Faculty of Engineering and Technology Theses and Dissertations
http://hdl.handle.net/10311/1389
2024-03-28T09:54:33ZDesign and implementation of an automated irrigation control system for optimal water usage and enhanced agricultural productivity
http://hdl.handle.net/10311/2452
Design and implementation of an automated irrigation control system for optimal water usage and enhanced agricultural productivity
Ncube, Innocent
Irrigation of crops is essential for profitable crop production in most arid regions. The “million dollar” question is: when to water, and how much water is needed? The answer to this question lies in the development of innovative ways of irrigation control. In most irrigation installations in developing countries, the trend is to irrigate or to water the crop at the farmer’s hunch without relying on scientific data. They do not use accurate data logging systems that gather data about the condition of the crop. This traditional approach of irrigation results in too much or too little water being delivered to the crop resulting in crop stress and reduced yield. This document outlines the design, development and implementation of a ‘smart’ and innovative automatic irrigation control system with Internet capability. The system makes use of accurate scientific methods of finding out if plants need water. If plants are found to be in need of water, the controller automatically triggers the system to deliver the right amounts of water to the crop. The design employs the Internet of Things (IoT) applications to automatically connect and download weather data and weather-forecast information from the OpenWeatherMap Internet server. The OpenWeatherMap is a Meteorological services provider company which is situated in London in the United Kingdom. OpenWeatherMap collects, stores and automatically disseminates on request, weather data about any geographical location in the world over the Internet. Through the automatic irrigation control system, the farmer is able to receive weather updates and weather forecast information covering the next thirteen days. The received weather data comprises ambient temperature, barometric pressure, ambient humidity, wind speed, sunrise and sunset times. The automatic irrigation control system’s ability to combine data from agricultural sensors and weather forecast information available on the Internet allows for optimisation of irrigation activities, thereby saving water and improving crop yield. To cater for situations where there are internet outages, the system has an in-built mini-weather station which measures local ambient temperature, ambient humidity and barometric pressure. The Internet capability of the system also enables the manufacturer to easily render remote technical assistance to the farmer. The system allows the farmer to use a smartphone or a personal computer to remotely monitor system parameters and crop performance from anywhere in the world through the Internet. The prototype was subjected to several validation tests and the results suggest that the system may reduce irrigation water consumption by 26%. It was concluded that the smart automatic irrigation control system results in optimised water usage and increased crop yield.
A dissertation submitted to the Dept. of Electrical Engineering, Faculty of Engineering and Technology, University of Botswana in partial fulfillment of the requirement of the degree of Masters in Science (Electrical & Electronic Engineering). Citation: Ncube, I. (2018) Design and implementation of an automated irrigation control system for optimal water usage and enhanced agricultural productivity, University of Botswana.
2018-01-01T00:00:00ZEffect of fruit maturity on yield and quality of seed oil and biodiesel of jatropha curcas found in Botswana
http://hdl.handle.net/10311/2450
Effect of fruit maturity on yield and quality of seed oil and biodiesel of jatropha curcas found in Botswana
Jonas, Mbako
This study was undertaken to investigate the influence of fruit maturity stage on yield and quality parameters of Jatropha curcas seed oil and derived biodiesel. The influence of fruit maturity on phorbol ester content (toxicity) in Jatropha curcas seed oil and seed cake was also investigated. Jatropha curcas (hereafter referred to as Jatropha) seeds used in this study were harvested from Jatropha plants adapted to Botswana climatic conditions. Biodiesel has received great attention as one of the renewable and clean burning fuels. This is so in an effort to reduce greenhouse gas emissions. Jatropha seed oil is considered as one of highly promising feedstock for biodiesel production. In order to meet the high demand of large scale biodiesel production, increment of seed oil output from Jatropha seeds is necessary. Harvesting Jatropha seeds/fruits when seed oil content is maximum is one of the factors than can help increase seed oil output from Jatropha seeds. Results from this investigation have shown that harvesting Jatropha fruits when they are yellow increases seed oil output by 6 to 9% as compared to harvesting the fruits on their final maturity stage (brown dry). Thus harvesting Jatropha seeds when they are yellow may increase feedstock (seed oil) availability in biodiesel production. The maximum oil content in Jatropha
seeds is attained at yellow maturity stage, and these are 30.1%, 30.6%, 26.2% and 27.9% for Jatropha seeds harvested from Thamaga, Mmadinare, Shashe and Maun areas, respectively. It is pertinent to mention that accumulation of seed oil in Jatropha seeds harvested from the aforementioned geographical locations follow a similar trend. Seed oil in Jatropha seeds increases continuously during fruit maturation and reaches peak level when the fruit turns yellow, thereafter it starts to decline until the final maturity stage (brown dry). The quality of both feedstock and biodiesel are of paramount importance, and Jatropha seed oil and derived biodiesel are no exception. Results from this investigation have revealed that fruit maturity have an impact on the quality of the seed oil hence the derived biodiesel. Fruit maturity influences some quality parameters of the seed oil. For instance, Free Fatty Acids (FFA) content in Jatropha seed oil varies with fruit maturity. Free fatty acid content in Jatropha seed oil increases continuously with seed maturity and this applies for all feedstock collected from all the geographical locations under investigation. These FFA content in Jatropha seed oil ranges from 0.2 to 0.7% for the four different fruit maturity stages, namely green yellow, yellow, yellow brown and brown dry. Seeds from
Mmadinare area (21.8811oS latitude, 27.7514oE longitude) recorded relatively highest FFA content from brown dry fruits (0.75%) whereas seeds from Thamaga area (24.72° S latitude, 25.53°
ii
E longitude) recorded relatively lowest FFA content (0.44%). Fatty acid composition of Jatropha seed oil also varies with fruit maturity. Fractional composition of unsaturated fatty acids, which makes up more than 70% of the total lipid, declines continuously with each consecutive maturity stage. As Jatropha fruits matures from green yellow to brown dry, the fractional composition of linoleic acid decrease by 8 to 9%. There is a logical relationship between the trend in fatty acid composition in Jatropha seed oil and seed oil content during fruit maturation. Based on this trend of unsaturated fatty acids in Jatropha seed oil, particularly linoleic and oleic acid, it can be concluded that reduction of seed oil content during seed desiccation stage (from yellow brown to brown dry) is a result of breakdown of some of the unsaturated fatty acids. The decline in fractional composition of unsaturated fatty acids in Jatropha seed oil during fruit maturation causes the cetane number of derived biodiesel to increase continuously with each successive maturity stage. The Peroxide Value (PV) of both Jatropha seed oil and derived biodiesel increase gradually and linearly with fruit maturity. The PV of seed oils from all the investigated geographical locations in Botswana (Mmadinare, Thamaga, Shashe and Maun) follow the same trend and in the same range. Effect of fruit maturity on other quality parameters such as cloud point, pour point, density, viscosity and calorific value (energy content) is minimal. Jatropha seeds from selected geographical locations in Botswana contain some levels of Phorbol Esters (PE) hence toxic. The PEs content vary with fruit maturity. Phorbol ester content in Jatropha seed oil ranges from 3.4 to 4.2mg/g whereas in seed cake ranges from 1.7 to 2.0mg/g during the four different fruit maturity stages. Jatropha seed oil and seed cake from yellow brown maturity stage are relatively the most toxic since they contain highest concentration of PEs.
A dissertation submitted to the Dept. of Industrial Design and Technology, Faculty of Engineering and Technology, University of Botswana in partial fulfillment of the requirement of the degree of Doctor of Philosophy in Engineering. Citation: Jonas, M. (2020) Effect of fruit maturity on yield and quality of seed oil and biodiesel of jatropha curcas found in Botswana, University of Botswana
2020-03-01T00:00:00ZCharacteristic influence of thermo-mechanical stresses leading to premature failure of compressor turbine blades of short-haul aircraft fleet
http://hdl.handle.net/10311/2399
Characteristic influence of thermo-mechanical stresses leading to premature failure of compressor turbine blades of short-haul aircraft fleet
Ngoret, Joshua Kimtai
Short-haul aircrafts play an integral role in air transport network, facilitating; passenger and cargo transport, security drills, ambulance services, disaster, wildlife and environment management, tourism amongst others. Unlike medium and long-hauls, these aircrafts are missioned to fly for under 3 hours and distances not exceeding 2000 km. As a result of short but, voluminous flight turnovers, changes in power settings, starts and stops; the compressor turbine (CT) blades of the engines are subjected to intense cyclic thermo-mechanical stresses.
Compressor turbine blades are specially profiled aerodynamic engine components specially designed to extract energy from high-temperature, high-pressure gases produced by the combustors. Due to severity of their operational environment, the CT blades degrade over time and often catastrophically fail without warning. In this regard, monitoring of CT blade life is crucial to ensure their proper health in service.
The current techniques employed to investigate the life of CT blades only inform of failure after exposure to service with scanty information on the numerous prematurely occurring failures. Consequently, accounting for CT blade life still poses a great challenge to air operators. This research therefore probed characteristic influence of thermo-mechanical stresses leading to premature failure of high pressure (HP), PT6A-114A engine CT blades from an assimilative approach. The prematurely retired HP, CT blades were collected from Vector Aerospace Kenya Limited after being in service for only 6378 creep-fatigue hours contrary to 10000 creep-fatigue hours preset by the manufacturer.
The CT blade was modeled for thermo-mechanical degradation in an environment that mimics the operational conditions to determine service life and resulting damage using commercial ANSYS tools version 15.0. A detailed microstructural and metallographic characterization was then performed using x-ray florescence (XRF), x-ray diffraction (XRD) and energy dispersive spectroscope-scanning electron microscopy (EDS-SEM) on the
protective coating and the substrate material. Mechanical testing was ultimately executed to ascertain the micro hardness and residual strength at time of retire from service.
The modeling results revealed that the tip of the CT blade had been rigorously attacked by exposure to heat as compared to the airfoil and the base. Notwithstanding this, it was noted that the CT blade could have served for another 1.44% more of the time it was in service, being exploited in the transient regime. The XRF results affirmed the existence of the bulk constituent elements that matched the manufacturers’ specification. The XRD analyses enabled positive identification of the resultant compounds which constituted the protective coating and the substrate material. The EDS-SEM results established that the protective coating of the tips was more attacked compared to the airfoils and the bases. As such, the substrate material degraded from evolution of creep and fatigue. The pores at the bases of the CT blades were found not influence distribution of uniform cuboidal phase at the bases in comparison the rafted tips and airfoils. This confirmed that degradation of the substrate material occurred as a result of creep and fatigue and not from manufacturing defects. Though micro hardness testing indicated that the material was still of high strength, continued safe service was not warrantied.
From this research, a robust assimilative approach was adopted for investigating life of CT blades enabling determination of instantaneous material status, magnitude of damage and remaining useful life (RUL). This work will assist air operators improve flight safety, enhance availability of aircrafts for operations while planning for maintenance will be made easier.
Premature failure of the CT blades can further be averted by; adhering to the engine’s operation limits, avoiding long and overexploitation of the engine and sticking to preset flight environments. In a move to improve heat, oxidation and corrosion resistance of the protective coating, inclusion of rare earth element such as yttrium, cesium and lanthanum would be noble. The substrate material could similarly be improved by addition of refractory elements such as ruthenium, iridium and rhenium in the composition of Inconel 713LC.
A dissertation submitted to the Dept. of Mechanical Engineering, Faculty of Engineering and Technology, University of Botswana in partial fulfillment of the requirement of the degree of Doctor of Philosophy in Engineering. Citation: Ngoret, J.K. (2019) Characteristic influence of thermo-mechanical stresses leading to premature failure of compressor turbine blades of short-haul aircraft fleet, University of Botswana.
2019-02-26T00:00:00ZThe effectiveness of management of lessons learned from Botswana Tourism Organisation (BTO) projects
http://hdl.handle.net/10311/2375
The effectiveness of management of lessons learned from Botswana Tourism Organisation (BTO) projects
Chika, Patience
Learning from past projects, be it to make the most of good practice or to avoid repetition of past mistakes, is one of the major success factors for continuous project accomplishment in organisations. Many researchers and project management practitioners underscore the need for organisations to effectively manage project learning, to ensure that organisations’ harvest lessons and apply them for the improvement of subsequent projects. That notwithstanding many organisations do not benefit from project learning, either because they do not have clear project learning processes in place, or the processes are not effectively implemented. Botswana Tourism Organisation (BTO) is one organisation that executes part of its mandate through the execution of construction projects in partnership with identified communities. This research embarked on assessing the effectiveness of the management of lessons learned by BTO for its construction projects. The research is a case study of five (5) projects that BTO has constructed since the organisation was established. The research was undertaken through a detailed review of the projects ‘documentation, distribution of questionnaires, follow-up interviews as well as focus group discussions with selected respondents. The results were analysed using various statistical, including rubric assessments, and non-statistical methods. The findings suggest that management of lessons learned for the projects is largely ineffective since some lessons learned processes i.e. capturing, storage and dissemination are minimally developed, while other processes i.e. analysis and infusion are virtually non-existent. Recommendations on key processes to be improved as well as key success factors for improvement have been put forth.
A dissertation submitted to the Dept. of Civil Engineering, Faculty of Engineering and Technology, University of Botswana in partial fulfillment of the requirement of the degree of Masters in Project Management. Citation: Chika, P. (2019) The effectiveness of management of lessons learned from Botswana Tourism Organisation (BTO) projects, University of Botswana.
2019-08-01T00:00:00Z