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Dissertations / Theses on the topic 'Control measurements'

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Published: 4 June 2021
Last updated: 30 May 2022

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1

Williams, Grevin Carlton. "Auxiliary measurements in predictive control." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357555.

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2

Buchler, Benjamin Caird. "Electro-optic control of quantum measurements." View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20020527.131758/index.html.

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3

Buchler, Benjamin Caird, and ben buchler@anu edu au. "Electro-optic control of quantum measurements." The Australian National University. Faculty of Science, 2002. http://thesis.anu.edu.au./public/adt-ANU20020527.131758.

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The performance of optical measurement systems is ultimately limited by the quantum nature of light. In this thesis, two techniques for circumventing the standard quantum measurement limits are modelled and tested experimentally. These techniques are electro-optic control and the use of squeezed light. An optical parametric amplifier is used to generate squeezing at 1064nm. The parametric amplifier is pumped by the output of a second harmonic generation cavity, which in turn is pumped by a Nd:YAG laser. By using various frequency locking techniques, the quadrature phase of the squeezing is stabilised, therefore making our squeezed source suitable for long term measurements. The best recorded squeezing is 5.5dB (or 70\%) below the standard quantum limit. The stability of our experiment makes it possible to perform a time domain measurement of photocurrent correlations due to squeezing. This technique allows direct visualisation of the quantum correlations caused by squeezed light. On the road to developing our squeezed source, methods of frequency locking optical cavities are investigated. In particular, the tilt locking method is tested on the second harmonic generation cavity used in the squeezing experiment. The standard method for locking this cavity involves the use of modulation sidebands, therefore leading to a noisy second harmonic wave. The modulation free tilt-locking method, which is based on spatial mode interference, is shown to be a reliable alternative. In some cases, electro-optic control may be used to suppress quantum measurement noise. Electro-optic feedback is investigated as a method for suppressing radiation pressure noise in an optical cavity. Modelling shows that the `squashed' light inside a feedback loop can reduce radiation pressure noise by a factor of two below the standard quantum limit. This result in then applied to a thermal noise detection system. The reduction in radiation pressure noise is shown to give improved thermal noise sensitivity, therefore proving that the modified noise properties of light inside a feedback loop can be used to reduce quantum measurement noise. Another method of electro-optic control is electro-optic feedforward. This is also investigated as a technique for manipulating quantum measurements. It is used to achieve noiseless amplification of a phase quadrature signal. The results clearly show that a feedforward loop is a phase sensitive amplifier that breaks the quantum limit for phase insensitive amplification. This experiment is the first demonstration of noiseless phase quadrature amplification. Finally, feedforward is explored as a tool for improving the performance of quantum nondemolition measurements. Modelling shows that feedforward is an effective method of increasing signal transfer efficiency. Feedforward is also shown to work well in conjunction with meter squeezing. Together, meter squeezing and feedforward provide a comprehensive quantum nondemolition enhancement package. Using the squeezed light from our optical parametric amplifier, an experimental demonstration of the enhancement scheme is shown to achieve record signal transfer efficiency of $T_{s}+T_{m}=1.81$.
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4

Thoutou, Sayi Mbani. "Quality control charts under random fuzzy measurements." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/19140.

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Includes bibliographical references. .
We consider statistical process control charts as tools that statistical process control utilizes for monitoring changes; identifying process variations and their causes in industrial processes (manufacturing processes) and which help manufacturers to take the appropriate action, rectify problems or improve manufacturing processes so as to produce good quality products. As an essential tool, researchers have always paid attention to the development of process control charts. Also, the sample sizes required for establishing control charts are often under discussion depending on the field of study. Of late, the problem of Fuzziness and Randomness often brought into modern manufacturing processes by the shortening product life cycles and diversification (in product designs, raw material supply etc) has compelled researchers to invoke quality control methodologies in their search for high customer satisfaction and better market shares (Guo et al 2006). We herein focus our attention on small sample sizes and focus on the development of quality control charts in terms of the Economic Design of Quality Control Charts; based on credibility measure theory under Random Fuzzy Measurements and Small Sample Asymptotic Distribution Theory. Economic process data will be collected from the study of Duncan (1956) in terms of these new developments as an illustrative example. or/Producer, otherwise they are undertaken with respect to the market as a whole. The techniques used for tackling the complex issues are diverse and wide-ranging as ascertained from the existing literature on the subject. The global ideology focuses on combining two streams of thought: the production optimisation and equilibrium techniques of the old monopolistic, cost-saving industry and; the new dynamic profit-maximising and risk-mitigating competitive industry. Financial engineering in a new and poorly understood market for electrical power must now take place in conjunction with - yet also constrained by - the physical production and distribution of the commodity.
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5

Agatep, Allan. "Voltage Stability Analysis Using Simulated Synchrophasor Measurements." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/957.

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An increase in demand for electric power has forced utility transmission systems to continuously operate under stressed conditions, which are close to instability limits. Operating power systems under such conditions along with inadequate reactive power reserves initiates a sequence of voltage instability points and can ultimately lead to a system voltage collapse. Significant research have been focused on time-synchronized measurements of power systems which can be used to frequently determine the state of a power system and can lead to a more robust protection, control and operation performance. This thesis discusses the applicability of two voltage stability synchrophasor-based indices from literature to analyze the stability of a power system. Various load flow scenarios were conducted on the BPA 10-Bus system and the IEEE 39-Bus System using PowerWorld Simulator. The two indices were analyzed and compared against each other along with other well-known methods. Results show that their performances are coherent to each other regarding to voltage stability of the system; the indices can also predict voltage collapse as well as provide insight on other locations within the system that can contribute to instability.
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6

Poonawala, Hasan A. "Formation control and connectivity control for mobile robot networks using vision based measurements." Thesis, The University of Texas at Dallas, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3629039.

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Several algorithms for multi-robot coordination assume that the communication network of a team of mobile robots is connected, so that information can be exchanged between any two robots in the team. The network topology is often state-dependent, and thus the robots may move in a way that causes the network to become disconnected. This dissertation proposes continuous time control laws that preserve the connectivity for both undirected and directed mobile robot networks, which can be used along with additional task-dependent control actions. An additional aim of the dissertation is to provide control algorithms to achieve multi-robot coordination methods using vision-based feedback. Feedback control laws are presented that achieve tracking of desired relative positions between a pair of non-holonomic mobile robots using relative position measurements only. Issues pertaining to vision-based implementation of the connectivity control laws are discussed, and solutions are presented.

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7

Levedahl, Blaine Alexander. "Vehicle Control in Full Unsteady Flow Using Surface Measurements." NCSU, 2010. http://www.lib.ncsu.edu/theses/available/etd-02272010-190048/.

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This dissertation is the first comprehensive attempt to address a new engineering problem: control of a vehicle maneuvering in a full unsteady flow field. The approach to the solution is focused in three main areas: modeling of a vehicle in full unsteady flow, control of a vehicle in full unsteady flow, and synthesizing the fluid loads for use in control of a vehicle maneuvering in a full unsteady flow field. To model a vehicle maneuvering in a full unsteady flow field this dissertation develops the Coupled Fluid Vehicle (CFV) model in which the fluid, which is a sum of a finite number of spatially dependent velocity fields whose contributions vary with time, is coupled to the vehicle rigid-body equations of motion. To control a vehicle maneuvering in a full unsteady flow field this dissertation develops the Fluid Compensation Control (FCC) strategy which gives the designer an opportunity to include the fluid states, in addition to the vehicle states, in the control law and an opportunity to balance reducing the fluid dynamic load through compensation and reducing the state error through regulation. To synthesize the fluid loads this dissertation has attempted to forward current work on the prediction of fluid loads from stagnation and separation point measurements using the Kutta principle, which says that the velocity around a vehicle is a smoothly varying function and that it is determined up to a multiplicative constant by its nodes (stagnation, separation, and reattachment points/lines), and by conducting an experiment to attempt to determine the correlation of the fluidic loads from the orientation and separation lines on a 3-dimensional bluff body.
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8

Johnsson, Roger. "Indirect measurements for control and diagnostics of IC engines /." Luleå, 2004. http://epubl.luth.se/1402-1544/2004/60/index.html.

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9

Vilela, João Vítor Cavalcanti. "Attitude control of rigid bodies with time-delayed measurements." reponame:Repositório Institucional da UnB, 2016. http://repositorio.unb.br/handle/10482/23347.

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Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2016.
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Desenvolver condições de estabilidade e projeto de controladores para controle de atitude de corpos rígidos sujeitos a atrasos no tempo é o objetivo desta dissertação. O modelo utilizado, escrito na forma de equação diferencial atrasada, advém das equações cinemática e dinâmica do corpo rígido modificadas considerando atrasos temporais. Estes atrasos podem representar latências dos sensores e atuadores, além de tempo de processamento de dados (e.g., cômputo dos sinais de controle) e de transmissão de dados quando os elementos do sistema de controle estão conectados por redes comunicação. Em particular, são supostos atrasos desconhecidos e variantes no tempo, o que lhes confere generalidade maior do que os casos abordados até então na literatura, onde os poucos trabalhos que abordaram o problema aprensentam resultados dependentes do valor exato do atraso ou o assumem constante, o que na prática dificilmente é verificado. As condições obtidas, escritas na forma de teoremas, são baseadas em sua maioria na teoria de Lyapunov-Krasovskii. Outro aspecto que diferencia este trabalho em relação aos demais é que os teoremas são formulados como desigualdades matriciais lineares (LMIs, em inglês). A formulação por LMIs é vantajosa não só pelas excelentes propriedades computacionais das LMIs (resolução em tempo polinomial), mas também porque as condições são escritas com variáveis, reduzindo o conservadorismo dos resultados e permitindo a automação do processo de verificação de estabilidade e projeto de controladores, o que também é uma contribuição desta dissertação. Além disso, os controladores possuem performance garantida segundo o critério H∞ , isto é, além de estabilidade, este tipo de controlador tem um nível mínimo de atenuação de perturbações assegurado.
Developing stability and controller design conditions for rigid body attitude control subjected to time delays is the goal of this dissertation. The rigid body model, written in form of functional differential equation, stems from the kinematic and dynamic rigid body equations, modified to take time delays into account. Such time delays may represent sensor and actuator latency, processing time (e.g., computing control signals) and transmission lags when the control system elements are connected by communication networks. In particular, time delays are considered unknown and time-varying, which makes them generalizations of previous results in literature, where the scarce works to tackle the problem present results dependent on the exact time delay value, which is hardly verified in practice. The proposed conditions, written as theorems, are mostly based on Lyapunov-Krasovskii theory. Another aspect that sets this work apart is that theorems are formulated as linear matrix inequalities (LMIs). LMI formulation is advantageous not only for its excellent computational properties (polynomial time solving), but also for the conditions are written with variables, which reduces results' conservatism e enables automating stability verification and controller design, which is a contribution of this work as well. In addition, controllers attain guaranteed performance according to H∞ criterion, that is, besides stability, this kind of controller presents a known minimum level of perturbation attenuation.
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10

Maguire, Sean Thomas George. "Attitude determination using low frequency radio polarisation measurements." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708927.

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11

Constantinides, N. "Adaptive control of the milling process and tool wear measurements." Thesis, University of Sheffield, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294141.

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12

Choi, Young Jin. "Application of tomographic techniques for rheological measurements and process control /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2003. http://uclibs.org/PID/11984.

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13

Abi, Assali López Wuendy Y. "Optimal selection of measurements and manipulated variables for production control." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8780.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Chemical and Biomolecular Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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14

KUHNER, GUILHERME SESTO. "DIGITAL CONTROL OF A PNEUMATIC POSITIONING SYSTEM FOR BIOMAGNET MEASUREMENTS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1996. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9376@1.

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Este trabalho apresenta uma solução para o problema de posicionamento automático preciso de um corpo em um plano horizontal, atendendo à restrição de não gerar campo magnético significativo junto ao objeto a ser posicionado. A motivação do trabalho reside na necessidade, por parte do Laboratório de Supercondutividade Aplicada e Magnetismo (LSAM) do Departamento de Física, de um posicionador para experimentação em magnetocardiografia. Inicialmente são discutidas as tecnologias de automação aplicáveis ao problema, justificando-se a opção por um sistema pneumático de atuação. O sistema posicionar montado é então descrito em profundidade, abordando-se os aspectos relacionados à geometria do problema em questão, materiais, montagens mecânicas e o sistema de controle digital. A seguir é apresentada uma abordagem matemática para o problema de controle de posição em malha fechada, visando à definição de uma lei de controle aplicável ao caso em estudo. Alguns resultados analíticos são obtidos para controle de sistema caracterizados por atrito Coulombiano, ao mesmo tempo em que se desenvolve um modelo para simulação numérica da dinâmica de movimento do posicionador. Com base nestas duas ferramentas, é apresentada uma discussão sobre a aplicabilidade dos controladores da família PID ao caso específico considerado. Por fim, resultados reais obtidos com a lei de controle proposta são comparadores aos resultados simulados, mostrando-se a validade e a utilidade do modelo teórico.
This thesis presents a solution or the problem of automatic precise positioning of na object in the horizontal plane, not generating any significative magnetic field in the region close to the object to be positioned. The study presented was developed as part of an effort to fulfill a necessity for a positioning system for magnetocardiography experimentation in the Magnetism and Applied Supercondutivity Laboratory of the Departament of Physics of this University. A discussion over applicable automation option is presents, along with a justification for a choice of a pneumatic actuating system. The whole precise positioning assembly is described in detail, including subjects such as movement geometry, material, mechanical structures and the digital control system. A mathematical study of the closed of the closed loop position control problem is then developed, aiming to define a control algorithm applicable to the problem. Algebraic analysis is used to describe the influence of Coulomb friction over the equations of motion of a proportional position control system, while a model for simulations experiments of the assembly´s positioning dynamics is developed. These tools are used as the basis for a discussion over the applicability of the PID controlers in the case in study. Moreover, the behavior of the proposed algorithm is recorded and compared to the results of the simulations, showing the correctness and the utility of the theoretical analysis.
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15

Huang, Chiung-Yi. "The application of phasor measurements for adaptive protection and control." Thesis, Virginia Tech, 1991. http://hdl.handle.net/10919/42131.

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This thesis describes an adaptive protection scheme that performs the collection of the voltage and current phasors during post-fault period, tracking the power swing phenomena, identifying the onset of instability, and then issuing a stabilizing command. In this work, the protection system is to maintain the reliability! ensure the secure operation, and prevent total collapse of the power system. The work is based upon methods of clustering for meter placement in a bulk power system, and selecting the pilot points for installing the phasor measurement units (PMU) to measure the bus voltage phasors and associated branch current phasors. According to the network law, fast calculation of state estimation can be made from these measurements. Because the on-line assessment of transient stability has to provide a quick and approximate result, the direct method which determines stability without explicit integration techniques is applicable in this study. The results of the system stability prediction in real-time by digital computer simulation under stable and unstable operating conditions are presented.
Master of Science

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16

Millican, Anthony J. "Bio-Inspired Trailing Edge Noise Control: Acoustic and Flow Measurements." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78376.

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Trailing edge noise control is an important problem associated mainly with wind turbines. As turbulence in the air flows over a wind turbine blade, it impacts the trailing edge and scatters, producing noise. Traditional methods of noise control involve modifying the physical trailing edge, or the scattering efficiency. Recently, inspired by the downy covering of owl feathers, researchers developed treatments that can be applied to the trailing edge to significantly reduce trailing edge noise. It was hypothesized that the noise reduction was due to manipulating the incoming turbulence, rather than the physical trailing edge itself, representing a new method of noise control. However, only acoustic measurements were reported, meaning the associated flow physics were still unknown. This thesis describes a comprehensive wall jet experiment to measure the flow effects near the bio-inspired treatments, termed “finlets” and “rails,” and relate those flow effects to the noise reduction. This was done using far-field microphones, a single hot-wire probe, and surface pressure fluctuation microphones. The far-field noise results showed that each treatment successfully reduced the noise, by up to 7 dB in some cases. The surface pressure measurements showed that the spanwise coherence was slightly reduced when the treatments were applied to the trailing edge. The velocity measurements clearly established the presence of a shear layer near the top of the treatments. As a whole, the dataset led to the shear-sheltering hypothesis: the bio-inspired treatments are effective based on reducing the spanwise pressure correlation and by sheltering the trailing edge from turbulent structures with the shear layer they create.
Master of Science
This thesis describes a project aimed at developing a technology inspired by the silent flight of owls, with the end goal of using this technology to reduce the noise generated by wind turbines. Specifically, the phenomenon known as "trailing edge noise" is the primary source of wind turbine noise, and is the noise source of interest here. It occurs when air turbulence (which can be thought of as unsteady air fluctuations) crashes into the rear (trailing) edge of wind turbine blades, scattering and producing noise. Typically, methods of reducing this noise source involve changing the shape of the trailing edge; this may not always be practical for existing wind turbines. Recently, inspired by the downy covering of owl feathers, researchers developed treatments that can be applied directly to the trailing edge, significantly reducing trailing edge noise. This bio-inspired concept was verified with numerous acoustic measurements. Based on those measurements, researchers hypothesized that the noise reduction was achieved by manipulating the incoming turbulence before it scattered off the trailing edge, rather than by changing the existing wind turbine blade, representing a new method of trailing edge noise control. However, as only acoustic measurements (not flow measurements) were reported, the changes in turbulence could not be examined. With the above motivation in mind, this thesis describes a comprehensive wind tunnel experiment to measure the changes in the aerodynamics and turbulence near the bio-inspired treatments, and relate those changes to the reduction in trailing edge noise. This was done using a hot-wire probe to measure the aerodynamics, as well as microphones to measure the radiated noise and surface pressure fluctuations. As a whole, the experimental results led to the shear-sheltering hypothesis: the bio-inspired treatments are effective based on the creation of a shear layer (a thin region between areas with different air speeds) which shelters the trailing edge from some turbulence, as well as by de-correlating surface pressure fluctuations along the trailing edge.
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17

Zhu, Ruoxi. "Online Voltage Stability Monitoring and Control Using Limited Synchrophasor Measurements." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/97197.

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As the scale and complexity of an interconnected power grid has increased significantly, power systems can be operated close to the verge of voltage instability. With the application of Phasor Measurement Units (PMUs), dispatchers are able to monitor long term voltage stability in a real time operational environment. This research addresses the critical issues by proposing three different methods. Voltage Stability Assessment Index (VSAI) is a Thévenin Equivalent (TE) based method considering voltage dynamic mechanisms. To extend the model from one load bus to a critical load center, Optimal Power Flow-Loading limit (OPF-LI) is developed to assess the voltage stability margin. To utilize limited available PMU measurements, State Calculator (SC) is included in the algorithm to approximate the dynamic states at the buses where PMU measurements are not available. The online voltage regulating method in terms of On-load Tap Changer (OLTC) control is also investigated. The methods proposed in this research have been validated with the test cases from the WECC 179 bus system.
M.S.
This thesis proposed a hybrid solution of voltage stability monitoring and control in a power system. For the performance of motors, heaters or other loads in the power system, it is important that the customers are supplied with stable voltage. The variation of the voltage may cause damages to the load. Therefore, the methods in this thesis provides a feasible solution to monitor voltage stability of load centers in a power system. In addition, a novel approach for voltage control is proposed to prevent a voltage collapse of the system. The simulation results illustrate that the approach introduced in this thesis is promising for real time application.
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18

Willson, James Griffin. "Quantitative force measurements of pneumatic control on a wing/strake model." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/24020.

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Approved for public release; distribution is unlimited
A low-speed wind-tunnel study to quantitatively measure the lift and drag effects of pneumatically controlling a leading edge vortex generated by a half-span, genericfighter- wing model was conducted. The study measured the added lift and drag upon the model, throughout a range of angles of attack, utilizing blowing tubes of different geometry and orientations. The effects of blowing upon the high pressure side of the strake were also investigated. Results showed that the effects of blowing were limited to changes in lift with no apparent changes in drag. Blowing appeared to reattach the flow during the initial stages of wing stall. Blowing increased lift by a maximum of 3.75% at angles of attack greater than 25°. The effects of blowing appeared oscillatory with respect to angle of attack. Blowing rates were varied from C„=0.0 to 0.0035 in an attempt to determine an optimum. It was found that changes in blowing rates had little effect upon ACL .
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19

Croxford, Anthony John. "Investigation of dynamics and control of fluidised beds using pressure measurements." Thesis, University of Bristol, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425085.

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20

Adewole, Adeyemi Charles. "Voltage stability assessment and wide area protection/control using synchrophasor measurements." Thesis, Cape Peninsula University of Technology, 2016. http://hdl.handle.net/20.500.11838/2380.

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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2016.
Electric power systems are being operated closer to their designed stability limits due to the constraints caused by the continuous increase in system loading, and the lack of new power stations and transmission network infrastructure to support this increase in system loading. This coupled with the practice of long distance bulk power transmission and cascading contingencies, makes system instability and consequently blackouts inevitable. In such scenarios, system instabilities like voltage instability becomes a serious threat to the secure operation of the power system, and voltage collapse (system-wide blackouts) are prone to occur. This is often compounded by the unavailability of real-time system measurements for situational awareness from the existing Supervisory Control and Data Acquisition (SCADA)/Energy Management System (EMS) platforms which are usually based on unsynchronized SCADA measurements with a slow reporting rate of 1 measurement every 2-10 seconds. This Doctoral thesis proposes non-iterative algorithms and methods of solution based on the IEEE C37.118 synchrophasor measurements from Phasor Measurement Units (PMUs) with a high reporting rate of up to 200 measurements every second (200 fps) for voltage stability assessment and automated wide area Centralised Protection/Control (CPC) against catastrophic voltage instabilities/blackouts in power systems. Extended formulations are proposed for the Optimal Placement of PMUs (OPP) in power systems with respect to voltage stability assessment. The impact of zero injection buses, critical buses, and PMU redundancy is considered in the formulation of the OPP problem solution. The extended formulations made use of Binary Integer programming (BIP) and Modal Participation Factors (MPFs) derived from the eigenvalues of the power flow Jacobian.
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21

Paparella, Rita. "Beam orbit control in TESLA superconducting cavities from dipole mode measurements." Paris 11, 2006. http://www.theses.fr/2006PA112153.

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Le passage d'un paquet d'électrons à l'intérieur d'une cavité supraconductrice TESLA soit donne lieu à un couplage avec le mode accélérant, soit excite un spectre de modes d'ordre supérieur (HOMs, Higher Order Modes). Une étude analytique sur le champ électromagnétique et les champs de sillages dans une cavité cylindrique a été effectuée. En plus, une étude expérimentale a été conduite grâce à l'utilise de Tesla Test Facility 2, au DESY d'Hambourg. Les excentricités et les désalignements des cavités ont été trouvés en observant les signaux des modes supérieurs avec un analyseur de spectre, ainsi comme les deux polarisations de chaque mode ont été distinguées. En suite, grâce à l'installation d'un système de diagnostique basé sure les HOMs, on a peut étudier plus efficacement la réponse du champ électromagnétique au passage du faisceau, ainsi que démontrer la possibilité de l'utilise des HOMs pour contrôler l'orbite du faisceau dans la partie froide de l'accélérateur. Pour l'analyse des signaux des modes monopolaires et dipolaires on a premièrement introduit le concept de régression linéaire, et en l'appliquant on a obtenu un résolution sur la position du faisceau de 3 um. Successivement la Model Independant Analysis (MIA), basée sur la décomposition en valeurs singuliers (SVD), a été utilisée pour obtenir une prédiction sur la position du faisceau relative aux signaux des HOMs précédemment enregistrés. La procédure d'utilise des HOMs comme moniteurs de la position du faisceau a donc été expliquée et l'utilité de modes dipolaires pour la diagnostique du faisceau avec une résolution de moins que 5 um a été démontrée
The passage of an electron bunch inside a superconductive cavity TESLA boyh gives place to a coupling with the accelerating mode, and excites a spectrum of Higher Order Modes (HOMs). An analytical study on the electromagnetic fields and wake fields in a cylindrical cavity has been carried out. Moreover, an experimental study has been made at Tesla Test Facility 2, at DESY of Hamburg. The eccentricities and misalignments of the cavities were found by observing the signals of the higher modes with a spectrum analyzer, thus the two polarizations of each mode were distinguished. Moreover, after the installation of a diagnostic system based on HOMs, a study about the response of the electromagnetic field to the passage of the beam as been carried out, and the possibility of using HOMs as beam position monitor in the cold section of the accelerator has been show. For the analysis of the signals of the monopole and dipole modes the concept of linear regression has been introduced, and by applying it a resolution on the beam position of 3 um has been obtained. Successively a Model Independant Analysis (MIA), based on the Singular Values Decomposition (SVD), was used to obtain a prediction on the beam position related to the HOMS signals previously recorded. The procedure of using the HOMs as beam position monitors was thus explained and the utility of the dipole modes for the beam diagnostic with a resolution of less than 5 um was shown
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22

Ruuska, J. (Jari). "Special measurements and control models for a basic oxygen furnace (BOF)." Doctoral thesis, Oulun yliopisto, 2012. http://urn.fi/urn:isbn:9789514298028.

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Abstract The target in this thesis was to study selected special measurements in a basic oxygen furnace (BOF) and develop a model to predict the steel temperature at the end of the oxygen blow. Furthermore, the work aimed at increasing knowledge on measurements and phenomena in the converter and in this way improve the possibility of more efficient monitoring and control of the process. Special measurements were investigated to obtain more knowledge about their usability in running the converter process. Analysing the measurement results also led to new process knowledge. The usage of a Radio Wave Interferometer (RWI) was seen as beneficial as it makes it possible to see the rising trend of the liquid surface level in advance and to perform some corrective actions to avoid excessive foaming and possible splashing out from the converter. Acoustic measurement could also detect trends in advance, but it was found to be sensitive to disturbing noise from the surroundings. Splashing measurement gives information about the current state of the slag but not advance information. Nevertheless, the measurements revealed several factors that usually increase splashing. It would be best to use the knowledge from two different measurements, for example RWI and splashing measurement, to predict increasing splashing, which causes significant iron losses. The development of the models for end temperature prediction and additional materials provided a lot of knowledge about the factors affecting the temperature. Factors that were used in grouping were the BOF number, heat size and end carbon content. However, there were many heats that did not satisfy the target. Furthermore, there is a need for additional research into temperature progress and its control in BOF. It would also be useful to study the effect of additional materials more systematically. There are other factors, such as the oxygen flow rate and lance height, which affect the temperature that are not included in the models. Some of the factors are measurable and some are not. There is still a need for more research in this area. This work strengthens the impression that the converter process is a complex one. It was noticed; as always in process development, that continuous monitoring and efforts are required to observe the changes in process conditions, raw materials or running practices. Otherwise, the benefit of the improvements and models will be lessened. However, it would be possible to set acknowledged routines and warnings into the improved monitoring system to help the operators notice the need for system tuning. A monitoring system would provide financial benefits in terms of having fewer reblowings, better yield and better quality of final product. Savings in raw materials can also be attained as the controllability of the process becomes better. As the monitoring system contains a database of guidelines, it would form a good basis for new employees to become familiar with the process and thus facilitate their training
Tiivistelmä Tämän opinnäytteen tarkoitus oli tutkia teräskonvertterin valittuja erikoismittauksia ja kehittää malli ennustamaan teräksen lämpötilaa happipuhalluksen lopussa. Työn tarkoituksena oli lisätä tietämystä mittauksista ja ilmiöistä konvertterissa ja tällä tapaa lisätä mahdollisuuksia prosessin tehokkaampaan monitorointiin ja ohjaukseen. Erikoismittauksia tutkittiin lisätietämyksen saamiseksi niiden käytettävyydestä konvertteriprosessin ajossa. Mittausten analysointi tuotti myös uutta prosessitietämystä. Radioaaltointerferometrin (RWI) käyttö koettiin hyödylliseksi, koska on mahdollista havaita kuonan pinnankorkeuden nousu ennakkoon ja suorittaa joitakin korjaavia toimenpiteitä liiallisen kuohumisen ja lopulta roiskumisen estämiseksi ulos konvertterista. Äänimittaus voi myös havaita trendin ennakkoon, mutta huomattiin sen olevan herkkä ympäristön häiriöäänille. Roiskemittaus antaa tietoa kuonan sen hetkisestä tilasta, mutta ei ennakkoon. Mittaukset toivat kuitenkin esiin useita tekijöitä, jotka yleensä lisäävät roiskumista. Olisi parasta käyttää kahden eri mittauksen tietoa, RWI ja roiskemittaus, ennustettaessa lisääntyvää roiskumista, joka aiheuttaa huomattavia rautahäviöitä. Loppulämpötilan ennustamiseen kehitetyn mallin ja lisäainemallin kehittäminen antoi paljon tietoa tekijöistä, jotka vaikuttavat lämpötilaan. Tekijät, joita käytettiin ryhmittelyssä, olivat konvertterinumero, panoskoko ja loppuhiilipitoisuus. Mallin soveltamisesta huolimatta jäi edelleen useita sulatuksia, jotka eivät osuneet tavoitteeseen. On edelleen tarve teräskonvertterin lämpötilakäyttäytymisen ja sen hallinnan lisätutkimukselle konvertterissa. Myös lisäaineiden vaikutusta lämpötilaan olisi hyödyllistä tutkia systemaattisemmin. On edelleen muita tekijöitä, esimerkiksi hapen virtausnopeus ja lanssin korkeus, jotka vaikuttavat lämpötilaan, mutta jotka eivät ole mukana malleissa. Osa näistä tekijöistä on mitattavia suureita ja osa ei. Lisätutkimukselle on edelleen tilaa tällä alueella. Tämä työ vahvistaa edelleen käsitystä, että konvertteriprosessi on monimutkainen. Huomattiin, kuten aina prosessikehityksessä, että jatkuvaa kehitystyötä pitää tehdä prosessiolosuhteiden, raaka-aineiden ja ajopraktiikoiden muutosten huomaamiseksi. Muuten parannusten ja mallien antama hyöty heikkenee. Monitorointijärjestelmään olisi mahdollista kehittää rutiineja ja varoituksia operaattorien avuksi, jotta he huomaisivat järjestelmävirityksen tarpeen. Monitorointijärjestelmä toisi taloudellista hyötyä, mm. lisäpuhallusten vähentymisen, lopputuotteen paremman saannon ja laadun muodossa. Raaka-ainesäästöjä voidaan saavuttaa prosessin ohjattavuuden parantuessa. Monitorointijärjestelmän sisältäessä sääntötietokannan, se luo hyvän pohjan uusille työntekijöille tutustua prosessiin ja näin heidän koulutuksensa onnistuisi helpommin
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23

Keating, Katrina Ann. "Noncognitive Variables for Placement| A Randomized Control Trial." Thesis, San Francisco State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10822840.

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This study was born out of a concern that U.S. community colleges were currently using or considering using noncognitive variables for academic placement without an understanding of how students would react to these scales in a high-stakes setting. While the use of noncognitive variables for placement often stems from a desire to overcome the myriad of limitations of content-based placement tests, the researcher was concerned that noncognitive variables had the potential to become an extension of the problems caused by the test.

This study was guided by two research questions: How does the high-stakes nature of academic placement impact student responses on noncognitive scales? How does the context, demand, characteristics, and framing of the noncognitive variables impact stereotype threat, if at all? The researcher performed a random control trial of incoming community college students to determine how they might react to questions about noncognitive variables. One group was told their responses would be used for placement, and the other was told that their responses would be used to improve instruction.

The major findings suggest that initial framing played a role in participant responses and lowered responses on some noncognitive variables, but that the act of having taken a placement test was also a moderator of student behavior and whether or not students believed the initial framing. Stereotype threat susceptibility appeared to have a statistically significant relationship with some participants’ responses on some noncognitive scales, and there was evidence that initial framing was not related. Finally, while participants were generally honest, those who did change their answers did so in a manner that was inconsistent, more so when given high stakes framing.

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Marques, Steven Joseph Jr. "Passive Scalar Measurements In Actively Excited Free Shear Flows." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36759.

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The objectives of this study were to implement a system to measure mixing in nonreacting flows and to study the mass transfer characteristics of two actively excited turbulent jets. This thesis describes the acquisition and analysis of phase-locked concentration field data using planar Mie scattering from smoke particles and planar laser-induced fluorescence of acetone. Both techniques were shown to be effective in providing information for the actively excited nozzles. However, the laser-induced fluorescence technique was superior for revealing detail in the flowfield structure. Spatial mode control techniques were applied to a triangular nozzle with vibrating actuators as the three sides and a swirl nozzle with pulsating tangential air jets. The effect of the different spatial modes on jet column development and the far fields of both nozzles is presented. Two- and three-dimensional iso-intensity contours, showing the relative intensity of light scattered by the nozzle fluid marker, were generated to show the flow structure. The areas inside the iso-intensity contours in the far field were also measured to determine relative effectiveness of nozzle fluid transport. Large scale structures were visible in the three-dimensional iso-intensity contours from both nozzles. In addition, the transport of seeded nozzle fluid was enhanced by the spatial mode excitation for both nozzles. Spatial mode excitation was also able to affect the shape of the far field contour. In particular, the first counterrotating helical mode, m=±1, generated the greatest effect on nozzle fluid transport and the most pronounced elliptical contour shape in the far field.
Master of Science
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25

Stewart, Stacyann B. "Grit and self-control as predictors of first-year student success." Thesis, University of Southern Maine, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3722559.

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The objective of this exploratory quantitative study was to investigate the relationships between grit, self-control, and the first academic semester of college students, and determine if the relationships differed by gender. Two research questions were examined; (1) What are the relationships between the individual factors of grit, self-control, and first-semester college GPA? And do they differ by gender? and (2) What combinations of factors (grit, self-control, high school GPA, and SAT scores) best predicts first-semester college GPA? And do they differ by gender?

This study investigated 88 first-time, first-year college students and their academic success during their first college semester using three instruments: the 12-Item Grit Scale, the Self-Control Scale, and the Short-Form C of the Marlowe-Crowne Social Desirability Scale. Correlation analysis and stepwise regression methods were used to examine relationships.

Findings from this study reinforce that high school GPA and SAT scores are predictors of college academic performance. However, the relationships between high school GPA, SAT scores, and fall GPA in this study were not as strong as indicated in previous studies. Results indicated that grit and academic performance had no relationship, while a small yet significant relationship was found between self-control and academic performance. Additionally, male and female students had somewhat different results in terms of grit, self-control, and academic performance. Predictors of academic performance for male students were high school GPA, self-control, and SAT scores. Female students’ predictors were high school GPA and SAT scores. During an exploration process in this study, self-control was the only predictor of students’ fall GPA when it was less than 2.67. Gender did not play a role in that particular finding, and the best and only predictor of all students’ fall GPA < 2.67 was self-control. That indicated that levels of earned GPA may be related to levels of self-control. The overall findings of this study contribute to further understanding factors related to college success, graduation, and better options for both life and career.

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26

Barajas, Leandro G. "Process Control in High-Noise Environments Using A Limited Number Of Measurements." Diss., Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/7741.

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The topic of this dissertation is the derivation, development, and evaluation of novel hybrid algorithms for process control that use a limited number of measurements and that are suitable to operate in the presence of large amounts of process noise. As an initial step, affine and neural network statistical process models are developed in order to simulate the steady-state system behavior. Such models are vitally important in the evaluation, testing, and improvement of all other process controllers referred to in this work. Afterwards, fuzzy logic controller rules are assimilated into a mathematical characterization of a model that includes the modes and mode transition rules that define a hybrid hierarchical process control. The main processing entity in such framework is a closed-loop control algorithm that performs global and then local optimizations in order to asymptotically reach minimum bias error; this is done while requiring a minimum number of iterations in order to promptly reach a desired operational window. The results of this research are applied to surface mount technology manufacturing-lines yield optimization. This work achieves a practical degree of control over the solder-paste volume deposition in the Stencil Printing Process (SPP). Results show that it is possible to change the operating point of the process by modifying certain machine parameters and even compensate for the difference in height due to change in print direction.
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27

Göckede, Mathias. "Adoption of footprint methods for the quality control of Eddy-covariance measurements." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975128248.

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28

Jones, Warren Anthony. "CONTROL OF DIFFUSING DUCT FLOWUSING ACTIVE VORTEX GENERATORSWITH HOT-FILM SENSOR MEASUREMENTS." NCSU, 2001. http://www.lib.ncsu.edu/theses/available/etd-20010528-224402.

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Experiments have been conducted using vane-type vortex generators to control flow separation and exit flow distortion in a diffusing duct. The primary purpose is to examine the feasibility of using surface-mounted hot-film sensors to determine the extent of exit flow distortion. The experimental set-up consists of a two-dimensional blow down type wind tunnel with a variable diffuser exit. One diffuser wall is curved to produce a Stratford-like pressure gradient. The wall's placement is adjustable such that the adverse pressure gradient can be adjusted to promote separation. An active vortex generator array that can be placed at three streamwise locations is used to reduce the extent of flow separation and exit distortion.Diffuser surface pressure and exit total pressure measurements are obtained and compared to the hot-film data. The time-averaged mean and rms voltages from the hot-film data are used as indicators of flow separation and exit flow distortion.Results show that, with the use of the vortex generators, high mean voltages and low levels of rms voltage correlate well with improved pressure recovery. Conversely, poorer pressure recovery is associated with lower mean voltages and higher rms values compared to the baseline cases. Increased total pressures at the diffuser exit are accompanied by increases in hot-film mean voltages. These indicate higher shear stresses, which also correspond to increased flow uniformity. Lower variations in the rms voltages compared to the baseline cases also correlated well with improved total pressures at the diffuser exit.

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29

Dawson, A. J. "Process and production measurements for automatic inspection and control of injection moulding." Thesis, University of Bradford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535848.

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30

Ransford, Kevin M. "Baseline vibration measurements of remotely piloted helicopters for higher harmonic control research." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/26396.

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31

Xu, Gang. "Manipulation and quantum control of ultracold atoms and molecules for precision measurements." Access restricted to users with UT Austin EID, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3038196.

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32

Marstorp, Gustav. "Automated Control System for Dust Concentration Measurements Using European Standard Reference Method." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292583.

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Most companies that have any type of combustion or other pollution process via emission to air needs to measure their emissions to ensure they are within legal boundaries. Among the different types of pollution measurements, one of the most common is dust concentration, also known as particle concentration. An important factor in dust concentration measurements is to ensure that the concentration of the measured dust is representative to the dust concentration in the emissions. This is measured in isokinetic deviation, defined as (vn 􀀀 vd)=vd, where vn is the velocity in the entry nozzle and vd the velocity in the duct. Methods of dust concentration measurements used today are dependent on manual tuning and sensor readings, and the isokinetic deviation is calculated after a test. The focus of this project was therefore to investigate how the process of dust concentration measurements using standard reference methods could be automated in the way that isokinetic sampling is controlled and regulated by an automated control system in real time. Pressures, temperatures and sampled gas volume were quantized. A PIDcontroller was designed, implemented and tested. The PID-controller took the differential pressure between the inside of the entry nozzle and the duct, called zero pressure, as input. The system was tested in a laboratory environment by letting a radial fan create a flow, and thus create a zero pressure of -60 Pa, meaning that the pressure in the duct was 60 Pa greater than the pressure inside the entry nozzle. The PID-controller was then enabled and ran for five minutes. The result showed that the PID-controller managed to control the system to the reference point in less than 50 seconds for entry nozzles of diameters 6 mm, 8 mm, 10 mm and 12 mm. The results of the isokinetic deviations were -12 %, -5 %, -6 % and -4 % for entry nozzles with diameters 6 mm, 8 mm, 10 mm and 12 mm respectively. This is higher than the accepted values according to the European standard, which allows deviations in the interval -5%to 15%. However, these tests ran for relatively short time periods and started with large deviations which made it difficult to reach an isokinetic deviaiton in the accepted interval. Possible improvements could be to include the real time isokinetic deviation in the PID-controller, this would make it possible to change the reference value of the zero pressure in real time and guarantee isokinetic deviations in the accepted interval, even in extraordinary situations.
EU-regler ställer krav på anläggningar att kontrollera och begränsa sina utsläpp av stoft enligt EU standard 13284-1:2017. Vid en stoftmätning måste det tas hänsyn till många parametrar, där en av de viktigaste parametrarna är att provtagningen ska utföras isokinetiskt. Isokinetisk provtagning innebär att hastigheten i kanalen (skorstenen) är samma som i sonden där provgasen sugs ut. Dagens metoder för stoftmätning förlitar sig på manuella inställningar och den isokinetiska avvikelsen beräknas efter ett test. Det resulterade i frågeställnigen hur en automatiserad metod för bestämning av masskoncentration av stoft kan utformas så att den isokinetiska avvikelsen beräknas i realtid. Tryck, temperatur och gasvolym kvantiserades från analoga sensorer och kommunicerades till en mikrokontroller med det seriella protokollet I2C. En PID-reglator designades, implementerades och testades. PID-regulatorn tog tryckskillnaden mellan kanal och sond som insignal. Utsignalen från PID-regulatorn var en spänning som via en motordriven ventil kontrollerade inflödet i munstycket. Systemet testades i laborativ miljö genom att låta en fläkt skapa ett flöde tills den uppmätta tryckskillnaden mellan sond och kanal var -60 Pa. Därefter aktiverades PID-regulatorn och testet pågick sedan i fem minuter. Testet utfördes för munstycken med diameterna 6 mm, 8 mm, 10 mm och 12 mm. Resultatet visade att PID-regulatorn styrde systemet till referenspunkten på mindre än 50 sekunder för samtliga diametrar på munstyckena. De isokinetiska avvikelserna (skillnaden i hastighet mellan munstycke och kanal) beräknades till -12 %, -5 %, -6 % och -4 % för munstyckena 6 mm, 8 mm, 10 mm och 12 mm. I två av fallen var det högre än det accepterade värdet enligt EU standarden som tillåter avvikelser inom intervallet -5 % till 15 %. Det kan förklaras av att testen utfördes under en relativ kort tidsperiod och startades med stora avvikelser. Regulatorn skulle dock kunna förbättras genom att använda testets aktuella isokinetiska avvikelse och med den informationen bestämma systemets referenspunkt. Det skulle göra det möjligt att kompensera för tidigare avvikelser och på det sättet uppnå isokinetiska avvikelser inom tillåtet intervall även för extremfall.
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33

Ravetta, Patricio A. "LORE Approach for Phased Array Measurements and Noise Control of Landing Gears." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/29975.

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A novel concept in noise control devices for landing gears is presented. These devices consist of elastic membranes creating a fairing around the major noise sources. The purpose of these devices is to reduce wake interactions and to hide components from the flow, thus, reducing the noise emission. The design of these fairings was focused on the major noise sources identified in a 777 main landing gear. To find the major noise sources, an extensive noise source identification process was performed using phased arrays. To this end, phased array technologies were developed and a 26%-scale 777 main landing gear model was tested at the Virginia Tech Stability Wind Tunnel. Since phased array technologies present some issues leading to misinterpretation of results and inaccuracy in determining actual levels, a new approach to the deconvolution of acoustic sources has been developed. The goal of this post-processing is to "simplify" the beamforming output by suppressing the sidelobes and reducing the sources mainlobe to a small number of points that accurately identify the noise sources position and their actual levels. To this end, the beamforming output is modeled as a superposition of "complex" point spread functions and a nonlinear system of equations is posted. Such system is solved using a new 2-step procedure. In the first step an approximated linear problem is solved, while in the second step an optimization is performed over the nonzero values obtained in the previous step. The solution to this system of equations renders the sources position and amplitude. The technique is called: noise source Localization and Optimization of Array Results (LORE). Numerical simulations as well as sample experimental results are shown for the proposed post-processing.
Ph. D.
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34

Johnsson, Roger. "Crankshaft speed measurements and analysis for control and diagnostics of diesel engines." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18687.

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The increasing demands from governments on the engine manufactures to lower the fuel consumption, lower the exhaust emissions and to reduce the noise have lead to an intensive research in the combustion process. Measurement of the combustion process inside the cylinder is only suitable in laboratory environment due to a number of limitations; the pressure transducer needed to measure the pressure is expensive, difficult to mount in the cylinder and has a limited lifetime that is much shorter than the engine's lifetime. Demands of on-board diagnostics where the combustion process is continuously monitored, on production vehicles have created a need for a method to indirectly measure the combustion process. The two main indirect methods are vibration measurement based reconstruction and crankshaft angular speed measurement reconstruction. The combustion process give rise to vibrations in the engine body that in the former method is measured with an accelerometer and the pressure can be reconstructed by using inverted transfer functions. The idea behind the latter method, the crankshaft angular speed reconstruction method, is that when one cylinder fires the produced torque is higher than the load torque and the crankshaft accelerates. As next cylinder goes into compression the total load torque increases and the crankshaft speed will decrease. This is repeated when the next cylinder fires and the produced crankshaft speed fluctuations will then contain information about the combustion and compression that caused it. In this thesis an indirect method to predict the maximum cylinder pressure is developed based on the crankshaft speed fluctuations combined with neural networks. The speed fluctuations were measured on a 6-cylinder inline diesel engine at 9 speed-load-combinations. A two layer (one hidden and one output layer) feedforward neural network was trained with the backpropagation algorithm. The prediction accuracy for pmax was found to be better than ±5 % at 95%-confidence interval for the validation set. Another important parameter for the engine control and for optimising the fuel efficiency at the same time as the exhaust emissions are kept to a minimum, is the position of the pistons most upper position, TDC (top dead centre). The TDC position is normally measured mechanically with means that need access to the cylinders (the cylinder head has to be removed). This method is time consuming and therefore expensive and because of that not used on production engines. Several indirect methods to measure the TDC- positions have been suggested. Either based on measured cylinder pressures, that again need a pressure transducer mounted in the cylinder, or on the crankshaft speed fluctuations. An indirect method based on the speed fluctuations, that are measured when the starter motor rotates the engine with turned off ignition, is developed. From the measured crankshaft speed fluctuations the TDC-positions can be determined either by curve fitting or with neural networks. The TDC position determined by curve fitting has a bias error, due to the out-of-phase acceleration component in the crankshaft that are induced by the starter motor, but also caused by heat exchange between the compressed gas and the cylinder walls and gas. The results from the neural network were found to be better and the TDC-position for all 6 cylinders was determined within ±0.1 degree crank angle at 95%-confidence interval.

Godkänd; 2001; 20070110 (biem)

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35

Ferrar, Anthony Maurice. "Measurements of Flow in Boundary Layer Ingesting Serpentine Inlets." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/36408.

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Highly integrated airframe-propulsion systems featuring ingestion of the airframe boundary layer oer reduced noise, emissions, and fuel consumption. Embedded engine systems are envisioned which require boundary layer ingesting (BLI) serpentine inlets to provide the needed air ow to the engine. These inlets produce distorted ow proles that can cause aeromechanical, stability, and performance changes in embedded engines. Proper design of embedded engine systems requires understanding of the underlying uid dynamics that occur within serpentine inlets. A serpentine inlet was tested in a specially designed wind tunnel that simulated boundary layer ingestion in a full-scale realistic environment. The measured total pressure proles at the inlet and exit planes of the duct, and the static pressure distributions along the walls provided useful data related to the ow in BLI serpentine inlet systems. A bleed ow control system was tested that utilized no more than 2% of the total inlet ow. Two bleed slots were employed, one near the rst bend of the S-duct and one near second. The bleed system successfully reduced inlet distortions by as much as 30%, implying improvements in stall margin and engine performance. Analysis of the wake shape entering the S-duct showed that the airframe and inlet duct are both important components of a wake-ingesting inlet/diusion system. Shape eects and static pressure distributions determined ow transport within the serpentine inlet. Flow separation within the S-duct increased distortion at the engine inlet plane. Discussion of airframe/inlet/engine compatibility demonstrates that embedded engine systems require multi-disciplinary collaborative design eorts. An included fundamental analysis provides performance estimates and design guidelines. The ideal airframe performance improvement associated with wake-ingestion is estimated.
Master of Science
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36

Olsson, Mattias. "Aiding Navigation for Groups of Aircraft with Bearing and Distance Measurements." Thesis, Linköpings universitet, Reglerteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-151887.

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This thesis extends previous work on navigational aidingof groups of aircraft, primarily intended for the fighter SAAB JAS 39 Gripen,as long as an aircraft gets GPS signals, it is easy to estimate position, but theGPS is relatively easy to jam, rendering alternative methods of positioning necessary.To use internal sensors measuring accelerations and angular velocities is agood replacement on short terms, but gives a drift in positioning over longer timeperiods. To resolve these issues, we review different possibilities to improve navigation performance bycombining measurement data from different aircraft using a consensus filter.We show that the performance canbe improved by using measurements of distance and angles to other aircraft withinthe group in a distributed filter.The filter is implemented in Matlab and evaluated in different scenarios, and this Extended Kalman-Consensus Filter (EKCF) is compared to a previously proposed solution using an Extended Kalman Filter (EKF).
Det här examensarbetet vidareutvecklar en befintlig algorithm för navigeringsstöttningav grupper av flygplan, främst inriktat på SAAB JAS 39 Gripen. Genomatt kombinera mätdata från olika flygplan kommer vi gå igenom hur man kanförbättra prestanda genom applicering av consensusfilter. Så länge ett plan harGPS-signal är positionering enkelt. Dock är den relativt lätt att störa ut, vilketgör alternativa lösningar för positionering nödvändiga. Att använda interna sensorersom mäter accelerationer och vinkelhastigheter fungerar utmärkt på kortsikt, men ger en drift över en längre tidsperiod.För att lösa de här problemen utvärderar vi olika möjligheter att förbättra navigationsprestandangenom att kombinera mätdata från olika flygplan med hjälpav ett consensusfilter. Vi visar att prestandan kan förbättras genom att användadistans- och vinkelmätningar inom gruppen med distribuerade filter. Filtret ärimplementerat i Matlab med olika scenarier och jämför Extended Kalman-ConsensusFilter (EKCF) med den föregående lösningen med ett Extended Kalman Filter (EKF).
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37

Wessling, Andreas. "Radar Target Modelling Based on RCS Measurements." Thesis, Linköping University, Department of Electrical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1183.

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When simulating target seekers, there is a great need for computationally efficient, target models. This report considers a study of radar target modelling based on Inverse Synthetic Aperture Radar (ISAR) measurements of generic aircraft. The results underlie future modelling of full-size air targets.

A method is developed for two-dimensional modelling of aspect-dependent target scattering. The approach taken is to generate point-scatterer models of two targets, where each point scatterer is defined according to its position and radar cross section (RCS), estimated from ISAR images. The scattered energy contributions from all point scatterers are summed to simulate a radar return signal. To validate the models, the modelled radar target centre is compared to the true radar target centre, which is determined from ISAR images.

The method is presented to be promising for modelling air targets with large, persistent radar cross section.

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38

Baldwin, Thomas L. "Real-time phasor measurements for improved monitoring and control of power system stability." Diss., This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06062008-170758/.

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39

Ferrante, Francesco. "On quantization and sporadic measurements in control systems : stability, stabilization, and observer design." Thesis, Toulouse, ISAE, 2015. http://www.theses.fr/2015ESAE0020/document.

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Dans cette thèse, nous aborderons deux aspects fondamentaux qui se posent dans les systèmes de commande modernes du fait de l'interaction entre des processus en temps continu et des dispositifs numériques: la synthèse de lois de commande en présence de quantificateurs et l'estimation d'état en présence de mesures sporadiques. Une des caractéristiques principales de cette thèse consiste également à proposer des méthodes constructives pour résoudre les problèmes envisagés. Plus précisément, pour répondre à cette exigence, nous allons nous tourner vers une approche basée sur les inégalités matricielles linéaires (LMI). Dans la première partie de la thèse, nous proposons un ensemble d'outils constructifs basés sur une approche LMI, pour l'analyse et la conception de systèmes de commande quantifiés impliquant des modèles et des correcteurs linéaires. L'approche est basée sur l'utilisation des inclusions différentielles qui permet de modéliser finement le comportement de la boucle fermée et ainsi d'obtenir des résultats intéressants. Dans la seconde partie de la thèse, inspirés par certains schémas d'observation classiques présentés dans la littérature, nous proposons deux observateurs pour l'estimation de l'état d'un système linéaire en présence de mesures sporadiques, c'est-à-dire prenant en compte la nature discrète des mesures disponibles. De plus, en se basant sur une des deux solutions présentées, une architecture de commande basée observateur est proposée afin de stabiliser asymptotiquement un système linéaire en présence à la fois de mesures sporadiques et d'un accès intermittent à l'entrée de commande du système
In this dissertation, two fundamental aspects arising in modern engineered control systems will be addressed:On the one hand, the presence of quantization in standard control loops. On the other hand, the state estimation in the presence of sporadic available measurements. These two aspects are addressed in two different parts. One of the main feature of this thesis consists of striving to derive computer-aided tools for the solution to the considered problems. Specifically, to meet this requirement, we revolve on a linear matrix inequalities (LMIs) approach. In the first part, we propose a set of LMI-based constructive Lyapunov-based tools for the analysis and the design of quantized control systems involving linear plants and linear controllers. The entire treatment revolves on the use of differential inclusions as modeling tools, and on stabilization of compact sets as a stability notion. In the second part of the thesis, inspired by some of the classical observation schemes presented in the literature of sampled-data observers, we propose two observers to exponentially estimate the state of a linear system in the presence of sporadic measurements. In addition, building upon one of the two observers, an observer-based controller architecture is proposed to asymptotically stabilize a linear plant in the presence of sporadic measurements and intermittent input access
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40

Magalhães, Ana. "Thermo-electric temperature measurements in friction stir welding : Towards feedback control of temperature." Licentiate thesis, Högskolan Väst, Avdelningen för produktionssystem (PS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-9982.

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Friction Stir Welding has seen a fast uptake in many industry segments. Mechanical properties superior to fusion welding, the ability to weld "unweldable" aluminium alloys and low distortion are often described as the main reasons for the fast industrial implementation of FSW. Most existing applications consist of long straight welding joints. Applications with complex weld geometries, however, are rarely produced by FSW. These geometries can induce thermal variations during the welding process, thus making it challenging to maintain a consistent weld quality. In-process adaptation of weld parameters to respond to geometrical variations and other environmental variants allow new design opportunities for FSW. Weld quality has been shown to be reliant on the welding temperature. However, the optimal methodology to control the temperature is still under development.The research work presented in this thesis focuses on some steps to take in order to reach the improvement of the FSW temperature controller, thus reach a better and consistent weld quality. In the present work different temperature methods were evaluated. Temperature measurements acquired by the tool-workpiece thermocouple (TWT) method were accurate and fast, and thereby enhanced suitable for the controller. Different environmental conditions influencing the material heat dissipation were imposed in order to verify the controller effect on the joint quality. In comparison with no controlled weld, the use of the controller enabled a fast optimization of welding parameters for the different conditions, leading to an improvement of the mechanical properties of the joint.For short weld lengths, such as stitch welds, the initial plunge and dwell stages occupy a large part of the total process time. In this work temperature control was applied during these stages. This approach makes the plunge and dwell stages more robust by preventing local material overheating, which could lead to a tool meltdown. The TWT method was demonstrated to allow a good process control during plunging and continuous welding. The approach proposed for control offers weld quality consistency and improvement. Also, it allows a reduction of the time required for the development of optimal parameters, providing a fast adaptation to disturbances during welding and, by decreasing the plunge time, provides a significant decrease on the process time for short welds.
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41

Wang, Joshua Kevin. "Identification, Analysis, and Control of Power System Events Using Wide-Area Frequency Measurements." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26250.

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The power system has long been operated in a shroud of introspection. Only recently have dynamic, wide-area time synchronized grid measurements brought to light the complex relationships between large machines thousands of miles apart. These measurements are invaluable to understanding the health of the system in real time, for disturbances to the balance between generation and load are manifest in the propagation of electromechanical waves throughout the grid. The global perspective of wide-area measurements provides a platform from which the destructive effects of these disturbances can be avoided. Virginia Tech's distributed network of low voltage frequency monitors, FNET, is able to track these waves as they travel throughout the North American interconnected grids. In contrast to other wide-area measurement systems, the ability to easily measure frequency throughout the grid provides a way to identify, locate, and analyze disturbances with high dynamic accuracy. The unique statistical properties of wide-area measurements require robust tools in order to accurately understand the nature of these events. Expert systems and data conditioning can then be used to quantify the magnitude and location of these disturbances without requiring any knowledge of the system state or topology. Adaptive application of these robust methods form the basis for real-time situational awareness and control. While automated control of the power system rarely utilize wide-area measurements, global insight into grid behavior can only improve disturbance rejection.
Ph. D.
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42

Palizban, Atefeh. "Wide-area monitoring and control utilizing PMU measurements for a system protection scheme." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/52888.

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The ever increasing complexity of the electrical grid has made it difficult to predict and anticipate contingencies. This is mainly due to the advent of deregulated electricity markets, aging transmission infrastructure and the growing penetration of renewable resources. The wave of blackouts in recent years has made utilities much more aware of the need for power system wide monitoring and control. One of the fundamental requirements to achieve that goal is to have common measurement reference. A few technology enablers have emerged which have led to development of a new kind of measurement paradigm; Phasor Measurement Units, or PMUs. PMUs bear high potential for wide-area system monitoring and control as well for conducting advanced engineering analysis. PMUs can provide time-synchronized high-resolution estimates of voltage and currents (both phase amplitude and angle) as well as frequency and rate of change of frequency. Such measurements, alternatively called synchrophasors, can provide visibility of a power system distributed over a wide geographical area and can be utilized in a multitude of applications including real-time monitoring, advanced power system protection, and advanced control schemes. In this thesis, a new special protection scheme (SPS) is proposed based on synchronized measurements provided by PMUs. An existing remedial action scheme (RAS) protecting for contingencies impacting the tie-line interconnecting the Alcan system to B.C. Hydro, using conventional relays is studied, and a new scheme based on time-synchronized, and high-resolution voltage angle measurements from PMU’s in a Wide-are monitoring system (WAMs) is proposed . In this new scheme, the angles of the buses at large power plants in both systems are examined and used to calculate various criteria based on region center of angle and the kinetic energy function to implement RAS. The results of a number of time domain simulations demonstrate that the proposed scheme can lead to faster operation of the SPS and decreased amount of generation and load shedding in the Alcan system. The achieved speed and efficiency of the proposed scheme in comparison to the existing installed scheme further highlight the opportunity in utilizing PMU measurements in online applications for power system protection and monitoring.
Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
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43

Kim, Sangho. "Observation and measurements of flow structures in the stagnation region of a wing-body junction." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-08222008-063435/.

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44

Erdem, Erinc. "Active flow control studies at Mach 5 : measurement and computation." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/active-flow-control-studies-at-mach-5-measurement-and-computation(73c02044-d17c-418d-821e-9e756b7cabbf).html.

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The difficulties regarding the control of high velocity flying vehicles in supersonic/hypersonic flight regime are still prevailing. Whether it is mixing enhancement,side force generation or aerodynamic steering, wall cooling or any otherfavourable method to control the flow, the resultant effects of different flow controltechniques on the associated flowfield demands careful experimental and numericalinvestigations. Traditional aerodynamic control surfaces are subjected tosevere flight conditions and loadings in different flight regimes resulting in impairedthe control effectiveness. Active flow control methods serve strong alternativeto achieve separation postponement, transition control, lift enhancement,mixing enhancement, drag reduction, turbulence modification and/or noise suppression,etc. This thesis deals with two main active flow control techniques;transverse jets at Mach 5 cross flow and energy deposition using arc discharge atMach 5 flow. The influence of roughness on the control effectiveness of transversejet interactions is also examined. The first objective of this thesis is to investigate experimentally the flowphysics of the sonic transverse jets at Mach 5 laminar cross flow both in timeaveraged and time resolved manner to provide reliable experimental data andbetter understanding at high Mach numbers. The parameters such as momentumflux ratio, incoming Reynolds number, type of the gas and the surface roughnessare studied. The size and structures of the upstream and downstream separationregions and jet penetration characteristics together with jet shear layer behaviourare examined. Moreover CFD simulations are conducted on a two dimensionalcase of Spaid and Zukoski and the numerical solver/procedure is validated. Thena three dimensional experimental case is simulated to provide greater understandingon the flow physics as well as to cross check measurements. As the main finding; jet interaction flow field can not be oversimplified andrepresented with only one parameter that is momentum flux ratio, J, as suggested by the literature; the incoming Reynolds number, type of injectant and roughnessare clearly affecting the interaction resulting in advantages or drawbacks for flowcontrol point of view. The second objective of this thesis is to investigate experimentally the dynamicsbetween the localised energy spot and the blunt body shock for dragreduction at Mach 5 flow. The localised energy spot is created firstly via steadyelectric arc struck between two electrodes using a small amount of energy andsecondly via pulsed laser focusing with a significant amount of energy. In caseof electric discharge, the effects of discharge are evaluated in comparison to nodischarge case with the electrodes. The unsteady wake/compression structuresare examined between the steadily deposited energy spot and the modified bowshock wave. And for the laser focussing unsteady interaction that is happeningin a short duration of time is investigated. The effect of the truncation, the distancebetween the electrodes and the model as well as the type and amount ofthe energy input on this phenomenon are examined. Moreover CFD simulationsare conducted on the baseline cases to cross check measurements together withtheoretical estimates. As the main finding; the effectiveness of the arc discharge is increasing withincreased truncation or the frontal area and when the arc to nose distance isthe shortest. However an important thing to note is that energy deposition atshorter distances might result higher stagnation point heating rates which aredetrimental. The test campaign clearly renders that the use of small amount ofonboard energy to create a local focused thermal spot in front of a vehicle is anefficient way of reducing drag.
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Frangakis, Stephanie. "Material parameter identification of acoustic polymeric foams via theoretical modeling and experimental measurements." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.41 Mb., 46 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1430780.

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46

Mokhtarian, Farzad. "Fluid dynamics of airfoils with moving surface boundary-layer control." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/29026.

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The concept of moving surface boundary-layer control, as applied to the Joukowsky and NACA airfoils, is investigated through a planned experimental program complemented by theoretical and flow visualization studies. The moving surface was provided by one or two rotating cylinders located at the leading edge, the trailing edge, or the top surface of the airfoil. Three carefully designed two-dimensional models, which provided a wide range of single and twin cylinder configurations, were tested at a subcritical Reynolds number (Re = 4.62 x 10⁴ or Re — 2.31 x 10⁵) in a laminar-flow tunnel over a range of angles of attack and cylinder rotational speeds. The test results suggest that the concept is indeed quite promising and can provide a substantial increase in lift and a delay in stall. The leading-edge rotating cylinder effectively extends the lift curve without substantially affecting its slope. When used in conjunction with a second cylinder on the upper surface, further improvements in the maximum lift and stall angle are possible. The maximum coefficient of lift realized was around 2.22, approximately 2.6 times that of the base airfoil. The maximum delay in stall was to around 45°. In general, the performance improves with an increase in the ratio of cylinder surface speed (Uc) to the free stream speed (U). However, the additional benefit derived progressively diminishes with an increase in Uc/U and becomes virtually negligible for Uc/U > 5. There appears to be an optimum location for the leading-edge-cylinder. Tests with the cylinder at the upper side of the leading edge gave quite promising results. Although the CLmax obtained was a little lower than the two-cylinder configuration (1.95 against 2.22), it offers a major advantage in terms of mechanical simplicity. Performance of the leading-edge-cylinder also depends on its geometry. A scooped configuration appears to improve performance at lower values of Uc/U (Uc/U ≤ 1). However, at higher rates of rotation the free stream is insensitive to the cylinder geometry and there is no particular advantage in using the scooped geometry. A rotating trailing-edge-cylinder affects the airfoil characteristics in a fundamentally different manner. In contrast to the leading-edge-cylinder, it acts as a flap by shifting the CL vs. α plots to the left thus increasing the lift coefficient at smaller angles of attack before stall. For example, at α = 4°, it changed the lift coefficient from 0.35 to 1.5, an increase of 330%. Thus in conjunction with the leading-edge- cylinder, it can provide significant improvements in lift over the entire range of small to moderately high angles of incidence (α ≤ 18°). On the theoretical side, to start with, the simple conformal transformation approach is used to obtain a closed form potential-flow solution for the leading-edge-cylinder configuration. Though highly approximate, the solution does predict correct trends and can be used at a relatively small angle of attack. This is followed by an extensive numerical study of the problem using: • the surface singularity approach including wall confinement and separated flow effects; • a finite-difference boundary-layer scheme to account for viscous corrections; and • an iteration procedure to construct an equivalent airfoil, in accordance with the local displacement thickness of the boundary layer, and to arrive at an estimate for the pressure distribution. Effect of the cylinder is considered either through the concept of slip velocity or a pair of counter-rotating vortices located below the leading edge. This significantly improves the correlation. However, discrepancies between experimental and numerical results do remain. Although the numerical model generally predicts CLmax with a reasonable accuracy, the stall estimate is often off because of an error in the slope of the lift curve. This is partly attributed to the spanwise flow at the model during the wind tunnel tests due to gaps in the tunnel floor and ceiling required for the connections to the externally located model support and cylinder drive motor. However, the main reason is the complex character of the unsteady flow with separation and reattachment, resulting in a bubble, which the present numerical procedure does not model adequately. It is expected that better modelling of the cylinder rotation with the slip velocity depending on a dissipation function, rotation, and angle of attack should considerably improve the situation. Finally, a flow visualization study substantiates, rather spectacularly, effectiveness of the moving surface boundary-layer control and qualitatively confirms complex character of the flow as predicted by the experimental data.
Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
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47

Kusekwa, Mashauri A. D. "Real-time state estimation of a distributed electrical power system under conditions of deregulation." Thesis, Cape Peninsula University of Technology, 2010. http://hdl.handle.net/20.500.11838/2186.

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Thesis (DTech (Electrical Engineering))--Cape Peninsula University of Technology, 2010.
Static state estimation is a mathematical procedure in which physical measurements from sub-stations and physical model are combined in an optimal way. That is, the measurements obtained from the sub-stations are used with the physical model and the states of the power system are selected or calculated such that the states match the measurements in some best way. The states of a power system are the bus voltage magnitude and voltage angle of each bus of the system. Static state estimation is an increasingly common part of electrical power utility energy management systems (EMS). It plays a critical part in a day-to-day operation of a power system utility. The system measurements obtained from static estimation are used for realtime operations like optimal power flow calculations and contingency analysis. Proper system operations with regards to avoidance of insecure conditions includes situational awareness, therefore, the static estimator plays an important role in power system security. A further motivation: in increasingly electrical power deregulation, more economic operations mean savings for customers and electrical power provider alike. Economic benefit might be realized if system operators have a more accurate situational awareness of the system through improved power system state estimator. The objective of the study was to develop method, algorithm and MATLAB program for solution of power system state estimation using parallel processing techniques. In achieving the objective, the study has concentrated on development of an approximate Tanzanian power system network model comprising of 30 buses and used as a case study; decomposing the bus admittance matrix of the model into 3 interconnected sub-systems; development of mathematical model for real and reactive power injections, real and reactive power flows in the transmission lines and tie-lines connecting the sub-systems; development of measurement data model for voltage magnitude, real and reactive power injections, real and reactive power flows; formulating of a constrained weighted least absolute value state estimation problem; development of decomposition-coordination method and algorithm; and formulating algorithm and MATLAB program for solving the constrained state estimation problem using parallel processing technique.
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48

James, Michael Mark. "Fundamental Studies of the Herschel-Quinke Tube Concept with Mode Measurements." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/35862.

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A fundamental study of the Herschel-Quincke (HQ) tube concept for the reduction of noise in circular ducts is presented here. Recent testing of the Herschel-Quincke tube concept on the Pratt-Whitney JT15D and AlliedSignal TFE731-60 engines showed the potential for the practical application of this approach. A model of the HQ-system has been developed to aid in the design of the system tested. The model has revealed new noise control mechanisms associated to the implementation of multiple HQ-waveguides in a duct in the presence of higher order modes. However, the practical nature of these engine facilities results in limitations with regard to the fundamental research knowledge that could be gained from testing in a more controlled laboratory environment. A series of experiments was conducted at the NASA Langley Research Center 0.30 m ducted fan test facility where detailed modal measurements were performed. The main goals of this research endeavor were to evaluate the accuracy of the previously developed theoretical model and provide insight into the noise control mechanisms. Experiments were performed with different disturbance mode structures, number of HQ tubes and arrays, and axial positions. The modes in the duct were generated with an array of acoustic drivers (no flow case) and measured with logarithmically spaced circumferential and helical microphone arrays located on the duct wall. The modal amplitudes of the incident, transmitted, and reflected modes in the duct were determined from the microphone measurements. This allowed for the comparison of analytical and experimental modal amplitudes, modal powers, total power, and reductions. The results of this study provide insight into the three noise control mechanisms associated with this approach: reflection, circumferential scattering, and radial scattering. Comparison with the experimental results shows that the model accurately predicts the sound power attenuation except near the cut-off frequency of the modes where it tends to overestimate the attenuation. The effect of the number of tubes in the array and its axial position was also evaluated. Overall, the results of this study validate the general modeling approach for the HQ tube concept.
Master of Science
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49

Andersson, Hugo, Viktor Mattsson, and Aleksandar Senek. "Implementation of PID control using Arduino microcontrollers for glucose measurements and micro incubator applications." Thesis, Uppsala universitet, Fasta tillståndets elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-255445.

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The task is to build a low-cost thermostat and design necessary elements to perform a study on water mixed glucose-impedance at different temperatures and cell growth in a temperature-controlled incubator housing a magnetic field of up to 3 mT. The incubator was designed in solidworks and made to fit petri dishes of two relevant sizes and necessary wiring. The coils designed to extend across the large of the incubator with six turns and a 4A current to yield a sixth of the required magnetic field, as field strength increases linearly with current and turns increasing either of these is advised, and a large enough homogenous field was observed to create a suitable environment for the study. A thermistor, temperature sensitive resistance, was used to get reading and a modified wheatstone bridge was used with a multiplying op-amp to stabilize and improve accuracy of readings. Using an arduino microprocessor utilizing a PID library to calculate the power needed from thermistor readings of ambient temperature and an H-bridge controller by PWM from the Arduino a thermostat capable of driving a peltier-cell was produced capable of raising, lowering and maintaining predefined temperatures.
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50

Ng, Jen Min. "An evaluation of factors that affect glycaemic control and its measurements in diabetes mellitus." Thesis, University of Hull, 2011. http://hydra.hull.ac.uk/resources/hull:4245.

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Diabetes mellitus (DM) is a complex and challenging disorder for the health care provider. Delayed detection and poor glycaemic control are both associated with a significant increase in the risk of patient morbidity and mortality. With almost 1 in 25 people in the general population suffering from DM, it is crucial that this condition is managed and treated appropriately. This thesis critically evaluates several factors that exert an influence on glycaemic control and glucose assessment in DM today. A significant proportion of the thesis discusses issues surrounding glycated haemoglobin (HbA1c) measurements in clinical practice. The thesis also examines several areas that influence glycaemic control in patients and evaluates other methods of glucose measurements including continuous glucose monitoring (CGMS), capillary glucose readings and glycated albumin. Glycaemic control in patients with diabetes can be influenced by changes in lifestyle,diet and psychological stress. The first study in this thesis summarises the effect of a flooding disaster on the glycaemic control of patients with DM. Glycaemic control in this study was measured via longitudinal HbA1c measurements over a 24 month period. This was the first study in the UK to show that severe disruption to lifestyle, environment and psychological stress caused by a flooding disaster results in the worsening of glycaemic control in patients compared to the preceding months. The effect of the flooding was most pronounced in patients on insulin treatment (HbA1c 8.6% (8.3, 8.9) affected vs. 8.2% (8.1, 8.3) unaffected, (p = 0.002)). Glycated haemoglobin (HbA1c) concentrations have been known to be unreliable and difficult to interpret when red cell physiology is abnormal. When this occurs, glycated albumin (GA) has been suggested as a better indicator to glycaemic control. This is evaluated in the next 2 studies in a group of patients with chronic kidney disease (CKD) and DM who received intravenous iron and erythropoietin stimulating agent (ESA) therapy. Both these drugs resulted in a significant fall in HbA1c levels (0.5% in iron, p
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