more damping force and the corresponding command voltage. The whole method is simulated by considering a three- dimensional smart base-isolated benchmark building  where the MR dampers are used as supplemental damping devices. This benchmark problem is a new generation of benchmark studies by the American Society of Civil Engi- neering (ASCE) Structural Control Committee, that offers a carefully modeled real-world structure in which different control strategies can be implemented and compared. The performance indices demonstrate that the proposed semi- active method can effectively suppress structural vibration caused by earthquake loading and can provide a desirable effect on structural performance.