PhD Theses

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    Investigation of power dissipation in data selective flips flops triggered by octree clocking technique for low power buffer design
    (University of Dar es Salaam, 2019) Singh, Ngangbam Phalguni
    In the past few decades, studies have demonstrated that power dissipation in one of the key challenges ‘’in Information and Communication Technology (ICT) devices. The main factors are memory storage elements, the logic elements and the clocking technique. It leads to heating effect on the devices after prolonged usage. In such an application, flip flop with proper clocking system can be to design low power buffer, which can reduce the power dissipation. This thesis presents a qualitative research investigating the power dissipation in various data selective flip flops. A ring counter, with octree clocking system and Combinational Elements (C-Elements), is developed to control the clock signals triggering the flip flops and avoid unwanted switching activities during redundant events. Buffers are accessed in the form of ring counters, which control data transfer between chips in the computer internal circuits. The viability of the design is verified by the simulation using Very High-Speed Hardware Description Language (VHDL) programs with Altera’s Quartus II and Xilinx’s ISE. Analog current and transient analysis are done using Multisim 8 tools. Simulation results show that the deployed technique provides reduction on power dissipation by 44.08% and 14.20% with respect to fixed body biased and static Random Access Memory (SRAM) respectively. Simulation results also show that the designed buffer dissipates 1.655 nW in 2 stage and 0.666 mW in 64 bits. The improvement in 64 bit delay buffer Octree clocking technique with DDFF is 14.72%.
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    Language and history on Kilimanjaro, the pare mountains, and the Taita hills.
    (University of Dar es Salaam, 1977) Nurse, Derek
    This study attempts to trace the linguistic history of three communities in N.E. Tanzania and S.E. Kenya, the Chaga, the Pare, and the ‘Taita’. Chapter I introduces the languages concerned, describes the general background, and outlines aims and methods. Chapter II uses lexicostatistics methods to establish a classification for all the Bantu-speaking peoples of E. Africa, After discussing the methodology and some of its limitations, it sketches the results, which largely correspond to those achieved by the author and a former colleague at the University of Dar es Salaam. Having thus set the framework, it then looks in more detail at the positions of Chaga, Pare, and ‘Taita’ within that framework. Whereas the isolated position of Changa emerges relatively clearly from these statistical methods, Pare and ‘Taita are less easily dealt with. Taking Guthrie’s framework of Proto-Bantu consonants and vowels, Chapter III examines the phonological changes that have taken place between the hypothetical proto-language and the present. It tries to see generalities affecting many languages and language groups, and it also mentions minor development peculiar to individual languages. Changa and the main ‘Taita’ dialect, Saghala, and Pare, are felt to be outliers of a large linguistic grouping which covers E. Kenya and much of Tanzania. Chapter IV compares the structural elements involved in the verb systems of the three ‘languages’ and their neighbours. While recognizing that there are certain difficulties inherent in the us of these elements for historical purposes, the chapter comes to conclusion similar to those reached in Chapter III. Chapter V deals with the evidence afforded by loanwords for historical contact. ‘Loanword’ is defined, and the methodology described. It is likely that the Bantu-speaking inhabitants of Central and Eastern Kenya, and N.E. Tanzania have long interacted, and were preceded by, and perhaps until recently lived alongside, considerable numbers of non-Bantu speaking peoples. In Chapter VI the conclusions from the foregoing four chapters are assembled, and compared with the results of other linguists, and with the evidence from nonlinguistic sources.
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    Exports of manufactures from African countries: a study in economic development and the structure of industrial exports from selected African countries
    (University of Dar es Salaam, 1986) Mbogoro, Damas
    This study is about the relationship between the level of economic development and the structure of industrial exports from African countries. In the course of our study we test three sets of hypotheses on trade in manufactured goods. The first set of hypotheses refers to the heckscher-ohlin or the factor proportions theory of international trade. The second set of hypotheses refers to the Linder thesis which postulates that that domestic representative demand is the basis for trade in manufactured goods; and the third set of hypotheses deals with hirach’s postulates of trade between developing and industrial a countries. By way of background the study also addresses the issue of the level of industrial development in Africa in the 1970s. While import substitution industrialization was the dominant strategy, African countries also adopted export oriented and indigenous industrialization strategies. Within the industrial sector, the food, beverages, tobacco, textiles, clothing and leather products industries were the dominant industries. Their contribution towards the number of establishments, employment, gross output and domestic value added was more than fifty per cent in many countries. On average, industries in Africa in the 1970s were characterized by low domestic value added mainly because of a high level of imported raw material input content for the import substituting industries and a low level of local processing for the export oriented industries. The export oriented industrialization strategy which was based on the processing of the abundant natural resources (mainly minerals) was characterized by the use of physical capital intensive techniques, and therefore offered very limited prospects for solving the urban-centered unemployment problem. About 80 per cent of industrial exports from Africa in both 1975 and 1980 were agriculture and mineral related (Ricardo) goods mostly mineral related and physical capital intensive. We have argued that most industrial exports from Africa were physical capital intensive largely because the export oriented industrialization strategy was based on the exploitation of natural resources. Partly because of the presence of a large share of natural resources intensive industrial exports we have found a very weak relationship between the level of economic development and the structure of industrial exports from Africa in both 1975 and 1980.
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    An appraisal of physical education curriculum implementation: a Comparative Study of Public and Private Secondary Schools in Dar es Salaam Region
    (University of Dar es Salaam, 2007) Peter, Josephat
    The present study sought to compare implementation of Physical Education (PE) curriculum between public and private secondary schools in Dar es Salaam Region. Six secondary schools (three public and three private) were surveyed for the study. The sample included 361 students and 18 teachers. Employed data collection methods included questionnaires, interviews, checklist documentary review and observation. Research findings revealed that • PE is taught optional, optional-compulsory, compulsory-optional or not taught at all in both public and private secondary schools; • In both public and private secondary schools, there is inadequate provision of qualified PE teachers, equipment, facilities and PE books; • The allotted PE time in public schools was 40 minutes per period taught twice a week, while in private schools it was 35 minutes per period taught once in a week; and • The teaching of other subjects and remedial classes were found in conflict with the allotted PE periods in both public and private schools, something that led to moderate use of the allotted PE time for PE classes. In conclusion, the present study deduced that PE is a statutory requirement in secondary schools but its implementation varied between public and private schools and within them. In light of the findings from the study, it was recommended that the Ministry of Education and Vocational Training should emphasize and insist on the teaching of PE as a compulsory and examinable academic subject in all secondary schools. Moreover the Tanzania public, particularly policy makers, parents, and children, must be sensitized and made aware on the importance of PE programs.
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    Modeling a unified communications and integrated collaboration system in the health sector of developing countries: a case study of the health sector of Uganda
    (University of Dar es Salaam, 2016) Favor, Excellence
    Health sector service system is essentially intricate, multi-disciplinary and fragmented social systemcomprising of numerous contributors and clients responsible to deliver health services to patients in distinct areas. Customizing the needs of single patients intensifies the intricacy of the systems as the system finds their current model and applications or systems used to support it, inadequate to meet their requirements (delivery, access and costs). This intricacy incites decision makers to assess intermediations such as Unified Communication and Integrated Collaboration (UCIC) system to improve the effectiveness and competence of health sector servicesystem due to evolving behaviourthe potential intended and unintended consequences. System Dynamic approach was used to develop simulation models to anticipate the degree of competence of a UCIC system intermediations as well as its cost friendliness it brings to service system. Contributions of this research are the assessmentof the existing infrastructures of the health sector in terms of communications and collaboration aspects, the use of system dynamics method and the development of two models for assessing the integration of UCIC system and traffic analysis in the health sector service system. The assessment shows the benefits as improvement in the quality of health service delivery by 40.73% and degree of exploitation by 36.51% and reduction of costs by 23.2 %. The traffic analysis assessment indicates that as the disease burden increases the traffic increases. There were policysuggestions that will assist policymakers and decision makers make decision for the betterment of the health service system thus healthy population, increased productivity, then improved human development index. The UCIC system has been especially designed for wide-area telemedicine platform and for homecare services. It allows patients to be monitored with seamless flow of information no matter their locations, even in geographically dispersed and isolated areas, where normally there is no infrastructure capable of supporting similar services
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    Back off-free fragment retransmission scheme for energy efficient IEEE 802.11 wireless local area networks
    (University of Dar es Salaam, 2016) Mafole, Prosper
    In IEEE 802.11-based wireless local area networks (WLANs), channel induced errors and collisions cause transmission failures which waste bandwidth and energy. To improve the energy efficiency of IEEE 802.11 WLAN devices, schemes which mitigate the effects of collisions and channel induced errors have been proposed. Simulation models have been developed in ns-3.14 and were used to evaluate the effectiveness of the proposed schemes. The schemes were compared to classical fragmentation (CF) scheme and showed significant improvements. The simulation results were verified by mathematical analysis. Backoff-free fragment retransmission (BFFR) mitigates effects of errors occurring within a fragment burst by immediate retransmission of the affected fragments without channel contention. The reduction of contention overhead accounts for bandwidth and energy saving. BFFR with enhanced collision avoidance (BECA), attains collision-free transmission schedules by picking a deterministic number of backoff slots when all fragments of a frame are successfully acknowledged. BFFR outperformed CF in energy efficiency by 31%, 10% and 15% for fragments of 250, 500 and 750 bytes respectively. Optimized BFFR (BFFR-4), outperformed BFFR in energy efficiency by 29%, 38% and 25% for the same respective fragment sizes while it outperfomed CF by 52%, 44% and 36% for the respective fragment sizes. BECA outperformed BFFR by reducing fragment retransmision rate from 8.2%, 18.3% and 27.3% to 6.6%, 15.9% and 24.5% for fragments of 250, 500 and 750 bytes respectively. BFFR and BECA are better candidates than CF for multimedia applications when STAs are either fixed or mobile. The schemes can be used in scenarios of mixed traffic consisting of multimedia applications, Web traffic, email and file transfer and improve network performance currently achieved by CF when either TCP, UDP or both protocols are used in a network of different sizes.
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    Development of e-learning content and delivery for self-learning environment case of selected rural secondary school in Tanzania
    (University of Dar es Salaam, 2011) Lujara, Suzan Kwegyir
    The effective use of Information and Communications Technology (ICT) in developing countries like Tanzania is crucial in order to overcome the challenges that are faced countrywide in many sectors, to reduce the digital divide and improve the economy. ICT is becoming more and more integrated in societies worldwide. its elects are clearly seen in people's lives as well as on countries' economy as it opens doors for new opportunities and change the attitude of people towards learning. Secondary schools in Tanzania are facing many problems which hamper students' learning. This in tum affects their performance in the National examinations hence reducing the growth of a learned society. This research specifically addresses the problem of lack of learning and teaching materials by using ICT tools for the development and delivery of e-Learning content. The research focused on two secondary schools, name]y, the Wali-Ul-Asr Seminary and Kibaha Secondary School as pilot schools in Kibaha district Pwani region. The research used courseware engineering methodology which integrated instructional design and software engineering. The research was also inspired by the concepts of participatory action research, Mode 2 knowledge production and triple helix, which incorporated stakeholders' participation throughout the research. The main stakeholders are students, teachers, and head teachers at secondary schools level, Ministry of Education and Vocational Training officials and researchers. This is an applied type of research addressing a practical problem in society. The outcome is a pilot package of e-Learning material comprised of sample chapters of Mathematics form 111 for the pilot site. Blended mode of delivery has been considered using Compact Disc/Digital Versatile Disc Read Only Memory, the Tanzania Secondary Schools e-Learning (TanSSe-L) System which is a customized Moodle platform and by using face to face learning.
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    The state, cultural significance and management of built heritage assets of Lindi and Mtwara regions, Tanzania
    (University of Dar es Salaam, 2012) Bwinabona, Elgidius Ichumbaki
    Tanzania possesses heritage assets spanning from Pliocene to present which should be conserved for both present and future generations. To assume their sustainability, Tanzania made legislations and policies and established institutions and departments. Despite such efforts, the majority of assets continue to get lost and some at an alarming rate. To address this issue, a study on the state, cultural significance and management of built heritage assets of Lindi and Mtwara regions was done. The study’s purposes were; to survey, identify and document built heritage assets, to assess their cultural significance and explore conservation and management challenges and strategies. To achieve this, both ethnographic inquiries and physical surveys were employed to collect data. Twenty one built heritage assets were identified, surveyed and documented. The assets’ cultural significances were also assessed. Documented assets date to between 10th and 20th centuries. These assets do explain various historic situations; existence of trade contact among Indian Ocean inhabitants, the colonial administrative systems of the 19th and 20th centuries and technological development during pre-colonial and colonial periods. Despite providing such important information, about 75% of these built heritage assets are in a dilapidated state. Numerous factors; both physical and anthropogenic contribute to this situation. To arrest the loss of these assets, the study recommends efforts to survey, identify, document, gazette and conserve potential built heritage assets. Also, this work recommends raising public awareness, improving collaboration among heritage stakeholders as well as adhering and integrating heritages’ policies, legislations and institutional frameworks.