Dissertations for Systems Engineering (SE)

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A Design Study for Multivariable Feedback Control System Regulation for Aircraft Turbo-Jet Engines
(The British University in Dubai (BUiD), 2012-01) El-Hassan, Taher Khalifa Babikir
This research work deals with the design of a multivariable control system for aircraft jet engines. It is motivated by the desire to exploit recent advances in design strategy emphasizing the dissipation of minimum control effort, and the need to investigate suitability and applicability compared with previous applied methodologies. Attention is paid to the energy consumed by the control system itself; in order to minimize wear, cost refits changes and noise generation improving thereby the reliability of aircraft engines. The first part of the research deals with introduction of gas turbine engines. The research theme problem states the design of a multivariable control system for a twin spool turbo-jet engine model with two inputs. These are the fuel flow rate and nozzle area controlling the high and low pressure spool speeds. Objectives are defined as evaluating the proposed controller in comparison to previous designs. This study is presented based upon evaluating the performance and power consumption of the proposed controller compared with other controllers designed in accordance with classical and modern control theory. Previous work conducted to design a controller for the theme problem is reviewed. This includes a controller designed by the Inverse Nyquist Array method and the one synthesized by optimal control method. The research concludes that the new least effort control technique gives superior performance and disturbance recovery. It also generates the simplest controller. This should promote the rapid implementation of this design theory for aircraft engines and for general multivariable applications in near future.
Transmission Line Modelling Techniques for Hybrid Systems
(The British University in Dubai (BUiD), 2012-05) Busamra, Haifa Ali Mubarak
The study in this research focuses on modelling a long, 400kV cable transmission line and the forced ventilation system employed. Emphasises is placed on exploring the most appropriate modelling techniques available to deal with transmission line systems. The projected benefits are to reduce the computational time, the errors in the mathematical derivation and achieve an accurate numerical simulation as a final result. The first portion of this research provides an introduction to the discoveries of electromagnetism and the development of modelling techniques from inception to the current known forms of structured adopted for various engineering system applications. The problem identified investigates the possibility of modelling the 400kV electrical cable, with its four line parameters for no line losses. The objectives set are to model the system by using two modelling methods, to verify the capability of the 400kV cable to transmit its full rated power and the effect of the ventilation system to enhance performance under loss and lossless operating conditions. The modelling process uses the Finite Element Method and the Distributed-Lumped Modelling Method. Results from both methods are compared and the research is concluded with a final recommendation of using the Distributed-Lumped Transmission Line Modelling Method for this, and similar applications.
Hybrid transmission line modeling of crude oil pipeline
(The British University in Dubai (BUiD), 2013-02) Matin, Adeleh Khames
"The purpose of this study was to investigate crude oil pipeline system once modeled as lumped distributed model and finite element, extracted from initial fluid equations. Substituting actual project values is a way to illustrate the advantages and disadvantages of each model in order to indicate the most effective way of computation. The principal conclusion was indicated that, finite element modeling of lossy pipeline when R and G were included, and 10 km pipeline was divided into five sections, was numerically unstable. Moreover, lossless finite element model required long calculation and high consumption of storage memory. In contrast, an examined study on lossy and lossless transmission line with much shorter computation demonstrated precise and stable transient responses. The result indicated even higher accuracy of lossy system when estimated graph intersects the original graph in three locations."
Aircraft wing flutter control
(The British University in Dubai (BUiD), 2013-06) Tavalla, Sahar Sadat
This research includes the design of a multivariable control system for aircraft wings. Two objectives are desired. The first is to control the vibrational problem for low-speed flight by applying a feedback control strategy. The second goal is to demonstrate that the controller for this wing assembly dissipates the least energy by comparing an alternative controller design technique. Simple procedures using established methods relating the wing vibrational problems, are outlined. The control strategies invoked using a simplified flutter dynamic model. A compensator designed to provide enhanced flutter suppression was employed. The transient performance of the system was computed for various flight velocities. Comparison of the energy dissipation for the gain ratios investigated was obtained. Numerical simulation was used to demonstrate the effectiveness of the approach advocated.
Minimum Effort Hydraulic System Regulation
(The British University in Dubai (BUiD), 2013-09) Tuqan, Basem Abdel Khaleq
An investigation into the electrohydraulic performance of long- stroke, loaded, spool valve-controlled, high-pressure, cylinder type servomechanism is presented herein. In addition to spool valve, a needle valve is also included in the hydraulic system so as to create oil leakage across the piston. The leakage flow across the piston is considered so as to produce damping to piston motion. To accommodate performance requirements; single input–multiple output modeling and regulation is proposed. In the study, oil compressibility, the inertia in piston motion and the state equations derived in linearized form are considered. PQR technique is used to derive the transfer function of the open loop system. The applied voltage on the spool and needle valves is considered the single input, while the load position and the leakage flow across the piston are considered as the multiple out-puts. Minimum effort is obtained by optimizing the pole locations of the single input – multiple output system. Optimum locations of the poles are determined by using root locus method and by creating a controller generated zero. The responses are analyzed according to two cases; when the volumes of the cylinder chambers are equal and when they are unequal. Simulation of output responses is shown in order to determine how far the volumes can be considered so as to validate output responses. The control technique used in the application dissipates minimum energy minimizing heat generation, wear and maintenance cost.
A Design Study for a Multivariable Feedback Controller for Aircraft Carrier Landing
(The British University in Dubai (BUiD), 2014-03) Al-Saadi, Ziad Abdulla
This research studies the design of a multivariable control system for aircraft landing. To improve the safety of aircraft landing, handling quality is improved whilst decreasing the number of critical tasks the pilot has to perform simultaneously with improved responsiveness of the aircraft to the pilot’s input commands. By adding another control surface on aircraft’s horizontal tail the dynamics of the aircraft motion are improved, and the pilot has the minimum number of inputs to effectively control the aircraft. Simulation of the results demonstrate the effectiveness of the dynamic reaction and steady state system response showing the aircraft response to tailplane or aileron input change. Least effort controller design method provides superior results motivating further application studies.
Controlling the velocity of air in the working section and in the body of a wind tunnel
(The British University in Dubai (BUiD), 2015-12) Al Wahaibi, Mohammed Saif
This dissertation deals with the multivariable control of an aircraft wind tunnel in order to find the simplest and most economical way of controlling the flow of air in the working section of a wind tunnel model. This model has two inputs, which are the fan motor and the ventilator vanes, and two outputs, which are the velocities in the form of multi input-output model. The comparison of the control methods used will be based on the assessment of the energy dissipated and the dynamic performance. The preferred control method of Least Effort Regulation will be assessed and related to the decoupling compensator method. Block diagrams of both methods and their plots will be included and step response transients and random noise assessment will be presented. The conclusion will state that the least effort control will be the best choice and a preferred method in terms of performance, economy, and energy dissipation from the results that are achieved.
Design Study for Optimum Multivariable Control System for Wind Tunnel Regulation
(The British University in Dubai (BUiD), 2016-08) Ashour, Ashraf Hussein
This Dissertation investigates the design of a multivariable control system for a wind tunnel to obtain the optimum control strategy in order to minimize energy dissipation, noise and cost which improve the quality and integrity of the wind tunnel test measurements. First the research is focused on identifying how a wind tunnel work with brief information about its components and types. Then the least effort control technique will be applied and discussed. Also study includes a controller designed by the Nyquist Array method and other control strategies. Plots of step response, disturbance suppression and transient recovery for both techniques will be presented with their block diagrams. The dissertation concludes with a comparison of the control methods used, based on the performance and energy dissipation.
A Design Study for a Multivariable Feedback Control System for Controlling the Air Gap of Maglev Train Suspension System د
(The British University in Dubai (BUiD), 2017-02) Al-NASSIR, IBRAHIM AHMED
This research present a study of the control of multivariable systems which are subjected to variable input and external load change. The topic of research is to design a controller to control the air gap of the suspension system of a Maglev Train. The design is conducted by implementing a recent research methodology called Least Effort Technique. This methodology were introduced by R. Whalley and M. Ebrahimi in 2006. The significant advantageous of Least effort technique is to reduce the energy consumption in the controller, reducing actuator activity, wear, heat, heat generation, operational and maintenance cost. This research emphasizes this technique enabling comparable transient and disturbance rejection characteristics against results obtained by classical control theories, such as Inverse Nyquist Array and H∞ control theory. The research is focusing on the control problems of the vertical clearance in the suspension system. Initially, the mathematical model of the system is compensated the effect of double integrator which appears in the characteristic equation Simulation of the system is presented to evaluate the effectiveness of the controller to maintain the air gap within the allowable limits, MATLAB-SIMILINK software will be used for simulation purposes and design validation.
Automatic Control for Electrical Lamination Machine Using Least Effort Theory
(The British University in Dubai (BUiD), 2017-05) AL SHEHHI, FAISAL MOHAMMED AHMED ALTAHMOOD
This project studies the design of a multivariable control system of a lamination machine that utilizes the least effort technique. In order to get rid of the instabilities of the system, two loops were considered for the design. By using methods of differentiation and elaborate equations, output responses were monitored. MATLAB was used to simulate the results which proved to be effective and showed fruitful outcomes in both transient and steady state. This machine would be able to predict the open loop performance of the system and would eliminate disturbances in the output. Least effort technique design provided improved performance of the system and helped in smooth running of the machine
A Design Study for Distributed Parameters Modelling of Naval Ship Propulsion Systems Maneuvering
(The British University in Dubai (BUiD), 2017-05) Al Hammadi, Ahmed Mohamed Abdulla Alobaidli
This research focuses on studying and investigating a ship’s propulsion system. A single shaft propulsion system which consists of gas turbine, gearbox, and a propeller will be considered as a model for the ship’s prolusion system. The system will employ a method of distributed lumped parameter modeling where an arrangement of the following configuration will be analyzed. This configuration comprises of rotors (representing gas turbine, gearbox, and propeller), bearings, and a shaft connecting the three rotors. A block diagram representing the system will be formulated and the shear stresses along the shaft and the angular speeds of the rotors will be computed. The system will be distributed to check its response and stability. The system once built up will be simulated to be tested under different conditions. Since there are many factors that can affect the system, it will be simulated based in certain assumptions and few conditions will be selected. The transient response of the system will be computed against predetermined inputs and scenarios. The results will be presented by graphics and the results will be commented upon.Same procedures will be applied on one more condition to test the propulsion system against sea mine that in result to the mine exploding underneath the propeller it will take off the propeller where the third rotor will be eliminated during the simulation.
A Comparative Design Study for Gas Turbine Regulation using Least Effort Control
(The British University in Dubai (BUiD), 2017-05) MEGDADI, EYAD
This study investigates gas turbine engine regulation for heavy duty vehicles using least effort and H infinity control strategies to evaluate the system response, performance and consumption of power. This research study shows how the least effort control gives good transient response, with characteristics of output decoupling and disturbance rejection using a simple feedback strategy. It is shown that the least effort controller gives minimum control energy consumption which causes least heat and power losses and lower maintenance cost. A comparison study with the H infinity method was conducted, to show the advantages and disadvantages of each method. The system model investigated used the linearized equations for an automotive gas turbine, to obtain the vehicle, high load response. The fuel flow and nozzle area of the gas turbine, are used as reference inputs to control the change in the model gas stream temperature, and angular velocity, as system outputs.
Marine Propulsion System
(The British University in Dubai (BUiD), 2017-09) AL SHARIF, HANAN AHMED
The research is an application of a multivariable system control for marine propulsion system where the propeller pitch is controlled to reach stability within different conditions and disturbances. Attention is paid also in fuel consumption in order to reduce the pollution via environment and cost reduction by improving the engine speed control. This dissertation is done on the marine propulsion system model that has been solved mathematically first and then testing the stability of the model using MATLAB/ SIMULINK software. By modeling the ship propulsion system it becomes easier to understand, what parameters are affecting the system and how to control them. The first part of the research is about an introduction of the marine propulsion system. The research problem states a model of multivariable control system for a propeller pitch with two inputs and three outputs. These are the fuel flow rate and the cylinder area controlling the torque and thrust that affects the ship speeds. The method used in this controller is the least effort technique as from the previous control dissertation this method is producing maximum stability, producing best performance and acting as best method for disturbance recovery. As mentioned above and concludes in this research after simulating the model, the least effort control technique shows the best performance and disturbance recovery using the simplest controller. These are the reasons of implementing it in many applications at the main time and the marine propulsion system a good example of the least effort technique application.
Study of Angular Velocity Control of Double Motor Propeller Shaft System
(The British University in Dubai (BUiD), 2017-10) MEGDADY, MAHER FLEAHAN SALEH
An investigation into multivariable control of propeller shaft system of marine vessels is introduced in this study. Two motors drive the shaft with two input voltages to produce torques which overcome the inertia of the load as well as the inertia of internal components of propeller shaft system in order to generate a rotational movement with two different angular speeds. In order to find the best response, best performance and the lowest power consumption by the controller of propeller shaft system, two approaches of control theory is presented; H-infinity control as well as Looping shaping. This paper shows how to reduce energy consumption, hence reduce tear of system’s internal component, the noise generated by system and maintenance cost. This research provides a comparison between the two control strategies in order to determine the pros and cons of each method and find the suitable controller based on application may be targeted later.
A Design Study for Multivariable Feedback Control For a Variable Speed Wind Turbine
(The British University in Dubai, 2017-10) AL AQRA, MELAD BAHJAT ABDELAZIZ
Electrical energy consumption is dramatically increasing due to industry developments and expanding of urban areas. Fossil fuels as an energy resource has many environmental and human health effects. Consequently, the demand for utilizing renewable clean energy arises. Wind energy is a significant source of energy since it is clean, renewable, and cost effective in comparison with other renewable resources like photovoltaic which has higher costs in production and maintenance. This research work deals with variable speed pitch controlled wind turbine and covers the modelling of wind turbines as an aerodynamic, mechanical and electrical system. The preliminary history of feedback control will be reviewed along with background of wind turbine developments. Moreover, the mathematical modelling of a Variable Speed Wind Turbine VSWT will be presented. This study is based on evaluating the performance and energy consumption of two controllers. The first controller is the new Least Effort controller which proved to have superior optimization of the consumed energy by the controller with a simple design using only proportional feedback. The other method is H-infinity controller with mixed sensitivity criteria. This controller results in a fast response but with heavy in energy consumptions and controller complexity. A comparison between the two control techniques showing the simulation results will be provided.
Modelling and Simulation of MD 500E Helicopter Drive System
(The British University in Dubai (BUiD), 2018-11) AL MANSOORI, AHMED
The primary aim of this study is to study the helicopter driveline system response of the helicopter model MD 500E. In order to meet the aims of this study, a mathematical model has been derived from the system from the physical description of the helicopter available. Lumped, finite element and hybrid, distributed-lumped parameter procedures developed by R Whalley, M Ebrahimi and Z Jamil paper “The Torsional response of rotor systems” are employed to represent the system of concern in efforts aimed at increasing accuracy, integrity and computational efficiency. The simulation was done using the Matlab Simulink platform. From the simulation, predictions can be made about how the helicopter’s drive shaft will behave under specific conditions. The results revealed that the three models share identical steady-state response and only vary in transient behaviour. In addition, it was observed that the hybrid, distributed-lumped model showed high accuracy and good integrity and computational efficiency in comparison to the lumped model as well as finite elements model
A Comparative Design Study for Multivariable Feedback Control System Regulation for pneumatic feed mixing system
(The British University in Dubai (BUiD), 2018-11) KHALIL, MOSAB KHAIR ABDELRADY
In this research, mixing system regulation was investigated. Two control methodologies were studied. Least effort method from the Modern British School, and H-infinity controller from Modern American School. The closed-loop system transients and steady-state response were validated. Controller disturbance rejection and energy consumption were verified, and the results were compared between the two design methodologies. This research is started with a brief history of control systems, major effective millstones of this science and examples of main implementations. After which the main idea about multivariable systems is presented. The system under study is a pneumatic feed mixing system used to simulate an industrial mixing process. It consists of two inputs and two outputs. Research objectives are to evaluate the two controllers under study and compare their performance and energy consumption used to achieve this performance. This system was raised as a control problem used by Dutton (1997) to compare several controllers, and re-used by Whalley and Ebrahimi (2006). Revalidation work is done for least effort controller, MATLAB® code and Simulink® model were designed, and the result is compared with another controller designed based on optimal H-infinity method. After a comparison between the two control techniques, this research concludes that the least effort control method is capable of giving superb solution to the control problem, all the objectives achieved with simple model and perfect energy consumption. H-infinity controller offered perfect response in terms of speed, disturbance rejection, and steady state de-coupling, but it has shown high energy cost with complicated model. This shall promote the use of least effort controller for general industrial multivariable mixing process and similar processes.
Dynamical Torsional Analysis of Schweizer 300C Helicopter Rotor Systems
(The British University in Dubai (BUiD), 2019-01) AL-SAEEDI, HAITHAM KHAMIS MOHAMMED
The study in this research focuses on building simulation model the motion systems of Schweizer 300C helicopter and Emphasises is put on examine the most suitable simulation techniques used to deal with the most accurate and closest to reality dynamical torsional response of the motion systems which will lead to the best analysis. In The first part of this research, an introductory to the history of helicopters and their dynamic fundamentles and the development and expansion of the Modeling methods from the beginning to the current forms adopted for wide variety engineering system applications. The problem identified examines the chances and possibilities of simulating the motion systems (tail and main rotors) of Schweizer 300C helicopter .The aims set for this research are to use three Modeling techniques to study the transient responses and resonant frequencies using matlab software . In this research three different techniques were adopted and compared for the simulation of the movement system of this heilcopter to identify the best and most accurate representation of dynamic torsional analysis of motion systems. The Modeling techniques used in this research are the Lumped Parameter Modeling-LPM, Finite Element Method-FEM and the Distributed-Lumped Parameter (Hybrid) model-DLPM. Finally, Modeling techniques and results obtained from each technique are compared and it can be concluded that Distributed-Lumped Parameter technique (DLPMT) is the most accurate and closest to the reality for this and such applications.
Simulation & Analysis of the Helicopter Transmission System
(The British University in Dubai (BUiD), 2019-01) LASFER, ABDALLAH
This report analyzes the main shafts of the helicopter transmission box. The corresponding behavior of the shafts, gears, and blades are monitored and studied. Three different methods were used to analyze the set of systems describing the behavior of the shafts. The first method is the lumped model analysis, which considers each element of the shaft to be discrete. The second method is the finite element method, which separates the shaft itself into smaller elements. The last method is the hybrid model, where the gears are taken as discrete elements, while the shaft characteristics are continuous functions of the shafts’ length. The speed at each end of each shaft is recorded and studied, as well as, the shafts threshold to the shear stress applied. The model results are compared for accuracy, precision and difficulty. Results conclude of simplicity of the lumped model but also impracticality. While the finite elements model is difficult to produce as it requires tedious solving of high order polynomials. The hybrid model is the most accurate in terms of shaft properties however; it faces difficulty in determining the critical speeds for mechanical failure.

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