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Radiation Dose And Image Quality From Pelvic Localisation Computed Tomography In Oncology
Get PDFDissertationIntroduction: Computed tomography (CT) in radiation therapy plays an important role in the accurate identification of the position of the tumour and organs at risk, through high geometric fidelity of the CT image. It has been determined that the radiation dose from CT is amongst the highest from all medical imaging. There is concern over the increased radiation dose from pelvic CT localisation scans, due to the increased scan length and the necessity for high image quality used in radiation therapy planning. The necessity for high image quality, while lowering the CT dose and honouring the ALARA principles, is essential.
Four article-style studies, which evaluate the CT dose and image quality produced for pelvic localisation scans and that are ultimately aimed at publication, are presented in this research paper.
Purpose: The purpose of this research was to determine the CT dose and image quality produced for pelvic localisation scans in a department of oncology, Free State. The aim was to measure the dose received by patients during pelvic CT localisation scans and to determine whether the dose is justified in terms of imaging requirements for radiation therapy planning. The objectives of the research were to (i) determine baseline dose level for pelvic CT scan utilising an anthropomorphic phantom, (ii) measure patients’ CT pelvic localisation dose by using size-specific dose estimates, (iii) to verify whether the field of view (FOV) modified image quality for patients of different sizes, utilising water phantoms and (iv) objectively examine image quality using the contrast-to-noise ratio (CNR) for patients’ CT localisation scans. The significance of this research is reflected in filling the gap in existing literature, as most published studies were conducted on diagnostic CT dose and image quality.
Methodology: The research was conducted as a prospective research study, performed between January and June 2019, after ethical approval was obtained. All CT scans were produced on a TSX-201A (Toshiba Aquilion © Large Bore) CT scanner. The CT baseline dose level was established utilising an anthropomorphic phantom. The patient dose for pelvic CT localisation was calculated by the size-specific dose estimate (SSDE) that determines the dose, based on individual patient dimensions. The participants were divided into three body mass index (BMI) categories; these were underweight, normal weight and overweight. The CT image quality was examined based on scans of different sized water phantoms utilising CT quality assurance tests. The patients’ CT image quality was derived from the contrast-to-noise ratio (CNR). Results: A total of 131 participants met the inclusion criteria of the research study and were grouped according to their BMI into categories, these being categorised as: overweight-, normal- and underweight BMI category. For the baseline dose level, the best kV and FOV combination was determined for the 120 kV setting with a large (L), large-large (LL) or extra-large (XL) FOV, which calculated at 14.0 cGy using SSDE. In terms of the BMI patient category the median dose was determined as: 12.3 cGy for an overweight BMI; 14.8 cGy for a normal BMI, which is in line with the baseline CT dose and 17.1 cGy for the underweight BMI category.
The image quality determined as per phantom indicated that the 135 kV demonstrated the highest quality as well as the highest dose. In terms of FOV the small and medium sized phantom could be scanned with any size FOV. However, the large phantom excelled with the L, LL and XL FOV. The results for the patients in terms of image quality, based on CNR illustrated that the normal BMI category patients had the highest quality. It was furthermore concluded that the overweight BMI patient category reflected the lowest image quality.
Conclusion: The research questions were addressed and the objectives of this research were indeed met. In addition, this research addressed the gap in relevant literature, by determining results based on oncological CT scans and protocols in terms of dose and image quality. The fact that only one anthropomorphic phantom was available for dose calculations and that no tissue types were present in the phantom to utilise for the image quality, limited the research. The researcher recommends that protocols for patients in different BMI categories be established for CT pelvic localisation scans whilst simultaneously adhering to the ALARA principles. Research demonstrates that there is an industrial drive to decrease dose while maintaining image quality. Numerous techniques have been introduced to assist with the reduction of dose. One of these techniques was illustrated by Irish researchers who established national diagnostic reference levels (DRL’s) for breast CT protocols in oncology. It is believed that by utilising knowledge from both diagnostic and oncology CT scan techniques, the reduction of CT dose - while maintaining image quality - is an achievable goal
Optimal Energy Management Of A Grid-Connected Dual-Tracking Photovoltaic System With Battery Storage: Case Of A Microbrewery Under Demand Response
Get PDFArticleNowadays, the production of craft beer in microbreweries has become very popular all over the world.
However, recent studies have demonstrated that the craft beer production process in microbreweries can
be considered as energy intensive due to the fact that more to 8% of the production cost is allocated to
thermal processes such as heating and cooling. Therefore, most microbreweries have been applying
some Energy Efficiency actions to their production processes to decrease the amount of energy
consumed and maximize the profits.
In cases where the amount of energy consumed cannot be reduced using Energy Efficiency actions,
Demand Response measures are implemented to reduce the cost of energy needed to supply the
different processes involved. From the available literature, most of the studies based on Demand
Response in the microbrewery sector have focused on the use of heating resources for the onsite energy
generation to directly support the thermal processes. Very few published studies looked at the onsite
“electricity” generation with small scale renewable energy sources and onsite energy storage to assist
with energy cost reduction strategies.
Therefore, this paper develops an optimal energy management model to minimize the energy cost of a
microbrewery, under demand response, supplied with a grid-connected photovoltaic system with battery
storage system. As a case study, a microbrewery in South Africa has been selected for simulation
purposes. The detailed brewing process’s load profile, the solar resource, the system components’
specifications as well as the Time of Use energy cost structure has been used as input to the developed
model with the aim of assessing and analyzing the technical and economic performance of the proposed
system under the given operation conditions and constraints. The simulation results have shown that, as
compared to supplying the microbrewery exclusively by the grid, the break-even point of the proposed
supply option happens after 9.5 years of operation, corresponding to ZAR 398583.18 (USD 22592,09)
cumulatively spent. For the considered 20 years’ operation lifetime, the projected savings on the lifecycle
cost is ZAR 603490.49 (USD 34206,44) or 40.8%. The result of the discounted payback period analysis
indicated that the total investment cost may be recovered in 13.8 years.
The microbrewery is selected as a case study just to highlight the fact that some processes are critical
and cannot be shifted without compromising the quality of the final product. Therefore, the proposed
hybrid system, the developed model and the optimization methodology can be applied to any load in
different demand sectors (residential, commercial and industrial) implementing demand response
measures in order to reduce their operation energy costs
Exploring The Gaps In Renewable Energy Integration To Grid
Get PDFArticleThe continued integration of diverse renewable energy sources into the power grid has led to a significant decrease in power
system inertia, thus resulting in several challenges in the electric power system such as frequency instability and sharp rise in
rate of change of frequency (rocof). In order to combat these challenges, several technologies such as the use of energy storage
systems, hybrid energy storages system and hybrid systems have been used to provide fast frequency response and regulation.
This paper gives a comprehensive review of these technologies thus highlighting their applications, merits and demerits for
frequency regulation in renewable energy sourced grid. Furthermore, the research reveals that hybridized system provides better
characteristics than singly sourced renewable energy system, therefore the best suited hybrid system can be formed based on
the desired power grid characteristics and specific power requirement. Finally, it was revealed that FESS, SMES and SCES
have similar characteristics, nonetheless, their characteristics is complimentary to that of BESS, CAES and PHES technology,
and so a hybrid combination comprising of BESS and SCES could be best suited for fast frequency response in renewable
energy sourced grid
Review of Big Data Analytics, Artificial Intelligence and Nature-Inspired Computing Models towards Accurate Detection of COVID-19 Pandemic Cases and Contact Tracing
Get PDFArticleThe emergence of the 2019 novel coronavirus (COVID-19) which was declared a pandemic
has spread to 210 countries worldwide. It has had a significant impact on health systems and
economic, educational and social facets of contemporary society. As the rate of transmission increases,
various collaborative approaches among stakeholders to develop innovative means of screening,
detecting and diagnosing COVID-19’s cases among human beings at a commensurate rate have
evolved. Further, the utility of computing models associated with the fourth industrial revolution
technologies in achieving the desired feat has been highlighted. However, there is a gap in terms of
the accuracy of detection and prediction of COVID-19 cases and tracing contacts of infected persons.
This paper presents a review of computing models that can be adopted to enhance the performance of
detecting and predicting the COVID-19 pandemic cases. We focus on big data, artificial intelligence
(AI) and nature-inspired computing (NIC) models that can be adopted in the current pandemic.
The review suggested that artificial intelligence models have been used for the case detection of
COVID-19. Similarly, big data platforms have also been applied for tracing contacts. However,
the nature-inspired computing (NIC) models that have demonstrated good performance in feature
selection of medical issues are yet to be explored for case detection and tracing of contacts in the
current COVID-19 pandemic. This study holds salient implications for practitioners and researchers
alike as it elucidates the potentials of NIC in the accurate detection of pandemic cases and optimized
contact tracing
Using A Safety Management System To Reduce Errors And Violations
Get PDFArticleThis study discusses if and how a safety management system (SMS) mitigates or reduces errors and violations
on construction sites. The study investigated SMS systems on three major projects in South Africa. The results
affirmed that SMS helps to control hazards and risks, but the desired outcome could only be achieved if it
is designed and implemented appropriately. The results suggested that on the construction sites visited, inadequate
implementation ultimately resulted in errors and violations becoming the norm. The apparently poor
implementation observed during the study was cause for concern. It should be addressed, jointly, by both workers
and management
"Multi-Stakeholder Perspectives On Approaches For Addressing The Incidence Of Urban Public Open Space Encroachment: The Case Of Freedom Square, Bloemfontein
Get PDFArticleSeveral studies have investigated the extinction of urban public open spaces in
South Africa. However, a fixation by such studies on well-established primary cities
has been noticed, whilst limited attention has been paid to emerging major cities. In
addition, findings from these studies have resulted from the perspectives of either
planning entities’ representatives or representatives of the communities associated
with open space encroachment. This implies the absence of a systemic and multistakeholder
engagement. This article contributes towards bridging these observed
gaps through the elicitation of multi-stakeholder perspectives on the enablers of urban
public open space encroachment in major cities, using a Mangaung Metropolitan
exemplar. Adopting a qualitative case study research design, data were gathered
using semi-structured interviews and focus-group interviews. Participants were
purposively recruited from Mangaung Metropolitan Municipality planning department
and community members residing in Freedom Square township, Bloemfontein. The
data were analysed using thematic analysis. Significant enablers identified include
low levels of sustainability literacy, low levels of citizen participation in the planning
process, and planners’ inability to manage extant value conflicts. The findings from
this study contribute to a broader study that seeks to develop an urban open space
planning and management framework for forestalling the incidence of encroachment
in major cities. Accordingly, this study’s findings have practical implications for
relevant planning stakeholders who are keen on curbing the incidence of urban open
space encroachment in South African townships
The Learning Experiences Of First Year Accounting Student Teachers And Implications On Curriculum Implementation
Get PDFThesisThis study explored the learning experiences of first year accounting student teachers and the implications such learning experiences have on curriculum implementation. The researcher sought to explore these learning experiences and the realities in the learning environment from a student perspective. To this effect, grounded in the theoretical assumptions of multiple intelligences and social constructivism, a sequential explanatory mixed methods design was used to answer the research questions and satisfy the research objectives. The population was all the first year B.Ed. accounting student teachers. Purposive sampling was used for the quantitative strand of the study while random sampling was used for the qualitative part. Data was collected using a Multiple Intelligence and Constructivist Learning Questionnaire which was specifically developed by the researcher for the study.
Guided by relevant literature, the sections of the questionnaire comprised of analytical intelligence, practical intelligence, creative intelligence, guided instruction and social constructivism. It had a total of eighty-six items which students had to rate between a scale of one and seven. For the correlational part of the quantitative strand, twenty-seven hypotheses were formulated for the Pearson correlation coefficient and t-tests. Descriptive statistics were used to analyse data on the students’ scores on the extent to which they encountered learning activities which appealed to the constructs of multiple intelligences. Inferential statistics were used to analyse data on the relationship between age, gender and multiple intelligences, guided instruction and social constructivism and between multiple intelligences, guided instruction and social constructivism.
Descriptive statistics revealed that students moderately experienced learning activities which promoted analytical intelligence while they always experienced those which promoted practical intelligence. Creative intelligence was the most neglected one in the learning activities. Inferential statistics revealed no relationship between gender, age and multiple intelligences, guided instruction and social constructivism. However, a strong positive relationship was established between multiple intelligences, guided instruction and social constructivism. The quantitative findings were used to formulate 19 questions for the focus group interviews in the qualitative part of the study. These questions were also justified by relevant literature. The qualitative verdicts and the phenomenological voices of the students concurred with the quantitative diagnosis. The findings establish and reaffirm the need to adopt social constructivist teaching approaches which are not only pedagogically compatible with the assumptions of multiple intelligences, but also stimulate and promote the development of all the cognitive levels of students as epitomised by the revised Bloom taxonomy.
The study has produced compelling empirical evidence to argue that in comparative terms student centred approaches are more appealing to both multiple intelligences and the revised Bloom taxonomy. The study convincingly established that student centred approaches do not only provide students with meaningful learning experiences, but also develop, enhance and promote their multiple intelligences and sustainable academic and cognitive development. Social constructivist teaching approaches have been established as pedagogically effective enough to galvanise students to participate in the teaching and learning process, take collective ownership of their learning progress and that of their classmates and to demonstrate enough intrinsic motivation in pursuit of academic objectives.
Informed by the study findings and the pedagogical ramifications of social constructivism, the theory of multiple intelligences and the instructional imperatives of the revised Bloom taxonomy, the study developed a model called the Curriculum Implementation and Attainment of Learning Objectives Model. The model is an embodiment and illustration of curriculum implementation which is anchored on a mirage of social constructivist learning perspectives towards the realisation of multiple intelligences and the cognitive learning objectives enshrined in the revised Bloom taxonomy
The Impact Of Organisational Culture On Innovation And Knowledge Sharing At The Great Zimbabwe University
Get PDFDissertationBecause of globalisation, a highly complex and unpredictable world of work has emerged, characterised by accelerated digitalisation and intense competition. Organisations cannot afford to operate according to old paradigms; instead, flexibility and organisational change have to take centre stage. The critical ingredients of organisational change are continuous innovation and knowledge sharing. These two variables are enhanced by a conducive organisational culture.
Continuous innovation and knowledge sharing have become the linchpin of contemporary organisations, especially universities. Universities are considered to be reservoirs of knowledge where new and existing knowledge should be shared, bringing about continuous innovation for the benefit of society. Universities thus need to create a conducive environment to enable innovation and knowledge sharing.
Although numerous studies have focused on the relationship between organisational culture and variables such as innovation and knowledge sharing, universities have largely been excluded from such research. For this reason, the current study investigated the impact of organisational culture on innovation and knowledge sharing at Great Zimbabwe University (GZU). In the Zimbabwean context, policymakers now expect universities to lead the industrialisation and modernisation agenda.
A structured questionnaire was administered via the SurveyMonkey platform to a sample of 277 GZU staff members. A total of 195 questionnaires were collected for data analysis, yielding a response rate of 70.39%. The survey included a biographical section followed by sections on organisational culture (based on the Competing Values Framework), innovation (based on Dobni, 2008) and knowledge sharing (based on Jolaee, Md Nor, Khani, & Md Yusoff, 2014). Data were interpreted using descriptive statistics and partial least squares structural equation modelling (PLS-SEM) to analyse the relationships between the variables.
The results indicated that the university under investigation had a dominant rational/clan cultural orientation. Furthermore, a significant relationship was found between organisational culture and innovation and organisational culture and knowledge sharing. No significant relationship was found between innovation and knowledge sharing. The findings confirmed that the culture profile of the university is imperative for innovation and knowledge sharing to be facilitated. The study proposes that innovation and knowledge sharing can best be realised through the prevalence of the adhocracy culture type. A strategic framework is proposed to the management of GZU to enhance the pervasiveness of these variables. Areas of further research and the limitations of the study are also set out
OSTBC MIMO Transceiver System For Radio Signal Propagation Challenges Over Irregular Terrain In The Northern Cape, South Africa
Get PDFDissertationThe Northern Cape Province in South Africa, along the Orange River valley, has radio signal reception challenges due to high mountain ranges. The South African Electricity Authority- Eskom has High Voltage assets to monitor in this region. However, due to radio signal reception challenges, it is impossible to monitor their assets via the Supervisory Control and Data Acquisition (SCADA) system.
This research aims at developing a Very-High Frequency Orthogonal Space – Time Block Code Multiple-In Multiple-Out (VHF OSTBC MIMO) transceiver simulation model over a Rayleigh fading channel to address the radio communication challenges along the Orange River. The transceiver simulation model will resemble the harsh multipath environment presented by the mountainous terrain in the Northern Cape Province.
In environments with irregular terrain such as hills and mountains, the radio signal comes across phenomena such as reflection, refraction, diffraction and scattering. Therefore, the transmitted radio signal undergoes heavy fading and inter-symbol interference (ISI), thus negatively impacting radio link performance. However, the Multiple-input- multiple-output (MIMO) system, which uses multiple antennas both at the transmitter and receiver, takes advantage of this drawback and makes use of the high levels of multi-paths to operate at an optimum. MIMO creates spatial diversity which accounts for better radio link performance, it also yields increased capacity and improves Signal-to-Noise Ratio (SNR) while reducing bit errors.
Therefore, MIMO is one of the systems of interest considered best to exploit in this research. Space- time coding (STC) has also been considered because of its ability to increase the reliability of the channel and for its signal decoding simplicity at the receiver. A suitable lower frequency band to use for this research was also investigated. The most attractive characteristic of the low frequency (LF) band that was sought after was its ability to easily diffract over large obstacles than higher frequencies. The Very High Frequency (VHF) band at 70 MHz was found to meet the requirements for the model used. Therefore, this dissertation presents the simulation results of a VHF OSTBC MIMO transceiver model over a Rayleigh fading channel that is typical of the mountainous regions of the Northern Cape Province in South Africa, to help overcome radio signal reception challenges.
The following are the different component blocks that made up the model: Random Binary Generator (RBG), Quadrature Phase Shift Key (QPSK) Modulator, Orthogonal Space-Time Block Code (OSTBC) Encoder, Multiple-In Multiple-Out (MIMO) Rayleigh Fading Channel, Added White Gaussian Noise (AWGN), Orthogonal Space-Time Block Code (OSTBC) Decoder and a Quadrature Phase Shift Key (QPSK) Demodulator.
The simulation results in this research were generated using the following software packages namely: Matlab/Simulink, Atoll Wireless Network and Pathloss 4 Network. The Matlab/Simulink software was used to determine the bit-error-rate (BER) performance of four different OSTBC MIMO systems, each using different antenna arrays. TheMatlab RF Propagation Tool-SiteViewer was used to generate coverage predictions and receive signal strength (RSS) levels of three VHF OSTBC MIMO systems operating at three different low VHF frequency bands. The Atoll Wireless Network software was used to generate coverage plot predictions. The Pathloss 4 software was used to generate Line of Sight (LoS) predictions.
The results have shown that employing the low band VHF OSTBC MIMO transceiver system in irregular terrain environments can greatly improve radio signal reception, data speeds, bandwidth efficiency and link reliability
An Investigation Into The Influence Of Ageing Components On Medium Voltage Network Configurations In Semi-Urban Areas
Get PDFDissertationAccess to electricity for all South Africans is a goal that is still achievable. Access to electricity is not a luxury, but a need. Electricity improves all individuals’ lives, including those who live in semi-urban areas. Most of the medium voltage electrical networks that supply semi-urban areas are more than 30 years old; some are beyond repair. The existing electrical network configurations can cause accelerated ageing of electrical components, which can have a negative impact on performance, quality of supply and the public. The three semi-urban areas selected for the study were located in different parts of Northern Cape. Visual inspection, components failure rate and voltage simulations were used during the investigation to shed light on the details of the selected networks and their ageing characteristics as well as how ageing components or infrastructure affect the performance of the network, the safety of personnel and equipment, and quality of supply.
Components on the electrical networks selected for the research have different deterioration characteristics in accordance with their environment and design of electrical network configuration. Ageing of electrical components on the network is mainly due to the materials used on the components, which deteriorate naturally after a certain period of service. However, some of the materials age because they have been operated beyond their design specifications. In relation to ageing, the most affected components are jumpers, pole-mounted transformers and wooden poles. Component failures lead to poor performance of the network as well as an unsafe and unreliable network. Northern Cape has one of the largest landscapes in South Africa, which makes the distribution networks much longer than they usually are. Thus, more time is needed to inspect them than any other networks in South Africa.
Ageing of components on the electrical network can result in capital loss, loss of life and high supply interruptions, which result in loss of revenue for the power utility. The results of this investigation show that safe, reliable and correctly designed or utilized electrical networks in semi-urban areas can improve the performance and quality of supply as well as reduce the maintenance costs of the network. The study shows that most of the component failures were more common in certain areas of the selected networks. Premature failures and ageing of components on MV network was one of the main causes of deteriorating performance on MV networks in semi-urban areas. In the field of electrical engineering, the focus is more on major components on the electrical network including power transformers, reactors and generally high voltage components because they are more expensive. Medium voltage components generally cost less than high voltage components; consequently, the cost of their maintenance is much lower, which is a gap that can be explored in future research