Unbound linear operators in operator ranges

Many results in operator theory for example some perturbation results, are at present known only in the Banach space case. The aim of this work is to provide a natural generalisation of such results by considering operator ranges (the image of a bounded operator defined everywhere on a Banach space) as well as investigating and characterizing some of the properties of operator ranges. For the sake of generality we will for the most part be considering unbounded or closed linear operators instead of continuous everywhere defined linear operators. We will not be attempting to give exhaustive coverage of unbounded linear operators but will try to give some insight into the use of operator range techniques in the theory of unbounded linear operators. The first chapter will be aimed mainly at defining and introducing concepts used in later chapters. In the second chapter we turn our attention to the conjugate of a linear operator whilst also briefly looking at projections in an operator range. Chapter three is concerned mainly with investigating and characterizing the closed range property of linear operators whereas in the first part of chapter four we will be proving some fairly well known results on compact, precompact and strictly singular operators to be used in chapter five. In the second half of chapter four we will investigate the relationship between weakly compact operators and pre-reflexive spaces. Chapter five will be dealing with perturbation of semi-Fredholm operators by first of all continuous and then by strictly singular operators. We close with a discussion of the instability of non-semi-Fredholm operators under compact and a-compact perturbations

The Giesel ejector: a practical appraisal of its ability to improve the performance of a steam locomotive

An ejector (jet pump) is a continuous flow pump which utilises the kinetic energy in a high velocity fluid stream, to entrain end extract a second fluid from a given location

High levels of stigma towards substance use and depression amongst non-specialist health workers in South Africa

As mental health-related stigma is a significant barrier to seeking and receiving healthcare, stigma amongst non-specialist health workers (NSHWs) towards patients with major depressive disorder (MDD) and substance use disorder (SUD) could negatively affect mental health service provision. This study aimed to explore (1) the level of stigma towards MDD and SUD among NSHWs employed in primary care settings in South Africa, (2) the extent to which socio-demographic factors might be associated with stigma levels amongst these NSHWs, and (3) NSHWs' interest in receiving training for MDD or SUD. Overall, 81 NSHWs completed a culturally modified version of the Social Distance Scale (SDS) that assessed stigma towards a hypothetical patient with MDD and a hypothetical patient with SUD; higher cumulative SDS scores represented greater stigma. With a possible range of 6-24, we found a mean SDS score of 9.0 (SD=3.7) for MDD and 11.7 (SD=4.4) for SUD. Results show elevated levels of stigma towards both hypothetical patients, with significantly higher mean SDS scores for SUD compared to MDD (p <0.001). No socio-demographic variables were significantly associated with MDD or SUD stigma levels. When asked to rate their interest, more NSHWs were “very interested” in receiving training for MDD (90.0%) than for SUD (80.8%); this difference was statistically significant (p=0.027). High levels of self-reported stigma, coupled with a desire for further training, suggest that it would be prudent to incorporate stigma reduction measures into future MDD and SUD training programmes for NSHWs

The effect of civil unrest on nursing personnel and nursing services in the Cape Peninsula during 1986

Civil unrest has become a feature of South African society and has resulted in varying degrees of social disruption. Health services, particularly those located in residential areas, have been affected. As nurses constitute the largest group of health care professionals in South Africa, and often live in the communities in which they work, they serve as useful indicators both of community dynamics and the health services. This study describes the effect of civil unrest on nursing personnel and determines the short term and long term effects on health and nursing services. A self-administered questionnaire was distributed to all community based nurses working in two major health services in the Cape Peninsula in 1986. In addition, routinely available health data directly related to nursing services were collected on a monthly basis for the period 1984-1988 (inclusive). For purpose of analysis the Cape Peninsula was classified into areas of high, medium and low impact violence evident in 1986. The nursing questionnaire had a response rate of 76.9%. Problems associated with civil violence that were identified were the need for nurses to ensure the safety of their own children; transportation to and from work; identification as nurses; security; curtailment of nursing services (particularly home visits); disruption of ancillary services; employer attitudes; political and police activity. Health data relating directly to nursing services revealed disrupted antenatal dinics, an increase in the number of women booking antenatally following a time of disrupted booking clinics, an increase in deliveries associated with interrupted family planning clinics, a decrease in treatment of ophthalmia neonatorum and umbilical sepsis associated with curtailed home visits. The study indicated that nurses wer:a not adequately equipped to cope with the changing demands mad1:1 upon them during periods of political instability; that civil unrest negatively affects nursing personnel and nursing services; and further, that disruption of a service impacted other services. It is recommended that in areas of violence it is essential to have a single management team co-ordinating all health services; education and in-service training must address the needs of nurses.and health care in situations of civil violence; nurses must strive to be accepted as universal carers and be committed to justice and peace; and the professional association must be proactive in providing guidelines to nurses who are affected by civil unrest

Traditional Image Processing and Modern Computer Vision Techniques for the Study of Two-Phase CO2 Flow

The work presented here details the development of software-based tools for the extraction of physical parameters which describe two-phase (gas-liquid) upwardly flowing CO2, for the purpose of using these parameters as sensor data for a control feedback loop, and for the automatic detection of flow regime transition, which is useful for the development of flow regime maps. The core focus of this thesis is the development of these tools in such a way that their primary input is an image or set of images. To achieve this, two schools of thought are explored: First, traditional image processing techniques are employed to study the flow. These techniques require manual image feature selection, and they make use of purposebuilt algorithms to extract the desired parameters from an input image using these features. The second approach makes use of modern computer vision techniques, where the image features are automatically learnt through machine learning, and an end-to-end network design makes use of these features to extract the desired output without manual tuning. Traditional image processing is used to develop an algorithm which extracts the void fraction value from an image of bubbly flow. This algorithm works by detecting individual bubbles within the input image, and then estimating the volume of each bubble (with uncertainty) in order to calculate the final void fraction. The outputs seen from this algorithm correlated well with those produced by established models for calculating void fraction, but the problem with this algorithm is its limited scope of use: it is only applicable to images of bubbly flow, a flow regime which exists for only a small portion of the total possible vapour quality range under steady state conditions. Two different tools, which share a similar architecture, and which classify flow regime and vapour quality respectively, were successfully developed using modern computer vision techniques. These models both take in video clips as their inputs. The approach makes use of deep learning to train a convolutional neural network (CNN), which is used for individual frame classification and image feature extraction, and a deep long short-term memory (LSTM) network, used to capture temporal features present in a sequence of image feature sets, and to make a final vapour quality or flow regime classification. The proposed architecture achieves accurate flow regime and vapour quality classifications in practical application to two-phase CO2 flow in vertical tubes based on off-line data and an on-line prototype implementation, developed as a proof of concept for the use of these models within a feedback control loop. The successful application of the LSTM network reveals the significance of temporal information for image based studies of multi-phase flow. When comparing these parallel developments, the advantages and disadvantages of the two approaches can be clearly seen. Traditional image processing requires far more extensive domain specific knowledge and manual fine tuning, but this approach allows for a user to clearly understand the outputs of the algorithm, whether they are correct or incorrect, as the internal mechanisms of the algorithm are all purpose built. This is not the case for deep learning based modern computer vision methodologies, which are more of a “black box”. These methods require a large amount of training data, but less domain specific knowledge, as the important features from the input data do not need to be manually selected and processed by the user. This leads to high performing systems which are difficult to understand and debug. There are different cases in which each of these methods would be preferable, but with the rapid evolution of deep learning and computer vision over the last few years, deep learning based computer vision appears to be replacing the traditional approach in many cases

Dickens's comic art: a study of the comic element in Dombey and .son, little Dorrit, and great expectations

The new Clarendon Dickens Edition (General Editors: John Butt and Kathleen Tillotson), was not available at the time' of writing for all of the novels which are studied in this thesis. Considerations of consistency and availability, therefore, dictated my use of the New Oxford Illustrated Edition of Dickens's novels. Details of the three main works referred to in this thesis are as follows: Dealings with the Firm of Dombey and Son (1848; rpt. Oxford: O.U.P., 1950) Little Dorrit (1857; rpt. Oxford: O.U.P., 1953) Great Expectations (1861; rpt. Oxford: O.U.P., 1953) All other quotations and references to Dickens's. works also refer to the New Oxford Illustrated Edition, unless otherwise noted. I have consulted the Clarendon Dickens (Variorum) Edition where applicable, and the few pertinent textual variations have been duly footnoted. All word-divisions at line endings are sanctioned by the Collins Ge~ Dictionary of Spelling and Word Division, compiled by S.8. Marshall (London: Collins, 1968)

An investigation into 88 KV surge arrester failures in the Eskom east grid traction network

The Eskom East Grid Traction Network (EGTN) supplying traction loads and distribution networks has experienced at least one surge arrester failure over the past ten years. These failures results in poor network reliability and customer dissatisfactions which are often overlooked. This is because reliability indices used in the reliability evaluation of transmission and distribution networks are different. It is suspected that fast transient faults in this network initiate system faults leading to surge arrester design parameter exceedances and poor network insulation coordination. Preliminary investigations in network suggest that transient studies were not done during network planning and design stages. This may have resulted in the lack of surge arrester parameter evaluations under transient conditions leading to improper surge arresters being selected and installed in this network resulting in surge arrester failures that are now evident. These failures may also have been exacerbated by the dynamic nature of traction loads as they are highly unbalanced, have poor power factors and emit high voltage distortions. Poor in-service conditions such as defects, insulation partial discharges and overheating, bolted faults in the network and quality of supply emissions can also contribute to surge arrester failures. To address problems arising with different reliability indices in these networks the reliability of the EGTN is evaluated. In this work the reliability evaluation of the EGTN is done by computing common distribution reliability indices using analytic and simulation methods. This is done by applying the analytic method in the EGTN by assessing network failure modes and effects analysis (FMEA) when the surge arrester fails in this network. The simulation method is applied by applying and modifying the MATLAB code proposed by Shavuka et al. [1]. These reliability indices are then compared with transmission reliability indices over the same period. This attempts to standardize reliability evaluations in these networks. To assess the impact of transient faults in the surge arrester parameter evaluation the EGTN is modelled and simulated by initiating transient faults sequentially in the network at different nodes and under different loading conditions. This is done by using Power System Blockset (PSB), Power System Analysis Toolbox (PSAT) and Alternate Transient Program (ATP) simulation tools and computing important surge arrester parameters i.e. continuous operating voltage, rated voltage, discharge current and energy absorption capability (EAC). These parameters are assessed by in the EGTN by evaluating computed surge arrester parameters against parameters provided by manufacturers, the Eskom 88 kV surge arrester specification and those parameters recommended in IEC 60099-4. To assess the impact and contribution of in-service conditions, faults and quality of supply emissions in surge arrester failures these contributing factors are investigated by assessing infra-red scans, fault analysis reports, results of the sampled faulted surge arrester in this network and quality of supply parameters around the time of failures. This study found that Eskom transmission and distribution network reliability indices can be standardized as distribution reliability indices i.e. SAIDI, SAIFI, CAIDI, ASAI and ASUI indices are similar to Eskom transmission indices i.e. SM, NOI, circuit availability index and circuit unavailability index respectively. Transient simulations in this study showed that certain surge arresters in the EGTN had their rated surge arrester parameters exceeded under certain transient conditions and loading conditions. These surge arresters failed as their discharge currents and EACs were exceeded under heavy and light network loading conditions. This study concluded that surge arresters whose discharge currents and EACs exceeded were improperly evaluated and selected prior to their installations in the EGTN. This study found the EAC to be the most import parameter in surge arrester performance evaluations. The Eskom 88 kV surge arrester specification was found to be inadequate, inaccurate and ambiguous as a number of inconsistencies in the usage of IEEE and IEC classified systems terminology were found. It was concluded that these inconsistencies may have led to confusions for manufacturers during surge arrester designs and selections in the EGTN. The evaluation of fault reports showed that two surge arrester failures in this network were caused by hardware failures such as conductor failure and poor network operating as the line was continuously closed onto a fault. There was no evidence that poor in-service and quality of supply emissions contributed to surge arrester failures in this network. PSB, PSAT and ATP simulation tools were found adequate in modelling and simulating the EGTN. However the PSB tool was found to be slow as the network expanded and the PSAT required user defined surge arrester models requiring detailed manufacture data sheets which are not readily available. ATP was found to be superior in terms of speed and accuracy in comparison to the PSB and PSAT tools. The MATLAB code proposed by Shavuka et al. [1] was found to be suitable and accurate in assessing transmission networks as EGTN's reliability indices computed from this code were comparable to benchmarked Eskom distribution reliability indices. The work carried out in this research will assist in improving surge arrester performance evaluations, the current surge arrester specification and surge arrester selections. Simulation tools utilized in this work show great potential in achieving this. Reliability studies conducted in this work will assist in standardizing reliability indices between Eskom's transmission and distribution divisions. In-service condition assessment carried out in this work will improve surge arrester condition monitoring and preventive maintenance practices

African women in religion and culture Chewa women in the Nkhoma synod of the church of central Africa, presbyterian: a critical study from women's perspective

This thesis is an inter-disciplinary approach to the study of Chewa women in the Nkhoma synod of the Church of Central Africa Presbyterian. It is an interpretation, from a women's perspective within the Reformed tradition of their status, roles, and experiences. The introduction provides a detailed explanation of the area of study, African women's perspective of religion and culture, and methodology. I Chapter one aims at examining the context of women in Malawi. This includes the current demography, politics, economy and education as they affect women. The chapter also includes a background history of Chewa people and the church of Central Africa, Presbyterian which provide a base for the understanding of Chewa women in the Nkhoma synod. Chapter two considers the position of Chewa women further by providing a detailed analysis of their position in traditional society. The period under study in this chapter is 1400-1870s. Through the study of the Makewana cult, the chapter aims at showing that Chewa women traditionally had religious leadership roles. This led to a discussion on the concept of God among the Chewa. In studying these traditional roles, the chapter shows both the positive and negative elements in Chewa culture. Chapters one and two then provide a framework for chapters three, four, and five. Chapter three analyzes in detail the issues of Chewa women in religious. leadership and culture under the Dutch Reformed Church Mission and the Nkhoma synod from 1889 to present. It examines church policies on women's participation in church leadership positions and theological education. It also examines how the church has handled cultural issues, especially the women's initiation ceremony, bride wealth, child marriages, polygamy, and widowhood. The concern of this chapter is to show that while Christianity liberated Chewa women from some degrading cultural practices, it also denied women leadership positions. Chapter four takes the issue of women's participation in the church further by examining the Chigwirizano-Women's organization. The aim of this chapter is to explore what the organization means to women, how it runs, and most of all, its relationship with the synod. The chapter establishes that Nkhoma synod women do not only suffer from patriarchy but also from clericalism. Chapter five moves from the historical approach to a sociological one. It is primarily a survey of attitudes of men and women in the synod on the issues raised in chapters three and four. It also aims at finding out if the presence of women in the general synod would make a difference. Chapter six considers the effect on Nkhoma synod women who have participated in continental church women's organizations, especially their aims at raising the consciousness of women and the church with regard to women's issues. Chapter seven provides a summary of the findings. It also raises theological issues on interpreting the Bible from a women's perspective and a new understanding of authority in the church. The chapter concludes by posing a challenge to the synod to develop a theology that takes into account the experiences of women in the church, and enables them to fulfil a creative role within it

Organisational justice and workplace social support as predictors of employee wellbeing: A case of high-income workers in South Africa

Amongst the 17 Sustainable Development Goals as proposed by the United Nations, the study was concerned with promoting decent work (Sustainable Development Goal 8) and wellbeing (Sustainable Development Goal 3) amongst high-income workers. In line with what constitutes decent work, the study aimed to determine to what extent organisational justice (comprising distributive, procedural, interpersonal, and informational justice) and workplace social support (comprising perceived organisational support, perceived supervisory support, and perceived co-worker support) predicted employee wellbeing amongst high-income workers. The results provided insight into the multidimensionality of wellbeing and revealed two types of wellbeing present in the study, namely work-related wellbeing and interpersonal wellbeing. The study adopted a correlational research design, assisted by survey research, where an online survey was distributed via LinkedIn and WhatsApp to collect data from high-income workers (N = 120). The regression results indicated that all types of organisational justice and workplace social support predicted the two types of wellbeing. In addition, mediation analyses indicated that supervisory support strengthened the relationship between interactional justice (i.e., interpersonal and informational justice) and employee wellbeing (i.e., work-related and interpersonal wellbeing). The study thus highlighted the importance of supervisory support in achieving interpersonal and informational justice and proposed training aimed at interpersonal skills for supervisors to aid in the management of employee wellbeing. In addition, the study highlighted how COVID-19 had disintegrated the workplace as many organisations required their employees to work remotely. The study thus proposed that organisations should seek ways for employees to interact with one another in a virtual working environment. Therefore, as organisations maintain decent working conditions by implementing fairness and support in the workplace, they contribute to the management of employee wellbeing

Investigating the Optical Link Performance of the End-of Substructure Card and Susceptibility to SEUs

Particle physics experiments carried out by CERN attempt to investigate the fundamental forces of matter. One of these experiments is the ATLAS experiment, which studies the proton-proton collisions in the LHC. A series of upgrades are planned to increase the luminosity by a factor of five, leading to the high-luminosity LHC (HL-LHC). This upgrade will increase the potential for new discoveries but brings with it design challenges in relation to the harsh radiation environment and significant data throughput required. The ATLAS experiment is building a new detector to cope with these challenges, titled the Inner Tracker (ITk). A crucial part of this new detector is the End-of-Substructure (EoS) card, which constitutes the interface between the ondetector electronics and the off-detector systems. In addition to the operational challenges, the HL-LHC does not allow for repairs or replacing of EoS cards once operation commences, emphasizing the need for thorough testing and qualification of this component. This thesis focuses on characterizing the performance of the EoS card in the presence of radiation, under non-ideal operating conditions and the impact of optical link parameters. The first set of tests is centered on qualifying the radiation tolerance of the EoS card. The radiation environment within the ITk poses a threat to the stable operation of electronics as energetic particles have the potential to cause erroneous changes in device logic, known as Single Event Upsets (SEU). The SEU susceptibility of the EoS card, with a focus on the Versatile Link Plus Transceiver (VTRx+) component, is studied by irradiating the EoS card with a neutron source with a distributed energy spectrum and a peak energy of 11MeV while performing a bit error rate (BER) test to monitor for radiation induced errors. The second set of tests deals with characterizing the impact of an irregular power supply on the EoS card's performance through simulating noise on the supply lines and monitoring the response in BER. The final set of tests investigates the impact the VTRx+ configuration parameters have on the quality of the optical signal. These tests were carried out at the University of Cape Town (UCT) with the support of DESY, a national research institute in Germany, responsible for the production of the EoS cards. A number of new firmware, software and hardware modules were developed as part of this work in order to carry out the tests required. The most significant of which comprised a novel firmware addition allowing for the evaluation of the optical signal quality with an FPGA. This contribution is now being integrated into the quality control proceedings at DESY, to be used in assessing optical signal quality of the entire set of approximately 1552 EoS cards being produced