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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

The efficacy of sanitation on microbiological hazards in ready-to-eat food outlets from selected primary manufacturers in Gauteng Province, South Africa

Lambrechts, Andre Albertus January 2011 (has links)
Dissertation submitted in fulfilment of the requirements for the degree Master of Technology: Environmental Health in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2011 / The retail sector in South Africa is increasingly evolving into a dynamic industry, driven by changes in technology, saturating markets and globalisation. A major phenomenon in South Africa has been the evolution of hypermarkets, which sell large quantities of almost all consumer goods on a self-service basis. The South African consumers are becoming increasingly health conscious and, as such, the demand for wellness foods, health and convenience food has escalated. Convenience foods are expected to remain popular with consumers and supermarkets and will therefore increase the amount of ready-to-eat food items offered. As the retail industry has changed over the last two decades, so has the epidemiology of foodborne illnesses, with an increase in the incidence of bacterial infections caused by emerging organisms. In addition, there are certain food safety issues specifically associated with ready-to-eat foods. In recent years, incidences of enteric diseases associated with meat consumption have risen. The emergence of several new foodborne diseases has led to an increased focus attention on the issue of food safety by consumers and the industry. The most commonly implicated foods in these disease outbreaks have been meat and dairy products. The microbial load of eight convenience food manufacturing plants was determined by firstly sampling stainless steel food contact surfaces after they had been cleaned and sanitised at the end of a day‘s shift. The samples were analysed for Total Plate Count (TPC), Escherichia coli, Salmonella species and Staphylococcus aureus and Listeria. The results showed that 59 % of the total areas sampled for TPC failed to comply with the legal requirements for food surfaces specified in the South African Health Act (< 100 cfu.cm-2). Listeria was detected in 23 % of the samples taken and E.coli was found in 1.3 % of the samples, while S. aureus was not detected in any of the samples. Fifty percent of the plants applied conventional cleaning methods for cleaning and sanitation and the remaining 50 % used the low-pressure foam (LPF) method. The bacterial results of the two cleaning methods were statistically compared and a statistically significant difference (P ≤ 0.05) was found between the TPC means of the cleaning methods after cleaning. No statistically significant difference (P > 0.05) was found in terms of the Listeria species counts after both cleaning processes. The LPF method proved to be the superior cleaning option for reducing TPC counts. Secondly surface samples were collected from washed and sanitised dominant hands of food handlers and analysed for the presence of total plate counts, S. aureus and E. coli. The study aimed to evaluate the efficacy of hand washing practices and sanitation before commencing work. A total of 230 samples were collected, involving 100 % of the food handlers in selected convenience food outlets. The highest bacterial count taken from handswas 7.4 x 10-3 cfu.cm-2 and the lowest showed no detectable growth. Forty percent of the TPC analysed complied with the legal limit of < 100 cfu.cm-2 and only 18 % of the food handlers had no detectable bacteria present on their hands. One hand sample tested positive for E. coli, which is generally viewed as an indication of faecal contamination. S. aureus could not be detected on the hands of any of the food handlers. The results of this study indicated that hand hygiene is unsatisfactory and underlined the importance of further training to improve food handlers‘ knowledge of good hand washing practices. The study also aimed to present data on the food hygiene knowledge and practices of food handlers based on a representative sample from convenience food outlets in the Gauteng area. The management, as well as food handlers, were interviewed without prior announcement and managers were interviewed prior to starting their shifts, followed by food handlers, after they had passed through the change room and hand wash facilities. Although the majority of food handlers adhered to basic hygiene principles, the results highlighted a need for proper and continuous training in hygiene practices, not only for food handlers, but also for management. Furthermore, all food handlers should adhere to a formal cleaning schedule and specific courses should be planned for food handlers. Most training is done away from the workplace and the workers might find it difficult to translate theory into practice. Although food safety training programmes are essential, behavioural changes will not occur merely as a result of having received training but rather continuous development of food handlers. In conclusion, the popularity of convenience food is bound to increase with the growing appeal for modern foods. Consumers in South Africa nowadays demand good quality and safe products at a reasonable cost. Due to continuous time constraints, convenience food is the food of the future for the working mother. It is clear that managing foodborne disease is a challenge and an economic problem subject to various constraints. Food safety has too often become a hit-or-miss gamble, with parents obliged to roll the dice when it comes to the safety of their children‘s food and consumers in general. The food industry therefore needs to improve food safety processes to prevent the contamination of foods and use methods to ensure safe food for consumers. Better training, more testing and better methods of tracking food must be utilised to verify that the processes are working. This study endeavoured to add to the understanding and improvement of hygiene processes as well as food handlers‘ practices in the convenience food industry in the Gauteng Province.
32

Evaluation of bambara groundnuts (Vigna subterrenea (L.) Verdc.) milk fermented with lactic acid bacteria as a probiotic beverage

Murevanhema, Yvonne, Yeukai January 2012 (has links)
Thesis presented in partial fulfilment of the requirements for the degree of Master of Technology (Food Technology) Department of Food Technology Faculty of Applied Sciences Cape Peninsula University of Technology, 2012 / The aim of this study was to evaluate bambara groundnut milk (BGNM) subjected to fermentation with lactic acid bacteria (LAB) as a probiotic beverage with a view to developing value-added product. Central Composite Rotatable Design (CCRD) was used to optimise the hydration time and temperature of BGN flour for optimum BGN milk (BGNM) production. The optimum time and temperature was 2 h at 25oC. The effect of variety was assessed on the quality and consumer acceptability of BGNM prepared from five varieties of BGN (black, red, brown, brown-eye, and black-eye) which were representatives of the BGN available in South Africa. BGNM from the five varieties differed significantly (p<0.05) in, lightness, chroma, redness, yellowness, hue and antioxidative activity, while the pH were not significantly different. The four BGNM samples were significantly different (p < 0.05) in appearance, colour, mouthfeel and overall acceptability but not in aroma and taste. A three factor design (4 x 3 x 3) consisting of probiotics (Lactobacillus acidophilus, L. bulgaricus, L. casei and L. plantarum), temperature and fermentation time, were used to estimate the optimal conditions for the production of BGN probiotic beverage (BGNPB). The optimal condition for the production of BGNPB was estimated to be 35oC for 24 h with a desirability of 0.854 for L. bulgaricus. The next promising probiotic was L. plantarum that could be fermented at 35oC for 24 h with 0.843 desirability. BGNM from the red variety were fermented with L. bulgaricus and L. plantarum and L bulgaricus (in combination), making plain and sweetened BGNPB which were evaluated for their quality and consumer acceptability. The four BGNPB samples were significantly different (p < 0.05) in aroma, taste, mouthfeel and overall acceptability but not in appearance and colour. The plain BGNPB were assessed for their proximate composition, antioxidant activity, in vitro probiotic tolerance to simulated gastric juices and bile and a 28 days shelf life study at 5, 15 and 25oC. The protein, total dietary fibre (TDF), ash and antioxidative activity of the BGNPB were significantly different while the fat and carbohydrates were not significantly different. Time and concentration of the gastric juice and bile had significant effects on the percentage bacterial survival of probiotics in the BGNPB. However, the probiotics did survive, in low numbers, in the simulated gastric juice and bile after 180 and 240 minutes of incubation. Titratable acidity, pH, microbial load and colour of the BGNPB were significantly affected by the storage time and temperature during the shelf life study. At the 5oC storage temperature the BGNPB had a right censored shelf life on day 28. At 15oC the shelf life was 18 and 10 days for L bulgaricus and L. plantarum and L. bulgaricus respectively. The outcome of this research showed that a novel BGNPB product can be made from fermenting BGNM with LAB.
33

An investigation into the potential of developing an in vitro method for propagating strelitziaceae

North, Jade Joan January 2011 (has links)
Master of Technology: Horticulture in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2011 / A study was conducted to investigate the effects of: i) various media compositions and wounding treatments on the in vitro germination, growth and regeneration of Strelitzia reginae plantlets derived from zygotic embryos, ii) antioxidants, plant growth regulator (PGR) concentrations and plant tissue wounding treatments on phenolic compound production. One experiment consisted of 8 medium types including different combinations of Murashige and Skoog (MS) medium strength, activated charcoal and vitamin supplements. Twelve replicates were used for each treatment. In another experiment, germinated plantlets were subjected to 2 wounding treatments; (unwounded explants (control) and explants longitudinally sectioned through the apical meristem). The explants were transferred to ten different regeneration media consiting of different concentrations and combinations of auxin and cytokinin supplements and antioxidants. Ten replicates were used for each treatment. Results indicated the positive role of activated charcoal (AC) in reducing oxidative browning of embryo explants. The highest germination rate of embryos was observed in media containing AC without vitamin supplementation. Germination significantly decreased with the addition of vitamins. With regard to effects of various media compositions and wounding treatments on in vitro growth and regeneration of Strelitzia, significant results were achieved with 1-naphthalene acetic acid (NAA) and 6-benzylaminopurine (BAP) concentrations on explant discoloration and callus formation. The antioxidant treatments, activated charcoal (AC) and ascorbic acid (AA) significantly affected explant discoloration, the induction of callus and the length of roots developed. Wounding treatments affected plant height, increased explant height and callus formation. Interactions between higher NAA and BAP concentrations together with wounding resulted in the most effective treatment in reducing explant discoloration at the media contact point. Furthermore, results showed the various NAA and BAP concentrations to significantly affect phenolic exudation. The media containing the highest PGR concentration resulted in the highest phenol content. AC significantly reduced the total phenol content of media by 53%, compared with AA. Phenolic exudation was significantly increased as a result of explant wounding. Various interactions between the NAA and BAP concentrations, antioxidants and wounding affected phenolic exudation and the total phenol content of media. This study provides insight into the contributing factors and methods of overcoming the major problem of phenolic oxidation and promoting the in vitro growth and regeneration of Strelitzia.
34

The effects of various drip fertigated water quantities on hydroponically cultivated Cucumis sativa L.

Sonnenberg, Donovan Mark January 2012 (has links)
Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Horticulture in the Faculty of Applied Sciences at the Cape Peninsula University of Technology, 2012 / The effects of various water quantities were assessed on Cucumber (Cucumis sativa L.) grown hydroponically in the greenhouse. The objectives of the study were to evaluate influence of water quantities on: i) photosynthesis and chlorophyll content of Cucumis sativa L.; ii) the nutrient uptake in Cucumis sativa L. iii) flavonoid and anthocyanin metabolism in Cucumis sativa L. and iv) growth and yield in Cucumis sativa L. The treatments included 8 various water regimes (2l/h, 4l/h, 6l/h, 8l/h, 10l/h, 12l/h, 14l/h and 16l/h. The plants received water five times a day, making it 10, 20, 30, 40, 50, 60, 70, and 80 litres per day. Results showed that generally the Photosynthetic rate (A), intercellular CO2 concentration (Ci) and stomata conductance (gs) and the transpiration rate of the cucumber plants were significantly increased by increasing water quantities compared with lower water quantities. Additionally, there were significant improvements in leaf colour in weeks 2, 3, 4, 5, 6, 7 and 8. Overall, the foliage colour was improved as water supply was increased. The greener leaves were documented in treatments supplied with higher water doses. Additionally, the chlorophyll content of cucumber plants was increased significantly with varying water quantities. The highest chlorophyll contents were found in plants treated with 16l/h. The fresh and dry weights of roots, leaves and stems were significantly (P≤0.001) influenced by different water quantities supplied to Cucumis sativa L. The largest quantity of fresh roots was recorded in the control treatment (2l/h) in comparison with all other treatments. However, the best growth with regard to fresh and dry weights of leaves and stems were recorded by supplying the water quantities ranging from 10-16l/h. Altering water supply significantly (P≤0.001) affected the uptake of nitrogen, phosphorous, potassium, calcium, sodium, copper, zinc, aluminium and iron in roots of Cucumis sativa L. Irregular results were recorded in the uptake of these nutrients in the roots. However, leaf uptake of N, P, K, Ca, magnesium, sulphur, Cu, Zn, manganese, boron, and Al responded significantly (P≤0.001) to the different water quantities. The best result for each was observed at quantities involving 16l/h. In stems of cucumber water quantities significantly (P≤0.001) affected the uptake of N, P, K, Ca, Mg, Na, S, Cu, Zn, Mn and B. The highest uptake of N, P, Ca, Mg and S were found at the maximum supply of water (16l/h) compared with the control (2l/h). Sodium uptake showed irregular patterns, whereas K and Zinc uptake peaked at 14l/h. The data from this study showed that flavonoid metabolism was not significantly affected by the different water quantities supplied to cucumber plants. However, the anthocyanin content in roots, leaves, and stem was significantly influenced by water levels. The lowest water quantity (2-6l/h) significantly increased the levels of anthocyanins in all tissues tested. Increasing water quantities significantly decreased the anthocynanin metabolism in all tissues. Plant height displayed significant differences with water quantities from weeks 1-8. In week 1, the plant height was superior at supplying 4l/h in comparison with other treatments. In week 2 and 5 irregular trends were detected. At weeks 3 and 4, plants supplied with 8-12l/h displayed superior plant height performance. At weeks 7-8, significant and optimal results were observed at water quantities ranging from 4-16l/h compared with the control treatment. Water quantities significantly (P≤0.001) affected the number of leaves per plant from weeks 2-8. Irregular results were displayed in weeks 2 and 3. At weeks 4 and 5, the highest numbers of leaves were in water quantities of 12l/h and 10l/h, respectively. Generally, leaf numbers increased with increasing water levels from weeks 6-8. Plant vigour was significantly affected by the alteration of water quantities at weeks 1, 2, 4, 5, 6, 7 and 8. At weeks 1 and 4, more vigorous plants were found in the treatments that received from 10-16 l/h. At weeks 2 and 5, optimal results were found at treatments that received from 6-14l/h. At weeks 6, 7 and 8, the most vigorous plants were found at the highest water quantity of 16l/h. With fruit length, fruit width, rind colour, fruit quality (marketable fruit) and weight, results from the harvest done in the first, second and third week showed that water quantities significantly influenced these parameters. Optimal results were reported when the plants were supplied with water ranging between 14-16l/h. During harvesting at week 4, the fruit length, width, rind colour, were of marketable quality at 16l/h. Generally, the plants that received highest amount of water (16l/h) had the highest cucumber yields compared with all other treatments. Higher water quantities in this study resulted in increased physiological responses such as photosynthesis and nutrient uptake which resulted in the higher fruit yields. In water-limited environments, results from this study could assist growers with reasonable cucumber yields while saving water for other farm uses.
35

The perception of corporate services in a Metropolitan Municipality on King III good governance compliance

Mutiro, Newton Sly January 2013 (has links)
Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Business Administration in Project Management in the Faculty of Business at the Cape Peninsula University of Technology 2013 / Good governance has been and is a growing phenomenon for almost all business organisations regardless of size, profit margins and purpose for existence. Government, quasi-government, non-governmental organisations and even civic organisations have adopted a project-based approach to business. The City of Cape Town Metropolitan Municipality is one such organisation that had adopted a project-based approach to business. The challenge was how to effectively and efficiently implement governance issues around projects and business organisations. Most organisations can easily be misled if issues of governance are not clearly defined and followed. A project-based approach helps in defining the resources needed at specific times, the time required for a specific task and the cost of a specific operation. In a multi-project environment (programme) resources are shared in a well-defined manner. The City of Cape Town Metropolitan Municipality has a huge responsibility in terms of successfully initiating, planning and implementing projects successfully. The magnitude and the dynamic complexities of their operation call for proper governance structures to be established within any municipality if service delivery is the main objective. Managing complex and mega projects calls for certain leadership traits. A fusion of these traits at different management levels will be critical for effective delivery of services to the electorate. Models and plans need to be in place as guidance to successful implementation of projects. A number of people, committees and institutions have developed different governance frameworks that can be adopted by organisations as a guide to good governance. This research is based on King III guide to good governance. Challenges experienced by other Municipalities and business organisations e.g. Nelson Mandela Municipality, Eastern Cape Education Department, Transnet, LeisureNet, Limpopo Provincial government and many others, directly relate to poor governance. This therefore calls for the investigation of the Corporate Services directorate in the City of Cape Town Metropolitan Municipality to establish the level of compliance with what King III had recommended as a framework for good governance. The City of Cape Town Metropolitan Municipality has different general governance frameworks in place. However they do not use them effectively because of different issues identified by the researcher. The major challenges facing the City of Cape Town Metropolitan Municipality are effective governance communication and lack of training in the practice of good governance. There were serious discrepancies when it comes to understanding and interpreting governance issues within the different levels of management. It is expected that an organisation like the City of Cape Town Metropolitan Municipality should have proper communication channels and effective training programmes. The researcher also found that information is not readily available to people who need it most yet the expectation is that information be readily available.
36

The employability skills of analytical chemistry graduates from an institution of higher learning: An investigation of their relevance to potential employers in the Western Cape

Nofemela, Fundisa Regina January 2013 (has links)
Dissertation submitted in partial fulfilment of the requirements for the degree Master of Technology: Business Administration in the Faculty of Business at the Cape Peninsula University of Technology 2013 / The shift in the employability skills required by employers has meant that, over and above their qualifications, graduates now need to have a set of specific skills that will enable them to be productive in the workplace. The basis for this study stems from the hypothesis that the intense competition for employment among graduates has meant that prospective employers now have a say in the attributes that are needed for potential employment. It is now no longer adequate for graduates to have a qualification, but to have, over and above the degree, specific employability skills that will enable them to be productive in the workplace. This study investigates the employability skills of analytical chemistry graduates at a university of technology for potential employers in the Western Cape. This was determined through a mixed-method approach, using both qualitative and quantitative research, and conducted amongst employers of analytical chemistry graduates in the chemical, cosmetic, petrochemical and pharmaceutical industries. In order to investigate the relevance of the employability skills, the following questions were asked: a. What skills are employers of new analytical chemistry graduates looking for in potential employees? b. What are the skills that past and current employers of analytical chemistry students, and graduates from the university of technology under investigation, have identified as important in these students and graduates? c. Is there congruence between the skills required by potential employers and those demonstrated by analytical chemistry graduates from the university of technology under investigation? This study was the basis for a potential further investigation into the development of a curriculum that will enable students to acquire the skills required by industry.
37

An analysis of the impact of variation orders on project performance

Ndihokubwayo, Ruben January 2008 (has links)
A DISSERTATION PRESENTED TO THE HIGHER DEGREES COMMITTEE OF THE CAPE PENINSULA UNIVERSITY OF TECHNOLOGY IN FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTERS OF TECHNOLOGY: CONSTRUCTION MANAGEMENT CAPE PENINSULA UNIVERSITY OF TECHNOLOGY, 2008 / This study investigated the impact of variation orders on project performance in order to take proactive measure to reduce them. The study had the following objectives, namely (1) to investigate the prevalence of variation orders on construction projects; (2) to determine the cost impact of variation orders; (3) to examine to what extent variation orders added value to construction projects; (4) to determine whether the activities associated with variation orders may be regarded as waste; (5) to identify the predominant origin agent as well as the causes of variation orders; and (6) to establish the nature and extent of the impact of variation orders on overall project performance. Literature relative to the research area was extensively reviewed. The data gathering approaches included an exploratory study on costs of variation orders on two construction projects, interviews with three top management personnel in construction contracting companies, the audit of site instructions with regard to waste and their value-addedness and self-administered questionnaires. A purposive sampling method was followed to identify participants into the study. The audit of site instructions revealed that most variation orders were beneficial. However, 14% of site instructions had waste associated with them. It was possible to quantify apparent waste associated with variation orders by means of an ‘origin-cause matrix’ designed for that purpose. Problematic situations arising from the occurrence of variation orders included discrepancies between the claimed and certified amounts. Variation orders impacted project performance with regard to cost and time overruns and disputes between parties to the contract. Most variation orders involved additional works. The complexity of works was the most predominant factor influencing the occurrence of variation orders. The reduction of the occurrence of variation orders was traced back to the pre-contract stage given that the most predominant origin agent of variation orders was the client and then due to an unclear brief of works to be executed. Suggestions regarding the reduction of variation orders include (1) adequate planning in advance is required by all involved parties before works start on site, (2) consultants should do a thorough concluding design and working drawings and contract documents should be complete at tender stage, (3) clients should provide clear brief, (4) enhance communication and all parties should be proactive at all times, (5) works should be supervised with an experienced and dedicated supervisor and (6) consultant should ensure that the design/specifications fall within the approved budget and the budget team should be appointed and participate during the design phase. The study suggests further investigation regarding the development of a more equitable basis of valuation of cost recovery which was beyond the scope of this research.
38

Development of nonlinear reconfigurable control of reconfigurable plants using the FPGA technology

Han, Yi January 2008 (has links)
Thesis submitted in fulfilment of the requirements for the degree Magister Technologiae: Discipline Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2008 / As one of the biggest developing country in the world, South Africa is developing very fast resent years. The country’s industrialization process is rapidly evolved. The manufacturing industry as one of the most important sections of the industrialization is playing a very heavy role in South Africa’s economic growth. Big percentage of population is involved in the manufacturing industry. It is necessary to keep and enhance the competitiveness of the South Africa’s manufacturing industry in the world wide. But the manufacturing companies are facing with unpredictable market demands and global competitions. To overcome these challenges, the manufacturing companies need to produce new products which can cater to the market demand as soon as possible. Reconfigurable Manufacturing System (RMS) is one of the possible solutions for the manufacturing companies to produce the suitable product for the market in a short period of time with low cost and flexibility. That is because the RMS can be reconfigured easily according to the required specifications for manufacturing the appropriate product for the market and with above mentioned characteristics. Now, RMS is considered as one of the promising concepts for mass production. As one of the very latest research fields, many companies, universities and institutions have been involved to design and develop RMSs. South Africa as one of the most important manufacturing country in the world, her own universities and researchers has the obligation to study this field and follow the newest development steps. In this project, a lab-scaled reconfigurable plant and a Field Programmable Gate Array (FPGA) technology based reconfigurable controller are used to realize and verify the concepts of the RMS in order to find the methodology of developing RMSs. The lab-scaled reconfigurable plant can be reconfigured into the inverted pendulum and the overhead crane. Although it is not used for manufacturing purpose, it can be used to verify the RMS concepts and the control strategies applied to it. Furthermore, control of the inverted pendulum and the overhead crane are both typical problems in the control field. It is meaningful to develop the controllers for them. As the reconfigurable plant is configured, the reconfigurable controller is reconfigured synchronously in order to produce the proper control signal for the reconfigured plant. In this project, both linear and nonlinear control strategies are deployed. Good results are received. The outcomes of the project are mainly for the education and fundamental research purposes, but the developed control strategies have significant sense towards the military missile guidance and the overhead crane operation in industry.
39

Augmentation of a nano-satellite electronic power system using a field-programmable-gate-array.

Cupido, Stephen William John January 2013 (has links)
Thesis is submitted in fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2013 / The CubeSat standard has various engineering challenges due to its small size and surface area. The challenge is to incorporate a large amount of technology into a form factor no bigger than 10cm3. This research project investigates the space environment, solar cells, secondary sources of power, and Field-Programmable-Gate-Array (FPGA) technology in order to address the size, weight and power challenges presented by the CubeSat standard. As FPGAs have not yet been utilised in this particular sub-system as the main controller, this research investigates whether or not the implementation of an FPGA-based electronic power supply sub-system will optimise its functionality by overcoming these size weight and power challenges. The SmartFusion FPGA was chosen due to its analogue front end which can reduce the number of peripheral components required by such complex systems. Various maximum power point tracking algorithms were studied and it was determined that the perturb-and-observe maximum power point tracking algorithm best suits the design constraints, as it only requires the measurement of either solar cell voltage or solar cell current, thus further decreasing the component count. The SmartFusion FPGA analogue compute engine allows for increased performance of the perturb-and-observe algorithm implemented on the microcontroller sub-system as it allows for the offloading of many repetitive calculations. A VHDL implementation of the pulse-width-modulator was developed in order to produce the various changes in duty cycle produced by the perturb-and-observe algorithm. The aim of this research project was achieved through the development and testing of a nano-satellite power system prototype using the SmartFusion FPGA from Microsemi with a decreased number of peripheral circuits. Maximum power point was achieved in 347ms at worst case with a 55% decrease in power consumption from the estimated 330mW as indicated in the power budget. The SmartFusion FPGA consumes only a worst case of 148.93mW. It was found that the unique features of the SmartFusion FPGA do in fact address the size weight and power constraints of the CubeSat standard within this sub-system.
40

Design and development of a battery cell voltage monitoring system

Prinsloo, Nick January 2011 (has links)
A Thesis for The Department of Electrical Engineering in fulfilment of the requirements for the Magister Technologiae degree in electrical engineering, at the Cape Peninsula University of Technology, 2011 / The purpose of this thesis was to design and develop a measurement system that would allow accurate measurement of individual cell voltages in a series cell stack. The system was initially proposed to be used in conjunction with an active cell balancer. This would allow for the efficient equalising of cells as well as provide detailed information on the cell stack and how the stack operates over time. Having a system that measures voltages accurately, with which the active cell balancer can be controlled would allow for peak cell lifetime and performance. Current battery management systems are large, complex and inefficient and a new way of battery management had to be investigated. To accurately measure individual cells in a series stack, the high common mode voltage must be negated. Different techniques that are currently used to create galvanic isolation were reviewed; circuits were designed and were simulated to find the most suitable design. The traditional methods used to create galvanic isolation did not provide adequate results. The methods were too inefficient and not accurate enough to be used. The methods that had the required accuracy were too complicated to connect in a useable system. This led to the investigation of integrated circuits created to measure voltages in large cell stacks. An integrated circuit from Linear Technology was chosen and a system was built. A system was thus designed that fulfilled the most desirable design specifications while delivering excellent results. The system allowed accurate, individual voltages to be measured in the presence of high common mode voltages. Accuracies and measurement time were well below the required system specification. Power consumption was high, but different component choice will lower power consumption to within specification. Excellent results were obtained overall with most, although not all results well below the design specifications. By including current measurements, as well as other technologies such as wireless communication, USB connectivity and a better data processor, this system will be at the forefront of current battery management technology.

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