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1
Li, Ming-Yan. "Performance analysis and enhancement of proportional navigation guidance systems /." Title page, table of contents and abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09ENS/09ensl693.pdf.
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Borg, Jonathan M. "An industrial robotic system for moving object interception using ideal proportional navigation guidance." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ54104.pdf.
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Warioba, Isabela Moses. "The first-past-the-post electoral system versus proportional representation in Africa : a comparative analysis." Diss., University of Pretoria, 2011. http://hdl.handle.net/2263/18651.
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Most African states emerged from shadows and made a transition from mono-party, one-person and military rule towards political pluralism and multi-party democratic governance in 1990s. One of the key ingredients of this transformation is the holding of regular elections and electoral systems that undergird the electoral process itself.
However still, most African states practice what is referred to as shallow democracy as opposed to deeper democracy that requires full participation of citizens and accountability. Shallow democracy is the democracy that has not made any positive impacts to the ordinary people despite the radical changes to the constitution and expansion of part activity.Prepared under the supervision of Mr Paulo Comoane at the Faculty of Law, Eduardo Mondlane University, Mozambique
Thesis (LLM (Human Rights and Democratisation in Africa)) -- University of Pretoria, 2011.
http://www.chr.up.ac.za/
nf2012
Centre for Human Rights
LLM
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Schiller, Noah Harrison. "Design and Validation of a Proportional Throttle Valve System for Liquid-Fuel Active Combustion Control." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9843.
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High-bandwidth fuel modulation is currently one of the most promising methods for active combustion control. To attenuate the large pressure oscillations in the combustion chamber, the fuel is pulsed so that the heat release rate fluctuations damp the pressure oscillations in the combustor. This thesis focuses on the development and implementation of a high-bandwidth, proportional modulation system for liquid-fuel active combustion control.
The throttle valve modulation system, discussed in this thesis, uses a 500-um piezoelectric stack coupled with an off-the-shelf valve. After comparing three other types of actuators, the piezoelectric stack was selected because of its compact size, bandwidth capabilities, and relatively low cost. Using the acoustic resonance of the fuel line, the system is able to achieve 128% pressure modulation, relative to the mean pressure, and is capable of producing more than 75% flow modulation at 115 Hz. Additionally, at 760 Hz the system produces 40% pressure modulation and 21% flow modulation with flow rates between 0.4 and 10 gph. Control authority was demonstrated on a single-nozzle kerosene combustor which exhibits a well-pronounced instability at ~115 Hz. Using the modulation system, the fundamental peak of the combustion instability was reduced by 30 dB, and the broadband sound pressure levels inside the combustor were reduced by 12 dB. However, the most important conclusion from the combustion control experiments was not the system?s accomplishments, but rather its inability to control the combustor at high global equivalence ratios. Our work indicates that having the ability to modulate a large percentage of the primary fuel is not always sufficient for active combustion control.Master of Science
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Kawera, Marie Sylvie. "Proportional representation electoral system and conflict management in divided societies: the case of Rwanda and Kenya." Diss., University of Pretoria, 2009. http://hdl.handle.net/2263/12431.
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Critically examines the role of electoral systems in the democratisation process and conflict management in divided societies such as Kenya and Rwanda. Analyses the power sharing arrangement institutionalized in Rwanda in the aftermath of the genocide in order to demonstrate the potential to mitigate issues of ethnic. Also explores the anomalous results caused by the current electoral system in Kenya (First Past The Post) in its process of democratization and then find out which is the most suitable electoral system which encourage co-operation and inclusiveness and
discourage conflict and exclusiveness.
minority representationA Dissertation submitted to the Faculty of Law University of Pretoria, in partial fulfilment of the requirements for the degree Masters of Law (LLM in Human Rights and Democratisation in Africa). Prepared under the supervision of Dr. Atangcho N Akonumbo, Faculté de Sciences Sociales et de Gestion, Université Catholique D’Afrique, Centrale Yaounde Cameroun.
Thesis (LLM (Human Rights and Democratisation in Africa))--University of Pretoria, 2009.
http://www.chr.up.ac.za/
Centre for Human Rights
LLM
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Lagimoniere, Ernest Eugene Jr. "The Design and Construction of a High Bandwidth Proportional Fuel Injection System for Liquid Fuel Active Combustion Control." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/34693.
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This last decade experienced a sudden increase of interest in the control of thermo-acoustic instabilities, in particular through the use of fuel modulation techniques. The primary goal of this research was to design, construct and characterize a high bandwidth proportional fuel injection system, which could be used to study the effect of specific levels of fuel modulation on the combustion process and the reduction of thermo-acoustic instabilities. A fuel injection system, incorporating the use of a closed loop piston and check valve, was designed to modulate the primary fuel supply of an atmospheric liquid-fueled swirl stabilized combustor operating at a mean volumetric fuel flow rate of 0.4 GPH. The ability of the fuel injection system to modulate the fuel was examined by measuring the fuel line pressure and the flow rate produced during operation. The authority of this modulation over the combustion process was investigated by examining the effect of fuel modulation on the combustor pressure and the heat release of the flame. Sinusoidal operation of the fuel injection system demonstrated: a bandwidth greater that 800 Hz, significant open loop authority (averaging 12 dB) with regards to the combustor pressure, significant open loop authority (averaging 33 dB) with regards to the unsteady heat release rate and an approximate 8 dB reduction of the combustor pressure oscillation present at 100 Hz, using a phase shift controller. It is possible to scale the closed loop piston and check valve configuration used to create the fuel injection system discussed in this work to realistic combustor operating conditions for further active combustion control studies.Master of Science
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Keating, Jennifer. "Relating forearm muscle electrical activity to finger forces." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-theses/580.
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The electromyogram (EMG) signal is desired to be used as a control signal for applications such as multifunction prostheses, wheelchair navigation, gait generation, grasping control, virtual keyboards, and gesture-based interfaces [25]. Several research studies have attempted to relate the electromyogram (EMG) activity of the forearm muscles to the mechanical activity of the wrist, hand and/or fingers [41], [42], [43]. A primary interest is for EMG control of powered upper-limb prostheses and rehabilitation orthotics. Existing commercial EMG-controlled devices are limited to rudimentary control capabilities of either discrete states (e.g. hand close/open), or one degree of freedom proportional control [4], [36]. Classification schemes for discriminating between hand/wrist functions and individual finger movements have demonstrated accuracy up to 95% [38], [39], [29]. These methods may provide for increased amputee function, though continuous control of movement is not generally achieved. This thesis considered proportional control via EMG-based estimation of finger forces with the goal of identifying whether multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm. Electromyogram (EMG) activity from the extensor and flexor muscles of the forearm was sensed with bipolar surface electrodes and related to the force produced at the four fingertips during constant-posture, slowly force-varying contractions from 20 healthy subjects. The contractions ranged between 30% maximum voluntary contractions (MVC) extension and 30% MVC flexion. EMG amplitude sampling rate, least squares regularization, linear vs. nonlinear models and number of electrodes used in the system identification were studied. Results are supportive that multiple degrees of freedom of proportional control information are available from the surface EMG of the forearm, at least in healthy subjects. An EMG amplitude sampling frequency of 4.096 Hz was found to produce models which allowed for good EMG amplitude estimates. Least squares regularization with a pseudo-inverse tolerance of 0.055 resulted in significant improvement in modeling results, with an average error of 4.69% MVC-6.59% MVC (maximum voluntary contraction). Increasing polynomial order did not significantly improve modeling results. Results from smaller electrode arrays remained fairly good with as few as six electrodes, with the average %MVC error ranging from 5.13%-7.01% across the four fingers. This study also identified challenges in the current experimental study design and subsequent system identification when EMG-force modeling is performed with four fingers simultaneously. Methods to compensate for these issues have been proposed in this thesis.
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Huet, Philippe. "A VMEbus-based data acquisition system for the multiwire proportional chambers of the H1 detector at the HERA Collider." Doctoral thesis, Universite Libre de Bruxelles, 1993. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212813.
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Macías, Cubeiro Rosa. "Development and Implementation of a Search and Locate Actuator System." Thesis, KTH, Elektrisk energiomvandling, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-109706.
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Over the last years, electrical roads have emerged as a cost effective and environmentally friendly solution towards a transportation system with less dependency on fossil fuels. This thesis presents the design of a search and locate system for road-bound conductive electrical roads with position control in two axes. The system is intended to find and follow the position of an electrified rail. The actuator system constitutes a firm groundwork for further research and development in this field. A laboratory test set up has been designed and both hardware and software parts have been constructed. The control of the system uses the CompactRIOTM technology from National Instruments. Results from the practical evaluation suggest that the non-linear characteristic of the system and the lack of direct position feedback from the motor rotation are the main causes of a non-accurate position control. Future development steps should focus on improving the mechanical design and include encoder feedback for the control loop as well as absolute automatic control with the incorporation of rail sensors.
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Narasimhan, Bharat. "An automated virtual tool to compute the entire set of proportional integral derivative controllers for a continuous linear time invariant system." Texas A&M University, 2007. http://hdl.handle.net/1969.1/85831.
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This thesis presents the very practical and novel approach of using the Graphical User
Interface (GUI) to compute the entire set of Proportional Integral Derivative (PID)
controllers given the transfer function or the frequency response of the system under
consideration.
Though there is a wide spread usage of PID controllers in the industry, until
recently no formal algorithm existed on determining a set of PID values that will
stabilize the given system. The industry still relies on algorithms like the Ziegler-
Nicholas or ad-hoc approaches in determining the value of PID controllers. Also
when it comes to model free approaches, the use of Fuzzy logic and Neural network
do not guarantee stability of the system.
For a continuous Linear Time Invariant system Bhattacharyya and others have
developed an algorithm that determines the entire set of PID controllers given the
transfer function or just the frequency response of the system. The GUI has been
developed based on this theory. The GUI also evaluates the user input performance
specifications and generates a subset of stable controllers given the performance criteria for the system.
This thesis presents an approach of automating the computation of entire set of stabilizing Proportional Integral Derivative (PID) controllers given the system
transfer function or the frequency response data of the system. The Graphical User
Interface (GUI) developed bridges the gap between the developed theory and the
industry.
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Le, Minh-Quyen. "Development of bilateral control for pneumatic actuated teleoperation system." Phd thesis, INSA de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00717743.
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The aim of this thesis is to investigate the development and control of electro-pneumatic actuators in a haptic teleoperation system. For controlling the mass flow rate of such actuators, two types of valve technology are sudied, i.e. solenoid (on/off) valve and proportional servovalve. The servovalves have found widespread applications in which high accuracy of force/position control are needed. They are however typically expensive due to the requirements of high-precision manufacturing. Therefore, the low-cost solenoid valves can be an alternative to the servovalves for achieving acceptable-performance pneumatic control. Generally, the highly nonlinear of the pneumatic actuator is heightened when it uses on/off solenoid valves instead of servovalves. In this case, precise control is challenging due to the discrete-input nature of the system. Our first objective is to demonstrate that it is possible to design an acceptable performance teleoperation system using master-slave robots that have pneumatic actuators equipped with only inexpensive on/off solenoid valves. To control efficiently the switching valves, several control approaches have been proposed, namely pulse width modulation (PWM), hybrid algorithm, and sliding mode control. A hybrid control theory, which includes more switching control modes, than PWM, allows to reduce the chattering problem and improve the energy consumption of the valves. Another strategy (i.e. a sliding mode control), which does not depend on the pneumatic model, is proposed. This control stratgy allows to perform not only the transparent analysis but also the stability analysis. In order to improve the dynamic performance and reduce the chattering problem in solenoid valve actuated pneumatic teleoperation systems, a five-mode sliding control scheme has been used, which can be considered as an extension of the three-mode sliding controller. Our study demonstrates that by increasing the number of possible control actions for the valves, we can reduce the valves' switching activities, hence improving the valve's life times at no cost to teleoperation transparency. The second objective of the thesis involves in implementing the proportional servovalves on the pneumatic teleoperation system. A comparison related to the teleoperation performance between an on/off valve and a servovalve is carried out. In experiments, it is observed that with the bilateral teleoperation architecture employing solenoid valves or servovalves, satisfactory force and position tracking between the master and the slave is obtained. In bilateral teleoperation control, force sensors are often omitted to save cost and to lessen weight and volume. Therefore, another aspect of our work consists in using observers for an estimation of operator and environment forces. Experimental results show that acceptable teleoperation transparency based on a simple Nicosia observer and a tangent linear control approach can be achieved.
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Peppas, Dimitrios Ioannis. "A computer analysis of proportional navigation and command to line of sight of a command guided missile for a point defence system." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1992. http://handle.dtic.mil/100.2/ADA261820.
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Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 1992. This thesis compares two types of command guidance to be used by a point defense system: Proportional Navigation and Command to Line Of Sight (CLOS). The system block diagram was first defined. The necessary transfer functions were derived. Two forward time models were evaluated, one for each guidance method, using state variable analysis. Two three dimensional scenarios were defined and their results used to compare the two methods. Parameters considered in the comparison were miss distance and acceleration load on the missile.Thesis advisor(s): Titus, Harold A. "December 1992." Includes bibliographical references. Also available online.
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André, Simon. "Design and Optimization of Controllers for an Electro-Hydraulic System." Thesis, Linköpings universitet, Reglerteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107620.
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Electro-Hydraulic (EH) systems are commonly used in the industry for applications that require high power-weight ratios and large driving forces. The EH system studied in this master thesis have recently been upgraded with new hardware components and as a part of this upgrade a new controller was requested. The system consists of a controller that computes a control signal for an electric motor. The motor drives a gear pump that generates a flow of hydraulic fluid. The flow is then directed to a cylinder. The movements of a piston in the cylinder is affected by the flow and the piston position can be measured. The measured piston position is then fed back to the controller and the control loop is complete. The system was previously controlled using a Proportional-Integral-Derivative (PID) controller and the purpose of this thesis is to compare the old controller with alternative control strategies suitable for this application. The evaluation of the controllers is based on both software and hardware simulations and results in a recommendation for final implementation of the best suited controller. The control strategies chosen for investigation are: a retuned PID controller, a PID controller with feed forward from reference, a PID based cascade controller, a Linear Quadratic (LQ) controller, and a Model Predictive Controller (MPC). To synthesize the controllers an approximate model of the system is formed and implemented in the software environment Matlab Simulink. The model is tuned to fit recorded data and provides a decent estimation of the actual system. The proposed control strategies are then simulated and evaluated in Simulink with the model posing as the real system. These simulations resulted in the elimination of the cascade controller as a possible candidate since it proved unstable for large steps in the reference signal. The remaining four controllers were all selected for simulation on the real hardware system. Unfortunately the MPC was never successfully implemented on the hardware due to some unknown compatibility error and hence eliminated as a possible candidate. The three remaining control strategies, PID, PID with feed forward from reference and the LQ controller, were all successfully implemented and simulated on hardware. The results from the hardware simulations compared to simulations made with the old controller, as well as the results from the software simulations, were then evaluated. Depending on the purpose one of two control strategies is recommended for this application. The LQ controller achieved the best overall performance and is presented as the control strategy best suited for this application.
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Fahlén, Daniel, and Ludvig Fri. "Modelling and Control of a Forklift’s Hydraulic Lowering Function." Thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139247.
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Material handling and logistics are fundamental parts of today’s global societyand forklifts are a crucial part of the material handling process. Making these asefficient and reliable as possible are therefore of great interest. In this master thesis, an effort has been made to improve the control of the hydraulic lowering function of a specific forklift. Today the lowering function iscontrolled through an open-loop control scheme making the control performancesensitive to disturbances and system changes. One disturbance of special interestis the temperature of the hydraulic fluid. The goal of this thesis was therefore todesign a controller with improved robustness as well as improved performance. To solve this a model-based control design approach was used and a nonlineargrey-box model was derived, implemented and validated. The model parameterswere estimated using a nonlinear least-squares optimisation problem. The resulting model captures most of the system dynamics and the model fit is higher than 70% which was deemed good enough to use for control design. A PID controller was designed based on the estimated model and the controllerparameters were optimised. Furthermore, the controller was evaluated in simulations and implemented in a real forklift. The proposed controller was compared to the original controller for various scenarios. The results reveal improvedsteady state behaviour with enhanced temperature robustness compared to theoriginal controller.Materialhantering och logistik är viktigt för att dagens globala samhälle ska fungera. En grundläggande del i materialhanteringsprocessen är gaffeltruckar, därför är det av intresse att göra gaffeltruckar så effektiva och pålitliga som möjligt. I det här examensarbetet har ett försök gjorts till att förbättra styrningen av den hydrauliska sänkningsfunktionen hos en specifik gaffeltruck. Dagens lösning använder sig av öppen styrning vilket gör reglerprestandan känslig för störningar och systemförändringar. En störning av extra intresse är temperaturen av hydraulvätskan. Målet med detta arbete var därför att designa en regulator med ökad robusthet och prestanda. För att lösa detta har en modellbaserad metod för regulatordesign använts där en olinjär gray-box modell härleddes, implementerades och validerades. Modellparametrarna skattades genom att ställa upp och lösa ett ickelinjärt minsta-kvadrat optimeringsproblem. Den resulterande modellen fångar det mesta av systemdynamiken och modellpassningen till uppmätt data var högre än 70\% vilket ansågs bra nog för att kunna använda modellen som en bas för regulatordesign. En PID regulator designades och regulatorparametrarna optimerades med hjälp av modellen. Regulatorn utvärderades i simuleringar och för att sedan implementeras den på en riktig gaffeltruck. Den föreslagna regulatorn jämfördes med den ursprungliga regulatorn i flera olika testfall. Resultaten visade ett bättre steady-state beteende och ökad robusthet mot temperaturförändringar för den designade regulatorn jämfört med den ursprungliga regulatorn.
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Bodin, Erik, and Henric Davidsson. "Model-Based Design of a Fork Control System in Very Narrow Aisle Forklifts." Thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138049.
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This thesis explains the model-based design of a fork control system in a turret head operated Very Narrow Aisle forklift in order to evaluate and push the limits of the current hardware architecture. The turret head movement consists of two separate motions, traversing and rotation, which both are hydraulically actuated. The plant is thoroughly modeled in the Mathworks softwares Simulink/Simscape to assist in the design of the control system. The control system is designed in Simulink/Stateflow and code-generated to be evaluated in the actual forklift. Optimal control theory is used to generate a minimum-jerk trajectory for auto-rotation, that is simultaneous traversing and rotation with the load kept in centre. The new control system is able to control the system within the positioning requirements of +/- 10 mm and +/- 9 mrad for traversing and rotation, respectively. It also shows good overall performance in terms of robustness since it has been tested and validated with different loads and on different versions of the forklift. However, the study also shows that the non-linearities of the system, especially in the hydraulic proportional valves, causes problems in a closed-loop control system. The work serves as a proof of concept for model-based development at the company since the development time of the new control system was significantly lower than for the original control system.
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Sahin, Murat. "Design And Simulation Of An Abs For An Integrated Active Safety System For Road Vehicles." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608801/index.pdf.
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Active safety systems for road vehicles have been improved considerably in recent years along with technological advances and the increasing demand for road safety. In the development route of active safety systems which started with introduction of digital controlled ABS in the late seventies, vehicle stability control systems have been developed which today, with an integration approach, incorporate ABS and other previously developed active safety technologies. ABS, as a main part of this new structure, still maintains its importance.
In this thesis, a design methodology of an antilock braking system controller for four wheeled road vehicles is presented with a detailed simulation work. In the study, it is intended to follow a flexible approach for integration with unified control structure of an integrated active safety system. The objective of the ABS controller, as in the previous designs in literature, is basically to provide retention of vehicle directional control capability and if possible shorter braking distances by controlling the wheel slip during braking. iv
A hierarchical structure was adopted for the ABS controller design. A high-level controller, through vehicle longitudinal acceleration based estimation, determines reference slip values and a low-level controller attempts to track these reference slip signals by modulating braking torques. Two control alternatives were offered for the design of the low-level controller: Fuzzy Logic Control and PID Control. Performance of the ABS controller was analyzed through extensive simulations conducted in MATLAB/Simulink for different road conditions and steering maneuvers. For simulations, an 8 DOF vehicle model was constructed with nonlinear tires.
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Rottwilm, Philipp Moritz. "Electoral system reform in early democratisers : strategic coordination under different electoral systems." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:6c3ebcf9-f25b-4ce8-a837-619230729c33.
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On the basis of case studies of 19th and early 20th century Germany, Sweden and the Netherlands, I address the question of how and when incumbent right elites reformed electoral systems under a rising political threat from the left. Some states adopted proportional representation (PR) earlier than others. Why did different states adopt PR at different times? One important factor was the existing electoral system before the adoption of PR. This has been missed in academic research since most scholars have assumed that the electoral system in place before the adoption of PR in most Western European states was single-member plurality (SMP). I show that the system in place prior to PR in most Western European states was not SMP but a two-round system (TRS). TRS effects are still poorly understood by political scientists. I argue that both PR and TRS were used as safeguards by the parties on the right against an electoral threat from the left, which originated from the expansion of suffrage. PR was used as a last resort after other safeguards had been exhausted. I state that in the presence of a strong left threat, countries with TRS could wait longer to implement PR than countries with SMP in place. Under TRS, the adoption of PR was considerably delayed since electoral coordination between parties could be applied more effectively than under SMP systems. This was largely due to the increase of information and time after the first round of TRS elections, which was used by right parties to coordinate votes around the most promising candidate before the second round. First round results under TRS were used as an "electoral opinion poll". Based on these results, the right could react more effectively than the left in order to improve outcomes in round two.
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Aucamp, Christiaan Daniël. "Model predictive control of a magnetically suspended flywheel energy storage system / Christiaan Daniël Aucamp." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8601.
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The goal of this dissertation is to evaluate the effectiveness of model predictive control (MPC)
for a magnetically suspended flywheel energy storage uninterruptible power supply (FlyUPS).
The reason this research topic was selected was to determine if an advanced control technique
such as MPC could perform better than a classical control approach such as decentralised
Proportional-plus-Differential (PD) control.
Based on a literature study of the FlyUPS system and the MPC strategies available, two MPC
strategies were used to design two possible MPC controllers were designed for the FlyUPS,
namely a classical MPC algorithm that incorporates optimisation techniques and the MPC
algorithm used in the MATLAB® MPC toolbox™. In order to take the restrictions of the system
into consideration, the model used to derive the controllers was reduced to an order of ten
according to the Hankel singular value decomposition of the model.
Simulation results indicated that the first controller based on a classical MPC algorithm and
optimisation techniques was not verified as a viable control strategy to be implemented on the
physical FlyUPS system due to difficulties obtaining the desired response. The second
controller derived using the MATLAB® MPC toolbox™ was verified to be a viable control
strategy for the FlyUPS by delivering good performance in simulation.
The verified MPC controller was then implemented on the FlyUPS. This implementation was
then analysed in order to validate that the controller operates as expected through a
comparison of the simulation and implementation results. Further analysis was then done by
comparing the performance of MPC with decentralised PD control in order to determine the
advantages and limitations of using MPC on the FlyUPS.
The advantages indicated by the evaluation include the simplicity of the design of the controller
that follows directly from the specifications of the system and the dynamics of the system, and
the good performance of the controller within the parameters of the controller design. The
limitations identified during this evaluation include the high computational load that requires a
relatively long execution time, and the inability of the MPC controller to adapt to unmodelled
system dynamics.
Based on this evaluation MPC can be seen as a viable control strategy for the FlyUPS, however
more research is needed to optimise the MPC approach to yield significant advantages over
other control techniques such as decentralised PD control.Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013
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Looja, Tuladhar R. "Control of Custom Power System using Active Disturbance Rejection Control." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1438913443.
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Miller, Sara Ann. "Ethnic Conflict, Electoral Systems, and Power Sharing in Divided Societies." Digital Archive @ GSU, 2006. http://digitalarchive.gsu.edu/political_science_theses/7.
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This paper investigates the relationship between ethnic conflict, electoral systems, and power sharing in ethnically divided societies. The cases of Guyana, Fiji, Sri Lanka, Lebanon, Mauritius, and Trinidad and Tobago are considered. Electoral systems are denoted based on presidential versus parliamentary system, and on proportional representation versus majoritarian/plurality. The paper concludes that, while electoral systems are important, other factors like the power distribution between ethnic groups, and ensuring a non-zero-sum game may be as important.
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Park, Sung Yeul. "A Wide Range and Precise Active and Reactive Power Flow Controller for Fuel Cell Power Conditioning Systems." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/28645.
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This dissertation aims to present a detailed analysis of the grid voltage disturbance in frequency domain for the current control design in the grid-tie inverter applications and to propose current control techniques in order to minimize its impact and maximize feasibility of the power conditioning system in distributed generations. Because the grid voltage is constantly changing, the inverter must be able to response to it. If the inverter is unable to respond properly, then the grid voltage power comes back to the system and damages the fuel cell power conditioning systems.
A closed-loop dynamic model for the current control loop of the grid-tie inverter has been developed. The model explains the structure of the inverter admittance terms. The disturbance of the grid voltages has been analyzed in frequency domain. The admittance compensator has been proposed to prevent the grid voltage effect. The proposed lead-lag current control with admittance compensator transfers current properly without system failure. In order to get rid of the steady-state error of the feedback current, a proportional-resonant controller (PR) has been adopted. A PR control with admittance compensation provides great performance from zero power to full power operation. In addition, active and reactive power flow controller has been proposed based on the PR controller with admittance compensation. The proposed active and reactive power flow control scheme shows a wide range power flow control from pure leading power to pure lagging power. Finally, the proposed controller scheme has been verified its feasibility in three phase grid-tie inverter applications. First of all, a half-bridge grid-tie inverter has been designed with PR controller and admittance compensation. Then three individual grid-tie inverters has been combined and produced three phase current to the three phase grid in either balanced condition or unbalanced condition.
The proposed control scheme can be applied not only single phase grid-tie inverter application, but also three phase grid-tie inverter application. This research can be applicable to the photovoltaic PCS as well. This technology makes renewable energy source more plausible for distributed generations.Ph. D.
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Groenewald, Petrus Johannes. "Die Suid-Afrikaanse nasionale kiesstelsel :|b'n kritiese ontleding en alternatiewe / P.J. Groenewald." Thesis, North-West University, 2013. http://hdl.handle.net/10394/9662.
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The Republic of South Africa entered into a new constitutional dispensation in 1994. As part of this new constitutional dispensation, a new electoral system, i.e. the closed-list proportional representative electoral system, was adopted. This electoral system was accepted for elections on a national level of representatives for the National Assembly and has certain advantages and disadvantages. Some political scientists, political parties and opinion formers are of the opinion that this electoral system brings about poor contact between the representatives in the National Assembly (Parliament) and the voters. Critics are also of the opinion that party leaders obtain too much power within this electoral system, in that the parties appoint candidates to the candidate lists. In elections, voters vote for specific political parties and therefore do not have a choice with regard to who their representatives are. The result is that South Africa adheres to the representative aspect of democracy, but is lacking with regard to the accounting of representatives to voters. The legitimacy of Parliament is impaired by this defect.
The aim of this study is to provide a critical analysis and investigate alternative frameworks of the South African electoral system and its functioning on a national level. In the analysis it is determined to what extent the South African electoral system meets the criteria set for an electoral system to ensure the legitimacy of Parliament, a sustainable representative democracy and an accountable government in the long term in the country. This analysis and evaluation was used to determine whether the existing closed-list proportional representative electoral system is the most suitable electoral system for South Africa and, if not, to identify and analyse an alternative electoral system for South Africa. The analysis entails a literature overview analysis of electoral systems.
From the study it appears that modern democracies use a wide variety of different electoral systems. There is consensus that no single best electoral system exists which could be used by all countries, since every country has its distinctive circumstances and an electoral system’s functioning and outcomes are affected by it. In this study, twelve different electoral systems are identified with specific advantages and disadvantages. Criteria were set with which electoral systems had to comply in order to promote democracy and ensure the legitimacy of Parliament. These criteria require that electoral systems have to promote and ensure broad representation, accessible and meaningful elections, reconciliation, stable and effective government, accountability of government, accountability of representatives, promotion of political parties, opposition and oversight, sustainability of the electoral process, and international standards.
The listed criteria were placed in order of priority according to those which are the most important in the current South African circumstances. In accordance with this, an evaluation model was drawn up which was quantified in order to calculate the extent to which every electoral system met the requirements and priority order. In determining the order of priority of the requirements in the criteria, the historical circumstances of South Africa, of discord, conflict, racial hatred, riots and suspicion between races, were taken into account.
When applying the evaluation model to the twelve different electoral systems, it was found that the current closed-list proportional representative electoral system is the most suitable electoral system for South Africa and should be retained.
In terms of the criticism of the current electoral system, the conclusion drawn is that electoral systems cannot ensure the measure of accountability of representatives. It is ensured by the internal rules and discipline of the political parties they represent. The contribution of electoral systems to the accountability of representatives is to ensure that voters have a choice between more than one candidate, or more than one political party at a following election. Furthermore, electoral systems also do not appoint candidates in an election; the respective political parties appoint them. In any appointment of candidates, the leadership and party bureaucracy will play a specific role, regardless of the type of electoral system.Thesis (PhD (Political Studies))--North-West University, Potchefstroom Campus, 2013.
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Dantas, Sivanildo de Ara?jo. "Sistema eleitoral proporcional : uma proposta t?cnico-politica para o Brasil." Universidade Federal do Rio Grande do Norte, 2006. http://repositorio.ufrn.br:8080/jspui/handle/123456789/14009.
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Previous issue date: 2006-08-25The present work aims to analyze the several proportional electoral systems from the contemporaries democracies in order to, in the end, purpose a system that better fits to the constitutional Brazilian order. In this direction, we pursued to indicate the main virtues and imperfections in proportional electoral systems in use in more than two hundred countries, especially relating to the positive and negative effects that these systems inject in the party systems, in the governability and in the representativity. In order to collect elements, and also before getting to the work s main point, other issues were approached, even in a shortened way. Nevertheless, in a position taking, we conclude the work opting for a proportional electoral system that potencializes the constitutional principles of representativity and governability as well as prints a party system strong and strict, once these are the depositaries of a democracy compromised with the Brazilian society
O presente trabalho tem por objetivo analisar os diversos sistemas eleitorais proporcionais das democracias contempor?neas para, ao final, propor um sistema que melhor se adeq?e ao ordenamento constitucional brasileiro. Nesse sentido, buscou-se apontar as principais virtudes e imperfei??es dos sistemas eleitorais proporcionais atualmente em vigor em mais de duzentos pa?ses, principalmente no que diz respeito aos efeitos positivos e negativos que esses sistemas projetam no sistema partid?rio, na governabilidade e na representatividade. De forma a colher subs?dios e, antes de chegar ao tema central do trabalho, outras quest?es tamb?m foram abordadas, ainda que de forma abreviada. Por?m, numa tomada de posi??o, conclui-se o trabalho optando-se por um sistema eleitoral proporcional que potencialize os princ?pios constitucionais da representatividade e da governabilidade e imprima um sistema partid?rio forte e coeso, visto serem esses deposit?rios de uma democracia comprometida com a sociedade brasileira
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Sun, Yong. "Reliability prediction of complex repairable systems : an engineering approach." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16273/.
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This research has developed several models and methodologies with the aim of improving the accuracy and applicability of reliability predictions for complex repairable systems. A repairable system is usually defined as one that will be repaired to recover its functions after each failure. Physical assets such as machines, buildings, vehicles are often repairable. Optimal maintenance strategies require the prediction of the reliability of complex repairable systems accurately. Numerous models and methods have been developed for predicting system reliability. After an extensive literature review, several limitations in the existing research and needs for future research have been identified. These include the follows: the need for an effective method to predict the reliability of an asset with multiple preventive maintenance intervals during its entire life span; the need for considering interactions among failures of components in a system; and the need for an effective method for predicting reliability with sparse or zero failure data. In this research, the Split System Approach (SSA), an Analytical Model for Interactive Failures (AMIF), the Extended SSA (ESSA) and the Proportional Covariate Model (PCM), were developed by the candidate to meet the needs identified previously, in an effective manner. These new methodologies/models are expected to rectify the identified limitations of current models and significantly improve the accuracy of the reliability prediction of existing models for repairable systems. The characteristics of the reliability of a system will alter after regular preventive maintenance. This alternation makes prediction of the reliability of complex repairable systems difficult, especially when the prediction covers a number of imperfect preventive maintenance actions over multiple intervals during the asset's lifetime. The SSA uses a new concept to address this issue effectively and splits a system into repaired and unrepaired parts virtually. SSA has been used to analyse system reliability at the component level and to address different states of a repairable system after single or multiple preventive maintenance activities over multiple intervals. The results obtained from this investigation demonstrate that SSA has an excellent ability to support the making of optimal asset preventive maintenance decisions over its whole life. It is noted that SSA, like most existing models, is based on the assumption that failures are independent of each other. This assumption is often unrealistic in industrial circumstances and may lead to unacceptable prediction errors. To ensure the accuracy of reliability prediction, interactive failures were considered. The concept of interactive failure presented in this thesis is a new variant of the definition of failure. The candidate has made several original contributions such as introducing and defining related concepts and terminologies, developing a model to analyse interactive failures quantitatively and revealing that interactive failure can be either stable or unstable. The research results effectively assist in avoiding unstable interactive relationship in machinery during its design phase. This research on interactive failures pioneers a new area of reliability prediction and enables the estimation of failure probabilities more precisely. ESSA was developed through an integration of SSA and AMIF. ESSA is the first effective method to address the reliability prediction of systems with interactive failures and with multiple preventive maintenance actions over multiple intervals. It enhances the capability of SSA and AMIF. PCM was developed to further enhance the capability of the above methodologies/models. It addresses the issue of reliability prediction using both failure data and condition data. The philosophy and procedure of PCM are different from existing models such as the Proportional Hazard Model (PHM). PCM has been used successfully to investigate the hazard of gearboxes and truck engines. The candidate demonstrated that PCM had several unique features: 1) it automatically tracks the changing characteristics of the hazard of a system using symptom indicators; 2) it estimates the hazard of a system using symptom indicators without historical failure data; 3) it reduces the influence of fluctuations in condition monitoring data on hazard estimation. These newly developed methodologies/models have been verified using simulations, industrial case studies and laboratory experiments. The research outcomes of this research are expected to enrich the body of knowledge in reliability prediction through effectively addressing some limitations of existing models and exploring the area of interactive failures.
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Selokela, Thulaganyo Goitseone. "The representation of women in municipal councils and executive structures - analysing the trends in the implementation of the Municipal Structures Act from the results of the 2006 and 2011 South African local government elections." Thesis, University of the Western Cape, 2012. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_3560_1370595210.
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McCabe, Andrew Peter. "Proportional-integral-plus control of nonlinear systems." Thesis, Lancaster University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289039.
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Oubellil, Raouia. "Modeling and control of a SEM-integrated nano-robotic system driven by piezoelectric stick-slip actuators." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT117.
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La capacité de réaliser des tâches robotiques dextres à l'échelle nanométrique dans un microscope électronique à balayage (MEB) est un enjeu crucial pour les nanotechnologies. Les systèmes nano-robotiques dédiés à des applications sous MEB ont ainsi émergé dans de nombreux laboratoires de robotique. Ils peuvent être composés d'un ou de plusieurs actionneurs intégrés à des plateformes nano-robotiques avec un ou plusieurs effecteurs. L’actionneur Piézoélectrique Stick-Slip (PSS) est l'un des meilleurs candidats pour actionner les systèmes nano-robotiques dédiés à des applications sous MEB car il est capable d'effectuer un positionnement grossier avec une plage de déplacement millimétrique et un positionnement précis avec une plage de déplacement de quelques micromètres. La modélisation des actionneurs PSS est complexe notamment en raison de leur mode de fonctionnement hybride. La commande est également difficile à cause de plusieurs caractéristiques liées aux actionneurs PSS, soient le frottement, l’hystérésis et les vibrations non-amorties, qui dégradent leur performances en termes de précision et de vitesse. Ce travail porte sur la modélisation et la commande d'un système nano-robotique à 3 axes dédié à des applications sous MEB et actionné par des actionneurs piézoélectriques de type stick-slip. Chaque élément et caractéristique des actionneurs PSS ont été analysés et modélisés afin d’établir par la suite un modèle dynamique complet capable de décrire les deux modes de fonctionnement, à savoir le mode balayage et pas à pas. Pour chacun de ces deux modes, des lois de commande ont ainsi été développées pour les actionneurs PSS. Des stratégies de commande robuste ont été synthétisées pour des objectifs de positionnement rapide et à haute résolution en mode balayage. De telles performances sont fondamentales dans plusieurs tâches micro-/nano-robotique tels que le nano-assemblage rapide et précis et la nano-caractérisation des matériaux. Une commande proportionnelle en fréquence et en amplitude est synthétisée pour effectuer un déplacement millimétrique en mode pas à pas. Ceci est motivé par les applications robotiques pour lesquelles une large plage de déplacement est requise, tels que le scan de grandes surfaces et les phases d’approche d’une sonde d’un échantillon à manipuler. Une stratégie de commutation qui combine les modes balayage et pas à pas, est alors proposée pour remédier au manque de précision en mode pas à pas, lors de passage d’un grand à un petit déplacement. Ce travail a donné lieu à des résultats qui ouvrent de nouvelles perspectives pour l'utilisation des actionneurs PSS dans les systèmes nano-robotiques dédiés à des applications sous MEBThe capability of doing dexterous robotic tasks at the nanometer scale inside a Scanning Electron Microscope (SEM) is a critical issue for nanotechnologies. SEM-integrated nano-robotic systems have consequently emerged in many robotics laboratories. They can be composed of one or more actuators assembled into nano-robotic platforms with one or several effectors. Piezoelectric Stick-Slip (PSS) actuators is one of the best candidate to actuate SEM-integrated nano-robotic systems because it is able to perform coarse positioning with millimeter displacement range and fine positioning with travel range of few micrometers. Modeling of PSS actuators is complex and difficult mainly because of their hybrid operating mode. Furthermore, control is challenging due to several characteristics related to PSS actuators, namely friction, hysteresis and undamped vibrations, which degrade their performance in terms of precision and speed. This work deals with modeling and control of a 3-axes SEM integrated nano-robotic system driven by piezoelectric stick-slip actuators. Each element and characteristic of PSS actuators are analyzed and modeled to thereafter establish a complete dynamic model able to describe the two functioning modes, namely the scanning and the stepping modes. PSS actuators are then controlled in each of these modes. Robust control strategies are developed to achieve high-resolution and fast positioning in scanning mode. Such performance is fundamental in several micro/nano-robotic tasks such as fast and accurate nano-assembly and nano-material characterization. A frequency/amplitude proportional controller is designed to perform millimeter displacement in stepping mode. This is motivated by robotic tasks where large motion is required, such as large surfaces scan and bringing a probe close to a sample to manipulate. A switched strategy, which combines scanning and stepping motion modes, is then proposed to remedy to the lack of precision in stepping motion, when passing from a large to a small displacement. This work has given rise to results which open new perspectives to the use of PSS actuators in SEM integrated nano-robotic systems
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Dahlin, Sam, and Mathias Åström. "En beslutsanalytisk granskning av offentlig upphandling inom IT-system : Tillämpning av känslighets- och robusthetsanalys." Thesis, Mittuniversitetet, Institutionen för informationssystem och –teknologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-39931.
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Research in the area of public procurement has gained increasing attention with increasing interest in researching different evaluation methods for incoming tenders in procurement. The study analyzed the structure for procurement with a multi-criteria model for observation of changes in ranking and studied the importance of correct scoring. A sensitivity and robustness analysis were used as a tool to study the stability and the strength of a contracting entity's priorities. The purpose of this thesis was a study to determine if the ranking of tenders became more sensitive to the structure of the model or for each tender's evaluation, where it was found that the ability to correctly score points was more crucial than being critical of weights assigned to the criteria in the procurement, respectively. Relationship between price and quality turned out to be unknown to some extent, the connection could be determined after all tenders were submitted and accumulated points were available.Forskning inom området offentlig upphandling har fått allt mer uppmärksamhet när intresset hamnat på undersökning av olika utvärderingsmetoder för inkommande anbud vid en upphandling. I studien analyserades uppbyggnaden för upphandlingar med en multikriteriemodell för observation över förändringar hos rangordning samt studerandet av vikten för en korrekt poängsättning. En känslighets- och robusthetsanalys tillämpades som verktyg för att studera stabiliteten och styrkan hos en upphandlande entitets prioriteringar. Syftet med uppsatsen var en undersökning för en bedömning om rangordningen av upphandlingars anbud blev känsligast mot strukturen på modellen eller för varje anbuds värdering, där det visade sig att förmågan för korrekt poängtilldelning var mer avgörande än att vara kritisk till vikterna som tilldelades respektive kriterier inom upphandlingen. Relationen mellan pris och kvalitet visade sig vara okänd till viss del, sambandet kunde avgöras efter att alla anbud var inskickade och samlade poäng fanns att tillhandahålla.
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Dixon, Roger. "Design and application of proportional-intergral-plus (PIP) control systems." Thesis, Lancaster University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337572.
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Riambau-Armet, Guillem. "Three essays on strategic political behavior in proportional representation systems." Thesis, Boston University, 2013. https://hdl.handle.net/2144/12837.
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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.The goal of this thesis is to understand and measure strategic behavior in proportional representation systems. Chapter one provides an empirical strategy to quantify strategic voting in such systems. Using pre-electoral survey data, it measures the degree of strategic voting in the Israeli legislative elections of 2006, which is shown to have been around 5%-10%. Chapter two uses pre-electoral data from Israel (2003 aud 2006 legislative elections) to show that that agents' perceptions on the affinities between party leaders matter over and above their own preferences and expectations on the distribution of seats in parliament, a fact that has been overlooked by the theoretical literature. A model that incorporates this behavior is also provided. Chapter three takes advantage of the fact that in New Zealand, Maori have the right to choose in which district to register (and therefore, vote), in order to understand the reasons behind Maori choices, using Census and electoral registration data from 2006. Results suggest that there is an agglomeration effect (Maori register where their Maori neighbors register) and also a small strategic effect (Maori register in the district they feel they can be more pivotal).
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Persson, Inger. "Essays on the Assumption of Proportional Hazards in Cox Regression." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2002. http://publications.uu.se/theses/91-554-5208-6/.
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Sandholm, Thomas. "Statistical Methods for Computational Markets : Proportional Share Market Prediction and Admission Control." Doctoral thesis, KTH, Data- och systemvetenskap, DSV, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4738.
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We design, implement and evaluate statistical methods for managing uncertainty when consuming and provisioning resources in a federated computational market. To enable efficient allocation of resources in this environment, providers need to know consumers' risk preferences, and the expected future demand. The guarantee levels to offer thus depend on techniques to forecast future usage and to accurately capture and model uncertainties. Our main contribution in this thesis is threefold; first, we evaluate a set of techniques to forecast demand in computational markets; second, we design a scalable method which captures a succinct summary of usage statistics and allows consumers to express risk preferences; and finally we propose a method for providers to set resource prices and determine guarantee levels to offer. The methods employed are based on fundamental concepts in probability theory, and are thus easy to implement, as well as to analyze and evaluate. The key component of our solution is a predictor that dynamically constructs approximations of the price probability density and quantile functions for arbitrary resources in a computational market. Because highly fluctuating and skewed demand is common in these markets, it is difficult to accurately and automatically construct representations of arbitrary demand distributions. We discovered that a technique based on the Chebyshev inequality and empirical prediction bounds, which estimates worst case bounds on deviations from the mean given a variance, provided the most reliable forecasts for a set of representative high performance and shared cluster workload traces. We further show how these forecasts can help the consumers determine how much to spend given a risk preference and how providers can offer admission control services with different guarantee levels given a recent history of resource prices.QC 20100909
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Villebonnet, Violaine. "Scheduling and Dynamic Provisioning for Energy Proportional Heterogeneous Infrastructures." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEN057/document.
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La consommation énergétique des centres de calculs et de données, aussi appelés « data centers », représentait 2% de la consommation mondiale d'électricité en 2012. Leur nombre est en augmentation et suit l'évolution croissante des objets connectés, services, applications, et des données collectées. Ces infrastructures, très consommatrices en énergie, sont souvent sur-dimensionnées et les serveurs en permanence allumés. Quand la charge de travail est faible, l'électricité consommée par les serveurs inutilisés est gaspillée, et un serveur inactif peut consommer jusqu'à la moitié de sa consommation maximale. Cette thèse s'attaque à ce problème en concevant un data center ayant une consommation énergétique proportionnelle à sa charge. Nous proposons un data center hétérogène, nommé BML pour « Big, Medium, Little », composé de plusieurs types de machines : des processeurs très basse consommation et des serveurs classiques. L'idée est de profiter de leurs différentes caractéristiques de performance, consommation, et réactivité d'allumage, pour adapter dynamiquement la composition de l'infrastructure aux évolutions de charge. Nous décrivons une méthode générique pour calculer les combinaisons de machines les plus énergétiquement efficaces à partir de données de profilage de performance et d'énergie acquis expérimentalement considérant une application cible, ayant une charge variable au cours du temps, dans notre cas un serveur web.Nous avons développé deux algorithmes prenant des décisions de reconfiguration de l'infrastructure et de placement des instances de l'application en fonction de la charge future. Les différentes temporalités des actions de reconfiguration ainsi que leur coûts énergétiques sont pris en compte dans le processus de décision. Nous montrons par simulations que nous atteignons une consommation proportionnelle à la charge, et faisons d'importantes économies d'énergie par rapport aux gestions classiques des data centersThe increasing number of data centers raises serious concerns regarding their energy consumption. These infrastructures are often over-provisioned and contain servers that are not fully utilized. The problem is that inactive servers can consume as high as 50% of their peak power consumption.This thesis proposes a novel approach for building data centers so that their energy consumption is proportional to the actual load. We propose an original infrastructure named BML for "Big, Medium, Little", composed of heterogeneous computing resources : from low power processors to classical servers. The idea is to take advantage of their different characteristics in terms of energy consumption, performance, and switch on reactivity to adjust the composition of the infrastructure according to the load evolutions. We define a generic methodology to compute the most energy proportional combinations of machines based on hardware profiling data.We focus on web applications whose load varies over time and design a scheduler that dynamically reconfigures the infrastructure, with application migrations and machines switch on and off, to minimize the infrastructure energy consumption according to the current application requirements.We have developed two different dynamic provisioning algorithms which take into account the time and energy overheads of the different reconfiguration actions in the decision process. We demonstrate through simulations based on experimentally acquired hardware profiles that we achieve important energy savings compared to classical data center infrastructures and management
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Hassoun, George Estandy. "A study of observability-enhanced guidance systems /." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phh355.pdf.
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Ramamurthi, Indu. "A versatile simulation tool for virtual implementation of proportional integral and derivative (PID) controllers." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/5961.
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This thesis proposes an interactive software tool that can be used to compute complete sets of Proportional Integral Derivative (PID) Controllers from knowledge of the plant transfer function/frequency response data. This is based on research results and algorithms developed by Bhattacharyya and others. Until these research results were published, it was not known if a nominal system could be stabilized using PID Controllers, and current PID Controller designs are carried out using ad hoc tuning rules. By using simulations, engineers can best plan for and observe the stabilizing effect each of the variables has on system performance in a realistic environment. The software application developed calculates and optimizes complete stabilizing sets of PID Controllers for a rational Linear Time Invariant (LTI) system, and has been developed for analytical models of plants with and without time delay. Further, these PID Controller sets are optimized to project subsets simultaneously satisfying multiple performance index specifications. Sets of PID Controllers that stabilize a system are also calculated automatically from knowledge of the frequency response of the plant. It allows the user ease of design and the ability to customize the final solution while permitting full control over source parameters. This thesis includes an introduction to the algorithms that have been developed for plant stabilization, a complete description of the graphical user interface, the simulation of the algorithms performed using LabVIEW, and a summary of future work.
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Luhiste, Maarja. "Candidate gender and electoral success in party list proportional representation (PR List) systems." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4371.
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This thesis studies women politicians’ journey along the path from candidates to elected representatives in party list proportional representation (PR list) systems. While past literature provides sufficient evidence that more women are elected in proportional electoral systems than in majority / plurality systems, there is limited research explaining the differences in women’s representation across varying types of PR list systems. This thesis aims to fill that gap, by focusing primarily on the election of women across preferential (open and ordered list systems) and non-preferential (closed list systems) PR list voting systems. Moreover, unlike the vast majority of previous research, which has relied on aggregate level data only, this research investigates the election of women at the individual candidate level. Such an approach allows the present thesis to consider, next to traditional aggregate level predictors, how party gatekeepers and the news media may either support or hinder women in progressing from candidates to elected representatives. Since the focus is set on the 2009 European Parliament elections, this thesis investigates the process of electing women cross-nationally. The results show that female candidates have a higher likelihood of being elected in non-preferential closed list voting systems than in preferential ordered list voting systems. The results suggest that this is the case because, first, party gatekeepers in ordered list systems place women in less viable electoral list positions than party gatekeepers in closed list systems; second, media cover female candidates less in ordered list systems compared to closed list systems; and finally, female candidates in ordered list systems fail to make up their less competitive starting position with preference votes because preference votes in ordered list systems do not significantly alter the initial party list rankings.
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Chopra, Shubham. "Evolved Design of a Nonlinear Proportional Integral Derivative (NPID) Controller." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/512.
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This research presents a solution to the problem of tuning a PID controller for a nonlinear system. Many systems in industrial applications use a PID controller to control a plant or the process. Conventional PID controllers work in linear systems but are less effective when the plant or the process is nonlinear because PID controllers cannot adapt the gain parameters as needed. In this research we design a Nonlinear PID (NPID) controller using a fuzzy logic system based on the Mamdani type Fuzzy Inference System to control three different DC motor systems. This fuzzy system is responsible for adapting the gain parameters of a conventional PID controller. This fuzzy system's rule base was heuristically evolved using an Evolutionary Algorithm (Differential Evolution). Our results show that a NPID controller can restore a moderately or a heavily under-damped DC motor system under consideration to a desired behavior (slightly under-damped).
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Hines, Anne Michelle. "Characteristics of Active Combustion Control for Liquid-Fuel Systems with Proportional Primary Fuel Modulation." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32569.
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The first part of this work focuses on control experiments performed on an unstable kerosene-fueled turbulent combustor. Using a phase shift controller and primary fuel modulation stability is successfully gained for a wide band of global equivalence ratios allowing the limitations of the control scheme to be characterized. It is shown that control signal saturation can significantly impact the ability of the control scheme to stabilize the system. Three different regions of controllability are defined based on the degree of saturation. A hysteresis behavior is also found to exist for the controller settings depending on whether stability is being maintained or realized for an unstable system.
The second part of this work focuses on the impact that primary fuel modulation has on the fuel spray. Measurements for a simplex nozzle and an air-assist nozzle are taken under both static and dynamic operating conditions with a Phase Doppler Anemometry system. The dynamic modulation is found to significantly impact the spray properties of both nozzles.
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Hojeij, Marie Rita. "Resource allocation techniques for non-orthogonal multiple access systems." Thesis, Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2018. http://www.theses.fr/2018IMTA0085/document.
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Avec l’émergence rapide des applications Internet, il est prévu que le trafic mobile mondial augmente de huit fois entre fin 2018 et 2022. En même temps, les futurs systèmes de communication se devront aussi d’améliorer l'efficacité spectrale des transmissions, le temps de latence et l’équité entre utilisateurs. À cette fin, une technique d’accès multiple non orthogonal (NOMA) a été récemment proposée comme un candidat prometteur pour les futurs accès radio. La technique NOMA est basée sur un nouveau domaine de multiplexage, le domaine des puissances. Elle permet la cohabitation de deux ou plusieurs utilisateurs par sous-porteuse ou sous-bande de fréquence. Cette thèse aborde plusieurs problèmes liés à l’allocation de ressources basée sur NOMA afin d'améliorer les performances du réseau en termes d'efficacité spectrale, de débit et/ou d’équité entre utilisateurs. Dans ce sens, des solutions théoriques et algorithmiques sont proposées et des résultats numériques sont obtenus afin de valider les solutions et de vérifier la capacité des algorithmes proposés à atteindre des performances optimales ou sous-optimales. Après une étude bibliographique des différentes techniques d’allocation de ressources présentée dans le premier chapitre, on propose dans le deuxième chapitre plusieurs stratégies d’allocation de ressource où une réduction de la bande utilisée par les utilisateurs est ciblée. Les résultats de simulation montrent que les stratégies proposées améliorent à la fois l’efficacité spectrale et le débit total des utilisateurs par rapport aux systèmes basés uniquement sur des techniques d’accès orthogonales. Quant au troisième chapitre, il étudie la performance du Proportional Fairness (PF) Scheduler tout en considérant que la bande passante est disponible en totalité. Dans ce sens, plusieurs améliorations basées sur le PF sont proposées, qui offrent au système NOMA des avantages en termes de débit, d’équité entre utilisateurs et de qualité de service. Dans le quatrième chapitre, nous proposons plusieurs techniques d’allocation de ressources qui donnent aux utilisateurs la possibilité de favoriser le débit par rapport à l’équité entre utilisateurs et vice versa. Dans le dernier chapitre, différentes techniques permettant une transmission hybride broadcast/broadband sur la même bande de fréquence sont proposées et comparées à l’état de l’artWith the proliferation of Internet applications, between the end of 2016 and 2022, total mobile traffic is expected to increase by 8 times. At the same time, communications networks are required to further enhance system efficiency, latency, and user fairness. To this end, non-orthogonal multiple access (NOMA) has recently emerged as a promising candidate for future radio access. By exploiting an additional multiplexing domain, the power domain, NOMA allows the cohabitation of two or more users per subcarrier, based on the principle of signal superposition. This dissertation addresses several radio resource allocation problems in mobile communication systems, in order to improve network performance in terms of spectral efficiency, through put, or fairness. Theoretical analysis and algorithmic solutions are derived. Numerical results are obtained to validate our theoretical findings and demonstrate the algorithms ability of attaining optimal or sub-optimal solutions. To this direction, the second chapter of this thesis investigates several new strategies for the allocation of radio resources (bandwidth and transmission power) using NOMA principle, where the minimization of the total amount of used bandwidth is targeted. Extensive simulation results show that the proposed strategies for resource allocation can improve both the spectral efficiency and the cell-edge user throughput, especially when compared to schemes employing only orthogonal signaling. A context where the total bandwidth is available has also been studied, in the 3rd chapter where we investigate the performance of the proportional fairness (PF) scheduler, and we propose modifications to it, at the level of user scheduling and power allocation that show to improve the system capacity, user fairness and QoS. In the 4th chapter, we proposed new pairing metrics that allow to favor the fairness at the expense of the throughput and vice versa. The proposed metrics show enhancements at the level of system capacity, user fairness, and computational complexity. Different techniques that allow a hybrid broadcast/multicast transmission on the same frequency platform are proposed in the last chapter and compared to the state of the art
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Ganguli, Nitu. "The design considerations for display oriented proportional text editors using bit-mapped graphics display systems /." Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66142.
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Ortiz, Jeffrey. "The Influence of Voting Systems on Voter Utility: Who Would Benefit." Scholarship @ Claremont, 2017. http://scholarship.claremont.edu/cmc_theses/1699.
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The voting system a government chooses has influence upon the way people vote, as it has some bearing on the average person’s utility received from voting. In the United States the Electoral College system is used to determine who becomes president-elect, but theoretical arguments have been made to support a change in voting structure to Proportional Representation. I developed my model to understand more about how a change in the voting structure would affect voter utility. My contribution to the research question focuses upon relative benefits of one voter in a specific party to another voter in another party. I used an empirical approach, using data pulled from past elections and survey data. My model suggests that Republican voters would receive a higher utility from a change in the voting system from the Electoral College to Proportional Representation. It is unclear whether Democrats would receive a higher benefit, but at least would receive a lesser utility change than that of the Republican voters.
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Al-Ouran, Rami R. "Linux Implementation of a New Model for Handling Task Dynamics in Proportional Share Based Scheduling Systems." Ohio University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1275681466.
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Erin, Reyhan. "Mixed-integer linear programming approach to U-line balancing with objective of achieving proportional throughput per worker in a dynamic environment /." Online version of thesis, 2007. http://hdl.handle.net/1850/4952.
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Zhang, Songling. "Development and Testing of An Application System for Intersection Data Collection and Analysis." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1513262599088906.
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Samaranayake, Lilantha. "Distributed control of electric drives via Ehernet." Licentiate thesis, KTH, Electrical Systems, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-1656.
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This report presents the work carried out aiming towardsdistributed control of electric drives through a networkcommunication medium with temporal constraints, i.e, Ethernet.A general analysis on time delayed systems is carried out,using state space representation of systems in the discretetime domain. The effect of input time delays is identified andis used in the preceding controller designs. The main hardwareapplication focused in this study is a Brushless DC servomotor, whose speed control loop is closed via a 10 MbpsSwitched Ethernet network. The speed control loop, which isapproximately a decade slower than the current control loop, isopened and interfaced to the network at the sensor/actuatornode. It is closed at the speed controller end at another nodein the same local area network (LAN) forming a distributedcontrol system (DCS).
The Proportional Integral (PI) classical controller designtechnique with ample changes in parameter tuning suitable fortime delayed systems is used. Then the standard Smith Predictoris tested, modified with the algebraic design techniqueCoefficient Diagram Method (CDM), which increases the systemdegrees of freedom. Constant control delay is assumed in thelatter designs despite the slight stochastic nature in thetiming data observations. Hence the poor transient performanceof the system is the price for the robustness inherited to thespeed controllers at the design stage. The controllability andobservability of the DCS may be lost, depending on the range inwhich the control delay is varying. However a state feedbackcontroller deploying on-line delay data, obtained by means ofsynchronizing the sensor node and controller node systemclocks, results in an effective compensation scheme for thenetwork induced delays. Hence the full state feedbackcontroller makes he distributed system transient performanceacceptable for servo applications with the help of poleplacement controller design.
Further, speed synchronizing controllers have been designedsuch that a speed fluctuation caused by a mechanical loadtorque disturbance on one motor is followed effectively by anyother specified motor in the distributed control network with aminimum tracking or synchronizing error. This type ofperformance is often demanded in many industrial applicationssuch as printing, paper, bagging, pick and place and materialcutting.
Keywords:Brushless DC Motor, Control Delay, DistributedMotion Control Systems, Proportional Integral Controller, SmithPredictor, Speed Synchronization, State Feedback Controller,Stochastic Systems, Switched-Ethernet, Synchronizing Error,Time Delayed Systems, Tracking Error
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Babalola, O. E., P. O. Awoyera, M. T. Tran, D. H. Le, O. B. Olalusi, A. Viloria, and D. Ovallos-Gazabon. "Mechanical and durability properties of recycled aggregate concrete with ternary binder system and optimized mix proportion." Elsevier Editora Ltda, 2020. http://hdl.handle.net/10757/656774.
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El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado.This study aimed to investigate the mechanical and durability properties of recycled aggre-gate concrete with a ternary binder system and optimized mix proportion. Two concretebatches were developed using a densified mix design approach (DMDA) to evaluate therequired mix proportions. Batch I have GGBS content varied at 0%, 10%, 20%, 30%, 40% and50% at constant w/b ratio of 0.45, while batch II concrete mix have varied water/binder ratios:0.3, 0.35, 0.4, 0.45 and 0.5 at constant GGBS replacement level of 30%. The fine aggregate(river sand) of the two batches was blended with fly ash at optimum loose packing density(FA + Sand) and superplasticizer (SP) was incorporated in the mix at a constant level of 1.4%.A control mix comprising of natural aggregate was also developed. The results obtainedshowcased the feasibility of producing structural concrete with recycled aggregates usingGGBS and fly ash. The mechanical and durability properties were best at 30% GGBS contentand 0.35 water/binder ratio. The DMDA for mix proportion adopted for RAC contributed sig-nificantly to improving its properties when compared to NAC, especially at the optimumobserved RAC mix with compressive strength of 52 MPa. Also, the mix demonstrated goodpermeability resistance in terms of chloride-ion ingress and capillary water absorption.
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陳奕仲. "Fractional-Order Proportional-Integral Power System Stabilizer." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/13001136437569445265.
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碩士國立臺灣海洋大學
電機工程學系
101
Fractional-order calculus is a generalization of the classical calculus. It allows the order of the differentiation operation to be a fractional number. It has been used in many applications with more accurate descriptions for system dynamic characteristics. The main purpose of this thesis is to investigate the application of the fractional-order theory to the design of power system stabilizer which provides a supplementary control signal to generator excitation system and has been widely adopted in the enhancement of power system stability. This study utilizes the Proportional-Integral controller in the design of power system stabilizer and examine whether the system can resume a new stable operating point in a shorter time period after being perturbed by small disturbance. The results show that the proposed power system stabilizer can provide positive damping for the system and thus can suppress low frequency oscillation to improve power system stability.
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Chiu, Yuh-Siang, and 邱昱翔. "Study of a Dynamic Proportional Combined Brake System for Scooters." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/21658414796952264978.
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碩士國立屏東科技大學
車輛工程系所
103
Because of higher agile and more convenience compared with four-wheel vehicle, two-wheel motorcycle is the most popular transportation that used in Taiwan. For the motorcycle, braking system is one of the critical parts to ensure driver’s safety. The brake system in four-wheel vehicle is with integrated braking system. When drivers step on the brake pedal, all the four wheels produce braking force simultaneously. But most of the two-wheel vehicles are equipped with separate braking system, that is, drivers pull the left brake handle bar to produce the rear braking force, while the right handle bar produces front brake force. Since most of the drivers were not trained well, a lot of unpredictable rollover dangerous were occur because the drivers accidentally pull the right handle first instead of the left one. Therefore it is regulated by governments in many countries that all the scooters must be equipped with ABS or combined brake system (CBS). With those two advanced systems (ABS and CBS), the drivers could execute single handle/pedal to initiate both the front and rear braking system to produce brake forces simultaneously. Currently, most of the CBS designs are of fixed proportional braking force type between the front and rear wheels. When apply this system to drum brake systems, a larger gap between the brake drum and brake shoe resulting from shoes wearing may cause rear wheel lack of brake force and, meanwhile, front wheel locked. This is a critical failure mode existing in the CBS that may cause safety problem. Furthermore, because of comfort and drivability considerations, and the effect of the load transfer phenomena during brake, it is required that the rear brake force should larger than the front wheel at initial braking operation stage. On the other hand, the front wheel should take larger brake force than the rear wheel at higher deceleration brake operations. The fixed proportional CBS is generally unable to offer these requirements. In this thesis, a dynamic proportional combined braking system (DPCBS) and automatic drum gap compensation (DGC) device for drum brake system are studied. Here, the DPCBS system is used to distribute the brake forces between front and rear wheel dynamically according to the pull force amplitude of the driver’s handle bar. The DGC is designed for compensating the gap variations between the brake drum and shoes. This thesis is focused on the development of the DPCBS and the DGC, under the considerations of cost, reliability, and durability. The works include motorcycle dynamics, mechanical design, and prototype testing. The experimental results have shown that the DPCBS could determine the proportion of front and rear wheel brake forces appropriately depending on the amount of the pull force of the brake handle bar. The DCG could adjust the gap for a worn brake shoes efficiently, with a success rates up to 99%.
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Hsueh, Nai-Wei, and 薛乃瑋. "A Weighted Proportional Fairness Scheduling Algorithm in IEEE 802.16 System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/78171973080433060474.
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碩士國立暨南國際大學
通訊工程研究所
99
The traditional Proportional Fair (PF) algorithm is proved effective in the 3G communication systems. Because the traffic type is best-effort, the received service rate is considered in tradeoff between fairness and channel quality. However, for future broadband wireless networks such as IEEE 802.16, diverse applications generate different data rates and require different quality of service (QoS). PF algorithm no longer works well in such scenario. In this paper, we consider the characteristics of different and propose a new scheduling scheme called weighted proportional fair scheduling (WPFS) where the received service rate of a user is normalized by its weight. With several experiments, we design a proper weight factor based on the estimated arrival data rate and the negotiated data rate. Simulation results show that the proposed method can not only effectively improve fairness in heterogeneous traffic environment, but also maintain good spectrum efficiency when comparing with the Maximum Sum Rate algorithm.
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Peng, Shih-yin, and 彭詩尹. "Design and Implementation of Full-digital Proportional Valve and Coding System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/10523134442895726605.
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碩士雲林科技大學
機械工程系碩士班
98
The purpose of the research was aimed at combining the intelligent control with the module design, which assisted in raising the degree of stability. Also, by applying the conception of digitization to control the pneumatic system and integrated the digital controller with other related system interfaces. Thanks to well development of mechanical and electronic technique, the solenoid valve controlled by digital signals progresses toward the direction of lightweight and high-speed. This research uses four same switching valves with different multiple outflow rate (1Q, 2Q, 4Q and 8Q). However, the flows could not follow accurately the multiple outflow rates after the test by ISO 6358 test bench. In addition, the synchronous switching is another problem to successfully implement the full-digital proportional valve. This research sets additional flow control valves on outputs for adjusting the exact outflow, and using the binary code system to improve the accuracy of experimental results. Besides, it also uses the air motor test platform to control the rotational speed by closed-loop control. In short, the full-digital proportional valve could promote the control technology by using ISO 6358 test bench to exactly adjust the output flow rate. The advantage of full-digital proportional valve are simple structure, cheaper cost, lower noise and longer operating life, and thus, it could replace the traditional proportional valve in the future market.