Dynamic optimisation problems are problems where the search space does not remain constant over time. Evolutionary algorithms aimed at static optimisation problems often fail to effectively optimise dynamic problems. The main reason for this is that the algorithms converge to a single optimum in the search space, and then lack the necessary diversity to locate new optima once the environment changes. Many approaches to adapting traditional evolutionary algorithms to dynamic environments are available in the literature, but differential evolution (DE) has been investigated as a base algorithm by only a few researchers. This thesis reports on adaptations of existing DE-based optimisation algorithms for dynamic environments. A novel approach, which evolves DE sub-populations based on performance in order to discover optima in an dynamic environment earlier, is proposed. It is shown that this approach reduces the average error in a wide range of benchmark instances. A second approach, which is shown to improve the location of individual optima in the search space, is combined with the first approach to form a new DE-based algorithm for dynamic optimisation problems. The algorithm is further adapted to dynamically spawn and remove sub-populations, which is shown to be an effective strategy on benchmark problems where the number of optima is unknown or fluctuates over time. Finally, approaches to self-adapting DE control parameters are incorporated into the newly created algorithms. Experimental evidence is presented to show that, apart from reducing the number of parameters to fine-tune, a benefit in terms of lower error values is found when employing self-adaptive control parameters. / Thesis (PhD)--University of Pretoria, 2012. / Computer Science / unrestricted

The health system in Abu Dhabi has undergone a series of far reaching reforms during the past six years, yet in spite of the structural transformations, public confidence in the performance of this vital sector is still skeptical at best and employee engagement is still low. The thesis was underpinned by the aim to reveal the challenges in public health system reform outside the context of western administration. This thesis is an attempt to analyse the intricate, multidimensional concept of organisational culture within the complex structure of public healthcare sector in a fast growing economy like Abu Dhabi. Managing organisational culture is increasingly viewed as an essential part of health system reform. Organisational culture in health care organisations has gained increased consideration as an important factor that affects health systems reform and influences the quality of health care. The research project aims to explore the context of health system reform in Abu Dhabi and to understand the organisational culture of the different constituents of its public healthcare sector. Using a multi-method investigation combining both qualitative and quantitative approaches using the Competing Values Framework as conceptual framework, this research aims to provide a critical assessment of organisational culture in healthcare sector in Abu Dhabi. Semi-structured interviews were conducted in the regulator, operator, and three public hospitals prior to the use of a survey instrument based on the Organisational Culture Assessment Instrument (OCAI). The data analysis revealed that the prevailing cultural model of the Abu Dhabi public sector organisations was concurrently governed by hierarchy and market cultures while the presence of clan and adhocracy models was relatively limited. Interesting variations in assessment of clan culture were found between UAE nationals and other nationality clusters. The findings also revealed a desired cultural shift manifested by a higher emphasis on clan and adhocracy cultures and a lower emphasis on hierarchy and market culture. Those results confirm the presence of two opposing or competing cultural dimensions clan/adhocracy vs. hierarchy/market. This research makes a considerable contribution to the sparse empirical studies in health system reforms and organisational culture in the Arab Gulf states, and proposes important explanations and possible solutions to the salient challenges facing the health system in Abu Dhabi.

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This master thesis deals with creating a new business subject, and focus on business plan and its usage in company practice. Theoretical introduction and the basic concepts definitions are included in the first part. Terms of business environment are also explained there. The second part is focused on the analysis of the business environment and new starting business subject. The proposals and recommendations for improving new business subject, which are based on analysis and outputs, are formulated in the final section.

Stereotypic behavior is often observed in children diagnosed with an Autism Spectrum Disorder (ASD; American Psychiatric Association, 2013). Stereotypy can inhibit skill acquisition by leading to inaccuracy on task performance and/or slower task completion (e.g., Koegel & Covert, 1972; Morrison & Rosales-Ruiz, 1997). Several studies have demonstrated that access to preferred matched stimulation leads to a reduction of vocal stereotypical behavior (e.g., Lanovaz, Rapp, & Ferguson, 2012). However, it is paramount that treatments not only be effective in decreasing the problem behavior, but do so without further inhibiting academic progress. The current study evaluated the effects of matched stimulation (i.e., music) on vocal stereotypy and acquisition of novel skills. Non-contingent access to music decreased levels of vocal stereotypy across participants and did not hinder mastery of discrimination skills. In addition, noncontingent access to music had only a minor impact on the participant’s latency to perform mastered tasks.

This thesis first introduces the basic notions of univariate survival analysis. Then the survival analysis setting is extended to competing risk models, i.e. the cases considering several events of interest or several causes of one event. In the competing risk model, we discuss the problem of identification, which means that it is not possible to identify marginal distributions from observed competing risk data. Next, we present copula models, which are a suitable mathematical tool for modelling dependence structure between random variables. We explain their basic characteristics, present some useful copula families and the relationship of copula parameters with certain dependence (correlation) measures. Further, we show the utilization of copulas within competing risks models and how they can be helpful in the solution of identifiability problem. Finally, we apply the listed theoretical knowledge in a simulated example. Powered by TCPDF (www.tcpdf.org)

The thesis presents fundamental characteristics of survival analysis in the case of competing risks and their relationships. In the case without regression, basic nonparametric estimates and a logarithmic likelihood function for parameter estimates is given. The main focus is on Cox's proportional hazards model (PH), a model with accelerated time (AFT) and a flexible regression model (FG) are also mentioned. The identifiability of the associated survival function is solved using copulas. Basics of copula theory and the measurement of dependence by correlation coefficients (Pearson, Spearman and Kendal) are described in a separate chapter. A substantial part of the theory is practically used in a generated case without regression.

In 2017, more than 6.9 million employees parted ways with their employer because of voluntary employee turnover, layoffs, or terminations. Emergency call center supervisors who fail to implement adequate job satisfaction strategies experience reduced productivity and increased voluntary turnover. The purpose of this multiple case study was to explore the strategies some southern Ontario 911 call center supervisors used to reduce job dissatisfaction. The conceptual framework supporting the study was the competing values framework. The population included 6 supervisors of 911 call centers in the province of Ontario, Canada, who successfully implemented job satisfaction strategies. Data were collected from interviews with the leaders and documentation. Data were analyzed using Yin's 5-step process. Three themes emerged: provide supportive leadership, create a balanced culture, and provide non-financial rewards. The implications for positive social change include healthy working communities through decreased job dissatisfaction resulting in organizations' greater productivity and provision of services.

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