Showing papers by "Hamid Reza Karimi published in 2011"

Robust Delay-Dependent $H_{\infty}$ Control of Uncertain Time-Delay Systems With Mixed Neutral, Discrete, and Distributed Time-Delays and Markovian Switching Parameters

Abstract: The problem of robust mode-dependent delayed state feedback H∞ control is investigated for a class of uncertain time-delay systems with Markovian switching parameters and mixed discrete, neutral, and distributed delays. Based on the Lyapunov-Krasovskii functional theory, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities for the stochastic stability and stabilization of the considered system using some free matrices. The desired control is derived based on a convex optimization method such that the resulting closed-loop system is stochastically stable and satisfies a prescribed level of H∞ performance, simultaneously. Finally, two numerical examples are given to illustrate the effectiveness of our approach.

Robust synchronization and fault detection of uncertain master-slave systems with mixed time-varying delays and nonlinear perturbations

Abstract: In this paper, the problem of robust synchronization and fault detection for a class of master-slave systems subjected to some nonlinear perturbations and mixed neutral and discrete time-varying delays is investigated based on an H ∞ performance condition. By introducing a descriptor technique, using Lyapunov-Krasovskii functional and a suitable change of variables, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities to synthesize the residual generation scheme. The explicit expression of the synchronization law is derived for the fault such that both asymptotic stability and a prescribed level of disturbance attenuation are satisfied for all admissible nonlinear perturbations. A numerical example with simulation results illustrates the effectiveness of the methodology.

LQG Control Design for Balancing an Inverted Pendulum Mobile Robot

Abstract: The objective of this paper is to design linear quadratic controllers for a system with an inverted pendulum on a mobile robot. To this goal, it has to be determined which control strategy delivers better performance with respect to pendulum’s angle and the robot’s position. The inverted pendulum represents a challenging control problem, since it continually moves toward an uncontrolled state. Simulation study has been done in MATLAB Simulink environment shows that both LQR and LQG are capable to control this system successfully. The result shows, however, that LQR produced better response compared to a LQG strategy.

Semiactive Control for Floating Offshore Wind Turbines Subject to Aero-hydro Dynamic Loads

Abstract: Wind and wave dynamic loads might cause undesirable vibrations that affect the structure in tegrity and system performance of floating offshore wind turbin es. This paper addresses the problem of dynamic load mitigat ion by using semiactive control techniques with the tuned liquid column dampers placed on the turbine's tower. The control law is formulated based on the mixed H2/H ∞ methods for ensuring the system stability and reliability. Furthermore, the proposed controller only uses output feedback so as to avoid the dependence on the knowledge of the states of the sy stem.

Development of lumped-parameter mathematical models for a vehicle localized impact

Abstract: In this paper, we propose a method of modeling for vehicle crash systems based on viscous and elastic properties of the materials. This paper covers an influence of different arrangement of spring and damper on the models’ response. Differences in simulating vehicle-torigid barrier collision and vehicle-to-pole collision are explained. Comparison of the models obtained from wideband (unfiltered) acceleration and filtered acceleration is done. At the end we propose a model which is suitable for localized collisions simulation.

Mathematical modeling of a vehicle crash test based on elasto-plastic unloading scenarios of spring-mass models.

Abstract: This paper investigates the usability of spring which exhibit nonlinear force-deflection characteristic in the area of mathematical modeling of vehicle crash. We present a method which allows us to obtain parameters of the spring-mass model basing on the full-scale experimental data analysis. Since vehicle collision is a dynamic event, it involves such phenomena as rebound and energy dissipation. Three different spring unloading scenarios (elastic, plastic, and elasto-plastic) are covered and their suitability for vehicle collision simulation is evaluated. Subsequently we assess which of those models fits the best to the real car’s behavior not only in terms of kinematic responses but also in terms of energy distribution.

Fuzzy Reliable Tracking Control for Flexible Air-breathing Hypersonic Vehicles

Abstract: In this paper, we present a fuzzy reliable tracking control design method for flexible air-breathing hypersonic vehicles (FAHVs) subject to disturbances and possible sensor/actuator failures. This problem is challenging due to the strong coupling effects, variable operating conditions and possible failures in FAHVs. First, Takagi-Sugeno (T-S) fuzzy model is used to represent the longitudinal dynamics model of FAHVs. Then, by considering the disturbances and the faults, the fuzzy reliable tracking problem is proposed, and the tracking control problem is transformed into a stabilization problem. A fuzzy reliable state-feedback controller is designed to guarantee the asymptotic stability of the closed-system. By the Lyapunov approach, the existence conditions for such a controller are established in terms of linear matrix inequalities. With the designed controllers, the reference command can be tracked in spite of actuator/sensor faults. Simulation has demonstrated the proposed design scheme.

Signal analysis and performance evaluation of a vehicle crash test with a fixed safety barrier based on haar wavelets

Abstract: Author's version of an article published in the journal: International Journal of Wavelets, Multiresolution and Information Processing. Also available from the publisher at: http://dx.doi.org/10.1142/s0219691311003979

Semi-decentralized strategies in structural vibration control

Abstract: Published version of an article published in the journal: Modeling, Identification and Control. Also available from the publisher at: http://dx.doi.org/10.4173/mic.2011.2.2

Predicting employees' well-being using work–family conflict and job strain models

Abstract: The present study examined the effects of two models of work–family confl ict (WFC) and job-strain on the jobrelated and context-free well-being of employees. The participants of the study consisted of Iranian employees from a variety of organizations. The effects of three dimensions of the job-strain model and six forms of WFC on affective well-being were assessed. The results of hierarchical multiple regression analysis revealed that the number of working hours, strain-based work interfering with family life (WIF) along with job characteristic variables (i.e. supervisory support, job demands and job control) all make a signifi cant contribution to the prediction of jobrelated well-being. On the other hand, strain-based WIF and family interfering with work (FIW) signifi cantly predicted context-free well-being. Implications are drawn and recommendations made regarding future research and interventions in the workplace. Copyright © 2010 John Wiley & Sons, Ltd.

Genetic relationships among Pistacia species studied by SAMPL markers

Abstract: Pistachio is economically important in Iran. Selection of suitable rootstocks, resistant to unfavorable and soil conditions and diseases, is important for increasing yield and the acreage of this crop. It is essential to identify the genetic relationships among Pistacia species for the breeding of pistachio rootstocks. The goal of this study was to determine the genetic relationship among Pistacia species (P. vera L., P. khinjuk Stocks., P. eurycarpa Yalt., P. atlantica subsp. atlantica Zoh., P. atlantica subsp. mutica Fish et C.A. Mey and P. atlantica subsp. cabulica Stocks.) with potential in the breeding of rootstocks using the selective amplification of microsatellite polymorphic loci (SAMPL) technique. Six primer combinations produced a total of 182 bands, with an average of 30.33 bands per primer pair, of which 128 were polymorphic. Three branches were obtained, the first containing P. vera, and the second containing P. khinjuk, P. eurycarpa, P. atlantica and subspecies mutica and cabulica, with numerous leaflets clustered in the third branch. UPGMA analysis separated P. atlantica subspecies from P. eurycarpa.

Effects of water salinity on growth indices and physiological parameters in some pistachio rootstocks

Abstract: Pistachio is one of the most important horticultural crops in Iran. The majority of the pistachio producing regions is located in arid and semi-arid areas with saline conditions. Therefore, selection of suitable rootstocks is important for increasing yield efficiency of this important nut crop. In this study, the effect of four water salinity levels (0.75, 5, 10 and 15 ds m−1) on growth indices and physiological parameters of four Pistacia vera L. rootstocks (Badami-e-Zarand A, Badami-e-Zarand B, Qazvini, and Sarakhs) were investigated under greenhouse conditions. After treatment for three months, leaf dry weight was reduced by about 30-50% at an irrigation water electrical conductivity (ECw) of 10 ds m−1. Badami-e-Zarand B was the most vigorous rootstock at the highest EC. Decreases in root and stem dry weight (average of all rootstocks combined) occurred at water salinity of 10 ds m−1. Chemical analysis of shoot and root indicated that the salinity affected the concentration and distribution of sodium (...

Wind turbine modeling using the bond graph

Abstract: This paper addresses the problem of bond graph methodology as a graphical approach for modeling wind turbine systems. In this case, we consider the modeling of a wind turbine system with individual pitch control scheme and the interaction with tower motions. Two different bond graph models are presented, one complex and one simplified. Furthermore, the purpose of this paper is not to validate a specific wind turbine model, but rather show the difference between modeling with a classical mechanical method and by using the bond graph approach. Simulation results illustrate the simplified system response obtained using implementation of the governing equations in MATLAB/Simulink and is compared with a bond graph implementation in the simulation program 20-sim.

Semiactive vibration control of nonlinear structures through adaptive backstepping techniques with H∞ performance

Abstract: This article presents a new approach to the vibration mitigation problem in structures subject to seismic motions. These kinds of structures are characterised by the uncertainties of the parameters that describe their dynamics, such as stiffness and damping coefficients. Moreover, the dampers used to mitigate the vibrations caused by earthquakes are usually nonlinear devices with frictional or hysteretic dynamics. We propose an adaptive backstepping controller to account for the uncertainties and the nonlinearities. The controller is formulated in such a way that it satisfies an H∞ performance. It is designed for a 10-storey building whose base is isolated with a frictional damper (passive device) and a magnetorheological damper (semiactive device). Controller performance is analysed through numerical simulations.

Mean-Square Filtering for Polynomial System States Confused with Poisson Noises over Polynomial Observations

Abstract: 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.2011.2.1

Adaptive H ∞ synchronization of master-slave systems with mixed time-varying delays and nonlinear perturbations: An LMI approach

Abstract: This paper proposes an adaptive synchronization problem for the master and slave structure of linear systems with nonlinear perturbations and mixed time-varying delays comprising different discrete and distributed time delays. Using an appropriate Lyapunov-Krasovskii functional, some delay-dependent sufficient conditions and an adaptation law including the master-slave parameters are established for designing a delayed synchronization law in terms of linear matrix inequalities(LMIs). The time-varying controller guarantees the H∞ synchronization of the two coupled master and slave systems regardless of their initial states. Particularly, it is shown that the synchronization speed can be controlled by adjusting the updated gain of the synchronization signal. Two numerical examples are given to demonstrate the effectiveness of the method.

State feedback control against sensor faults for Lipschitz nonlinear systems via new sliding mode observer techniques

Abstract: This paper investigates the problem of simultaneous state and fault estimation and observer-based fault tolerant controller design for Lipschitz nonlinear systems with sensor failure. A new estimation technique is presented in this paper to deal with this design problem. In the proposed approaches, the original system is first augmented by a descriptor model transformation, then a new Proportional and Derivative sliding mode observer technique is developed to obtain accurate estimations of both system states and sensor faults. The designing observer is generalized from the PD observer in [3], but is not a trivial extension. Based on the state estimates, a observer-based control strategy is developed to stabilize the resulting closed-loop system. Finally, a numerical example is presented to illustrate the effectiveness and applicability of the proposed technique.

H(infinity) control design for building structures under seismic motion with wireless communication

Abstract: In this paper, we contribute to the further development of delay-range-dependent state-feedback aspect of robust control for vibration reduction in a building structure with limited wireless communication capacity subjected to measurement quantization, signal transmission delay and data packet dropout, which appear typically in a network environment. The feedback loop is subjected to a time-varying bounded delay within the sensors and the structure. By using an appropriate Lyapunov-Krasovskii functional and some free weighting matrices, new sufficient conditions in terms of some linear matrix inequalities are established for the existence of desired controllers such that the resulting closed-loop system is asymptotically stable and kept within a prescribed level of H1 performance bound. Finally, simulation results are given to illustrate the usefulness of the proposed control methodology.

Control Design Methodologies for Vibration Mitigation on Wind Turbine Systems

Abstract: Published version of a chapter in the book: Vibration Analysis and Control - New Trends and Developments. Also available from the publisher at: http://www.intechopen.com/source/pdfs/17693/InTech-Control_design_methodologies_for_vibration_mitigation_on_wind_turbine_systems.pdf. OA

Stenting (cutting and grafting)-a technique for propagating pomegranate (punica granatum l.)

Abstract: There is inadequate information on the application of rootstocks in the propagation of pomegranate. The aim of this research was to study propagation of pomegranate using the stenting method. The experiment was conducted on the basis of a completely randomised design (CRD) with two factors: rootstock (R1, R2 and R3) and the concentration of indole-3-butyric acid (IBA) (0 and 500 mg/l), in three replications. The rootstocks were ‘Gorj-e-Dadashi’ (R1), ‘Gorj-e-Shahvar’ (R2) and ‘Gool Safid-eAshk-e-Zar’ (R3), and the scions were of the cultivar Malas-e-Yazdi. The results indicated that rootstock type and IBA treatment influenced bud-take and root formation. The highest bud-take percentage was obtained with R1 in combination with 500 mg/l IBA.

Effects of water salinity on growth indices and physiological parameters in some pistachio rootstocks

Abstract: Pistachio is one of the most important horticultural crops in Iran. The majority of the pistachio producing regions is located in arid and semi-arid areas with saline conditions. Therefore, selection of suitable rootstocks is important for increasing yield efficiency of this important nut crop. In this study, the effect of four water salinity levels (0.75, 5, 10 and 15 ds m−1) on growth indices and physiological parameters of four Pistacia vera L. rootstocks (Badami-e-Zarand A, Badami-e-Zarand B, Qazvini, and Sarakhs) were investigated under greenhouse conditions. After treatment for three months, leaf dry weight was reduced by about 30-50% at an irrigation water electrical conductivity (ECw) of 10 ds m−1. Badami-e-Zarand B was the most vigorous rootstock at the highest EC. Decreases in root and stem dry weight (average of all rootstocks combined) occurred at water salinity of 10 ds m−1. Chemical analysis of shoot and root indicated that the salinity affected the concentration and distribution of sodium (...

Study of pomegranate (Punica granatum L.) propagation using bench grafting.

Abstract: There is inadequate information in the case of rootstock application in pomegranate. In this study, propagation of pomegranate was investigated using bench grafting. The experiment was conducted as factorial in the framework of CRD design with three replications. The rootstocks were R1, R2 and R3 and the scions included ‘Gorj-eDadashi’ (S1) and ‘Gorj-e-Shahvar’ (S2). At the end of experiment, successful callus formation at graft union, bud take percentage (BT), bud take stem length, internodes length and shoot fresh and dry weight were measured. The results indicated that rootstock influenced all measured characters including bud take and consequently the highest and lowest BT were obtained in R1 and R3 , respectively. The interaction between rootstock/scion indicated the highest BT in R3S1 and R2S2.

Active-passive control strategy for adjacent buildings

Abstract: In this paper, a control strategy to mitigate the vibrational response of adjacent buildings under seismic excitation is presented. The proposed strategy combines inter-building passive actuators with active actuators placed in the building stories. The main ideas are presented by means of a simplified two-building model; however, a semi-decentralized overlapping approach via the inclusion principle has been used to impose a proper information exchange structure suitable for wireless control of large buildings. Numerical simulations have been carried out to assess the performance of the proposed methodology with promising results. The overall control system exhibits some degree of fault-tolerance since only partial degradation of the control performance results from partial failures of the control system.

Sliding mode exponential H ∞ synchronization of Markovian jumping master-slave systems with time-delays and nonlinear uncertainties

Abstract: This paper investigates the problem of exponential H ∞ synchronization for a class of master-slave systems with both discrete and distributed time-delays, norm-bounded nonlinear uncertainties and Markovian switching parameters. Using an appropriate Lyapunov-Krasovskii functional, some delay-dependent sufficient conditions and a synchronization law which include the master-slave parameters are established for designing a delay-dependent mode-dependent sliding mode exponential H ∞ synchronization control law in terms of linear matrix inequalities. The controller guarantees the H ∞ synchronization of the two coupled master and slave systems regardless of their initial states. A numerical example is given to show the effectiveness of the method.

Stability analysis and H ∞ controller design of a class of switched discrete-time fuzzy systems

Abstract: In this paper, the problems of stability analysis and H ∞ controller design of a class of switched nonlinear systems are investigated. In a classical way, the modeling of the systems is approached by switched fuzzy systems, and both fast switching and slow switching are considered there. In particular, for slow switching scheme, a new mode-dependent average dwell time switching is proposed for the underlying switched fuzzy systems. Based on a fuzzy-basis-dependent and mode-dependent Lyapunov function, the H ∞ state-feedback controller is derived. A numerical example is given to show the validity and potential of the theoretical results.

Data gathering and mathematical modelling for pitch stabilisation of a high speed catamaran

Abstract: This paper deals with the data gathering phase for a 21-foot long planing catamaran. The boat experiences a take-off phenomenon at high speed which needs to be countered. An overview of stability problems in high speed hydroplanes is described with possible solutions recommended. A subsequent gathering of data using laser scanning and computational fluid dynamics (CFD) analysis of the boat are described. The paper ends with a look at the initial developments of stabilising systems for the boat.