Injury to the anterior cruciate ligament (ACL) may have consequences for an athlete in the form of pain, decreased activity levels and early-onset osteoarthritis. Female athletes are at increased risk of injury, perhaps because of differences in neuromuscular function. Methods of identifying risk factors and effective prevention strategies for ACL injury have traditionally involved athletes of high school age or older. However by that age, the opportune time to intervene may have passed. This thesis involves a sequence of studies which measures the neuromuscular function of younger athletes, aged 10-14 years. First, the reliability of measuring strength and power of the lower extremity on an isokinetic dynamometer was explored. Torque and power of the hip flexors and knee extensors were the only measures with acceptable reliability. Conversely, peak velocity of all the tested hip and knee movements demonstrated acceptable reliability. A high amount of variability was found with all test movements, and so alternate tests should be used if measuring an individual athlete’s ability. From the data collected within the reliability study, a sex comparison was undertaken to determine if neuromuscular power differed at this young age. It was determined that girls and boys between 10 and 14 years of age do not differ in terms of knee or hip movement velocity or power. There is evidence to suggest that sex differences exist by adulthood; further research is required to determine when the disparity becomes apparent. The final project was to determine whether strength training would improve the manner in which young female athletes land from a jump; a common ACL injury mechanism. This randomized controlled trial found no difference between the intervention group who trained their legs, and the control group who trained their arms. However those athletes with the poorest landings appeared to improve their movement pattern regardless of training regime. This thesis contributes to the literature by providing evidence for measurement protocols for young athletes, introducing neuromuscular power instead of strength into the investigation of contributing factors to injury, and by furthering the examination of strength training as an effective component of prevention programs.

This study has presented a new model for predicting software reliability based on design metrics. An introduction to the problem of software reliability is followed by a brief overview of software reliability models. A description of the models is given, including a discussion of some of the issues associated with them. The intractability of validating life-critical software is presented. Such validation is shown to require extended periods of test time that are impractical in real world situations. This problem is also inherent in fault tolerant software systems of the type currently being implemented in critical applications today. The design metrics developed at Ball State University is proposed as the basis of a new model for predicting software reliability from information available during the design phase of development. The thesis investigates the proposition that a relationship exists between the design metric D(G) and the errors that are found in the field. A study, performed on a subset of a large defense software system, discovered evidence to support the proposition. / Department of Computer Science

In recent years there has been a rapid increase in the number of wireless devices for both commercial and defense applications. Such unprecedented demand has increased device cost and complexity and also added a strain on the spectrum utilization of wireless communication systems. This thesis addresses these issues, from an antenna system perspective, by developing new techniques to dynamically optimize adaptive beamforming arrays for improved anti-jamming and reliability. Available frequency spectrum is a scarce resource, and therefor e increased interference will occur as the wireless spectrum saturates. To mitig ate unintentional interference, or intentional interference from a jamming source, antenna arrays are used to focus electromagnetic energy on a signal of interest while simultaneously minimizing radio frequency energy in directions of interfering signals. The reliability of such arrays, especially in commercial satellite and defense applications, can be addressed by hardware redundancy, but at the expense of increased volume, mass as well as component and design cost. This thesis proposes the development of new models and optimization algorithms to dynamically adapt beamforming arrays to mitigate interference and increase hardware reliability. The contributions of this research are as follows. First, analytical models are developed and experimental results show that small antenna arrays can thwart interference using dynamically applied stochastic algorithms. This type of insitu optimization, with an algorithm dynamically optimizing a beamformer to thwart interference sources with unknown positions, inside of an anechoic chamber has not been done before to our knowledge. Second, it is shown that these algorithms can recover from hardware failures and localized faults in the array. Experiments were performed with a proof-of-concept four-antenna array. This is the first hardware demonstration showing an antenna array with live hardware fault recovery that is adapted by stochastic algorithms in an anechoic chamber. We also compare multiple stochastic algorithms in performing both anti-jamming and hardware fault recovery. Third, we show that stochastic algorithms can be used to continuously track and mitigate interfering signals that continuously move in an additive white Gaussian noise wireless channel.

Determining the quality of natural language applications is one of the most important aspects of technology development. There has, however, been very little work done on establishing how well the methods and measures represent the quality of the technology and how reliable the evaluation results presented in most research are. This study presents a new stepwise evaluation reliability methodology that provides a step-by-step framework for creating predictive models of evaluation metric reliability that take into account inherent evaluation variables. These models can then be used to predict how reliable a particular evaluation will be prior to doing an evaluation, based on the variables that are present in the evaluation data. This allows evaluators to predict the reliability of the evaluation prior to doing the evaluation and adjusting the evaluation data to ensure reliable results. Furthermore, this permits researchers to compare results when the same evaluation data is not available. The new methodology is firstly applied to a well-defined technology, namely spelling checkers, with a detailed discussion of the evaluation techniques and statistical procedures required to accurately model an evaluation. The spelling checker evaluations are investigated in more detail to show how individual variables affect the evaluation results. Finally, a predictive regression model for each of the spelling checker evaluations is created and validated to verify the accuracy of its predictive capability. After performing the in-depth analysis and application of the stepwise evaluation reliability methodology on spelling checkers, the methodology is applied to two more technologies, namely part of speech tagging and named entity recognition. These validation procedures are applied across multiple languages, specifically Dutch, English, Spanish and Iberian Portuguese. Performing these additional evaluations shows that the methodology is applicable to a broader set of technologies across multiple languages. / Thesis (PhD (Linguistics and Literary Theory))--North-West University, Potchefstroom Campus, 2013.

Determining the quality of natural language applications is one of the most important aspects of technology development. There has, however, been very little work done on establishing how well the methods and measures represent the quality of the technology and how reliable the evaluation results presented in most research are. This study presents a new stepwise evaluation reliability methodology that provides a step-by-step framework for creating predictive models of evaluation metric reliability that take into account inherent evaluation variables. These models can then be used to predict how reliable a particular evaluation will be prior to doing an evaluation, based on the variables that are present in the evaluation data. This allows evaluators to predict the reliability of the evaluation prior to doing the evaluation and adjusting the evaluation data to ensure reliable results. Furthermore, this permits researchers to compare results when the same evaluation data is not available. The new methodology is firstly applied to a well-defined technology, namely spelling checkers, with a detailed discussion of the evaluation techniques and statistical procedures required to accurately model an evaluation. The spelling checker evaluations are investigated in more detail to show how individual variables affect the evaluation results. Finally, a predictive regression model for each of the spelling checker evaluations is created and validated to verify the accuracy of its predictive capability. After performing the in-depth analysis and application of the stepwise evaluation reliability methodology on spelling checkers, the methodology is applied to two more technologies, namely part of speech tagging and named entity recognition. These validation procedures are applied across multiple languages, specifically Dutch, English, Spanish and Iberian Portuguese. Performing these additional evaluations shows that the methodology is applicable to a broader set of technologies across multiple languages. / Thesis (PhD (Linguistics and Literary Theory))--North-West University, Potchefstroom Campus, 2013.

In recent decades, there has been a dramatic increase in utilizing renewable energy resources by many power utilities around the world. The tendency toward using renewable energy resources is mainly due to the environmental concerns and fuel cost escalation associated with conventional fossil generation. Among renewable resources, wind energy is a proven source for power generation that positively contributes to global, social, and economic environments. Nowadays, wind energy is a mature, abundant, and emission-free power generation technology, and a significant percentage of electrical power demand is supplied by wind. However, the intermittent nature of wind generation introduces various challenges for both the operation and planning of power systems. One of the problems of increasing the use of wind generation can be seen from the reliability assessment point of view. Indeed, there is a recognized need to study the contribution of wind generation to overall system reliability and to ensure the adequacy of generation capacity. Wind power generation is different than conventional generation (i.e., fossil-based) in that wind power is variable and non-controllable, which can affect power system reliability. Therefore, modeling wind generation in a reliability assessment calls for reliable stochastic simulation techniques that can properly handle the uncertainty and precisely reflect the variable characteristics of the wind at a particular site. The research presented in this thesis focuses on developing a reliable and appropriate model for the reliability assessment of power system generation, including wind energy sources. This thesis uses the Monte Carlo Markov Chain (MCMC) technique due to its ability to produce synthetic wind power time series data that sufficiently consider the randomness of the wind along with keeping the statistical and temporal characteristics of the measured data. Thereafter, the synthetic wind power time series based on MCMC is coupled with a probabilistic sequential methodology for conventional generation in order to assess the overall adequacy of generating systems. The study presented in this thesis is applied to two test systems, designated the Roy Billinton Test System (RBTS) and the IEEE Reliability Test System (IEEE-RTS). A wide range of reliability indices are then calculated, including loss of load expectation (LOLE), loss of energy expectation (LOEE), loss of load frequency (LOLF), energy not supplied per interruption (ENSPI), demand not supplied per interruption (DNSPI), and expected duration per interruption (EDPI). To show the effectiveness of the proposed methodology, a further study is conducted to compare the obtained reliability indices using the MCMC model and the ARMA model, which is often used in reliability studies. The methodologies and the results illustrated in this thesis aim to provide useful information to planners or developers who endeavor to assess the reliability of power generation systems that contain wind generation.

Social support has been proven to play a major role in the well-being of an individual. Unfortunately, the conceptualisation of the construct is vague and many authors disagree about the various properties and dimensions of the construct. Seen from a health-related perspective, social support can be regarded as divided into two main spectrums, the main-effect model and the stress-buffering model. The main-effect model proposes that social support has a beneficial effect, whether or not an individual is under stress, while the stress-buffering model proposes that social support buffers an individual from potentially pathological influences. The construct is furthermore conceptualised as consisting of distinct structural, functional and perceptual dimensions. The aim of the research was to develop an instrument which would incorporate all three of these dimensions and could be proven valid and statistically reliable. A cross-sectional survey design was used. An availability sample of qualified educators in the North-West Province of South Africa was used. The Social Support Survey was developed as a measuring instrument and administered along with a biographical questionnaire. Descriptive statistics and inferential statistics were used to analyse the data. Contrary to expectation, factor analysis indicated that the four factors regarding the characteristics of the support, as well as the five factors regarding the types of support, were clustered around the source of support. This might be due to the Likert-scale matrix design of the questionnaire, which required participants to answer a wide range of questions regarding the type, importance, amount, adequacy and accessibility of support. By way of conclusion, recommendations were made. / Thesis (M.Com. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2008.

The use of generator circuit breakers in power stations was investigated and evaluated. A feasibility study to determine if the additional capital cost required, when using a generator circuit breaker in a power station could be justified by the advantages it provides. The background to the study is provided through a technology and literature survey. Included in the technology review and the literature study is information on interruption mediums, the historic developments of circuit breakers and generator circuit breaker application theory. This data was used to determine the practicality of using a specific interruption medium within a generator circuit breaker application. The requirements of generator circuit breakers were determined and used to evaluate the interruption mediums in question. To ensure practical results, commonly used layouts were used to determine the effect of using a generator circuit breaker on the reliability, availability and the mean time to repair of a power station electrical distribution layout. Furthermore, the effect of the protection on the generator and generator transformer was evaluated. It was found that increased selectivity of the protection system by using a generator circuit breaker limits the extent of equipment damage in case of failure. Practical layouts were used to determine the effect on reliability. The analysis was conducted using assumed values of operational costs to determine the cost incurred through the change in reliability of the power station. By adding a generator circuit breaker, the station transformer and associated equipment is regarded as back-up or redundant equipment. This increases the reliability of the power station dramatically and limits the risk of income lost due to failures. The full evaluation included the estimation of the capital investment costs and the impact that the additional cost has on the operational requirements of a power station. The study determined that the capital cost required to use a generator circuit breaker results in no additional income for a power station. Through the increased protection, higher availability and the possible omission of power station ancillary equipment, the use of generator circuit breakers will result in more power being delivered and more income generated by a power station. The study proved that the generator circuit breaker is a critical part of a power station layout and is a necessary capital requirement to ensure the sustainability of the power station. / Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2010.

During the last decade much research has been done on consumer perceptions in the so-called pure services with scant attention being devoted to the analysis of retail services associated with the marketing of goods. However, in recent years the service quality debate received much attention and closer examination in retailing. It is, therefore, not surprising that many of m s spend substantial resources to measure service quality and manage customer satisfaction. This research was undertaken primarily to develop a conceptual model of service quality within a supermarket context. The research is supported by a detailed literature study into the marketing of services, service quality, service encounters and established service quality models. Four central questions were formulated and answered by the study. What are the dimensions used by consumers to evaluate supermarket service quality? How reliable is the proposed service quality scale? What relationship can be observed between the proposed service quality dimensions and future store patronage? What relationships can be observed between the proposed service quality dimensions and overall service quality? In order to develop and validate a measurement model for supermarket service quality, exploratory research was conducted using focus group interviews to establish aspects that could be important to consumers regarding service quality. This enabled the researcher to obtain a fairly accurate measure of consumers' perceptions of supermarket service quality. Based on the exploratory research, a forty-item scale was developed for the empirical study. The instrument was then subjected to a scale purification process through exploratory factor analysis. Non-probability sampling (judgment and convenience) was used and structured questionnaires were administered to six hundred and seven consumers from three stores of a national supermarket chain. A thirty-item scale was finally developed, which comprised three dimensions, namely reliability, atmospherics and policy. Continatory factor analysis was further undertaken in order to establish the overall model fit in terms of the three dimensions. Empirical evidence suggests, that the reliability, atmospherics and policy dimensions are all positively associated with consumers' perceptions of overall service quality. Reliability and atmospherics emerged as strong predictors of future store patronage and satisfaction. However, policy did not emerge as a strong predictor of future behavioural intentions. Empirical evidence also suggests that there is a causal ordering of service quality which influences customer satisfaction. The findings suggest that managements of supermarkets should incorporate all three underlying dimensions in order for them to access their customers’ evaluation of their service. Although it is probable that the relative importance of each dimension and variables within each dimension may vary from one retailer to another, it is important for managers to identify these components of the senice which make a contribution to service quality and customer satisfaction. The service offering must, therefore, be designed by managers to reflect these perceptions in order to allow them develop better service quality strategies. The findings in this study also suggest the need for a more extensive study so as to validate the model. However, it provides an avenue for academics and researchers to explore and contribute to the ongoing debate on the measurement of service quality and its relationship with customer satisfaction. / Thesis (Ph.D. (Marketing))--North-West University, Vaal Triangle Campus, 2004.

During the last decade much research has been done on consumer perceptions in the so-called pure services with scant attention being devoted to the analysis of retail services associated with the marketing of goods. However, in recent years the service quality debate received much attention and closer examination in retailing. It is, therefore, not surprising that many of m s spend substantial resources to measure service quality and manage customer satisfaction. This research was undertaken primarily to develop a conceptual model of service quality within a supermarket context. The research is supported by a detailed literature study into the marketing of services, service quality, service encounters and established service quality models. Four central questions were formulated and answered by the study. What are the dimensions used by consumers to evaluate supermarket service quality? How reliable is the proposed service quality scale? What relationship can be observed between the proposed service quality dimensions and future store patronage? What relationships can be observed between the proposed service quality dimensions and overall service quality? In order to develop and validate a measurement model for supermarket service quality, exploratory research was conducted using focus group interviews to establish aspects that could be important to consumers regarding service quality. This enabled the researcher to obtain a fairly accurate measure of consumers' perceptions of supermarket service quality. Based on the exploratory research, a forty-item scale was developed for the empirical study. The instrument was then subjected to a scale purification process through exploratory factor analysis. Non-probability sampling (judgment and convenience) was used and structured questionnaires were administered to six hundred and seven consumers from three stores of a national supermarket chain. A thirty-item scale was finally developed, which comprised three dimensions, namely reliability, atmospherics and policy. Continatory factor analysis was further undertaken in order to establish the overall model fit in terms of the three dimensions. Empirical evidence suggests, that the reliability, atmospherics and policy dimensions are all positively associated with consumers' perceptions of overall service quality. Reliability and atmospherics emerged as strong predictors of future store patronage and satisfaction. However, policy did not emerge as a strong predictor of future behavioural intentions. Empirical evidence also suggests that there is a causal ordering of service quality which influences customer satisfaction. The findings suggest that managements of supermarkets should incorporate all three underlying dimensions in order for them to access their customers’ evaluation of their service. Although it is probable that the relative importance of each dimension and variables within each dimension may vary from one retailer to another, it is important for managers to identify these components of the senice which make a contribution to service quality and customer satisfaction. The service offering must, therefore, be designed by managers to reflect these perceptions in order to allow them develop better service quality strategies. The findings in this study also suggest the need for a more extensive study so as to validate the model. However, it provides an avenue for academics and researchers to explore and contribute to the ongoing debate on the measurement of service quality and its relationship with customer satisfaction. / Thesis (Ph.D. (Marketing))--North-West University, Vaal Triangle Campus, 2004.