Isabela Roxana Birs

Bio: Isabela Roxana Birs is an academic researcher from Technical University of Cluj-Napoca. The author has contributed to research in topics: PID controller & Control theory. The author has an hindex of 9, co-authored 51 publications receiving 288 citations. Previous affiliations of Isabela Roxana Birs include Control Group & Ghent University.

Seismic Mitigation in Civil Structures Using a Fractional Order PD Controller

Abstract: In this paper, a systematic tuning procedure for a fractional order PD controller for seismic mitigation is proposed. The tuning is based upon reducing the magnitude of the compensated system at the resonance frequency as compared to the magnitude of the uncompensated structure. For simplicity, a laboratory scale 1DOF (one degree of freedom) steel structure is used as the case study, The simulation results considering the El Centro earthquake accelerograms show that the designed control strategy is highly suitable for solving seismic mitigation of steel structures and ensures improved response in comparison with steel structures equipped with passive protection. 

Experimental results of fractional order PI controller designed for second order plus dead time (SOPDT) processes

Abstract: The present paper presentes the tuning of a Fractional Order Proportional Integral (FOPI) controller for second-order-plus-time-delay (SOPDT) plants. The tuning procedure is based on imposing frequency domain constraints for the open loop system with the FOPI controller and the SOPDT plant. The gain crossover frequency, phase margin and the iso-damping property that guarantees a certain degree of robustness to gain variations are imposed in order to obtain the parameters of the fractional order controller. The proposed method is validated by real life implementation on a process whose dynamics are approximated to a SOPDT model. The settling time, steady state error, robustness and disturbance rejection capabilities are analyzed using experimental test cases.

An optimal fractional order controller for vibration attenuation

Abstract: Unwanted vibrations may cause severe damage and may endanger the lives of passengers on board of an airplane. In the last years, there has been an increased focus on the study of active vibration techniques. A viable possibility to actively control the vibration of an airplane wing is by using piezoelectric actuators. The paper presents a novel tuning procedure of a fractional order Proportional Derivative controller based on three points of the magnitude Bode diagram. The eloquence of the controller is experimentally validated on an experimental setup consisting of an aluminum beam that replicates an airplane wing.

Modelling and calibration of a conventional activated sludge wastewater treatment plant

Abstract: Wastewater treatment plants (WWTPs) are key infrastructures for ensuring a proper protection of the environment. Mathematical modelling and simulation of activated sludge systems have gained increasing attention in control engineering within the last years. The most widely used models to describe the biochemical processes that take place in a WWTP are the Activated Sludge Models 1–3. Due to their increased complexity, these models are often unsuited for control systems design. The aim of this paper is to develop reduced order models which can adequately describe the biochemical processes for the purpose of on-line control design. The models developed contain a minimum number of variables and parameters that allow for model identification and validation based on available on-line measurements.

Fractional Order Internal Model Control Strategies for a Submerged Nanorobot

Abstract: Fractional calculus is a well-known tool that improves the closed loop performance of processes when compared to integer order approaches. The study presents a generalization of the popular Internal Model Control (IMC) strategy for fractional order processes of any complexity. The controller is based on the inverse fractional order transfer function to which a fractional order filter is added. The velocity of a scalable nanorobot operating in submersed environments is the chosen process to exemplify the proposed control strategy. The Fractional Order Internal Model Control (FOIMC) is developed for the fractional dynamics of the robot. The validity of method is proved through simulations regarding reference tracking, disturbance rejection and robustness to gain variations.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Formulas For Natural Frequency And Mode Shape

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Non-newtonian fluids.

Abstract: The Viscosity can be imagined as the force that should be applied to a layer of fluid belonging to the plane fixed to the velocity of the layer placed at a fixed distance. For example a fluid flowing in a tube at different speeds: the minimum speed is in the edge of the section (due to friction) and the maximum speed is at the center. The viscosity in this example is that pressure which is exerted on the wall allows a constant speed on the whole section.

Applications of Fractional Calculus

Abstract: Explicit formula and graphs of few special functions are derived in the paper on the basis of various definitions of various fractional derivatives and various fractional integrals. Their applications are also reviewed in the paper.