Faculty of Engeneering and The Built Environment

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    ANALYSIS OF TRENDS AND VOLATILITY OF CRYPTOCURRENCIES IN THE GLOBAL MARKET
    (Technical University of Kenya, 2023-06-01) KHAMILA, DOUGLAS
    The motivation of this study was to analyze trends, volatility and model identification for Bitcoin, Ethereum and Ripple cryptocurrencies in the global market. The study utilized weekly price and cryptocurrency trading datasets from https://coinmarketcap.com. The study period was from 1st February 2015 to 26th December 2021. Two models, Arima and Garch models have been used in the study to determine the trends and volatility in the global market, trends have shown that cryptocurrencies have continued to increase in the market creating a worrying trends of overrunning both the domestic and international currencies, cryptocurrencies have remained unregulated in domestic markets and even in global markets, this have made it difficult to establish the value of digital assets held by mostly the tech-savvy individuals amounting to billions that have affected the markets both locally and internationally. Model identification was also determined using akaike information criterion values, the models that reported the least akaike information criterion values were considered to be the best models. On volatility, the results revealed that cryptocurrencies prices varied with time positively, which means traders looking to capitalize on volatility for profits may use such indicators as a strength indexes, volumes and establish support and resistance levels. The results from this study are important for market stability, investment and risk management purposes
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    A COMPARATIVE STUDY OF PENCIL BEAM AND COLLAPSED CONE CONVOLUTION DOSE CALCULATION ALGORITHMS IN PELVIC AND THORACIC TREATMENT PLANS
    (2023-11-01) Dina, Moraa
    Different algorithms used to calculate doses in radiotherapy planning adopt different techniques in simulating doses received by the target (tumor) volume. Such differences can come about in terms of dose distribution in the target volume and doses received by surrounding organs. Due to such differences, it is necessary to take into consideration the best algorithm suitable for a range of mediums i.e homogeneous and heterogeneous mediums. The differences in the way different algorithms simulate doses in different media may bring about dosimetric variations which can relatively affect treatment outcomes in 3D-conformal radiotherapy. The primary focus of this research was to compare dose variations for two dose calculations algorithms namely, Pencil Beam (PB) algorithm and the Collapsed Cone Convolution (CCC) in highly and less heterogeneous mediums. The study was an analytical retrospective study consisting of 8 pelvic and 7 thoracic treatment plans approved and scheduled to undergo 3D- CRT. The treatment plans were generated using PB and the same treatment plans recalculated using the CCC calculation algorithm. Dosimetric variations between the two dose calculation algorithms were observed and evaluated based on variations in plan parameters such as dose received by the tumor volume and the dose received by critical organs (OAR’s). Minimum and Maximum mean dose values were obtained from PTV and OAR’s from the two dose calculation algorithms. Differences in dose values between the two algorithms were analyzed using standard errors (SE) to determine if in fact the differences were significant. At a CI of 95% (P=0.05), it was found out that the two calculation algorithms demonstrated insignificant dose differences to a treatment plan. PB algorithm demonstrated high dose received to the tumor volume compared to the CCC algorithm. A visual analysis of the results using box plots demonstrated that the two algorithms showed no major differences in doses received by the PTV and OAR’s. It made no significant difference to a treatment plan if the planner (Medical Physicist) would adopt either of the algorithms in calculating doses for cervix or esophagus treatment plans using ONCENTRA Treatment Planning System
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    DETERMINING TRANSIT DOSE FOR THE BEBIG SAGINOVA® HDR Ir-192 STEPPING SOURCE BRACHYTHERAPY UNIT
    (Technical University of Kenya, 2023-11-01) MURIITHI, MILLICENT
    The Bebig SagiNova® HDR brachytherapy treatment unit implements the TG-43 formalism in calculating radiation dose, which does not account for transit doses during treatment. It is unclear how significant the transit dose is and depending on its magnitude, it may impact the clinical outcome. The goal of this study is to determine the transit dose component for the Bebig SagiNova® HDR brachytherapy unit with an Ir-192 stepping source. The well-type chamber measurement technique was used to measure charge collected as the Ir 192 source moved from the afterloader. The charge measurements were collected for different source configurations and analyzed using two techniques; the multiple exposure method and the graphical method to determine effective transit time. The overall effective transit time was quantified as the source moved to its first dwell position (entry time), between activated dwell points (interdwell time) and during retraction out of the applicator back into the afterloader (exit time). The effective transit time of 2.02s was obtained with the multiple exposure method as well as the graphical solution method. The effective transit time was not influenced by the analysis technique. The overall effective transit time for the unit was determined to be about 13.80s and 13.99s using the multiple exposure method and the graphical solution respectively. The significance of the amount of dose during transit is not clear, as it depends on the activity and configuration of the source, prescribed dose and the quantity of treatment fractions used. It is necessary to determine and document transit time and doses for assessing their significance on the delivered dose to help improve the overall efficiency of brachytherapy and patient care
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    ETERMINATION OF THE COUCH TRANSMISSION FACTOR AND ITS INCORPORATION IN TREATMENT PLANNING SYSTEM
    (2023-11-01) Chanzu, Ian
    Treatment couch is an equipment used in the treatment of cancer patients. It is used to give comfort and support during treatment. This ensures good treatment outcome as the patient will be intact thereby maximizing the dose to the target while minimizing the dose to surrounding organs. In order to improve tumour dose coverage, more radiation beams are placed to come from different angles, others penetrating the couch before reaching the target. The treatment couch is made of carbon fibre thus making it radiotranslucence especially for the radiation beams penetrating through it before reaching the target. Research previously done, shows that the treatment couch causes poor dose distribution resulting to underdose. To solve this problem, the treatment Couch Transmission Factor (CTF) needs to be included in the Treatment Planning System (TPS) in order to compensate for the dose absorbed by the couch. This study investigated the CTF of the iBEAM evo treatment couch and virtual TPS couch model, and its incorporation in the Oncentra TPS. The study was carried out in three phases using a cylindrical CTDI phantom, ion chamber and a TPS generated virtual square phantom. Phases 1 and 2 gave an equal mean CTF of 1.00 for 6MV and 15MV while phase 3 gave a mean CTF of 0.97 for 6MV and 0.98 for 15MV. The highest deviations recorded between CTF values in phase 1 and phase 3 were at GAP 11 (-9.03%) for 6MV photon energy and GAP 4 (-4.96%) and GAP 11(-6.65%) for 15MV photon energy. The highest deviations recorded between CTF values in phase 2 and phase 3 were at 11 (-9.53%) for 6MV photon energies and 11 (-6.85%) for 15MV photon energy. The implication of these results was seen on the dose deviations between phases 1, 2 and phase 3 if the plans in the TPS could have been delivered. The highest recorded underdose was 12.71 monitor units in phase 2 at GAP 11(213.8°) and 10.63 monitor units in phase 1 at GAP 11 (213.8°) for 6MV, 7.02 monitor units in phase 1 and 7.97 monitor units in phase 2 for 15MV at GAP 11(213.8°). In conclusion, from this research done, the CTF is not incorporated in the TPS. However, further studies are recommended of the same when the CT couch attached on the CTDI scanned image is included in the external or body contour
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    An evaluation of the cadastral system in Kenya And a strategy for its modernization
    (2013) Wayumba, Gordon
    ABSTRACT - ': ,ladasfral system in Kenya was established in 1903 to support land alienation for the white .- ::s who had come into the country in the early part of the 20th Century. In the last hundred :--s. th€ system has remained more or less the same, where land records are kept in paper : .:r and majority of operations are carried out on a manual basis. The lack of a modern . .:-ral system has contributed to problems in land adminishation in the country. --= ,Jovernment has expressed the need to modernize the cadastral system in order to facilitate : . --r land administration, support the development of an integrated Land Information t:".:qement System and a National Spatial Data Infrastructure. However, one persistent : . - - ninator to these efforts has been the lack of strategies for such modernization. -" ! srudy set out to contribute to the solution of this problem through the following objectives; ; : -3tion of the current cadastral system in Kenya, identification and analysis of appropriate '--:,,.logies and strategies for modernization of the cadastral system in Keny4 and testing of ' = ; -:rability of the identified technologies and strategies in the cadastral system. ' : \lethods adopted included; administration of standard questionnaires to selected -. .:...lders, personal interviews, field observations and review of existing literature on cadastre" -' = rolder involvement in the study consisted of private and public sector Land Surveyors, - .3rs. Valuers, members of Co-operative organizations, and general users of cadastral ::-ation. ; :...lv also carried out field measurements with selected geospatial technologies in selected - s:res to assess their suitability in cadastral mapping and modelling. These technologies . - --l: Global Positioning System, high spatial resolution satellite imagery, and Geographical -,:tion System. Further work involved the development and testing a new cadastral model ' - : - n the Multi-Value Vector Maps approach and Smiths Normalization procedures. - ' : --lir results from the research are that; the administrative structure is bureaucratic, complex - - : . .:hly cenftalized; the cadastral processes are equally complex, duplicative and slow; and all : :Si€d technologies were found suitable for cadastral mapping and modelling, however, the : i ::;hrology lacks proper guidelines for application and calibration bases. :r:S of cadastral modelling, it was found that Smiths Normalization and Functional ;-r-r1c! Diagrams automatically produce fully Normalized Tables and successfully query . - .:iay of multi-parcel ownerships. The study also found out that a hyghbrid of Object- i: -' ,:.al database management system is better-suitable for the development of GlS-based , - - -,.::l databases than typical Relational or Object-Oriented models on their own. ' ': ::-Jy concludes that the main problem with the cadastral system in Kenya is lack of - - : --.-rtzation and decentralization, and therefore recommends for a complete decentralization -. :Jministrative system and implementation of a comprehensive computerization possibly - :he der.elopment of a Land Information System.
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    MODELING SOLUTE DYNAMICS IN AQUIFERS: CASE STUDY OF IRON DISPERSION IN CHYULU AQUIFER, KENYA
    (Technical University of Kenya, 2022-11) NG’ANG’A, STANLEY KIBE
    Chyulu in Makueni County falls in the Arid and Semi-Arid Lands (ASAL) parts of southeastern Kenya. The main source of water is boreholes whose water is mostly saline, harmful to human health and environment and sometimes fail to produce enough water to justify the high cost of drilling. Availability of both the groundwater potential and water quality index (WQI) maps would be paramount. Water quality parameters such as pH, turbidity, iron, fluoride, electrical conductivity, total dissolved solids, were used in assessment of the impact of stratum geochemistry on the groundwater quality. The results showed water whose parameters far exceeded the upper limits as per World Health Organization (WHO) standards. The negative impact of iron to storage and plumbing facilities was notable with tanks leaking by the third year of use due to corrosion and therefore reduction of iron using appropriate technology in the water would be a notable improvement of water quality. These parameters included iron, fluoride and nitrates among others and to understand their behavior in the aquifer/stratum, groundwater models are used. These models require modification to suite particular parameter because different ions react differently in the stratum. This study sought to develop tools for solute characterization that address strata like the Chyulu aquifer one that have excess iron among other salts. The study mapped groundwater in terms of quantity using drainage, rainfall, aspect, slope, topography, impact of the vadoze zone, and conductivity of the aquifer as inputs in (DRASTIC) modeling which utilizes both GIS and remote sensing techniques. The groundwater quality index (WQI) and quality map was also developed using the corresponding parameters’ concentrations. The study also tested a non-motorized aeration/filtration process using a fabricated unit that was used for aeration of feed water and its filtration. A user-defined Reactive Three–Dimensional Multi-Species Transport (RT3D) sub-routine that was linked to the Groundwater Modeling System (GMS) software that depicted the oxygenation of ferrous iron (II) at neutral pH was developed and tested using the non-motorized aeration filtration unit that now acted as batch reactor to predict chemical reactions in the aquifer. To validate the user-defined RT3D subroutine ferrous and ferric ions were measured every six months from June 2016 to December 2019. These test results were compared with those that were obtained from GMS/RT3D model after the subroutine had been linked to GMS software. This study concludes that the main consideration in deciding the site of a borehole in the study area be water quality because only 10% of the whole study area had portable water while 91 % of the area has either high or moderate groundwater potential. The non-motorized aeration/filtration system reduced the iron in groundwater by 58.3% and therefore this oxygenation process improves water quality. The other conclusion is that the User-defined RT3D subroutine predicted the iron flow through the stratum very accurately because the coefficient of correlation for ferrous ions was 0.8 while that for ferric ions was 0.82 which meant that the proposed subroutine as linked to the GMS model can be used to predict the solute (ferrous and ferric ions) in the Chyulu stratum/aquifer at Makindu. This study recommends that this user-defined model be tested and calibrated for use in other aquifers and that the model be tailor made/adopted to investigate the flow of calcium and its derivatives in aquifers.
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    MONITORING OF TREE SPECIES USING OBJECT BASED TIME SERIES ANALYSIS: -A CASE STUDY OF ACACIA XANTHOPHLOEA SPP IN LAKE NAKURU NATIONAL PARK, KENYA
    (Technical University of Kenya, 2023-08) OSIO, ANNE ACHIENG
    ABSTRACT The significance of wetlands as suppliers of ecosystem services to flora and wildlife in conservation zones is examined in this study. Acacia xanthophloea trees in Kenya's Lake Nakuru National Park are the subject of particular attention since they are in danger of going extinct as a result of repeated floods. This study attempts to detect and quantify the damage to the trees over time in order to comprehend the rate of their deterioration in order to address this issue. To identify and categorize Acacia xanthophloea trees in the Lake Nakuru riparian reserve, the study used an object-based image approach to determine the most efficient model for this task, a variety of spaceborne and aerial sensing technologies were used, including multi-temporal and multi-spatial. The overall goal of the study was to quantify Acacia xanthophloea and related plant species in terms of spectral, spatial, and contextual features in order to determine their degree of deterioration in both space and time. The study shows that the OBIA-Random Forest model and particular training techniques successfully and accurately identified Acacia xanthophloea trees. To identify riparian vegetation before and after floods, various algorithms were used, revealing changes in vegetation coverage brought on by flooding. The health and changes in vegetation degradation were monitored over time using NDVI (Normalized Difference Vegetation Index) maps. Classification of non-degraded forests, degraded forests, and submerged degraded forests was done using temporal profiles based on Landsat time series. The study also tested a variety of data processing methods, including the use of CNN frameworks on datasets based on UAVs and high-resolution Pleiades-1A images. The findings indicated alterations in Acacia xanthophloea coverage throughout various time periods and places, pointing to both gains and losses in tree populations. The importance of wetlands and Acacia xanthophloea trees in providing ecosystem services is highlighted by this study's findings. The study used a range of remote sensing tools and analysis techniques to identify, measure, and monitor the damage done to these trees over time. The results have consequences for conservation initiatives and offer guidance for managing and preserving biodiversity in ecosystems with similar wetlands. In order to stop the extinction of Acacia xanthophloea trees and improve general conservation practices, the technique chosen, incorporating the OBIA approach, provides a useful tool for swift response and management plans.
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    Towards effective self-help housing delivery: Contributions through network analysis in Nairobi,Kenya and Johannesburg,South Africa
    (2006) Omenya, Alfred Odhiambo
    This thesis deals with self-help housing networks in Nairobi, Kenya and Johannesburg, South Africa. It starts bydiscussing some of the current manifestations and challenges of self-help housing in the two contexts. It locates these against neo-liberal development paradigms in Kenya and South Africa. It reviews some of the main theories and concepts that have been applied to understand self-help housing, arguing that there are many issues that these lenses fail to explain. Amongst these are the relationships amongst actors and the ways resources are exchanged in self-help housing. The thesis discusses some of the key resources used for self-help housing in Nairobi and Johannesburg, namely: land, finance, labour, materials and technology, and infrastructure and services. It develops a case for network analysis of these resources and actors in self-help housing. The second part of the thesis is dedicated to analysis of self-help housing networks in Nairobi and Johannesburg, based on empirical data. The three categories of networks analysed are: individual-based ego-centric networks; group-based networks of collective action; and content-of-ties-based networks of exchange. The study compares self-help housing networks in Nairobi and Johannesburg. On one hand, lack of the state intervention in Kenya has resulted in self-help housing in Nairobi being accessed almost exclusively through networks. On the other hand, state intervention in South Africa has resulted in weakening of ties within local groups and domination of state/market hierarchies in access to various self-help housing resources in Johannesburg. The major conclusion from this study is that, in both cities, networks remain a viable third way of provision of housing, in addition to (not instead of) housing production through state/market hierarchies and decentralised models. Networks tend to overcome lack of inclusion dominant in state/market hierarchies and lack of capacity, endemic in decentralised models. In terms of analysis, the study shows that network theories are relevant to understanding the operations of actors and access to resources in low-income housing, complementing sector-based understanding, which remains dominant in analysis of low-income housing today.