With the ongoing trend in moving the upper levels of the automation hierarchy to the cloud, there has been investigation into supplying industrial automation as a cloud based service. There are many practical considerations which pose limitations on the feasibility of the idea. This research investigates some of the requirements which would be needed to implement a platform which would facilitate competition between different controllers which would compete to control a process in real-time. This work considers only the issues relating to implementation of the philosophy from a control theoretic perspective, issues relating to hardware/communications infrastructure and cyber security are beyond the scope of this work. A platform is formulated and all the relevant control requirements of the system are discussed. It is found that in order for such a platform to determine the behaviour of a controller, it would need to simulate the controller on a model of the process over an extended period of time. This would require a measure of the disturbance to be available, or at least an estimate thereof. This therefore increases the complexity of the platform. The practicality of implementing such a platform is discussed in terms of system identification and model/controller maintenance. A model of the surge tank from SibanyeStillwater’s Platinum bulk tailings treatment (BTT) plant, the aim of which is to keep the density of the tank outflow constant while maintaining a steady tank level, was derived, linearised and an input-output controllability analysis performed on the model. Six controllers were developed for the process, including four conventional feedback controllers (decentralised PI, inverse, modified inverse and H¥) and two Model Predictive Controllers (MPC) (one linear and another nonlinear). It was shown that both the inverse based and H¥ controllers fail to control the tank level to set-point in the event of an unmeasured disturbance. The competing concept was successfully illustrated on this process with the linear MPC controller being the most often selected controller, and the overall performance of the plant substantially improved by having access to more advanced control techniques, which is facilitated by the proposed platform. A first appendix presents an investigation into a previously proposed switching philosophy [15] in terms of its ability to determine the best controller, as well as the stability of the switching scheme. It is found that this philosophy cannot provide an accurate measure of controller performance owing to the use of one step ahead predictions to analyse controller behaviour. Owing to this, the philosophy can select an unstable controller when there is a stable, well tuned controller competing to control the process. A second appendix shows that there are cases where overall system performance can be improved through the use of the proposed platform. In the presence of constraints on the rate of change of the inputs, a more aggressive controller is shown to be selected so long as the disturbance or reference changes do not cause the controller to violate these input constraints. This means that switching back to a less aggressive controller is necessary in the event that the controller attempts to violate these constraints. This is demonstrated on a simple first order plant as well as the surge tank process. Overall it is concluded that, while there are practical issues surrounding plant and system identification and model/controller maintenance, it would be possible to implement such a platform which would allow a given plant access to advanced process control solutions without the need for procuring the services of a large vendor. / Dissertation (MEng)--University of Pretoria, 2020. / Electrical, Electronic and Computer Engineering / MEng / Unrestricted

The growing interest in sustainability amounts pressure on organisations to operate in more environmentally friendly ways, sparking the need for radical sustainable change. The purpose of this study is to discover what factors and conditions facilitate and hinder organisational learning for sustainability transitions (ST), a topic that has caught recent academic attention and thus needs further interdisciplinary research. The conceptual framework derives inspiration from the Four Factors of Learning for ST whilst the Competing Values Framework and the Three Loops of Learning are used as additional lens to better understand the conditions of learning for ST. The thesis will take a qualitative approach through conducting a content analysis of three company documents and seven semi-structured interviews with employees from a public service agency in Scandinavia currently implementing a transition lab. A descriptive analysis of the coded data highlights the levels of understanding and acceptance towards sustainability transitions from the case organisation and the conditions that facilitate and hinder organisational learning. The results show that the most prominent of the Four Factors of Learning for ST in the early phase of a sustainability transition is interpersonal, followed by material, institutional and intrapersonal. Within these factors, the discussion further highlights the most prevalent sub-codes and themes that reoccur in the data. Moreover, five key findings under the themes of flexibility versus control, resource availability through digitalisation, communication, collaboration and facing complexity using institutional logics were identified as the primary facilitating and hindering factors that promote learning for STs. Finally, recommendations are presented to inform both theory, and practice, as further analysing learning for ST is of high relevance to better understand and design these learning journeys and a more sustainable (organisational) future.

Functional analysis procedures were used to assess and treat multiple topographies of self-injurious behavior exhibited by an individual. An experimental functional analysis indicated that one topography, hand biting, appeared to be maintained by social positive reinforcement in the form of delivery of tangible items. The analysis also provided evidence that a second form of self-injury, skin picking, was automatically reinforced. To treat positively reinforced hand biting, access to a preferred tangible was arranged contingent on the omission of biting for a prespecified time interval. Hand biting was nearly eliminated, and low rates were maintained as the schedule of reinforcement was thinned to 10 min. Competing stimulus assessments identified that magazines effectively suppressed all occurrences of skin picking; therefore, noncontingent access to magazines was implemented. Using a combination of multielement and multiple baseline designs, we were able to demonstrate that the two topographies of self-injury were maintained by independent reinforcement contingencies and that interventions corresponding to each topography and function effectively treated both behaviors.

Los modelos de sobrevivencia o duración son útiles para modelar la distribución subyacente del periodo en el que ocurre el evento específico. El presente artículo analiza la duración de la tasa de referencia del Banco Central de Reserva del Perú (BCRP) y sus determinantes, haciendo uso de los modelos de sobrevivencia para un análisis que incluye los riesgos competitivos. En presencia de riesgos competitivos, el enfoque convencional de la duración puede obtener resultados sesgados y no interpretables. Por lo que, siguiendo la propuesta inicial de Gutiérrez y Lozano (2010), se recurre al análisis de riesgos competitivos a fin de analizar la duración entre los cambios de tasa de política monetaria en Perú, tomando en cuenta los dos escenarios posibles (incrementos y recortes) y magnitudes (25 pb y más de 25 pb); así como las variables que inciden en su comportamiento. Las regresiones bajo riesgos competitivos sugieren un comportamiento asimétrico en lo que respecta a las variables que definen los cambios de la tasa de referencia (incrementos o recortes). Variables como la inflación, producto y la tasa de referencia del periodo afectan al riesgo de ambos estados; sin embargo, un recorte en la tasa de referencia es también determinado por la brecha de la inflación local respecto a la extranjera y la duración de la tasa de referencia previa. En particular, los resultados son consistentes con una economía regida bajo el marco de metas de inflación. Se extrae que, el BCRP puede mantener la tasa de referencia en un nivel constante hasta que las variables de interés, como la inflación, se encuentren en condiciones críticas. Los resultados de las pruebas también confirman que la duración de tasas con cambios pequeños y grandes no son estadísticamente diferentes en las subidas de tasas. / Survival or duration models are useful for modeling the underlying distribution of the period in which the specific event occurs. This article analyzes the duration of the monetary policy rate of Peru and its determinants, in base of survival models including competing risks. In the presence of competing risks, the conventional duration method could get biased and uninterpretable results. Therefore, following the initial proposal of Gutierrez and Lozano (2010), this article includes competitive risks in order to analyze the duration between changes in the monetary policy rate of Peru, taking into account two possible scenarios, rate hikes and rate cuts, and magnitudes (25 bp and more than 25 bp); as well as the variables that affect their behavior. The regressions under competing risks suggest an asymmetric behavior between the variables that define the specific event of the monetary policy rate (increases or decreases). The models for rate hikes and rate cuts agree in finding the influences of variables, in the risk of both specific events: inflation, domestic product and the monetary policy rate. However, a cut in the monetary policy rate is also determined by the gap between local and US inflation and the duration of the previous rate. The results are consistent with an economy under the inflation targeting framework. As an inference, the Central Reserve Bank of Peru can maintain the reference rate at a constant level until the variables of interest, such as inflation, are in critical conditions. Test results also confirm that the duration of rates with small and large changes are not statistically different in rate hikes. / Trabajo de investigación

Indiana University-Purdue University Indianapolis (IUPUI) / Observational studies and clinical trials with time-to-event data frequently involve multiple event types, known as competing risks. The cumulative incidence function (CIF) is a particularly useful parameter as it explicitly quantifies clinical prognosis. Common issues in competing risks data analysis on the CIF include interval censoring, missing event types, and left truncation. Interval censoring occurs when the event time is not observed but is only known to lie between two observation times, such as clinic visits. Left truncation, also known as delayed entry, is the phenomenon where certain participants enter the study after the onset of disease under study. These individuals with an event prior to their potential study entry time are not included in the analysis and this can induce selection bias. In order to address unmet needs in appropriate methods and software for competing risks data analysis, this thesis focuses the following development of application and methods. First, we develop a convenient and exible tool, the R package intccr, that performs semiparametric regression analysis on the CIF for interval-censored competing risks data. Second, we adopt the augmented inverse probability weighting method to deal with both interval censoring and missing event types. We show that the resulting estimates are consistent and double robust. We illustrate this method using data from the East-African International Epidemiology Databases to Evaluate AIDS (IeDEA EA) where a significant portion of the event types is missing. Last, we develop an estimation method for semiparametric analysis on the CIF for competing risks data subject to both interval censoring and left truncation. This method is applied to the Indianapolis-Ibadan Dementia Project to identify prognostic factors of dementia in elder adults. Overall, the methods developed here are incorporated in the R package intccr. / 2021-05-06

Indiana University-Purdue University Indianapolis (IUPUI) / It is generally of interest to explore if the risk of death would be modified by medical conditions (e.g., illness) that have occurred prior. This situation gives rise to semicompeting risks data, which are a mixture of competing risks and progressive state data. This type of data occurs when a non-terminal event can be censored by a well-defined terminal event, but not vice versa. In the first part of this dissertation, the shared gamma-frailty conditional Markov model (GFCMM) is adopted because it bridges the copula models and illness-death models. Maximum likelihood estimation methodology has been proposed in the literature. However, we found through numerical experiments that the unrestricted model sometimes yields nonparametric biased estimation. Hence a practical guideline is provided for using the GFCMM that includes (i) a score test to assess whether the restricted model, which does not exhibit estimation problems, is reasonable under a proportional hazards assumption, and (ii) a graphical illustration to evaluate whether the unrestricted model yields nonparametric estimation with substantial bias for cases where the test provides a statistical significant result against the restricted model. However, the scientific question of interest that whether the status of non-terminal event alters the risk to terminal event can only be partially addressed based on the aforementioned approach. Therefore in the second part of this dissertation, we adopt a Markov illness-death model, whose transition intensities are essentially equivalent to the marginal hazards defined in GFCMM, but with different interpretations; we develop three nonparametric tests, including a linear test, a Kolmogorov-Smirnov-type test, and a L2-distance-type test, to directly compare the two transition intensities under consideration. The asymptotic properties of the proposed test statistics are established using empirical process theory. The performance of these tests in nite samples is numerically evaluated through extensive simulation studies. All three tests provide similar power levels with non-crossing curves of cumulative transition intensities, while the linear test is suboptimal when the curves cross. Eventually, the proposed tests successfully address the scientific question of interest. This research is applied to Indianapolis-Ibadan Dementia Project (IIDP) to explore whether dementia occurrence changes mortality risk. / 2022-05-06

Indiana University-Purdue University Indianapolis (IUPUI) / Survival analysis has broad applications in diverse research areas. In this dissertation, we consider an innovative application of survival analysis approach to phase I dose-finding design and the modeling of multivariate survival data. In the first part of the dissertation, we apply time to event analysis in an innovative dose-finding design. To account for the unique feature of a new class of oncology drugs, T-cell engagers, we propose a phase I dose-finding method incorporating systematic intra-subject dose escalation. We utilize survival analysis approach to analyze intra-subject dose-escalation data and to identify the maximum tolerated dose. We evaluate the operating characteristics of the proposed design through simulation studies and compare it to existing methodologies. The second part of the dissertation focuses on multivariate survival data with semi-competing risks. Time-to-event data from the same subject are often correlated. In addition, semi-competing risks are sometimes present with correlated events when a terminal event can censor other non-terminal events but not vice versa. We use a semiparametric frailty model to account for the dependence between correlated survival events and semi-competing risks and adopt penalized partial likelihood (PPL) approach for parameter estimation. In addition, we investigate methods for variable selection in semi-parametric frailty models and propose a double penalized partial likelihood (DPPL) procedure for variable selection of fixed effects in frailty models. We consider two penalty functions, least absolute shrinkage and selection operator (LASSO) and smoothly clipped absolute deviation (SCAD) penalty. The proposed methods are evaluated in simulation studies and illustrated using data from Indianapolis-Ibadan Dementia Project.

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Organisational culture is a long debated research field, one that is greatly influential in modern day workspace, possibly deeply affecting organisational performance. This thesis is a case study on Blizzard entertainment from 1997 to 2005, where Blizzard North and Blizzard South, two organisations, existed and worked on some of the company’s most influential games. The authors analysed and inspected the unique culture of each of the organisation, intending to understand the effect of organisational culture on video game development. The analysis is conducted utilising multiple organisational cultural theories and models. Both of the studios' organisational culture is explored in this study and the study aims to show the effect of these organisational cultures in the game development process. The importance of this research lies in studying the connection between organisational culture and the gaming development process. This research is for an audience which takes interest in starting their own company or working in one, people who want to understand how companies work and people who are interested to see different behaviours in different situations. The key findings of this study are about how organisational culture affects different aspects of game development such as design, approaches and relationships between peers.

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