published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

The gas-liquid reaction between chlorodifluoromethane (R-22) and methanol, in the presence of sodium hydroxide, was investigated in an isothermal, stirred, semi-batch reactor. The objective of the study was to develop a model for the reaction and to identify the kinetic parameters. Reactor temperature was varied from 283 to 303 K, with inlet R-22 partial pressures between 40.5 and 60.8 kPa (absolute). Solutions containing sodium hydroxide concentrations of between 1.5 and 2.5 mol·dm-3 were charged into the reactor prior to each experiment. Preliminary investigations using the R-22-methanol system revealed that stainless steel was an inappropriate choice of material for the reactor as it displayed catalytic tendencies toward trimethyl orthoformate formation. Consequently, the reactor was constructed from glass and was equipped with an internal cooling coil, a single heating jacket and a temperature control unit. Liquid samples that were withdrawn from the reactor were degassed under vacuum to remove residual chlorodifluoromethane, and thereby inhibit further reaction. Spectrophotometry was used to analyze the liquid samples to determine the concentration of chloride ions in solution. The products obtained were difluorodimethyl ether (major product) and trimethyl orthoformate (by-product) as well as sodium chloride and sodium fluoride salts. Difluorodimethyl ether is a potential replacement for ozone depleting CFC refrigerants. A Box-Behnken experimental design was used to investigate the effect of reaction conditions on the product distribution. Variations in the reaction temperature, initial concentration of sodium hydroxide and inlet partial pressure of R-22 were considered. The modeling of the gas-liquid reactions was based on the -dehydrohalogenation mechanism. Since gas solubility in a liquid decreases in the presence of dissolved salts, the "salting-out" effect on mass transfer was included in the reactor model. Sechenov coefficients for sodium chloride and sodium fluoride were combined to give a salt Sechenov coefficient Ksalt . It was known from the literature that the presence of precipitated salts causes inefficient mixing and inhibits mass transfer, particularly in this system due to the relatively low salt solubilities in methanol. This mixing effect was also included in the appropriate mass transfer terms of the reactor model. The experimental data was fitted to a proposed kinetic scheme. Kinetic parameters for each of the proposed reactions, the Sechenov ‘salting out’ coefficients and the mixing parameter were obtained through the use of a non-linear, least-squares optimization algorithm. For the kinetic study, activation energies of 89.12 and 45.83 kJ·mol-1 were obtained for the difluorodimethyl ether and trimethyl orthoformate formation reactions, respectively, with a Sechenov salt coefficient of 0.712 and a mixing parameter of 22.43. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.

Health is one of the most important elements in every individual’s life. Even though there is much advancement in science, the quality of healthcare has never been up to the mark. This appears to be true especially in the field of Physiotherapy. Physiotherapy is the analysis of human joints and bodies and providing remedies for any pains or injuries that might have affected the physiology of a body. To give patients a top notch quality health analysis and treatment, either the number of doctors should increase, or there should be an alternative replacement for a doctor. Our Master Thesis is aimed at developing a prototype which can aid in providing healthcare of high standards to the millions.  Methods: Microsoft Kinect SDK 2.0 is used to develop the prototype. The study shows that Kinect can be used both as Marker-based and Marker less systems for tracking human motion. The degree angles formed from the motion of five joints namely shoulder, elbow, hip, knee and ankle were calculated. The device has infrared, depth and colour sensors in it. Depth data is used to identify the parts of the human body using pixel intensity information and the located parts are mapped onto RGB colour frame.  The image resulting from the Kinect skeleton mode was considered as the images resulting from the markerless system and used to calculate the angle of the same joints. In this project, data generated from the movement tracking algorithm for Posture Side and Deep Squat Side movements are collected and stored for further evaluation.  Results: Based on the data collected, our system automatically evaluates the quality of movement performed by the user. The system detected problems in static posture and Deep squat based on the feedback on our system by Physiotherapist.

Segundo relatório disponibilizado pela World Health Organization (WHO) (WHO, 2015), 1,3 milhões de pessoas morrem todos os anos no mundo devido à acidentes de trânsito. Veículos inteligentes se mostram como uma proeminente solução para reduzir esse drástico número. Por isso, diversos grupos de pesquisa no mundo têm concentrado esforços para o desenvolvimento de pesquisa que viabilize o desenvolvimento desse tipo de tecnologia. Diversos são os requisitos necessários para que um veículo possa circular de forma completamente autônoma. Localização, mapeamento, reconhecimento de semáforos e placas de trânsito são apenas alguns dentre tantos. Para que um veículo trafegue nas vias de forma segura, ele precisa saber onde estão os agentes que coabitam o mesmo espaço. Depois que esses agentes são detectados é necessário predizer suas movimentações de forma a reduzir os riscos de colisão. Neste projeto propôs-se a construção de um sistema que visa detectar agentes (obstáculos) e realizar o rastreamento deles para estimar suas velocidades e localizações enquanto estiverem no campo de visão do veículo autônomo, assim possibilitando realizar o cálculo da chance de colisão de cada um desses obstáculos com o veículo autônomo. O sistema utiliza unicamente a informação provida por uma câmera estereoscópica. Os pontos da cena são agrupados utilizando a informação da 24-vizinhança, disparidade e um valor que corresponde a chance de fazerem parte de um obstáculo. Após o agrupamento, cada grupo é dado como um possível obstáculo, após checar a consistência desses obstáculos por dois frames consecutivos, o grupo, agora considerado um obstáculo passa a ser rastreado utilizando filtro de Kalman (WELCH; BISHOP, 1995) e para checar a correspondência de obstáculos ao longo de toda a sequência é utilizado o algoritmo de Munkres (MUNKRES, 1957). A detecção e o rastreamento foram avaliados quantitativamente e qualitativamente utilizando dados coletados no Campus II da USP de São Carlos, bem como o conjunto de dados KITTI (GEIGER; LENZ; URTASUN, 2012). Os resultados demonstram a eficiência do algoritmo tanto na detecção dos obstáculos como no rastreamento dos mesmos. / According to a report provided by the WHO (World Health Organization) in 2015 (WHO, 2015), 1.3 million people die every year worldwide due to traffic accidents. Intelligent vehicles appear as a prominent solution to reduce this number. Many research groups in the world have been focussing efforts on the development of research in order to enable the development of such technology. There are several requirements for a vehicle be completely autonomous on the roads. Location, mapping, recognition of traffic lights and traffic signs are just a few among many. For safety the vehicle needs to detect all the other elements that are present in the same environment and to estimate their velocity in order to know where they are planning to go to avoid any kind of collision. This project proposes a system to detect obstacles and perform their tracking to estimate their speeds and locations enabling the calculation of the chance of collision of each of these obstacles with the autonomous vehicle. The system only uses the information provided by a stereoscopic camera. The points in the scene are clustered using the 24-neighborhood information, disparity and a value related to the chance of it being part of an obstacle. After the clustering, each cluster is considered a possible obstacle, when the consistence is checked in two frames the cluster becames an obstacle and starts being tracked using Kalman filter (WELCH; BISHOP, 1995), to match obstacles being tracked in the whole sequence the Munkres algorithm (MUNKRES, 1957) is used. The detection and tracking were evaluated qualitatively and quantitatively using data collected in the Campus II of USP in São Carlos and data from KITTI dataset (GEIGER; LENZ; URTASUN, 2012). The results show the algorithms efficiency in obstacle detection and tracking.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1978. / Includes bibliographical references. / by Chun-Chieh Chen. / M.S.

Leung, Man Kin. / Thesis submitted in: October 2008. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (leaves 121-126). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgement --- p.iv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Overview --- p.1 / Chapter 1.2 --- Motivation --- p.4 / Chapter 1.3 --- Contributions --- p.5 / Chapter 1.4 --- Organization of the thesis --- p.6 / Chapter 2 --- Literature review --- p.8 / Chapter 2.1 --- Introduction --- p.8 / Chapter 2.2 --- Background knowledge --- p.9 / Chapter 2.2.1 --- Pinhole camera model --- p.10 / Chapter 2.2.2 --- Kalman filter --- p.11 / Chapter 2.2.3 --- Extended Kalman filter --- p.14 / Chapter 2.2.4 --- Unscented Kalman filter --- p.15 / Chapter 2.3 --- Batch method --- p.19 / Chapter 2.3.1 --- Multiple view geometry --- p.19 / Chapter 2.3.2 --- Factorization --- p.21 / Chapter 2.3.3 --- Bundle adjustment --- p.22 / Chapter 2.4 --- Sequential method --- p.23 / Chapter 2.5 --- SLAM using cameras --- p.24 / Chapter 2.6 --- Summary --- p.26 / Chapter 3 --- Pose tracking of a stereo camera system --- p.27 / Chapter 3.1 --- Overview --- p.27 / Chapter 3.1.1 --- Related work --- p.27 / Chapter 3.1.2 --- Contribution --- p.29 / Chapter 3.2 --- Problem definition --- p.29 / Chapter 3.3 --- Algorithm --- p.31 / Chapter 3.3.1 --- Initialization --- p.33 / Chapter 3.3.2 --- Feature tracking and stereo correspondence matching --- p.33 / Chapter 3.3.3 --- Pose tracking based on two trifocal tensors --- p.35 / Chapter 3.3.4 --- Pose tracking using extended Kalman filter (Our EKF-2 approach) --- p.37 / Chapter 3.3.5 --- Pose tracking using unscented Kalman filter (Our UKF-2 approach) --- p.41 / Chapter 3.3.6 --- Pose tracking using differential evolution (Our DE-2 approach) --- p.44 / Chapter 3.4 --- Experiment --- p.49 / Chapter 3.4.1 --- Synthetic experiments --- p.49 / Chapter 3.4.2 --- Real experiments --- p.55 / Chapter 3.5 --- Summary --- p.67 / Chapter 4 --- Advance to two pairs of stereo cameras --- p.68 / Chapter 4.1 --- Overview --- p.68 / Chapter 4.1.1 --- Related work --- p.68 / Chapter 4.1.2 --- Contribution --- p.69 / Chapter 4.2 --- Problem definition --- p.70 / Chapter 4.3 --- Algorithm --- p.72 / Chapter 4.3.1 --- Initialization --- p.72 / Chapter 4.3.2 --- Feature tracking and stereo correspondence matching --- p.74 / Chapter 4.3.3 --- Pose tracking based on four trifocal tensors --- p.76 / Chapter 4.3.4 --- Pose tracking using extended Kalman filter (Our EKF-4 approach) --- p.79 / Chapter 4.3.5 --- Pose tracking using unscented Kalman filter (Our UKF-4 approach) --- p.84 / Chapter 4.4 --- Experiment --- p.87 / Chapter 4.4.1 --- Synthetic experiments --- p.87 / Chapter 4.4.2 --- Real experiments --- p.100 / Chapter 4.5 --- Summary --- p.113 / Chapter 5 --- Conclusion --- p.115 / Chapter 5.1 --- Conclusion --- p.115 / Chapter 5.2 --- Scope of Applications --- p.116 / Chapter 5.3 --- Limitations --- p.117 / Chapter 5.4 --- Difficulties --- p.118 / Chapter 5.5 --- Future work --- p.118 / Bibliography --- p.121

Charge-Coupled-Device (CCD) cameras have opened a new world in astronomy and other related sciences with their high quantum efficiency, stability, linearity, and easy handling. Nevertheless, there is still noise in raw CCD images and even more noise is added through the image calibration process. This makes it essential to know exactly how the calibration process impacts the noise level in the image. The properties and characteristics of the calibration frames were explored. This was done for bias frames, dark frames and flat-field frames at different temperatures and for different exposure times. At first, it seemed advantageous to scale down a dark frame from a high temperature to the temperature at which the image is taken. However, the different pixel populations have different doubling temperatures. Although the main population could be scaled down accurately, the hot pixel populations could not. A global doubling temperature cannot be used to scale down dark frames taken at one temperature to calibrate the image taken at another temperature. It was discovered that the dark count increased if the chip was exposed to light prior to measurements of the dark count. This increase, denoted as dark offset, is dependent on the time and intensity of the prior exposure of the chip to light. The dark offset decayes with a characteristic time constant of 50 seconds. The cause might be due to storage effects within chip. It was found that the standard procedures for image calibration did not always generate the best and fastest way to process an image with a high signal-to-noise ratio. This was shown for both master dark frames and master flat-field frames. In a real world example, possible night sessions using master frame calibration are explained. Three sessions are discussed in detail concerning the trade-offs in imaging time, memory requirements, calibration time, and noise level. An efficient method for obtaining a noise map of an image was developed, i.e., a method for determining how accurate single pixel values are, by approximating the noise in several different cases.

Body worn cameras (BWCs) are a newer piece of equipment that has been issued to police officers in efforts to increase transparency and improve relations with the community. Researchers who have just recently begun studying the effects of BWCs have observed changes in behavior of officers who wear the equipment. Some of these changes potentially have an adverse effect on citizens and the officers who wear BWCs. Lipsky's street-level bureaucracy theory was utilized to examine police officer use of discretion when conducting field activities while wearing BWCs. The research question pertained to police officers' perceptions regarding changes in behavior while being video recorded on duty. This study used generic qualitative inquiry to understand five police officers' perceptions through individual semi structured interviews complemented by the responsive interview model. Themes that emerged consisted of implementation, personal harm, privacy, and behavior modification. Notable findings under the theme of implementation included lack of initial acceptance of the equipment followed by approval of the equipment after use; and that initial training of BWCs was deemed insufficient. In the personal harm theme, participants expressed concern over functionality of BWCs and that superiors possibly would use footage for punitive reasons. Minimal privacy issues for officers were discovered; however, use of BWCs in private residences was perceived by participants as a concern for citizens. The most significant behavior modification was increased professionalism. Implications for social change include improved officer and citizen safety and the delivery of more effective police services, improving relations with the community.

Wearable video systems (WVSs) are one of the most popular and fastest growing technologies used by law enforcement today. While published WVS literature predominantly focuses on stakeholder perceptions, community interactions, assaults against officers, and use of force, there has diminutive exploration of the impact of WVSs as it related to aspects of police misconduct, especially in the Cruiser Police Department (pseudonym; CPD). The purpose of this mixed methods study was to explore and describe how the use of the use of WVSs by the CPD impact police misconduct, by tracking the changes in complaint type and disposition of a 5-year period, and to examine how CPD officers perceive the impact of the use of WVSs. Deterrence theory and phenomenology provided structure for this research study. The quantitative portion of this study consisted of an interrupted time series analysis of 419 documented complaints against CPD officers between June 2013 and June 2018. The qualitative portion consisted of 67 anonymous, online surveys completed by current CPD officers with WVS experience that were thematically analyzed. Quantitative findings included a 13% overall increase in the number of complaints, a 15% drop in citizen complaints, a 28% increase in chief-initiated complaints, and a 41% increase in sustained complaints. Qualitative findings provided insight into CPD officers' acceptance and value of WVS, along with their strong concern for WVSs implementation creating more discipline of officers. Implications for positive social change include an awareness of unintended consequences of current policies and practices and empirical awareness of trends associated with WVS, specifically regarding discipline, officer acceptance, and police-community interaction.

Wearable video systems (WVSs) are one of the most popular and fastest growing technologies used by law enforcement today. While published WVS literature predominantly focuses on stakeholder perceptions, community interactions, assaults against officers, and use of force, there has diminutive exploration of the impact of WVSs as it related to aspects of police misconduct, especially in the Cruiser Police Department (pseudonym; CPD). The purpose of this mixed methods study was to explore and describe how the use of the use of WVSs by the CPD impact police misconduct, by tracking the changes in complaint type and disposition of a 5-year period, and to examine how CPD officers perceive the impact of the use of WVSs. Deterrence theory and phenomenology provided structure for this research study. The quantitative portion of this study consisted of an interrupted time series analysis of 419 documented complaints against CPD officers between June 2013 and June 2018. The qualitative portion consisted of 67 anonymous, online surveys completed by current CPD officers with WVS experience that were thematically analyzed. Quantitative findings included a 13% overall increase in the number of complaints, a 15% drop in citizen complaints, a 28% increase in chief-initiated complaints, and a 41% increase in sustained complaints. Qualitative findings provided insight into CPD officers' acceptance and value of WVS, along with their strong concern for WVSs implementation creating more discipline of officers. Implications for positive social change include an awareness of unintended consequences of current policies and practices and empirical awareness of trends associated with WVS, specifically regarding discipline, officer acceptance, and police-community interaction.