The rapid growth in wireless communications has given rise to an increasing demand for channel capacity using limited bandwidth. Wireless channels vary over time due to fading and changing interference conditions. Typical wireless systems are designed by choosing a modulation scheme to meet worst case conditions and thus rely on power control to adapt to changing channel conditions. Adaptive modulation, however, exploits these channel variations to improve the spectral efficiency of wireless communications by intelligently changing the modulation scheme based on channel conditions. Necessarily, among the modulation schemes used are spectrally efficient modulation schemes such as quadrature amplitude modulation (QAM) techniques. QAM yields the high spectral efficiency due to its use of amplitude as well as phase modulation and therefore is an effective technique for achieving high channel capacity. The main drawbacks of QAM modulation are its reduced energy efficiency (as compared to standard QPSK) and its sensitivity to channel amplitude variations. Adaptive modulation attempts to address the first drawback by using more energy efficient schemes in low SNR conditions are reserving the use of QAM for high SNR conditions. The second drawback leads to a requirement of high quality channel estimation. Many researchers have studied pilot symbol assisted modulation for compensating the effects of fading at the receiver. A main contribution of this thesis is the investigation of different channel estimation techniques (along with the effect of pilot symbol spacing and Doppler spread) on the performance of adaptive modulation. Another important parameter affecting adaptive modulation is the signal-to-noise ratio. In order to adapt modulation efficiently, it is essential to have accurate knowledge of the channel signal-to-noise ratio. The performance of adaptive modulation depends directly on how well the channel SNR is estimated. The more accurate the estimation of the channel SNR is, the better the choice of modulation scheme becomes, and the better the ability to exploit the variations in the wireless channel is. The second main contribution of this thesis is the investigation of the impact of SNR estimation techniques on the performance and spectral efficiency of adaptive modulation. Further, we investigate the impact of various channel conditions on SNR estimation and the resulting impact on the performance of adaptive modulation. Finally, we investigate long term SNR estimation, its use in adaptive modulation and present a comparison between the two approaches / Master of Science

Yes / In order to improve the performance of the reverse osmosis (RO) desalination plant powered by photovoltaic (PV), two cooling systems were proposed in this study to cool the PV and preheating the RO feed water as well. In the cooling design (1), the cooling fluid flows in direct contact with the back surface of the PV through channels of half circular cross-sections. While in the design (2), it flows through channels of squar cross-sections fixed on the PV back surface. Two nano-fluids were also tested as cooling fluid: H2O/CuO and H2O/Al2O3, in addition to distilled water for the purpose of comparison. The effect of changing the weight concentration of the nano-fluid (0.05, 0.1, and 0.15%) on the PV performance was also investigated. The results showed that the PV integrated with the cooling design (1) achieves better performance compared to design (2) at all studied cooling fluids. The improvements in the electric efficiency of the PV integrated with design (1) reached 39.5, 34.8 and 27.3 % when CuO and Al2O3 nano-fluids and distilled water were used as cooling fluid, respectively, compared to the uncooled PV. Based on the obtained experimental results, the PV integrated with design (1) was selected to power the RO with H2O/CuO nano-fluid of weight concentration 0.15% and flow rate 0.15 kg/s being used as the coolant. The RO powered by the improved PV was tested at different salinities of brackish water when the preheating technique was implemented. The results showed that the proposed PV-RO desalination system produces 366 l/day when brackish water of salinity 3000 ppm was used.

<p dir="ltr">Unmanned Aerial Systems (UAS) have the potential to drastically change how civil infrastructure is inspected, monitored, and managed. This innovative technology can ensure the inspector’s safety, provide additional inspection information, and reduce costs. However, a challenge arose as this industry expanded: a lack of standardized guidelines or minimum performance requirements to perform these operations. With no standard tests to verify UAS’ ability to conduct inspections and unknown detection capabilities, agencies are left to rely upon consultants’ or vendors’ promotional material and claims when considering UAS deployment. The following work proposes a series of performance-based assessments and procedural documentation to establish minimum standards for using UAS in bridge inspection applications. Through this work, the following performance-based tests have been developed: (1) a controlled environment simulating bridge geometries to assess the overall capability of a UAS used for bridge inspection [evaluation chamber], (2) an assessment of UAS performance under multiple environmental temperatures [environmental temperature chamber], (3) a UAS performance assessment under varying wind speeds [wind chamber], (4) a consolidated checklist compiling Federal Aviation Administration guidelines and best practices [flight checklist], (5) a field assessment of UAS under conditions analogous to on-site bridge inspection [practical test]. For infrastructure owners, embracing these performance-based assessments will help ensure that UAS meets a minimum level of performance and allow owners to verify and distinguish between various UAS used for bridge inspection. This work also discusses positive feedback from beta testing provided by industry and infrastructure owner representatives, showcasing the effectiveness of providing an authentic assessment of UAS bridge inspection capabilities. Future work encourages the wide implementation of this assessment program and encourages owners to refrain from using untested technology in the inspection of their infrastructure.</p>

The rapid expansion of the postwar commercial aviation industry in Canada was made possible, in part, by the thousands of wartime pilots who filled the ranks of the nation’s major airlines beginning in 1944. Through mentorship of subsequent generations of peacetime aviators, wartime pilots had lasting impacts on the Canadian commercial aviation industry during their time flying for companies such as Trans Canada Airlines (TCA). Following an examination of the agreements made between the Royal Canadian Air Force and TCA between 1944 and 1945 for the transfer of pilots between the two organizations, this thesis tracks the development of the professional culture of wartime RCAF aviators through an analysis of their training and subsequent operational flying during the war. It concludes that while there were numerous benefits for commercial aviation in Canada through this process, there were, likewise, a series of negative repercussions for the safety of the Canadian aviation industry.

A handling quality investigation was performed on the swept gull-wing configuration. The swept gull-wing configuration is tailless and has a wing with a transition in the sweep and dihedral angle. An example of this type of aircraft is the Exulans. This aircraft is currently under development at the University of Pretoria. The handling quality study was focussed on pitch axis dynamics. The Exulans is a research testbed that will be used to investigate the swept gull-wing configuration and its special controls by means of full-scale flight testing. Variable wing sweep, twisting elevons and winglets will be investigated as means of control. These control devices are configured in such a way as to have minimum impact on the performance of the aircraft. The handling qualities of the swept gull-wing configuration have to be acceptable while using these different control strategies. The study was launched to investigate whether a gull-wing configuration aircraft will have satisfactory handling qualities at CG positions associated with the most favourable aerodynamic performance. There is an aerodynamic performance gain in designing an aircraft so that the CG falls on the so-called `E-point'. The E-point is the centre of pressure for an elliptical circulation distribution. An elliptical circulation distribution is associated with the highest Oswald efficiency for an aircraft. Time domain simulation techniques and frequency domain analysis techniques were used to analyse the handling qualities of the gull-wing configuration. The C-star criterion was used to analyse handling qualities with time domain simulation data as input. Comparative time domain simulations were performed between the Exulans and other aircraft to compare handling qualities. Eigenvalue analysis was used together with the thumbprint criterion to investigate inherent gull-wing airframe dynamics. The Shomber-Gertsen and Military Specification 8785 criteria were also used for the same purpose. The Neal-Smith method was used to investigate the effect of control authority on handling qualities and the effect of a pilot. The Monnich and Dalldorff criterion was used to evaluate gust handling qualities. An analysis chart by Fremaux and Vairo was used to evaluate the tumbling susceptibility of the gull-wing configuration. The pitch handling quality investigation shows sufficient promise that the swept gull-wing configuration will have acceptable handling qualities with the CG placed at positions associated with optimised aerodynamic performance. Analysis showed that the swept gull-wing configuration is potentially prone to tumbling. With low static margins, the configuration should exhibit improved handling qualities in gusty conditions when compared to existing tailless aircraft. It is recommended that a lateral handling quality study be performed before full scale flight testing commences on the Exulans. In addition, the possibility of wingtip stall must be investigated for the case of the swept gull-wing configuration. / Dissertation (MEng)--University of Pretoria, 2008. / Mechanical and Aeronautical Engineering / unrestricted

Legal and scientific imperatives necessitate the validation of a psychometric battery before using it for the purposes of personnel selection and decision- making. The aim of this investigation is to validate a selection battery, i.e. the Ability, Processing of Information and Learning (APIL) Battery and Raven's Advanced Progressive Matrices (APM), used in selecting university bridging - course students. The empirical study is informed by a literature review focussing on the legal and scientific parameters of psychometrics within selection, the conceptualisation of intelligence and its relationship to academic performance. Hypotheses are posed regarding the predictive power of the selection battery and the effect of biographical factors on academic performance. Results indicate that the APU. Battery apd Raven's APM are both valid predictors of academic performance, ·although the former appears more effective. This investigation emphasises the influence of moderating factors, i.e. factors other than cognitive ability, on academic performance. / Industrial and Organisational Psychology / M. Adm. (Industrial and Organisational Psychology)

1 online resource (vii, 138 leaves : ill.) / Following an awareness of an increased turn over of staff in the eating disorder unit as compared with other specialised units, in a psychiatric hospital in Johannesburg, South Africa, Tara Hospital, the researcher was motivated to investigate the issue. An exploratory, descriptive based research was chosen to explore and gain information about the topic and its implications. A qualitative research approach was used to gain insight into the perceptions and needs of the team working on the unit. The case study method was used. A pilot study was undertaken to test the validity of the interview schedules. The sampling category was a non- probability one. Individuals were selected from the population of staff working on the unit. Participants were selected from two groups, those who were presently working on the unit and those who had previously worked on the unit and now working in other units. Interview procedure involved personal semi-structured interviews conducted by the researcher and analysed qualitatively and a structured interview questionnaire analysed quantitatively. The researchers assumption that many staff members move from working in an eating disorders unit was confirmed and is due to the following: Staff turnover is due to constant exposure to occupational stress and burnout. Feelings of helplessness, a sense of being unappreciated and excessive exposure to conflict from the patients. In addition, staff experience minimum rewards leading to lowered job satisfaction due to the patients slow recovery rates and a poor prognosis of the illness. Staff also experience a change in their eating patterns and an increased awareness around food and food issues. Recommendations to the staff include: * Psycho-education on eating disorders. * Implementation of strategies to provide supportive care for all staff members. * Education on stress management and strategies to prevent staff burnout and lowered job satisfaction. * A multidisciplinary teamwork approach by the staff, when working in the unit. / Social Work / M. A. (Social Science in Mental Health)

This research was geared towards the investigation of management strategies (factors) that affect the performance ofMSMEs in Kenya. Many developed countries record a time in history when entrepreneurial activities led to revival of economical growth after decline. This implies MSMEs is a very vital sector especially for a developing country like Kenya. MSMEs stagnate and their performance is uncertain according to writers such as Namusonge, Management inadequacies have been suggested in several studies. The objectives of this research was to, 1. To identifY the critical management factors affecting the performance of MSMEs in Kenya; ii. To establish the process through which managerial factors affect the performance of a MSMEs in Kenya ; m. To determine the integrative effect of various management factors in the MSMES in Kenya; IV. To establish the effect of demographics and management factors on performance, v. To establish effects of external environment on internal management factors A conceptual model was formulated from the literature review showing relationships of the management strategies and the environment they operate in. These relationships became the basis for the hypotheses which were later tested. In chapter 4, a mini research (pilot study) was conducted in May 2007,whose main aim was to test the reliability and validity of the research instruments. The 36 questionnaires returned were analysed through descriptive method. Results obtained indicated the instruments were reliable and the results valid. A few corrections suggested were made. The major correction was addition of question 35 to collect financial information. The data collection was done between mid August and mid October 2007.In chapter 5, the researcher analysesd the results of the survey after receiving 180 questionnaires. Time was a constraint. In chapter 6, the hypotheses and conceptual model were analysed and the results obtained suggested that, most strategies did not affect the profitability separately but severally. The integrated effect of the management strategies and the associated factors had a higher impact on performance of the MSMES than any individual strategies. In chapter 7, the conclusions, summaries and Recommendations are given. / Business Management / D. Com. (Business Management and Policy)

Plusieurs études ont démontré que prés de deux tiers des patients subissant une chirurgie cardiaque souffrent de douleur d’intensité modérée à sévère. Ces niveaux de douleur semblent être partiellement expliqués par la présence de barrières individuelles face au soulagement de la douleur. Le savoir acquis sur les cognitions associées à la douleur ne semble pas avoir été traduit dans de nouvelles approches éducatives face à la douleur aiguë. Le but du projet doctoral était 1) de développer une intervention visant à faciliter l’autogestion de la douleur postopératoire après une chirurgie cardiaque et, 2) d’en évaluer l’acceptabilité et la faisabilité, ainsi que le potentiel d’efficacité sur le soulagement de la douleur de patients subissant une chirurgie cardiaque. Le développement de l’iintervention SOULAGE-TAVIE a inclus quatre étapes fondées sur les savoirs clinique, empirique et théorique et inspirées de plusieurs écrits méthodologiques. SOULAGE-TAVIE consiste en une session préopératoire éducative sur la gestion de la douleur post-chirurgie cardiaque d’approximativement 30 minutes sur un ordinateur, dispensée sur mesure en fonction d’un algorithme. Deux renforcements cliniques en personne sont aussi offerts en phase postopératoire. L’évaluation de l’intervention consistait en un essai clinique pilote à répartition aléatoire incluant 60 participants répartis entre le groupe expérimental (GE : SOULAGE-TAVIE) et le groupe contrôle (GC : soins usuels incluant un feuillet d’information). Les données étaient recueillies au moment de l’admission et dans les sept jours postopératoires. SOULAGE-TAVIE a été jugée comme acceptable et faisable. De plus, les participants du GE n’ont pas expérimenté une douleur de plus faible intensité mais ils ont rapporté significativement moins d’interférence de la douleur avec la toux et la respiration profonde, ont démontré moins de barrières face à la gestion de la douleur et ont consommé plus d’opiacés. Cette étude pilote procure des résultats prometteurs sur les bénéfices potentiels de cette nouvelle approche sur mesure utilisant les technologies de l’information et de la communication (TIC). L’autonomisation des personnes est cruciale et complémentaire pour soutenir le soulagement de la douleur dans le contexte actuel de soins. / Several studies have shown that many patients undergoing a cardiac surgery suffer from moderate to severe pain. These levels of pain may be explained by individual barriers toward pain relief. Knowledge acquired on pain-related cognitions has not been translated into new approaches. The aim of the doctoral project was 1) to develop an intervention to facilitate the self-management of postoperative pain after cardiac surgery and, 2) to assess its the acceptability and feasibility and to investigate its efficacy potential on pain relief in patients undergoing cardiac surgery. The development of SOULAGE-TAVIE included four steps based on clinical, empirical and theoretical knowledge and inspired by diverse methodological considerations. SOULAGE-TAVIE consists in a 30-minute computer-tailored preoperative educational session about postoperative pain management, tailored according to an algorithm. Two short reinforcements are provided in person. The evaluation of SOULAGE-TAVIE consisted in a pilot randomized controlled trial including 60 participants assigned to the experimental group (EG: SOULAGE-TAVIE) and the control group (CG: usual care including educational pamphlet). Data were collected at the time of admission and across Day 1 to 7 after surgery. The results provide preliminary support for the acceptability and feasibility of a tailored and virtual intervention. The results revealed that patients of the EG did not experience less intense pain but they reported significantly less pain interference when breathing/coughing, exhibited fewer pain-related barriers, and consumed more opioid medication. This pilot study provides promising results to support the potential benefits of this new web-tailored approach. Patient empowerment is complementary yet crucial in the current context of care and may contribute to improve pain relief.

In conjunction with the Texas Technology Immersion Pilot program (TIP), the State of Texas implemented a four-year annual evaluation called the Evaluation of the Texas Technology Immersion Pilot (eTxTiP). It focused on the technology immersion experience through one-to-one mobile technology of sixth grade students in 22 selected middle schools. Initial findings suggested academic growth, especially in math, increased rigor of student work, greater teacher collaboration, a more positive school environment, and transformation of instructional practices. This study focused on one of the original schools selected to participate in the TIP program, exploring the impact over time of one-to-one mobile technology on one group of students over an 8-year period beginning with their third grade year. The selected school’s demographic makeup reflected a large number of schools within the state, including its size, rural location and economically disadvantaged student population. Based on an interrupted time series design, state assessment data was analyzed using a piecewise growth model. The study revealed no statistically significant academic growth in reading and math performance among the participants.